Photolysis of pure solid O{sub 3} and O{sub 2} films at 193 nm

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

Raut, U.; Loeffler, M. J.; Fama, M.

2011-05-21

We studied quantitatively the photochemistry of solid O{sub 3} and O{sub 2} films at 193 nm and 22 K with infrared spectroscopy and microgravimetry. Photolysis of pure ozone destroyed O{sub 3}, but a small amount of ozone remained in the film at high fluence. Photolysis of pure O{sub 2} produced O{sub 3} in an amount that increased with photon fluence to a stationary level. For both O{sub 2} and O{sub 3} films, the O{sub 3}:O{sub 2} ratio at large fluences is {approx}0.07, about two orders of magnitude larger than those obtained in gas phase photolysis. This enhancement is attributed tomore » the increased photodissociation of O{sub 2} due to photoabsorption by O{sub 2} dimers, a process significant at solid-state densities. We obtain initial quantum yield for ozone synthesis from solid oxygen, {Phi}(O{sub 3}) = 0.24 {+-} 0.06, and quantum yields for destruction of O{sub 3} and O{sub 2} in their parent solids, {Phi}(-O{sub 3}) = 1.0 {+-} 0.2 and {Phi}(-O{sub 2}) = 0.36 {+-} 0.1. Combined with known photoabsorption cross sections, we estimate probabilities for geminate recombination of 0.5 {+-} 0.1 for O{sub 3} fragments and 0.88 {+-} 0.03 for oxygen atoms from O{sub 2} dissociation. Using a single parameter kinetic model, we deduce the ratio of reaction cross sections for an O atom with O{sub 2} vs. O{sub 3} to be 0.1-0.2. The general good agreement of the model with the data suggests the validity of the central assumption of efficient energy and spin relaxation of photofragments in the solid prior to their reactions with other species.« less

Inhibition and acclimation of C(3) photosynthesis to moderate heat: a perspective from thermally contrasting genotypes of Acer rubrum (red maple).

PubMed

Weston, David J; Bauerle, William L

2007-08-01

Effects of moderate heat on growth and photosynthesis were investigated in two clonal genotypes of Acer rubrum L., originally collected from the thermally contrasting habitats of Florida and Minnesota, USA, and known in the horticultural trade for sensitivity and insensitivity to heat, respectively. Under both common garden and warm greenhouse conditions (day/night temperature of 33/25 degrees C), the Florida genotype exhibited more growth than the Minnesota genotype. To determine the physiological parameters associated with this response, plants were acclimated to ambient (27/25 degrees C) or moderately elevated (33/25 degrees C) temperatures for 21 days before measurement of net photosynthesis at temperatures ranging from 25 to 48 degrees C. In vivo measurements of gas exchange and chlorophyll a fluorescence of ambient-acclimated plants revealed that, compared with the Minnesota genotype, the Florida genotype maintained a higher photosynthetic rate, higher stomatal conductance, more open PSII reaction centers, a greater PSII quantum yield and a lower quantum requirement for photosystem II (phi(PSII)) per mole of CO(2) fixed (phi(CO(2) )) throughout the measurement temperature range. When both genotypes were acclimated at 33/25 degrees C and measured at 33 degrees C, analysis of the response of net photosynthesis to calculated intercellular CO(2) concentration indicated that the maximal rate of Rubisco carboxylation (V(cmax)) decreased more in the Minnesota genotype than in the Florida genotype in response to elevated temperature. Additionally, phi(PSII)/phi(CO(2) ) at 33 degrees C was markedly higher for Minnesota plants under photorespiratory conditions, but similar to Florida plants under non-photorespiratory conditions. The results indicate that the higher net photosynthetic rate at 33/25 degrees C of the Florida genotype compared with the Minnesota genotype could be a result of several mechanisms, including the maintenance of a higher V(cmax )and a more efficient quantum requirement of PSII per mole of CO(2) fixed, which is likely the result of lower photorespiration.

The Contradiction Between the Measurement Theory of Quantum Mechanics and the Theory that the Velocity of Any Particle Can Not be Larger than the Velocity of Light

NASA Technical Reports Server (NTRS)

Shen, Y.; Shen, Z. J.; Shen, G. T.; Yang, B. C.

1996-01-01

By the measurement theory of quantum mechanics and the method of Fourier transform,we proved that the wave function psi(x,y,z,t)= (8/((2(pi)(2L(exp (1/2)))(exp 3))(Phi(L,t,x)Phi(L,t,y)Phi(L,t,z)). According to the theory that the velocity of any particle can not be larger than the velocity of light and the Born interpretation, when absolute value of delta greater than (ct+ L),Phi(L,t,delta) = 0. But according to the calculation, we proved that for some delta, even if absolute value of delta is greater than (ct+L), Phi(L,t,delta) is not equal to 0.

Prospects for studying penguin decays in LHCb experiments

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

Barsuk, S. Ya.; Pakhlova, G. V., E-mail: Galina.Pakhlova@cern.ch; Belyaev, I. M.

2006-04-15

Investigation of loop penguin decays of beauty hadrons seems promising in testing the predictions of the Standard Model of electroweak and strong interactions and in seeking new phenomena beyond the Standard Model. The possibility of studying the radiative penguin decays B{sup 0} {sup {yields}} K*{sup 0}{gamma}, B{sup 0}{sub s} {sup {yields}} {phi}{gamma}, and B{sup 0} {sup {yields}} {omega}{gamma} and the gluonic penguin decays B{sup 0} {sup {yields}} {phi}K{sup 0}{sub S} and B{sup 0}{sub s} {sup {yields}} {phi}{phi} in LHCb experiments is discussed.

Physiological functions of the water-water cycle (Mehler reaction) and the cyclic electron flow around PSI in rice leaves.

PubMed

Makino, Amane; Miyake, Chikahiro; Yokota, Akiho

2002-09-01

Changes in chlorophyll fluorescence, P700(+)-absorbance and gas exchange during the induction phase and steady state of photosynthesis were simultaneously examined in rice (Oryza sativa L.), including the rbcS antisense plants. The quantum yield of photosystem II (PhiPSII) increased more rapidly than CO(2) assimilation in 20% O(2). This rapid increase in PhiPSII resulted from the electron flux through the water-water cycle (WWC) because of its dependency on O(2). The electron flux of WWC reached a maximum just after illumination, and rapidly generated non-photochemical quenching (NPQ). With increasing CO(2) assimilation, the electron flux of WWC and NPQ decreased. In 2% O(2), WWC scarcely operated and PhiPSI was always higher than PhiPSII. This suggested that cyclic electron flow around PSI resulted in the formation of NPQ, which remained at higher levels in 2% O(2). The electron flux of WWC in the rbcS antisense plants was lower, but these plants always showed a higher NPQ. This was also caused by the operation of the cyclic electron flow around PSI because of a higher ratio of PhiPSI/PhiPSII, irrespective of O(2) concentration. The results indicate that WWC functions as a starter of photosynthesis by generating DeltapH across thylakoid membranes for NPQ formation, supplying ATP for carbon assimilation. However, WWC does not act to maintain a high NPQ, and PhiPSII is down-regulated by DeltapH generated via the cyclic electron flow around PSI.

[Photooxidation of P700 in photosystem 1 preparations with various amounts of antenna chlorophyll a].

PubMed

Il'ina, M D; Borisov, A Iu

1982-12-01

A number of membrane fragments and pigment-protein complexes of photosystem 1 was obtained from pea chloroplasts, using ionic and non-ionic detergents (SDS, digitonin, Triton X-100, lauryldimethylamine-N-oxide). The ratio of chlorophyll (Chl) a to P700 varied from 220 to 30. For non-dialyzed preparations the quantum yield of P700 photooxidation (phi e) measured by the initial rate of photobleaching at 696-698 nm with excitation at the Soret band of Chla was equal to 40-60%. When the P700 photooxidation was measured at 432 nm, the phi e value showed a further decrease to 20-40% during red light excitation over the range of 660-680 nm but rose to 70-90% at the exciting light wavelengths of greater than or equal to 695 nm. On the basis of the observed dependences the red absorption band was approximated by a sum of two spectra: the spectrum of Chla photoactive in P700 photooxidation and that of photoinactive Chla. Both spectra had maxima near the absorption peak of the object. The photoinactive fraction was additionally enriched by the long-wavelength absorption forms of Chla with an absorption maximum over the range of 684-690 nm. The amount of the bulk Chla in the photoinactive fraction was no less than 40%. The phi e value for freshly dialyzed preparation at a Chla/P700 ratio of 30 was equal to 50-60% independent of the exciting light wavelength. An addition of 0.05% Triton X-100 to this preparation caused: i) a blue shift of the absorption and fluorescence maxima; ii) a decrease of the long-wavelength absorption forms content of Chla and, iii) a considerable increase in fluorescence lifetime and quantum yield due to deaggregation of Chla and its solubilization by detergent micelles. The same phenomenon seems to be responsible for the formation of photoinactive fraction of a pigment, since after addition of a detergent the above-mentioned spectral dependence of phi e appeared, i.e. phi e showed a 3-fold decrease (down to 18%) within the region of 660-680 nm and a 1,6-fold increase (up to 90%) at 705-730 nm. These results suggest that the detergents destroy the intact construction of a light-harvesting antenna rather than that of the photosystem 1 reaction center.

Study of {chi}{sub cj} Decays at BES III

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

Zhong, J.

2010-08-05

In spring 2009 BES III has taken its first large data sample on the {psi}(2S) resonance. More than 1{center_dot}10{sup 8} {psi}(2S) decays have been recorded. First results on the analyses {chi}{sub cJ{yields}{pi}}{sup 0{pi}0}, {chi}{sub cj{yields}{eta}{eta}} and {chi}{sub cj{yields}{phi}{phi}} are presented. The decay mode {chi}{sub c1{yields}{phi}{phi}} has been observed for the first time. The results presented in this document are preliminary.

Warm inflationary model in loop quantum cosmology

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

Herrera, Ramon

A warm inflationary universe model in loop quantum cosmology is studied. In general we discuss the condition of inflation in this framework. By using a chaotic potential, V({phi}){proportional_to}{phi}{sup 2}, we develop a model where the dissipation coefficient {Gamma}={Gamma}{sub 0}=constant. We use recent astronomical observations for constraining the parameters appearing in our model.

Synthesis of Substituted 2,3,5,6-tetraarylbenzo(1,2-b:5,4-b')difurans

NASA Technical Reports Server (NTRS)

Abdul-Aziz, Mahmoud; Auping, Judith V.; Meador, Michael A.

1995-01-01

A series of substituted 2,3,5,6-tetraarylbenzo(l,2-b:5,4-b')difurans 1 was synthesized. This synthesis is based upon the photocyclization of 2,5-dibenzoylresorcinol dibenzyl ethers to the corresponding tetrahydrobenzo(1,2-b:5,4-b')difurans. Treatment of the photoproducts with methanesulfonyl chloride in pyridine afforded 1 in overall yields ranging from 30-72%. A number of these compounds have high fluorescence quantum yields (of phi(sub f) = 0.76-0.90), and their fluorescence spectra exhibit large solvatochromic shifts. These compounds may be suitable for use as fluorescent probes.

Quantum corrections to quasi-periodic solution of Sine-Gordon model and periodic solution of phi4 model

NASA Astrophysics Data System (ADS)

Kwiatkowski, G.; Leble, S.

2014-03-01

Analytical form of quantum corrections to quasi-periodic solution of Sine-Gordon model and periodic solution of phi4 model is obtained through zeta function regularisation with account of all rest variables of a d-dimensional theory. Qualitative dependence of quantum corrections on parameters of the classical systems is also evaluated for a much broader class of potentials u(x) = b2f(bx) + C with b and C as arbitrary real constants.

George E Valley Prize Talk: Measurements of phi-meson production and the observation of antihypertriton in Au+Au collisions at RHIC

NASA Astrophysics Data System (ADS)

Chen, Jinhui

2013-04-01

Collisions of heavy nuclei at the Relativistic Heavy-Ion Collider (RHIC) at Brookhaven National Laboratory (BNL) briefly produce hot and dense matter that has been interpreted as a quark gluon plasma (QGP) . The energy density of the plasma is similar to that of the universe a few microseconds after the Big Bang. This plasma contains roughly equal numbers of quarks and antiquarks. As a result of the high energy density of the QGP phase, many strange-antistrange quark pairs are liberated from the quantum vacuum. The plasma cools and transitions into a hadron gas, producing nucleons, hyperons, mesons, and their antiparticles. The phi-mesons are ideal experimental probe to explore the QGP evolution dynamics. They are predicted to have relatively small hadronic interaction cross sections. Thus those phi-mesons carry the information directly from the hadronization stage with little or no distortion due to hadronic rescattering. In this talk, I will present the phi-meson production in Au+Au collisions at center-of-mass energy of 200GeV. Energy and system size dependence of the phi yields at mid-rapidity will be discussed. Centrality and transverse momentum dependence of the phi elliptic flow and nuclear modification factor will be presented. Properties of strange quarks in the bulk matter at hadron formation will be discussed. I will also present the details of the antihypertriton observation from the STAR experiment. Physics implication related to the QGP formation and hyperon-nucleon interaction from the data will be discussed.

Surface Wave Propagation on a Laterally Heterogeneous Earth

NASA Astrophysics Data System (ADS)

Tromp, Jeroen

1992-01-01

Love and Rayleigh waves propagating on the surface of the Earth exhibit path, phase and amplitude anomalies as a result of the lateral heterogeneity of the mantle. In the JWKB approximation, these anomalies can be determined by tracing surface wave trajectories, and calculating phase and amplitude anomalies along them. A time- or frequency -domain JWKB analysis yields local eigenfunctions, local dispersion relations, and conservation laws for the surface wave energy. The local dispersion relations determine the surface wave trajectories, and the energy equations determine the surface wave amplitudes. On an anisotrophic Earth model the local dispersion relation and the local vertical eigenfunctions depend explicitly on the direction of the local wavevector. Apart from the usual dynamical phase, which is the integral of the local wavevector along a raypath, there is an additional variation is phase. This additional phase, which is an analogue of the Berry phase in adiabatic quantum mechanics, vanishes in a waveguide with a local vertical two-fold symmetry axis or a local horizontal mirror plane. JWKB theory breaks down in the vicinity of caustics, where neighboring rays merge and the surface wave amplitude diverges. Based upon a potential representation of the surface wave field, a uniformly valid Maslov theory can be obtained. Surface wave trajectories are determined by a system of four ordinary differential equations which define a three-dimensional manifold in four-dimensional phase space (theta,phi,k_theta,k _phi), where theta is colatitude, phi is longitude, and k_theta and k _phi are the covariant components of the wavevector. There are no caustics in phase space; it is only when the rays in phase space are projected onto configuration space (theta,phi), the mixed spaces (k_theta,phi ) and (theta,k_phi), or onto momentum space (k_theta,k _phi), that caustics occur. The essential strategy is to employ a mixed or momentum space representation of the wavefield in the vicinity of a configuration space caustic.

[Effects of acid rain stress on Eleocarpus glabripetalus seedlings leaf chlorophyll fluorescence characteristics and growth].

PubMed

Yin, Xiu-Min; Yu, Shu-Quan; Jiang, Hong; Liu, Mei-Hu

2010-06-01

A pot experiment was conducted to study the Eleocarpus glabripetalus seedlings leaf chlorophyll fluorescence characteristics and growth in different seasons under simulated acid rain stress (heavy, pH = 2. 5; moderate, pH = 4.0; and control, pH = 5.6). In the same treatments, the leaf relative chlorophyll content (SPAD), maximum PS II photochemical efficiency (F(v)/F(m)), actual PSII photochemical quantum yield (phi(PS II)), plant height, and stem diameter in different seasons were all in the order of October > July > April > January. In the same seasons, all the parameters were in the order of heavy acid rain > moderate acid rain > control. The interactions between different acid rain stress and seasons showed significant effects on the SPAD, F(v)/F(m), plant height, and stem diameter, but lesser effects on phi(PS II), qp and qN.

Optical properties of humic substances and CDOM: relation to structure.

PubMed

Boyle, Erin S; Guerriero, Nicolas; Thiallet, Anthony; Del Vecchio, Rossana; Blough, Neil V

2009-04-01

The spectral dependencies of absorption and fluorescence emission (emission maxima (lamdamax), quantum yields (phi), and mean lifetimes (taum)) were acquired for a commercial lignin, Suwannee River humic (SRHA) and fulvic (SRFA) acids, and a series solid phase extracts (C18) from the Middle Atlantic Bight (MAB extracts). These parameters were compared with the relative average size and total lignin phenol content (TLP). TLP was strongly correlated with absorption at 280 and 355 nm for the MAB extracts, SRHA, and SRFA. The spectral dependence of lamdamax, phi), and taum was very similar for all samples, suggesting a common photophysical and thus structural basis. A strong decrease of phi and taum with increasing average size indicates that intramolecular interactions must be important. When combined with previous work, the results lead us to conclude that the optical properties commonly associated with terrestrial humic substances and chromophoric dissolved organic matter arise primarily from an ensemble of partially oxidized lignins derived from vascular plant sources. Theyfurther provide additional support for an electronic interaction model in which intramolecular energy transfer, excited-state electron transfer, as well as charge transfer likely play important roles in producing the observed optical and photochemical properties of these materials.

Observation of {chi}{sub c1} Decays into Vector Meson Pairs {phi}{phi}, {omega}{omega}, and {omega}{phi}

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

Ablikim, M.; An, Z. H.; Bai, J. Z.

Using (106{+-}4)x10{sup 6} {psi}(3686) events accumulated with the BESIII detector at the BEPCII e{sup +}e{sup -} collider, we present the first measurement of decays of {chi}{sub c1} to vector meson pairs {phi}{phi}, {omega}{omega}, and {omega}{phi}. The branching fractions are measured to be (4.4{+-}0.3{+-}0.5)x10{sup -4}, (6.0{+-}0.3{+-}0.7)x10{sup -4}, and (2.2{+-}0.6{+-}0.2)x10{sup -5}, for {chi}{sub c1}{yields}{phi}{phi}, {omega}{omega}, and {omega}{phi}, respectively, which indicates that the hadron helicity selection rule is significantly violated in {chi}{sub cJ} decays. In addition, the measurement of {chi}{sub cJ}{yields}{omega}{phi} provides the first indication of the rate of doubly OZI-suppressed {chi}{sub cJ} decay. Finally, we present improved measurements for the branching fractionsmore » of {chi}{sub c0} and {chi}{sub c2} to vector meson pairs.« less

Exact diagonalization of quantum lattice models on coprocessors

NASA Astrophysics Data System (ADS)

Siro, T.; Harju, A.

2016-10-01

We implement the Lanczos algorithm on an Intel Xeon Phi coprocessor and compare its performance to a multi-core Intel Xeon CPU and an NVIDIA graphics processor. The Xeon and the Xeon Phi are parallelized with OpenMP and the graphics processor is programmed with CUDA. The performance is evaluated by measuring the execution time of a single step in the Lanczos algorithm. We study two quantum lattice models with different particle numbers, and conclude that for small systems, the multi-core CPU is the fastest platform, while for large systems, the graphics processor is the clear winner, reaching speedups of up to 7.6 compared to the CPU. The Xeon Phi outperforms the CPU with sufficiently large particle number, reaching a speedup of 2.5.

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

Achasov, N. N.

It is argued that the realization of gauge invariance condition as a consequent of cancellation between the {phi} {sup {yields}} {gamma}f{sub 0} {sup {yields}} {gamma}{pi}{sup 0}{pi}{sup 0} resonance contribution and the {phi} {sup {yields}} {gamma}{pi}{sup 0}{pi}{sup 0} background one, suggested by A.V. Anisovich et al., Yad. Fiz. 68, 1614 (2005), is misleading.

[Effects of exogenous spermidine on Cucumis sativus L. seedlings photosynthesis under root zone hypoxia stress].

PubMed

Wang, Tian; Wang, Suping; Guo, Shirong; Sun, Yanjun

2006-09-01

With water culture, this paper studied the effects of exogenous spermidine (Spd) on the net photosynthetic rate (Pn), intercellular CO2 concentrations (Ci), stomatal conductance (Gs), transpiration rate (Tr), apparent quantum yield (phi c), and carboxylation efficiency (CE) of cucumber seedlings tinder hypoxia stress. The results showed that the Pn decreased gradually under hypoxia stress, and reached the minimum 10 days after by 63. 33% of the control. Compared with that of hypoxia-stressed plants, the Pn after 10 days application of exogenous Spd increased 1.25 times. A negative correlation (R2 = 0.4730 - 0.7118) was found between Pn and Ci. Gs and Tr changed in wider ranges, which decreased under hypoxia-stress, but increased under hypoxia-stress plus exogenous Spd application. There was a significant positive correlation between Gs and Tr (R2 = 0.7821 - 0.9458), but these two parameters had no significant correlation with Pn; Hypoxia stress induced a decrease of phi c and CE by 63.01% and 72.33%, respectively, while hypoxia stress plus exogenous Spd application made phi c and CE increase by 23% and 14%, respectively. The photo-inhibition of cucumber seedlings under hypoxia stress was mainly caused by non-stomatal limitation, while exogenous Spd alleviated the hypoxia stress by repairing photosynthesis system.

On absolutely continuous weakly mixing cocycles over irrational rotations

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

Rozhdestvenskii, A V

2003-06-30

A weakly mixing cocycle over a rotation {alpha} is a measurable function {phi}:S{sup 1}{yields}S{sup 1}, where S{sup 1}={l_brace}z element of C:|z|=1{r_brace}, such that the equation {phi}{sup n}(z)=c (h(exp(2{pi}i{alpha})z))/(h(z))for almost all z; (*) has no measurable solutions h( {center_dot} ):S{sup 1}{yields}S{sup 1} for any n element of Z{l_brace}0{r_brace} and c element of C, |c|=1. If the irrational number {alpha} has bounded convergents in its continued fraction expansion and a function M(y) increases more slowly than y ln{sup 1/2}y, then it is proved that there exists a weakly mixing cocycle of the form {phi}(exp(2{pi}ix))=exp(2{pi}i{phi}-tilde(x)), where {phi}-tilde:T{yields}R belongs to the class W{sup 1}(M(L)(T)).more » In addition, it is shown that equation (*) (and also the corresponding additive cohomological equation) is soluble for {phi}-tilde element of W{sup 1}(L log{sub +}{sup 1/2}L(T))« less

Validation of photosynthetic-fluorescence parameters as biomarkers for isoproturon toxic effect on alga Scenedesmus obliquus.

PubMed

Dewez, David; Didur, Olivier; Vincent-Héroux, Jonathan; Popovic, Radovan

2008-01-01

Photosynthetic-fluorescence parameters were investigated to be used as valid biomarkers of toxicity when alga Scenedesmus obliquus was exposed to isoproturon [3-(4-isopropylphenyl)-1,1-dimethylurea] effect. Chlorophyll fluorescence induction of algal cells treated with isoproturon showed inactivation of photosystem II (PSII) reaction centers and strong inhibition of PSII electron transport. A linear correlation was found (R2>or=0.861) between the change of cells density affected by isoproturon and the change of effective PSII quantum yield (PhiM'), photochemical quenching (qP) and relative photochemical quenching (qP(rel)) values. The cells density was also linearly dependent (R2=0.838) on the relative unquenched fluorescence parameter (UQF(rel)). Non-linear correlation was found (R2=0.937) only between cells density and the energy transfer efficiency from absorbed light to PSII reaction center (ABS/RC). The order of sensitivity determined by the EC-50% was: UQF(rel)>PhiM'>qP>qP(rel)>ABS/RC. Correlations between cells density and those photosynthetic-fluorescence parameters provide supporting evidence to use them as biomarkers of toxicity for environmental pollutants.

Quantum Mechanics for Everybody: An autonomous MOOC on EdX for nonscientists

NASA Astrophysics Data System (ADS)

Freericks, James; Cutler, Dylan; Vieira-Barbosa, Lucas

2017-01-01

We have launched a MOOC for nonscientists that teaches quantum mechanics using the Feynman methodology as outlined in his QED book and in a similar book by Daniel Styer. Using a combination of videos, voice-over powerpoint animations, computer simulations and interactive tutorials, we teach the fundamentals of quantum mechanics employing a minimum of math (high school algebra, square roots, and a little trigonometry) but going into detail on a number of complex quantum ideas. We begin with the Stern-Gerlach experiment, including delayed choice and Bell's inequality variants. Then we focus on light developing the quantum theory for partial reflection and diffraction. At this point we demonstrate the complexity of quantum physics by showing how watched and unwatched two-slit experiments behave differently and how quantum particles interfere. The four week course ends with advanced topics in light where we cover the idea of an interaction free measurement, the quantum Zeno effect and indistinguishable particles via the Hong-Ou-Mandel experiment. We hope this MOOC will reach thousands of students interesting in learning quantum mechanics without any dumbing down or the need to learn complex math. It can also be used with undergraduates to help with conceptual understanding. Funded by the National Science Foundation under grants numbered PHY-1620555 and PHY-1314295 and by Georgetown University.

A Gaussian measure of quantum phase noise

NASA Technical Reports Server (NTRS)

Schleich, Wolfgang P.; Dowling, Jonathan P.

1992-01-01

We study the width of the semiclassical phase distribution of a quantum state in its dependence on the average number of photons (m) in this state. As a measure of phase noise, we choose the width, delta phi, of the best Gaussian approximation to the dominant peak of this probability curve. For a coherent state, this width decreases with the square root of (m), whereas for a truncated phase state it decreases linearly with increasing (m). For an optimal phase state, delta phi decreases exponentially but so does the area caught underneath the peak: all the probability is stored in the broad wings of the distribution.

Effective size of certain macroscopic quantum superpositions.

PubMed

Dür, Wolfgang; Simon, Christoph; Cirac, J Ignacio

2002-11-18

Several experiments and experimental proposals for the production of macroscopic superpositions naturally lead to states of the general form /phi(1)>( multiply sign in circle N)+/phi 2 >( multiply sign in circle N), where the number of subsystems N is very large, but the states of the individual subsystems have large overlap, // 2=1-epsilon 2. We propose two different methods for assigning an effective particle number to such states, using ideal Greenberger-Horne-Zeilinger states of the form /0>( multiply sign in circle n)+/1>( multiply sign in circle n) as a standard of comparison. The two methods are based on decoherence and on a distillation protocol, respectively. Both lead to an effective size n of the order of N epsilon 2.

The structure of premixed particle-cloud flames

NASA Technical Reports Server (NTRS)

Seshadri, K.; Berlad, A. L.; Tangirala, V.

1992-01-01

The structure of premixed flames propagating in combustible systems, containing uniformly distributed volatile fuel particles, in an oxidizing gas mixture, is analyzed. It is presumed that the fuel particles vaporize first to yield a gaseous fuel of known chemical structure, which is subsequently oxidized in the gas phase. The analysis is performed in the asymptotic limit, where the value of the characteristic Zeldovich number, based on the gas-phase oxidation of the gaseous fuel is large, and for values of phi(u) greater than or equal to 1.0, where phi(u) is the equivalence ratio based on the fuel available in the fuel particles. The structure of the flame is presumed to consist of a preheat vaporization zone where the rate of the gas-phase chemical reaction is small, a reaction zone where convection and the rate of vaporization of the fuel particles are small and a convection zone where diffusive terms in the conservation equations are small. For given values phi(u) the analysis yields results for the burning velocity and phi(g) where phi(g) is the effective equivalence ratio in the reaction zone. The analysis shows that even though phi(u) greater than or equal to 1.0, for certain cases the calculated value of phi(g) is less than unity. This prediction is in agreement with experimental observations.

Effect of dietary phosphorus, phytase, and 25-hydroxycholecalciferol on broiler chicken bone mineralization, litter phosphorus, and processing yields.

PubMed

Angel, R; Saylor, W W; Mitchell, A D; Powers, W; Applegate, T J

2006-07-01

Three floor pen experiments (Exp) were conducted to evaluate low nonphytin P (NPP) concentrations and the NPP sparing effect of phytase (PHY) and 25-hydroxycholecalciferol (25D) on bone mineralization, bone breaking during commercial processing, litter P, and water-soluble P (WSP) concentrations. Tested treatments (TRT) were control, National Research Council NPP; University of Maryland (UMD) NPP; UMD + PHY, UMD NPP reduced by 0.064% NPP + 600 U of PHY/kg; UMD + PHY + 25D, UMD NPP reduced by 0.090% NPP + 600 U of PHY and 70 microg of 25D/kg; control + PHY mimicked the industry practice of diets by 0.1% when PHY is added; and negative control with 90% UMD NPP concentrations. UMD + PHY and control + PHY diets contained 600 U of PHY/kg, and UMD + PHY + 25D contained 600 U of PHY + 70 microg of 25D/kg. Performance results were presented separately. After each Exp, litter P and WSP were determined, and bone measurements were obtained on 8 or 10 broilers per pen. Tested TRT did not affect broiler BW. Femur ash weight of broilers fed the UMD and UMD + PHY + 25D was lower in all Exp compared with that of broilers fed the control diet. Femur ash was similar for control and UMD + PHY broilers, yet averaged over all Exp, UMD + PHY broilers consumed 39% less NPP and required less NPP per gram of femur ash than those on the control (4.87 and 7.77 g of NPP/g of ash, Exp 3). At the end of Exp 3, broilers were processed in a commercial facility. Despite reductions in NPP intake and bone mineralization, no differences were observed in measurements of economic importance (parts lost, carcass yield, and incidence of broken bones). The P excretion per bird was lowest for birds fed the UMD + PHY + 25D diet followed by those fed the UMD + PHY and negative control diets (10.44, 12.00, and 13.78 g of P/bird, respectively) and were highest for those fed the control diet (19.55 g of P/bird). These results suggest that feeding diets low in P together with PHY and 25D will not affect performance or increase losses at processing while resulting in improved P retention and reductions in P and WSP excreted.

Self-reproduction in k-inflation

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

Helmer, Ferdinand; Winitzki, Sergei

2006-09-15

We study cosmological self-reproduction in models of inflation driven by a scalar field {phi} with a noncanonical kinetic term (k-inflation). We develop a general criterion for the existence of attractors and establish conditions selecting a class of k-inflation models that admit a unique attractor solution. We then consider quantum fluctuations on the attractor background. We show that the correlation length of the fluctuations is of order c{sub s}H{sup -1}, where c{sub s} is the speed of sound. By computing the magnitude of field fluctuations, we determine the coefficients of Fokker-Planck equations describing the probability distribution of the spatially averaged fieldmore » {phi}. The field fluctuations are generally large in the inflationary attractor regime; hence, eternal self-reproduction is a generic feature of k-inflation. This is established more formally by demonstrating the existence of stationary solutions of the relevant Fokker-Planck equations. We also show that there exists a (model-dependent) range {phi}{sub R}<{phi}<{phi}{sub max} within which large fluctuations are likely to drive the field towards the upper boundary {phi}={phi}{sub max}, where the semiclassical consideration breaks down. An exit from inflation into reheating without reaching {phi}{sub max} will occur almost surely (with probability 1) only if the initial value of {phi} is below {phi}{sub R}. In this way, strong self-reproduction effects constrain models of k-inflation.« less

Potts glass reflection of the decoding threshold for qudit quantum error correcting codes

NASA Astrophysics Data System (ADS)

Jiang, Yi; Kovalev, Alexey A.; Pryadko, Leonid P.

We map the maximum likelihood decoding threshold for qudit quantum error correcting codes to the multicritical point in generalized Potts gauge glass models, extending the map constructed previously for qubit codes. An n-qudit quantum LDPC code, where a qudit can be involved in up to m stabilizer generators, corresponds to a ℤd Potts model with n interaction terms which can couple up to m spins each. We analyze general properties of the phase diagram of the constructed model, give several bounds on the location of the transitions, bounds on the energy density of extended defects (non-local analogs of domain walls), and discuss the correlation functions which can be used to distinguish different phases in the original and the dual models. This research was supported in part by the Grants: NSF PHY-1415600 (AAK), NSF PHY-1416578 (LPP), and ARO W911NF-14-1-0272 (LPP).

Differential cross sections and spin density matrix elements for gamma p -> phi p from CLAS

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

Biplab Dey, Curtis A. Meyer

2011-10-01

Preliminary differential cross-sections and the {rho}{sub MM'}{sup 0} spin density matrix elements (SDME) for the reaction {gamma}p {yields} {phi} for both charged- ({phi} {yields} K{sup +}K{sup -}) and neutral-mode ({phi} {yields} K{sub L}{sup 0}K{sub S}{sup 0}) topologies obtained from CLAS are presented. Our kinematic coverage is from near production threshold ({radical}s {approx} 1.97more » $$ GeV) to {radical}s = 2.84$$ GeV, with a wide coverage in the production angle. As seen in previous LEPS results, the differential cross-sections show a localized 'bump' between {radical}s {approx} 2 and 2.2 GeV that is not expected from a simple Pomeron exchange picture. Comparisons between the charged- and neutral-mode results and possible effects from the K{sup +} {Lambda}(1520) channel are discussed. Our SDME results confirm the well-known deviations from t-channel helicity conservation (TCHC) for Pomeron exchange, but s-channel helicity conservation (SCHC) is also seen to be broken.« less

q-bosons and the q-analogue quantized field

NASA Technical Reports Server (NTRS)

Nelson, Charles A.

1995-01-01

The q-analogue coherent states are used to identify physical signatures for the presence of a 1-analogue quantized radiation field in the q-CS classical limits where the absolute value of z is large. In this quantum-optics-like limit, the fractional uncertainties of most physical quantities (momentum, position, amplitude, phase) which characterize the quantum field are O(1). They only vanish as O(1/absolute value of z) when q = 1. However, for the number operator, N, and the N-Hamiltonian for a free q-boson gas, H(sub N) = h(omega)(N + 1/2), the fractional uncertainties do still approach zero. A signature for q-boson counting statistics is that (Delta N)(exp 2)/ (N) approaches 0 as the absolute value of z approaches infinity. Except for its O(1) fractional uncertainty, the q-generalization of the Hermitian phase operator of Pegg and Barnett, phi(sub q), still exhibits normal classical behavior. The standard number-phase uncertainty-relation, Delta(N) Delta phi(sub q) = 1/2, and the approximate commutation relation, (N, phi(sub q)) = i, still hold for the single-mode q-analogue quantized field. So, N and phi(sub q) are almost canonically conjugate operators in the q-CS classical limit. The q-analogue CS's minimize this uncertainty relation for moderate (absolute value of z)(exp 2).

Quantum Chemical Calculations Using Accelerators: Migrating Matrix Operations to the NVIDIA Kepler GPU and the Intel Xeon Phi.

PubMed

Leang, Sarom S; Rendell, Alistair P; Gordon, Mark S

2014-03-11

Increasingly, modern computer systems comprise a multicore general-purpose processor augmented with a number of special purpose devices or accelerators connected via an external interface such as a PCI bus. The NVIDIA Kepler Graphical Processing Unit (GPU) and the Intel Phi are two examples of such accelerators. Accelerators offer peak performances that can be well above those of the host processor. How to exploit this heterogeneous environment for legacy application codes is not, however, straightforward. This paper considers how matrix operations in typical quantum chemical calculations can be migrated to the GPU and Phi systems. Double precision general matrix multiply operations are endemic in electronic structure calculations, especially methods that include electron correlation, such as density functional theory, second order perturbation theory, and coupled cluster theory. The use of approaches that automatically determine whether to use the host or an accelerator, based on problem size, is explored, with computations that are occurring on the accelerator and/or the host. For data-transfers over PCI-e, the GPU provides the best overall performance for data sizes up to 4096 MB with consistent upload and download rates between 5-5.6 GB/s and 5.4-6.3 GB/s, respectively. The GPU outperforms the Phi for both square and nonsquare matrix multiplications.

Evidence of N*(1535) resonance contribution in the pn{yields}d{phi} reaction

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

Cao Xu; Theoretical Physics Center for Sciences Facilities, Chinese Academy of Sciences, Beijing 100049; Graduate University of Chinese Academy of Sciences, Beijing 100049

2009-08-15

The N*(1535) resonance contributions to the pn{yields}d{phi} reaction are evaluated in an effective Lagrangian model. The {pi}-, {eta}-, and {rho}-meson exchange are considered. It is shown that the contributions from {pi}- and {rho}-meson exchange are dominant, while the contribution from {eta}-meson exchange is negligibly small. Our theoretical results reproduce the experimental data of both total cross section and angular distribution well. This is more evidence that the N*(1535) resonance has a large ss component leading to a large coupling to N{phi}, which may be the real origin of the Okubo-Zweig-Iizuka rule violation in the {pi}N and pN reactions.

Study of Quantum Chaos in the Framework of Triaxial Rotator Models

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

Proskurins, J.; Bavrins, K.; Andrejevs, A.

2009-01-28

Dynamical quantum chaos criteria--a perturbed wave function entropy W({psi}{sub i}) and a fragmentation width {kappa}({phi}{sub k}) of basis states were studied in two cases of nuclear rigid triaxial rotator models. The first model is characterized by deformation angle {gamma} only, while the second model depends on both quadrupole deformation parameters ({beta},{gamma}). The degree of chaoticity has been determined in the studies of the dependence of criteria W({psi}{sub i}) and {kappa}({phi}{sub k}) from nuclear spin values up to I{<=}101 for model parameters {gamma} and ({beta},{gamma}) correspondingly. The transition from librational to rotational type energy spectra has been considered for both modelsmore » as well.« less

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

Lin, C.T.

Linear and nonlinear photochemistries of 1,4-diazabicyclo(2.2.2)octane (DABCO) are investigated at room temperature by using ArF (193 nm) and KrF (248 nm) lasers. With an unfocused beam geometry, DABCO vapor displays a strong fluorescence when excited at 248 nm, but it shows no detectable emission with 193-nm excitation. The linear photochemistry quantum yield for DABCO is determined as phi/sub p/(248nm) approx. 0.1 and phi/sub p/(193 nm) approx. 0.3. The main stable photochemical products are analyzed as C/sub 2/H/sub 4/ and C/sub 2/H/sub 2/ for 248- and 193-nm excitation, respectively. When focused beam excitation is used, both ArF and KrF lasers dissociatemore » DABCO molecules and give three strong radical emissions of CN*(B vector /sup 2/..sigma.. ..-->.. X vector /sup 2/ ..sigma../sup +/), CH*(A vector /sup 2/..delta.. ..-->.. X vector /sup 2/II), and C/sub 2/*(D vector /sup 3/II/sub g/ ..-->.. a vector /sup 3/II/sub u/). The time behavior, the laser power dependence, and the sample pressure dependence of these emissive radicals are examined. The possible mechanisms for the Rydberg state photochemistry of DABCO are discussed.« less

A Measurement of the D+(s) lifetime

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

Link, J.M.; Yager, P.M.; /UC, Davis

2005-04-01

A high statistics measurement of the D{sub s}{sup +} lifetime from the Fermilab fixed-target FOCUS photoproduction experiment is presented. They describe the analysis of the two decay modes, D{sub s}{sup +} {yields} {phi}(1020){pi}{sup +} and D{sub s}{sup +} {yields} {bar K}*(892){sup 0}K{sup +}, used for the measurement. The measured lifetime is 507.4 {+-} 5.5(stat.) {+-} 5.1(syst.) is using 8961 {+-} 105 D{sub s}{sup +} {yields} {phi}(1020){pi}{sup +} and 4680 {+-} 90 D{sub s}{sup +} {yields} {bar K}*(892){sup 0} K{sup +} decays. This is a significant improvement over the present world average.

Force-field parameters of the Psi and Phi around glycosidic bonds to oxygen and sulfur atoms.

PubMed

Saito, Minoru; Okazaki, Isao

2009-12-01

The Psi and Phi torsion angles around glycosidic bonds in a glycoside chain are the most important determinants of the conformation of a glycoside chain. We determined force-field parameters for Psi and Phi torsion angles around a glycosidic bond bridged by a sulfur atom, as well as a bond bridged by an oxygen atom as a preparation for the next study, i.e., molecular dynamics free energy calculations for protein-sugar and protein-inhibitor complexes. First, we extracted the Psi or Phi torsion energy component from a quantum mechanics (QM) total energy by subtracting all the molecular mechanics (MM) force-field components except for the Psi or Phi torsion angle. The Psi and Phi energy components extracted (hereafter called "the remaining energy components") were calculated for simple sugar models and plotted as functions of the Psi and Phi angles. The remaining energy component curves of Psi and Phi were well represented by the torsion force-field functions consisting of four and three cosine functions, respectively. To confirm the reliability of the force-field parameters and to confirm its compatibility with other force-fields, we calculated adiabatic potential curves as functions of Psi and Phi for the model glycosides by adopting the Psi and Phi force-field parameters obtained and by energetically optimizing other degrees of freedom. The MM potential energy curves obtained for Psi and Phi well represented the QM adiabatic curves and also these curves' differences with regard to the glycosidic oxygen and sulfur atoms. Our Psi and Phi force-fields of glycosidic oxygen gave MM potential energy curves that more closely represented the respective QM curves than did those of the recently developed GLYCAM force-field. (c) 2009 Wiley Periodicals, Inc.

Numerical methods for studying anharmonic oscillator approximations to the phi super 4 sub 2 quantum field theory

NASA Technical Reports Server (NTRS)

Isaacson, D.; Marchesin, D.; Paes-Leme, P. J.

1980-01-01

This paper is an expanded version of a talk given at the 1979 T.I.C.O.M. conference. It is a self-contained introduction, for applied mathematicians and numerical analysts, to quantum mechanics and quantum field theory. It also contains a brief description of the authors' numerical approach to the problems of quantum field theory, which may best be summarized by the question; Can we compute the eigenvalues and eigenfunctions of Schrodinger operators in infinitely many variables.

Interest rates in quantum finance: the Wilson expansion and Hamiltonian.

PubMed

Baaquie, Belal E

2009-10-01

Interest rate instruments form a major component of the capital markets. The Libor market model (LMM) is the finance industry standard interest rate model for both Libor and Euribor, which are the most important interest rates. The quantum finance formulation of the Libor market model is given in this paper and leads to a key generalization: all the Libors, for different future times, are imperfectly correlated. A key difference between a forward interest rate model and the LMM lies in the fact that the LMM is calibrated directly from the observed market interest rates. The short distance Wilson expansion [Phys. Rev. 179, 1499 (1969)] of a Gaussian quantum field is shown to provide the generalization of Ito calculus; in particular, the Wilson expansion of the Gaussian quantum field A(t,x) driving the Libors yields a derivation of the Libor drift term that incorporates imperfect correlations of the different Libors. The logarithm of Libor phi(t,x) is defined and provides an efficient and compact representation of the quantum field theory of the Libor market model. The Lagrangian and Feynman path integrals of the Libor market model of interest rates are obtained, as well as a derivation given by its Hamiltonian. The Hamiltonian formulation of the martingale condition provides an exact solution for the nonlinear drift of the Libor market model. The quantum finance formulation of the LMM is shown to reduce to the industry standard Bruce-Gatarek-Musiela-Jamshidian model when the forward interest rates are taken to be exactly correlated.

Matrix Results and Techniques in Quantum Information Science and Related Topics

NASA Astrophysics Data System (ADS)

Pelejo, Diane Christine

In this dissertation, we present several matrix-related problems and results motivated by quantum information theory. Some background material of quantum information science will be discussed in chapter 1, while chapter 7 gives a summary of results and concluding remarks. In chapter 2, we look at 2n x 2 n unitary matrices, which describe operations on a closed n-qubit system. We define a set of simple quantum gates, called controlled single qubit gates, and their associated operational cost. We then present a recurrence scheme to decompose a general 2n x 2n unitary matrix to the product of no more than 2n-12n-1 single qubit gates with small number of controls. In chapter 3, we address the problem of finding a specific element phi among a given set of quantum channels S that will produce the optimal value of a scalar function D(rho 1,phi(rho2)), on two fixed quantum states rho 1 and rho2. Some of the functions we considered for D(·,·) are the trace distance, quantum fidelity and quantum relative entropy. We discuss the optimal solution when S is the set of unitary quantum channels, the set of mixed unitary channels, the set of unital quantum channels, and the set of all quantum channels. In chapter 4, we focus on the spectral properties of qubit-qudit bipartite states with a maximally mixed qudit subsystem. More specifically, given positive numbers a1 ≥ ... ≥ a 2n ≥ 0, we want to determine if there exist a 2n x 2n density matrix rho having eigenvalues a1,..., a2n and satisfying tr 1(rho)=1/n In. This problem is a special case of the more general quantum marginal problem. We give the minimal necessary and sufficient conditions on a1,..., a2n for n ≤ 6 and state some observations on general values of n.. In chapter 5, we discuss the numerical method of alternating projections and illustrate its usefulness in: (a) constructing a quantum channel, if it exists, such that phi(rho(1))=sigma(1),...,phi(rho (k))=sigma(k) for given rho (1),...,rho(k) ∈ Dn and sigma(1),...,sigma (k) ∈ Dm, (b) constructing a multipartite state rho having a prescribed set of reduced states rho1,..., rhor on r of its subsystems, (c) constructing a multipartite staterho having prescribed reduced states and additional properties such as having prescribed eigenvalues, prescribed rank or low von Neuman entropy; and (d) determining if a square matrix A can be written as a product of two positive semidefinite contractions. In chapter 6, we examine the shape of the Minkowski product of convex subsets K1 and K2 of C given by K1K 2 = {ab: a ∈ K1, b ∈ K2}, which has applications in the study of the product numerical range and quantum error-correction. In Karol, it was conjectured that K1K 2 is star-shaped when K1 and K2 are convex. We give counterexamples to show that this conjecture does not hold in general but we show that the set K 1K2 is star-shaped if K 1 is a line segment or a circular disk.

Use of the Lorentz-operator in relativistic quantum mechanics to guarentee a single-energy root

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

Ritchie, A B

1998-08-01

The Lorentz-operator form of relativistic quantum mechanics, with relativistic wave equation i{h_bar}{partial_derivative}{psi}/{partial_derivative}t=(mc{sup 2}{gamma}+e{Phi}){psi}, is implemented to guarantee a single-energy root. The Lorentz factor as modified by Pauli's ansatz is given by {gamma}={radical}1+[{rvec {sigma}}{center_dot}(i{h_bar}{rvec {del}}+(e/c){rvec A})]{sup 2}/m{sup 2}c{sup 2}, such that the theory is appropriate for electrons. Magnetic fine structure in the Lorentz relativistic wave equation emerges on the use of an appropriate operator form of the Lienard-Wiechert four- potential ({Phi},{rvec A}) from electromagnetic theory. Although computationally more intensive the advantage of the theory is the elimination of the negative-root of the energy and an interpretation of the wave function basedmore » on a one-particle, positive definite probability density like that of nonrelativistic quantum mechanics.« less

Measurement of the Branching Fraction, Polarization, and CP Asymmetry for B{sup 0}{yields}{rho}{sup +}{rho}{sup -} Decays, and Determination of the Cabibbo-Kobayashi-Maskawa Phase {phi}{sub 2}

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

Somov, A.; Schwartz, A.J.; Bahinipati, S.

2006-05-05

We have measured the branching fraction B, longitudinal polarization fraction f{sub L}, and CP asymmetry coefficients A and S for B{sup 0}{yields}{rho}{sup +}{rho}{sup -} decays with the Belle detector at the KEKB e{sup +}e{sup -} collider using 253 fb{sup -1} of data. We obtain B=[22.8{+-}3.8(stat){sub -2.6}{sup +2.3}(syst)]x10{sup -6}, f{sub L}=0.941{sub -0.040}{sup +0.034}(stat){+-}0.030(syst), A=0.00{+-}0.30(stat){+-}0.09(syst), and S=0.08{+-}0.41(stat){+-}0.09(syst). These values are used to constrain the Cabibbo-Kobayashi-Maskawa phase {phi}{sub 2}; the solution consistent with the standard model is {phi}{sub 2}=(88{+-}17) deg. or 59 deg. <{phi}{sub 2}<115 deg. at 90% C.L.

[Effects of light intensity on growth and photosynthetic characteristics of Tulipa edulis].

PubMed

Xu, Hongjian; Zhu, Zaibiao; Guo, Qiaosheng; Wu, Zhengjun; Ma, Hongliang; Miao, Yuanyuan

2012-02-01

Present study was conducted to explore the growth and photosynthetic characteristics of Tulipa edulis under different light conditions (23%, 45%, 63%, 78%, 100% of full sunlight) and to determine the optimum light intensity for growth of T. edulis. The leaf area and biomass indicators as well as reproductive characteristics were measured. The photosynthetic basic parameters and light response curve were determined by a LI-6400XT portable photosynthesis system, and the light response curve characteristic parameters was determined. Additionally, chlorophyll fluorescence parameters were determined by assorted fluorescence leaf chamber of LI-6400XT. The lowest biomass yield was observed in the 23% and 100% of full sunlight treatments while the highest value was found under the 78% of full sunlight conditions. With the reduction of light availability, the success rate of sexual reproduction, light saturation point (LSP) and light compensation point (LCP) reduced, while apparent quantum yield (AQY) increased. 23% and 45% of full sunlight treatments led to lower photosynthesis rate (Pn) and higher apparent quantum yield (AQY) in comparison with other treatents. The highest photosynthesis rate was observed in the 78% and 100% of full sunlight treatments. In addition, 78% of full sunlight treatments led to highest Fv/Fm, Fv'/Fm', PhiPS II, ETR, and qP. T. edulis was able to adapt in a wide range of light intensity, and 78% of full sunlinght was the most suitable light condition for growth of T. edulis.

Saturated ferromagnetism from statistical transmutation in two dimensions.

PubMed

Saiga, Yasuhiro; Oshikawa, Masaki

2006-01-27

The total spin of the ground state is calculated in the U-->infinity Hubbard model with uniform magnetic flux perpendicular to a square lattice, in the absence of Zeeman coupling. It is found that the saturated ferromagnetism emerges in a rather wide region in the space of the flux density phi and the electron density ne. In particular, the saturated ferromagnetism at phi=ne is induced by the formation of a spin-1/2 boson, which is a composite of an electron and the unit flux quantum.

Order and disorder in crystals of hexameric NTPases from dsRNA bacteriophages.

PubMed

Mancini, Erika J; Grimes, Jonathan M; Malby, Robyn; Sutton, Geoffrey C; Kainov, Denis E; Juuti, Jarmo T; Makeyev, Eugene V; Tuma, Roman; Bamford, Dennis H; Stuart, David I

2003-12-01

The packaging of genomic RNA in members of the Cystoviridae is performed by P4, a hexameric protein with NTPase activity. Across family members such as Phi6, Phi8 and Phi13, the P4 proteins show low levels of sequence identity, but presumably have similar atomic structures. Initial structure-determination efforts for P4 from Phi6 and Phi8 were hampered by difficulties in obtaining crystals that gave ordered diffraction. Diffraction from crystals of full-length P4 showed a variety of disorder and anisotropy. Subsequently, crystals of Phi13 P4 were obtained which yielded well ordered diffraction to 1.7 A. Comparison of the packing arrangements of P4 hexamers in different crystal forms and analysis of the disorder provides insights into the flexibility of this family of proteins, which might be an integral part of their biological function.

[Response of photosynthetic characteristics of peanut seedlings leaves to low light].

PubMed

Zhang, Kun; Wan, Yong-shan; Liu, Feng-zhen; Zhang, Er-qun; Wang, Su

2009-12-01

To investigate the effects of shading and light recovery on the photosynthetic characteristics of peanut seedlings leaves, different shading treatments including no shading, 27% shading, 43% shading, and 77% shading were performed with black sunshade net at the seedling stage of two peanut cultivars Fenghua 1 and Fenghua 2, with related parameters determined. It was shown that with the increase of shading degree, the leaf chlorophyll content, actual PSII photochemical efficiency under irradiance (phi(PS II)), and maximum PS II photochemical efficiency (Fv/Fm) of test cultivars increased, while the Chl a/b ratio and photosynthetic rate (Pn) decreased. On the first day after light recovery, the Pn and stomatal conductance (Gs) decreased while the intercellular CO2 concentration (Ci) increased with increasing shading degree when measured under high light, but the Pn increased and the Gs and Ci decreased with increasing shading degree when measured under low light. The ratio of Pn measured under low light to that measured under high light increased significantly. With increasing shading degree, the light compensation point, light saturation point, CO2 compensation point, CO2 saturation point, and carboxylation efficiency decreased, while the apparent quantum yield increased. After the removal of shading, the Pn, phi(PS II), and Fv/Fm under natural light decreased immediately, but increased gradually 3-5 days after. 15 days after light recovery, the Pn, phi(PS II) and Fv/Fm in treatment 27% shading recovered to the level of no shading. As for the other treatments, the restored extent differed with shading degree and test variety. In the same treatments, the leaf chlorophyll content, Pn and phi(PS II) of Fenghua 1 were higher than those of Fenghua 2. The results demonstrated that shading at seedling stage improved the capabilities of test varieties in using low light, but reduced the capabilities in using high light.

Enhancement of high-order harmonic generation by a two-color field: Influence of propagation effects

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

Schiessl, K.; Persson, E.; Burgdoerfer, J.

2006-11-15

Recent calculations of the response of a single atom subjected to a two-color laser pulse with the higher frequency being resonant with an excitation of the target atom revealed a significant enhancement of photoionization as well as high-order harmonic generation [K. Ishikawa, Phy. Rev. Lett. 91, 043002 (2003)]. We investigate the problem in the framework a fully quantum-mechanical pulse propagation algorithm and perform calculations for rare gases in the single-active-electron approximation. The enhancement of harmonic output compared to the corresponding one-color pulse remains intact for short propagation lengths, promising the feasibility of experimental realization. We also study weak second colorsmore » resonant via a two-photon transition where significant enhancements in harmonic yields can be observed as well.« less

Particulates generated from combustion of polymers (plastics).

PubMed

Shemwell, B E; Levendis, Y A

2000-01-01

This is an experimental study on the characterization of particulate (soot) emissions from burning polymers. Emissions of polystyrene (PS), polyethylene (PE), polypropylene (PP), polymethyl methacrylate (PMMA), and polyvinyl chloride (PVC) plastics were studied. Combustion took place in a laboratory-scale, electrically heated, drop-tube furnace at temperatures of 1300 and 1500 K, in air. The nominal bulk (global) equivalence ratio, phi, was varied in the range of 0.5-1.5, and the gas residence time in the nearly isothermal radiation zone of the furnace was approximately 1 sec. The particulate emissions were size-classified at the exit of the furnace, using a multi-stage inertial particle impactor. Results showed that both the yields and the size distributions of the emitted soot were remarkably different for the five plastics burned. Soot yields increased with an increasing bulk equivalence ratio. Combustion of PS yielded the highest amounts of soot (most highly agglomerated), several times more than the rest of the polymers. More soot was emitted from PS at 1500 than at 1300 K. Substantial amounts of soot agglomerates were larger than 9 microns. At 1500 and 1300 K, 35 and 29% of the soot mass, respectively, was PM2 (2 microns or smaller). Emissions from PE and PP were remarkably similar to each other. These polymers produced very low emissions at phi < or = 0.5, but emissions increased drastically with phi, and most of the soot was very fine (70-97% of the mass was PM2, depending on phi). Emissions from the combustion of PMMA were comparatively low and were the least influenced by the bulk phi, and 79-95% of the emissions were PM2. Combustion of PVC yielded the lowest amounts of soot; moreover, only 13-34% of the mass was PM2. On a comparative basis, at 1500 K, the following ranges of particulate yields were PM2: 19-75 mg/g of PS, 8-36 mg/g of PE, 1.5-47 mg/g of PP, 11-20 mg/g of PMMA, and 2-8 mg/g of PVC, depending on phi. These comparative results demonstrate that PS produces the highest amounts of fine particulates, followed by PP, PE, and PMMA, and then PVC. Burning these materials with excess oxygen drastically reduces the particulate emissions of PE and PP, substantially reduces those of PS, and mildly reduces those of PMMA and PVC.

Electroweak vacuum instability and renormalized Higgs field vacuum fluctuations in the inflationary universe

NASA Astrophysics Data System (ADS)

Kohri, Kazunori; Matsui, Hiroki

2017-08-01

In this work, we investigated the electroweak vacuum instability during or after inflation. In the inflationary Universe, i.e., de Sitter space, the vacuum field fluctuations < δ phi 2 > enlarge in proportion to the Hubble scale H2. Therefore, the large inflationary vacuum fluctuations of the Higgs field < δ phi 2 > are potentially catastrophic to trigger the vacuum transition to the negative-energy Planck-scale vacuum state and cause an immediate collapse of the Universe. However, the vacuum field fluctuations < δ phi 2 >, i.e., the vacuum expectation values have an ultraviolet divergence, and therefore a renormalization is necessary to estimate the physical effects of the vacuum transition. Thus, in this paper, we revisit the electroweak vacuum instability from the perspective of quantum field theory (QFT) in curved space-time, and discuss the dynamical behavior of the homogeneous Higgs field phi determined by the effective potential V eff( phi ) in curved space-time and the renormalized vacuum fluctuations < δ phi 2 >ren via adiabatic regularization and point-splitting regularization. We simply suppose that the Higgs field only couples the gravity via the non-minimal Higgs-gravity coupling ξ(μ). In this scenario, the electroweak vacuum stability is inevitably threatened by the dynamical behavior of the homogeneous Higgs field phi, or the formations of AdS domains or bubbles unless the Hubble scale is small enough H< ΛI .

[Effects of soil progressive drought during the flowering and boll-forming stage on gas exchange parameters and chlorophyll fluorescence characteristics of the subtending leaf to cotton boll].

PubMed

Liu, Zhao-wei; Zhang, Pan; Wang, Rui; Kuai, Jie; Li, Lei; Wang, You-hua; Zhou, Zhi-guo

2014-12-01

To investigate the dynamic changes and response mechanisms of gas exchange parameters and fluorescence indices of the subtending leaf to cotton boll under soil progressive drought stress, pot experiments of the hybrid cotton No. 3 were conducted with soil relative water content (SRWC) (75 +/- 5)% as control group, SRWC (60 +/- 5)% and SRWC (45 +/- 5)% as experimental groups dealt with progressive drought for 50 days. Results showed that, the net photosynthetic rate (Pn), stomatal conductance (g(s)) and leaf intercellular CO2 concentration (Ci) decreased while Ls increased under SRWC (60 +/- 5)% for 0-21 days. Furthermore, there was no significant change in chlorophyll fluorescence indices. This indicated that stomatal limitation was the main reason for the reduction of photosynthesis of cotton. In addition, when drought for 21-49 days under SRWC (60 +/- 5)%, Pn kept decreasing, while Ci began to increase and Ls began to decrease. Potential photochemical efficiency (Fv/Fm), quantum yield of photo system II (phi(PSI)) and photochemical quenching coefficient (q(P)) reduced significantly, but non-photochemical quenching coefficient (NPQ) first rose then decreased. Thus, nonstomatal limitation was the main reason why the photosynthesis of cotton reduced. Photosynthetic organization and photosynthetic enzyme system were destroyed, boll setting intensity reduced and the number of boll and yield reduced significantly. Drought for 0-14 days under SRWC (45 +/- 5)% treatment led to sharp decrease in Pn, g(s) and Ci, whereas Ls obviously increased. There was no significant change in Fv/Fm, phi(PSII), q(P), indicating stomatal limitation was the main reason why the photosynthesis of cotton reduced. Pn decreased slowly, while Ci began to rise and Ls began to decline under SRWC (45 +/- 5)% treatment for 14-49 days. Fv/Fm, phi(PSII), q(P) decreased while NPQ rose first then declined, which indicated that nonstomatal limitation worked to reduce the cotton photosynthetic performance. The boll setting intensity reduced significantly and the number of boll and yield declined. The critical stress time of cotton growth in current study was 21 and 14 days respectively under SRWC (60 +/- 5)% and SRWC (45 +/- 5)% treatments during the flowering and boll-forming stage.

CP violation experiment at Fermilab

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

Hsiung, Yee B.

1990-07-01

The E731 experiment at Fermilab has searched for direct'' CP violation in K{sup 0} {yields} {pi}{pi}, which is parametrized by {var epsilon}{prime}/{var epsilon}. For the first time, in 20% of the data set, all four modes of the K{sub L,S} {yields} {pi}{sup +}{pi}{sup {minus}} ({pi}{sup 0}{pi}{sup 0}) were collected simultaneously, providing a great check on the systematic uncertainty. The result is Re({var epsilon}{prime}/{var epsilon}) = {minus}0.0004 {plus minus} 0.0014 (stat) {plus minus} 0.0006(syst), which provides no evidence for direct'' CP violation. The CPT symmetry has also been tested by measuring the phase difference {Delta}{phi} = {phi}{sub 00} {minus} {phi}{sub {plusmore » minus}} between the two CP violating parameters {eta}{sub 00} and {eta}{sub {plus minus}}. We fine {Delta}{phi} = {minus}0.3{degrees} {plus minus} 2.4{degree}(stat) {plus minus} 1.2{degree}(syst). Using this together with the world average {phi}{sub {plus minus}}, we fine that the phase of the K{sup 0}-{bar K}{sup 0} mixing parameter {var epsilon} is 44.5{degree} {plus minus} 1.5{degree}. Both of these results agree well with the predictions of CPT symmetry. 17 refs., 10 figs.« less

Adiabatically-controlled two-qubit gates using quantum dot hybrid qubits

NASA Astrophysics Data System (ADS)

Frees, Adam; Gamble, John King; Friesen, Mark; Coppersmith, S. N.

With its recent success in experimentally performing single-qubit gates, the quantum dot hybrid qubit is an excellent candidate for two-qubit gating. Here, we propose an operational scheme which exploits the electrostatic properties of such qubits to yield a tunable effective coupling in a system with a static capacitive coupling between the dots. We then use numerically calculated fidelities to demonstrate the effect of charge noise on single- and two-qubit gates with this scheme. Finally, we show steps towards optimizing the gates fidelities, and discuss ways that the scheme could be further improved. This work was supported in part by ARO (W911NF-12-0607) (W911NF-12-R-0012), NSF (PHY-1104660), ONR (N00014-15-1-0029). The authors gratefully acknowledge support from the Sandia National Laboratories Truman Fellowship Program, which is funded by the Laboratory Directed Research and Development (LDRD) Program. Sandia is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the US Department of Energy's National Nuclear Security Administration under Contract No. DE-AC04-94AL85000.

Precision force sensing with optically-levitated nanospheres

NASA Astrophysics Data System (ADS)

Geraci, Andrew

2017-04-01

In high vacuum, optically-trapped dielectric nanospheres achieve excellent decoupling from their environment and experience minimal friction, making them ideal for precision force sensing. We have shown that 300 nm silica spheres can be used for calibrated zeptonewton force measurements in a standing-wave optical trap. In this optical potential, the known spacing of the standing wave anti-nodes can serve as an independent calibration tool for the displacement spectrum of the trapped particle. I will describe our progress towards using these sensors for tests of the Newtonian gravitational inverse square law at micron length scales. Optically levitated dielectric objects also show promise for a variety of other precision sensing applications, including searches for gravitational waves and other experiments in quantum optomechanics. National Science Foundation PHY-1205994, PHY-1506431, PHY-1509176.

Partonic Flow and phi-Meson production in Au+Au collisions at sqrt radical sNN = 200 GeV.

PubMed

Abelev, B I; Aggarwal, M M; Ahammed, Z; Anderson, B D; Arkhipkin, D; Averichev, G S; Bai, Y; Balewski, J; Barannikova, O; Barnby, L S; Baudot, J; Baumgart, S; Belaga, V V; Bellingeri-Laurikainen, A; Bellwied, R; Benedosso, F; Betts, R R; Bhardwaj, S; Bhasin, A; Bhati, A K; Bichsel, H; Bielcik, J; Bielcikova, J; Bland, L C; Blyth, S-L; Bombara, M; Bonner, B E; Botje, M; Bouchet, J; Brandin, A V; Bravar, A; Burton, T P; Bystersky, M; Cadman, R V; Cai, X Z; Caines, H; Calderón de la Barca Sánchez, M; Callner, J; Catu, O; Cebra, D; Chajecki, Z; Chaloupka, P; Chattopadhyay, S; Chen, H F; Chen, J H; Chen, J Y; Cheng, J; Cherney, M; Chikanian, A; Christie, W; Chung, S U; Coffin, J P; Cormier, T M; Cosentino, M R; Cramer, J G; Crawford, H J; Das, D; Dash, S; Daugherity, M; de Moura, M M; Dedovich, T G; DePhillips, M; Derevschikov, A A; Didenko, L; Dietel, T; Djawotho, P; Dogra, S M; Dong, X; Drachenberg, J L; Draper, J E; Du, F; Dunin, V B; Dunlop, J C; Dutta Mazumdar, M R; Eckardt, V; Edwards, W R; Efimov, L G; Emelianov, V; Engelage, J; Eppley, G; Erazmus, B; Estienne, M; Fachini, P; Fatemi, R; Fedorisin, J; Feng, A; Filip, P; Finch, E; Fine, V; Fisyak, Y; Fu, J; Gagliardi, C A; Gaillard, L; Ganti, M S; Garcia-Solis, E; Ghazikhanian, V; Ghosh, P; Gorbunov, Y G; Gos, H; Grebenyuk, O; Grosnick, D; Grube, B; Guertin, S M; Guimaraes, K S F F; Gupta, N; Haag, B; Hallman, T J; Hamed, A; Harris, J W; He, W; Heinz, M; Henry, T W; Heppelmann, S; Hippolyte, B; Hirsch, A; Hjort, E; Hoffman, A M; Hoffmann, G W; Hofman, D J; Hollis, R S; Horner, M J; Huang, H Z; Hughes, E W; Humanic, T J; Igo, G; Iordanova, A; Jacobs, P; Jacobs, W W; Jakl, P; Jia, F; Jones, P G; Judd, E G; Kabana, S; Kang, K; Kapitan, J; Kaplan, M; Keane, D; Kechechyan, A; Kettler, D; Khodyrev, V Yu; Kim, B C; Kiryluk, J; Kisiel, A; Kislov, E M; Klein, S R; Knospe, A G; Kocoloski, A; Koetke, D D; Kollegger, T; Kopytine, M; Kotchenda, L; Kouchpil, V; Kowalik, K L; Kravtsov, P; Kravtsov, V I; Krueger, K; Kuhn, C; Kulikov, A I; Kumar, A; Kurnadi, P; Kuznetsov, A A; Lamont, M A C; Landgraf, J M; Lange, S; LaPointe, S; Laue, F; Lauret, J; Lebedev, A; Lednicky, R; Lee, C-H; Lehocka, S; LeVine, M J; Li, C; Li, Q; Li, Y; Lin, G; Lin, X; Lindenbaum, S J; Lisa, M A; Liu, F; Liu, H; Liu, J; Liu, L; Ljubicic, T; Llope, W J; Longacre, R S; Love, W A; Lu, Y; Ludlam, T; Lynn, D; Ma, G L; Ma, J G; Ma, Y G; Mahapatra, D P; Majka, R; Mangotra, L K; Manweiler, R; Margetis, S; Markert, C; Martin, L; Matis, H S; Matulenko, Yu A; McClain, C J; McShane, T S; Melnick, Yu; Meschanin, A; Millane, J; Miller, M L; Minaev, N G; Mioduszewski, S; Mironov, C; Mischke, A; Mitchell, J; Mohanty, B; Morozov, D A; Munhoz, M G; Nandi, B K; Nattrass, C; Nayak, T K; Nelson, J M; Nepali, C; Netrakanti, P K; Nogach, L V; Nurushev, S B; Odyniec, G; Ogawa, A; Okorokov, V; Oldenburg, M; Olson, D; Pachr, M; Pal, S K; Panebratsev, Y; Pavlinov, A I; Pawlak, T; Peitzmann, T; Perevoztchikov, V; Perkins, C; Peryt, W; Phatak, S C; Planinic, M; Pluta, J; Poljak, N; Porile, N; Poskanzer, A M; Potekhin, M; Potrebenikova, E; Potukuchi, B V K S; Prindle, D; Pruneau, C; Putschke, J; Qattan, I A; Raniwala, R; Raniwala, S; Ray, R L; Relyea, D; Ridiger, A; Ritter, H G; Roberts, J B; Rogachevskiy, O V; Romero, J L; Rose, A; Roy, C; Ruan, L; Russcher, M J; Sahoo, R; Sakrejda, I; Sakuma, T; Salur, S; Sandweiss, J; Sarsour, M; Sazhin, P S; Schambach, J; Scharenberg, R P; Schmitz, N; Seger, J; Selyuzhenkov, I; Seyboth, P; Shabetai, A; Shahaliev, E; Shao, M; Sharma, M; Shen, W Q; Shimanskiy, S S; Sichtermann, E P; Simon, F; Singaraju, R N; Smirnov, N; Snellings, R; Sorensen, P; Sowinski, J; Speltz, J; Spinka, H M; Srivastava, B; Stadnik, A; Stanislaus, T D S; Staszak, D; Stock, R; Strikhanov, M; Stringfellow, B; Suaide, A A P; Suarez, M C; Subba, N L; Sumbera, M; Sun, X M; Sun, Z; Surrow, B; Symons, T J M; Szanto de Toledo, A; Takahashi, J; Tang, A H; Tarnowsky, T; Thomas, J H; Timmins, A R; Timoshenko, S; Tokarev, M; Trainor, T A; Trentalange, S; Tribble, R E; Tsai, O D; Ulery, J; Ullrich, T; Underwood, D G; Van Buren, G; van der Kolk, N; van Leeuwen, M; Vander Molen, A M; Varma, R; Vasilevski, I M; Vasiliev, A N; Vernet, R; Vigdor, S E; Viyogi, Y P; Vokal, S; Voloshin, S A; Waggoner, W T; Wang, F; Wang, G; Wang, J S; Wang, X L; Wang, Y; Watson, J W; Webb, J C; Westfall, G D; Wetzler, A; Whitten, C; Wieman, H; Wissink, S W; Witt, R; Wu, J; Wu, Y; Xu, N; Xu, Q H; Xu, Z; Yepes, P; Yoo, I-K; Yue, Q; Yurevich, V I; Zhan, W; Zhang, H; Zhang, W M; Zhang, Y; Zhang, Z P; Zhao, Y; Zhong, C; Zhou, J; Zoulkarneev, R; Zoulkarneeva, Y; Zubarev, A N; Zuo, J X

2007-09-14

We present first measurements of the phi-meson elliptic flow (v2(pT)) and high-statistics pT distributions for different centralities from radical sNN=200 GeV Au+Au collisions at RHIC. In minimum bias collisions the v2 of the phi meson is consistent with the trend observed for mesons. The ratio of the yields of the Omega to those of the phi as a function of transverse momentum is consistent with a model based on the recombination of thermal s quarks up to pT approximately 4 GeV/c, but disagrees at higher momenta. The nuclear modification factor (R CP) of phi follows the trend observed in the K S 0 mesons rather than in Lambda baryons, supporting baryon-meson scaling. These data are consistent with phi mesons in central Au+Au collisions being created via coalescence of thermalized s quarks and the formation of a hot and dense matter with partonic collectivity at RHIC.

PhySortR: a fast, flexible tool for sorting phylogenetic trees in R.

PubMed

Stephens, Timothy G; Bhattacharya, Debashish; Ragan, Mark A; Chan, Cheong Xin

2016-01-01

A frequent bottleneck in interpreting phylogenomic output is the need to screen often thousands of trees for features of interest, particularly robust clades of specific taxa, as evidence of monophyletic relationship and/or reticulated evolution. Here we present PhySortR, a fast, flexible R package for classifying phylogenetic trees. Unlike existing utilities, PhySortR allows for identification of both exclusive and non-exclusive clades uniting the target taxa based on tip labels (i.e., leaves) on a tree, with customisable options to assess clades within the context of the whole tree. Using simulated and empirical datasets, we demonstrate the potential and scalability of PhySortR in analysis of thousands of phylogenetic trees without a priori assumption of tree-rooting, and in yielding readily interpretable trees that unambiguously satisfy the query. PhySortR is a command-line tool that is freely available and easily automatable.

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.

Charmless and Penguin Decays at CDF

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

Dorigo, Mirco; Collaboration, for the CDF

2010-12-01

Penguin transitions play a key role in the search of New Physics hints in the heavy flavor sector. During the last decade CDF has been exploring this opportunity with a rich study of two-body charmless decays of neutral B mesons into charged final-state particles. After briefly introducing the aspects of this physics peculiar to the hadron collision environment, I report on two interesting results: the first polarization measurement of the B{sub s}{sup 0} {yields} {phi}{phi} decay and the update of the B{sub (s)}{sup 0} {yields} h{sup +}h{prime}{sup -} decays analysis.

Towards a Quantum Memory assisted MDI-QKD node

NASA Astrophysics Data System (ADS)

Namazi, Mehdi; Vallone, Giuseppe; Jordaan, Bertus; Goham, Connor; Shahrokhshahi, Reihaneh; Villoresi, Paolo; Figueroa, Eden

2017-04-01

The creation of large quantum network that permits the communication of quantum states and the secure distribution of cryptographic keys requires multiple operational quantum memories. In this work we present our progress towards building a prototypical quantum network that performs the memory-assisted measurement device independent QKD protocol. Currently our network combines the quantum part of the BB84 protocol with room-temperature quantum memory operation, while still maintaining relevant quantum bit error rates for single-photon level operation. We will also discuss our efforts to use a network of two room temperature quantum memories, receiving, storing and transforming randomly polarized photons in order to realize Bell state measurements. The work was supported by the US-Navy Office of Naval Research, Grant Number N00141410801, the National Science Foundation, Grant Number PHY-1404398 and the Simons Foundation, Grant Number SBF241180.

Development of the Tagger Microscope & Analysis of Spin Density Matrix Elements in gamma-p -> phi-p for the GlueX Experiment

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

Barnes, Alexander E.

The quark model has been successful in classifying the spectrum of mesons observed since the 1960s, however, it fails to explain some of the measured bound states. Lattice QCD predictions have shown that an excited gluonic field may contribute to the quantum numbers of the bound state and form hybrid mesons, qq-bar-g, where g is a constituent gluon. It is possible for some hybrids to possess quantum numbers forbidden by the quark model and are known as \\smoking gun" hybrids due to their lack of mixing with conventional qq-bar states. The GlueX photoproduction experiment at Jefferson Lab in Newport News,more » VA is designed to study hybrid mesons and to map their spectrum. A 12 GeV electron beam produces 9 GeV linearly polarized photons via coherent bremsstrahlung in a diamond radiator which are incident on a liquid H2 target. In order to determine the photon energy, the use of a tagging spectrometer which measures the energy of the post-bremsstrahlung electron is required. The tagger microscope is a scintillating fiber detector designed to measure the energy of electrons corresponding to the polarized photons. The main focus of this work is the design and construction of the tagger microscope electronics as well as the calibration of the microscope within the experiment. Additionally, the analysis of the reaction gamma-p -> phi-p, where phi (1020) -> K+K-, is discussed. This analysis provides a high-level calibration for GlueX in regards to understanding the acceptance and sensitivity of the detectors to mesons with strange quark content. By studying the phi with linearly polarized photons, information on the production mechanism can be extracted. The measurement of the phi spin-density matrix elements are shown and compared with past data which are found to be in agreement.« less

Silicon based quantum dot hybrid qubits

NASA Astrophysics Data System (ADS)

Kim, Dohun

2015-03-01

The charge and spin degrees of freedom of an electron constitute natural bases for constructing quantum two level systems, or qubits, in semiconductor quantum dots. The quantum dot charge qubit offers a simple architecture and high-speed operation, but generally suffers from fast dephasing due to strong coupling of the environment to the electron's charge. On the other hand, quantum dot spin qubits have demonstrated long coherence times, but their manipulation is often slower than desired for important future applications. This talk will present experimental progress of a `hybrid' qubit, formed by three electrons in a Si/SiGe double quantum dot, which combines desirable characteristics (speed and coherence) in the past found separately in qubits based on either charge or spin degrees of freedom. Using resonant microwaves, we first discuss qubit operations near the `sweet spot' for charge qubit operation. Along with fast (>GHz) manipulation rates for any rotation axis on the Bloch sphere, we implement two independent tomographic characterization schemes in the charge qubit regime: traditional quantum process tomography (QPT) and gate set tomography (GST). We also present resonant qubit operations of the hybrid qubit performed on the same device, DC pulsed gate operations of which were recently demonstrated. We demonstrate three-axis control and the implementation of dynamic decoupling pulse sequences. Performing QPT on the hybrid qubit, we show that AC gating yields π rotation process fidelities higher than 93% for X-axis and 96% for Z-axis rotations, which demonstrates efficient quantum control of semiconductor qubits using resonant microwaves. We discuss a path forward for achieving fidelities better than the threshold for quantum error correction using surface codes. This work was supported in part by ARO (W911NF-12-0607), NSF (PHY-1104660), DOE (DE-FG02-03ER46028), and by the Laboratory Directed Research and Development program at Sandia National Laboratories under contract DE-AC04-94AL85000.

Charmless hadronic B decays into a tensor meson

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

Cheng, Hai-Yang; C. N. Yang Institute for Theoretical Physics, State University of New York Stony Brook, Stony Brook, New York 11794; Yang, Kwei-Chou

2011-02-01

Two-body charmless hadronic B decays involving a tensor meson in the final state are studied within the framework of QCD factorization (QCDF). Because of the G-parity of the tensor meson, both the chiral-even and chiral-odd two-parton light-cone distribution amplitudes of the tensor meson are antisymmetric under the interchange of momentum fractions of the quark and antiquark in the SU(3) limit. Our main results are: (i) In the naieve factorization approach, the decays such as B{sup -}{yields}K{sub 2}*{sup 0}{pi}{sup -} and B{sup 0}{yields}K{sub 2}*{sup -}{pi}{sup +} with a tensor meson emitted are prohibited because a tensor meson cannot be created frommore » the local V-A or tensor current. Nevertheless, the decays receive nonfactorizable contributions in QCDF from vertex, penguin and hard spectator corrections. The experimental observation of B{sup -}{yields}K{sub 2}*{sup 0}{pi}{sup -} indicates the importance of nonfactorizable effects. (ii) For penguin-dominated B{yields}TP and TV decays, the predicted rates in naieve factorization are usually too small by 1 to 2 orders of magnitude. In QCDF, they are enhanced by power corrections from penguin annihilation and nonfactorizable contributions. (iii) The dominant penguin contributions to B{yields}K{sub 2}*{eta}{sup (')} arise from the processes: (a) b{yields}sss{yields}s{eta}{sub s} and (b) b{yields}sqq{yields}qK{sub 2}* with {eta}{sub q}=(uu+dd)/{radical}(2) and {eta}{sub s}=ss. The interference, constructive for K{sub 2}*{eta}{sup '} and destructive for K{sub 2}*{eta}, explains why {Gamma}(B{yields}K{sub 2}*{eta}{sup '})>>{Gamma}(B{yields}K{sub 2}*{eta}). (iv) We use the measured rates of B{yields}K{sub 2}*({omega},{phi}) to extract the penguin-annihilation parameters {rho}{sub A}{sup TV} and {rho}{sub A}{sup VT} and the observed longitudinal polarization fractions f{sub L}(K{sub 2}*{omega}) and f{sub L}(K{sub 2}*{phi}) to fix the phases {phi}{sub A}{sup VT} and {phi}{sub A}{sup TV}. (v) The experimental observation that f{sub T}/f{sub L}<<1 for B{yields}K{sub 2}*(1430){phi}, whereas f{sub T}/f{sub L}{approx}1 for B{yields}K{sub 2}*(1430){omega} with f{sub T} being the transverse polarization fraction, can be accommodated in QCDF, but it cannot be dynamically explained at first place. For penguin-dominated B{yields}TV decays, we find f{sub L}(K{sub 2}*{rho}){approx}f{sub L}(K{sub 2}*{omega}){approx}0.65, whereas f{sub L}(K*f{sub 2}){approx}0.93. It will be of great interest to measure f{sub L} for these modes to test QCDF. Theoretically, transverse polarization is expected to be small in tree-dominated B{yields}TV decays except for the a{sub 2}{sup -}{rho}{sup 0}, a{sub 2}{sup -}{rho}{sup +}, K{sub 2}*{sup 0}K*{sup -} and K{sub 2}*{sup 0}K*{sup 0} modes. (vi) For tree-dominated decays, their rates are usually very small except for the a{sub 2}{sup 0}({pi}{sup -},{rho}{sup -}), a{sub 2}{sup +}({pi}{sup -},{rho}{sup -}) and f{sub 2}({pi}{sup -},{rho}{sup -}) modes with branching fractions of order 10{sup -6} or even larger.« less

Exact, E = 0, classical and quantum solutions for general power-law oscillators

NASA Technical Reports Server (NTRS)

Nieto, Michael Martin; Daboul, Jamil

1995-01-01

For zero energy, E = 0, we derive exact, classical and quantum solutions for all power-law oscillators with potentials V(r) = -gamma/r(exp nu), gamma greater than 0 and -infinity less than nu less than infinity. When the angular momentum is non-zero, these solutions lead to the classical orbits (p(t) = (cos mu(phi(t) - phi(sub 0)t))(exp 1/mu) with mu = nu/2 - 1 does not equal 0. For nu greater than 2, the orbits are bound and go through the origin. We calculate the periods and precessions of these bound orbits, and graph a number of specific examples. The unbound orbits are also discussed in detail. Quantum mechanically, this system is also exactly solvable. We find that when nu is greater than 2 the solutions are normalizable (bound), as in the classical case. Further, there are normalizable discrete, yet unbound, states. They correspond to unbound classical particles which reach infinity in a finite time. Finally, the number of space dimensions of the system can determine whether or not an E = 0 state is bound. These and other interesting comparisons to the classical system will be discussed.

Quantum Reactive Scattering of Ultracold K+KRb Reaction: Universality and Chaotic Dynamics

NASA Astrophysics Data System (ADS)

Croft, J. F. E.; Makrides, C.; Li, M.; Petrov, A.; Kendrick, B. K.; Balakrishnan, N.; Kotochigova, S.

2017-04-01

A fundamental question in the study of chemical reactions is how reactions proceed at a collision energy close to absolute zero. This question is no longer hypothetical: quantum degenerate gases of atoms and molecules can now be created at temperatures lower than a few tens of nanoKelvin. In this talk, we discuss the benchmark ultracold reaction between, the most-celebrated ultracold molecule, KRb and K. We report numerically exact quantum-mechanical calculations of the K+KRb reaction on an accurate ab initio ground state potential energy surface of the K2Rb system and compare our results with available experimental data and predictions of universal models. The role of non-additive three-body contributions to the interaction potential is examined and is found to be small for the total reaction rates. However, the rotationally resolved rate coefficients are shown to be sensitive to the short-range interaction potential and follow a Poissonian distribution. This work was supported in part by NSF Grants PHY-1505557 (N.B.), PHY-1619788 (S.K.), ARO MURI Grant No. W911NF-12-1-0476 (N.B. & S.K.), and DOE LDRD Grant No. 20170221ER (B.K.).

Expression, purification and characterization of a phyAm-phyCs fusion phytase*

PubMed Central

Zou, Li-kou; Wang, Hong-ning; Pan, Xin; Tian, Guo-bao; Xie, Zi-wen; Wu, Qi; Chen, Hui; Xie, Tao; Yang, Zhi-rong

2008-01-01

The phyAm gene encoding acid phytase and optimized neutral phytase phyCs gene were inserted into expression vector pPIC9K in correct orientation and transformed into Pichia pastoris in order to expand the pH profile of phytase and decrease the cost of production. The fusion phytase phyAm-phyCs gene was successfully overexpressed in P. pastoris as an active and extracellular phytase. The yield of total extracellular fusion phytase activity is (25.4±0.53) U/ml at the flask scale and (159.1±2.92) U/ml for high cell-density fermentation, respectively. Purified fusion phytase exhibits an optimal temperature at 55 °C and an optimal pH at 5.5~6.0 and its relative activity remains at a relatively high level of above 70% in the range of pH 2.0 to 7.0. About 51% to 63% of its original activity remains after incubation at 75 °C to 95 °C for 10 min. Due to heavy glycosylation, the expressed fusion phytase shows a broad and diffuse band in SDS-PAGE (sodium dodecyl sulfate-polyacrylamide gel electrophoresis). After deglycosylation by endoglycosidase H (EndoHf), the enzyme has an apparent molecular size of 95 kDa. The characterization of the fusion phytase was compared with those of phyCs and phyAm. PMID:18600783

Anomalous electron spin decoherence in an optically pumped quantum dot

NASA Astrophysics Data System (ADS)

Shi, Xiaofeng; Sham, L. J.

2013-03-01

We study the nuclear-spin-fluctuation induced spin decoherence of an electron (SDE) in an optically pumped quantum dot. The SDE is computed in terms of the steady distribution of the nuclear field (SDNF) formed through the hyperfine interaction (HI) with two different nuclear species in the dot. A feedback loop between the optically driven electron spin and the nuclear spin ensemble determines the SDNF [W. Yang and L. J. Sham, Phy. Rev. B 85, 235319(2012)]. Different from that work and others reviewed therein, where a bilinear HI, SαIβ , between the electron (or hole) spin S and the nuclear spin I is used, we use an effective nonlinear interaction of the form SαIβIγ derived from the Fermi-contact HI. Our feedback loop forms a multi-peak SDNF in which the SDE shows remarkable collapses and revivals in nanosecond time scale. Such an anomalous SDE results from a quantum interference effect of the electron Larmor precession in a multi-peak effective magnetic field. In the presence of a bilinear HI that suppresses the nuclear spin fluctuation, the non-Markovian SDE persists whenever there are finite Fermi contact interactions between two or more kinds of nuclei and the electron in the quantum dot. This work is supported by NSF(PHY 1104446) and the US Army Research Office MURI award W911NF0910406.

Leptonic and charged kaon decay modes of the phi meson measured in heavy-ion collisions at the CERN super proton synchrotron.

PubMed

Adamová, D; Agakichiev, G; Antończyk, D; Appelshäuser, H; Belaga, V; Bielcíková, J; Braun-Munzinger, P; Busch, O; Cherlin, A; Damjanovic, S; Dietel, T; Dietrich, L; Drees, A; Esumi, S I; Filimonov, K; Fomenko, K; Fraenkel, Z; Garabatos, C; Glässel, P; Hering, G; Holeczek, J; Krobath, G; Kushpil, V; Ludolphs, W; Maas, A; Marín, A; Milosević, J; Miśkowiec, D; Ortega, R; Panebrattsev, Y; Petchenova, O; Petrácek, V; Radomski, S; Rak, J; Ravinovich, I; Rehak, P; Sako, H; Schmitz, W; Schukraft, J; Sedykh, S; Shimansky, S; Stachel, J; Sumbera, M; Tilsner, H; Tserruya, I; Tsiledakis, G; Wessels, J P; Wienold, T; Wurm, J P; Yurevich, S; Yurevich, V

2006-04-21

We report on results of a measurement of meson production in central Pb-Au collisions at E(lab) = 158A GeV. For the first time in the history of high energy heavy-ion collisions, phi mesons were reconstructed both in the K+K- and the dilepton decay channels in the same experiment. This measurement yields rapidity densities near midrapidity, from the two decay channels, of 2.05 +/- 0.14(stat) +/- 0.25(syst) and 2.04 +/- 0.49(stat) +/- 0.32(syst), respectively. The shape of the measured transverse momentum spectrum is also in close agreement in both decay channels. The data rule out a possible enhancement of the phi yield in the leptonic over the hadronic decay channel of a factor 1.6 or larger at the 95% C.L. This rules out the discrepancy reported in the literature between measurements of the hadronic and dimuon decay channels by two different experiments.

Unimodular Gravity and General Relativity UV divergent contributions to the scattering of massive scalar particles

NASA Astrophysics Data System (ADS)

Gonzalez-Martin, S.; Martin, C. P.

2018-01-01

We work out the one-loop and order κ2 mphi2 UV divergent contributions, coming from Unimodular Gravity and General Relativity, to the S matrix element of the scattering process phi + phi→ phi + phi in a λ phi4 theory with mass mphi. We show that both Unimodular Gravity and General Relativity give rise to the same UV divergent contributions in Dimensional Regularization. This seems to be at odds with the known result that in a multiplicative MS dimensional regularization scheme the General Relativity corrections, in the de Donder gauge, to the beta function, βλ, of the λ coupling do not vanish, whereas the Unimodular Gravity corrections, in a certain gauge, do vanish. Actually, by comparing the UV divergent contributions calculated in this paper with those which give rise to the non-vanishing gravitational corrections to βλ, one readily concludes that the UV divergent contributions that yield the just mentioned non-vanishing gravitational corrections to βλ do not contribute to the UV divergent behaviour of the S matrix element of phi + phi→ phi + phi. This shows that any physical consequence—such as the existence of asymptotic freedom due to gravitational interactions—drawn from the value of βλ is not physically meaningful.

The {alpha}-particle excited scintillation response of the liquid phase epitaxy grown LuAG:Ce thin films

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

Prusa, P.; Cechak, T.; Mares, J. A.

2008-01-28

Liquid phase epitaxy grown Lu{sub 3}Al{sub 5}O{sub 12}:Ce (LuAG:Ce) 20 {mu}m thick films and plate cut from the bulk Czochralski-grown LuAG:Ce crystal were prepared for comparison of photoelectron yield (PhY) and PhY dependence on shaping time (0.5-10 {mu}s). {sup 241}Am ({alpha} particles) was used for excitation. At the 0.5 {mu}s shaping time, the best film shows comparable PhY with the bulk sample. PhY of bulk material increases noticeably more with shaping time than that of the films. Energy resolution of films is better. Influence of Pb{sup 2+} contamination in the films (from the flux) and antisite Lu{sub Al} defect inmore » bulk material is discussed.« less

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

Fujii, M.; Sato, K.; Kimura, K.

Photoelectron spectra due to autoionization for two series of high Rydberg states have been observed for diazabicyclooctane (DABCO) in a supersonic jet. The selection rule of the autoionization has been found to be ..delta..v = -1 for each vibrational mode involved in the Rydberg states, consistent with Berry's theory available for the vibrational autoionization of a polyatomic molecule. The relative autoionization efficiencies Phi/sub a/ for the high Rydberg series have also been determined from two-color MPI and fluorescence dip spectra. The irregular variation of Phi/sub a/ with the principal quantum number n has been found for the two Rydberg series,more » suggesting the irregular variation in their nonradiative rates« less

FerriBRIGHT: a rationally designed fluorescent probe for redox active metals.

PubMed

Kennedy, Daniel P; Kormos, Chad M; Burdette, Shawn C

2009-06-24

The novel catechol-BODIPY dyad, 8-(3,4-dihydroxyphenyl)-2,6-bis(ethoxycarbonyl)-1,3,5,7-tetramethyl-4,4-difluoro-4-bora-3a,4a-diaza-s-indacene (FerriBRIGHT) was rationally designed with the aid of computational methods. FerriBRIGHT could be prepared by standard one-pot synthesis of BODIPY fluorophores from 3,4-bis(benzyloxy)benzaldehyde (1) and 3,5-dimethyl-4-(ethoxycarbonyl)pyrrole (3); however, isolating the dipyrrin intermediate 8-[3,4-bis(benzyloxy)phenyl]-2,6-bis(ethoxycarbonyl)-1,3,5,7-tetramethyl-4,4-diaza-s-indacene (7) prior to reaction with excess BF(3).OEt(2) led to marked improvements in the isolated overall yield of the desired compound. In addition to these improvements in fluorophore synthesis, microwave-assisted palladium-catalyzed hydrogenolysis of benzyl ethers was used to reduce reaction times and catalyst loading in preparation of the desired compound. When FerriBRIGHT is exposed to excess FeCl(3), CuCl(2), [Co(NH(3))(5)Cl]Cl(2), 2,3-dichloro-5,6-dicyanobenzoquinone, or ceric ammonium nitrate in methanol, a significant enhancement of fluorescence is observed. FerriBRIGHT-Q, the product resulting from the oxidation of the pendant catechol to the corresponding quinone, was found to be the emissive species. FerriBRIGHT-Q was synthesized independently, isolated, and fully characterized to allow for direct comparison with the spectroscopic data acquired in solution. Biologically relevant reactive oxygen species, such as H(2)O(2), (*)OH, (1)O(2), O(2)(*-), and bleach (NaOCl), failed to cause any changes in the emission intensity of FerriBRIGHT. In accordance with the quantum mechanical calculations, the quantum yield of fluorescence for FerriBRIGHT (Phi(fl) approximately 0) and FerriBRIGHT-Q (Phi(fl) = 0.026, lambda(ex)/lambda(em) = 490 nm/510 nm) suggests that photoinduced electron transfer between the catechol and the BODIPY dye is attenuated upon oxidation, which results in fluorescence enhancement. Binding studies of FerriBRIGHT with Ga(NO(3))(3), a redox-inactive analogue of Fe(III), provided conditional binding constant log beta(12)' = 13.3 +/- 0.2 for a [Ga(FerriBRIGHT)(2)](-) complex. A 2.8-fold enhancement of fluorescence intensity upon addition of Ga(III) to FerriBRIGHT suggests the possibility of metal ion sensing with this new class of compounds.

Spacetime Replication of Quantum Information Using (2 , 3) Quantum Secret Sharing and Teleportation

NASA Astrophysics Data System (ADS)

Wu, Yadong; Khalid, Abdullah; Davijani, Masoud; Sanders, Barry

The aim of this work is to construct a protocol to replicate quantum information in any valid configuration of causal diamonds and assess resources required to physically realize spacetime replication. We present a set of codes to replicate quantum information along with a scheme to realize these codes using continuous-variable quantum optics. We use our proposed experimental realizations to determine upper bounds on the quantum and classical resources required to simulate spacetime replication. For four causal diamonds, our implementation scheme is more efficient than the one proposed previously. Our codes are designed using a decomposition algorithm for complete directed graphs, (2 , 3) quantum secret sharing, quantum teleportation and entanglement swapping. These results show the simulation of spacetime replication of quantum information is feasible with existing experimental methods. Alberta Innovates, NSERC, China's 1000 Talent Plan and the Institute for Quantum Information and Matter, which is an NSF Physics Frontiers Center (NSF Grant PHY-1125565) with support of the Gordon and Betty Moore Foundation (GBMF-2644).

Irreducible normalizer operators and thresholds for degenerate quantum codes with sublinear distances

NASA Astrophysics Data System (ADS)

Pryadko, Leonid P.; Dumer, Ilya; Kovalev, Alexey A.

2015-03-01

We construct a lower (existence) bound for the threshold of scalable quantum computation which is applicable to all stabilizer codes, including degenerate quantum codes with sublinear distance scaling. The threshold is based on enumerating irreducible operators in the normalizer of the code, i.e., those that cannot be decomposed into a product of two such operators with non-overlapping support. For quantum LDPC codes with logarithmic or power-law distances, we get threshold values which are parametrically better than the existing analytical bound based on percolation. The new bound also gives a finite threshold when applied to other families of degenerate quantum codes, e.g., the concatenated codes. This research was supported in part by the NSF Grant PHY-1416578 and by the ARO Grant W911NF-11-1-0027.

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

Mack, Philipp; /Karlsruhe U., EKP

We report on the search for B{sup 0}{sub s}{yields}{mu}{sup +}{mu}{sup -}, B{sup 0}{sub d}{yields}{mu}{sup +}{mu}{sup -} decays and b{yields} s{mu}{sup +}{mu}{sup -} transitions in exclusive decays of B mesons using the CDF II detector at the Fermilab Tevatron Collider. Using 2 fb{sup -1} of Run II data we find upper limits on the branching fractions {beta}(B{sup 0}{sub s}{yields}{mu}{sup +}{mu}{sup -})<5.8 x 10{sup -8} and {beta}(B{sup 0}{sub d}{yields}{mu}{sup +}{mu}{sup -})<1.8 x 10{sup -8} at 95% confidence level. The results for the branching fractions of the b{yields} s{mu}{sup +}{mu}{sup -} transitions using 924 pb{sup -1} of Run II data are {beta}(B{sup +}{yields}{mu}{supmore » +}{mu}{sup -}K{sup +})=(0.60{+-}0.15{+-}0.04) x 10{sup -6}, {beta}(B{sup 0}{sub d}{yields}{mu}{sup +}{mu}{sup -}K{sup *0})=(0.82{+-}0.31{+-}0.10) x 10{sup -6} and {beta}(B{sup 0}{sub s}{yields} {mu}{sup +}{mu}{sup -}{phi})/{beta}(B{sup 0}{sub s}{yields}J/{psi}{phi}) < 2.61 x 10{sup -3} at 95% confidence level.« less

Public health intelligence and the detection of potential pandemics.

PubMed

French, Martin; Mykhalovskiy, Eric

2013-02-01

This article considers contemporary developments in public health intelligence (PHI), especially their focus on health events of pandemic potential. It argues that the sociological study of PHI can yield important insights for the sociology of pandemics. PHI aims to detect health events as (or even before) they unfold. Whilst its apparatuses envelope traditional public health activities, such as epidemiological surveillance, they increasingly extend to non-traditional public health activities such as data-mining in electronically mediated social networks. With a focus on non-traditional PHI activities, the article first situates the study of PHI in relation to the sociology of public health. It then discusses the conceptualisation and actualisation of pandemics, reflecting on how public health professionals and organisations must equip themselves with diverse allies in order to realise the claims they make about pandemic phenomena. Finally, using the analytic tools of actor-network theory, sites for future empirical research that can contribute to the sociology of pandemics are suggested. © 2012 The Authors. Sociology of Health & Illness © 2012 Foundation for the Sociology of Health & Illness/Blackwell Publishing Ltd.

Leakage of The Quantum Dot Hybrid Qubit in The Strong Driving Regime

NASA Astrophysics Data System (ADS)

Yang, Yuan-Chi; Friesen, Mark; Coppersmith, S. N.

Recent experimental demonstrations of high-fidelity single-qubit gates suggest that the quantum dot hybrid qubit is a promising candidate for large-scale quantum computing. The qubit is comprised of three electrons in a double quantum dot, and can be protected from charge noise by operating in an extended sweet-spot regime. Gate operations are based on exchange interactions mediated by an excited state. However, strong resonant driving causes unwanted leakage into the excited state. Here, we theoretically analyze leakage caused by strong driving, and explore methods for increasing gate fidelities. This work was supported in part by ARO (W911NF-12-0607), NSF (PHY-1104660), ONR (N00014-15-1-0029), and the University of Wisconsin-Madison.

Measurement of branching fraction and time-dependent CP asymmetry parameters in B{sup 0}{yields}D*{sup +}D*{sup -}K{sub S}{sup 0} decays

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

Dalseno, J.; Moloney, G. R.; Sevior, M. E.

2007-10-01

We present a measurement of the branching fraction and time-dependent CP violation parameters for B{sup 0}{yields}D*{sup +}D*{sup -}K{sub S}{sup 0} decays. These results are obtained from a 414 fb{sup -1} data sample that contains 449x10{sup 6} BB pairs collected at the {upsilon}(4S) resonance with the Belle detector at the KEKB asymmetric-energy e{sup +}e{sup -} collider. We obtain the branching fraction, B(B{sup 0}{yields}D*{sup +}D*{sup -}K{sub S}{sup 0})=[3.4{+-}0.4(stat){+-}0.7(syst)]x10{sup -3}, which is in agreement with the current world average. We also obtain an upper limit on the product branching fraction for a possible two-body decay, B(B{sup 0}{yields}D{sub s1}{sup +}(2536)D*{sup -})B(D{sub s1}{sup +}(2536){yields}D*{sup +}K{submore » S}{sup 0})<7.1x10{sup -4} (90% CL). In the traditional 2-parameter time-dependent CP analysis, we measure the CP violation parameters, A{sub CP}=-0.01{sub -0.28}{sup +0.28}(stat){+-}0.09(syst), Dsin2{phi}{sub 1}=0.06{sub -0.44}{sup +0.45}(stat){+-}0.06(syst). No evidence for either mixing-induced or direct CP violation is found. In a 3-parameter fit sensitive to cos2{phi}{sub 1} performed in the half-Dalitz spaces, s{sup -}{<=}s{sup +} and s{sup -}>s{sup +}, where s{sup {+-}}{identical_to}m{sup 2}(D*{sup {+-}}K{sub S}{sup 0}), we extract the CP violation parameters, J{sub c}/J{sub 0}=0.60{sub -0.28}{sup +0.25}(stat){+-}0.08(syst), 2J{sub s1}/J{sub 0}sin2{phi}{sub 1}=-0.17{sub -0.42}{sup +0.42}(stat){+-}0.09(syst), 2J{sub s2}/J{sub 0}cos2{phi}{sub 1}=-0.23{sub -0.41}{sup +0.43}(stat){+-}0.13(syst). A large value of J{sub c}/J{sub 0} would indicate a significant resonant contribution from a broad unknown D{sub s}**{sup +} state. Although the sign of the factor, 2J{sub s2}/J{sub 0}, can be deduced from theory, no conclusion can be drawn regarding the sign of cos2{phi}{sub 1} given the errors.« less

Dynamics of short-term acclimation to UV radiation in marine diatoms.

PubMed

Fouqueray, Manuela; Mouget, Jean-Luc; Morant-Manceau, Annick; Tremblin, Gérard

2007-11-12

In order to investigate the dynamics of the acclimation of marine diatoms to ultraviolet radiation (UVR), Amphora coffeaeformis, Odontella aurita and Skeletonema costatum were exposed for 5 h per day to a combination of UVA and UVB (UVBR/UVAR ratio 4.5%) with a total UVR daily dose of 110 kJ m(-2), which is equivalent to that observed in the natural environment. This treatment was applied in the middle of the photoperiod and was repeated on five successive days. During the UVR treatment, chlorophyll fluorescence parameters were monitored, damage and repair constants were calculated from effective quantum yield values (phi(PSII)), and rapid light curves (electron transport rate versus irradiance curves using short light steps of different intensity) were plotted to determine the maximum relative electron transport rate (rETR(max)) and maximum light use efficiency (alpha). In all species the growth rate was lower than control from day 1-3, but increased thereafter, except for S. costatum. The cellular chlorophyll a content increased significantly with repeated daily exposure to UVR for A. coffeaeformis only. In all species, the fluorescence parameters (F(m), the maximum fluorescence level measured in the dark, phi(PSII), rETR(max) and alpha) decreased during UVR exposure, in contrast to F(0) (the minimum fluorescence level measured in the dark). The response to UVR stress was species-specific. S. costatum was very sensitive, and failed to survive for more than three days, whereas A. coffeaeformis and O. aurita were able to acclimate to UVR stress. These two species used different strategies. In A. coffeaeformis, the repair constant was lower than the damage constant, but phi(PSII) values returned to baseline values at the beginning of each experimental day, indicating that an effective active recovery process occurred after stress. In O. aurita, the repair processes took place during the stress, and could account for the UVR tolerance of this species.

Method to compute the stress-energy tensor for a quantum field outside a black hole that forms from collapse

NASA Astrophysics Data System (ADS)

Anderson, Paul; Evans, Charles

2017-01-01

A method to compute the stress-energy tensor for a quantized massless minimally coupled scalar field outside the event horizon of a 4-D black hole that forms from the collapse of a spherically symmetric null shell is given. The method is illustrated in the corresponding 2-D case which is mathematically similar but is simple enough that the calculations can be done analytically. The approach to the Unruh state at late times is discussed. National Science Foundation Grant No. PHY-1505875 to Wake Forest University and National Science Foundation Grant No. PHY-1506182 to the University of North Carolina, Chapel Hill

The response of growth and patulin production of postharvest pathogen Penicillium expansum to exogenous potassium phosphite treatment.

PubMed

Lai, Tongfei; Wang, Ying; Fan, Yaya; Zhou, Yingying; Bao, Ying; Zhou, Ting

2017-03-06

In this study, the effects of exogenous potassium phosphite (Phi) on growth and patulin production of postharvest pathogen Penicillium expansum were assessed. The results indicated that P. expansum under 5mmol/L Phi stress presented obvious development retardation, yield reduction of patulin and lower infectivity to apple fruit. Meanwhile, expression analysis of 15 genes related to patulin biosynthesis suggested that Phi mainly affected the early steps of patulin synthetic route at transcriptional level. Furthermore, a global view of proteome and transcriptome alteration of P. expansum spores during 6h of Phi stress was evaluated by iTRAQ (isobaric tags for relative and absolute quantitation) and RNA-seq (RNA sequencing) approaches. A total of 582 differentially expressed proteins (DEPs) and 177 differentially expressed genes (DEGs) were acquired, most of which participated in carbohydrate metabolism, amino acid metabolism, lipid metabolism, genetic information processing and biosynthesis of secondary metabolites. Finally, 39 overlapped candidates were screened out through correlational analysis between iTRAQ and RNA-seq datasets. These findings will afford more precise and directional clues to explore the inhibitory mechanism of Phi on growth and patulin biosynthesis of P. expansum, and be beneficial to develop effective controlling approaches based on Phi. Copyright © 2016 Elsevier B.V. All rights reserved.

The Pathogen-Host Interactions database (PHI-base): additions and future developments

PubMed Central

Urban, Martin; Pant, Rashmi; Raghunath, Arathi; Irvine, Alistair G.; Pedro, Helder; Hammond-Kosack, Kim E.

2015-01-01

Rapidly evolving pathogens cause a diverse array of diseases and epidemics that threaten crop yield, food security as well as human, animal and ecosystem health. To combat infection greater comparative knowledge is required on the pathogenic process in multiple species. The Pathogen-Host Interactions database (PHI-base) catalogues experimentally verified pathogenicity, virulence and effector genes from bacterial, fungal and protist pathogens. Mutant phenotypes are associated with gene information. The included pathogens infect a wide range of hosts including humans, animals, plants, insects, fish and other fungi. The current version, PHI-base 3.6, available at http://www.phi-base.org, stores information on 2875 genes, 4102 interactions, 110 host species, 160 pathogenic species (103 plant, 3 fungal and 54 animal infecting species) and 181 diseases drawn from 1243 references. Phenotypic and gene function information has been obtained by manual curation of the peer-reviewed literature. A controlled vocabulary consisting of nine high-level phenotype terms permits comparisons and data analysis across the taxonomic space. PHI-base phenotypes were mapped via their associated gene information to reference genomes available in Ensembl Genomes. Virulence genes and hotspots can be visualized directly in genome browsers. Future plans for PHI-base include development of tools facilitating community-led curation and inclusion of the corresponding host target(s). PMID:25414340

Broad-spectrum inhibition of Phytophthora infestans by fungal endophytes

PubMed Central

von Dahlen, Janina K; Schnake, Anika; Ginschel, Sarah; Schulz, Barbara; Rose, Laura E

2018-01-01

ABSTRACT Phytophthora infestans is a devastating pathogen of tomato and potato. It readily overcomes resistance genes and applied agrochemicals and hence even today causes large yield losses. Fungal endophytes provide a largely unexplored avenue of control of Phy. infestans. Not only do endophytes produce a wide array of bioactive metabolites, they may also directly compete with and defeat pathogens in planta. Here, we tested 12 fungal endophytes isolated from different plant species in vitro for their production of metabolites with anti- Phytophthora activity. Four well-performing isolates were evaluated for their ability to suppress nine isolates of Phy. infestans on agar medium and in planta. Two endophytes reliably inhibited all Phy. infestans isolates on agar medium, of which Phoma eupatorii isolate 8082 was the most promising. It nearly abolished infection by Phy. infestans in planta. Our data indicate a role for the production of anti-Phytophthora compounds by the fungus and/or an enhanced plant defense response, as evident by an enhanced anthocyanin production. Here, we present a potential biocontrol agent, which can inhibit a broad-spectrum of Phy. infestans isolates. Such broadly acting inhibition is ideal, because it allows for effective control of genetically diverse isolates and may slow the adaptation of Phy. infestans. PMID:29528408

Weyl current, scale-invariant inflation, and Planck scale generation

DOE PAGES

Ferreira, Pedro G.; Hill, Christopher T.; Ross, Graham G.

2017-02-08

Scalar fields,more » $$\\phi$$ i, can be coupled nonminimally to curvature and satisfy the general criteria: (i) the theory has no mass input parameters, including M P=0; (ii) the $$\\phi$$ i have arbitrary values and gradients, but undergo a general expansion and relaxation to constant values that satisfy a nontrivial constraint, K($$\\phi$$ i)=constant; (iii) this constraint breaks scale symmetry spontaneously, and the Planck mass is dynamically generated; (iv) there can be adequate inflation associated with slow roll in a scale-invariant potential subject to the constraint; (v) the final vacuum can have a small to vanishing cosmological constant; (vi) large hierarchies in vacuum expectation values can naturally form; (vii) there is a harmless dilaton which naturally eludes the usual constraints on massless scalars. Finally, these models are governed by a global Weyl scale symmetry and its conserved current, K μ. At the quantum level the Weyl scale symmetry can be maintained by an invariant specification of renormalized quantities.« less

Non-Gaussian microwave background fluctuations from nonlinear gravitational effects

NASA Technical Reports Server (NTRS)

Salopek, D. S.; Kunstatter, G. (Editor)

1991-01-01

Whether the statistics of primordial fluctuations for structure formation are Gaussian or otherwise may be determined if the Cosmic Background Explorer (COBE) Satellite makes a detection of the cosmic microwave-background temperature anisotropy delta T(sub CMB)/T(sub CMB). Non-Gaussian fluctuations may be generated in the chaotic inflationary model if two scalar fields interact nonlinearly with gravity. Theoretical contour maps are calculated for the resulting Sachs-Wolfe temperature fluctuations at large angular scales (greater than 3 degrees). In the long-wavelength approximation, one can confidently determine the nonlinear evolution of quantum noise with gravity during the inflationary epoch because: (1) different spatial points are no longer in causal contact; and (2) quantum gravity corrections are typically small-- it is sufficient to model the system using classical random fields. If the potential for two scalar fields V(phi sub 1, phi sub 2) possesses a sharp feature, then non-Gaussian fluctuations may arise. An explicit model is given where cold spots in delta T(sub CMB)/T(sub CMB) maps are suppressed as compared to the Gaussian case. The fluctuations are essentially scale-invariant.

Vacuum-polarization effects in global monopole space-times

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

Mazzitelli, F.D.; Lousto, C.O.

1991-01-15

The gravitational effect produced by a global monopole may be approximated by a solid deficit angle. As a consequence, the energy-momentum tensor of a quantum field will have a nonzero vacuum expectation value. Here we study this vacuum-polarization effect'' around the monopole. We find explicit expressions for both {l angle}{phi}{sup 2}{r angle}{sub ren} and {l angle}{ital T}{sub {mu}{nu}}{r angle}{sub ren} for a massless scalar field. The back reaction of the quantum field on the monopole metric is also investigated.

Cross Sections for the Reactions e+e to K+ K- pi+pi-, K+ K- pi0pi0, and K+ K- K+ K- Measured Using Initial-State Radiation

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

Lees, J.P.; Poireau, V.; Prencipe, E.

2011-08-19

We study the processes e{sup +}e{sup -} {yields} K{sup +}K{sup -}{pi}{sup +}{pi}-{gamma}, K{sup +}K{sup -}{pi}{sup 0}{pi}{sup 0}{gamma}, and K{sup +}K{sup -}K{sup +}K{sup -}{gamma}, where the photon is radiated from the initial state. About 84000, 8000, and 4200 fully reconstructed events, respectively, are selected from 454 fb{sup -1} of BABAR data. The invariant mass of the hadronic final state defines the e{sup +}e{sup -} center-of-mass energy, so that the K{sup +}K{sup -}{pi}{sup +}{pi}{sup -}{gamma} data can be compared with direct measurements of the e{sup +}e{sup -} {yields} K{sup +}K{sup -}{pi}{sup +}{pi}{sup -} reaction. No direct measurements exist for the e{sup +}e{supmore » -} {yields} K{sup +}K{sup -}{pi}{sup 0}{pi}{sup 0} or e{sup +}e{sup -} {yields} K{sup +}K{sup -}K{sup +}K{sup -} reactions, and we present an update of our previous result with doubled statistics. Studying the structure of these events, we find contributions from a number of intermediate states, and extract their cross sections. In particular, we perform a more detailed study of the e{sup +}e{sup -} {yields} {phi}(1020){pi}{pi}{gamma} reaction, and confirm the presence of the Y (2175) resonance in the {phi}(1020)f{sub 0}(980) and K{sup +}K{sup -} f{sub 0}(980) modes. In the charmonium region, we observe the J/{psi} in all three final states and in several intermediate states, as well as the {phi}(2S) in some modes, and measure the corresponding branching fractions.« less

Correlation between lifetime heterogeneity and kinetics heterogeneity during chlorophyll fluorescence induction in leaves: 1. Mono-frequency phase and modulation analysis reveals a conformational change of a PSII pigment complex during the IP thermal phase.

PubMed

Moise, Nicolae; Moya, Ismaël

2004-06-28

The relationship between the fluorescence lifetime (tau) and yield (Phi) obtained in phase and modulation fluorometry at 54 MHz during the chlorophyll fluorescence induction in dark-adapted leaves under low actinic light has been investigated. Three typical phases have been identified: (i) linear during the OI photochemical rise, (ii) convex curvature during the subsequent IP thermal rise, and (iii) linear during the PS slow decay. A similar relationship has been obtained in the fluorescence induction for the fluorescence yield measured at 685 nm plotted versus the fluorescence yield measured at 735 nm. A spectrally resolved analysis shows that the curvature of the tau-Phi relationship is not due to chlorophyll fluorescence reabsorption effects. Several other hypotheses are discussed and we conclude that the curvature of the tau-Phi relationship is due to a variable and transitory nonphotochemical quenching. We tentatively propose that this quenching results from a conformational change of a pigment-protein complex of Photosystem II core antenna during the IP phase and could explain both spectral and temporal transitory changes of the fluorescence. A variable blue shift of the 685 nm peak of the fluorescence spectrum during the IP phase has been observed, supporting this hypothesis.

Effects of Fuel Distribution on Detonation Tube Performance

NASA Technical Reports Server (NTRS)

Perkins, Hugh Douglas

2002-01-01

A pulse detonation engine (PDE) uses a series of high frequency intermittent detonation tubes to generate thrust. The process of filling the detonation tube with fuel and air for each cycle may yield non-uniform mixtures. Lack of mixture uniformity is commonly ignored when calculating detonation tube thrust performance. In this study, detonation cycles featuring idealized non-uniform H2/air mixtures were analyzed using the SPARK two-dimensional Navier-Stokes CFD code with 7-step H2/air reaction mechanism. Mixture non-uniformities examined included axial equivalence ratio gradients, transverse equivalence ratio gradients, and partially fueled tubes. Three different average test section equivalence ratios (phi), stoichiometric (phi = 1.00), fuel lean (phi = 0.90), and fuel rich (phi = 1.10), were studied. All mixtures were detonable throughout the detonation tube. It was found that various mixtures representing the same test section equivalence ratio had specific impulses within 1 percent of each other, indicating that good fuel/air mixing is not a prerequisite for optimal detonation tube performance.

Restoration of prostaglandin E2-producing splenic macrophages in sup 89 Sr-treated mice with bone marrow from Corynebacterium parvum primed donors

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

Shibata, Y.

1989-05-01

Administration of Corynebacterium parvum (CP), 56 mg/kg ip to CBA/J mice effected the induction of prostaglandin E2 (PGE2) producing macrophages (M phi) in the bone marrow and the spleen. Maximal release of PGE2 from M phi cultured in vitro with calcium ionophore A23187 for 2 h was reached by marrow M phi removed on 5 days after CP (450 ng/mg cell protein), and by splenic M phi 9 days after CP (400 ng/mg). Neither M phi population, however, yielded more than 6.0 ng/mg leukotriene C4. To assess ontogenic relationships mice were depleted of bone marrow and blood monocytes by ivmore » injection of the bone-seeking isotope, 89Sr. CP was given at several points before or after bone marrow cell depletion. PGE2 production by splenic M phi harvested on day 9 after CP was profoundly impaired when CP was administered either concurrently with or 3 days after 89Sr. When CP was administered 1, 3, 5, and 7 days before 89Sr, however, the induction of PGE2-producing M phi in the spleen was unaffected. To determine whether bone marrow cells from CP-injected donors can restore PGE2-producing splenic M phi (PGSM) in 89Sr-mice, recipient mice which had and had not received CP 3 days after 89Sr were transfused with 5 x 10(6) syngeneic bone marrow cells from donor mice prepared at varying intervals after CP administration. The results clearly indicate the capacity of bone marrow cells harvested on either day 1 or 2 following CP to restore PGSM in CP-primed, but not unprimed, recipients.« less

Using time reversal to detect entanglement and spreading of quantum information

NASA Astrophysics Data System (ADS)

Gaerttner, Martin

2017-04-01

Characterizing and understanding the states of interacting quantum systems and their non-equilibrium dynamics is the goal of quantum simulation. For this it is crucial to find experimentally feasible means for quantifying how entanglement and correlation build up and spread. The ability of analog quantum simulators to reverse the unitary dynamics of quantum many-body systems provides new tools in this quest. One such tool is the multiple-quantum coherence (MQC) spectrum previously used in NMR spectroscopy which can now be studied in so far inaccessible parameter regimes near zero temperature in highly controllable environments. I present recent progress in relating the MQC spectrum to established entanglement witnesses such as quantum Fisher information. Recognizing the MQC as out-of-time-order correlation functions, which quantify the spreading, or scrambling, of quantum information, allows us to establish a connection between these quantities and multi-partite entanglement. I will show recent experimental results obtained with a trapped ion quantum simulator and a spinor BEC illustrating the power of time reversal protocols. Supported by: JILA-NSF-PFC-1125844, NSF-PHY-1521080, ARO, AFOSR, AFOSR-MURI, DARPA, NIST.

Sympathetic cooling of nanospheres with cold atoms

NASA Astrophysics Data System (ADS)

Montoya, Cris; Witherspoon, Apryl; Ranjit, Gambhir; Casey, Kirsten; Kitching, John; Geraci, Andrew

2016-05-01

Ground state cooling of mesoscopic mechanical structures could enable new hybrid quantum systems where mechanical oscillators act as transducers. Such systems could provide coupling between photons, spins and charges via phonons. It has recently been shown theoretically that optically trapped dielectric nanospheres could reach the ground state via sympathetic cooling with trapped cold atoms. This technique can be beneficial in cases where cryogenic operation of the oscillator is not practical. We describe experimental advances towards coupling an optically levitated dielectric nanosphere to a gas of cold Rubidium atoms. The sphere and the cold atoms are in separate vacuum chambers and are coupled using a one-dimensional optical lattice. This work is partially supported by NSF, Grant Nos. PHY-1205994,PHY-1506431.

The Pathogen-Host Interactions database (PHI-base): additions and future developments.

PubMed

Urban, Martin; Pant, Rashmi; Raghunath, Arathi; Irvine, Alistair G; Pedro, Helder; Hammond-Kosack, Kim E

2015-01-01

Rapidly evolving pathogens cause a diverse array of diseases and epidemics that threaten crop yield, food security as well as human, animal and ecosystem health. To combat infection greater comparative knowledge is required on the pathogenic process in multiple species. The Pathogen-Host Interactions database (PHI-base) catalogues experimentally verified pathogenicity, virulence and effector genes from bacterial, fungal and protist pathogens. Mutant phenotypes are associated with gene information. The included pathogens infect a wide range of hosts including humans, animals, plants, insects, fish and other fungi. The current version, PHI-base 3.6, available at http://www.phi-base.org, stores information on 2875 genes, 4102 interactions, 110 host species, 160 pathogenic species (103 plant, 3 fungal and 54 animal infecting species) and 181 diseases drawn from 1243 references. Phenotypic and gene function information has been obtained by manual curation of the peer-reviewed literature. A controlled vocabulary consisting of nine high-level phenotype terms permits comparisons and data analysis across the taxonomic space. PHI-base phenotypes were mapped via their associated gene information to reference genomes available in Ensembl Genomes. Virulence genes and hotspots can be visualized directly in genome browsers. Future plans for PHI-base include development of tools facilitating community-led curation and inclusion of the corresponding host target(s). © The Author(s) 2014. Published by Oxford University Press on behalf of Nucleic Acids Research.

Search for charmonium and charmoniumlike states in {Upsilon}(2S) radiative decays

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

Wang, X. L.; Yuan, C. Z.; Wang, P.

2011-10-01

Using a sample of 158x10{sup 6} {Upsilon}(2S) events collected with the Belle detector, charmonium and charmoniumlike states with even charge parity are searched for in {Upsilon}(2S) radiative decays. No significant {chi}{sub cJ} or {eta}{sub c} signal is observed, and the following upper limits at 90% confidence level (C. L.) are obtained: B({Upsilon}(2S){yields}{gamma}{chi}{sub c0})<1.0x10{sup -4}, B({Upsilon}(2S){yields}{gamma}{chi}{sub c1})<3.6x10{sup -6}, B({Upsilon}(2S){yields}{gamma}{chi}{sub c2})<1.5x10{sup -5}, and B({Upsilon}(2S){yields}{gamma}{eta}{sub c})<2.7x10{sup -5}. No significant signal of any charmoniumlike state is observed, and we obtain the limits B({Upsilon}(2S){yields}{gamma}X(3872))xB(X(3872){yields}{pi}{sup +}{pi}{sup -}J/{psi})<0.8x10{sup -6}, B({Upsilon}(2S){yields}{gamma}X(3872))x B(X(3872){yields}{pi}{sup +}{pi}{sup -}{pi}{sup 0}J/{psi})<2.4x10{sup -6}, B({Upsilon}(2S){yields}{gamma}X(3915))xB(X(3915){yields}{omega}J/{psi})<2.8x10{sup -6}, B({Upsilon}(2S){yields}{gamma}Y(4140))xB(Y(4140){yields}{phi}J/{psi}))<1.2x10{sup -6}, and B({Upsilon}(2S){yields}{gamma}X(4350))xB(X(4350){yields}{phi}J/{psi}))<1.3x10{sup -6} at 90% C. L.

Quantum lattice model solver HΦ

NASA Astrophysics Data System (ADS)

Kawamura, Mitsuaki; Yoshimi, Kazuyoshi; Misawa, Takahiro; Yamaji, Youhei; Todo, Synge; Kawashima, Naoki

2017-08-01

HΦ [aitch-phi ] is a program package based on the Lanczos-type eigenvalue solution applicable to a broad range of quantum lattice models, i.e., arbitrary quantum lattice models with two-body interactions, including the Heisenberg model, the Kitaev model, the Hubbard model and the Kondo-lattice model. While it works well on PCs and PC-clusters, HΦ also runs efficiently on massively parallel computers, which considerably extends the tractable range of the system size. In addition, unlike most existing packages, HΦ supports finite-temperature calculations through the method of thermal pure quantum (TPQ) states. In this paper, we explain theoretical background and user-interface of HΦ. We also show the benchmark results of HΦ on supercomputers such as the K computer at RIKEN Advanced Institute for Computational Science (AICS) and SGI ICE XA (Sekirei) at the Institute for the Solid State Physics (ISSP).

Experimental implementation of the Bacon-Shor code with 10 entangled photons

NASA Astrophysics Data System (ADS)

Gimeno-Segovia, Mercedes; Sanders, Barry C.

The number of qubits that can be effectively controlled in quantum experiments is growing, reaching a regime where small quantum error-correcting codes can be tested. The Bacon-Shor code is a simple quantum code that protects against the effect of an arbitrary single-qubit error. In this work, we propose an experimental implementation of said code in a post-selected linear optical setup, similar to the recently reported 10-photon GHZ generation experiment. In the procedure we propose, an arbitrary state is encoded into the protected Shor code subspace, and after undergoing a controlled single-qubit error, is successfully decoded. BCS appreciates financial support from Alberta Innovates, NSERC, China's 1000 Talent Plan and the Institute for Quantum Information and Matter, which is an NSF Physics Frontiers Center(NSF Grant PHY-1125565) with support of the Moore Foundation(GBMF-2644).

Conformationally constrained dipeptide surrogates with aromatic side-chains: synthesis of 4-aryl indolizidin-9-one amino acids by conjugate addition to a common alpha,omega-diaminoazelate enone intermediate.

PubMed

Cluzeau, Jérôme; Lubell, William D

2004-03-05

Four methyl 9-oxo-8-(N-(Boc)-amino)-4-phenyl-1-azabicyclo[4.3.0]nonane carboxylates (11, 4-Ph-I(9)aa-OMe) were synthesized from (2S,8S,5E)-di-tert-butyl-4-oxo-5-ene-2,8-bis[N-(PhF)amino]azelate [(5E)-7, PhF = 9-(9-phenylfluorenyl)] via a seven-step process featuring a conjugate addition/reductive amination/lactam cyclization sequence. Various nucleophiles were used in the conjugate addition reactions on enone (5E)-7 as a general route for making alpha,omega-diaminoazelates possessing different substituents in good yield albeit low diastereoselectivity except in the case of aryl Grignard reagents (9/1 to 15/1 drs). 6-Phenylazelates (6S)-8d and (6R)-8d were separated by chromatography and diastereoselective precipitation and independently transformed into 4-Ph-I(9)aa-OMe. From (6S)-8d, (2S,4R,6R,8S)-4-Ph-I(9)aa-OMe 11 was prepared selectively in 51% yield. Reductive amination of (6R)-8d provided the desired pipecolates 9 along with desamino compound 10, which was minimized by performing the hydrogenation in the presence of ammonium acetate. Subsequent ester exchange, lactam cyclization, and amine protection provided three products (2R,4S,6S,8R)-, (2R,4S,6S,8S)-, and (2S,4S,6R,8S)-4-Ph-I(9)aa-OMe 11 in 10, 6, and 6% yields, respectively, from (6R)-8d. Ester hydrolysis of (2S,4R,6R,8S)-11 furnished 4-phenyl indolizidin-9-one N-(Boc)amino acid 3 as a novel constrained Ala-Phe dipeptide surrogate for studying conformation-activity relationships of biologically active peptides.

Simulation of double layers in a model auroral circuit with nonlinear impedance

NASA Technical Reports Server (NTRS)

Smith, R. A.

1986-01-01

A reduced circuit description of the U-shaped potential structure of a discrete auroral arc, consisting of the flank transmission line plus parallel-electric-field region, is used to provide the boundary condition for one-dimensional simulations of the double-layer evolution. The model yields asymptotic scalings of the double-layer potential, as a function of an anomalous transport coefficient alpha and of the perpendicular length scale l(a) of the arc. The arc potential phi(DL) scales approximately linearly with alpha, and for alpha fixed phi (DL) about l(a) to the z power. Using parameters appropriate to the auroral zone acceleration region, potentials of phi (DPL) 10 kV scale to projected ionospheric dimensions of about 1 km, with power flows of the order of magnitude of substorm dissipation rates.

Representation of natural numbers in quantum mechanics

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

Benioff, Paul

2001-03-01

This paper represents one approach to making explicit some of the assumptions and conditions implied in the widespread representation of numbers by composite quantum systems. Any nonempty set and associated operations is a set of natural numbers or a model of arithmetic if the set and operations satisfy the axioms of number theory or arithmetic. This paper is limited to k-ary representations of length L and to the axioms for arithmetic modulo k{sup L}. A model of the axioms is described based on an abstract L-fold tensor product Hilbert space H{sup arith}. Unitary maps of this space onto a physicalmore » parameter based product space H{sup phy} are then described. Each of these maps makes states in H{sup phy}, and the induced operators, a model of the axioms. Consequences of the existence of many of these maps are discussed along with the dependence of Grover's and Shor's algorithms on these maps. The importance of the main physical requirement, that the basic arithmetic operations are efficiently implementable, is discussed. This condition states that there exist physically realizable Hamiltonians that can implement the basic arithmetic operations and that the space-time and thermodynamic resources required are polynomial in L.« less

Transient and stationary spectroscopy of cytochrome c: ultrafast internal conversion controls photoreduction.

PubMed

Löwenich, Dennis; Kleinermanns, Karl; Karunakaran, Venugopal; Kovalenko, Sergey Alexander

2008-01-01

Photoreduction of cytochrome c (Cyt c) has been reinvestigated using femtosecond-to-nanosecond transient absorption and stationary spectroscopy. Femtosecond spectra of oxidized Cyt c, recorded in the probe range 270-1000 nm, demonstrate similar evolution upon 266 or 403 nm excitation: an ultrafast 0.3 ps internal conversion followed by a 4 ps vibrational cooling. Late transient spectra after 20 ps, from the cold ground-state chromophore, reveal a small but measurable signal from reduced Cyt c. The yield phi for Fe3+-->Fe2+ photoreduction is measured to be phi(403) = 0.016 and phi(266) = 0.08 for 403 and 266 nm excitation. These yields lead to a guess of the barrier E(f)(A) = 55 kJ mol(-1) for thermal ground-state electron transfer (ET). Nanosecond spectra initially show the typical absorption from reduced Cyt c and then exhibit temperature-dependent sub-microsecond decays (0.5 micros at 297 K), corresponding to a barrier E(A)(b) = 33 kJ mol(-1) for the back ET reaction and a reaction energy DeltaE = 22 kJ mol(-1). The nanosecond transients do not decay to zero on a second time scale, demonstrating the stability of some of the reduced Cyt c. The yields calculated from this stable reduced form agree with quasistationary reduction yields. Modest heating of Cyt c leads to its efficient thermal reduction as demonstrated by differential stationary absorption spectroscopy. In summary, our results point to ultrafast internal conversion of oxidized Cyt c upon UV or visible excitation, followed by Fe-porphyrin reduction due to thermal ground-state ET as the prevailing mechanism.

Prostate Health Index (PHI) Predicts High-stage Pathology in African American Men.

PubMed

Schwen, Zeyad R; Tosoian, Jeffrey J; Sokoll, Lori J; Mangold, Leslie; Humphreys, Elizabeth; Schaeffer, Edward M; Partin, Alan W; Ross, Ashley E

2016-04-01

To evaluate the association between the Prostate Health Index (PHI) and adverse pathology in a cohort of African American (AA) men undergoing radical prostatectomy. Eighty AA men with prostate-specific antigen (PSA) of 2-10 ng/mL underwent measurement of PSA, free PSA (fPSA), and p2PSA prior to radical prostatectomy. PHI was calculated as [(p2PSA/fPSA) × (PSA)(½)]. Biomarker association with pT3 disease was assessed using logistic regression, and covariates were added to a baseline multivariable model including digital rectal examination. Biomarker ability to predict pT3 disease was measured using the area under the receiver operator characteristic curve. Sixteen men (20%) demonstrated pT3 disease on final pathology. Mean age, PSA, and %fPSA were similar in men with and without pT3 disease (all P  >  .05), whereas PHI was significantly greater in men with pT3 disease (mean 57.2 vs 46.6, P  =  .04). Addition of PHI to the baseline multivariable model improved discriminative ability by 12.9% (P  =. .04) and yielded greater diagnostic accuracy than models, including other individual biomarkers. In AA men with PSA of 2-10 ng/mL, PHI was predictive of pT3 prostate cancer and may help to identify men at increased risk of adverse pathology. Additional studies are needed to substantiate these findings and identify appropriate thresholds for clinical use. Copyright © 2016 Elsevier Inc. All rights reserved.

Responses of Picea mariana to elevated CO2 concentration during growth, cold hardening and dehardening: phenology, cold tolerance, photosynthesis and growth.

PubMed

Bigras, F J; Bertrand, A

2006-07-01

Seedlings from a northern and a southern provenance of black spruce (Picea mariana Mill. BSP) from eastern Canada were exposed to 37 or 71 Pa of carbon dioxide (CO2) during growth, cold hardening and dehardening in a greenhouse. Bud phenology, cold tolerance and photosynthetic efficiency were assessed during the growing and over-wintering periods. Bud set occurred earlier in elevated [CO2] than in ambient [CO2], but it was later in the southern provenance than in the northern provenance. An increase in seedling cold tolerance in early fall was related to early bud set in elevated [CO2]. Maximal photosystem II (PSII) photochemical efficiency (F(v)/F(m)), effective quantum yield (phi(PSII)), photochemical quenching (q(P)), light-saturated photosynthesis (Amax), apparent quantum efficiency (alpha'), light-saturated rate of carboxylation (Vcmax) and electron transport (Jmax) decreased during hardening and recovered during dehardening. Although Amax and alpha' were higher in elevated [CO2] when measured at the growth [CO2], down-regulation of photosynthesis occurred in elevated [CO2] as shown by lower F(v)/F(m), phi(PSII), Vcmax and Jmax. Elevated [CO2] reduced gene expression of the small subunit of Rubisco and also decreased chlorophyll a/chlorophyll b ratio and nitrogen concentration in needles, confirming our observation of down-regulation of photosynthesis. Elevated [CO2] increased the CO2 diffusion gradient and decreased photorespiration, which may have contributed to enhance Amax despite down-regulation of photosynthesis. Total seedling dry mass was higher in elevated [CO2] than in ambient [CO2] at the end of the growing season. However, because of earlier bud formation and cold hardening, and down-regulation of photosynthesis during fall and winter in elevated [CO2], the treatment difference in dry mass increment was less by the end of the winter than during the growing season. Differences in photosynthetic rate observed during fall, winter and spring account for the inter-annual variations in carbon assimilation of black spruce seedlings: our results demonstrate that these variations need to be considered in carbon budget studies.

Preliminary evidence for the influence of physiography and scale upon the autocorrelation function of remotely sensed data

NASA Technical Reports Server (NTRS)

Labovitz, M. L.; Toll, D. L.; Kennard, R. E.

1980-01-01

Previously established results demonstrate that LANDSAT data are autocorrelated and can be described by a univariate linear stochastic process known as auto-regressive-integrated-moving-average model of degree 1, 0, 1 or ARIMA (1, 0, 1). This model has two coefficients of interest for interpretation phi(1) and theta(1). In a comparison of LANDSAT thematic mapper simulator (TMS) data and LANDSAT MSS data several results were established: (1) The form of the relatedness as described by this model is not dependent upon system look angle or pixel size. (2) The phi(1) coefficient increases with decreasing pixel size and increasing topographic complexity. (3) Changes in topography have a greater influence upon phi(1) than changes in land cover class. (4) The theta(1) seems to vary with the amount of atmospheric haze. These patterns of variation in phi(1) and theta(1) are potentially exploitable by the remote sensing community to yield stochastically independent sets of observations, characterize topography, and reduce the number of bytes needed to store remotely sensed data.

What’s Past is Prologue: A Scoping Review of Recent Public Health and Global Health Informatics Literature

PubMed Central

Dixon, Brian E.; Pina, Jamie; Kharrazi, Hadi; Gharghabi, Fardad; Richards, Janise

2015-01-01

Objective: To categorize and describe the public health informatics (PHI) and global health informatics (GHI) literature between 2012 and 2014. Methods: We conducted a semi-systematic review of articles published between January 2012 and September 2014 where information and communications technologies (ICT) was a primary subject of the study or a main component of the study methodology. Additional inclusion and exclusion criteria were used to filter PHI and GHI articles from the larger biomedical informatics domain. Articles were identified using MEDLINE as well as personal bibliographies from members of the American Medical Informatics Association PHI and GHI working groups. Results: A total of 85 PHI articles and 282 GHI articles were identified. While systems in PHI continue to support surveillance activities, we identified a shift towards support for prevention, environmental health, and public health care services. Furthermore, articles from the U.S. reveal a shift towards PHI applications at state and local levels. GHI articles focused on telemedicine, mHealth and eHealth applications. The development of adequate infrastructure to support ICT remains a challenge, although we identified a small but growing set of articles that measure the impact of ICT on clinical outcomes. Discussion: There is evidence of growth with respect to both implementation of information systems within the public health enterprise as well as a widening of scope within each informatics discipline. Yet the articles also illuminate the need for more primary research studies on what works and what does not as both searches yielded small numbers of primary, empirical articles. Conclusion: While the body of knowledge around PHI and GHI continues to mature, additional studies of higher quality are needed to generate the robust evidence base needed to support continued investment in ICT by governmental health agencies. PMID:26392846

Quantal Time Asymmetry: Mathematical Foundation and Physical Interpretation

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

Bohm, A.

2010-07-29

Time in standard quantum mechanics extends from -{infinity}t{sub 0}(Feynman (1948)). In experiments on single Ba{sup +} ions, Dehmelt and others observed this finite preparation timemore » as the ensemble of onset-times t{sub 0}{sup 1}, t{sub 0}{sup 2},...,t{sub 0}{sup n} of dark periods. How the semigroup time evolution, t{sub 0{identical_to}}0

Optical coupling of cold atoms to a levitated nanosphere

NASA Astrophysics Data System (ADS)

Montoya, Cris; Witherspoon, Apryl; Fausett, Jacob; Lim, Jason; Kitching, John; Geraci, Andrew

2017-04-01

Cooling mechanical oscillators to their quantum ground state enables the study of quantum phenomena at macroscopic levels. In many cases, the temperature required to cool a mechanical mode to the ground state is below what current cryogenic systems can achieve. As an alternative to cooling via cryogenic systems, it has been shown theoretically that optically trapped nanospheres could reach the ground state by sympathetically cooling the spheres via cold atoms. Such cooled spheres can be used in quantum limited sensing and matter-wave interferometry, and could also enable new hybrid quantum systems where mechanical oscillators act as transducers. In our setup, optical fields are used to couple a sample of cold Rubidium atoms to a nanosphere. The sphere is optically levitated in a separate vacuum chamber, while the atoms are trapped in a 1-D optical lattice and cooled using optical molasses. This work is partially supported by NSF, Grant No. PHY-1506431.

Phytochrome from Green Plants: Properties and biological Function

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

Quail, Peter H.

2014-07-25

Plants constantly monitor the light environment for informational light signals used to direct adaptational responses to the prevailing conditions. One major such response, the Shade-Avaoidance Response (SAR), triggered when plants sense the presence of competing neighbors, results in enhanced channeling of photosynthetically-fixed carbon into stem elongation at the expense of deposition in reproductive tissues. This response has been selected against in many modern food crops to ensure maximum edible yield (e.g. seeds). Converse enhancement of the SAR, with consequent increased carbon channeling into vegetative cellulose, could contribute to the generation of crops with improved yield of tissues suitable for cellulosicmore » biofuel production. The signal for this response is light enriched in far-red wavelengths. This signal is produced by sunlight filtered through, or reflected from, neighboring vegetation, as a result of preferential depletion of red photons through chlorophyll absorption. The plant phytochrome (phy) photoreceptor system (predominantly phyB) senses this signal through its capacity to switch reversibly, in milliseconds, between two molecular states: the biologically inactive Pr (red-light-absorbing) and biologically active Pfr (far-red-light-absorbing) conformers. The photoequilibrium established between these two conformers in light-grown plants is determined by the ratio of red-to-far-red wavelengths in the incoming signal. The levels of Pfr then dictate the recipient plant’s growth response: high levels suppress elongation growth; low levels promote elongation growth. Studies on seedling deetiolation have advanced our understanding considerably in recent years, of the mechanism by which the photoactivated phy molecule transduces its signal into cellular growth responses. The data show that a subfamily of phy-interacting bHLH transcription factors (PIFs) promote skotomorphogenic seedling development in post-germinative darkness, but that the phy Pfr conformer reverses this activity upon initial light exposure, inducing the switch to photomorphogenic development. This reversal involves light-triggered translocation of the photoactivated phy molecule into the nucleus where it interacts with PIF-family members, inducing rapid phosphorylation and degradation of the PIFs via the ubiquitin-proteasome system. This degradation in turn elicits rapid alterations in gene expression that drive the deetiolation transition. This project has made considerable progress in defining phy-PIF signaling activity in controlling the SAR. The biological functions of the multiple PIF-family members in controlling the SAR, including dissection of the relative contributions of the individual PIFs to this process, as well as to diurnal growth-control oscillations, have been investigated using higher-order pif-mutant combinations. Using microarray analysis of a quadruple pif mutant we have defined the shade-induced, PIF-regulated transcriptional network genome-wide. This has revealed that a dynamic antagonism between the phys and PIFs generates selective reciprocal responses during deetiolation and the SAR in a rapidly light-responsive transcriptional network. Using integrated RNA-seq and ChIP-seq analysis of higher order pif-mutant combinations, we have defined the direct gene-targets of PIF transcriptional regulation, and have obtained evidence that this regulation involves differential direct targeting of rapidly light-responsive genes by the individual PIF-family members. This project has provided significant advances in our understanding of the molecular mechanisms by which the phy-PIF photosensory signaling pathway regulates an important bioenergy-related plant response to the light environment. The identification of molecular targets in the primary transcriptional-regulatory circuitry of this pathway has the potential to enable genetic or reverse-genetic manipulation of the partitioning of carbon between reproductive and vegetative (cellulose-accumulating) tissue, toward enhanced bioenergy yield.« less

Transient and late time attractor tachyon dark energy: Can we distinguish it from quintessence?

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

Ali, Amna; Sami, M.; Sen, A. A.

2009-06-15

The string inspired tachyon field can serve as a candidate of dark energy. Its equation of state parameter w varies from 0 to -1. In the case of tachyon field potential V({phi}){yields}0 slower (faster) than 1/{phi}{sup 2} at infinity, dark energy (dark matter) is a late time attractor. We investigate the tachyon dark energy models under the assumption that w is close to -1. We find that all the models exhibit unique behavior around the present epoch which is exactly the same as that of the thawing quintessence.

Employing OpenCL to Accelerate Ab Initio Calculations on Graphics Processing Units.

PubMed

Kussmann, Jörg; Ochsenfeld, Christian

2017-06-13

We present an extension of our graphics processing units (GPU)-accelerated quantum chemistry package to employ OpenCL compute kernels, which can be executed on a wide range of computing devices like CPUs, Intel Xeon Phi, and AMD GPUs. Here, we focus on the use of AMD GPUs and discuss differences as compared to CUDA-based calculations on NVIDIA GPUs. First illustrative timings are presented for hybrid density functional theory calculations using serial as well as parallel compute environments. The results show that AMD GPUs are as fast or faster than comparable NVIDIA GPUs and provide a viable alternative for quantum chemical applications.

Studies with infections fragments of phage DNA. Final report, January 1, 1970--June 30, 1976

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

Schachtele, C. F.

The minute, virulent and structurally intricate Bacillus subtilis bacteriophage phi 29 was utilized to study in vivo viral development. Purified strands of phi 29 DNA were used to analyze transcription of the viral genome. Early mRNA hybridizes to the light DNA strand which controls DNA replication and other early functions. Late mRNA hybridizes to the heavy DNA strand which codes for phage structural proteins. The temporal sequence of specific viral protein synthesis was analyzed by gel electrophoresis and was shown to directly correlate with the RNA transcription pattern. The genes carried by phi 29 have been marked with ts andmore » sus mutations and mapped by appropriate crosses yielding a linear map of 17 cistrons. Fragments of the phi 29 DNA were shown to retain their biological activity and marker rescue studies indicated that gene transfer could be performed with pieces having a molecular weight of less than 1 million daltons. Mutant infection under nonpermissive conditions and the analysis of precursor structures has allowed the formation of a tentative morphogenetic pathway leading to the formation of infectious particles. Work with phi 29 has established this virus as an advantageous model system for studying a variety of problems in molecular biology and approximately a dozen laboratories in the country and abroad are working with this phage.« less

Phytase from Citrobacter koseri PM-7: Enhanced production using statistical method and application in ameliorating mineral bioaccessibility and protein digestibility of high-phytate food.

PubMed

Tripathi, Preeti; A, Jyothi Lakshmi; Kapoor, Mukesh

2018-01-02

The present study was aimed at enhancing phytase (Phy-Ck) production from Citrobacter koseri PM-7 using response surface methodology (RSM) and improving the bioaccessibility of minerals (Fe and Zn) and protein digestibility in high-phytate food using Phy-Ck. A five-variable and three-level central composite design of RSM using wheat bran (6.681%, w/v), inoculum level (2.5%, v/v), and triton X-100 (0.2%, v/v) resulted in up to 5.57-fold (1.047 U/ml) improvement in Phy-Ck yield from C. koseri PM-7 when compared with fermentation media I and II. The model was successfully validated in the design space by taking a random set of variable combinations. Treatment of high-phytate food with partially purified Phy-Ck showed improvement in mineral bioaccessibility maximally for defatted sesame flour (DSF) (Fe 45.5%; Zn 50.7%) followed by wheat flour (WF) (Fe 13.5%; Zn 14.4%), green gram flour (GGF) (Fe 0.7%; Zn 3.8%) and defatted groundnut flour (DGF) (Zn 5.6%). The in vitro protein digestibility (IVPD) of WF increased from 48.83 to 65.04%, GGF from 45.04 to 57.12%, and DSF from 47.34 to 55.7% after Phy-Ck treatment.

Effects of Boron foliar-fertilization on irrigated soybean (Glycine max L. Merr.) in the Mississippi River Valley Delta of the midsouth, USA

USDA-ARS?s Scientific Manuscript database

Irrigated soybeans in the Mississippi Delta have been reported to with increased seed yields when fertilized with a boron (B). Furrow irrigated soybean cultivars were foliar fertilized with a B solution at growth stages R3 and/or R5. No consistent trends in yield or seed weight were noted. No phy...

Commensurability effects in one-dimensional Anderson localization: Anomalies in eigenfunction statistics

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

Kravtsov, V.E., E-mail: kravtsov@ictp.it; Landau Institute for Theoretical Physics, 2 Kosygina st., 117940 Moscow; Yudson, V.I., E-mail: yudson@isan.troitsk.ru

Highlights: > Statistics of normalized eigenfunctions in one-dimensional Anderson localization at E = 0 is studied. > Moments of inverse participation ratio are calculated. > Equation for generating function is derived at E = 0. > An exact solution for generating function at E = 0 is obtained. > Relation of the generating function to the phase distribution function is established. - Abstract: The one-dimensional (1d) Anderson model (AM), i.e. a tight-binding chain with random uncorrelated on-site energies, has statistical anomalies at any rational point f=(2a)/({lambda}{sub E}) , where a is the lattice constant and {lambda}{sub E} is the demore » Broglie wavelength. We develop a regular approach to anomalous statistics of normalized eigenfunctions {psi}(r) at such commensurability points. The approach is based on an exact integral transfer-matrix equation for a generating function {Phi}{sub r}(u, {phi}) (u and {phi} have a meaning of the squared amplitude and phase of eigenfunctions, r is the position of the observation point). This generating function can be used to compute local statistics of eigenfunctions of 1d AM at any disorder and to address the problem of higher-order anomalies at f=p/q with q > 2. The descender of the generating function P{sub r}({phi}){identical_to}{Phi}{sub r}(u=0,{phi}) is shown to be the distribution function of phase which determines the Lyapunov exponent and the local density of states. In the leading order in the small disorder we derived a second-order partial differential equation for the r-independent ('zero-mode') component {Phi}(u, {phi}) at the E = 0 (f=1/2 ) anomaly. This equation is nonseparable in variables u and {phi}. Yet, we show that due to a hidden symmetry, it is integrable and we construct an exact solution for {Phi}(u, {phi}) explicitly in quadratures. Using this solution we computed moments I{sub m} = N< vertical bar {psi} vertical bar {sup 2m}> (m {>=} 1) for a chain of the length N {yields} {infinity} and found an essential difference between their m-behavior in the center-of-band anomaly and for energies outside this anomaly. Outside the anomaly the 'extrinsic' localization length defined from the Lyapunov exponent coincides with that defined from the inverse participation ratio ('intrinsic' localization length). This is not the case at the E = 0 anomaly where the extrinsic localization length is smaller than the intrinsic one. At E = 0 one also observes an anomalous enhancement of large moments compatible with existence of yet another, much smaller characteristic length scale.« less

Vacuum stress energy density and its gravitational implications

NASA Astrophysics Data System (ADS)

Estrada, Ricardo; Fulling, Stephen A.; Kaplan, Lev; Kirsten, Klaus; Liu, Zhonghai; Milton, Kimball A.

2008-04-01

In nongravitational physics the local density of energy is often regarded as merely a bookkeeping device; only total energy has an experimental meaning—and it is only modulo a constant term. But in general relativity the local stress-energy tensor is the source term in Einstein's equation. In closed universes, and those with Kaluza-Klein dimensions, theoretical consistency demands that quantum vacuum energy should exist and have gravitational effects, although there are no boundary materials giving rise to that energy by van der Waals interactions. In the lab there are boundaries, and in general the energy density has a nonintegrable singularity as a boundary is approached (for idealized boundary conditions). As pointed out long ago by Candelas and Deutsch, in this situation there is doubt about the viability of the semiclassical Einstein equation. Our goal is to show that the divergences in the linearized Einstein equation can be renormalized to yield a plausible approximation to the finite theory that presumably exists for realistic boundary conditions. For a scalar field with Dirichlet or Neumann boundary conditions inside a rectangular parallelepiped, we have calculated by the method of images all components of the stress tensor, for all values of the conformal coupling parameter and an exponential ultraviolet cutoff parameter. The qualitative features of contributions from various classes of closed classical paths are noted. Then the Estrada-Kanwal distributional theory of asymptotics, particularly the moment expansion, is used to show that the linearized Einstein equation with the stress-energy near a plane boundary as source converges to a consistent theory when the cutoff is removed. This paper reports work in progress on a project combining researchers in Texas, Louisiana and Oklahoma. It is supported by NSF Grants PHY-0554849 and PHY-0554926.

[Response processes of Aralia elata photosynthesis and transpiration to light and soil moisture].

PubMed

Chen, Jian; Zhang, Guang-Can; Zhang, Shu-Yong; Wang, Meng-Jun

2008-06-01

By using CIRAS-2 portable photosynthesis system, the light response processes of Aralia elata photosynthesis and transpiration under different soil moisture conditions were studied, aimed to understand the adaptability of A. elata to different light and soil moisture conditions. The results showed that the response processes of A. elata net photosynthetic rate (Pn), transpiration rate (Tr), and water use efficiency (WUE) to photon flux density (PFD) were different. With the increasing PFD in the range of 800-1800 micromol x m2(-2) x s(-1), Pn changed less, Tr decreased gradually, while WUE increased obviously. The light saturation point (LSP) and light compensation point (LCP) were about 800 and 30 micromol m(-2) x s(-1), respectively, and less affected by soil water content; while the apparent photosynthetic quantum yield (Phi) and dark respiratory rate (Rd) were more affected by the moisture content. The Pn and WUE had evident threshold responses to the variations of soil water content. When the soil relative water content (RWC) was in the range of 44%-79%, A. elata could have higher levels of Pn and WUE.

Full-dimensional Quantum Calculations of Rovibrational Transitions in CS induced by H2

NASA Astrophysics Data System (ADS)

Yang, Benhui; Zhang, Peng; Stancil, Phillip; Bowman, J.; Balakrishnan, N.; Forrey, R.

2017-04-01

Carbon monosulfide (CS), the sulfur analogue of carbon monoxide, has been widely observed in a variety interstellar regions. An accurate prediction of its abundance requires collisional rate coefficients with ambient gases. However, the collisional rate coefficients are largely unknown and primarily rely on theoretical scattering calculations. In interstellar clouds, the dominant collision partner is H2. Rate coefficient data on CS-H2 collisions are limited to pure rotational transitions and no data exist for rovibrational transitions. In this work we evaluate the first full-dimensional potential energy surface for the CS-H2 system using high-level electronic structure theory and perform explicit quantum close-coupling calculations of rovibrational transitions in CS induced by H2 collisions. Cross sections and rate coefficients for rotational transitions are compared with previous theoretical results obtained within a rigid-rotor model. For rovibrational transitions, state-to-state rate coefficients are evaluated for several low-lying rotational levels in the first excited vibrational level of CS. Results are presented for both para-H2 and ortho-H2 collision partners. Work at UGA and Emory are supported by NASA Grant No. NNX16AF09G, at UNLV by NSF Grant No. PHY-1505557, and at Penn State by NSF Grant No. PHY-1503615.

Non-traditional Aharonov-Bohm effects in condensed matter

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

Krive, I.V.; Rozhavsky, A.S.

1992-05-10

In 1959, Aharonov and Bohm proposed an elegant experiment demonstrating observability of electromagnetic potentials (or, which is the same, the non-locality of the wave function of charged particles) in quantum mechanics. This paper discusses the Aharonov-Bohm effect, based on the fundamental principles of quantum theory, as the superposition principles, the quantum character of motion of particles and locality of the interaction of a charge with an electromagnetic potential L{sub int} = j{sub {mu}}A{sup {mu}}. It is thus no wonder that the Aharonov-Bohm's paper aroused much dispute which is still ongoing. Originally, the Aharonov-Bohm effect (ABE) means the dependence of themore » interference pattern on the magnetic fluid flux {phi} in a Gendaken experiment on a coherent electron beam in the field of an infinitely thin solenoid. Later, however, it became common to refer to the Aharonov-Bohm phenomenon wherever the characteristics of systems under study appear to depend on the flux {phi} in the absence of electric and magnetic fields. In this sense, it was highly interesting to analyze the ABE in condensed media (the many-particle Aharonov-Bohm effect), in particular to study the dependence of the thermodynamic and kinetic characteristics, e.g., of metal on the flux. Such a problem was first discussed by Byers and Yang who formulated the general theorems related to the ABE in conducting condensed media. The next important step was the work of Kulik who formulated a concrete model and calculated the flux-dependent contribution to the metal free energy and provided a first clear formulation of the requirements to reveal.« less

Molecular structure and conformations of para-methylbenzene sulfonamide and ortho-methylbenzene sulfonamide: gas electron diffraction and quantum chemical calculations study.

PubMed

Petrov, Vjacheslav M; Girichev, Georgiy V; Oberhammer, Heinz; Petrova, Valentina N; Giricheva, Nina I; Bardina, Anna V; Ivanov, Sergey N

2008-04-03

The molecular structure and conformational properties of para-methylbenzene sulfonamide (4-MBSA) and ortho-methylbenzene sulfonamide (2-MBSA) have been studied by gas electron diffraction (GED) and quantum chemical methods (B3LYP/6-311+G** and MP2/6-31G**). Quantum chemical calculations predict the existence of two conformers for 4-MBSA with the S-N bond perpendicular to the benzene plane and the NH2 group either eclipsing or staggering the S-O bonds of the SO2 group. Both conformers possess CS symmetry. The eclipsed form is predicted to be favored by DeltaE = 0.63 kcal/mol (B3LYP) or 1.00 kcal/mol (MP2). According to the calculations, the S-N bond in 2-MBSA can possess planar direction opposite the methyl group (phi(C2C1SN) = 180 degrees ) or nonplanar direction (phi(C2C1SN) approximately 60 degrees ). In both cases, the NH2 group can adopt eclipsed or staggered orientation, resulting in a total of four stable conformers. The nonplanar eclipsed conformer (C1 symmetry) and the planar eclipsed form (CS symmetry) are predicted to be favored. According to the GED analysis, the saturated vapor over solid 4-MBSA at T = 151(3) degrees C consists as mixture of the eclipsed (78(19) %) and staggered (22(19) %) forms. The saturated vapor over solid 2-MBSA at T = 157(3) degrees C consists as a mixture of the nonplanar eclipsed (69(11) %) and planar eclipsed (31(11) %) forms.

The dissociative recombination of O2(+) - The quantum yield of O(1S) and O(1D)

NASA Technical Reports Server (NTRS)

Abreu, V. J.; Solomon, S. C.; Sharp, W. E.; Hays, P. B.

1983-01-01

Data from the visible airglow experiment on the Atmosphere Explorer-E satellite have been used to determine the quantum yield of O(1S) and O(1D) from the dissociative recombination of O2(+). A range of values between 0.09 and 0.23 has been obtained for the quantum yield of O(1S). It is shown that the quantum yield of O(1S) depends on the ratio of electron density to atomic oxygen density. This suggests that the quantum yield of O(1S) may depend on the degree of vibrational excitation of the recombining O2(+). The quantum yield of O(1D) has been measured to be 1.23 + or - 0.42, with no dependence on the electron-oxygen ratio.

One step Pd(0)-catalyzed synthesis, X-ray analysis, and photophysical properties of cyclopent[hi]aceanthrylene: fullerene-like properties in a nonalternant cyclopentafused aromatic hydrocarbon.

PubMed

Dang, Hung; Levitus, Marcia; Garcia-Garibay, Miguel A

2002-01-09

A simple procedure for the synthesis of cyclopentafused polycyclic aromatic hydrocarbons (CP-PAH) with Pd(PPh(3))(2)Cl(2) catalyst has been applied to the one-pot palladium(0)-catalyzed coupling of 9,10-dibromoanthracene (1) with 2-methyl-3-butyn-2-ol. Reactions carried out in refluxing benzene in the presence of CuSO(4)/Al(2)O(3) yielded 9,10-dialkynylanthracene 2a, alkynyl aceanthrylene 2b, and 2,7-disubstituted cyclopent[hi]aceanthrylene 2c in 13%, 23%, and 19% purified yields, respectively, with total conversions of 80-90%. Sealed tube reactions without copper at 110 degrees C improved the yield of 2c up to >75%. Single-crystal X-ray analyses of 2a and 2c reveal a three-dimensional hydrogen bonding network, producing a unique crystal packing. The packing structure of 2b is dominated by pi-pi stacking interactions between two aceanthrylene molecules. CP-PAHs 2b and 2c have potentially interesting fullerene-like photophysics. While the UV-vis and fluorescence spectra of 2a (Phi(F) = 0.87) show the characteristic vibronic structure of anthracene, the UV-vis spectra of ruby-red aceanthrylene 2b and greenish-black cyclopent[hi]aceanthrylene 2c extend well into the visible range. Isomers 2b and 2c showed no detectable fluorescence emission. Unlike fullerenes, compounds 2b and 2c are poor singlet oxygen sensitizers with measured (1)O(2) quantum yields of 0.02 and 0.06, respectively. As expected from a simple Hückel analysis, 2c has relatively low two-electron reduction potentials as determined by cyclic voltammetry.

Clash of symmetries in a Randall-Sundrum-like spacetime

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

Dando, Gareth; George, Damien P.; Volkas, Raymond R.

2005-08-15

We present a toy model that exhibits clash-of-symmetries style Higgs field kink configurations in a Randall-Sundrum-like spacetime. The model has two complex scalar fields {phi}{sub 1,2}, with a sextic potential obeying global U(1)xU(1) and discrete {phi}{sub 1}{r_reversible}{phi}{sub 2} interchange symmetries. The scalar fields are coupled to 4+1 dimensional gravity endowed with a bulk cosmological constant. We show that the coupled Einstein-Higgs field equations have an interesting analytic solution provided the sextic potential adopts a particular form. The 4+1 metric is shown to be that of a smoothed-out Randall-Sundrum type of spacetime. The thin-brane Randall-Sundrum limit, whereby the Higgs field kinksmore » become step functions, is carefully defined in terms of the fundamental parameters in the action. The 'clash-of-symmetries' feature, defined in previous papers, is manifested here through the fact that both of the U(1) symmetries are spontaneously broken at all nonasymptotic points in the extra dimension w. One of the U(1)'s is asymptotically restored as w{yields}-{infinity}, with the other U(1) restored as w{yields}+{infinity}. The spontaneously broken discrete symmetry ensures topological stability. In the gauged version of this model we find new flat-space solutions, but in the warped metric case we have been unable to find any solutions with nonzero gauge fields.« less

Interlayer tunneling in double-layer quantum hall pseudoferromagnets.

PubMed

Balents, L; Radzihovsky, L

2001-02-26

We show that the interlayer tunneling I-V in double-layer quantum Hall states displays a rich behavior which depends on the relative magnitude of sample size, voltage length scale, current screening, disorder, and thermal lengths. For weak tunneling, we predict a negative differential conductance of a power-law shape crossing over to a sharp zero-bias peak. An in-plane magnetic field splits this zero-bias peak, leading instead to a "derivative" feature at V(B)(B(parallel)) = 2 pi Planck's over 2 pi upsilon B(parallel)d/e phi(0), which gives a direct measurement of the dispersion of the Goldstone mode corresponding to the spontaneous symmetry breaking of the double-layer Hall state.

Simplified model to describe the dissociative recombination of linear polyatomic ions of astrophysical interest

NASA Astrophysics Data System (ADS)

Fonseca Dos Santos, Samantha; Douguet, Nicolas; Kokoouline, Viatcheslav; Orel, Ann

2013-05-01

We will present theoretical results on the dissociative recombination (DR) of the linear polyatomic ions HCNH+, HCO+ and N2H+. Besides their astrophysical importance, they also share the characteristic that at low electronic impact energies their DR process happens via the indirect DR mechanism. We apply a general simplified model successfully implemented to treat the DR process of the highly symmetric non-linear molecules H3+, CH3+, H3O+ and NH4+ to calculated cross sections and DR rates for these ions. The model is based on multichannel quantum defect theory and accounts for all the main ingredients of indirect DR. New perspectives on dissociative recombination of HCO+ will also be discussed, including the possible role of HOC+ in storage ring experimental results. This work is supported by the DOE Office of Basic Energy Science and the National Science Foundation, Grant No's PHY-11-60611 and PHY-10-68785.

Fermionic dark matter and neutrino masses in a B - L model

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

Sánchez-Vega, B. L.; Schmitz, E. R.

2015-09-01

In this work we present a common framework for neutrino masses and dark matter. Specifically, we work with a local B - L extension of the standard model which has three right-handed neutrinos, n(Ri), and some extra scalars, Phi, phi(i), besides the standard model fields. The n(Ri)'s have nonstandard B - L quantum numbers and thus these couple to different scalars. This model has the attractive property that an almost automatic Z(2) symmetry acting only on a fermionic field, n(R3), is present. Taking advantage of this Z(2) symmetry, we study both the neutrino mass generation via a natural seesaw mechanismmore » at low energy and the possibility of n(R3) being a dark matter candidate. For this last purpose, we study its relic abundance and its compatibility with the current direct detection experiments.« less

Manipulating the Energetics and Rates of Electron Transfer in Rhodobacter capsulatus Reaction Centers with Asymmetric Pigment Content

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

Faries, Kaitlyn M.; Dylla, Nicholas P.; Hanson, Deborah K.

2017-07-17

Seemingly redundant parallel pathways for electron transfer (ET), composed of identical sets of cofactors, are a cornerstone feature of photosynthetic reaction centers (RCs) involved in light-energy conversion. In native bacterial RCs, both A and B branches house one bacteriochlorophyll (BChl) and one bacteriopheophytin (BPh), but the A branch is used exclusively. Described herein are the results-obtained for two Rhodobacter capsulatus RCs with an unnaturally high degree of cofactor asymmetry, two BPh on the RC's B side and two BChl on the A side. These pigment changes derive, respectively, from the His(M180)Leu mutation [a BPh ((Phi(B)) replaces the B-side BChl (BB)],more » and the Leu(M212)His mutation [a BChl (beta(A))) replaces the A-side BPh (H-A)]. Additionally, Tyr(M208)Phe was employed to disfavor ET to the A branch; in one mutant, Val(M131)Glu creates a hydrogen bond to H-B to enhance ET to H-B. In both Phi(B) mutants, the decay kinetics of the excited primary ET donor (P*) resolve three populations with lifetimes of similar to 9 ps (50-60%), similar to 40 ps (10-20%), and similar to 200 ps (20-30%), with P+Phi(-)(B) formed predominantly from the 9 ps fraction. The 50-60% yield of P+Phi(B)- is the highest yet observed for a Phi(B)-containing RC. The results provide insight into factors needed for efficient multistep ET.« less

Data for polarization in charmless B{yields}{phi}K*: A signal for new physics?

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

Das, Prasanta Kumar; Yang, K.-C.

2005-05-01

The recent observations of sizable transverse fractions of B{yields}{phi}K* may hint for the existence of new physics. We analyze all possible new-physics four-quark operators and find that two classes of new-physics operators could offer resolutions to the B{yields}{phi}K* polarization anomaly. The operators in the first class have structures (1-{gamma}{sub 5})x(1-{gamma}{sub 5}), {sigma}(1-{gamma}{sub 5})x{sigma}(1-{gamma}{sub 5}), and in the second class (1+{gamma}{sub 5})x(1+{gamma}{sub 5}), {sigma}(1+{gamma}{sub 5})x{sigma}(1+{gamma}{sub 5}). For each class, the new-physics effects can be lumped into a single parameter. Two possible experimental results of polarization phases, arg(A{sub perpendicular})-arg(A{sub parallel}){approx_equal}{pi} or 0, originating from the phase ambiguity in data, could be separatelymore » accounted for by our two new-physics scenarios: the first (second) scenario with the first (second) class new-physics operators. The consistency between the data and our new-physics analysis suggests a small new-physics weak phase, together with a large(r) strong phase. We obtain sizable transverse fractions {lambda}{sub parallel{sub parallel}}+{lambda}{sub perpendicular{sub perpendicular}}{approx_equal}{lambda}{sub 00}, in accordance with the observations. We find {lambda}{sub parallel{sub parallel}}{approx_equal}0.8{lambda}{sub perpendicular{sub perpendicular}} in the first scenario but {lambda}{sub parallel{sub parallel}} > or approx. {lambda}{sub perpendicular{sub perpendicular}} in the second scenario. We discuss the impact of the new-physics weak phase on observations.« less

Electron spin control and torsional optomechanics of an optically levitated nanodiamond in vacuum

NASA Astrophysics Data System (ADS)

Li, Tongcang; Hoang, Thai; Ahn, Jonghoon; Bang, Jaehoon

Electron spins of diamond nitrogen-vacancy (NV) centers are important quantum resources for nanoscale sensing and quantum information. Combining such NV spin systems with levitated optomechanical resonators will provide a hybrid quantum system for many novel applications. Here we optically levitate a nanodiamond and demonstrate electron spin control of its built-in NV centers in vacuum. We observe that the strength of electron spin resonance (ESR) is enhanced when the air pressure is reduced. We also observe that oxygen and helium gases have different effects on both the photoluminescence and the ESR contrast of nanodiamond NV centers, indicating potential applications of NV centers in oxygen gas sensing. For spin-optomechanics, it is important to control the orientation of the nanodiamond and NV centers in a magnetic field. Recently, we have observed the angular trapping and torsional vibration of a levitated nanodiamond, which paves the way towards levitated torsional optomechanics in the quantum regime. NSF 1555035-PHY.

Quantum Yield of Single Surface Plasmons Generated by a Quantum Dot Coupled with a Silver Nanowire.

PubMed

Li, Qiang; Wei, Hong; Xu, Hongxing

2015-12-09

The interactions between surface plasmons (SPs) in metal nanostructures and excitons in quantum emitters (QEs) lead to many interesting phenomena and potential applications that are strongly dependent on the quantum yield of SPs. The difficulty in distinguishing all the possible exciton recombination channels hinders the experimental determination of SP quantum yield. Here, we experimentally measured for the first time the quantum yield of single SPs generated by the exciton-plasmon coupling in a system composed of a single quantum dot and a silver nanowire (NW). By utilizing the SP guiding property of the NW, the decay rates of all the exciton recombination channels, i.e., direct free space radiation channel, SP generation channel, and nonradiative damping channel, are quantitatively obtained. It is determined that the optimum emitter-NW coupling distance for the largest SP quantum yield is about 10 nm, resulting from the different distance-dependent decay rates of the three channels. These results are important for manipulating the coupling between plasmonic nanostructures and QEs and developing on-chip quantum plasmonic devices for potential nanophotonic and quantum information applications.

Absolute quantum yield measurement of powder samples.

PubMed

Moreno, Luis A

2012-05-12

Measurement of fluorescence quantum yield has become an important tool in the search for new solutions in the development, evaluation, quality control and research of illumination, AV equipment, organic EL material, films, filters and fluorescent probes for bio-industry. Quantum yield is calculated as the ratio of the number of photons absorbed, to the number of photons emitted by a material. The higher the quantum yield, the better the efficiency of the fluorescent material. For the measurements featured in this video, we will use the Hitachi F-7000 fluorescence spectrophotometer equipped with the Quantum Yield measuring accessory and Report Generator program. All the information provided applies to this system. Measurement of quantum yield in powder samples is performed following these steps: 1. Generation of instrument correction factors for the excitation and emission monochromators. This is an important requirement for the correct measurement of quantum yield. It has been performed in advance for the full measurement range of the instrument and will not be shown in this video due to time limitations. 2. Measurement of integrating sphere correction factors. The purpose of this step is to take into consideration reflectivity characteristics of the integrating sphere used for the measurements. 3. Reference and Sample measurement using direct excitation and indirect excitation. 4. Quantum Yield calculation using Direct and Indirect excitation. Direct excitation is when the sample is facing directly the excitation beam, which would be the normal measurement setup. However, because we use an integrating sphere, a portion of the emitted photons resulting from the sample fluorescence are reflected by the integrating sphere and will re-excite the sample, so we need to take into consideration indirect excitation. This is accomplished by measuring the sample placed in the port facing the emission monochromator, calculating indirect quantum yield and correcting the direct quantum yield calculation. 5. Corrected quantum yield calculation. 6. Chromaticity coordinates calculation using Report Generator program. The Hitachi F-7000 Quantum Yield Measurement System offer advantages for this application, as follows: High sensitivity (S/N ratio 800 or better RMS). Signal is the Raman band of water measured under the following conditions: Ex wavelength 350 nm, band pass Ex and Em 5 nm, response 2 sec), noise is measured at the maximum of the Raman peak. High sensitivity allows measurement of samples even with low quantum yield. Using this system we have measured quantum yields as low as 0.1 for a sample of salicylic acid and as high as 0.8 for a sample of magnesium tungstate. Highly accurate measurement with a dynamic range of 6 orders of magnitude allows for measurements of both sharp scattering peaks with high intensity, as well as broad fluorescence peaks of low intensity under the same conditions. High measuring throughput and reduced light exposure to the sample, due to a high scanning speed of up to 60,000 nm/minute and automatic shutter function. Measurement of quantum yield over a wide wavelength range from 240 to 800 nm. Accurate quantum yield measurements are the result of collecting instrument spectral response and integrating sphere correction factors before measuring the sample. Large selection of calculated parameters provided by dedicated and easy to use software. During this video we will measure sodium salicylate in powder form which is known to have a quantum yield value of 0.4 to 0.5.

Limited Irrigation Water Management Research in Colorado, USA

USDA-ARS?s Scientific Manuscript database

The Limited Irrigation Research Farm (LIRF) is located in north-central Colorado (USA) near the city of Greeley. The research focus is to explore management objectives focused on maintaining high crop yields with limited water supplies. Researchers, which include agricultural engineers and plant phy...

Robust distant-entanglement generation using coherent multiphoton scattering

NASA Astrophysics Data System (ADS)

Chan, Ching-Kit; Sham, L. J.

2013-03-01

The generation and controllability of entanglement between distant quantum states have been the heart of quantum computation and quantum information processing. Existing schemes for solid state qubit entanglement are based on the single-photon spectroscopy that has the merit of a high fidelity entanglement creation, but with a very limited efficiency. This severely restricts the scalability for a qubit network system. Here, we describe a new distant entanglement protocol using coherent multiphoton scattering. The scheme makes use of the postselection of large and distinguishable photon signals, and has both a high success probability and a high entanglement fidelity. Our result shows that the entanglement generation is robust against photon fluctuations, and has an average entanglement duration within the decoherence time in various qubit systems, based on existing experimental parameters. This research was supported by the U.S. Army Research Office MURI award W911NF0910406 and by NSF grant PHY-1104446.

Topologically non-trivial electronic and magnetic states in doped copper Kagome lattices

NASA Astrophysics Data System (ADS)

Guterding, Daniel; Jeschke, Harald O.; Valenti, Roser

We present a theoretical investigation of doped copper kagome materials based on natural minerals Herbertsmithite [ZnCu3(OH)6Cl2] and Barlowite[Cu4(OH)6FBr]. Using ab-initio density functional theory calculations we estimate the stability of the hypothetical compounds against structural distortions and analyze their electronic and magnetic properties. We find that materials based on Herbertsmithite present an ideal playground for investigating the interplay of non-trivial band-topology and strong electronic correlation effects. In particular, we propose candidates for the Quantum Spin Hall effect at filling 4/3 and the Quantum Anomalous Hall effect at filling 2/3. For the Barlowite system we point out a route to realize a Quantum Spin Liquid. This work was supported by Deutsche Forschungsgemeinschaft under Grant No. SFB/TR 49 and the National Science Foundation under Grant No. PHY11-25915.

Towards measuring quantum electrodynamic torque with a levitated nanorod

NASA Astrophysics Data System (ADS)

Xu, Zhujing; Bang, Jaehoon; Ahn, Jonghoon; Hoang, Thai M.; Li, Tongcang

2017-04-01

According to quantum electrodynamics, quantum fluctuations of electromagnetic fields give rise to a zero-point energy that never vanishes, even in the absence of electromagnetic sources. The interaction energy will not only lead to the well-known Casimir force but will also contribute to the Casimir torque for anisotropic materials. We propose to use an optically levitated nanorod in vacuum and a birefringent substrate to experimentally investigate the QED torque. We have previously observed the libration of an optically levitated non-spherical nanoparticle in vacuum and found it to be an ultrasensitive torque sensor. A nanorod with a long axis of 300nm and a diameter of 60nm levitated in vacuum at 10 (- 8) torr will have a remarkable torque detection sensitivity on the order of 10 (- 28) Nm/ √Hz, which will be sufficient to detect the Casimir torque. This work is partially supported by the National Science Foundation under Grant No.1555035-PHY.

Size-Dependent Biexciton Quantum Yields and Carrier Dynamics of Quasi-Two-Dimensional Core/Shell Nanoplatelets

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

Ma, Xuedan; Diroll, Benjamin T.; Cho, Wooje

Quasi-two-dimensional nanoplatelets (NPLs) possess fundamentally different excitonic properties from zero-dimensional quantum dots. We study lateral size-dependent photon emission statistics and carrier dynamics of individual NPLs using second-order photon correlation (g( 2)(τ)) spectroscopy and photoluminescence (PL) intensity-dependent lifetime analysis. Room-temperature radiative lifetimes of NPLs can be derived from maximum PL intensity periods in PL time traces. It first decreases with NPL lateral size and then stays constant, deviating from the electric dipole approximation. Analysis of the PL time traces further reveals that the single exciton quantum yield in NPLs decreases with NPL lateral size and increases with protecting shell thickness, indicatingmore » the importance of surface passivation on NPL emission quality. Second-order photon correlation (g( 2)(τ)) studies of single NPLs show that the biexciton quantum yield is strongly dependent on the lateral size and single exciton quantum yield of the NPLs. In large NPLs with unity single exciton quantum yield, the corresponding biexciton quantum yield can reach unity. In conclusion, these findings reveal that by careful growth control and core–shell material engineering, NPLs can be of great potential for light amplification and integrated quantum photonic applications.« less

Size-Dependent Biexciton Quantum Yields and Carrier Dynamics of Quasi-Two-Dimensional Core/Shell Nanoplatelets

DOE PAGES

Ma, Xuedan; Diroll, Benjamin T.; Cho, Wooje; ...

2017-08-08

Quasi-two-dimensional nanoplatelets (NPLs) possess fundamentally different excitonic properties from zero-dimensional quantum dots. We study lateral size-dependent photon emission statistics and carrier dynamics of individual NPLs using second-order photon correlation (g( 2)(τ)) spectroscopy and photoluminescence (PL) intensity-dependent lifetime analysis. Room-temperature radiative lifetimes of NPLs can be derived from maximum PL intensity periods in PL time traces. It first decreases with NPL lateral size and then stays constant, deviating from the electric dipole approximation. Analysis of the PL time traces further reveals that the single exciton quantum yield in NPLs decreases with NPL lateral size and increases with protecting shell thickness, indicatingmore » the importance of surface passivation on NPL emission quality. Second-order photon correlation (g( 2)(τ)) studies of single NPLs show that the biexciton quantum yield is strongly dependent on the lateral size and single exciton quantum yield of the NPLs. In large NPLs with unity single exciton quantum yield, the corresponding biexciton quantum yield can reach unity. In conclusion, these findings reveal that by careful growth control and core–shell material engineering, NPLs can be of great potential for light amplification and integrated quantum photonic applications.« less

Field-acclimated Gossypium hirsutum cultivars exhibit genotypic and seasonal differences in photosystem II thermostability.

PubMed

Snider, John L; Oosterhuis, Derrick M; Collins, Guy D; Pilon, Cristiane; Fitzsimons, Toby R

2013-03-15

Previous investigations have demonstrated that photosystem II (PSII) thermostability acclimates to prior exposure to heat and drought, but contrasting results have been reported for cotton (Gossypium hirsutum). We hypothesized that PSII thermotolerance in G. hirsutum would acclimate to environmental conditions during the growing season and that there would be differences in PSII thermotolerance between commercially-available U.S. cultivars. To this end, three cotton cultivars were grown under dryland conditions in Tifton Georgia, and two under irrigated conditions in Marianna Arkansas. At Tifton, measurements included PSII thermotolerance (T15, the temperature causing a 15% decline in maximum quantum yield), leaf temperatures, air temperatures, midday (1200 to 1400h) leaf water potentials (ΨMD), leaf-air vapor pressure deficit (VPD), actual quantum yield (ΦPSII) and electron transport rate through PSII (ETR) on three sample dates. At Marianna, T15 was measured on two sample dates. Optimal air and leaf temperatures were observed on all sample dates in Tifton, but PSII thermotolerance increased with water deficit conditions (ΨMD=-3.1MPa), and ETR was either unaffected or increased under water-stress. Additionally, T15 for PHY 499 was ∼5°C higher than for the other cultivars examined (DP 0912 and DP 1050). The Marianna site experienced more extreme high temperature conditions (20-30 days Tmax≥35°C), and showed an increase in T15 with higher average Tmax. When average T15 values for each location and sample date were plotted versus average daily Tmax, strong, positive relationships (r(2) from .954 to .714) were observed between Tmax and T15. For all locations T15 was substantially higher than actual field temperature conditions. We conclude that PSII thermostability in G. hirsutum acclimates to pre-existing environmental conditions; PSII is extremely tolerant to high temperature and water-deficit stress; and differences in PSII thermotolerance exist between commercially-available cultivars. Copyright © 2012 Elsevier GmbH. All rights reserved.

Micro-optomechanical trampoline resonators

NASA Astrophysics Data System (ADS)

Pepper, Brian; Kleckner, Dustin; Sonin, Petro; Jeffrey, Evan; Bouwmeester, Dirk

2011-03-01

Recently, micro-optomechanical devices have been proposed for implementation of experiments ranging from non-demolition measurements of phonon number to creation of macroscopic quantum superpositions. All have strenuous requirements on optical finesse, mechanical quality factor, and temperature. We present a set of devices composed of dielectric mirrors on Si 3 N4 trampoline resonators. We describe the fabrication process and present data on finesse and quality factor. The authors gratefully acknowledge support from NSF PHY-0804177 and Marie Curie EXT-CT-2006-042580.

Absolute I(asterisk) quantum yields for the ICN A state by diode laser gain-vs-absorption spectroscopy

NASA Technical Reports Server (NTRS)

Hess, Wayne P.; Leone, Stephen R.

1987-01-01

Absolute I(asterisk) quantum yields have been measured as a function of wavelength for room temperature photodissociation of the ICN A state continuum. The yields are obtained by the technique of time-resolved diode laser gain-vs-absorption spectroscopy. Quantum yields are evaluated at seven wavelengths from 248 to 284 nm. The yield at 266 nm is 66.0 + or - 2 percent and it falls off to 53.4 + or - 2 percent and 44.0 + or - 4 percent at 284 and 248 nm, respectively. The latter values are significantly higher than those obtained by previous workers using infrared fluorescence. Estimates of I(asterisk) quantum yields obtained from analysis of CN photofragment rotational distributions, as discussed by other workers, are in good agreement with the I(asterisk) yields reported here. The results are considered in conjunction with recent theoretical and experimental work on the CN rotational distributions and with previous I(asterisk) quantum yield results.

Unity quantum yield of photogenerated charges and band-like transport in quantum-dot solids.

PubMed

Talgorn, Elise; Gao, Yunan; Aerts, Michiel; Kunneman, Lucas T; Schins, Juleon M; Savenije, T J; van Huis, Marijn A; van der Zant, Herre S J; Houtepen, Arjan J; Siebbeles, Laurens D A

2011-09-25

Solid films of colloidal quantum dots show promise in the manufacture of photodetectors and solar cells. These devices require high yields of photogenerated charges and high carrier mobilities, which are difficult to achieve in quantum-dot films owing to a strong electron-hole interaction and quantum confinement. Here, we show that the quantum yield of photogenerated charges in strongly coupled PbSe quantum-dot films is unity over a large temperature range. At high photoexcitation density, a transition takes place from hopping between localized states to band-like transport. These strongly coupled quantum-dot films have electrical properties that approach those of crystalline bulk semiconductors, while retaining the size tunability and cheap processing properties of colloidal quantum dots.

Feeding enhances photosynthetic efficiency in the carnivorous pitcher plant Nepenthes talangensis.

PubMed

Pavlovic, Andrej; Singerová, Lucia; Demko, Viktor; Hudák, Ján

2009-08-01

Cost-benefit models predict that carnivory can increase the rate of photosynthesis (A(N)) by leaves of carnivorous plants as a result of increased nitrogen absorption from prey. However, the cost of carnivory includes decreased A(N) and increased respiration rates (R(D)) of trapping organs. The principal aim of the present study was to assess the costs and benefits of carnivory in the pitcher plant Nepenthes talangensis, leaves of which are composed of a lamina and a pitcher trap, in response to feeding with beetle larvae. Pitchers of Nepenthes grown at 200 micromol m(-2) s(-1) photosynthetically active radiation (PAR) were fed with insect larvae for 2 months, and the effects on the photosynthetic processes were then assessed by simultaneous measurements of gas exchange and chlorophyll fluorescence of laminae and pitchers, which were correlated with nitrogen, carbon and total chlorophyll concentrations. A(N) and maximum (F(v)/F(m)) and effective quantum yield of photosystem II (Phi(PSII)) were greater in the fed than unfed laminae but not in the fed compared with unfed pitchers. Respiration rate was not significantly affected in fed compared with unfed plants. The unfed plants had greater non-photochemical quenching (NPQ) of chlorophyll fluorescence. Higher NPQ in unfed lamina did not compensate for their lower Phi(PSII), resulting in lower photochemical quenching (QP) and thus higher excitation pressure on PSII. Biomass and nitrogen and chlorophyll concentration also increased as a result of feeding. The cost of carnivory was shown by lower A(N) and Phi(PSII) in pitchers than in laminae, but R(D) depended on whether it was expressed on a dry weight or a surface area basis. Correlation between nitrogen and A(N) in the pitchers was not found. Cost-benefit analysis showed a large beneficial effect on photosynthesis from feeding as light intensity increased from 200 to 1000 micromol m(-2) s(-1) PAR after which it did not increase further. All fed plants began to flower. Feeding pitchers with insect larvae increases A(N) of leaf laminae, due to higher nutrient acquisition, with strong correlation with nitrogen concentration, but A(N) of pitchers does not increase, despite increased nitrogen concentration in their tissue. Increased A(N) improves growth and reproduction and is likely to increase the competitive advantage of carnivorous over non-carnivorous plants in nutrient-poor habitats.

An ultracold potassium Rydberg source for experiments in quantum optics and many-body physics

NASA Astrophysics Data System (ADS)

Conover, Charles; Dupre, Pamela; Tong, Ai Phuong; Sanon, Carlvin; Clarke, Kevin; Doolittle, Brian; Louria, Stephen; Adamson, Philip

2017-04-01

We report on the development of an apparatus for the study of quantum dynamics of Rydberg atoms of potassium. Samples of Rydberg atoms at 1 mK and varying density are excited in a magneto-optical trap of 107 K-39 atoms. The atoms are excited to Rydberg states in a steps from 4s to 5p and from 5p to ns and nd states using stabilized external-cavity diode lasers at 405 nm and 980 nm. Selective field ionization and detection with microchannel plates provides a platform for spectroscopic measurements in potassium, exploration of multiphoton processes, and experiments on cold atom collisions. This research was supported by the National Science Foundation under Grant PHY-1126599.

Control of Emission Color of High Quantum Yield CH3NH3PbBr3 Perovskite Quantum Dots by Precipitation Temperature.

PubMed

Huang, He; Susha, Andrei S; Kershaw, Stephen V; Hung, Tak Fu; Rogach, Andrey L

2015-09-01

Emission color controlled, high quantum yield CH 3 NH 3 PbBr 3 perovskite quantum dots are obtained by changing the temperature of a bad solvent during synthesis. The products for temperatures between 0 and 60 °C have good spectral purity with narrow emission line widths of 28-36 nm, high absolute emission quantum yields of 74% to 93%, and short radiative lifetimes of 13-27 ns.

Creating high yield water soluble luminescent graphene quantum dots via exfoliating and disintegrating carbon nanotubes and graphite flakes.

PubMed

Lin, Liangxu; Zhang, Shaowei

2012-10-21

We have developed an effective method to exfoliate and disintegrate multi-walled carbon nanotubes and graphite flakes. With this technique, high yield production of luminescent graphene quantum dots with high quantum yield and low oxidization can be achieved.

Note: Measuring instrument of singlet oxygen quantum yield in photodynamic effects

NASA Astrophysics Data System (ADS)

Li, Zhongwei; Zhang, Pengwei; Zang, Lixin; Qin, Feng; Zhang, Zhiguo; Zhang, Hongli

2017-06-01

Using diphenylisobenzofuran (C20H14O) as a singlet oxygen (1O2) reporter, a comparison method, which can be used to measure the singlet oxygen quantum yield (ΦΔ) of the photosensitizer quantitatively, is presented in this paper. Based on this method, an automatic measuring instrument of singlet oxygen quantum yield is developed. The singlet oxygen quantum yield of the photosensitizer hermimether and aloe-emodin is measured. It is found that the measuring results are identical to the existing ones, which verifies the validity of the measuring instrument.

4-amino-1H-benzo[g]quinazoline-2-one: a fluorescent analog of cytosine to probe protonation sites in triplex forming oligonucleotides.

PubMed

Godde, F; Toulmé, J J; Moreau, S

2000-08-01

We developed a new fluorescent analog of cytosine, the 4-amino-1H-benzo[g]quinazoline-2-one, which constitute a probe sensitive to pH. The 2'-O-Me ribonucleoside derivative of this heterocycle was synthesized and exhibited a fluorescence emission centered at 456 nm, characterized by four major excitation maxima (250, 300, 320 and 370 nm) and a fluorescence quantum yield of Phi = 0.62 at pH 7.1. The fluorescence emission maximum shifted from 456 to 492 nm when pH was decreased from 7.1 to 2.1. The pK(a) (4) was close to that of cytosine (4.17). When introduced in triplex forming oligonucleotides this new nucleoside can be used to reveal the protonation state of triplets in triple-stranded structures. Complex formation was detected by a significant quenching of fluorescence emission (approximately 88%) and the N-3 protonation of the quinazoline ring by a shift of the emission maximum from 485 to 465 nm. Using this probe we unambiguously showed that triplex formation of the pyrimidine motif does not require the protonation of all 4-amino-2-one pyrimidine rings.

Quantum Yields in Mixed-Conifer Forests and Ponderosa Pine Plantations

NASA Astrophysics Data System (ADS)

Wei, L.; Marshall, J. D.; Zhang, J.

2008-12-01

Most process-based physiological models require canopy quantum yield of photosynthesis as a starting point to simulate carbon sequestration and subsequently gross primary production (GPP). The quantum yield is a measure of photosynthetic efficiency expressed in moles of CO2 assimilated per mole of photons absorbed; the process is influenced by environmental factors. In the summer 2008, we measured quantum yields on both sun and shade leaves for four conifer species at five sites within Mica Creek Experimental Watershed (MCEW) in northern Idaho and one conifer species at three sites in northern California. The MCEW forest is typical of mixed conifer stands dominated by grand fir (Abies grandis (Douglas ex D. Don) Lindl.). In northern California, the three sites with contrasting site qualities are ponderosa pine (Pinus ponderosa C. Lawson var. ponderosa) plantations that were experimentally treated with vegetation control, fertilization, and a combination of both. We found that quantum yields in MCEW ranged from ~0.045 to ~0.075 mol CO2 per mol incident photon. However, there were no significant differences between canopy positions, or among sites or tree species. In northern California, the mean value of quantum yield of three sites was 0.051 mol CO2/mol incident photon. No significant difference in quantum yield was found between canopy positions, or among treatments or sites. The results suggest that these conifer species maintain relatively consistent quantum yield in both MCEW and northern California. This consistency simplifies the use of a process-based model to accurately predict forest productivity in these areas.

Progress towards two double-dot qubits in Si/SiGe: quadruple quantum dots

NASA Astrophysics Data System (ADS)

Foote, Ryan H.; Ward, Daniel R.; Kim, Dohun; Thorgrimsson, Brandur; Smith, Luke; Savage, D. E.; Lagally, M. G.; Friesen, Mark; Coppersmith, S. N.; Eriksson, M. A.

We present the fabrication and electrical characterization of two types of gate-defined quadruple quantum dot devices formed in Si/SiGe heterostructures. We compare two designs, one which uses three layers of tightly overlapping gates and is similar to the work found in, and one which uses only two layers of gates and has significantly more open space between neighboring gates. We demonstrate charge-state conditional quantum oscillations in the more open device, we compare the tunability of both devices with each other, and we discuss the implications of these measurements on a path towards larger numbers of coupled quantum dot qubits. This work is supported in part by ARO (W911NF-12-1-0607), NSF (DMR-1206915, PHY-1104660), ONR (N00014-15-1-0029) and the Department of Defense. Development and maintenance of the growth facilities used for fabricating samples supported by DOE (DE-FG02-03ER46028). DK acknowledges support from the Korea Institute of Science and Technology Institutional Program (Project No. 2E26681). This research utilized facilities supported by the NSF (DMR-0832760, DMR-1121288).

Phi-value analysis of apo-azurin folding: comparison between experiment and theory.

PubMed

Zong, Chenghang; Wilson, Corey J; Shen, Tongye; Wolynes, Peter G; Wittung-Stafshede, Pernilla

2006-05-23

Pseudomonas aeruginosa azurin is a 128-residue beta-sandwich metalloprotein; in vitro kinetic experiments have shown that it folds in a two-state reaction. Here, we used a variational free energy functional to calculate the characteristics of the transition state ensemble (TSE) for folding of the apo-form of P. aeruginosa azurin and investigate how it responds to thermal and mutational changes. The variational method directly yields predicted chevron plots for wild-type and mutant apo-forms of azurin. In parallel, we performed in vitro kinetic-folding experiments on the same set of azurin variants using chemical perturbation. Like the wild-type protein, all apo-variants fold in apparent two-state reactions both in calculations and in stopped-flow mixing experiments. Comparisons of phi (phi) values determined from the experimental and theoretical chevron parameters reveal an excellent agreement for most positions, indicating a polarized, highly structured TSE for folding of P. aeruginosa apo-azurin. We also demonstrate that careful analysis of side-chain interactions is necessary for appropriate theoretical description of core mutants.

[Asymmetric biosynthesis of d-pseudoephedrine by recombinant Bacillus subtilis].

PubMed

Peng, Yanhong; Zhang, Liang; Ding, Zhongyang; Wang, Zhengxiang; Shi, Guiyang

2011-07-01

In order to successfully express the carbonyl reductase gene mldh in Bacillus subtilis and complete coenzyme regeneration by B. subtilis glucose dehydrogenase, the promoter PrpsD and the terminator TrpsD from B. subtilis rpsD gene were used as the expression cassette to be a recombinant plasmid pHY300plk-PrpsD-TrpsD. After that, the carbonyl reductase gene mldh was inserted into the previous plasmid and a plasmid pHY300plk-PrpsD-mldh-TrpsD was achieved, followed by transformed into B. subtilis Wb600 to obtain a recombinant B. subtilis Wb600 (pHY300plk-PrpsD-mldh-TrpsD). Subsequently, the results for whole-cell biotransformation from recombinant B. subtilis showed that it could be used to catalyze MAK (1-phenyl- 1-keto-2-methylaminopropane) to d-pseudoephedrine in the presence of glucose. The yield of d-pseudoephedrine could be up to 97.5 mg/L and the conversion rate of MAK was 24.1%. This study indicates the possibility of biotransformation production of d-pseudoephedrine from recombinant B. subtilis.

The effects of nonuniform magnetic field strength on density flux and test particle transport in drift wave turbulence

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

Dewhurst, J. M.; Hnat, B.; Dendy, R. O.

2009-07-15

The extended Hasegawa-Wakatani equations generate fully nonlinear self-consistent solutions for coupled density n and vorticity {nabla}{sup 2}{phi}, where {phi} is electrostatic potential, in a plasma with background density inhomogeneity {kappa}=-{partial_derivative} ln n{sub 0}/{partial_derivative}x and magnetic field strength inhomogeneity C=-{partial_derivative} ln B/{partial_derivative}x. Finite C introduces interchange effects and {nabla}B drifts into the framework of drift turbulence through compressibility of the ExB and diamagnetic drifts. This paper addresses the direct computation of the radial ExB density flux {gamma}{sub n}=-n{partial_derivative}{phi}/{partial_derivative}y, tracer particle transport, the statistical properties of the turbulent fluctuations that drive {gamma}{sub n} and tracer motion, and analytical underpinnings. Systematic trends emergemore » in the dependence on C of the skewness of the distribution of pointwise {gamma}{sub n} and in the relative phase of density-velocity and density-potential pairings. It is shown how these effects, together with conservation of potential vorticity {pi}={nabla}{sup 2}{phi}-n+({kappa}-C)x, account for much of the transport phenomenology. Simple analytical arguments yield a Fickian relation {gamma}{sub n}=({kappa}-C)D{sub x} between the radial density flux {gamma}{sub n} and the radial tracer diffusivity D{sub x}, which is shown to explain key trends in the simulations.« less

Expression of an Aspergillus niger Phytase Gene (phyA) in Saccharomyces cerevisiae

PubMed Central

Han, Yanming; Wilson, David B.; Lei, Xin gen

1999-01-01

Phytase improves the bioavailability of phytate phosphorus in plant foods to humans and animals and reduces phosphorus pollution of animal waste. Our objectives were to express an Aspergillus niger phytase gene (phyA) in Saccharomyces cerevisiae and to determine the effects of glycosylation on the phytase’s activity and thermostability. A 1.4-kb DNA fragment containing the coding region of the phyA gene was inserted into the expression vector pYES2 and was expressed in S. cerevisiae as an active, extracellular phytase. The yield of total extracellular phytase activity was affected by the signal peptide and the medium composition. The expressed phytase had two pH optima (2 to 2.5 and 5 to 5.5) and a temperature optimum between 55 and 60°C, and it cross-reacted with a rabbit polyclonal antibody against the wild-type enzyme. Due to the heavy glycosylation, the expressed phytase had a molecular size of approximately 120 kDa and appeared to be more thermostable than the commercial enzyme. Deglycosylation of the phytase resulted in losses of 9% of its activity and 40% of its thermostability. The recombinant phytase was effective in hydrolyzing phytate phosphorus from corn or soybean meal in vitro. In conclusion, the phyA gene was expressed as an active, extracellular phytase in S. cerevisiae, and its thermostability was affected by glycosylation. PMID:10223979

Recombinant HAP Phytase of the Thermophilic Mold Sporotrichum thermophile: Expression of the Codon-Optimized Phytase Gene in Pichia pastoris and Applications.

PubMed

Ranjan, Bibhuti; Satyanarayana, T

2016-02-01

The codon-optimized phytase gene of the thermophilic mold Sporotrichum thermophile (St-Phy) was expressed in Pichia pastoris. The recombinant P. pastoris harboring the phytase gene (rSt-Phy) yielded a high titer of extracellular phytase (480 ± 23 U/mL) on induction with methanol. The recombinant phytase production was ~40-fold higher than that of the native fungal strain. The purified recombinant phytase (rSt-Phy) has the molecular mass of 70 kDa on SDS-PAGE, with K m and V max (calcium phytate), k cat and k cat/K m values of 0.147 mM and 183 nmol/mg s, 1.3 × 10(3)/s and 8.84 × 10(6)/M s, respectively. Mg(2+) and Ba(2+) display a slight stimulatory effect, while other cations tested exert inhibitory action on phytase. The enzyme is inhibited by chaotropic agents (guanidinium hydrochloride, potassium iodide, and urea), Woodward's reagent K and 2,3-bunatedione, but resistant to both pepsin and trypsin. The rSt-Phy is useful in the dephytinization of broiler feeds efficiently in simulated gut conditions of chick leading to the liberation of soluble inorganic phosphate with concomitant mitigation in antinutrient effects of phytates. The addition of vanadate makes it a potential candidate for generating haloperoxidase, which has several applications.

Absolute 1* quantum yields for the ICN A state by diode laser gain versus absorption spectroscopy

NASA Technical Reports Server (NTRS)

Hess, Wayne P.; Leone, Stephen R.

1987-01-01

Absolute I* quantum yields were measured as a function of wavelength for room temperature photodissociation of the ICN A state continuum. The temperature yields are obtained by the technique of time-resolved diode laser gain-versus-absorption spectroscopy. Quantum yields are evaluated at seven wavelengths from 248 to 284 nm. The yield at 266 nm is 66.0 +/- 2% and it falls off to 53.4 +/- 2% and 44.0 +/- 4% at 284 and 248 respectively. The latter values are significantly higher than those obtained by previous workers using infrared fluorescence. Estimates of I* quantum yields obtained from analysis of CN photofragment rotational distributions, as discussed by other workers, are in good agreement with the I* yields. The results are considered in conjunction with recent theoretical and experimental work on the CN rotational distributions and with previous I* yield results.

Characterization of a gate-defined double quantum dot in a Si/SiGe nanomembrane

NASA Astrophysics Data System (ADS)

Knapp, T. J.; Mohr, R. T.; Li, Yize Stephanie; Thorgrimsson, Brandur; Foote, Ryan H.; Wu, Xian; Ward, Daniel R.; Savage, D. E.; Lagally, M. G.; Friesen, Mark; Coppersmith, S. N.; Eriksson, M. A.

We report the characterization of a gate-defined double quantum dot formed in a Si/SiGe nanomembrane. Previously, all heterostructures used to form quantum dots were created using the strain-grading method of strain relaxation, a method that necessarily introduces misfit dislocations into a heterostructure and thereby degrades the reproducibility of quantum devices. Using a SiGe nanomembrane as a virtual substrate eliminates the need for misfit dislocations but requires a wet-transfer process that results in a non-epitaxial interface in close proximity to the quantum dots. We show that this interface does not prevent the formation of quantum dots, and is compatible with a tunable inter-dot tunnel coupling, the identification of spin states, and the measurement of a singlet-to-triplet transition as a function of the applied magnetic field. This work was supported in part by ARO (W911NF-12-0607), NSF (DMR-1206915, PHY-1104660), and the United States Department of Defense. The views and conclusions contained in this document are those of the author and should not be interpreted as representing the official policies, either expressly or implied, of the US Government. T.J. Knapp et al. (2015). arXiv:1510.08888 [cond-mat.mes-hall].

Photon Tagger Timing Calibration for the Rad Phi Experiment

NASA Astrophysics Data System (ADS)

Russell, Mammei; Smith, Elton

2000-10-01

Vector mesons provide a rich laboratory for the study of fundamental physics and radiative decays probe the very nature of the internal structure of these mesons, which possess the same quantum numbers of photons. Experiment E94-016, which collected data this past summer in Hall B of the Thomas Jefferson National Accelerator Facility (JLab), has measured the the branching ratios for rare radiative decays of the phi meson, i.e. φarrow f_0(975)γ arrow π^0π^0γ, φ arrow a_0(980)γ arrow π0 η γ, and φ arrow η'γ. A lead glass calorimeter, in concert with several detectors, measured these decays. A tagged beam of bremsstrahlung photons was directed upon a solid Beryllium target. A three-level trigger was then employed to preferentially select radiative decays of the φ meson. We calibrated timing of each detector by referencing individual detectors to one another. Tight timing will enhance signal relative to background.

High quantum yield ZnO quantum dots synthesizing via an ultrasonication microreactor method.

PubMed

Yang, Weimin; Yang, Huafang; Ding, Wenhao; Zhang, Bing; Zhang, Le; Wang, Lixi; Yu, Mingxun; Zhang, Qitu

2016-11-01

Green emission ZnO quantum dots were synthesized by an ultrasonic microreactor. Ultrasonic radiation brought bubbles through ultrasonic cavitation. These bubbles built microreactor inside the microreactor. The photoluminescence properties of ZnO quantum dots synthesized with different flow rate, ultrasonic power and temperature were discussed. Flow rate, ultrasonic power and temperature would influence the type and quantity of defects in ZnO quantum dots. The sizes of ZnO quantum dots would be controlled by those conditions as well. Flow rate affected the reaction time. With the increasing of flow rate, the sizes of ZnO quantum dots decreased and the quantum yields first increased then decreased. Ultrasonic power changed the ultrasonic cavitation intensity, which affected the reaction energy and the separation of the solution. With the increasing of ultrasonic power, sizes of ZnO quantum dots first decreased then increased, while the quantum yields kept increasing. The effect of ultrasonic temperature on the photoluminescence properties of ZnO quantum dots was influenced by the flow rate. Different flow rate related to opposite changing trend. Moreover, the quantum yields of ZnO QDs synthesized by ultrasonic microreactor could reach 64.7%, which is higher than those synthesized only under ultrasonic radiation or only by microreactor. Copyright © 2016 Elsevier B.V. All rights reserved.

phyA-GFP is spectroscopically and photochemically similar to phyA and comprises both its native types, phyA' and phyA''.

PubMed

Sineshchekov, Vitaly; Sudnitsin, Artem; Ádám, Éva; Schäfer, Eberhard; Viczián, András

2014-12-01

Low-temperature fluorescence investigations of phyA-GFP used in experiments on its nuclear-cytoplasmic partitioning were carried out. In etiolated hypocotyls of phyA-deficient Arabidopsis thaliana expressing phyA-GFP, it was found that it is similar to phyA in spectroscopic parameters with both its native types, phyA' and phyA'', present and their ratio shifted towards phyA'. In transgenic tobacco hypocotyls, native phyA and rice phyA-GFP were also identical to phyA in the wild type whereas phyA-GFP belonged primarily to the phyA' type. Finally, truncated oat Δ6-12 phyA-GFP expressed in phyA-deficient Arabidopsis was represented by the phyA' type in contrast to full-length oat phyA-GFP with an approximately equal proportion of the two phyA types. This correlates with a previous observation that Δ6-12 phyA-GFP can form only numerous tiny subnuclear speckles while its wild-type counterpart can also localize into bigger and fewer subnuclear protein complexes. Thus, phyA-GFP is spectroscopically and photochemically similar or identical to the native phyA, suggesting that the GFP tag does not affect the chromophore. phyA-GFP comprises phyA'-GFP and phyA''-GFP, suggesting that both of them are potential participants in nuclear-cytoplasmic partitioning, which may contribute to its complexity.

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

Acosta, D.; Affolder, Anthony A.; Albrow, M.G.

The authors have measured the azimuthal angular correlation of b{bar b} production, using 86.5 pb{sup -1} of data collected by Collider Detector at Fermilab (CDF) in p{bar p} collisions at {radical}s = 1.8 TeV during 1994-1995. In high-energy p{bar p} collisions, such as at the Tevatron, b{bar b} production can be schematically categorized into three mechanisms. The leading-order (LO) process is ''flavor creation'', where both b and {bar b} quarks substantially participate in the hard scattering and result in a distinct back-to-back signal in final state. The ''flavor excitation'' and the ''gluon splitting'' processes, which appear at next-leading-order (NLO), aremore » known to make a comparable contribution to total b{bar b} cross section, while providing very different opening angle distributions from the LO process. An azimuthal opening angle between bottom and anti-bottom, {Delta}{phi}, has been used for the correlation measurement to probe the interaction creating b{bar b} pairs. The {Delta}{phi} distribution has been obtained from two different methods. one method measures the {Delta}{phi} between bottom hadrons using events with two reconstructed secondary vertex tags. The other method uses b{bar b} {yields} (J/{psi}X)({ell}X') events, where the charged lepton ({ell}) is an electron (e) or a muon ({mu}), to measure {Delta}{phi} between bottom quarks. The b{bar b} purity is determined as a function of {Delta}{phi} by fitting the decay length of the J/{psi} and the impact parameter of the {ell}. Both methods quantify the contribution from higher-order production mechanisms by the fraction of the b{bar b} pairs produced in the same azimuthal hemisphere, f{sub toward}. The measured f{sub toward} values are consistent with both parton shower Monte Carlo and NLO QCD predictions.« less

A carboxy-terminal fragment of protein mu 1/mu 1C is present in infectious subvirion particles of mammalian reoviruses and is proposed to have a role in penetration.

PubMed Central

Nibert, M L; Fields, B N

1992-01-01

Penetration of a cell membrane as an early event in infection of cells by mammalian reoviruses appears to require a particular type of viral particle, the infectious subvirion particle (ISVP), which is generated from an intact virion by proteolytic cleavage of the outer capsid proteins sigma 3 and mu 1/mu 1C. Characterizations of the structural components and properties of ISVPs are thus relevant to attempts to understand the mechanism of penetration by reoviruses. In this study, a novel, approximately 13-kDa carboxy-terminal fragment (given the name phi) was found to be generated from protein mu 1/mu 1C during in vitro treatments of virions with trypsin or chymotrypsin to yield ISVPs. With trypsin treatment, both the carboxy-terminal fragment phi and the amino-terminal fragment mu 1 delta/delta were shown to be generated and to remain attached to ISVPs in stoichiometric quantities. Sites of protease cleavage were identified in the deduced amino acid sequence of mu 1 by determining the amino-terminal sequences of phi proteins: trypsin cleaves between arginine 584 and isoleucine 585, and chymotrypsin cleaves between tyrosine 581 and glycine 582. Findings in this study indicate that sequences in the phi portion of mu 1/mu 1C may participate in the unique functions attributed to ISVPs. Notably, the delta-phi cleavage junction was predicted to be flanked by a pair of long amphipathic alpha-helices. These amphipathic alpha-helices, together with the myristoyl group at the extreme amino terminus of mu 1/mu 1N, are proposed to interact directly with the lipid bilayer of a cell membrane during penetration by mammalian reoviruses. Images PMID:1328674

Degradation Mechanisms in Blue Phosphorescent Organic Light-Emitting Devices by Exciton-Polaron Interactions: Loss in Quantum Yield versus Loss in Charge Balance.

PubMed

Zhang, Yingjie; Aziz, Hany

2017-01-11

We study the relative importance of deterioration of material quantum yield and charge balance to the electroluminescence stability of PHOLEDs, with a special emphasis on blue devices. Investigations show that the quantum yields of both host and emitter in the emission layer degrade due to exciton-polaron interactions and that the deterioration in material quantum yield plays the primary role in device degradation under operation. On the other hand, the results show that the charge balance factor is also affected by exciton-polaron interactions but only plays a secondary role in determining device stability. Finally, we show that the degradation mechanisms in blue PHOLEDs are fundamentally the same as those in green PHOLEDs. The limited stability of the blue devices is a result of faster deterioration in the quantum yield of the emitter.

A tunable microstrip SQUID amplifier for the Axion Dark Matter eXperiment (ADMX)

NASA Astrophysics Data System (ADS)

O'Kelley, Sean; Hansen, Jorn; Weingarten, Elan; Mueck, Michael; Hilton, Gene; Clarke, John

2014-03-01

We describe a microstrip SQUID (Superconducting QUantum Interference Device) amplifier (MSA) used as the photon detector in the Axion Dark Matter eXperiment (ADMX). Cooled to 100 mK or lower, an optimized MSA approaches the quantum limit of detection. The axion dark matter is detected via Primakoff conversion to a microwave photon in a high-Q (~ 105) tunable microwave cavity, currently cooled to about 1.6 K, in the presence of a 7-tesla magnetic field. The MSA consists of a square loop of thin Nb film, incorporating two Josephson tunnel junctions with resistive shunts to prevent hysteresis in the current-voltage characteristic. The microstrip is a square Nb coil deposited over an intervening insulating layer. Since the photon frequency is determined by the unknown axion mass, the cavity and amplifier must be tunable over a broad frequency range. Tunability is achieved by terminating the microstrip with a GaAs varactor diode with a voltage-controlled capacitance that enables us to vary the resonance from nearly 1/2 to 1/4 of a wavelength. With the SQUID current-biased in the voltage state, we demonstrate a gain of typically 20 dB over nearly one octave, 415 MHz to 800 MHz. Supported by DOE Grants DE-FG02-97ER41029, DE-FG02-96ER40956, DE-AC52-07NA27344, DE-AC03-76SF00098, NSF grants PHY-1067242 and PHY-1306729, and the Livermore LDRD program.

Fluorescence Quantum Yield Measurements of Fluorescent Proteins: A Laboratory Experiment for a Biochemistry or Molecular Biophysics Laboratory Course

ERIC Educational Resources Information Center

Wall, Kathryn P.; Dillon, Rebecca; Knowles, Michelle K.

2015-01-01

Fluorescent proteins are commonly used in cell biology to assess where proteins are within a cell as a function of time and provide insight into intracellular protein function. However, the usefulness of a fluorescent protein depends directly on the quantum yield. The quantum yield relates the efficiency at which a fluorescent molecule converts…

Determination of the rate of photoreduction of O2 in the water-water cycle in watermelon leaves and enhancement of the rate by limitation of photosynthesis.

PubMed

Miyake, C; Yokota, A

2000-03-01

A study was performed to determine how the electron fluxes for the photosynthetic carbon reduction (PCR) and the photorespiratory carbon oxidation (PCO) cycles affect the photoreduction of O2 at PSI, which is the limiting step in the water-water cycle. Simultaneous measurements were made of CO2-gas exchange, transpiration and quantum yield of PSII [phi(PSII)] using leaves of watermelon (Citrullus lanatus). The total electron flux in PSII[Je(PSII)], as estimated from phi(PSII), was always larger than the total electron flux required for the PCR and PCO cycles at various partial pressures of CO2 and O2 and 1,100 micromol photons m(-2)s(-1). This observation suggested the existence of an alternative electron flux (Ja). Ja was divided into O2-dependent [Ja(O2-depend)] and O2-independent [Ja(O2-independ)] components. The magnitude of half Ja(O2-depend), 7.5 to 9.5 micromol e- m(-2)s(-1), and its apparent Km for O2, about 8.0 kPa, could be accounted for by the photoreduction of O2 at PSI either mediated by ferredoxin or catalyzed by monodehydroascorbate reductase. The results indicated that Ja(O2-depend) was driven by the water-water cycle. A decrease in the intercellular partial pressure of CO2 from 23 to 5.0 Pa at 21 kPa O2 enhanced Ja(O2-depend) by a factor of 1.3. Saturation of the activities of both the PCR and PCO cycles by increasing the photon flux density induced Ja. These results indicate the electron flux in PSII that exceeds the flux required for the PCR and PCO cycles induces the photoreduction of O2 in the water-water cycle.

Spectroscopy characterization and quantum yield determination of quantum dots

NASA Astrophysics Data System (ADS)

Contreras Ortiz, S. N.; Mejía Ospino, E.; Cabanzo, R.

2016-02-01

In this paper we show the characterization of two kinds of quantum dots: hydrophilic and hydrophobic, with core and core/shell respectively, using spectroscopy techniques such as UV-Vis, fluorescence and Raman. We determined the quantum yield in the quantum dots using the quinine sulphate as standard. This salt is commonly used because of its quantum yield (56%) and stability. For the CdTe excitation, we used a wavelength of 549nm and for the CdSe/ZnS excitation a wavelength of 527nm. The results show that CdSe/ZnS (49%) has better fluorescence, better quantum dots, and confirm the fluorescence result. The quantum dots have shown a good fluorescence performance, so this property will be used to replace dyes, with the advantage that quantum dots are less toxic than some dyes like the rhodamine. In addition, in this work we show different techniques to find the quantum dots emission: fluorescence spectrum, synchronous spectrum and Raman spectrum.

Quantum magnetism in different AMO systems.

NASA Astrophysics Data System (ADS)

Rey, Ana Maria

One of the most important goals of modern quantum sciences is to learn how to control and entangle many-body systems and use them to make powerful and improved quantum devices, materials and technologies. However, since performing full state tomography does not scale favorably with the number of particles, as the size of quantum systems grow, it becomes extremely challenging to identify, and quantify the buildup of quantum correlations and coherence. In this talk I will report on a protocol that we have developed and experimentally demonstrated in a trapped ion quantum magnet in a Penning trap, which can perform quantum simulations of Ising spin models. In those experiments strong spin-spin interactions can be engineered through optical dipole forces that excite phonons of the crystals. The number of ions can be varied from tens to hundreds with high fidelity control. The protocol uses time reversal of the many-body dynamics, to measure out-of-time-order correlation functions (OTOCs). By measuring a family of OTOCs as a function of a tunable parameter we obtain fine-grained information about the state of the system encoded in the multiple quantum coherence spectrum, extract the quantum state purity, and demonstrate the build-up of up to 8-body correlations. We also use the protocol and comparisons to a full solution of the master equation to investigate the impact of spin-motion entanglement and decoherence in the quantum dynamics. Future applications of this protocol could enable studies of manybody localization, quantum phase transitions, and tests of the holographic duality between quantum and gravitational systems. Supported by NSF-PHY-1521080, JILA-NSF PFC-1125844, ARO and AFOSR-MURI.

Nicotine can skew the characterization of the macrophage type-1 (M{Phi}1) phenotype differentiated with granulocyte-macrophage colony-stimulating factor to the M{Phi}2 phenotype

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

Yanagita, Manabu; Kobayashi, Ryohei; Murakami, Shinya, E-mail: ipshinya@dent.osaka-u.ac.jp

Macrophages (M{Phi}s) exhibit functional heterogeneity and plasticity in the local microenvironment. Recently, it was reported that M{Phi}s can be divided into proinflammatory M{Phi}s (M{Phi}1) and anti-inflammatory M{Phi}s (M{Phi}2) based on their polarized functional properties. Here, we report that nicotine, the major ingredient of cigarette smoke, can modulate the characteristics of M{Phi}1. Granulocyte-macrophage colony-stimulating factor-driven M{Phi}1 with nicotine (Ni-M{Phi}1) showed the phenotypic characteristics of M{Phi}2. Like M{Phi}2, Ni-M{Phi}1 exhibited antigen-uptake activities. Ni-M{Phi}1 suppressed IL-12, but maintained IL-10 and produced high amounts of MCP-1 upon lipopolysaccharide stimulation compared with M{Phi}1. Moreover, we observed strong proliferative responses of T cells to lipopolysaccharide-stimulated M{Phi}1,more » whereas Ni-M{Phi}1 reduced T cell proliferation and inhibited IFN-{gamma} production by T cells. These results suggest that nicotine can change the functional characteristics of M{Phi} and skew the M{Phi}1 phenotype to M{Phi}2. We propose that nicotine is a potent regulator that modulates immune responses in microenvironments.« less

Coronal Heating and the Increase of Coronal Luminosity with Magnetic Flux

NASA Technical Reports Server (NTRS)

Moore, R. L.; Falconer, D. A.; Porter, J. G.; Hathaway, D. H.; Six, N. Frank (Technical Monitor)

2002-01-01

We present the observed scaling of coronal luminosity with magnetic flux in a set of quiet regions. Comparison of this with the observed scaling found for active regions suggests an underlying difference between coronal heating in active regions and quiet regions. From SOHO/EIT coronal images and SOHO/MDI magnetograms of four similar large quiet regions, we measure L(sub corona) and Phi(sub total) in random subregions ranging in area from about four supergranules [(70,000 km)(exp 2)] to about 100 supergranules [(0.5 R(sub sun))(exp 2)], where L(sub corona) is the luminosity of the corona in a subregion and Phi(sub total) is the flux content of the magnetic network in the subregion. This sampling of our quiet regions yields a correlation plot of Log L(sub corona) vs Log Phi(sub total) appropriate for comparison with the corresponding plot for active regions. For our quiet regions, the mean values of L(sub corona) and Phi(sub total) both increase linearly with area (simply because each set of subregions of the same area has very nearly the same mean coronal luminosity per unit area and mean magnetic flux per unit area), and in each constant-area set the values of L(sub corona) and Phi(sub total) 'scatter' about their means for that area. This results in the linear least-squares fit to the Log ((L (sub corona)), vs Log ((Phi (sub total)) plot having a slope somewhat less than one. If active regions mimicked our quiet regions in that all large sets of same-area active regions had the same mean coronal luminosity per unit area and same mean magnetic flux per unit area, then the least-squares fit to their Log((L (sub corona)) vs Log((Phi (sub total)) plot would also have a slope of less than one. Instead, the slope for active regions is 1.2. Given the observed factor of three scatter about the least-squares linear fit, this slope is consistent with Phi(sub total) on average increasing linearly with area (A) as in quiet regions, but L(sub corona) on average increasing as the volume (A(exp 1.5)) of the active region instead of as the area. This possibility is reasonable if the heating in active regions is a burning down of previously-stored coronal magnetic energy rather than a steady dissipation of energy flux from below as expected in quiet regions.

An application of geostatistics and fractal geometry for reservoir characterization

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

Aasum, Y.; Kelkar, M.G.; Gupta, S.P.

1991-03-01

This paper presents an application of geostatistics and fractal geometry concepts for 2D characterization of rock properties (k and {phi}) in a dolomitic, layered-cake reservoir. The results indicate that lack of closely spaced data yield effectively random distributions of properties. Further, incorporation of geology reduces uncertainties in fractal interpolation of wellbore properties.

Summing up the Euler [phi] Function

ERIC Educational Resources Information Center

Loomis, Paul; Plytage, Michael; Polhill, John

2008-01-01

The Euler [phi] function counts the number of positive integers less than and relatively prime to a positive integer n. Here we look at perfect totient numbers, number for which [phi](n) + [phi]([phi](n)) + [phi]([phi]([phi](n))) + ... + 1 = n.

Minimized virus binding for tests of barrier materials.

PubMed Central

Lytle, C D; Routson, L B

1995-01-01

Viruses are used to test the barrier properties of materials. Binding of virus particles during passage through holes in the material may yield misleading test results. The choices of challenge virus and suspending medium may be important for minimizing confounding effects that might arise from such binding. In this study, different surrogate viruses, as well as different support media, were evaluated to determine optimal test parameters. Two membranes with high-binding properties (nitrocellulose and cationic polysulfone) were used as filters to compare binding activities of different surrogate challenge viruses (MS2, phi X174, T7, PRD1, and phi 6) in different media. The media consisted of buffered saline with surfactants, serum, or culture broth as additives. In addition, elution rates of viruses that bound to the membranes were determined. The results suggest that viruses can bind by hydrophobic and electrostatic interactions, with phi X174 displaying the lowest level of binding by either process. The nonionic detergents Triton X-100 and Tween 80 (0.1%) equally minimized hydrophobic interactions. Neither anionic nor cationic surfactants were as effective at nontoxic levels. Serum was effective at reducing both hydrophobic and electrostatic binding, with 2% being sufficient for eliminating binding under our test conditions. Thus, phi X174 remains the best choice as a surrogate virus to test barrier materials, and Triton X-100 (0.1%) remains a good choice for reducing hydrophobic binding. In addition, binding of viruses by barrier materials is unlikely to prevent passage of blood-borne pathogens. PMID:7574603

Quantum Yields of Soluble and Particulate Material in the Ocean

DTIC Science & Technology

1999-09-30

and prospects. IEEE Transactions, 46(5): 825-829 In Press Moisan, T.A. & B.G. Mitchell UV Absorption by Mycosporine - like Amino Acids in Phaeocystis...were grown to evaluate the spectral quantum yield of in vivo chlorophyll a fluorescence. We determined that mycosporine amino acids with UV absorption...evaluate the role of photoprotective pigments, including mycosporine amino acids and the xanthophyll pigments in Phaeocystis, on the spectral quantum yield

[Genome Rearrangements in Azospirillum brasilense Sp7 with the Involvement of the Plasmid pRhico and the Prophage phiAb-Cd].

PubMed

Katsy, E I; Petrova, L P

2015-12-01

Alphaproteobacteria of the species Azospirillum brasilense have a multicomponent genome that undergoes frequent spontaneous rearrangements, yielding changes in the plasmid profiles of strains. Specifically, variants (Cd, Sp7.K2, Sp7.1, Sp7.4, Sp7.8, etc.) of the type strainA. brasilense Sp7 that had lost a 115-MDa plasmid were previously selected. In many of them, the molecular weight of a 90-MDa plasmid (p90 or pRhico), which is a kind of "depot" for glycopolymer biosynthesis genes, increased. In this study, a collection of primers was designed to the plasmid pRhico and to the DNA of prophage phiAb-Cd integrated in it. The use ofthese primers in polymerase chain reactions allowed the detection of the probable excision of phiAb-Cd phage from the DNA of A. brasilense variants Sp7.4 and Sp7.8 and other alterations of the pRhico structure in A. brasilense strains Cd, Sp7.K2, and Sp7.8. The developed primers and PCR conditions may be recoin mended for primary analysis of spontaneous plasmid rearrangements in A. brasilense Sp7 and related strains.

Electron spin control and spin-libration coupling of a levitated nanodiamond

NASA Astrophysics Data System (ADS)

Hoang, Thai; Ma, Yue; Ahn, Jonghoon; Bang, Jaehoon; Robicheaux, Francis; Gong, Ming; Yin, Zhang-Qi; Li, Tongcang

2017-04-01

Hybrid spin-mechanical systems have great potentials in sensing, macroscopic quantum mechanics, and quantum information science. Recently, we optically levitated a nanodiamond and demonstrated electron spin control of its built-in nitrogen-vacancy (NV) centers in vacuum. We also observed the libration (torsional vibration) of a nanodiamond trapped by a linearly polarized laser beam in vacuum. We propose to achieve strong coupling between the electron spin of a NV center and the libration of a levitated nanodiamond with a uniform magnetic field. With a uniform magnetic field, multiple spins can couple to the torsional vibration at the same time. We propose to use this strong coupling to realize the Lipkin-Meshkov-Glick (LMG) model and generate rotational superposition states. This work is supported by the National Science Foundation under Grant No. 1555035-PHY.

[Fluorescence spectra and quantum yield of TiO2 nanocrystals synthesized by alcohothermal method].

PubMed

Song, Cui-Hong; Li, Yan-Ting; Li, Jing; Wei, Yong-Ju; Hu, Yu-Zhu; Wei, Yu

2008-01-01

Fluorescence spectra and fluorescence quantum yield of TiO2 nanocrystals were studied. Using tetra n-butyl titanate as a starting material, a facile alcohothermal technique was used to synthesize TiO2 nanocrystals. As can be seen from the transmittance electron microscopy (TEM) image, TiO2 nanocrystals with a relatively uniform particle size distribution of < 10 nm are present in the transparent sol. The transparent sol presents a strong stable fluorescence emission with a maximum at 450 nm, which is greatly dependent on the size quantization effects, defect energy level and the surface state of TiO2 nanocrystals. The quantum yield (gamma) of TiO2 was determined by the relative comparison procedure, using freshly prepared analytical purity quinine sulfate in 0.05 mol x L(-1) H2SO4 as a relative quantum yield standard. The emission quantum yield of TiO2 nanocrystals prepared in alcoholic media was calculated to be about 0.20 at wavelengths ranging from 330 to 370 nm, which was much higher than the values reported in previous works. So, it is supposed that nano-TiO2 will be applied as a potential quantum dots fluorescence probe in biological analysis.

Ensemble brightening and enhanced quantum yield in size-purified silicon nanocrystals

DOE PAGES

Miller, Joseph B.; Van Sickle, Austin R.; Anthony, Rebecca J.; ...

2012-07-18

Here, we report on the quantum yield, photoluminescence (PL) lifetime and ensemble photoluminescent stability of highly monodisperse plasma-synthesized silicon nanocrystals (SiNCs) prepared though density-gradient ultracentrifugation in mixed organic solvents. Improved size uniformity leads to a reduction in PL line width and the emergence of entropic order in dry nanocrystal films. We find excellent agreement with the anticipated trends of quantum confinement in nanocrystalline silicon, with a solution quantum yield that is independent of nanocrystal size for the larger fractions but decreases dramatically with size for the smaller fractions. We also find a significant PL enhancement in films assembled from themore » fractions, and we use a combination of measurement, simulation and modeling to link this ‘brightening’ to a temporally enhanced quantum yield arising from SiNC interactions in ordered ensembles of monodisperse nanocrystals. Using an appropriate excitation scheme, we exploit this enhancement to achieve photostable emission.« less

Overexpression of phyA and appA Genes Improves Soil Organic Phosphorus Utilisation and Seed Phytase Activity in Brassica napus

PubMed Central

Wang, Yi; Ye, Xiangsheng; Ding, Guangda; Xu, Fangsen

2013-01-01

Phytate is the major storage form of organic phosphorus in soils and plant seeds, and phosphorus (P) in this form is unavailable to plants or monogastric animals. In the present study, the phytase genes phyA and appA were introduced into Brassica napus cv Westar with a signal peptide sequence and CaMV 35S promoter, respectively. Three independent transgenic lines, P3 and P11 from phyA and a18 from appA, were selected. The three transgenic lines exhibited significantly higher exuded phytase activity when compared to wild-type (WT) controls. A quartz sand culture experiment demonstrated that transgenic Brassica napus had significantly improved P uptake and plant biomass. A soil culture experiment revealed that seed yields of transgenic lines P11 and a18 increased by 20.9% and 59.9%, respectively, when compared to WT. When phytate was used as the sole P source, P accumulation in seeds increased by 20.6% and 46.9% with respect to WT in P11 and a18, respectively. The P3 line accumulated markedly more P in seeds than WT, while no significant difference was observed in seed yields when phytate was used as the sole P source. Phytase activities in transgenic canola seeds ranged from 1,138 to 1,605 U kg–1 seeds, while no phytase activity was detected in WT seeds. Moreover, phytic acid content in P11 and a18 seeds was significantly lower than in WT. These results introduce an opportunity for improvement of soil and seed phytate-P bioavailability through genetic manipulation of oilseed rape, thereby increasing plant production and P nutrition for monogastric animals. PMID:23573285

Aeronomical determinations of the quantum yields of O (1S) and O (1D) from dissociative recombination of O2(+)

NASA Technical Reports Server (NTRS)

Yee, Jeng-Hwa; Abreu, Vincent J.; Colwell, William B.

1989-01-01

Data from the visible-airglow experiment on the Atmosphere Explorer-E satellite have been used to determine the quantum yields of O (1S) and O (1D) from the dissociative recombination of O2(+) based on a constant total recombination rate from each vibrational level. A range of values between 0.05 and 0.18 has been obtained for the quantum yield of O (1S) and shows a positive correlation with the extent of the vibrational excitation of O2(+). The quantum yield of O (1D) has been measured to be 0.9 + or - 0.2, with no apparent dependence on the vibrational distribution of O2(+).

Tuning Single Quantum Dot Emission with a Micromirror.

PubMed

Yuan, Gangcheng; Gómez, Daniel; Kirkwood, Nicholas; Mulvaney, Paul

2018-02-14

The photoluminescence of single quantum dots fluctuates between bright (on) and dark (off) states, also termed fluorescence intermittency or blinking. This blinking limits the performance of quantum dot-based devices such as light-emitting diodes and solar cells. However, the origins of the blinking remain unresolved. Here, we use a movable gold micromirror to determine both the quantum yield of the bright state and the orientation of the excited state dipole of single quantum dots. We observe that the quantum yield of the bright state is close to unity for these single QDs. Furthermore, we also study the effect of a micromirror on blinking, and then evaluate excitation efficiency, biexciton quantum yield, and detection efficiency. The mirror does not modify the off-time statistics, but it does change the density of optical states available to the quantum dot and hence the on times. The duration of the on times can be lengthened due to an increase in the radiative recombination rate.

Observation of {chi}{sub cJ} Radiative Decays to Light Vector Mesons

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

Bennett, J. V.; Mitchell, R. E.; Shepherd, M. R.

2008-10-10

Using a total of 2.74x10{sup 7} decays of the {psi}(2S) collected with the CLEO-c detector, we present a study of {chi}{sub cJ}{yields}{gamma}V, where V={rho}{sup 0}, {omega}, {phi}. The transitions {chi}{sub c1}{yields}{gamma}{rho}{sup 0} and {chi}{sub c1}{yields}{gamma}{omega} are observed with B({chi}{sub c1}{yields}{gamma}{rho}{sup 0})=(2.43{+-}0.19{+-}0.22)x10{sup -4} and B({chi}{sub c1}{yields}{gamma}{omega})=(8.3{+-}1.5{+-}1.2)x10{sup -5}. In the {chi}{sub c1}{yields}{gamma}{rho}{sup 0} transition, the final state meson is dominantly longitudinally polarized. Upper limits on the branching fractions of other {chi}{sub cJ} states to light vector mesons are presented.

Premixed flame propagation in combustible particle cloud mixtures

NASA Technical Reports Server (NTRS)

Seshadri, K.; Yang, B.

1993-01-01

The structures of premixed flames propagating in combustible systems, containing uniformly distributed volatile fuel particles, in an oxidizing gas mixtures is analyzed. The experimental results show that steady flame propagation occurs even if the initial equivalence ratio of the combustible mixture based on the gaseous fuel available in the particles, phi(u) is substantially larger than unity. A model is developed to explain these experimental observations. In the model it is presumed that the fuel particles vaporize first to yield a gaseous fuel of known chemical composition which then reacts with oxygen in a one-step overall process. It is shown that the interplay of vaporization kinetics and oxidation process, can result in steady flame propagation in combustible mixtures where the value of phi(u) is substantially larger than unity. This prediction is in agreement with experimental observations.

An efficient MPI/OpenMP parallelization of the Hartree–Fock–Roothaan method for the first generation of Intel® Xeon Phi™ processor architecture

DOE PAGES

Mironov, Vladimir; Moskovsky, Alexander; D’Mello, Michael; ...

2017-10-04

The Hartree-Fock (HF) method in the quantum chemistry package GAMESS represents one of the most irregular algorithms in computation today. Major steps in the calculation are the irregular computation of electron repulsion integrals (ERIs) and the building of the Fock matrix. These are the central components of the main Self Consistent Field (SCF) loop, the key hotspot in Electronic Structure (ES) codes. By threading the MPI ranks in the official release of the GAMESS code, we not only speed up the main SCF loop (4x to 6x for large systems), but also achieve a significant (>2x) reduction in the overallmore » memory footprint. These improvements are a direct consequence of memory access optimizations within the MPI ranks. We benchmark our implementation against the official release of the GAMESS code on the Intel R Xeon PhiTM supercomputer. Here, scaling numbers are reported on up to 7,680 cores on Intel Xeon Phi coprocessors.« less

An efficient tensor transpose algorithm for multicore CPU, Intel Xeon Phi, and NVidia Tesla GPU

NASA Astrophysics Data System (ADS)

Lyakh, Dmitry I.

2015-04-01

An efficient parallel tensor transpose algorithm is suggested for shared-memory computing units, namely, multicore CPU, Intel Xeon Phi, and NVidia GPU. The algorithm operates on dense tensors (multidimensional arrays) and is based on the optimization of cache utilization on x86 CPU and the use of shared memory on NVidia GPU. From the applied side, the ultimate goal is to minimize the overhead encountered in the transformation of tensor contractions into matrix multiplications in computer implementations of advanced methods of quantum many-body theory (e.g., in electronic structure theory and nuclear physics). A particular accent is made on higher-dimensional tensors that typically appear in the so-called multireference correlated methods of electronic structure theory. Depending on tensor dimensionality, the presented optimized algorithms can achieve an order of magnitude speedup on x86 CPUs and 2-3 times speedup on NVidia Tesla K20X GPU with respect to the naïve scattering algorithm (no memory access optimization). The tensor transpose routines developed in this work have been incorporated into a general-purpose tensor algebra library (TAL-SH).

Solvent Dependency in the Quantum Efficiency of 4-[(4-Aminophenyl)-(4-imino-1-cyclohexa-2, 5- dienylidene) methyl] Aniline Hydrochloride.

PubMed

Pathrose, Bini; Nampoori, V P N; Radhakrishnan, P; Sahira, H; Mujeeb, A

2015-05-01

In the present work dual beam thermal lens technique is used for studying the solvent dependency on the quantum efficiency of a novel dye used for biomedical applications. The role of solvent in the absolute fluorescence quantum yield of 4-[(4-Aminophenyl)-(4-imino-1-cyclohexa-2, 5- dienylidene) methyl] aniline hydrochloride is studied using thermal lens technique. It is observed that the variation in solvents and its concentration results considerable variations in the fluorescence quantum yield. These variations are due to the non-radiative relaxation of the absorbed energy and because of the different solvent properties. The highest quantum yield of the dye is observed in the polar protic solvent-water.

In Search of the Perfect Photocage: Structure-Reactivity Relationships in meso-Methyl BODIPY Photoremovable Protecting Groups.

PubMed

Slanina, Tomáš; Shrestha, Pradeep; Palao, Eduardo; Kand, Dnyaneshwar; Peterson, Julie A; Dutton, Andrew S; Rubinstein, Naama; Weinstain, Roy; Winter, Arthur H; Klán, Petr

2017-10-25

A detailed investigation of the photophysical parameters and photochemical reactivity of meso-methyl BODIPY photoremovable protecting groups was accomplished through systematic variation of the leaving group (LG) and core substituents as well as substitutions at boron. Efficiencies of the LG release were evaluated using both steady-state and transient absorption spectroscopies as well as computational analyses to identify the optimal structural features. We find that the quantum yields for photorelease with this photocage are highly sensitive to substituent effects. In particular, we find that the quantum yields of photorelease are improved with derivatives with higher intersystem crossing quantum yields, which can be promoted by core heavy atoms. Moreover, release quantum yields are dramatically improved by boron alkylation, whereas alkylation in the meso-methyl position has no effect. Better LGs are released considerably more efficiently than poorer LGs. We find that these substituent effects are additive, for example, a 2,6-diiodo-B-dimethyl BODIPY photocage features quantum yields of 28% for the mediocre LG acetate and a 95% quantum yield of release for chloride. The high chemical and quantum yields combined with the outstanding absorption properties of BODIPY dyes lead to photocages with uncaging cross sections over 10 000 M -1 cm -1 , values that surpass cross sections of related photocages absorbing visible light. These new photocages, which absorb strongly near the second harmonic of an Nd:YAG laser (532 nm), hold promise for manipulating and interrogating biological and material systems with the high spatiotemporal control provided by pulsed laser irradiation, while avoiding the phototoxicity problems encountered with many UV-absorbing photocages. More generally, the insights gained from this structure-reactivity relationship may aid in the development of new highly efficient photoreactions.

Quantum yield measurements of light-induced H₂ generation in a photosystem I-[FeFe]-H₂ase nanoconstruct.

PubMed

Applegate, Amanda M; Lubner, Carolyn E; Knörzer, Philipp; Happe, Thomas; Golbeck, John H

2016-01-01

The quantum yield for light-induced H2 generation was measured for a previously optimized bio-hybrid cytochrome c 6-crosslinked PSI(C13G)-1,8-octanedithiol-[FeFe]-H2ase(C97G) (PSI-H2ase) nanoconstruct. The theoretical quantum yield for the PSI-H2ase nanoconstruct is 0.50 molecules of H2 per photon absorbed, which equates to a requirement of two photons per H2 generated. Illumination of the PSI-H2ase nanoconstruct with visible light between 400 and 700 nm resulted in an average quantum yield of 0.10-0.15 molecules of H2 per photon absorbed, which equates to a requirement of 6.7-10 photons per H2 generated. A possible reason for the difference between the theoretical and experimental quantum yield is the occurrence of non-productive PSI(C13G)-1,8-octanedithiol-PSIC13G (PSI-PSI) conjugates, which would absorb light without generating H2. Assuming the thiol-Fe coupling is equally efficient at producing PSI-PSI conjugates as well as in producing PSI-H2ase nanoconstructs, the theoretical quantum yield would decrease to 0.167 molecules of H2 per photon absorbed, which equates to 6 photons per H2 generated. This value is close to the range of measured values in the current study. A strategy that purifies the PSI-H2ase nanoconstructs from the unproductive PSI-PSI conjugates or that incorporates different chemistries on the PSI and [FeFe]-H2ase enzyme sites could potentially allow the PSI-H2ase nanoconstruct to approach the expected theoretical quantum yield for light-induced H2 generation.

Photogeneration of reactive transient species upon irradiation of natural water samples: Formation quantum yields in different spectral intervals, and implications for the photochemistry of surface waters.

PubMed

Marchisio, Andrea; Minella, Marco; Maurino, Valter; Minero, Claudio; Vione, Davide

2015-04-15

Chromophoric dissolved organic matter (CDOM) in surface waters is a photochemical source of several transient species such as CDOM triplet states ((3)CDOM*), singlet oxygen ((1)O2) and the hydroxyl radical (OH). By irradiation of lake water samples, it is shown here that the quantum yields for the formation of these transients by CDOM vary depending on the irradiation wavelength range, in the order UVB > UVA > blue. A possible explanation is that radiation at longer wavelengths is preferentially absorbed by the larger CDOM fractions, which show lesser photoactivity compared to smaller CDOM moieties. The quantum yield variations in different spectral ranges were definitely more marked for (3)CDOM* and OH compared to (1)O2. The decrease of the quantum yields with increasing wavelength has important implications for the photochemistry of surface waters, because long-wavelength radiation penetrates deeper in water columns compared to short-wavelength radiation. The average steady-state concentrations of the transients ((3)CDOM*, (1)O2 and OH) were modelled in water columns of different depths, based on the experimentally determined wavelength trends of the formation quantum yields. Important differences were found between such modelling results and those obtained in a wavelength-independent quantum yield scenario. Copyright © 2015 Elsevier Ltd. All rights reserved.

Reaction pathways of photoexcited retinal in proteorhodopsin studied by pump-dump-probe spectroscopy.

PubMed

Rupenyan, Alisa; van Stokkum, Ivo H M; Arents, Jos C; van Grondelle, Rienk; Hellingwerf, Klaas J; Groot, Marie Louise

2009-12-17

Proteorhodopsin (pR) is a membrane-embedded proton pump from the microbial rhodopsin family. Light absorption by its retinal chromophore initiates a photocycle, driven by trans/cis isomerization on the femtosecond to picosecond time scales. Here, we report a study on the photoisomerization dynamics of the retinal chromophore of pR, using dispersed ultrafast pump-dump-probe spectroscopy. The application of a pump pulse initiates the photocycle, and with an appropriately tuned dump pulse applied at a time delay after the dump, the molecules in the initial stages of the photochemical process can be de-excited and driven back to the ground state. In this way, we were able to resolve an intermediate on the electronic ground state that represents chromophores that are unsuccessful in isomerization. In particular, the fractions of molecules that undergo slow isomerization (20 ps) have a high probability to enter this state rather than the isomerized K-state. On the ground state reaction surface, return to the stable ground state conformation via a structural or vibrational relaxation occurs in 2-3 ps. Inclusion of this intermediate in the kinetic scheme led to more consistent spectra of the retinal-excited state, and to a more accurate estimation of the quantum yield of isomerization (Phi = 0.4 at pH 6).

Fluorescence imaging and dynamics of intracellular ionic concentrations in single living cells: application to pHi and Mgi variations

NASA Astrophysics Data System (ADS)

Viallet, Pierre M.; Yassine, Mohamed; Salmon, Jean-Marie; Vigo, Jean

1996-05-01

The intracellular concentration of ions such as H+, Hg2+, Ca2+ is known to monitor the activity of many intracellular enzymes. Furthermore these ions are considered as intracellular messengers involved in signal transducing. Moreover recent technological progresses gave rise to the feeling that accurate data are instantly accessible on microvolumes. So the determination of ionic intracellular concentrations has been achieved using fluorescent specific probes and different equipments (Microspectrofluorometer, Flow Cytometer, Numerical Image Analyzer with or without Confocal system), without taking care of the physico-chemical properties of the probe. Unfortunately fluorescent probes are supposed to fill up conflicting requirements in terms of ionic affinity, specificity, fluorescence quantum yield of the free and ion-bound probe, absence of fading and diffusibility out of the cell. Because most of the probes are not so specific than it is claimed, unexpected interactions may obscure the interpretation of results and even make it difficult to get an intracellular calibration curve. Such a situation generally precludes the use of the popular simplest methods of data acquisition and treatment. The scope of this presentation is to point out some underestimated difficulties, to discuss different ways for bypassing some of them and to rationale the use of Videomicrofluorometry.

Quantum Yield Heterogeneity among Single Nonblinking Quantum Dots Revealed by Atomic Structure-Quantum Optics Correlation

DOE PAGES

Orfield, Noah J.; McBride, James R.; Wang, Feng; ...

2016-02-05

Physical variations in colloidal nanostructures give rise to heterogeneity in expressed optical behavior. This correlation between nanoscale structure and function demands interrogation of both atomic structure and photophysics at the level of single nanostructures to be fully understood. In this paper, by conducting detailed analyses of fine atomic structure, chemical composition, and time-resolved single-photon photoluminescence data for the same individual nanocrystals, we reveal inhomogeneity in the quantum yields of single nonblinking “giant” CdSe/CdS core/shell quantum dots (g-QDs). We find that each g-QD possesses distinctive single exciton and biexciton quantum yields that result mainly from variations in the degree of charging,more » rather than from volume or structure inhomogeneity. We further establish that there is a very limited nonemissive “dark” fraction (<2%) among the studied g-QDs and present direct evidence that the g-QD core must lack inorganic passivation for the g-QD to be “dark”. Finally and therefore, in contrast to conventional QDs, ensemble photoluminescence quantum yield is principally defined by charging processes rather than the existence of dark g-QDs.« less

System and method for constructing filters for detecting signals whose frequency content varies with time

DOEpatents

Qian, S.; Dunham, M.E.

1996-11-12

A system and method are disclosed for constructing a bank of filters which detect the presence of signals whose frequency content varies with time. The present invention includes a novel system and method for developing one or more time templates designed to match the received signals of interest and the bank of matched filters use the one or more time templates to detect the received signals. Each matched filter compares the received signal x(t) with a respective, unique time template that has been designed to approximate a form of the signals of interest. The robust time domain template is assumed to be of the order of w(t)=A(t)cos(2{pi}{phi}(t)) and the present invention uses the trajectory of a joint time-frequency representation of x(t) as an approximation of the instantaneous frequency function {phi}{prime}(t). First, numerous data samples of the received signal x(t) are collected. A joint time frequency representation is then applied to represent the signal, preferably using the time frequency distribution series. The joint time-frequency transformation represents the analyzed signal energy at time t and frequency f, P(t,f), which is a three-dimensional plot of time vs. frequency vs. signal energy. Then P(t,f) is reduced to a multivalued function f(t), a two dimensional plot of time vs. frequency, using a thresholding process. Curve fitting steps are then performed on the time/frequency plot, preferably using Levenberg-Marquardt curve fitting techniques, to derive a general instantaneous frequency function {phi}{prime}(t) which best fits the multivalued function f(t). Integrating {phi}{prime}(t) along t yields {phi}{prime}(t), which is then inserted into the form of the time template equation. A suitable amplitude A(t) is also preferably determined. Once the time template has been determined, one or more filters are developed which each use a version or form of the time template. 7 figs.

The Broken Ring: Reduced Aromaticity in Lys-Trp Cations and High pH Tautomer Correlates with Lower Quantum Yield and Shorter Lifetimes

PubMed Central

2015-01-01

Several nonradiative processes compete with tryptophan fluorescence emission. The difficulty in spectral interpretation lies in associating specific molecular environmental features with these processes and thereby utilizing the fluorescence spectral data to identify the local environment of tryptophan. Here, spectroscopic and molecular modeling study of Lys-Trp dipeptide charged species shows that backbone-ring interactions are undistinguished. Instead, quantum mechanical ground state isosurfaces reveal variations in indole π electron distribution and density that parallel charge (as a function of pK1, pK2, and pKR) on the backbone and residues. A pattern of aromaticity-associated quantum yield and fluorescence lifetime changes emerges. Where quantum yield is high, isosurfaces have a charge distribution similar to the highest occupied molecular orbital (HOMO) of indole, which is the dominant fluorescent ground state of the 1La transition dipole moment. Where quantum yield is low, isosurface charge distribution over the ring is uneven, diminished, and even found off ring. At pH 13, the indole amine is deprotonated, and Lys-Trp quantum yield is extremely low due to tautomer structure that concentrates charge on the indole amine; the isosurface charge distribution bears scant resemblance to the indole HOMO. Such greatly diminished fluorescence has been observed for proteins where the indole nitrogen is hydrogen bonded, lending credence to the association of aromaticity changes with diminished quantum yield in proteins as well. Thus tryptophan ground state isosurfaces are an indicator of indole aromaticity, signaling the partition of excitation energy between radiative and nonradiative processes. PMID:24882092

{phi} meson production in pp annihilation at rest

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

Srisuphaphon, S.; Yan, Y.; Thailand Center of Excellence in Physics, Ministry of Education, Bangkok

2011-10-01

Apparent channel-dependent violations of the Okubo-Zwieg-Iizuka (OZI) rule in nucleon-antinucleon annihilation reactions in the presence of an intrinsic strangeness component in the nucleon are discussed. Admixture of ss quark pairs in the nucleon wave function enables the direct coupling to the {phi}-meson in the annihilation channel without violating the OZI rule. Three forms are considered in this work for the strangeness content of the proton wave function, namely, the uud cluster with a ss sea-quark component, kaon-hyperon clusters based on a simple chiral quark model, and the pentaquark picture uudss. Nonrelativistic quark model calculations reveal that the strangeness magnetic momentmore » {mu}{sub s} and the strangeness contribution to the proton spin {sigma}{sub s} from the first two models are consistent with recent experimental data, where {mu}{sub s} and {sigma}{sub s} are negative. For the third model, the uuds subsystem with the configurations [31]{sub FS}[211]{sub F}[22]{sub S} and [31]{sub FS}[31]{sub F}[22]{sub S} leads to negative values of {mu}{sub s} and {sigma}{sub s}. With effective quark line diagrams incorporating the {sup 3}P{sub 0} model, we give estimates for the branching ratios of the annihilation reactions at rest pp{yields}{phi}X (X={pi}{sup 0}, {eta}, {rho}{sup 0}, {omega}). Results for the branching ratios of {phi}X production from atomic pp s-wave states are for the first and third model found to be strongly channel dependent, in good agreement with measured rates.« less

Diagrammar in classical scalar field theory

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

Cattaruzza, E., E-mail: Enrico.Cattaruzza@gmail.com; Gozzi, E., E-mail: gozzi@ts.infn.it; INFN, Sezione di Trieste

2011-09-15

In this paper we analyze perturbatively a g{phi}{sup 4}classical field theory with and without temperature. In order to do that, we make use of a path-integral approach developed some time ago for classical theories. It turns out that the diagrams appearing at the classical level are many more than at the quantum level due to the presence of extra auxiliary fields in the classical formalism. We shall show that a universal supersymmetry present in the classical path-integral mentioned above is responsible for the cancelation of various diagrams. The same supersymmetry allows the introduction of super-fields and super-diagrams which considerably simplifymore » the calculations and make the classical perturbative calculations almost 'identical' formally to the quantum ones. Using the super-diagrams technique, we develop the classical perturbation theory up to third order. We conclude the paper with a perturbative check of the fluctuation-dissipation theorem. - Highlights: > We provide the Feynman diagrams of perturbation theory for a classical field theory. > We give a super-formalism which links the quantum diagrams to the classical ones. > We check perturbatively the fluctuation-dissipation theorem.« less

Surface Acoustic Wave Study of Exciton Condensation in Bilayer Quantum Hall Systems

NASA Astrophysics Data System (ADS)

Pollanen, J.; Eisenstein, J. P.; Pfeiffer, L. N.; West, K. W.

In bilayer two-dimensional electron systems (2DES) in GaAs a strongly correlated many-electron state forms at low temperature and high magnetic field when the total electron density nT becomes equal to the degeneracy of a single spin split Landau level. This state corresponds to a total filling factor νT = 1 and can be described in terms of pseudospin ferromagnetism, or equivalently, Bose condensation of bilayer excitons. We have simultaneously measured magneto-transport and the propagation of pulsed surface acoustic waves (SAWs) at a frequency of 747 MHz to explore the phase transition between two independent layers at νT = 1 / 2 + 1 / 2 and the correlated state at νT = 1 in a high quality double quantum well device. We tune through this transition by varying the total electron density in our device with front and backside electrostatic gates. We acknowledge funding provided by the Institute for Quantum Information and Matter, an NSF Physics Frontiers Center (NFS Grant PHY-1125565) with support of the Gordon and Betty Moore Foundation (GBMF-12500028).

Calculation of the conductance of two dimensional narrow wires

NASA Astrophysics Data System (ADS)

Kander, Ilan

1989-05-01

There is an interest in the quantum transport of electrons in systems where the sample dimensions are less than a phase coherence length L(sub phi) which is the distance across which the electrons lose phase memory (typically by inelastic scattering). The two-contact conductance is examined of 2-D systems (strips) as functions of Fermi energy system dimensions as is the amount of disorder at zero temperature. Under these conditions all scattering processes are elastic. The term channel is used in order to describe a quantum state with a given transverse quantum number and the appropriate longitudinal momentum. A channel is considered conducting if its longitudinal momentum is real, and decaying if its longitudinal momentum is imaginary. The calculation of the conductance is done in two ways. Transfer matrix for very long systems and Green's function for relatively short ones. The conductance curve in an ordered system is quantized and in a disordered system it is smeared. Interesting changes in the conductance near the thresholds for changes in the quantized value of the conductance are observed.

Tenfold increase in the Rabi decay time of the quantum dot hybrid qubit

NASA Astrophysics Data System (ADS)

Thorgrimsson, Brandur; Kim, Dohun; Simmons, C. B.; Ward, Daniel R.; Foote, Ryan H.; Savage, D. E.; Lagally, M. G.; Friesen, Mark; Coppersmith, S. N.; Eriksson, M. A.

The quantum dot hybrid qubit is formed from three electrons in a double quantum dot. In previous work, we showed that the hybrid qubit has the speed of a charge qubit and the stability of a spin qubit. Here, we show that the hybrid qubit is also highly tunable, and can be tuned into regimes with desirable coherence properties. By changing the interdot tunnel rate by only 25%, from 5 GHz to 6.25 GHz, we are able to increase the Rabi decay time by a factor of ten, from 18 ns to 177 ns. We attribute this improvement to the refinement of an extended ``sweet spot'' in the energy dispersion of the hybrid qubit, where the qubit is less susceptible to charge noise, which is a dominant source of decoherence. This work was supported in part by ARO (W911NF-12-0607) and NSF (DMR-1206915 and PHY-1104660). Development and maintenance of the growth facilities used for fabricating samples is sup- ported by DOE (DE-FG02-03ER46028). This research utilized NSF-supported shared facilities at the University of Wisconsin-Madison.

Primary quantum yields of NO2 photodissociation

NASA Technical Reports Server (NTRS)

Gardner, Edward P.; Sperry, Paul D.; Calvert, Jack G.

1987-01-01

The quantum yields of formation of NO, O2, and NO2 loss are measured for NO2 vapor at low pressures (0.13-0.30 torr) irradiated at 334-405 nm wavelengths and temperature in the range 273-370 K in order to study the primary quantum efficiencies of NO2 photodecomposition. The temperature and wavelength dependences of the primary quantum efficiencies are examined. It is observed that the primary quantum efficiencies increase rapidly from near zero at 424 nm to near unity for excitation at wavelengths less than 394 nm. The theory of Pitts et al. (1964) that the energy deficiency for photodissociation of NO2 excited at wavelengths greater than 397.9 nm is due to the rotational and vibrational energy of the NO2 molecules is confirmed by the data. Values for the primary quantum yields of NO2 photodecomposition as a function of wavelength are presented.

Photosensitized electron transfer processes in SiO2 colloids and sodium lauryl sulfate micellar systems: Correlation of quantum yields with interfacial surface potentials

PubMed Central

Laane, Colja; Willner, Itamar; Otvos, John W.; Calvin, Melvin

1981-01-01

The effectiveness of negatively charged colloidal SiO2 particles in controlling photosensitized electron transfer reactions has been studied and compared with that of the negatively charged sodium lauryl sulfate (NaLauSO4) micellar system. In particular, the photosensitized reduction of the zwitterionic electron acceptor propylviologen sulfonate (PVS0) with tris(2,2′-bipyridinium)ruthenium(II) [Ru(bipy)32+] as the sensitizer and triethanolamine as the electron donor is found to have a quantum yield of 0.033 for formation of the radical anion (PVS[unk]) in the SiO2 colloid compared with 0.005 in the homogeneous system and 0.0086 in a NaLauSO4 micellar solution. The higher quantum yields obtained with the SiO2 colloidal system are attributed to substantial stabilization against back reaction of the intermediate photoproducts—i.e., Ru(bipy)33+ and PVS[unk]—by electrostatic repulsion of the reduced electron acceptor from the negatively charged particle surface. The binding properties of the SiO2 particles and NaLauSO4 micelles were investigated by flow dialysis. The results show that the sensitizer binds to both interfaces and that the SiO2 interface is characterized by a much higher surface potential than the micellar interface (≈-170 mV vs. -85 mV). The effect of ionic strength on the surface potential was estimated from the Gouy-Chapman theory, and the measured quantum yields of photosensitized electron transfer were correlated with surface potential at different ionic strengths. This correlation shows that the quantum yield is not affected by surface potentials smaller than ≈-40 mV. At larger potentials, the quantum yield increases rapidly. The quantum yield obtained in the micellar system at different strengths fits nicely on the correlation curve for the colloid SiO2 system. These results indicate that the surface potential is the dominant factor in the quantum yield improvement for PVS0 reduction. PMID:16593095

Percolation bounds for decoding thresholds with correlated erasures in quantum LDPC codes

NASA Astrophysics Data System (ADS)

Hamilton, Kathleen; Pryadko, Leonid

Correlations between errors can dramatically affect decoding thresholds, in some cases eliminating the threshold altogether. We analyze the existence of a threshold for quantum low-density parity-check (LDPC) codes in the case of correlated erasures. When erasures are positively correlated, the corresponding multi-variate Bernoulli distribution can be modeled in terms of cluster errors, where qubits in clusters of various size can be marked all at once. In a code family with distance scaling as a power law of the code length, erasures can be always corrected below percolation on a qubit adjacency graph associated with the code. We bound this correlated percolation transition by weighted (uncorrelated) percolation on a specially constructed cluster connectivity graph, and apply our recent results to construct several bounds for the latter. This research was supported in part by the NSF Grant PHY-1416578 and by the ARO Grant W911NF-14-1-0272.

The development of two postnatal health instruments: one for mothers (M-PHI) and one for fathers (F-PHI) to measure health during the first year of parenting.

PubMed

Jones, G L; Morrell, C J; Cooke, J M; Speier, D; Anumba, D; Stewart-Brown, S

2011-09-01

To develop and psychometrically evaluate two questionnaires measuring both positive and negative postnatal health of mothers (M-PHI) and fathers (F-PHI) during the first year of parenting. The M-PHI and the F-PHI were developed in four stages. Stage 1: Postnatal women's focus group (M-PHI) and postnatal fathers' postal questionnaire (F-PHI); Stage 2: Qualitative interviews; Stage 3: Pilot postal survey and main postal survey; and Stage 4: Test-retest postal survey. The M-PHI consisted of a 29-item core questionnaire with six main scales and five conditional scales. The F-PHI consisted of a 27-item questionnaire with six main scales. All scales achieved good internal reliability (Cronbach's α 0.66-0.87 for M-PHI, 0.72-0.90 for F-PHI). Intraclass correlation coefficients demonstrated high test-retest reliability (0.60-0.88). Correlation coefficients supported the criterion validity of the M-PHI and the F-PHI when tested against the Short-Form-12 (SF-12), Edinburgh Postnatal Depression Scale (EPDS) and the Warwick and Edinburgh Mental Well-Being Scale (WEMWBS). The M-PHI and F-PHI are valid, reliable, parent-generated instruments. These unique instruments will be invaluable for practitioners wishing to promote family-centred care and for trialists and other researchers requiring a validated instrument to measure both positive and negative health during the first postnatal year, as to date no such measurement has existed.

PKS1 plays a role in red-light-based positive phototropism in roots.

PubMed

Molas, Maria Lia; Kiss, John Z

2008-06-01

Aerial parts of plants curve towards the light (i.e. positive phototropism), and roots typically grow away from the light (i.e. negative phototropism). In addition, Arabidopsis roots exhibit positive phototropism relative to red light (RL), and this response is mediated by phytochromes A and B (phyA and phyB). Upon light stimulation, phyA and phyB interact with the phytochrome kinase substrate (PKS1) in the cytoplasm. In this study, we investigated the role of PKS1, along with phyA and phyB, in the positive phototropic responses to RL in roots. Using a high-resolution feedback system, we studied the phenotypic responses of roots of phyA, phyB, pks1, phyA pks1 and phyB pks1 null mutants as well as the PKS1-overexpressing line in response to RL. PKS1 emerged as an intermediary in the signalling pathways and appears to promote a negative curvature to RL in roots. In addition, phyA and phyB were both essential for a positive response to RL and act in a complementary fashion. However, either photoreceptor acting without the other results in negative curvature in response to red illumination so that the mode of action differs depending on whether phyA and phyB act independently or together. Our results suggest that PKS1 is part of a signalling pathway independent of phyA and phyB and that PKS1 modulates RL-based root phototropism.

Electro Optical Properties of Copolymer Blends: Lasing, Electroluminescence and Photophysics

DTIC Science & Technology

2006-04-15

conjugated main chain structures with high photoluminescent and electroluminescent quantum yields. The structures incorporated fluorene containing moieties...The systems studied focused on novel conjugated main chain structures with high photoluminescent and electroluminescent quantum yields. The structures...the quantum efficient fluorine group. The properties of segmented copolymers that incorporate fluorenes were compared to the homo-PPV type systems

A versatile method for the determination of photochemical quantum yields via online UV-Vis spectroscopy.

PubMed

Stadler, Eduard; Eibel, Anna; Fast, David; Freißmuth, Hilde; Holly, Christian; Wiech, Mathias; Moszner, Norbert; Gescheidt, Georg

2018-05-16

We have developed a simple method for determining the quantum yields of photo-induced reactions. Our setup features a fibre coupled UV-Vis spectrometer, LED irradiation sources, and a calibrated spectrophotometer for precise measurements of the LED photon flux. The initial slope in time-resolved absorbance profiles provides the quantum yield. We show the feasibility of our methodology for the kinetic analysis of photochemical reactions and quantum yield determination. The typical chemical actinometers, ferrioxalate and ortho-nitrobenzaldehyde, as well as riboflavin, a spiro-compound, phosphorus- and germanium-based photoinitiators for radical polymerizations and the frequently utilized photo-switch azobenzene serve as paradigms. The excellent agreement of our results with published data demonstrates the high potential of the proposed method as a convenient alternative to the time-consuming chemical actinometry.

Fluorescence quantum yield measurements of fluorescent proteins: a laboratory experiment for a biochemistry or molecular biophysics laboratory course.

PubMed

Wall, Kathryn P; Dillon, Rebecca; Knowles, Michelle K

2015-01-01

Fluorescent proteins are commonly used in cell biology to assess where proteins are within a cell as a function of time and provide insight into intracellular protein function. However, the usefulness of a fluorescent protein depends directly on the quantum yield. The quantum yield relates the efficiency at which a fluorescent molecule converts absorbed photons into emitted photons and it is necessary to know for assessing what fluorescent protein is the most appropriate for a particular application. In this work, we have designed an upper-level, biochemistry laboratory experiment where students measure the fluorescence quantum yields of fluorescent proteins relative to a standard organic dye. Four fluorescent protein variants, enhanced cyan fluorescent protein (ECFP), enhanced green fluorescent protein (EGFP), mCitrine, and mCherry, were used, however the methods described are useful for the characterization of any fluorescent protein or could be expanded to fluorescent quantum yield measurements of organic dye molecules. The laboratory is designed as a guided inquiry project and takes two, 4 hr laboratory periods. During the first day students design the experiment by selecting the excitation wavelength, choosing the standard, and determining the concentration needed for the quantum yield experiment that takes place in the second laboratory period. Overall, this laboratory provides students with a guided inquiry learning experience and introduces concepts of fluorescence biophysics into a biochemistry laboratory curriculum. © 2014 The International Union of Biochemistry and Molecular Biology.

Photochemical redox reactions of copper(II)-alanine complexes in aqueous solutions.

PubMed

Lin, Chen-Jui; Hsu, Chao-Sheng; Wang, Po-Yen; Lin, Yi-Liang; Lo, Yu-Shiu; Wu, Chien-Hou

2014-05-19

The photochemical redox reactions of Cu(II)/alanine complexes have been studied in deaerated solutions over an extensive range of pH, Cu(II) concentration, and alanine concentration. Under irradiation, the ligand-to-metal charge transfer results in the reduction of Cu(II) to Cu(I) and the concomitant oxidation of alanine, which produces ammonia and acetaldehyde. Molar absorptivities and quantum yields of photoproducts for Cu(II)/alanine complexes at 313 nm are characterized mainly with the equilibrium Cu(II) speciation where the presence of simultaneously existing Cu(II) species is taken into account. By applying regression analysis, individual Cu(I) quantum yields are determined to be 0.094 ± 0.014 for the 1:1 complex (CuL) and 0.064 ± 0.012 for the 1:2 complex (CuL2). Individual quantum yields of ammonia are 0.055 ± 0.007 for CuL and 0.036 ± 0.005 for CuL2. Individual quantum yields of acetaldehyde are 0.030 ± 0.007 for CuL and 0.024 ± 0.007 for CuL2. CuL always has larger quantum yields than CuL2, which can be attributed to the Cu(II) stabilizing effect of the second ligand. For both CuL and CuL2, the individual quantum yields of Cu(I), ammonia, and acetaldehyde are in the ratio of 1.8:1:0.7. A reaction mechanism for the formation of the observed photoproducts is proposed.

A method of self-pursued boundary value on a body and the Magnus effect calculated with this method

NASA Astrophysics Data System (ADS)

Yoshino, Fumio; Hayashi, Tatsuo; Waka, Ryoji

1991-03-01

A computational method, designated 'SPB', is proposed for the automatic determination of the stream function Phi on an arbitrarily profiled body without recourse to empirical factors. The method is applied to the case of a rotating, circular cross-section cylinder in a uniform shear flow, and the results obtained are compared with those of both the method in which the value of Phi is fixed on a body and the conventional empirical method; it is in view of this established that the SPB method is very efficient and applicable to both steady and unsteady flows. The SPB method, in addition to yielding the aerodynamic forces acting on a cylinder, shows that the Magnus effect lift force decreases as the velocity gradient of the shear flow increases while the cylinder's rotational speed is kept constant.

Observation of the Y (4140) structure in the J/ψΦ mass spectrum in B±→ J/ψΦK ± decays

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

Aaltonen, T.; González, B. Álvarez; Amerio, S.

Here, the observation of themore » $Y(4140)$ structure in $$B^\\pm\\rightarrow J/\\psi\\,\\phi K^\\pm$$ decays produced in $$\\bar{p} p $$ collisions at $$\\sqrt{s}=1.96~TeV$$ is reported with a statistical significance greater than 5 standard deviations. A fit to the $$J/\\psi\\,\\phi$$ mass spectrum is performed assuming the presence of a Breit-Wigner resonance. The fit yields a signal of $$19^{+6}_{-5}$$ resonance events, and resonance mass and width of $$4143.4^{+2.9}_{-3.0}(\\mathrm{stat})\\pm0.6(\\mathrm{syst}) ~MeVcc$$ and $$15.3^{+10.4}_{-6.1}(\\mathrm{stat})\\pm2.5(\\mathrm{syst})~MeVcc$$ respectively. The parameters of this resonance-like structure are consistent with values reported from an earlier CDF analysis.« less

Observation of the Y (4140) structure in the J/ψΦ mass spectrum in B±→ J/ψΦK ± decays

DOE PAGES

Aaltonen, T.; González, B. Álvarez; Amerio, S.; ...

2017-07-27

Here, the observation of themore » $Y(4140)$ structure in $$B^\\pm\\rightarrow J/\\psi\\,\\phi K^\\pm$$ decays produced in $$\\bar{p} p $$ collisions at $$\\sqrt{s}=1.96~TeV$$ is reported with a statistical significance greater than 5 standard deviations. A fit to the $$J/\\psi\\,\\phi$$ mass spectrum is performed assuming the presence of a Breit-Wigner resonance. The fit yields a signal of $$19^{+6}_{-5}$$ resonance events, and resonance mass and width of $$4143.4^{+2.9}_{-3.0}(\\mathrm{stat})\\pm0.6(\\mathrm{syst}) ~MeVcc$$ and $$15.3^{+10.4}_{-6.1}(\\mathrm{stat})\\pm2.5(\\mathrm{syst})~MeVcc$$ respectively. The parameters of this resonance-like structure are consistent with values reported from an earlier CDF analysis.« less

Modern Physics Simulations

NASA Astrophysics Data System (ADS)

Brandt, Douglas; Hiller, John R.; Moloney, Michael J.

1995-10-01

The Consortium for Upper Level Physics Software (CUPS) has developed a comprehensive series of Nine Book/Software packages that Wiley will publish in FY `95 and `96. CUPS is an international group of 27 physicists, all with extensive backgrounds in the research, teaching, and development of instructional software. The project is being supported by the National Science Foundation (PHY-9014548), and it has received other support from the IBM Corp., Apple Computer Corp., and George Mason University. The Simulations being developed are: Astrophysics, Classical Mechanics, Electricity & Magnetism, Modern Physics, Nuclear and Particle Physics, Quantum Mechanics, Solid State, Thermal and Statistical, and Wave and Optics.

General dynamical properties of cosmological models with nonminimal kinetic coupling

NASA Astrophysics Data System (ADS)

Matsumoto, Jiro; Sushkov, Sergey V.

2018-01-01

We consider cosmological dynamics in the theory of gravity with the scalar field possessing the nonminimal kinetic coupling to curvature given as η Gμνphi,μphi,ν, where η is an arbitrary coupling parameter, and the scalar potential V(phi) which assumed to be as general as possible. With an appropriate dimensionless parametrization we represent the field equations as an autonomous dynamical system which contains ultimately only one arbitrary function χ (x)= 8 π | η | V(x/√8 π) with x=√8 πphi. Then, assuming the rather general properties of χ(x), we analyze stationary points and their stability, as well as all possible asymptotical regimes of the dynamical system. It has been shown that for a broad class of χ(x) there exist attractors representing three accelerated regimes of the Universe evolution, including de Sitter expansion (or late-time inflation), the Little Rip scenario, and the Big Rip scenario. As the specific examples, we consider a power-law potential V(phi)=M4(phi/phi0)σ, Higgs-like potential V(phi)=λ/4(phi2‑phi02)2, and exponential potential V(phi)=M4 e‑phi/phi0.

Active experiments in modifying spacecraft potential: Results from ATS-5 and ATS-6

NASA Technical Reports Server (NTRS)

Olsen, R. C.; Whipple, E. C.

1979-01-01

The processing of data from onboard spacecraft instruments are described. The modification of spacecraft potentials is reviewed. Analysis of this data yielded the following results: (1) electron emission (E approximately 10 electron-volts) did not perturb the status of a satellite at low potential the absolute value of phi approximately 50 volts by more than 50 volts (the ATS 5 low energy limit), (2) emission of a low energy plasma (E approximatey 10 volts) does not change low potentials (the absolute value of phi approximately 5 volts) by more than a few volts (ATS 6 low energy resolution), (3) when ATS 6 entered eclipse in the presence of a high energy plasma (10 keV), the neutralizer suppressed any rise in the absolute value of phi (within a few volts resolution), (4) when the electron emitter on ATS 5 operated, it served to discharge negative potentials from thousands to hundreds of volts, and (5) when the neutralizer on ATS 6 was operated, it served to discharge kilovolt potentials to below 50 volts. Low altitude (100 - 300 km) experiments with KV electron beams are studied. Differential charging was eliminated by the operation of the main thruster on ATS 6 clamped on the spacecraft at -5 volts.

Lysine 206 in Arabidopsis phytochrome A is the major site for ubiquitin-dependent protein degradation.

PubMed

Rattanapisit, Kaewta; Cho, Man-Ho; Bhoo, Seong Hee

2016-02-01

Phytochrome A (phyA) is a light labile phytochrome that mediates plant development under red/far-red light condition. Degradation of phyA is initiated by red light-induced phyA-ubiquitin conjugation through the 26S proteasome pathway. The N-terminal of phyA is known to be important in phyA degradation. To determine the specific lysine residues in the N-terminal domain of phyA involved in light-induced ubiquitination and protein degradation, we aligned the amino acid sequence of the N-terminal domain of Arabidopsis phyA with those of phyA from other plant species. Based on the alignment results, phytochrome over-expressing Arabidopsis plants were generated. In particular, wild-type and mutant (substitutions of conserved lysines by arginines) phytochromes fused with GFP were expressed in phyA(-)211 Arabidopsis plants. Degradation kinetics of over-expressed phyA proteins revealed that degradation of the K206R phyA mutant protein was delayed. Delayed phyA degradation of the K206R phyA mutant protein resulted in reduction of red-light-induced phyA-ubiquitin conjugation. Furthermore, seedlings expressing the K206R phyA mutant protein showed an enhanced phyA response under far-red light, resulting in inhibition of hypocotyl elongation as well as cotyledon opening. Together, these results suggest that lysine 206 is the main lysine for rapid ubiquitination and protein degradation of Arabidopsis phytochrome A. © The Authors 2015. Published by Oxford University Press on behalf of the Japanese Biochemical Society. All rights reserved.

Polariton-Assisted Singlet Fission in Acene Aggregates.

PubMed

Martínez-Martínez, Luis A; Du, Matthew; F Ribeiro, Raphael; Kéna-Cohen, Stéphane; Yuen-Zhou, Joel

2018-04-19

Singlet fission is an important candidate to increase energy conversion efficiency in organic photovoltaics by providing a pathway to increase the quantum yield of excitons per photon absorbed in select materials. We investigate the dependence of exciton quantum yield for acenes in the strong light-matter interaction (polariton) regime, where the materials are embedded in optical microcavities. Starting from an open-quantum-systems approach, we build a kinetic model for time-evolution of species of interest in the presence of singlet quenchers and show that polaritons can decrease or increase exciton quantum yields compared to the cavity-free case. In particular, we find that hexacene, under the conditions of our model, can feature a higher yield than cavity-free pentacene when assisted by polaritonic effects. Similarly, we show that pentacene yield can be increased when assisted by polariton states. Finally, we address how various relaxation processes between bright and dark states in lossy microcavities affect polariton photochemistry. Our results also provide insights on how to choose microcavities to enhance similarly related chemical processes.

Light propagation and fluorescence quantum yields in liquid scintillators

NASA Astrophysics Data System (ADS)

Buck, C.; Gramlich, B.; Wagner, S.

2015-09-01

For the simulation of the scintillation and Cherenkov light propagation in large liquid scintillator detectors a detailed knowledge about the absorption and emission spectra of the scintillator molecules is mandatory. Furthermore reemission probabilities and quantum yields of the scintillator components influence the light propagation inside the liquid. Absorption and emission properties are presented for liquid scintillators using 2,5-Diphenyloxazole (PPO) and 4-bis-(2-Methylstyryl)benzene (bis-MSB) as primary and secondary wavelength shifter. New measurements of the quantum yields for various aromatic molecules are shown.

Bacteriophage phi11 lysin: physicochemical characterization and comparison with phage phi80a lysin

USDA-ARS?s Scientific Manuscript database

Phage lytic enzymes are promising antimicrobial agents. Lysins of phage phi11 (LysPhi11) and phi80a (LysPhi80a) can lyse (destroy) biofilms and cells of antibiotic-resistant strains of Staphylococcus aureus. Stability of enzymes is one of the parameters making their practical use possible. The obj...

Quantum mechanics: The Bayesian theory generalized to the space of Hermitian matrices

NASA Astrophysics Data System (ADS)

Benavoli, Alessio; Facchini, Alessandro; Zaffalon, Marco

2016-10-01

We consider the problem of gambling on a quantum experiment and enforce rational behavior by a few rules. These rules yield, in the classical case, the Bayesian theory of probability via duality theorems. In our quantum setting, they yield the Bayesian theory generalized to the space of Hermitian matrices. This very theory is quantum mechanics: in fact, we derive all its four postulates from the generalized Bayesian theory. This implies that quantum mechanics is self-consistent. It also leads us to reinterpret the main operations in quantum mechanics as probability rules: Bayes' rule (measurement), marginalization (partial tracing), independence (tensor product). To say it with a slogan, we obtain that quantum mechanics is the Bayesian theory in the complex numbers.

Intermediate quantum maps for quantum computation

NASA Astrophysics Data System (ADS)

Giraud, O.; Georgeot, B.

2005-10-01

We study quantum maps displaying spectral statistics intermediate between Poisson and Wigner-Dyson. It is shown that they can be simulated on a quantum computer with a small number of gates, and efficiently yield information about fidelity decay or spectral statistics. We study their matrix elements and entanglement production and show that they converge with time to distributions which differ from random matrix predictions. A randomized version of these maps can be implemented even more economically and yields pseudorandom operators with original properties, enabling, for example, one to produce fractal random vectors. These algorithms are within reach of present-day quantum computers.

Arabidopsis fhl/fhy1 double mutant reveals a distinct cytoplasmic action of phytochrome A

PubMed Central

Rösler, Jutta; Klein, Ilse; Zeidler, Mathias

2007-01-01

Phytochrome A (phyA) plays an important role during germination and early seedling development. Because phyA is the primary photoreceptor for the high-irradiance response and the very-low-fluence response, it can trigger development not only in red and far-red (FR) light but also in a wider range of light qualities. Although phyA action is generally associated with translocation to the nucleus and regulation of transcription, there is evidence for additional cytoplasmic functions. Because nuclear accumulation of phyA has been shown to depend on far-red-elongated hypocotyl 1 (FHY1) and FHL (FHY1-like), investigation of phyA function in a double fhl/fhy1 mutant might be valuable in revealing the mechanism of phyA translocation and possible cytoplasmic functions. In fhl/fhy1, the FR-triggered nuclear translocation of phyA could no longer be detected but could be restored by transgenic expression of CFP:FHY1. Whereas the fhl/fhy1 mutant showed a phyA phenotype in respect to hypocotyl elongation and cotyledon opening under high-irradiance response conditions as well as a typical phyA germination phenotype under very-low-fluence response conditions, fhl/fhy1 showed no phenotype with respect to the phyA-dependent abrogation of negative gravitropism in blue light and in red-enhanced phototropism, demonstrating clear cytoplasmic functions of phyA. Disturbance of phyA nuclear import in fhl/fhy1 led to formation of FR-induced phyA:GFP cytoplasmic foci resembling the sequestered areas of phytochrome. FHY1 and FHL play crucial roles in phyA nuclear translocation and signaling. Thus the double-mutant fhl/fhy1 allows nuclear and cytoplasmic phyA functions to be separated, leading to the novel identification of cytoplasmic phyA responses. PMID:17566111

Interactions of phytochromes A, B1 and B2 in light-induced competence for adventitious shoot formation in hypocotyl of tomato (Solanum lycopersicum L.).

PubMed

Lercari, B; Bertram, L

2004-02-01

The interactions of phytochrome A (phyA), phytochrome B1 (phyB1) and phytochrome B2 (phyB2) in light-dependent shoot regeneration from the hypocotyl of tomato was analysed using all eight possible homozygous allelic combinations of the null mutants. The donor plants were pre-grown either in the dark or under red or far-red light for 8 days after sowing; thereafter hypocotyl segments (apical, middle and basal portions) were transferred onto hormone-free medium for culture under different light qualities. Etiolated apical segments cultured in vitro under white light showed a very high frequency of regeneration for all of the genotypes tested besides phyB1phyB2, phyAphyB1 and phyAphyB1phyB2 mutants. Evidence is provided of a specific interference of phyB2 with phyA-mediated HIR to far-red and blue light in etiolated explants. Pre-treatment of donor plants by growth under red light enhanced the competence of phyB1phyB2, phyAphyB1 and phyAphyB1phyB2 mutants for shoot regeneration, whereas pre-irradiation with far-red light enhanced the frequency of regeneration only in the phyAphyB1 mutant. Multiple phytochromes are involved in red light- and far-red light-dependent acquisition of competence for shoot regeneration. The position of the segments along the hypocotyl influenced the role of the various phytochromes and the interactions between them. The culture of competent hypocotyl segments under red, far-red or blue light reduced the frequency of explants forming shoots compared to those cultured under white light, with different genotypes having different response patterns.

Canonical single field slow-roll inflation with a non-monotonic tensor-to-scalar ratio

NASA Astrophysics Data System (ADS)

Germán, Gabriel; Herrera-Aguilar, Alfredo; Hidalgo, Juan Carlos; Sussman, Roberto A.

2016-05-01

We take a pragmatic, model independent approach to single field slow-roll canonical inflation by imposing conditions, not on the potential, but on the slow-roll parameter epsilon(phi) and its derivatives epsilon'(phi) and epsilon''(phi), thereby extracting general conditions on the tensor-to-scalar ratio r and the running nsk at phiH where the perturbations are produced, some 50-60 e-folds before the end of inflation. We find quite generally that for models where epsilon(phi) develops a maximum, a relatively large r is most likely accompanied by a positive running while a negligible tensor-to-scalar ratio implies negative running. The definitive answer, however, is given in terms of the slow-roll parameter ξ2(phi). To accommodate a large tensor-to-scalar ratio that meets the limiting values allowed by the Planck data, we study a non-monotonic epsilon(phi) decreasing during most part of inflation. Since at phiH the slow-roll parameter epsilon(phi) is increasing, we thus require that epsilon(phi) develops a maximum for phi > phiH after which epsilon(phi) decrease to small values where most e-folds are produced. The end of inflation might occur trough a hybrid mechanism and a small field excursion Δphie ≡ |phiH-phie| is obtained with a sufficiently thin profile for epsilon(phi) which, however, should not conflict with the second slow-roll parameter η(phi). As a consequence of this analysis we find bounds for Δphie, rH and for the scalar spectral index nsH. Finally we provide examples where these considerations are explicitly realised.

Quantum Yields of CAM Plants Measured by Photosynthetic O2 Exchange 1

PubMed Central

Adams, William W.; Nishida, Kojiro; Osmond, C. Barry

1986-01-01

The quantum yield of photosynthetic O2 exchange was measured in eight species of leaf succulents representative of both malic enzyme type and phosphoenolpyruvate carboxykinase type CAM plants. Measurements were made at 25°C and CO2 saturation using a leaf disc O2 electrode system, either during or after deacidification. The mean quantum yield was 0.095 ± 0.012 (sd) moles O2 per mole quanta, which compared with 0.094 ± 0.006 (sd) moles O2 per mole quanta for spinach leaf discs measured under the same conditions. There were no consistent differences in quantum yield between decarboxylation types or during different phases of CAM metabolism. On the basis of current notions of compartmentation of CAM biochemistry, our observations are interpreted to indicate that CO2 refixation is energetically independent of gluconeogenesis during deacidification. PMID:16664793

Incentive Spirometry after Lung Resection: A Randomized Controlled Trial.

PubMed

Malik, Peter Ra; Fahim, Christine; Vernon, Jordyn; Thomas, Priya; Schieman, Colin; Finley, Christian J; Agzarian, John; Shargall, Yaron; Farrokhyar, Forough; Hanna, Wael C

2018-04-24

Incentive spirometry (IS) is thought to reduce the incidence of postoperative pulmonary complications (PPC) after lung resection. We sought to determine whether the addition of IS to routine physiotherapy following lung resection results in a lower rate of PPC, as compared to physiotherapy alone. A single-blind prospective randomized controlled trial was conducted in adults undergoing lung resection. Individuals with previous lung surgery or home oxygen were excluded. Participants randomized to the control arm (PHY) received routine physiotherapy alone (deep breathing, ambulation and shoulder exercises). Those randomized to the intervention arm (PHY/IS) received IS in addition to routine physiotherapy. The trial was powered to detect a 10% difference in the rate of PPC (beta=80%). Student's t-test and chi-square were utilized for continuous and categorical variables respectively, with a significance level of p=0.05. A total of 387 participants (n=195 PHY/IS; n=192 PHY) were randomized between 2014-2017. Baseline characteristics were comparable for both arms. The majority of patients underwent a pulmonary lobectomy (PHY/IS=59.5%, PHY=61.0%, p=0.84), with no difference in the rates of minimally invasive and open procedures. There were no differences in the incidence of PPC at 30 days postoperatively (PHY/IS=12.3%, PHY=13.0%, p=0.88). There were no differences in rates of pneumonia (PHY/IS=4.6%, PHY=7.8%, p=0.21), mechanical ventilation (PHY/IS=2.1%, PHY=1.0%, p=0.41), home-oxygen (PHY/IS=13.8%, PHY=14.6%, p=0.89), hospital length of stay (PHY/IS=4 days, PHY=4 days, p=0.34), or rate of readmission to hospital (PHY/IS=10.3%, PH=9.9%, p=1.00). The addition of IS to routine postoperative physiotherapy does not reduce the incidence of PPC after lung resection. Copyright © 2018. Published by Elsevier Inc.

Purification and characterization of two distinct acidic phytases with broad pH stability from Aspergillus niger NCIM 563.

PubMed

Soni, S K; Magdum, A; Khire, J M

2010-11-01

Aspergillus niger NCIM 563 produced two different extracellular phytases (Phy I and Phy II) under submerged fermentation conditions at 30°C in medium containing dextrin-glucose-sodium nitrate-salts. Both the enzymes were purified to homogeneity using Rotavapor concentration, Phenyl-Sepharose column chromatography and Sephacryl S-200 gel filtration. The molecular mass of Phy I and II as determined by SDS-PAGE and gel filtration were 66, 264, 150 and 148 kDa respectively, indicating that Phy I consists of four identical subunits and Phy II is a monomer. The pI values of Phy I and II were 3.55 and 3.91, respectively. Phy I was highly acidic with optimum pH of 2.5 and was stable over a broad pH range (1.5-9.0) while Phy II showed a pH optimum of 5.0 with stability in the range of pH 3.5-9.0. Phy I exhibited very broad substrate specificity while Phy II was more specific for sodium phytate. Similarly Phy II was strongly inhibited by Ag(+), Hg(2+) (1 mM) metal ions and Phy I was partially inhibited. Peptide analysis by Mass Spectrometry (MS) MALDI-TOF also indicated that both the proteins were totally different. The K(m) for Phy I and II for sodium phytate was 2.01 and 0.145 mM while V(max) was 5,018 and 1,671 μmol min(-1) mg(-1), respectively. The N-terminal amino acid sequences of Phy I and Phy II were FSYGAAIPQQ and GVDERFPYTG, respectively. Phy II showed no homology with Phy I and any other known phytases from the literature suggesting its unique nature. This, according to us, is the first report of two distinct novel phytases from Aspergillus niger.

Phytochrome B Requires PIF Degradation and Sequestration to Induce Light Responses Across a Wide Range of Light Conditions.

PubMed

Park, Eunae; Kim, Yeojae; Choi, Giltsu

2018-05-15

Phytochrome B (phyB) inhibits the function of phytochrome-interacting factors (PIFs) by inducing their degradation and sequestration, but the relative physiological importance of these two phyB activities is unclear. In an analysis of published Arabidopsis thaliana phyB mutations, we identified a point mutation in the N-terminal half of phyB (phyBG111D) that abolishes its PIF sequestration activity without affecting its PIF degradation activity. We also identified a point mutation in the phyB C-terminal domain, which, when combined with a deletion of the C-terminal end (phyB990G767R), does the opposite; it blocks PIF degradation without affecting PIF sequestration. The resulting phyB proteins, phyB990G767R and phyBG111D, are equally capable of inducing light responses under continuous red light. However, phyBG111D, which exhibits only the PIF degradation activity, induces stronger light responses than phyB990G767R under white light with prolonged dark periods (i.e., diurnal cycles). In contrast, phyB990G767R, which exhibits only the PIF sequestration activity, induces stronger light responses in flickering light (a condition that mimics sunflecks). Together, our results indicate that both of these separable phyB activities are required for light responses in varying light conditions. © 2018 American Society of Plant Biologists. All rights reserved.

Poly(vinylpyrrolidone) supported copper nanoclusters: glutathione enhanced blue photoluminescence for application in phosphor converted light emitting devices

NASA Astrophysics Data System (ADS)

Wang, Zhenguang; Susha, Andrei S.; Chen, Bingkun; Reckmeier, Claas; Tomanec, Ondrej; Zboril, Radek; Zhong, Haizheng; Rogach, Andrey L.

2016-03-01

Poly(vinylpyrrolidone) supported Cu nanoclusters were synthesized by reduction of Cu(ii) ions with ascorbic acid in water, and initially showed blue photoluminescence with a quantum yield of 8%. An enhancement of the emission quantum yield has been achieved by treatment of Cu clusters with different electron-rich ligands, with the most pronounced effect (photoluminescence quantum yield of 27%) achieved with glutathione. The bright blue emission of glutathione treated Cu NCs is fully preserved in the solid state powder, which has been combined with commercial green and red phosphors to fabricate down-conversion white light emitting diodes with a high colour rendering index of 92.Poly(vinylpyrrolidone) supported Cu nanoclusters were synthesized by reduction of Cu(ii) ions with ascorbic acid in water, and initially showed blue photoluminescence with a quantum yield of 8%. An enhancement of the emission quantum yield has been achieved by treatment of Cu clusters with different electron-rich ligands, with the most pronounced effect (photoluminescence quantum yield of 27%) achieved with glutathione. The bright blue emission of glutathione treated Cu NCs is fully preserved in the solid state powder, which has been combined with commercial green and red phosphors to fabricate down-conversion white light emitting diodes with a high colour rendering index of 92. Electronic supplementary information (ESI) available: The optical spectra of control experiments for Cu NC synthesis, optimization of the reaction conditions, and spectra for LEDs chips and blue LEDs. See DOI: 10.1039/c6nr00806b

Acid-base and ion balance in fishes with bimodal respiration.

PubMed

Shartau, R B; Brauner, C J

2014-03-01

The evolution of air breathing during the Devonian provided early fishes with bimodal respiration with a stable O2 supply from air. This was, however, probably associated with challenges and trade-offs in terms of acid-base balance and ionoregulation due to reduced gill:water interaction and changes in gill morphology associated with air breathing. While many aspects of acid-base and ionoregulation in air-breathing fishes are similar to water breathers, the specific cellular and molecular mechanisms involved remain largely unstudied. In general, reduced ionic permeability appears to be an important adaptation in the few bimodal fishes investigated but it is not known if this is a general characteristic. The kidney appears to play an important role in minimizing ion loss to the freshwater environment in the few species investigated, and while ion uptake across the gut is probably important, it has been largely unexplored. In general, air breathing in facultative air-breathing fishes is associated with an acid-base disturbance, resulting in an increased partial pressure of arterial CO2 and a reduction in extracellular pH (pHE ); however, several fishes appear to be capable of tightly regulating tissue intracellular pH (pHI ), despite a large sustained reduction in pHE , a trait termed preferential pHI regulation. Further studies are needed to determine whether preferential pHI regulation is a general trait among bimodal fishes and if this confers reduced sensitivity to acid-base disturbances, including those induced by hypercarbia, exhaustive exercise and hypoxia or anoxia. Additionally, elucidating the cellular and molecular mechanisms may yield insight into whether preferential pHI regulation is a trait ultimately associated with the early evolution of air breathing in vertebrates. © 2014 The Fisheries Society of the British Isles.

Single-particle tracking of quantum dot-conjugated prion proteins inside yeast cells

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

Tsuji, Toshikazu; Kawai-Noma, Shigeko; Pack, Chan-Gi

2011-02-25

Research highlights: {yields} We develop a method to track a quantum dot-conjugated protein in yeast cells. {yields} We incorporate the conjugated quantum dot proteins into yeast spheroplasts. {yields} We track the motions by conventional or 3D tracking microscopy. -- Abstract: Yeast is a model eukaryote with a variety of biological resources. Here we developed a method to track a quantum dot (QD)-conjugated protein in the budding yeast Saccharomyces cerevisiae. We chemically conjugated QDs with the yeast prion Sup35, incorporated them into yeast spheroplasts, and tracked the motions by conventional two-dimensional or three-dimensional tracking microscopy. The method paves the way towardmore » the individual tracking of proteins of interest inside living yeast cells.« less

The differential production cross section of the $$\\phi $$ (1020) meson in $$\\sqrt{s}$$ TeV $pp$ collisions measured with the ATLAS detector

DOE PAGES

Aad, G.; Abajyan, T.; Abbott, B.; ...

2014-07-01

Ameasurement is presented of themore » $$\\phi $$×BR($$\\phi $$ →K < sup > + < /sup > K < sup > - < /sup > ) production cross section at √s = 7 TeV using pp collision data corresponding to an integrated luminosity of 383 μb -1, collected with the ATLAS experiment at the HC. Selection of $$\\phi $$(1020) mesons is based on the identification of charged kaons by their energy loss in the pixel detector. The differential cross section ismeasured as a function of the transverse momentum, pT,$$\\phi $$ , and rapidity, y$$\\phi $$, of the $$\\phi $$(1020) meson in the fiducial region 500 < pT,$$\\phi $$ < 1200MeV, |y$$\\phi $$ | < 0.8, kaon p T,K > 230 MeV and kaon momentum p K < 800 MeV. The integrated $$\\phi $$(1020)-meson production cross section in this fiducial range is measured to be sφ×BR($$\\phi $$ →K < sup > + < /sup > K < sup > - < /sup > ) = 570 ± 8 (stat) ± 66 (syst) ± 20 (lumi) μb.« less

Quenching mechanism of Zn(salicylaldimine) by nitroaromatics.

PubMed

Germain, Meaghan E; Vargo, Thomas R; McClure, Beth Anne; Rack, Jeffrey J; Van Patten, P Gregory; Odoi, Michael; Knapp, Michael J

2008-07-21

Nitroaromatics and nitroalkanes quench the fluorescence of Zn(Salophen) (H2Salophen = N,N'-phenylene-bis-(3,5-di- tert-butylsalicylideneimine); ZnL(R)) complexes. A structurally related family of ZnL(R) complexes (R = OMe, di-tBu, tBu, Cl, NO2) were prepared, and the mechanisms of fluorescence quenching by nitroaromatics were studied by a combined kinetics and spectroscopic approach. The fluorescent quantum yields for ZnL(R) were generally high (Phi approximately 0.3) with sub-nanosecond fluorescence lifetimes. The fluorescence of ZnL(R) was quenched by nitroaromatic compounds by a mixture of static and dynamic pathways, reflecting the ZnL(R) ligand bulk and reduction potential. Steady-state Stern-Volmer plots were curved for ZnL(R) with less-bulky substituents (R = OMe, NO2), suggesting that both static and dynamic pathways were important for quenching. Transient Stern-Volmer data indicated that the dynamic pathway dominated quenching for ZnL(R) with bulky substituents (R = tBu, DtBu). The quenching rate constants with varied nitroaromatics (ArNO2) followed the driving force dependence predicted for bimolecular electron transfer: ZnL* + ArNO2 --> ZnL(+) + ArNO2(-). A treatment of the diffusion-corrected quenching rates with Marcus theory yielded a modest reorganization energy (lambda = 25 kcal/mol), and a small self-exchange reorganization energy for ZnL*/ZnL(+) (ca. 20 kcal/mol) was estimated from the Marcus cross-relation, suggesting that metal phenoxyls may be robust biological redox cofactors. Electronic structure calculations indicated very small changes in bond distances for the ZnL --> ZnL(+) oxidation, suggesting that solvation was the dominant contributor to the observed reorganization energy. These mechanistic insights provide information that will be helpful to further develop ZnL(R) as sensors, as well as for potential photoinduced charge transfer chemistry.

Structural changes upon excitation of D1-D2-Cyt b559 photosystem II reaction centers depend on the beta-carotene content.

PubMed

Losi, Aba; Yruela, Inmaculada; Reus, Michael; Holzwarth, Alfred R; Braslavsky, Silvia E

2003-07-01

Different preparations of D1-D2-Cyt b559 complexes from spinach with different beta-carotene (Car) content [on average from <0.5 to 2 per reaction center (RC)] were studied by means of laser-induced optoacoustic spectroscopy. phiP680(+)Pheo(-) does not depend on the preparation (or on the Car content) inasmuch as the magnitude of the prompt heat (produced within 20 ns) does not vary for the different samples upon excitation at 675 and 620 nm. The energy level of the primary charge-separated state, P680(+)Pheo(-), was determined as EP680(+)Pheo(-) = 1.55 eV. Thus, an enthalpy change accompanying charge separation from excited P680 of deltaH*P680Pheo-->P680(+)Pheo(-) = -0.27 eV is obtained. Calculations using the heat evolved during the time-resolved decay of P680(+)Pheo(-) (< or = 100 ns) affords a triplet (3[P680Pheo]) quantum yield phi3[P680Pheo] = 0.5 +/- 0.14. The structural volume change, deltaV1, corresponding to the formation of P680(+)Pheo(-), strongly depends on the Car content; it is ca. -2.5 A3 molecule(-1) for samples with <0.5 Car on average, decreases (in absolute value) to -0.5 +/- 0.2 A3 for samples with an average of 1 Car, and remains the same for samples with two Cars per RC. This suggests that the Car molecules induce changes in the ground-state RC conformation, an idea which was confirmed by preferential excitation of Car with blue light, which produced different carotene triplet lifetimes in samples with 2 Car compared to those containing less carotene. We conclude that the two beta-carotenes are not structurally equivalent. Upon blue-light excitation (480 nm, preferential carotene absorption) the fraction of energy stored is ca. 60% for the 9Chl-2Car sample, whereas it is 40% for the preparations with one or less Cars on average, indicating different paths of energy distribution after Car excitation in these RCs with remaining chlorophyll antennae.

Photoelectric Effect: Back to Basics.

ERIC Educational Resources Information Center

Powell, R. A.

1978-01-01

Presents a simplified theoretical analysis of the variation of quantum yield with photon energy in the photoelectric experiment. Describes a way to amplify the experiment and make it more instructive to advanced students through the measurement of quantum yield of a photo cell. (GA)

DETERMINATION OF APPARENT QUANTUM YIELD SPECTRA FOR THE FORMATION OF BIOLOGICALLY LABILE PHOTOPRODUCTS

EPA Science Inventory

Quantum yield spectra for the photochemical formation of biologically labile photoproducts from dissolved organic matter (DOM) have not been available previously, although they would greatly facilitate attempts to model photoproduct formation rates across latitudinal, seasonal, a...

Terahertz cascades from nanoparticles

NASA Astrophysics Data System (ADS)

Arnardottir, K. B.; Liew, T. C. H.

2018-05-01

In this article we propose a system capable of terahertz (THz) radiation with quantum yield above unity. The system consists of nanoparticles where the material composition varies along the radial direction of each nanoparticle in such a way that a ladder of equidistant energy levels emerges. By then exciting the highest level of this ladder we produce multiple photons of the same frequency in the THz range. We demonstrate how we can calculate a continuous material composition profile that achieves a high quantum yield and then show that a more experimentally friendly design of a multishell nanoparticle can still result in a high quantum yield.

Photo-kinetics of photoinduced transformation reaction of methylene green with titanium trichloride in different solvents

NASA Astrophysics Data System (ADS)

Nadeem, Syed Muhammad Saqib; Saeed, Rehana

2017-08-01

The photo-kinetics of photoinduced transformation reaction of methylene green and titanium trichloride was investigated in water and different aqueous-alcoholic solvents. The reaction is pseudo-first order, dependent only on the concentration of titanium trichloride at fixed concentration of methylene green. The effect of water and aqueous-alcoholic solvents was studied in the acidic range from 4 to 7. It was observed that the quantum yield (φ) of reaction increased with increase in polarity of the solvent. The quantum yield (φ) was high in acidic condition and decreased with further increase in acidity. The quantum yield (φ) increased sharply with increase in concentration of titanium trichloride while it almost remained unaffected by change in concentration of methylene green. The addition of ions increased the quantum yield (φ) of reaction. The increase in temperature decreased the rate and quantum yield (φ) of reaction. An electron transfer mechanism for the reaction has been proposed in accordance with the kinetics of reaction. The absence of any reaction intermediate was confirmed by spectroscopic investigations. Activation energy ( E a) was calculated by Arrhenius relation. Thermodynamic parameters such as activation energy ( E a), enthalpy change (Δ H), free energy change (Δ G) and entropy change (Δ S) were also evaluated.

Fluorescence quantum yield of carbon dioxide for quantitative UV laser-induced fluorescence in high-pressure flames

NASA Astrophysics Data System (ADS)

Lee, T.; Bessler, W. G.; Yoo, J.; Schulz, C.; Jeffries, J. B.; Hanson, R. K.

2008-11-01

The fluorescence quantum yield for ultraviolet laser-induced fluorescence of CO2 is determined for selected excitation wavelengths in the range 215-250 nm. Wavelength-resolved laser-induced fluorescence (LIF) spectra of CO2, NO, and O2 are measured in the burned gases of a laminar CH4/air flame ( φ=0.9 and 1.1) at 20 bar with additional NO seeded into the flow. The fluorescence spectra are fit to determine the relative contribution of the three species to infer an estimate of fluorescence quantum yield for CO2 that ranges from 2-8×10-6 depending on temperature and excitation wavelength with an estimated uncertainty of ±0.5×10-6. The CO2 fluorescence signal increases linearly with gas pressure for flames with constant CO2 mole fraction for the 10 to 60 bar range, indicating that collisional quenching is not an important contributor to the CO2 fluorescence quantum yield. Spectral simulation calculations are used to choose two wavelengths for excitation of CO2, 239.34 and 242.14 nm, which minimize interference from LIF of NO and O2. Quantitative LIF images of CO2 are demonstrated using these two excitation wavelengths and the measured fluorescence quantum yield.

Control of the external photoluminescent quantum yield of emitters coupled to nanoantenna phased arrays

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

Guo, Ke; Verschuuren, Marc A.; Lozano, Gabriel

2015-08-21

Optical losses in metals represent the largest limitation to the external quantum yield of emitters coupled to plasmonic antennas. These losses can be at the emission wavelength, but they can be more important at shorter wavelengths, i.e., at the excitation wavelength of the emitters, where the conductivity of metals is usually lower. We present accurate measurements of the absolute external photoluminescent quantum yield of a thin layer of emitting material deposited over a periodic nanoantenna phased array. Emission and absorptance measurements of the sample are performed using a custom-made setup including an integrating sphere and variable angle excitation. The measurementsmore » reveal a strong dependence of the external quantum yield on the angle at which the optical field excites the sample. Such behavior is attributed to the coupling between far-field illumination and near-field excitation mediated by the collective resonances supported by the array. Numerical simulations confirm that the inherent losses associated with the metal can be greatly reduced by selecting an optimum angle of illumination, which boosts the light conversion efficiency in the emitting layer. This combined experimental and numerical characterization of the emission from plasmonic arrays reveals the need to carefully design the illumination to achieve the maximum external quantum yield.« less

Nuclear spin-isospin excitations from covariant quasiparticle-vibration coupling

NASA Astrophysics Data System (ADS)

Robin, Caroline; Litvinova, Elena

2016-09-01

Methods based on the relativistic Lagrangian of quantum hadrodynamics and nuclear field theory provide a consistent framework for the description of nuclear excitations, naturally connecting the high- and medium-energy scales of mesons to the low-energy domain of nucleonic collective motion. Applied in the neutral channel, this approach has been quite successful in describing the overall transition strength up to high excitation energies, as well as fine details of the low-lying distribution. Recently, this method has been extended to the description of spin-isospin excitations in open-shell nuclei. In the charge-exchange channel, the coupling between nucleons and collective vibrations generates a time-dependent proton-neutron effective interaction, in addition to the static pion and rho-meson exchange, and introduces complex configurations that induce fragmentation and spreading of the resonances. Such effects have a great impact on the quenching of the strength and on the computing of weak reaction rates that are needed for astrophysics modeling. Gamow-Teller transitions in medium-mass nuclei and associated beta-decay half-lives will be presented. Further developments aiming to include additional ground-state correlations will also be discussed. This work is supported by US-NSF Grants PHY-1404343 and PHY-1204486.

An efficient tensor transpose algorithm for multicore CPU, Intel Xeon Phi, and NVidia Tesla GPU

DOE PAGES

Lyakh, Dmitry I.

2015-01-05

An efficient parallel tensor transpose algorithm is suggested for shared-memory computing units, namely, multicore CPU, Intel Xeon Phi, and NVidia GPU. The algorithm operates on dense tensors (multidimensional arrays) and is based on the optimization of cache utilization on x86 CPU and the use of shared memory on NVidia GPU. From the applied side, the ultimate goal is to minimize the overhead encountered in the transformation of tensor contractions into matrix multiplications in computer implementations of advanced methods of quantum many-body theory (e.g., in electronic structure theory and nuclear physics). A particular accent is made on higher-dimensional tensors that typicallymore » appear in the so-called multireference correlated methods of electronic structure theory. Depending on tensor dimensionality, the presented optimized algorithms can achieve an order of magnitude speedup on x86 CPUs and 2-3 times speedup on NVidia Tesla K20X GPU with respect to the na ve scattering algorithm (no memory access optimization). Furthermore, the tensor transpose routines developed in this work have been incorporated into a general-purpose tensor algebra library (TAL-SH).« less

Efficient Carrier Multiplication in Colloidal Silicon Nanorods

DOE PAGES

Stolle, Carl Jackson; Lu, Xiaotang; Yu, Yixuan; ...

2017-08-01

In this study, auger recombination lifetimes, absorption cross sections, and the quantum yields of carrier multiplication (CM), or multiexciton generation (MEG), were determined for solvent-dispersed silicon (Si) nanorods using transient absorption spectroscopy (TAS). Nanorods with an average diameter of 7.5 nm and aspect ratios of 6.1, 19.3, and 33.2 were examined. Colloidal Si nanocrystals of similar diameters were also studied for comparison. The nanocrystals and nanorods were passivated with organic ligands by hydrosilylation to prevent surface oxidation and limit the effects of surface trapping of photoexcited carriers. All samples used in the study exhibited relatively efficient photoluminescence. The Auger lifetimesmore » increased with nanorod length, and the nanorods exhibited higher CM quantum yield and efficiency than the nanocrystals with a similar band gap energy E g. Beyond a critical length, the CM quantum yield decreases. Finally, nanorods with the aspect ratio of 19.3 had the highest CM quantum yield of 1.6 ± 0.2 at 2.9E g, which corresponded to a multiexciton yield that was twice as high as observed for the spherical nanocrystals.« less

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

Stolle, Carl Jackson; Lu, Xiaotang; Yu, Yixuan

In this study, auger recombination lifetimes, absorption cross sections, and the quantum yields of carrier multiplication (CM), or multiexciton generation (MEG), were determined for solvent-dispersed silicon (Si) nanorods using transient absorption spectroscopy (TAS). Nanorods with an average diameter of 7.5 nm and aspect ratios of 6.1, 19.3, and 33.2 were examined. Colloidal Si nanocrystals of similar diameters were also studied for comparison. The nanocrystals and nanorods were passivated with organic ligands by hydrosilylation to prevent surface oxidation and limit the effects of surface trapping of photoexcited carriers. All samples used in the study exhibited relatively efficient photoluminescence. The Auger lifetimesmore » increased with nanorod length, and the nanorods exhibited higher CM quantum yield and efficiency than the nanocrystals with a similar band gap energy E g. Beyond a critical length, the CM quantum yield decreases. Finally, nanorods with the aspect ratio of 19.3 had the highest CM quantum yield of 1.6 ± 0.2 at 2.9E g, which corresponded to a multiexciton yield that was twice as high as observed for the spherical nanocrystals.« less

Photoevaporating Disks around Young Stars: Ultracompact HII Regions and Protoplanetary Disks.

NASA Astrophysics Data System (ADS)

Johnstone, Douglas Ian

1995-01-01

Newly formed stars produce sufficient Lyman continuum luminosity phi to significantly alter the structure and evolution of the accretion disk surrounding them. In the absence of a stellar wind, a nearly static, photoionized, 10^4 K, disk atmosphere, with a scale height that increases with disk radius varpi as varpi^{3/2 }, forms inside the gravitational radius varpig ~ 1014(M_*/ M_odot) cm where M _* is the mass of the central star. This ionized atmosphere is maintained by both the direct radiation from the central star and the diffuse field produced in the disk atmosphere by the significant fraction of hydrogen recombinations directly to the ground state. Beyond varpig the material evaporated from the disk is capable of escaping from the system and produces an ionized disk wind. The mass-loss due to this disk wind peaks at varpig . The inclusion of a stellar wind into the basic picture reduces the height of the inner disk atmosphere and introduces a new scale radius varpi_ {w} where the thermal pressure of the material evaporated from the disk balances the ram pressure in the wind. In this case the mass-loss due to the disk wind peaks at varpiw and is enhanced over the no-wind case. The photoevaporation of disks around newly formed stars has significance to both ultracompact HII regions and the dispersal of solar-type nebulae. High mass stars are intrinsically hot and thus yield sufficient Lyman luminosity to create, even without a stellar wind, disk mass-loss rates of order 2 times 10 ^{-5}phi_sp{49} {1/2} M_odotyr ^{-1}, where phi 49 = phi/(10 49 Lyman continuum photons s^{-1}). This wind, which will last until the disk is dispersed, ~ 10^5 yrs if the disk mass is M_ {d}~0.3M_*, yields sizes, emission measures and ages consistent with observations of ultracompact HII regions. The well-observed high mass star MWC 349 may be the best example to date of an evaporating disk around a high mass star. On the other end of the stellar scale, many newly formed low-mass stars are known to have enhanced extreme ultraviolet luminosity suggested to be due to boundary layer accretion. Assuming that most low mass stars have such an enhanced Lyman luminosity phi ~ 1041 s ^{-1}, for ~ 3 times 10^7 yrs it is possible to remove most of the gas in the outer disk. A diagnostic of this mass loss may be the low-velocity forbidden oxygen, nitrogen, and sulphur line emission observed around young stars with disks. Photoevaporating disk models yield reasonable agreement with the flux seen in these lines. The process of photoevaporation also has implications for the formation of the giant planets within the solar nebula. Within young stellar clusters a few high mass stars may overwhelm the internal Lyman continuum flux from low mass stars and externally evaporated disks may result. The Trapezium region presents the best studied example of such a cluster. Photoionization due to high energy photons from the high mass stars erode the disks around nearby low mass stars. The resulting short destruction times for these disks constrain the gestation period for creating planets.

Measurement of the decays B--> phiK and B--> phiK*.

PubMed

Aubert, B; Boutigny, D; Gaillard, J M; Hicheur, A; Karyotakis, Y; Lees, J P; Robbe, P; Tisserand, V; Palano, A; Chen, G P; Chen, J C; Qi, N D; Rong, G; Wang, P; Zhu, Y S; Eigen, G; Reinertsen, P L; Stugu, B; Abbott, B; Abrams, G S; Borgland, A W; Breon, A B; Brown, D N; Button-Shafer, J; Cahn, R N; Clark, A R; Fan, Q; Gill, M S; Gowdy, S J; Gritsan, A; Groysman, Y; Jacobsen, R G; Kadel, R W; Kadyk, J; Kerth, L T; Kluth, S; Kolomensky, Y G; Kral, J F; LeClerc, C; Levi, M E; Liu, T; Lynch, G; Meyer, A B; Momayezi, M; Oddone, P J; Perazzo, A; Pripstein, M; Roe, N A; Romosan, A; Ronan, M T; Shelkov, V G; Telnov, A V; Wenzel, W A; Bright-Thomas, P G; Harrison, T J; Hawkes, C M; Kirk, A; Knowles, D J; O'Neale, S W; Penny, R C; Watson, A T; Watson, N K; Deppermann, T; Koch, H; Krug, J; Kunze, M; Lewandowski, B; Peters, K; Schmuecker, H; Steinke, M; Andress, J C; Barlow, N R; Bhimji, W; Chevalier, N; Clark, P J; Cottingham, W N; De Groot, N; Dyce, N; Foster, B; Mass, A; McFall, J D; Wallom, D; Wilson, F F; Abe, K; Hearty, C; Mattison, T S; McKenna, J A; Thiessen, D; Camanzi, B; Jolly, S; McKemey, A K; Tinslay, J; Blinov, V E; Bukin, A D; Bukin, D A; Buzykaev, A R; Dubrovin, M S; Golubev, V B; Ivanchenko, V N; Korol, A A; Kravchenko, E A; Onuchin, A P; Salnikov, A A; Serednyakov, S I; Skovpen, Y I; Telnov, V I; Yushkov, A N; Lankford, A J; Mandelkern, M; McMahon, S; Stoker, D P; Ahsan, A; Arisaka, K; Buchanan, C; Chun, S; Branson, J G; MacFarlane, D B; Prell, S; Rahatlou, S; Raven, G; Sharma, V; Campagnari, C; Dahmes, B; Hart, P A; Kuznetsova, N; Levy, S L; Long, O; Lu, A; Richman, J D; Verkerke, W; Witherell, M; Yellin, S; Beringer, J; Dorfan, D E; Eisner, A M; Frey, A; Grillo, A A; Grothe, M; Heusch, C A; Johnson, R P; Kroeger, W; Lockman, W S; Pulliam, T; Sadrozinski, H; Schalk, T; Schmitz, R E; Schumm, B A; Seiden, A; Turri, M; Walkowiak, W; Williams, D C; Wilson, M G; Chen, E; Dubois-Felsmann, G P; Dvoretskii, A; Hitlin, D G; Metzler, S; Oyang, J; Porter, F C; Ryd, A; Samuel, A; Weaver, M; Yang, S; Zhu, R Y; Devmal, S; Geld, T L; Jayatilleke, S; Mancinelli, G; Meadows, B T; Sokoloff, M D; Bloom, P; Fahey, S; Ford, W T; Gaede, F; Johnson, D R; Michael, A K; Nauenberg, U; Olivas, A; Park, H; Rankin, P; Roy, J; Sen, S; Smith, J G; van Hoek, W C; Wagner, D L; Blouw, J; Harton, J L; Krishnamurthy, M; Soffer, A; Toki, W H; Wilson, R J; Zhang, J; Brandt, T; Brose, J; Colberg, T; Dahlinger, G; Dickopp, M; Dubitzky, R S; Maly, E; Müller-Pfefferkorn, R; Otto, S; Schubert, K R; Schwierz, R; Spaan, B; Wilden, L; Behr, L; Bernard, D; Bonneaud, G R; Brochard, F; Cohen-Tanugi, J; Ferrag, S; Roussot, E; T'Jampens, S; Thiebaux, C; Vasileiadis, G; Verderi, M; Anjomshoaa, A; Bernet, R; Di Lodovico, F; Khan, A; Muheim, F; Playfer, S; Swain, J E; Falbo, M; Bozzi, C; Dittongo, S; Folegani, M; Piemontese, L; Treadwell, E; Anulli, F; Baldini-Ferroli, R; Calcaterra, A; de Sangro, R; Falciai, D; Finocchiaro, G; Patteri, P; Peruzzi, I M; Piccolo, M; Xie, Y; Zallo, A; Bagnasco, S; Buzzo, A; Contri, R; Crosetti, G; Fabbricatore, P; Farinon, S; Lo Vetere, M; Macri, M; Monge, M R; Musenich, R; Pallavicini, M; Parodi, R; Passaggio, S; Pastore, F C; Patrignani, C; Pia, M G; Priano, C; Robutti, E; Santroni, A; Morii, M; Bartoldus, R; Dignan, T; Hamilton, R; Mallik, U; Cochran, J; Crawley, H B; Fischer, P A; Lamsa, J; Meyer, W T; Rosenberg, E I; Benkebil, M; Grosdidier, G; Hast, C; Höcker, A; Lacker, H M; LePeltier, V; Lutz, A M; Plaszczynski, S; Schune, M H; Trincaz-Duvoid, S; Valassi, A; Wormser, G; Bionta, R M; Brigljevic, V; Fackler, O; Fujino, D; Lange, D J; Mugge, M; Shi, X; van Bibber, K; Wenaus, T J; Wright, D M; Wuest, C R; Carroll, M; Fry, J R; Gabathuler, E; Gamet, R; George, M; Kay, M; Payne, D J; Sloane, R J; Touramanis, C; Aspinwall, M L; Bowerman, D A; Dauncey, P D; Egede, U; Eschrich, I; Gunawardane, N J; Martin, R; Nash, J A; Sanders, P; Smith, D; Azzopardi, D E; Back, J J; Dixon, P; Harrison, P F; Potter, R J; Shorthouse, H W; Strother, P; Vidal, P B; Williams, M I; Cowan, G; George, S; Green, M G; Kurup, A; Marker, C E; McGrath, P; McMahon, T R; Ricciardi, S; Salvatore, F; Scott, I; Vaitsas, G; Brown, D; Davis, C L; Allison, J; Barlow, R J; Boyd, J T; Forti, A; Fullwood, J; Jackson, F; Lafferty, G D; Savvas, N; Simopoulos, E T; Weatherall, J H; Farbin, A; Jawahery, A; Lillard, V; Olsen, J; Roberts, D A; Schieck, J R; Blaylock, G; Dallapiccola, C; Flood, K T; Hertzbach, S S; Kofler, R; Lin, C S; Moore, T B; Staengle, H; Willocq, S; Wittlin, J; Brau, B; Cowan, R; Sciolla, G; Taylor, F; Yamamoto, R K; Britton, D I; Milek, M; Patel, P M; Trischuk, J; Lanni, F; Palombo, F; Bauer, J M; Booke, M; Cremaldi, L; Eschenburg, V; Kroeger, R; Reidy, J; Sanders, D A; Summers, D J; Martin, J P; Nief, J Y; Seitz, R; Taras, P; Zacek, V; Nicholson, H; Sutton, C S; Cartaro, C; Cavallo, N; De Nardo, G; Fabozzi, F; Gatto, C; Lista, L; Paolucci, P; Piccolo, D; Sciacca, C; LoSecco, J M; Alsmiller, J R; Gabriel, T A; Handler, T; Brau, J; Frey, R; Iwasaki, M; Sinev, N B; Strom, D; Colecchia, F; Dal Corso, F; Dorigo, A; Galeazzi, F; Margoni, M; Michelon, G; Morandin, M; Posocco, M; Rotondo, M; Simonetto, F; Stroili, R; Torassa, E; Voci, C; Benayoun, M; Briand, H; Chauveau, J; David, P; De La Vaissière, C; Del Buono, L; Hamon, O; Le Diberder, F; Leruste, P; Lory, J; Roos, L; Stark, J; Versillé, S; Manfredi, P F; Re, V; Speziali, V; Frank, E D; Gladney, L; Guo, Q H; Panetta, J H; Angelini, C; Batignani, G; Bettarini, S; Bondioli, M; Carpinelli, M; Forti, F; Giorgi, M A; Lusiani, A; Martinez-Vidal, F; Morganti, M; Neri, N; Paoloni, E; Rama, M; Rizzo, G; Sandrelli, F; Simi, G; Triggiani, G; Walsh, J; Haire, M; Judd, D; Paick, K; Turnbull, L; Wagoner, D E; Albert, J; Bula, C; Lu, C; McDonald, K T; Miftakov, V; Schaffner, S F; Smith, A J; Tumanov, A; Varnes, E W; Cavoto, G; del Re, D; Faccini, R; Ferrarotto, F; Ferroni, F; Fratini, K; Lamanna, E; Leonardi, E; Mazzoni, M A; Morganti, S; Piredda, G; Safai Tehrani, F; Serra, M; Voena, C; Christ, S; Waldi, R; Adye, T; Franek, B; Geddes, N I; Gopal, G P; Xella, S M; Aleksan, R; De Domenico, G; Emery, S; Gaidot, A; Ganzhur, S F; Giraud, P F; Hamel De Monchenault, G; Kozanecki, W; Langer, M; London, G W; Mayer, B; Serfass, B; Vasseur, G; Yeche, C; Zito, M; Copty, N; Purohit, M V; Singh, H; Yumiceva, F X; Adam, I; Anthony, P L; Aston, D; Baird, K; Bartelt, J; Bloom, E; Boyarski, A M; Bulos, F; Calderini, G; Claus, R; Convery, M R; Coupal, D P; Coward, D H; Dorfan, J; Doser, M; Dunwoodie, W; Field, R C; Glanzman, T; Godfrey, G L; Grosso, P; Himel, T; Huffer, M E; Innes, W R; Jessop, C P; Kelsey, M H; Kim, P; Kocian, M L; Langenegger, U; Leith, D W; Luitz, S; Luth, V; Lynch, H L; Manzin, G; Marsiske, H; Menke, S; Messner, R; Moffeit, K C; Mount, R; Muller, D R; O'Grady, C P; Petrak, S; Quinn, H; Ratcliff, B N; Robertson, S H; Rochester, L S; Roodman, A; Schietinger, T; Schindler, R H; Schwiening, J; Serbo, V V; Snyder, A; Soha, A; Spanier, S M; Stahl, A; Stelzer, J; Su, D; Sullivan, M K; Talby, M; Tanaka, H A; Trunov, A; Va'vra, J; Wagner, S R; Weinstein, A J; Wisniewski, W J; Young, C C; Burchat, P R; Cheng, C H; Kirkby, D; Meyer, T I; Roat, C; De Silva, A; Henderson, R; Bugg, W; Cohn, H; Hart, E; Weidemann, A W; Benninger, T; Izen, J M; Kitayama, I; Lou, X C; Turcotte, M; Bianchi, F; Bona, M; Di Girolamo, B; Gamba, D; Smol, A; Zanin, D; Bosisio, L; Della Ricca, G; Lanceri, L; Pompili, A; Poropat, P; Prest, M; Vallazza, E; Vuagnin, G; Panvini, R S; Brown, C M; Kowalewski, R; Roney, J M; Band, H R; Charles, E; Dasu, S; Elmer, P; Hu, H; Johnson, J R; Liu, R; Nielsen, J; Orejudos, W; Pan, Y; Prepost, R; Scott, I J; Sekula, S J; von Wimmersperg-Toeller, J H; Wu, S L; Yu, Z; Zobering, H; Kordich, T M; Neal, H

2001-10-08

We have observed the decays B--> phiK and phiK(*) in a sample of over 45 million B mesons collected with the BABAR detector at the PEP-II collider. The measured branching fractions are B(B+--> phiK+) = (7.7(+1.6)(-1.4)+/-0.8)x10(-6), B(B0--> phiK0) = (8.1(+3.1)(-2.5)+/-0.8)x10(-6), B(B+--> phiK(*+)) = (9.7(+4.2)(-3.4)+/-1.7)x10(-6), and B(B0--> phiK(*0)) = (8.7(+2.5)(-2.1)+/-1.1)x10(-6). We also report the upper limit B(B+--> phipi(+))<1.4x10(-6) ( 90% C.L.).

Effects of Bleaching by Nitrogen Deficiency on the Quantum Yield of Photosystem II in Synechocystis sp. PCC 6803 Revealed by Chl Fluorescence Measurements.

PubMed

Ogawa, Takako; Sonoike, Kintake

2016-03-01

Estimation of photosynthesis by Chl fluorescence measurement of cyanobacteria is always problematic due to the interference from respiratory electron transfer and from phycocyanin fluorescence. The interference from respiratory electron transfer could be avoided by the use of DCMU or background illumination by blue light, which oxidizes the plastoquinone pool that tends to be reduced by respiration. On the other hand, the precise estimation of photosynthesis in cells with a different phycobilisome content by Chl fluorescence measurement is difficult. By subtracting the basal fluorescence due to the phycobilisome and PSI, it becomes possible to estimate the precise maximum quantum yield of PSII in cyanobacteria. Estimated basal fluorescence accounted for 60% of the minimum fluorescence, resulting in a large difference between the 'apparent' yield and 'true' yield under high phycocyanin conditions. The calculated value of the 'true' maximum quantum yield of PSII was around 0.8, which was similar to the value observed in land plants. The results suggest that the cause of the apparent low yield reported in cyanobacteria is mainly ascribed to the interference from phycocyanin fluorescence. We also found that the 'true' maximum quantum yield of PSII decreased under nitrogen-deficient conditions, suggesting the impairment of the PSII reaction center, while the 'apparent' maximum quantum yield showed a marginal change under the same conditions. Due to the high contribution of phycocyanin fluorescence in cyanobacteria, it is essential to eliminate the influence of the change in phycocyanin content on Chl fluorescence measurement and to evaluate the 'true' photosynthetic condition. © The Author 2016. Published by Oxford University Press on behalf of Japanese Society of Plant Physiologists. All rights reserved. For permissions, please email: journals.permissions@oup.com.

High quantum-yield phosphors via quantum splitting and upconversion

NASA Astrophysics Data System (ADS)

Jeong, Joayoung

The Gd3+ ion has been used to induce quantum splitting in luminescent materials by using cross-relaxation energy transfer (CRET). In Nd:LiGdF4, quantum splitting results from a two-step CRET between Gd3+ and Nd3+, first involving a transition 6G→6I on Gd3+ and an excitation within the 4f3 configuration of Nd3+ followed by a second CRET that brings Gd3+ to 6P7/2. The excited Nd3+ ion rapidly relaxes nonradiatively to the emitting 4F3/2. The excited Gd3+ ion then transfers its energy back to Nd3+, which gives rise to the second photon. The result is a quantum yield of 1.05 +/- 0.35 with emission in the NIR following excitation at 175 nm. GdF3:Pr3+, Eu 3+ also exhibits quantum splitting, but only at very low concentration of Pr3+ (0.3%) and Eu3+ (0.2%), resulting in a quantum yield of approximately 20% under 160-nm excitation. Host intrinsic emission via a self-trapped exciton (STE) was also examined as a means to sensitize Gd3+ emission. The material ScPO4:Gd 3+ exhibits a high absolute quantum yield of 0.9 +/- 0.2 under 170-nm excitation, demonstrating a potentially new and efficient pathway for exciting quantum splitting phosphors. Single crystals of the material GdZrF7 were grown, and its structure was established via single-crystal X-ray diffraction methods. Doped samples of GdZrF7:Yb3+, Er3+ exhibit bright up-conversion luminescence with light output that is up to twice that of a commercial material based on the host Gd2O2S. When doped with Eu3+, the fluoride also emits a nearly white color under vacuum ultraviolet excitation with an absolute quantum yield near 0.9. The new compound Gd4.67(SiO4)3S was synthesized and studied. The structure was established via single-crystal X-ray methods, and the luminescence of Tb3+ samples was investigated.

The anticholinergic and antiglutamatergic drug caramiphen reduces seizure duration in soman-exposed rats: Synergism with the benzodiazepine diazepam

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

Schultz, M.K.; Wright, L.K.M.; Stone, M.F.

2012-03-15

Therapy of seizure activity following exposure to the nerve agent soman (GD) includes treatment with the anticonvulsant diazepam (DZP), an allosteric modulator of γ-aminobutyric acid A (GABA{sub A}) receptors. However, seizure activity itself causes the endocytosis of GABA{sub A} receptors and diminishes the inhibitory effects of GABA, thereby reducing the efficacy of DZP. Treatment with an N-methyl-D-aspartic acid (NMDA) receptor antagonist prevents this reduction in GABAergic inhibition. We examined the efficacy of the NMDA receptor antagonist caramiphen edisylate (CED; 20 mg/kg, im) and DZP (10 mg/kg, sc), administered both separately and in combination, at 10, 20 or 30 min followingmore » seizure onset for attenuation of the deleterious effects associated with GD exposure (1.2 LD{sub 50}; 132 μg/kg, sc) in rats. Outcomes evaluated were seizure duration, neuropathology, acetylcholinesterase (AChE) activity, body weight, and temperature. We also examined the use of the reversible AChE inhibitor physostigmine (PHY; 0.2 mg/kg, im) as a therapy for GD exposure. We found that the combination of CED and DZP yielded a synergistic effect, shortening seizure durations and reducing neuropathology compared to DZP alone, when treatment was delayed 20–30 min after seizure onset. PHY reduced the number of animals that developed seizures, protected a fraction of AChE from GD inhibition, and attenuated post-exposure body weight and temperature loss independent of CED and/or DZP treatment. We conclude that: 1) CED and DZP treatment offers considerable protection against the effects of GD and 2) PHY is a potential therapeutic option following GD exposure, albeit with a limited window of opportunity. -- Highlights: ► Soman (GD) produced seizure activity resulting in neuropathology in rats. ► Tx: caramiphen (CED) and/or diazepam (DZP) @ 10, 20 or 30 min after seizure onset. ► CED/DZP showed superior anticonvulsant and neuroprotective capacity. ► Physostigmine (PHY) was examined as an adjunct post-exposure therapy. ► PHY attenuated GD-induced seizure development, but not seizure duration.« less

System and method for constructing filters for detecting signals whose frequency content varies with time

DOEpatents

Qian, Shie; Dunham, Mark E.

1996-01-01

A system and method for constructing a bank of filters which detect the presence of signals whose frequency content varies with time. The present invention includes a novel system and method for developing one or more time templates designed to match the received signals of interest and the bank of matched filters use the one or more time templates to detect the received signals. Each matched filter compares the received signal x(t) with a respective, unique time template that has been designed to approximate a form of the signals of interest. The robust time domain template is assumed to be of the order of w(t)=A(t)cos{2.pi..phi.(t)} and the present invention uses the trajectory of a joint time-frequency representation of x(t) as an approximation of the instantaneous frequency function {.phi.'(t). First, numerous data samples of the received signal x(t) are collected. A joint time frequency representation is then applied to represent the signal, preferably using the time frequency distribution series (also known as the Gabor spectrogram). The joint time-frequency transformation represents the analyzed signal energy at time t and frequency .function., P(t,f), which is a three-dimensional plot of time vs. frequency vs. signal energy. Then P(t,f) is reduced to a multivalued function f(t), a two dimensional plot of time vs. frequency, using a thresholding process. Curve fitting steps are then performed on the time/frequency plot, preferably using Levenberg-Marquardt curve fitting techniques, to derive a general instantaneous frequency function .phi.'(t) which best fits the multivalued function f(t), a trajectory of the joint time-frequency domain representation of x(t). Integrating .phi.'(t) along t yields .phi.(t), which is then inserted into the form of the time template equation. A suitable amplitude A(t) is also preferably determined. Once the time template has been determined, one or more filters are developed which each use a version or form of the time template.

Nuclear and Particle Physics Simulations: The Consortium of Upper-Level Physics Software

NASA Astrophysics Data System (ADS)

Bigelow, Roberta; Moloney, Michael J.; Philpott, John; Rothberg, Joseph

1995-06-01

The Consortium for Upper Level Physics Software (CUPS) has developed a comprehensive series of Nine Book/Software packages that Wiley will publish in FY `95 and `96. CUPS is an international group of 27 physicists, all with extensive backgrounds in the research, teaching, and development of instructional software. The project is being supported by the National Science Foundation (PHY-9014548), and it has received other support from the IBM Corp., Apple Computer Corp., and George Mason University. The Simulations being developed are: Astrophysics, Classical Mechanics, Electricity & Magnetism, Modern Physics, Nuclear and Particle Physics, Quantum Mechanics, Solid State, Thermal and Statistical, and Wave and Optics.

Photoactive High Explosives: Substituents Effects on Tetrazine Photochemistry and Photophysics

DOE PAGES

McGrane, Shawn David; Bolme, Cynthia Anne; Greenfield, Margo Torello; ...

2016-01-21

High explosives that are photoactive, i.e., can be initiated with light, offer significant advantages in reduced potential for accidental electrical initiation. In this study, we examined a series of structurally related tetrazine based photoactive high explosive materials to detail their photochemical and photophysical properties. Using photobleaching infrared absorption, we determined quantum yields of photochemistry for nanosecond pulsed excitation at 355 and 532 nm. Changes in mass spectrometry during laser irradiation in vacuum measured the evolution of gaseous products. Fluorescence spectra, quantum yields, and lifetimes were measured to observe radiative channels of energy decay that compete with photochemistry. For the 6more » materials studied, quantum yields of photochemistry ranged from <10 –5 to 0.03 and quantum yield of fluorescence ranged from <10 –3 to 0.33. In all cases, the photoexcitation nonradiatively relaxed primarily to heat, appropriate for supporting photothermal initiation processes. Lastly, the photochemistry observed was dominated by ring scission of the tetrazine, but there was evidence of more extensive multistep reactions as well.« less

Optomechanical Control of Quantum Yield in Trans-Cis Ultrafast Photoisomerization of a Retinal Chromophore Model.

PubMed

Valentini, Alessio; Rivero, Daniel; Zapata, Felipe; García-Iriepa, Cristina; Marazzi, Marco; Palmeiro, Raúl; Fdez Galván, Ignacio; Sampedro, Diego; Olivucci, Massimo; Frutos, Luis Manuel

2017-03-27

The quantum yield of a photochemical reaction is one of the most fundamental quantities in photochemistry, as it measures the efficiency of the transduction of light energy into chemical energy. Nature has evolved photoreceptors in which the reactivity of a chromophore is enhanced by its molecular environment to achieve high quantum yields. The retinal chromophore sterically constrained inside rhodopsin proteins represents an outstanding example of such a control. In a more general framework, mechanical forces acting on a molecular system can strongly modify its reactivity. Herein, we show that the exertion of tensile forces on a simplified retinal chromophore model provokes a substantial and regular increase in the trans-to-cis photoisomerization quantum yield in a counterintuitive way, as these extension forces facilitate the formation of the more compressed cis photoisomer. A rationale for the mechanochemical effect on this photoisomerization mechanism is also proposed. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Phosphite, an analog of phosphate, suppresses the coordinated expression of genes under phosphate starvation.

PubMed

Varadarajan, Deepa K; Karthikeyan, Athikkattuvalasu S; Matilda, Paino Durzo; Raghothama, Kashchandra G

2002-07-01

Phosphate (Pi) and its analog phosphite (Phi) are acquired by plants via Pi transporters. Although the uptake and mobility of Phi and Pi are similar, there is no evidence suggesting that plants can utilize Phi as a sole source of phosphorus. Phi is also known to interfere with many of the Pi starvation responses in plants and yeast (Saccharomyces cerevisiae). In this study, effects of Phi on plant growth and coordinated expression of genes induced by Pi starvation were analyzed. Phi suppressed many of the Pi starvation responses that are commonly observed in plants. Enhanced root growth and root to shoot ratio, a hallmark of Pi stress response, was strongly inhibited by Phi. The negative effects of Phi were not obvious in plants supplemented with Pi. The expression of Pi starvation-induced genes such as LePT1, LePT2, AtPT1, and AtPT2 (high-affinity Pi transporters); LePS2 (a novel acid phosphatase); LePS3 and TPSI1 (novel genes); and PAP1 (purple acid phosphatase) was suppressed by Phi in plants and cell cultures. Expression of luciferase reporter gene driven by the Pi starvation-induced AtPT2 promoter was also suppressed by Phi. These analyses showed that suppression of Pi starvation-induced genes is an early response to addition of Phi. These data also provide evidence that Phi interferes with gene expression at the level of transcription. Synchronized suppression of multiple Pi starvation-induced genes by Phi points to its action on the early molecular events, probably signal transduction, in Pi starvation response.

USE OF THE PROSTATE HEALTH INDEX FOR DETECTION OF PROSTATE CANCER: RESULTS FROM A LARGE ACADEMIC PRACTICE

PubMed Central

Tosoian, Jeffrey J.; Druskin, Sasha C.; Andreas, Darian; Mullane, Patrick; Chappidi, Meera; Joo, Sarah; Ghabili, Kamyar; Agostino, Joseph; Macura, Katarzyna J.; Carter, H. Ballentine; Schaeffer, Edward M.; Partin, Alan W.; Sokoll, Lori J.; Ross, Ashley E.

2016-01-01

BACKGROUND The Prostate Health Index (phi) outperforms PSA and other PSA derivatives for the diagnosis of prostate cancer (PCa). The impact of phi testing in the real-world clinical setting has not been previously assessed. METHODS In a single, large, academic center, phi was tested in 345 patients presenting for diagnostic evaluation for PCa. Findings on prostate biopsy (including Grade Group [GG], defined as GG1: Gleason score [GS] 6, GG2: GS 3+4=7, GG3: GS 4+3=7, GG4: GS 8, and GG5: GS 9-10), magnetic resonance imaging (MRI), and radical prostatectomy (RP) were prospectively recorded. Biopsy rates and outcomes were compared to a contemporary cohort that did not undergo phi testing (n=1318). RESULTS Overall, 39% of men with phi testing underwent prostate biopsy. No men with phi<19.6 were diagnosed with PCa, and only 3 men with phi<27 had cancer of GG≥2. Phi was superior to PSA for the prediction of any PCa (AUC 0.72 vs. 0.47) and GG≥2 PCa (AUC 0.77 vs. 0.53) on prostate biopsy. Among men undergoing MRI and phi, no men with phi<27 and PI-RADS≤3 had GG≥2 cancer. For those men proceeding to RP, increasing phi was associated with higher pathologic GG (p=0.002) and stage (p=0.001). Compared to patients who did not undergo phi testing, the use of phi was associated with a 9% reduction in the rate of prostate biopsy (39% vs. 48%; p<0.001). Importantly, the reduction in biopsy among the phi population was secondary to decreased incidence of negative (8%) and GG1 (1%) biopsies, while the proportion of biopsies detecting GG≥2 cancers remained unchanged. CONCLUSIONS In this large, real-time clinical experience, phi outperformed PSA alone, was associated with high-grade PCa, and provided complementary information to MRI. Incorporation of phi into clinical practice reduced the rate of unnecessary biopsies without changing the frequency of detection of higher grade cancers. PMID:28117387

Phytochromes play a role in phototropism and gravitropism in Arabidopsis roots

NASA Astrophysics Data System (ADS)

Correll, Melanie J.; Coveney, Katrina M.; Raines, Steven V.; Mullen, Jack L.; Hangarter, Roger P.; Kiss, John Z.

2003-05-01

Phototropism as well as gravitropism plays a role in the oriented growth of roots in flowering plants. In blue or white light, roots exhibit negative phototropism, but red light induces positive phototropism in Arabidopsis roots. Phytochrome A (phyA) and phyB mediate the positive red-light-based photoresponse in roots since single mutants (and the double phyAB mutant) were severely impaired in this response. In blue-light-based negative phototropism, phyA and phyAB (but not phyB) were inhibited in the response relative to the WT. In root gravitropism, phyB and phyAB (but not phyA) were inhibited in the response compared to the WT. The differences observed in tropistic responses were not due to growth limitations since the growth rates among all the mutants tested were not significantly different from that of the WT. Thus, our study shows that the blue-light and red-light systems interact in roots and that phytochrome plays a key role in plant development by integrating multiple environmental stimuli.

Multiple phytochromes are involved in red-light-induced enhancement of first-positive phototropism in arabidopsis thaliana

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

Janoudi, A.K.; Gordon, W.R.; Poff, K.L.

1997-03-01

The amplitude of phototropic curvature to blue light is enhanced by a prior exposure of seedlings to red light. This enhancement is mediated by phytochrome. Fluence-response relationships have been constructed for red-light-induced enhancement in the phytochrome A (phyA) null mutant, the phytochrome B- (phyB) deficient mutant, and in two transgenic lines of Arabidopsis thaliana that overexpress either phyA or phyB. These fluence-response relationships demonstrate the existence of two responses in enhancement, a response in the very-low-to-low-fluence range, and a response in the high-fluence range. Only the response in the high-fluence range is present in the phyA null mutant. In contrast,more » the phyB-deficient mutant is indistinguishable from the wild-type parent in red-light responsiveness. These data indicate that phyA is necessary for the very-low-to-low but not the high-fluence response, and that phyB is not necessary for either response range. Based on these results, the high-fluence response, if controlled by a single phytochrome, must be controlled by a phytochrome other than phyA or phyB. Overexpression of phyA has a negative effect and overexpression of phyB has an enhancing effect in the high fluence range. These results suggest that overexpression of either phytochrome perturbs the function of the endogenous photoreceptor system in unpreditable fashion. 25 refs., 3 figs.« less

SUMOylation of phytochrome-B negatively regulates light-induced signaling in Arabidopsis thaliana

PubMed Central

Sadanandom, Ari; Ádám, Éva; Orosa, Beatriz; Viczián, András; Klose, Cornelia; Zhang, Cunjin; Josse, Eve-Marie; Kozma-Bognár, László; Nagy, Ferenc

2015-01-01

The red/far red light absorbing photoreceptor phytochrome-B (phyB) cycles between the biologically inactive (Pr, λmax, 660 nm) and active (Pfr; λmax, 730 nm) forms and functions as a light quality and quantity controlled switch to regulate photomorphogenesis in Arabidopsis. At the molecular level, phyB interacts in a conformation-dependent fashion with a battery of downstream regulatory proteins, including PHYTOCHROME INTERACTING FACTOR transcription factors, and by modulating their activity/abundance, it alters expression patterns of genes underlying photomorphogenesis. Here we report that the small ubiquitin-like modifier (SUMO) is conjugated (SUMOylation) to the C terminus of phyB; the accumulation of SUMOylated phyB is enhanced by red light and displays a diurnal pattern in plants grown under light/dark cycles. Our data demonstrate that (i) transgenic plants expressing the mutant phyBLys996Arg-YFP photoreceptor are hypersensitive to red light, (ii) light-induced SUMOylation of the mutant phyB is drastically decreased compared with phyB-YFP, and (iii) SUMOylation of phyB inhibits binding of PHYTOCHROME INTERACTING FACTOR 5 to phyB Pfr. In addition, we show that OVERLY TOLERANT TO SALT 1 (OTS1) de-SUMOylates phyB in vitro, it interacts with phyB in vivo, and the ots1/ots2 mutant is hyposensitive to red light. Taken together, we conclude that SUMOylation of phyB negatively regulates light signaling and it is mediated, at least partly, by the action of OTS SUMO proteases. PMID:26283376

Photosynthetic Physiological Response of Radix Isatidis (Isatis indigotica Fort.) Seedlings to Nicosulfuron

PubMed Central

Ning, Na; Wen, Yinyuan; Dong, Shuqi; Yin, Meiqiang; Guo, Meijun; Wang, Binqiang; Feng, Lei; Guo, Pingyi

2014-01-01

Radix Isatidis (Isatis indigotica Fort.) is one of the most important traditional Chinese medicine plants. However, there is no suitable herbicide used for weed control in Radix Isatidis field during postemergence stage. To explore the safety of sulfonylurea herbicide nicosulfuron on Radix Isatidis (Isatis indigotica Fort.) seedlings and the photosynthetic physiological response of the plant to the herbicide, biological mass, leaf area, photosynthetic pigment content, photosynthetic rate, chlorophyll fluorescence characteristics, and P700 parameters of Radix Isatidis seedlings were analyzed 10 d after nicosulfuron treatment at 5th leaf stage in this greenhouse research. The results showed that biological mass, total chlorophyll, chlorophyll a, and carotenoids content, photosynthetic rate, stomatal conductance, PS II maximum quantum yield, PS II effective quantum yield, PS II electron transport rate, photochemical quenching, maximal P700 change, photochemical quantum yield of PS I, and PS I electron transport rate decreased with increasing herbicide concentrations, whereas initial fluorescence, quantum yield of non-regulated energy dissipation in PS II and quantum yield of non-photochemical energy dissipation due to acceptor side limitation in PS I increased. It suggests that nicosulfuron ≥1 mg L−1 causes the damage of chloroplast, PS II and PS I structure. Electron transport limitations in PS I receptor side, and blocked dark reaction process may be the main cause of the significantly inhibited growth and decreased photosynthetic rate of Radix Isatidis seedlings. PMID:25165819

Synthesis, characterization and photophysical-theoretical analysis of compounds A-π-D. 1. Effect of alkyl-phenyl substituted amines in photophysical properties

NASA Astrophysics Data System (ADS)

Ortega, E.; Montecinos, R.; Cattin, L.; Díaz, F. R.; del Valle, M. A.; Bernède, J. C.

2017-08-01

The study of new dipolar A-π-D molecules, which have an acceptor (A) and donor (D) charge joined by a conjugate bridge, have been an attention focus in the recent years due their different properties. In the current work, a molecular system has been modified in order to compare the effect on properties, such as quantum yield. Thus, two series were generated (alkyl- and alkoxy-substituted) to determine if molecules with tertiary asymmetric amines change their optical properties and whether quantum yield is affected. The different products have been characterized by several techniques such as UV-Vis spectrophotometry, elemental analysis, NMR, FT-IR, mass spectroscopy and fluorescence spectroscopy. Furthermore, their behavior in eight organic solvents, dichloromethane, tetrahydrofuran, ethyl acetate, 1,4-dioxane, acetone, acetonitrile, dimethylformamide and dimethylsulfoxide were experimentally and theoretically studied. The quantum yields were higher for the alkyl-substituted series. Theoretically, the dihedral angles formed between the tertiary amine and carbonyl group moieties have a correlation with quantum yield values, helping to explain why they are higher in non-polar solvents. Consequently, the maximum quantum yield was obtained with (E)-2-cyano-3-(5-((E)-2-(9,9-diethyl-7-(methyl(phenyl)amino)-9H-fluoren-2-yl) vinyl)thiophen-2-yl)acrylic acid (M8-1) in 1,4-dioxane, reaching 98.8%.

Silicon Nanoparticles with Surface Nitrogen: 90% Quantum Yield with Narrow Luminescence Bandwidth and the Ligand Structure Based Energy Law.

PubMed

Li, Qi; Luo, Tian-Yi; Zhou, Meng; Abroshan, Hadi; Huang, Jingchun; Kim, Hyung J; Rosi, Nathaniel L; Shao, Zhengzhong; Jin, Rongchao

2016-09-27

Silicon nanoparticles (NPs) have been widely accepted as an alternative material for typical quantum dots and commercial organic dyes in light-emitting and bioimaging applications owing to silicon's intrinsic merits of least toxicity, low cost, and high abundance. However, to date, how to improve Si nanoparticle photoluminescence (PL) performance (such as ultrahigh quantum yield, sharp emission peak, high stability) is still a major issue. Herein, we report surface nitrogen-capped Si NPs with PL quantum yield up to 90% and narrow PL bandwidth (full width at half-maximum (fwhm) ≈ 40 nm), which can compete with commercial dyes and typical quantum dots. Comprehensive studies have been conducted to unveil the influence of particle size, structure, and amount of surface ligand on the PL of Si NPs. Especially, a general ligand-structure-based PL energy law for surface nitrogen-capped Si NPs is identified in both experimental and theoretical analyses, and the underlying PL mechanisms are further discussed.

Multisite light-induced phosphorylation of the transcription factor PIF3 is necessary for both its rapid degradation and concomitant negative feedback modulation of photoreceptor phyB levels in Arabidopsis

USDA-ARS?s Scientific Manuscript database

Plants constantly monitor informational light signals using sensory photoreceptors, which include the phytochrome (phy) family (phyA to phyE), and adjust their growth and development accordingly. Following light-induced nuclear translocation, photoactivated phy molecules bind to and induce rapid pho...

Efficient Calculation of Exact Exchange Within the Quantum Espresso Software Package

NASA Astrophysics Data System (ADS)

Barnes, Taylor; Kurth, Thorsten; Carrier, Pierre; Wichmann, Nathan; Prendergast, David; Kent, Paul; Deslippe, Jack

Accurate simulation of condensed matter at the nanoscale requires careful treatment of the exchange interaction between electrons. In the context of plane-wave DFT, these interactions are typically represented through the use of approximate functionals. Greater accuracy can often be obtained through the use of functionals that incorporate some fraction of exact exchange; however, evaluation of the exact exchange potential is often prohibitively expensive. We present an improved algorithm for the parallel computation of exact exchange in Quantum Espresso, an open-source software package for plane-wave DFT simulation. Through the use of aggressive load balancing and on-the-fly transformation of internal data structures, our code exhibits speedups of approximately an order of magnitude for practical calculations. Additional optimizations are presented targeting the many-core Intel Xeon-Phi ``Knights Landing'' architecture, which largely powers NERSC's new Cori system. We demonstrate the successful application of the code to difficult problems, including simulation of water at a platinum interface and computation of the X-ray absorption spectra of transition metal oxides.

Quantum teleportation of an arbitrary two-qubit state and its relation to multipartite entanglement

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

Rigolin, Gustavo

2005-03-01

We explicitly show a protocol in which an arbitrary two qubit state vertical bar {phi}>=a vertical bar 00>+b vertical bar 01>+c vertical bar 10>+d vertical bar 11> is faithfully and deterministically teleported from Alice to Bob. We construct the 16 orthogonal generalized Bell states that can be used to teleport the two qubits. The local operations Bob must perform on his qubits in order to recover the teleported state are also constructed. They are restricted only to single-qubit gates. This means that a controlled-NOT gate is not necessary to complete the protocol. A generalization where N qubits are teleported ismore » also shown. We define a generalized magic basis, which possesses interesting properties. These properties help us to suggest a generalized concurrence from which we construct a measure of entanglement that has a clear physical interpretation: A multipartite state has maximum entanglement if it is a genuine quantum teleportation channel.« less

[Genetic study of bacteriophage phi81. I. Isolation, study of complementation and preliminary mapping of amber-mutants of bacteriophage phi81].

PubMed

Sineokiĭ, S P; Pogosov, V Z; Iankovskiĭ, N K; Krylov, V N

1976-01-01

123 Amber mutants of lambdoid bacteriophage phi81 are isolated and distributed into 19 complementation groups. Deletion mapping made possible to locate 5 gene groups on the genetic map of bacteriophage phi81 and to determine a region of possible location of mm' sticky ends on the prophage genetic map. A gene of phage phi81 is localized, which controls the adsorption specificity, and which functional similarity to a respective gene of phage phi80 is demonstrated.

Do the cations in clay and the polymer matrix affect quantum dot fluorescent properties?

PubMed

Wei, Wenjun; Liu, Cui; Liu, Jiyan; Liu, Xueqing; Zou, Linling; Cai, Shaojun; Shi, Hong; Cao, Yuan-Cheng

2016-06-01

This paper studied the effects of cations and polymer matrix on the fluorescent properties of quantum dots (QDs). The results indicated that temperature has a greater impact on fluorescence intensity than clay cations (mainly K(+) and Na(+) ). Combined fluorescence lifetime and steady-state spectrometer tests showed that QD lifetimes all decreased when the cation concentration was increased, but the quantum yields were steady at various cation concentrations of 0, 0.05, 0.5 and 1 M. Poly(ethylene oxide) (PEO), poly(vinyl alcohol) (PVA) and diepoxy resin were used to study the effects of polymers on QD lifetime and quantum yield. The results showed that the lifetime for QDs 550 nm in PEO and PVA was 17.33 and 17.12 ns, respectively; for the epoxy resin, the lifetime was 0.74 ns, a sharp decrease from 24.47 ns. The quantum yield for QDs 550 nm changed from 34.22% to 7.45% and 7.81% in PEO and PVA, respectively; for the epoxy resin the quantum yield was 2.25%. QDs 580 nm and 620 nm showed the same results as QDs 550 nm. This study provides useful information on the design, synthesis and application of QDs-polymer luminescent materials. Copyright © 2015 John Wiley & Sons, Ltd. Copyright © 2015 John Wiley & Sons, Ltd.

Action spectra of photosystems II and I and quantum yield of photosynthesis in leaves in State 1.

PubMed

Laisk, Agu; Oja, Vello; Eichelmann, Hillar; Dall'Osto, Luca

2014-02-01

The spectral global quantum yield (YII, electrons/photons absorbed) of photosystem II (PSII) was measured in sunflower leaves in State 1 using monochromatic light. The global quantum yield of PSI (YI) was measured using low-intensity monochromatic light flashes and the associated transmittance change at 810nm. The 810-nm signal change was calibrated based on the number of electrons generated by PSII during the flash (4·O2 evolution) which arrived at the PSI donor side after a delay of 2ms. The intrinsic quantum yield of PSI (yI, electrons per photon absorbed by PSI) was measured at 712nm, where photon absorption by PSII was small. The results were used to resolve the individual spectra of the excitation partitioning coefficients between PSI (aI) and PSII (aII) in leaves. For comparison, pigment-protein complexes for PSII and PSI were isolated, separated by sucrose density ultracentrifugation, and their optical density was measured. A good correlation was obtained for the spectral excitation partitioning coefficients measured by these different methods. The intrinsic yield of PSI was high (yI=0.88), but it absorbed only about 1/3 of quanta; consequently, about 2/3 of quanta were absorbed by PSII, but processed with the low intrinsic yield yII=0.63. In PSII, the quantum yield of charge separation was 0.89 as detected by variable fluorescence Fv/Fm, but 29% of separated charges recombined (Laisk A, Eichelmann H and Oja V, Photosynth. Res. 113, 145-155). At wavelengths less than 580nm about 30% of excitation is absorbed by pigments poorly connected to either photosystem, most likely carotenoids bound in pigment-protein complexes. Copyright © 2013 Elsevier B.V. All rights reserved.

Evaluation of PHI Hunter in Natural Language Processing Research.

PubMed

Redd, Andrew; Pickard, Steve; Meystre, Stephane; Scehnet, Jeffrey; Bolton, Dan; Heavirland, Julia; Weaver, Allison Lynn; Hope, Carol; Garvin, Jennifer Hornung

2015-01-01

We introduce and evaluate a new, easily accessible tool using a common statistical analysis and business analytics software suite, SAS, which can be programmed to remove specific protected health information (PHI) from a text document. Removal of PHI is important because the quantity of text documents used for research with natural language processing (NLP) is increasing. When using existing data for research, an investigator must remove all PHI not needed for the research to comply with human subjects' right to privacy. This process is similar, but not identical, to de-identification of a given set of documents. PHI Hunter removes PHI from free-form text. It is a set of rules to identify and remove patterns in text. PHI Hunter was applied to 473 Department of Veterans Affairs (VA) text documents randomly drawn from a research corpus stored as unstructured text in VA files. PHI Hunter performed well with PHI in the form of identification numbers such as Social Security numbers, phone numbers, and medical record numbers. The most commonly missed PHI items were names and locations. Incorrect removal of information occurred with text that looked like identification numbers. PHI Hunter fills a niche role that is related to but not equal to the role of de-identification tools. It gives research staff a tool to reasonably increase patient privacy. It performs well for highly sensitive PHI categories that are rarely used in research, but still shows possible areas for improvement. More development for patterns of text and linked demographic tables from electronic health records (EHRs) would improve the program so that more precise identifiable information can be removed. PHI Hunter is an accessible tool that can flexibly remove PHI not needed for research. If it can be tailored to the specific data set via linked demographic tables, its performance will improve in each new document set.

Contribution of elevated intracellular calcium to pulmonary arterial myocyte alkalinization during chronic hypoxia

PubMed Central

Luke, Trevor; Shimoda, Larissa A.

2016-01-01

Abstract In the lung, exposure to chronic hypoxia (CH) causes pulmonary hypertension, a debilitating disease. Development of this condition arises from increased muscularity and contraction of pulmonary vessels, associated with increases in pulmonary arterial smooth muscle cell (PASMC) intracellular pH (pHi) and Ca2+ concentration ([Ca2+]i). In this study, we explored the interaction between pHi and [Ca2+]i in PASMCs from rats exposed to normoxia or CH (3 weeks, 10% O2). PASMC pHi and [Ca2+]i were measured with fluorescent microscopy and the dyes BCECF and Fura-2. Both pHi and [Ca2+]i levels were elevated in PASMCs from hypoxic rats. Exposure to KCl increased [Ca2+]i and pHi to a similar extent in normoxic and hypoxic PASMCs. Conversely, removal of extracellular Ca2+ or blockade of Ca2+ entry with NiCl2 or SKF 96365 decreased [Ca2+]i and pHi only in hypoxic cells. Neither increasing pHi with NH4Cl nor decreasing pHi by removal of bicarbonate impacted PASMC [Ca2+]i. We also examined the roles of Na+/Ca2+ exchange (NCX) and Na+/H+ exchange (NHE) in mediating the elevated basal [Ca2+]i and Ca2+-dependent changes in PASMC pHi. Bepridil, dichlorobenzamil, and KB-R7943, which are NCX inhibitors, decreased resting [Ca2+]i and pHi only in hypoxic PASMCs and blocked the changes in pHi induced by altering [Ca2+]i. Exposure to ethyl isopropyl amiloride, an NHE inhibitor, decreased resting pHi and prevented changes in pHi due to changing [Ca2+]i. Our findings indicate that, during CH, the elevation in basal [Ca2+]i may contribute to the alkaline shift in pHi in PASMCs, likely via mechanisms involving reverse-mode NCX and NHE. PMID:27076907

Clinical utility of the Prostate Health Index (phi) for biopsy decision management in a large group urology practice setting.

PubMed

White, Jay; Shenoy, B Vittal; Tutrone, Ronald F; Karsh, Lawrence I; Saltzstein, Daniel R; Harmon, William J; Broyles, Dennis L; Roddy, Tamra E; Lofaro, Lori R; Paoli, Carly J; Denham, Dwight; Reynolds, Mark A

2018-04-01

Deciding when to biopsy a man with non-suspicious DRE findings and tPSA in the 4-10 ng/ml range can be challenging, because two-thirds of such biopsies are typically found to be benign. The Prostate Health Index (phi) exhibits significantly improved diagnostic accuracy for prostate cancer detection when compared to tPSA and %fPSA, however only one published study to date has investigated its impact on biopsy decisions in clinical practice. An IRB approved observational study was conducted at four large urology group practices using a physician reported two-part questionnaire. Physician recommendations were recorded before and after receiving the phi test result. A historical control group was queried from each site's electronic medical records for eligible men who were seen by the same participating urologists prior to the implementation of the phi test in their practice. 506 men receiving a phi test were prospectively enrolled and 683 men were identified for the historical control group (without phi). Biopsy and pathological findings were also recorded for both groups. Men receiving a phi test showed a significant reduction in biopsy procedures performed when compared to the historical control group (36.4% vs. 60.3%, respectively, P < 0.0001). Based on questionnaire responses, the phi score impacted the physician's patient management plan in 73% of cases, including biopsy deferrals when the phi score was low, and decisions to perform biopsies when the phi score indicated an intermediate or high probability of prostate cancer (phi ≥36). phi testing significantly impacted the physician's biopsy decision for men with tPSA in the 4-10 ng/ml range and non-suspicious DRE findings. Appropriate utilization of phi resulted in a significant reduction in biopsy procedures performed compared to historical patients seen by the same participating urologists who would have met enrollment eligibility but did not receive a phi test.

Evaluation of PHI Hunter in Natural Language Processing Research

PubMed Central

Redd, Andrew; Pickard, Steve; Meystre, Stephane; Scehnet, Jeffrey; Bolton, Dan; Heavirland, Julia; Weaver, Allison Lynn; Hope, Carol; Garvin, Jennifer Hornung

2015-01-01

Objectives We introduce and evaluate a new, easily accessible tool using a common statistical analysis and business analytics software suite, SAS, which can be programmed to remove specific protected health information (PHI) from a text document. Removal of PHI is important because the quantity of text documents used for research with natural language processing (NLP) is increasing. When using existing data for research, an investigator must remove all PHI not needed for the research to comply with human subjects’ right to privacy. This process is similar, but not identical, to de-identification of a given set of documents. Materials and methods PHI Hunter removes PHI from free-form text. It is a set of rules to identify and remove patterns in text. PHI Hunter was applied to 473 Department of Veterans Affairs (VA) text documents randomly drawn from a research corpus stored as unstructured text in VA files. Results PHI Hunter performed well with PHI in the form of identification numbers such as Social Security numbers, phone numbers, and medical record numbers. The most commonly missed PHI items were names and locations. Incorrect removal of information occurred with text that looked like identification numbers. Discussion PHI Hunter fills a niche role that is related to but not equal to the role of de-identification tools. It gives research staff a tool to reasonably increase patient privacy. It performs well for highly sensitive PHI categories that are rarely used in research, but still shows possible areas for improvement. More development for patterns of text and linked demographic tables from electronic health records (EHRs) would improve the program so that more precise identifiable information can be removed. Conclusions PHI Hunter is an accessible tool that can flexibly remove PHI not needed for research. If it can be tailored to the specific data set via linked demographic tables, its performance will improve in each new document set. PMID:26807078

Nuclear phytochrome A signaling promotes phototropism in Arabidopsis.

PubMed

Kami, Chitose; Hersch, Micha; Trevisan, Martine; Genoud, Thierry; Hiltbrunner, Andreas; Bergmann, Sven; Fankhauser, Christian

2012-02-01

Phototropin photoreceptors (phot1 and phot2 in Arabidopsis thaliana) enable responses to directional light cues (e.g., positive phototropism in the hypocotyl). In Arabidopsis, phot1 is essential for phototropism in response to low light, a response that is also modulated by phytochrome A (phyA), representing a classical example of photoreceptor coaction. The molecular mechanisms underlying promotion of phototropism by phyA remain unclear. Most phyA responses require nuclear accumulation of the photoreceptor, but interestingly, it has been proposed that cytosolic phyA promotes phototropism. By comparing the kinetics of phototropism in seedlings with different subcellular localizations of phyA, we show that nuclear phyA accelerates the phototropic response, whereas in the fhy1 fhl mutant, in which phyA remains in the cytosol, phototropic bending is slower than in the wild type. Consistent with this data, we find that transcription factors needed for full phyA responses are needed for normal phototropism. Moreover, we show that phyA is the primary photoreceptor promoting the expression of phototropism regulators in low light (e.g., PHYTOCHROME KINASE SUBSTRATE1 [PKS1] and ROOT PHOTO TROPISM2 [RPT2]). Although phyA remains cytosolic in fhy1 fhl, induction of PKS1 and RPT2 expression still occurs in fhy1 fhl, indicating that a low level of nuclear phyA signaling is still present in fhy1 fhl.

Nuclear Phytochrome A Signaling Promotes Phototropism in Arabidopsis[W][OA

PubMed Central

Kami, Chitose; Hersch, Micha; Trevisan, Martine; Genoud, Thierry; Hiltbrunner, Andreas; Bergmann, Sven; Fankhauser, Christian

2012-01-01

Phototropin photoreceptors (phot1 and phot2 in Arabidopsis thaliana) enable responses to directional light cues (e.g., positive phototropism in the hypocotyl). In Arabidopsis, phot1 is essential for phototropism in response to low light, a response that is also modulated by phytochrome A (phyA), representing a classical example of photoreceptor coaction. The molecular mechanisms underlying promotion of phototropism by phyA remain unclear. Most phyA responses require nuclear accumulation of the photoreceptor, but interestingly, it has been proposed that cytosolic phyA promotes phototropism. By comparing the kinetics of phototropism in seedlings with different subcellular localizations of phyA, we show that nuclear phyA accelerates the phototropic response, whereas in the fhy1 fhl mutant, in which phyA remains in the cytosol, phototropic bending is slower than in the wild type. Consistent with this data, we find that transcription factors needed for full phyA responses are needed for normal phototropism. Moreover, we show that phyA is the primary photoreceptor promoting the expression of phototropism regulators in low light (e.g., PHYTOCHROME KINASE SUBSTRATE1 [PKS1] and ROOT PHOTO TROPISM2 [RPT2]). Although phyA remains cytosolic in fhy1 fhl, induction of PKS1 and RPT2 expression still occurs in fhy1 fhl, indicating that a low level of nuclear phyA signaling is still present in fhy1 fhl. PMID:22374392

ABSORBANCE, ABSORPTION COEFFICIENT, AND APPARENT QUANTUM YIELD: A COMMENT ON AMBIGUITY IN THE USE OF THESE OPTICAL CONCEPTS

EPA Science Inventory

Several important optical terms such as "absorbance" and "absorption coefficient" are frequently used ambiguously in the current peer-reviewed literature. Since they are important terms that are required to derive other quantities such as the "apparent quantum yield" of photoprod...

How does gravity save or kill Q-balls?

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

Tamaki, Takashi; Sakai, Nobuyuki; Department of Education, Yamagata University, Yamagata 990-8560

2011-02-15

We explore stability of gravitating Q-balls with potential V{sub 4}({phi})=(m{sup 2}/2){phi}{sup 2}-{lambda}{phi}{sup 4}+({phi}{sup 6}/M{sup 2}) via catastrophe theory, as an extension of our previous work on Q-balls with potential V{sub 3}({phi})=(m{sup 2}/2){phi}{sup 2}-{mu}{phi}{sup 3}+{lambda}{phi}{sup 4}. In flat spacetime Q-balls with V{sub 4} in the thick-wall limit are unstable and there is a minimum charge Q{sub min}, where Q-balls with Q

Experimental studies of the near threshold production of K{sup +}K{sup -} pairs at COSY-11

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

Gil, Damian; Smyrski, Jerzy

2007-11-07

This paper sums up experimental studies of the near threshold production of K{sup +}K{sup -} pairs at COSY-11. The total cross section of the reaction pp{yields}ppK{sup +}K{sup -} has been measured at five excess energies below the {phi} production threshold with the magnetic spectrometer COSY-11. The new data show a significant enhancement of the total cross section compared to pure phase space expectations.

The effect on reliability and sensitivity to level of training of combining analytic and holistic rating scales for assessing communication skills in an internal medicine resident OSCE.

PubMed

Daniels, Vijay John; Harley, Dwight

2017-07-01

Although previous research has compared checklists to rating scales for assessing communication, the purpose of this study was to compare the effect on reliability and sensitivity to level of training of an analytic, a holistic, and a combined analytic-holistic rating scale in assessing communication skills. The University of Alberta Internal Medicine Residency runs OSCEs for postgraduate year (PGY) 1 and 2 residents and another for PGY-4 residents. Communication stations were scored with an analytic scale (empathy, non-verbal skills, verbal skills, and coherence subscales) and a holistic scale. Authors analyzed reliability of individual and combined scales using generalizability theory and evaluated each scale's sensitivity to level of training. For analytic, holistic, and combined scales, 12, 12, and 11 stations respectively yielded a Phi of 0.8 for the PGY-1,2 cohort, and 16, 16, and 14 stations yielded a Phi of 0.8 for the PGY-4 cohort. PGY-4 residents scored higher on the combined scale, the analytic rating scale, and the non-verbal and coherence subscales. A combined analytic-holistic rating scale increased score reliability and was sensitive to level of training. Given increased validity evidence, OSCE developers should consider combining analytic and holistic scales when assessing communication skills. Copyright © 2017 Elsevier B.V. All rights reserved.

Estimation of the use of pesticides and their potential environmental impacts in Hipólito Yrigoyen, Buenos Aires, Argentina

NASA Astrophysics Data System (ADS)

Gonzalo Mayoral, Eliana; Nuñez, Mariana

2017-04-01

The process of agriculturalisation in the Pampean Region of Argentina revealed not only a significant advance of agriculture on medium to low-end land, but also the adoption of certain cultural practices, including the use of pesticides. In this sense, this research aims to know the estimated use of herbicides in the Hipólito Yrigoyen District (PHY) during the agricultural campaign 2015/16 and the potential environmental impacts resulting from the society / nature relationships identified from ecological zoning of the same. The Ecological Zoning (ZE) of the PHY (166.300 ha) at a scale of 1:500.000 allowed to identify 3 Morphological Units (UM) and 6 Morpho-phytopedic Units (UMFE), which were evaluated according to their ecological rural suitability. This evaluation indicates that 34,46% of the PHY shows aptitude from regular to good for annual crop yield, while 65,54% of the remaining area has regular or good aptitude for livestock use of cultivated forage (46,21%) and native plants (19,33%). However, despite PHY's livestock-agricultural aptitude, the evolution of current land use indicates that since 1988 and especially in 2002, only agricultural activities have led land use, focusing on the production of a few crops. In fact, in the 2015/16 crop year, 92.900 ha were sown mainly with soybean (59,2%) and maize (19,38%), and to a lesser extent with oats, barley, wheat, sunflower and sorghum (21,42%). The estimation of the use of agrochemicals according to the productive approach identified in the Inland Pampa, allows to affirm that within the group of herbicides, the most used in the 2015/16 campaign in PHY was glyphosate (364.500 l), followed by atrazine (72.800 l), 2,4-D (48.550 l) and Metsulfuron-methyl (532.000 g). According to the above, in relation to the production modality and the estimation of the use of herbicides in the last agricultural season, the analysis of the society-nature relations in the PHY reveals the potential environmental impacts derived from this activity. In general terms, potentially impacted environmental factors include soil, vegetation, fauna, ecosystems, water and society, and within the identified impacts, the proliferation of agrochemical resistant weeds, the simplification and homogenization of ecosystems, the genetic erosion and loss of variability, the reduction of surface and ground water quality, and the health risks of workers and the nearby population, are directly associated with the use of agrochemicals.

Interaction between physostigmine and soman on brain regional cholinesterase activity and /sup 3/H-physostigmine distribution

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

Hallak, M.E.; Woodruff, E.; Giacobini, E.

1986-03-05

Physostigmine (Phy) concentrations (as radioactivity) were studied in various brain areas after /sup 3/H-Phy administration as a function of time. Five min after 500 ..mu..g/kg i.m., cortex (CX) and total brain showed similar concentrations (370 ng/g) which were 50-90% higher than those of other brain regions (striatum, hippocampus, and medulla oblongata). Soman did not affect Phy levels in whole brain after pretreatment with Phy (100 or 500 ..mu..g/kg), however, the regional distribution of Phy was altered by soman as was ChE inhibition. A significant increase in Phy concentration was seen in HC (22 and 45% at 5 and 30 min,more » respectively) and CX (21% at 30 min). ChE activity in total brain was 12, 30, and 24% (5, 15 and 30 min after soman administration) lower than after Phy alone. If the pretreatment dose of Phy was increased to 500 ..mu..g/kg /sup 3/H-Phy, ChE activity was further reduced to 4, 13 and 19%. This might indicate that higher doses of Phy provide more protection of the enzyme from soman than lower doses. The protective role of Phy seen in total brain was not consistent for all brain regions. Soman alone produced a 95% ChE inhibition and there were no differences in its effect between total brain or brain areas. Pretreatment of the rat with Phy produced a protective effect upon ChE activity up to 30 min. However, no protective effect on survival was observed.« less

Phytochromes play a role in phototropism and gravitropism in Arabidopsis roots.

PubMed

Correll, Melanie J; Coveney, Katrina M; Raines, Steven V; Mullen, Jack L; Hangarter, Roger P; Kiss, John Z

2003-01-01

Phototropism as well as gravitropism plays a role in the oriented growth of roots in flowering plants. In blue or white light, roots exhibit negative phototropism, but red light induces positive phototropism in Arabidopsis roots. Phytochrome A (phyA) and phyB mediate the positive red-light-based photoresponse in roots since single mutants (and the double phyAB mutant) were severely impaired in this response. In blue-light-based negative phototropism, phyA and phyAB (but not phyB) were inhibited in the response relative to the WT. In root gravitropism, phyB and phyAB (but not phyA) were inhibited in the response compared to the WT. The differences observed in tropistic responses were not due to growth limitations since the growth rates among all the mutants tested were not significantly different from that of the WT. Thus, our study shows that the blue-light and red-light systems interact in roots and that phytochrome plays a key role in plant development by integrating multiple environmental stimuli. c2003 COSPAR. Published by Elsevier Ltd. All rights reserved.

Phytochromes play a role in phototropism and gravitropism in Arabidopsis roots

NASA Technical Reports Server (NTRS)

Correll, Melanie J.; Coveney, Katrina M.; Raines, Steven V.; Mullen, Jack L.; Hangarter, Roger P.; Kiss, John Z.

2003-01-01

Phototropism as well as gravitropism plays a role in the oriented growth of roots in flowering plants. In blue or white light, roots exhibit negative phototropism, but red light induces positive phototropism in Arabidopsis roots. Phytochrome A (phyA) and phyB mediate the positive red-light-based photoresponse in roots since single mutants (and the double phyAB mutant) were severely impaired in this response. In blue-light-based negative phototropism, phyA and phyAB (but not phyB) were inhibited in the response relative to the WT. In root gravitropism, phyB and phyAB (but not phyA) were inhibited in the response compared to the WT. The differences observed in tropistic responses were not due to growth limitations since the growth rates among all the mutants tested were not significantly different from that of the WT. Thus, our study shows that the blue-light and red-light systems interact in roots and that phytochrome plays a key role in plant development by integrating multiple environmental stimuli. c2003 COSPAR. Published by Elsevier Ltd. All rights reserved.

Sequential and coordinated action of phytochromes A and B during Arabidopsis stem growth revealed by kinetic analysis

NASA Technical Reports Server (NTRS)

Parks, B. M.; Spalding, E. P.; Evans, M. L. (Principal Investigator)

1999-01-01

Photoreceptor proteins of the phytochrome family mediate light-induced inhibition of stem (hypocotyl) elongation during the development of photoautotrophy in seedlings. Analyses of overt mutant phenotypes have established the importance of phytochromes A and B (phyA and phyB) in this developmental process, but kinetic information that would augment emerging molecular models of phytochrome signal transduction is absent. We have addressed this deficiency by genetically dissecting phytochrome-response kinetics, after having solved the technical issues that previously limited growth studies of small Arabidopsis seedlings. We show here, with resolution on the order of minutes, that phyA initiated hypocotyl growth inhibition upon the onset of continuous red light. This primary contribution of phyA began to decrease after 3 hr of irradiation, the same time at which immunochemically detectable phyA disappeared and an exclusively phyB-dependent phase of inhibition began. The sequential and coordinated actions of phyA and phyB in red light were not observed in far-red light, which inhibited growth persistently through an exclusively phyA-mediated pathway.

Intracellular pH Regulation in Cultured Astrocytes from Rat Hippocampus

PubMed Central

Bevensee, Mark O.; Weed, Regina A.; Boron, Walter F.

1997-01-01

We studied the regulation of intracellular pH (pHi) in single cultured astrocytes passaged once from the hippocampus of the rat, using the dye 2′,7′-biscarboxyethyl-5,6-carboxyfluorescein (BCECF) to monitor pHi. Intrinsic buffering power (βI) was 10.5 mM (pH unit)−1 at pHi 7.0, and decreased linearly with pHi; the best-fit line to the data had a slope of −10.0 mM (pH unit)−2. In the absence of HCO3 −, pHi recovery from an acid load was mediated predominantly by a Na-H exchanger because the recovery was inhibited 88% by amiloride and 79% by ethylisopropylamiloride (EIPA) at pHi 6.05. The ethylisopropylamiloride-sensitive component of acid extrusion fell linearly with pHi. Acid extrusion was inhibited 68% (pHi 6.23) by substituting Li+ for Na+ in the bath solution. Switching from a CO2/HCO3 −-free to a CO2/HCO3 −-containing bath solution caused mean steady state pHi to increase from 6.82 to 6.90, due to a Na+-driven HCO3 − transporter. The HCO3 −-induced pHi increase was unaffected by amiloride, but was inhibited 75% (pHi 6.85) by 400 μM 4,4′-diisothiocyanatostilbene-2,2′-disulfonic acid (DIDS), and 65% (pHi 6.55–6.75) by pretreating astrocytes for up to ∼6.3 h with 400 μM 4-acetamide-4′-isothiocyanatostilbene-2,2′-disulfonic acid (SITS). The CO2/HCO3 −-induced pHi increase was blocked when external Na+ was replaced with N-methyl-d-glucammonium (NMDG+). In the presence of HCO3 −, the Na+-driven HCO3 − transporter contributed to the pHi recovery from an acid load. For example, HCO3 − shifted the plot of acid-extrusion rate vs. pHi by 0.15–0.3 pH units in the alkaline direction. Also, with Na-H exchange inhibited by amiloride, HCO3 − increased acid extrusion 3.8-fold (pHi 6.20). When astrocytes were acid loaded in amiloride, with Li+ as the major cation, HCO3 − failed to elicit a substantial increase in pHi. Thus, Li+ does not appear to substitute well for Na+ on the HCO3 − transporter. We conclude that an amiloride-sensitive Na-H exchanger and a Na+-driven HCO3 − transporter are the predominant acid extruders in astrocytes. PMID:9379175

76 FR 63342 - Petition for Exemption; Summary of Petition Received

Federal Register 2010, 2011, 2012, 2013, 2014

2011-10-12

...-1039. Petitioner: PHI, Inc. Section of 14 CFR Affected: Sec. 91.9(a). Description of Relief Sought: PHI, Inc. (PHI), requests an exemption from 91.9(a) to allow PHI to operate S-92A helicopters in accordance...

Quantum Criticality and Black Holes

ScienceCinema

Sachdev, Subir [Harvard University, Cambridge, Massachusetts, United States

2017-12-09

I will describe the behavior of a variety of condensed matter systems in the vicinity of zero temperature quantum phase transitions. There is a remarkable analogy between the hydrodynamics of such systems and the quantum theory of black holes. I will show how insights from this analogy have shed light on recent experiments on the cuprate high temperature superconductors. Studies of new materials and trapped ultracold atoms are yielding new quantum phases, with novel forms of quantum entanglement. Some materials are of technological importance: e.g. high temperature superconductors. Exact solutions via black hole mapping have yielded first exact results for transport coefficients in interacting many-body systems, and were valuable in determining general structure of hydrodynamics. Theory of VBS order and Nernst effect in cuprates. Tabletop 'laboratories for the entire universe': quantum mechanics of black holes, quark-gluon plasma, neutrons stars, and big-bang physics.

Brightly Luminescent and Color-Tunable Colloidal CH3NH3PbX3 (X = Br, I, Cl) Quantum Dots: Potential Alternatives for Display Technology.

PubMed

Zhang, Feng; Zhong, Haizheng; Chen, Cheng; Wu, Xian-gang; Hu, Xiangmin; Huang, Hailong; Han, Junbo; Zou, Bingsuo; Dong, Yuping

2015-04-28

Organometal halide perovskites are inexpensive materials with desirable characteristics of color-tunable and narrow-band emissions for lighting and display technology, but they suffer from low photoluminescence quantum yields at low excitation fluencies. Here we developed a ligand-assisted reprecipitation strategy to fabricate brightly luminescent and color-tunable colloidal CH3NH3PbX3 (X = Br, I, Cl) quantum dots with absolute quantum yield up to 70% at room temperature and low excitation fluencies. To illustrate the photoluminescence enhancements in these quantum dots, we conducted comprehensive composition and surface characterizations and determined the time- and temperature-dependent photoluminescence spectra. Comparisons between small-sized CH3NH3PbBr3 quantum dots (average diameter 3.3 nm) and corresponding micrometer-sized bulk particles (2-8 μm) suggest that the intense increased photoluminescence quantum yield originates from the increase of exciton binding energy due to size reduction as well as proper chemical passivations of the Br-rich surface. We further demonstrated wide-color gamut white-light-emitting diodes using green emissive CH3NH3PbBr3 quantum dots and red emissive K2SiF6:Mn(4+) as color converters, providing enhanced color quality for display technology. Moreover, colloidal CH3NH3PbX3 quantum dots are expected to exhibit interesting nanoscale excitonic properties and also have other potential applications in lasers, electroluminescence devices, and optical sensors.

Structural Basis for Near Unity Quantum Yield Core/Shell Nanostructures

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

McBride, James; Treadway, Joe; Pennycook, Stephen J

2006-01-01

Aberration-corrected Z-contrast scanning transmission electron microscopy of core/shell nanocrystals shows clear correlations between structure and quantum efficiency. Uniform shell coverage is obtained only for a graded CdS/ZnS shell material and is found to be critical to achieving near 100% quantum yield. The sublattice sensitivity of the images confirms that preferential growth takes place on the anion-terminated surfaces. This explains the three-dimensional "nanobullet" shape observed in the case of core/shell nanorods.

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

Chen Lin; Chen Yixin

We show that no universal quantum cloning machine exists that can broadcast an arbitrary mixed qubit with a constant fidelity. Based on this result, we investigate the dependent quantum cloner in the sense that some parameter of the input qubit {rho}{sub s}({theta},{omega},{lambda}) is regarded as constant in the fidelity. For the case of constant {omega}, we establish the 1{yields}2 optimal symmetric dependent cloner with a fidelity 1/2. It is also shown that the 1{yields}M optimal quantum cloning machine for pure qubits is also optimal for mixed qubits, when {lambda} is the unique parameter in the fidelity. For general N{yields}M broadcastingmore » of mixed qubits, the situation is very different.« less

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

Bisio, Alessandro; D'Ariano, Giacomo Mauro; Perinotti, Paolo

We analyze quantum algorithms for cloning of a quantum measurement. Our aim is to mimic two uses of a device performing an unknown von Neumann measurement with a single use of the device. When the unknown device has to be used before the bipartite state to be measured is available we talk about 1{yields}2 learning of the measurement, otherwise the task is called 1{yields}2 cloning of a measurement. We perform the optimization for both learning and cloning for arbitrary dimension d of the Hilbert space. For 1{yields}2 cloning we also propose a simple quantum network that achieves the optimal fidelity.more » The optimal fidelity for 1{yields}2 learning just slightly outperforms the estimate and prepare strategy in which one first estimates the unknown measurement and depending on the result suitably prepares the duplicate.« less

Intracellular pH change does not accompany egg activation in the mouse.

PubMed

Phillips, K P; Baltz, J M

1996-09-01

In the sea urchin, some other marine invertebrates, and the frog, Xenopus, egg activation at fertilization is accompanied by an increase in intracellular pH (pHi). We measured pHi in germinal vesicle (GV)-intact mouse oocytes, ovulated eggs, and in vivo fertilized zygotes using the pH indicator dye, SNARF-1. The mean pH, was 6.96 +/- 0.004 (+/- SEM) in GV-intact oocytes, 7.00 +/- 0.01 in ovulated, unfertilized eggs, and 7.02 +/- 0.01 in fertilized zygotes, indicating no sustained changes in pHi after germinal vesicle breakdown (GVBD) or fertilization. To examine whether transient changes in pHi occur shortly after egg activation, mouse eggs were parthenogenetically activated by 7% ethanol in phosphate buffered saline (PBS); no significant change in pHi followed ethanol activation. Since increased Na+/H+ antiporter activity is responsible for pHi increase in the sea urchin, pHi was measured in the absence of added bicarbonate or CO2 (a condition under which the antiporter would be the only major pHi regulatory mechanism able to operate, since the others were bicarbonate-dependent) in GV-intact oocytes, ovulated eggs, and in vivo fertilized zygotes to determine whether a Na+/H+ antiporter was activated. There was no physiologically significant difference in pHi after GVBD or fertilization, when pHi was measured in bicarbonate-free medium, nor any change upon parthenogenetic activation. Thus, a change in pHi is not a feature of egg activation in the mouse.

Influence of quantum dot's quantum yield to chemiluminescent resonance energy transfer.

PubMed

Wang, Hai-Qiao; Li, Yong-Qiang; Wang, Jian-Hao; Xu, Qiao; Li, Xiu-Qing; Zhao, Yuan-Di

2008-03-03

The resonance energy transfer between chemiluminescence donor (luminol-H2O2 system) and quantum dots (QDs, emission at 593 nm) acceptors (CRET) was investigated. The resonance energy transfer efficiencies were compared while the oil soluble QDs, water soluble QDs (modified with thioglycolate) and QD-HRP conjugates were used as acceptor. The fluorescence of QD can be observed in the three cases, indicating that the CRET occurs while QD acceptor in different status was used. The highest CRET efficiency (10.7%) was obtained in the case of oil soluble QDs, and the lowest CRET efficiency (2.7%) was observed in the QD-HRP conjugates case. This result is coincident with the quantum yields of the acceptors (18.3% and 0.4%). The same result was observed in another similar set of experiment, in which the amphiphilic polymer modified QDs (emission at 675 nm) were used. It suggests that the quantum yield of the QD in different status is the crucial factor to the CRET efficiency. Furthermore, the multiplexed CRET between luminol donor and three different sizes QD acceptors was observed simultaneously. This work will offer useful support for improving the CRET studies based on quantum dots.

[Application study on PHI and 16PF and SCL-90 for freshman's psychology inspection].

PubMed

Niu, Peng

2009-07-01

To explore the effect of application of the measurement table of PHI and 16PF and SCL-90 for freshmen psychology inspection. The measurement tables of PHI and 16PF for psychology inspection of freshmen of 2004-2007 years were used to sift crisis intervention objects. Continuous four years test showed certain stability, in addition to excited factors,the scores of Freshmen's PHI factors were more lower than normal. The incidence rates of mental problems screened by PHI table were very low and 3-5 serious-mental-problem students weren't detected. The problem can be resolved by the application of PHI combined with 16PF through remesuring the suspected cases by SCL-90. The combinative application of PHI, 16PF and SCL-90 would be better.

Triazatruxene: A Rigid Central Donor Unit for a D-A3 Thermally Activated Delayed Fluorescence Material Exhibiting Sub-Microsecond Reverse Intersystem Crossing and Unity Quantum Yield via Multiple Singlet-Triplet State Pairs.

PubMed

Dos Santos, Paloma L; Ward, Jonathan S; Congrave, Daniel G; Batsanov, Andrei S; Eng, Julien; Stacey, Jessica E; Penfold, Thomas J; Monkman, Andrew P; Bryce, Martin R

2018-06-01

By inverting the common structural motif of thermally activated delayed fluorescence materials to a rigid donor core and multiple peripheral acceptors, reverse intersystem crossing (rISC) rates are demonstrated in an organic material that enables utilization of triplet excited states at faster rates than Ir-based phosphorescent materials. A combination of the inverted structure and multiple donor-acceptor interactions yields up to 30 vibronically coupled singlet and triplet states within 0.2 eV that are involved in rISC. This gives a significant enhancement to the rISC rate, leading to delayed fluorescence decay times as low as 103.9 ns. This new material also has an emission quantum yield ≈1 and a very small singlet-triplet gap. This work shows that it is possible to achieve both high photoluminescence quantum yield and fast rISC in the same molecule. Green organic light-emitting diode devices with external quantum efficiency >30% are demonstrated at 76 cd m -2 .

The Effect of Correlated Energetic Disorder on Charge Transport in Organic Semiconductors

NASA Astrophysics Data System (ADS)

Allen, Jonathan; Röding, Sebastian; Cherqui, Charles; Dunlap, David

2012-10-01

In their 1995 paper describing a Monte Carlo simulation for dissociation of an electron-hole pair in the presence of Gaussian energetic disorder, Albrect and Bäassler reported a surprising result. They found that increasing the width σ of the energetic disorder increases the quantum yield φ. They attributed this behavior to the tendency for energy fluctuations to compete against the Coulombic pair attraction, driving the electron-hole pair apart at short distances where, without disorder, recombination would be almost certain. We have expanded upon this notion, and introduced spatial correlation into the energetic disorder. By correlating the energetic disorder, we have demonstrated even larger quantum yields in simulation, attributable to the tendency of correlation to drive the charges further apart spatially than merely random disorder. Our results generally support the findings of Greenham et al. in that a larger correlation radius gives a larger quantum yield. In addition to larger quantum yield, we believe that correlated disorder could be used to create pathways for charge transport within a material, allowing the charge carrier behavior to be tuned.

Tailoring the Energy Landscape in Quasi-2D Halide Perovskites Enables Efficient Green-Light Emission.

PubMed

Quan, Li Na; Zhao, Yongbiao; García de Arquer, F Pelayo; Sabatini, Randy; Walters, Grant; Voznyy, Oleksandr; Comin, Riccardo; Li, Yiying; Fan, James Z; Tan, Hairen; Pan, Jun; Yuan, Mingjian; Bakr, Osman M; Lu, Zhenghong; Kim, Dong Ha; Sargent, Edward H

2017-06-14

Organo-metal halide perovskites are a promising platform for optoelectronic applications in view of their excellent charge-transport and bandgap tunability. However, their low photoluminescence quantum efficiencies, especially in low-excitation regimes, limit their efficiency for light emission. Consequently, perovskite light-emitting devices are operated under high injection, a regime under which the materials have so far been unstable. Here we show that, by concentrating photoexcited states into a small subpopulation of radiative domains, one can achieve a high quantum yield, even at low excitation intensities. We tailor the composition of quasi-2D perovskites to direct the energy transfer into the lowest-bandgap minority phase and to do so faster than it is lost to nonradiative centers. The new material exhibits 60% photoluminescence quantum yield at excitation intensities as low as 1.8 mW/cm 2 , yielding a ratio of quantum yield to excitation intensity of 0.3 cm 2 /mW; this represents a decrease of 2 orders of magnitude in the excitation power required to reach high efficiency compared with the best prior reports. Using this strategy, we report light-emitting diodes with external quantum efficiencies of 7.4% and a high luminescence of 8400 cd/m 2 .

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

Saunders, Will; Smedley, Scott; Gillingham, Peter

We present Simulated Annealing fiber-to-target allocation simulations for the proposed DESI and 4MOST massively multiplexed spectroscopic surveys, and for both Poisson and realistically clustered mock target samples. We simulate both Echidna and theta-phi actuator designs, including the restrictions caused by the physical actuator characteristics during repositioning. For DESI, with theta-phi actuators, used in 5 passes over the sky for a mock ELG/LRG/QSO sample, with matched fiber and target densities, a total target allocation yield of 89.3% was achieved, but only 83.7% for the high-priority Ly-alpha QSOs. If Echidna actuators are used with the same pitch and number of passes, themore » yield increases by 5.7% and 16% respectively. Echidna also allows a factor-of-two increase in the number of close Ly-alpha QSO pairs that can be observed. Echidna spine tilt causes a variable loss of throughput, with average loss being the same as the loss at the rms tilt. With a natural tilt minimization scheme, we find an rms tilt always close to 0.58 x maximum. There is an additional but much smaller defocus loss, equivalent to an average defocus of 30microns. These tilt losses offset the gains in yield for Echidna, but because the survey strategy is driven by the higher priority targets, a clear survey speed advantage remains. For 4MOST, high and low latitude sample mock catalogs were supplied by the 4MOST team, and allocations were carried out with the proposed Echidna-based positioner geometry. At high latitudes, the resulting target completeness was 85.3% for LR targets and 78.9% for HR targets. At low latitude, the target completeness was 93.9% for LR targets and 71.2% for HR targets.« less

Molecular characterization of a genomic region in a Lactococcus bacteriophage that is involved in its sensitivity to the phage defense mechanism AbiA.

PubMed

Dinsmore, P K; Klaenhammer, T R

1997-05-01

A spontaneous mutant of the lactococcal phage phi31 that is insensitive to the phage defense mechanism AbiA was characterized in an effort to identify the phage factor(s) involved in sensitivity of phi31 to AbiA. A point mutation was localized in the genome of the AbiA-insensitive phage (phi31A) by heteroduplex analysis of a 9-kb region. The mutation (G to T) was within a 738-bp open reading frame (ORF245) and resulted in an arginine-to-leucine change in the predicted amino acid sequence of the protein. The mutant phi31A-ORF245 reduced the sensitivity of phi31 to AbiA when present in trans, indicating that the mutation in ORF245 is responsible for the AbiA insensitivity of phi31A. Transcription of ORF245 occurs early in the phage infection cycles of phi31 and phi31A and is unaffected by AbiA. Expansion of the phi31 sequence revealed ORF169 (immediately upstream of ORF245) and ORF71 (which ends 84 bp upstream of ORF169). Two inverted repeats lie within the 84-bp region between ORF71 and ORF169. Sequence analysis of an independently isolated AbiA-insensitive phage, phi31B, identified a mutation (G to A) in one of the inverted repeats. A 118-bp fragment from phi31, encompassing the 84-bp region between ORF71 and ORF169, eliminates AbiA activity against phi31 when present in trans, establishing a relationship between AbiA and this fragment. The study of this region of phage phi31 has identified an open reading frame (ORF245) and a 118-bp DNA fragment that interact with AbiA and are likely to be involved in the sensitivity of this phage to AbiA.

[Improvement of Phi bodies stain and its clinical significance].

PubMed

Gong, Xu-Bo; Lu, Xing-Guo; Yan, Li-Juan; Xiao, Xi-Bin; Wu, Dong; Xu, Gen-Bo; Zhang, Xiao-Hong; Zhao, Xiao-Ying

2009-02-01

The aim of this study was to improve the dyeing method of hydroperoxidase (HPO), to analyze the morphologic features of Phi bodies and to evaluate the clinical application of this method. 128 bone marrow or peripheral blood smears from patients with myeloid and lymphoid malignancies were stained by improved HPO staining. The Phi bodies were observed with detection rate of Phi bodies in different leukemias. 69 acute myeloid leukemia (AML) specimens were chosen randomly, the positive rate and the number of Phi bodies between the improved HPO and POX stain based on the same substrate of 3, 3'diaminobenzidine were compared. The results showed that the shape of bundle-like Phi bodies was variable, long or short. while the nubbly Phi bodies often presented oval and smooth. Club-like Phi bodies were found in M(3). The detection rates of bundle-like Phi bodies in AML M(1)-M(5) were 42.9% (6/14), 83.3% (15/18), 92.0% (23/25), 52.3% (11/21), 33.3% (5/15) respectively, and those of nubbly Phi bodies were 28.6% (4/14), 66.7% (12/18), 11.1% (3/25), 33.3% (7/21), 20.0% (3/15) respectively. The detection rate of bundle-like Phi bodies in M(3) was significantly higher than that in (M(1) + M(2)) or (M(4) + M(5)) groups. The detection rate of nubbly Phi bodies in (M(1) + M(2)) group was higher than that in M(3) group. In conclusion, after improvement of staining method, the HPO stain becomes simple, the detection rate of Phi bodies is higher than that by the previous method, the positive granules are more obvious, and the results become stable. This improved method plays an important role in differentiating AML from ALL, subtyping AML, and evaluating the therapeutic results.

The role and uptake of private health insurance in different health care systems: are there lessons for developing countries?

PubMed

Odeyemi, Isaac Ao; Nixon, John

2013-01-01

Social and national health insurance schemes are being introduced in many developing countries in moving towards universal health care. However, gaps in coverage are common and can only be met by out-of-pocket payments, general taxation, or private health insurance (PHI). This study provides an overview of PHI in different health care systems and discusses factors that affect its uptake and equity. A representative sample of countries was identified (United States, United Kingdom, The Netherlands, France, Australia, and Latvia) that illustrates the principal forms and roles of PHI. Literature describing each country's health care system was used to summarize how PHI is utilized and the factors that affect its uptake and equity. In the United States, PHI is a primary source of funding in conjunction with tax-based programs to support vulnerable groups; in the UK and Latvia, PHI is used in a supplementary role to universal tax-based systems; in France and Latvia, complementary PHI is utilized to cover gaps in public funding; in The Netherlands, PHI is supplementary to statutory private and social health insurance; in Australia, the government incentivizes the uptake of complementary PHI through tax rebates and penalties. The uptake of PHI is influenced by age, income, education, health care system typology, and the incentives or disincentives applied by governments. The effect on equity can either be positive or negative depending on the type of PHI adopted and its role within the wider health care system. PHI has many manifestations depending on the type of health care system used and its role within that system. This study has illustrated its common applications and the factors that affect its uptake and equity in different health care systems. The results are anticipated to be helpful in informing how developing countries may utilize PHI to meet the aim of achieving universal health care.

Density perturbations in general modified gravitational theories

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

De Felice, Antonio; Tsujikawa, Shinji; Mukohyama, Shinji

2010-07-15

We derive the equations of linear cosmological perturbations for the general Lagrangian density f(R,{phi},X)/2+L{sub c}, where R is a Ricci scalar, {phi} is a scalar field, and X=-{partial_derivative}{sup {mu}{phi}{partial_derivative}}{sub {mu}{phi}/}2 is a field kinetic energy. We take into account a nonlinear self-interaction term L{sub c}={xi}({phi}) {open_square}{phi}({partial_derivative}{sup {mu}{phi}{partial_derivative}}{sub {mu}{phi}}) recently studied in the context of ''Galileon'' cosmology, which keeps the field equations at second order. Taking into account a scalar-field mass explicitly, the equations of matter density perturbations and gravitational potentials are obtained under a quasistatic approximation on subhorizon scales. We also derive conditions for the avoidance of ghosts and Laplacianmore » instabilities associated with propagation speeds. Our analysis includes most of modified gravity models of dark energy proposed in literature; and thus it is convenient to test the viability of such models from both theoretical and observational points of view.« less

P2P Watch: Personal Health Information Detection in Peer-to-Peer File-Sharing Networks

PubMed Central

El Emam, Khaled; Arbuckle, Luk; Neri, Emilio; Rose, Sean; Jonker, Elizabeth

2012-01-01

Background Users of peer-to-peer (P2P) file-sharing networks risk the inadvertent disclosure of personal health information (PHI). In addition to potentially causing harm to the affected individuals, this can heighten the risk of data breaches for health information custodians. Automated PHI detection tools that crawl the P2P networks can identify PHI and alert custodians. While there has been previous work on the detection of personal information in electronic health records, there has been a dearth of research on the automated detection of PHI in heterogeneous user files. Objective To build a system that accurately detects PHI in files sent through P2P file-sharing networks. The system, which we call P2P Watch, uses a pipeline of text processing techniques to automatically detect PHI in files exchanged through P2P networks. P2P Watch processes unstructured texts regardless of the file format, document type, and content. Methods We developed P2P Watch to extract and analyze PHI in text files exchanged on P2P networks. We labeled texts as PHI if they contained identifiable information about a person (eg, name and date of birth) and specifics of the person’s health (eg, diagnosis, prescriptions, and medical procedures). We evaluated the system’s performance through its efficiency and effectiveness on 3924 files gathered from three P2P networks. Results P2P Watch successfully processed 3924 P2P files of unknown content. A manual examination of 1578 randomly selected files marked by the system as non-PHI confirmed that these files indeed did not contain PHI, making the false-negative detection rate equal to zero. Of 57 files marked by the system as PHI, all contained both personally identifiable information and health information: 11 files were PHI disclosures, and 46 files contained organizational materials such as unfilled insurance forms, job applications by medical professionals, and essays. Conclusions PHI can be successfully detected in free-form textual files exchanged through P2P networks. Once the files with PHI are detected, affected individuals or data custodians can be alerted to take remedial action. PMID:22776692

P2P watch: personal health information detection in peer-to-peer file-sharing networks.

PubMed

Sokolova, Marina; El Emam, Khaled; Arbuckle, Luk; Neri, Emilio; Rose, Sean; Jonker, Elizabeth

2012-07-09

Users of peer-to-peer (P2P) file-sharing networks risk the inadvertent disclosure of personal health information (PHI). In addition to potentially causing harm to the affected individuals, this can heighten the risk of data breaches for health information custodians. Automated PHI detection tools that crawl the P2P networks can identify PHI and alert custodians. While there has been previous work on the detection of personal information in electronic health records, there has been a dearth of research on the automated detection of PHI in heterogeneous user files. To build a system that accurately detects PHI in files sent through P2P file-sharing networks. The system, which we call P2P Watch, uses a pipeline of text processing techniques to automatically detect PHI in files exchanged through P2P networks. P2P Watch processes unstructured texts regardless of the file format, document type, and content. We developed P2P Watch to extract and analyze PHI in text files exchanged on P2P networks. We labeled texts as PHI if they contained identifiable information about a person (eg, name and date of birth) and specifics of the person's health (eg, diagnosis, prescriptions, and medical procedures). We evaluated the system's performance through its efficiency and effectiveness on 3924 files gathered from three P2P networks. P2P Watch successfully processed 3924 P2P files of unknown content. A manual examination of 1578 randomly selected files marked by the system as non-PHI confirmed that these files indeed did not contain PHI, making the false-negative detection rate equal to zero. Of 57 files marked by the system as PHI, all contained both personally identifiable information and health information: 11 files were PHI disclosures, and 46 files contained organizational materials such as unfilled insurance forms, job applications by medical professionals, and essays. PHI can be successfully detected in free-form textual files exchanged through P2P networks. Once the files with PHI are detected, affected individuals or data custodians can be alerted to take remedial action.

Tonometry revisited: perfusion-related, metabolic, and respiratory components of gastric mucosal acidosis in acute cardiorespiratory failure.

PubMed

Jakob, Stephan M; Parviainen, Ilkka; Ruokonen, Esko; Kogan, Alexander; Takala, Jukka

2008-05-01

Mucosal pH (pHi) is influenced by local perfusion and metabolism (mucosal-arterial pCO2 gradient, DeltapCO2), systemic metabolic acidosis (arterial bicarbonate), and respiration (arterial pCO2). We determined these components of pHi and their relation to outcome during the first 24 h of intensive care. We studied 103 patients with acute respiratory or circulatory failure (age, 63+/-2 [mean+/-SEM]; Acute Physiology and Chronic Health Evaluation II score, 20+/-1; Sequential Organ Failure Assessment score, 8+/-0). pHi, and the effects of bicarbonate and arterial and mucosal pCO2 on pHi, were assessed at admission, 6, and 24 h. pHi was reduced (at admission, 7.27+/-0.01) due to low arterial bicarbonate and increased DeltapCO2. Low pHi (<7.32) at admission (n=58; mortality, 29% vs. 13% in those with pHi>or=7.32 at admission; P=0.061) was associated with an increased DeltapCO2 in 59% of patients (mortality, 47% vs. 4% for patients with low pHi and normal DeltapCO2; P=0.0003). An increased versus normal DeltapCO2, regardless of pHi, was associated with increased mortality at admission (51% vs. 5%; P<0.0001; n=39) and at 6 h (34% vs. 13%; P=0.016; n=45). A delayed normalization or persistently low pHi (n=47) or high DeltapCO2 (n=25) was associated with high mortality (low pHi [34%] vs. high DeltapCO2 [60%]; P=0.046). In nonsurvivors, hypocapnia increased pHi at baseline, 6, and 24 h (all P

Some demographic issues affecting private health insurance.

PubMed

Hanning, Brian

2004-01-01

There will be significant changes in the demography of persons with Private Health Insurance (PHI). Two methods of projecting PHI coverage are discussed in this paper. The first assumes the only factors affecting PHI coverage are demographic change and mortality and facilitates comparisons between actual and projected PHI coverage. The second projects the percentage of the population insured in each five year age cohort, and makes allowance for changes in PHI coverage due to all factors. Demographic change will increase Registered Health Benefit Organization (RHBO) premiums by 1.7% per annum. The role of these projections in analysing the effect of future premium increases on PHI retention rates is also discussed.

Measurement of fluorophore concentrations and fluorescence quantum yield in tissue-simulating phantoms using three diffusion models of steady-state spatially resolved fluorescence.

PubMed

Diamond, Kevin R; Farrell, Thomas J; Patterson, Michael S

2003-12-21

Steady-state diffusion theory models of fluorescence in tissue have been investigated for recovering fluorophore concentrations and fluorescence quantum yield. Spatially resolved fluorescence, excitation and emission reflectance Carlo simulations, and measured using a multi-fibre probe on tissue-simulating phantoms containing either aluminium phthalocyanine tetrasulfonate (AlPcS4), Photofrin meso-tetra-(4-sulfonatophenyl)-porphine dihydrochloride The accuracy of the fluorophore concentration and fluorescence quantum yield recovered by three different models of spatially resolved fluorescence were compared. The models were based on: (a) weighted difference of the excitation and emission reflectance, (b) fluorescence due to a point excitation source or (c) fluorescence due to a pencil beam excitation source. When literature values for the fluorescence quantum yield were used for each of the fluorophores, the fluorophore absorption coefficient (and hence concentration) at the excitation wavelength (mu(a,x,f)) was recovered with a root-mean-square accuracy of 11.4% using the point source model of fluorescence and 8.0% using the more complicated pencil beam excitation model. The accuracy was calculated over a broad range of optical properties and fluorophore concentrations. The weighted difference of reflectance model performed poorly, with a root-mean-square error in concentration of about 50%. Monte Carlo simulations suggest that there are some situations where the weighted difference of reflectance is as accurate as the other two models, although this was not confirmed experimentally. Estimates of the fluorescence quantum yield in multiple scattering media were also made by determining mu(a,x,f) independently from the fitted absorption spectrum and applying the various diffusion theory models. The fluorescence quantum yields for AlPcS4 and TPPS4 were calculated to be 0.59 +/- 0.03 and 0.121 +/- 0.001 respectively using the point source model, and 0.63 +/- 0.03 and 0.129 +/- 0.002 using the pencil beam excitation model. These results are consistent with published values.

Independent regulation of reovirus membrane penetration and apoptosis by the mu1 phi domain.

PubMed

Danthi, Pranav; Coffey, Caroline M; Parker, John S L; Abel, Ty W; Dermody, Terence S

2008-12-01

Apoptosis plays an important role in the pathogenesis of reovirus encephalitis. Reovirus outer-capsid protein mu1, which functions to penetrate host cell membranes during viral entry, is the primary regulator of apoptosis following reovirus infection. Ectopic expression of full-length and truncated forms of mu1 indicates that the mu1 phi domain is sufficient to elicit a cell death response. To evaluate the contribution of the mu1 phi domain to the induction of apoptosis following reovirus infection, phi mutant viruses were generated by reverse genetics and analyzed for the capacity to penetrate cell membranes and elicit apoptosis. We found that mutations in phi diminish reovirus membrane penetration efficiency by preventing conformational changes that lead to generation of key reovirus entry intermediates. Independent of effects on membrane penetration, amino acid substitutions in phi affect the apoptotic potential of reovirus, suggesting that phi initiates apoptosis subsequent to cytosolic delivery. In comparison to wild-type virus, apoptosis-defective phi mutant viruses display diminished neurovirulence following intracranial inoculation of newborn mice. These results indicate that the phi domain of mu1 plays an important regulatory role in reovirus-induced apoptosis and disease.

Phi is not beta, and why Wertheimer's discovery launched the Gestalt revolution.

PubMed

Steinman, R M; Pizlo, Z; Pizlo, F J

2000-01-01

Max Wertheimer (1880-1943), the founder of the Gestalt School of Psychology, published a monograph on the perception of apparent motion in 1912, which initiated a new direction for a great deal of subsequent perceptual theory and research. Wertheimer's research was inspired by a serendipitous observation of a pure apparent movement, which he called the phi-phenomenon to distinguish it from optimal apparent movement (beta), which resembles real movement. Wertheimer called his novel observation 'pure' because it was perceived in the absence of any object being seen to change its position in space. The phi-phenomenon, as well as the best conditions for seeing it, were not described clearly in this monograph, leading to considerable subsequent confusion about its appearance and occurrence. We review the history leading to the discovery of the phi-phenomenon, and then describe: (i) a likely source for the confusion evident in most contemporary research on the phi-phenomenon; (ii) the best conditions for seeing the phi-phenomenon; (iii) new conditions that provide a particularly vivid phi-phenomenon; and (iv) two lines of thought that may provide explanations of the phi-phenomenon and also distinguish phi from beta.

PHI-base: a new interface and further additions for the multi-species pathogen–host interactions database

PubMed Central

Urban, Martin; Cuzick, Alayne; Rutherford, Kim; Irvine, Alistair; Pedro, Helder; Pant, Rashmi; Sadanadan, Vidyendra; Khamari, Lokanath; Billal, Santoshkumar; Mohanty, Sagar; Hammond-Kosack, Kim E.

2017-01-01

The pathogen–host interactions database (PHI-base) is available at www.phi-base.org. PHI-base contains expertly curated molecular and biological information on genes proven to affect the outcome of pathogen–host interactions reported in peer reviewed research articles. In addition, literature that indicates specific gene alterations that did not affect the disease interaction phenotype are curated to provide complete datasets for comparative purposes. Viruses are not included. Here we describe a revised PHI-base Version 4 data platform with improved search, filtering and extended data display functions. A PHIB-BLAST search function is provided and a link to PHI-Canto, a tool for authors to directly curate their own published data into PHI-base. The new release of PHI-base Version 4.2 (October 2016) has an increased data content containing information from 2219 manually curated references. The data provide information on 4460 genes from 264 pathogens tested on 176 hosts in 8046 interactions. Prokaryotic and eukaryotic pathogens are represented in almost equal numbers. Host species belong ∼70% to plants and 30% to other species of medical and/or environmental importance. Additional data types included into PHI-base 4 are the direct targets of pathogen effector proteins in experimental and natural host organisms. The curation problems encountered and the future directions of the PHI-base project are briefly discussed. PMID:27915230

Schwinger effect in de Sitter space

NASA Astrophysics Data System (ADS)

Fröb, Markus B.; Garriga, Jaume; Kanno, Sugumi; Sasaki, Misao; Soda, Jiro; Tanaka, Takahiro; Vilenkin, Alexander

2014-04-01

We consider Schwinger pair production in 1+1 dimensional de Sitter space, filled with a constant electric field E. This can be thought of as a model for describing false vacuum decay beyond the semiclassical approximation, where pairs of a quantum field phi of mass m and charge e play the role of vacuum bubbles. We find that the adiabatic ``in" vacuum associated with the flat chart develops a space-like expectation value for the current J, which manifestly breaks the de Sitter invariance of the background fields. We derive a simple expression for J(E), showing that both ``upward" and ``downward" tunneling contribute to the build-up of the current. For heavy fields, with m2 gg eE,H2, the current is exponentially suppressed, in agreement with the results of semiclassical instanton methods. Here, H is the inverse de Sitter radius. On the other hand, light fields with m ll H lead to a phenomenon of infrared hyperconductivity, where a very small electric field mHlesssimeE ll H2 leads to a very large current J ~ H3/E. We also show that all Hadamard states for phi necessarily break de Sitter invariance. Finally, we comment on the role of initial conditions, and ``persistence of memory" effects.

Design of UV laser pulses for the preparation of matrix isolated homonuclear diatomic molecules in selective vibrational superposition states.

PubMed

Korolkov, M V; Manz, J

2007-05-07

The preparation of matrix isolated homonuclear diatomic molecules in a vibrational superposition state c0Phie=1,v=0+cjPhie=1,v=j, with large (|c0|2 approximately 1) plus small contributions (|cj|2<1) of the ground v=0 and specific v=j low excited vibrational eigenstates, respectively, in the electronic ground (e=1) state, and without any net population transfer to electronic excited (e>1) states, is an important challenge; it serves as a prerequisite for coherent spin control. For this purpose, the authors investigate two scenarios of laser pulse control, involving sequential or intrapulse pump- and dump-type transitions via excited vibronic states Phiex,k with a dominant singlet or triplet character. The mechanisms are demonstrated by means of quantum simulations for representative nuclear wave packets on coupled potential energy surfaces, using as an example a one-dimensional model for Cl2 in an Ar matrix. A simple three-state model (including Phi1,0, Phi1,j and Phiex,k) allows illuminating analyses and efficient determinations of the parameters of the laser pulses based on the values of the transition energies and dipole couplings of the transient state which are derived from the absorption spectra.

Formation of negative ions in the interstellar medium by dissociative electron attachment to the H2CN molecule

NASA Astrophysics Data System (ADS)

Kokoouline, Viatcheslav; Fonseca Dos Santos, Samantha; Douguet, Nicolas; Orel, Ann

2013-05-01

The methylene amidogen radical (H2CN) was first discovered, in 1962 by Cochran et al ., and since then it has received considerable attention from both experimentalists and theoreticians. It is considered an important intermediate in the combustion of nitramine propellants and proposed to play a role in extraterrestrial atmospheres. It was detected in interstellar clouds in 1994, and its dissociative electron attachment (DEA) process may be responsible for the formation of the CN- and the H- negative ions: e-+H2CN --> CN- + H2; e-+H2CN --> H- + HCN. We report here the results of our ab initio quantum chemical studies of the geometrical and electronic structure of the methylene amidogen and and its negative ion H2CN- in the theoretical of DEA in H2CN. The scattering calculations are carried out using the complex Kohn variational method. The nuclear dynamics, including dissociation, will later be treated using the MCTDH code with a three-dimensional potential energy surface, in which the distance of CN is kept frozen. This work is supported by the DOE Office of Basic Energy Science and the National Science Foundation, Grant No's PHY-11-60611 and PHY-10-68785.

Universality and chaotic dynamics in reactive scattering of ultracold KRb molecules with K atoms

NASA Astrophysics Data System (ADS)

Li, Ming; Makrides, Constantinos; Petrov, Alexander; Kotochigova, Svetlana; Croft, James F. E.; Balakrishnan, Naduvalath; Kendrick, Brian K.

2017-04-01

We study the benchmark reaction between the most-celebrated ultracold polar molecule, KRb, with an ultracold K atom. For the first time we map out an accurate ab initio ground potential energy surface of the K2Rb complex in full dimensionality and performed a numerically exact quantum-mechanical calculation of reaction dynamics based on coupled-channels approach in hyperspherical coordinates. An analysis of the adiabatic hyperspherical potentials reveals a chaotic distribution for the short-range complex that plays a key role in governing the reaction outcome. The equivalent distribution for a lighter collisional system with a smaller density of states (here the Li2Yb trimer) only shows random behavior. We find an extreme sensitivity of our chaotic system to a small perturbation associated with the weak non-additive three-body potential contribution that does not affect the total reaction rate coefficient but leads to a significant change in the rotational distribution in the product molecule. In both cases the distribution of these rates is random or Poissonian. This work was supported in part by NSF Grant PHY-1505557 (N.B.) and PHY-1619788 (S.K.), ARO MURI Grant No. W911NF-12-1-0476 (N.B. & S.K.), and DOE LDRD Grant No. 20170221ER (B.K.).

Time-efficient simulations of tight-binding electronic structures with Intel Xeon PhiTM many-core processors

NASA Astrophysics Data System (ADS)

Ryu, Hoon; Jeong, Yosang; Kang, Ji-Hoon; Cho, Kyu Nam

2016-12-01

Modelling of multi-million atomic semiconductor structures is important as it not only predicts properties of physically realizable novel materials, but can accelerate advanced device designs. This work elaborates a new Technology-Computer-Aided-Design (TCAD) tool for nanoelectronics modelling, which uses a sp3d5s∗ tight-binding approach to describe multi-million atomic structures, and simulate electronic structures with high performance computing (HPC), including atomic effects such as alloy and dopant disorders. Being named as Quantum simulation tool for Advanced Nanoscale Devices (Q-AND), the tool shows nice scalability on traditional multi-core HPC clusters implying the strong capability of large-scale electronic structure simulations, particularly with remarkable performance enhancement on latest clusters of Intel Xeon PhiTM coprocessors. A review of the recent modelling study conducted to understand an experimental work of highly phosphorus-doped silicon nanowires, is presented to demonstrate the utility of Q-AND. Having been developed via Intel Parallel Computing Center project, Q-AND will be open to public to establish a sound framework of nanoelectronics modelling with advanced HPC clusters of a many-core base. With details of the development methodology and exemplary study of dopant electronics, this work will present a practical guideline for TCAD development to researchers in the field of computational nanoelectronics.

The prostate health index PHI predicts oncological outcome and biochemical recurrence after radical prostatectomy - analysis in 437 patients

PubMed Central

Maxeiner, Andreas; Kilic, Ergin; Matalon, Julia; Friedersdorff, Frank; Miller, Kurt; Jung, Klaus; Stephan, Carsten; Busch, Jonas

2017-01-01

The purpose of this study was to investigate the Prostate-Health-Index (PHI) for pathological outcome prediction following radical prostatectomy and also for biochemical recurrence prediction in comparison to established parameters such as Gleason-score, pathological tumor stage, resection status (R0/1) and prostate-specific antigen (PSA). Out of a cohort of 460 cases with preoperative PHI-measurements (World Health Organization calibration: Beckman Coulter Access-2-Immunoassay) between 2001 and 2014, 437 patients with complete follow up data were included. From these 437 patients, 87 (19.9%) developed a biochemical recurrence. Patient characteristics were compared by using chi-square test. Predictors were analyzed by multivariate adjusted logistic and Cox regression. The median follow up for a biochemical recurrence was 65 (range 3-161) months. PHI, PSA, [-2]proPSA, PHI- and PSA-density performed as significant variables (p < 0.05) for cancer aggressiveness: Gleason-score <7 or ≥7 (ISUP grade 1 or ≥2) . Concerning pathological tumor stage discrimination and prediction, variables as PHI, PSA, %fPSA, [-2]proPSA, PHI- and PSA-density significantly discriminated between stages

The prostate health index PHI predicts oncological outcome and biochemical recurrence after radical prostatectomy - analysis in 437 patients.

PubMed

Maxeiner, Andreas; Kilic, Ergin; Matalon, Julia; Friedersdorff, Frank; Miller, Kurt; Jung, Klaus; Stephan, Carsten; Busch, Jonas

2017-10-03

The purpose of this study was to investigate the Prostate-Health-Index (PHI) for pathological outcome prediction following radical prostatectomy and also for biochemical recurrence prediction in comparison to established parameters such as Gleason-score, pathological tumor stage, resection status (R0/1) and prostate-specific antigen (PSA). Out of a cohort of 460 cases with preoperative PHI-measurements (World Health Organization calibration: Beckman Coulter Access-2-Immunoassay) between 2001 and 2014, 437 patients with complete follow up data were included. From these 437 patients, 87 (19.9%) developed a biochemical recurrence. Patient characteristics were compared by using chi-square test. Predictors were analyzed by multivariate adjusted logistic and Cox regression. The median follow up for a biochemical recurrence was 65 (range 3-161) months. PHI, PSA, [-2]proPSA, PHI- and PSA-density performed as significant variables (p < 0.05) for cancer aggressiveness: Gleason-score <7 or ≥7 (ISUP grade 1 or ≥2) . Concerning pathological tumor stage discrimination and prediction, variables as PHI, PSA, %fPSA, [-2]proPSA, PHI- and PSA-density significantly discriminated between stages

Cryogenic on-chip multiplexer for the study of quantum transport in 256 split-gate devices

NASA Astrophysics Data System (ADS)

Al-Taie, H.; Smith, L. W.; Xu, B.; See, P.; Griffiths, J. P.; Beere, H. E.; Jones, G. A. C.; Ritchie, D. A.; Kelly, M. J.; Smith, C. G.

2013-06-01

We present a multiplexing scheme for the measurement of large numbers of mesoscopic devices in cryogenic systems. The multiplexer is used to contact an array of 256 split gates on a GaAs/AlGaAs heterostructure, in which each split gate can be measured individually. The low-temperature conductance of split-gate devices is governed by quantum mechanics, leading to the appearance of conductance plateaux at intervals of 2e2/h. A fabrication-limited yield of 94% is achieved for the array, and a "quantum yield" is also defined, to account for disorder affecting the quantum behaviour of the devices. The quantum yield rose from 55% to 86% after illuminating the sample, explained by the corresponding increase in carrier density and mobility of the two-dimensional electron gas. The multiplexer is a scalable architecture, and can be extended to other forms of mesoscopic devices. It overcomes previous limits on the number of devices that can be fabricated on a single chip due to the number of electrical contacts available, without the need to alter existing experimental set ups.

Dehydroindigo, the forgotten indigo and its contribution to the color of Maya Blue.

PubMed

Rondão, Raquel; Seixas de Melo, J Sérgio; Bonifácio, Vasco D B; Melo, Maria J

2010-02-04

A comprehensive investigation of the electronic spectral and photophysical properties of the oxidized form of indigo, dehydroindigo (DHI), has been carried out in solution at 293 K. It is shown that dehydroindigo readily converts into its neutral keto form, the blue indigo, in a process which depends on the solvent and water content of the medium. DHI was investigated in toluene, in benzene, and in methanol and it was found that both the oxidized and the keto indigo forms are present in solution. In marked contrast to what has been found for keto-indigo, where the internal conversion channel dominates >99% of the excited state deactivation, or with the fully reduced leuco-indigo, where fluorescence, internal conversion, and singlet-to-triplet intersystem crossing coexist, in the case of DHI in toluene and benzene, the dominant excited state deactivation channel involves the triplet state. Triplet state yields (phi(T)) of 70-80%, with negligible fluorescence (< or = 0.01%) are observed in these solvents. In methanol the phi(T) value decreases to approximately 15%, with an increase of the fluorescence quantum yield to 2%, which makes these processes competitive with the S(1) --> S(0) internal conversion deactivation process. The data are experimentally compatible with the existence of a lowest lying singlet excited state of n,pi* origin in toluene and of pi,pi* origin in methanol. A time-resolved investigation in the picosecond time domain suggests that the emission of DHI involves three interconnected species (involving rotational isomerism), with relative contributions depending on the emission wavelength. DFT calculations (B3LYP 6-31G** level) were performed in order to characterize the electronic ground (S(0)) and excited singlet (S(1)) and triplet (T(1)) states of DHI. The HOMO-LUMO transition was found to accompany an n --> pi* transition of the oxygen nonbonding orbitals to the central CC and adjacent C-N bonds. Calculations also revealed that in S(0) the two indole-like moieties deviate from planarity from ca. 20 degrees, whereas in S(1) and T(1) the predicted structure is basically planar; a gradual decrease of the carbon-carbon central bond distance is seen in the order S(0), S(1), T(1). An additional study on the blue pigment Maya Blue was made, and the comparison between the solid-state spectra of indigo, DHI, and Maya Blue suggests that, in line with recent investigations, DHI is present together with indigo in Maya Blue. These results are relevant to the discussion of the involvement of dehydroindigo in the palette of colors of the ancient Maya Blue pigment.

Wilson Dslash Kernel From Lattice QCD Optimization

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

Joo, Balint; Smelyanskiy, Mikhail; Kalamkar, Dhiraj D.

2015-07-01

Lattice Quantum Chromodynamics (LQCD) is a numerical technique used for calculations in Theoretical Nuclear and High Energy Physics. LQCD is traditionally one of the first applications ported to many new high performance computing architectures and indeed LQCD practitioners have been known to design and build custom LQCD computers. Lattice QCD kernels are frequently used as benchmarks (e.g. 168.wupwise in the SPEC suite) and are generally well understood, and as such are ideal to illustrate several optimization techniques. In this chapter we will detail our work in optimizing the Wilson-Dslash kernels for Intel Xeon Phi, however, as we will show themore » technique gives excellent performance on regular Xeon Architecture as well.« less

Revisiting chameleon gravity: Thin-shell and no-shell fields with appropriate boundary conditions

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

Tamaki, Takashi; Department of Physics, Rikkyo University, Toshima, Tokyo 171-8501; Tsujikawa, Shinji

2008-10-15

We derive analytic solutions of a chameleon scalar field {phi} that couples to a nonrelativistic matter in the weak gravitational background of a spherically symmetric body, paying particular attention to a field mass m{sub A} inside of the body. The standard thin-shell field profile is recovered by taking the limit m{sub A}r{sub c}{yields}{infinity}, where r{sub c} is a radius of the body. We show the existence of 'no-shell' solutions where the field is nearly frozen in the whole interior of the body, which does not necessarily correspond to the 'zero-shell' limit of thin-shell solutions. In the no-shell case, under themore » condition m{sub A}r{sub c}>>1, the effective coupling of {phi} with matter takes the same asymptotic form as that in the thin-shell case. We study experimental bounds coming from the violation of equivalence principle as well as solar-system tests for a number of models including f(R) gravity and find that the field is in either the thin-shell or the no-shell regime under such constraints, depending on the shape of scalar-field potentials. We also show that, for the consistency with local gravity constraints, the field at the center of the body needs to be extremely close to the value {phi}{sub A} at the extremum of an effective potential induced by the matter coupling.« less

Adaptation to high CO2 concentration in an optimal environment: radiation capture, canopy quantum yield and carbon use efficiency

NASA Technical Reports Server (NTRS)

Monje, O.; Bugbee, B.

1998-01-01

The effect of elevated [CO2] on wheat (Triticum aestivum L. Veery 10) productivity was examined by analysing radiation capture, canopy quantum yield, canopy carbon use efficiency, harvest index and daily C gain. Canopies were grown at either 330 or 1200 micromoles mol-1 [CO2] in controlled environments, where root and shoot C fluxes were monitored continuously from emergence to harvest. A rapidly circulating hydroponic solution supplied nutrients, water and root zone oxygen. At harvest, dry mass predicted from gas exchange data was 102.8 +/- 4.7% of the observed dry mass in six trials. Neither radiation capture efficiency nor carbon use efficiency were affected by elevated [CO2], but yield increased by 13% due to a sustained increase in canopy quantum yield. CO2 enrichment increased root mass, tiller number and seed mass. Harvest index and chlorophyll concentration were unchanged, but CO2 enrichment increased average life cycle net photosynthesis (13%, P < 0.05) and root respiration (24%, P < 0.05). These data indicate that plant communities adapt to CO2 enrichment through changes in C allocation. Elevated [CO2] increases sink strength in optimal environments, resulting in sustained increases in photosynthetic capacity, canopy quantum yield and daily C gain throughout the life cycle.

Recursive mass matrix factorization and inversion: An operator approach to open- and closed-chain multibody dynamics

NASA Technical Reports Server (NTRS)

Rodriguez, G.; Kreutz, K.

1988-01-01

This report advances a linear operator approach for analyzing the dynamics of systems of joint-connected rigid bodies.It is established that the mass matrix M for such a system can be factored as M=(I+H phi L)D(I+H phi L) sup T. This yields an immediate inversion M sup -1=(I-H psi L) sup T D sup -1 (I-H psi L), where H and phi are given by known link geometric parameters, and L, psi and D are obtained recursively by a spatial discrete-step Kalman filter and by the corresponding Riccati equation associated with this filter. The factors (I+H phi L) and (I-H psi L) are lower triangular matrices which are inverses of each other, and D is a diagonal matrix. This factorization and inversion of the mass matrix leads to recursive algortihms for forward dynamics based on spatially recursive filtering and smoothing. The primary motivation for advancing the operator approach is to provide a better means to formulate, analyze and understand spatial recursions in multibody dynamics. This is achieved because the linear operator notation allows manipulation of the equations of motion using a very high-level analytical framework (a spatial operator algebra) that is easy to understand and use. Detailed lower-level recursive algorithms can readily be obtained for inspection from the expressions involving spatial operators. The report consists of two main sections. In Part 1, the problem of serial chain manipulators is analyzed and solved. Extensions to a closed-chain system formed by multiple manipulators moving a common task object are contained in Part 2. To retain ease of exposition in the report, only these two types of multibody systems are considered. However, the same methods can be easily applied to arbitrary multibody systems formed by a collection of joint-connected regid bodies.

Rigidifying fluorescent linkers by metal-organic framework formation for fluorescence blue shift and quantum yield enhancement.

PubMed

Wei, Zhangwen; Gu, Zhi-Yuan; Arvapally, Ravi K; Chen, Ying-Pin; McDougald, Roy N; Ivy, Joshua F; Yakovenko, Andrey A; Feng, Dawei; Omary, Mohammad A; Zhou, Hong-Cai

2014-06-11

We demonstrate that rigidifying the structure of fluorescent linkers by structurally constraining them in metal-organic frameworks (MOFs) to control their conformation effectively tunes the fluorescence energy and enhances the quantum yield. Thus, a new tetraphenylethylene-based zirconium MOF exhibits a deep-blue fluorescent emission at 470 nm with a unity quantum yield (99.9 ± 0.5%) under Ar, representing ca. 3600 cm(-1) blue shift and doubled radiative decay efficiency vs the linker precursor. An anomalous increase in the fluorescence lifetime and relative intensity takes place upon heating the solid MOF from cryogenic to ambient temperatures. The origin of these unusual photoluminescence properties is attributed to twisted linker conformation, intramolecular hindrance, and framework rigidity.

The reaction of NH2 with NO2

NASA Technical Reports Server (NTRS)

Jayanty, R. K. M.; Simonaitis, R.; Heicklen, J.

1976-01-01

Ammonia (NH3) was photolyzed at 213.9 nm in the presence of NO2 at 25 C in order to study the reactions of NH2 with NO2. The products included NO, with a quantum yield of 1.0. The other measured products of the reaction were N2 and N2O with respective quantum yields of 0.94 plus or minus 0.10 and 0.3 in the presence of small amounts of He and 0.65 plus or minus 0.15 and 0.13 in the presence of a large excess of He. The quantum yield for NO2 consumption was 6.0 plus or minus 2.0 in the absence of He. These results are explained in terms of various reactions.

Symmetry relations in charmless B{yields}PPP decays

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

Gronau, Michael; Rosner, Jonathan L.; Enrico Fermi Institute and Department of Physics, University of Chicago, 5640 South Ellis Avenue, Chicago, Illinois 60637

2005-11-01

Strangeness-changing decays of B mesons to three-body final states of pions and kaons are studied, assuming that they are dominated by a {delta}I=0 penguin amplitude with flavor structure b{yields}s. Numerous isospin relations for B{yields}K{pi}{pi} and for underlying quasi-two-body decays are compared successfully with experiment, in some cases resolving ambiguities in fitting resonance parameters. The only exception is a somewhat small branching ratio noted in B{sup 0}{yields}K*{sup 0}{pi}{sup 0}, interpreted in terms of destructive interference between a penguin amplitude and an enhanced electroweak penguin contribution. Relations for B decays into three kaons are derived in terms of final states involving K{submore » S} or K{sub L}, assuming that {phi}K-subtracted decay amplitudes are symmetric in K and K, as has been observed experimentally. Rates due to nonresonant backgrounds are studied using a simple model, which may reduce discrete ambiguities in Dalitz plot analyses.« less

Amplitude Analysis of B0 to K^ pi^-pi^0 and Evidence of Direct CP Violation in B to K^* pi decays

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

Lees, J.P.

We analyze the decay B{sup 0} {yields} K{sup +} {pi}{sup -} {pi}{sup 0} with a sample of 454 million B{bar B} events collected by the BABAR detector at the PEP-II asymmetric-energy B factory at SLAC, and extract the complex amplitudes of seven interfering resonances over the Dalitz plot. These results are combined with amplitudes measured in B{sup 0} {yields} K{sup 0}{sub s}{pi}{sup +}{pi}{sup -} decays to construct isospin amplitudes from B{sup 0} {yields} K{sup *}{pi} and B{sup 0} {yields} {rho}K decays. We measure the phase of the isospin amplitude {Phi}{sub 3/2}, useful in constraining the CKM unitarity triangle angle {gamma}more » and evaluate a CP rate asymmetry sum rule sensitive to the presence of new physics operators. We measure direct CP violation in B{sup 0} {yields} K{sup *+}{pi}{sup -} decays at the level of 3 {sigma} when measurements from both B{sup 0} {yields} K{sup +}{pi}{sup -}{pi}{sup 0} and B{sup 0} {yields} K{sup 0}{sub s}{pi}{sup +}{pi}{sup -} decays are combined.« less

X-Phi and Carnapian Explication.

PubMed

Shepherd, Joshua; Justus, James

2015-04-01

The rise of experimental philosophy (x-phi) has placed metaphilosophical questions, particularly those concerning concepts, at the center of philosophical attention. X-phi offers empirically rigorous methods for identifying conceptual content, but what exactly it contributes towards evaluating conceptual content remains unclear. We show how x-phi complements Rudolf Carnap's underappreciated methodology for concept determination, explication. This clarifies and extends x-phi's positive philosophical import, and also exhibits explication's broad appeal. But there is a potential problem: Carnap's account of explication was limited to empirical and logical concepts, but many concepts of interest to philosophers (experimental and otherwise) are essentially normative. With formal epistemology as a case study, we show how x-phi assisted explication can apply to normative domains.

phiGENOME: an integrative navigation throughout bacteriophage genomes.

PubMed

Stano, Matej; Klucar, Lubos

2011-11-01

phiGENOME is a web-based genome browser generating dynamic and interactive graphical representation of phage genomes stored in the phiSITE, database of gene regulation in bacteriophages. phiGENOME is an integral part of the phiSITE web portal (http://www.phisite.org/phigenome) and it was optimised for visualisation of phage genomes with the emphasis on the gene regulatory elements. phiGENOME consists of three components: (i) genome map viewer built using Adobe Flash technology, providing dynamic and interactive graphical display of phage genomes; (ii) sequence browser based on precisely formatted HTML tags, providing detailed exploration of genome features on the sequence level and (iii) regulation illustrator, based on Scalable Vector Graphics (SVG) and designed for graphical representation of gene regulations. Bringing 542 complete genome sequences accompanied with their rich annotations and references, makes phiGENOME a unique information resource in the field of phage genomics. Copyright © 2011 Elsevier Inc. All rights reserved.

AgCl-doped CdSe quantum dots with near-IR photoluminescence.

PubMed

Kotin, Pavel Aleksandrovich; Bubenov, Sergey Sergeevich; Mordvinova, Natalia Evgenievna; Dorofeev, Sergey Gennadievich

2017-01-01

We report the synthesis of colloidal CdSe quantum dots doped with a novel Ag precursor: AgCl. The addition of AgCl causes dramatic changes in the morphology of synthesized nanocrystals from spherical nanoparticles to tetrapods and finally to large ellipsoidal nanoparticles. Ellipsoidal nanoparticles possess an intensive near-IR photoluminescence ranging up to 0.9 eV (ca. 1400 nm). In this article, we explain the reasons for the formation of the ellipsoidal nanoparticles as well as the peculiarities of the process. The structure, Ag content, and optical properties of quantum dots are also investigated. The optimal conditions for maximizing both the reaction yield and IR photoluminescence quantum yield are found.

DNA conformational change induced by the bacteriophage phi 29 connector.

PubMed Central

Valpuesta, J M; Serrano, M; Donate, L E; Herranz, L; Carrascosa, J L

1992-01-01

Translocation of viral DNA inwards and outwards of the capsid of double-stranded DNA bacteriophages occurs through the connector, a key viral structure that is known to interact with DNA. It is shown here that phage phi 29 connector binds both linear and circular double-stranded DNA. However, DNA-mediated protection of phi 29 connectors against Staphylococcus aureus endoprotease V8 digestion suggests that binding to linear DNA is more stable than to circular DNA. Endoprotease V8-protection assays also suggest that the length of the linear DNA required to produce a stable phi 29 connector-DNA interaction is, at least, twice longer than the phi 29 connector channel. This result is confirmed by experiments of phi 29 connector-protection of DNA against DNase I digestion. Furthermore, DNA circularization assays indicate that phi 29 connectors restrain negative supercoiling when bound to linear DNA. This DNA conformational change is not observed upon binding to circular DNA and it could reflect the existence of some left-handed DNA coiling or DNA untwisting inside of the phi 29 connector channel. Images PMID:1454519

Scaling of ion expansion energy with laser flux in moderate-Z plasmas produced by lasers

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

Gupta, P.D.; Goel, S.K.; Uppal, J.S.

1982-09-01

Ion expansion energy measurements in plasmas created by focusing 1-GW, 5-nsec Nd:glass laser on plane solid targets of polythene, carbon, and aluminum are reported. It is observed that the scaling of ion expansion energy with laser flux Phi varies between Phi/sup 0.28/ and Phi/sup 0.66/ for polythene, Phi/sup 0.28/ and Phi/sup 0.70/ for carbon, and Phi/sup 0.51/ and Phi/sup 0.44/ for aluminum in the flux range 5 x 10/sup 10/--5 x 10/sup 12/ W/cm/sup 2/ of our experiment. The scaling is either much slower or faster than a scaling of Phi/sup 4/9/ expected from a self-regulating model for plasmas createdmore » in the low flux range. It is shown that this behavior, as well as results of experiments on similar plasmas reported by other authors, can be explained when radiation losses and the energy spent in ionization are also considered in the self-regulating model.« less

Defining, Describing, and Categorizing Public Health Infrastructure Priorities for Tropical Cyclone, Flood, Storm, Tornado, and Tsunami-Related Disasters.

PubMed

Ryan, Benjamin J; Franklin, Richard C; Burkle, Frederick M; Watt, Kerrianne; Aitken, Peter; Smith, Erin C; Leggat, Peter

2016-08-01

The study aim was to undertake a qualitative research literature review to analyze available databases to define, describe, and categorize public health infrastructure (PHI) priorities for tropical cyclone, flood, storm, tornado, and tsunami-related disasters. Five electronic publication databases were searched to define, describe, or categorize PHI and discuss tropical cyclone, flood, storm, tornado, and tsunami-related disasters and their impact on PHI. The data were analyzed through aggregation of individual articles to create an overall data description. The data were grouped into PHI themes, which were then prioritized on the basis of degree of interdependency. Sixty-seven relevant articles were identified. PHI was categorized into 13 themes with a total of 158 descriptors. The highest priority PHI identified was workforce. This was followed by water, sanitation, equipment, communication, physical structure, power, governance, prevention, supplies, service, transport, and surveillance. This review identified workforce as the most important of the 13 thematic areas related to PHI and disasters. If its functionality fails, workforce has the greatest impact on the performance of health services. If addressed post-disaster, the remaining forms of PHI will then be progressively addressed. These findings are a step toward providing an evidence base to inform PHI priorities in the disaster setting. (Disaster Med Public Health Preparedness. 2016;10:598-610).

The occurrence of phi in dento-facial beauty of fine art from antiquity through the Renaissance.

PubMed

Wiener, R Constance; Wiener Pla, Regina M

2012-01-01

External beauty is a complex construct that influences lives and may be impacted by dentists. Beauty is not easily quantified, but one cited anthropometric of beauty is the ratio phi, the number 1.618033(...). This study examined phi as a measure of female frontal facial beauty in classic Western art, using pre- Renaissance (N = 30), and Renaissance (N = 30) artwork. Four horizontal and five vertical ratios were determined in the works of art, which were then compared with the phi ratio. All horizontal ratios for both pre-Renaissance and Renaissance artwork were similar to each other, but did not contain the phi ratio (P < 0.001). Nevertheless, all vertical ratios for pre-Renaissance and Renaissance art-work did contain the phi ratio within their confidence intervals with the exception of the vertical ratio, "intereye point to soft tissue menton/ intereye point to stomion", that was found to be less than phi in the Renaissance group. The study provides evidence of the presence of the phi ratio in vertical aspect of females in artwork from pre-Renaissance through the Renaissance demonstrating consistent temporal preferences. Therefore, the phi ratio seems to be an important consideration in altering vertical facial dimensions in full mouth rehabilitation and reconstructive orthognathic surgery involving females.

Cytoplasmic pH influences cytoplasmic calcium in MC3T3-E1 osteoblast cells

NASA Technical Reports Server (NTRS)

Lin, H. S.; Hughes-Fulford, M.; Kumegawa, M.; Pitts, A. C.; Snowdowne, K. W.

1993-01-01

We found that the cytoplasmic concentration of calcium (Cai) of MC3T3-E1 osteoblasts was influenced by the type of pH buffer we used in the perfusing medium, suggesting that intracellular pH (pHi) might influence Cai. To study this effect, the Cai and pHi were monitored as we applied various experimental conditions known to change pHi. Exposure to NH4Cl caused a transient increase in both pHi and Cai without a change in extracellular pH (pHo). Decreasing pHo and pHi by lowering the bicarbonate concentration of the medium decreased Cai, and increasing pHi by the removal of 5% CO2 increased Cai. Clamping pHi to known values with 10 microM nigericin, a potassium proton ionophore, also influenced Cai: acid pHi lowered Cai, whereas alkaline pHi increased it. The rise in Cai appears to be very sensitive to the extracellular concentration of calcium, suggesting the existence of a pH-sensitive calcium influx mechanism. We conclude that physiologic changes in pH could modulate Cai by controlling the influx of calcium ions and could change the time course of the Cai transient associated with hormonal activation.

RNA packaging device of double-stranded RNA bacteriophages, possibly as simple as hexamer of P4 protein.

PubMed

Kainov, Denis E; Pirttimaa, Markus; Tuma, Roman; Butcher, Sarah J; Thomas, George J; Bamford, Dennis H; Makeyev, Eugene V

2003-11-28

Genomes of complex viruses have been demonstrated, in many cases, to be packaged into preformed empty capsids (procapsids). This reaction is performed by molecular motors translocating nucleic acid against the concentration gradient at the expense of NTP hydrolysis. At present, the molecular mechanisms of packaging remain elusive due to the complex nature of packaging motors. In the case of the double-stranded RNA bacteriophage phi 6 from the Cystoviridae family, packaging of single-stranded genomic precursors requires a hexameric NTPase, P4. In the present study, the purified P4 proteins from two other cystoviruses, phi 8 and phi 13, were characterized and compared with phi 6 P4. All three proteins are hexameric, single-stranded RNA-stimulated NTPases with alpha/beta folds. Using a direct motor assay, we found that phi 8 and phi 13 P4 hexamers translocate 5' to 3' along ssRNA, whereas the analogous activity of phi 6 P4 requires association with the procapsid. This difference is explained by the intrinsically high affinity of phi 8 and phi 13 P4s for nucleic acids. The unidirectional translocation results in RNA helicase activity. Thus, P4 proteins of Cystoviridae exhibit extensive similarity to hexameric helicases and are simple models for studying viral packaging motor mechanisms.

Measurements of CP Asymmetries in the Decay B --> {phi}K

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

Aubert, B

The authors present a preliminary measurement of the time-dependent CP asymmetry for the neutral B-meson decay B{sup 0} --> {phi}K{sup 0}. They use a sample of approximately 227 million B-meson pairs recorded at the {Upsilon}(4S) resonance with the BABAR detector at the PEP-II B-meson Factory at SLAC. They reconstruct the CP eigenstates {phi}K{sub s}{sup 0} and {phi}K{sub L}{sup 0} where {phi} --> K{sup +}K{sup -}, K{sub s}{sup 0} --> {pi}{sup +}{pi}{sup -}, and K{sub L}{sup 0} is observed via its hadronic interactions. The other B meson in the event is tagged as either a B{sup 0} or {bar B}{sup 0}more » from its decay products. The values of the CP-violation parameters deived from the combined {phi}K{sup 0} dataset are S{sub {phi}K} = +0.50 {+-} 0.25(stat.){sub -0.04}{sup +0.07}(syst.) and C{sub {phi}K} = 0.00 {+-} 0.23(stat.) {+-}0.05(syst.). In addition, the authors measure the CP-violating charge asymmetry A{sub CP}(B{sup +} --> {phi}K{sup +}) = 0.054 {+-} 0.056(stat.) {+-} 0.012(syst.). All results are preliminary.« less

Kinetics and metabolism of physostigmine in rat in the presence of soman

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

Khalique, A.; Somani, S.M.

1986-03-01

The effect of soman (105 ..mu..g/kg; 1.5 LD/sub 50/ s.c.) administration on pharmacokinetics and metabolism of /sup 3/H-physostigmine (Phy) was studied in rats. The rats were pretreated with either Phy 100 ..mu..g/kg i.v. or 500 ..mu..g/kg i.m., 5 or 15 min prior to soman administration. Phy and metabolites were determined in plasma and brain by HPLC. The half-life of Phy in plasma after i.v. administration was 15.5 min both in the presence and absence of soman, however the t/sub 1/2/ in brain was 11 min and 13 min, respectively. Clearance was 71.4 ml/min/kg in the Phy treated rat and 90more » ml/min/kg in the presence of soman. The half-life of Phy in plasma was 18 min and 17 min, and in brain 17 min and 15 min, respectively in the absence and presence of soman after i.m. dose of Phy. Clearance after Phy treatment was 85.2 mlmin/kg however in the presence of soman, it was 66.7 ml/min/kg. Phy was slightly less metabolized to eseroline and two other metabolites, M/sub 1/ and M/sub 2/, in the presence of soman after i.v. as well as after i.m. administration in plasma and brain. The soman administration does not change the pharmacokinetics of Phy by the two different dosages and routes of administration.« less

PHI-base: a new interface and further additions for the multi-species pathogen-host interactions database.

PubMed

Urban, Martin; Cuzick, Alayne; Rutherford, Kim; Irvine, Alistair; Pedro, Helder; Pant, Rashmi; Sadanadan, Vidyendra; Khamari, Lokanath; Billal, Santoshkumar; Mohanty, Sagar; Hammond-Kosack, Kim E

2017-01-04

The pathogen-host interactions database (PHI-base) is available at www.phi-base.org PHI-base contains expertly curated molecular and biological information on genes proven to affect the outcome of pathogen-host interactions reported in peer reviewed research articles. In addition, literature that indicates specific gene alterations that did not affect the disease interaction phenotype are curated to provide complete datasets for comparative purposes. Viruses are not included. Here we describe a revised PHI-base Version 4 data platform with improved search, filtering and extended data display functions. A PHIB-BLAST search function is provided and a link to PHI-Canto, a tool for authors to directly curate their own published data into PHI-base. The new release of PHI-base Version 4.2 (October 2016) has an increased data content containing information from 2219 manually curated references. The data provide information on 4460 genes from 264 pathogens tested on 176 hosts in 8046 interactions. Prokaryotic and eukaryotic pathogens are represented in almost equal numbers. Host species belong ∼70% to plants and 30% to other species of medical and/or environmental importance. Additional data types included into PHI-base 4 are the direct targets of pathogen effector proteins in experimental and natural host organisms. The curation problems encountered and the future directions of the PHI-base project are briefly discussed. © The Author(s) 2016. Published by Oxford University Press on behalf of Nucleic Acids Research.

Novel phytochrome sequences in Arabidopsis thaliana: Structure, evolution, and differential expression of a plant regulatory photoreceptor family

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

Sharrock, R.A.; Quail, P.H.

1989-01-01

Phytochrome is a plant regulatory photoreceptor that mediates red light effects on a wide variety of physiological and molecular responses. DNA blot analysis indicates that the Arabidopsis thaliana genome contains four to five phytochrome-related gene sequences. The authors have isolated and sequenced cDNA clones corresponding to three of these genes and have deduced the amino acid sequence of the full-length polypeptide encoded in each case. One of these proteins (phyA) shows 65-80% amino acid sequence identity with the major, etiolated-tissue phytochrome apoproteins described previously in other plant species. The other two polypeptides (phyB and phyC) are unique in that theymore » have low sequence identity with each other, with phyA, and with all previously described phytochromes. The phyA, phyB, and phyC proteins are of similar molecular mass, have related hydropathic profiles, and contain a conserved chromophore attachment region. However, the sequence comparison data indicate that the three phy genes diverged early in plant evolution, well before the divergence of the two major groups of angiosperms, the monocots and dicots. The steady-state level of the phyA transcript is high in dark-grown A. thaliana seedlings and is down-regulated by light. In contrast, the phyB and phyC transcripts are present at lower levels and are not strongly light-regulated. These findings indicate that the red/far red light-responsive phytochrome photoreceptor system in A. thaliana, and perhaps in all higher plants, consists of a family of chromoproteins that are heterogeneous in structure and regulation.« less

Time course of cholinesterase activity in plasma, brain and muscle of rat pretreated with physostigmine, and then soman

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

Giacobini, E.; Boyer, A.; Somani, S.M.

1986-03-05

Time course of /sup 3/H-physostigmine (Phy) concentration and cholinesterase (ChE) activity in plasma and tissues was studied in rats pretreated with Phy and then soman. Rats were dosed with Phy (100 ..mu..g/kg, i.v.), 5 or 15 min prior to soman (105 ..mu..g/kg, 1.5 LD/sub 50/, s.c.) treatment and were sacrificed at various times; Phys conc. and ChE activity were determined. BuChE activity in plasma was 5% of control from 7-30 min after Phy i.v. pretreatment and soman or soman alone treatment. Plasma Phy conc. steadily declined (32.6 ng/ml at 7 min) to 15 ng/ml at 30 min. ChE activity inmore » muscle was 60-50% of control for Phy pretreated but soman alone gave 85-72% activity from 2-30 min. Brain ChE activity was about 5% of control within 2 min after soman treatment; however, with Phy pretreatment, the activity was about 52% at 7 min, 40% at 22 min, which recovered to 45% of control at 35 min, indicating that Phy protected brain ChE. Brain Phy conc. steadily declined (58.6 ng/g at 7 min) to 11.7 ng/g at 30 min. However, pretreatment of rat with a higher dose of Phy and then soman showed BuChE in plasma and ChE in brain and muscle to be about 25, 35 and 51%, in comparison to about 5% in plasma and brain with soman alone treatment, indicating higher protection of ChE enzyme with higher conc. of Phy in plasma and brain.« less

A phytochrome/phototropin chimeric photoreceptor of fern functions as a blue/far-red light-dependent photoreceptor for phototropism in Arabidopsis.

PubMed

Kanegae, Takeshi; Kimura, Izumi

2015-08-01

In the fern Adiantum capillus-veneris, the phototropic response of the protonemal cells is induced by blue light and partially inhibited by subsequent irradiation with far-red light. This observation strongly suggests the existence of a phytochrome that mediates this blue/far-red reversible response; however, the phytochrome responsible for this response has not been identified. PHY3/NEO1, one of the three phytochrome genes identified in Adiantum, encodes a chimeric photoreceptor composed of both a phytochrome and a phototropin domain. It was demonstrated that phy3 mediates the red light-dependent phototropic response of Adiantum, and that phy3 potentially functions as a phototropin. These findings suggest that phy3 is the phytochrome that mediates the blue/far-red response in Adiantum protonemata. In the present study, we expressed Adiantum phy3 in a phot1 phot2 phototropin-deficient Arabidopsis line, and investigated the ability of phy3 to induce phototropic responses under various light conditions. Blue light irradiation clearly induced a phototropic response in the phy3-expressing transgenic seedlings, and this effect was fully inhibited by simultaneous irradiation with far-red light. In addition, experiments using amino acid-substituted phy3 indicated that FMN-cysteinyl adduct formation in the light, oxygen, voltage (LOV) domain was not necessary for the induction of blue light-dependent phototropism by phy3. We thus demonstrate that phy3 is the phytochrome that mediates the blue/far-red reversible phototropic response in Adiantum. Furthermore, our results imply that phy3 can function as a phototropin, but that it acts principally as a phytochrome that mediates both the red/far-red and blue/far-red light responses. © 2015 The Authors The Plant Journal © 2015 John Wiley & Sons Ltd.

Tumor-cytolytic human macrophages cultured as nonadherent cells: potential for the adoptive immunotherapy of cancer.

PubMed

Helinski, E H; Hurley, E L; Streck, R J; Bielat, K L; Pauly, J L

1990-01-01

Tumor-cytolytic lymphokine (e.g., interleukin-2; IL-2)-activated killer cells are currently being evaluated in IL-2/LAK cell adoptive immunotherapy regimens for the treatment of cancer. Monocyte-derived macrophages (M phi) are also known to be efficient tumor killer cells; accordingly, M phi that have been activated in vitro may also be of therapeutic merit. However, attempts to cultivate M phi for morphological and functional studies have often been compromised because M phi adhere rapidly and tenaciously to cultureware. Studies that we have conducted to address this problem have proven successful in developing procedures for the long-term cultivation of non-adherent immunocompetent M phi in serum-free medium using petri dishes containing a thin Teflon liner. The utility of this technology is documented by the results of studies presented herein in which light and scanning electron microscopy was used to analyze tumor-cytolytic human M phi. In these experiments, we demonstrated that nonadherent immunocompetent human M phi can be prepared for detailed examinations of their pleomorphic membrane architecture. Moreover, nonadherent human M phi could readily be collected for preparing conjugates of M phi and tumor cells. It is anticipated that this technology should prove useful for future structure-function studies defining the topographical location and spatial distribution of antigens and receptors on M phi membrane ultrastructures, particularly the microvilli-like projections that bridge together an immunocompetent effector M phi and target cell (e.g., tumor cells and microbial pathogens) and which provide the physical interaction required for the initial phases of a cellular immune response that includes antigen recognition and cell-to-cell adhesion.

Expression of Aspergillus nidulans phy Gene in Nicotiana benthamiana Produces Active Phytase with Broad Specificities

PubMed Central

Oh, Tae-Kyun; Oh, Sung; Kim, Seongdae; Park, Jae Sung; Vinod, Nagarajan; Jang, Kyung Min; Kim, Sei Chang; Choi, Chang Won; Ko, Suk-Min; Jeong, Dong Kee; Udayakumar, Rajangam

2014-01-01

A full-length phytase gene (phy) of Aspergillus nidulans was amplified from the cDNA library by polymerase chain reaction (PCR), and it was introduced into a bacterial expression vector, pET-28a. The recombinant protein (rPhy-E, 56 kDa) was overexpressed in the insoluble fraction of Escherichia coli culture, purified by Ni-NTA resin under denaturing conditions and injected into rats as an immunogen. To express A. nidulans phytase in a plant, the full-length of phy was cloned into a plant expression binary vector, pPZP212. The resultant construct was tested for its transient expression by Agrobacterium-infiltration into Nicotiana benthamiana leaves. Compared with a control, the agro-infiltrated leaf tissues showed the presence of phy mRNA and its high expression level in N. benthamiana. The recombinant phytase (rPhy-P, 62 kDa) was strongly reacted with the polyclonal antibody against the nonglycosylated rPhy-E. The rPhy-P showed glycosylation, two pH optima (pH 4.5 and pH 5.5), an optimum temperature at 45~55 °C, thermostability and broad substrate specificities. After deglycosylation by peptide-N-glycosidase F (PNGase-F), the rPhy-P significantly lost the phytase activity and retained 1/9 of the original activity after 10 min of incubation at 45 °C. Therefore, the deglycosylation caused a significant reduction in enzyme thermostability. In animal experiments, oral administration of the rPhy-P at 1500 U/kg body weight/day for seven days caused a significant reduction of phosphorus excretion by 16% in rat feces. Besides, the rPhy-P did not result in any toxicological changes and clinical signs. PMID:25192284

Genome of Enterobacteriophage Lula/phi80 and Insights into Its Ability To Spread in the Laboratory Environment

PubMed Central

Rotman, Ella; Kouzminova, Elena; Plunkett, Guy

2012-01-01

The novel temperate bacteriophage Lula, contaminating laboratory Escherichia coli strains, turned out to be the well-known lambdoid phage phi80. Our previous studies revealed that two characteristics of Lula/phi80 facilitate its spread in the laboratory environment: cryptic lysogen productivity and stealthy infectivity. To understand the genetics/genomics behind these traits, we sequenced and annotated the Lula/phi80 genome, encountering an E. coli-toxic gene revealed as a gap in the sequencing contig and analyzing a few genes in more detail. Lula/phi80's genome layout copies that of lambda, yet homology with other lambdoid phages is mostly limited to the capsid genes. Lula/phi80's DNA is resistant to cutting with several restriction enzymes, suggesting DNA modification, but deletion of the phage's damL gene, coding for DNA adenine methylase, did not make DNA cuttable. The damL mutation of Lula/phi80 also did not change the phage titer in lysogen cultures, whereas the host dam mutation did increase it almost 100-fold. Since the high phage titer in cultures of Lula/phi80 lysogens is apparently in response to endogenous DNA damage, we deleted the only Lula/phi80 SOS-controlled gene, dinL. We found that dinL mutant lysogens release fewer phage in response to endogenous DNA damage but are unchanged in their response to external DNA damage. The toxic gene of Lula/phi80, gamL, encodes an inhibitor of the host ATP-dependent exonucleases, RecBCD and SbcCD. Its own antidote, agt, apparently encoding a modifier protein, was found nearby. Interestingly, Lula/phi80 lysogens are recD and sbcCD phenocopies, so GamL and Agt are part of lysogenic conversion. PMID:23042999

Relationship between intracellular pH and proton mobility in rat and guinea-pig ventricular myocytes.

PubMed

Swietach, Pawel; Vaughan-Jones, Richard D

2005-08-01

Intracellular H+ ion mobility in eukaryotic cells is low because of intracellular buffering. We have investigated whether Hi+ mobility varies with pHi. A dual microperfusion apparatus was used to expose guinea-pig or rat myocytes to small localized doses (3-5 mm) of ammonium chloride (applied in Hepes-buffered solution). Intracellular pH (pHi) was monitored confocally using the fluorescent dye, carboxy-SNARF-1. Local ammonium exposure produced a stable, longitudinal pHi gradient. Its size was fed into a look-up table (LUT) to give an estimate of the apparent intracellular proton diffusion coefficient (D(app)H). LUTs were generated using a diffusion-reaction model of Hi+ mobility based on intracellular buffer diffusion. To examine the pHi sensitivity of D(app)H, whole-cell pHi was initially displaced using a whole-cell ammonium or acetate prepulse, before locally applying the low dose of ammonium. In both rat and guinea-pig, D(app)H decreased with pHi over the range 7.5-6.5. In separate pipette-loading experiments, the intracellular diffusion coefficient for carboxy-SNARF-1 (a mobile-buffer analogue) exhibited no significant pHi dependence. The pHi sensitivity of D(app)H is thus likely to be governed by the mobile fraction of intrinsic buffering capacity. These results reinforce the buffer hypothesis of Hi+ mobility. The pHi dependence of D(app)H was used to characterize the mobile and fixed buffer components, and to estimate D(mob) (the average diffusion coefficient for intracellular mobile buffer). One consequence of a decline in Hi+ mobility at low pHi is that it will predispose the myocardium to pHi nonuniformity. The physiological relevance of this is discussed.

Hydrogen ion dynamics in human red blood cells

PubMed Central

Swietach, Pawel; Tiffert, Teresa; Mauritz, Jakob M A; Seear, Rachel; Esposito, Alessandro; Kaminski, Clemens F; Lew, Virgilio L; Vaughan-Jones, Richard D

2010-01-01

Our understanding of pH regulation within red blood cells (RBCs) has been inferred mainly from indirect experiments rather than from in situ measurements of intracellular pH (pHi). The present work shows that carboxy-SNARF-1, a pH fluorophore, when used with confocal imaging or flow cytometry, reliably reports pHi in individual, human RBCs, provided intracellular fluorescence is calibrated using a ‘null-point’ procedure. Mean pHi was 7.25 in CO2/HCO3−-buffered medium and 7.15 in Hepes-buffered medium, and varied linearly with extracellular pH (slope of 0.77). Intrinsic (non-CO2/HCO3−-dependent) buffering power, estimated in the intact cell (85 mmol (l cell)−1 (pH unit)−1 at resting pHi), was somewhat higher than previous estimates from cell lysates (50–70 mmol (l cell)−1 (pH unit)−1). Acute displacement of pHi (superfusion of weak acids/bases) triggered rapid pHi recovery. This was mediated via membrane Cl−/HCO3− exchange (the AE1 gene product), irrespective of whether recovery was from an intracellular acid or base load, and with no evident contribution from other transporters such as Na+/H+ exchange. H+-equivalent flux through AE1 was a linear function of [H+]i and reversed at resting pHi, indicating that its activity is not allosterically regulated by pHi, in contrast to other AE isoforms. By simultaneously monitoring pHi and markers of cell volume, a functional link between membrane ion transport, volume and pHi was demonstrated. RBC pHi is therefore tightly regulated via AE1 activity, but modulated during changes of cell volume. A comparable volume–pHi link may also be important in other cell types expressing anion exchangers. Direct measurement of pHi should be useful in future investigations of RBC physiology and pathology. PMID:20962000

Prostate Health Index (Phi) and Prostate Cancer Antigen 3 (PCA3) Significantly Improve Prostate Cancer Detection at Initial Biopsy in a Total PSA Range of 2–10 ng/ml

PubMed Central

Perdonà, Sisto; Marino, Ada; Mazzarella, Claudia; Perruolo, Giuseppe; D’Esposito, Vittoria; Cosimato, Vincenzo; Buonerba, Carlo; Di Lorenzo, Giuseppe; Musi, Gennaro; De Cobelli, Ottavio; Chun, Felix K.; Terracciano, Daniela

2013-01-01

Many efforts to reduce prostate specific antigen (PSA) overdiagnosis and overtreatment have been made. To this aim, Prostate Health Index (Phi) and Prostate Cancer Antigen 3 (PCA3) have been proposed as new more specific biomarkers. We evaluated the ability of phi and PCA3 to identify prostate cancer (PCa) at initial prostate biopsy in men with total PSA range of 2–10 ng/ml. The performance of phi and PCA3 were evaluated in 300 patients undergoing first prostate biopsy. ROC curve analyses tested the accuracy (AUC) of phi and PCA3 in predicting PCa. Decision curve analyses (DCA) were used to compare the clinical benefit of the two biomarkers. We found that the AUC value of phi (0.77) was comparable to those of %p2PSA (0.76) and PCA3 (0.73) with no significant differences in pairwise comparison (%p2PSA vs phi p = 0.673, %p2PSA vs. PCA3 p = 0.417 and phi vs. PCA3 p = 0.247). These three biomarkers significantly outperformed fPSA (AUC = 0.60), % fPSA (AUC = 0.62) and p2PSA (AUC = 0.63). At DCA, phi and PCA3 exhibited a very close net benefit profile until the threshold probability of 25%, then phi index showed higher net benefit than PCA3. Multivariable analysis showed that the addition of phi and PCA3 to the base multivariable model (age, PSA, %fPSA, DRE, prostate volume) increased predictive accuracy, whereas no model improved single biomarker performance. Finally we showed that subjects with active surveillance (AS) compatible cancer had significantly lower phi and PCA3 values (p<0.001 and p = 0.01, respectively). In conclusion, both phi and PCA3 comparably increase the accuracy in predicting the presence of PCa in total PSA range 2–10 ng/ml at initial biopsy, outperforming currently used %fPSA. PMID:23861782

Prostate Health Index (Phi) and Prostate Cancer Antigen 3 (PCA3) significantly improve prostate cancer detection at initial biopsy in a total PSA range of 2-10 ng/ml.

PubMed

Ferro, Matteo; Bruzzese, Dario; Perdonà, Sisto; Marino, Ada; Mazzarella, Claudia; Perruolo, Giuseppe; D'Esposito, Vittoria; Cosimato, Vincenzo; Buonerba, Carlo; Di Lorenzo, Giuseppe; Musi, Gennaro; De Cobelli, Ottavio; Chun, Felix K; Terracciano, Daniela

2013-01-01

Many efforts to reduce prostate specific antigen (PSA) overdiagnosis and overtreatment have been made. To this aim, Prostate Health Index (Phi) and Prostate Cancer Antigen 3 (PCA3) have been proposed as new more specific biomarkers. We evaluated the ability of phi and PCA3 to identify prostate cancer (PCa) at initial prostate biopsy in men with total PSA range of 2-10 ng/ml. The performance of phi and PCA3 were evaluated in 300 patients undergoing first prostate biopsy. ROC curve analyses tested the accuracy (AUC) of phi and PCA3 in predicting PCa. Decision curve analyses (DCA) were used to compare the clinical benefit of the two biomarkers. We found that the AUC value of phi (0.77) was comparable to those of %p2PSA (0.76) and PCA3 (0.73) with no significant differences in pairwise comparison (%p2PSA vs phi p = 0.673, %p2PSA vs. PCA3 p = 0.417 and phi vs. PCA3 p = 0.247). These three biomarkers significantly outperformed fPSA (AUC = 0.60), % fPSA (AUC = 0.62) and p2PSA (AUC = 0.63). At DCA, phi and PCA3 exhibited a very close net benefit profile until the threshold probability of 25%, then phi index showed higher net benefit than PCA3. Multivariable analysis showed that the addition of phi and PCA3 to the base multivariable model (age, PSA, %fPSA, DRE, prostate volume) increased predictive accuracy, whereas no model improved single biomarker performance. Finally we showed that subjects with active surveillance (AS) compatible cancer had significantly lower phi and PCA3 values (p<0.001 and p = 0.01, respectively). In conclusion, both phi and PCA3 comparably increase the accuracy in predicting the presence of PCa in total PSA range 2-10 ng/ml at initial biopsy, outperforming currently used %fPSA.

Seasonal and spatial variabilities in the water chemistry of prairie pothole wetlands influence the photoproduction of reactive intermediates.

PubMed

McCabe, Andrew J; Arnold, William A

2016-07-01

The hydrology and water chemistry of prairie pothole wetlands vary spatially and temporally, on annual and decadal timescales. Pesticide contamination of wetlands arising from agricultural activities is a foremost concern. Photochemical reactions are important in the natural attenuation of pesticides and may be important in limiting ecological and human exposure. Little is known, however, about the variable influence of wetland water chemistry on indirect photochemistry. In this study, seasonal water samples were collected from seven sites throughout the prairie pothole region over three years to understand the spatiotemporal dynamics of reactive intermediate photoproduction. Samples were classified by the season in which they were collected (spring, summer, or fall) and the typical hydroperiod of the wetland surface water (temporary or semi-permanent). Under photostable conditions, steady-state concentrations and apparent quantum yields or quantum yield coefficients were measured for triplet excited states of dissolved organic matter, singlet oxygen, hydroxyl radical, and carbonate radical under simulated sunlight. Steady-state concentrations and quantum yields increased on average by 15% and 40% from spring to fall, respectively. Temporary wetlands had 40% higher steady-state concentrations of reactive intermediates than semi-permanent wetlands, but 50% lower quantum yields. Computed quantum yields for reactive intermediate formation were used to predict the indirect photochemical half-lives of seven pesticides in average temporary and semi-permanent prairie pothole wetlands. As a first approximation, the predictions agree to within two orders of magnitude of previously reported half-lives. Copyright © 2016 Elsevier Ltd. All rights reserved.

The phi-meson and Chiral-mass-meson production in heavy-ion collisions as potential probes of quark-gluon-plasma and Chiral symmetry transitions

NASA Technical Reports Server (NTRS)

Takahashi, Y.; Eby, P. B.

1985-01-01

Possibilities of observing abundances of phi mesons and narrow hadronic pairs, as results of QGP and Chiral transitions, are considered for nucleus-nucleus interactions. Kinematical requirements in forming close pairs are satisfied in K+K decays of S(975) and delta (980) mesons with small phi, and phi (91020) mesons with large PT, and in pi-pi decays of familiar resonance mesons only in a partially restored chiral symmetry. Gluon-gluon dominance in QGP can enhance phi meson production. High hadronization rates of primordial resonance mesons which form narrow hadronic pairs are not implausible. Past cosmic ray evidences of anomalous phi production and narrow pair abundances are considered.

Generalized Weyl-Wigner map and Vey quantum mechanics

NASA Astrophysics Data System (ADS)

Dias, Nuno Costa; Prata, João Nuno

2001-12-01

The Weyl-Wigner map yields the entire structure of Moyal quantum mechanics directly from the standard operator formulation. The covariant generalization of Moyal theory, also known as Vey quantum mechanics, was presented in the literature many years ago. However, a derivation of the formalism directly from standard operator quantum mechanics, clarifying the relation between the two formulations, is still missing. In this article we present a covariant generalization of the Weyl order prescription and of the Weyl-Wigner map and use them to derive Vey quantum mechanics directly from the standard operator formulation. The procedure displays some interesting features: it yields all the key ingredients and provides a more straightforward interpretation of the Vey theory including a direct implementation of unitary operator transformations as phase space coordinate transformations in the Vey idiom. These features are illustrated through a simple example.

Quantum optics and nano-optics teaching laboratory for the undergraduate curriculum: teaching quantum mechanics and nano-physics with photon counting instrumentation

NASA Astrophysics Data System (ADS)

Lukishova, Svetlana G.

2017-08-01

At the Institute of Optics, University of Rochester (UR), we have adapted to the main challenge (the lack of space in the curriculum) by developing a series of modular 3-hour experiments and 20-min-demonstrations based on technical elective, 4-credit-hour laboratory course "Quantum Optics and Nano-Optics Laboratory" (OPT 253/OPT453/PHY434), that were incorporated into a number of required courses ranging from freshman to senior level. Rochester Monroe Community College (MCC) students also benefited from this facility that was supported by four NSF grants. MCC students carried out two 3-hour labs on photon quantum mechanics at the UR. Since 2006, total 566 students passed through the labs with lab reports submission (including 144 MCC students) and more than 250 students through lab demonstrations. In basic class OPT 253, four teaching labs were prepared on generation and characterization of entangled and single (antibunched) photons demonstrating the laws of quantum mechanics: (1) entanglement and Bell's inequalities, (2) single-photon interference (Young's double slit experiment and Mach-Zehnder interferometer), (3) confocal microscope imaging of single-emitter (colloidal nanocrystal quantum dots and NV-center nanodiamonds) fluorescence within photonic (liquid crystal photonic bandgap microcavities) or plasmonic (gold bowtie nanoantennas) nanostructures, (4) Hanbury Brown and Twiss setup. Fluorescence antibunching from nanoemitters. Students also carried out measurements of nanodiamond topography using atomic force microscopy and prepared photonic bandgap materials from cholesteric liquid crystals. Manuals, student reports, presentations, lecture materials and quizzes, as well as some NSF grants' reports are placed on a website http://www.optics.rochester.edu/workgroups/lukishova/QuantumOpticsLab/ . In 2011 UR hosted 6 professors from different US universities in three-days training of these experiments participating in the Immersion Program of the Advanced Laboratory Physics Association.

Purcell-enhanced quantum yield from carbon nanotube excitons coupled to plasmonic nanocavities

DOE PAGES

Luo, Yue; Ahmadi, Ehsaneh D.; Shayan, Kamran; ...

2017-11-10

Single-walled carbon nanotubes (SWCNTs) are promising absorbers and emitters to enable novel photonic applications and devices but are also known to suffer from low optical quantum yields. Here we demonstrate SWCNT excitons coupled to plasmonic nanocavity arrays reaching deeply into the Purcell regime with Purcell factors (F P) up to F P = 180 (average F P = 57), Purcell-enhanced quantum yields of 62% (average 42%), and a photon emission rate of 15 MHz into the first lens. The cavity coupling is quasi-deterministic since the photophysical properties of every SWCNT are enhanced by at least one order of magnitude. Furthermore,more » the measured ultra-narrow exciton linewidth (18 ueV) reaches the radiative lifetime limit, which is promising towards generation of transform-limited single photons. Furthermore, to demonstrate utility beyond quantum light sources we show that nanocavity-coupled SWCNTs perform as single-molecule thermometers detecting plasmonically induced heat at cryogenic temperatures in a unique interplay of excitons, phonons, and plasmons at the nanoscale.« less

Identification of QTL and Qualitative Trait Loci for Agronomic Traits Using SNP Markers in the Adzuki Bean.

PubMed

Li, Yuan; Yang, Kai; Yang, Wei; Chu, Liwei; Chen, Chunhai; Zhao, Bo; Li, Yisong; Jian, Jianbo; Yin, Zhichao; Wang, Tianqi; Wan, Ping

2017-01-01

The adzuki bean ( Vigna angularis ) is an important grain legume. Fine mapping of quantitative trait loci (QTL) and qualitative trait genes plays an important role in gene cloning, molecular-marker-assisted selection (MAS), and trait improvement. However, the genetic control of agronomic traits in the adzuki bean remains poorly understood. Single-nucleotide polymorphisms (SNPs) are invaluable in the construction of high-density genetic maps. We mapped 26 agronomic QTLs and five qualitative trait genes related to pigmentation using 1,571 polymorphic SNP markers from the adzuki bean genome via restriction-site-associated DNA sequencing of 150 members of an F 2 population derived from a cross between cultivated and wild adzuki beans. We mapped 11 QTLs for flowering time and pod maturity on chromosomes 4, 7, and 10. Six 100-seed weight (SD100WT) QTLs were detected. Two major flowering time QTLs were located on chromosome 4, firstly VaFld4.1 (PEVs 71.3%), co-segregating with SNP marker s690-144110, and VaFld4.2 (PEVs 67.6%) at a 0.974 cM genetic distance from the SNP marker s165-116310. Three QTLs for seed number per pod ( Snp3.1, Snp3.2 , and Snp4.1 ) were mapped on chromosomes 3 and 4. One QTL VaSdt4.1 of seed thickness (SDT) and three QTLs for branch number on the main stem were detected on chromosome 4. QTLs for maximum leaf width (LFMW) and stem internode length were mapped to chromosomes 2 and 9, respectively. Trait genes controlling the color of the seed coat, pod, stem and flower were mapped to chromosomes 3 and 1. Three candidate genes, VaAGL, VaPhyE , and VaAP2 , were identified for flowering time and pod maturity. VaAGL encodes an agamous-like MADS-box protein of 379 amino acids. VaPhyE encodes a phytochrome E protein of 1,121 amino acids. Four phytochrome genes ( VaPhyA1, VaPhyA2, VaPhyB , and VaPhyE ) were identified in the adzuki bean genome. We found candidate genes VaAP2/ERF.81 and VaAP2/ERF.82 of SD100WT, VaAP2-s4 of SDT, and VaAP2/ERF.86 of LFMW. A candidate gene VaUGT related to black seed coat color was identified. These mapped QTL and qualitative trait genes provide information helpful for future adzuki bean candidate gene cloning and MAS breeding to improve cultivars with desirable growth periods, yields, and seed coat color types.

Quantum yield and rate constant of the singlet 1Δ g oxygen luminescence in an aqueous medium in the presence of nanoscale inhomogeneities

NASA Astrophysics Data System (ADS)

Jarnikova, E. S.; Parkhats, M. V.; Stasheuski, A. S.; Lepeshkevich, S. V.; Dzhagarov, B. M.

2017-04-01

The quantum yields and lifetimes of photosensitized luminescence of the 1Δ g state of singlet oxygen in an aquatic media with a controlled concentration of dielectric anisotropy centers (polyethylene glycol) have been measured using the methods of laser fluorometry. It is established that the quantum yield and the rate constant ( k r ) of the a 1Δ g → X 3Σ g - luminescence of 1O2 increase as the polymer concentration increases. The effect is analyzed within a general approach involving a relationship between kr and dielectric properties of the medium and is explained by the increased density of photon states and the local field factor in the space around O2( a 1Δ g ).

Accurate quantum yields by laser gain vs absorption spectroscopy - Investigation of Br/Br(asterisk) channels in photofragmentation of Br2 and IBr

NASA Technical Reports Server (NTRS)

Haugen, H. K.; Weitz, E.; Leone, S. R.

1985-01-01

Various techniques have been used to study photodissociation dynamics of the halogens and interhalogens. The quantum yields obtained by these techniques differ widely. The present investigation is concerned with a qualitatively new approach for obtaining highly accurate quantum yields for electronically excited states. This approach makes it possible to obtain an accuracy of 1 percent to 3 percent. It is shown that measurement of the initial transient gain/absorption vs the final absorption in a single time-resolved signal is a very accurate technique in the study of absolute branching fractions in photodissociation. The new technique is found to be insensitive to pulse and probe laser characteristics, molecular absorption cross sections, and absolute precursor density.

Cross sections and quantum yields of the 3 micron emission for Er(3+) and Ho(3+) dopants in crystalsls

NASA Astrophysics Data System (ADS)

Payne, Stephen A.; Smith, Larry K.; Krupke, William F.

1995-05-01

The lifetime, quantum yields, and branching ratios for the 2.8 micron emissions of several Er-and Ho-doped fluorides and oxides were measured. Among the fluoride crystals examined, which included LiYF4, BaY2F8, LaF3, and KY3F10, only the Ho:LiFY4 systems showed any proof of nonradiative decay. Conversely, all the oxide crystals were affected by nonradiative processes, resulting in measured quantum yields ranging from 3.6% for Er:Y3Al5O12 to 62% for Er in Gd3Sc2Ga3O12. In addition, plots of the 2.8 micron emission cross sections for seven Er- and Ho-doped crystals were presented.

Sample-averaged biexciton quantum yield measured by solution-phase photon correlation.

PubMed

Beyler, Andrew P; Bischof, Thomas S; Cui, Jian; Coropceanu, Igor; Harris, Daniel K; Bawendi, Moungi G

2014-12-10

The brightness of nanoscale optical materials such as semiconductor nanocrystals is currently limited in high excitation flux applications by inefficient multiexciton fluorescence. We have devised a solution-phase photon correlation measurement that can conveniently and reliably measure the average biexciton-to-exciton quantum yield ratio of an entire sample without user selection bias. This technique can be used to investigate the multiexciton recombination dynamics of a broad scope of synthetically underdeveloped materials, including those with low exciton quantum yields and poor fluorescence stability. Here, we have applied this method to measure weak biexciton fluorescence in samples of visible-emitting InP/ZnS and InAs/ZnS core/shell nanocrystals, and to demonstrate that a rapid CdS shell growth procedure can markedly increase the biexciton fluorescence of CdSe nanocrystals.

IRBIT plays an important role in NHE3-mediated pHi regulation in HSG cells.

PubMed

Tran, Tien Manh; Park, Moon-Yong; Lee, Jiyeon; Bae, Jun-Seok; Hwang, Sung-Min; Choi, Se-Young; Mikoshiba, Katsuhiko; Park, Kyungpyo

2013-07-19

Expression of inositol-1,4,5-trisphosphate (IP3) receptor-binding protein (IRBIT) has been reported in epithelial cells. However, its role in pHi regulation is not well understood. In this study, we investigated the role of IRBIT in pHi regulation, mediated by Na(+)/H(+) exchangers (NHEs), in salivary glands. We measured pHi recovery from cell acidification in BCECF-loaded salivary HSG cells. Western blot and co-immunoprecipitation (CO-IP) assays were also performed, showing that NHE1, 2 and 3 are expressed, and IRBIT binds to NHE3. HOE642, a specific NHE1 blocker, inhibited pHi recovery, but 40% pH(i) recovery was still observed even at the highest concentration of HOE642. Furthermore, pretreatment of the cells with siIRBIT significantly inhibited pHi recovery, indicating that NHE3 potentially plays a role in pHi recovery as well. The amount of membrane-localized NHE3 and its interaction with IRBIT are also significantly increased by cell acidification. In addition, we found that Ste20p-related proline alanine-rich kinase (SPAK) reverses the effect of IRBIT on membrane NHE3 translocation. Taken together, we conclude that IRBIT plays an important role in pHi regulation, mediated by NHE3, and further regulated by SPAK. Copyright © 2013 Elsevier Inc. All rights reserved.

Characterisation of transition state structures for protein folding using 'high', 'medium' and 'low' {Phi}-values.

PubMed

Geierhaas, Christian D; Salvatella, Xavier; Clarke, Jane; Vendruscolo, Michele

2008-03-01

It has been suggested that Phi-values, which allow structural information about transition states (TSs) for protein folding to be obtained, are most reliably interpreted when divided into three classes (high, medium and low). High Phi-values indicate almost completely folded regions in the TS, intermediate Phi-values regions with a detectable amount of structure and low Phi-values indicate mostly unstructured regions. To explore the extent to which this classification can be used to characterise in detail the structure of TSs for protein folding, we used Phi-values divided into these classes as restraints in molecular dynamics simulations. This type of procedure is related to that used in NMR spectroscopy to define the structure of native proteins from the measurement of inter-proton distances derived from nuclear Overhauser effects. We illustrate this approach by determining the TS ensembles of five proteins and by showing that the results are similar to those obtained by using as restraints the actual numerical Phi-values measured experimentally. Our results indicate that the simultaneous consideration of a set of low-resolution Phi-values can provide sufficient information for characterising the architecture of a TS for folding of a protein.

A novel protein tyrosine phosphatase like phytase from Lactobacillus fermentum NKN51: Cloning, characterization and application in mineral release for food technology applications.

PubMed

Sharma, Rekha; Kumar, Piyush; Kaushal, Vandana; Das, Rahul; Kumar Navani, Naveen

2018-02-01

A novel protein tyrosine phosphatase like phytase (PTPLP), designated as PhyLf from probiotic bacterium Lactobacillus fermentum NKN51 was identified, cloned, expressed and characterized. The recombinant PhyLf showed specific activity of 174.5 U/mg. PhyLf exhibited strict specificity towards phytate and optimum temperature at 60 °C, pH 5.0 and ionic strength of 100 mM. K m and K cat of PhyLf for phytate were 0.773 mM and 84.31 s -1 , respectively. PhyLf exhibited high resistance against oxidative inactivation. PhyLf shares no homology, sans the active site with reported PTLPs, warranting classification as a new subclass. Dephytinization of durum wheat and finger millet under in vitro gastrointestinal conditions using PhyLf enhanced the bioaccessibility of mineral ions. Probiotic origin, phytate specificity, resistance to oxidative environment and gastric milieu coupled with ability to release micronutrients are unique properties of PhyLf which present a strong case for its use in ameliorating nutritional value of cereals and animal feed. Copyright © 2017 Elsevier Ltd. All rights reserved.

Ordovician and Silurian Phi Kappa and Trail Creek formations, Pioneer Mountains, central Idaho; stratigraphic and structural revisions, and new data on graptolite faunas

USGS Publications Warehouse

Dover, James H.; Berry, William B.N.; Ross, Reuben James

1980-01-01

Recent geologic mapping in the northern Pioneer Mountains combined with the identification of graptolites from 116 new collections indicate that the Ordovician and Silurian Phi Kappa and Trail Creek Formations occur in a series of thrust-bounded slices within a broad zone of imbricate thrust faulting. Though confirming a deformational style first reported in a 1963 study by Michael Churkin, our data suggest that the complexity and regional extent of the thrust zone were not previously recognized. Most previously published sections of the Phi Kappa and Trail Creek Formations were measured across unrecognized thrust faults and therefore include not only structural repetitions of graptolitic Ordovician and Silurian rocks but also other tectonically juxtaposed lithostratigraphic units of diverse ages as well. Because of this discovery, the need to reconsider the stratigraphic validity of these formations and their lithology, nomenclature, structural distribution, facies relations, and graptolite faunas has arisen. The Phi Kappa Formation in most thrust slices has internal stratigraphic continuity despite the intensity of deformation to which it was subjected. As revised herein, the Phi Kappa Formation is restricted to a structurally repeated succession of predominantly black, carbonaceous, graptolitic argillite and shale. Some limy, light-gray-weathering shale occurs in the middle part of the section, and fine-grained locally pebbly quartzite is present at the base. The basal quartzite is here named the Basin Gulch Quartzite Member of the Phi Kappa. The Phi Kappa redefined on a lithologic basis represents the span of Ordovician time from W. B. N. Berry's graptolite zones 2-4 through 15 and also includes approximately 17 m of lithologically identical shale of Early and Middle Silurian age at the top. The lower contact of the formation as revised is tectonic. The Phi Kappa is gradationally overlain by the Trail Creek Formation as restricted herein. Most of the coarser clastic rocks reported in previously measured sections of the Phi Kappa, as well as the sequence along Phi Kappa Creek from which the name originates, are excluded from the Phi Kappa as revised and are reassigned to two structural plates of Mississippian Copper Basin Formation; other strata now excluded from the formation are reassigned to the Trail Creek Formation and to an unnamed Silurian and Devonian unit. As redefined, the Phi Kappa Formation is only about 240 m thick, compared with the 3,860 m originally estimated, and it occupies only about 25 percent of the outcrop area previously mapped in 1930 by H. G. Westgate and C. P. Ross. Despite this drastic reduction in thickness and the exclusion of the rocks along Phi Kappa Creek, the name Phi Kappa is retained because of widely accepted prior usage to denote the Ordovician graptolitic shale facies of central Idaho, and because the Phi Kappa Formation as revised is present in thrust slices on Phi Kappa Mountain, at the head of Phi Kappa Creek. The lithic and faunal consistency of this unit throughout the area precludes the necessity for major facies telescoping along individual faults within the outcrop belt. However, tens of kilometers of tectonic shortening seems required to juxtapose the imbricated Phi Kappa shale facies with the Middle Ordovician part of the carbonate and quartzite shale sequence of east central Idaho. The shelf rocks are exposed in the Wildhorse structural window of the northeastern Pioneer Mountains, and attain a thickness of at least 1,500 m throughout the region north and east of the Pioneer Mountains. The Phi Kappa is in direct thrust contact on intensely deformed medium- to high-grade metamorphic equivalents of the same shelf sequence in the Pioneer window at the south end of the Phi Kappa-Trail Creek outcrop belt. Along East Pass, Big Lake, and Pine Creeks, north of the Pioneer Mountains, some rocks previously mapped as Ramshorn Slate are lithologically and faunally equivalent to the P

Cross-couplings in the elaboration of luminescent bis-terpyridyl iridium complexes: the effect of extended or inhibited conjugation on emission.

PubMed

Leslie, Wendy; Batsanov, Andrei S; Howard, Judith A K; Williams, J A Gareth

2004-02-21

The utility of Suzuki cross-coupling methodology for the in situ elaboration of bromo-functionalised bis-terpyridyl iridium(III) complexes has been explored. The complex [Ir(tpy)(tpy-phi-Br)]3+ [tpy-phi-Br = 4'-(4-bromophenyl)-2,2':6',2''-terpyridine] undergoes palladium-catalysed cross-coupling with aryl boronic acids to yield biaryl-substituted complexes directly. The biphenyl and 4-cyanobiphenyl-substituted products display relatively intense, long-lived (tau > 100 mus) yellow emission in degassed aqueous solution at room temperature, assigned to a 3pi-pi* state. A 4-aminobiphenyl-substituted analogue displays an additional low energy absorbance band, attributed to an intraligand charge-transfer (ILCT) excited state, and is scarcely emissive under the same conditions. The iridium(III) complex of 4'-mesityl-terpyridine is also reported. Its emission is much shorter-lived, with a spectral profile resembling that of unsubstituted [Ir(tpy)2]3+, confirming the need for the attainment of a roughly coplanar geometry for stabilisation of the 3pi-pi* excited state.

The 'shoulder' and the 'ridge' in PHENIX

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

McCumber, M. P.; Awes, Terry C; Cianciolo, Vince

2008-01-01

The observation of jet quenching in ultra-relativistic heavy ion collisions demonstrates significant energy loss of fast partons when passing through the created medium. Correlations between final-state particles at intermediate transverse momentum (1.0 {approx}< p{sub T} {approx}< 4.0 GeV/c) allow for study of the medium and its response to deposited energy. Comparison of these measurements in heavy ion collisions with measurements in proton collisions show strong modification of the correlation shape and particle yields. Two new structures are created, both extended in {Delta}{eta}, one centered at {Delta}{phi} = 0 ('ridge') and the other occurring at {Delta}{phi} {approx} {pi} {+-} 1.1 ('shoulder').more » In these proceedings, we describe the measurements of these structures that show consistency with a scenario of parton-medium interaction and response. We discuss a new analysis which selects on the angle of trigger particles relative to the reaction plane in Run7. New measurements of the centrality and p{sub T} dependencies of the structures raise the possibility that the same production mechanism may give rise to both phenomena.« less

Application of geometric algebra for the description of polymer conformations.

PubMed

Chys, Pieter

2008-03-14

In this paper a Clifford algebra-based method is applied to calculate polymer chain conformations. The approach enables the calculation of the position of an atom in space with the knowledge of the bond length (l), valence angle (theta), and rotation angle (phi) of each of the preceding bonds in the chain. Hence, the set of geometrical parameters {l(i),theta(i),phi(i)} yields all the position coordinates p(i) of the main chain atoms. Moreover, the method allows the calculation of side chain conformations and the computation of rotations of chain segments. With these features it is, in principle, possible to generate conformations of any type of chemical structure. This method is proposed as an alternative for the classical approach by matrix algebra. It is more straightforward and its final symbolic representation considerably simpler than that of matrix algebra. Approaches for realistic modeling by means of incorporation of energetic considerations can be combined with it. This article, however, is entirely focused at showing the suitable mathematical framework on which further developments and applications can be built.

The extraction of Φ – N total cross section from d ( γ , p K + K - ) n

DOE PAGES

Qian, X.; Chen, W.; Gao, H.; ...

2009-10-01

We report on the first measurement of the differential cross section ofmore » $$\\phi$$-meson photoproduction for the $$d(\\gamma,pK^{+}K^{-})n$$ exclusive reaction channel. The experiment was performed using a \\textcolor{black}{tagged-photon} beam and the CEBAF Large Acceptance Spectrometer (CLAS) at Jefferson Lab. A combined analysis using data from the $$d(\\gamma,pK^{+}K^{-})n$$ channel and those from a previous publication on coherent $$\\phi$$ production on the deuteron has been carried out to extract the $$\\phi-N$$ total cross section, $$\\sigma_{\\phi N}$$. The extracted $$\\phi-N$$ total cross section favors a value above 20 mb. This value is larger than the value extracted using vector-meson dominance models for $$\\phi$$ photoproduction on the proton.« less

Water relation, leaf gas exchange and chlorophyll a fluorescence imaging of soybean leaves infected with Colletotrichum truncatum.

PubMed

Dias, Carla Silva; Araujo, Leonardo; Alves Chaves, Joicy Aparecida; DaMatta, Fábio M; Rodrigues, Fabrício A

2018-06-01

Considering the potential of anthracnose to decrease soybean yield and the need to gain more information regarding its effect on soybean physiology, the present study performed an in-depth analysis of the photosynthetic performance of soybean leaflets challenged with Colletotrichum truncatum by combining chlorophyll a fluorescence images with gas-exchange measurements and photosynthetic pigment pools. There were no significant differences between non-inoculated and inoculated plants in leaf water potential, apparent hydraulic conductance, net CO 2 assimilation rate, stomatal conductance to water vapor and transpiration rate. For internal CO 2 concentration, significant difference between non-inoculated and inoculated plants occurred only at 36 h after inoculation. Reductions in the values of the chlorophyll a fluorescence parameters [initial fluorescence (F 0 ), maximal fluorescence (F m ), maximal photosystem II quantum yield (F v /F m ), quantum yield of regulated energy dissipation (Y(NPQ))] and increases in effective PS II quantum yield (Y(II)), quantum yield of non-regulated energy dissipation Y(NO) and photochemical quenching coefficient (q P ) were noticed on the necrotic vein tissue in contrast to the surrounding leaf tissue. It appears that the impact of the infection by C. truncatum on the photosynthetic performance of the leaflets was minimal considering the preference of the fungus to colonize the veins. Copyright © 2018 Elsevier Masson SAS. All rights reserved.

Violet-to-Blue Gain and Lasing from Colloidal CdS Nanoplatelets: Low-Threshold Stimulated Emission Despite Low Photoluminescence Quantum Yield

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

Diroll, Benjamin T.; Talapin, Dmitri V.; Schaller, Richard D.

Amplified spontaneous emission (ASE) and lasing from solution-processed materials are demonstrated in the challenging violet-to-blue (430–490 nm) spectral region for colloidal nanoplatelets of CdS and newly synthesized core/shell CdS/ZnS nanoplatelets. Despite modest band-edge photoluminescence quantum yields of 2% or less for single excitons, which we show results from hole trapping, the samples exhibit low ASE thresholds. Furthermore, four-monolayer CdS samples show ASE at shorter wavelengths than any reported film of colloidal quantum-confined material. This work underlines that low quantum yields for single excitons do not necessarily lead to a poor gain medium. The low ASE thresholds originate from negligible dispersionmore » in thickness, large absorption cross sections of 2.8 × 10–14 cm–2, and rather slow (150 to 300 ps) biexciton recombination. We show that under higher-fluence excitation, ASE can kinetically outcompete hole trapping. Using nanoplatelets as the gain medium, lasing is observed in a linear optical cavity. This work confirms the fundamental advantages of colloidal quantum well structures as gain media, even in the absence of high photoluminescence efficiency.« less

Inkjet printed fluorescent nanorod layers exhibit superior optical performance over quantum dots

NASA Astrophysics Data System (ADS)

Halivni, Shira; Shemesh, Shay; Waiskopf, Nir; Vinetsky, Yelena; Magdassi, Shlomo; Banin, Uri

2015-11-01

Semiconductor nanocrystals exhibit unique fluorescence properties which are tunable in size, shape and composition. The high quantum yield and enhanced stability have led to their use in biomedical imaging and flat panel displays. Here, semiconductor nanorod based inkjet inks are presented, overcoming limitations of the commonly reported quantum dots in printing applications. Fluorescent seeded nanorods were found to be outstanding candidates for fluorescent inks, due to their low particle-particle interactions and negligible self-absorption. This is manifested by insignificant emission shifts upon printing, even in highly concentrated printed layers and by maintenance of a high fluorescence quantum yield, unlike quantum dots which exhibit fluorescence wavelength shifts and quenching effects. This behavior results from the reduced absorption/emission overlap, accompanied by low energy transfer efficiencies between the nanorods as supported by steady state and time resolved fluorescence measurements. The new seeded nanorod inks enable patterning of thin fluorescent layers, for demanding light emission applications such as signage and displays.Semiconductor nanocrystals exhibit unique fluorescence properties which are tunable in size, shape and composition. The high quantum yield and enhanced stability have led to their use in biomedical imaging and flat panel displays. Here, semiconductor nanorod based inkjet inks are presented, overcoming limitations of the commonly reported quantum dots in printing applications. Fluorescent seeded nanorods were found to be outstanding candidates for fluorescent inks, due to their low particle-particle interactions and negligible self-absorption. This is manifested by insignificant emission shifts upon printing, even in highly concentrated printed layers and by maintenance of a high fluorescence quantum yield, unlike quantum dots which exhibit fluorescence wavelength shifts and quenching effects. This behavior results from the reduced absorption/emission overlap, accompanied by low energy transfer efficiencies between the nanorods as supported by steady state and time resolved fluorescence measurements. The new seeded nanorod inks enable patterning of thin fluorescent layers, for demanding light emission applications such as signage and displays. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr06248a

LASER APPLICATIONS AND OTHER TOPICS IN QUANTUM ELECTRONICS: Kinetics and quantum yield of photoluminescence of EuFOD3 doped into a nanoporous glass with the help of supercritical CO2

NASA Astrophysics Data System (ADS)

Bagratashvili, V. N.; Gerasimova, V. I.; Gordienko, V. M.; Tsypina, S. I.; Chutko, E. A.

2008-08-01

The kinetics of photoluminescence of a EuFOD3 metalloorganic compound doped into a nanoporous Vycor glass by the method of supercritical fluid impregnation is studied. The lifetime of luminescence of EuFOD3 molecules in pores excited by an excimer XeCl laser was 40 μs, which is considerably smaller than this lifetime (150—890 μs) in solutions. The quantum yield of luminescence of EuFOD3 was estimate as ≈4×10-4.

Y1Ba2Cu3O(7-delta) thin film dc SQUIDs (superconducting quantum interference device)

NASA Astrophysics Data System (ADS)

Racah, Daniel

1991-03-01

Direct current superconducting quantum interferometers (SQUIDs) based on HTSC thin films have been measured and characterized. The thin films used were of different quality: (1) Granular films on Sapphire substrates, prepared either by e-gun evaporation, by laser ablation or by MOCVD (metal oxide chemical vapor deposition), (2) Epitaxial films on MgO substrates. Modulations of the voltage on the SQUIDs as a function of the applied flux have been observed in a wide range of temperatures. The nature of the modulation was found to be strongly dependent on the morphology of the film and on its critical current. The SQUIDs based on granular films were relatively noisy, hysteretic and with a complicated V-phi shape. Those devices based on low quality (lowIc) granular films could be measured only at low temperatures (much lower than 77 K). While those of higher quality (granular films with high Ic) could be measured near to the superconductive transition. The SQUID based on high quality epitaxial film was measured near Tc and showed an anomalous, time dependent behavior.

Open release of the DCA++ project

NASA Astrophysics Data System (ADS)

Haehner, Urs; Solca, Raffaele; Staar, Peter; Alvarez, Gonzalo; Maier, Thomas; Summers, Michael; Schulthess, Thomas

We present the first open release of the DCA++ project, a highly scalable and efficient research code to solve quantum many-body problems with cutting edge quantum cluster algorithms. The implemented dynamical cluster approximation (DCA) and its DCA+ extension with a continuous self-energy capture nonlocal correlations in strongly correlated electron systems thereby allowing insight into high-Tc superconductivity. With the increasing heterogeneity of modern machines, DCA++ provides portable performance on conventional and emerging new architectures, such as hybrid CPU-GPU and Xeon Phi, sustaining multiple petaflops on ORNL's Titan and CSCS' Piz Daint. Moreover, we will describe how best practices in software engineering can be applied to make software development sustainable and scalable in a research group. Software testing and documentation not only prevent productivity collapse, but more importantly, they are necessary for correctness, credibility and reproducibility of scientific results. This research used resources of the Oak Ridge Leadership Computing Facility (OLCF) awarded by the INCITE program, and of the Swiss National Supercomputing Center. OLCF is a DOE Office of Science User Facility supported under Contract DE-AC05-00OR22725.

Remote Semi-State Preparation as SuperDense Quantum Teleportation

NASA Astrophysics Data System (ADS)

Bernstein, Herbert J.

2011-03-01

Recent advances in experimental technique make SuperDense Teleportation (SDT) possible. The effect uses remote state preparation to send more state-specifying parameters per bit than ordinary quantum teleportation (QT) can transmit. SDT uses a maximal entanglement to teleport the relative phases of an {n}-dimensional equimodular state. This means that one can send only {n}-1 of the total (2 n - 2) parameters -- comprising the relative phases and amplitudes -- of a general state. Nevertheless, for {n} >= 3 , SDT sends more of these state-specifying parameters than QT for a given number of classical bits. In the limit of large {n} the ratio is 2 to 1, hence the nomenclature Bennett suggested, SDT, by analogy with Super Dense Coding. Alice's measurements and Bob's transformations are simpler than in QT. The roles of Charles the state chooser, and Diana who deploys it, are different than in QT. I briefly review possible experimental realizations, including two that are under consideration at the present time by an experimental group leading in higher-dimension entanglement work. Supported in part by NSF grants PHY97-22614 & 07-58149 & KITP, UCSB, including an ITP Scholar-ship.

Construction of RNA-Quantum Dot Chimera for Nanoscale Resistive Biomemory Application.

PubMed

Lee, Taek; Yagati, Ajay Kumar; Pi, Fengmei; Sharma, Ashwani; Choi, Jeong-Woo; Guo, Peixuan

2015-07-28

RNA nanotechnology offers advantages to construct thermally and chemically stable nanoparticles with well-defined shape and structure. Here we report the development of an RNA-QD (quantum dot) chimera for resistive biomolecular memory application. Each QD holds two copies of the pRNA three-way junction (pRNA-3WJ) of the bacteriophage phi29 DNA packaging motor. The fixed quantity of two RNAs per QD was achieved by immobilizing the pRNA-3WJ with a Sephadex aptamer for resin binding. Two thiolated pRNA-3WJ serve as two feet of the chimera that stand on the gold plate. The RNA nanostructure served as both an insulator and a mediator to provide defined distance between the QD and gold. Immobilization of the chimera nanoparticle was confirmed with scanning tunneling microscopy. As revealed by scanning tunneling spectroscopy, the conjugated pRNA-3WJ-QD chimera exhibited an excellent electrical bistability signal for biomolecular memory function, demonstrating great potential for the development of resistive biomolecular memory and a nano-bio-inspired electronic device for information processing and computing.

Geometric phase effects in ultracold chemistry

NASA Astrophysics Data System (ADS)

Hazra, Jisha; Naduvalath, Balakrishnan; Kendrick, Brian K.

2016-05-01

In molecules, the geometric phase, also known as Berry's phase, originates from the adiabatic transport of the electronic wavefunction when the nuclei follow a closed path encircling a conical intersection between two electronic potential energy surfaces. It is demonstrated that the inclusion of the geometric phase has an important effect on ultracold chemical reaction rates. The effect appears in rotationally and vibrationally resolved integral cross sections as well as cross sections summed over all product quantum states. It arises from interference between scattering amplitudes of two reaction pathways: a direct path and a looping path that encircle the conical intersection between the two lowest adiabatic electronic potential energy surfaces. Illustrative results are presented for the O+ OH --> H+ O2 reaction and for hydrogen exchange in H+ H2 and D+HD reactions. It is also qualitatively demonstrated that the geometric phase effect can be modulated by applying an external electric field allowing the possibility of quantum control of chemical reactions in the ultracold regime. This work was supported in part by NSF Grant PHY-1505557 (N.B.) and ARO MURI Grant No. W911NF-12-1-0476 (N.B.).

Thermal oxidation of Si/SiGe heterostructures for use in quantum dot qubits

NASA Astrophysics Data System (ADS)

Neyens, Samuel F.; Foote, Ryan H.; Knapp, T. J.; McJunkin, Thomas; Savage, D. E.; Lagally, M. G.; Coppersmith, S. N.; Eriksson, M. A.

Here we demonstrate dry thermal oxidation of a Si/SiGe heterostructure at 700°C and use a Hall bar device to measure the mobility after oxidation to be 43,000 cm2V-1s-1 at a carrier density of 4.1 ×1011 cm-2. Surprisingly, we find no significant reduction in mobility compared with an Al2O3 device made with atomic layer deposition on the same heterostructure, indicating thermal oxidation can be used to process Si/SiGe quantum dot devices. This result provides a path for investigating improvements to the gate oxide in Si/SiGe qubit devices, whose performance is believed to be limited by charge noise in the oxide layer. This work was supported in part by ARO (W911NF-12-0607) and NSF (DMR-1206915 and PHY-1104660). Development and maintenance of the growth facilities used for fabricating samples is supported by DOE (DE-FG02-03ER46028). This research utilized NSF-supported shared facilities at the University of Wisconsin-Madison.

Construction of RNA-Quantum Dot Chimera for Nanoscale Resistive Biomemory Application

PubMed Central

Lee, Taek; Yagati, Ajay Kumar; Pi, Fengmei; Sharma, Ashwani; Choi, Jeong-Woo; Guo, Peixuan

2015-01-01

RNA nanotechnology offer advantages to construct thermally and chemically stable nanoparticles with well-defined shape and structure. Here we report the development of an RNA-Qd (quantum dot) chimera for resistive biomolecular memory application. Each Qd holds two copies of the pRNA three-way junction (pRNA-3WJ) of bacteriophage phi29 DNA-packaging motor. The fixed quantity of two RNA per Qd was achieved by immobilizing pRNA-3WJ harboring Sephadex aptamer for resin binding. Two thiolated pRNA-3WJ serves as two feet of the chimera to stand on the gold plate. The RNA nanostructure served as both an insulator and a mediator to provide defined distance between Qd and gold. Immobilization of chimera nanoparticle was confirmed through scanning tunneling microscopy (STM). As revealed by scanning tunneling spectroscopy (STS), the conjugated pRNA-3WJ-Qd chimera exhibited excellent electrical bi-stability signal for biomolecular memory function, demonstrating great potential for the development of resistive biomolecular memory and nanobio-inspired electronic device for information processing and computing. PMID:26135474

Separation of photoactive conformers based on hindered diarylethenes: efficient modulation in photocyclization quantum yields.

PubMed

Li, Wenlong; Jiao, Changhong; Li, Xin; Xie, Yongshu; Nakatani, Keitaro; Tian, He; Zhu, Weihong

2014-04-25

Endowing both solvent independency and excellent thermal bistability, the benzobis(thiadiazole)-bridged diarylethene system provides an efficient approach to realize extremely high photocyclization quantum yields (Φo-c , up to 90.6 %) by both separating completely pure anti-parallel conformer and suppressing intramolecular charge transfer (ICT). © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

The Novel Phages phiCD5763 and phiCD2955 Represent Two Groups of Big Plasmidial Siphoviridae Phages of Clostridium difficile.

PubMed

Ramírez-Vargas, Gabriel; Goh, Shan; Rodríguez, César

2018-01-01

Until recently, Clostridium difficile phages were limited to Myoviruses and Siphoviruses of medium genome length (32-57 kb). Here we report the finding of phiCD5763, a Siphovirus with a large extrachromosomal circular genome (132.5 kb, 172 ORFs) and a large capsid (205.6 ± 25.6 nm in diameter) infecting MLST Clade 1 strains of C. difficile . Two subgroups of big phage genomes similar to phiCD5763 were identified in 32 NAP CR1 /RT012/ST-54 C. difficile isolates from Costa Rica and in whole genome sequences (WGS) of 41 C. difficile isolates of Clades 1, 2, 3, and 4 from Canada, USA, UK, Belgium, Iraq, and China. Through comparative genomics we discovered another putative big phage genome in a non-NAP CR1 isolate from Costa Rica, phiCD2955, which represents other big phage genomes found in 130 WGS of MLST Clade 1 and 2 isolates from Canada, USA, Hungary, France, Austria, and UK. phiCD2955 (131.6 kb, 172 ORFs) is related to a previously reported C. difficile phage genome, phiCD211/phiCDIF1296T. Detailed genome analyses of phiCD5763, phiCD2955, phiCD211/phiCDIF1296T, and seven other putative C. difficile big phage genome sequences of 131-136 kb reconstructed from publicly available WGS revealed a modular gene organization and high levels of sequence heterogeneity at several hotspots, suggesting that these genomes correspond to biological entities undergoing recombination. Compared to other C. difficile phages, these big phages have unique predicted terminase, capsid, portal, neck and tail proteins, receptor binding proteins (RBPs), recombinases, resolvases, primases, helicases, ligases, and hypothetical proteins. Moreover, their predicted gene load suggests a complex regulation of both phage and host functions. Overall, our results indicate that the prevalence of C. difficile big bacteriophages is more widespread than realized and open new avenues of research aiming to decipher how these viral elements influence the biology of this emerging pathogen.

Release and bioactivity of bone morphogenetic protein-2 are affected by scaffold binding techniques in vitro and in vivo.

PubMed

Suliman, Salwa; Xing, Zhe; Wu, Xujun; Xue, Ying; Pedersen, Torbjorn O; Sun, Yang; Døskeland, Anne P; Nickel, Joachim; Waag, Thilo; Lygre, Henning; Finne-Wistrand, Anna; Steinmüller-Nethl, Doris; Krueger, Anke; Mustafa, Kamal

2015-01-10

A low dose of 1μg rhBMP-2 was immobilised by four different functionalising techniques on recently developed poly(l-lactide)-co-(ε-caprolactone) [(poly(LLA-co-CL)] scaffolds. It was either (i) physisorbed on unmodified scaffolds [PHY], (ii) physisorbed onto scaffolds modified with nanodiamond particles [nDP-PHY], (iii) covalently linked onto nDPs that were used to modify the scaffolds [nDP-COV] or (iv) encapsulated in microspheres distributed on the scaffolds [MICS]. Release kinetics of BMP-2 from the different scaffolds was quantified using targeted mass spectrometry for up to 70days. PHY scaffolds had an initial burst of release while MICS showed a gradual and sustained increase in release. In contrast, NDP-PHY and nDP-COV scaffolds showed no significant release, although nDP-PHY scaffolds maintained bioactivity of BMP-2. Human mesenchymal stem cells cultured in vitro showed upregulated BMP-2 and osteocalcin gene expression at both week 1 and week 3 in the MICS and nDP-PHY scaffold groups. These groups also demonstrated the highest BMP-2 extracellular protein levels as assessed by ELISA, and mineralization confirmed by Alizarin red. Cells grown on the PHY scaffolds in vitro expressed collagen type 1 alpha 2 early but the scaffold could not sustain rhBMP-2 release to express mineralization. After 4weeks post-implantation using a rat mandible critical-sized defect model, micro-CT and Masson trichrome results showed accelerated bone regeneration in the PHY, nDP-PHY and MICS groups. The results demonstrate that PHY scaffolds may not be desirable for clinical use, since similar osteogenic potential was not seen under both in vitro and in vivo conditions, in contrast to nDP-PHY and MICS groups, where continuous low doses of BMP-2 induced satisfactory bone regeneration in both conditions. The nDP-PHY scaffolds used here in critical-sized bone defects for the first time appear to have promise compared to growth factors adsorbed onto a polymer alone and the short distance effect prevents adverse systemic side effects. Copyright © 2014. Published by Elsevier B.V.

Photodissociation of quantum state-selected diatomic molecules yields new insight into ultracold chemistry

NASA Astrophysics Data System (ADS)

McDonald, Mickey; McGuyer, Bart H.; Lee, Chih-Hsi; Apfelbeck, Florian; Zelevinsky, Tanya

2016-05-01

When a molecule is subjected to a sufficiently energetic photon it can break apart into fragments through a process called ``photodissociation''. For over 70 years this simple chemical reaction has served as a vital experimental tool for acquiring information about molecular structure, since the character of the photodissociative transition can be inferred by measuring the 3D photofragment angular distribution (PAD). While theoretical understanding of this process has gradually evolved from classical considerations to a fully quantum approach, experiments to date have not yet revealed the full quantum nature of this process. In my talk I will describe recent experiments involving the photodissociation of ultracold, optical lattice-trapped, and fully quantum state-resolved 88Sr2 molecules. Optical absorption images of the PADs produced in these experiments reveal features which are inherently quantum mechanical in nature, such as matter-wave interference between output channels, and are sensitive to the quantum statistics of the molecular wavefunctions. The results of these experiments cannot be predicted using quasiclassical methods. Instead, we describe our results with a fully quantum mechanical model yielding new intuition about ultracold chemistry.

Intracellular pH in mammalian stages of Trypanosoma cruzi is K+-dependent and regulated by H+-ATPases.

PubMed

Van Der Heyden, N; Docampo, R

2000-02-05

Regulation of intracellular pH (pHi) was investigated in Trypanosoma cruzi amastigotes and trypomastigotes using 2',7'-bis-(carboxyethyl)-5(and-6)-carboxyfluorescein (BCECF). pHi was determined to be 7.33 +/- 0.08 and 7.35 +/- 0.07 in amastigotes and trypomastigotes, respectively, and there were no significant differences in the regulation of pH, between the two stages. Steady-state pHi, recovery of pHi from acidification, and H+-efflux were all decreased markedly by the H+-ATPase inhibitors N,N'-dicyclohexylcarbodi-imide (DCCD), diethylstilbestrol (DES) and N-ethylmaleimide (NEM) supporting a significant role for a plasma membrane H+-ATPase in the regulation of pHi. pHi was maintained at neutrality over a range of external pH (pHe) from 5-8 in parasites suspended in a buffer containing Na+ and K+ (standard buffer) but was acidified at low pHe in the absence of these cations (choline buffer). The pHi of trypomastigotes decreased significantly when they transformed into amastigotes. The rate of recovery of pHi by acidified parasites was similar in Na+-free buffer and standard buffer but was slower in the absence of K+ (K+-free or choline buffer) and parasites suspended in choline buffer were acidic by 0.25 pH units as compared with controls. Ba2+ and Cs+ decreased the pHi of parasites suspended in standard but not choline buffer suggesting the presence of an inward directed K+ channel. The pHi of amastigotes and trypomastigotes suspended in Cl(-)-free buffer was decreased by 0.13 and 0.2 pH units, respectively, supporting the presence of a chloride conductive channel. No evidence of pH regulation via a Na+/H+ or Cl-/HCO3- exchanger was found. These results are consistent with the presence of a plasma membrane H+-ATPase that regulates pHi and is supported by K+ and Cl- channels.

Medically Unexplained and Explained Physical Symptoms in the General Population: Association with Prevalent and Incident Mental Disorders

PubMed Central

van Eck van der Sluijs, Jonna; ten Have, Margreet; Rijnders, Cees; van Marwijk, Harm; de Graaf, Ron; van der Feltz-Cornelis, Christina

2015-01-01

Background Clinical studies have shown that Medically Unexplained Symptoms (MUS) are related to common mental disorders. It is unknown how often common mental disorders occur in subjects who have explained physical symptoms (PHY), MUS or both, in the general population, what the incidence rates are, and whether there is a difference between PHY and MUS in this respect. Aim To study the prevalence and incidence rates of mood, anxiety and substance use disorders in groups with PHY, MUS and combined MUS and PHY compared to a no-symptoms reference group in the general population. Method Data were derived from the Netherlands Mental Health Survey and Incidence Study-2 (NEMESIS-2), a nationally representative face-to-face survey of the general population aged 18-64 years. We selected subjects with explained physical symptoms only (n=1952), with MUS only (n=177), with both MUS and PHY (n=209), and a reference group with no physical symptoms (n=4168). The assessment of common mental disorders was through the Composite International Diagnostic Interview 3.0. Multivariate logistic regression analyses were used to examine the association between group membership and the prevalence and first-incidence rates of comorbid mental disorders, adjusted for socio-demographic characteristics. Results MUS were associated with the highest prevalence rates of mood and anxiety disorders, and combined MUS and PHY with the highest prevalence rates of substance disorder. Combined MUS and PHY were associated with a higher incidence rate of mood disorder only (OR 2.9 (95%CI:1.27,6.74)). Conclusion In the general population, PHY, MUS and the combination of both are related to mood and anxiety disorder, but odds are highest for combined MUS and PHY in relation to substance use disorder. Combined MUS and PHY are related to a greater incidence of mood disorder. These findings warrant further research into possibilities to improve recognition and early intervention in subjects with combined MUS and PHY. PMID:25853676

Aqueous synthesis of high bright and tunable near-infrared AgInSe2-ZnSe quantum dots for bioimaging.

PubMed

Che, Dongchen; Zhu, Xiaoxu; Wang, Hongzhi; Duan, Yourong; Zhang, Qinghong; Li, Yaogang

2016-02-01

Efficient synthetic methods for near-infrared quantum dots with good biophysical properties as bioimaging agents are urgently required. In this work, a simple and fast synthesis of highly luminescent, near-infrared AgInSe2-ZnSe quantum dots (QDs) with tunable emissions in aqueous media is reported. This method avoids high temperature and pressure and organic solvents to directly generate water-dispersible AgInSe2-ZnSe QDs. The photoluminescence emission peak of the AgInSe2-ZnSe QDs ranged from 625 to 940nm, with quantum yields up to 31%. The AgInSe2-ZnSe QDs with high quantum yield, near-infrared and low cytotoxic could be used as good cell labels, showing great potential applications in bio-imaging. Copyright © 2015 Elsevier Inc. All rights reserved.

Quantum yield for carbon monoxide production in the 248 nm photodissociation of carbonyl sulfide (OCS)

NASA Technical Reports Server (NTRS)

Zhao, Z.; Stickel, R. E.; Wine, P. H.

1995-01-01

Tunable diode laser absorption spectroscopy has been coupled with excimer laser flash photolysis to measure the quantum yield for CO production from 248 nm photodissociation of carbonyl sulfide (OCS) relative to the well-known quantum yield for CO production from 248 nm photolysis of phosgene (Cl2CO2). The temporal resolution of the experiments was sufficient to distinguish CO formed directly by photodissociation from that formed by subsequent S((sup 3)P(sub J)) reaction with OCS. Under the experimental conditions employed, CO formation via the fast S((sup 1)D(sub 2)) + OCS reaction was minimal. Measurements at 297K and total pressures from 4 to 100 Torr N2 + N2O show the CO yield to be greater than 0.95 and most likely unity. This result suggests that the contribution of OCS as a precursor to the lower stratospheric sulfate aerosol layer is somewhat larger than previously thought.

Specific binding of (/sup 3/H-Tyr8)physalaemin to rat submaxillary gland substance P receptor

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

Bahouth, S.W.; Lazaro, D.M.; Brundish, D.E.

1985-01-01

(/sup 3/H)Physalaemin ((/sup 3/H)PHY) binds to a single class of noninteracting sites on rat submaxillary gland membranes suspended in high ionic strength media with a KD of 2.7 nM, a Bmax of 240 fmol/mg of protein, and low nonspecific binding. The relative potencies of substance P (SP) and its fragments in competing with (/sup 3/H)PHY correlate with their relative salivation potencies. This indicates that (/sup 3/H)PHY interacts with a physiologically relevant SP receptor. In low ionic strength media, the KD of (/sup 3/H)PHY does not change, but SP and some of its fragments are more potent than PHY in competingmore » with (/sup 3/H) PHY. Computer-assisted analysis of (/sup 3/H)PHY and (/sup 3/H)SP binding in high and low ionic strength media demonstrated that both peptides are equipotent in high ionic strength but that the affinity of SP increases by 70-fold in low ionic strength. The SP fragments that contain a basic residue in positions 1 and/or 3 also display an increased affinity in low ionic strength. These findings document that (/sup 3/H)PHY binding in high ionic strength (mu . 0.6) accurately reflects the pharmacological potencies of agonists on the SP-P receptor. The binding of (/sup 3/H)PHY, like that of (/sup 3/H)SP, increases by the addition of divalent cations (Mg2+ greater than Ca2+ greater than Mn2+). Guanine nucleotides decrease (/sup 3/H)PHY binding by decreasing the Bmax to the same level (160 fmol/mg of protein), in the presence or absence of Mg2+.« less

Evolutionary divergence of phytochrome protein function in Zea mays PIF3 signaling.

PubMed

Kumar, Indrajit; Swaminathan, Kankshita; Hudson, Karen; Hudson, Matthew E

2016-07-01

Two maize phytochrome-interacting factor (PIF) basic helix-loop-helix (bHLH) family members, ZmPIF3.1 and ZmPIF3.2, were identified, cloned and expressed in vitro to investigate light-signaling interactions. A phylogenetic analysis of sequences of the maize bHLH transcription factor gene family revealed the extent of the PIF family, and a total of seven predicted PIF-encoding genes were identified from genes encoding bHLH family VIIa/b proteins in the maize genome. To investigate the role of maize PIFs in phytochrome signaling, full-length cDNAs for phytochromes PhyA2, PhyB1, PhyB2 and PhyC1 from maize were cloned and expressed in vitro as chromophorylated holophytochromes. We showed that ZmPIF3.1 and ZmPIF3.2 interact specifically with the Pfr form of maize holophytochrome B1 (ZmphyB1), showing no detectable affinity for the Pr form. Maize holophytochrome B2 (ZmphyB2) showed no detectable binding affinity for PIFs in either Pr or Pfr forms, but phyB Pfr from Arabidopsis interacted with ZmPIF3.1 similarly to ZmphyB1 Pfr. We conclude that subfunctionalization at the protein-protein interaction level has altered the role of phyB2 relative to that of phyB1 in maize. Since the phyB2 mutant shows photomorphogenic defects, we conclude that maize phyB2 is an active photoreceptor, without the binding of PIF3 seen in other phyB family proteins. © The Author 2016. Published by Oxford University Press on behalf of the Society for Experimental Biology.

Plasma HIV viral rebound following protocol-indicated cessation of ART commenced in primary and chronic HIV infection.

PubMed

Hamlyn, Elizabeth; Ewings, Fiona M; Porter, Kholoud; Cooper, David A; Tambussi, Giuseppe; Schechter, Mauro; Pedersen, Court; Okulicz, Jason F; McClure, Myra; Babiker, Abdel; Weber, Jonathan; Fidler, Sarah

2012-01-01

The magnitude of HIV viral rebound following ART cessation has consequences for clinical outcome and onward transmission. We compared plasma viral load (pVL) rebound after stopping ART initiated in primary (PHI) and chronic HIV infection (CHI). Two populations with protocol-indicated ART cessation from SPARTAC (PHI, n = 182) and SMART (CHI, n = 1450) trials. Time for pVL to reach pre-ART levels after stopping ART was assessed in PHI using survival analysis. Differences in pVL between PHI and CHI populations 4 weeks after stopping ART were examined using linear and logistic regression. Differences in pVL slopes up to 48 weeks were examined using linear mixed models and viral burden was estimated through a time-averaged area-under-pVL curve. CHI participants were categorised by nadir CD4 at ART stop. Of 171 PHI participants, 71 (41.5%) rebounded to pre-ART pVL levels, at a median of 50 (95% CI 48-51) weeks after stopping ART. Four weeks after stopping treatment, although the proportion with pVL ≥ 400 copies/ml was similar (78% PHI versus 79% CHI), levels were 0.45 (95% CI 0.26-0.64) log(10) copies/ml lower for PHI versus CHI, and remained lower up to 48 weeks. Lower CD4 nadir in CHI was associated with higher pVL after ART stop. Rebound for CHI participants with CD4 nadir >500 cells/mm(3) was comparable to that experienced by PHI participants. Stopping ART initiated in PHI and CHI was associated with viral rebound to levels conferring increased transmission risk, although the level of rebound was significantly lower and sustained in PHI compared to CHI.

A Systematic Review and Meta-analysis of the Diagnostic Accuracy of Prostate Health Index and 4-Kallikrein Panel Score in Predicting Overall and High-grade Prostate Cancer.

PubMed

Russo, Giorgio Ivan; Regis, Federica; Castelli, Tommaso; Favilla, Vincenzo; Privitera, Salvatore; Giardina, Raimondo; Cimino, Sebastiano; Morgia, Giuseppe

2017-08-01

Markers for prostate cancer (PCa) have progressed over recent years. In particular, the prostate health index (PHI) and the 4-kallikrein (4K) panel have been demonstrated to improve the diagnosis of PCa. We aimed to review the diagnostic accuracy of PHI and the 4K panel for PCa detection. We performed a systematic literature search of PubMed, EMBASE, Cochrane, and Academic One File databases until July 2016. We included diagnostic accuracy studies that used PHI or 4K panel for the diagnosis of PCa or high-grade PCa. The methodological quality was assessed using the Quality Assessment of Diagnostic Accuracy Studies (QUADAS-2) tool. Twenty-eight studies including 16,762 patients have been included for the analysis. The pooled data showed a sensitivity of 0.89 and 0.74 for PHI and 4K panel, respectively, for PCa detection and a pooled specificity of 0.34 and 0.60 for PHI and 4K panel, respectively. The derived area under the curve (AUC) from the hierarchical summary receiver operating characteristic (HSROC) showed an accuracy of 0.76 and 0.72 for PHI and 4K panel respectively. For high-grade PCa detection, the pooled sensitivity was 0.93 and 0.87 for PHI and 4K panel, respectively, whereas the pooled specificity was 0.34 and 0.61 for PHI and 4K panel, respectively. The derived AUC from the HSROC showed an accuracy of 0.82 and 0.81 for PHI and 4K panel, respectively. Both PHI and the 4K panel provided good diagnostic accuracy in detecting overall and high-grade PCa. Copyright © 2016 Elsevier Inc. All rights reserved.

An Integrative Model for Phytochrome B Mediated Photomorphogenesis: From Protein Dynamics to Physiology

PubMed Central

Kircher, Stefan; Kirchenbauer, Daniel; Timmer, Jens; Nagy, Ferenc; Schäfer, Eberhard; Fleck, Christian

2010-01-01

Background Plants have evolved various sophisticated mechanisms to respond and adapt to changes of abiotic factors in their natural environment. Light is one of the most important abiotic environmental factors and it regulates plant growth and development throughout their entire life cycle. To monitor the intensity and spectral composition of the ambient light environment, plants have evolved multiple photoreceptors, including the red/far-red light-sensing phytochromes. Methodology/Principal Findings We have developed an integrative mathematical model that describes how phytochrome B (phyB), an essential receptor in Arabidopsis thaliana, controls growth. Our model is based on a multiscale approach and connects the mesoscopic intracellular phyB protein dynamics to the macroscopic growth phenotype. To establish reliable and relevant parameters for the model phyB regulated growth we measured: accumulation and degradation, dark reversion kinetics and the dynamic behavior of different nuclear phyB pools using in vivo spectroscopy, western blotting and Fluorescence Recovery After Photobleaching (FRAP) technique, respectively. Conclusions/Significance The newly developed model predicts that the phyB-containing nuclear bodies (NBs) (i) serve as storage sites for phyB and (ii) control prolonged dark reversion kinetics as well as partial reversibility of phyB Pfr in extended darkness. The predictive power of this mathematical model is further validated by the fact that we are able to formalize a basic photobiological observation, namely that in light-grown seedlings hypocotyl length depends on the total amount of phyB. In addition, we demonstrate that our theoretical predictions are in excellent agreement with quantitative data concerning phyB levels and the corresponding hypocotyl lengths. Hence, we conclude that the integrative model suggested in this study captures the main features of phyB-mediated photomorphogenesis in Arabidopsis. PMID:20502669

Evaluation of the Xeon phi processor as a technology for the acceleration of real-time control in high-order adaptive optics systems

NASA Astrophysics Data System (ADS)

Barr, David; Basden, Alastair; Dipper, Nigel; Schwartz, Noah; Vick, Andy; Schnetler, Hermine

2014-08-01

We present wavefront reconstruction acceleration of high-order AO systems using an Intel Xeon Phi processor. The Xeon Phi is a coprocessor providing many integrated cores and designed for accelerating compute intensive, numerical codes. Unlike other accelerator technologies, it allows virtually unchanged C/C++ to be recompiled to run on the Xeon Phi, giving the potential of making development, upgrade and maintenance faster and less complex. We benchmark the Xeon Phi in the context of AO real-time control by running a matrix vector multiply (MVM) algorithm. We investigate variability in execution time and demonstrate a substantial speed-up in loop frequency. We examine the integration of a Xeon Phi into an existing RTC system and show that performance improvements can be achieved with limited development effort.

A search for a doubly-charged Higgs boson in pp collisions at $$\\sqrt{s} = 7 \\ \\mbox{TeV}$$

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

Chatrchyan, S.; Khachatryan, V.; Sirunyan, A. M.

A search for a doubly-charged Higgs boson in pp collisions atmore » $$ \\sqrt{s}=7 $$ TeV is presented. The data correspond to an integrated luminosity of 4.9 inverse femtobarns, collected by the CMS experiment at the LHC. The search is performed using events with three or more isolated charged leptons of any flavor, giving sensitivity to the decays of pair-produced triplet components Phi[++]Phi[--], and Phi[++]Phi[-] from associated production. No excess is observed compared to the background prediction, and upper limits at the 95% confidence level are set on the Phi[++] production cross section, under specific assumptions on its branching fractions. Lower bounds on the Phi[++] mass are reported, providing significantly more stringent constraints than previously published limits.« less

Effects of intracellular pH on the mitotic apparatus and mitotic stage in the sand dollar egg.

PubMed

Watanabe, K; Hamaguchi, M S; Hamaguchi, Y

1997-01-01

The effect of change in intracellular pH (pHi) on mitosis was investigated in the sand dollar egg. The pHi in the fertilized egg of Scaphechinus mirabilis and Clypeaster japonicus, which was 7.34 and 7.31, respectively, changed by means of treating the egg at nuclear envelope breakdown with sea water containing acetate and/or ammonia at various values of pH. The mitotic apparatus at pHi 6.70 became larger than that of normal fertilized eggs; that is, the mitotic spindle had the maximal size, especially in length at pHi 6.70. The spindle length linearly decreased when pHi increased from 6.70 to 7.84. By polarization microscopy, the increase in birefringence retardation was detected at slightly acidic pHi, suggesting that the increase in size of the spindle is caused by the increase in the amount of microtubules in the spindle. At pHi 6.30, the organization of the mitotic apparatus was inhibited. Furthermore, slightly acidic pHi caused cleavage retardation or inhibition. By counting the number of the eggs at various mitotic stages with time after treating them with the media, it is found that metaphase was persistent and most of the S. mirabilis eggs were arrested at metaphase under the condition of pHi 6.70. It is concluded that at slightly acidic pH, the microtubules in the spindle are stabilized and more microtubules assembled than those in the normal eggs.

Multisite Light-Induced Phosphorylation of the Transcription Factor PIF3 Is Necessary for Both Its Rapid Degradation and Concomitant Negative Feedback Modulation of Photoreceptor phyB Levels in Arabidopsis[C][W

PubMed Central

Ni, Weimin; Xu, Shou-Ling; Chalkley, Robert J.; Pham, Thao Nguyen D.; Guan, Shenheng; Maltby, Dave A.; Burlingame, Alma L.; Wang, Zhi-Yong; Quail, Peter H.

2013-01-01

Plants constantly monitor informational light signals using sensory photoreceptors, which include the phytochrome (phy) family (phyA to phyE), and adjust their growth and development accordingly. Following light-induced nuclear translocation, photoactivated phy molecules bind to and induce rapid phosphorylation and degradation of phy-interacting basic Helix Loop Helix (bHLH) transcription factors (PIFs), such as PIF3, thereby regulating the expression of target genes. However, the mechanisms underlying the signal-relay process are still not fully understood. Here, using mass spectrometry, we identify multiple, in vivo, light-induced Ser/Thr phosphorylation sites in PIF3. Using transgenic expression of site-directed mutants of PIF3, we provide evidence that a set of these phosphorylation events acts collectively to trigger rapid degradation of the PIF3 protein in response to initial exposure of dark-grown seedlings to light. In addition, we show that phyB-induced PIF3 phosphorylation is also required for the known negative feedback modulation of phyB levels in prolonged light, potentially through codegradation of phyB and PIF3. This mutually regulatory intermolecular transaction thus provides a mechanism with the dual capacity to promote early, graded, or threshold regulation of the primary, PIF3-controlled transcriptional network in response to initial light exposure, and later, to attenuate global sensitivity to the light signal through reductions in photoreceptor levels upon prolonged exposure. PMID:23903316

Culture expansion of adipose derived stromal cells. A closed automated Quantum Cell Expansion System compared with manual flask-based culture.

PubMed

Haack-Sørensen, Mandana; Follin, Bjarke; Juhl, Morten; Brorsen, Sonja K; Søndergaard, Rebekka H; Kastrup, Jens; Ekblond, Annette

2016-11-16

Adipose derived stromal cells (ASCs) are a rich and convenient source of cells for clinical regenerative therapeutic approaches. However, applications of ASCs often require cell expansion to reach the needed dose. In this study, cultivation of ASCs from stromal vascular fraction (SVF) over two passages in the automated and functionally closed Quantum Cell Expansion System (Quantum system) is compared with traditional manual cultivation. Stromal vascular fraction was isolated from abdominal fat, suspended in α-MEM supplemented with 10% Fetal Bovine Serum and seeded into either T75 flasks or a Quantum system that had been coated with cryoprecipitate. The cultivation of ASCs from SVF was performed in 3 ways: flask to flask; flask to Quantum system; and Quantum system to Quantum system. In all cases, quality controls were conducted for sterility, mycoplasmas, and endotoxins, in addition to the assessment of cell counts, viability, immunophenotype, and differentiation potential. The viability of ASCs passage 0 (P0) and P1 was above 96%, regardless of cultivation in flasks or Quantum system. Expression of surface markers and differentiation potential was consistent with ISCT/IFATS standards for the ASC phenotype. Sterility, mycoplasma, and endotoxin tests were consistently negative. An average of 8.0 × 10 7 SVF cells loaded into a Quantum system yielded 8.96 × 10 7 ASCs P0, while 4.5 × 10 6 SVF cells seeded per T75 flask yielded an average of 2.37 × 10 6 ASCs-less than the number of SVF cells seeded. ASCs P1 expanded in the Quantum system demonstrated a population doubling (PD) around 2.2 regardless of whether P0 was previously cultured in flasks or Quantum, while ASCs P1 in flasks only reached a PD of 1.0. Manufacturing of ASCs in a Quantum system enhances ASC expansion rate and yield significantly relative to manual processing in T-flasks, while maintaining the purity and quality essential to safe and robust cell production. Notably, the use of the Quantum system entails significantly reduced working hours and thereby costs.

Analysis of wavelength-dependent photoisomerization quantum yields in bilirubins by fitting two exciton absorption bands

NASA Astrophysics Data System (ADS)

Mazzoni, M.; Agati, G.; Troup, G. J.; Pratesi, R.

2003-09-01

The absorption spectra of bilirubins were deconvoluted by two Gaussian curves of equal width representing the exciton bands of the non-degenerate molecular system. The two bands were used to study the wavelength dependence of the (4Z, 15Z) rightarrow (4Z, 15E) configurational photoisomerization quantum yield of the bichromophoric bilirubin-IXalpha (BR-IX), the intrinsically asymmetric bile pigment associated with jaundice and the symmetrically substituted bilirubins (bilirubin-IIIalpha and mesobilirubin-XIIIalpha), when they are irradiated in aqueous solution bound to human serum albumin (HSA). The same study was performed for BR-IX in ammoniacal methanol solution (NH4OH/MeOH). The quantum yields of the configurational photoprocesses were fitted with a combination function of the two Gaussian bands normalized to the total absorption, using the proportionality coefficients and a scaling factor as parameters. The decrease of the (4Z, 15Z) rightarrow (4Z, 15E) quantum yield with increasing wavelength, which occurs for wavelengths longer than the most probable Franck-Condon transition of the molecule, did not result in a unique function of the exciton absorptions. In particular we found two ranges corresponding to different exciton interactions with different proportionality coefficients and scaling factors. The wavelength-dependent photoisomerization of bilirubins was described as an abrupt change in quantum yield as soon as the resulting excitation was strongly localized in each chromophore. The change was correlated to a variation of the interaction between the two chromophores when the short-wavelength exciton absorption became vanishingly small. With the help of the circular dichroism (CD) spectrum of BR-IX in HSA, a small band was resolved in the bilirubin absorption spectrum, delivering part of the energy required for the (4Z, 15Z) rightarrow (4Z, 15E) photoisomerization of the molecule.

Comparisons of Photosynthetic Responses of Xanthium strumarium and Helianthus annuus to Chronic and Acute Water Stress in Sun and Shade 1

PubMed Central

Ben, Gui-Ying; Osmond, C. Barry; Sharkey, Thomas D.

1987-01-01

We have examined the effects of mild, chronic water stress and acute water stress on two water stress sensitive plants, Xanthium strumarium and Helianthus annuus. Using a combination of the leaf disc O2 electrode to measure the light responses of photosynthesis and 77 K fluorescence to monitor damage to the primary photochemistry, we have found the following: (a) The CO2 saturated rate of photosynthesis at high light is the most water stress sensitive parameter measured. (b) The apparent quantum yield (moles O2 per mole photons) was slightly, if at all, affected by mild water stress (>−1.5 megapascals). (c) Severe water stress (<−1.5 megapascals) reduced the quantum yield of photosynthesis regardless of whether the stress was applied in sun or shade. The light independent reduction of quantum yield was not associated with a reduction in 77 K fluorescence (Fv/Fm) indicating that the quantum yield reduction was not the result of damage to primary photochemistry. (d) The diel fluctuation in 77 K fluorescence seen in sun-exposed control leaves was greatly exaggerated in water stressed leaves because of enhanced decline in 77 K fluorescence in the morning. The rate of recovery was similar in both control and water stressed leaves. Shaded leaves showed no change in 77 K fluorescence regardless of whether water stress was imposed or not. (e) The water stress sensitive plants used in these experiments did not recover from acute water stress severe enough to reduce the quantum yield or chronic water stress which lasted long enough that light dependent damage to primary photochemistry occurred. PMID:16665465

Comparisons of Photosynthetic Responses of Xanthium strumarium and Helianthus annuus to Chronic and Acute Water Stress in Sun and Shade.

PubMed

Ben, G Y; Osmond, C B; Sharkey, T D

1987-06-01

We have examined the effects of mild, chronic water stress and acute water stress on two water stress sensitive plants, Xanthium strumarium and Helianthus annuus. Using a combination of the leaf disc O(2) electrode to measure the light responses of photosynthesis and 77 K fluorescence to monitor damage to the primary photochemistry, we have found the following: (a) The CO(2) saturated rate of photosynthesis at high light is the most water stress sensitive parameter measured. (b) The apparent quantum yield (moles O(2) per mole photons) was slightly, if at all, affected by mild water stress (>-1.5 megapascals). (c) Severe water stress (<-1.5 megapascals) reduced the quantum yield of photosynthesis regardless of whether the stress was applied in sun or shade. The light independent reduction of quantum yield was not associated with a reduction in 77 K fluorescence (F(v)/F(m)) indicating that the quantum yield reduction was not the result of damage to primary photochemistry. (d) The diel fluctuation in 77 K fluorescence seen in sun-exposed control leaves was greatly exaggerated in water stressed leaves because of enhanced decline in 77 K fluorescence in the morning. The rate of recovery was similar in both control and water stressed leaves. Shaded leaves showed no change in 77 K fluorescence regardless of whether water stress was imposed or not. (e) The water stress sensitive plants used in these experiments did not recover from acute water stress severe enough to reduce the quantum yield or chronic water stress which lasted long enough that light dependent damage to primary photochemistry occurred.

Elastic and transport cross sections for inert gases in a hydrogen plasma

NASA Astrophysics Data System (ADS)

Krstic, Predrag

2005-05-01

Accurate elastic differential and integral scattering and transport cross sections have been computed using a fully quantum-mechanical approach for hydrogen ions (H^+, D^+ and T^+) colliding with Neon, Krypton and Xenon, in the center of mass energy range 0.1 to 200 eV. The momentum transfer and viscosity cross sections have been extended to higher keV collision energies using a classical, three-body scattering method. The results were compared with previously calculated values for Argon and Helium, as well as with simple analytical models. The cross sections, tabulated and available through the world wide web (www-cfadc.phy.ornl.gov) are of significance in fusion plasma modeling, gaseous electronics and other plasma applications.

Uncertainty relation for the discrete Fourier transform.

PubMed

Massar, Serge; Spindel, Philippe

2008-05-16

We derive an uncertainty relation for two unitary operators which obey a commutation relation of the form UV=e(i phi) VU. Its most important application is to constrain how much a quantum state can be localized simultaneously in two mutually unbiased bases related by a discrete fourier transform. It provides an uncertainty relation which smoothly interpolates between the well-known cases of the Pauli operators in two dimensions and the continuous variables position and momentum. This work also provides an uncertainty relation for modular variables, and could find applications in signal processing. In the finite dimensional case the minimum uncertainty states, discrete analogues of coherent and squeezed states, are minimum energy solutions of Harper's equation, a discrete version of the harmonic oscillator equation.

Development of optimal models of porous media by combining static and dynamic data: the permeability and porosity distributions.

PubMed

Hamzehpour, Hossein; Rasaei, M Reza; Sahimi, Muhammad

2007-05-01

We describe a method for the development of the optimal spatial distributions of the porosity phi and permeability k of a large-scale porous medium. The optimal distributions are constrained by static and dynamic data. The static data that we utilize are limited data for phi and k, which the method honors in the optimal model and utilizes their correlation functions in the optimization process. The dynamic data include the first-arrival (FA) times, at a number of receivers, of seismic waves that have propagated in the porous medium, and the time-dependent production rates of a fluid that flows in the medium. The method combines the simulated-annealing method with a simulator that solves numerically the three-dimensional (3D) acoustic wave equation and computes the FA times, and a second simulator that solves the 3D governing equation for the fluid's pressure as a function of time. To our knowledge, this is the first time that an optimization method has been developed to determine simultaneously the global minima of two distinct total energy functions. As a stringent test of the method's accuracy, we solve for flow of two immiscible fluids in the same porous medium, without using any data for the two-phase flow problem in the optimization process. We show that the optimal model, in addition to honoring the data, also yields accurate spatial distributions of phi and k, as well as providing accurate quantitative predictions for the single- and two-phase flow problems. The efficiency of the computations is discussed in detail.

Elevated Prostate Health Index (phi) and Biopsy Reclassification During Active Surveillance of Prostate Cancer.

PubMed

Andreas, Darian; Tosoian, Jeffrey J; Landis, Patricia; Wolf, Sacha; Glavaris, Stephanie; Lotan, Tamara L; Schaeffer, Edward M; Sokoll, Lori J; Ross, Ashley E

2016-07-01

The Prostate Health Index (phi) has been FDA approved for decision-making regarding prostate biopsy. Phi has additionally been shown to positively correlate with tumor volume, extraprostatic disease and higher Gleason grade tumors. Here we describe a case in which an elevated phi encouraged biopsy of a gentleman undergoing active surveillance leading to reclassification of his disease as high risk prostate cancer.

Dye to use with virus challenge for testing barrier materials.

PubMed Central

Lytle, C D; Felten, R P; Truscott, W

1991-01-01

Can FD&C Blue no. 1 dye photoinactivate bacteriophages phi X174, T7, PRD1, and phi 6 under laboratory lighting conditions? At high levels of light, the dye (500 microM) photoinactivated only phi 6. Thus, this dye can be used at concentrations up to 500 microM with bacteriophages phi X174, T7, and PRD1 to test barrier material integrity. PMID:1872612

Tiny abortive initiation transcripts exert antitermination activity on an RNA hairpin-dependent intrinsic terminator.

PubMed

Lee, Sooncheol; Nguyen, Huong Minh; Kang, Changwon

2010-10-01

No biological function has been identified for tiny RNA transcripts that are abortively and repetitiously released from initiation complexes of RNA polymerase in vitro and in vivo to date. In this study, we show that abortive initiation affects termination in transcription of bacteriophage T7 gene 10. Specifically, abortive transcripts produced from promoter phi 10 exert trans-acting antitermination activity on terminator T phi both in vitro and in vivo. Following abortive initiation cycling of T7 RNA polymerase at phi 10, short G-rich and oligo(G) RNAs were produced and both specifically sequestered 5- and 6-nt C + U stretch sequences, consequently interfering with terminator hairpin formation. This antitermination activity depended on sequence-specific hybridization of abortive transcripts with the 5' but not 3' half of T phi RNA. Antitermination was abolished when T phi was mutated to lack a C + U stretch, but restored when abortive transcript sequence was additionally modified to complement the mutation in T phi, both in vitro and in vivo. Antitermination was enhanced in vivo when the abortive transcript concentration was increased via overproduction of RNA polymerase or ribonuclease deficiency. Accordingly, antitermination activity exerted on T phi by abortive transcripts should facilitate expression of T phi-downstream promoter-less genes 11 and 12 in T7 infection of Escherichia coli.

Estimation of Reconnection Flux Using Post-Eruption Arcades and Its Relevance to Magnetic Clouds at 1 AU

NASA Technical Reports Server (NTRS)

Gopalswamy, N.; Yashiro, S.; Akiyama, S.; Xie, H.

2017-01-01

We report on a new method to compute the flare reconnection (RC) flux from post-eruption arcades (PEAs) and the underlying photospheric magnetic fields. In previous works, the RC flux has been computed using the cumulative flare ribbon area. Here we obtain the RC flux as the flux in half of the area underlying the PEA in EUV imaged after the flare maximum. We apply this method to a set of 21 eruptions that originated near the solar disk center in Solar Cycle 23. We find that the RC flux from the arcade method ((Phi)rA) has excellent agreement with the flux from the flare-ribbon method ((Phi)rR) according to (Phi)rA = 1.24((Phi)rR)(sup 0.99). We also find (Phi)rA to be correlated with the poloidal flux ((Phi)P) of the associated magnetic cloud at 1 AU: (Phi)P = 1.20((Phi)rA)(sup 0.85). This relation is nearly identical to that obtained by Qiu et al. (Astrophys. J. 659, 758, 2007) using a set of only 9 eruptions. Our result supports the idea that flare reconnection results in the formation of the flux rope and PEA as a common process.

Role of phi cells and the endodermis under salt stress in Brassica oleracea.

PubMed

Fernandez-Garcia, N; Lopez-Perez, L; Hernandez, M; Olmos, E

2009-01-01

Phi cell layers were discovered in the 19th century in a small number of species, including members of the Brassicaceae family. A mechanical role was first suggested for this structure; however, this has never been demonstrated. The main objective of the present work was to analyse the ultrastructure of phi cells, their influence on ion movement from the cortex to the stele, and their contribution to salt stress tolerance in Brassica oleracea. Transmission electron microscopy and X-ray microanalysis studies were used to analyse the subcellular structure and distribution of ions in phi cells and the endodermis under salt stress. Ion movement was analysed using lanthanum as an apoplastic tracer. The ultrastructural results confirm that phi cells are specialized cells showing cell wall ingrowths in the inner tangential cell walls. X-ray microanalysis confirmed a build-up of sodium. Phi thickenings were lignified and lanthanum moved periplasmically at this level. To the best of our knowledge, this is the first study reporting the possible role of the phi cells as a barrier controlling the movement of ions from the cortex to the stele. Therefore, the phi cell layer and endodermis seem to be regulating ion transport in Brassica oleracea under salt stress.

Yellow fluorescent protein phiYFPv (Phialidium): structure and structure-based mutagenesis

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

Pletneva, Nadya V.; Pletnev, Vladimir Z., E-mail: vzpletnev@gmail.com; Souslova, Ekaterina

The yellow fluorescent protein phiYFPv with improved folding has been developed from the spectrally identical wild-type phiYFP found in the marine jellyfish Phialidium. The yellow fluorescent protein phiYFPv (λ{sub em}{sup max} ≃ 537 nm) with improved folding has been developed from the spectrally identical wild-type phiYFP found in the marine jellyfish Phialidium. The latter fluorescent protein is one of only two known cases of naturally occurring proteins that exhibit emission spectra in the yellow–orange range (535–555 nm). Here, the crystal structure of phiYFPv has been determined at 2.05 Å resolution. The ‘yellow’ chromophore formed from the sequence triad Thr65-Tyr66-Gly67 adoptsmore » the bicyclic structure typical of fluorophores emitting in the green spectral range. It was demonstrated that perfect antiparallel π-stacking of chromophore Tyr66 and the proximal Tyr203, as well as Val205, facing the chromophore phenolic ring are chiefly responsible for the observed yellow emission of phiYFPv at 537 nm. Structure-based site-directed mutagenesis has been used to identify the key functional residues in the chromophore environment. The obtained results have been utilized to improve the properties of phiYFPv and its homologous monomeric biomarker tagYFP.« less

Liquid drop model for charged spherical metal clusters

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

Seidl, M.; Brack, M.

1996-02-01

The average ground-state energy of a charged spherical metal cluster with {ital N} atoms and {ital z} excessive valence electrons, i.e., with net charge {ital Q}={minus}{ital ez} and radius {ital R}={ital r}{sub {ital sN}}{sup 1/3}, is presented in the liquid drop model (LDM) expansion {ital E}({ital N},{ital z})={ital a}{sub v}{ital N}+{ital a}{sub s}{ital N}{sup 2/3}+{ital a}{sub c}{ital N}{sup 1/3}+{ital a}{sub 0}({ital z})+{ital a}{sub {minus}1}({ital z}){ital N}{sup {minus}1/3}+{ital O}({ital N}{sup {minus}2/3}). We derive analytical expressions for the leading LDM coefficients {ital a}{sub v}, {ital a}{sub s}, {ital a}{sub c}, and, in particular, for the charge dependence of the further LDM coefficientsmore » {ital a}{sub 0} and {ital a}{sub {minus}1}, using the jellium model and density functional theory in the local density approximation. We obtain for the ionization energy {ital I}({ital R})={ital W}+{alpha}({ital e}{sup 2}/{ital R})+{ital O}({ital R}{sup {minus}2}), with the bulk work function {ital W}=[{Phi}(+{infinity}){minus}{Phi}(0)]{minus}{ital e}{sub b}, given first by Mahan and Schaich in terms of the electrostatic potential {Phi} and the bulk energy per electron {ital e}{sub b}, and a new analytical expression for the dimensionless coefficient {alpha}. We demonstrate that within classical theory {alpha}=1/2 but, in agreement with experimental information, {alpha} tends to {approximately}0.4 if quantum-mechanical contributions are included. In order to test and confirm our analytical expressions, we discuss the numerical results of semiclassical density variational calculations in the extended Thomas{endash}Fermi model. Copyright {copyright} 1996 Academic Press, Inc.« less

Measurement of CP-violation parameters in decays of B_s^0 \\to J/\\psi \\phi with the ATLAS detector

NASA Astrophysics Data System (ADS)

Maevskiy, A. S.; ATLAS Collaboration

2017-01-01

A measurement of CP-violating weak phase φs and B_s^0 meson decay width difference with B_s0 \\to J/\\psi φ decays in the ATLAS experiment is presented. It is based on integrated luminosity of 14.3 fb-1 collected by the ATLAS detector from 8 TeV pp collisions at the LHC. The measured values are statistically combined with those from 4.9 fb-1 of 7 TeV collisions data, yielding an overall Run-1 ATLAS result.

Inclusion of 5-[4-(1-dodecanoylpyridinium)]-10,15,20-triphenylporphine in supramolecular aggregates of cationic amphiphilic cyclodextrins: physicochemical characterization of the complexes and strengthening of the antimicrobial photosensitizing activity.

PubMed

Ferro, Stefania; Jori, Giulio; Sortino, Salvatore; Stancanelli, Rosanna; Nikolov, Peter; Tognon, Giuseppe; Ricchelli, Fernanda; Mazzaglia, Antonino

2009-09-14

Recent findings suggest that visible light-promoted photooxidative processes mediated by sensitizers of appropriate chemical structure could represent a useful tool for properly addressing the problem of the increasing occurrence of infectious diseases caused by multiantibiotic-resistant microbial pathogens. The monocationic meso-substituted porphyrin 5-[4-(1-dodecanoylpyridinium)]-10,15,20-triphenyl-porphine (TDPyP) complexed into supramolecular aggregates of cationic amphiphilic beta-cyclodextrin (SC(6)NH(2)) (mean diameter = 20 nm) appeared to be endowed with favorable properties to act as a photosensitizing agent, including a very high quantum yield (Phi(Delta) = 0.90) for the generation of the highly reactive oxygen species, singlet oxygen ((1)O(2)). Although the yield of (1)O(2) generation was comparable to that obtained after TDPyP incorporation into cationic unilamellar liposomes of N-[1-(2,3-dioleoyloxy)propyl]-N,N,N-trimethylammonium chloride (DOTAP) SC(6)NH(2)-bound TDPyP was more active than DOTAP-bound TDPyP in photosensitizing the inactivation of the Gram-positive methicillin-resistant bacterium Staphylococcus aureus (MRSA). At variance with DOTAP-bound TDPyP, photoactivated SC(6)NH(2)-bound TDPyP was efficient also in photokilling Gram-negative bacterial pathogens, such as Escherichia coli . These observations are in agreement with the well-known photobactericidal effect of positively charged porphyrin derivatives, which can be markedly enhanced after incorporation into carriers with multiple positive charges. In addition, transmission electron microscopy studies revealed that potentiation of the TDPyP-mediated photobactericidal effect by incorporation into SC(6)NH(2) is a consequence of the carrier's ability to promote an efficient crossing of the very tightly organized three-dimensional architecture of the bacterial outer wall by the embedded porphyrin so that a prompt interaction between the short-lived photogenerated (1)O(2) and the nearby targets, whose integrity is critical for cell survival, can take place.

Laser flash photolysis of ozone - O/1D/ quantum yields in the fall-off region 297-325 nm

NASA Technical Reports Server (NTRS)

Brock, J. C.; Watson, R. T.

1980-01-01

The wavelength dependence of the quantum yield for O(1D) production from ozone photolysis has been determined between 297.5 nm and 325 nm in order to resolve serious discrepancies among previous studies. The results of this investigation are compared to earlier work by calculating atmospheric production rate constants for O(1D). It is found that for the purpose of calculating this rate constant, there is now good agreement among three studies at 298 K. Furthermore, it appears that previous data on the temperature dependence of the O(1D) quantum yield fall-off is adequate for determining the vertical profile of the O(1D) production rate constant. Several experimental difficulties associated with using NO2(asterisk) chemiluminescence to monitor O(1D) have been identified.

Sample-Averaged Biexciton Quantum Yield Measured by Solution-Phase Photon Correlation

DOE PAGES

Beyler, Andrew P.; Bischof, Thomas S.; Cui, Jian; ...

2014-11-19

The brightness of nanoscale optical materials such as semiconductor nanocrystals is currently limited in high excitation flux applications by inefficient multiexciton fluorescence. We have devised a solution-phase photon correlation measurement that can conveniently and reliably measure the average biexciton-to-exciton quantum yield ratio of an entire sample without user selection bias. This technique can be used to investigate the multiexciton recombination dynamics of a broad scope of synthetically underdeveloped materials, including those with low exciton quantum yields and poor fluorescence stability. Here in this study, we have applied this method to measure weak biexciton fluorescence in samples of visible-emitting InP/ZnS andmore » InAs/ZnS core/shell nanocrystals, and to demonstrate that a rapid CdS shell growth procedure can markedly increase the biexciton fluorescence of CdSe nanocrystals.« less

Quantitative photoabsorption and fluorescence spectroscopy of benzene, naphthalene, and some derivatives at 106-295 nm

NASA Technical Reports Server (NTRS)

Suto, Masako; Wang, Xiuyan; Shan, Jun; Lee, L. C.

1992-01-01

Photoabsorption and fluorescence cross sections of benzene, (o-, m-, p-) xylenes, naphthalene, 1-methylnaphthalene, and 2-ethylnaphthalene in the gas phase are measured at 106-295 nm using synchrotron radiation as a light source. Fluorescences are observed from the photoexcitation of benzene and xylenes at 230-280 nm and from naphthalene and its derivatives at 190-295 nm. The absolute fluorescence cross section is determined by calibration with respect to the emission intensity of the NO(A-X) system, for which the fluorescence quantum yield is equal to 1. To cross-check the current calibration method, the quantum yield of the SO2(C-X) system at 220-230 nm was measured since it is about equal to 1. The current quantum-yield data are compared with previously published values measured by different methods.

Sample-Averaged Biexciton Quantum Yield Measured by Solution-Phase Photon Correlation

PubMed Central

Beyler, Andrew P.; Bischof, Thomas S.; Cui, Jian; Coropceanu, Igor; Harris, Daniel K.; Bawendi, Moungi G.

2015-01-01

The brightness of nanoscale optical materials such as semiconductor nanocrystals is currently limited in high excitation flux applications by inefficient multiexciton fluorescence. We have devised a solution-phase photon correlation measurement that can conveniently and reliably measure the average biexciton-to-exciton quantum yield ratio of an entire sample without user selection bias. This technique can be used to investigate the multiexciton recombination dynamics of a broad scope of synthetically underdeveloped materials, including those with low exciton quantum yields and poor fluorescence stability. Here, we have applied this method to measure weak biexciton fluorescence in samples of visible-emitting InP/ZnS and InAs/ZnS core/shell nanocrystals, and to demonstrate that a rapid CdS shell growth procedure can markedly increase the biexciton fluorescence of CdSe nanocrystals. PMID:25409496

Intracellular pH in sperm physiology.

PubMed

Nishigaki, Takuya; José, Omar; González-Cota, Ana Laura; Romero, Francisco; Treviño, Claudia L; Darszon, Alberto

2014-08-01

Intracellular pH (pHi) regulation is essential for cell function. Notably, several unique sperm ion transporters and enzymes whose elimination causes infertility are either pHi dependent or somehow related to pHi regulation. Amongst them are: CatSper, a Ca(2+) channel; Slo3, a K(+) channel; the sperm-specific Na(+)/H(+) exchanger and the soluble adenylyl cyclase. It is thus clear that pHi regulation is of the utmost importance for sperm physiology. This review briefly summarizes the key components involved in pHi regulation, their characteristics and participation in fundamental sperm functions such as motility, maturation and the acrosome reaction. Copyright © 2014 Elsevier Inc. All rights reserved.

On character amenability of Banach algebras

NASA Astrophysics Data System (ADS)

Kaniuth, E.; Lau, A. T.; Pym, J.

2008-08-01

We continue our work [E. Kaniuth, A.T. Lau, J. Pym, On [phi]-amenability of Banach algebras, Math. Proc. Cambridge Philos. Soc. 144 (2008) 85-96] in the study of amenability of a Banach algebra A defined with respect to a character [phi] of A. Various necessary and sufficient conditions of a global and a pointwise nature are found for a Banach algebra to possess a [phi]-mean of norm 1. We also completely determine the size of the set of [phi]-means for a separable weakly sequentially complete Banach algebra A with no [phi]-mean in A itself. A number of illustrative examples are discussed.

The genome of the Erwinia amylovora phage PhiEaH1 reveals greater diversity and broadens the applicability of phages for the treatment of fire blight.

PubMed

Meczker, Katalin; Dömötör, Dóra; Vass, János; Rákhely, Gábor; Schneider, György; Kovács, Tamás

2014-01-01

The enterobacterium Erwinia amylovora is the causal agent of fire blight. This study presents the analysis of the complete genome of phage PhiEaH1, isolated from the soil surrounding an E. amylovora-infected apple tree in Hungary. Its genome is 218 kb in size, containing 244 ORFs. PhiEaH1 is the second E. amylovora infecting phage from the Siphoviridae family whose complete genome sequence was determined. Beside PhiEaH2, PhiEaH1 is the other active component of Erwiphage, the first bacteriophage-based pesticide on the market against E. amylovora. Comparative genome analysis in this study has revealed that PhiEaH1 not only differs from the 10 formerly sequenced E. amylovora bacteriophages belonging to other phage families, but also from PhiEaH2. Sequencing of more Siphoviridae phage genomes might reveal further diversity, providing opportunities for the development of even more effective biological control agents, phage cocktails against Erwinia fire blight disease of commercial fruit crops.

[PHI regulates histone methylation and acetylation in Burkitt lymphoma Daudi cell line].

PubMed

Hong, Ling-Ling; Ma, Xu-Dong; Huang, Yi-Qun

2011-02-01

This study was purposed to investigate the effects of phenylhexyl isothiocyanate (PHI) on Burkitt lymphoma Daudi cell line and regulation of histone acetylation and methylation in Daudi cells, and to explore the potential mechanism. The apoptotic rate of Daudi cells treated with PHI was measured by flow cytometry, the changes of histone H3 and H4 acetylation, histone H3K9 and H3K4 methylation in Daudi cells treated with PHI were detected by Western blot. The results showed that PHI could induce apoptosis of Daudi cells, increased the acetylation level of H3 and H4, enhanced the methylation of H3K4, but reduced the methylation of H3K9. It is concluded that the PHI can up-regulate the acetylation level of histone H3 associated with transcription stimulation and the methylation of histone H3K4, down-regulate the methylation on histone H3K9 associated with transcription inhibition, promotes the apoptosis of Daudi cells. PHI may be a potential agent for target therapy of lymphoma.

The life of phi: the development of phi thickenings in roots of the orchids of the genus Miltoniopsis.

PubMed

Idris, Nurul A; Collings, David A

2015-02-01

Phi thickenings, bands of secondary wall thickenings that reinforce the primary wall of root cortical cells in a wide range of species, are described for the first time in the epiphytic orchid Miltoniopsis. As with phi thickenings found in other plants, the phi thickenings in Miltoniopsis contain highly aligned cellulose running along the lengths of the thickenings, and are lignified but not suberized. Using a combination of histological and immunocytochemical techniques, thickening development can be categorized into three different stages. Microtubules align lengthwise along the thickening during early and intermediate stages of development, and callose is deposited within the thickening in a pattern similar to the microtubules. These developing thickenings also label with the fluorescently tagged lectin wheat germ agglutinin (WGA). These associations with microtubules and callose, and the WGA labeling, all disappear when the phi thickenings are mature. This pattern of callose and WGA deposition show changes in the thickened cell wall composition and may shed light on the function of phi thickenings in plant roots, a role for which has yet to be established.

Particle-in-Cell laser-plasma simulation on Xeon Phi coprocessors

NASA Astrophysics Data System (ADS)

Surmin, I. A.; Bastrakov, S. I.; Efimenko, E. S.; Gonoskov, A. A.; Korzhimanov, A. V.; Meyerov, I. B.

2016-05-01

This paper concerns the development of a high-performance implementation of the Particle-in-Cell method for plasma simulation on Intel Xeon Phi coprocessors. We discuss the suitability of the method for Xeon Phi architecture and present our experience in the porting and optimization of the existing parallel Particle-in-Cell code PICADOR. Direct porting without code modification gives performance on Xeon Phi close to that of an 8-core CPU on a benchmark problem with 50 particles per cell. We demonstrate step-by-step optimization techniques, such as improving data locality, enhancing parallelization efficiency and vectorization leading to an overall 4.2 × speedup on CPU and 7.5 × on Xeon Phi compared to the baseline version. The optimized version achieves 16.9 ns per particle update on an Intel Xeon E5-2660 CPU and 9.3 ns per particle update on an Intel Xeon Phi 5110P. For a real problem of laser ion acceleration in targets with surface grating, where a large number of macroparticles per cell is required, the speedup of Xeon Phi compared to CPU is 1.6 ×.

Genome packaging in EL and Lin68, two giant phiKZ-like bacteriophages of P. aeruginosa.

PubMed

Sokolova, O S; Shaburova, O V; Pechnikova, E V; Shaytan, A K; Krylov, S V; Kiselev, N A; Krylov, V N

2014-11-01

A unique feature of the Pseudomonas aeruginosa giant phage phiKZ is its way of genome packaging onto a spool-like protein structure, the inner body. Until recently, no similar structures have been detected in other phages. We have studied DNA packaging in P. aeruginosa phages EL and Lin68 using cryo-electron microscopy and revealed the presence of inner bodies. The shape and positioning of the inner body and the density of the DNA packaging in EL are different from those found in phiKZ and Lin68. This internal organization explains how the shorter EL genome is packed into a large EL capsid, which has the same external dimensions as the capsids of phiKZ and Lin68. The similarity in the structural organization in EL and other phiKZ-like phages indicates that EL is phylogenetically related to other phiKZ-like phages, and, despite the lack of detectable DNA homology, EL, phiKZ, and Lin68 descend from a common ancestor. Copyright © 2014 Elsevier Inc. All rights reserved.

A Phosphine-Free Route to Size-Adjustable CdSe and CdSe/CdS Core-Shell Quantum Dots for White-Light-Emitting Diodes.

PubMed

Zhang, Yugang; Li, Guopeng; Zhang, Ting; Song, Zihang; Wang, Hui; Zhang, Zhongping; Jiang, Yang

2018-03-01

The selenium dioxide was used as the precursor to synthesize wide-size-ranged CdSe quantum dots (2.4-5.7 nm) via hot-injection route. The CdSe quantum dots are featured with high crystalline, monodisperse, zinc blende structure and wide emission region (530-635 nm). In order to improve the stability and quantum yield, a phosphine-free single-molecular precursor approach is used to obtain CdSe/CdS core/shell quantum dots. The CdSe/CdS quantum dots are highly fluorescent with quantum yield up to 65%, and persist the good monodispersity and high crystallinity. Moreover, the quantum dots white light-emitting-diodes are fabricated by using the resultant red emission core/shell quantum dots and Y3Al5O12:Ce3+ yellow phosphors as color-conversion layers on a blue InGaN chip. The prepared light-emitting-diodes show good performance with CIE-1931 coordinated of (0.3583, 0.3349), an Ra of 92.9, and a Tc of 4410 K at 20 mA, which indicate that the combination of red-emission QDs and yellow phophors as a promising approach to obtain warm WLEDs with good color rendering.

Excited-state properties of nucleic acid components

NASA Astrophysics Data System (ADS)

Salet, C.; Bensasson, R. V.; Becker, R. S.

1981-12-01

Measurements were made of the fluorescence and phosphorescence spectra and lifetimes, and also of the absorption spectra, lifetimes, extinction coefficients, and quantum yields of the T1 lower triplet states of thymine, uracil, their N, N'-dimethyl derivatives, thymidine, thymidine monophosphate, uridine, and uridine monophosphate in various solvents at 300 °K. The influence of the solvent on the quantum yield of the T1 state of nucleic acid components is discussed.

Laboratory Measurements of Photolytic Parameters for Formaldehyde.

DTIC Science & Technology

1980-11-01

dynamic dilution methods. Compressed air stored in steel cylinders, carefully selected to contain carbon monoxide and hydrogen at mixing ratios of...in air has been investi- gated in the laboratory at two temperatures: 300 and 220 K. Quantum yields for the formation of CO and H2 were determined at...procedures in the case of pure formaldehyde gave consistent results. (b) Quantum Yields Mixtures of formaldehyde in air were photolyzed in a

Synthesis and characterization of near-infrared absorbing water soluble squaraines and study of their photodynamic effects in DLA live cells.

PubMed

Shafeekh, Kulathinte M; Soumya, Mohanannair S; Rahim, Moochikkadavath A; Abraham, Annie; Das, Suresh

2014-01-01

Here, we report the synthesis, photophysical properties and photodynamic effects in DLA live cells of three water soluble squaraine dyes, viz. bisbenzothiazolium squaraine dyes SQMI and SQDI with iodine in one and both benzothiazolium units, respectively, and an unsymmetrical squaraine dye ASQI containing iodinated benzothiazolium and aniline substituents. The diiodinated SQDI showed an anomalous trend in both fluorescence and triplet quantum yields over the monoiodinated SQMI, with SQDI showing higher fluorescence and lower triplet quantum yields compared to SQMI. Nanosecond laser flash photolysis of SQDI and SQMI indicated the formation of triplet excited states with quantum yield of 0.19 and 0.26, respectively. On photoirradiation, both the SQDI and SQMI generate singlet oxygen and it was observed that both dyes undergoing oxidation reactions with the singlet oxygen generated. ASQI which exhibited a lower triplet quantum yield of 0.06 was, however, stable and did not react with the singlet oxygen generated. In vitro cytotoxicity studies of these dyes in DLA live cells were performed using Trypan blue dye exclusion method and it reflect an order of cytotoxicity of SQDI>SQMI>ASQI. Intracellular generation of the ROS was confirmed by dichlorofluorescein assay after the in vitro PDT. © 2014 The American Society of Photobiology.

Efficiencies of induction of DNA double strand breaks in solution by photoabsorption at phosphorus and platinum.

PubMed

Maeda, Munetoshi; Kobayashi, Katsumi; Hieda, Kotaro

2004-01-01

This paper aims at determining and comparing the cross sections and quantum yields for DNA strand break induction by the Auger effect at the K-shell of phosphorus and at the LIII-shell of platinum. Using synchrotron radiation, free and Pt-bound pBR322 plasmid DNA were irradiated in solution with monochromatic X-rays, the energies of which were 2.153 and 2.147 keV, corresponding to "on" and "below" the phosphorus K-shell photoabsorption, and 11.566 and 11.542 keV for "above" and "below" the L(III)-shell photoabsorption of platinum, respectively. To suppress indirect effects by hydroxyl radicals, DMSO (1M) was used as a scavenger. The inner-shell photoabsorption of phosphorus and of platinum significantly increased the induction of DNA double strand breaks (DSB), whereas it had little effect on single strand break (SSB) induction. The quantum yields for the induction of DSB were calculated to be 0.017 and 1.13, in the case of phosphorus and platinum, respectively. CONCLSIONS: The value of the quantum yield for the DSB induction of platinum was about 66-fold larger than that for the phosphorus. These results clearly demonstrate that the quantum yield of DSB depends upon the magnitude of the Auger cascade.

Towards efficient solar hydrogen production by intercalated carbon nitride photocatalyst.

PubMed

Gao, Honglin; Yan, Shicheng; Wang, Jiajia; Huang, Yu An; Wang, Peng; Li, Zhaosheng; Zou, Zhigang

2013-11-07

The development of efficient photocatalytic material for converting solar energy to hydrogen energy as viable alternatives to fossil-fuel technologies is expected to revolutionize energy shortage and environment issues. However, to date, the low quantum yield for solar hydrogen production over photocatalysts has hindered advances in the practical applications of photocatalysis. Here, we show that a carbon nitride intercalation compound (CNIC) synthesized by a simple molten salt route is an efficient polymer photocatalyst with a high quantum yield. We found that coordinating the alkali metals into the C-N plane of carbon nitride will induce the un-uniform spatial charge distribution. The electrons are confined in the intercalated region while the holes are in the far intercalated region, which promoted efficient separation of photogenerated carriers. The donor-type alkali metal ions coordinating into the nitrogen pots of carbon nitrides increase the free carrier concentration and lead to the formation of novel nonradiative paths. This should favor improved transport of the photogenerated electron and hole and decrease the electron-hole recombination rate. As a result, the CNIC exhibits a quantum yield as high as 21.2% under 420 nm light irradiation for solar hydrogen production. Such high quantum yield opens up new opportunities for using cheap semiconducting polymers as energy transducers.

Intense visible emission from ZnO/PAAX (X = H or Na) nanocomposite synthesized via a simple and scalable sol-gel method

NASA Astrophysics Data System (ADS)

Zhu, Y.; Apostoluk, A.; Gautier, P.; Valette, A.; Omar, L.; Cornier, T.; Bluet, J. M.; Masenelli-Varlot, K.; Daniele, S.; Masenelli, B.

2016-03-01

Intense visible nano-emitters are key objects for many technologies such as single photon source, bio-labels or energy convertors. Chalcogenide nanocrystals have ruled this domain for several decades. However, there is a demand for cheaper and less toxic materials. In this scheme, ZnO nanoparticles have appeared as potential candidates. At the nanoscale, they exhibit crystalline defects which can generate intense visible emission. However, even though photoluminescence quantum yields as high as 60% have been reported, it still remains to get quantum yield of that order of magnitude which remains stable over a long period. In this purpose, we present hybrid ZnO/polyacrylic acid (PAAH) nanocomposites, obtained from the hydrolysis of diethylzinc in presence of PAAH, exhibiting quantum yield systematically larger than 20%. By optimizing the nature and properties of the polymeric acid, the quantum yield is increased up to 70% and remains stable over months. This enhancement is explained by a model based on the hybrid type II heterostructure formed by ZnO/PAAH. The addition of PAAX (X = H or Na) during the hydrolysis of ZnEt2 represents a cost effective method to synthesize scalable amounts of highly luminescent ZnO/PAAX nanocomposites.

Faster search by lackadaisical quantum walk

NASA Astrophysics Data System (ADS)

Wong, Thomas G.

2018-03-01

In the typical model, a discrete-time coined quantum walk searching the 2D grid for a marked vertex achieves a success probability of O(1/log N) in O(√{N log N}) steps, which with amplitude amplification yields an overall runtime of O(√{N} log N). We show that making the quantum walk lackadaisical or lazy by adding a self-loop of weight 4 / N to each vertex speeds up the search, causing the success probability to reach a constant near 1 in O(√{N log N}) steps, thus yielding an O(√{log N}) improvement over the typical, loopless algorithm. This improved runtime matches the best known quantum algorithms for this search problem. Our results are based on numerical simulations since the algorithm is not an instance of the abstract search algorithm.

Developing Workforce Capacity in Public Health Informatics: Core Competencies and Curriculum Design

PubMed Central

Wholey, Douglas R.; LaVenture, Martin; Rajamani, Sripriya; Kreiger, Rob; Hedberg, Craig; Kenyon, Cynthia

2018-01-01

We describe a master’s level public health informatics (PHI) curriculum to support workforce development. Public health decision-making requires intensive information management to organize responses to health threats and develop effective health education and promotion. PHI competencies prepare the public health workforce to design and implement these information systems. The objective for a Master’s and Certificate in PHI is to prepare public health informaticians with the competencies to work collaboratively with colleagues in public health and other health professions to design and develop information systems that support population health improvement. The PHI competencies are drawn from computer, information, and organizational sciences. A curriculum is proposed to deliver the competencies and result of a pilot PHI program is presented. Since the public health workforce needs to use information technology effectively to improve population health, it is essential for public health academic institutions to develop and implement PHI workforce training programs. PMID:29770321

Intracellular pH of symbiotic dinoflagellates

NASA Astrophysics Data System (ADS)

Gibbin, E. M.; Davy, S. K.

2013-09-01

Intracellular pH (pHi) is likely to play a key role in maintaining the functional success of cnidarian-dinoflagellate symbiosis, yet until now the pHi of the symbiotic dinoflagellates (genus Symbiodinium) has never been quantified. Flow cytometry was used in conjunction with the ratiometric fluorescent dye BCECF to monitor changes in pHi over a daily light/dark cycle. The pHi of Symbiodinium type B1 freshly isolated from the model sea anemone Aiptasia pulchella was 7.25 ± 0.01 (mean ± SE) in the light and 7.10 ± 0.02 in the dark. A comparable effect of irradiance was seen across a variety of cultured Symbiodinium genotypes (types A1, B1, E1, E2, F1, and F5) which varied between pHi 7.21-7.39 in the light and 7.06-7.14 in the dark. Of note, there was a significant genotypic difference in pHi, irrespective of irradiance.

Analog quadrature signal to phase angle data conversion by a quadrature digitizer and quadrature counter

DOEpatents

Buchenauer, C.J.

1981-09-23

The quadrature phase angle phi (t) of a pair of quadrature signals S/sub 1/(t) and S/sub 2/(t) is digitally encoded on a real time basis by a quadrature digitizer for fractional phi (t) rotational excursions and by a quadrature up/down counter for full phi (t) rotations. The pair of quadrature signals are of the form S/sub 1/(t) = k(t) sin phi (t) and S/sub 2/(t) = k(t) cos phi (t) where k(t) is a signal common to both. The quadrature digitizer and the quadrature up/down counter may be used together or singularly as desired or required. Optionally, a digital-to-analog converter may follow the outputs of the quadrature digitizer and the quadrature up/down counter to provide an analog signal output of the quadrature phase angle phi (t).

Analog quadrature signal to phase angle data conversion by a quadrature digitizer and quadrature counter

DOEpatents

Buchenauer, C. Jerald

1984-01-01

The quadrature phase angle .phi.(t) of a pair of quadrature signals S.sub.1 (t) and S.sub.2 (t) is digitally encoded on a real time basis by a quadrature digitizer for fractional .phi.(t) rotational excursions and by a quadrature up/down counter for full .phi.(t) rotations. The pair of quadrature signals are of the form S.sub.1 (t)=k(t) sin .phi.(t) and S.sub.2 (t)=k(t) cos .phi.(t) where k(t) is a signal common to both. The quadrature digitizer and the quadrature up/down counter may be used together or singularly as desired or required. Optionally, a digital-to-analog converter may follow the outputs of the quadrature digitizer and the quadrature up/down counter to provide an analog signal output of the quadrature phase angle .phi.(t).

Macrophage tumoricidal mechanisms are selectively altered by prenatal chlordane exposure.

PubMed

Theus, S A; Tabor, D R; Soderberg, L S; Barnett, J B

1992-09-01

Macrophages (m phi) derived from mice treated in utero with chlordane show a significant delay of tumoricidal induction activity. In this study, m phi from chlordane-treated animals required a 48 h in vitro period of induction with interferon-gamma and lipopolysaccharide (IFN/LPS) before they could kill P815 targets. Similarly, m phi from chlordane-treated animals also failed to produce an immediate H2O2 burst upon perturbation. Conversely, their stimulated control m phi counterparts were tumoricidal by 2 h and exhibited a respiratory burst without any delay. Moreover, levels of the second messenger, inositol triphosphate (IP3), were significantly delayed in chlordane-treated animals following interaction with IFN/LPS. When nitrate/nitrite production was analyzed as an alternate mechanism for killing tumors, stimulated m phi from both normal and chlordane-treated animals responded equally. The data show that chlordane differentially introduces defects in m phi biochemical mechanisms associated with tumor killing.

Measurement of differential cross sections in the $$\\phi^*$$ variable for inclusive Z boson production in pp collisions at $$\\sqrt{s}=$$ 8 TeV

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

Sirunyan, Albert M; et al.

Measurements of differential cross sections dmore » $$\\sigma$$/d$$\\phi^*$$ and double-differential cross sections d$$^2\\sigma$$/d$$\\phi^*\\,$$d$|y|$ for inclusive Z boson production are presented using the dielectron and dimuon final states. The kinematic observable $$\\phi^*$$ correlates with the dilepton transverse momentum but has better resolution, and $y$ is the dilepton rapidity. The analysis is based on data collected with the CMS experiment at a centre-of-mass energy of 8 TeV corresponding to an integrated luminosity of 19.7 fb$$^{-1}$$. The normalised cross section (1/$$\\sigma$$)$$\\,$$d$$\\sigma$$/d$$\\phi^*$$, within the fiducial kinematic region, is measured with a precision of better than 0.5% for $$\\phi^*$$<1. The measurements are compared to theoretical predictions and they agree, typically, within few percent.« less

Developing Workforce Capacity in Public Health Informatics: Core Competencies and Curriculum Design.

PubMed

Wholey, Douglas R; LaVenture, Martin; Rajamani, Sripriya; Kreiger, Rob; Hedberg, Craig; Kenyon, Cynthia

2018-01-01

We describe a master's level public health informatics (PHI) curriculum to support workforce development. Public health decision-making requires intensive information management to organize responses to health threats and develop effective health education and promotion. PHI competencies prepare the public health workforce to design and implement these information systems. The objective for a Master's and Certificate in PHI is to prepare public health informaticians with the competencies to work collaboratively with colleagues in public health and other health professions to design and develop information systems that support population health improvement. The PHI competencies are drawn from computer, information, and organizational sciences. A curriculum is proposed to deliver the competencies and result of a pilot PHI program is presented. Since the public health workforce needs to use information technology effectively to improve population health, it is essential for public health academic institutions to develop and implement PHI workforce training programs.

Search for charmonium and charmoniumlike states in {Upsilon}(1S) radiative decays

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

Shen, C. P.; University of Hawaii, Honolulu, Hawaii 96822; Wang, X. L.

2010-09-01

Using a sample of 102x10{sup 6} {Upsilon}(1S) events collected with the Belle detector, we report on the first search for charge-parity-even charmonium and charmoniumlike states in {Upsilon}(1S) radiative decays. No significant {chi}{sub cJ} or {eta}{sub c} signal is observed and 90% C.L. limits on B({Upsilon}(1S){yields}{gamma}{chi}{sub c0})<6.5x10{sup -4}, B({Upsilon}(1S){yields}{gamma}{chi}{sub c1})<2.3x10{sup -5}, B({Upsilon}(1S){yields}{gamma}{chi}{sub c2})<7.6x10{sup -6}, and B({Upsilon}(1S){yields}{gamma}{eta}{sub c})<5.7x10{sup -5} are obtained. The product branching fraction limits B({Upsilon}(1S){yields}{gamma}X(3872))B(X(3872){yields}{pi}{sup +}{pi}{sup -}{pi}{sup +}{pi}{sup -}J/{psi})<1.6x10{sup -6}, B({Upsilon}(1S){yields}{gamma}X(3872))B(X(3872){yields}{pi}{sup +}{pi}{sup -}{pi}{sup 0}J/{psi})<2.8x10{sup -6}, B({Upsilon}(1S){yields}{gamma}X(3915)) B(X(3915){yields}{omega}J/{psi})<3.0x10{sup -6}, and B({Upsilon}(1S){yields}{gamma}Y(4140))B(Y(4140){yields}{phi}J/{psi})<2.2x10{sup -6} are obtained at the 90% C.L. Furthermore, no evidence is found for excited charmonium states below 4.8 GeV/c{sup 2}.

Reusable design: A proposed approach to Public Health Informatics system design

PubMed Central

2011-01-01

Background Since it was first defined in 1995, Public Health Informatics (PHI) has become a recognized discipline, with a research agenda, defined domain-specific competencies and a specialized corpus of technical knowledge. Information systems form a cornerstone of PHI research and implementation, representing significant progress for the nascent field. However, PHI does not advocate or incorporate standard, domain-appropriate design methods for implementing public health information systems. Reusable design is generalized design advice that can be reused in a range of similar contexts. We propose that PHI create and reuse information design knowledge by taking a systems approach that incorporates design methods from the disciplines of Human-Computer Interaction, Interaction Design and other related disciplines. Discussion Although PHI operates in a domain with unique characteristics, many design problems in public health correspond to classic design problems, suggesting that existing design methods and solution approaches are applicable to the design of public health information systems. Among the numerous methodological frameworks used in other disciplines, we identify scenario-based design and participatory design as two widely-employed methodologies that are appropriate for adoption as PHI standards. We make the case that these methods show promise to create reusable design knowledge in PHI. Summary We propose the formalization of a set of standard design methods within PHI that can be used to pursue a strategy of design knowledge creation and reuse for cost-effective, interoperable public health information systems. We suggest that all public health informaticians should be able to use these design methods and the methods should be incorporated into PHI training. PMID:21333000

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

Orfield, Noah J.; McBride, James R.; Wang, Feng

Physical variations in colloidal nanostructures give rise to heterogeneity in expressed optical behavior. This correlation between nanoscale structure and function demands interrogation of both atomic structure and photophysics at the level of single nanostructures to be fully understood. In this paper, by conducting detailed analyses of fine atomic structure, chemical composition, and time-resolved single-photon photoluminescence data for the same individual nanocrystals, we reveal inhomogeneity in the quantum yields of single nonblinking “giant” CdSe/CdS core/shell quantum dots (g-QDs). We find that each g-QD possesses distinctive single exciton and biexciton quantum yields that result mainly from variations in the degree of charging,more » rather than from volume or structure inhomogeneity. We further establish that there is a very limited nonemissive “dark” fraction (<2%) among the studied g-QDs and present direct evidence that the g-QD core must lack inorganic passivation for the g-QD to be “dark”. Finally and therefore, in contrast to conventional QDs, ensemble photoluminescence quantum yield is principally defined by charging processes rather than the existence of dark g-QDs.« less

Strongly Coupled Tin-Halide Perovskites to Modulate Light Emission: Tunable 550-640 nm Light Emission (FWHM 36-80 nm) with a Quantum Yield of up to 6.4.

PubMed

Chen, Min-Yi; Lin, Jin-Tai; Hsu, Chia-Shuo; Chang, Chung-Kai; Chiu, Ching-Wen; Chen, Hao Ming; Chou, Pi-Tai

2018-05-01

Colloidal perovskite quantum dots represent one of the most promising materials for applications in solar cells and photoluminescences. These devices require a low density of crystal defects and a high yield of photogenerated carriers, which are difficult to realize in tin-halide perovskite because of the intrinsic instability of tin during nucleation. Here, an enhancement in the luminescent property of tin-halide perovskite nanoplates (TPNPs) that are composed of strongly coupled layered structures with the chemical formula of PEA 2 SnX 4 (PEA = C 6 H 5 (CH 2 ) 2 NH 3 , X = Br, I) is reported. TPNPs (X = I) show an emission at a wavelength of 640 nm, with high quantum yield of 6.40 ± 0.14% and full width at half maximum (FWHM) as small as 36 nm. The presence of aliphatic carboxylic acid is found to play a key role in reducing the tin perovskite defect density, which significantly improves the emission intensity and stability of TPNPs. Upon mixing iodo- and bromo- precursors, the emission wavelength is successfully tuned from 640 nm (PEA 2 SnI 4 ) to 550 nm (PEA 2 SnBr 4 ), with a corresponding emission quantum yield and FWHM of 0.16-6.40% and 36-80 nm, respectively. The results demonstrate a major advance for the emission yield and tunability of tin-halide perovskites. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Photoswitchable Fluorescent Diarylethene Derivatives with Thiophene 1,1-Dioxide Groups: Effect of Alkyl Substituents at the Reactive Carbons

PubMed Central

Sumi, Takaki; Irie, Masahiro

2017-01-01

Photoswitching and fluorescent properties of sulfone derivatives of 1,2-bis(2-alkyl-4-methyl-5-phenyl-3-thienyl)perfluorocyclopentene, 1–5, having methyl, ethyl, n-propyl, i-propyl, and i-butyl substituents at the reactive carbons (2- and 2′-positions) of the thiophene 1,1-dioxide rings were studied. Diarylethenes 1–5 underwent isomerization reactions between open-ring and closed-ring forms upon alternate irradiation with ultraviolet (UV) and visible light and showed fluorescence in the closed-ring forms. The alkyl substitution at the reactive carbons affects the fluorescent property of the closed-ring isomers. The closed-ring isomers 2b–5b with ethyl, n-propyl, i-propyl, and i-butyl substituents show higher fluorescence quantum yields than 1b with methyl substituents. In polar solvents, the fluorescence quantum yield of 1b markedly decreases, while 2b–5b maintain the relatively high fluorescence quantum yields. Although the cycloreversion quantum yields of the derivatives with methyl, ethyl, n-propyl, and i-propyl substituents are quite low and in the order of 10−5, introduction of i-butyl substituents was found to increase the yield up to the order of 10−3. These results indicate that appropriate alkyl substitution at the reactive carbons is indispensable for properly controlling the photoswitching and fluorescent properties of the photoswitchable fluorescent diarylethenes, which are potentially applicable to super-resolution fluorescence microscopies. PMID:28869489

Thermal performance testing of two Thales 9310 pulse-tube cryocoolers for PHyTIR

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

Paine, Christopher G.

2014-01-29

PHyTIR is a NASA-funded technology demonstration for a near-term earth-observing instrument in the thermal infrared spectrum, intended for use in the HyspIRI mission. PHyTIR will use two Thales 9310 single-stage pulse tube cryocoolers, one to directly cool the FPA, the other to simulate a passive radiator. We report performance measurements for the two Thales 9310 cryocoolers intended for inclusion in the PHyTIR demonstrator.

Genomic characterization of Ralstonia solanacearum phage phiRSB1, a T7-like wide-host-range phage.

PubMed

Kawasaki, Takeru; Shimizu, Mio; Satsuma, Hideki; Fujiwara, Akiko; Fujie, Makoto; Usami, Shoji; Yamada, Takashi

2009-01-01

PhiRSB1 is a wide-host-range, T7-like bacteriophage that infects and efficiently lyses the phytopathogenic bacterium Ralstonia solanacearum. The phiRSB1 genome comprises 43,079 bp of double-stranded DNA (61.7% G+C) with 325-bp terminal repeats and contains 47 open reading frames. Strong activity of tandem early promoters and wide specificity of phage promoters of phiRSB1 were demonstrated.

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

Mthethwa, T.P.; Moloto, M.J., E-mail: mmoloto@uj.ac.za; De Vries, A.

Graphical abstract: SEM images of CdS/PMMA showing coiling as loading of CdS nanoparticles is increased. Thermal stability is increased with increase in %loading of both CdS and CdSe nanoparticles. Research highlights: {yields} TOPO-capped CdS and HDA-capped CdSe nanoparticles were synthesized and fully characterized. {yields} The nanoparticles were mixed with the polymer, PMMA using electrospinning technique using 2, 5 and 10% weight loadings. {yields} The mixture was spun to produce fibres with optical and thermal properties showing significant change and also the increase in loading causing bending or spiraling. {yields} Both TEM images for nanoparticles and SEM for fibres shows themore » morphology and sizes of the particles. -- Abstract: Electrospinning technique was used to fabricate poly(methyl methacrylate) (PMMA) fibres incorporating CdS and CdSe quantum dots (nanoparticles). Different nanoparticle loadings (2, 5 and 10 wt% with respect to PMMA) were used and the effect of the quantum dots on the properties of the fibres was studied. The optical properties of the hybrid composite fibres were investigated by photoluminescence and UV-vis spectrophotometry. Scanning electron microscopy (SEM), X-ray diffraction and FTIR spectrophotometry were also used to investigate the morphology and structure of the fibres. The optical studies showed that the size-tunable optical properties can be achieved in the polymer fibres by addition of quantum dots. SEM images showed that the morphologies of the fibres were dependent on the added amounts of quantum dots. A spiral type of morphology was observed with an increase in the concentration of CdS and CdSe nanoparticles. Less beaded structures and bigger diameter fibres were obtained at higher quantum dot concentrations. X-ray diffractometry detected the amorphous peaks of the polymer and even after the quantum dots were added and the FTIR analysis shows that there was no considerable interaction between the quantum dots and the polymer fibres at low concentration of quantum dots however at higher concentrations some interactions were observed which shows that QDs were present on the surfaces of the fibres.« less

[The value of PHI/PCA3 in the early diagnosis of prostate cancer].

PubMed

Tan, S J; Xu, L W; Xu, Z; Wu, J P; Liang, K; Jia, R P

2016-01-12

To investigate the value of prostate health index (PHI) and prostate cancer gene 3 (PCA3) in the early diagnosis of prostate cancer (PCa). A total of 190 patients with abnormal serum prostate specific antigen (PSA) or abnormal digital rectal examination were enrolled. They were all underwent initial biopsy and 11 of them were also underwent repeated biopsy. In addition, 25 healthy cases (with normal digital rectal examination and PSA<4 ng/ml) were the control group.The PHI and PCA3 were detected by using immunofluorescence and Loop-Mediated Isothermal Amplification (LAMP). The sensitivity and specificity of diagnosis were determined by ROC curve.In addition, the relationship between PHI/PSA and the Gleason score and clinical stage were analyzed. A total of 89 patients were confirmed PCa by Pathological diagnosis. The other 101 patients were diagnosed as benign prostatic hyperplasia (BPH). The sensitivity and specificity of PCA3 test were 85.4% was 92.1%. Area under curve (AUC) of PHI is higher than AUC of PSA (0.727>0.699). The PHI in peripheral blood was positively correlated with Gleason score and clinical stage. The detection of PCA3 and PHI shows excellent detecting effectiveness. Compared with single PSA, the combined detection of PHI and PCA3 improved the diagnostic specificity. It can provide a new method for the early diagnosis in prostate cancer and avoid unnecessary biopsies.

Genome packaging in EL and Lin68, two giant phiKZ-like bacteriophages of P. aeruginosa

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

Sokolova, O.S., E-mail: sokolova@mail.bio.msu.ru; A.V. Shoubnikov Institute of Crystallography RAS, Moscow; Shaburova, O.V.

A unique feature of the Pseudomonas aeruginosa giant phage phiKZ is its way of genome packaging onto a spool-like protein structure, the inner body. Until recently, no similar structures have been detected in other phages. We have studied DNA packaging in P. aeruginosa phages EL and Lin68 using cryo-electron microscopy and revealed the presence of inner bodies. The shape and positioning of the inner body and the density of the DNA packaging in EL are different from those found in phiKZ and Lin68. This internal organization explains how the shorter EL genome is packed into a large EL capsid, whichmore » has the same external dimensions as the capsids of phiKZ and Lin68. The similarity in the structural organization in EL and other phiKZ-like phages indicates that EL is phylogenetically related to other phiKZ-like phages, and, despite the lack of detectable DNA homology, EL, phiKZ, and Lin68 descend from a common ancestor. - Highlights: • We performed a comparative structural study of giant P. aeruginosa phages: EL, Lin68 and phiKZ. • We revealed that the inner body is a common feature in giant phages. • The phage genome size correlates with the overall dimensions of the inner body.« less

PhiC31 recombination system demonstrates heritable germinal transmission of site-specific excision from the Arabidopsis genome

PubMed Central

2010-01-01

Background The large serine recombinase phiC31 from broad host range Streptomyces temperate phage, catalyzes the site-specific recombination of two recognition sites that differ in sequence, typically known as attachment sites attB and attP. Previously, we characterized the phiC31 catalytic activity and modes of action in the fission yeast Schizosaccharomyces pombe. Results In this work, the phiC31 recombinase gene was placed under the control of the Arabidopsis OXS3 promoter and introduced into Arabidopsis harboring a chromosomally integrated attB and attP-flanked target sequence. The phiC31 recombinase excised the attB and attP-flanked DNA, and the excision event was detected in subsequent generations in the absence of the phiC31 gene, indicating germinal transmission was possible. We further verified that the genomic excision was conservative and that introduction of a functional recombinase can be achieved through secondary transformation as well as manual crossing. Conclusion The phiC31 system performs site-specific recombination in germinal tissue, a prerequisite for generating stable lines with unwanted DNA removed. The precise site-specific deletion by phiC31 in planta demonstrates that the recombinase can be used to remove selectable markers or other introduced transgenes that are no longer desired and therefore can be a useful tool for genome engineering in plants. PMID:20178628

Rapid creation of distant entanglement by multi-photon resonant fluorescence

NASA Astrophysics Data System (ADS)

Cohen, Guy Z.; Sham, L. J.

2014-03-01

We study a simple, effective and robust method for entangling two separate stationary quantum dot spin qubits with high fidelity using multi-photon Gaussian state. The fluorescence signals from the two dots interfere at a beam splitter. The bosonic nature of photons leads, in analogy with the Hong-Ou-Mandel (HOM) effect, to selective pairing of photon holes (photon absences in the fluorescent signals). By the HOM effect, two photon holes with the same polarization end up at the same beam splitter output. As a result, two odd photon number detections at the outgoing beams, which must correspond to two photon holes with different polarizations, herald entanglement creation. The robustness of the Gaussian states is evidenced by the ability to compensate for photon absorption and noise by a moderate increase in the number of photons at the input. We calculate the entanglement generation rate in the ideal, non-ideal and near-ideal detector regimes and find substantial improvement over single-photon schemes in all three regimes. Fast and efficient spin-spin entanglement creation can form the basis for a scalable quantum dot quantum computing network. Our predictions can be tested using current experimental capabilities. This research was supported by the U.S. Army Research Office MURI award W911NF0910406, by NSF grant PHY-1104446 and by ARO (IARPA, W911NF-08-1-0487). The authors thank D. G. Steel for useful discussions.

A synchronous game for binary constraint systems

NASA Astrophysics Data System (ADS)

Kim, Se-Jin; Paulsen, Vern; Schafhauser, Christopher

2018-03-01

Recently, Slofstra proved that the set of quantum correlations is not closed. We prove that the set of synchronous quantum correlations is not closed, which implies his result, by giving an example of a synchronous game that has a perfect quantum approximate strategy but no perfect quantum strategy. We also exhibit a graph for which the quantum independence number and the quantum approximate independence number are different. We prove new characterisations of synchronous quantum approximate correlations and synchronous quantum spatial correlations. We solve the synchronous approximation problem of Dykema and the second author, which yields a new equivalence of Connes' embedding problem in terms of synchronous correlations.

Raising yield potential in wheat: increasing photosynthesis capacity and efficiency

USDA-ARS?s Scientific Manuscript database

Increasing wheat yields to help to ensure food security is a major challenge. Meeting this challenge requires a quantum improvement in the yield potential of wheat. Past increases in yield potential have largely resulted from improvements in harvest index not through increased biomass. Further large...

Correlation complementarity yields bell monogamy relations.

PubMed

Kurzyński, P; Paterek, T; Ramanathan, R; Laskowski, W; Kaszlikowski, D

2011-05-06

We present a method to derive Bell monogamy relations by connecting the complementarity principle with quantum nonlocality. The resulting monogamy relations are stronger than those obtained from the no-signaling principle alone. In many cases, they yield tight quantum bounds on the amount of violation of single and multiple qubit correlation Bell inequalities. In contrast with the two-qubit case, a rich structure of possible violation patterns is shown to exist in the multipartite scenario.

The effect of axial ligands on the quantum yield of singlet oxygen of new silicon phthalocyanine

NASA Astrophysics Data System (ADS)

Lv, Huafei; Zhang, Xuemei; Yu, Xinxin; Pan, Sujuan; Xie, Shusen; Yang, Hongqin; Peng, Yiru

2016-10-01

The singlet oxygen (1O2) production abilitity is an important factor to assess their potential as effective of photosensitizers. In this paper, the 1O2 production rate, production rate constant and quantum yield of silicon(IV) phthalocyanine axially bearing 1-3 generation dendritic substituents were evaluated by a high performance liquid chromatographic method. The results show that the 1O2 production rate and production rate constant of these compounds increase gradually with dendritic generations increase. And the 1O2 quantum yield of silicon(IV) phthalocyanine with first generation dendritic ligand was the highest. This may be due to the isolation effect of the dendritic ligands on the phthalocyanine core. The parameters of the observed 1O2 production properties will provide valuable data for these dendrimer phthalocyanines as promising photosensitizer in PDT application.

Photochemical studies of a fluorescent chlorophyll catabolite--source of bright blue fluorescence in plant tissue and efficient sensitizer of singlet oxygen.

PubMed

Jockusch, Steffen; Turro, Nicholas J; Banala, Srinivas; Kräutler, Bernhard

2014-02-01

Fluorescent chlorophyll catabolites (FCCs) are fleeting intermediates of chlorophyll breakdown, which is seen as an enzyme controlled detoxification process of the chlorophylls in plants. However, some plants accumulate large amounts of persistent FCCs, such as in senescent leaves and in peels of yellow bananas. The photophysical properties of such a persistent FCC (Me-sFCC) were investigated in detail. FCCs absorb in the near UV spectral region and show blue fluorescence (max at 437 nm). The Me-sFCC fluorescence had a quantum yield of 0.21 (lifetime 1.6 ns). Photoexcited Me-sFCC intersystem crosses into the triplet state (quantum yield 0.6) and generates efficiently singlet oxygen (quantum yield 0.59). The efficient generation of singlet oxygen makes fluorescent chlorophyll catabolites phototoxic, but might also be useful as a (stress) signal and for defense of the plant tissue against infection by pathogens.

Short-Term Flooding Effects on Gas Exchange and Quantum Yield of Rabbiteye Blueberry (Vaccinium ashei Reade) 1

PubMed Central

Davies, Frederick S.; Flore, James A.

1986-01-01

Roots of 1.5-year-old `Woodard' rabbiteye blueberry plants (Vaccinium ashei Reade) were flooded in containers or maintained at container capacity over a 5-day period. Carbon assimilation, and stomatal and residual conductances were monitored on one fully expanded shoot/plant using an open flow gas analysis system. Quantum yield was calculated from light response curves. Carbon assimilation and quantum yield of flooded plants decreased to 64 and 41% of control values, respectively, after 1 day of flooding and continued decreasing to 38 and 27% after 4 days. Stomatal and residual conductances to CO2 also decreased after 1 day of flooding compared with those of unflooded plants with residual conductance severely limiting carbon assimilation after 4 days of flooding. Stomatal opening occurred in 75 to 90 minutes and rate of opening was unaffected by flooding. PMID:16664791

Evaluating the Applicability of Phi Coefficient in Indicating Habitat Preferences of Forest Soil Fauna Based on a Single Field Study in Subtropical China.

PubMed

Cui, Yang; Wang, Silong; Yan, Shaokui

2016-01-01

Phi coefficient directly depends on the frequencies of occurrence of organisms and has been widely used in vegetation ecology to analyse the associations of organisms with site groups, providing a characterization of ecological preference, but its application in soil ecology remains rare. Based on a single field experiment, this study assessed the applicability of phi coefficient in indicating the habitat preferences of soil fauna, through comparing phi coefficient-induced results with those of ordination methods in charactering soil fauna-habitat(factors) relationships. Eight different habitats of soil fauna were implemented by reciprocal transfer of defaunated soil cores between two types of subtropical forests. Canonical correlation analysis (CCorA) showed that ecological patterns of fauna-habitat relationships and inter-fauna taxa relationships expressed, respectively, by phi coefficients and predicted abundances calculated from partial redundancy analysis (RDA), were extremely similar, and a highly significant relationship between the two datasets was observed (Pillai's trace statistic = 1.998, P = 0.007). In addition, highly positive correlations between phi coefficients and predicted abundances for Acari, Collembola, Nematode and Hemiptera were observed using linear regression analysis. Quantitative relationships between habitat preferences and soil chemical variables were also obtained by linear regression, which were analogous to the results displayed in a partial RDA biplot. Our results suggest that phi coefficient could be applicable on a local scale in evaluating habitat preferences of soil fauna at coarse taxonomic levels, and that the phi coefficient-induced information, such as ecological preferences and the associated quantitative relationships with habitat factors, will be largely complementary to the results of ordination methods. The application of phi coefficient in soil ecology may extend our knowledge about habitat preferences and distribution-abundance relationships, which will benefit the understanding of biodistributions and variations in community compositions in the soil. Similar studies in other places and scales apart from our local site will be need for further evaluation of phi coefficient.

Evaluating the Applicability of Phi Coefficient in Indicating Habitat Preferences of Forest Soil Fauna Based on a Single Field Study in Subtropical China

PubMed Central

Cui, Yang; Wang, Silong; Yan, Shaokui

2016-01-01

Phi coefficient directly depends on the frequencies of occurrence of organisms and has been widely used in vegetation ecology to analyse the associations of organisms with site groups, providing a characterization of ecological preference, but its application in soil ecology remains rare. Based on a single field experiment, this study assessed the applicability of phi coefficient in indicating the habitat preferences of soil fauna, through comparing phi coefficient-induced results with those of ordination methods in charactering soil fauna-habitat(factors) relationships. Eight different habitats of soil fauna were implemented by reciprocal transfer of defaunated soil cores between two types of subtropical forests. Canonical correlation analysis (CCorA) showed that ecological patterns of fauna-habitat relationships and inter-fauna taxa relationships expressed, respectively, by phi coefficients and predicted abundances calculated from partial redundancy analysis (RDA), were extremely similar, and a highly significant relationship between the two datasets was observed (Pillai's trace statistic = 1.998, P = 0.007). In addition, highly positive correlations between phi coefficients and predicted abundances for Acari, Collembola, Nematode and Hemiptera were observed using linear regression analysis. Quantitative relationships between habitat preferences and soil chemical variables were also obtained by linear regression, which were analogous to the results displayed in a partial RDA biplot. Our results suggest that phi coefficient could be applicable on a local scale in evaluating habitat preferences of soil fauna at coarse taxonomic levels, and that the phi coefficient-induced information, such as ecological preferences and the associated quantitative relationships with habitat factors, will be largely complementary to the results of ordination methods. The application of phi coefficient in soil ecology may extend our knowledge about habitat preferences and distribution-abundance relationships, which will benefit the understanding of biodistributions and variations in community compositions in the soil. Similar studies in other places and scales apart from our local site will be need for further evaluation of phi coefficient. PMID:26930593

Embryonic common snapping turtles (Chelydra serpentina) preferentially regulate intracellular tissue pH during acid-base challenges.

PubMed

Shartau, Ryan B; Crossley, Dane A; Kohl, Zachary F; Brauner, Colin J

2016-07-01

The nests of embryonic turtles naturally experience elevated CO2 (hypercarbia), which leads to increased blood PCO2  and a respiratory acidosis, resulting in reduced blood pH [extracellular pH (pHe)]. Some fishes preferentially regulate tissue pH [intracellular pH (pHi)] against changes in pHe; this has been proposed to be associated with exceptional CO2 tolerance and has never been identified in amniotes. As embryonic turtles may be CO2 tolerant based on nesting strategy, we hypothesized that they preferentially regulate pHi, conferring tolerance to severe acute acid-base challenges. This hypothesis was tested by investigating pH regulation in common snapping turtles (Chelydra serpentina) reared in normoxia then exposed to hypercarbia (13 kPa PCO2 ) for 1 h at three developmental ages: 70% and 90% of incubation, and yearlings. Hypercarbia reduced pHe but not pHi, at all developmental ages. At 70% of incubation, pHe was depressed by 0.324 pH units while pHi of brain, white muscle and lung increased; heart, liver and kidney pHi remained unchanged. At 90% of incubation, pHe was depressed by 0.352 pH units but heart pHi increased with no change in pHi of other tissues. Yearlings exhibited a pHe reduction of 0.235 pH units but had no changes in pHi of any tissues. The results indicate common snapping turtles preferentially regulate pHi during development, but the degree of response is reduced throughout development. This is the first time preferential pHi regulation has been identified in an amniote. These findings may provide insight into the evolution of acid-base homeostasis during development of amniotes, and vertebrates in general. © 2016. Published by The Company of Biologists Ltd.

Evidence for the role of a Na(+)/HCO(3)(-) cotransporter in trout hepatocyte pHi regulation.

PubMed

Furimsky, M; Moon, T W; Perry, S F

2000-07-01

The mechanisms of intracellular pH (pHi) regulation were examined in hepatocytes of the rainbow trout Oncorhynchus mykiss. pHi was monitored using the pH-sensitive fluorescent dye BCECF, and the effects of various media and pharmacological agents were examined for their influence on baseline pHi and recovery rates from acid and base loading. Rates of Na(+) uptake were measured using (22)Na, and changes in membrane potential were examined using the potentiometric fluorescent dye Oxonol VI. The rate of proton extrusion following acid loading was diminished by the blockade of either Na(+)/H(+) exchange (using amiloride) or anion transport (using DIDS). The removal of external HCO(3)(-) and the abolition of outward K(+) diffusion by the channel blocker Ba(2+) also decreased the rate of proton extrusion following acid load. Depolarization of the cell membrane with 50 mmol l(-)(1) K(+), however, did not affect pHi. The rate of recovery from base loading was significantly diminished by the blockade of anion transport, removal of external HCO(3)(-) and, to a lesser extent, by blocking Na(+)/H(+) exchange. The blockade of K(+) conductance had no effect. The decrease in Na(+) uptake rate observed in the presence of the anion transport blocker DIDS and the DIDS-sensitive hyperpolarization of membrane potential during recovery from acid loading suggest that a Na(+)-dependent electrogenic transport system is involved in the restoration of pHi after intracellular acidification. The effects on baseline pHi indicate that the different membrane exchangers are tonically active in the maintenance of steady-state pHi. This study confirms the roles of a Na(+)/H(+) exchanger and a Cl(-)/HCO(3)(-) exchanger in the regulation of trout hepatocyte pHi and provides new evidence that a Na(+)/HCO(3)(-) cotransporter contributes to pHi regulation.

Intracellular pH regulation by acid-base transporters in mammalian neurons

PubMed Central

Ruffin, Vernon A.; Salameh, Ahlam I.; Boron, Walter F.; Parker, Mark D.

2014-01-01

Intracellular pH (pHi) regulation in the brain is important in both physiological and physiopathological conditions because changes in pHi generally result in altered neuronal excitability. In this review, we will cover 4 major areas: (1) The effect of pHi on cellular processes in the brain, including channel activity and neuronal excitability. (2) pHi homeostasis and how it is determined by the balance between rates of acid loading (JL) and extrusion (JE). The balance between JE and JL determine steady-state pHi, as well as the ability of the cell to defend pHi in the face of extracellular acid-base disturbances (e.g., metabolic acidosis). (3) The properties and importance of members of the SLC4 and SLC9 families of acid-base transporters expressed in the brain that contribute to JL (namely the Cl-HCO3 exchanger AE3) and JE (the Na-H exchangers NHE1, NHE3, and NHE5 as well as the Na+- coupled HCO3− transporters NBCe1, NBCn1, NDCBE, and NBCn2). (4) The effect of acid-base disturbances on neuronal function and the roles of acid-base transporters in defending neuronal pHi under physiopathologic conditions. PMID:24592239

Comparative evaluation of urinary PCA3 and TMPRSS2: ERG scores and serum PHI in predicting prostate cancer aggressiveness.

PubMed

Tallon, Lucile; Luangphakdy, Devillier; Ruffion, Alain; Colombel, Marc; Devonec, Marian; Champetier, Denis; Paparel, Philippe; Decaussin-Petrucci, Myriam; Perrin, Paul; Vlaeminck-Guillem, Virginie

2014-07-30

It has been suggested that urinary PCA3 and TMPRSS2:ERG fusion tests and serum PHI correlate to cancer aggressiveness-related pathological criteria at prostatectomy. To evaluate and compare their ability in predicting prostate cancer aggressiveness, PHI and urinary PCA3 and TMPRSS2:ERG (T2) scores were assessed in 154 patients who underwent radical prostatectomy for biopsy-proven prostate cancer. Univariate and multivariate analyses using logistic regression and decision curve analyses were performed. All three markers were predictors of a tumor volume≥0.5 mL. Only PHI predicted Gleason score≥7. T2 score and PHI were both independent predictors of extracapsular extension(≥pT3), while multifocality was only predicted by PCA3 score. Moreover, when compared to a base model (age, digital rectal examination, serum PSA, and Gleason sum at biopsy), the addition of both PCA3 score and PHI to the base model induced a significant increase (+12%) when predicting tumor volume>0.5 mL. PHI and urinary PCA3 and T2 scores can be considered as complementary predictors of cancer aggressiveness at prostatectomy.

Imaging of Intracellular pH in Tumor Spheroids Using Genetically Encoded Sensor SypHer2.

PubMed

Zagaynova, Elena V; Druzhkova, Irina N; Mishina, Natalia M; Ignatova, Nadezhda I; Dudenkova, Varvara V; Shirmanova, Marina V

2017-01-01

Intracellular pH (pHi) is one of the most important parameters that regulate the physiological state of cells and tissues. pHi homeostasis is crucial for normal cell functioning. Cancer cells are characterized by having a higher (neutral to slightly alkaline) pHi and lower (acidic) extracellular pH (pHe) compared to normal cells. This is referred to as a "reversed" pH gradient, and is essential in supporting their accelerated growth rate, invasion and migration, and in suppressing anti-tumor immunity, the promotion of metabolic coupling with fibroblasts and in preventing apoptosis. Moreover, abnormal pH, both pHi and pHe, contribute to drug resistance in cancers. Therefore, the development of methods for measuring pH in living tumor cells is likely to lead to better understanding of tumor biology and to open new ways for cancer treatment. Genetically encoded, fluorescent, pH-sensitive probes represent promising instruments enabling the subcellular measurement of pHi with unrivaled specificity and high accuracy. Here, we describe a protocol for pHi imaging at a microscopic level in HeLa tumor spheroids, using the genetically encoded ratiometric (dual-excitation) pHi indicator, SypHer2.

Bacteriophage phi 6 RNA-dependent RNA polymerase: molecular details of initiating nucleic acid synthesis without primer.

PubMed

Laurila, Minni R L; Makeyev, Eugene V; Bamford, Dennis H

2002-05-10

Like most RNA polymerases, the polymerase of double-strand RNA bacteriophage phi6 (phi6pol) is capable of primer-independent initiation. Based on the recently solved phi6pol initiation complex structure, a four-amino acid-long loop (amino acids 630-633) has been suggested to stabilize the first two incoming NTPs through stacking interactions with tyrosine, Tyr(630). A similar loop is also present in the hepatitis C virus polymerase, another enzyme capable of de novo initiation. Here, we use a series of phi6pol mutants to address the role of this element. As predicted, mutants at the Tyr(630) position are inefficient in initiation de novo. Unexpectedly, when the loop is disordered by changing Tyr(630)-Lys(631)-Trp(632) to GSG, phi6pol becomes a primer-dependent enzyme, either extending complementary oligonucleotide or, when the template 3' terminus can adopt a hairpin-like conformation, utilizing a "copy-back" initiation mechanism. In contrast to the wild-type phi6pol, the GSG mutant does not require high GTP concentration for its optimal activity. These findings suggest a general model for the initiation of de novo RNA synthesis.

Characterization of group H streptococcal temperate bacteriophage phi 227.

PubMed

Nugent, K M; Cole, R M

1977-03-01

phi 227, a temperate phage from a group H streptococcus (Streptococcus sanguis), was propagated vegetatively in group H strain Wicky 4-EryR, and its characteristics were determined. A procedure dependent on multiplicity of infection, incubation time, and treatment of crude lysates with diatomaceous earth was found to optimize phage yield, resulting in titers of 1 X 10(10) to 2 X 10(10) PFU/ml. Without prior treatment with diatomaceous earth, subsequent purification procedures (methanol, ammonium sulfate, polyethylene glycol) gave recoveries of less than 1% of crude lysate titers. Adsorption of phi227 to host cells was relatively unaffected by the medium, but calcium (not substituted by magnesium) was required for formation of infectious centers. The phage receptor was present on purified cell walls, resisted trypsin and heat, and was removed ty hydrochloric acid, trichloracetic acid, and hot formamide: however, formamide-extracted material failed to inactivate phage, and the nature of the receptor is unknown. Single-step growth experiments showed a latent period of 39 min and a burst size of 100 PFU/infectious center; results were unaffected by omission of supplemental Ca2+, by supplementation with Mg2, addition of glucose, or changes of pH between 6.35 and 8.0; but increased temperature (40 to 43 degrees C) shortened the latent period and decreased the burst size. The latent period was prolonged in genetically competent host cells and in chemically defined medium; and in the latter, the burst size was smaller. Phage replication was sensitive to those metabolic inhibitors which inhibited the host streptococcus: these included rifampin, fluorodeoxyuridine, hydroxyurea, dihydrostreptomycin, and 6-P-hydroxyphenylazouracil. The data suggest that phi227 does not code for a rifampin-resistant RNA polymerase. However, in a rifampin-resistant host strain, phage replication and lysogen formation were both decreased suggesting that altered host core polymerase had less affinity for (some) promotors on the phi227 template. In transfection, a Ca2+-dependent stabilization step that was inhibited by Mg2+ was demonstrated; transformation was not affected by either Ca2+ or Mg2+, and the site and nature of the stabilization are unknown. More than one molecule of DNA was required for plaque formation. Biophysical characterization showed a type B phage of buoyant density (CsCl) 1.50, containing five proteins and 54.8% DNA. The duplex linear DNA had a molecular weight (calculated from contour length) of 23.2 X 10(6) and a guanine plus cytosine content (calculated from melting point) of 42.3 mol%. Similar characterizations of streptococcal phages, including biophysical data, have not been previously available.

Fundamental Quantum 1/F Noise in Ultrasmall Semiconductor Devices and Their Optimal Design Principles

DTIC Science & Technology

1988-05-31

Hooge parameter. 2. 1 / f Noise of the Recombination Current Generated in the Depletion Region The quantum i/ f ...theory. There are two forms of quantum 11f noise . In the first place C~ and Cn4 p n to quantum 1 / f noise theory. This would yield Hooge parameters S...Fundamental Quantum 1 / f Noise in Ultrasmall S~ iodcrD’vesadOtm.Dsgn P in. 12. PERSONAL AUTHOR(S) Handel, Peter H. (Princioal investiaat r) 13a. TYPE

Proceedings of the Quantum Computation for Physical Modeling Workshop 2004. Held in North Falmouth, MA on 12-15 September 2004

DTIC Science & Technology

2005-10-01

late the difficulty of some basic 1-bit and n-bit quantum and classical operations in an simple unconstrained scenario. KEY WORDS: Time evolution... quantum circuit and design are presented for an optimized entangling probe attacking the BB84 Protocol of quantum key distribution (QKD) and yielding...unambiguous, at least some of the time. It follows that the BB84 (Bennett-Brassard 1984) proto- col of quantum key distribution has a vulnerability similar to

Interaction of Water-Soluble CdTe Quantum Dots with Bovine Serum Albumin

PubMed Central

2011-01-01

Semiconductor nanoparticles (quantum dots) are promising fluorescent markers, but it is very little known about interaction of quantum dots with biological molecules. In this study, interaction of CdTe quantum dots coated with thioglycolic acid (TGA) with bovine serum albumin was investigated. Steady state spectroscopy, atomic force microscopy, electron microscopy and dynamic light scattering methods were used. It was explored how bovine serum albumin affects stability and spectral properties of quantum dots in aqueous media. CdTe–TGA quantum dots in aqueous solution appeared to be not stable and precipitated. Interaction with bovine serum albumin significantly enhanced stability and photoluminescence quantum yield of quantum dots and prevented quantum dots from aggregating. PMID:27502633

77 FR 71172 - Proposed Collection; Comment Request

Federal Register 2010, 2011, 2012, 2013, 2014

2012-11-29

... beneficiaries on their TRICARE benefits. Personal health information (PHI) and personally identifiable.../PHI to obtain and verify TRICARE eligibility, treatment, payment, and other healthcare operations... during the case resolution process, individuals may object to the collection of PHI and PII via verbal or...

Spectral observations of Be stars in the visible range. I - Phi Per, Psi Per, 11 Cam, and Phi And

NASA Astrophysics Data System (ADS)

Krugov, V. D.

1986-02-01

Phi Per was found to display considerable variations of emission in H-alpha and H-beta. The H-alpha and H-beta emission profiles of Psi Per appeared to vary with a period of several years. A complete disappearance of H-alpha emission was observed for 11 Cam. Finally, the H-alpha emission for Phi And did not display intensity variations during the entire period of observations in 1983.

The Effects of Exercise on Pharmacokinetics and Pharmacodynamics of Physostigmine in Rats

DTIC Science & Technology

1989-02-15

Phy ( cholinesterase activity ) are likely to be altered by exercise due to altered blood flow rates to liver and pH of muscle. During exercise...concurrent acute exercise on the ChE activity in RBC aad tissues and in blood biochemical parameters in rats. Phy has been reported to reduce the...Springfield, Illinois. Also, we have studied the effect of exercise training, Phy and training + Phy on ChE activity in RBC and tissues and on blood biochemi

New evidence for primordial action site of Fluazifop-P-butyl on Acanthospermum hispidum seedlings: From the effects on chlorophyll fluorescence characteristics and histological observation.

PubMed

Shang, Yuhong; Yang, Congjun; Liu, Zhihang; Song, Jiqing; Li, Pingliang; Li, Lingxu; Zhou, Fei; Xin, Hua; Wan, Fanghao; Matsumoto, Hiroshi; Luo, Xiaoyong

2017-10-01

Acanthospermum hispidum DC, an Asteraceae weed species, was very susceptible to fluazifop-P-butyl, but tolerant to other aryloxyphenoxypropionate herbicides, such as haloxyfop-P-methyl. However, other Asteraceae weeds including Bidens pilosa were all tolerant to fluazifop-P-butyl. Membrane lipid peroxidation by increasing the levels of reactive oxygen species (ROS) was proposed as an action mechanism of fluazifop-P-butyl in A. hispidum. To further clarify the primordial action site of fluazifop-P-butyl in this species, the effects on chlorophyll fluorescence characteristics and cytohistology of apical meristems were studied. Chlorophyll fluorescence characteristics (CFC) in sensitive A. hispidum seedlings were markedly affected by 10μM fluazifop-P-butyl, with the dark fluorescence yield (Fo), maximal fluorescence yield (Fm), maximal PS II quantum yield (Fv/Fm), effective photosystem II (PS II) quantum yield [Y(II)], and quantum yield of regulated energy dissipation [Y(NPQ)] declining, quantum yield of nonregulated energy dissipation [Y(NO)] rising, but these measures were not affected in Bidens pilosa. The effects of fluazifop-P-butyl on chlorophyll fluorescence properties were observed on the growing point before the mature leaves by about 4-6h. Haloxyfop-P-methyl, a control herbicide, had no effects on CFC of either A. hispidum or B. pilosa. In addition, damage to apical meristem cells of A. hispidum was observed at 6 HAT prior to changes in chlorophyll fluorescence parameters suggesting that the primary action site of fluazifop-P-butyl in this species is in the apical meristem and the effects on CFC may be the results of secondary action. Copyright © 2017 Elsevier Inc. All rights reserved.

Can time-dependent density functional theory predict intersystem crossing in organic chromophores? A case study on benzo(bis)-X-diazole based donor-acceptor-donor type molecules.

PubMed

Tam, Teck Lip Dexter; Lin, Ting Ting; Chua, Ming Hui

2017-06-21

Here we utilized new diagnostic tools in time-dependent density functional theory to explain the trend of intersystem crossing in benzo(bis)-X-diazole based donor-acceptor-donor type molecules. These molecules display a wide range of fluorescence quantum yields and triplet yields, making them excellent candidates for testing the validity of these diagnostic tools. We believe that these tools are cost-effective and can be applied to structurally similar organic chromophores to predict/explain the trends of intersystem crossing, and thus fluorescence quantum yields and triplet yields without the use of complex and expensive multireference configuration interaction or multireference pertubation theory methods.

Quantum coherence effects in natural light-induced processes: cis-trans photoisomerization of model retinal under incoherent excitation.

PubMed

Tscherbul, Timur V; Brumer, Paul

2015-12-14

We present a theoretical study of quantum coherence effects in the primary cis-trans photoisomerization of retinal in rhodopsin induced by incoherent solar light. Using the partial secular Bloch-Redfield quantum master equation approach based on a two-state two-mode linear vibronic coupling model of the retinal chromophore [S. Hahn and G. Stock, J. Phys. Chem. B, 2000, 104, 1146-1149], we show that a sudden turn-on of incoherent pumping can generate substantial Fano coherences among the excited states of retinal. These coherences are the most pronounced in the regime where the matrix elements of the transition dipole moment between the ground and excited eigenstates are parallel to one another. We show that even when the transition dipole moments are perpendicular (implying the absence of light-induced Fano coherence) a small amount of excited-state coherence is still generated due to the coupling to intramolecular vibrational modes and the protein environment, causing depopulation of the excited eigenstates. The overall effect of the coherences on the steady-state population and on the photoproduct quantum yield is shown to be small; however we observe a significant transient effect on the formation of the trans photoproduct, enhancing the photoreaction quantum yield by ∼11% at 200 fs. These calculations suggest that coupling to intramolecular vibrational modes and the protein environment play an important role in photoreaction dynamics, suppressing oscillations in the quantum yield associated with Fano interference.

PHI and PCA3 improve the prognostic performance of PRIAS and Epstein criteria in predicting insignificant prostate cancer in men eligible for active surveillance.

PubMed

Cantiello, Francesco; Russo, Giorgio Ivan; Cicione, Antonio; Ferro, Matteo; Cimino, Sebastiano; Favilla, Vincenzo; Perdonà, Sisto; De Cobelli, Ottavio; Magno, Carlo; Morgia, Giuseppe; Damiano, Rocco

2016-04-01

To assess the performance of prostate health index (PHI) and prostate cancer antigen 3 (PCA3) when added to the PRIAS or Epstein criteria in predicting the presence of pathologically insignificant prostate cancer (IPCa) in patients who underwent radical prostatectomy (RP) but eligible for active surveillance (AS). An observational retrospective study was performed in 188 PCa patients treated with laparoscopic or robot-assisted RP but eligible for AS according to Epstein or PRIAS criteria. Blood and urinary specimens were collected before initial prostate biopsy for PHI and PCA3 measurements. Multivariate logistic regression analyses and decision curve analysis were carried out to identify predictors of IPCa using the updated ERSPC definition. At the multivariate analyses, the inclusion of both PCA3 and PHI significantly increased the accuracy of the Epstein multivariate model in predicting IPCa with an increase of 17 % (AUC = 0.77) and of 32 % (AUC = 0.92), respectively. The inclusion of both PCA3 and PHI also increased the predictive accuracy of the PRIAS multivariate model with an increase of 29 % (AUC = 0.87) and of 39 % (AUC = 0.97), respectively. DCA revealed that the multivariable models with the addition of PHI or PCA3 showed a greater net benefit and performed better than the reference models. In a direct comparison, PHI outperformed PCA3 performance resulting in higher net benefit. In a same cohort of patients eligible for AS, the addition of PHI and PCA3 to Epstein or PRIAS models improved their prognostic performance. PHI resulted in greater net benefit in predicting IPCa compared to PCA3.

Distinct moieties underlie biphasic H+ gating of connexin43 channels, producing a pH optimum for intercellular communication

PubMed Central

Garciarena, Carolina D.; Malik, Akif; Swietach, Pawel; Moreno, Alonso P.; Vaughan-Jones, Richard D.

2018-01-01

Most mammalian cells can intercommunicate via connexin-assembled, gap-junctional channels. To regulate signal transmission, connexin (Cx) channel permeability must respond dynamically to physiological and pathophysiological stimuli. One key stimulus is intracellular pH (pHi), which is modulated by a tissue’s metabolic and perfusion status. Our understanding of the molecular mechanism of H+ gating of Cx43 channels—the major isoform in the heart and brain—is incomplete. To interrogate the effects of acidic and alkaline pHi on Cx43 channels, we combined voltage-clamp electrophysiology with pHi imaging and photolytic H+ uncaging, performed over a range of pHi values. We demonstrate that Cx43 channels expressed in HeLa or N2a cell pairs are gated biphasically by pHi via a process that consists of activation by H+ ions at alkaline pHi and inhibition at more acidic pHi. For Cx43 channel–mediated solute/ion transmission, the ensemble of these effects produces a pHi optimum, near resting pHi. By using Cx43 mutants, we demonstrate that alkaline gating involves cysteine residues of the C terminus and is independent of motifs previously implicated in acidic gating. Thus, we present a molecular mechanism by which cytoplasmic acid–base chemistry fine tunes intercellular communication and establishes conditions for the optimal transmission of solutes and signals in tissues, such as the heart and brain.—Garciarena, C. D., Malik, A., Swietach, P., Moreno, A. P., Vaughan-Jones, R. D. Distinct moieties underlie biphasic H+ gating of connexin43 channels, producing a pH optimum for intercellular communication. PMID:29183963

Prostate health index (phi) and prostate cancer antigen 3 (PCA3) significantly improve diagnostic accuracy in patients undergoing prostate biopsy.

PubMed

Perdonà, Sisto; Bruzzese, Dario; Ferro, Matteo; Autorino, Riccardo; Marino, Ada; Mazzarella, Claudia; Perruolo, Giuseppe; Longo, Michele; Spinelli, Rosa; Di Lorenzo, Giuseppe; Oliva, Andrea; De Sio, Marco; Damiano, Rocco; Altieri, Vincenzo; Terracciano, Daniela

2013-02-15

Prostate health index (phi) and prostate cancer antigen 3 (PCA3) have been recently proposed as novel biomarkers for prostate cancer (PCa). We assessed the diagnostic performance of these biomarkers, alone or in combination, in men undergoing first prostate biopsy for suspicion of PCa. One hundred sixty male subjects were enrolled in this prospective observational study. PSA molecular forms, phi index (Beckman coulter immunoassay), PCA3 score (Progensa PCA3 assay), and other established biomarkers (tPSA, fPSA, and %fPSA) were assessed before patients underwent a 18-core first prostate biopsy. The discriminating ability between PCa-negative and PCa-positive biopsies of Beckman coulter phi and PCA3 score and other used biomarkers were determined. One hundred sixty patients met inclusion criteria. %p2PSA (p2PSA/fPSA × 100), phi and PCA3 were significantly higher in patients with PCa compared to PCa-negative group (median values: 1.92 vs. 1.55, 49.97 vs. 36.84, and 50 vs. 32, respectively, P ≤ 0.001). ROC curve analysis showed that %p2PSA, phi, and PCA3 are good indicator of malignancy (AUCs = 0.68, 0.71, and 0.66, respectively). A multivariable logistic regression model consisting of both the phi index and PCA3 score allowed to reach an overall diagnostic accuracy of 0.77. Decision curve analysis revealed that this "combined" marker achieved the highest net benefit over the examined range of the threshold probability. phi and PCA3 showed no significant difference in the ability to predict PCa diagnosis in men undergoing first prostate biopsy. However, diagnostic performance is significantly improved by combining phi and PCA3. Copyright © 2012 Wiley Periodicals, Inc.

Optimal future liver remnant in patients treated with extensive preoperative chemotherapy for colorectal liver metastases.

PubMed

Shindoh, Junichi; Tzeng, Ching-Wei D; Aloia, Thomas A; Curley, Steven A; Zimmitti, Giuseppe; Wei, Steven H; Huang, Steven Y; Mahvash, Armeen; Gupta, Sanjay; Wallace, Michael J; Vauthey, Jean-Nicolas

2013-08-01

Patients with colorectal liver metastases (CLM) are increasingly treated with preoperative chemotherapy. Chemotherapy associated liver injury is associated with postoperative hepatic insufficiency (PHI) and mortality. The adequate minimum future liver remnant (FLR) volume in patients treated with extensive chemotherapy remains unknown. All patients with standardized FLR > 20 %, who underwent extended right hepatectomy for CLM from 1993-2011, were divided into three cohorts by chemotherapy duration: no chemotherapy (NC, n = 30), short duration (SD, ≤12 weeks, n = 78), long duration (LD, >12 weeks, n = 86). PHI and mortality were compared by using uni-/multivariate analyses. Optimal FLR for LD chemotherapy was determined using a minimum p-value approach. A total of 194 patients met inclusion criteria. LD chemotherapy was significantly associated with PHI (NC + SD 3.7 vs. LD 16.3%, p = 0.006). Ninety-day mortality rates were 0 % in NC, 1.3 % in SD, and 2.3% in LD patients, respectively (p = 0.95). In patients with FLR > 30 %, PHI occurred in only two patients (both LD, 2/20, 10 %), but all patients with FLR > 30 % survived. The best cutoff of FLR for preventing PHI after chemotherapy >12 weeks was estimated as >30 %. Both LD chemotherapy (odds ratio [OR] 5.4, p = 0.004) and FLR ≤ 30 % (OR 6.3, p = 0.019) were independent predictors of PHI. Preoperative chemotherapy >12 weeks increases the risk of PHI after extended right hepatectomy. In patients treated with long-duration chemotherapy, FLR > 30 % reduces the rate of PHI and may provide enough functional reserve for clinical rescue if PHI develops.

Effects of plasmalemmal V-ATPase activity on plasma membrane potential of resident alveolar macrophages.

PubMed

Heming, T A; Bidani, A

2003-01-01

The acid-base status and functional responses of alveolar macrophages (mphi) are influenced by the activity of plasmalemmal V-type H+-pump (V-ATPase), an electrogenic H+ extruder that provides a possible link between intracellular pH (pHi) and plasma membrane potential (Em). This study examined the relationships among Em, pHi, and plasmalemmal V-ATPase activity in resident alveolar mphi from rabbits. Em and pHi were measured using fluorescent probes. Em was -46 mV and pHi was 7.14 at an extracellular pH (pHo) of 7.4. The pHi declined progressively at lower pHo values. Decrements in pHo, also caused depolarization of the plasma membrane, independent of V-ATPase activity. The pH effects on Em were sensitive to external K+, and hence, probably involved pH-sensitive K+ conductance. H+ were not distributed at equilibrium across the plasma membrane. V-ATPase activity was a major determinant of the transmembrane H+ disequilibrium. Pump inhibition with bafilomycin A1 caused cytosolic acidification, due most likely to the retention of metabolically generated H+. V-ATPase inhibition also caused depolarization of the plasma membrane, but the effects were mediated indirectly via the accompanying pHi changes. V-ATPase activity was sensitive to Em. Em hyperpolarization (valinomycin-clamp) reduced V-ATPase activity, causing an acidic shift in baseline pHi under steady-state conditions and slowing pHi recovery from NH4Cl prepulse acid-loads. The findings indicate that a complex relationship exists among Em, pHi, and pHo that was partially mediated by plasmalemmal V-ATPase activity. This relationship could have important consequences for the expression of pH- and/or voltage-sensitive functions in alveolar mphi.

Lunisolar tidal force and its relationship to chlorophyll fluorescence in Arabidopsis thaliana.

PubMed

Fisahn, Joachim; Klingelé, Emile; Barlow, Peter

2015-01-01

The yield of chlorophyll fluorescence Ft was measured in leaves of Arabidopsis thaliana over periods of several days under conditions of continuous illumination (LL) without the application of saturating light pulses. After linearization of the time series of the chlorophyll fluorescence yield (ΔFt), oscillations became apparent with periodicities in the circatidal range. Alignments of these linearized time series ΔFt with the lunisolar tidal acceleration revealed high degrees of synchrony and phase congruence. Similar congruence with the lunisolar tide was obtained with the linearized quantum yield of PSII (ΔФII), recorded after application of saturating light pulses. These findings strongly suggest that there is an exogenous timekeeper which is a stimulus for the oscillations detected in both the linearized yield of chlorophyll fluorescence (ΔFt) and the linearized quantum yield of PSII (ΔФII).

Lunisolar tidal force and its relationship to chlorophyll fluorescence in Arabidopsis thaliana

PubMed Central

Fisahn, Joachim; Klingelé, Emile; Barlow, Peter

2015-01-01

The yield of chlorophyll fluorescence Ft was measured in leaves of Arabidopsis thaliana over periods of several days under conditions of continuous illumination (LL) without the application of saturating light pulses. After linearization of the time series of the chlorophyll fluorescence yield (ΔFt), oscillations became apparent with periodicities in the circatidal range. Alignments of these linearized time series ΔFt with the lunisolar tidal acceleration revealed high degrees of synchrony and phase congruence. Similar congruence with the lunisolar tide was obtained with the linearized quantum yield of PSII (ΔФII), recorded after application of saturating light pulses. These findings strongly suggest that there is an exogenous timekeeper which is a stimulus for the oscillations detected in both the linearized yield of chlorophyll fluorescence (ΔFt) and the linearized quantum yield of PSII (ΔФII). PMID:26376108

X-Phi and Carnapian Explication

PubMed Central

Shepherd, Joshua; Justus, James

2015-01-01

The rise of experimental philosophy (x-phi) has placed metaphilosophical questions, particularly those concerning concepts, at the center of philosophical attention. X-phi offers empirically rigorous methods for identifying conceptual content, but what exactly it contributes towards evaluating conceptual content remains unclear. We show how x-phi complements Rudolf Carnap’s underappreciated methodology for concept determination, explication. This clarifies and extends x-phi’s positive philosophical import, and also exhibits explication’s broad appeal. But there is a potential problem: Carnap’s account of explication was limited to empirical and logical concepts, but many concepts of interest to philosophers (experimental and otherwise) are essentially normative. With formal epistemology as a case study, we show how x-phi assisted explication can apply to normative domains. PMID:26345713

High quantum yield of the Egyptian blue family of infrared phosphors (MCuSi4O10, M = Ca, Sr, Ba)

NASA Astrophysics Data System (ADS)

Berdahl, Paul; Boocock, Simon K.; Chan, George C.-Y.; Chen, Sharon S.; Levinson, Ronnen M.; Zalich, Michael A.

2018-05-01

The alkaline earth copper tetra-silicates, blue pigments, are interesting infrared phosphors. The Ca, Sr, and Ba variants fluoresce in the near-infrared (NIR) at 909, 914, and 948 nm, respectively, with spectral widths on the order of 120 nm. The highest quantum yield ϕ reported thus far is ca. 10%. We use temperature measurements in sunlight to determine this parameter. The yield depends on the pigment loading (mass per unit area) ω with values approaching 100% as ω → 0 for the Ca and Sr variants. Although maximum quantum yield occurs near ω = 0, maximum fluorescence occurs near ω = 70 g m-2, at which ϕ = 0.7. The better samples show fluorescence decay times in the range of 130 to 160 μs. The absorbing impurity CuO is often present. Good phosphor performance requires long fluorescence decay times and very low levels of parasitic absorption. The strong fluorescence enhances prospects for energy applications such as cooling of sunlit surfaces (to reduce air conditioning requirements) and luminescent solar concentrators.

Temporal variability in chlorophyll fluorescence of back-reef corals in Ofu, American Samoa

USGS Publications Warehouse

Piniak, G.A.; Brown, E.K.

2009-01-01

Change in the yield of chlorophyll a fluorescence is a common indicator of thermal stress in corals. The present study reports temporal variability in quantum yield measurements for 10 coral species in Ofu, American Samoa - a place known to experience elevated and variable seawater temperatures. In winter, the zooxanthellae generally had higher dark-adapted maximum quantum yield (F v/Fm), higher light- adapted effective quantum yield (??F/F'm), and lower relative electron transport rates (rETR) than in the summer. Temporal changes appeared unrelated to the expected bleaching sensitivity of corals. All species surveyed, with the exception of Montipora grisea, demonstrated significant temporal changes in the three fluorescence parameters. Fluorescence responses were influenced by the microhabitat - temporal differences in fluorescence parameters were usually observed in the habitat with a more variable temperature regime (pool 300), while differences in Fv/Fm between species were observed only in the more environmentally stable habitat (pool 400). Such species-specific responses and microhabitat variability should be considered when attempting to determine whether observed in situ changes are normal seasonal changes or early signs of bleaching. ?? 2009 Marine Biological Laboratory.

Photodynamic therapy potential of thiol-stabilized CdTe quantum dot-group 3A phthalocyanine conjugates (QD-Pc).

PubMed

Tekdaş, Duygu Aydın; Durmuş, Mahmut; Yanık, Hülya; Ahsen, Vefa

2012-07-01

Thiol stabilized CdTe quantum dot (QD) nanoparticles were synthesized in aqueous phase and were used as energy donors to tetra-triethyleneoxythia substituted aluminum, gallium and indium phthalocyanines through fluorescence resonance energy transfer (FRET). Energy transfer occurred from the QDs to phthalocyanines upon photoexcitation of the QDs. An enhancement in efficiency of energy transfer with the nature of the carboxylic thiol stabilizer on the QDs was observed. As a result of the nanoparticle and the phthalocyanine mixing, the photoluminescence efficiency of the phthalocyanine moieties in the mixtures does not strictly follow the quantum yields of the bare phthalocyanines. The photochemistry study of phthalocyanines in the presence of the QDs revealed high singlet oxygen quantum yield, hence the possibility of using QDs in combination with phthalocyanines as photosensitizers in photodynamic therapy of cancer. The fluorescence of the CdTe quantum dots-phthalocyanine conjugates (QDs-Pc) were effectively quenched by addition of 1,4-benzoquinone. Copyright © 2012 Elsevier B.V. All rights reserved.

Scalable focused ion beam creation of nearly lifetime-limited single quantum emitters in diamond nanostructures

PubMed Central

Schröder, Tim; Trusheim, Matthew E.; Walsh, Michael; Li, Luozhou; Zheng, Jiabao; Schukraft, Marco; Sipahigil, Alp; Evans, Ruffin E.; Sukachev, Denis D.; Nguyen, Christian T.; Pacheco, Jose L.; Camacho, Ryan M.; Bielejec, Edward S.; Lukin, Mikhail D.; Englund, Dirk

2017-01-01

The controlled creation of defect centre—nanocavity systems is one of the outstanding challenges for efficiently interfacing spin quantum memories with photons for photon-based entanglement operations in a quantum network. Here we demonstrate direct, maskless creation of atom-like single silicon vacancy (SiV) centres in diamond nanostructures via focused ion beam implantation with ∼32 nm lateral precision and <50 nm positioning accuracy relative to a nanocavity. We determine the Si+ ion to SiV centre conversion yield to be ∼2.5% and observe a 10-fold conversion yield increase by additional electron irradiation. Low-temperature spectroscopy reveals inhomogeneously broadened ensemble emission linewidths of ∼51 GHz and close to lifetime-limited single-emitter transition linewidths down to 126±13 MHz corresponding to ∼1.4 times the natural linewidth. This method for the targeted generation of nearly transform-limited quantum emitters should facilitate the development of scalable solid-state quantum information processors. PMID:28548097

Scalable focused ion beam creation of nearly lifetime-limited single quantum emitters in diamond nanostructures

DOE PAGES

Schroder, Tim; Trusheim, Matthew E.; Walsh, Michael; ...

2017-05-26

The controlled creation of defect centre—nanocavity systems is one of the outstanding challenges for efficiently interfacing spin quantum memories with photons for photon-based entanglement operations in a quantum network. Here we demonstrate direct, maskless creation of atom-like single silicon vacancy (SiV) centres in diamond nanostructures via focused ion beam implantation with ~32 nm lateral precision and <50 nm positioning accuracy relative to a nanocavity. We determine the Si+ ion to SiV centre conversion yield to be ~2.5% and observe a 10-fold conversion yield increase by additional electron irradiation. Low-temperature spectroscopy reveals inhomogeneously broadened ensemble emission linewidths of ~51 GHz andmore » close to lifetime-limited single-emitter transition linewidths down to 126±13 MHz corresponding to ~1.4 times the natural linewidth. Furthermore, this method for the targeted generation of nearly transform-limited quantum emitters should facilitate the development of scalable solid-state quantum information processors.« less

Scalable focused ion beam creation of nearly lifetime-limited single quantum emitters in diamond nanostructures

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

Schroder, Tim; Trusheim, Matthew E.; Walsh, Michael

The controlled creation of defect centre—nanocavity systems is one of the outstanding challenges for efficiently interfacing spin quantum memories with photons for photon-based entanglement operations in a quantum network. Here we demonstrate direct, maskless creation of atom-like single silicon vacancy (SiV) centres in diamond nanostructures via focused ion beam implantation with ~32 nm lateral precision and <50 nm positioning accuracy relative to a nanocavity. We determine the Si+ ion to SiV centre conversion yield to be ~2.5% and observe a 10-fold conversion yield increase by additional electron irradiation. Low-temperature spectroscopy reveals inhomogeneously broadened ensemble emission linewidths of ~51 GHz andmore » close to lifetime-limited single-emitter transition linewidths down to 126±13 MHz corresponding to ~1.4 times the natural linewidth. Furthermore, this method for the targeted generation of nearly transform-limited quantum emitters should facilitate the development of scalable solid-state quantum information processors.« less

Cellular reflectarray antenna and method of making same

NASA Technical Reports Server (NTRS)

Romanofsky, Robert R (Inventor)

2011-01-01

A method of manufacturing a cellular reflectarray antenna arranged in an m by n matrix of radiating elements for communication with a satellite includes steps of determining a delay .phi.m,n for each of said m by n matrix of elements of said cellular reflectarray antenna using sub-steps of: determining the longitude and latitude of operation, determining elevation and azimuth angles of the reflectarray with respect to the satellite and converting theta.sub.0 (.theta..sub.0) and phi.sub.0 (.phi..sub.0), determining .DELTA..beta..sub.m,n, the pointing vector correction, for a given inter-element spacing and wavelength, determining .DELTA..phi..sub.m,n, the spherical wave front correction factor, for a given radius from the central element and/or from measured data from the feed horn; and, determining a delay .phi.m,n for each of said m by n matrix of elements as a function of .DELTA..beta..sub.m,n and .DELTA..phi..sub.m,n.

Cellular reflectarray antenna and method of making same

NASA Technical Reports Server (NTRS)

Romanofsky, Robert R (Inventor)

2010-01-01

A method of manufacturing a cellular reflectarray antenna arranged in an m by n matrix of radiating elements for communication with a satellite includes steps of determining a delay .phi.m,n for each of said m by n matrix of elements of said cellular reflectarray antenna using sub-steps of: determining the longitude and latitude of operation, determining elevation and azimuth angles of the reflectarray with respect to the satellite and converting theta.sub.0 (.theta..sub.0) and phi.sub.0 (.phi..sub.0), determining .DELTA..beta..sub.m,n, the pointing vector correction, for a given inter-element spacing and wavelength, determining .DELTA..phi..sub.m,n, the spherical wave front correction factor, for a given radius from the central element and/or from measured data from the feed horn; and, determining a delay .phi.m,n for each of said m by n matrix of elements as a function of .DELTA..beta..sub.m,n and .DELTA..phi..sub.m,n..

An RR Lyrae period shift in terms of the Fourier parameter Phi sub 31

NASA Technical Reports Server (NTRS)

Clement, Christine M.; Jankulak, Michael; Simon, Norman R.

1992-01-01

The Fourier phase parameter Phi sub 31 has been determined for RRc stars in five globular clusters, NGC 6171, M5, M3, M53, and M15. The results indicate that the RRc stars in a given cluster show a sequence of Phi sub 31 increasing with period, and that the higher the cluster metallicity, the higher the sequence lies in a plot of Phi sub 31 with period. The Phi sub 31 values for the stars in NGC 6171 and M5 presented here are based on observations made with the University of Toronto 0.61 m telescope at Las Campanas, Chile, while those for M3, M53, and M15 are based on published data. A bootstrap procedure has been used to establish the uncertainties in the Fourier parameters. The physical significance of the relationship among Phi sub 31, period, and metallicity is not yet understood. It will need to be tested with hydrodynamic pulsation models computed with new opacities.