Demonstration of thermal dissipation of absorbed quanta during energy-dependent quenching of chlorophyll fluorescence in photosynthetic membranes.

PubMed

Yahyaoui, W; Harnois, J; Carpentier, R

1998-11-27

When plant leaves or chloroplasts are exposed to illumination that exceeds their photosynthetic capacity, photoprotective mechanisms such as described by the energy-dependent (non-photochemical) quenching of chlorophyll fluorescence are involved. The protective action is attributed to an increased rate constant for thermal dissipation of absorbed quanta. We applied photoacoustic spectroscopy to monitor thermal dissipation in spinach thylakoid membranes together with simultaneous measurement of chlorophyll fluorescence in the presence of inhibitors of opposite action on the formation of delta pH across the thylakoid membrane (tentoxin and nigericin/valinomycin). A linear relationship between the appearance of fluorescence quenching during formation of the delta pH and the reciprocal variation of thermal dissipation was demonstrated. Dicyclohexylcarbodiimide, which is known to prevent protonation of the minor light-harvesting complexes of photosystem II, significantly reduced the formation of fluorescence quenching and the concurrent increase in thermal dissipation. However, the addition of exogenous ascorbate to activate the xanthophyll de-epoxidase increased non-photochemical fluorescence quenching without affecting the measured thermal dissipation. It is concluded that a portion of energy-dependent fluorescence quenching that is independent of de-epoxidase activity can be readily measured by photoacoustic spectroscopy as an increase in thermal deactivation processes.

Characterization of imaging performance in differential phase contrast CT compared with the conventional CT: Spectrum of noise equivalent quanta NEQ(k)

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

Tang Xiangyang; Yang Yi; Tang Shaojie

Purpose: Differential phase contrast CT (DPC-CT) is emerging as a new technology to improve the contrast sensitivity of conventional attenuation-based CT. The noise equivalent quanta as a function over spatial frequency, i.e., the spectrum of noise equivalent quanta NEQ(k), is a decisive indicator of the signal and noise transfer properties of an imaging system. In this work, we derive the functional form of NEQ(k) in DPC-CT. Via system modeling, analysis, and computer simulation, we evaluate and verify the derived NEQ(k) and compare it with that of the conventional attenuation-based CT. Methods: The DPC-CT is implemented with x-ray tube and gratings.more » The x-ray propagation and data acquisition are modeled and simulated through Fresnel and Fourier analysis. A monochromatic x-ray source (30 keV) is assumed to exclude any system imperfection and interference caused by scatter and beam hardening, while a 360 Degree-Sign full scan is carried out in data acquisition to avoid any weighting scheme that may disrupt noise randomness. Adequate upsampling is implemented to simulate the x-ray beam's propagation through the gratings G{sub 1} and G{sub 2} with periods 8 and 4 {mu}m, respectively, while the intergrating distance is 193.6 mm (1/16 of the Talbot distance). The dimensions of the detector cell for data acquisition are 32 Multiplication-Sign 32, 64 Multiplication-Sign 64, 96 Multiplication-Sign 96, and 128 Multiplication-Sign 128 {mu}m{sup 2}, respectively, corresponding to a 40.96 Multiplication-Sign 40.96 mm{sup 2} field of view in data acquisition. An air phantom is employed to obtain the noise power spectrum NPS(k), spectrum of noise equivalent quanta NEQ(k), and detective quantum efficiency DQE(k). A cylindrical water phantom at 5.1 mm diameter and complex refraction coefficient n= 1 -{delta}+i{beta}= 1 -2.5604 Multiplication-Sign 10{sup -7}+i1.2353 Multiplication-Sign 10{sup -10} is placed in air to measure the edge transfer function, line spread function

Contextual essay for integrated thematic unit: Kids, Quarks, and Quanta

NASA Astrophysics Data System (ADS)

Draeger, Vicki Lee

This essay provides the research and rationale to support the theory that early adolescence is the best time to present an introduction to quantum mechanics. It supports the creation of an integrated thematic unit to be used with students ages 11--14 in an inclusion classroom without limiting the unit to only an inclusion setting. The first section sets forth five problems the unit was written to address. Citing The National Center for Education Statistics 2000 version of The Nation's Report Card, the problems with current practices in science education resulting in poor student performance are presented. References to Project 2061: Science for All Americans help to demonstrate that students with disabilities are seldom considered when physical science curriculum is being developed, supporting the position that equity in science education is necessary, while maintaining challenging subject matter. The problem of the poor quality of many physical science texts is addressed, with an emphasis on the importance of curricular connections. The poor quality of physical science teacher training in many university teacher training courses is discussed, and the nature of the integrated thematic unit as a curriculum design is examined with reference to what is considered the over-emphasis on "reality-based" content to the exclusion of abstract subject matter. Having presented the problems and supporting their validity, the essay then demonstrated how Kids, Quarks, and Quanta specifically addresses each problem. The two and a half year study of Dr. John Hubisz and the committee he formed under The David and Lucille Packard Foundation grant to review and critique the physical science textbooks currently used with early adolescents is often referenced to support both the problems of teacher training and the poor quality of many texts. Recent brain research conducted by researchers of the National Institute of Mental Health is used to support the presentation of more abstract

Results from the irradiation of stainless steel and copper by 23 MeV γ-quanta in the atmosphere of molecular deuterium at a pressure of 2 kbar

NASA Astrophysics Data System (ADS)

Didyk, A. Yu.; Wisniewski, R.

2014-05-01

Metal samples were arranged inside a "finger-type" high-pressure chamber (DHPC-FT) filled by deuterium. They were two aluminum rods, a copper rod, two specimens of homogeneous YMn2 alloy, and a stainless steel wire. The pressure of molecular deuterium in DHPC-FT was about 2 kbar. The samples were irradiated by braking γ-quanta at a threshold energy of 23 MeV. All the samples were studied using scanning electron microscopy (SEM) and X-ray (roentgen) microelement probe analysis (RMPA). Considerable changes in the surface structure and elemental composition were found for the samples of copper, aluminum, YMn2 alloy, and stainless steel. Unusual results were analyzed in detail and compared with the earlier data.

LEDs based upon AlGaInP heterostructures with multiple quantum wells: comparison of fast neutrons and gamma-quanta irradiation

NASA Astrophysics Data System (ADS)

Gradoboev, A. V.; Orlova, K. N.; Simonova, A. V.

2018-05-01

The paper presents the research results of watt and volt characteristics of LEDs based upon AlGaInP heterostructures with multiple quantum wells in the active region. The research is completed for LEDs (emission wavelengths 624 nm and 590 nm) under irradiation by fast neutron and gamma-quanta in passive powering mode. Watt-voltage characteristics in the average and high electron injection areas are described as a power function of the operating voltage. It has been revealed that the LEDs transition from average electron injection area to high electron injection area occurs by overcoming the transition area. It disappears as it get closer to the limit result of the irradiation LEDs that is low electron injection mode in the entire supply voltage range. It has been established that the gamma radiation facilitates initial defects restructuring only 42% compared to 100% when irradiation is performed by fast neutrons. Ratio between measured on the boundary between low and average electron injection areas current value and the contribution magnitude of the first stage LEDs emissive power reducing is established. It is allows to predict LEDs resistance to irradiation by fast neutrons and gamma rays.

Light quanta modulated characteristics of Ni uptake by Brassica juncea seedlings: the interdependence of plant metal concentration and biomass.

PubMed

Dasgupta-Schubert, N; Whelan, T; Reyes, M A; Lloren, C; Brandt, T T; Persans, M W

2007-01-01

The relationships between the concentration of metal in the growth medium, Cs, the concentration of metal absorbed by the plant, Cp, and the total biomass achieved, M, all of which are factors relevant to the efficiency of metal uptake and tolerance by the plant, have been investigated via the physiological response of Brassica juncea seedlings to Ni stress. The factorial growth experiments treated the Ni concentration in agar medium and the diurnal light quanta as independently variable parameters. Observations included the evidence of light enhancement of Ni toxicity in the root, as well as at the whole-plant level. The shoot mass index possibly is an indicator of the amount of shoot metal sequestration in B. juncea, as are the logarithmic variation of Cp with Cs and the power-law dependence of M on Cp. The sum total of these observations indicates that, for the Ni accumulating plant B. juncea, the overall metabolic allocation to either growth or metal tolerance of the plant is important. Neither a rapid biomass increase nor a high metal absorbed concentration favored the removal of high metal mass from the medium. Rather, the plants with a moderate rate of biomass growth and a moderate absorbed metal concentration demonstrated the ability to remove the maximum mass of metal from the medium. The implication of these results as related to the extant model of phyoextraction efficiency is discussed.

Role of edge superconducting states in trapping of multi-quanta vortices by microholes. Application of the bitter decoration technique

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

Bezryadin, A.; Pannetier, B.

1996-01-01

The Bitter decoration technique is used to study the trapping of single and multiple quanta vortices by a lattice of circular microholes. By keeping a thin superconducting layer (the bottom) inside each hole the authors are able to visualise the trapped vortices. From this they determine, for the first time, the filling factor FF, i.e. the number of vortices captured inside a hole. In all cases the sample is cooled at a constant field before making the decoration. Two qualitatively different states of the vortex crystal are observed: (1) In case when the interhole distance is much larger than themore » coherence length, the filling factor averaged over many identical holes () is a stepwise function of the magnetic flux (of the external field) through the hole, because each hole captures the same number of vortices. The density of fluxoids inside the openings is higher than in the uniform film, but much lower than it should be in the state of equilibrium. The authors claim that the number of trapped vortices is determined by the edge superconducting states which appear around each hole at the modified third critical field H{sub c3}* > H{sub c2}. Below H{sub c2} such states produce a surface barrier of a new type. This barrier for the vortex entrance and exit is due to the strong increase of the order parameter near the hole edge. It keeps constant the number of captured vortices during the cooling at a fixed field. (2) An increase of the hole density or of the hole radius initiates a sharp redistribution of fluxoids: all of them drop inside holes. This first order transition leads to a localization of all vortices and consequently to a qualitative change of the transport properties (TAFF in this case). In the resulting new state the filling factor is not any more the same for neighboring holes and its averaged value is equal to the frustration of the hole network.« less

Braiding light quanta

NASA Astrophysics Data System (ADS)

Iadecola, Thomas; Schuster, Thomas; Chamon, Claudio

The possibility that anyons -- quantum particles other than fermions or bosons -- can emerge in condensed matter systems has motivated generations of physicists. In addition to being of fundamental scientific importance, so-called non-Abelian anyons are particularly sought-after for potential applications to quantum computing. However, experimental evidence of anyons in electronic systems remains inconclusive. We propose to demonstrate non-Abelian braiding by injecting coherent states of light into ``topological guided modes'' in specially-fabricated photonic waveguide arrays. These modes are photonic analogues of topological zero modes in electronic systems. Light traveling inside spatially well-separated topological guided modes can be braided, leading to the accumulation of non-Abelian phases. We propose an optical interference experiment to probe this non-Abelian braiding directly. T.I. is supported by a National Science Foundation Graduate Research Fellowship under Grant No. DGE-1247312.

QUANTA Users Manual

DTIC Science & Technology

1980-07-01

WORKI, WORK2, ALOC, and FLAMB . The WORK1 array comprises a number of small arrays which have been read from input and will be utilized throughout the...of the WORK2 array at least as large as the maximum of the two. The size is the same for both the ALOC and FLAMB arrays. The ALOC array stores the...allocation matrix and the FLAMB array is used for the Lagrangian multiplier matrix. Their dimension should be set to 3 x NWPNS x NTGTS, where NTGTS is

A new method of differential structural analysis of gamma-family basic parameters

NASA Technical Reports Server (NTRS)

Melkumian, L. G.; Ter-Antonian, S. V.; Smorodin, Y. A.

1985-01-01

The maximum likelihood method is used for the first time to restore parameters of electron photon cascades registered on X-ray films. The method permits one to carry out a structural analysis of the gamma quanta family darkening spots independent of the gamma quanta overlapping degree, and to obtain maximum admissible accuracies in estimating the energies of the gamma quanta composing a family. The parameter estimation accuracy weakly depends on the value of the parameters themselves and exceeds by an order of the values obtained by integral methods.

Natural thermodynamics

NASA Astrophysics Data System (ADS)

Annila, Arto

2016-02-01

The principle of increasing entropy is derived from statistical physics of open systems assuming that quanta of actions, as undividable basic build blocks, embody everything. According to this tenet, all systems evolve from one state to another either by acquiring quanta from their surroundings or by discarding quanta to the surroundings in order to attain energetic balance in least time. These natural processes result in ubiquitous scale-free patterns: skewed distributions that accumulate in a sigmoid manner and hence span log-log scales mostly as straight lines. Moreover, the equation for least-time motions reveals that evolution is by nature a non-deterministic process. Although the obtained insight in thermodynamics from the notion of quanta in motion yields nothing new, it accentuates that contemporary comprehension is impaired when modeling evolution as a computable process by imposing conservation of energy and thereby ignoring that quantum of actions are the carriers of energy from the system to its surroundings.

Quanta of geometry and unification

NASA Astrophysics Data System (ADS)

Chamseddine, Ali H.

2016-11-01

This is a tribute to Abdus Salam’s memory whose insight and creative thinking set for me a role model to follow. In this contribution I show that the simple requirement of volume quantization in spacetime (with Euclidean signature) uniquely determines the geometry to be that of a noncommutative space whose finite part is based on an algebra that leads to Pati-Salam grand unified models. The Standard Model corresponds to a special case where a mathematical constraint (order one condition) is satisfied. This provides evidence that Salam was a visionary who was generations ahead of his time.

Triode for Magnetic Flux Quanta.

PubMed

Vlasko-Vlasov, V K; Colauto, F; Benseman, T; Rosenmann, D; Kwok, W-K

2016-11-15

In an electronic triode, the electron current emanating from the cathode is regulated by the electric potential on a grid between the cathode and the anode. Here we demonstrate a triode for single quantum magnetic field carriers, where the flow of individual magnetic vortices in a superconducting film is regulated by the magnetic potential of striae of soft magnetic strips deposited on the film surface. By rotating an applied in-plane field, the magnetic strip potential can be varied due to changes in the magnetic charges at the strip edges, allowing accelerated or retarded motion of magnetic vortices inside the superconductor. Scaling down our design and reducing the gap width between the magnetic stripes will enable controlled manipulation of individual vortices and creation of single flux quantum circuitry for novel high-speed low-power superconducting electronics.

Quanta of Geometry and Unification

NASA Astrophysics Data System (ADS)

Chamseddine, Ali H.

This is a tribute to Abdus Salam's memory whose insight and creative thinking set for me a role model to follow. In this contribution I show that the simple requirement of volume quantization in space-time (with Euclidean signature) uniquely determines the geometry to be that of a noncommutative space whose finite part is based on an algebra that leads to Pati-Salam grand unified models. The Standard Model corresponds to a special case where a mathematical constraint (order one condition) is satisfied. This provides evidence that Salam was a visionary who was generations ahead of his time.

Triode for magnetic flux quanta.

NASA Astrophysics Data System (ADS)

Vlasko-Vlasov, Vitalii; Colauto, Fabiano; Benseman, Timothy; Rosenmann, Daniel; Kwok, Wai-Kwong

We designed a magnetic vortex triode using an array of closely spaced soft magnetic Py strips on top of a Nb superconducting film. The strips act similar to the grid electrode in an electronic triode, where the electron flow is regulated by the grid potential. In our case, we tune the vortex motion by the magnetic charge potential of the strip edges, using a small magnetic field rotating in the film plane. The magnetic charges emerging at the stripe edges and proportional to the magnetization component perpendicular to the edge direction, form linear potential barriers or valleys for vortex motion in the superconducting layer. We directly imaged the normal flux penetration into the Py/Nb films and observed retarded or accelerated entry of the normal vortices depending on the in-plane magnetization direction in the stripes. The observed flux behavior is explained by interactions between magnetically charged lines and magnetic monopoles of vortices similar to those between electrically charged strings and point charges. We discuss the possibility of using our design for manipulation of individual vortices in high-speed, low-power superconducting electronic circuits. This work was supported by the U.S. DOE, Office of Science, Materials Sciences and Engineering Division, and Office of BES (contract DE-AC02-06CH11357). F. Colauto thanks the Sao Paulo Research Foundation FAPESP (Grant No. 2015/06.085-3).

Triode for Magnetic Flux Quanta

DOE PAGES

Vlasko-Vlasov, V. K.; Colauto, F.; Benseman, T.; ...

2016-11-15

In an electronic triode, the electron current emanating from the cathode is regulated by the electric potential on a grid between the cathode and the anode. Here we demonstrate a triode for single quantum magnetic field carriers, where the flow of individual magnetic vortices in a superconducting film is regulated by the magnetic potential of striae of soft magnetic strips deposited on the film surface. By rotating an applied in-plane field, the magnetic strip potential can be varied due to changes in the magnetic charges at the strip edges, allowing accelerated or retarded motion of magnetic vortices inside the superconductor.more » Scaling down our design and reducing the gap width between the magnetic stripes will enable controlled manipulation of individual vortices and creation of single flux quantum circuitry for novel high-speed low-power superconducting electronics.« less

Simulation of the Focal Spot of the Accelerator Bremsstrahlung Radiation

NASA Astrophysics Data System (ADS)

Sorokin, V.; Bespalov, V.

2016-06-01

Testing of thick-walled objects by bremsstrahlung radiation (BR) is primarily performed via high-energy quanta. The testing parameters are specified by the focal spot size of the high-energy bremsstrahlung radiation. In determining the focal spot size, the high- energy BR portion cannot be experimentally separated from the low-energy BR to use high- energy quanta only. The patterns of BR focal spot formation have been investigated via statistical modeling of the radiation transfer in the target material. The distributions of BR quanta emitted by the target for different energies and emission angles under normal distribution of the accelerated electrons bombarding the target have been obtained, and the ratio of the distribution parameters has been determined.

International multi-center evaluation of a novel chemiluminescence assay for the detection of anti-dsDNA antibodies.

PubMed

Bentow, C; Lakos, G; Martis, P; Wahl, E; Garcia, M; Viñas, O; Espinosa, G; Cervera, R; Sjöwall, C; Carmona-Fernandes, D; Santos, M J; Hanly, J G; Mahler, M

2016-07-01

Anti-double stranded desoxyribonucleic acid (anti-dsDNA) antibodies are considered fairly specific for systemic lupus erythematosus (SLE) and their quantification is useful for the clinical management of SLE patients. We assessed the diagnostic performance of the QUANTA Flash dsDNA chemiluminescent immunoassay (CIA) in comparison to an ELISA, using patients from five participating countries. The main focus was to evaluate the correlation between anti-dsDNA antibody results from the CIA and global SLE disease activity, as measured by the SLE Disease Activity Index 2000 (SLEDAI-2K). A total of 1431 samples (SLE, n = 843; disease controls, n = 588) from five countries (Canada, USA, Portugal, Sweden and Spain) were tested with QUANTA Flash dsDNA (Inova Diagnostics, San Diego, CA, USA). Data obtained with the QUANTA Lite dsDNA SC ELISA (Inova Diagnostics) were available for samples from three sites (Canada, USA and Sweden, n = 566). The SLEDAI-2K scores were available for 805 SLE patients and a cut-off of > 4 was used to define active disease. QUANTA Flash dsDNA had a sensitivity of 54.3% for the diagnosis of SLE, combined with 89.8% specificity. Anti-dsDNA antibody levels were significantly higher (p < 0.0001) in active SLE (SLEDAI-2K > 4; n = 232; median value 83.0 IU/mL) versus the inactive patients (n = 573; median value 22.3 IU/mL), and the SLEDAI-2K scoring correlated with their dsDNA antibody levels (Spearman's rho = 0.44, p < 0.0001). Similar but less pronounced findings were also found for the ELISA, in relation to disease activity. The QUANTA Flash dsDNA assay showed good clinical performance in a large international multi-center study. Additionally, the strong correlation between anti-dsDNA antibody results and SLEDAI-2K scores supported the potential utility of QUANTA Flash dsDNA for monitoring disease activity. © The Author(s) 2016.

USSR Report, Life Sciences Biomedical and Behavioral Sciences.

DTIC Science & Technology

1987-05-28

No 3, May-Jun 85) 64 Cytogenetic Effects of Gamma Quanta and of Secondary Emission Generated by 70 GeV Protons on Chinese Hamster Fibroblasts...Irradiation With Gamma Quanta and Secondary Emission Generated by 70 GeV Protons (A.Kh. Akhmadiyeva, S.I. Zaichkina, et al.; RADIOBIOLOGIYA, No 3, May-Jun...ase, the enzyme assuring an active transfer of univalent cations through the membrane. Natural metabolites (I) and (II) exhibited the highest

Test of a single module of the J-PET scanner based on plastic scintillators

NASA Astrophysics Data System (ADS)

Moskal, P.; Niedźwiecki, Sz.; Bednarski, T.; Czerwiński, E.; Kapłon, Ł.; Kubicz, E.; Moskal, I.; Pawlik-Niedźwiecka, M.; Sharma, N. G.; Silarski, M.; Zieliński, M.; Zoń, N.; Białas, P.; Gajos, A.; Kochanowski, A.; Korcyl, G.; Kowal, J.; Kowalski, P.; Kozik, T.; Krzemień, W.; Molenda, M.; Pałka, M.; Raczyński, L.; Rudy, Z.; Salabura, P.; Słomski, A.; Smyrski, J.; Strzelecki, A.; Wieczorek, A.; Wiślicki, W.

2014-11-01

A Time of Flight Positron Emission Tomography scanner based on plastic scintillators is being developed at the Jagiellonian University by the J-PET collaboration. The main challenge of the conducted research lies in the elaboration of a method allowing application of plastic scintillators for the detection of low energy gamma quanta. In this paper we report on tests of a single detection module built out from the BC-420 plastic scintillator strip (with dimensions of 5×19×300 mm3) read out at two ends by Hamamatsu R5320 photomultipliers. The measurements were performed using collimated beam of annihilation quanta from the 68Ge isotope and applying the Serial Data Analyzer (Lecroy SDA6000A) which enabled sampling of signals with 50 ps intervals. The time resolution of the prototype module was established to be better than 80 ps (σ) for a single level discrimination. The spatial resolution of the determination of the hit position along the strip was determined to be about 0.93 cm (σ) for the annihilation quanta. The fractional energy resolution for the energy E deposited by the annihilation quanta via the Compton scattering amounts to σ(E) / E ≈ 0.044 /√{ E(MeV) } and corresponds to the σ(E) / E of 7.5% at the Compton edge.

The Free Electron Laser Sideband Instability Reconsidered.

DTIC Science & Technology

1987-08-12

sidebands. The stability is determined by the sign of df /dtl i.e., the relative population of oscillation quanta Wwb, bounce frequency around resonance. The...wigglers. (e) The growth is proportional to [df(J)/d(b(J)], the relative population in oscillation quanta around resonance, in agreement with the quantum...signal and the sideband. The total vector potential is given by A eie )A weik ) z( eiey )Arei(krZ- t) (exiey)A sei(ksz-& st) + CC (2) where the subscripts w

Does mean mean MEAN!? Digits For A Very Long Time Giving Us The Finger!: 1881 Statistics Log-Law was: Quanta=Digits!: BEC; Zipf 1/f-Law; Information-Thy; Random-#s = Euler V Bernoulli; Q-Computing = Arithmetic; P=/=NP SANS Complexity: Euclid 3-Mille

NASA Astrophysics Data System (ADS)

Siegel, Edward

2008-03-01

Classic statistics digits Newcomb[Am.J.Math.4,39,1881]-Weyl[Goett.Nachr.1912]-Benford[Proc.Am.Phil.Soc.78,4,51,1938]("NeWBe")probability ON-AVERAGE/MEAN log-law: =log[1+1/d]=log[(d+1)/d][google:``Benford's-Law'';"FUZZYICS": Siegel[AMS Nat.-Mtg.:2002&2008)]; Raimi[Sci.Am.221,109,1969]; Hill[Proc.AMS,123,3,887,1996]=log-base=units=SCALE-INVARIANCE!. Algebraic-inverse d=1/[ê(w)-1]: BOSONS(1924)=DIGITS(<1881): Energy-levels:ground=(d=0),first-(d=1)-excited ,... No fractions; only digit-integer-differences=quanta! Quo vadis digit =oo vs. <<,... simple-arithmetic!

The black hole quantum atmosphere

NASA Astrophysics Data System (ADS)

Dey, Ramit; Liberati, Stefano; Pranzetti, Daniele

2017-11-01

Ever since the discovery of black hole evaporation, the region of origin of the radiated quanta has been a topic of debate. Recently it was argued by Giddings that the Hawking quanta originate from a region well outside the black hole horizon by calculating the effective radius of a radiating body via the Stefan-Boltzmann law. In this paper we try to further explore this issue and end up corroborating this claim, using both a heuristic argument and a detailed study of the stress energy tensor. We show that the Hawking quanta originate from what might be called a quantum atmosphere around the black hole with energy density and fluxes of particles peaked at about 4 MG, running contrary to the popular belief that these originate from the ultra high energy excitations very close to the horizon. This long distance origin of Hawking radiation could have a profound impact on our understanding of the information and transplanckian problems.

Synchronous γ (Co60) photons and thermal processing induced insulator metal transition in amorphous chalcogenide As4Se3Te3 composition

NASA Astrophysics Data System (ADS)

El-Sayed, S. A.; Morsy, M. A.

2018-05-01

Amorphous chalcogenide composition AS4Se3Te3 is prepared by conventional quenching technique. The separate annealing or γ quanta irradiation not effect on the dc conductivity properties of the prepared composition. When the prepared samples are subjected to simultaneous annealing at temperature 413 K and γ quanta irradiation the dc conductivity increases. The dark dc conductivity increases by increasing the time of exposure to γ irradiation. At irradiation dose 1.47 × 104 Gy the dc conductivity starts to have metallic like conductivity character. These samples could be used as high temperature γ quanta dosimeter. By applying scaling theory on the samples irradiated with different dose of γ irradiation the critical exponents are determined and found to be < 2. The dark dc conductivity continuously decreases to 0 as temperature tends to zero. The steric value is low in the insulator side of conductivity, but high and almost saturated in the metallic side of conductivity.

Lateral distribution on charged particles in EAS

NASA Technical Reports Server (NTRS)

Dedenko, L. G.; Kulikov, G. V.; Solovjeva, V. I.; Sulakov, V. F.

1985-01-01

Lateral distribution of charged particles which allow for the finiteness of energy gamma-quanta, the inhomogeneity of the atmosphere and the experimental selection of EAS are needed to interpret experimental data. The effects of finiteness of energy of gamma-quanta which produce the partial electron-photon cascades were considered by substituting K R sub m instead of R sub m in NKG approximation where K was found to be 0.56 from comparison with the experimental data. New results on the lateral distribution of electrons in the partial cascades from gamma-quanta were obtained. It is shown that the coefficient K can be regarded as a constant. The last approximation of K was found to be most adequate when compared with the experimental data. The inhomogeneity of the atmosphere, muons and experimental selection are considered. The calculation of Ne are extended from 100,000 to 10 million for sea level and for Akeno level.

Pulse-shape discrimination with Cs2HfCl6 crystal scintillator

NASA Astrophysics Data System (ADS)

Cardenas, C.; Burger, A.; Goodwin, B.; Groza, M.; Laubenstein, M.; Nagorny, S.; Rowe, E.

2017-10-01

The results of investigation into cesium hafnium chloride (Cs2HfCl6) scintillating crystals as a promising detector to search for rare nuclear processes occurring in Hf isotopes is reported. The light output, quenching factor, and pulse-shape characteristics have been investigated at room temperature. The scintillation response of the crystal induced by α-particles and γ-quanta were studied to determine possibility of particle discrimination. Using the optimal filter method we obtained clear separation between signals with a factor of merit (FOM) = 9.3. This indicates that we are able to fully separate signals originating from α-particles and γ-quanta. Similar fruitful discrimination power was obtained by applying the mean time method (FOM = 7) and charge integration method (FOM = 7.5). The quenching factor for collimated 4 MeV α-particles is found to be 0.36, showing that α-particles generate more than a third of the light compared to γ-quanta at the same energy.

Method of virtual quanta and gravitational radiation

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

Matzner, R.A.; Nutku, Y.

1974-02-01

The radio signals received from pulsars are pulses which are frequently broadened as a result of scattering in the interstellar medium. This broadening is examined theoretically using a diffraction theory of wave propagation in weakly irregular media. The theory is valid for all distances in the scattering medium, and particular attention is paid to the transition from the regime where single scattering predominates to that where all the radiation has been multiply- scattered. Typical pulse shapes are calculated and the results are compared with the theory of pulse broadening based on geometrical optics which represents the limiting case for extrememore » multiple scatter. (auth)« less

Dressed Hard States and Black Hole Soft Hair.

PubMed

Mirbabayi, Mehrdad; Porrati, Massimo

2016-11-18

A recent, intriguing Letter by Hawking, Perry, and Strominger suggests that soft photons and gravitons can be regarded as black hole hair and may be relevant to the black hole information paradox. In this Letter we make use of factorization theorems for infrared divergences of the S matrix to argue that by appropriately dressing in and out hard states, the soft-quanta-dependent part of the S matrix becomes essentially trivial. The information paradox can be fully formulated in terms of dressed hard states, which do not depend on soft quanta.

The simple perfection of quantum correlation in human vision.

PubMed

Bouman, Maarten A

2006-01-01

A theory is presented that specifies the amount of light that is needed for the perception of any stimulus that is defined in space, time and color. For detection and discrimination mechanistic neural elements with deterministic procedures exist. Twin pairs of red and green cones are ordered in three sets along clockwise and counter clockwise revolving spirals and along circles around the center of the fovea. In the rod-free fovea the red pairs are ordered along the spirals and the green along the circles. Each cone is accompanied by--dependent on retinal eccentricity--up to 100 satellite rods. For the retinal signal processing such a receptor group constitutes a space-quantum in analogy with time-quanta of about 0.04 s. In the peripheral retina the red and green twin pairs of space-quanta are roughly ordered along and at random distributed over the spirals and circles. Over each time-quantum, the cone and rods of a space-quantum sum their responses in a common nerve circuit of the luminosity channel. The summation's results from twin pairs of the same set of space-quanta are correlated by two-fold spatio-temporal coincidence mechanisms in the retina. Their outcome signals the perception of light, movement and edge. In the fused binocular visual field the movement and edge signals of the three sets from both eyes perfectly join vectorially together, provided the responding pairs of space-quanta are binocularly in perfect register as they normally are. The receptor's Weber gain control makes the receptor an all-or-none-system. The space-quantum's De Vries gain control makes its sensitivity equal to the average of the poisson fluctuations in quantum absorption per time-quantum. The controls are based on, respectively, arithmetically feed forward and backward inhibitive nerve mechanisms. The thermal noise of the photo-pigment resets the controls. The response to the second quantum absorption in a time-quantum in the individual rod, red or green cone has accession to

GASEOUS SCINTILLATION COUNTER

DOEpatents

Eggler, C.; Huddleston, C.M.

1959-04-28

A gaseous excitation counter for detecting the presence amd measuring the energy of subatomic particles and electromagnetic radiation is described. The counter includes a gas-tight chamber filled with an elemental gas capable of producing ultra-violet excitation quanta when irradiated with subatomic particles and electromagnetic radiation. The gas has less than one in a thousand parts ultra-violet absorbing contamination. When nuclear radiation ps present the ultra-violet light produced by the gas strikes a fluorescent material within the counter, responsive to produce visible excitation quanta, and photo-sensitive counting means detect the visible emission.

Experimental search for the radiative capture reaction d + d {yields} {sup 4}He + {gamma} from the dd{mu} muonic molecule state J = 1

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

Baluev, V. V.; Bogdanova, L. N.; Bom, V. R.

2011-07-15

A search for the muon-catalyzed fusion reaction d + d {yields} {sup 4}He + {gamma} in the dd{mu} muonic molecule was performed using the experimental installation TRITON with BGO detectors for {gamma}-quanta. A high-pressure target filled with deuterium was exposed to the negative muon beam of the JINR Phasotron to detect {gamma}-quanta with the energy 23.8 MeV. An experimental estimation for the yield of radiative deuteron capture from the dd{mu} state J = 1 was obtained at the level of {eta}{sub {gamma}} {<=} 8 Multiplication-Sign 10{sup -7} per fusion.

Constructive and Destructive Interference in Nonadiabatic Tunneling via Conical Intersections

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

Xie, Changjian; Kendrick, Brian K.; Yarkony, David R.

As a manifestation of the molecular Aharonov–Bohm effect, tunneling-facilitated dissociation under a conical intersection (CI) requires the inclusion of the geometric phase (GP) to ensure a single-valued adiabatic wave function encircling the CI. Here, we demonstrate using a simple two-dimensional model that the GP induces destructive interference for vibrational states with even quanta in the coupling mode, but it leads to constructive interference for those with odd quanta. The interference patterns are manifested in tunneling wave functions and clearly affect the tunneling lifetime. Furthermore, we show that the inclusion of the diagonal Born–Oppenheimer correction is necessary for agreement with exactmore » results.« less

Constructive and Destructive Interference in Nonadiabatic Tunneling via Conical Intersections

DOE PAGES

Xie, Changjian; Kendrick, Brian K.; Yarkony, David R.; ...

2017-03-31

As a manifestation of the molecular Aharonov–Bohm effect, tunneling-facilitated dissociation under a conical intersection (CI) requires the inclusion of the geometric phase (GP) to ensure a single-valued adiabatic wave function encircling the CI. Here, we demonstrate using a simple two-dimensional model that the GP induces destructive interference for vibrational states with even quanta in the coupling mode, but it leads to constructive interference for those with odd quanta. The interference patterns are manifested in tunneling wave functions and clearly affect the tunneling lifetime. Furthermore, we show that the inclusion of the diagonal Born–Oppenheimer correction is necessary for agreement with exactmore » results.« less

76 FR 48130 - Southern Illinois University, et al.; Notice of Decision on Applications for Duty-Free Entry of...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-08-08

... Number: 11-032. Applicant: Southern Illinois University, Integrated Microscopy and Graphic Expertise (IMAGE) Center, 750 Communications Drive--Mailcode 4402, Carbondale, IL 62901. Instrument: Quanta 450...

The influence of DNA inhibitor synthesis on the induction and repair of double-strand DNA breaks in human lymphocytes under action of radiation with a different linear energy transfer

NASA Astrophysics Data System (ADS)

Boreyko, A. V.; Chausov, V. N.; Krasavin, E. A.; Ravnachka, I.; Stukova, S. I.

2011-07-01

The influence that inhibitors of repair and replicative DNA synthesis, 1-β-D-arabinofuranosyl-cytosine and hydroxyurea, have on the formation and repair kinetics of double-strand breaks (DSBs) in peripheral human blood lymphocytes under the influence of radiation with a different linear energy transfer (LET) (gamma quanta and accelerated heavy ions) is studied. It is demonstrated that lithium and boron ions with LETs of 20 and 40 keV/μm, respectively, possess higher biological effectiveness with respect to the DNA DSB induction criterion. The value of the relative biological effectiveness of accelerated lithium and boron ions is 1.5 ± 0.1 and 1.6 ± 0.1, respectively. It is found that, upon cell irradiation by gamma quanta in the absence of inhibitors, efficient DNA DSB repair is observed during incubation. Under the conditions of cell incubation and in the presence of inhibitors, some growth in the number of DNA DSBs, rather than a reduction, is observed after 5-h incubation. In the case of the action of accelerated boron ions (as well as gamma quanta), under normal conditions, the efficient repair of induced DNA lesions takes place. Unlike the action of gamma quanta, in the case of cell incubation in the presence of radiomodifiers, the number of induced DNA DSBs falls. These results may testify to the fact that the repair of double-strand DNS breaks takes place under the action of ionizing radiation with a different LET on mammalian cells in the presence of DNA synthesis inhibitors Ara-C and HU. It is concluded that, for cells subject to gamma irradiation, no DNA DSB repair is observed due to the large contribution of single-strand incision DNA breaks formed in the postradiation period in the course of excision nucleotide repair.

CDOM Sources and Photobleaching Control Quantum Yields for Oceanic DMS Photolysis.

PubMed

Galí, Martí; Kieber, David J; Romera-Castillo, Cristina; Kinsey, Joanna D; Devred, Emmanuel; Pérez, Gonzalo L; Westby, George R; Marrasé, Cèlia; Babin, Marcel; Levasseur, Maurice; Duarte, Carlos M; Agustí, Susana; Simó, Rafel

2016-12-20

Photolysis is a major removal pathway for the biogenic gas dimethylsulfide (DMS) in the surface ocean. Here we tested the hypothesis that apparent quantum yields (AQY) for DMS photolysis varied according to the quantity and quality of its photosensitizers, chiefly chromophoric dissolved organic matter (CDOM) and nitrate. AQY compiled from the literature and unpublished studies ranged across 3 orders of magnitude at the 330 nm reference wavelength. The smallest AQY(330) were observed in coastal waters receiving major riverine inputs of terrestrial CDOM (0.06-0.5 m 3 (mol quanta) -1 ). In open-ocean waters, AQY(330) generally ranged between 1 and 10 m 3 (mol quanta) -1 . The largest AQY(330), up to 34 m 3 (mol quanta) -1 ), were seen in the Southern Ocean potentially associated with upwelling. Despite the large AQY variability, daily photolysis rate constants at the sea surface spanned a smaller range (0.04-3.7 d -1 ), mainly because of the inverse relationship between CDOM absorption and AQY. Comparison of AQY(330) with CDOM spectral signatures suggests there is an interplay between CDOM origin (terrestrial versus marine) and photobleaching that controls variations in AQYs, with a secondary role for nitrate. Our results can be used for regional or large-scale assessment of DMS photolysis rates in future studies.

Particle production in a gravitational wave background

NASA Astrophysics Data System (ADS)

Jones, Preston; McDougall, Patrick; Singleton, Douglas

2017-03-01

We study the possibility that massless particles, such as photons, are produced by a gravitational wave. That such a process should occur is implied by tree-level Feynman diagrams such as two gravitons turning into two photons, i.e., g +g →γ +γ . Here we calculate the rate at which a gravitational wave creates a massless scalar field. This is done by placing the scalar field in the background of a plane gravitational wave and calculating the 4-current of the scalar field. Even in the vacuum limit of the scalar field it has a nonzero vacuum expectation value (similar to what occurs in the Higgs mechanism) and a nonzero current. We associate this with the production of scalar field quanta by the gravitational field. This effect has potential consequences for the attenuation of gravitational waves since the massless field is being produced at the expense of the gravitational field. This is related to the time-dependent Schwinger effect, but with the electric field replaced by the gravitational wave background and the electron/positron field quanta replaced by massless scalar "photons." Since the produced scalar quanta are massless there is no exponential suppression, as occurs in the Schwinger effect due to the electron mass.

On Einstein, Light Quanta, Radiation, and Relativity in 1905

ERIC Educational Resources Information Center

Miller, Arthur I.

1976-01-01

Analyzes section 8 of Einstein's relativity paper of 1905, "On the Electrodynamics of Moving Bodies," in its historical context. Relates this section to the rest of the relativity paper, to the genesis of relativity theory, and to contemporaneous work on radiation theory. (Author/MLH)

Role of albedo from the Gamma-400 telescope calorimeter when recording the primary gamma emission.

NASA Astrophysics Data System (ADS)

Ginsburg, V. L.; Kurnosova, L. V.; Labensky, A. G.; Topchiev, N. P.; Fradkin, M. I.; Kaplin, V. A.; Kaplin, D. V.; Loginov, V. A.; Maklyaev, E. F.; Runtso, M. F.; Gorchakov, E. V.

A calorimeter albedo emission affecting the Gamma-400 telescope operation is studied, when recording γ-quanta at energies from 10 to 1000 GeV. Methods for diminishing this impact on measuring data are proposed.

Operating Spin Echo in the Quantum Regime for an Atomic-Ensemble Quantum Memory

NASA Astrophysics Data System (ADS)

Rui, Jun; Jiang, Yan; Yang, Sheng-Jun; Zhao, Bo; Bao, Xiao-Hui; Pan, Jian-Wei

2015-09-01

Spin echo is a powerful technique to extend atomic or nuclear coherence times by overcoming the dephasing due to inhomogeneous broadenings. However, there are disputes about the feasibility of applying this technique to an ensemble-based quantum memory at the single-quanta level. In this experimental study, we find that noise due to imperfections of the rephasing pulses has both intense superradiant and weak isotropic parts. By properly arranging the beam directions and optimizing the pulse fidelities, we successfully manage to operate the spin echo technique in the quantum regime by observing nonclassical photon-photon correlations as well as the quantum behavior of retrieved photons. Our work for the first time demonstrates the feasibility of harnessing the spin echo method to extend the lifetime of ensemble-based quantum memories at the single-quanta level.

Remnants, fuzzballs or wormholes?

NASA Astrophysics Data System (ADS)

Mathur, Samir D.

2014-11-01

The black hole information paradox has caused enormous confusion over four decades. But in recent years, the theorem of quantum strong-subadditivity has sorted out the possible resolutions into three sharp categories: (i) No new physics at r ≫ lp; this necessarily implies remnants/information loss. A realization of remnants is given by a baby universe attached near r 0. (ii) Violation of the "no-hair" theorem by nontrivial effects at the horizon r M. This possibility is realized by fuzzballs in string theory, and gives unitary evaporation. (iii) Having the vacuum at the horizon, but requiring that Hawking quanta at r M3 be somehow identified with degrees of freedom inside the black hole. A model for this "extreme nonlocality" is realized by conjecturing that wormholes connect the radiation quanta to the hole.

Photon polarization version of the GHz-Mermin Gedanken

NASA Technical Reports Server (NTRS)

Kiess, Thomas E.

1992-01-01

We have defined a photon polarization analog of the Greenberger, Horne, and Zeilinger (GHZ) experiment that was initially proposed for spin-1/2 quanta. Analogs of the ket states and Pauli spin matrix operators are presented.

FastLane: An Agile Congestion Signaling Mechanism for Improving Datacenter Performance

DTIC Science & Technology

2013-05-20

Cloudera, Ericsson, Facebook, General Electric, Hortonworks, Huawei , Intel, Microsoft, NetApp, Oracle, Quanta, Samsung, Splunk, VMware and Yahoo...Web Services, Google, SAP, Blue Goji, Cisco, Clearstory Data, Cloud- era, Ericsson, Facebook, General Electric, Hortonworks, Huawei , Intel, Microsoft

Switchable geometric frustration in an artificial-spin-ice-superconductor heterosystem.

PubMed

Wang, Yong-Lei; Ma, Xiaoyu; Xu, Jing; Xiao, Zhi-Li; Snezhko, Alexey; Divan, Ralu; Ocola, Leonidas E; Pearson, John E; Janko, Boldizsar; Kwok, Wai-Kwong

2018-06-11

Geometric frustration emerges when local interaction energies in an ordered lattice structure cannot be simultaneously minimized, resulting in a large number of degenerate states. The numerous degenerate configurations may lead to practical applications in microelectronics 1 , such as data storage, memory and logic 2 . However, it is difficult to achieve very high degeneracy, especially in a two-dimensional system 3,4 . Here, we showcase in situ controllable geometric frustration with high degeneracy in a two-dimensional flux-quantum system. We create this in a superconducting thin film placed underneath a reconfigurable artificial-spin-ice structure 5 . The tunable magnetic charges in the artificial-spin-ice strongly interact with the flux quanta in the superconductor, enabling switching between frustrated and crystallized flux quanta states. The different states have measurable effects on the superconducting critical current profile, which can be reconfigured by precise selection of the spin-ice magnetic state through the application of an external magnetic field. We demonstrate the applicability of these effects by realizing a reprogrammable flux quanta diode. The tailoring of the energy landscape of interacting 'particles' using artificial-spin-ices provides a new paradigm for the design of geometric frustration, which could illuminate a path to control new functionalities in other material systems, such as magnetic skyrmions 6 , electrons and holes in two-dimensional materials 7,8 , and topological insulators 9 , as well as colloids in soft materials 10-13 .

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

Hawking's acting roles

NASA Astrophysics Data System (ADS)

Castell, Stephen

2012-06-01

In the wake of Stephen Hawking's appearance on the TV show The Big Bang Theory, last month's "Quanta" page (May p3), included a request: "If you think Hawking should appear in any other TV shows, then let us know".

Infrared Lasers in Chemistry.

ERIC Educational Resources Information Center

John, Phillip

1982-01-01

Selected infrared laser chemistry topics are discussed including carbon dioxide lasers, infrared quanta and molecules, laser-induced chemistry, structural isomerization (laser purification, sensitized reactions, and dielectric breakdown), and fundamental principles of laser isotope separation, focusing on uranium isotope separation. (JN)

Energy sources, self-organization, and the origin of life.

PubMed

Boiteau, Laurent; Pascal, Robert

2011-02-01

The emergence and early developments of life are considered from the point of view that contingent events that inevitably marked evolution were accompanied by deterministic driving forces governing the selection between different alternatives. Accordingly, potential energy sources are considered for their propensity to induce self-organization within the scope of the chemical approach to the origin of life. Requirements in terms of quality of energy locate thermal or photochemical activation in the atmosphere as highly likely processes for the formation of activated low-molecular weight organic compounds prone to induce biomolecular self-organization through their ability to deliver quanta of energy matching the needs of early biochemical pathways or the reproduction of self-replicating entities. These lines of reasoning suggest the existence of a direct connection between the free energy content of intermediates of early pathways and the quanta of energy delivered by available sources of energy.

Marrying Excitons and Plasmons in Monolayer Transition-Metal Dichalcogenides

NASA Astrophysics Data System (ADS)

Van Tuan, Dinh; Scharf, Benedikt; Žutić, Igor; Dery, Hanan

2017-10-01

Just as photons are the quanta of light, plasmons are the quanta of orchestrated charge-density oscillations in conducting media. Plasmon phenomena in normal metals, superconductors, and doped semiconductors are often driven by long-wavelength Coulomb interactions. However, in crystals whose Fermi surface is comprised of disconnected pockets in the Brillouin zone, collective electron excitations can also attain a shortwave component when electrons transition between these pockets. In this work, we show that the band structure of monolayer transition-metal dichalcogenides gives rise to an intriguing mechanism through which shortwave plasmons are paired up with excitons. The coupling elucidates the origin for the optical sideband that is observed repeatedly in monolayers of WSe2 and WS2 but not understood. The theory makes it clear why exciton-plasmon coupling has the right conditions to manifest itself distinctly only in the optical spectra of electron-doped tungsten-based monolayers.

Energy Sources, Self-organization, and the Origin of Life

NASA Astrophysics Data System (ADS)

Boiteau, Laurent; Pascal, Robert

2011-02-01

The emergence and early developments of life are considered from the point of view that contingent events that inevitably marked evolution were accompanied by deterministic driving forces governing the selection between different alternatives. Accordingly, potential energy sources are considered for their propensity to induce self-organization within the scope of the chemical approach to the origin of life. Requirements in terms of quality of energy locate thermal or photochemical activation in the atmosphere as highly likely processes for the formation of activated low-molecular weight organic compounds prone to induce biomolecular self-organization through their ability to deliver quanta of energy matching the needs of early biochemical pathways or the reproduction of self-replicating entities. These lines of reasoning suggest the existence of a direct connection between the free energy content of intermediates of early pathways and the quanta of energy delivered by available sources of energy.

The New Physics

NASA Astrophysics Data System (ADS)

Fraser, Gordon

2006-04-01

Introduction Gordon Fraser; Part I. Matter and the Universe: 1. Cosmology Wendy Freedman and Rocky Kolb; 2. Gravity Ronald Adler; 3. Astrophysics Arnon Dar; 4. Particles and the standard model Chris Quigg; 5. Superstrings Michael Green; Part II. Quantum Matter: 6. Atoms and photons Claude Cohen-Tannoudji and Jean Dalibard; 7. The quantum world of ultra-cold atoms Christopher Foot and William Phillips; 8. Superfluidity Henry Hall; 9. Quantum phase transitions Subir Sachdev; Part III. Quanta in Action: 10. Quantum entanglement Anton Zeilinger; 11. Quanta, ciphers and computers Artur Ekert; 12. Small-scale structure and nanoscience Yoseph Imry; Part IV. Calculation and Computation: 13. Nonlinearity Henry Abarbanel; 14. Complexity Antonio Politi; 15. Collaborative physics, e-science and the grid Tony Hey and Anne Trefethen; Part V. Science in Action: 16. Biophysics Cyrus Safinya; 17. Medical physics Nicolaj Pavel; 18. Physics and materials Robert Cahn; 19. Physics and society Ugo Amaldi.

The New Physics

NASA Astrophysics Data System (ADS)

Fraser, Gordon

2009-08-01

Introduction Gordon Fraser; Part I. Matter and the Universe: 1. Cosmology Wendy Freedman and Rocky Kolb; 2. Gravity Ronald Adler; 3. Astrophysics Arnon Dar; 4. Particles and the standard model Chris Quigg; 5. Superstrings Michael Green; Part II. Quantum Matter: 6. Atoms and photons Claude Cohen-Tannoudji and Jean Dalibard; 7. The quantum world of ultra-cold atoms Christopher Foot and William Phillips; 8. Superfluidity Henry Hall; 9. Quantum phase transitions Subir Sachdev; Part III. Quanta in Action: 10. Quantum entanglement Anton Zeilinger; 11. Quanta, ciphers and computers Artur Ekert; 12. Small-scale structure and nanoscience Yoseph Imry; Part IV. Calculation and Computation: 13. Nonlinearity Henry Abarbanel; 14. Complexity Antonio Politi; 15. Collaborative physics, e-science and the grid Tony Hey and Anne Trefethen; Part V. Science in Action: 16. Biophysics Cyrus Safinya; 17. Medical physics Nicolaj Pavel; 18. Physics and materials Robert Cahn; 19. Physics and society Ugo Amaldi.

[Photoeffects, Einstein's light quanta and the history of their acceptance].

PubMed

Wiederkehr, Karl Heinrich

2006-01-01

It is generally supposed, that the discovery of the efficacy-quantum by Planck was the impetus to Einstein's hypothesis of lightquanta. With its help Einstein could explain the external light-electrical effect. But even years before Einstein had worked at the photoeffect and already made experiments on it. For that reason the article gives a short survey about the history of the lightelectric effects. Lenard's basical work about the release of the photoelectrons is dealt with in detail, without which Einstein would scarcely have found his lightquanta. Furthermore it is shown how difficult it was for the physicists to give up--at least partially--the traditional view of the undulation-nature of light, and how they searched to explain the great energies of the photoelectrons. On the other side it is set forth how Einstein's formula of lightquanta was gradually confirmed. The tragical development of Einstein's personal relations with Johannes Stark and Philipp Lenard are briefly described. Stark was one of the few who supported Einstein's ideas at the beginning. Only with the Compton-effect, which could only be quantitatively interpreted by means of lightquanta and the special theory of relativity 1923, the way was free for the general acceptance of the lightquanta. Einstein did not agree to the obtained dualism of undulation and corpuscle; he had a different solution in mind about the fusion of the two forms of appearance of light.

Bose-Einstein condensation of spin wave quanta at room temperature.

PubMed

Dzyapko, O; Demidov, V E; Melkov, G A; Demokritov, S O

2011-09-28

Spin waves are delocalized excitations of magnetic media that mainly determine their magnetic dynamics and thermodynamics at temperatures far below the critical one. The quantum-mechanical counterparts of spin waves are magnons, which can be considered as a gas of weakly interacting bosonic quasi-particles. Here, we discuss the room-temperature kinetics and thermodynamics of the magnon gas in yttrium iron garnet films driven by parametric microwave pumping. We show that for high enough pumping powers, the thermalization of the driven gas results in a quasi-equilibrium state described by Bose-Einstein statistics with a non-zero chemical potential. Further increases of the pumping power cause a Bose-Einstein condensation documented by an observation of the magnon accumulation at the lowest energy level. Using the sensitivity of the Brillouin light scattering spectroscopy to the degree of coherence of the scattering magnons, we confirm the spontaneous emergence of coherence of the magnons accumulated at the bottom of the spectrum, occurring if their density exceeds a critical value.

Experimental study of the vidicon system for information recording using the wide-gap spark chamber of gamma - telescope gamma-I

NASA Technical Reports Server (NTRS)

Akimov, V. V.; Bazer-Bashv, R.; Voronov, S. A.; Galper, A. M.; Gro, M.; Kalinkin, L. F.; Kerl, P.; Kozlov, V. D.; Koten, F.; Kretol, D.

1979-01-01

The development of the gamma ray telescope is investigated. The wide gap spark chambers, used to identify the gamma quanta and to determine the directions of their arrival, are examined. Two systems of information recording with the spark chambers photographic and vidicon system are compared.

Missing energies at pair creation

NASA Technical Reports Server (NTRS)

El-Ela, A. A.; Hassan, S.; Bagge, E. R.

1985-01-01

Wilson cloud chamber measurements of the separated spectra of positrons and electrons produced by gamma quanta of 6.14 MeV differ considerably from the theoretically predicted spectra by BETHE and HEITLER, but are in good agreement with those of a modified theory of pair creation.

Magnetic moment of single layer graphene rings

NASA Astrophysics Data System (ADS)

Margulis, V. A.; Karpunin, V. V.; Mironova, K. I.

2018-01-01

Magnetic moment of single layer graphene rings is investigated. An analytical expression for the magnetic moment as a function of the magnetic field flux through the one-dimensional quantum rings is obtained. This expression has the oscillation character. The oscillation period is equal to one flux quanta.

Advanced Materials for Quantum Computing

DTIC Science & Technology

2010-04-28

with Magnons co-PI: Leszek Malkinski w/ Postdoc Dr. Seong-Gi Min Project Name: Quantum Computing with Magnons 1. Brief Narrative: Quanta of...spinwaves called magnons can be used to exchange quantum information between solid state qubits. The project was driven by the concept of spiwave bus

Multi-Resource Fair Queueing for Packet Processing

DTIC Science & Technology

2012-06-19

Huawei , Intel, MarkLogic, Microsoft, NetApp, Oracle, Quanta, Splunk, VMware and by DARPA (contract #FA8650-11-C-7136). Multi-Resource Fair Queueing for...Google PhD Fellowship, gifts from Amazon Web Services, Google, SAP, Blue Goji, Cisco, Cloud- era, Ericsson, General Electric, Hewlett Packard, Huawei

Quantum graviton creation in a model universe

NASA Technical Reports Server (NTRS)

Berger, B. K.

1974-01-01

Consideration of the mechanism of production of gravitons in the empty, anisotropic, spatially inhomogeneous Gowdy three-torus cosmology. The Gowdy cosmology is an exact solution of the vacuum Einstein equations and is obtained as a generalization of the homogeneous empty Bianchi Type I (Kasner) cosmology by permitting the metric components to depend on one of the space variables in addition to time. The Hamiltonian methods of Arnowitt, Deser, and Misner are employed to identify the dynamical variables which are to be quantized. The WKB regime solution is identical to that found by Doroshkevich, Zel'dovich, and Novikov (DZN) for a universe containing collisionless anisotropic radiation. Using a procedure similar to that of Parker (1971) or Zel'dovich and Starobinskii (1971) for defining quantum number, it is found that the DZN large-time radiation consists of quanta (gravitons) created from an initial vacuum. The quantum behavior is much like the semiclassical enhancement of quantum number with the added feature of creation of quanta from vacuum fluctuations.

RADIOMETRIC EQUIPMENT ON SECOND SPACESHIP-SATELLITE

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

Papkov, S.F.; Pisarenko, N.F.; Savenko, I.A.

1961-01-01

Equipment installed on the second Soviet spaceshipsatellite to measure radiation and determine dose absorption is described. A scintillation counter recorded charged particles penetrating the skin of the spaceship and gamma quanta with energies exceeding 25 kev. Two CTC-5 gas-discharge counters also recorded charged particles, and, as the efficiency of gamma recording was low (below 10/sup -2/), a comparison of readings made it possible to evaluate the contribution of the charged particles and the gamma quanta, respectively, to the absorbed dose. A separate scintillation counter measured the energy flow of relatively soft charged particles. Electronic equipment was supplied with energy frommore » a 6( plus or minus 1)-v battery with power not over 0.5 w. A thorough check of the spaceship after its return to earth demonstrated that all the counters and electronie devices had retained their efficiency. A block diagram of the equipment is given. (OTS)« less

Quantum entanglement of angular momentum states with quantum numbers up to 10,010

PubMed Central

Fickler, Robert; Campbell, Geoff; Buchler, Ben; Lam, Ping Koy; Zeilinger, Anton

2016-01-01

Photons with a twisted phase front carry a quantized amount of orbital angular momentum (OAM) and have become important in various fields of optics, such as quantum and classical information science or optical tweezers. Because no upper limit on the OAM content per photon is known, they are also interesting systems to experimentally challenge quantum mechanical prediction for high quantum numbers. Here, we take advantage of a recently developed technique to imprint unprecedented high values of OAM, namely spiral phase mirrors, to generate photons with more than 10,000 quanta of OAM. Moreover, we demonstrate quantum entanglement between these large OAM quanta of one photon and the polarization of its partner photon. To our knowledge, this corresponds to entanglement with the largest quantum number that has been demonstrated in an experiment. The results may also open novel ways to couple single photons to massive objects, enhance angular resolution, and highlight OAM as a promising way to increase the information capacity of a single photon. PMID:27856742

Quantum entanglement of angular momentum states with quantum numbers up to 10,010

NASA Astrophysics Data System (ADS)

Fickler, Robert; Campbell, Geoff; Buchler, Ben; Lam, Ping Koy; Zeilinger, Anton

2016-11-01

Photons with a twisted phase front carry a quantized amount of orbital angular momentum (OAM) and have become important in various fields of optics, such as quantum and classical information science or optical tweezers. Because no upper limit on the OAM content per photon is known, they are also interesting systems to experimentally challenge quantum mechanical prediction for high quantum numbers. Here, we take advantage of a recently developed technique to imprint unprecedented high values of OAM, namely spiral phase mirrors, to generate photons with more than 10,000 quanta of OAM. Moreover, we demonstrate quantum entanglement between these large OAM quanta of one photon and the polarization of its partner photon. To our knowledge, this corresponds to entanglement with the largest quantum number that has been demonstrated in an experiment. The results may also open novel ways to couple single photons to massive objects, enhance angular resolution, and highlight OAM as a promising way to increase the information capacity of a single photon.

A Scalable Microfabricated Ion Trap for Quantum Information Processing

NASA Astrophysics Data System (ADS)

Maunz, Peter; Haltli, Raymond; Hollowell, Andrew; Lobser, Daniel; Mizrahi, Jonathan; Rembetski, John; Resnick, Paul; Sterk, Jonathan D.; Stick, Daniel L.; Blain, Matthew G.

2016-05-01

Trapped Ion Quantum Information Processing (QIP) relies on complex microfabricated trap structures to enable scaling of the number of quantum bits. Building on previous demonstrations of surface-electrode ion traps, we have designed and characterized the Sandia high-optical-access (HOA-2) microfabricated ion trap. This trap features high optical access, high trap frequencies, low heating rates, and negligible charging of dielectric trap components. We have observed trap lifetimes of more than 100h, measured trap heating rates for ytterbium of less than 40quanta/s, and demonstrated shuttling of ions from a slotted to an above surface region and through a Y-junction. Furthermore, we summarize demonstrations of high-fidelity single and two-qubit gates realized in this trap. Sandia is a multiprogram laboratory operated by Sandia Corporation, a Lockheed Martin Company, for the United States Department of Energy's National Nuclear Security Administration under Contract DE-AC04-94AL85000. This work was supported by the Intelligence Advanced Research Projects Activity (IARPA).

Quantum entanglement of angular momentum states with quantum numbers up to 10,010.

PubMed

Fickler, Robert; Campbell, Geoff; Buchler, Ben; Lam, Ping Koy; Zeilinger, Anton

2016-11-29

Photons with a twisted phase front carry a quantized amount of orbital angular momentum (OAM) and have become important in various fields of optics, such as quantum and classical information science or optical tweezers. Because no upper limit on the OAM content per photon is known, they are also interesting systems to experimentally challenge quantum mechanical prediction for high quantum numbers. Here, we take advantage of a recently developed technique to imprint unprecedented high values of OAM, namely spiral phase mirrors, to generate photons with more than 10,000 quanta of OAM. Moreover, we demonstrate quantum entanglement between these large OAM quanta of one photon and the polarization of its partner photon. To our knowledge, this corresponds to entanglement with the largest quantum number that has been demonstrated in an experiment. The results may also open novel ways to couple single photons to massive objects, enhance angular resolution, and highlight OAM as a promising way to increase the information capacity of a single photon.

Vibrational Mode-Specific Reaction of Methane with a Nickel Surface

NASA Astrophysics Data System (ADS)

Beck, Rainer

2004-03-01

The dissociation of methane on a nickel catalyst is a key step in steam reforming of natural gas for hydrogen production. Despite substantial effort in both experiment and theory, there is still no atomic scale description of this important gas-surface reaction. To elucidate its dynamics, we have performed quantum state resolved studies of vibrationally excited methane reacting on the Ni(100) surface using pulsed laser and molecular beam techniques. We observed up to a factor of 5 greater reaction probability for methane-d2 with two quanta of excitation in one C-H bond versus a nearly isoenergetic state with one quanta in each of two C-H bonds. The observed reactivities point to a transition state structure which has one of the C-H bonds significantly elongated. Our results also clearly exclude the possibility of statistical models correctly describing the mechanism of this process and emphasize the importance of full-dimensional calculations of the reaction dynamics.

Energy budget for the cultured, zooxanthellate octocoral Sinularia flexibilis.

PubMed

Khalesi, Mohammad K; Beeftink, H H; Wijffels, R H

2011-12-01

The zooxanthellate octocoral Sinularia flexibilis is a producer of potential pharmaceutically important metabolites such as antimicrobial and cytotoxic substances. Controlled rearing of the coral, as an alternative for commercial exploitation of these compounds, requires the study of species-specific growth requirements. In this study, phototrophic vs. heterotrophic daily energy demands of S. flexibilis was investigated through light and Artemia feeding trials in the laboratory. Rate of photosynthetic oxygen by zooxanthellae in light (≈200 μmol quanta m⁻² s⁻¹) was measured for the coral colonies with and without feeding on Artemia nauplii. Respiratory oxygen was measured in the dark, again with and without Artemia nauplii. Photosynthesis-irradiance curve at light intensities of 0, 50, 100, 200, and 400 μmol quanta m⁻² s⁻¹ showed an increase in photosynthetic oxygen production up to a light intensity between 100 and 200 μmol quanta m⁻² s⁻¹. The photosynthesis to respiration ratio (P/R > 1) confirmed phototrophy of S. flexibilis. Both fed and non-fed colonies in the light showed high carbon contribution by zooxanthellae to animal (host) respiration values of 111-127%. Carbon energy equivalents allocated to the coral growth averaged 6-12% of total photosynthesis energy (mg C g⁻¹ buoyant weight day⁻¹ and about 0.02% of the total daily radiant energy. "Light utilization efficiency (ε)" estimated an average ε value of 75% 12 h⁻¹ for coral practical energetics. This study shows that besides a fundamental role of phototrophy vs. heterotrophy in daily energy budget of S. flexibilis, an efficient fraction of irradiance is converted to useable energy.

The Mössbauer rotor experiment and the general theory of relativity

NASA Astrophysics Data System (ADS)

Corda, Christian

2016-05-01

In the recent paper Yarman et al. (2015), the authors claim that our general relativistic analysis in Corda (2015), with the additional effect due to clock synchronization, cannot explain the extra energy shift in the Mössbauer rotor experiment. In their opinion, the extra energy shift due to the clock synchronization is of order 10-13 and cannot be detected by the detectors of γ-quanta which are completely insensitive to such a very low order of energy shifts. In addition, they claim to have shown that the extra energy shift can be explained in the framework of the so-called YARK gravitational theory. They indeed claim that such a theory should replace the general theory of relativity (GTR) as the correct theory of gravity. In this paper we show that the authors Yarman et al. (2015) had a misunderstanding of our theoretical analysis in Corda (2015). In fact, in that paper we have shown that electromagnetic radiation launched by the central source of the apparatus is redshifted of a quantity 0 . 6 ¯ v2/c2 when arriving to the detector of γ-quanta. This holds independently by the issue that the original photons are detected by the resonant absorber which, in turns, triggers the γ-quanta which arrive to the final detector. In other words, the result in Corda (2015) was a purely theoretical result that is completely independent of the way the experiment is concretely realized. Now, we show that, with some clarification, the results of Corda (2015) hold also when one considers the various steps of the concrete detection. In that case, the resonant absorber detects the energy shift and the separated detector of γ-quanta merely measures the resulting intensity. In addition, we also show that the YARK gravitational theory is in macroscopic contrast with geodesic motion and, in turn, with the weak equivalence principle (WEP). This is in contrast with another claim of the authors of Yarman et al. (2015), i.e. that the YARK gravitational theory arises from the WEP

Sensitometric properties of Agfa Dentus OrthoLux, Agfa Dentus ST8G, and Kodak Ektavision panoramic radiographic film.

PubMed

Wakoh, M; Nishikawa, K; Kobayashi, N; Farman, A G; Kuroyanagi, K

2001-02-01

The purpose of this study was to compare the sensitometric properties of and visualization of anatomical structures with Agfa OrthoLux green-sensitive panoramic radiographic film, Agfa ST8G green sensitive panoramic radiographic film, and Kodak Ektavision green-sensitive panoramic radiographic film used in combination with an Agfa Ortho Regular 400 imaging screen, Kodak Ektavision imaging screen, and Kodak Lanex Regular imaging screen. The density response and resolution of panoramic radiographic film/intensifying screen combinations was evaluated by means of Hunter and Driffield curves, modulation transfer functions, and noise-equivalent number of quanta. Image clarity of selected anatomical structures was rated independently by 6 oral and maxillofacial radiologists. The ISO speed for the Agfa OrthoLux panoramic radiographic film combinations was the fastest, and the ISO speed for the Kodak Ektavision green-sensitive panoramic radiographic film combinations was the slowest. The average gradient for the Agfa ST8G systems was relatively steep in comparison with those for the other film/screen combinations. The modulation transfer functions for the Kodak Ektavision film were higher than those for the other films, irrespective of the screen combination used, and those for Agfa OrthoLux film were slightly higher than those for Agfa ST8G film. The noise-equivalent number of quanta for the Agfa ST8G film/screen combinations was lower than those for the other film/screen combinations. The noise-equivalent number of quanta for the Kodak Ektavision film/screen combinations was well within the high-frequency range, whereas Agfa OrthoLux combined with either the Kodak Ektavision imaging screen or the Kodak Lanex Regular imaging screen produced a noise-equivalent number of quanta similar to those of the Kodak Ektavision film/screen combinations in the low-frequency range. Agfa OrthoLux was perceived to provide clearer images of the selected anatomical details than Agfa ST8G

Harmonic oscillator states in aberration optics

NASA Technical Reports Server (NTRS)

Wolf, Kurt Bernardo

1993-01-01

The states of the three-dimensional quantum harmonic oscillator classify optical aberrations of axis-symmetric systems due to the isomorphism between the two mathematical structures. Cartesian quanta and angular momentum classifications have their corresponding aberration classifications. The operation of concatenation of optical elements introduces a new operation between harmonic oscillator states.

Teaching Einsteinian Physics at Schools: Part 1, Models and Analogies for Relativity

ERIC Educational Resources Information Center

Kaur, Tejinder; Blair, David; Moschilla, John; Stannard, Warren; Zadnik, Marjan

2017-01-01

The Einstein-First project aims to change the paradigm of school science teaching through the introduction of modern Einsteinian concepts of space and time, gravity and quanta at an early age. These concepts are rarely taught to school students despite their central importance to modern science and technology. The key to implementing the…

Elimination des constantes arbitraires dans la theorie relativiste des quanta [85

NASA Astrophysics Data System (ADS)

This article shows how the influence of the undetermined constants in the integral theory of collisions1)2)3)4) can be avoided. A rule is given by which the probability amplitudes (5[F]-matrix) may be calculated in terms of a given local action. The procedure of the integral method differs essentially from the differential method employed by Tomonaga6), Schwikger5), FÅÕímaí7) and Dyson8) in that the two sorts of diverging terms occuring in the formal solution of a Schroedinqer equation are avoided. These two divergencies are: 1) the well known «.self energy» divergencies which have been since corrected by methods of regularization (Rivikr1), Pattli and Villaks9)); 2) the more serious boundary divergencies (Stueckelberg4)) due to the sharp spatio-temporal limitation of the space-time region of evolution V in which the collisions occur. The convergent parts (anomalous g-factor of the electron and the Lamb-Rethekford shift) obtained by Schwinger are, in the present theory, the boundary independent amplitudes in fourth approximation. Üp to this approximation the rule eliminates the arbitrary constants from all conservative processes.

Selective bond breaking mediated by state specific vibrational excitation in model HOD molecule through optimized femtosecond IR pulse: a simulated annealing based approach.

PubMed

Shandilya, Bhavesh K; Sen, Shrabani; Sahoo, Tapas; Talukder, Srijeeta; Chaudhury, Pinaki; Adhikari, Satrajit

2013-07-21

The selective control of O-H/O-D bond dissociation in reduced dimensionality model of HOD molecule has been explored through IR+UV femtosecond pulses. The IR pulse has been optimized using simulated annealing stochastic approach to maximize population of a desired low quanta vibrational state. Since those vibrational wavefunctions of the ground electronic states are preferentially localized either along the O-H or O-D mode, the femtosecond UV pulse is used only to transfer vibrationally excited molecule to the repulsive upper surface to cleave specific bond, O-H or O-D. While transferring from the ground electronic state to the repulsive one, the optimization of the UV pulse is not necessarily required except specific case. The results so obtained are analyzed with respect to time integrated flux along with contours of time evolution of probability density on excited potential energy surface. After preferential excitation from [line]0, 0> ([line]m, n> stands for the state having m and n quanta of excitations in O-H and O-D mode, respectively) vibrational level of the ground electronic state to its specific low quanta vibrational state ([line]1, 0> or [line]0, 1> or [line]2, 0> or [line]0, 2>) by using optimized IR pulse, the dissociation of O-D or O-H bond through the excited potential energy surface by UV laser pulse appears quite high namely, 88% (O-H ; [line]1, 0>) or 58% (O-D ; [line]0, 1>) or 85% (O-H ; [line]2, 0>) or 59% (O-D ; [line]0, 2>). Such selectivity of the bond breaking by UV pulse (if required, optimized) together with optimized IR one is encouraging compared to the normal pulses.

[Influence of elevated atmospheric CO2 concentration on photosynthesis and leaf nitrogen partition in process of photosynthetic carbon cycle in Musa paradisiaca].

PubMed

Sun, G; Zhao, P; Zeng, X; Peng, S

2001-06-01

The photosynthetic rate (Pn) in leaves of Musa paradisiaca grown under elevated CO2 concentration (700 +/- 56 microliters.L-1) for one week was 5.14 +/- 0.32 mumol.m-2.s-1, 22.1% higher than that under ambient CO2 concentration, while under elevated CO2 concentration for 8 week, the Pn decreased by 18.1%. It can be inferred that the photosynthetic acclimation to elevated CO2 concentration and the Pn inhibition occurred in leaves of M. paradisiaca. The respiration rate in light (Rd) was lower in leaves under higher CO2 concentration, compared with that under ambient CO2 concentration. If the respiration in light was not included, the difference in CO2 compensation point for the leaves of both plants was not significant. Under higher CO2 concentration for 8 weeks, the maximum carboxylation rate(Vcmax) and electron transportation rate (J) in leaves decreased respectively by 30.5% and 14.8%, compared with that under ambient CO2 concentration. The calculated apparent quantum yield (alpha) in leaves under elevated CO2 concentration according to the initial slope of Pn/PAR was reduced to 0.014 +/- 0.010 molCO2.mol-1 quanta, compared with the value of 0.025 +/- 0.005 molCO2.mol-1 quanta in the control. The efficiency of light energy conversion also decreased from 0.203 to 0.136 electrons.quanta-1 in plants under elevated CO2 concentration. A lower partitioning coefficient for leaf nitrogen in Rubisco, bioenergetics and thylakoid light-harvesting components was observed in plants under higher CO2 concentration. The results indicated that the multi-process of photosynthesis was suppressed significantly by a long-term (8 weeks) higher CO2 concentration incubation.

Sequential testing with different tissue transglutaminase antibodies, a new approach for diagnosis of celiac disease.

PubMed

Venugopal, Giriprasad; Mechenro, John; Makharia, Govind; Singh, Alka; Pugazhendhi, Srinivasan; Balamurugan, Ramadass; Ramakrishna, Balakrishnan S

2017-11-01

The diagnosis of celiac disease (CeD) in clinical practice relies on serological testing for IgA antibodies to human tissue transglutaminase (anti-tTG) which diagnose CeD autoimmunity. We compared three kits for their performance in diagnosis of the disease and evaluated the point prevalence of CeD autoimmunity in a South Indian urban population. In the first part of the study, sera from 90 patients with documented CeD and 92 healthy controls were tested for anti-tTG using three different kits. One thousand nine hundred and seventeen healthy adults residing in urban areas of Vellore and Kancheepuram districts were tested for CeD autoimmunity using a sequential two-test strategy. The sensitivity, specificity, false positivity, false negativity, positive predictive value, and negative predictive value for the three assays respectively were as follows: 95.5%, 82.6%, 17.3%, 4.4%, 84.3%, and 95% for the Aeskulisa New Generation Assay; 85.5%, 100%, 0%, 14.4%, 100%, and 87.6% for Quanta Lite; and 71.1%, 100%, 0%, 28.8%, 100%, and 71% for Celiac Microlisa. The ROC curves showed good discrimination for all three ELISAs with an AUC of 0.947, 0.950, and 0.886 for the Aeskulisa, Quanta Lite, and Celiac Microlisa, respectively. Of 1917 (males 908, females 1009) healthy adults, 113 (5.89%) were seropositive for IgA anti-htTG in the Aeskulisa test. Two of the latter tested positive in the Quanta Lite assay and/or the Celiac Microlisa assay. The CeD autoimmunity prevalence in this urban population was 1.0 per thousand (95% confidence interval 0.3 to 3.7 per thousand). Sequential testing for anti-tTG using first a highly sensitive assay followed by a very specific assay is a new strategy for screening for CeD in clinical practice.

Teaching Quantum Physics without Paradoxes

ERIC Educational Resources Information Center

Hobson, Art

2007-01-01

Although the resolution to the wave-particle paradox has been known for 80 years, it is seldom presented. Briefly, the resolution is that material particles and photons are the quanta of extended spatially continuous but energetically quantized fields. But because the resolution resides in quantum field theory and is not usually spelled out in…

Hawking radiation from ultrashort laser pulse filaments.

PubMed

Belgiorno, F; Cacciatori, S L; Clerici, M; Gorini, V; Ortenzi, G; Rizzi, L; Rubino, E; Sala, V G; Faccio, D

2010-11-12

Event horizons of astrophysical black holes and gravitational analogues have been predicted to excite the quantum vacuum and give rise to the emission of quanta, known as Hawking radiation. We experimentally create such a gravitational analogue using ultrashort laser pulse filaments and our measurements demonstrate a spontaneous emission of photons that confirms theoretical predictions.

The MARS15-based FermiCORD code system for calculation of the accelerator-induced residual dose

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

Grebe, A.; Leveling, A.; Lu, T.

The FermiCORD code system, a set of codes based on MARS15 that calculates the accelerator-induced residual doses at experimental facilities of arbitrary configurations, has been developed. FermiCORD is written in C++ as an add-on to Fortran-based MARS15. The FermiCORD algorithm consists of two stages: 1) simulation of residual doses on contact with the surfaces surrounding the studied location and of radionuclide inventories in the structures surrounding those locations using MARS15, and 2) simulation of the emission of the nuclear decay gamma-quanta by the residuals in the activated structures and scoring the prompt doses of these gamma-quanta at arbitrary distances frommore » those structures. The FermiCORD code system has been benchmarked against similar algorithms based on other code systems and showed a good agreement. The code system has been applied for calculation of the residual dose of the target station for the Mu2e experiment and the results have been compared to approximate dosimetric approaches.« less

The MARS15-based FermiCORD code system for calculation of the accelerator-induced residual dose

NASA Astrophysics Data System (ADS)

Grebe, A.; Leveling, A.; Lu, T.; Mokhov, N.; Pronskikh, V.

2018-01-01

The FermiCORD code system, a set of codes based on MARS15 that calculates the accelerator-induced residual doses at experimental facilities of arbitrary configurations, has been developed. FermiCORD is written in C++ as an add-on to Fortran-based MARS15. The FermiCORD algorithm consists of two stages: 1) simulation of residual doses on contact with the surfaces surrounding the studied location and of radionuclide inventories in the structures surrounding those locations using MARS15, and 2) simulation of the emission of the nuclear decay γ-quanta by the residuals in the activated structures and scoring the prompt doses of these γ-quanta at arbitrary distances from those structures. The FermiCORD code system has been benchmarked against similar algorithms based on other code systems and against experimental data from the CERF facility at CERN, and FermiCORD showed reasonable agreement with these. The code system has been applied for calculation of the residual dose of the target station for the Mu2e experiment and the results have been compared to approximate dosimetric approaches.

Long Josephson tunnel junctions with doubly connected electrodes

NASA Astrophysics Data System (ADS)

Monaco, R.; Mygind, J.; Koshelets, V. P.

2012-03-01

In order to mimic the phase changes in the primordial Big Bang, several cosmological solid-state experiments have been conceived, during the last decade, to investigate the spontaneous symmetry breaking in superconductors and superfluids cooled through their transition temperature. In one of such experiments, the number of magnetic flux quanta spontaneously trapped in a superconducting loop was measured by means of a long Josephson tunnel junction built on top of the loop itself. We have analyzed this system and found a number of interesting features not occurring in the conventional case with simply connected electrodes. In particular, the fluxoid quantization results in a frustration of the Josephson phase, which, in turn, reduces the junction critical current. Further, the possible stable states of the system are obtained by a self-consistent application of the principle of minimum energy. The theoretical findings are supported by measurements on a number of samples having different geometrical configuration. The experiments demonstrate that a very large signal-to-noise ratio can be achieved in the flux quanta detection.

Cosmological evolution as squeezing: a toy model for group field cosmology

NASA Astrophysics Data System (ADS)

Adjei, Eugene; Gielen, Steffen; Wieland, Wolfgang

2018-05-01

We present a simple model of quantum cosmology based on the group field theory (GFT) approach to quantum gravity. The model is formulated on a subspace of the GFT Fock space for the quanta of geometry, with a fixed volume per quantum. In this Hilbert space, cosmological expansion corresponds to the generation of new quanta. Our main insight is that the evolution of a flat Friedmann–Lemaître–Robertson–Walker universe with a massless scalar field can be described on this Hilbert space as squeezing, familiar from quantum optics. As in GFT cosmology, we find that the three-volume satisfies an effective Friedmann equation similar to the one of loop quantum cosmology, connecting the classical contracting and expanding solutions by a quantum bounce. The only free parameter in the model is identified with Newton’s constant. We also comment on the possible topological interpretation of our squeezed states. This paper can serve as an introduction into the main ideas of GFT cosmology without requiring the full GFT formalism; our results can also motivate new developments in GFT and its cosmological application.

DOSIMETRIC MEASUREMENTS ON THE SECOND SOVIET SPACESHIP SATELLITE

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

Savenko, I.A.; Pisarenko, N.F.; Shavrin, P.I.

1963-02-01

Readings of counters placed inside Sputnik II are given for one portion of its trajectory. The readings were taken by a gas-discharge counter STS-5 and a NaI crystal scintillator counter that registered gamma quanta, charged particles with a 25-kev counting threshold, and the aggregate energy liberation of ionizing radiations in the crystal. (C.E.S.)

New design for a microwave discharge lamp.

PubMed

Glangetas, A

1980-03-01

A simple discharge lamp with a microwave cavity fitting inside provides an intense source of VUV resonance radiation for photochemical work inside a vacuum chamber. Good coupling and minimum reabsorption result in better efficiency ( greater, similar1%) and more intense output power (up to 2.5x10(16) quanta s(-1)) than have been achieved previously.

Electromagnetic dissociation effects in galactic heavy-ion fragmentation

NASA Technical Reports Server (NTRS)

Norbury, J. W.; Townsend, L. W.

1986-01-01

Methods for calculating cross sections for the breakup of galactic heavy ions by the Coulomb fields of the interacting nuclei are presented. By using the Weizsacker-Williams method of virtual quanta, estimates of electromagnetic dissociation cross sections for a variety of reactions applicable to galactic cosmic ray shielding studies are presented and compared with other predictions and with available experimental data.

Duration of classicality in highly degenerate interacting Bosonic systems

DOE PAGES

Sikivie, Pierre; Todarello, Elisa M.

2017-04-28

We study sets of oscillators that have high quantum occupancy and that interact by exchanging quanta. It is shown by analytical arguments and numerical simulation that such systems obey classical equations of motion only on time scales of order their relaxation time τ and not longer than that. The results are relevant to the cosmology of axions and axion-like particles.

Magnetic orientation in birds: non-compass responses under monochromatic light of increased intensity.

PubMed

Wiltschko, Wolfgang; Munro, Ursula; Ford, Hugh; Wiltschko, Roswitha

2003-10-22

Migratory Australian silvereyes (Zosterops lateralis) were tested under monochromatic light at wavelengths of 424 nm blue and 565 nm green. At a low light level of 7 x 10(15) quanta m(-2) s(-1) in the local geomagnetic field, the birds preferred their seasonally appropriate southern migratory direction under both wavelengths. Their reversal of headings when the vertical component of the magnetic field was inverted indicated normal use of the avian inclination compass. A higher light intensity of 43 x 10(15) quanta m(-2) s(-1), however, caused a fundamental change in behaviour: under bright blue, the silvereyes showed an axial tendency along the east-west axis; under bright green, they showed a unimodal preference of a west-northwesterly direction that followed a shift in magnetic north, but was not reversed by inverting the vertical component of the magnetic field. Hence it is not based on the inclination compass. The change in behaviour at higher light intensities suggests a complex interaction between at least two receptors. The polar nature of the response under bright green cannot be explained by the current models of light-dependent magnetoreception and will lead to new considerations on these receptive processes.

Learning Quanta: Barriers to Stimulating Transitions in Student Understanding of Orbital Ideas

ERIC Educational Resources Information Center

Taber, Keith S.

2005-01-01

This paper reports the results of applying a particular analytical perspective to data from an interview study: a typology of learning impediments informed by research into learning and students' ideas in science. This typology is a heuristic tool that may help diagnose the origins of students' learning difficulties. Here it is applied to data…

The band systems of alkali vapors

NASA Technical Reports Server (NTRS)

Weizel, W.; Kulp, M.

1988-01-01

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

Optimization and Comparison of Different Digital Mammographic Tomosynthesis Reconstruction Methods

DTIC Science & Technology

2007-04-01

physical measurements of impulse response analysis, modulation transfer function (MTF) and noise power spectrum (NPS). (Months 5- 12). 1.2.1. Simulate...added: projection images with simulated impulse and the 1/r2 shading difference. Other system blur and noise issues were not addressed in this paper...spectrum (NPS), Noise -equivalent quanta (NEQ), impulse response, Back Projection (BP) 1. INTRODUCTION Digital breast tomosynthesis is a new

Assessment of wavelength-dependent parameters of photosynthetic electron transport with a new type of multi-color PAM chlorophyll fluorometer.

PubMed

Schreiber, Ulrich; Klughammer, Christof; Kolbowski, Jörg

2012-09-01

Technical features of a novel multi-color pulse amplitude modulation (PAM) chlorophyll fluorometer as well as the applied methodology and some typical examples of its practical application with suspensions of Chlorella vulgaris and Synechocystis PCC 6803 are presented. The multi-color PAM provides six colors of pulse-modulated measuring light (peak-wavelengths at 400, 440, 480, 540, 590, and 625 nm) and six colors of actinic light (AL), peaking at 440, 480, 540, 590, 625 and 420-640 nm (white). The AL can be used for continuous illumination, maximal intensity single-turnover pulses, high intensity multiple-turnover pulses, and saturation pulses. In addition, far-red light (peaking at 725 nm) is provided for preferential excitation of PS I. Analysis of the fast fluorescence rise kinetics in saturating light allows determination of the wavelength- and sample-specific functional absorption cross section of PS II, Sigma(II)(λ), with which the PS II turnover rate at a given incident photosynthetically active radiation (PAR) can be calculated. Sigma(II)(λ) is defined for a quasi-dark reference state, thus differing from σ(PSII) used in limnology and oceanography. Vastly different light response curves for Chlorella are obtained with light of different colors, when the usual PAR-scale is used. Based on Sigma(II)(λ) the PAR, in units of μmol quanta/(m(2) s), can be converted into PAR(II) (in units of PS II effective quanta/s) and a fluorescence-based electron transport rate ETR(II) = PAR(II) · Y(II)/Y(II)(max) can be defined. ETR(II) in contrast to rel.ETR qualifies for quantifying the absolute rate of electron transport in optically thin suspensions of unicellular algae and cyanobacteria. Plots of ETR(II) versus PAR(II) for Chlorella are almost identical using either 440 or 625 nm light. Photoinhibition data are presented suggesting that a lower value of ETR(II)(max) with 440 nm possibly reflects photodamage via absorption by the Mn-cluster of the oxygen

Performance evaluation of a novel chemiluminescence assay for detection of anti-GBM antibodies: an international multicenter study.

PubMed

Mahler, Michael; Radice, Antonella; Sinico, Renato A; Damoiseaux, Jan; Seaman, Andrea; Buckmelter, Kristen; Vizjak, Alenka; Buchner, Carol; Binder, Walter L; Fritzler, Marvin J; Cui, Zhao

2012-01-01

Autoantibodies to the non-collagen region (NC1) of the alpha-3 subunit of collagen IV represent a serological hallmark in the diagnosis of Goodpasture's syndrome (GPS). The objective of our study was to carefully analyze the performance characteristics of a novel anti-glomerular basement membrane (GBM) chemiluminescence immunoassay (CIA). Sera from patients with GPS (n = 90) were collected from four clinical centers. Samples from different disease groups (n = 397) and healthy individuals (n = 400) were used as controls. All samples were tested for anti-GBM antibodies by a rapid, random access CIA (QUANTA Flash™ GBM). Most of the samples were also tested using other methods including different commercial anti-GBM IgG assays and research assays for anti-GBM IgA and IgM. The sensitivity and specificity of the novel CIA was 95.6% [95% confidence interval (CI) 89.0-98.8%] and 99.6% (95% CI 98.9-99.9%), respectively. Receiver operating characteristic analysis showed good discrimination between GPS patients and controls. The area under the curve was 0.98 (CI 0.96-1.0). The three anti-GBM antibody-positive samples from the control group were from two healthy individuals and one human immunodeficiency virus (HIV)-infected patient. All three individuals had low levels of anti-GBM antibodies [20, 24 and 25 chemiluminescent unit (CU), cutoff 20 CU]. When the results of the new CIA were compared to other methods, good agreement was observed: 95.8% (kappa = 0.92) versus EliA™ GBM, 97.4% (kappa = 0.95) versus both BINDAZYME™ Anti-GBM and QUANTA Lite® GBM. Anti-GBM IgA was detectable in low concentrations in patients with GPS and was associated with anti-GBM IgG but was less useful in discriminating GPS patients and controls. No discrimination was found for anti-GBM IgM. The novel QUANTA Flash™ GBM CIA demonstrated good sensitivity and specificity and had good agreement with other methods. Our data confirm that ∼5% of patients with GPS do not have detectable levels of

Morphological, Thermal, Electrical and Electromechanical Properties of Polyvinylidene Fluoride (PVDF)-Functionalized Carbon Nanotube Composites (Preprint)

DTIC Science & Technology

2012-03-01

several times with deionized water and ethanol to remove undissolved chemicals. Finally the solution was filtered through 0.2 µm cellulose nitrate...was recorded for 3 times and average was used. To observe the morphology of the synthesized samples, FESEM (Quanta 3D ) was performed. Powder was...linear within elastic region and start going to plastic region with further increment in load. For testing electromechanical properties of these f-CNT

Evaluation of Ho:KPb2Cl5 as a Diode-Pumpable Mid-IR Laser Material

DTIC Science & Technology

2016-09-01

is the decay of the upper laser level without emitting light , due to the simultaneous emission of enough lattice vibrational quanta (phonons) to...have an energy level spacing that can result in emission at the desired laser wavelength, and that state must emit light efficiently. It is also...extremely desirable that it absorb light in the wavelength region where laser diodes operate most efficiently, approximately 800–1000 nm. This enables

The origin of unequal bond lengths in the C 1B 2 state of SO 2: Signatures of high-lying potential energy surface crossings in the low-lying vibrational structure

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

Park, G. Barratt; Jiang, Jun; Field, Robert W.

Here the C 1B 2 state of SO 2 has a double-minimum potential in the antisymmetric stretch coordinate, such that the minimum energy geometry has nonequivalent SO bond lengths. The asymmetry in the potential energy surface is expressed as a staggering in the energy levels of the v' 3 progression. We have recently made the first observation of low-lying levels with odd quanta of v' 3, which allows us--in the current work--to characterize the origins of the level staggering. Our work demonstrates the usefulness of low-lying vibrational level structure, where the character of the wavefunctions can be relatively easily understood,more » to extract information about dynamically important potential energy surface crossings that occur at much higher energy. The measured staggering pattern is consistent with a vibronic coupling model for the double-minimum, which involves direct coupling to the bound 2 1A 1 state and indirect coupling with the repulsive 3 1A 1 state. The degree of staggering in the v' 3 levels increases with quanta of bending excitation, which is consistent with the approach along the C state potential energy surface to a conical intersection with the 2 1A 1 surface at a bond angle of ~145°.« less

The origin of unequal bond lengths in the C 1B 2 state of SO 2: Signatures of high-lying potential energy surface crossings in the low-lying vibrational structure

DOE PAGES

Park, G. Barratt; Jiang, Jun; Field, Robert W.

2016-04-14

Here the C 1B 2 state of SO 2 has a double-minimum potential in the antisymmetric stretch coordinate, such that the minimum energy geometry has nonequivalent SO bond lengths. The asymmetry in the potential energy surface is expressed as a staggering in the energy levels of the v' 3 progression. We have recently made the first observation of low-lying levels with odd quanta of v' 3, which allows us--in the current work--to characterize the origins of the level staggering. Our work demonstrates the usefulness of low-lying vibrational level structure, where the character of the wavefunctions can be relatively easily understood,more » to extract information about dynamically important potential energy surface crossings that occur at much higher energy. The measured staggering pattern is consistent with a vibronic coupling model for the double-minimum, which involves direct coupling to the bound 2 1A 1 state and indirect coupling with the repulsive 3 1A 1 state. The degree of staggering in the v' 3 levels increases with quanta of bending excitation, which is consistent with the approach along the C state potential energy surface to a conical intersection with the 2 1A 1 surface at a bond angle of ~145°.« less

Non-destructive NIR-FT-raman analyses in practice. Part II. Analyses of 'jumping' crystals, photosensitive crystals and gems.

PubMed

Andreev, G N; Schrader, B; Boese, R; Rademacher, P; von Cranach, L

2001-12-01

Using an improved sampling arrangement we observed the FT Raman spectra of the different phases of a 'jumping crystal', an inositol derivative. The phase transition produced--as consequences of large changes of the unit cell constants--changes in frequency and intensity mainly of CH deformation vibrations. Photochemical reactions, usually produced with light quanta in the visible range, are not activated with the quanta from the Nd:YAG laser at 1064 nm. The Raman spectra of the 'dark' form of a dinitrobenzyl pyridine and afterwards the 'light' form, the product of its illumination in the visible range, were recorded. We could not observe changes of most bands, especially not of the NO2-vibrations; however, a new strong band appeared at 1253 cm(-1), which may be due to the expected NH-photo-isomer. Genuine gemstones and fakes can be unambiguously identified by FT Raman spectroscopy. This is especially useful for the stones whose physical properties are quite similar to those of diamonds--moissanite and zirconia. The quality of diamonds can be estimated from relative band intensities; however, this is not in complete agreement with the internationally accepted visual qualification. Synthetic diamonds produced by CVD (chemical vapor deposition) show remarkable differences from natural ones in their FT-Raman spectra.

Investigation of X-ray lasers on the SOKOL-P facility at RFNC-VNIITF

NASA Astrophysics Data System (ADS)

Gavrilov, D. S.; Andriyash, A. V.; Vikhlyaev, D. A.; Gorokhov, S. A.; Dmitrov, D. A.; Zapysov, A. L.; Kakshin, A. G.; Kapustin, I. A.; Loboda, E. A.; Lykov, V. A.; Politov, V. Yu.; Potapov, A. V.; Pronin, V. A.; Rykovanov, G. N.; Sukhanov, V. N.; Tischenko, A. S.; Ugodenko, A. A.; Chefonov, O. V.

2007-11-01

The experiments [1] have demonstrated generation of the laser X-radiation (LXR) λ=326A on 3p-3s transitions of Ne-like Ti ions at sequential irradiation of the targets by two laser pulses, focused into a narrow line. The small signal gain equaled 30cm-1. The intensity was 0.5.10^12 W/cm^2 in the prepulse of 0.4ns and 10^14 W/cm^2 in the master pulse of 4ps (delay 1.5 ns). The dependence of LXR yield on the laser energy is demonstrated to have an exponential form. The traveling pumping wave mode was realized using the reflective echelon and the LXR yield is as great as 5-fold. The latest experiments have demonstrated the LXR generation on 4d-4p of Ni-like molybdenum λ=189A. The development of LXR generation model, and numerical codes which allow for the quanta delay effects, quanta refraction in plasma with heavy density gradient, and also the saturation effect have made it possible to describe the experimental dependence of the output LXR yield on the active medium length. Good quantitative agreement is also evident when estimating the output LXR yield on Ne-like Ti ions. [1]Andriyash Quantum Electronics 36 511

Drag effects and vortex states in binary superfluids in optical lattices

NASA Astrophysics Data System (ADS)

Meyerovich, Alexander; Kuklov, Anatoly

2005-03-01

Drag effects in two-condensate superfluids (A and B) in optical lattices are explored in strongly interacting limit. Mutual drag changes circulation quanta of vortices depending on the component concentration and interaction. This is a lattice analog of ^3He-HeII mixtures, in which the drag, proportional to the difference between bare and effective masses of quasiparticles, causes pressure-driven transitions in vortex charges [1]. The vortex binding in the hard-core boson limit relies, in contrast to the soft-core case studied in Monte Carlo simulations [2], on the vacancy-assisted tunneling. The model lattice for study of such effects is introduced. The variational and Monte Carlo calculations for the system, in which the tunneling for component A depends on the concentration of B, show the possibility of formation of the quasi-molecular condensate ABm in addition to the condensates of A and B. A strong drag, leading to the composite vortices with multiple quanta, also becomes possible. The work is supported by NSF grants DMR-0077266 and ITR-405460001 and PSC-CUNY- 665560035. 1. A. E. Meyerovich, Phys. Rev. A 68, 05162 (2003); Sov. Phys.-JETP 60, 41 (1984) 2. A. Kuklov, N. Prokof'ev, and B. Svistunov, Phys. Rev. Lett. 92, 030403 (2004)

Estimation of chromophoric dissolved organic matter (CDOM) and photosynthetic activity of estuarine phytoplankton using a multiple-fixed-wavelength spectral fluorometer.

PubMed

Goldman, Emily A; Smith, Erik M; Richardson, Tammi L

2013-03-15

The utility of a multiple-fixed-wavelength spectral fluorometer, the Algae Online Analyser (AOA), as a means of quantifying chromophoric dissolved organic matter (CDOM) and phytoplankton photosynthetic activity was tested using algal cultures and natural communities from North Inlet estuary, South Carolina. Comparisons of AOA measurements of CDOM to those by spectrophotometry showed a significant linear relationship, but increasing amounts of background CDOM resulted in progressively higher over-estimates of chromophyte contributions to a simulated mixed algal community. Estimates of photosynthetic activity by the AOA at low irradiance (≈ 80 μmol quanta m(-2) s(-1)) agreed well with analogous values from the literature for the chlorophyte, Dunaliella tertiolecta, but were substantially lower than previous measurements of the maximum quantum efficiency of photosystem II (F(v)/F(m)) in Thalassiosira weissflogii (a diatom) and Rhodomonas salina (a cryptophyte). When cells were exposed to high irradiance (1500 μmol quanta m(-2) s(-1)), declines in photosynthetic activity with time measured by the AOA mirrored estimates of cellular fluorescence capacity using the herbicide 3'-(3, 4-dichlorophenyl)-1',1'-dimethyl urea (DCMU). The AOA shows promise as a tool for the continuous monitoring of phytoplankton community composition, CDOM, and the group-specific photosynthetic activity of aquatic ecosystems. Copyright © 2012 Elsevier Ltd. All rights reserved.

Isotope-Identifying neutron reflectometry

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

Nikitenko, Yu. V., E-mail: nikiten@nf.jinr.ru; Petrenko, A. V.; Gundorin, N. A.

2015-07-15

The possibilities of an isotope-indentifying study of layered structures in different regimes of a neutron wave field are considered. The detection of specularly reflected neutrons and secondary radiation (caused by neutron capture) in the form of charged particles, γ quanta, and nuclear fission fragments, as well as neutrons spin-flipped in a noncollinear magnetic field and on nuclei of elements with spin, makes it possible to implement isotope-indentifying neutron reflectometry.

Status of the AFRL/RW Bio-Sensors Lab

DTIC Science & Technology

2012-03-28

shall be subject to any penalty for failing to comply with a collection of information if it does not display a currently valid OMB control number...various materials: polarization characterizations, spectral BRDFs , Mueller matrix elements, surface roughness characterization with a Zygo profilometer... model 5900LV, with the capability to image up to 100,000X at 30,000eV) and an ESEM (FEI Quanta 200, with ancillary equipment including EDAX’s

Asymptotic Charges at Null Infinity in Any Dimension

NASA Astrophysics Data System (ADS)

Campoleoni, Andrea; Francia, Dario; Heissenberg, Carlo

2018-03-01

We analyse the conservation laws associated with large gauge transformations of massless fields in Minkowski space. Our aim is to highlight the interplay between boundary conditions and finiteness of the asymptotically conserved charges in any space-time dimension, both even and odd, greater than or equal to three. After discussing non-linear Yang-Mills theory and revisiting linearised gravity, our investigation extends to cover the infrared behaviour of bosonic massless quanta of any spin.

Low-Density, Refractory Multi-Principal Element Alloys of the Cr-Nb-Ti-V-Zr System: Microstructure and Phase Analysis (Postprint)

DTIC Science & Technology

2012-12-19

remelted five times, being flipped for each melt, and was in a liquid state for about 5 min during each melting event. The pre- pared cigar -shaped...section surfaces using a 136 Vickers diamond pyramid under a 500 g load applied for 20 s. The micro- structure was analyzed by scanning electron ...microscopy (SEM) using a Quanta 600F scanning electron microscope (FEI, North America NanoPort, Hillsboro, OR) equipped with backscatter electron (BSE

Role of Acetylcholinesterase on the Structure and Function of Cholinergic Synapses: Insights Gained from Studies on Knockout Mice

DTIC Science & Technology

2011-01-01

in the number of quanta released per impulse or a reduction in the desensitization rate of AChRs, which are potentially adaptive, do not seem to occur... potential , Medical chemical defense 16. SECURITY CLASSIFICATION OF: 17. LIMITATION OF ABSTRACT 18. NUMBER OF PAGES 19a. NAME OF RESPONSIBLE PERSON...must adapt to allow for survival of the organism in the absence of AChE. Nerve-elicited muscle contractions, miniature endplate potentials (MEPPs) and

Analytic Methods for Predicting Significant Multi-Quanta Effects in Collisional Molecular Energy Transfer

NASA Technical Reports Server (NTRS)

Bieniek, Ronald J.

1996-01-01

Collision-induced transitions can significantly affect molecular vibrational-rotational populations and energy transfer in atmospheres and gaseous systems. This, in turn. can strongly influence convective heat transfer through dissociation and recombination of diatomics. and radiative heat transfer due to strong vibrational coupling. It is necessary to know state-to-state rates to predict engine performance and aerothermodynamic behavior of hypersonic flows, to analyze diagnostic radiative data obtained from experimental test facilities, and to design heat shields and other thermal protective systems. Furthermore, transfer rates between vibrational and translational modes can strongly influence energy flow in various 'disturbed' environments, particularly where the vibrational and translational temperatures are not equilibrated.

Space γ-observatory GAMMA-400 Current Status and Perspectives

NASA Astrophysics Data System (ADS)

Galper, A. M.; Bonvicini, V.; Topchiev, N. P.; Adriani, O.; Aptekar, R. L.; Arkhangelskaja, I. V.; Arkhangelskiy, A. I.; Bergstrom, L.; Berti, E.; Bigongiari, G.; Bobkov, S. G.; Boezio, M.; Bogomolov, E. A.; Bonechi, S.; Bongi, M.; Bottai, S.; Castellini, G.; Cattaneo, P. W.; Cumani, P.; Dedenko, G. L.; De Donato, C.; Dogiel, V. A.; Gorbunov, M. S.; Gusakov, Yu. V.; Hnatyk, B. I.; Kadilin, V. V.; Kaplin, V. A.; Kaplun, A. A.; Kheymits, M. D.; Korepanov, V. E.; Larsson, J.; Leonov, A. A.; Loginov, V. A.; Longo, F.; Maestro, P.; Marrocchesi, P. S.; Mikhailov, V. V.; Mocchiutti, E.; Moiseev, A. A.; Mori, N.; Moskalenko, I. V.; Naumov, P. Yu.; Papini, P.; Pearce, M.; Picozza, P.; Rappoldi, A.; Ricciarini, S.; Runtso, M. F.; Ryde, F.; Serdin, O. V.; Sparvoli, R.; Spillantini, P.; Suchkov, S. I.; Tavani, M.; Taraskin, A. A.; Tiberio, A.; Tyurin, E. M.; Ulanov, M. V.; Vacchi, A.; Vannuccini, E.; Vasilyev, G. I.; Yurkin, Yu. T.; Zampa, N.; Zirakashvili, V. N.; Zverev, V. G.

GAMMA-400 γ-ray telescope is designed to measure fluxes of γ-rays and the electron-positron cosmic ray component possibly generated in annihilation or decay of dark matter particles; to search for and study in detail discrete γ-ray sources, to examine the energy spectra of Galactic and extragalactic diffuse γ-rays, to study γ-ray bursts and γ-rays from the active Sun. GAMMA-400 consists of plastic scintillation anticoincidence top and lateral detectors, converter-tracker, plastic scintillation detectors for the time-of-flight system (TOF), two-part calorimeter (CC1 and CC2), plastic scintillation lateral detectors of calorimeter, plastic scintillation detectors of calorimeter, and neutron detector. The converter-tracker consists of 13 layers of double (x, y) silicon strip coordinate detectors (pitch of 0.08 mm). The first three and final one layers are without tungsten while the middle nine layers are interleaved with nine tungsten conversion foils. The thickness of CC1 and CC2 is 2 X0 (0.1λ0) and 23 X0 (1.1λ0) respectively (where X0 is radiation length and λ0 is nuclear interaction one). The total calorimeter thickness is 25 X0 or 1.2λ0 for vertical incident particles registration and 54 X0 or 2.5λ0 for laterally incident ones. The energy range for γ-rays and electrons (positrons) registration in the main aperture is from ∼0.1 GeV to ∼3.0 TeV. The γ-ray telescope main aperture angular and energy resolutions are respectively ∼0.01 and ∼1% for 102 GeV γ-quanta, the proton rejection factor is ∼5×105. The first three strip layers without tungsten provide the registration of γ-rays down to ∼20 MeV in the main aperture. Also this aperture allows investigating high energy light nuclei fluxes characteristics. Electrons, positrons, light nuclei and gamma-quanta will also register from the lateral directions due to special aperture configuration. Lateral aperture energy resolution is the same as for main aperture for electrons, positrons, light

The effect of potassium on exocytosis of transmitter at the frog neuromuscular junction.

PubMed Central

Ceccarelli, B; Fesce, R; Grohovaz, F; Haimann, C

1988-01-01

1. Electrophysiology and morphology have been combined to investigate the time course of the exocytosis of quanta of neurotransmitter induced by elevated concentrations of K+ at the frog neuromuscular junction. 2. Replicas of freeze-fractured resting nerve terminals fixed in the presence of 20 mM-K+ showed images of fusion of synaptic vesicles with the presynaptic axolemma which were closely associated with the active zones. After 1 min in 20 nM-K+ fusions appeared also outside the active zones, and by 5 min they became uniformly distributed over the presynaptic membrane. 3. The average total density of fusions was not significantly different at the various times examined since it decreased at the active zones while it increased over the rest of the membrane. 4. Resting terminals fixed in 20 mM-K+ released 33,000-45,000 quanta after the addition of fixative; terminals stimulated by 20 mM-K+ for 1-5 min released 50,000-100,000 quanta during fixation. The fixative potentiated K+-induced transmitter release. 5. Fusions were uniformly distributed in terminals pre-incubated for 5 min in 20 mM-K+ without added Ca2+, stimulated by adding Ca2+ for 30 s, and then fixed. Conversely, after 5 min stimulation in hypertonic Ringer solution fusions remained predominantly located near the active zones. A similar distribution was observed after 15 min stimulation by a lower concentration of K+ (15 mM). 6. At all concentrations of K+ tested (10, 15, 20, 25 mM) miniature end-plate potential (MEPP) rate attained a steady-state value within 10-15 min. Values from a single junction were generally lower at higher concentrations of K+, which indicates partial inactivation of the secretion-recycling process. 7. The data indicate that K+ initially activates exocytosis at the active zones. Subsequently, ectopic exocytosis is activated while sites at the active zones appear to undergo partial inactivation. These phenomena are not related to the intensity or to the amount of previous secretion

The Mathematical Structure of Elementary Particles. II.

DTIC Science & Technology

1985-05-01

apparently related to the Higgs fields of electroweak interactions. 6.11 UNITARY SYM’ILTRY OF THE STABLE QUANTA We still need to analyze the implications of...Remark this A has nothing to do with the cosmological constant in Chapter V.) From now on we agree to represent any complex number A in...bring in the axial symmetry effects, but this would be useless because in our case new phe- nomena arise (exchange forces, metric averaging, Higgs

Commissioning of the J-PET Detector for Studies of Decays of Positronium Atoms

NASA Astrophysics Data System (ADS)

Czerwiński, E.; Dulski, K.; Białas, P.; Curceanu, C.; Gajos, A.; Głowacz, B.; Gorgol, M.; Hiesmayr, B. C.; Jasińska, B.; Kisielewska, D.; Korcyl, G.; Kowalski, P.; Kozik, T.; Krawczyk, N.; Krzemień, W.; Kubicz, E.; Mohammed, M.; Niedźwiecki, Sz.; Pałka, M.; Pawlik-Niedźwiecka, M.; Raczyński, L.; Rudy, Z.; Sharma, N. G.; Sharma, S.; Shopa, R. Y.; Silarski, M.; Skurzok, M.; Wieczorek, A.; Wiślicki, W.; Zgardzińska, B.; Zieliński, M.; Moskal, P.

The Jagiellonian Positron Emission Tomograph (J-PET) is a detector for medical imaging of the whole human body as well as for physics studies involving detection of electron-positron annihilation into photons. J-PET has high angular and time resolution and allows for measurement of spin of the positronium and the momenta and polarization vectors of annihilation quanta. In this article, we present the potential of the J-PET system for background rejection in the decays of positronium atoms.

Neutral Pion Photoproduction on Neutron

DOE PAGES

Bulychev, S. A.; Kudryavtsev, A. E.; Kulikov, V. V.; ...

2018-03-12

The reaction γn → π 0n is investigated both theoretically and experimentally as an important step toward determining the electromagnetic coupling constants of the N* and Δ* resonances. We analyze the data on the collisions of γ quanta with energies between 200 and 800 MeV with a deuterium target collected by the A2 experiment in Mainz, Germany. Furthermore, these complement the data for neutral-pion photoproduction on protons obtained by the same experiment.

CMB and the elementary particles structure deduced from QFT of non-dot model

NASA Astrophysics Data System (ADS)

Chen, Shao-Guang

In my paper ‘Planck Constant Deduced from Metrical Results of Doppler Effect of Moving Particle —Uncertainty Principle Caused by Collision of a Particle with CMB Photons and Virtual Photons (H05-0036-10)’ the absolute velocity is decided by CMB which as a mark of the vacuum. CMB come from the thermal radiation of stars via gravitational redshift about 10 (13) year (E14- 0032-08). In my paper ‘Quanta turn-advance ism, China Science && Technology Overview 131 192-210 (2011)’, QFT four-dimensional uncertainty principle and momentum-energy conservation law had been generalized as a five-dimensional equations: de Broglie wavelength as a position vector \\underline{q}= (i c t, r, s), momentum \\underline{P} = (i E / c, P, U c), \\underline{q} = i h / \\underline{P}, \\underline{q} \\underline{q} = 0, \\underline{P} \\underline{P} = 0, Sigma∑ \\underline{P} = \\underline{P} (0) . The five-dimensional time-space-spin had been quantized as a non-dot model basic cell, the lowest energy state vertical polarized left spin 1/2 neutrino and right spin 1/2 antineutrino are just the left, right advance unit quanta _{0}nuυ, nuυ _{0} and left, right back unit quanta (0) nuυ, nuυ (0) , it again compose into spin 1 unit advance photons _{0}nuυnuυ _{0} and back (0) nuυnuυ (0) , spin 0 unit rest mass nuυ _{0}nuυ (0) and anti-mass _{0}nuυ (0) nuυ, spin 0 unit positive charge _{0}nuυnuυ (0) and negative charge nuυ _{0} (0) nuυ. It accord to the high energy physics experimental results of the transformation among the photons, masses quanta and charges quanta. The physical vacuum is the even collocation of non-combinational nuυ _{0} or _{0}nuυ. QFT is no longer with divergence difficulty by the non-dot model. It is mathematically easy that from five-dimensional equations deduce out the Dirac, Klein-Gordan, Maxwell equations and Lorentz force formula, but appear some new results. The interactions between _{0}nuυ, nuυ _{0}, (0) nuυ, nuυ (0) , i.e., force f

Riemann-Hypothesis Millennium-Problem(MP) Physics Proof via CATEGORY-SEMANTICS(C-S)/F =C Aristotle SQUARE-of-OPPOSITION(SoO) DEduction-LOGIC DichotomY

NASA Astrophysics Data System (ADS)

Baez, Joao-Joan; Lapidaryus, Michelle; Siegel, Edward Carl-Ludwig

2013-03-01

Riemann-hypothesis physics-proof combines: Siegel-Antono®-Smith[AMS Joint Mtg.(2002)- Abs.973-03-126] digits on-average statistics HIll[Am. J. Math 123, 3, 887(1996)] logarithm-function's (1,0)- xed-point base =units =scale-invariance proven Newcomb [Am. J. Math. 4, 39(1881)]-Weyl[Goett. Nachr.(1914); Math. Ann.7, 313(1916)]-Benford[Proc. Am. Phil. Soc. 78, 4, 51(1938)]-law [Kac,Math. of Stat.-Reasoning(1955); Raimi, Sci. Am. 221, 109(1969)] algebraic-inversion to ONLY Bose-Einstein quantum-statistics(BEQS) with digit d = 0 gapFUL Bose-Einstein Condensation(BEC) insight that digits are quanta are bosons because bosons are and always were quanta are and always were digits, via Siegel-Baez category-semantics tabular list-format matrix truth-table analytics in Plato-Aristotle classic ''square-of-opposition'' : FUZZYICS =CATEGORYICS/Category-Semantics, with Goodkind Bose-Einstein Condensation (BEC) ABOVE ground-state with/and Rayleigh(cut-limit of ''short-cut method''1870)-Polya(1922)-''Anderson''(1958) localization [Doyle and Snell,Random-Walks and Electrical-Networks, MAA(1981)-p.99-100!!!] in Brillouin[Wave-Propagation in Periodic-Structures(1946) Dover(1922)]-Hubbard-Beeby[J.Phys.C(1967)] Siegel[J.Nonxline-Sol.40,453(1980)] generalized-disorder collective-boson negative-dispersion mode-softening universality-principle(G...P) first use of the ``square-of-opposition'' in physics since Plato and Aristote!!!

Inflationary dynamics and preheating of the nonminimally coupled inflaton field in the metric and Palatini formalisms

NASA Astrophysics Data System (ADS)

Fu, Chengjie; Wu, Puxun; Yu, Hongwei

2017-11-01

The inflationary dynamics and preheating in a model with a nonminimally coupled inflaton field in the metric and Palatini formalisms are studied in this paper. We find that in both formalisms, irrespective of the initial conditions, our Universe will evolve into a slow-roll inflationary era and then the scalar field rolls into an oscillating phase. The value of the scalar field at the end of the inflation in the Palatini formalism is always larger than that in the metric one, which becomes more and more obvious with the increase of the absolute value of the coupling parameter |ξ |. During the preheating, we find that the inflaton quanta are produced explosively due to the parameter resonance and the growth of inflaton quanta will be terminated by the backreaction. With the increase of |ξ |, the resonance bands gradually close to the zero momentum (k =0 ), and the structure of resonance changes and becomes broader and broader in the metric formalism, while it remains to be narrow in the Palatini formalism. The energy transfer from the inflaton field to the fluctuation becomes more and more efficient with the increase of |ξ |, and in the metric formalism the growth of the efficiency of energy transfer is much faster than that in the Palatini formalism. Therefore, the inflation and preheating show different characteristics in different formalisms.

A feasibility study of ortho-positronium decays measurement with the J-PET scanner based on plastic scintillators

NASA Astrophysics Data System (ADS)

Kamińska, D.; Gajos, A.; Czerwiński, E.; Alfs, D.; Bednarski, T.; Białas, P.; Curceanu, C.; Dulski, K.; Głowacz, B.; Gupta-Sharma, N.; Gorgol, M.; Hiesmayr, B. C.; Jasińska, B.; Korcyl, G.; Kowalski, P.; Krzemień, W.; Krawczyk, N.; Kubicz, E.; Mohammed, M.; Niedźwiecki, Sz.; Pawlik-Niedźwiecka, M.; Raczyński, L.; Rudy, Z.; Silarski, M.; Wieczorek, A.; Wiślicki, W.; Zgardzińska, B.; Zieliński, M.; Moskal, P.

2016-08-01

We present a study of the application of the Jagiellonian positron emission tomograph (J-PET) for the registration of gamma quanta from decays of ortho-positronium (o-Ps). The J-PET is the first positron emission tomography scanner based on organic scintillators in contrast to all current PET scanners based on inorganic crystals. Monte Carlo simulations show that the J-PET as an axially symmetric and high acceptance scanner can be used as a multi-purpose detector well suited to pursue research including e.g. tests of discrete symmetries in decays of ortho-positronium in addition to the medical imaging. The gamma quanta originating from o-Ps decay interact in the plastic scintillators predominantly via the Compton effect, making the direct measurement of their energy impossible. Nevertheless, it is shown in this paper that the J-PET scanner will enable studies of the { o-Ps }→ 3γ decays with angular and energy resolution equal to σ (θ ) ≈ {0.4°} and σ (E) ≈ 4.1 {keV}, respectively. An order of magnitude shorter decay time of signals from plastic scintillators with respect to the inorganic crystals results not only in better timing properties crucial for the reduction of physical and instrumental background, but also suppresses significantly the pile-ups, thus enabling compensation of the lower efficiency of the plastic scintillators by performing measurements with higher positron source activities.

Investigation of the structure of /sup 4/He in a translationally invariant oscillator basis

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

Bartaya, O.L.; Macharadze, T.S.

1977-12-01

The binding energy, mean square radius, and charge form factor of the /sup 4/He nucleus are calculated using a translationally invariant basis. The realistic local nucleon-nucleon potential of Gogni, Pires, and De Tourreil (Phys. Lett. B 32B, 591 (1970)) is used in the calculations. Taken into account in the basis are all translationally invariant oscillator states with spatial symmetry (f)=4) and number of excitation quanta N< or =8 and with symmetry (f)=22) and N< or =6.

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

Tannenbaum, Michael J.

The search for the left-handed W± bosons, the proposed quanta of the weak interaction, and the Higgs boson, which spontaneously breaks the symmetry of unification of electromagnetic and weak interactions, has driven elementary-particle physics research from the time that I entered college to the present and has led to many unexpected and exciting discoveries which revolutionized our view of subnuclear physics over that period. In this article I describe how these searches and discoveries have intertwined with my own career.

Waiting for the W and the Higgs

DOE PAGES

Tannenbaum, Michael J.

2016-10-06

The search for the left-handed W± bosons, the proposed quanta of the weak interaction, and the Higgs boson, which spontaneously breaks the symmetry of unification of electromagnetic and weak interactions, has driven elementary-particle physics research from the time that I entered college to the present and has led to many unexpected and exciting discoveries which revolutionized our view of subnuclear physics over that period. In this article I describe how these searches and discoveries have intertwined with my own career.

Davydov Solitons in Polypeptides

NASA Astrophysics Data System (ADS)

Scott, A. C.

1985-08-01

The experimental evidence for self-trapping of amide-I (CO stretching) vibrational energy in crystalline acetanilide (a model protein) is reviewed and related to A. S. Davydov's theory of solitons as a mechanism for energy storage and transport in protein. Particular attention is paid to the construction of quantum states that contain N amide-I vibrational quanta. It is noted that the `N = 2' state is almost exactly resonant with the free energy that is released upon hydrolysis of adenosine triphosphate.

Positron Annihilation in Polycrystalline Silver Samples Subjected to the Stretching Force

NASA Astrophysics Data System (ADS)

Pajak, J.; Rudzińska, W.; Pietrzak, R.; Szymański, Cz.; Smiatek, W.

Angular distributions of the positron annihilation quanta, positron lifetime and resistivity were measured for polycrystalline silver samples deformed by uniaxial tension up to different deformation degrees. The S parameter as a function of deformation degree of the sample has been determined. The data obtained for silver samples elongated up to different elongation degrees indicate the dominant role of vacancies and larger defects type clusters created during the deformation process. The positron annihilation data are corrob-orated by results obtained by resistivity measurements.

Waiting for the W. and the Higgs

NASA Astrophysics Data System (ADS)

Tannenbaum, M. J.

2016-12-01

The search for the left-handed W± bosons, the proposed quanta of the weak interaction, and the Higgs boson, which spontaneously breaks the symmetry of unification of electromagnetic and weak interactions, has driven elementary-particle physics research from the time that I entered college to the present and has led to many unexpected and exciting discoveries which revolutionized our view of subnuclear physics over that period. In this article I describe how these searches and discoveries have intertwined with my own career.

Dirac Sea and its Evolution

NASA Astrophysics Data System (ADS)

Volfson, Boris

2013-09-01

The hypothesis of transition from a chaotic Dirac Sea, via highly unstable positronium, into a Simhony Model of stable face-centered cubic lattice structure of electrons and positrons securely bound in vacuum space, is considered. 13.75 Billion years ago, the new lattice, which, unlike a Dirac Sea, is permeable by photons and phonons, made the Universe detectable. Many electrons and positrons ended up annihilating each other producing energy quanta and neutrino-antineutrino pairs. The weak force of the electron-positron crystal lattice, bombarded by the chirality-changing neutrinos, may have started capturing these neutrinos thus transforming from cubic crystals into a quasicrystal lattice. Unlike cubic crystal lattice, clusters of quasicrystals are "slippery" allowing the formation of centers of local torsion, where gravity condenses matter into galaxies, stars and planets. In the presence of quanta, in a quasicrystal lattice, the Majorana neutrinos' rotation flips to the opposite direction causing natural transformations in a category comprised of three components; two others being positron and electron. In other words, each particle-antiparticle pair "e-" and "e+", in an individual crystal unit, could become either a quasi- component "e- ve e+", or a quasi- component "e+ - ve e-". Five-to-six six billion years ago, a continuous stimulation of the quasicrystal aetherial lattice by the same, similar, or different, astronomical events, could have triggered Hebbian and anti-Hebbian learning processes. The Universe may have started writing script into its own aether in a code most appropriate for the quasicrystal aether "hardware": Eight three-dimensional "alphabet" characters, each corresponding to the individual quasi-crystal unit shape. They could be expressed as quantum Turing machine qubits, or, alternatively, in a binary code. The code numerals could contain terminal and nonterminal symbols of the Chomsky's hierarchy, wherein, the showers of quanta, forming the

Estimation of composition of cosmic rays with E sub zero approximately equals 10(17) - 10(18) eV

NASA Technical Reports Server (NTRS)

Glushkov, A. V.; Efimov, N. N.; Efremov, N. N.; Makarov, I. T.; Pravdin, M. I.; Dedenko, L. I.

1985-01-01

Fluctuations of the shower maximum depth obtained from analysis of electron and muon fluctuations and the extensive air showers (EAS) Cerenkov light on the Yakutsk array data and data of other arrays are considered. On the basis of these the estimation of composition of primaries with E sub 0 = 5.10 to the 17th power eV is received. Estimation of gamma-quanta flux with E sub 0 10 to the 17th power eV is given on the poor-muon showers.

An Automated System for the Control of, and Data Acquisition from Multiphoton Ionization and Fluorescence Lifetime Measurements.

DTIC Science & Technology

1986-09-01

Quanta- Ray company , which also supplied the laser used for the multiphoton work. The, burner was mounted on a translator stage from Velmex, Inc...and no longer exists as a process in the system. When the user analysis program has completed, the lifetime program is again automatically re-started...KCHAR) RETURN 100 FORMAT(I3) 101 FORMAT(F7.2) END SUBROUTINE LAB4 FODA SE"oteD C This routine puts the label "INTEGRAL FROM DATA SET" on the MDP C screen

Davydov solitons in polypeptides

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

Scott, A.

1984-10-01

The experimental evidence for self-trapping of amide-I (CO stretching) vibrational energy in crystalline acetanilide (a model protein) is reviewed and related to A. S. Davydov's theory of solitons as a mechanism for energy storage and transport in protein. Particular attention is paid to the construction of quantum states that contain N amide-I vibrational quanta. It is noted that the N = 2 state is almost exactly resonant with the free energy that is released upon hydrolysis of adenosine triphosphate. 30 references, 4 figures, 3 tables.

The detective quantum efficiency of photon-counting x-ray detectors using cascaded-systems analyses

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

Tanguay, Jesse; Yun, Seungman; School of Mechanical Engineering, Pusan National University, Jangjeon-dong, Geumjeong-gu, Busan 609-735

Purpose: Single-photon counting (SPC) x-ray imaging has the potential to improve image quality and enable new advanced energy-dependent methods. The purpose of this study is to extend cascaded-systems analyses (CSA) to the description of image quality and the detective quantum efficiency (DQE) of SPC systems. Methods: Point-process theory is used to develop a method of propagating the mean signal and Wiener noise-power spectrum through a thresholding stage (required to identify x-ray interaction events). The new transfer relationships are used to describe the zero-frequency DQE of a hypothetical SPC detector including the effects of stochastic conversion of incident photons to secondarymore » quanta, secondary quantum sinks, additive noise, and threshold level. Theoretical results are compared with Monte Carlo calculations assuming the same detector model. Results: Under certain conditions, the CSA approach can be applied to SPC systems with the additional requirement of propagating the probability density function describing the total number of image-forming quanta through each stage of a cascaded model. Theoretical results including DQE show excellent agreement with Monte Carlo calculations under all conditions considered. Conclusions: Application of the CSA method shows that false counts due to additive electronic noise results in both a nonlinear image signal and increased image noise. There is a window of allowable threshold values to achieve a high DQE that depends on conversion gain, secondary quantum sinks, and additive noise.« less

A common fluence threshold for first positive and second positive phototropism in Arabidopsis thaliana

NASA Technical Reports Server (NTRS)

Janoudi, A.; Poff, K. L.

1990-01-01

The relationship between the amount of light and the amount of response for any photobiological process can be based on the number of incident quanta per unit time (fluence rate-response) or on the number of incident quanta during a given period of irradiation (fluence-response). Fluence-response and fluence rate-response relationships have been measured for second positive phototropism by seedlings of Arabidopsis thaliana. The fluence-response relationships exhibit a single limiting threshold at about 0.01 micromole per square meter when measured at fluence rates from 2.4 x 10(-5) to 6.5 x 10(-3) micromoles per square meter per second. The threshold values in the fluence rate-response curves decrease with increasing time of irradiation, but show a common fluence threshold at about 0.01 micromole per square meter. These thresholds are the same as the threshold of about 0.01 micromole per square meter measured for first positive phototropism. Based on these data, it is suggested that second positive curvature has a threshold in time of about 10 minutes. Moreover, if the times of irradiation exceed the time threshold, there is a single limiting fluence threshold at about 0.01 micromole per square meter. Thus, the limiting fluence threshold for second positive phototropism is the same as the fluence threshold for first positive phototropism. Based on these data, we suggest that this common fluence threshold for first positive and second positive phototropism is set by a single photoreceptor pigment system.

Preillumination of lettuce seedlings with red light enhances the resistance of photosynthetic apparatus to UV-A.

PubMed

Kreslavski, Vladimir D; Lyubimov, Valery Yu; Shirshikova, Galina N; Shmarev, Alexander N; Kosobryukhov, Anatoly A; Schmitt, Franz-Josef; Friedrich, Thomas; Allakhverdiev, Suleyman I

2013-05-05

Seedlings of 10-day-old lettuce (Lactuca sativa L., cultivar Berlin) were preilluminated by low intensity red light (λmax=660 nm, 10 min, 5 μmol quanta m(-2) s(-1)) and far-red light (λmax=730 nm, 10 min, 5 μmol quanta m(-2) s(-1)) to study the effect of pre-treatment on photosynthesis, photochemical activity of photosystem II (PSII), the contents of photosynthetic and UV-A-absorbing pigments (UAPs) and H2O2, as well as total and ascorbate peroxidase activities in cotyledonary leaves of seedlings exposed to UV-A. UV radiation reduced the photosynthetic rate (Pn), the activity of PSII, and the contents of Chl a and b, carotenoids and UAPs in the leaves, but increased the content of H2O2 and the total peroxidase activity. Preillumination with red light removed these effects of UV. In turn, the illumination with red light, then far-red light removed the effect of the red light. Illumination with red light alone increased the content of UAPs, as well as peroxidase activity. It is suggested that higher resistance of the lettuce photosynthetic apparatus to UV-A radiation is associated with involvement of the active form of phytochrome B, thereby increasing peroxidase activities as well as UAPs and saving preservation of photosynthetic pigment contents due to pre-illumination with red light. Copyright © 2013 Elsevier B.V. All rights reserved.

Bayesian analysis of the kinetics of quantal transmitter secretion at the neuromuscular junction.

PubMed

Saveliev, Anatoly; Khuzakhmetova, Venera; Samigullin, Dmitry; Skorinkin, Andrey; Kovyazina, Irina; Nikolsky, Eugeny; Bukharaeva, Ellya

2015-10-01

The timing of transmitter release from nerve endings is considered nowadays as one of the factors determining the plasticity and efficacy of synaptic transmission. In the neuromuscular junction, the moments of release of individual acetylcholine quanta are related to the synaptic delays of uniquantal endplate currents recorded under conditions of lowered extracellular calcium. Using Bayesian modelling, we performed a statistical analysis of synaptic delays in mouse neuromuscular junction with different patterns of rhythmic nerve stimulation and when the entry of calcium ions into the nerve terminal was modified. We have obtained a statistical model of the release timing which is represented as the summation of two independent statistical distributions. The first of these is the exponentially modified Gaussian distribution. The mixture of normal and exponential components in this distribution can be interpreted as a two-stage mechanism of early and late periods of phasic synchronous secretion. The parameters of this distribution depend on both the stimulation frequency of the motor nerve and the calcium ions' entry conditions. The second distribution was modelled as quasi-uniform, with parameters independent of nerve stimulation frequency and calcium entry. Two different probability density functions for the distribution of synaptic delays suggest at least two independent processes controlling the time course of secretion, one of them potentially involving two stages. The relative contribution of these processes to the total number of mediator quanta released depends differently on the motor nerve stimulation pattern and on calcium ion entry into nerve endings.

Examples of the Zeroth Theorem of the History of Science

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

Jackson, J.D.

2007-08-24

The zeroth theorem of the history of science, enunciated byE. P. Fischer, states that a discovery (rule,regularity, insight) namedafter someone (often) did not originate with that person. I present fiveexamples from physics: the Lorentz condition partial muAmu = 0 definingthe Lorentz gauge of the electromagnetic potentials; the Dirac deltafunction, delta(x); the Schumann resonances of the earth-ionospherecavity; the Weizsacker-Williams method of virtual quanta; the BMTequation of spin dynamics. I give illustrated thumbnail sketches of boththe true and reputed discoverers and quote from their "discovery"publications.

Diffeomorphism Group Representations in Relativistic Quantum Field Theory

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

Goldin, Gerald A.; Sharp, David H.

We explore the role played by the di eomorphism group and its unitary representations in relativistic quantum eld theory. From the quantum kinematics of particles described by representations of the di eomorphism group of a space-like surface in an inertial reference frame, we reconstruct the local relativistic neutral scalar eld in the Fock representation. An explicit expression for the free Hamiltonian is obtained in terms of the Lie algebra generators (mass and momentum densities). We suggest that this approach can be generalized to elds whose quanta are spatially extended objects.

Measurement of the energy of horizontal cosmic ray muons

NASA Astrophysics Data System (ADS)

Gettert, Michael

1993-03-01

An experiment in which the energy of cosmic ray muons is determined by measuring the electron positron pairs that they radiate off when passing through matter is described. The detector is a stack of lead converters interspersed with ionization chambers for particle detection. The chambers use as active medium the liquid tetra methyl silane (TMS). The radiated quanta initiate electromagnetic cascades in the lead and are recognized due to the characteristic shower development. The energy spectrum of horizontal muons is presented and from this the primary cosmic ray spectrum is deduced.

Electric discharge in water as a source of UV radiation, ozone and hydrogen peroxide

NASA Astrophysics Data System (ADS)

Anpilov, A. M.; Barkhudarov, E. M.; Bark, Yu B.; Zadiraka, Yu V.; Christofi, M.; Kozlov, Yu N.; Kossyi, I. A.; Kop'ev, V. A.; Silakov, V. P.; Taktakishvili, M. I.; Temchin, S. M.

2001-03-01

Results are presented from investigations of multispark electric discharge in water excited along multielectrode metal-dielectric systems with gas supply into the interelectrode gaps. The intensity distribution of discharge radiation in the region covering the biologically active soft UV (190≤λ≤430 nm) has been determined and the absolute number of quanta in this wavelength interval has been measured. The potentiality of the slipping surface discharge in water for its disinfection is analysed. The energy expenditure for water cleansing is estimated to be as low as ~10-4 kWh l-1.

Experimental Studies of Josephson Effect

DTIC Science & Technology

1990-09-06

to test predictions that macroscopic variables, such as the flux through a SQUID loop, display quantum mechanical properties such as tunneling and...approximately Oo/L as flux quanta enter the loop. In the Josephson junctions used here are lead-alloy tunnel junc- linear region, for I, <<J, the rate...magnetometer. The junctions ln(F)-AU/kT+In(f/2z). (3) used were nominal I x I pm 2 Nb/AI2O3/Nb tunnel junc- As Fig. 3 shows, the observed dependence is in

Bioluminescence of Marine Dinoflagellates

PubMed Central

Seliger, H. H.; Fastie, W. G.; Taylor, W. R.; McElroy, W. D.

1962-01-01

Portable light-baffled underwater photometers have been designed for the measurement of dinoflagellate bioluminescence by day and night. Maximal light emission is obtained by mechanical stimulation in a defined volume. The pump which stimulates the dinoflagellates also constantly replenishes the sample volume so that continuous measurements are possible. Evidence for both diurnal variation and vertical migration is presented. Using luminous bacteria for calibration a single dinoflagellate has been found to emit of the order of 1010 light quanta per flash. The technique suggests that large scale mapping of bioluminescence is feasible. PMID:19873546

J-PET detector system for studies of the electron-positron annihilations

NASA Astrophysics Data System (ADS)

Pawlik-Niedźwiecka, M.; Khreptak, O.; Gajos, A.; Wieczorek, A.; Alfs, D.; Bednarski, T.; Białas, P.; Curceanu, C.; Czerwiński, E.; Dulski, K.; Głowacz, B.; Gupta-Sharma, N.; Gorgol, M.; Hiesmayr, B. C.; Jasińska, B.; Kamińska, D.; Korcyl, G.; Kowalski, P.; Krzmień, W.; Krawczyk, N.; Kubicz, E.; Mohammed, M.; Niedźwiecki, Sz.; Raczyński, L.; Rudy, Z.; Silarski, M.; Wiślicki, W.; Zgardzińska, B.; Zieliński, M.; Moskal, P.

2016-11-01

Jagiellonian Positron Emission Tomograph (J-PET) has been recently constructed at the Jagiellonian University as a prototype of a cost-effective scanner for the metabolic imaging of the whole human body. J-PET detector is optimized for the measurement of momentum and polarization of photons from the electron-positron annihilations. It is built out of strips of plastic scintillators, forming three cylindrical layers. As detector of gamma quanta it will be used for studies of discrete symmetries and multiparticle entanglement of photons originating from the decays of ortho-positronium atoms.

Quasi-polaritons in Bose-Einstein condensates induced by Casimir-Polder interaction with graphene.

PubMed

Terças, H; Ribeiro, S; Mendonça, J T

2015-06-03

We consider the mechanical coupling between a two-dimensional Bose-Einstein condensate and a graphene sheet via the vacuum fluctuations of the electromagnetic field which are at the origin of the so-called Casimir-Polder potential. By deriving a self-consistent set of equations governing the dynamics of the condensate and the flexural (out-of-plane) modes of the graphene, we can show the formation of a new type of purely acoustic quasi-particle excitation, a quasi-polariton resulting from the coherent superposition of quanta of flexural and Bogoliubov modes.

Magnonic Black Holes.

PubMed

Roldán-Molina, A; Nunez, Alvaro S; Duine, R A

2017-02-10

We show that the interaction between the spin-polarized current and the magnetization dynamics can be used to implement black-hole and white-hole horizons for magnons-the quanta of oscillations in the magnetization direction in magnets. We consider three different systems: easy-plane ferromagnetic metals, isotropic antiferromagnetic metals, and easy-plane magnetic insulators. Based on available experimental data, we estimate that the Hawking temperature can be as large as 1 K. We comment on the implications of magnonic horizons for spin-wave scattering and transport experiments, and for magnon entanglement.

Experimental test of the polarization direction correlation method (PDCO)

NASA Astrophysics Data System (ADS)

Starosta, K.; Morek, T.; Droste, Ch.; Rohoziński, S. G.; Srebrny, J.; Wierzchucka, A.; Bergström, M.; Herskind, B.; Melby, E.; Czosnyka, T.; Napiorkowski, P. J.

1999-02-01

The study of the polarization direction correlation method (PDCO) for γ quanta emitted from the nuclear states oriented in fusion-evaporation reactions is discussed with emphasis on making unique multipolarity assignments. The method is applied to the data coming from a typical experiment performed with the EUROGAM II array, where polarization-sensitive CLOVER detectors were used. The accuracy obtained in the experiment for the studied transitions was high enough to exclude, using the PDCO method, most of the ambiguities which occur if the assignments are made on the basis of angular correlation measurements alone.

Measurements of the gamma-quanta angular distributions emitted from neutron inelastic scattering on 28Si

NASA Astrophysics Data System (ADS)

Fedorov, N. A.; Grozdanov, D. N.; Bystritskiy, V. M.; Kopach, Yu. N.; Ruskov, I. N.; Skoy, V. R.; Tretyakova, T. Yu.; Zamyatin, N. I.; Wang, D.; Aliev, F. A.; Hramco, C.; Gandhi, A.; Kumar, A.; Dabylova, S.; Bogolubov, E. P.; Barmakov, Yu. N.

2018-04-01

The characteristic gamma radiation from the interaction of 14.1 MeV neutrons with a natural silicon sample is investigated with Tagged Neutron Method (TNM). The anisotropy of gamma-ray emission of 1.779 MeV was measured at 11 azimuth angles with a step of ∠15°. The present results are in good agreement with some recent experimental data.

Estimating the timing of quantal releases during end-plate currents at the frog neuromuscular junction.

PubMed Central

Van der Kloot, W

1988-01-01

1. Following motor nerve stimulation there is a period of greatly enhanced quantal release, called the early release period or ERP (Barrett & Stevens, 1972b). Until now, measurements of the probability of quantal releases at different points in the ERP have come from experiments in which quantal output was greatly reduced, so that the time of release of individual quanta could be detected or so that the latency to the release of the first quantum could be measured. 2. A method has been developed to estimate the timing of quantal release during the ERP that can be used at much higher levels of quantal output. The assumption is made that each quantal release generates an end-plate current (EPC) that rises instantaneously and then decays exponentially. The peak amplitude of the quantal currents and the time constant for their decay are measured from miniature end-plate currents (MEPCs). Then a number of EPCs are averaged, and the times of release of the individual quanta during the ERP estimated by a simple mathematical method for deconvolution derived by Cohen, Van der Kloot & Attwell (1981). 3. The deconvolution method was tested using data from preparations in high-Mg2+ low-Ca2+ solution. One test was to reconstitute the averaged EPCs from the estimated times of quantal release and the quantal currents, by using Fourier convolution. The reconstructions fit well to the originals. 4. Reconstructions were also made from averaged MEPCs which do not rise instantaneously and the estimated times of quantal release.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:2466987

Efficient method for calculations of ro-vibrational states in triatomic molecules near dissociation threshold: Application to ozone

NASA Astrophysics Data System (ADS)

Teplukhin, Alexander; Babikov, Dmitri

2016-09-01

A method for calculations of rotational-vibrational states of triatomic molecules up to dissociation threshold (and scattering resonances above it) is devised, that combines hyper-spherical coordinates, sequential diagonalization-truncation procedure, optimized grid DVR, and complex absorbing potential. Efficiency and accuracy of the method and new code are tested by computing the spectrum of ozone up to dissociation threshold, using two different potential energy surfaces. In both cases good agreement with results of previous studies is obtained for the lower energy states localized in the deep (˜10 000 cm-1) covalent well. Upper part of the bound state spectrum, within 600 cm-1 below dissociation threshold, is also computed and is analyzed in detail. It is found that long progressions of symmetric-stretching and bending states (up to 8 and 11 quanta, respectively) survive up to dissociation threshold and even above it, whereas excitations of the asymmetric-stretching overtones couple to the local vibration modes, making assignments difficult. Within 140 cm-1 below dissociation threshold, large-amplitude vibrational states of a floppy complex O⋯O2 are formed over the shallow van der Waals plateau. These are assigned using two local modes: the rocking-motion and the dissociative-motion progressions, up to 6 quanta in each, both with frequency ˜20 cm-1. Many of these plateau states are mixed with states of the covalent well. Interestingly, excitation of the rocking-motion helps keeping these states localized within the plateau region, by raising the effective barrier.

Modified Bose-Einstein and Fermi-Dirac statistics if excitations are localized on an intermediate length scale: applications to non-Debye specific heat.

PubMed

Chamberlin, Ralph V; Davis, Bryce F

2013-10-01

Disordered systems show deviations from the standard Debye theory of specific heat at low temperatures. These deviations are often attributed to two-level systems of uncertain origin. We find that a source of excess specific heat comes from correlations between quanta of energy if excitations are localized on an intermediate length scale. We use simulations of a simplified Creutz model for a system of Ising-like spins coupled to a thermal bath of Einstein-like oscillators. One feature of this model is that energy is quantized in both the system and its bath, ensuring conservation of energy at every step. Another feature is that the exact entropies of both the system and its bath are known at every step, so that their temperatures can be determined independently. We find that there is a mismatch in canonical temperature between the system and its bath. In addition to the usual finite-size effects in the Bose-Einstein and Fermi-Dirac distributions, if excitations in the heat bath are localized on an intermediate length scale, this mismatch is independent of system size up to at least 10(6) particles. We use a model for correlations between quanta of energy to adjust the statistical distributions and yield a thermodynamically consistent temperature. The model includes a chemical potential for units of energy, as is often used for other types of particles that are quantized and conserved. Experimental evidence for this model comes from its ability to characterize the excess specific heat of imperfect crystals at low temperatures.

A Common Fluence Threshold for First Positive and Second Positive Phototropism in Arabidopsis thaliana1

PubMed Central

Janoudi, Abdul; Poff, Kenneth L.

1990-01-01

The relationship between the amount of light and the amount of response for any photobiological process can be based on the number of incident quanta per unit time (fluence rate-response) or on the number of incident quanta during a given period of irradiation (fluence-response). Fluence-response and fluence rate-response relationships have been measured for second positive phototropism by seedlings of Arabidopsis thaliana. The fluence-response relationships exhibit a single limiting threshold at about 0.01 micromole per square meter when measured at fluence rates from 2.4 × 10−5 to 6.5 × 10−3 micromoles per square meter per second. The threshold values in the fluence rateresponse curves decrease with increasing time of irradiation, but show a common fluence threshold at about 0.01 micromole per square meter. These thresholds are the same as the threshold of about 0.01 micromole per square meter measured for first positive phototropism. Based on these data, it is suggested that second positive curvature has a threshold in time of about 10 minutes. Moreover, if the times of irradiation exceed the time threshold, there is a single limiting fluence threshold at about 0.01 micromole per square meter. Thus, the limiting fluence threshold for second positive phototropism is the same as the fluence threshold for first positive phototropism. Based on these data, we suggest that this common fluence threshold for first positive and second positive phototropism is set by a single photoreceptor pigment system. PMID:11537470

Black hole quantum spectrum

NASA Astrophysics Data System (ADS)

Corda, Christian

2013-12-01

Introducing a black hole (BH) effective temperature, which takes into account both the non-strictly thermal character of Hawking radiation and the countable behavior of emissions of subsequent Hawking quanta, we recently re-analysed BH quasi-normal modes (QNMs) and interpreted them naturally in terms of quantum levels. In this work we improve such an analysis removing some approximations that have been implicitly used in our previous works and obtaining the corrected expressions for the formulas of the horizon's area quantization and the number of quanta of area and hence also for Bekenstein-Hawking entropy, its subleading corrections and the number of micro-states, i.e. quantities which are fundamental to realize the underlying quantum gravity theory, like functions of the QNMs quantum "overtone" number n and, in turn, of the BH quantum excited level. An approximation concerning the maximum value of n is also corrected. On the other hand, our previous results were strictly corrected only for scalar and gravitational perturbations. Here we show that the discussion holds also for vector perturbations. The analysis is totally consistent with the general conviction that BHs result in highly excited states representing both the "hydrogen atom" and the "quasi-thermal emission" in quantum gravity. Our BH model is somewhat similar to the semi-classical Bohr's model of the structure of a hydrogen atom. The thermal approximation of previous results in the literature is consistent with the results in this paper. In principle, such results could also have important implications for the BH information paradox.

Co-regulation of dark and light reactions in three biochemical subtypes of C(4) species.

PubMed

Kiirats, Olavi; Kramer, David M; Edwards, Gerald E

2010-08-01

Regulation of light harvesting in response to changes in light intensity, CO(2) and O(2) concentration was studied in C(4) species representing three different metabolic subtypes: Sorghum bicolor (NADP-malic enzyme), Amaranthus edulis (NAD-malic enzyme), and Panicum texanum (PEP-carboxykinase). Several photosynthetic parameters were measured on the intact leaf level including CO(2) assimilation rates, O(2) evolution, photosystem II activities, thylakoid proton circuit and dissipation of excitation energy. Gross rates of O(2) evolution (J(O)₂'), measured by analysis of chlorophyll fluorescence), net rates of O(2) evolution and CO(2) assimilation responded in parallel to changes in light and CO(2) levels. The C(4) subtypes had similar energy requirements for photosynthesis since there were no significant differences in maximal quantum efficiencies for gross rates of O(2) evolution (average value = 0.072 O(2)/quanta absorbed, approximately 14 quanta per O(2) evolved). At saturating actinic light intensities, when photosynthesis was suppressed by decreasing CO(2), ATP synthase proton conductivity (g (H) (+)) responded strongly to changes in electron flow, decreasing linearly with J(O)₂', which was previously observed in C(3) plants. It is proposed that g (H) (+) is controlled at the substrate level by inorganic phosphate availability. The results suggest development of nonphotochemical quenching in C(4) plants is controlled by a decrease in g (H) (+), which causes an increase in proton motive force by restricting proton efflux from the lumen, rather than by cyclic or pseudocyclic electron flow.

A novel method for the line-of-response and time-of-flight reconstruction in TOF-PET detectors based on a library of synchronized model signals

NASA Astrophysics Data System (ADS)

Moskal, P.; Zoń, N.; Bednarski, T.; Białas, P.; Czerwiński, E.; Gajos, A.; Kamińska, D.; Kapłon, Ł.; Kochanowski, A.; Korcyl, G.; Kowal, J.; Kowalski, P.; Kozik, T.; Krzemień, W.; Kubicz, E.; Niedźwiecki, Sz.; Pałka, M.; Raczyński, L.; Rudy, Z.; Rundel, O.; Salabura, P.; Sharma, N. G.; Silarski, M.; Słomski, A.; Smyrski, J.; Strzelecki, A.; Wieczorek, A.; Wiślicki, W.; Zieliński, M.

2015-03-01

A novel method of hit time and hit position reconstruction in scintillator detectors is described. The method is based on comparison of detector signals with results stored in a library of synchronized model signals registered for a set of well-defined positions of scintillation points. The hit position is reconstructed as the one corresponding to the signal from the library which is most similar to the measurement signal. The time of the interaction is determined as a relative time between the measured signal and the most similar one in the library. A degree of similarity of measured and model signals is defined as the distance between points representing the measurement- and model-signal in the multi-dimensional measurement space. Novelty of the method lies also in the proposed way of synchronization of model signals enabling direct determination of the difference between time-of-flights (TOF) of annihilation quanta from the annihilation point to the detectors. The introduced method was validated using experimental data obtained by means of the double strip prototype of the J-PET detector and 22Na sodium isotope as a source of annihilation gamma quanta. The detector was built out from plastic scintillator strips with dimensions of 5 mm×19 mm×300 mm, optically connected at both sides to photomultipliers, from which signals were sampled by means of the Serial Data Analyzer. Using the introduced method, the spatial and TOF resolution of about 1.3 cm (σ) and 125 ps (σ) were established, respectively.

High-quality imaging in environmental scanning electron microscopy--optimizing the pressure limiting system and the secondary electron detection of a commercially available ESEM.

PubMed

Fitzek, H; Schroettner, H; Wagner, J; Hofer, F; Rattenberger, J

2016-04-01

In environmental scanning electron microscopy applications in the kPa regime are of increasing interest for the investigation of wet and biological samples, because neither sample preparation nor extensive cooling are necessary. Unfortunately, the applications are limited by poor image quality. In this work the image quality at high pressures of a FEI Quanta 600 (field emission gun) and a FEI Quanta 200 (thermionic gun) is greatly improved by optimizing the pressure limiting system and the secondary electron (SE) detection system. The scattering of the primary electron beam strongly increases with pressure and thus the image quality vanishes. The key to high-image quality at high pressures is to reduce scattering as far as possible while maintaining ideal operation conditions for the SE-detector. The amount of scattering is reduced by reducing both the additional stagnation gas thickness (aSGT) and the environmental distance (ED). A new aperture holder is presented that significantly reduces the aSGT while maintaining the same field-of-view (FOV) as the original design. With this aperture holder it is also possible to make the aSGT even smaller at the expense of a smaller FOV. A new blade-shaped SE-detector is presented yielding better image quality than usual flat SE-detectors. The electrode of the new SE detector is positioned on the sample table, which allows the SE-detector to operate at ideal conditions regardless of pressure and ED. © 2015 The Authors Journal of Microscopy © 2015 Royal Microscopical Society.

Experimental evaluation of environmental scanning electron microscopes at high chamber pressure.

PubMed

Fitzek, H; Schroettner, H; Wagner, J; Hofer, F; Rattenberger, J

2015-11-01

In environmental scanning electron microscopy (ESEM) high pressure applications have become increasingly important. Wet or biological samples can be investigated without time-consuming sample preparation and potential artefacts from this preparation can be neglected. Unfortunately, the signal-to-noise ratio strongly decreases with increasing chamber pressure. To evaluate the high pressure performance of ESEM and to compare different electron microscopes, information about spatial resolution and detector type is not enough. On the one hand, the scattering of the primary electron beam increases, which vanishes the contrast in images; and on the other hand, the secondary electrons (SE) signal amplification decreases. The stagnation gas thickness (effective distance the beam has to travel through the imaging gas) as well as the SE detection system depend on the microscope and for a complete and serious evaluation of an ESEM or low vacuum SEM it is necessary to specify these two parameters. A method is presented to determine the fraction of scattered and unscattered electrons and to calculate the stagnation gas thickness (θ). To evaluate the high pressure performance of the SE detection system, a method is presented that allows for an analysis of a single image and the calculation of the signal-to-noise ratio of this image. All investigations are performed on an FEI ESEM Quanta 600 (field emission gun) and an FEI ESEM Quanta 200 (thermionic gun). These methods and measurements should represent opportunities for evaluating the high pressure performance of an ESEM. © 2015 The Authors Journal of Microscopy © 2015 Royal Microscopical Society.

Desensitization shortens the high-quantal-content endplate current time course in frog muscle with intact cholinesterase.

PubMed

Giniatullin, R A; Talantova, M; Vyskocil, F

1997-08-01

1. The desensitization induced by bath-applied carbachol or acetylcholine (ACh) and potentiated by proadifen (SKF 525A) was studied in the frog sartorius with intact synaptic acetylcholinesterase (AChE). 2. The reduction in the density and number of postsynaptic receptors produced by desensitization lowered the amplitude of the endplate currents (EPCs) and shortened the EPC decay when the quantal content (m) of the EPC was about 170 and when multiple release of quanta at single active zones was highly probably. The shortening of high-quantal-content EPCs persisted for at least 15 min after the wash-out of agonists, at a time when the amplitude had recovered fully. 3. The decay times of the low-quantal-content EPCs recorded from preparations pretreated with 5 mM Mg2+ (m approximately 70) and single-quantum miniature endplate currents (MEPCs) were not affected by carbachol, ACh or proadifen. 4. The desensitization of ACh receptors potentiated by proadifen, prevented completely the 6- to 8-fold prolongation of EPC which was induced by neostigmine inhibition of synaptic AChE. 5. It is assumed that high-quantal-content EPCs increase the incidence of multiple quanta release at single active zones and the probability of repetitive binding of ACh molecules which leads to EPC prolongation. The shortening which persists after complete recovery of the amplitude during wash-out of the exogenous agonist is probably due to 'trapping' of ACh molecules onto rapidly desensitized receptors and the reduced density of functional AChRs during the quantum action.

Distribution patterns of zoochlorellae and zooxanthellae hosted by two Pacific Northeast anemones, Anthopleura elegantissima and A. xanthogrammica.

PubMed

Bates, Amanda E; McLean, Lily; Laing, Patrick; Raeburn, Lisa A; Hare, Crystal

2010-06-01

This study investigated patterns in the relative abundance of two photosynthetic algal symbionts, zoochlorellae (ZC) and zooxanthellae (ZX), hosted by two temperate anemones, Anthopleura elegantissima and A. xanthogrammica. Previous studies have documented varying proportions of each symbiont along environmental gradients, presumably determined by their respective physiological capabilities. To test for differences in the algal type between the two host species, we sampled anemone tissues (tentacle or tentacle and body column) of similarly sized polyps that were located close together in multiple habitats: tidepools, crevices, underneath rock ledges, and along natural light gradients in caves. The ZC-A. elegantissima symbiosis was rare on the west coast of Vancouver Island, British Columbia, Canada. Even in low-irradiance habitats, ZC were the dominant algae hosted by A. xanthogrammica, while nearby A. elegantissima hosted ZX or was algae-free. As a first step in determining whether symbiont growth rates differed between the two host species, we quantified mitotic index (MI), the percentage of cells with division furrows, under artificial light and in the field by simultaneously sampling tentacles from both species. MI was more stable in A. elegantissima: the MI of ZX isolated from the tentacles of A. xanthogrammica was slightly higher at a light level of 80 micromol quanta m(-2) s(-1) than it was for ZX from A. elegantissima (respectively, 7.3 vs. 6.2) and relatively lower at 40 micromol quanta m(-2) s(-1) (3.9 vs. 5.6). Our data indicate host-specific differences in symbiont distributions and MI when extrinsic physical parameters were similar.

Comparison of enzyme-linked immunosorbent assay and rapid chemiluminescent analyser in the detection of myeloperoxidase and proteinase 3 autoantibodies.

PubMed

Pucar, Phillippa A; Hawkins, Carolyn A; Randall, Katrina L; Li, Candice; McNaughton, Euan; Cook, Matthew C

2017-06-01

Antibodies to myeloperoxidase (MPO) and proteinase 3 (PR3) are vital in the diagnosis and management of ANCA-associated vasculitis. A chemiluminescent immunoassay (CLIA; Quanta Flash) provides MPO and PR3 antibody results in 30 minutes, which is much faster than enzyme-linked immunosorbent assay (ELISA). We compared the performance of ELISA (Orgentec) and CLIA (Quanta Flash) for MPO and PR3 antibody quantitation on 303 samples, comprising 196 consecutive samples received in a single diagnostic laboratory over a 3 month period, and 107 samples collected from 42 known vasculitis patients over a 40 month period. We observed a correlation between both methods using spearman correlation coefficients (MPO, r s  = 0.63, p < 0.01; PR3, r s  = 0.69, p < 0.01). There was agreement between both methods in determining a positive or negative result. In the vasculitis cohort, CLIA performed well at clinically important stages of disease; diagnosis (eight samples all positive by both assays) and disease relapse (correlation for both MPO and PR3 antibody quantitation r s  = 0.84, p = 0.03 and r s  = 0.78, p < 0.01, respectively). Three samples were discordant at clinical relapse, testing positive by CLIA, including one high positive associated with relapse requiring a change in treatment. In summary, CLIA appears to be at least as accurate as ELISA for measurement of MPO and PR3 antibodies. Copyright © 2017. Published by Elsevier B.V.

Quantization of spinor fields. III. Fermions on coherent (Bose) domains

NASA Astrophysics Data System (ADS)

Garbaczewski, Piotr

1983-02-01

A formulation of the c-number classics-quanta correspondence rule for spinor systems requires all elements of the quantum field algebra to be expanded into power series with respect to the generators of the canonical commutation relation (CCR) algebra. On the other hand, the asymptotic completeness demand would result in the (Haag) expansions with respect to the canonical anticommutation relation (CAR) generators. We establish the conditions under which the above correspondence rule can be reconciled with the existence of Haag expansions in terms of asymptotic free Fermi fields. Then, the CAR become represented on the state space of the Bose (CCR) system.

Multiple nucleon knockout by Coulomb dissociation in relativistic heavy-ion collisions

NASA Technical Reports Server (NTRS)

Cucinotta, Francis A.; Norbury, John W.; Townsend, Lawrence W.

1988-01-01

The Coulomb dissociation contributions to fragmentation cross sections in relativistic heavy ion collisions, where more than one nucleon is removed, are estimated using the Weizsacker-Williams method of virtual quanta. Photonuclear cross sections taken from experimental results were used to fold into target photon number spectra calculated with the Weizsacker-Williams method. Calculations for several projectile target combinations over a wide range of charge numbers, and a wide range of incident projectile energies, are reported. These results suggest that multiple nucleon knockout by the Coulomb field may be of negligible importance in galactic heavy ion studies for projectiles lighter than Fe-56.

Calculation of the Coulomb Fission Cross Sections for Pb-Pb and Bi-Pb Interactions at 158 A GeV

NASA Technical Reports Server (NTRS)

Poyser, William J.; Ahern, Sean C.; Norbury, John W.; Tripathi, R. K.

2002-01-01

The Weizsacker-Williams (WW) method of virtual quanta is used to make approximate cross section calculations for peripheral relativistic heavy-ion collisions. We calculated the Coulomb fission cross sections for projectile ions of Pb-208 and Bi-209 with energies of 158 A GeV interacting with a Pb-208 target. We also calculated the electromagnetic absorption cross section for Pb-208 ion interacting as described. For comparison we use both the full WW method and a standard approximate WW method. The approximate WW method in larger cross sections compared to the more accurate full WW method.

Einstein-Podolsky-Rosen-Bohm experiment and Bell inequality violation using Type 2 parametric down conversion

NASA Technical Reports Server (NTRS)

Kiess, Thomas E.; Shih, Yan-Hua; Sergienko, A. V.; Alley, Carroll O.

1994-01-01

We report a new two-photon polarization correlation experiment for realizing the Einstein-Podolsky-Rosen-Bohm (EPRB) state and for testing Bell-type inequalities. We use the pair of orthogonally-polarized light quanta generated in Type 2 parametric down conversion. Using 1 nm interference filters in front of our detectors, we observe from the output of a 0.5mm beta - BaB2O4 (BBO) crystal the EPRB correlations in coincidence counts, and measure an associated Bell inequality violation of 22 standard deviations. The quantum state of the photon pair is a polarization analog of the spin-1/2 singlet state.

Multifluxon dynamics in driven Josephson junctions

NASA Astrophysics Data System (ADS)

Lawrence, Albert; Kim, Nung Soo; McDaniel, James; Jack, Michael

1985-06-01

The dynamics of fluxons in a long Josephson junction driven by time-varying nonuniform bias currents are described by a generalization of the sine-Gordon equation. This equation has solitary wave solutions which correspond to current vortices or quantized packets of magnetic flux in the junction. As with the sine-Gordon equation, multifluxon solutions may be demonstrated for the long Josephson junction. Our numerical calculations show that several fluxons may be launched or annihilated at the end of a junction. We also show multiple steady state conditions which correspond to one or more flux quanta trapped in the junction.

Higher Dimensional Spacetimes for Visualizing and Modeling Subluminal, Luminal and Superluminal Flight

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

Froning, H. David; Meholic, Gregory V.

2010-01-28

This paper briefly explores higher dimensional spacetimes that extend Meholic's visualizable, fluidic views of: subluminal-luminal-superluminal flight; gravity, inertia, light quanta, and electromagnetism from 2-D to 3-D representations. Although 3-D representations have the potential to better model features of Meholic's most fundamental entities (Transluminal Energy Quantum) and of the zero-point quantum vacuum that pervades all space, the more complex 3-D representations loose some of the clarity of Meholic's 2-D representations of subluminal and superlumimal realms. So, much new work would be needed to replace Meholic's 2-D views of reality with 3-D ones.

Direct stimulation of the retina by the method of virtual-quanta for heavy cosmic-ray nuclei

NASA Technical Reports Server (NTRS)

Mcnulty, P. J.; Madey, R.

1972-01-01

The contribution to the frequency of visual sensations induced in the dark-adapted eye by the virtual photon field was calculated, this field is associated with the heavy nuclei that exist in space beyond the geomagnetic field. In order to determine the probability that the virtual photon field induces a light flash, only the portion of the virtual photon spectrum that corresponds to the known frequency dependence of the sensitivity of human rods to visible light was utilized. The results can be expressed as a curve of the mean frequency of light flashes induced by the absorption of at least R virtual photons versus the threshold number R. The contribution to the light flash frequency from the virtual photon field of heavy cosmic ray nuclei is smaller than that from Cerenkov photons. The flux and energy spectra of galactic cosmic ray nuclei helium to iron were used.

Prevalence of anti-DFS70 antibodies in patients with and without systemic autoimmune rheumatic diseases.

PubMed

Shovman, Ora; Gilburd, Boris; Chayat, Chen; Amital, Howard; Langevitz, Pnina; Watad, Abdulla; Guy, Adi; Perez, Dolores; Azoulay, Danielle; Blank, Miri; Segal, Yael; Bentow, Chelsea; Mahler, Michael; Shoenfeld, Yehuda

2018-01-01

Autoantibodies to the dense fine speckled 70 (DFS70) antigen are common among antinuclear antibodies (ANA) positive healthy individuals (HI). We assessed the prevalence of anti-DFS70 antibodies in patients with and without ANA-associated rheumatic diseases (AARDs) by two methods: chemiluminescent immunoassay (CIA) and an indirect immunofluorescence (IIF) assay based on immunoadsorption for DFS70. Fifty-one ANA-positive sera samples from patients with confirmed clinical diagnosis of AARD, 92 samples from HI and 85 samples submitted to a reference laboratory for routine ANA testing were evaluated for the presence of anti-DFS70 antibodies. The samples were evaluated by QUANTA Flash DFS70 CIA using BIO-FLASH instrument and by NOVA Lite selected HEp-2 kit on NOVA View - an automated IIF system. Sera with DFS positive pattern were pre-absorbed with highly purified human DFS70 antigen, and then tested again. Twenty-four samples (10.5%) tested by QUANTA Flash DFS70 CIA were positive for anti-DFS70 antibodies. The prevalence of monospecific anti-DFS70 antibodies was significantly higher in healthy subjects than in patients with AARDs (10.9% vs. 1.9%, p=0.02). The frequency of anti-DFS70 antibodies in samples submitted for routine ANA testing was 15.2%. A very good agreement was found between CIA and the DFS pattern identified by the automated HEp-2 IIF (kappa=0.97). In 80% of the samples obtained from patients without AARDs, immunoadsorption effectively inhibited the anti-DFS70 antibodies. The data confirm that mono-specific anti-DFS70 antibodies are a strong discriminator between ANA positive HI and AARD patients, and their evaluation should be included in ANA testing algorithms.

Mechanisms underlying the influence of saliency on value-based decisions

PubMed Central

Chen, Xiaomo; Mihalas, Stefan; Niebur, Ernst; Stuphorn, Veit

2013-01-01

Objects in the environment differ in their low-level perceptual properties (e.g., how easily a fruit can be recognized) as well as in their subjective value (how tasty it is). We studied the influence of visual salience on value-based decisions using a two alternative forced choice task, in which human subjects rapidly chose items from a visual display. All targets were equally easy to detect. Nevertheless, both value and salience strongly affected choices made and reaction times. We analyzed the neuronal mechanisms underlying these behavioral effects using stochastic accumulator models, allowing us to characterize not only the averages of reaction times but their full distributions. Independent models without interaction between the possible choices failed to reproduce the observed choice behavior, while models with mutual inhibition between alternative choices produced much better results. Mutual inhibition thus is an important feature of the decision mechanism. Value influenced the amount of accumulation in all models. In contrast, increased salience could either lead to an earlier start (onset model) or to a higher rate (speed model) of accumulation. Both models explained the data from the choice trials equally well. However, salience also affected reaction times in no-choice trials in which only one item was present, as well as error trials. Only the onset model could explain the observed reaction time distributions of error trials and no-choice trials. In contrast, the speed model could not, irrespective of whether the rate increase resulted from more frequent accumulated quanta or from larger quanta. Visual salience thus likely provides an advantage in the onset, not in the processing speed, of value-based decision making. PMID:24167161

Detective quantum efficiency of photon-counting x-ray detectors.

PubMed

Tanguay, Jesse; Yun, Seungman; Kim, Ho Kyung; Cunningham, Ian A

2015-01-01

Single-photon-counting (SPC) x-ray imaging has the potential to improve image quality and enable novel energy-dependent imaging methods. Similar to conventional detectors, optimizing image SPC quality will require systems that produce the highest possible detective quantum efficiency (DQE). This paper builds on the cascaded-systems analysis (CSA) framework to develop a comprehensive description of the DQE of SPC detectors that implement adaptive binning. The DQE of SPC systems can be described using the CSA approach by propagating the probability density function (PDF) of the number of image-forming quanta through simple quantum processes. New relationships are developed to describe PDF transfer through serial and parallel cascades to accommodate scatter reabsorption. Results are applied to hypothetical silicon and selenium-based flat-panel SPC detectors including the effects of reabsorption of characteristic/scatter photons from photoelectric and Compton interactions, stochastic conversion of x-ray energy to secondary quanta, depth-dependent charge collection, and electronic noise. Results are compared with a Monte Carlo study. Depth-dependent collection efficiency can result in substantial broadening of photopeaks that in turn may result in reduced DQE at lower x-ray energies (20-45 keV). Double-counting interaction events caused by reabsorption of characteristic/scatter photons may result in falsely inflated image signal-to-noise ratio and potential overestimation of the DQE. The CSA approach is extended to describe signal and noise propagation through photoelectric and Compton interactions in SPC detectors, including the effects of escape and reabsorption of emission/scatter photons. High-performance SPC systems can be achieved but only for certain combinations of secondary conversion gain, depth-dependent collection efficiency, electronic noise, and reabsorption characteristics.

Black holes and beyond

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

Mathur, Samir D., E-mail: mathur.16@osu.edu

The black hole information paradox forces us into a strange situation: we must find a way to break the semiclassical approximation in a domain where no quantum gravity effects would normally be expected. Traditional quantizations of gravity do not exhibit any such breakdown, and this forces us into a difficult corner: either we must give up quantum mechanics or we must accept the existence of troublesome 'remnants'. In string theory, however, the fundamental quanta are extended objects, and it turns out that the bound states of such objects acquire a size that grows with the number of quanta in themore » bound state. The interior of the black hole gets completely altered to a 'fuzzball' structure, and information is able to escape in radiation from the hole. The semiclassical approximation can break at macroscopic scales due to the large entropy of the hole: the measure in the path integral competes with the classical action, instead of giving a subleading correction. Putting this picture of black hole microstates together with ideas about entangled states leads to a natural set of conjectures on many long-standing questions in gravity: the significance of Rindler and de Sitter entropies, the notion of black hole complementarity, and the fate of an observer falling into a black hole. - Highlights: Black-Right-Pointing-Pointer The information paradox is a serious problem. Black-Right-Pointing-Pointer To solve it we need to find 'hair' on black holes. Black-Right-Pointing-Pointer In string theory we find 'hair' by the fuzzball construction. Black-Right-Pointing-Pointer Fuzzballs help to resolve many other issues in gravity.« less

The physics of time and the arrow thereof

NASA Astrophysics Data System (ADS)

Hecht, Eugene

2018-01-01

Although the physics of time is of fundamental importance, the concept gets little attention in most introductory courses. Still, we now know enough to begin to formulate a coherent account of the physical nature of time. Newton’s absolute time has given way to Leibniz’s relational time. From Relativity Theory we learn that time in addition to being relational is also relative, and local; as we will see, the rates at which events unfold are influenced by both the relative velocity of the observer, and the local gravitational field strength—time is not universal. The intrinsic relationship between light-speed and time will be examined via relativity. Moreover, it will be shown that the Special Theory requires that the quanta of the electromagnetic field (i.e. photons), only exist at speed c; the ramifications of that extraordinary property, coupled with conservation of energy, profoundly influence the progression of time. Time in our everyday lives is the abstract measure of the unfolding of macroscopic occurrences, all of which are irreversible. It is posited that these events are irreversible because they are invariably accompanied by the emission of radiant energy, photons and/or gravitons. By contrast, entropy is a descriptor of processes, it is not a causative agency; although correlated with the so-called arrow-of-time, it cannot be its cause. Using a variety of physical thought experiments, it will be shown that the unidirectional ‘flow’ of time, the arrow-of-time, is a result of the fact that energy quanta only travel toward the future. That is the fundamental asymmetry in our otherwise temporally symmetric physics.

Light Dependence of [3H]Leucine Incorporation in the Oligotrophic North Pacific Ocean†

PubMed Central

Church, Matthew J.; Ducklow, Hugh W.; Karl, David M.

2004-01-01

The influence of irradiance on bacterial incorporation of [3H]leucine was evaluated at Station ALOHA in the oligotrophic North Pacific subtropical gyre. Six experiments were conducted on three cruises to Station ALOHA to examine how [3H]leucine incorporation varied as a function of irradiance. Two experiments were also conducted to assess the photoautotrophic response to irradiance (based on photosynthetic uptake of [14C]bicarbonate) in both the upper and lower photic zones. Rates of [3H]leucine incorporation responded to irradiance in a photosynthesis-like manner, increasing sharply at low light and then saturating and sometimes declining with increasing light intensity. The influence of irradiance on bacterial growth was evaluated in both the well-lit (5 to 25 m) and dimly lit regions of the upper ocean (75 to 100 m) to determine whether the bacterial response to irradiance differed along the depth-dependent light gradient of the photic zone. [3H]leucine incorporation rates were analyzed with a photosynthesis-irradiance model for a quantitative description of the relationships between [3H]leucine incorporation and irradiance. Maximum rates of [3H]leucine incorporation in the upper photic zone increased 48 to 92% relative to those of dark-incubated samples, with [3H]leucine incorporation saturating at light intensities between 58 and 363 μmol of quanta m−2 s−1. Rates of [3H]leucine incorporation in the deep photic zone were photostimulated 53 to 114% and were susceptible to photoinhibition, with rates declining at light intensities of >100 μmol of quanta m−2 s−1. The results of these experiments revealed that sunlight directly influences bacterial growth in this open-ocean ecosystem. PMID:15240286

GEMS (Gravity Electro-Magnetism Strong) SU(5) Theory and The Prediction of Exchange Boson Masses

NASA Astrophysics Data System (ADS)

Brandenburg, John

2012-10-01

The GEMS SU(5) [1] theory includes short range Nuclear Forces in the GEM unification theory [2], where the importance of the square root of the proton-electron mass ratio: σ = 42.8503 was found. The creation of mass by a Higgs field coupling must, by the Equivalence Principle, be viewed in the context of General Relativity. This is done here using Kaluza-Klein theory in a Feynman-Hawkings path integral formalism. GEM theory, quantum concepts of virtual particles, and ZPF (Zero Point Fluctuation) allow understanding of the Strong Force and Weak forces as the extension of electrodynamics in the quantum limit. The Strong and Weak forces are found to be associated with EM models of the electron and proton as finite sized structures respectively. Higher order Mie resonances off the EM ``mass at a distance'' structures associated with the electron, proton and fifth dimension generate the quanta with masses of the pion mπ = 2 me /α 140.0 MeV and Z boson: mZ = 2σ mp = 80.4 GeV. The ηc meson mη = 2980 GeV is identified with the 5^th dimension compactification force mediated by the Radion field. Another particle associated with this mass inducing field is the ``Radion'' or Higgs scattering quanta off the fifth dimension with a mass σmη 128.6 GeV which is the Higgs Boson. A GEMS SU(5) Georgi-Glashow model, is proposed, where the unification energy is now the Planck energy.[0pt] [1] Brandenburg, J.E. (2012)., STAIF II Conference Albuquerque NM[0pt] [2] Brandenburg, J.E. (2007). IEEE Transactions On Plasma Science, Vol. 35, No. 4., p845.

Zn2+ at a cellular crossroads

PubMed Central

Liang, Xiaomeng; Dempski, Robert E.; Burdette, Shawn C.

2016-01-01

Zinc is an essential micronutrient for cellular homeostasis. Initially proposed to only contribute to cellular viability through structural roles and non-redox catalysis, advances in quantifying changes in nM and pM quantities of Zn2+ have elucidated increasing functions as an important signaling molecule. This includes Zn2+-mediated regulation of transcription factors and subsequent protein expression, storage and release of intracellular compartments of zinc quanta into the extracellular space which modulates plasma membrane protein function, as well as intracellular signaling pathways which contribute to the immune response. This review highlights some recent advances in our understanding of zinc signaling. PMID:27010344

Insensitivity of Hawking radiation to an invariant Planck-scale cutoff

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

Agullo, Ivan; Departamento de Fisica Teorica and IFIC, Centro Mixto Universidad de Valencia-CSIC, Facultad de Fisica, Universidad de Valencia, Burjassot-46100, Valencia; Navarro-Salas, Jose

2009-08-15

A disturbing aspect of Hawking's derivation of black hole radiance is the need to invoke extreme conditions for the quantum field that originates the emitted quanta. It is widely argued that the derivation requires the validity of the conventional relativistic field theory to arbitrarily high, trans-Planckian scales. We stress in this note that this is not necessarily the case if the question is presented in a covariant way. We point out that Hawking radiation is immediately robust against an invariant Planck-scale cutoff. This important feature of Hawking radiation is relevant for a quantum gravity theory that preserves, in some way,more » the Lorentz symmetry.« less

Single Photon Counting Performance and Noise Analysis of CMOS SPAD-Based Image Sensors.

PubMed

Dutton, Neale A W; Gyongy, Istvan; Parmesan, Luca; Henderson, Robert K

2016-07-20

SPAD-based solid state CMOS image sensors utilising analogue integrators have attained deep sub-electron read noise (DSERN) permitting single photon counting (SPC) imaging. A new method is proposed to determine the read noise in DSERN image sensors by evaluating the peak separation and width (PSW) of single photon peaks in a photon counting histogram (PCH). The technique is used to identify and analyse cumulative noise in analogue integrating SPC SPAD-based pixels. The DSERN of our SPAD image sensor is exploited to confirm recent multi-photon threshold quanta image sensor (QIS) theory. Finally, various single and multiple photon spatio-temporal oversampling techniques are reviewed.

Single Photon Counting Performance and Noise Analysis of CMOS SPAD-Based Image Sensors

PubMed Central

Dutton, Neale A. W.; Gyongy, Istvan; Parmesan, Luca; Henderson, Robert K.

2016-01-01

SPAD-based solid state CMOS image sensors utilising analogue integrators have attained deep sub-electron read noise (DSERN) permitting single photon counting (SPC) imaging. A new method is proposed to determine the read noise in DSERN image sensors by evaluating the peak separation and width (PSW) of single photon peaks in a photon counting histogram (PCH). The technique is used to identify and analyse cumulative noise in analogue integrating SPC SPAD-based pixels. The DSERN of our SPAD image sensor is exploited to confirm recent multi-photon threshold quanta image sensor (QIS) theory. Finally, various single and multiple photon spatio-temporal oversampling techniques are reviewed. PMID:27447643

Improvement of the Davydov theory of bioenergy transport in protein molecular systems.

PubMed

Pang, X F

2000-11-01

The Hamiltonian and the wave function in the Davydov theory have simultaneously been improved and extended, based on some physical and biological grounds and on results from other models. The equations of motion for the improved Davydov model with a quasicoherent two-quanta state and a new interaction term in the Hamiltonian describe bioenergy transport along the molecular chains in protein molecules by a soliton mechanism. Some elementary properties of the soliton, including the nonlinear coupling energy and greatly increased binding energy of the soliton, are also given. The results obtained suggest that the model could be a candidate for a bioenergy transport mechanism in protein molecules.

Proposed entanglement of X-ray nuclear polaritons as a potential method for probing matter at the subatomic scale.

PubMed

Liao, Wen-Te; Pálffy, Adriana

2014-02-07

A setup for generating the special superposition of a simultaneously forward- and backward-propagating collective excitation in a nuclear sample is studied. We show that by actively manipulating the scattering channels of single x-ray quanta with the help of a normal incidence x-ray mirror, a nuclear polariton which propagates in two opposite directions can be generated. The two counterpropagating polariton branches are entangled by a single x-ray photon. The quantum nature of the nuclear excitation entanglement gives rise to a subangstrom-wavelength standing wave excitation pattern that can be used as a flexible tool to probe matter dynamically on the subatomic scale.

In search of the black swans

NASA Astrophysics Data System (ADS)

Buchanan, Mark

2009-04-01

In 1890 an electricity company enticed the German physicist Max Planck to help it in its efforts to make more efficient light bulbs. Planck, as a theorist, naturally started with the fundamentals and soon became enmeshed in the thorny problem of explaining the spectrum of black-body radiation, which he eventually did by introducing the idea - a "purely formal" assumption, as he then considered it - that electromagnetic energy can only be emitted or absorbed in discrete quanta. The rest is history. Electric light bulbs and mathematical necessity led Planck to discover quantum theory and to kick start the most significant scientific revolution of the 20th century.

Classical Physics and the Bounds of Quantum Correlations.

PubMed

Frustaglia, Diego; Baltanás, José P; Velázquez-Ahumada, María C; Fernández-Prieto, Armando; Lujambio, Aintzane; Losada, Vicente; Freire, Manuel J; Cabello, Adán

2016-06-24

A unifying principle explaining the numerical bounds of quantum correlations remains elusive, despite the efforts devoted to identifying it. Here, we show that these bounds are indeed not exclusive to quantum theory: for any abstract correlation scenario with compatible measurements, models based on classical waves produce probability distributions indistinguishable from those of quantum theory and, therefore, share the same bounds. We demonstrate this finding by implementing classical microwaves that propagate along meter-size transmission-line circuits and reproduce the probabilities of three emblematic quantum experiments. Our results show that the "quantum" bounds would also occur in a classical universe without quanta. The implications of this observation are discussed.

Mesoscopic Dynamical Differences from Quantum State Preparation in a Bose-Hubbard Trimer

NASA Astrophysics Data System (ADS)

Olsen, M. K.; Neely, T. W.; Bradley, A. S.

2018-06-01

Conventional wisdom is that quantum effects will tend to disappear as the number of quanta in a system increases, and the evolution of a system will become closer to that described by mean-field classical equations. In this Letter we combine newly developed theoretical and experimental techniques to propose and analyze an experiment using a Bose-Hubbard trimer where the opposite is the case. We find that differences in the preparation of a centrally evacuated trimer can lead to readily observable differences in the subsequent dynamics which increase with system size. Importantly, these differences can be detected by the simple measurements of atomic number.

THE QUANTIC AND STATISTICAL BASES OF VISUAL EXCITATION

PubMed Central

Baumgardt, Ernest L. M.

1948-01-01

1. The photochemical theories of vision cannot provide a valid interpretation of the facts over the whole range of brightness. The fact that liminal excitation is increased by the absorption of a very small number of quanta, each absorbing rod receiving a single quantum, excludes the intervention of the mass action law which is the basis of all photochemical theories. 2. Owing to the quantic structure of light and to the random distribution of quanta in a faint light pencil, there must exist numerical relations between the threshold energy on the one hand and the size of the retinal area stimulated and the stimulation time on the other, whatever may be the inner mechanism of liminal excitation. When taking as a basis Van der Velden's experimental results, viz. that two quanta absorbed during a certain interval of time are sufficient to raise threshold excitation, the probability calculus enables us to compute the course of threshold energy in relation to the stimulation time and to the stimulated retinal area. No arbitrary parameter is needed to do so; the only constant to be used is found by experiment. 3. The quantic and statistical theory of visual excitation that we put forward in the present paper enables us to predict the validity of Ricco's law within what we call a "quasi-independent unit" and the validity of Piper's law within a test area made up of a certain number of such units. This theory does not correspond exactly with Piéron's law for foveal threshold in relation to the size of the stimulated area, but the deviation is probably due to an artefact; viz., the action of the micronystagmus. 4. Experiment proves that in region IV of the retina, 15° temporally from the fovea of the right eye of two observers, Ricco's law applies strictly in rod vision from 2'12'' to 31'36'' and, perhaps, further on. 5. In the same region, from 12'30'' to 31'36'', Piper's law applies strictly in cone vision of extremely red light. 6. In peripheral vision with extremely

Application of TQSM polypharmacokinetics and its similarity approach to ascertain Q-marker by analyses of transitivity in vivo of five candidates in Buyanghuanwu injection.

PubMed

Zhang, Yu-Tian; Xiao, Mei-Feng; Liao, Qiong; Liu, Wen-Long; Deng, Kai-Wen; Zhou, Yi-Qun; Tang, Yu; He, Fu-Yuan; Yang, Yan-Tao

2018-03-07

It is well-known that the public still have been facing on a severe issue about the inconsistency of quality and therapeutic efficacy of traditional medicines. Recently, Professor Chang-Xiao Liu has created a new promising concept for identifying relevant quality-markers (Q-marker) from herbs, their formulas and manufacturing products. Therefore, building up a new approach is necessary for us to bridge over quality to efficacy of pharmaceutical products. In this paper, five candidate Q-markers, astragaloside IV, paeonflorin, amygdalin, tetramethylpyrazine, ferulic acid in Buyanghuanwu injection (BYHWI) had been designed to carry out in rat by using single and polypharmacokinetic models for total quanta to ascertain adequate Q-marker. The Q-marker transitivity in vivo was studied with polypharmacokinetic model and its similarity approach, which were modeled with TQSM principle. The Q-marker was ascertained with transitive similarity and bioavailability in polypharmacokinetics. Their concentrations in plasma sample of white rat were determined by RP-HPLC. Data analyses were used by the DAS software for singles and myself-written-program with EXCEL for multiples. In BYHWI, five candidate Q-marker pharmacokinetic profiles were singly fixed to two compartmental models in rat using classical compartmental analysis, but there were tremendous differences among which the candidate parameters were fluctuated from nearly 3552 folds to equivalency. The theoretical value of TQSM polypharmacokinetic parameters such as AUC T , MRT T , VRT T , CL T , V T over the mixure of five drugs were 110.8 ± 51.91 mg min ml -1 , 176.0 ± 36.5 min, 39,921 ± 4311 min 2 , 0.3116 ± 0.02347 ml min -1  kg -1 , 54.83 ± 7.683 ml kg -1 respectively. The TQSM polypharmacokinetic parameters in astragaloside Ⅳ ordered by AUC T , MRT T , VRT T , CL T , V T were 110.8 ± 51.91 mg min ml -1 , 176.0 ± 36.5 min, 39,921 ± 4311 min 2 , 0.3116�

Photoacclimation of Prochlorococcus sp. (Prochlorophyta) Strains Isolated from the North Atlantic and the Mediterranean Sea.

PubMed Central

Partensky, F.; Hoepffner, N.; Li, WKW.; Ulloa, O.; Vaulot, D.

1993-01-01

Two Atlantic (SARG and NATL1) strains and one Mediterranean (MED) strain of Prochlorococcus sp., a recently discovered marine, free-living prochlorophyte, were grown over a range of "white" irradiances (lg) and under low blue light to examine their photoacclimation capacity. All three strains contained divinyl (DV) chlorophylls (Chl) a and b, both distinguishable from "normal" Chls by their red-shifted blue absorption maximum, a Chl c-like pigment at low concentration, zeaxanthin, and [alpha]-carotene. The presence of two phaeophytin b peaks in acidified extracts from both Atlantic strains grown at high lg suggests that these strains also had a normal Chl b-like pigment. In these strains, the total Chl b to DV-Chl a molar ratio decreased from about 1 at 7.5 [mu]mol quanta m-2 s-1 to 0.4 to 0.5 at 133 [mu]mol quanta m-2 s-1. In contrast, the MED strain always had a low DV-Chl b to DV-Chl a molar ratio, ranging between 0.13 at low lg and 0.08 at high lg. The discrepancies between the Atlantic and MED strains could result from differences either in the number of light-harvesting complexes (LHC) II per photosystem II or in the Chl b-binding capacity of the apoproteins constituting LHC II. Photosynthesis was saturated at approximately 5 fg C(fg Chl)-1 h-1 or 6 fg C cell-1 h-1, and growth was saturated at approximately 0.45 d-1 for both MED and SARG strains at 18[deg]C, but saturating irradiances differed between strains. Atlantic strains exhibited increased light-saturated rates and quantum yield for carbon fixation under blue light. PMID:12231684

Simultaneous quantum yield measurements of carbon uptake and oxygen evolution in microalgal cultures

PubMed Central

Gholami, Pardis; Kline, David I.; DuPont, Christopher L.; Dickson, Andrew G.; Mendola, Dominick; Martz, Todd; Allen, Andrew E.; Mitchell, B. Greg

2018-01-01

The photosynthetic quantum yield (Φ), defined as carbon fixed or oxygen evolved per unit of light absorbed, is a fundamental but rarely determined biophysical parameter. A method to estimate Φ for both net carbon uptake and net oxygen evolution simultaneously can provide important insights into energy and mass fluxes. Here we present details for a novel system that allows quantification of carbon fluxes using pH oscillation and simultaneous oxygen fluxes by integration with a membrane inlet mass spectrometer. The pHOS system was validated using Phaeodactylum tricornutum cultured with continuous illumination of 110 μmole quanta m-2 s-1 at 25°C. Furthermore, simultaneous measurements of carbon and oxygen flux using the pHOS-MIMS and photon flux based on spectral absorption were carried out to explore the kinetics of Φ in P. tricornutum during its acclimation from low to high light (110 to 750 μmole quanta m-2 s-1). Comparing results at 0 and 24 hours, we observed strong decreases in cellular chlorophyll a (0.58 to 0.21 pg cell-1), Fv/Fm (0.71 to 0.59) and maximum ΦCO2 (0.019 to 0.004) and ΦO2 (0.028 to 0.007), confirming the transition toward high light acclimation. The Φ time-series indicated a non-synchronized acclimation response between carbon uptake and oxygen evolution, which has been previously inferred based on transcriptomic changes for a similar experimental design with the same diatom that lacked physiological data. The integrated pHOS-MIMS system can provide simultaneous carbon and oxygen measurements accurately, and at the time-resolution required to resolve high-resolution carbon and oxygen physiological dynamics. PMID:29920568

Time resolution of the plastic scintillator strips with matrix photomultiplier readout for J-PET tomograph.

PubMed

Moskal, P; Rundel, O; Alfs, D; Bednarski, T; Białas, P; Czerwiński, E; Gajos, A; Giergiel, K; Gorgol, M; Jasińska, B; Kamińska, D; Kapłon, Ł; Korcyl, G; Kowalski, P; Kozik, T; Krzemień, W; Kubicz, E; Niedźwiecki, Sz; Pałka, M; Raczyński, L; Rudy, Z; Sharma, N G; Słomski, A; Silarski, M; Strzelecki, A; Wieczorek, A; Wiślicki, W; Witkowski, P; Zieliński, M; Zoń, N

2016-03-07

Recent tests of a single module of the Jagiellonian Positron Emission Tomography system (J-PET) consisting of 30 cm long plastic scintillator strips have proven its applicability for the detection of annihilation quanta (0.511 MeV) with a coincidence resolving time (CRT) of 0.266 ns. The achieved resolution is almost by a factor of two better with respect to the current TOF-PET detectors and it can still be improved since, as it is shown in this article, the intrinsic limit of time resolution for the determination of time of the interaction of 0.511 MeV gamma quanta in plastic scintillators is much lower. As the major point of the article, a method allowing to record timestamps of several photons, at two ends of the scintillator strip, by means of matrix of silicon photomultipliers (SiPM) is introduced. As a result of simulations, conducted with the number of SiPM varying from 4 to 42, it is shown that the improvement of timing resolution saturates with the growing number of photomultipliers, and that the [Formula: see text] configuration at two ends allowing to read twenty timestamps, constitutes an optimal solution. The conducted simulations accounted for the emission time distribution, photon transport and absorption inside the scintillator, as well as quantum efficiency and transit time spread of photosensors, and were checked based on the experimental results. Application of the [Formula: see text] matrix of SiPM allows for achieving the coincidence resolving time in positron emission tomography of [Formula: see text]0.170 ns for 15 cm axial field-of-view (AFOV) and [Formula: see text]0.365 ns for 100 cm AFOV. The results open perspectives for construction of a cost-effective TOF-PET scanner with significantly better TOF resolution and larger AFOV with respect to the current TOF-PET modalities.

Detective quantum efficiency of photon-counting x-ray detectors

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

Tanguay, Jesse, E-mail: jessetan@mail.ubc.ca; Yun, Seungman; Kim, Ho Kyung

Purpose: Single-photon-counting (SPC) x-ray imaging has the potential to improve image quality and enable novel energy-dependent imaging methods. Similar to conventional detectors, optimizing image SPC quality will require systems that produce the highest possible detective quantum efficiency (DQE). This paper builds on the cascaded-systems analysis (CSA) framework to develop a comprehensive description of the DQE of SPC detectors that implement adaptive binning. Methods: The DQE of SPC systems can be described using the CSA approach by propagating the probability density function (PDF) of the number of image-forming quanta through simple quantum processes. New relationships are developed to describe PDF transfermore » through serial and parallel cascades to accommodate scatter reabsorption. Results are applied to hypothetical silicon and selenium-based flat-panel SPC detectors including the effects of reabsorption of characteristic/scatter photons from photoelectric and Compton interactions, stochastic conversion of x-ray energy to secondary quanta, depth-dependent charge collection, and electronic noise. Results are compared with a Monte Carlo study. Results: Depth-dependent collection efficiency can result in substantial broadening of photopeaks that in turn may result in reduced DQE at lower x-ray energies (20–45 keV). Double-counting interaction events caused by reabsorption of characteristic/scatter photons may result in falsely inflated image signal-to-noise ratio and potential overestimation of the DQE. Conclusions: The CSA approach is extended to describe signal and noise propagation through photoelectric and Compton interactions in SPC detectors, including the effects of escape and reabsorption of emission/scatter photons. High-performance SPC systems can be achieved but only for certain combinations of secondary conversion gain, depth-dependent collection efficiency, electronic noise, and reabsorption characteristics.« less

Superconductor Digital Electronics: -- Current Status, Future Prospects

NASA Astrophysics Data System (ADS)

Mukhanov, Oleg

2011-03-01

Two major applications of superconductor electronics: communications and supercomputing will be presented. These areas hold a significant promise of a large impact on electronics state-of-the-art for the defense and commercial markets stemming from the fundamental advantages of superconductivity: simultaneous high speed and low power, lossless interconnect, natural quantization, and high sensitivity. The availability of relatively small cryocoolers lowered the foremost market barrier for cryogenically-cooled superconductor electronic systems. These fundamental advantages enabled a novel Digital-RF architecture - a disruptive technological approach changing wireless communications, radar, and surveillance system architectures dramatically. Practical results were achieved for Digital-RF systems in which wide-band, multi-band radio frequency signals are directly digitized and digital domain is expanded throughout the entire system. Digital-RF systems combine digital and mixed signal integrated circuits based on Rapid Single Flux Quantum (RSFQ) technology, superconductor analog filter circuits, and semiconductor post-processing circuits. The demonstrated cryocooled Digital-RF systems are the world's first and fastest directly digitizing receivers operating with live satellite signals, enabling multi-net data links, and performing signal acquisition from HF to L-band with 30 GHz clock frequencies. In supercomputing, superconductivity leads to the highest energy efficiencies per operation. Superconductor technology based on manipulation and ballistic transfer of magnetic flux quanta provides a superior low-power alternative to CMOS and other charge-transfer based device technologies. The fundamental energy consumption in SFQ circuits defined by flux quanta energy 2 x 10-19 J. Recently, a novel energy-efficient zero-static-power SFQ technology, eSFQ/ERSFQ was invented, which retains all advantages of standard RSFQ circuits: high-speed, dc power, internal memory. The

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.

Time resolution of the plastic scintillator strips with matrix photomultiplier readout for J-PET tomograph

NASA Astrophysics Data System (ADS)

Moskal, P.; Rundel, O.; Alfs, D.; Bednarski, T.; Białas, P.; Czerwiński, E.; Gajos, A.; Giergiel, K.; Gorgol, M.; Jasińska, B.; Kamińska, D.; Kapłon, Ł.; Korcyl, G.; Kowalski, P.; Kozik, T.; Krzemień, W.; Kubicz, E.; Niedźwiecki, Sz; Pałka, M.; Raczyński, L.; Rudy, Z.; Sharma, N. G.; Słomski, A.; Silarski, M.; Strzelecki, A.; Wieczorek, A.; Wiślicki, W.; Witkowski, P.; Zieliński, M.; Zoń, N.

2016-03-01

Recent tests of a single module of the Jagiellonian Positron Emission Tomography system (J-PET) consisting of 30 cm long plastic scintillator strips have proven its applicability for the detection of annihilation quanta (0.511 MeV) with a coincidence resolving time (CRT) of 0.266 ns. The achieved resolution is almost by a factor of two better with respect to the current TOF-PET detectors and it can still be improved since, as it is shown in this article, the intrinsic limit of time resolution for the determination of time of the interaction of 0.511 MeV gamma quanta in plastic scintillators is much lower. As the major point of the article, a method allowing to record timestamps of several photons, at two ends of the scintillator strip, by means of matrix of silicon photomultipliers (SiPM) is introduced. As a result of simulations, conducted with the number of SiPM varying from 4 to 42, it is shown that the improvement of timing resolution saturates with the growing number of photomultipliers, and that the 2× 5 configuration at two ends allowing to read twenty timestamps, constitutes an optimal solution. The conducted simulations accounted for the emission time distribution, photon transport and absorption inside the scintillator, as well as quantum efficiency and transit time spread of photosensors, and were checked based on the experimental results. Application of the 2× 5 matrix of SiPM allows for achieving the coincidence resolving time in positron emission tomography of ≈ 0.170 ns for 15 cm axial field-of-view (AFOV) and ≈ 0.365 ns for 100 cm AFOV. The results open perspectives for construction of a cost-effective TOF-PET scanner with significantly better TOF resolution and larger AFOV with respect to the current TOF-PET modalities.

SU-E-T-236: Deconvolution of the Total Nuclear Cross-Sections of Therapeutic Protons and the Characterization of the Reaction Channels

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

Ulmer, W.

2015-06-15

Purpose: The knowledge of the total nuclear cross-section Qtot(E) of therapeutic protons Qtot(E) provides important information in advanced radiotherapy with protons, such as the decrease of fluence of primary protons, the release of secondary particles (neutrons, protons, deuterons, etc.), and the production of nuclear fragments (heavy recoils), which usually undergo β+/− decay by emission of γ-quanta. Therefore determination of Qtot(E) is an important tool for sophisticated calculation algorithms of dose distributions. This cross-section can be determined by a linear combination of shifted Gaussian kernels and an error-function. The resonances resulting from deconvolutions in the energy space can be associated withmore » typical nuclear reactions. Methods: The described method of the determination of Qtot(E) results from an extension of the Breit-Wigner formula and a rather extended version of the nuclear shell theory to include nuclear correlation effects, clusters and highly excited/virtually excited nuclear states. The elastic energy transfer of protons to nucleons (the quantum numbers of the target nucleus remain constant) can be removed by the mentioned deconvolution. Results: The deconvolution of the term related to the error-function of the type cerf*er((E-ETh)/σerf] is the main contribution to obtain various nuclear reactions as resonances, since the elastic part of energy transfer is removed. The nuclear products of various elements of therapeutic interest like oxygen, calcium are classified and calculated. Conclusions: The release of neutrons is completely underrated, in particular, for low-energy protons. The transport of seconary particles, e.g. cluster formation by deuterium, tritium and α-particles, show an essential contribution to secondary particles, and the heavy recoils, which create γ-quanta by decay reactions, lead to broadening of the scatter profiles. These contributions cannot be accounted for by one single Gaussian kernel for the

High-dynamic-range scene compression in humans

NASA Astrophysics Data System (ADS)

McCann, John J.

2006-02-01

Single pixel dynamic-range compression alters a particular input value to a unique output value - a look-up table. It is used in chemical and most digital photographic systems having S-shaped transforms to render high-range scenes onto low-range media. Post-receptor neural processing is spatial, as shown by the physiological experiments of Dowling, Barlow, Kuffler, and Hubel & Wiesel. Human vision does not render a particular receptor-quanta catch as a unique response. Instead, because of spatial processing, the response to a particular quanta catch can be any color. Visual response is scene dependent. Stockham proposed an approach to model human range compression using low-spatial frequency filters. Campbell, Ginsberg, Wilson, Watson, Daly and many others have developed spatial-frequency channel models. This paper describes experiments measuring the properties of desirable spatial-frequency filters for a variety of scenes. Given the radiances of each pixel in the scene and the observed appearances of objects in the image, one can calculate the visual mask for that individual image. Here, visual mask is the spatial pattern of changes made by the visual system in processing the input image. It is the spatial signature of human vision. Low-dynamic range images with many white areas need no spatial filtering. High-dynamic-range images with many blacks, or deep shadows, require strong spatial filtering. Sun on the right and shade on the left requires directional filters. These experiments show that variable scene- scenedependent filters are necessary to mimic human vision. Although spatial-frequency filters can model human dependent appearances, the problem still remains that an analysis of the scene is still needed to calculate the scene-dependent strengths of each of the filters for each frequency.

Electrical and thermal conductance quantization in nanostructures

NASA Astrophysics Data System (ADS)

Nawrocki, Waldemar

2008-10-01

In the paper problems of electron transport in mesoscopic structures and nanostructures are considered. The electrical conductance of nanowires was measured in a simple experimental system. Investigations have been performed in air at room temperature measuring the conductance between two vibrating metal wires with standard oscilloscope. Conductance quantization in units of G0 = 2e2/h = (12.9 kΩ)-1 up to five quanta of conductance has been observed for nanowires formed in many metals. The explanation of this universal phenomena is the formation of a nanometer-sized wire (nanowire) between macroscopic metallic contacts which induced, due to theory proposed by Landauer, the quantization of conductance. Thermal problems in nanowires are also discussed in the paper.

Impenetrable barriers for positrons in neighbourhood of superheavy nuclei with Z>118

NASA Astrophysics Data System (ADS)

Neznamov, V. P.

2017-12-01

Analysis of quantum mechanical motion of charged half-spin particles in the repulsive Coulomb field results in that an impenetrable potential barrier not explored earlier was found. For a particle at rest with a reduced mass m, the barrier radius is equal to half classical radius: the barrier radius decreases with increase in the particle energy. For the stable and quasi-stable nuclei with Z > 118, presence of an impenetrable barrier as β +-decay leads to the existence of “traps” for positrons in the neighbourhood of nuclei and as Zcr ≃ 170 (with emission of electron-positron pairs by vacuum) leads to the existence of a quasi-constant source of annihilation quanta.

Compact Gamma-Beam Source for Nuclear Security Technologies

NASA Astrophysics Data System (ADS)

Gladkikh, P.; Urakawa, J.

2015-10-01

A compact gamma-beam source dedicated to the development of the nuclear security technologies by use of the nuclear resonance fluorescence is described. Besides, such source is a very promising tool for novel technologies of the express cargoes inspection to prevent nuclear terrorism. Gamma-beam with the quanta energies from 0.3MeV to 7.2MeV is generated in the Compton scattering of the "green" laser photons on the electron beam with energies from 90MeV to 430MeV. The characteristic property of the proposed gammabeam source is a narrow spectrum (less than 1%) at high average gamma-yield (of 1013γ/s) due to special operation mode.

Splash, pop, sizzle: Information processing with phononic computing

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

Sklan, Sophia R.

2015-05-15

Phonons, the quanta of mechanical vibration, are important to the transport of heat and sound in solid materials. Recent advances in the fundamental control of phonons (phononics) have brought into prominence the potential role of phonons in information processing. In this review, the many directions of realizing phononic computing and information processing are examined. Given the relative similarity of vibrational transport at different length scales, the related fields of acoustic, phononic, and thermal information processing are all included, as are quantum and classical computer implementations. Connections are made between the fundamental questions in phonon transport and phononic control and themore » device level approach to diodes, transistors, memory, and logic. .« less

Parametric control in coupled fermionic oscillators

NASA Astrophysics Data System (ADS)

Ghosh, Arnab

2014-10-01

A simple model of parametric coupling between two fermionic oscillators is considered. Statistical properties, in particular the mean and variance of quanta for a single mode, are described by means of a time-dependent reduced density operator for the system and the associated P function. The density operator for fermionic fields as introduced by Cahill and Glauber [K. E. Cahill and R. J. Glauber, Phys. Rev. A 59, 1538 (1999), 10.1103/PhysRevA.59.1538] thus can be shown to provide a quantum mechanical description of the fields closely resembling their bosonic counterpart. In doing so, special emphasis is given to population trapping, and quantum control over the states of the system.

SiO 2/SiC interface proved by positron annihilation

NASA Astrophysics Data System (ADS)

Maekawa, M.; Kawasuso, A.; Yoshikawa, M.; Itoh, H.

2003-06-01

We have studied positron annihilation in a Silicon carbide (SiC)-metal/oxide/semiconductor (MOS) structure using a monoenergetic positron beam. The Doppler broadening of annihilation quanta were measured as functions of the incident positron energy and the gate bias. Applying negative gate bias, significant increases in S-parameters were observed. This indicates the migration of implanted positrons towards SiO 2/SiC interface and annihilation at open-volume type defects. The behavior of S-parameters depending on the bias voltage was well correlated with the capacitance-voltage ( C- V) characteristics. We observed higher S-parameters and the interfacial trap density in MOS structures fabricated using the dry oxidation method as compared to those by pyrogenic oxidation method.

Quantum Requirement for Photosynthesis in Chlorophyll-Deficient Plants with Unusual Lamellar Structures

PubMed Central

Schmid, Georg H.; Gaffron, Hans

1967-01-01

Neither an over-all deficiency of chlorophyll, nor an increased enzymatic capacity for maximal rates, nor an unusual lamellar structure was found to change the number of quanta required for the evolution of one molecule of oxygen in healthy aurea mutants of tobacco. The average minimal quantum number remains 10 (efficiency 0.1) as in many algae and typical higher plants. Most of the time the optimal efficiency depends on the availability of some far-red radiation, particularly in the blue region of the spectrum where blue light alone is rather inefficient. These results fit an explanation offered earlier in connection with the hydrogen or acetate photometabolism of algae in far-red light. PMID:19873573

Uphill energy transfer from long-wavelength absorbing chlorophylls to PS II in Ostreobium sp. is functional in carbon assimilation.

PubMed

Wilhelm, Christian; Jakob, Torsten

2006-03-01

From the algal genus Ostrobium two species are known which express a chlorophyll antenna absorbing between 710 and 725 nm to a different extent. In a comparative study with these two species it is shown that quanta absorbed by this long wavelength antenna can be transferred to PS II leading to significant PS II-related electron transfer. It is documented that under monochromatic far red light illumination growth continues with rather high efficiency. The data show that the uphill-energy transfer to PS II reduces the quantum yield under white light significantly. It is discussed that this strategy of energy conversion might play a role in special environments where far red light is the predominant energy source.

Underdamped long Josephson junction coupled to overdamped single-flux-quantum circuits

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

Zhang, Y.M.; Borzenets, V.; Kaplunenko, V.K.

1997-09-01

We report a circuit that integrates an underdamped long Josephson junction with overdamped single-flux-quantum (SFQ) circuits. We confirm that the resonant soliton modes in the long junction are not affected by SFQ cells coupled to the junction, and demonstrate that the radiation frequency and linewidth of the soliton resonances can be measured with SFQ T-flip-flops. Our experimental results also show that a 4{pi} quantum mechanical phase leap at the end of the long junction, which is due to the reflection of a soliton, creates two single flux quanta propagating in the overdamped Josephson transmission line. {copyright} {ital 1997 American Institutemore » of Physics.}« less

Black hole as a point radiator and recoil effect on the brane world.

PubMed

Frolov, Valeri; Stojković, Dejan

2002-10-07

A small black hole attached to a brane in a higher-dimensional space emitting quanta into the bulk may leave the brane as a result of a recoil. We construct a field theory model in which such a black hole is described as a massive scalar particle with internal degrees of freedom. In this model, the probability of transition between the different internal levels is identical to the probability of thermal emission calculated for the Schwarzschild black hole. The discussed recoil effect implies that the thermal emission of the black holes, which might be created by interaction of high energy particles in colliders, could be terminated and the energy nonconservation can be observed in the brane experiments.

A Survey of Plasmas and Their Applications

NASA Technical Reports Server (NTRS)

Eastman, Timothy E.; Grabbe, C. (Editor)

2006-01-01

Plasmas are everywhere and relevant to everyone. We bath in a sea of photons, quanta of electromagnetic radiation, whose sources (natural and artificial) are dominantly plasma-based (stars, fluorescent lights, arc lamps.. .). Plasma surface modification and materials processing contribute increasingly to a wide array of modern artifacts; e.g., tiny plasma discharge elements constitute the pixel arrays of plasma televisions and plasma processing provides roughly one-third of the steps to produce semiconductors, essential elements of our networking and computing infrastructure. Finally, plasmas are central to many cutting edge technologies with high potential (compact high-energy particle accelerators; plasma-enhanced waste processors; high tolerance surface preparation and multifuel preprocessors for transportation systems; fusion for energy production).

Anderson localized state as a predissipative state: irreversible emission of thermalized quanta from a dynamically delocalized state.

PubMed

Yamada, Hiroaki; Ikeda, Kensuke S

2002-04-01

It was shown that localization in one-dimensional disordered (quantum) electronic system is destroyed against coherent harmonic perturbations and the delocalized electron exhibits an unlimited diffusive motion [Yamada and Ikeda, Phys. Rev. E 59, 5214 (1999)]. The appearance of diffusion implies that the system has potential for irreversibility and dissipation. In the present paper, we investigate dissipative property of the dynamically delocalized state, and we show that an irreversible quasistationary energy flow indeed appears in the form of a "heat" flow when we couple the system with another dynamical degree of freedom. In the concrete we numerically investigate dissipative properties of a one-dimensional tight-binding electronic system perturbed by time-dependent harmonic forces, by coupling it with a quantum harmonic oscillator or a quantum anharmonic oscillator. It is demonstrated that if the on-site potential is spatially irregular an irreversible energy transfer from the scattered electron to the test oscillator occurs. Moreover, the test oscillator promptly approaches a thermalized state characterized by a well-defined time-dependent temperature. On the contrary, such a relaxation process cannot be observed at all for periodic potential systems. Our system is one of the minimal quantum systems in which a distinct nonequilibrium statistical behavior is self-induced.

Discovery of Dozy Chaos and Discovery of Quanta: Analogy Being in Science and Perhaps in Human Progress

NASA Astrophysics Data System (ADS)

Egorov, Vladimir V.

The concept of a dozy chaos in the theory of quantum transitions and its applications are discussed in a historical context. Conjectured that dozy chaos is of primary importance to the dynamic self-organization of any living organism and concentrated in its brain. A hypothesis of the physical origin of cancer is put forward. Surmised that dozy chaos is the physical origin of life and driving force of its evolution.

Electron Transport In Nanowires - An Engineer'S View

NASA Astrophysics Data System (ADS)

Nawrocki, W.

In the paper technological problems connected to electron transport in mesoscopic- and nanostructures are considered. The electrical conductance of nanowires formed by metallic contacts in an experimental setup proposed by Costa-Kramer et al. The investigation has been performed in air at room temperature measuring the conductance between two vibrating metal wires with standard oscilloscope. Conductance quantization in units of G o = 2e /h = (12.9 kΩ)-1 up to five quanta of conductance has been observed for nanowires formed in many metals. The explanation of this universal phenomena is the formation of a nanometer-sized wire (nanowire) between macroscopic metallic contacts which induced, due to theory proposed by Landauer, the quantization of conductance. Thermal problems in nanowirese are also discussed in the paper.

First results of experiments with a medical one-coordinate X-ray detector on synchrotron radiation of VEPP-4

NASA Astrophysics Data System (ADS)

Dementyev, E. N.; Dovga, E. Ya.; Kulipanov, G. N.; Medvedko, A. S.; Mezentsev, N. A.; Pindyurin, V. F.; Sheromov, M. A.; Skrinsky, A. N.; Sokolov, A. S.; Ushakov, V. A.; Zagorodnikov, E. I.; Kaidorin, A. G.; Neugodov, Yu. V.

1986-05-01

The first results of studying the performance of a fast X-ray one-coordinate detector on the SR beam from VEPP-4 are presented. The detector consists of 128 independent channels, each being a scintillation counter on the basis of NaI(Tl) crystals. The spatial resolution of the detector constitutes 1.5 mm and its speed of response is 128 × 1 MHz. The main purpose of the detector is to examine the human circulatory system by the method of difference angiography at an energy of quanta corresponding to the K-absorption edge of iodine (33.2 keV). The first results on radiation exposure of the blood vessels of a live dog with a spatial resolution of 0.75 mm are given.

EPR experiment and 2-photon interferometry: Report of a 2-photon interference experiment

NASA Technical Reports Server (NTRS)

Shih, Y. H.; Rubin, M. H.; Sergienko, A. V.

1992-01-01

After a very brief review of the historical Einstein, Podolsky, and Rosen (EPR) experiments, a new two-photon interference type EPR experiment is reported. A two-photon state was generated by optical parametric down conversion. Pairs of light quanta with degenerate frequency but divergent directions of propagation were sent to two independent Michelson interferometers. First and second order interference effectors were studied. Different than other reports, we observed that the second order interference visibility vanished when the optical path difference of the interferometers were much less than the coherence length of the pumping laser beam. However, we also observed that the second order interference behaved differently depending on whether the interferometers were set at equal or different optical path differences.

Violation of the second law of thermodynamics in the quantum microworld

NASA Astrophysics Data System (ADS)

Čápek, V.; Bok, J.

2001-02-01

One of the previously reported linear models of open quantum systems (interacting with a single thermal bath but otherwise not aided from outside) endowed with the faculty of spontaneous self-organization challenging standard thermodynamics is reconstructed here. It is then able to produce, in a cyclic manner, a useful (this time mechanical) work at the cost of just thermal energy in the bath whose quanta get properly in-phased. This means perpetuum mobile of the second kind explicitly violating the second law in its Thomson formulation. No approximations can be made responsible for the effect as a special scaling procedure is used that makes the chosen kinetic theory exact. The effect is purely quantum and disappears in the classical limit.

Teaching Einsteinian physics at schools: part 1, models and analogies for relativity

NASA Astrophysics Data System (ADS)

Kaur, Tejinder; Blair, David; Moschilla, John; Stannard, Warren; Zadnik, Marjan

2017-11-01

The Einstein-First project aims to change the paradigm of school science teaching through the introduction of modern Einsteinian concepts of space and time, gravity and quanta at an early age. These concepts are rarely taught to school students despite their central importance to modern science and technology. The key to implementing the Einstein-First curriculum is the development of appropriate models and analogies. This paper is the first part of a three-paper series. It presents the conceptual foundation of our approach, based on simple physical models and analogies, followed by a detailed description of the models and analogies used to teach concepts of general and special relativity. Two accompanying papers address the teaching of quantum physics (Part 2) and research outcomes (Part 3).

Quantum entanglement of high angular momenta.

PubMed

Fickler, Robert; Lapkiewicz, Radek; Plick, William N; Krenn, Mario; Schaeff, Christoph; Ramelow, Sven; Zeilinger, Anton

2012-11-02

Single photons with helical phase structures may carry a quantized amount of orbital angular momentum (OAM), and their entanglement is important for quantum information science and fundamental tests of quantum theory. Because there is no theoretical upper limit on how many quanta of OAM a single photon can carry, it is possible to create entanglement between two particles with an arbitrarily high difference in quantum number. By transferring polarization entanglement to OAM with an interferometric scheme, we generate and verify entanglement between two photons differing by 600 in quantum number. The only restrictive factors toward higher numbers are current technical limitations. We also experimentally demonstrate that the entanglement of very high OAM can improve the sensitivity of angular resolution in remote sensing.

Gravitational self-interactions of a degenerate quantum scalar field

NASA Astrophysics Data System (ADS)

Chakrabarty, Sankha S.; Enomoto, Seishi; Han, Yaqi; Sikivie, Pierre; Todarello, Elisa M.

2018-02-01

We develop a formalism to help calculate in quantum field theory the departures from the description of a system by classical field equations. We apply the formalism to a homogeneous condensate with attractive contact interactions and to a homogeneous self-gravitating condensate in critical expansion. In their classical descriptions, such condensates persist forever. We show that in their quantum description, parametric resonance causes quanta to jump in pairs out of the condensate into all modes with wave vector less than some critical value. We calculate, in each case, the time scale over which the homogeneous condensate is depleted and after which a classical description is invalid. We argue that the duration of classicality of inhomogeneous condensates is shorter than that of homogeneous condensates.

Amplified fermion production from overpopulated Bose fields

NASA Astrophysics Data System (ADS)

Berges, J.; Gelfand, D.; Sexty, D.

2014-01-01

We study the real-time dynamics of fermions coupled to scalar fields in a linear sigma model, which is often employed in the context of preheating after inflation or as a low-energy effective model for quantum chromodynamics. We find a dramatic amplification of fermion production in the presence of highly occupied bosonic quanta for weak as well as strong effective couplings. For this we consider the range of validity of different methods: lattice simulations with male/female fermions, the mode functions approach and the quantum 2PI effective action with its associated kinetic theory. For strongly coupled fermions we find a rapid approach to a Fermi-Dirac distribution with time-dependent temperature and chemical potential parameters, while the bosons are still far from equilibrium.

High-Penetration PV Integration Handbook for Distribution Engineers

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

Seguin, Rich; Woyak, Jeremy; Costyk, David

2016-01-01

This handbook has been developed as part of a five-year research project which began in 2010. The National Renewable Energy Laboratory (NREL), Southern California Edison (SCE), Quanta Technology, Satcon Technology Corporation, Electrical Distribution Design (EDD), and Clean Power Research (CPR) teamed together to analyze the impacts of high-penetration levels of photovoltaic (PV) systems interconnected onto the SCE distribution system. This project was designed specifically to leverage the experience that SCE and the project team would gain during the significant installation of 500 MW of commercial scale PV systems (1-5 MW typically) starting in 2010 and completing in 2015 within SCE’smore » service territory through a program approved by the California Public Utility Commission (CPUC).« less

NREL/SCE High Penetration PV Integration Project: FY13 Annual Report

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

Mather, B. A.; Shah, S.; Norris, B. L.

2014-06-01

In 2010, the National Renewable Energy Laboratory (NREL), Southern California Edison (SCE), Quanta Technology, Satcon Technology Corporation, Electrical Distribution Design (EDD), and Clean Power Research (CPR) teamed to analyze the impacts of high penetration levels of photovoltaic (PV) systems interconnected onto the SCE distribution system. This project was designed specifically to benefit from the experience that SCE and the project team would gain during the installation of 500 megawatts (MW) of utility-scale PV systems (with 1-5 MW typical ratings) starting in 2010 and completing in 2015 within SCE's service territory through a program approved by the California Public Utility Commissionmore » (CPUC). This report provides the findings of the research completed under the project to date.« less

From photons to phonons and back: a THz optical memory in diamond.

PubMed

England, D G; Bustard, P J; Nunn, J; Lausten, R; Sussman, B J

2013-12-13

Optical quantum memories are vital for the scalability of future quantum technologies, enabling long-distance secure communication and local synchronization of quantum components. We demonstrate a THz-bandwidth memory for light using the optical phonon modes of a room temperature diamond. This large bandwidth makes the memory compatible with down-conversion-type photon sources. We demonstrate that four-wave mixing noise in this system is suppressed by material dispersion. The resulting noise floor is just 7×10(-3) photons per pulse, which establishes that the memory is capable of storing single quanta. We investigate the principle sources of noise in this system and demonstrate that high material dispersion can be used to suppress four-wave mixing noise in Λ-type systems.

New stable perfluoroallyl radical from perfluoro-2,4-dimethyl-3-ethylpentene-2 and its photoconversion reactions

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

Shvedova, M.K.; Allayarov, S.R.; Barkalov, I.M.

1988-05-01

The thermally and chemically stable perfluoroally radical is formed in the radiolysis of perfluoro-2, 4-dimethyl-3-ethylpentene-2. A phototransformation of this radical into other radicals takes place under the action of UV light (/lambda/ < 300 nm) which are thermally unstable. Samples containing up to 90% FMP and 10% of its isomers were placed into ampules made of quartz or SK-4B glass, which gave to EPR signal after irradiation; the ampules were evacuated to a pressure of 0.13 Pa, frozen to 77 K, and irradiated with /sup 60/Co /lambda/-quanta at 77 K with doses up to 200 kGy. Irradiation with UV lightmore » was performed at 77 K with light from a DRSh-1000 lamp.« less

Nonlinear Schrödinger equation and classical-field description of thermal radiation

NASA Astrophysics Data System (ADS)

Rashkovskiy, Sergey A.

2018-03-01

It is shown that the thermal radiation can be described without quantization of energy in the framework of classical field theory using the nonlinear Schrödinger equation which is considered as a classical field equation. Planck's law for the spectral energy density of thermal radiation and the Einstein A-coefficient for spontaneous emission are derived without using the concept of the energy quanta. It is shown that the spectral energy density of thermal radiation is apparently not a universal function of frequency, as follows from the Planck's law, but depends weakly on the nature of atoms, while Planck's law is valid only as an approximation in the limit of weak excitation of atoms. Spin and relativistic effects are not considered in this paper.

Detecting neutrons by forward recoil protons at the Energy & Transmutation facility: Detector development and calibration with 14.1-MeV neutrons

NASA Astrophysics Data System (ADS)

Afanasev, S.; Vishnevskiy, A.; Vishnevskiy, D.; Rogachev, A.; Tyutyunnikov, S.

2017-05-01

As part of the Energy & Transmutation project, we are developing a detector for neutrons with energies in the 10-100 MeV range emitted from the target irradiated by a charged-particle beam. The neutron is detected by measuring the time-of-flight and total kinetic energy of the forward-going recoil proton [1] knocked out at a small angle from a thin layer of plastic scintillator, which has to be selected against an intense background created by γ quanta, scattered neutrons, and charged particles. On the other hand, neutron energy has to be measured over the full range with no extra tuning of the detector operation regime. Initial measurements with a source of 14.1-MeV neutrons are reported.

Electron Generation of Leptons and Hadrons with Conjugate α-QUANTIZED Lifetimes and Masses

NASA Astrophysics Data System (ADS)

Mac Gregor, Malcolm H.

In elementary particle theories the fine structure constant α = e2/ℏc serves as the coupling constant for lepton interactions (QED), but is assumed to play no role in hadron interactions (QCD). However, experiments have long indicated an α spacing in the lifetimes of the long-lived threshold-state hadrons, and they also suggest an α-related mass structure. Lifetimes and masses are conjugate quantum mechanical variables, so the α-dependence of these two variables is a mutual property. The relevance of α to hadron interactions is an experimental question, independent of theory. In the present paper we first make a detailed analysis of the experimental lifetime data. This analysis demonstrates that out of 156 particles with well-determined lifetimes τ, the 120 short excited-state lifetimes τ<10-21 sec have a continuum of values, but the 36 long threshold-state lifetimes τ>10-21 sec occur in α-spaced groups that cleanly sort out the s, c, b quark flavors. These 36 metastable lifetimes also exhibit a factor-of-3 c-to-b "flavor structure" and a pervasive factor-of-2 "hyperfine structure." We then invoke the conjugate relationship between lifetimes and masses to trace out an α-defined set of mass quanta that tie together leptons and hadrons. Mass generation occurs via an initial "α-leap" from an electron pair to a "platform state" M, and then subsequent excitations by a dominant quantum X. The low-mass "MX octet" of particles — μ, p, τ, π, η, η‧, K, ϕ — is reproduced to an average accuracy of 0.4%, with no adjustable parameters except a small binding energy for hadronic pairs. Without the inclusion of lepton masses, the spectrum of hadron masses is difficult to understand. These conjugate α-quantized results reinforce the reality of the spin 1/2 u, d, s, c, b quarks, and they also lead to the identification of a closely-related set of spinless mass quanta for the pseudoscalar mesons.

Line shape parameters of PH3 transitions in the Pentad near 4-5 μm: Self-broadened widths, shifts, line mixing and speed dependence

NASA Astrophysics Data System (ADS)

Malathy Devi, V.; Benner, D. Chris; Kleiner, Isabelle; Sams, Robert L.; Fletcher, Leigh N.

2014-08-01

Accurate knowledge of spectroscopic line parameters of PH3 is important for remote sensing of the outer planets, especially Jupiter and Saturn. In a recent study, line positions and intensities for the Pentad bands of PH3 have been reported from analysis of high-resolution, high signal-to noise room-temperature spectra recorded with two Fourier transform spectrometers (2014) [1]. The results presented in this study were obtained during the analysis of positions and intensities, but here we focus on the measurements of spectral line shapes (e.g. widths, shifts, line mixing) for the 2ν4, ν2 + ν4, ν1 and ν3 bands. A multispectrum nonlinear least squares curve fitting technique employing a non-Voigt line shape to include line mixing and speed dependence of the Lorentz width was employed to fit the spectra simultaneously. The least squares fittings were performed on five room-temperature spectra recorded at various PH3 pressures (∼2-50 Torr) with the Bruker IFS-125HR Fourier transform spectrometer (FTS) located at the Pacific Northwest National Laboratory (PNNL), in Richland, Washington. Over 840 Lorentz self-broadened half-width coefficients, 620 self-shift coefficients and 185 speed dependence parameters were measured. Line mixing was detected for transitions in the 2ν4, ν1 and ν3 bands, and their values were quantified for 10 A+A- pairs of transitions via off-diagonal relaxation matrix element formalism. The dependences of the measured half-width coefficients on the J and K rotational quanta of the transitions are discussed. The self-width coefficients for the ν1 and ν3 bands from this study are compared to the self-width coefficients for transitions with the same rotational quanta (J, K) reported for the Dyad (ν2 and ν4) bands. The measurements from present study should be useful for the development of a reliable theoretical modeling of pressure-broadened widths, shifts and line mixing in symmetric top molecules with C3v symmetry in general, and of PH3

Line shape parameters of PH 3 transitions in the Pentad near 4–5 μm: Self-broadened widths, shifts, line mixing and speed dependence

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

Malathy Devi, V.; Benner, D. C.; Kleiner, Isabelle

2014-08-01

Accurate knowledge of spectroscopic line parameters of PH 3 is important for remote sensing of the outer planets, especially Jupiter and Saturn. In a recent study, line positions and intensities for the Pentad bands of PH 3 have been reported from analysis of high-resolution, high signal-to noise room-temperature spectra recorded with two Fourier transform spectrometers (2014) [1]. The results presented in this study were obtained during the analysis of positions and intensities, but here we focus on the measurements of spectral line shapes (e.g. widths, shifts, line mixing) for the 2ν 4, ν 2 + ν 4, ν 1 andmore » ν 3 bands. A multispectrum nonlinear least squares curve fitting technique employing a non-Voigt line shape to include line mixing and speed dependence of the Lorentz width was employed to fit the spectra simultaneously. The least squares fittings were performed on five room-temperature spectra recorded at various PH 3 pressures (~2–50 Torr) with the Bruker IFS-125HR Fourier transform spectrometer (FTS) located at the Pacific Northwest National Laboratory (PNNL), in Richland, Washington. Over 840 Lorentz self-broadened half-width coefficients, 620 self-shift coefficients and 185 speed dependence parameters were measured. Line mixing was detected for transitions in the 2ν 4, ν 1 and ν 3 bands, and their values were quantified for 10 A+A- pairs of transitions via off-diagonal relaxation matrix element formalism. The dependences of the measured half-width coefficients on the J and K rotational quanta of the transitions are discussed. The self-width coefficients for the ν 1 and ν 3 bands from this study are compared to the self-width coefficients for transitions with the same rotational quanta (J, K) reported for the Dyad (ν 2 and ν 4) bands. The measurements from present study should be useful for the development of a reliable theoretical modeling of pressure-broadened widths, shifts and line mixing in symmetric top molecules with C 3v

Enhancing light-harvesting power with coherent vibrational interactions: A quantum heat engine picture

NASA Astrophysics Data System (ADS)

Killoran, N.; Huelga, S. F.; Plenio, M. B.

2015-10-01

Recent evidence suggests that quantum effects may have functional importance in biological light-harvesting systems. Along with delocalized electronic excitations, it is now suspected that quantum coherent interactions with certain near-resonant vibrations may contribute to light-harvesting performance. However, the actual quantum advantage offered by such coherent vibrational interactions has not yet been established. We investigate a quantum design principle, whereby coherent exchange of single energy quanta between electronic and vibrational degrees of freedom can enhance a light-harvesting system's power above what is possible by thermal mechanisms alone. We present a prototype quantum heat engine which cleanly illustrates this quantum design principle and quantifies its quantum advantage using thermodynamic measures of performance. We also demonstrate the principle's relevance in parameter regimes connected to natural light-harvesting structures.

In Search of the Ultimate Building Blocks

NASA Astrophysics Data System (ADS)

't Hooft, Gerard

1996-12-01

An apology; 1. The beginning of the journey to the small: cutting paper; 2. To molecules and atoms; 3. The magic mystery of the quanta; 4. Dazzling velocities; 5. The elementary particle zoo before 1970; 6. Life and death; 7. The crazy kaons; 8. The invisible quarks; 9. Fields or bootstraps?; 10. The Yang-Mills bonanza; 11. Superconducting empty space: the Higgs-Kibble machine; 12. Models; 13. Colouring in the strong forces; 14. The magnetic monopole; 15. Gypsy; 16. The brilliance of the standard model; 17. Anomalies; 18. Deceptive perfection; 19. Weighing neutrinos; 20. The great desert; 21. Technicolor; 22. Grand unification; 23. Supergravity; 24. Eleven dimensional space-time; 25. Attaching the super string; 26. Into the black hole; 27. Theories that do not yet exist … ; 28. Dominance of the rule of the smallest.

Influence of damping on quantum interference - An exactly soluble model

NASA Technical Reports Server (NTRS)

Caldeira, A. O.; Leggett, A. J.

1985-01-01

This paper reports the result of a calculation which shows the effect of damping on the quantum interference of two Gaussian wave packets in a harmonic potential. The influence-functional method, which seems to be the most appropriate one for this kind of calculation, is used. It is shown that quantum-interference effects are severely diminished by the presence of damping even when its influence on the system is only light. The corrections to the undamped formulas are always expressible in terms of the phenomenological damping constant, the temperature (in the high-temperature limit), the cutoff frequency of the reservoir oscillators, and the mean number of quanta of energy intially present in the system. Both weakly and strongly damped systems are analyzed in the regime of low and high temperatures.

A semiconductor photon-sorter

NASA Astrophysics Data System (ADS)

Bennett, A. J.; Lee, J. P.; Ellis, D. J. P.; Farrer, I.; Ritchie, D. A.; Shields, A. J.

2016-10-01

Obtaining substantial nonlinear effects at the single-photon level is a considerable challenge that holds great potential for quantum optical measurements and information processing. Of the progress that has been made in recent years one of the most promising methods is to scatter coherent light from quantum emitters, imprinting quantum correlations onto the photons. We report effective interactions between photons, controlled by a single semiconductor quantum dot that is weakly coupled to a monolithic cavity. We show that the nonlinearity of a transition modifies the counting statistics of a Poissonian beam, sorting the photons in number. This is used to create strong correlations between detection events and to create polarization-correlated photons from an uncorrelated stream using a single spin. These results pave the way for semiconductor optical switches operated by single quanta of light.

Topological defects in mixtures of superconducting condensates with different charges

NASA Astrophysics Data System (ADS)

Garaud, Julien; Babaev, Egor

2014-06-01

We investigate the topological defects in phenomenological models describing mixtures of charged condensates with commensurate electric charges. Such situations are expected to appear for example in liquid metallic deuterium. This is modeled by a multicomponent Ginzburg-Landau theory where the condensates are coupled to the same gauge field by different coupling constants whose ratio is a rational number. We also briefly discuss the case where electric charges are incommensurate. Flux quantization and finiteness of the energy per unit length dictate that the different condensates have different winding and thus different number of (fractional) vortices. Competing attractive and repulsive interactions lead to molecule-like bound states between fractional vortices. Such bound states have finite energy and carry integer flux quanta. These can be characterized by the CP1 topological invariant that motivates their denomination as skyrmions.

Celebrating the physics in geophysics

NASA Astrophysics Data System (ADS)

Davis, Anthony B.; Sornette, Didier

The United Nations' Educational, Scientific and Cultural Organization (UNESCO) declared 2005 the “World Year of Physics” in celebration of the centennial of Einstein's annus mirabilis when, as junior clerk at the Swiss Patent Office in Berne, he published three papers that changed physics forever by (1) introducing Special Relativity and demonstrating the equivalence of mass and energy (E = mc2), (2) explaining the photoelectric effect with Planck's then-still-new-and-controversial concept of light quanta (E = hv), and (3) investigating the macroscopic phenomenon of Brownian motion using Boltzmann's molecular dynamics (E = kT), still far from fully accepted at the time.The celebration of Einstein's work in physics inspires the reflection on the status of geophysics and its relationship with physics, in particular with respect to great discoveries.

Search for neutrino generated air shower candidates with energy ≥ 1019 eV and Zenith angle θ

NASA Astrophysics Data System (ADS)

Knurenko, Stanislav; Petrov, Igor; Sabourov, Artem

2017-06-01

The description of the methodology and results of searching for air showers generated by neutral particles such as high energy gamma quanta and astroneutrinos are presented. For this purpose, we conducted a comprehensive analysis of the data: the electron, the muon and the EAS Cerenkov light, and their response time in scintillation and Cherenkov detectors. Air showers with energy more than 5·1018 eV and zenith angle θ ≥ 55∘ are selected and analyzed. Search results indicate a lack of air shower events formed by gamma-rays or high-energy neutrinos, but it does not mean that such air showers do not exist in nature; for example, experiments that recorded showers having a marked low muon content, i.e., "Muonless", are likely to be candidates for showers produced by neutral primary particles.

Study of the Radiation Resistance of Endohedral Fullerenes of Rare-Earth Elements and Their Water-Soluble Derivatives

NASA Astrophysics Data System (ADS)

Dubovskii, I. M.; Lebedev, V. T.; Shilin, V. A.; Szhogina, A. A.; Suyasova, M. V.; Sedov, V. P.

2018-01-01

Endohedral metallofullerenes Me@C2 n ( n = 30-50), their hydroxylated derivatives Me@C2 n (OH)38-40 ( Me = Tm, Ho, Eu, Sm, Co), and fullerenol C60(OH)38 have been synthesized The radiation resistance of these structures under irradiation in reactor by thermal and fast neutron fluxes in the fluence range of 1018-1019 cm-2 (cadmium ratio of 10) has been analyzed. Endofullerenols are shown to be more stable in comparison with initial endohedral fullerenes; the molecules containing Eu and Sm (atoms characterized by the largest slow-neutron absorption cross section) turned out to be most stable. The mechanism of the formation of secondary Eu and Sm endofullerenols is discussed taking into account the neutron capture and emission of γ quanta by excited nuclei, which acquire the recoil energy.

Production of gravitational waves during preheating with nonminimal coupling

NASA Astrophysics Data System (ADS)

Fu, Chengjie; Wu, Puxun; Yu, Hongwei

2018-04-01

We study the preheating and the in-process production of gravitational waves (GWs) after inflation in which the inflaton is nonminimally coupled to the curvature in a self-interacting quartic potential with the method of lattice simulation. We find that the nonminimal coupling enhances the amplitude of the density spectrum of inflaton quanta, and as a result, the peak value of the GW spectrum generated during preheating is enhanced as well and might reach the limit of detection in future GW experiments. The peaks of the GW spectrum not only exhibit distinctive characteristics as compared to those of minimally coupled inflaton potentials but also imprint information on the nonminimal coupling and the parametric resonance, and thus the detection of these peaks in the future will provide us a new avenue to reveal the physics of the early universe.

Quantum origins of objectivity

NASA Astrophysics Data System (ADS)

Horodecki, R.; Korbicz, J. K.; Horodecki, P.

2015-03-01

In spite of all of its successes, quantum mechanics leaves us with a central problem: How does nature create a bridge from fragile quanta to the objective world of everyday experience? Here we find that a basic structure within quantum mechanics that leads to the perceived objectivity is a so-called spectrum broadcast structure. We uncover this based on minimal assumptions, without referring to any dynamical details or a concrete model. More specifically, working formally within the decoherence theory setting with multiple environments (called quantum Darwinism), we show how a crucial for quantum mechanics notion of nondisturbance due to Bohr [N. Bohr, Phys. Rev. 48, 696 (1935), 10.1103/PhysRev.48.696] and a natural definition of objectivity lead to a canonical structure of a quantum system-environment state, reflecting objective information records about the system stored in the environment.

Magnetic Property in Large Array Niobium Antidot Thin Films

NASA Astrophysics Data System (ADS)

Tinghui, Chen; Hsiang-Hsi, Kung; Wei-Li, Lee; Institute of Physics, Academia Sinica, Taipei, Taiwan Team

2014-03-01

In a superconducting ring, the total flux inside the ring is required to be an integer number of the flux quanta. Therefore, a supercurrent current can appear within the ring in order to satisfy this quantization rule, which gives rise to certain magnetic response. By using a special monolayer polymer/nanosphere hybrid we developed previously, we fabricated a series of superconducting niobium antidot thin films with different antidot diameters. The antidots form well-ordered triangular lattice with a lattice spacing about 200 nm and extend over an area larger than 1 cm2, which enables magnetic detections simply by a SQUID magnetometer. We observed magnetization oscillation with external magnetic field due to the supercurrent screening effect, where different features for large and small antidot thin films were found. Detailed size and temperature dependencies of the magnetization in niobium antidot nanostructures will be presented.

Micro-Macro Duality and Space-Time Emergence

NASA Astrophysics Data System (ADS)

Ojima, Izumi

2011-03-01

The microscopic origin of space-time geometry is explained on the basis of an emergence process associated with the condensation of infinite number of microscopic quanta responsible for symmetry breakdown, which implements the basic essence of "Quantum-Classical Correspondence" and of the forcing method in physical and mathematical contexts, respectively. From this viewpoint, the space-time dependence of physical quantities arises from the "logical extension" [8] to change "constant objects" into "variable objects" by tagging the order parameters associated with the condensation onto "constant objects"; the logical direction here from a value y to a domain variable x (to materialize the basic mechanism behind the Gel'fand isomorphism) is just opposite to that common in the usual definition of a function ƒ : x⟼ƒ(x) from its domain variable x to a value y = ƒ(x).

Hysteretic Vortex-Matching Effects in High-Tc Superconductors with Nanoscale Periodic Pinning Landscapes Fabricated by He Ion-Beam Projection

NASA Astrophysics Data System (ADS)

Zechner, G.; Jausner, F.; Haag, L. T.; Lang, W.; Dosmailov, M.; Bodea, M. A.; Pedarnig, J. D.

2017-07-01

Square arrays of submicrometer columnar defects in thin YBa2 Cu3 O7 -δ (YBCO) films with spacings down to 300 nm are fabricated by a He ion-beam projection technique. Pronounced peaks in the critical current and corresponding minima in the resistance demonstrate the commensurate arrangement of flux quanta with the artificial pinning landscape, despite the strong intrinsic pinning in epitaxial YBCO films. While these vortex-matching signatures are exactly at the predicted values in field-cooled experiments, they are displaced in zero-field-cooled, magnetic-field-ramped experiments, conserving the equidistance of the matching peaks and minima. These observations reveal an unconventional critical state in a cuprate superconductor with an artificial, periodic pinning array. The long-term stability of such out-of-equilibrium vortex arrangements paves the way for electronic applications employing fluxons.

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

Mazuritskiy, M. I., E-mail: mazurmik@gmail.com; Lerer, A. M.; Makhno, P. V.

The angular distribution of the X-ray intensity at the exit of microchannel plates at grazing incidence of monochromatic radiation on the walls of microcapillaries has been investigated. The angles and energies of the primary radiation quanta at which the synchrotron beam excites X-ray fluorescence propagating inside polycapillary structures have been determined. The angular dependences of the intensity distribution of X-rays transmitted through the microcapillaries have been studied theoretically and experimentally for energies corresponding to the region of anomalous dispersion near the L{sub 2,3} absorption edges of silicon. The propagation of waves in hollow polycapillary waveguides, the excitation of X-ray fluorescence,more » and the X-ray diffraction at the exit of microchannel plates have been modeled mathematically. The mathematical model takes into account the presence of a transition layer on the microchannel surface.« less

[Application of droplet digital PCR technology for genetic testing and prenatal diagnosis of spinal muscular atrophy].

PubMed

Zou, Yang; Xu, Peiwen; Li, Jie; Huang, Sexin; Gao, Ming; Kang, Ranran; Gao, Xuan; Gao, Yuan

2016-10-01

To explore the clinical application of droplet digital PCR (ddPCR) for genetic testing and prenatal diagnosis of spinal muscular atrophy (SMA) with deletion of SMN1 gene exon 7. A total of 138 clinical samples, including 121 peripheral blood, 13 amniotic fluid, 2 umbilical cord blood and 2 chorionic villi from 56 SMA families, were tested by both ddPCR and multiplex ligation-dependent probe amplification (MLPA). Results of the two approaches were analyzed with commercial software QuantaSoft (ddPCR) and Coffalyser (MLPA), respectively. Among the 138 cases, 25 had two copies, 84 had one copy, and 29 had null copy of exon 7 of the SMN1 gene. The results of ddPCR and MLPA were completely consistent. As a rapid, precise and economically efficient method, ddPCR will provide a new choice for genetic testing of SMA.

Radiolytic decomposition of ammonium halides

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

Orlov, S.L.; Gromov, V.V.; Saunin, E.I.

1988-11-01

Chromatographic analyses were made of the gaseous products of the radiolysis of polycrystalline NH/sub 4/F, NH/sub 4/Cl, NH/sub 4/Br, and NH/sub 4/I, of particle size 0.25-0.5 mm. The irradiation was performed with /sup 60/Co ..sigma..-quanta, at room temperature in previously evacuated and sealed glass ampules. Determination was made of the amount of gas liberated into the space of the ampule during the irradiation, and of the amount retained in the crystal matrix and evolved on dissolution of the resulting samples in deaerated water. At the same time quantitative determinations of halogen were made by the thiosulfate method. It was shownmore » that hydrogen and nitrogen were formed in the radiolysis of all the compounds investigated. The yields are listed.« less

Vibrational Mode-Specific Reaction of Methane on a Nickel Surface

NASA Astrophysics Data System (ADS)

Beck, Rainer D.; Maroni, Plinio; Papageorgopoulos, Dimitrios C.; Dang, Tung T.; Schmid, Mathieu P.; Rizzo, Thomas R.

2003-10-01

The dissociation of methane on a nickel catalyst is a key step in steam reforming of natural gas for hydrogen production. Despite substantial effort in both experiment and theory, there is still no atomic-scale description of this important gas-surface reaction. We report quantum state-resolved studies, using pulsed laser and molecular beam techniques, of vibrationally excited methane reacting on the nickel (100) surface. For doubly deuterated methane (CD2H2), we observed that the reaction probability with two quanta of excitation in one C-H bond was greater (by as much as a factor of 5) than with one quantum in each of two C-H bonds. These results clearly exclude the possibility of statistical models correctly describing the mechanism of this process and attest to the importance of full-dimensional calculations of the reaction dynamics.

Vibrational mode-specific reaction of methane on a nickel surface.

PubMed

Beck, Rainer D; Maroni, Plinio; Papageorgopoulos, Dimitrios C; Dang, Tung T; Schmid, Mathieu P; Rizzo, Thomas R

2003-10-03

The dissociation of methane on a nickel catalyst is a key step in steam reforming of natural gas for hydrogen production. Despite substantial effort in both experiment and theory, there is still no atomic-scale description of this important gas-surface reaction. We report quantum state-resolved studies, using pulsed laser and molecular beam techniques, of vibrationally excited methane reacting on the nickel (100) surface. For doubly deuterated methane (CD2H2), we observed that the reaction probability with two quanta of excitation in one C-H bond was greater (by as much as a factor of 5) than with one quantum in each of two C-H bonds. These results clearly exclude the possibility of statistical models correctly describing the mechanism of this process and attest to the importance of full-dimensional calculations of the reaction dynamics.

Enhancing light-harvesting power with coherent vibrational interactions: A quantum heat engine picture

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

Killoran, N.; Huelga, S. F.; Plenio, M. B.

Recent evidence suggests that quantum effects may have functional importance in biological light-harvesting systems. Along with delocalized electronic excitations, it is now suspected that quantum coherent interactions with certain near-resonant vibrations may contribute to light-harvesting performance. However, the actual quantum advantage offered by such coherent vibrational interactions has not yet been established. We investigate a quantum design principle, whereby coherent exchange of single energy quanta between electronic and vibrational degrees of freedom can enhance a light-harvesting system’s power above what is possible by thermal mechanisms alone. We present a prototype quantum heat engine which cleanly illustrates this quantum design principlemore » and quantifies its quantum advantage using thermodynamic measures of performance. We also demonstrate the principle’s relevance in parameter regimes connected to natural light-harvesting structures.« less

Fading Hawking radiation

NASA Astrophysics Data System (ADS)

Sakalli, Izzet; Halilsoy, Mustafa; Pasaoglu, Hale

2012-07-01

In this study, we explore a particular type Hawking radiation which ends with zero temperature and entropy. The appropriate black holes for this purpose are the linear dilaton black holes. In addition to the black hole choice, a recent formalism in which the Parikh-Wilczek's tunneling formalism amalgamated with quantum corrections to all orders in ħ is considered. The adjustment of the coefficients of the quantum corrections plays a crucial role on this particular Hawking radiation. The obtained tunneling rate indicates that the radiation is not pure thermal anymore, and hence correlations of outgoing quanta are capable of carrying away information encoded within them. Finally, we show in detail that when the linear dilaton black hole completely evaporates through such a particular radiation, entropy of the radiation becomes identical with the entropy of the black hole, which corresponds to "no information loss".

Propagation of monochromatic light in a hot and dense medium

NASA Astrophysics Data System (ADS)

Masood, Samina S.

2017-12-01

Photons, as quanta of electromagnetic fields, determine the electromagnetic properties of an extremely hot and dense medium. Considering the properties of the photons in the interacting medium of charged particles, we explicitly calculate the electromagnetic properties such as the electric permittivity, magnetic permeability, refractive index and the propagation speed of electromagnetic signals in an extremely hot and dense background. Photons acquire a dynamically generated mass in such a medium. The screening mass of the photon, the Debye shielding length and the plasma frequency are calculated as functions of the statistical parameters of the medium. We study the properties of the propagating particles in astrophysical systems of distinct statistical conditions. The modifications in the properties of the medium lead to the equation of state of the system. We mainly calculate all these parameters for extremely high temperatures of the early universe.

Oxygen evolution from single- and multiple-turnover light pulses: temporal kinetics of electron transport through PSII in sunflower leaves.

PubMed

Oja, Vello; Eichelmann, Hillar; Laisk, Agu

2011-12-01

Oxygen evolution per single-turnover flash (STF) or multiple-turnover pulse (MTP) was measured with a zirconium O(2) analyzer from sunflower leaves at 22 °C. STF were generated by Xe arc lamp, MTP by red LED light of up to 18000 μmol quanta m(-2) s(-1). Ambient O(2) concentration was 10-30 ppm, STF and MTP were superimposed on far-red background light in order to oxidize plastoquinone (PQ) and randomize S-states. Electron (e(-)) flow was calculated as 4 times O(2) evolution. Q (A) → Q (B) electron transport was investigated firing double STF with a delay of 0 to 2 ms between the two. Total O(2) evolution per two flashes equaled to that from a single flash when the delay was zero and doubled when the delay exceeded 2 ms. This trend was fitted with two exponentials with time constants of 0.25 and 0.95 ms, equal amplitudes. Illumination with MTP of increasing length resulted in increasing O(2) evolution per pulse, which was differentiated with an aim to find the time course of O(2) evolution with sub-millisecond resolution. At the highest pulse intensity of 2.9 photons ms(-1) per PSII, 3 e(-) initially accumulated inside PSII and the catalytic rate of PQ reduction was determined from the throughput rate of the fourth and fifth e(-). A light response curve for the reduction of completely oxidized PQ was a rectangular hyperbola with the initial slope of 1.2 PSII quanta per e(-) and V (m) of 0.6 e(-) ms(-1) per PSII. When PQ was gradually reduced during longer MTP, V (m) decreased proportionally with the fraction of oxidized PQ. It is suggested that the linear kinetics with respect to PQ are apparent, caused by strong product inhibition due to about equal binding constants of PQ and PQH(2) to the Q (B) site. The strong product inhibition is an appropriate mechanism for down-regulation of PSII electron transport in accordance with rate of PQH(2) oxidation by cytochrome b(6)f. © Springer Science+Business Media B.V. 2011

Bio-optical characteristics along the Straits of Magallanes

NASA Astrophysics Data System (ADS)

Lutz, Vivian; Frouin, Robert; Negri, Rubén; Silva, Ricardo; Pompeu, Mayza; Rudorff, Natalia; Cabral, Anderson; Dogliotti, Ana; Martinez, Gustavo

2016-05-01

The Straits of Magallanes at the tip of South America connects the Atlantic and Pacific Oceans. The variability in the absorption characteristics by phytoplankton (aph(440)), non-pigmented particles, NPP (aNPP(440)), and chromophoric dissolved organic matter, CDOM (ay(440)), measured along the Straits in late summer 2011 (R/V Melville MV1102 cruise), was analyzed. Satellite-derived monthly PAR data showed that at the time of the cruise the western sector was exposed to a low-light environment (~ 16 mol quanta m-2d-1) while the eastern sector received higher irradiance (~ 28 mol quanta m-2d-1). In the Patagonian Shelf total absorption was dominated by phytoplankton (up to 76%; aph(440)=0.265 m-1), while in the Atlantic Sector of the Straits, the major contributor was NPP (up to 42%; aNPP(440)=0.138 m-1), and in the Pacific Sector of the Straits CDOM contributed up to 80% of the total absorption (ay(440)=0.232 m-1). These changes could be related in part to the input of fresh water from glacier melting and rain in the Pacific Sector (ay(440) vs salinity rs=-0.98). The carbon biomass (C) was composed in its majority by pico-phytoplankton and secondly by nano-phytoplankton, with exception of the Atlantic Sector where the micro-phytoplankton dominated. Carbon to chlorophyll-a ratios (C:Chla) were very low throughout the Straits (average of ~ 6) because of photoacclimation to the extremely low light. Complementary pigments data obtained in spring 2003 by the BEAGLE expedition indicated the predominance of diatoms all along the Straits, but the bio-optical trend resembled the one found in late summer 2011, i.e., NPP dominated the absorption in the well mixed Atlantic Sector, phytoplankton in the Middle Sector, and CDOM in the Pacific Sector. These results emphasize that underwater light is the major factor affecting phytoplankton growth and physiology, and that prevalent physical and geochemical conditions play an important role regulating the bio-optical properties in

Simultaneous observation of the quantization and the interference pattern of a plasmonic near-field

DOE PAGES

Piazza, L.; Lummen, T. T. A.; Quiñonez, E.; ...

2015-03-02

Surface plasmon polaritons can confine electromagnetic fields in subwavelength spaces and are of interest for photonics, optical data storage devices and biosensing applications. In analogy to photons, they exhibit wave–particle duality, whose different aspects have recently been observed in separate tailored experiments. Here we demonstrate the ability of ultrafast transmission electron microscopy to simultaneously image both the spatial interference and the quantization of such confined plasmonic fields. Our experiments are accomplished by spatiotemporally overlapping electron and light pulses on a single nanowire suspended on a graphene film. The resulting energy exchange between single electrons and the quanta of the photoinducedmore » near-field is imaged synchronously with its spatial interference pattern. In conclusion, this methodology enables the control and visualization of plasmonic fields at the nanoscale, providing a promising tool for understanding the fundamental properties of confined electromagnetic fields and the development of advanced photonic circuits.« less

Supersymmetric interactions of a six-dimensional self-dual tensor and fixed-shape second quantized strings

NASA Astrophysics Data System (ADS)

Ganor, Ori J.

2018-02-01

"Curvepole (2,0)-theory" is a deformation of the (2,0)-theory with nonlocal interactions. A curvepole is defined as a two-dimensional generalization of a dipole. It is an object of fixed two-dimensional shape of which the boundary is a charged curve that interacts with a 2-form gauge field. Curvepole theory was previously only defined indirectly via M-theory. Here, we propose a supersymmetric Lagrangian, constructed explicitly up to quartic terms, for an "Abelian" curvepole theory, which is an interacting deformation of the free (2,0) tensor multiplet. This theory contains fields of which the quanta are curvepoles (i.e., fixed-shape strings). Supersymmetry is preserved (at least up to quartic terms) if the shape of the curvepoles is (two-dimensional) planar. This nonlocal six-dimensional quantum field theory may also serve as a UV completion for certain (local) five-dimensional gauge theories.

Heat transport through atomic contacts.

PubMed

Mosso, Nico; Drechsler, Ute; Menges, Fabian; Nirmalraj, Peter; Karg, Siegfried; Riel, Heike; Gotsmann, Bernd

2017-05-01

Heat transport and dissipation at the nanoscale severely limit the scaling of high-performance electronic devices and circuits. Metallic atomic junctions serve as model systems to probe electrical and thermal transport down to the atomic level as well as quantum effects that occur in one-dimensional (1D) systems. Whereas charge transport in atomic junctions has been studied intensively in the past two decades, heat transport remains poorly characterized because it requires the combination of a high sensitivity to small heat fluxes and the formation of stable atomic contacts. Here we report heat-transfer measurements through atomic junctions and analyse the thermal conductance of single-atom gold contacts at room temperature. Simultaneous measurements of charge and heat transport reveal the proportionality of electrical and thermal conductance, quantized with the respective conductance quanta. This constitutes a verification of the Wiedemann-Franz law at the atomic scale.

Medium-Induced QCD Cascade: Democratic Branching and Wave Turbulence

NASA Astrophysics Data System (ADS)

Blaizot, J.-P.; Iancu, E.; Mehtar-Tani, Y.

2013-08-01

We study the average properties of the gluon cascade generated by an energetic parton propagating through a quark-gluon plasma. We focus on the soft, medium-induced emissions which control the energy transport at large angles with respect to the leading parton. We show that the effect of multiple branchings is important. In contrast with what happens in a usual QCD cascade in vacuum, medium-induced branchings are quasidemocratic, with offspring gluons carrying sizable fractions of the energy of their parent gluon. This results in an efficient mechanism for the transport of energy toward the medium, which is akin to wave turbulence with a scaling spectrum ˜1/ω. We argue that the turbulent flow may be responsible for the excess energy carried by very soft quanta, as revealed by the analysis of the dijet asymmetry observed in Pb-Pb collisions at the LHC.

GAS EXCHANGE OF ALGAE. I. EFFECTS OF TIME, LIGHT INTENSITY, AND SPECTRAL-ENERGY DISTRIBUTION ON THE PHOTOSYNTHETIC QUOTIENT OF CHLORELLA PYRENOIDOSA.

PubMed

AMMANN, E C; LYNCH, V H

1965-07-01

Continuously growing cultures of Chlorella pyrenoidosa Starr 252, operating at constant density and under constant environmental conditions, produced uniform photosynthetic quotient (PQ = CO(2)/O(2)) and O(2) values during 6 months of observations. The PQ for the entire study was 0.90 +/- 0.024. The PQ remained constant over a threefold light-intensity change and a threefold change in O(2) production (0.90 +/- 0.019). At low light intensities, when the rate of respiration approached the rate of photosynthesis, the PQ became extremely variable. Six lamps of widely different spectral-energy distribution produced no significant change in the PQ (0.90 +/- 0.025). Oxygen production was directly related to the number of quanta available, irrespective of spectral-energy distribution. Such dependability in producing uniform PQ and O(2) values warrants a consideration of algae to maintain a constant gas environment for submarine or spaceship use.

Physics of Gravitational Interaction: Geometry of Space or Quantum Field in Space

NASA Astrophysics Data System (ADS)

Baryshev, Yurij

2006-03-01

Thirring-Feynman's tensor field approach to gravitation opens new understanding on the physics of gravitational interaction and stimulates novel experiments on the nature of gravity. According to Field Gravity, the universal gravity force is caused by exchange of gravitons - the quanta of gravity field. Energy of this field is well-defined and excludes the singularity. All classical relativistic effects are the same as in General Relativity. The intrinsic scalar (spin 0) part of gravity field corresponds to ``antigravity'' and only together with the pure tensor (spin 2) part gives the usual Newtonian force. Laboratory and astrophysical experiments which may test the predictions of FG, will be performed in near future. In particular, observations at gravity observatories with bar and interferometric detectors, like Explorer, Nautilus, LIGO and VIRGO, will check the predicted scalar gravitational waves from supernova explosions. New types of cosmological models in Minkowski space are possible too.

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

Lisitsyn, V. M.; Stepanov, S. A., E-mail: stepanovsa@tpu.ru; Yangyang, Ju

In most promising widespread gallium nitride based LEDs emission is generated in the blue spectral region with a maximum at about 450 nm which is converted to visible light with the desired spectrum by means of phosphor. The thermal energy in the conversion is determined by the difference in the energies of excitation and emission quanta and the phosphor quantum yield. Heat losses manifest themselves as decrease in the luminous efficacy. LED heating significantly reduces its efficiency and life. In addition, while heating, the emission generation output and the efficiency of the emission conversion decrease. Therefore, the reduction of the energymore » losses caused by heating is crucial for LED development. In this paper, heat losses in phosphor-converted LEDs (hereinafter chips) during spectrum conversion are estimated. The limit values of the luminous efficacy for white LEDs are evaluated.« less

DQE analysis for CCD imaging arrays

NASA Astrophysics Data System (ADS)

Shaw, Rodney

1997-05-01

By consideration of the statistical interaction between exposure quanta and the mechanisms of image detection, the signal-to-noise limitations of a variety of image acquisition technologies are now well understood. However in spite of the growing fields of application for CCD imaging- arrays and the obvious advantages of their multi-level mode of quantum detection, only limited and largely empirical approaches have been made to quantify these advantages on an absolute basis. Here an extension is made of a previous model for noise-free sequential photon-counting to the more general case involving both count-noise and arbitrary separation functions between count levels. This allows a basic model to be developed for the DQE associated with devices which approximate to the CCD mode of operation, and conclusions to be made concerning the roles of the separation-function and count-noise in defining the departure from the ideal photon counter.

Origin of a signal detected with the LSD detector after the accident at the chernobyl nuclear power plant

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

Agafonova, N. Yu., E-mail: natagafonova@gmail.com; Malgin, A. S., E-mail: malgin@lngs.infn.it; Fulgione, W.

A rare signal was detected at 23:53 Moscow time on April 27, 1986 with the LSD low-background scintillation detector located under Mont Blanc at a distance of 1820 km from Chernobyl. To reveal the origin of this signal, we discuss the results obtained with other instruments operating within a similar program, as well as analyze the characteristics of the pulses of the signal and facts referring to the explosion of the Chernobyl reactor. A hypothesis based on detection with the LSD of gamma-quanta from {beta} decays of {sup 135}I nuclei ejected into atmosphere by the reactor explosion and carried inmore » the underground detector camera with air of positive ventilation is considered. The explosion origin of the LSD signal indicates a new technogenic source of the background in the search for neutrino bursts from cores of collapsing stars.« less

Full-Counting Many-Particle Dynamics: Nonlocal and Chiral Propagation of Correlations

NASA Astrophysics Data System (ADS)

Ashida, Yuto; Ueda, Masahito

2018-05-01

The ability to measure single quanta allows the complete characterization of small quantum systems known as full-counting statistics. Quantum gas microscopy enables one to observe many-body systems at the single-atom precision. We extend the idea of full-counting statistics to nonequilibrium open many-particle dynamics and apply it to discuss the quench dynamics. By way of illustration, we consider an exactly solvable model to demonstrate the emergence of unique phenomena such as nonlocal and chiral propagation of correlations, leading to a concomitant oscillatory entanglement growth. We find that correlations can propagate beyond the conventional maximal speed, known as the Lieb-Robinson bound, at the cost of probabilistic nature of quantum measurement. These features become most prominent at the real-to-complex spectrum transition point of an underlying parity-time-symmetric effective non-Hermitian Hamiltonian. A possible experimental situation with quantum gas microscopy is discussed.

Fine structure constant and quantized optical transparency of plasmonic nanoarrays.

PubMed

Kravets, V G; Schedin, F; Grigorenko, A N

2012-01-24

Optics is renowned for displaying quantum phenomena. Indeed, studies of emission and absorption lines, the photoelectric effect and blackbody radiation helped to build the foundations of quantum mechanics. Nevertheless, it came as a surprise that the visible transparency of suspended graphene is determined solely by the fine structure constant, as this kind of universality had been previously reserved only for quantized resistance and flux quanta in superconductors. Here we describe a plasmonic system in which relative optical transparency is determined solely by the fine structure constant. The system consists of a regular array of gold nanoparticles fabricated on a thin metallic sublayer. We show that its relative transparency can be quantized in the near-infrared, which we attribute to the quantized contact resistance between the nanoparticles and the metallic sublayer. Our results open new possibilities in the exploration of universal dynamic conductance in plasmonic nanooptics.

A reflection on theories of light

NASA Astrophysics Data System (ADS)

Quehenberger, R. C. Z.

2012-12-01

Insights into the foundations of quantum theory, including the wave-particle duality of light as developed in the last century, raise several questions. How can we imagine light both as wave and particle? What is a particle? How can we make comprehensible the phenomenon of light as elec-tromagnetic distortion, incorporating the ideas of Maxwell, Faraday and especially Theodor Kaluza, who placed light in 5-dimensional space? We investigate a 3D digital dynamic geometrical model applied to theories of light in order to provide a visual access for a better mathematical understanding. Hence to achieve this convergence of theories, we examine experimental facts of the famous entangled photon picture and theories of lines of force with AR methods to bring together the notion of "light quanta" and their connection to a discrete space structure in 5D. Examples of 3D animation are here depicted as still frames.

Total Reaction Cross Section Excitation Function Studies for 6He Interaction with 181Ta, 59Co, natSi, 9Be Nuclei

NASA Astrophysics Data System (ADS)

Sobolev, Yu. G.; Penionzhkevich, Yu. E.; Borcea, C.; Demekhina, N. A.; Eshanov, A. G.; Ivanov, M. P.; Kabdrakhimova, G. D.; Kabyshev, A. M.; Kugler, A.; Kuterbekov, K. A.; Lukyanov, K. V.; Maj, A.; Maslov, V. A.; Negret, A.; Skobelev, N. K.; Testov, D.; Trzaska, W. H.; Voskobojnik, E. I.; Zemlyanaya, E. V.

2015-06-01

Total reaction cross section excitation functions σR(E) were measured for 6He secondary beam particles on 181Ta, 59Co, natSi and 9Be targets in a wide energy range by direct and model-independent method. This experimental method was based on prompt n-γ 4π-technique applied in event-by event mode. A high efficiency CsI(Tl) γ-spectrometer was used for the detection of reaction products (prompt γ-quanta and neutrons) accompanying each reaction event. Using the ACCULINNA fragment-separator 6He fragments (produced by 11B primary beam with 9Be target) are separated and transported to n-γ shielded experimental cave at FLNR JINR. The measured total reaction cross section data σR(E) for the above mentioned reactions are compared with a theoretical calculation based on the optical potential with the real part having the double-folding form.

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

Patil, Vidya, E-mail: vidya.patil@ruparel.edu; Patki, Mugdha, E-mail: mugdha.patki@ruparel.edu

Many nonlinear optical (NLO) crystals have been identified as potential candidates in optical and electro-optical devices. Use of NLO organic crystals is expected in photonic applications. Hence organic nonlinear optical materials have been intensely investigated due to their potentially high nonlinearities, and rapid response in electro-optic effect compared to inorganic NLO materials. There are many methods to grow organic crystals such as vapor growth method, melt growth method and solution growth method. Out of these methods, solution growth method is useful in providing constraint free crystal. Single crystals of Dopamine have been grown by evaporating the solvents from aqueous solution.more » Crystals obtained were of the size of orders of mm. The crystal structure of dopamine was determined using XRD technique. Images of crystals were obtained using FEG SEM Quanta Series under high vacuum and low KV.« less

Phase-to-intensity conversion of magnonic spin currents and application to the design of a majority gate

PubMed Central

Brächer, T.; Heussner, F.; Pirro, P.; Meyer, T.; Fischer, T.; Geilen, M.; Heinz, B.; Lägel, B.; Serga, A. A.; Hillebrands, B.

2016-01-01

Magnonic spin currents in the form of spin waves and their quanta, magnons, are a promising candidate for a new generation of wave-based logic devices beyond CMOS, where information is encoded in the phase of travelling spin-wave packets. The direct readout of this phase on a chip is of vital importance to couple magnonic circuits to conventional CMOS electronics. Here, we present the conversion of the spin-wave phase into a spin-wave intensity by local non-adiabatic parallel pumping in a microstructure. This conversion takes place within the spin-wave system itself and the resulting spin-wave intensity can be conveniently transformed into a DC voltage. We also demonstrate how the phase-to-intensity conversion can be used to extract the majority information from an all-magnonic majority gate. This conversion method promises a convenient readout of the magnon phase in future magnon-based devices. PMID:27905539

Simultaneous observation of the quantization and the interference pattern of a plasmonic near-field

PubMed Central

Piazza, L; Lummen, T.T.A.; Quiñonez, E; Murooka, Y; Reed, B.W.; Barwick, B; Carbone, F

2015-01-01

Surface plasmon polaritons can confine electromagnetic fields in subwavelength spaces and are of interest for photonics, optical data storage devices and biosensing applications. In analogy to photons, they exhibit wave–particle duality, whose different aspects have recently been observed in separate tailored experiments. Here we demonstrate the ability of ultrafast transmission electron microscopy to simultaneously image both the spatial interference and the quantization of such confined plasmonic fields. Our experiments are accomplished by spatiotemporally overlapping electron and light pulses on a single nanowire suspended on a graphene film. The resulting energy exchange between single electrons and the quanta of the photoinduced near-field is imaged synchronously with its spatial interference pattern. This methodology enables the control and visualization of plasmonic fields at the nanoscale, providing a promising tool for understanding the fundamental properties of confined electromagnetic fields and the development of advanced photonic circuits. PMID:25728197

Asynchronous discrete event schemes for PDEs

NASA Astrophysics Data System (ADS)

Stone, D.; Geiger, S.; Lord, G. J.

2017-08-01

A new class of asynchronous discrete-event simulation schemes for advection-diffusion-reaction equations is introduced, based on the principle of allowing quanta of mass to pass through faces of a (regular, structured) Cartesian finite volume grid. The timescales of these events are linked to the flux on the face. The resulting schemes are self-adaptive, and local in both time and space. Experiments are performed on realistic physical systems related to porous media flow applications, including a large 3D advection diffusion equation and advection diffusion reaction systems. The results are compared to highly accurate reference solutions where the temporal evolution is computed with exponential integrator schemes using the same finite volume discretisation. This allows a reliable estimation of the solution error. Our results indicate a first order convergence of the error as a control parameter is decreased, and we outline a framework for analysis.

Entropy Conservation of Linear Dilaton Black Holes in Quantum Corrected Hawking Radiation

NASA Astrophysics Data System (ADS)

Sakalli, I.; Halilsoy, M.; Pasaoglu, H.

2011-10-01

It has been shown recently that information is lost in the Hawking radiation of the linear dilaton black holes in various theories when applying the tunneling formalism of Parikh and Wilczek without considering quantum gravity effects. In this paper, we recalculate the emission probability by taking into account the log-area correction to the Bekenstein-Hawking entropy and the statistical correlation between quanta emitted. The crucial role of the quantum gravity effects on the information leakage and black hole remnant is highlighted. The entropy conservation of the linear dilaton black holes is discussed in detail. We also model the remnant as an extreme linear dilaton black hole with a pointlike horizon in order to show that such a remnant cannot radiate and its temperature becomes zero. In summary, we show that the information can also leak out of the linear dilaton black holes together with preserving unitarity in quantum mechanics.

[Radiobiological effects of total mice irradiation with Bragg's peak protons].

PubMed

Ivanov, A A; Molokanov, A G; Ushakov, I B; Bulynina, T M; Vorozhtsova, S V; Abrosimova, A N; Kryuchkova, D M; Gaevsky, V N

2013-01-01

Outbred CD-1 female mice were irradiated in a proton beam (171 MeV, 5 Gy) on the phasotron at the Joint Institute of Nuclear Research (Dubna, Russia). Radiation was delivered in two points of the depth dose distribution: at the beam entry and on Bragg's peak. Technical requirements for studying the effects of Bragg's peak protons on organism of experimental animals were specified. It was recognized that protons with high linear energy transfer (mean LET = 1.6 keV/microm) cause a more severe damaging effect to the hemopoietic system and cytogenetic apparatus in bone marrow cells as compared with entry protons and 60Co gamma-quanta. It was shown that recovery of the main hemopoietic organs and immunity as well as elimination of chromosomal aberrations take more time following irradiation with Bragg's peak protons but not protons with the energy of 171 MeV.

Readily releasable pool of synaptic vesicles measured at single synaptic contacts.

PubMed

Trigo, Federico F; Sakaba, Takeshi; Ogden, David; Marty, Alain

2012-10-30

To distinguish between different models of vesicular release in brain synapses, it is necessary to know the number of vesicles of transmitter that can be released immediately at individual synapses by a high-calcium stimulus, the readily releasable pool (RRP). We used direct stimulation by calcium uncaging at identified, single-site inhibitory synapses to investigate the statistics of vesicular release and the size of the RRP. Vesicular release, detected as quantal responses in the postsynaptic neuron, showed an unexpected stochastic variation in the number of quanta from stimulus to stimulus at high intracellular calcium, with a mean of 1.9 per stimulus and a maximum of three or four. The results provide direct measurement of the RRP at single synaptic sites. They are consistent with models in which release proceeds from a small number of vesicle docking sites with an average occupancy around 0.7.

Generation of Langmuir wave supercontinuum by phase-preserving equilibration of plasmons with irreversible wave-particle interaction

NASA Astrophysics Data System (ADS)

Eiichirou, Kawamori

2018-04-01

We report the observation of supercontinuum of Langmuir plasma waves, that exhibits broad power spectrum having significant spatio-temporal coherence grown from a monochromatic seed-wave, in one-dimensional particle-in-cell simulations. The Langmuir wave supercontinuum (LWSC) is formed when the seed wave excites side-band fields efficiently by the modulational instabilities. Its identification is achieved by the use of the tricoherence analysis, which detects four wave mixings (FWMs) of plasmons (plasma wave quanta), and evaluation of the first order coherence, which is a measure of temporal coherence, of the wave electric fields. The irreversible evolution to the coherent LWSC from the seed wave is realized by the wave-particle interactions causing stochastic electron motions in the phase space and the coherence of LWSC is maintained by the phase-preserving FWMs of plasmons. The LWSC corresponds to a quasi Bernstein-Greene-Kruskal mode.

Some problems of the detection of the high energy gamma-radiation in space

NASA Astrophysics Data System (ADS)

Fradkin, M. I.; Ginzburg, V. L.; Kurnosova, L. V.; Labensky, A. G.; Razorenov, L. A.; Rusakovich, M. A.; Topchiev, N. P.; Kaplin, V. A.; Runtso, M. F.; Gorchakov, E. V.; Ignatiev, P. P.

1995-05-01

Diffuse gamma radiation in the Galaxy has been measured with instruments onboard the COS-B and Compton Gamma Ray Observatory (CGRO) satellites from the tens of keV up to about 30 GeV. There is no experimental data at higher energies, but this data is very important for the spectrum of primary cosmic rays and the existence of neutralinos (hypothetical supersymmetrical particles which are supposed to constitute dark matter in the Galaxy and create gamma-quanta in the process of annihilation). The GAMMA-400 collaboration is working on the design of a telescope for gamma-ray measurements in the 10-1000 GeV range. The electronics of the GAMMA-400 eliminate some hindering effects, in particular the influence of backscattered gammas emitted by the very massive calorimeter (calorimeter albedo). The GAMMA-400 project may be realized in the near future if economic conditions in Russia are favorable.

Auroral nitric oxide concentration and infrared emission

NASA Astrophysics Data System (ADS)

Reidy, W. P.; Degges, T. C.; Hurd, A. G.; Stair, A. T., Jr.; Ulwick, J. C.

1982-05-01

Rocket-borne measurements of infrared auroral emission by nitric oxide are analyzed. Four rocket flights provided opportunities to measure 5.3- and 2.7-micron NO emission by means of infrared fixed band radiometers and CVF spectrometers, narrow band photometers, and incident energy spectra on various occasions. Analysis of infrared emission profiles and electron flux data indicates the NO density to be significantly enhanced with respect to midlatitude values. NO emission in the fundamental 5.3-micron band is attributed to resonance excitation by warm earth radiation, collisional excitation primarily by O atoms and chemiluminescence from the reaction of N with O2; with an energy efficiency of 0.015. The overtone band emission at 2.7 microns is accounted for by chemiluminescence produced with an energy efficiency of 0.0054. Total photon yield for the chemiluminescence reaction is estimated to range from 1.2 to 2.4 vibrational quanta per NO molecule.

Metamaterial bricks and quantization of meta-surfaces

PubMed Central

Memoli, Gianluca; Caleap, Mihai; Asakawa, Michihiro; Sahoo, Deepak R.; Drinkwater, Bruce W.; Subramanian, Sriram

2017-01-01

Controlling acoustic fields is crucial in diverse applications such as loudspeaker design, ultrasound imaging and therapy or acoustic particle manipulation. The current approaches use fixed lenses or expensive phased arrays. Here, using a process of analogue-to-digital conversion and wavelet decomposition, we develop the notion of quantal meta-surfaces. The quanta here are small, pre-manufactured three-dimensional units—which we call metamaterial bricks—each encoding a specific phase delay. These bricks can be assembled into meta-surfaces to generate any diffraction-limited acoustic field. We apply this methodology to show experimental examples of acoustic focusing, steering and, after stacking single meta-surfaces into layers, the more complex field of an acoustic tractor beam. We demonstrate experimentally single-sided air-borne acoustic levitation using meta-layers at various bit-rates: from a 4-bit uniform to 3-bit non-uniform quantization in phase. This powerful methodology dramatically simplifies the design of acoustic devices and provides a key-step towards realizing spatial sound modulators. PMID:28240283

Vibronic coupling effect on the electron transport through molecules

NASA Astrophysics Data System (ADS)

Tsukada, Masaru; Mitsutake, Kunihiro

2007-03-01

Electron transport through molecular bridges or molecular layers connected to nano-electrodes is determined by the combination of coherent and dissipative processes, controlled by the electron-vibron coupling, transfer integrals between the molecular orbitals, applied electric field and temperature. We propose a novel theoretical approach, which combines ab initio molecular orbital method with analytical many-boson model. As a case study, the long chain model of the thiophene oligomer is solved by a variation approach. Mixed states of moderately extended molecular orbital states mediated and localised by dress of vibron cloud are found as eigen-states. All the excited states accompanied by multiple quanta of vibration can be solved, and the overall carrier transport properties including the conductance, mobility, dissipation spectra are analyzed by solving the master equation with the transition rates estimated by the golden rule. We clarify obtained in a uniform systematic way, how the transport mode changes from a dominantly coherent transport to the dissipative hopping transport.

Resolving the vacuum fluctuations of an optomechanical system using an artificial atom

NASA Astrophysics Data System (ADS)

Lecocq, F.; Teufel, J. D.; Aumentado, J.; Simmonds, R. W.

2015-08-01

Heisenberg’s uncertainty principle results in one of the strangest quantum behaviours: a mechanical oscillator can never truly be at rest. Even at a temperature of absolute zero, its position and momentum are still subject to quantum fluctuations. However, direct energy detection of the oscillator in its ground state makes it seem motionless, and in linear position measurements detector noise can masquerade as mechanical fluctuations. Thus, how can we resolve quantum fluctuations? Here, we parametrically couple a micromechanical oscillator to a microwave cavity to prepare the system in its quantum ground state and then amplify the remaining vacuum fluctuations into real energy quanta. We monitor the photon/phonon-number distributions using a superconducting qubit, allowing us to resolve the quantum vacuum fluctuations of the macroscopic oscillator’s motion. Our results further demonstrate the ability to control a long-lived mechanical oscillator using a non-Gaussian resource, directly enabling applications in quantum information processing and enhanced detection of displacement and forces.

Reconfigurable nanoscale spin-wave directional coupler

PubMed Central

Wang, Qi; Pirro, Philipp; Verba, Roman; Slavin, Andrei; Hillebrands, Burkard; Chumak, Andrii V.

2018-01-01

Spin waves, and their quanta magnons, are prospective data carriers in future signal processing systems because Gilbert damping associated with the spin-wave propagation can be made substantially lower than the Joule heat losses in electronic devices. Although individual spin-wave signal processing devices have been successfully developed, the challenging contemporary problem is the formation of two-dimensional planar integrated spin-wave circuits. Using both micromagnetic modeling and analytical theory, we present an effective solution of this problem based on the dipolar interaction between two laterally adjacent nanoscale spin-wave waveguides. The developed device based on this principle can work as a multifunctional and dynamically reconfigurable signal directional coupler performing the functions of a waveguide crossing element, tunable power splitter, frequency separator, or multiplexer. The proposed design of a spin-wave directional coupler can be used both in digital logic circuits intended for spin-wave computing and in analog microwave signal processing devices. PMID:29376117

X-ray Generation in Strongly Nonlinear Plasma Waves

NASA Astrophysics Data System (ADS)

Kiselev, S.; Pukhov, A.; Kostyukov, I.

2004-09-01

We show that a laser wake field in the “bubble” regime [

Observation of b 2 symmetry vibrational levels of the SO 2C 1B 2 state: Vibrational level staggering, Coriolis interactions, and rotation-vibration constants

DOE PAGES

Park, G. Barratt; Jiang, Jun; Saladrigas, Catherine A.; ...

2016-04-14

Here, the C 1B 2 state of SO 2 has a double-minimum potential in the antisymmetric stretch coordinate, such that the minimum energy geometry has nonequivalent SO bond lengths. However, low-lying levels with odd quanta of antisymmetric stretch (b 2 vibrational symmetry) have not previously been observed because transitions into these levels from the zero-point level of the X ~ state are vibronically forbidden. We use IR-UV double resonance to observe the b 2 vibrational levels of the C state below 1600 cm –1 of vibrational excitation. This enables a direct characterization of the vibrational level staggering that results frommore » the double-minimum potential. In addition, it allows us to deperturb the strong c-axis Coriolis interactions between levels of a 1 and b 2 vibrational symmetry, and to determine accurately the vibrational dependence of the rotational constants in the distorted C electronic state.« less

Observation of b 2 symmetry vibrational levels of the SO 2C 1B 2 state: Vibrational level staggering, Coriolis interactions, and rotation-vibration constants

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

Park, G. Barratt; Jiang, Jun; Saladrigas, Catherine A.

Here, the C 1B 2 state of SO 2 has a double-minimum potential in the antisymmetric stretch coordinate, such that the minimum energy geometry has nonequivalent SO bond lengths. However, low-lying levels with odd quanta of antisymmetric stretch (b 2 vibrational symmetry) have not previously been observed because transitions into these levels from the zero-point level of the X ~ state are vibronically forbidden. We use IR-UV double resonance to observe the b 2 vibrational levels of the C state below 1600 cm –1 of vibrational excitation. This enables a direct characterization of the vibrational level staggering that results frommore » the double-minimum potential. In addition, it allows us to deperturb the strong c-axis Coriolis interactions between levels of a 1 and b 2 vibrational symmetry, and to determine accurately the vibrational dependence of the rotational constants in the distorted C electronic state.« less

Network-Physics (NP) BEC DIGITAL(#)-VULNERABILITY; ``Q-Computing"=Simple-Arithmetic;Modular-Congruences=SignalXNoise PRODUCTS=Clock-model;BEC-Factorization;RANDOM-# Definition;P=/=NP TRIVIAL Proof!!!

NASA Astrophysics Data System (ADS)

Pi, E. I.; Siegel, E.

2010-03-01

Siegel[AMS Natl.Mtg.(2002)-Abs.973-60-124] digits logarithmic- law inversion to ONLY BEQS BEC:Quanta/Bosons=#: EMP-like SEVERE VULNERABILITY of ONLY #-networks(VS.ANALOG INvulnerability) via Barabasi NP(VS.dynamics[Not.AMS(5/2009)] critique);(so called)``quantum-computing''(QC) = simple-arithmetic (sansdivision);algorithmiccomplexities:INtractibility/UNdecidabi lity/INefficiency/NONcomputability/HARDNESS(so MIScalled) ``noise''-induced-phase-transition(NIT)ACCELERATION:Cook-Levin theorem Reducibility = RG fixed-points; #-Randomness DEFINITION via WHAT? Query(VS. Goldreich[Not.AMS(2002)] How? mea culpa)= ONLY MBCS hot-plasma v #-clumping NON-random BEC; Modular-Arithmetic Congruences = Signal x Noise PRODUCTS = clock-model; NON-Shor[Physica A,341,586(04)]BEC logarithmic-law inversion factorization: Watkins #-theory U statistical- physics); P=/=NP C-S TRIVIAL Proof: Euclid!!! [(So Miscalled) computational-complexity J-O obviation(3 millennia AGO geometry: NO:CC,``CS'';``Feet of Clay!!!'']; Query WHAT?:Definition: (so MIScalled)``complexity''=UTTER-SIMPLICITY!! v COMPLICATEDNESS MEASURE(S).

Network-Physics(NP) Bec DIGITAL(#)-VULNERABILITY Versus Fault-Tolerant Analog

NASA Astrophysics Data System (ADS)

Alexander, G. K.; Hathaway, M.; Schmidt, H. E.; Siegel, E.

2011-03-01

Siegel[AMS Joint Mtg.(2002)-Abs.973-60-124] digits logarithmic-(Newcomb(1881)-Weyl(1914; 1916)-Benford(1938)-"NeWBe"/"OLDbe")-law algebraic-inversion to ONLY BEQS BEC:Quanta/Bosons= digits: Synthesis reveals EMP-like SEVERE VULNERABILITY of ONLY DIGITAL-networks(VS. FAULT-TOLERANT ANALOG INvulnerability) via Barabasi "Network-Physics" relative-``statics''(VS.dynamics-[Willinger-Alderson-Doyle(Not.AMS(5/09)]-]critique); (so called)"Quantum-computing is simple-arithmetic(sans division/ factorization); algorithmic-complexities: INtractibility/ UNdecidability/ INefficiency/NONcomputability / HARDNESS(so MIScalled) "noise"-induced-phase-transitions(NITS) ACCELERATION: Cook-Levin theorem Reducibility is Renormalization-(Semi)-Group fixed-points; number-Randomness DEFINITION via WHAT? Query(VS. Goldreich[Not.AMS(02)] How? mea culpa)can ONLY be MBCS "hot-plasma" versus digit-clumping NON-random BEC; Modular-arithmetic Congruences= Signal X Noise PRODUCTS = clock-model; NON-Shor[Physica A,341,586(04)] BEC logarithmic-law inversion factorization:Watkins number-thy. U stat.-phys.); P=/=NP TRIVIAL Proof: Euclid!!! [(So Miscalled) computational-complexity J-O obviation via geometry.

Modified dark matter: Relating dark energy, dark matter and baryonic matter

NASA Astrophysics Data System (ADS)

Edmonds, Douglas; Farrah, Duncan; Minic, Djordje; Ng, Y. Jack; Takeuchi, Tatsu

Modified dark matter (MDM) is a phenomenological model of dark matter, inspired by gravitational thermodynamics. For an accelerating universe with positive cosmological constant (Λ), such phenomenological considerations lead to the emergence of a critical acceleration parameter related to Λ. Such a critical acceleration is an effective phenomenological manifestation of MDM, and it is found in correlations between dark matter and baryonic matter in galaxy rotation curves. The resulting MDM mass profiles, which are sensitive to Λ, are consistent with observational data at both the galactic and cluster scales. In particular, the same critical acceleration appears both in the galactic and cluster data fits based on MDM. Furthermore, using some robust qualitative arguments, MDM appears to work well on cosmological scales, even though quantitative studies are still lacking. Finally, we comment on certain nonlocal aspects of the quanta of modified dark matter, which may lead to novel nonparticle phenomenology and which may explain why, so far, dark matter detection experiments have failed to detect dark matter particles.

a Portable Pixel Detector Operating as AN Active Nuclear Emulsion and its Application for X-Ray and Neutron Tomography

NASA Astrophysics Data System (ADS)

Vykydal, Z.; Jakubek, J.; Holy, T.; Pospisil, S.

2006-04-01

This work is devoted to the development of a USB1.1 (Universal Serial Bus) based read out system for the Medipix2 detector to achieve maximum portability of this position sensitive detecting device. All necessary detector support is integrated into one compact system (80 × 50 × 20 mm3) including the detector bias source (up to 100 V). The read out interface can control external I2C based devices, so in case of tomography it is easy to synchronize detector shutter with stepper motor control. An additional significant advantage of the USB interface is the support of back side pulse processing. This feature enables to determine the energy additionally to the position of a heavy charged particle hitting the sensor. Due to the small pixel dimensions it is also possible to distinguish the type of single quanta of radiation from the track created in the pixel detector as in case of an active nuclear emulsion.

Metamaterial bricks and quantization of meta-surfaces

NASA Astrophysics Data System (ADS)

Memoli, Gianluca; Caleap, Mihai; Asakawa, Michihiro; Sahoo, Deepak R.; Drinkwater, Bruce W.; Subramanian, Sriram

2017-02-01

Controlling acoustic fields is crucial in diverse applications such as loudspeaker design, ultrasound imaging and therapy or acoustic particle manipulation. The current approaches use fixed lenses or expensive phased arrays. Here, using a process of analogue-to-digital conversion and wavelet decomposition, we develop the notion of quantal meta-surfaces. The quanta here are small, pre-manufactured three-dimensional units--which we call metamaterial bricks--each encoding a specific phase delay. These bricks can be assembled into meta-surfaces to generate any diffraction-limited acoustic field. We apply this methodology to show experimental examples of acoustic focusing, steering and, after stacking single meta-surfaces into layers, the more complex field of an acoustic tractor beam. We demonstrate experimentally single-sided air-borne acoustic levitation using meta-layers at various bit-rates: from a 4-bit uniform to 3-bit non-uniform quantization in phase. This powerful methodology dramatically simplifies the design of acoustic devices and provides a key-step towards realizing spatial sound modulators.

A charge-driven molecular water pump.

PubMed

Gong, Xiaojing; Li, Jingyuan; Lu, Hangjun; Wan, Rongzheng; Li, Jichen; Hu, Jun; Fang, Haiping

2007-11-01

Understanding and controlling the transport of water across nanochannels is of great importance for designing novel molecular devices, machines and sensors and has wide applications, including the desalination of seawater. Nanopumps driven by electric or magnetic fields can transport ions and magnetic quanta, but water is charge-neutral and has no magnetic moment. On the basis of molecular dynamics simulations, we propose a design for a molecular water pump. The design uses a combination of charges positioned adjacent to a nanopore and is inspired by the structure of channels in the cellular membrane that conduct water in and out of the cell (aquaporins). The remarkable pumping ability is attributed to the charge dipole-induced ordering of water confined in the nanochannels, where water can be easily driven by external fields in a concerted fashion. These findings may provide possibilities for developing water transport devices that function without osmotic pressure or a hydrostatic pressure gradient.

X-ray-generated heralded macroscopical quantum entanglement of two nuclear ensembles.

PubMed

Liao, Wen-Te; Keitel, Christoph H; Pálffy, Adriana

2016-09-19

Heralded entanglement between macroscopical samples is an important resource for present quantum technology protocols, allowing quantum communication over large distances. In such protocols, optical photons are typically used as information and entanglement carriers between macroscopic quantum memories placed in remote locations. Here we investigate theoretically a new implementation which employs more robust x-ray quanta to generate heralded entanglement between two crystal-hosted macroscopical nuclear ensembles. Mössbauer nuclei in the two crystals interact collectively with an x-ray spontaneous parametric down conversion photon that generates heralded macroscopical entanglement with coherence times of approximately 100 ns at room temperature. The quantum phase between the entangled crystals can be conveniently manipulated by magnetic field rotations at the samples. The inherent long nuclear coherence times allow also for mechanical manipulations of the samples, for instance to check the stability of entanglement in the x-ray setup. Our results pave the way for first quantum communication protocols that use x-ray qubits.

Quantum tachyons

NASA Astrophysics Data System (ADS)

Tomaschitz, R.

2005-02-01

The interaction of superluminal radiation with matter in atomic bound-bound and bound-free transitions is investigated. We study transitions in the relativistic hydrogen atom effected by superluminal quanta. The superluminal radiation field is coupled by minimal substitution to the Dirac equation in a Coulomb potential. We quantize the interaction to obtain the transition matrix for induced and spontaneous superluminal radiation in hydrogen-like ions. The tachyonic photoelectric effect is scrutinized, the cross-sections for ground state ionization by transversal and longitudinal tachyons are derived. We examine the relativistic regime, high electronic ejection energies, as well as the first order correction to the non-relativistic cross-sections. In the ultra-relativistic limit, both the longitudinal and transversal cross-sections are peaked at small but noticeably different scattering angles. In the non-relativistic limit, the longitudinal cross-section has two maxima, and its minimum is located at the transversal maximum. Ionization cross-sections can thus be used to discriminate longitudinal radiation from transversal tachyons and photons.

Stable topological insulators achieved using high energy electron beams

PubMed Central

Zhao, Lukas; Konczykowski, Marcin; Deng, Haiming; Korzhovska, Inna; Begliarbekov, Milan; Chen, Zhiyi; Papalazarou, Evangelos; Marsi, Marino; Perfetti, Luca; Hruban, Andrzej; Wołoś, Agnieszka; Krusin-Elbaum, Lia

2016-01-01

Topological insulators are potentially transformative quantum solids with metallic surface states which have Dirac band structure and are immune to disorder. Ubiquitous charged bulk defects, however, pull the Fermi energy into the bulk bands, denying access to surface charge transport. Here we demonstrate that irradiation with swift (∼2.5 MeV energy) electron beams allows to compensate these defects, bring the Fermi level back into the bulk gap and reach the charge neutrality point (CNP). Controlling the beam fluence, we tune bulk conductivity from p- (hole-like) to n-type (electron-like), crossing the Dirac point and back, while preserving the Dirac energy dispersion. The CNP conductance has a two-dimensional character on the order of ten conductance quanta and reveals, both in Bi2Te3 and Bi2Se3, the presence of only two quantum channels corresponding to two topological surfaces. The intrinsic quantum transport of the topological states is accessible disregarding the bulk size. PMID:26961901

Loading a single photon into an optical cavity

NASA Astrophysics Data System (ADS)

Du, Shengwang; Liu, Chang; Sun, Yuan; Zhao, Luwei; Zhang, Shanchao; Loy, M. M. T.

2015-05-01

Confining and manipulating single photons inside a reflective optical cavity is an essential task of cavity quantum electrodynamics (CQED) for probing the quantum nature of light quanta. Such systems are also elementary building blocks for many protocols of quantum network, where remote cavity quantum nodes are coupled through flying photons. The connectivity and scalability of such a quantum network strongly depends on the efficiency of loading a single photon into cavity. In this work we demonstrate that a single photon with an optimal temporal waveform can be efficiently loaded into a cavity. Using heralded narrow-band single photons with exponential growth wave packet whose time constant matches the photon lifetime in the cavity, we demonstrate a loading efficiency of more than 87 percent from free space to a single-sided Fabry-Perot cavity. Our result and approach may enable promising applications in realizing large-scale CQED-based quantum networks. The work was supported by the Hong Kong RGC (Project No. 601411).

Gas Exchange of Algae

PubMed Central

Ammann, Elizabeth C. B.; Lynch, Victoria H.

1965-01-01

Continuously growing cultures of Chlorella pyrenoidosa Starr 252, operating at constant density and under constant environmental conditions, produced uniform photosynthetic quotient (PQ = CO2/O2) and O2 values during 6 months of observations. The PQ for the entire study was 0.90 ± 0.024. The PQ remained constant over a threefold light-intensity change and a threefold change in O2 production (0.90 ± 0.019). At low light intensities, when the rate of respiration approached the rate of photosynthesis, the PQ became extremely variable. Six lamps of widely different spectral-energy distribution produced no significant change in the PQ (0.90 ± 0.025). Oxygen production was directly related to the number of quanta available, irrespective of spectral-energy distribution. Such dependability in producing uniform PQ and O2 values warrants a consideration of algae to maintain a constant gas environment for submarine or spaceship use. Images Fig. 1 PMID:14339260

Riemann-Hypothesis Millennium-Problem(MP) Physics Proof via CATEGORY-SEMANTICS(C-S)/F=C Aristotle SQUARE-of-OPPOSITION(SoO) DEduction-LOGIC DichotomY

NASA Astrophysics Data System (ADS)

Baez, J.; Lapidaryus, M.; Siegel, Edward Carl-Ludwig

2011-03-01

Riemann-hypothesis physics-proof combines: Siegel-Antonoff-Smith[AMS Joint Mtg.(2002)-Abs.973-03-126] digits on-average statistics HIll[Am. J. Math 123, 3, 887(1996)] logarithm-function's (1,0)-fixed-point base=units=scale-invariance proven Newcomb[Am. J. Math. 4, 39(1881)]-Weyl[Goett. Nachr.(1914); Math. Ann. 7, 313(1916)]-Benford[Proc. Am. Phil. Soc. 78, 4, 51(1938)]-law [Kac, Math. of Stat.-Reasoning(1955); Raimi, Sci. Am. 221, 109(1969)] algebraic-inversion to ONLY Bose-Einstein quantum-statistics(BEQS) with digit d = 0 gapFUL Bose-Einstein Condensation(BEC) insight that digits are quanta are bosons were always digits, via Siegel-Baez category-semantics tabular list-format matrix truth-table analytics in Plato-Aristotle classic "square-of-opposition" : FUZZYICS=CATEGORYICS/Category-Semantics, with Goodkind Bose-Einstein condensation(BEC) ABOVE ground-state with/and Rayleigh(cut-limit of "short-cut method";1870)-Polya(1922)-"Anderson"(1958) localization [Doyle and Snell, Random-Walks and Electrical-Networks, MAA(1981)-p.99-100!!!].

Fractional Josephson vortices in two-gap superconductor long Josephson junctions

NASA Astrophysics Data System (ADS)

Kim, Ju

2014-03-01

We investigated the phase dynamics of long Josephson junctions (LJJ) with two-gap superconductors in the broken time reversal symmetry state. In this LJJ, spatial phase textures (i-solitons) can be excited due to the presence of two condensates and the interband Joesphson effect between them. The presence of a spatial phase texture in each superconductor layer leads to a spatial variation of the critical current density between the superconductor layers. We find that this spatial dependence of the crtitical current density can self-generate magnetic flux in the insulator layer, resulting in Josephson vortices with fractional flux quanta. Similar to the situation in a YBa2 Cu3O7 - x superconductor film grain boundary, the fractionalization of a Josephson vortex arises as a response to either periodic or random excitation of i-solitions. This suggests that magnetic flux measurements may be used to probe i-soliton excitations in multi-gap superconductor LJJs.

Twisted molecular excitons as mediators for changing the angular momentum of light

NASA Astrophysics Data System (ADS)

Zang, Xiaoning; Lusk, Mark T.

2017-07-01

Molecules with CN or CN h symmetry can absorb quanta of optical angular momentum to generate twisted excitons with well-defined quasiangular momenta of their own. Angular momentum is conserved in such interactions at the level of a paraxial approximation for the light beam. A sequence of absorption events can thus be used to create a range of excitonic angular momenta. Subsequent decay can produce radiation with a single angular momentum equal to that accumulated. Such molecules can thus be viewed as mediators for changing the angular momentum of light. This sidesteps the need to exploit nonlinear light-matter interactions based on higher-order susceptibilities. A tight-binding paradigm is used to verify angular momentum conservation and demonstrate how it can be exploited to change the angular momentum of light. The approach is then extended to a time-dependent density functional theory setting where the key results are shown to hold in a many-body, multilevel setting.

Effect of the tilted magnetic field on the magnetosubbands and conductance in the bilayer quantum wire

NASA Astrophysics Data System (ADS)

Chwiej, T.

2016-10-01

We theoretically study the single electron magnetotransport in GaAs and InGaAs vertically stacked bilayer nanowires. In considered geometry, the tilted magnetic field is always perpendicular to the main (transport) axis of the quantum wire and, therefore its transverse and vertical components allow separately for changing the magnitude of intralayer and interlayer subbands mixing. We study the changes introduced to energy dispersion relation E(k) by tilted magnetic field of strength up to several tesla and analyze their origins for symmetric as well as asymmetric confining potentials in the growth direction. Calculated energy dispersion relations are thereafter used to show that the value of a conductance of the bilayer nanowire may abruptly rise as well as fall by few conductance quanta when the Fermi energy in nanosystem is changed. It is also shown that such conductance oscillations, in conjunction with spin Zeeman effect, may give a moderately spin polarized current in the bilayer nanowire.

Metamaterial bricks and quantization of meta-surfaces.

PubMed

Memoli, Gianluca; Caleap, Mihai; Asakawa, Michihiro; Sahoo, Deepak R; Drinkwater, Bruce W; Subramanian, Sriram

2017-02-27

Controlling acoustic fields is crucial in diverse applications such as loudspeaker design, ultrasound imaging and therapy or acoustic particle manipulation. The current approaches use fixed lenses or expensive phased arrays. Here, using a process of analogue-to-digital conversion and wavelet decomposition, we develop the notion of quantal meta-surfaces. The quanta here are small, pre-manufactured three-dimensional units-which we call metamaterial bricks-each encoding a specific phase delay. These bricks can be assembled into meta-surfaces to generate any diffraction-limited acoustic field. We apply this methodology to show experimental examples of acoustic focusing, steering and, after stacking single meta-surfaces into layers, the more complex field of an acoustic tractor beam. We demonstrate experimentally single-sided air-borne acoustic levitation using meta-layers at various bit-rates: from a 4-bit uniform to 3-bit non-uniform quantization in phase. This powerful methodology dramatically simplifies the design of acoustic devices and provides a key-step towards realizing spatial sound modulators.

Reshaping the phonon energy landscape of nanocrystals inside a terahertz plasmonic nanocavity.

PubMed

Jin, Xin; Cerea, Andrea; Messina, Gabriele C; Rovere, Andrea; Piccoli, Riccardo; De Donato, Francesco; Palazon, Francisco; Perucchi, Andrea; Di Pietro, Paola; Morandotti, Roberto; Lupi, Stefano; De Angelis, Francesco; Prato, Mirko; Toma, Andrea; Razzari, Luca

2018-02-22

Phonons (quanta of collective vibrations) are a major source of energy dissipation and drive some of the most relevant properties of materials. In nanotechnology, phonons severely affect light emission and charge transport of nanodevices. While the phonon response is conventionally considered an inherent property of a nanomaterial, here we show that the dipole-active phonon resonance of semiconducting (CdS) nanocrystals can be drastically reshaped inside a terahertz plasmonic nanocavity, via the phonon strong coupling with the cavity vacuum electric field. Such quantum zero-point field can indeed reach extreme values in a plasmonic nanocavity, thanks to a mode volume well below λ 3 /10 7 . Through Raman measurements, we find that the nanocrystals within a nanocavity exhibit two new "hybridized" phonon peaks, whose spectral separation increases with the number of nanocrystals. Our findings open exciting perspectives for engineering the optical phonon response of functional nanomaterials and for implementing a novel platform for nanoscale quantum optomechanics.

'Nature and the Greeks' and 'Science and Humanism'

NASA Astrophysics Data System (ADS)

Schrödinger, Erwin

2014-11-01

Foreword; Part I. Nature and the Greeks: 1. The motives for returning to ancient thought; 2. The competition, reason v. senses; 3. The Pythagoreans; 4. The Ionian enlightenment; 5. The religion of Xenophanes, Heraclitus of Ephesus; 6. The atomists; 7. What are the special features?; Part II. Science and Humanism: 1. The spiritual bearing of science on life; 2. The practical achievements of science tending to obliterate its true import; 3. A radical change in our ideas of matter; 4. Form, not substance, the fundamental concept; 5. The nature of our 'models'; 6. Continuous descriptions and causality; 7. The intricacy of the continuum; 8. The makeshift of wave mechanics; 9. The alleged breakdown of the barrier between subject and object; 10. Atoms or quanta - the counter-spell of old standing, to escape the intricacy of the continuum; 11. Would physical indeterminacy give free will a chance?; 12. The bar to prediction, according to Niels Bohr; Literature.

Continuous high speed coherent one-way quantum key distribution.

PubMed

Stucki, Damien; Barreiro, Claudio; Fasel, Sylvain; Gautier, Jean-Daniel; Gay, Olivier; Gisin, Nicolas; Thew, Rob; Thoma, Yann; Trinkler, Patrick; Vannel, Fabien; Zbinden, Hugo

2009-08-03

Quantum key distribution (QKD) is the first commercial quantum technology operating at the level of single quanta and is a leading light for quantum-enabled photonic technologies. However, controlling these quantum optical systems in real world environments presents significant challenges. For the first time, we have brought together three key concepts for future QKD systems: a simple high-speed protocol; high performance detection; and integration both, at the component level and for standard fibre network connectivity. The QKD system is capable of continuous and autonomous operation, generating secret keys in real time. Laboratory and field tests were performed and comparisons made with robust InGaAs avalanche photodiodes and superconducting detectors. We report the first real world implementation of a fully functional QKD system over a 43 dB-loss (150 km) transmission line in the Swisscom fibre optic network where we obtained average real-time distribution rates over 3 hours of 2.5 bps.

World Antibody-Drug Conjugate Summit, October 15-16, 2013, San Francisco, CA.

PubMed

Klinguer-Hamour, Christine; Strop, Pavel; Shah, Dhaval K; Ducry, Laurent; Xu, April; Beck, Alain

2014-01-01

The World Antibody-Drug Conjugate (WADC) Summits organized by Hanson Wade are currently the largest meetings fully dedicated to ADCs. The first global ADC Summit was organized in Boston in October 2010. Since 2011, two WADC are held every year in Frankfurt and San Francisco, respectively. The 2013 WADC San Francisco event was structured around plenary sessions with keynote speakers from AbbVie, Agensys, ImmunoGen, Immunomedics, Genentech, Pfizer and Seattle Genetics. Parallel tracks were also organized addressing ADC discovery, development and optimization of chemistry, manufacturing and control (CMC) issues. Discovery and process scientists, regulatory experts (US Food and Drug Administration), academics and clinicians were present, including representatives from biotechnology firms (Concortis, CytomX Therapeutics, Glykos, Evonik, Igenica, Innate Pharma, Mersana Therapeutics, Polytherics, Quanta Biodesign, Redwood Bioscience, Sutro Biopharma, SynAffix), pharmaceutical companies (Amgen, Genmab, Johnson and Johnson, MedImmune, Novartis, Progenics, Takeda) and contract research or manufacturing organizations (Baxter, Bayer, BSP Pharmaceuticals, Fujifilm/Diosynth, Lonza, Pierre Fabre Contract Manufacturing, Piramal, SAFC, SafeBridge).

Direct Measurement of Photon Recoil from a Levitated Nanoparticle

NASA Astrophysics Data System (ADS)

Jain, Vijay; Gieseler, Jan; Moritz, Clemens; Dellago, Christoph; Quidant, Romain; Novotny, Lukas

2016-06-01

The momentum transfer between a photon and an object defines a fundamental limit for the precision with which the object can be measured. If the object oscillates at a frequency Ω0 , this measurement backaction adds quanta ℏΩ0 to the oscillator's energy at a rate Γrecoil, a process called photon recoil heating, and sets bounds to coherence times in cavity optomechanical systems. Here, we use an optically levitated nanoparticle in ultrahigh vacuum to directly measure Γrecoil. By means of a phase-sensitive feedback scheme, we cool the harmonic motion of the nanoparticle from ambient to microkelvin temperatures and measure its reheating rate under the influence of the radiation field. The recoil heating rate is measured for different particle sizes and for different excitation powers, without the need for cavity optics or cryogenic environments. The measurements are in quantitative agreement with theoretical predictions and provide valuable guidance for the realization of quantum ground-state cooling protocols and the measurement of ultrasmall forces.

Detection efficiency calculation for photons, electrons and positrons in a well detector. Part I: Analytical model

NASA Astrophysics Data System (ADS)

Pommé, S.

2009-06-01

An analytical model is presented to calculate the total detection efficiency of a well-type radiation detector for photons, electrons and positrons emitted from a radioactive source at an arbitrary position inside the well. The model is well suited to treat a typical set-up with a point source or cylindrical source and vial inside a NaI well detector, with or without lead shield surrounding it. It allows for fast absolute or relative total efficiency calibrations for a wide variety of geometrical configurations and also provides accurate input for the calculation of coincidence summing effects. Depending on its accuracy, it may even be applied in 4π-γ counting, a primary standardisation method for activity. Besides an accurate account of photon interactions, precautions are taken to simulate the special case of 511 keV annihilation quanta and to include realistic approximations for the range of (conversion) electrons and β -- and β +-particles.

A Two-Tier Golgi-Based Control of Organelle Size Underpins the Functional Plasticity of Endothelial Cells

PubMed Central

Ferraro, Francesco; Kriston-Vizi, Janos; Metcalf, Daniel J.; Martin-Martin, Belen; Freeman, Jamie; Burden, Jemima J.; Westmoreland, David; Dyer, Clare E.; Knight, Alex E.; Ketteler, Robin; Cutler, Daniel F.

2014-01-01

Summary Weibel-Palade bodies (WPBs), endothelial-specific secretory granules that are central to primary hemostasis and inflammation, occur in dimensions ranging between 0.5 and 5 μm. How their size is determined and whether it has a functional relevance are at present unknown. Here, we provide evidence for a dual role of the Golgi apparatus in controlling the size of these secretory carriers. At the ministack level, cisternae constrain the size of nanostructures (“quanta”) of von Willebrand factor (vWF), the main WPB cargo. The ribbon architecture of the Golgi then allows copackaging of a variable number of vWF quanta within the continuous lumen of the trans-Golgi network, thereby generating organelles of different sizes. Reducing the WPB size abates endothelial cell hemostatic function by drastically diminishing platelet recruitment, but, strikingly, the inflammatory response (the endothelial capacity to engage leukocytes) is unaltered. Size can thus confer functional plasticity to an organelle by differentially affecting its activities. PMID:24794632

Edge currents shunt the insulating bulk in gapped graphene

NASA Astrophysics Data System (ADS)

Zhu, M. J.; Kretinin, A. V.; Thompson, M. D.; Bandurin, D. A.; Hu, S.; Yu, G. L.; Birkbeck, J.; Mishchenko, A.; Vera-Marun, I. J.; Watanabe, K.; Taniguchi, T.; Polini, M.; Prance, J. R.; Novoselov, K. S.; Geim, A. K.; Ben Shalom, M.

2017-02-01

An energy gap can be opened in the spectrum of graphene reaching values as large as 0.2 eV in the case of bilayers. However, such gaps rarely lead to the highly insulating state expected at low temperatures. This long-standing puzzle is usually explained by charge inhomogeneity. Here we revisit the issue by investigating proximity-induced superconductivity in gapped graphene and comparing normal-state measurements in the Hall bar and Corbino geometries. We find that the supercurrent at the charge neutrality point in gapped graphene propagates along narrow channels near the edges. This observation is corroborated by using the edgeless Corbino geometry in which case resistivity at the neutrality point increases exponentially with increasing the gap, as expected for an ordinary semiconductor. In contrast, resistivity in the Hall bar geometry saturates to values of about a few resistance quanta. We attribute the metallic-like edge conductance to a nontrivial topology of gapped Dirac spectra.

Generation of large coherent states by bang–bang control of a trapped-ion oscillator

PubMed Central

Alonso, J.; Leupold, F. M.; Solèr, Z. U.; Fadel, M.; Marinelli, M.; Keitch, B. C.; Negnevitsky, V.; Home, J. P.

2016-01-01

Fast control of quantum systems is essential to make use of quantum properties before they degrade by decoherence. This is important for quantum-enhanced information processing, as well as for pushing quantum systems towards the boundary between quantum and classical physics. ‘Bang–bang' control attains the ultimate speed limit by making large changes to control fields much faster than the system can respond, but is often challenging to implement experimentally. Here we demonstrate bang–bang control of a trapped-ion oscillator using nanosecond switching of the trapping potentials. We perform controlled displacements with which we realize coherent states with up to 10,000 quanta of energy. We use these displaced states to verify the form of the ion-light interaction at high excitations far outside the usual regime of operation. These methods provide new possibilities for quantum-state manipulation and generation, alongside the potential for a significant increase in operational clock speed for trapped-ion quantum information processing. PMID:27046513

Theory of scattering of electromagnetic waves of the microwave range in a turbid medium

NASA Astrophysics Data System (ADS)

Konstantinov, O. V.; Matveentsev, A. V.

2013-02-01

The coefficient of extinction of electromagnetic waves of the microwave range due to their scattering from clusters suspended in an amorphous medium and responsible for turbidity is calculated. Turbidity resembles the case when butter clusters transform water into milk. In the case under investigation, the clusters are conductors (metallic or semiconducting). The extinction coefficient is connected in a familiar way with the cross section of light scattering from an individual cluster. A new formula is derived for the light scattering cross section in the case when damping of oscillations of an electron is due only to spontaneous emission of light quanta. In this case, the resonant scattering cross section for light can be very large. It is shown that this can be observed only in a whisker nanocluster. In addition, the phonon energy on a whisker segment must be higher than the photon energy, which is close to the spacing between the electron energy levels in the cluster.

Reconfigurable nanoscale spin-wave directional coupler.

PubMed

Wang, Qi; Pirro, Philipp; Verba, Roman; Slavin, Andrei; Hillebrands, Burkard; Chumak, Andrii V

2018-01-01

Spin waves, and their quanta magnons, are prospective data carriers in future signal processing systems because Gilbert damping associated with the spin-wave propagation can be made substantially lower than the Joule heat losses in electronic devices. Although individual spin-wave signal processing devices have been successfully developed, the challenging contemporary problem is the formation of two-dimensional planar integrated spin-wave circuits. Using both micromagnetic modeling and analytical theory, we present an effective solution of this problem based on the dipolar interaction between two laterally adjacent nanoscale spin-wave waveguides. The developed device based on this principle can work as a multifunctional and dynamically reconfigurable signal directional coupler performing the functions of a waveguide crossing element, tunable power splitter, frequency separator, or multiplexer. The proposed design of a spin-wave directional coupler can be used both in digital logic circuits intended for spin-wave computing and in analog microwave signal processing devices.

Revisiting a pre-inflationary radiation era and its effect on the CMB power spectrum

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

Das, Suratna; Goswami, Gaurav; Rangarajan, Raghavan

2015-06-01

We revisit the scenario where inflation is preceded by a radiation era by considering that the inflaton too could have been in thermal equilibrium early in the radiation era. Hence we take into account not only the effect of a pre-inflationary era on the inflaton mode functions but also that of a frozen thermal distribution of inflaton quanta. We initially discuss in detail the issues relevant to our scenario of a pre-inflationary radiation dominated era and then obtain the scalar power spectrum for this scenario. We find that the power spectrum is free from infrared divergences. We then use themore » WMAP and Planck data to determine the constraints on the inflaton comoving 'temperature' and on the duration of inflation. We find that the best fit value of the duration of inflation is less than 1 e-folding more than what is required to solve cosmological problems, while only an upper bound on the inflaton temperature can be obtained.« less

Electronic torsional sound in linear atomic chains: Chemical energy transport at 1000 km/s

NASA Astrophysics Data System (ADS)

Kurnosov, Arkady A.; Rubtsov, Igor V.; Maksymov, Andrii O.; Burin, Alexander L.

2016-07-01

We investigate entirely electronic torsional vibrational modes in linear cumulene chains. The carbon nuclei of a cumulene are positioned along the primary axis so that they can participate only in the transverse and longitudinal motions. However, the interatomic electronic clouds behave as a torsion spring with remarkable torsional stiffness. The collective dynamics of these clouds can be described in terms of electronic vibrational quanta, which we name torsitons. It is shown that the group velocity of the wavepacket of torsitons is much higher than the typical speed of sound, because of the small mass of participating electrons compared to the atomic mass. For the same reason, the maximum energy of the torsitons in cumulenes is as high as a few electronvolts, while the minimum possible energy is evaluated as a few hundred wavenumbers and this minimum is associated with asymmetry of zero point atomic vibrations. Theory predictions are consistent with the time-dependent density functional theory calculations. Molecular systems for experimental evaluation of the predictions are proposed.

Tensile strength and the mining of black holes.

PubMed

Brown, Adam R

2013-11-22

There are a number of important thought experiments that involve raising and lowering boxes full of radiation in the vicinity of black hole horizons. This Letter looks at the limitations placed on these thought experiments by the null energy condition, which imposes a fundamental bound on the tensile-strength-to-weight ratio of the materials involved, makes it impossible to build a box near the horizon that is wider than a single wavelength of the Hawking quanta, and puts a severe constraint on the operation of "space elevators" near black holes. In particular, it is shown that proposals for mining black holes by lowering boxes near the horizon, collecting some Hawking radiation, and dragging it out to infinity cannot proceed nearly as rapidly as has previously been claimed. As a consequence of this limitation, the boxes and all the moving parts are superfluous and black holes can be destroyed equally rapidly by threading the horizon with strings.

Photonic polarization gears for ultra-sensitive angular measurements

PubMed Central

D'Ambrosio, Vincenzo; Spagnolo, Nicolò; Del Re, Lorenzo; Slussarenko, Sergei; Li, Ying; Kwek, Leong Chuan; Marrucci, Lorenzo; Walborn, Stephen P.; Aolita, Leandro; Sciarrino, Fabio

2013-01-01

Quantum metrology bears a great promise in enhancing measurement precision, but is unlikely to become practical in the near future. Its concepts can nevertheless inspire classical or hybrid methods of immediate value. Here we demonstrate NOON-like photonic states of m quanta of angular momentum up to m=100, in a setup that acts as a ‘photonic gear’, converting, for each photon, a mechanical rotation of an angle θ into an amplified rotation of the optical polarization by mθ, corresponding to a ‘super-resolving’ Malus’ law. We show that this effect leads to single-photon angular measurements with the same precision of polarization-only quantum strategies with m photons, but robust to photon losses. Moreover, we combine the gear effect with the quantum enhancement due to entanglement, thus exploiting the advantages of both approaches. The high ‘gear ratio’ m boosts the current state of the art of optical non-contact angular measurements by almost two orders of magnitude. PMID:24045270

Registered particles onboard identification in the various apertures of GAMMA-400 space gamma-telescope

NASA Astrophysics Data System (ADS)

Arkhangelskaja, Irene

2016-07-01

GAMMA-400 (Gamma Astronomical Multifunctional Modular Apparatus) will be the gamma-telescope onboard international satellite gamma-observatory designed for particle registration in the wide energy band. Its parameters are optimized for detection of gamma-quanta with the energy ˜ 100 GeV in the main aperture. The main scientific goals of GAMMA-400 are to investigate fluxes of γ-rays and the electron-positron cosmic ray component possibly generated by dark matter particles decay or annihilation and to search for and study in detail discrete γ-ray sources, to investigate the energy spectra of Galactic and extragalactic diffuse γ-rays, and to study γ-ray bursts and γ-emission from the active Sun. This article presents analysis of detected events identification procedures and energy resolution in three apertures provide particles registration both from upper and lateral directions based on GAMMA-400 modeling due special designed software. Time and segmentation methods are used to reject backsplash (backscattering particles created when high energy γ-rays interact with the calorimeter's matter and move in the opposite direction) in the main aperture while only energy deposition analysis allows to reject this effect in the additional and lateral ones. The main aperture provides the best angular (all strip layers information analysis) and energy (energy deposition in the all detectors studying) resolution in the energy range 0.1 - 3 × 10^{3} GeV. The energy resolution in this band is 1%. Triggers in the main aperture will be formed using information about particle direction provided by time of flight system and presence of charged particle or backsplash signal formed according to analysis of energy deposition in combination of all two-layers anticoincidence systems individual detectors. In the additional aperture gamma-telescope allows to register events in the energy band 10 × 10^{-3} - 3 × 10^{3} GeV. The additional aperture energy resolution provides due to

Could photosynthesis function on Proxima Centauri b?

NASA Astrophysics Data System (ADS)

Ritchie, Raymond J.; Larkum, Anthony W. D.; Ribas, Ignasi

2018-04-01

Could oxygenic and/or anoxygenic photosynthesis exist on planet Proxima Centauri b? Proxima Centauri (spectral type - M5.5 V, 3050 K) is a red dwarf, whereas the Sun is type G2 V (5780 K). The light regimes on Earth and Proxima Centauri b are compared with estimates of the planet's suitability for Chlorophyll a (Chl a) and Chl d-based oxygenic photosynthesis and for bacteriochlorophyll (BChl)-based anoxygenic photosynthesis. Proxima Centauri b has low irradiance in the oxygenic photosynthesis range (400-749 nm: 64-132 µmol quanta m-2 s-1). Much larger amounts of light would be available for BChl-based anoxygenic photosynthesis (350-1100 nm: 724-1538 µmol quanta m-2 s-1). We estimated primary production under these light regimes. We used the oxygenic algae Synechocystis PCC6803, Prochlorothrix hollandica, Acaryochloris marina, Chlorella vulgaris, Rhodomonas sp. and Phaeodactylum tricornutum and the anoxygenic photosynthetic bacteria Rhodopseudomonas palustris (BChl a), Afifella marina (BChl a), Thermochromatium tepidum (BChl a), Chlorobaculum tepidum (BChl a + c) and Blastochloris viridis (BChl b) as representative photosynthetic organisms. Proxima Centauri b has only ~3% of the PAR (400-700 nm) of Earth irradiance, but we found that potential gross photosynthesis (P g) on Proxima Centauri b could be surprisingly high (oxygenic photosynthesis: earth ~0.8 gC m-2 h-1 Proxima Centauri b ~0.14 gC m-2 h-1). The proportion of PAR irradiance useable by oxygenic photosynthetic organisms (the sum of Blue + Red irradiance) is similar for the Earth and Proxima Centauri b. The oxygenic photic zone would be only ~10 m deep in water compared with ~200 m on Earth. The P g of an anoxic Earth (gC m-2 h-1) is ~0.34-0.59 (land) and could be as high as ~0.29-0.44 on Proxima Centauri b. 1 m of water does not affect oxygenic or anoxygenic photosynthesis on Earth, but on Proxima Centauri b oxygenic P g is reduced by ~50%. Effective elimination of near IR limits P g by photosynthetic

Gravitational constant is likely dependent on the absolute velocity of galaxy

NASA Astrophysics Data System (ADS)

Chen, Shao-Guang

In my paper ‘Quanta turn-advance ism, China Science && Technology Overview 131 192-210 (2011)’, QFT four-dimensional uncertainty principle and momentum-energy conservation law had been generalized as a five-dimensional equations: de Broglie wavelength as a position vector \\underline{q}= (i c t, r, s), momentum \\underline{P} = (i E/c, P, U c), \\underline{q} = i h / \\underline{P}, \\underline{q} \\underline{q} = 0, \\underline{P} \\underline{P} = 0, Sigma∑\\underline{P} = \\underline{P} (0) . The five-dimensional time-space-spin had been quantized as a non-dot model basic cell, the lowest energy state vertical polarized left spin 1/2 neutrino and right spin 1/2 antineutrino are just the left, right advance unit quanta _{0}nuυ, nuυ _{0} and left, right back unit quanta (0) nuυ, nuυ (0) , it again compose into spin 1 unit advance photon _{0}nuυnuυ _{0} and back (0) nuυnuυ (0) , spin 0 unit rest mass nuυ _{0}nuυ (0) and anti-mass _{0}nuυ (0) nuυ, spin 0 unit positive charge _{0}nuυnuυ (0) and negative charge nuυ _{0} (0) nuυ. It accord to the high energy physics experiment results of the transformation among the photons, masses quanta and charges quanta. The physical vacuum is the even collocation of non-combinational nuυ _{0} or _{0}nuυ. It is mathematically easy that from five-dimensional equations deduce out the Dirac, Klein-Gordan, Maxwell equations and Lorentz force formula, but appear some new results. The interactions between _{0}nuυ, nuυ _{0}, (0) nuυ, nuυ (0) , i.e., force f = ± ( h c / 2 r (3) ) r cos thetaθ for r not equal to 0 and f = 0 for r = 0, f as the magnetic force makes the photons, rest mass and charge quanta automatically come into being and stabilize. QFT no longer with divergence difficulty by the non-dot model. The explanation of abnormal magnetic moment and Lamb shift is more natural and simple only with the spin — the conjunction between turn and advance. Many testable results had been obtained. In the

Gamma-telescopes Fermi/LAT and GAMMA-400 Trigger Systems Event Recognizing Methods Comparison

NASA Astrophysics Data System (ADS)

Arkhangelskaja, I. V.; Murchenko, A. E.; Chasovikov, E. N.; Arkhangelskiy, A. I.; Kheymits, M. D.

Usually instruments for high-energy γ-quanta registration consists of converter (where γ-quanta produced pairs) and calorimeter for particles energy measurements surrounded by anticoincidence shield used to events identification (whether incident particle was charged or neutral). The influence of pair formation by γ-quanta in shield and the backsplash (moved in the opposite direction particles created due high energy γ-rays interact with calorimeter) should be taken into account. It leads to decrease both effective area and registration efficiency at E>10 GeV. In the presented article the event recognizing methods used in Fermi/LAT trigger system is considered in comparison with the ones applied in counting and triggers signals formation system of gamma-telescope GAMMA-400. The GAMMA-400 (Gamma Astronomical Multifunctional Modular Apparatus) will be the new high-apogee space γ-observatory. The GAMMA-400 consist of converter-tracker based on silicon-strip coordinate detectors interleaved with tungsten foils, imaging calorimeter make of 2 layers of double (x, y) silicon strip coordinate detectors interleaved with planes of CsI(Tl) crystals and the electromagnetic calorimeter CC2 consists only of CsI(Tl) crystals. Several plastics detections systems used as anticoincidence shield, for particles energy and moving direction estimations. The main differences of GAMMA-400 constructions from Fermi/LAT one are using the time-of-flight system with base of 50 cm and double layer structure of plastic detectors provides more effective particles direction definition and backsplash rejection. Also two calorimeters in GAMMA-400 composed the total absorbtion spectrometer with total thickness ∼ 25 X0 or ∼1.2 λ0 for vertical incident particles registration and 54 X0 or 2.5 λ0 for laterally incident ones (where λ0 is nuclear interaction length). It provides energy resolution 1-2% for 10 GeV-3.0×103 GeV events while the Fermi/LAT energy resolution does not reach such a

Loop Quantum Gravity and the Meaning of Diffeomorphism Invariance

NASA Astrophysics Data System (ADS)

Rovelli, Carlo; Gaul, Marcus

This series of lectures gives an introduction to the non-perturbative and background-independent formulation for a quantum theory of gravitation which is called loop quantum gravity . The Hilbert space of kinematical quantum states is constructed and a complete basis of spin network states is introduced. Afterwards an application of the formalism is provided by the spectral analysis of the area operator, which is the quantum analogue of the classical area function. This leads to one of the key results of loop quantum gravity obtained in the last few years: the derivation of the discreteness of the geometry and the computation of the quanta of area. Special importance is attached to the role played by the diffeomorphism group in order to clarify the notion of observability in general relativity - a concept far from being trivial. Finally an outlock onto a possible dynamical extension of the theory is given, leading to a "sum over histories" approach, namely a so-called spin foam model . Throughout the whole lecture great significance is attached to conceptual and interpretational issues.

Zonal-flow dynamics from a phase-space perspective

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

Ruiz, D. E.; Parker, J. B.; Shi, E. L.

The wave kinetic equation (WKE) describing drift-wave (DW) turbulence is widely used in the studies of zonal flows (ZFs) emerging from DW turbulence. But, this formulation neglects the exchange of enstrophy between DWs and ZFs and also ignores effects beyond the geometrical-optics limit. Furthermore, we derive a modified theory that takes both of these effects into account, while still treating DW quanta (“driftons”) as particles in phase space. The drifton dynamics is described by an equation of the Wigner–Moyal type, which is commonly known in the phase-space formulation of quantum mechanics. In the geometrical-optics limit, this formulation features additional termsmore » missing in the traditional WKE that ensure exact conservation of the total enstrophy of the system, in addition to the total energy, which is the only conserved invariant in previous theories based on the WKE. We present numerical simulations to illustrate the importance of these additional terms. The proposed formulation can be considered as a phase-space representation of the second-order cumulant expansion, or CE2.« less

Electronic torsional sound in linear atomic chains: Chemical energy transport at 1000 km/s

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

Kurnosov, Arkady A.; Rubtsov, Igor V.; Maksymov, Andrii O.

2016-07-21

We investigate entirely electronic torsional vibrational modes in linear cumulene chains. The carbon nuclei of a cumulene are positioned along the primary axis so that they can participate only in the transverse and longitudinal motions. However, the interatomic electronic clouds behave as a torsion spring with remarkable torsional stiffness. The collective dynamics of these clouds can be described in terms of electronic vibrational quanta, which we name torsitons. It is shown that the group velocity of the wavepacket of torsitons is much higher than the typical speed of sound, because of the small mass of participating electrons compared to themore » atomic mass. For the same reason, the maximum energy of the torsitons in cumulenes is as high as a few electronvolts, while the minimum possible energy is evaluated as a few hundred wavenumbers and this minimum is associated with asymmetry of zero point atomic vibrations. Theory predictions are consistent with the time-dependent density functional theory calculations. Molecular systems for experimental evaluation of the predictions are proposed.« less

On spectroscopy for a whole Abelian model

NASA Astrophysics Data System (ADS)

Chauca, J.; Doria, R.

2012-10-01

Postulated on the whole meaning a whole abelian gauge symmetry is being introduced. Various physical areas as complexity, statistical mechanics, quantum mechanics are partially supporting this approach where the whole is at origin. However, the reductionist crisis given by quark confinement definitely sustains this insight. It says that fundamental parts can not be seen isolatedely. Consequently, there is an experimental situation where the parts should be substituted by something more. This makes us to look for writing the wholeness principle under gauge theory. For this, one reinterprets the gauge parameter where instead of compensating fields it is organizing a systemic gauge symmetry. Now, it introduces a fields set {AμI} rotating under a common gauge symmetry. Thus, given a fields collection {AμI} as origin, the effort at this work is to investigate on its spectroscopy. Analyze for the abelian case the correspondent involved quanta. Understand that for a whole model diversity replaces elementarity. Derive the associated quantum numbers as spin, mass, charge, discrete symmetries in terms of such systemic symmetry. Observe how the particles diversity is manifested in terms of wholeness.

Zonal-flow dynamics from a phase-space perspective

DOE PAGES

Ruiz, D. E.; Parker, J. B.; Shi, E. L.; ...

2016-12-16

The wave kinetic equation (WKE) describing drift-wave (DW) turbulence is widely used in the studies of zonal flows (ZFs) emerging from DW turbulence. But, this formulation neglects the exchange of enstrophy between DWs and ZFs and also ignores effects beyond the geometrical-optics limit. Furthermore, we derive a modified theory that takes both of these effects into account, while still treating DW quanta (“driftons”) as particles in phase space. The drifton dynamics is described by an equation of the Wigner–Moyal type, which is commonly known in the phase-space formulation of quantum mechanics. In the geometrical-optics limit, this formulation features additional termsmore » missing in the traditional WKE that ensure exact conservation of the total enstrophy of the system, in addition to the total energy, which is the only conserved invariant in previous theories based on the WKE. We present numerical simulations to illustrate the importance of these additional terms. The proposed formulation can be considered as a phase-space representation of the second-order cumulant expansion, or CE2.« less

Synaptic noise is an information bottleneck in the inner retina during dynamic visual stimulation

PubMed Central

Freed, Michael A; Liang, Zhiyin

2014-01-01

In daylight, noise generated by cones determines the fidelity with which visual signals are initially encoded. Subsequent stages of visual processing require synapses from bipolar cells to ganglion cells, but whether these synapses generate a significant amount of noise was unknown. To characterize noise generated by these synapses, we recorded excitatory postsynaptic currents from mammalian retinal ganglion cells and subjected them to a computational noise analysis. The release of transmitter quanta at bipolar cell synapses contributed substantially to the noise variance found in the ganglion cell, causing a significant loss of fidelity from bipolar cell array to postsynaptic ganglion cell. Virtually all the remaining noise variance originated in the presynaptic circuit. Circuit noise had a frequency content similar to noise shared by ganglion cells but a very different frequency content from noise from bipolar cell synapses, indicating that these synapses constitute a source of independent noise not shared by ganglion cells. These findings contribute a picture of daylight retinal circuits where noise from cones and noise generated by synaptic transmission of cone signals significantly limit visual fidelity. PMID:24297850

The contrasting roles of Planck's constant in classical and quantum theories

NASA Astrophysics Data System (ADS)

Boyer, Timothy H.

2018-04-01

We trace the historical appearance of Planck's constant in physics, and we note that initially the constant did not appear in connection with quanta. Furthermore, we emphasize that Planck's constant can appear in both classical and quantum theories. In both theories, Planck's constant sets the scale of atomic phenomena. However, the roles played in the foundations of the theories are sharply different. In quantum theory, Planck's constant is crucial to the structure of the theory. On the other hand, in classical electrodynamics, Planck's constant is optional, since it appears only as the scale factor for the (homogeneous) source-free contribution to the general solution of Maxwell's equations. Since classical electrodynamics can be solved while taking the homogenous source-free contribution in the solution as zero or non-zero, there are naturally two different theories of classical electrodynamics, one in which Planck's constant is taken as zero and one where it is taken as non-zero. The textbooks of classical electromagnetism present only the version in which Planck's constant is taken to vanish.

Characterizing the risk of infection from Mycobacterium tuberculosis in commercial passenger aircraft using quantitative microbial risk assessment.

PubMed

Jones, Rachael M; Masago, Yoshifumi; Bartrand, Timothy; Haas, Charles N; Nicas, Mark; Rose, Joan B

2009-03-01

Quantitative microbial risk assessment was used to predict the likelihood and spatial organization of Mycobacterium tuberculosis (Mtb) transmission in a commercial aircraft. Passenger exposure was predicted via a multizone Markov model in four scenarios: seated or moving infectious passengers and with or without filtration of recirculated cabin air. The traditional exponential (k = 1) and a new exponential (k = 0.0218) dose-response function were used to compute infection risk. Emission variability was included by Monte Carlo simulation. Infection risks were higher nearer and aft of the source; steady state airborne concentration levels were not attained. Expected incidence was low to moderate, with the central 95% ranging from 10(-6) to 10(-1) per 169 passengers in the four scenarios. Emission rates used were low compared to measurements from active TB patients in wards, thus a "superspreader" emitting 44 quanta/h could produce 6.2 cases or more under these scenarios. Use of respiratory protection by the infectious source and/or susceptible passengers reduced infection incidence up to one order of magnitude.

Effects of charge density waves on flux dynamics in weak-pinning single crystals of NbSe2 : free flux flow, flux-core size effects, and unexpected doubling of Jc(H) `peak effect'

NASA Astrophysics Data System (ADS)

Favreau, Peter; Gapud, Albert A.; Moraes, Sunhee; Delong, Lance; Reyes, Arneil P.; Thompson, James R.; Christen, David K.

2010-03-01

The interaction of two different ordering schemes -- charge density waves (CDWs) and superconductivity -- is studied in high-quality samples of NbSe2, particularly in the motion of magnetic flux quanta. More specifically, the study is on the effect of ``switching off'' the CDW phase -- effected by doping with Ta -- on the magnetic-field H dependence of: (i) the Lorentz-force-driven free flux flow (FFF) resistivity ρf associated with the ordered motion of vortices, and (ii) critical current density Jc. FFF is achieved for the first time in this material. The field dependence of ρf deviates from traditional Bardeen-Stephen flux flow and is more consistent with effects of flux core size as predicted by Kogan and Zelezhina. However, the suppression of CDW's seems to have no significant effect on these properties. On the other hand, Jc(H) shows a surprising double peak for the CDW-suppressed sample --contrary to previous studies in which the Jc peak was shown to disappear. Possible mechanisms are discussed.

Spectral transfers and zonal flow dynamics in the generalized Charney-Hasegawa-Mima model

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

Lashmore-Davies, C.N.; Thyagaraja, A.; McCarthy, D.R.

2005-12-15

The mechanism of four nonlinearly interacting drift or Rossby waves is used as the basic process underlying the turbulent evolution of both the Charney-Hasegawa-Mima-equation (CHME) and its generalized modification (GCHME). Hasegawa and Kodama's concept of equivalent action (or quanta) is applied to the four-wave system and shown to control the distribution of energy and enstrophy between the modes. A numerical study of the GCHME is described in which the initial state contains a single finite-amplitude drift wave (the pump wave), and all the modulationally unstable modes are present at the same low level (10{sup -6} times the pump amplitude). Themore » simulation shows that at first the fastest-growing modulationally unstable modes dominate but reveals that at a later time, before pump depletion occurs, long- and short-wavelength modes, driven by pairs of fast-growing modes, grow at 2{gamma}{sub max}. The numerical simulation illustrates the development of a spectrum of turbulent modes from a finite-amplitude pump wave.« less

Quantum information to the home

NASA Astrophysics Data System (ADS)

Choi, Iris; Young, Robert J.; Townsend, Paul D.

2011-06-01

Information encoded on individual quanta will play an important role in our future lives, much as classically encoded digital information does today. Combining quantum information carried by single photons with classical signals encoded on strong laser pulses in modern fibre-to-the-home (FTTH) networks is a significant challenge, the solution to which will facilitate the global distribution of quantum information to the home and with it a quantum internet [1]. In real-world networks, spontaneous Raman scattering in the optical fibre would induce crosstalk between the high-power classical channels and a single-photon quantum channel, such that the latter is unable to operate. Here, we show that the integration of quantum and classical information on an FTTH network is possible by performing quantum key distribution (QKD) on a network while simultaneously transferring realistic levels of classical data. Our novel scheme involves synchronously interleaving a channel of quantum data with the Raman scattered photons from a classical channel, exploiting the periodic minima in the instantaneous crosstalk and thereby enabling secure QKD to be performed.

Study of a generalized birks formula for the scintillation response of a CaMoO4 crystal

NASA Astrophysics Data System (ADS)

Lee, J. Y.; Kim, H. J.; Kang, Sang Jun; Lee, M. H.

2017-12-01

We have investigated the scintillation characteristics of CaMoO4 (CMO) crystals by using a gamma source and various internal alpha sources. A 137Cs source with 662-keV gamma-rays was used for the gamma-quanta light yield calibration. Internal radioactive contaminations provided alpha particles with different energies from 5.41 to 7.88 MeV. We developed a C++ program based on the ROOT package for the fitting of parameters in a generalized Birks semi-empirical formula by combining the experimental and the simulation data. Results for the fitted Birks parameters are k b1 = 3.3 × 10 -3 (g/MeVcm2) for the 1st parameter and k b2 = 7.9 × 10 -5 (g/MeVcm2)2 for the 2nd parameter. The χ2/n.d.f. (Number of Degree of Freedom) is calculated as 0.1/4. We were able to estimate the 238U and 234U contaminations in a CMO crystal by using the generalized Birks semi-empirical formula.

Measurements and calculations of the Coulomb cross section for the production of direct electron pairs by energetic heavy nuclei in nuclear track emulsion

NASA Technical Reports Server (NTRS)

Derrickson, J. H.; Eby, P. B.; Fountain, W. F.; Parnell, T. A.; Dong, B. L.; Gregory, J. C.; Takahashi, Y.; King, D. T.

1988-01-01

Measurements and theoretical predictions of the Coulomb cross section for the production of direct electron pairs by heavy ions in emulsion have been performed. Nuclear track emulsions were exposed to the 1.8 GeV/amu Fe-56 beam at the Lawrence Berkeley Laboratory bevalac and to the 60 and 200 GeV/amu O-16 and the 200 GeV/amu S-32 beam at the European Center for Nuclear Research Super Proton Synchrotron modified to accelerate heavy ions. The calculations combine the Weizsacker-Williams virtual quanta method applicable to the low-energy transfers and the Kelner-Kotov relativistic treatment for the high-energy transfers. Comparison of the measured total electron pair yield, the energy transfer distribution, and the emission angle distribution with theoretical predictions revealed a discrepancy in the frequency of occurrence of the low-energy pairs (less than or = 10 MeV). The microscope scanning criteria used to identify the direct electron pairs is described and efforts to improve the calculation of the cross section for pair production are also discussed.

Exploring Divisibility and Summability of 'Photon' Wave Packets in Nonlinear Optical Phenomena

NASA Technical Reports Server (NTRS)

Prasad, Narasimha; Roychoudhuri, Chandrasekhar

2009-01-01

Formulations for second and higher harmonic frequency up and down conversions, as well as multi photon processes directly assume summability and divisibility of photons. Quantum mechanical (QM) interpretations are completely congruent with these assumptions. However, for linear optical phenomena (interference, diffraction, refraction, material dispersion, spectral dispersion, etc.), we have a profound dichotomy. Most optical engineers innovate and analyze all optical instruments by propagating pure classical electromagnetic (EM) fields using Maxwell s equations and gives only lip-service to the concept "indivisible light quanta". Further, irrespective of linearity or nonlinearity of the phenomena, the final results are always registered through some photo-electric or photo-chemical effects. This is mathematically well modeled by a quadratic action (energy absorption) relation. Since QM does not preclude divisibility or summability of photons in nonlinear & multi-photon effects, it cannot have any foundational reason against these same possibilities in linear optical phenomena. It implies that we must carefully revisit the fundamental roots behind all light-matter interaction processes and understand the common origin of "graininess" and "discreteness" of light energy.

Accurate Vibrational-Rotational Parameters and Infrared Intensities of 1-Bromo-1-fluoroethene: A Joint Experimental Analysis and Ab Initio Study.

PubMed

Pietropolli Charmet, Andrea; Stoppa, Paolo; Giorgianni, Santi; Bloino, Julien; Tasinato, Nicola; Carnimeo, Ivan; Biczysko, Malgorzata; Puzzarini, Cristina

2017-05-04

The medium-resolution gas-phase infrared (IR) spectra of 1-bromo-1-fluoroethene (BrFC═CH 2 , 1,1-C 2 H 2 BrF) were investigated in the range 300-6500 cm -1 , and the vibrational analysis led to the assignment of all fundamentals as well as many overtone and combination bands up to three quanta, thus giving an accurate description of its vibrational structure. Integrated band intensity data were determined with high precision from the measurements of their corresponding absorption cross sections. The vibrational analysis was supported by high-level ab initio investigations. CCSD(T) computations accounting for extrapolation to the complete basis set and core correlation effects were employed to accurately determine the molecular structure and harmonic force field. The latter was then coupled to B2PLYP and MP2 computations in order to account for mechanical and electrical anharmonicities. Second-order perturbative vibrational theory was then applied to the thus obtained hybrid force fields to support the experimental assignment of the IR spectra.

Physical Realization of von Neumann Lattices in Rotating Bose Gases with Dipole Interatomic Interactions.

PubMed

Cheng, Szu-Cheng; Jheng, Shih-Da

2016-08-22

This paper reports a novel type of vortex lattice, referred to as a bubble crystal, which was discovered in rapidly rotating Bose gases with long-range interactions. Bubble crystals differ from vortex lattices which possess a single quantum flux per unit cell, while atoms in bubble crystals are clustered periodically and surrounded by vortices. No existing model is able to describe the vortex structure of bubble crystals; however, we identified a mathematical lattice, which is a subset of coherent states and exists periodically in the physical space. This lattice is called a von Neumann lattice, and when it possesses a single vortex per unit cell, it presents the same geometrical structure as an Abrikosov lattice. In this report, we extend the von Neumann lattice to one with an integral number of flux quanta per unit cell and demonstrate that von Neumann lattices well reproduce the translational properties of bubble crystals. Numerical simulations confirm that, as a generalized vortex, a von Neumann lattice can be physically realized using vortex lattices in rapidly rotating Bose gases with dipole interatomic interactions.

The Road to the Common PET/CT Detector

NASA Astrophysics Data System (ADS)

Nassalski, Antoni; Moszynski, Marek; Szczesniak, Tomasz; Wolski, Dariusz; Batsch, Tadeusz

2007-10-01

Growing interest in the development of dual modality positron emission/X-rays tomography (PET/CT) systems prompts researchers to face a new challenge: to acquire both the anatomical and functional information in the same measurement, simultaneously using the same detection system and electronics. The aim of this work was to study a detector consisting of LaBr3, LSO or LYSO pixel crystals coupled to an avalanche photodiode (APD). The measurements covered tests of the detectors in PET and CT modes, respectively. The measurements included the determination of light output, energy resolution, the non-proportionality of the light yield and the time resolution for 511 keV annihilation quanta; analysis also included characterizing the PET detector, and determining the dependence of counting rate versus mean current of the APD in the X-ray detection. In the present experiment, the use of counting and current modes in the CT detection increases the dynamic range of the measured dose of X-rays by a factor of 20, compared to the counting mode alone.

Artificial ice using superconducting vortices (Conference Presentation)

NASA Astrophysics Data System (ADS)

Trastoy Quintela, Juan; Malnou, Maxime; Ulysse, Christian; Bernard, Rozenn; Bergeal, Nicolas; Faini, Giancarlo; Lesueur, Jerome; Briatico, Javier; Villegas, Javier E.

2016-10-01

We use magnetic flux quanta (superconducting vortices) on artificial energy landscapes (pinning arrays) to create a new type of artificial ice. This vortex ice shows unusual temperature effects that offer new possibilities in the study of ice systems. We have investigated the matching of the flux lattice to pinning arrays that present geometrical frustration. The pinning arrays are fabricated on YBCO films using masked O+ ion irradiation. The details of the magneto-resistance imply that the flux lattice organizes into a vortex ice. The absence of history-dependent effects suggests that the vortex ice is highly ordered. Due to the technique used for the artificial energy landscape fabrication, we have the ability to change the pinning array geometry using temperature as a control knob. In particular we can switch the geometrical frustration on and off, which opens the door to performing a new type of annealing absent in other artificial ice systems. * Work supported by the French ANR "MASTHER", and the Fundación Barrié (Galicia, Spain)

Organic-based magnon spintronics.

PubMed

Liu, Haoliang; Zhang, Chuang; Malissa, Hans; Groesbeck, Matthew; Kavand, Marzieh; McLaughlin, Ryan; Jamali, Shirin; Hao, Jingjun; Sun, Dali; Davidson, Royce A; Wojcik, Leonard; Miller, Joel S; Boehme, Christoph; Vardeny, Z Valy

2018-04-01

Magnonics concepts utilize spin-wave quanta (magnons) for information transmission, processing and storage. To convert information carried by magnons into an electric signal promises compatibility of magnonic devices with conventional electronic devices, that is, magnon spintronics 1 . Magnons in inorganic materials have been studied widely with respect to their generation 2,3 , transport 4,5 and detection 6 . In contrast, resonant spin waves in the room-temperature organic-based ferrimagnet vanadium tetracyanoethylene (V(TCNE) x (x ≈ 2)), were detected only recently 7 . Herein we report room-temperature coherent magnon generation, transport and detection in films and devices based on V(TCNE) x using three different techniques, which include broadband ferromagnetic resonance (FMR), Brillouin light scattering (BLS) and spin pumping into a Pt adjacent layer. V(TCNE) x can be grown as neat films on a large variety of substrates, and it exhibits extremely low Gilbert damping comparable to that in yttrium iron garnet. Our studies establish an alternative use for organic-based magnets, which, because of their synthetic versatility, may substantially enrich the field of magnon spintronics.

Organic-based magnon spintronics

NASA Astrophysics Data System (ADS)

Liu, Haoliang; Zhang, Chuang; Malissa, Hans; Groesbeck, Matthew; Kavand, Marzieh; McLaughlin, Ryan; Jamali, Shirin; Hao, Jingjun; Sun, Dali; Davidson, Royce A.; Wojcik, Leonard; Miller, Joel S.; Boehme, Christoph; Vardeny, Z. Valy

2018-03-01

Magnonics concepts utilize spin-wave quanta (magnons) for information transmission, processing and storage. To convert information carried by magnons into an electric signal promises compatibility of magnonic devices with conventional electronic devices, that is, magnon spintronics1. Magnons in inorganic materials have been studied widely with respect to their generation2,3, transport4,5 and detection6. In contrast, resonant spin waves in the room-temperature organic-based ferrimagnet vanadium tetracyanoethylene (V(TCNE)x (x ≈ 2)), were detected only recently7. Herein we report room-temperature coherent magnon generation, transport and detection in films and devices based on V(TCNE)x using three different techniques, which include broadband ferromagnetic resonance (FMR), Brillouin light scattering (BLS) and spin pumping into a Pt adjacent layer. V(TCNE)x can be grown as neat films on a large variety of substrates, and it exhibits extremely low Gilbert damping comparable to that in yttrium iron garnet. Our studies establish an alternative use for organic-based magnets, which, because of their synthetic versatility, may substantially enrich the field of magnon spintronics.

Synchrophasor Based Tracking Three-Phase State Estimator and It's Applications

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

Phadke, A. G.; Thorp, James; Centeno, Virgilio

2013-08-31

Electric power infrastructure is one of the critical resources of the nation. Its reliability in the face of natural or man-made catastrophes is of paramount importance for the economic and public health wellbeing of a modern society. Maintaining high levels of security for the high voltage transmission back bone of the electric supply network is a task requiring access to modern monitoring tools. These tools have been made particularly effective with the advent of synchronized phasor measurement units (PMUs) which became available in late 1990s, and have now become an indispensable for optimal monitoring, protection and control of the powermore » grid. The present project was launched with an objective of demonstrating the value of the Wide Area Measurement System (WAMS) using PMUs and its applications on the Dominion Virginia Power High Voltage transmission grid. Virginia Tech is the birth place of PMUs, and was chosen to be the Principal Investigator of this project. In addition to Dominion Virginia Power, Quanta Technology of Raleigh, NC was selected to be co-Principal Investigators of this project.« less

A direct view by immunofluorescent comet assay (IFCA) of DNA damage induced by nicking and cutting enzymes, ionizing (137)Cs radiation, UV-A laser microbeam irradiation and the radiomimetic drug bleomycin.

PubMed

Grigaravicius, Paulius; Rapp, Alexander; Greulich, Karl Otto

2009-03-01

In DNA repair research, DNA damage is induced by different agents, depending on the technical facilities of the investigating researchers. A quantitative comparison of different investigations is therefore often difficult. By using a modified variant of the neutral comet assay, where the histone H1 is detected by immunofluorescence [immunofluorescent comet assay (IFCA)], we achieve previously unprecedented resolution in the detection of fragmented chromatin and show that trillions of ultraviolet A photons (of a few eV), billions of bleomycin (BLM) molecules and thousands of gamma quanta (of 662 keV) generate, in first order, similar damage in the chromatin of HeLa cells. A somewhat more detailed inspection shows that the damage caused by 20 Gy ionizing radiation and by a single laser pulse of 10 microJ are comparable, while the damage caused by 12 microg/ml BLM depends highly on the individual cell. Taken together, this work provides a detailed view of DNA fragmentation induced by different treatments and allows comparing them to some extent, especially with respect to the neutral comet assay.

Capacity Evaluation of a Quantum-Based Channel in a Biological Context.

PubMed

Loscri, Valeria; Vegni, Anna Maria

2016-12-01

Nanotechnology, as enabler of the miniaturization of devices in a scale ranging from 1 to few hundreds of nm , represents a viable solution for " alternative" communication paradigms that could be effective in complex networked systems, as body area networks. Traditional communication paradigms are not effective in the context of joint body and nano-networked systems, for several reasons, and then novel approaches have been investigated such as nanomechanical, electromagnetic, acoustic, molecular, etc. On the other hand, quantum phenomena represent a natural direction for developing nanotechnology, since it has to be considered as a new scale where new phenomena can occur and can be exploited for information purpose. Specific quantum particles are phonons, the quanta of mechanical vibrations (i.e., acoustic excitations), that can be analyzed as potential information carriers in a body networked context. In this paper we will focus on the generation of phonons from photon-phonon interaction, by irradiating a sample of human tissue with an electro-magnetic field, and then we will theoretically derive the information capacity and the bit rate in the frequency range [10 3 - 10 12 ] Hz.

Dark Energy and Dark Matter as w = -1 Virtual Particles and the World Hologram Model

NASA Astrophysics Data System (ADS)

Sarfatti, Jack

2011-04-01

The elementary physics battle-tested principles of Lorentz invariance, Einstein equivalence principle and the boson commutation and fermion anti-commutation rules of quantum field theory explain gravitationally repulsive dark energy as virtual bosons and gravitationally attractive dark matter as virtual fermion-antifermion pairs. The small dark energy density in our past light cone is the reciprocal entropy-area of our future light cone's 2D future event horizon in a Novikov consistent loop in time in our accelerating universe. Yakir Aharonov's "back-from-the-future" post-selected final boundary condition is set at our observer-dependent future horizon that also explains why the irreversible thermodynamic arrow of time of is aligned with the accelerating dark energy expansion of the bulk 3D space interior to our future 2D horizon surrounding it as the hologram screen. Seth Lloyd has argued that all 2D horizon surrounding surfaces are pixelated quantum computers projecting interior bulk 3D quanta of volume (Planck area)Sqrt(area of future horizon) as their hologram images in 1-1 correspondence.

Influence of Sky Conditions on Estimation of Photosynthetic Photon Flux Density for Agricultural Ecosystem

NASA Astrophysics Data System (ADS)

Yamashita, M.; Yoshimura, M.

2018-04-01

Photosynthetic photon flux density (PPFD: µmol m-2 s-1) is indispensable for plant physiology processes in photosynthesis. However, PPFD is seldom measured, so that PPFD has been estimated by using solar radiation (SR: W m-2) measured in world wide. In method using SR, there are two steps: first to estimate photosynthetically active radiation (PAR: W m-2) by the fraction of PAR to SR (PF) and second: to convert PAR to PPFD using the ratio of quanta to energy (Q / E: µmol J-1). PF and Q/E usually have been used as the constant values, however, recent studies point out that PF and Q / E would not be constants under various sky conditions. In this study, we use the numeric data of sky-conditions factors such cloud cover, sun appearance/hiding and relative sky brightness derived from whole-sky image processing and examine the influences of sky-conditions factors on PF and Q / E of global and diffuse PAR. Furthermore, we discuss our results by comparing with the existing methods.

Coherent quantum phase slip.

PubMed

Astafiev, O V; Ioffe, L B; Kafanov, S; Pashkin, Yu A; Arutyunov, K Yu; Shahar, D; Cohen, O; Tsai, J S

2012-04-18

A hundred years after the discovery of superconductivity, one fundamental prediction of the theory, coherent quantum phase slip (CQPS), has not been observed. CQPS is a phenomenon exactly dual to the Josephson effect; whereas the latter is a coherent transfer of charges between superconducting leads, the former is a coherent transfer of vortices or fluxes across a superconducting wire. In contrast to previously reported observations of incoherent phase slip, CQPS has been only a subject of theoretical study. Its experimental demonstration is made difficult by quasiparticle dissipation due to gapless excitations in nanowires or in vortex cores. This difficulty might be overcome by using certain strongly disordered superconductors near the superconductor-insulator transition. Here we report direct observation of CQPS in a narrow segment of a superconducting loop made of strongly disordered indium oxide; the effect is made manifest through the superposition of quantum states with different numbers of flux quanta. As with the Josephson effect, our observation should lead to new applications in superconducting electronics and quantum metrology.

Nanofocusing of structured light for quadrupolar light-matter interactions.

PubMed

Sakai, Kyosuke; Yamamoto, Takeaki; Sasaki, Keiji

2018-05-17

The spatial structure of an electromagnetic field can determine the characteristics of light-matter interactions. A strong gradient of light in the near field can excite dipole-forbidden atomic transitions, e.g., electric quadrupole transitions, which are rarely observed under plane-wave far-field illumination. Structured light with a higher-order orbital angular momentum state may also modulate the selection rules in which an atom can absorb two quanta of angular momentum: one from the spin and another from the spatial structure of the beam. Here, we numerically demonstrate a strong focusing of structured light with a higher-order orbital angular momentum state in the near field. A quadrupole field was confined within a gap region of several tens of nanometres in a plasmonic tetramer structure. A plasmonic crystal surrounding the tetramer structure provides a robust antenna effect, where the incident structured light can be strongly coupled to the quadrupole field in the gap region with a larger alignment tolerance. The proposed system is expected to provide a platform for light-matter interactions with strong multipolar effects.

Room temperature 1040fps, 1 megapixel photon-counting image sensor with 1.1um pixel pitch

NASA Astrophysics Data System (ADS)

Masoodian, S.; Ma, J.; Starkey, D.; Wang, T. J.; Yamashita, Y.; Fossum, E. R.

2017-05-01

A 1Mjot single-bit quanta image sensor (QIS) implemented in a stacked backside-illuminated (BSI) process is presented. This is the first work to report a megapixel photon-counting CMOS-type image sensor to the best of our knowledge. A QIS with 1.1μm pitch tapered-pump-gate jots is implemented with cluster-parallel readout, where each cluster of jots is associated with its own dedicated readout electronics stacked under the cluster. Power dissipation is reduced with this cluster readout because of the reduced column bus parasitic capacitance, which is important for the development of 1Gjot arrays. The QIS functions at 1040fps with binary readout and dissipates only 17.6mW, including I/O pads. The readout signal chain uses a fully differential charge-transfer amplifier (CTA) gain stage before a 1b-ADC to achieve an energy/bit FOM of 16.1pJ/b and 6.9pJ/b for the whole sensor and gain stage+ADC, respectively. Analog outputs with on-chip gain are implemented for pixel characterization purposes.

Extending geometrical optics: A Lagrangian theory for vector waves

DOE PAGES

Ruiz, D. E.; Dodin, I. Y.

2017-03-16

Even when neglecting diffraction effects, the well-known equations of geometrical optics (GO) are not entirely accurate. Traditional GO treats wave rays as classical particles, which are completely described by their coordinates and momenta, but vector-wave rays have another degree of freedom, namely, their polarization. The polarization degree of freedom manifests itself as an effective (classical) “wave spin” that can be assigned to rays and can affect the wave dynamics accordingly. A well-known manifestation of polarization dynamics is mode conversion, which is the linear exchange of quanta between different wave modes and can be interpreted as a rotation of the wavemore » spin. Another, less-known polarization effect is the polarization-driven bending of ray trajectories. Here, this work presents an extension and reformulation of GO as a first-principle Lagrangian theory, whose effective Hamiltonian governs the aforementioned polarization phenomena simultaneously. As an example, the theory is applied to describe the polarization-driven divergence of right-hand and left-hand circularly polarized electromagnetic waves in weakly magnetized plasma.« less

Extending geometrical optics: A Lagrangian theory for vector waves

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

Ruiz, D. E.; Dodin, I. Y.

Even when neglecting diffraction effects, the well-known equations of geometrical optics (GO) are not entirely accurate. Traditional GO treats wave rays as classical particles, which are completely described by their coordinates and momenta, but vector-wave rays have another degree of freedom, namely, their polarization. The polarization degree of freedom manifests itself as an effective (classical) “wave spin” that can be assigned to rays and can affect the wave dynamics accordingly. A well-known manifestation of polarization dynamics is mode conversion, which is the linear exchange of quanta between different wave modes and can be interpreted as a rotation of the wavemore » spin. Another, less-known polarization effect is the polarization-driven bending of ray trajectories. Here, this work presents an extension and reformulation of GO as a first-principle Lagrangian theory, whose effective Hamiltonian governs the aforementioned polarization phenomena simultaneously. As an example, the theory is applied to describe the polarization-driven divergence of right-hand and left-hand circularly polarized electromagnetic waves in weakly magnetized plasma.« less

Semiclassical S-matrix for black holes

DOE PAGES

Bezrukov, Fedor; Levkov, Dmitry; Sibiryakov, Sergey

2015-12-01

In this study, we propose a semiclassical method to calculate S-matrix elements for two-stage gravitational transitions involving matter collapse into a black hole and evaporation of the latter. The method consistently incorporates back-reaction of the collapsing and emitted quanta on the metric. We illustrate the method in several toy models describing spherical self-gravitating shells in asymptotically flat and AdS space-times. We find that electrically neutral shells reflect via the above collapse-evaporation process with probability exp(–B), where B is the Bekenstein-Hawking entropy of the intermediate black hole. This is consistent with interpretation of exp(B) as the number of black hole states.more » The same expression for the probability is obtained in the case of charged shells if one takes into account instability of the Cauchy horizon of the intermediate Reissner-Nordström black hole. As a result, our semiclassical method opens a new systematic approach to the gravitational S-matrix in the non-perturbative regime.« less

Higher curvature self-interaction corrections to Hawking radiation

NASA Astrophysics Data System (ADS)

Fairoos, C.; Sarkar, Sudipta; Yogendran, K. P.

2017-07-01

The purely thermal nature of Hawking radiation from evaporating black holes leads to the information loss paradox. A possible route to its resolution could be if (enough) correlations are shown to be present in the radiation emitted from evaporating black holes. A reanalysis of Hawking's derivation including the effects of self-interactions in general relativity shows that the emitted radiation does deviate from pure thermality; however no correlations exist between successively emitted Hawking quanta. We extend the calculations to Einstein-Gauss-Bonnet gravity and investigate if higher curvature corrections to the action lead to some new correlations in the Hawking spectra. The effective trajectory of a massless shell is determined by solving the constraint equations and the semiclassical tunneling probability is calculated. As in the case of general relativity, the radiation is no longer thermal and there is no correlation between successive emissions. The absence of any extra correlations in the emitted radiations even in Gauss-Bonnet gravity suggests that the resolution of the paradox is beyond the scope of semiclassical gravity.

Physics is …; The Physicist explores attributes of physics

NASA Astrophysics Data System (ADS)

Baker, F. Todd

2016-12-01

He's back! 'The physicist'returns with an entirely new compilation of questions and answers from his long-lived website where laypeople can ask questions about anything physics related. This book focuses on adjectives (practical, beautiful, surprising, cool, frivolous) instead of nouns like the first two books (atoms, photons, quanta, mechanics, relativity). The answers within 'Physics Is' are responses to people looking for answers to fascinating (and often uninformed) questions. It covers topics such as sports, electromagnetism, gravitational theory, special relativity, superheroes, videogames, and science fiction. These books are designed for laypeople and rely heavily on concepts rather than formalism. That said, they keep the physics correct and don't water down, so expert physicists will find this book and its two companion titles fun reads. They may actually recognize similar questions posed to them by friends and family. As with the first two books, 'Physics Is' ends with a chapter with questions from people who think that 'The physicist' is a psychic and from people who think they have the answers to life, the universe and everything.

Flux Noise due to Spins in SQUIDs

NASA Astrophysics Data System (ADS)

LaForest, Stephanie

Superconducting Quantum Interference Devices (SQUIDs) are currently being used as flux qubits and read-out detectors in a variety of solid-state quantum computer architectures. The main limitation of SQUID qubits is that they have a coherence time of the order of 10 micros, due to the presence of intrinsic flux noise that is not yet fully understood. The origin of flux noise is currently believed to be related to spin impurities present in the materials and interfaces that form the device. Here we present a novel numerical method that enables calculations of the flux produced by spin impurities even when they are located quite close to the SQUID wire. We show that the SQUID will be particularly sensitive to spins located at its wire edges, generating flux shifts of up to 4 nano flux quanta, much higher than previous calculations based on the software package FastHenry. This shows that spin impurities in a particular region along the wire's surface play a much more important role in producing flux noise than other spin impurities located elsewhere in the device.

Carbon dioxide flux, transpiration and light response of millet in the Sahel

NASA Astrophysics Data System (ADS)

Friborg, T.; Boegh, E.; Soegaard, H.

1997-02-01

Within the framework of the HAPEX-Sahel experiment carried out in Niger during the rainy season of 1992, measurements of fluxes defining the vegetation-atmosphere interaction were conducted over a millet field, for a period of nearly 2 months. These measurements comprised continuous recording of solar radiation, atmospheric carbon dioxide fluxes using the eddy correlation technique, and sap flow through millet plants. Based on biometric measurements of the millet plants comprising height, spacing and leaf area index, the solar radiation is converted to absorbed photosynthetically active radiation (aPAR). The coupling between the three parameters is examined in pairs. The diurnal and seasonal variations are analysed in relation to plant development. A strong linear relationship between aPAR and carbon dioxide assimilation can be established from the measurements, giving a quantum yield of 0.03 mol CO 2 mol -1 quanta. A comparison between CO 2 flux and transpiration shows that this relationship is affected by the water vapour pressure deficit of the atmosphere, but corresponds to the results found for other drought-tolerant C 4 crops.

Emerging technologies in Si active photonics

NASA Astrophysics Data System (ADS)

Wang, Xiaoxin; Liu, Jifeng

2018-06-01

Silicon photonics for synergistic electronic–photonic integration has achieved remarkable progress in the past two decades. Active photonic devices, including lasers, modulators, and photodetectors, are the key challenges for Si photonics to meet the requirement of high bandwidth and low power consumption in photonic datalinks. Here we review recent efforts and progress in high-performance active photonic devices on Si, focusing on emerging technologies beyond conventional foundry-ready Si photonics devices. For emerging laser sources, we will discuss recent progress towards efficient monolithic Ge lasers, mid-infrared GeSn lasers, and high-performance InAs quantum dot lasers on Si for data center applications in the near future. We will then review novel modulator materials and devices beyond the free carrier plasma dispersion effect in Si, including GeSi and graphene electro-absorption modulators and plasmonic-organic electro-optical modulators, to achieve ultralow power and high speed modulation. Finally, we discuss emerging photodetectors beyond epitaxial Ge p–i–n photodiodes, including GeSn mid-infrared photodetectors, all-Si plasmonic Schottky infrared photodetectors, and Si quanta image sensors for non-avalanche, low noise single photon detection and photon counting. These emerging technologies, though still under development, could make a significant impact on the future of large-scale electronicSilicon photonics for synergistic electronic-photonic integration has achieved remarkable progress in the past two decades. Active photonic devices, including lasers, modulators, and photodetectors, are the key challenges for Si photonics to meet the requirement of high bandwidth and low power consumption in photonic datalinks. Here we review recent efforts and progress in high-performance active photonic devices on Si, focusing on emerging technologies beyond conventional foundry-ready Si photonics devices. For emerging laser sources, we will discuss recent

Dynamical Localization in Molecular Systems.

NASA Astrophysics Data System (ADS)

Wang, Xidi

In the first four chapters of this thesis we concentrate on the Davydov model which describes the vibrational energy quanta of Amide I bonds (C=O bonds on the alpha -helix) coupled to the acoustic phonon modes of the alpha-helix backbone in the form of a Frohlich Hamiltonian. Following a brief introduction in chapter one, in chapter two we formulate the dynamics of vibrational quanta at finite temperature by using coherent state products. The fluctuation-dissipation relation is derived. At zero temperature, in the continuum limit, we recover the original results of Davydov. We also achieve good agreement with numerical simulations. In chapter three, the net contraction of the lattice is calculated exactly at any temperature, and its relation to the so -call "topological stability" of the Davydov soliton is discussed. In the second section of the chapter three we calculate the overtone spectra of crystalline acetanilide (according to some opinions ACN provides experimental evidence for the existence of Davydov solitons). Good agreement with experimental data has been obtained. In chapter four we study the self-trapped vibrational excitations by the Quantum Monte Carlo technique. For a single excitation, the temperature dependence of different physical observables is calculated. The quasi-particle which resembles the Davydov soliton has been found to be fairly narrow using the most commonly used data for the alpha -helix; at temperatures above a few Kelvin, the quasi-particle reaches its smallest limit (extends over three sites), which implies diffusive motion of the small polaron-like quasi-particle at high temperatures. For the multi-excitation case, bound pairs and clusters of excitations are found at low temperatures; they gradually dissociate when the temperature of the system is increased as calculated from the density-density correlation function. In the last chapter of this thesis, we study a more general model of dynamical local modes in molecular systems

Reaction of physiological factors on the solar-geomagnetic activity (the physical mechanisms)

NASA Astrophysics Data System (ADS)

Avakyan, Sergey; Voronin, Nikolai; Dubarenko, Konstantin

This presentation proposes and provides substantiation for a hypothesis concerning the mechanism by which solar and geomagnetic activity (mainly of solar flares and magnetic storms) affects the biosphere, including man. The hypothesis, including a physical mechanism introduced by the authors, is that high-lying (Rydberg) states of all gases of the earth’s upper atmosphere are excited by ionospheric energetic electrons. Rydberg atoms, molecules and ions of all atmospheric gases emit characteristic radio emission in the spectral range from decimeters to millimeters. This radiation can easily penetrate to low atmosphere and biosphere carrying complete information about power and duration of solar flare and geomagnetic storms to biosphere. The microwave radioemission have the resonances at the spectral range 109 ÷ 1012 Hz at the cells and membranes, DNA and RNA, molecules of haemoglobin, erythrocytes, and this fact can explain the extremely small threshold for influence of ionospheric radioemission at the monochromatic (characteristic) transitions on biological objects, including the viscosity of blood. The energy estimates of the flux intensity of microwave radiation of the ionosphere from Rydberg states are used to prove for the first time that the values of this flux agree with the experimental data. A method is proposed for distinguishing the contributions of microwave radiation and magnetic perturbation in the geo-biocorrelations, taking into account the effect that the magnetic-field variations are not in phase with the flux of corpuscles from the radiation belts in the ionosphere during the period of a geomagnetic storm. Quanta of microwave radiation are emitted from the heights of 90 - 360 km, i.e. in the basic ionosphere regions. Their energy by almost 10 orders of magnitude exceeds that of the quanta of low-frequency electromagnetic background of the ionosphere (with the frequencies lower than 100 Hz, which coincide with those of biorhythms). Thereby

Numerical-analytic implementation of the higher-order canonical Van Vleck perturbation theory for the interpretation of medium-sized molecule vibrational spectra.

PubMed

Krasnoshchekov, Sergey V; Isayeva, Elena V; Stepanov, Nikolay F

2012-04-12

Anharmonic vibrational states of semirigid polyatomic molecules are often studied using the second-order vibrational perturbation theory (VPT2). For efficient higher-order analysis, an approach based on the canonical Van Vleck perturbation theory (CVPT), the Watson Hamiltonian and operators of creation and annihilation of vibrational quanta is employed. This method allows analysis of the convergence of perturbation theory and solves a number of theoretical problems of VPT2, e.g., yields anharmonic constants y(ijk), z(ijkl), and allows the reliable evaluation of vibrational IR and Raman anharmonic intensities in the presence of resonances. Darling-Dennison and higher-order resonance coupling coefficients can be reliably evaluated as well. The method is illustrated on classic molecules: water and formaldehyde. A number of theoretical conclusions results, including the necessity of using sextic force field in the fourth order (CVPT4) and the nearly vanishing CVPT4 contributions for bending and wagging modes. The coefficients of perturbative Dunham-type Hamiltonians in high-orders of CVPT are found to conform to the rules of equality at different orders as earlier proven analytically for diatomic molecules. The method can serve as a good substitution of the more traditional VPT2.

Generating and manipulating quantized vortices on-demand in a Bose-Einstein condensate: A numerical study

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

Gertjerenken, B.; Kevrekidis, P. G.; Carretero-González, R.

Here, we numerically investigate an experimentally viable method for generating and manipulating on-demand several vortices in a highly oblate atomic Bose-Einstein condensate (BEC) in order to initialize complex vortex distributions for studies of vortex dynamics. The method utilizes moving laser beams to generate, capture, and transport vortices inside and outside the BEC. This methodology is examined in detail and shows a wide parameter range of applicability for the prototypical two-vortex case, as well as case examples of producing and manipulating several vortices for which there is no net circulation, corresponding to equal numbers of positive and negative circulation vortices, andmore » cases for which there is one net quantum of circulation. We also find that the presence of dissipation can help stabilize the pinning of the vortices on their respective laser beam pinning sites. Finally, we illustrate how to utilize laser beams as repositories that hold large numbers of vortices and how to deposit individual vortices in a sequential fashion in the repositories in order to construct superfluid flows about the repository beams with several quanta of circulation.« less

Generating and manipulating quantized vortices on-demand in a Bose-Einstein condensate: A numerical study

DOE PAGES

Gertjerenken, B.; Kevrekidis, P. G.; Carretero-González, R.; ...

2016-02-01

Here, we numerically investigate an experimentally viable method for generating and manipulating on-demand several vortices in a highly oblate atomic Bose-Einstein condensate (BEC) in order to initialize complex vortex distributions for studies of vortex dynamics. The method utilizes moving laser beams to generate, capture, and transport vortices inside and outside the BEC. This methodology is examined in detail and shows a wide parameter range of applicability for the prototypical two-vortex case, as well as case examples of producing and manipulating several vortices for which there is no net circulation, corresponding to equal numbers of positive and negative circulation vortices, andmore » cases for which there is one net quantum of circulation. We also find that the presence of dissipation can help stabilize the pinning of the vortices on their respective laser beam pinning sites. Finally, we illustrate how to utilize laser beams as repositories that hold large numbers of vortices and how to deposit individual vortices in a sequential fashion in the repositories in order to construct superfluid flows about the repository beams with several quanta of circulation.« less

Photothermal therapy of acute leukemia cells in the near-infrared region using gold nanorods CD-33 conjugates

NASA Astrophysics Data System (ADS)

Liopo, Anton; Conjusteau, André; Konopleva, Marina; Andreeff, Michael; Oraevsky, Alexander

2011-03-01

In the present work, we demonstrate a potential use of gold nanorods as a contrast agent for selective photothermal therapy of human acute leukemia cells (HL-60) using a near-infrared laser. Gold Nanorods (GNR) are synthesized and conjugated to CD33, a 67 kDa glycoprotein found on the surface of myeloid cells that belongs to the sialoadhesin family of proteins. After pegylation, or conjugation with CD33 antibody, GNR were non-toxic for acute and chronic leukemia cells. We used a Quanta System q-switched titanium sapphire laser emitting at a center wavelength of 755 nm. Each sample was illuminated with 1 laser shot at either high or low fluence. Both laser modes were used in 3 independent cell probes. HL-60 cells were treated for 45 min with GNR conjugated with mAb CD33, or with GNR-Pegylated particles. After laser application, the cells were resuspended and analyzed to cell viability with Trypan blue exclusion assay. GNR-CD33 conjugates significantly increase the percentage of cell death as compared with a control group after laser illumination: a 3 fold increase is observed.

The quantal release at a neuro-neuronal synapse is regulated by the content of acetylcholine in the presynaptic cell.

PubMed

Poulain, B; Baux, G; Tauc, L

1986-01-01

Transmitter release was studied with respect to the presynaptic acetylcholine (ACh) content at a central identified inhibitory synapse (Cl- conductance) of Aplysia californica. Statistical analysis of the synaptic noise evoked by sustained depolarization of the presynaptic neuron allowed us to calculate the quantal parameters of the postsynaptic responses. Loading of the presynaptic neurone with injected ACh led to an increase in the postsynaptic responses whereas the calculated miniature postsynaptic current (MPSC) was unmodified. Destruction of choline by choline oxidase either applied extracellularly and coupled to intense stimulations of the presynaptic cell or injected into the presynaptic neuron induced a depression of the postsynaptic response although the amplitude of the calculated MPSC remained constant. As the size of the MPSC, i.e. the size of the quantum, did not change in these experiments, it was concluded that the presynaptic ACh content controls the number of quanta released by a given presynaptic depolarization. As additional evidence, effects of abrupt increase in tonicity of the external medium were studied. The observed transient enhancement of the quantal content of the postsynaptic response could be attributed to an increase in the presynaptic concentration of ACh, resulting from the reduction in cellular volume.

Quality engineering and control semiannual progress report, November--December 1977 and January--April 1978

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

Carpenter, R.L.

1978-10-10

Determination of ppM concentrations of dibutyl phosphate in aqueous solutions of nitric acid or sodium carbonate is possible after an extraction step with carbon tetrachloride. Ester cleavage of the fatty triglyceride constituents is the principal radiolytic reaction in irradiation of a dolphin-head oil base precision watch oil. Use of a special container and a vacuum-brazing furnace permits the high-temperature dynamic determination of volatile surface contamination from samples of large geometric surface areas. Status of the mass spectrometer development project is discussed. A mass spectroscopy method provided rapid, specific, and quantitative results for environmental monitoring of polychlorinated biphenyl compounds. A sequentialmore » procedure for improved separation of actinides in soil samples was developed. Testing of packings in intimate contact with acid was accomplished by differential thermal analysis. Analysis results obtained on the XRD-6 x-ray unit are discussed for Nb in U-Nb alloys and for Cr and Ne in stainless steels. Correlation coefficients of 0.994 or better resulted for the determinations of Cr, Mn, and Ne in the stainless steel standards employed in the statistical evaluation of the Quanta Metrix x-ray unit.« less

Magnon-drag thermopile.

PubMed

Costache, Marius V; Bridoux, German; Neumann, Ingmar; Valenzuela, Sergio O

2011-12-18

Thermoelectric effects in spintronics are gathering increasing attention as a means of managing heat in nanoscale structures and of controlling spin information by using heat flow. Thermal magnons (spin-wave quanta) are expected to play a major role; however, little is known about the underlying physical mechanisms involved. The reason is the lack of information about magnon interactions and of reliable methods to obtain it, in particular for electrical conductors because of the intricate influence of electrons. Here, we demonstrate a conceptually new device that enables us to gather information on magnon-electron scattering and magnon-drag effects. The device resembles a thermopile formed by a large number of pairs of ferromagnetic wires placed between a hot and a cold source and connected thermally in parallel and electrically in series. By controlling the relative orientation of the magnetization in pairs of wires, the magnon drag can be studied independently of the electron and phonon-drag thermoelectric effects. Measurements as a function of temperature reveal the effect on magnon drag following a variation of magnon and phonon populations. This information is crucial to understand the physics of electron-magnon interactions, magnon dynamics and thermal spin transport.

Fractional Matching Effect due to Pinning of the Vortex Lattice by an Array of Magnetic Dots

NASA Astrophysics Data System (ADS)

Stoll, O. M.; Montero, M. I.; Jönsson-Åkerman, B. J.; Schuller, Ivan K.

2001-03-01

We have investigated the pinning of magnetic flux quanta by rectangular arrays of nanoscaled magnetic dots. We measured the resistivity vs. magnetic field characteristics using a high magnetic field resolution of up to 0.1 G over the full field range ( 2 kG to 2 kG). By this we the appearance of minima at half and third integer values of the matching field. It is well known that a reconfiguration of the vortex lattice from a rectangular to a square type geometry occurs in rectangular arrays of magnetic dots when the magnetic field is increased over a threshold value H_r. If we lower the magnetic field after crossing H_r, we find that some of the minima at the full integer matching field are missing. This hysteretic behavior occurs only when Hr is exceeded before the subsequent decrease of the magnetic field. We present the experimental results and discuss preliminary models for the explanation of these observations. This work was supported by the grants NSF and DOE. Two of us acknowledge postdoctoral fellowships by the DAAD (Deutscher Akademischer Austauschdienst) (O.M.S.) and the Secretaria De Estado De Educacion Y Universidades (M.I.M.) respectively.

X-Ray generation in strongly nonlinear plasma waves.

NASA Astrophysics Data System (ADS)

Kiselev, Sergey; Pukhov, Alexander; Kostyukov, Igor

2004-11-01

Using three-dimensional particle-in-cell simulations we show that a strongly nonlinear plasma wave excited by an ultrahigh intensity laser pulse works as a compact high-brightness source of Xray radiation. It has been recently suggested by A. Pukhov and J. Meyer-ter-Vehn, Appl. Phys. B 74, 355 (2002), that in a strongly nonlinear regime the plasma wave transforms to a ``bubble'', which is almost free from background electrons. Inside the bubble, a dense bunch of relativistic electrons is produced. These accelerated electrons make betatron oscillations in the transverse fields of the bubble and emit a bright broadband X-ray radiation with a maximum about 50 keV. The emission is confined to a small angle of about 0.1 rad. In addition, we make simulations of X-ray generation by an external 28.5-GeV electron bunch injected into the bubble. Gamma-quanta with up to GeV energies are observed in the simulation in a good agreement with analytical results. The energy conversion is efficient, leading to a significant stopping of the electron bunch over 5 mm interaction distance.

Arctic Tundra Vegetation Functional Types Based on Photosynthetic Physiology and Optical Properties

NASA Technical Reports Server (NTRS)

Huemmrich, Karl F.; Gamon, John; Tweedie, Craig; Campbell, Petya K.; Landis, David R.; Middleton, Elizabeth M.

2013-01-01

Non-vascular plants (lichens and mosses) are significant components of tundra landscapes and may respond to climate change differently from vascular plants affecting ecosystem carbon balance. Remote sensing provides critical tools for monitoring plant cover types, as optical signals provide a way to scale from plot measurements to regional estimates of biophysical properties, for which spatial-temporal patterns may be analyzed. Gas exchange measurements were collected for pure patches of key vegetation functional types (lichens, mosses, and vascular plants) in sedge tundra at Barrow AK. These functional types were found to have three significantly different values of light use efficiency (LUE) with values of 0.013+/-0.001, 0.0018+/-0.0002, and 0.0012+/-0.0001 mol C/mol absorbed quanta for vascular plants, mosses and lichens, respectively. Discriminant analysis of the spectra reflectance of these patches identified five spectral bands that separated each of these vegetation functional types as well as nongreen material (bare soil, standing water, and dead leaves). These results were tested along a 100 m transect where midsummer spectral reflectance and vegetation coverage were measured at one meter intervals.

Observation of the fractional quantum Hall effect in graphene.

PubMed

Bolotin, Kirill I; Ghahari, Fereshte; Shulman, Michael D; Stormer, Horst L; Kim, Philip

2009-11-12

When electrons are confined in two dimensions and subject to strong magnetic fields, the Coulomb interactions between them can become very strong, leading to the formation of correlated states of matter, such as the fractional quantum Hall liquid. In this strong quantum regime, electrons and magnetic flux quanta bind to form complex composite quasiparticles with fractional electronic charge; these are manifest in transport measurements of the Hall conductivity as rational fractions of the elementary conductance quantum. The experimental discovery of an anomalous integer quantum Hall effect in graphene has enabled the study of a correlated two-dimensional electronic system, in which the interacting electrons behave like massless chiral fermions. However, owing to the prevailing disorder, graphene has so far exhibited only weak signatures of correlated electron phenomena, despite intense experimental and theoretical efforts. Here we report the observation of the fractional quantum Hall effect in ultraclean, suspended graphene. In addition, we show that at low carrier density graphene becomes an insulator with a magnetic-field-tunable energy gap. These newly discovered quantum states offer the opportunity to study correlated Dirac fermions in graphene in the presence of large magnetic fields.

Revisiting arithmetic solutions to the W =0 condition

NASA Astrophysics Data System (ADS)

Kanno, Keita; Watari, Taizan

2017-11-01

The gravitino mass is expected not to be much smaller than the Planck scale for a large fraction of vacua in flux compactifications. There is no continuous parameter to tune even by hand, and it seems that the gravitino mass can be small only as a result of accidental cancellation among period integrals weighted by integer-valued flux quanta. DeWolfe et al. [J. High Energy Phys. 02 (2005) 037, 10.1088/1126-6708/2005/02/037] proposed paying close attention to vacua where the Hodge decomposition is possible within a number field, so that the precise cancellation takes place as a result of algebra. We focus on a subclass of those vacua—those with complex multiplication—and explore more on the idea in this article. It turns out, in Type IIB compactifications, that those vacua admit nontrivial supersymmetric flux configurations if and only if the reflex field of the Weil intermediate Jacobian is isomorphic to the quadratic imaginary field generated by the axidilaton vacuum expectation value. We also found that flux statistics are highly enriched on such vacua, as F-term conditions become linearly dependent.

Vibrational investigations of CO2-H2O, CO2-(H2O)2, and (CO2)2-H2O complexes isolated in solid neon.

PubMed

Soulard, P; Tremblay, B

2015-12-14

The van der Waals complex of H2O with CO2 has attracted considerable theoretical interest as a typical example of a weak binding complex with a dissociation energy less than 3 kcal/mol. Up to now, experimental vibrational data are sparse. We have studied by FTIR the complexes involving CO2 and water molecules in solid neon. Many new absorption bands close to the well known monomers fundamentals give evidence for at least three (CO2)n-(H2O)m complexes, noted n:m. Concentration effects combined with a detailed vibrational analysis allow for the identification of sixteen, twelve, and five transitions for the 1:1, 1:2, and 2:1 complexes, respectively. Careful examination of the far infrared spectral region allows the assignment of several 1:1 and 1:2 intermolecular modes, confirmed by the observation of combinations of intra + intermolecular transitions, and anharmonic coupling constants have been derived. Our results demonstrate the high sensibility of the solid neon isolation to investigate the hydrogen-bonded complexes in contrast with the gas phase experiments for which two quanta transitions cannot be easily observed.

Behavioural and physiological limits to vision in mammals

PubMed Central

Field, Greg D.

2017-01-01

Human vision is exquisitely sensitive—a dark-adapted observer is capable of reliably detecting the absorption of a few quanta of light. Such sensitivity requires that the sensory receptors of the retina, rod photoreceptors, generate a reliable signal when single photons are absorbed. In addition, the retina must be able to extract this information and relay it to higher visual centres under conditions where very few rods signal single-photon responses while the majority generate only noise. Critical to signal transmission are mechanistic optimizations within rods and their dedicated retinal circuits that enhance the discriminability of single-photon responses by mitigating photoreceptor and synaptic noise. We describe behavioural experiments over the past century that have led to the appreciation of high sensitivity near absolute visual threshold. We further consider mechanisms within rod photoreceptors and dedicated rod circuits that act to extract single-photon responses from cellular noise. We highlight how these studies have shaped our understanding of brain function and point out several unresolved questions in the processing of light near the visual threshold. This article is part of the themed issue ‘Vision in dim light’. PMID:28193817

Enhanced Photolysis of Nucleic Acid Monomers by Pyrophosphate in the Simulated Primitive Soup

NASA Astrophysics Data System (ADS)

Kongjiang, Wang; Zhifang, Chai; Xianming, Pan

1999-05-01

In our simulation of the photochemistry of the primitive soup, it was found that yield of chromophore loss of some nucleic acid bases, nucleosides and nucleotides [NA] undergoing ultraviolet radiation by medium pressure mercury lamp [MPML] was enhanced by pyrophosphate and triphosphate whether O2 is present or not. The yield of chromophore loss of guanosine, uracil, 5' CMP, and the derivatives of adenine and thymine was observed to rise with the increase of molar concentration of pyrophosphate in N2-saturated systems. In air-saturated samples, increase in yield of chromophore loss was observed when the concentration of pyrophosphate reaches 5×10-4 M, relative yield of chromophore loss (CLrel) coming to maximum in the range from 0.01 to 0.1 M, followed by a slight decline with the further increase of pyrophosphate concentration. The enhancement of photolysis of NA by pyrophosphate was due to the interaction between NA and pyrophosphate radicals photoionized by UV quanta of wavelength less than about 210 nm in the emission spectrum of a MPML. The relevance of this phenomenon to the origin of life has been discussed as well.

Topology, localization, and quantum information in atomic, molecular and optical systems

NASA Astrophysics Data System (ADS)

Yao, Norman Ying

The scientific interface between atomic, molecular and optical (AMO) physics, condensed matter, and quantum information science has recently led to the development of new insights and tools that bridge the gap between macroscopic quantum behavior and detailed microscopic intuition. While the dialogue between these fields has sharpened our understanding of quantum theory, it has also raised a bevy of new questions regarding the out-of-equilibrium dynamics and control of many-body systems. This thesis is motivated by experimental advances that make it possible to produce and probe isolated, strongly interacting ensembles of disordered particles, as found in systems ranging from trapped ions and Rydberg atoms to ultracold polar molecules and spin defects in the solid state. The presence of strong interactions in these systems underlies their potential for exploring correlated many-body physics and this thesis presents recent results on realizing fractionalization and localization. From a complementary perspective, the controlled manipulation of individual quanta can also enable the bottom-up construction of quantum devices. To this end, this thesis also describes blueprints for a room-temperature quantum computer, quantum credit cards and nanoscale quantum thermometry.

The Subcellular Origin of Bioluminescence in Noctiluca miliaris

PubMed Central

Eckert, Roger; Reynolds, George T.

1967-01-01

The light emitted by Noctiluca has its origin in 1 to 5 x 104 organelles ("microsources") which are scattered throughout the perivacuolar cytoplasm, and which appear to be the elementary functional units of bioluminescence. Microscopical techniques, image intensification, and microphotometry were employed in their investigation. Microsources are fluorescent, strongly phase-retarding, and range widely in diameter below 1.5 microns. The number of quanta emitted in a flash from a microsource ("microflash") is of the order of 105 photons. However, microflashes show a wide range of intensities, which are correlated with the size of the organelles from which they arise. Each organelle responds repetitively and with reproducible time course to a succession of invading triggering potentials. Reversible changes in the intensity of the flash emitted by the whole cell ("macroflash") occur because of graduations in intensity of microflashes rather than as a result of changes in the number of responsive organelles. The shape of the flash emitted by individual microsources resembles that of the macroflash except for slightly shorter rise and decay times. It is concluded that the macroflash results from somewhat asynchronous, but otherwise parallel summation of microflashes. PMID:5340466

How quantum entanglement in DNA synchronizes double-strand breakage by type II restriction endonucleases.

PubMed

Kurian, P; Dunston, G; Lindesay, J

2016-02-21

Macroscopic quantum effects in living systems have been studied widely in pursuit of fundamental explanations for biological energy transport and sensing. While it is known that type II endonucleases, the largest class of restriction enzymes, induce DNA double-strand breaks by attacking phosphodiester bonds, the mechanism by which simultaneous cutting is coordinated between the catalytic centers remains unclear. We propose a quantum mechanical model for collective electronic behavior in the DNA helix, where dipole-dipole oscillations are quantized through boundary conditions imposed by the enzyme. Zero-point modes of coherent oscillations would provide the energy required for double-strand breakage. Such quanta may be preserved in the presence of thermal noise by the enzyme's displacement of water surrounding the DNA recognition sequence. The enzyme thus serves as a decoherence shield. Palindromic mirror symmetry of the enzyme-DNA complex should conserve parity, because symmetric bond-breaking ceases when the symmetry of the complex is violated or when physiological parameters are perturbed from optima. Persistent correlations in DNA across longer spatial separations-a possible signature of quantum entanglement-may be explained by such a mechanism. Copyright © 2015 Elsevier Ltd. All rights reserved.

The perception of microsound and its musical implications.

PubMed

Roads, Curtis

2003-11-01

Sound particles or microsounds last only a few milliseconds, near the threshold of auditory perception. We can easily analyze the physical properties of sound particles either individually or in masses. However, correlating these properties with human perception remains complicated. One cannot speak of a single time frame, or a "time constant" for the auditory system. The hearing mechanism involves many different agents, each of which operates on its own timescale. The signals being sent by diverse hearing agents are integrated by the brain into a coherent auditory picture. The pioneer of "sound quanta," Dennis Gabor (1900-1979), suggested that at least two mechanisms are at work in microevent detection: one that isolates events, and another that ascertains their pitch. Human hearing imposes a certain minimum duration in order to establish a firm sense of pitch, amplitude, and timbre. This paper traces disparate strands of literature on the topic and summarizes their meaning. Specifically, we examine the perception of intensity and pitch of microsounds, the phenomena of tone fusion and fission, temporal auditory acuity, and preattentive perception. The final section examines the musical implications of microsonic analysis, synthesis, and transformation.

Stochastic space interval as a link between quantum randomness and macroscopic randomness?

NASA Astrophysics Data System (ADS)

Haug, Espen Gaarder; Hoff, Harald

2018-03-01

For many stochastic phenomena, we observe statistical distributions that have fat-tails and high-peaks compared to the Gaussian distribution. In this paper, we will explain how observable statistical distributions in the macroscopic world could be related to the randomness in the subatomic world. We show that fat-tailed (leptokurtic) phenomena in our everyday macroscopic world are ultimately rooted in Gaussian - or very close to Gaussian-distributed subatomic particle randomness, but they are not, in a strict sense, Gaussian distributions. By running a truly random experiment over a three and a half-year period, we observed a type of random behavior in trillions of photons. Combining our results with simple logic, we find that fat-tailed and high-peaked statistical distributions are exactly what we would expect to observe if the subatomic world is quantized and not continuously divisible. We extend our analysis to the fact that one typically observes fat-tails and high-peaks relative to the Gaussian distribution in stocks and commodity prices and many aspects of the natural world; these instances are all observable and documentable macro phenomena that strongly suggest that the ultimate building blocks of nature are discrete (e.g. they appear in quanta).

Ultradian hormone stimulation induces glucocorticoid receptor-mediated pulses of gene transcription.

PubMed

Stavreva, Diana A; Wiench, Malgorzata; John, Sam; Conway-Campbell, Becky L; McKenna, Mervyn A; Pooley, John R; Johnson, Thomas A; Voss, Ty C; Lightman, Stafford L; Hager, Gordon L

2009-09-01

Studies on glucocorticoid receptor (GR) action typically assess gene responses by long-term stimulation with synthetic hormones. As corticosteroids are released from adrenal glands in a circadian and high-frequency (ultradian) mode, such treatments may not provide an accurate assessment of physiological hormone action. Here we demonstrate that ultradian hormone stimulation induces cyclic GR-mediated transcriptional regulation, or gene pulsing, both in cultured cells and in animal models. Equilibrium receptor-occupancy of regulatory elements precisely tracks the ligand pulses. Nascent RNA transcripts from GR-regulated genes are released in distinct quanta, demonstrating a profound difference between the transcriptional programs induced by ultradian and constant stimulation. Gene pulsing is driven by rapid GR exchange with response elements and by GR recycling through the chaperone machinery, which promotes GR activation and reactivation in response to the ultradian hormone release, thus coupling promoter activity to the naturally occurring fluctuations in hormone levels. The GR signalling pathway has been optimized for a prompt and timely response to fluctuations in hormone levels, indicating that biologically accurate regulation of gene targets by GR requires an ultradian mode of hormone stimulation.

Could quantum gravity phenomenology be tested with high intensity lasers?

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

Magueijo, Joao; Canadian Institute for Theoretical Astrophysics, 60 St. George Street, Toronto M5S 3H8; Theoretical Physics Group, Imperial College, Prince Consort Road, London SW7 2BZ

2006-06-15

In phenomenological quantum gravity theories, Planckian behavior is triggered by the energy of elementary particles approaching the Planck energy, E{sub P}, but it is also possible that anomalous behavior strikes systems of particles with total energy near E{sub P}. This is usually perceived to be pathological and has been labeled 'the soccer ball problem'. We point out that there is no obvious contradiction with experiment if coherent collections of particles with bulk energy of order E{sub P} do indeed display Planckian behavior, a possibility that would open a new experimental window. Unfortunately, field theory realizations of 'doubly' (or deformed) specialmore » relativity never exhibit a soccer ball problem; we present several formulations where this is undeniably true. Upon closer scrutiny we discover that the only chance for Planckian behavior to be triggered by large coherent energies involves the details of second quantization. We find a formulation where the quanta have their energy-momentum (mass-shell) relations deformed as a function of the bulk energy of the coherent packet to which they belong, rather than the frequency. Given ongoing developments in laser technology, such a possibility would be of great experimental interest.« less

Spatial imaging in color and HDR: prometheus unchained

NASA Astrophysics Data System (ADS)

McCann, John J.

2013-03-01

The Human Vision and Electronic Imaging Conferences (HVEI) at the IS and T/SPIE Electronic Imaging meetings have brought together research in the fundamentals of both vision and digital technology. This conference has incorporated many color disciplines that have contributed to the theory and practice of today's imaging: color constancy, models of vision, digital output, high-dynamic-range imaging, and the understanding of perceptual mechanisms. Before digital imaging, silver halide color was a pixel-based mechanism. Color films are closely tied to colorimetry, the science of matching pixels in a black surround. The quanta catch of the sensitized silver salts determines the amount of colored dyes in the final print. The rapid expansion of digital imaging over the past 25 years has eliminated the limitations of using small local regions in forming images. Spatial interactions can now generate images more like vision. Since the 1950's, neurophysiology has shown that post-receptor neural processing is based on spatial interactions. These results reinforced the findings of 19th century experimental psychology. This paper reviews the role of HVEI in color, emphasizing the interaction of research on vision and the new algorithms and processes made possible by electronic imaging.

A chip-integrated coherent photonic-phononic memory.

PubMed

Merklein, Moritz; Stiller, Birgit; Vu, Khu; Madden, Stephen J; Eggleton, Benjamin J

2017-09-18

Controlling and manipulating quanta of coherent acoustic vibrations-phonons-in integrated circuits has recently drawn a lot of attention, since phonons can function as unique links between radiofrequency and optical signals, allow access to quantum regimes and offer advanced signal processing capabilities. Recent approaches based on optomechanical resonators have achieved impressive quality factors allowing for storage of optical signals. However, so far these techniques have been limited in bandwidth and are incompatible with multi-wavelength operation. In this work, we experimentally demonstrate a coherent buffer in an integrated planar optical waveguide by transferring the optical information coherently to an acoustic hypersound wave. Optical information is extracted using the reverse process. These hypersound phonons have similar wavelengths as the optical photons but travel at five orders of magnitude lower velocity. We demonstrate the storage of phase and amplitude of optical information with gigahertz bandwidth and show operation at separate wavelengths with negligible cross-talk.Optical storage implementations based on optomechanical resonator are limited to one wavelength. Here, exploiting stimulated Brillouin scattering, the authors demonstrate a coherent optical memory based on a planar integrated waveguide, which can operate at different wavelengths without cross-talk.

Quantized visual awareness.

PubMed

Escobar, W A

2013-01-01

The proposed model holds that, at its most fundamental level, visual awareness is quantized. That is to say that visual awareness arises as individual bits of awareness through the action of neural circuits with hundreds to thousands of neurons in at least the human striate cortex. Circuits with specific topologies will reproducibly result in visual awareness that correspond to basic aspects of vision like color, motion, and depth. These quanta of awareness (qualia) are produced by the feedforward sweep that occurs through the geniculocortical pathway but are not integrated into a conscious experience until recurrent processing from centers like V4 or V5 select the appropriate qualia being produced in V1 to create a percept. The model proposed here has the potential to shift the focus of the search for visual awareness to the level of microcircuits and these likely exist across the kingdom Animalia. Thus establishing qualia as the fundamental nature of visual awareness will not only provide a deeper understanding of awareness, but also allow for a more quantitative understanding of the evolution of visual awareness throughout the animal kingdom.

Parallel adaptive wavelet collocation method for PDEs

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

Nejadmalayeri, Alireza, E-mail: Alireza.Nejadmalayeri@gmail.com; Vezolainen, Alexei, E-mail: Alexei.Vezolainen@Colorado.edu; Brown-Dymkoski, Eric, E-mail: Eric.Browndymkoski@Colorado.edu

2015-10-01

A parallel adaptive wavelet collocation method for solving a large class of Partial Differential Equations is presented. The parallelization is achieved by developing an asynchronous parallel wavelet transform, which allows one to perform parallel wavelet transform and derivative calculations with only one data synchronization at the highest level of resolution. The data are stored using tree-like structure with tree roots starting at a priori defined level of resolution. Both static and dynamic domain partitioning approaches are developed. For the dynamic domain partitioning, trees are considered to be the minimum quanta of data to be migrated between the processes. This allowsmore » fully automated and efficient handling of non-simply connected partitioning of a computational domain. Dynamic load balancing is achieved via domain repartitioning during the grid adaptation step and reassigning trees to the appropriate processes to ensure approximately the same number of grid points on each process. The parallel efficiency of the approach is discussed based on parallel adaptive wavelet-based Coherent Vortex Simulations of homogeneous turbulence with linear forcing at effective non-adaptive resolutions up to 2048{sup 3} using as many as 2048 CPU cores.« less

On spectroscopy for a whole Abelian model

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

Chauca, J.; Doria, R.; Aprendanet, Petropolis, 25600

Postulated on the whole meaning a whole abelian gauge symmetry is being introduced. Various physical areas as complexity, statistical mechanics, quantum mechanics are partially supporting this approach where the whole is at origin. However, the reductionist crisis given by quark confinement definitely sustains this insight. It says that fundamental parts can not be seen isolatedely. Consequently, there is an experimental situation where the parts should be substituted by something more. This makes us to look for writing the wholeness principle under gauge theory. For this, one reinterprets the gauge parameter where instead of compensating fields it is organizing a systemicmore » gauge symmetry. Now, it introduces a fields set {l_brace}A{sub {mu}I}{r_brace} rotating under a common gauge symmetry. Thus, given a fields collection {l_brace}A{sub {mu}I}{r_brace} as origin, the effort at this work is to investigate on its spectroscopy. Analyze for the abelian case the correspondent involved quanta. Understand that for a whole model diversity replaces elementarity. Derive the associated quantum numbers as spin, mass, charge, discrete symmetries in terms of such systemic symmetry. Observe how the particles diversity is manifested in terms of wholeness.« less

State selected ion--molecule reactions by a TESICO technique. V. N/sub 2//sup +/(v)+Ar. -->. N/sub 2/+Ar/sup +/

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

Kato, T.; Tanaka, K.; Koyano, I.

1982-07-15

Charge transfer reactions N/sub 2//sup +/(v)+Ar..-->..Ar/sup +/+N/sub 2/ (1) have been studied by selecting the vibrational states of N/sub 2//sup +/ using the threshold electron--secondary ion coincidence (TESICO) technique. Relative cross sections sigma(v) for the individual vibrational states v = 0--3 have been determined at three collision energies, 0.3, 1.5, and 11.8 eV. Results show that Reaction (1), which is endoergic for v = 0, is considerably enhanced by the vibrational excitation of N/sub 2//sup +/ at all collision energies. While excitation of one vibrational quantum enhances the cross section substantially, excitation of additional quanta further increases the cross sectionmore » up to v = 3. The ratios sigma(2)/sigma(1) and sigma(3)/sigma(2) are, however, much smaller than sigma(1)/sigma(0) and are significantly larger at the highest collision energy than at the other two collision energies. These results are discussed in conjunction with the calculated results based on the simple two-state theory of Rapp and Francis and the Franck--Condon factors.« less

Satellite-to-ground quantum key distribution.

PubMed

Liao, Sheng-Kai; Cai, Wen-Qi; Liu, Wei-Yue; Zhang, Liang; Li, Yang; Ren, Ji-Gang; Yin, Juan; Shen, Qi; Cao, Yuan; Li, Zheng-Ping; Li, Feng-Zhi; Chen, Xia-Wei; Sun, Li-Hua; Jia, Jian-Jun; Wu, Jin-Cai; Jiang, Xiao-Jun; Wang, Jian-Feng; Huang, Yong-Mei; Wang, Qiang; Zhou, Yi-Lin; Deng, Lei; Xi, Tao; Ma, Lu; Hu, Tai; Zhang, Qiang; Chen, Yu-Ao; Liu, Nai-Le; Wang, Xiang-Bin; Zhu, Zhen-Cai; Lu, Chao-Yang; Shu, Rong; Peng, Cheng-Zhi; Wang, Jian-Yu; Pan, Jian-Wei

2017-09-07

Quantum key distribution (QKD) uses individual light quanta in quantum superposition states to guarantee unconditional communication security between distant parties. However, the distance over which QKD is achievable has been limited to a few hundred kilometres, owing to the channel loss that occurs when using optical fibres or terrestrial free space that exponentially reduces the photon transmission rate. Satellite-based QKD has the potential to help to establish a global-scale quantum network, owing to the negligible photon loss and decoherence experienced in empty space. Here we report the development and launch of a low-Earth-orbit satellite for implementing decoy-state QKD-a form of QKD that uses weak coherent pulses at high channel loss and is secure because photon-number-splitting eavesdropping can be detected. We achieve a kilohertz key rate from the satellite to the ground over a distance of up to 1,200 kilometres. This key rate is around 20 orders of magnitudes greater than that expected using an optical fibre of the same length. The establishment of a reliable and efficient space-to-ground link for quantum-state transmission paves the way to global-scale quantum networks.

How quantum entanglement in DNA synchronizes double-strand breakage by type II restriction endonucleases

PubMed Central

Kurian, P.; Dunston, G.; Lindesay, J.

2015-01-01

Macroscopic quantum effects in living systems have been studied widely in pursuit of fundamental explanations for biological energy transport and sensing. While it is known that type II endonucleases, the largest class of restriction enzymes, induce DNA double-strand breaks by attacking phosphodiester bonds, the mechanism by which simultaneous cutting is coordinated between the catalytic centers remains unclear. We propose a quantum mechanical model for collective electronic behavior in the DNA helix, where dipole-dipole oscillations are quantized through boundary conditions imposed by the enzyme. Zero-point modes of coherent oscillations would provide the energy required for double-strand breakage. Such quanta may be preserved in the presence of thermal noise by the enzyme’s displacement of water surrounding the DNA recognition sequence. The enzyme thus serves as a decoherence shield. Palindromic mirror symmetry of the enzyme-DNA complex should conserve parity, because symmetric bond-breaking ceases when the symmetry of the complex is violated or when physiological parameters are perturbed from optima. Persistent correlations in DNA across longer spatial separations—a possible signature of quantum entanglement—may be explained by such a mechanism. PMID:26682627

Optical amplifiers for coherent lidar

NASA Technical Reports Server (NTRS)

Fork, Richard

1996-01-01

We examine application of optical amplification to coherent lidar for the case of a weak return signal (a number of quanta of the return optical field close to unity). We consider the option that has been explored to date, namely, incorporation of an optical amplifier operated in a linear manner located after reception of the signal and immediately prior to heterodyning and photodetection. We also consider alternative strategies where the coherent interaction, the nonlinear processes, and the amplification are not necessarily constrained to occur in the manner investigated to date. We include the complications that occur because of mechanisms that occur at the level of a few, or one, quantum excitation. Two factors combine in the work to date that limit the value of the approach. These are: (1) the weak signal tends to require operation of the amplifier in the linear regime where the important advantages of nonlinear optical processing are not accessed, (2) the linear optical amplifier has a -3dB noise figure (SN(out)/SN(in)) that necessarily degrades the signal. Some improvement is gained because the gain provided by the optical amplifier can be used to overcome losses in the heterodyned process and photodetection. The result, however, is that introduction of an optical amplifier in a well optimized coherent lidar system results in, at best, a modest improvement in signal to noise. Some improvement may also be realized on incorporating more optical components in a coherent lidar system for purely practical reasons. For example, more compact, lighter weight, components, more robust alignment, or more rapid processing may be gained. We further find that there remain a number of potentially valuable, but unexplored options offered both by the rapidly expanding base of optical technology and the recent investigation of novel nonlinear coherent interference phenomena occurring at the single quantum excitation level. Key findings are: (1) insertion of linear optical

Polycrystalline scintillators for large area detectors in HEP experiments

NASA Astrophysics Data System (ADS)

Dosovitskiy, G.; Fedorov, A.; Karpyuk, P.; Kuznetsova, D.; Mikhlin, A.; Kozlov, D.; Dosovitskiy, A.; Korjik, M.

2017-06-01

After significant increase of the accelerator luminosity throughout the High Luminosity phase of LHC, charged hadrons and neutrons with fluences higher than 1014 p/cm2 per year in the largest pseudo-rapidity regions of the detectors will cause increased radiation damage of materials. Increasing activation of the experimental equipment will make periodical maintenance and replacement of detector components difficult. Therefore, the selected materials for new detectors should be tolerant to radiation damage. Y3Al5O12:Ce (YAG:Ce) crystal was found to be one of the most radiation hard scintillation materials. However, production of YAG:Ce in a single crystalline form is costly, because crystal growth is performed at temperature near 1900°C with a very low rate of transformation of a raw material into a crystal. We propose translucent YAG:Ce ceramics as an alternative cheaper solution. Ceramic samples were sintered up to density ~98% of the theoretical value and were translucent. The samples have demonstrated light yield of 2200 phot./MeV under 662 keV γ-quanta, which gives the expected response to minimum ionizing particle around 3000 phot. for 2 mm thick plate. Scintillation light yield, registered under surface layer excitation with α-particles, was 50-70% higher than for the reference single crystal YAG:Ce.

Black hole evaporation, quantum hair and supertranslations

NASA Astrophysics Data System (ADS)

Gómez, César; Zell, Sebastian

2018-04-01

In a black hole, hair and quantum information retrieval are interrelated phenomena. The existence of any new form of hair necessarily implies the existence of features in the quantum-mechanically evaporated radiation. Therefore, classical supertranslation hair can be only distinguished from global diffeomorphisms if we have access to the interior of the black hole. Indirect information on the interior can only be obtained from the features of the quantum evaporation. We demonstrate that supertranslations (T^-,T^+) \\in BMS-⊗ BMS+ can be used as bookkeepers of the probability distributions of the emitted quanta where the first element describes the classical injection of energy and the second one is associated to quantum-mechanical emission. However, the connection between T^- and T^+ is determined by the interior quantum dynamics of the black hole. We argue that restricting to the diagonal subgroup is only possible for decoupled modes, which do not bring any non-trivial information about the black hole interior and therefore do not constitute physical hair. It is shown that this is also true for gravitational systems without horizon, for which both injection and emission can be described classically. Moreover, we discuss and clarify the role of infrared physics in purification.

Physical and Constructive (Limiting) Criterions of Gear Wheels Wear

NASA Astrophysics Data System (ADS)

Fedorov, S. V.

2018-01-01

We suggest using a generalized model of friction - the model of elastic-plastic deformation of the body element, which is located on the surface of the friction pairs. This model is based on our new engineering approach to the problem of friction-triboergodynamics. Friction is examined as transformative and dissipative process. Structural-energetic interpretation of friction as a process of elasto-plastic deformation and fracture contact volumes is proposed. The model of Hertzian (heavy-loaded) friction contact evolution is considered. The least wear particle principle is formulated. It is mechanical (nano) quantum. Mechanical quantum represents the least structural form of solid material body in conditions of friction. It is dynamic oscillator of dissipative friction structure and it can be examined as the elementary nanostructure of metal’s solid body. At friction in state of most complete evolution of elementary tribosystem (tribocontact) all mechanical quanta (subtribosystems) with the exception of one, elasticity and reversibly transform energy of outer impact (mechanic movement). In these terms only one mechanical quantum is the lost - standard of wear. From this position we can consider the physical criterion of wear and the constructive (limiting) criterion of gear teeth and other practical examples of tribosystems efficiency with new tribology notion - mechanical (nano) quantum.

Unveiling the High Energy Obscured Universe: Hunting Collapsed Objects Physics

NASA Technical Reports Server (NTRS)

Ubertini, P.; Bazzano, A.; Cocchi, M.; Natalucci, L.; Bassani, L.; Caroli, E.; Stephen, J. B.; Caraveo, P.; Mereghetti, S.; Villa, G.

2005-01-01

A large part of energy from space is coming from collapsing stars (SN, Hypernovae) and collapsed stars (black holes, neutron stars and white dwarfs). The peak of their energy release is in the hard-X and gamma-ray wavelengths where photons are insensitive to absorption and can travel from the edge the Universe or the central core of the Galaxy without loosing the primordial information of energy, time signature and polarization. The most efficient process to produce energetic photons is gravitational accretion of matter from a "normal" star onto a collapsed companion (LGxMcollxdMacc/dtx( 1Rdisc)-dMacc/dt x c2), exceeding by far the nuclear reaction capability to generate high energy quanta. Thus our natural laboratory for "in situ" investigations are collapsed objects in which matter and radiation co-exist in extreme conditions of temperature and density due to gravitationally bent geometry and magnetic fields. This is a unique opportunity to study the physics of accretion flows in stellar mass and super-massive Black Holes (SMBHs), plasmoids generated in relativistic jets in galactic microQSOs and AGNs, ionised plasma interacting at the touching point of weakly magnetized NS surface, GRB/Supernovae connection, and the mysterious origins of "dark" GRB and X-ray flash.

Imaging characteristics of different mammographic screens.

PubMed

Kuhn, H; Knüpfer, W

1992-01-01

A study of mammography systems with green-emitting screens was conducted to determine how the image quality parameters (apart from dose requirement), such as modulation transfer function (MTF) and Wiener spectrum (WS), depend on the dye content of the compound and coating weight of the screen. In addition, the contribution to total noise of the individual components, i.e., film, screen, and quantum noise, was studied. The quantities derived from MTF and WS, namely detective quantum efficiency (DQE) and noise equivalent quanta (NEQ), were also investigated in regard to their dose dependency. It can be demonstrated that the MTF of the screens becomes more favorable when the dye content is increased, while noise is not significantly affected. This suggests the use of a mammography screen capable of greater detail recognition, requiring at least double the dose of today's conventional systems with approximately 80 microGy system dose. On the other hand, the manufacture of a screen with about 60% of the dose of the conventional system is possible with very little loss in image quality. For the systems in common use today (80 microGy), quantum noise represents a considerable share of the total noise at low spatial frequencies, whereas in high spatial frequencies, the graininess of the film dominates quantum noise and screen structure.

[Sex difference of functional and structural alterations in the myocardium of rats with hypothyroidism].

PubMed

Khara, M R; Pavlovych, S I; Mykhaĭliuk, V M

2013-01-01

In experiments on sexually mature rats we studied specific cholinergic regulations of the heart and the degree of its structural damage in hypothyroidism, depending on gender and hormone-productive activity of the gonads. Hypothyroidism in sexually mature males and females was modelled with mercazolil intragastric administration (75 mg/kg) daily during 15 days. We also studied the intensity of bradycardia, which occurred in response to electrical stimulation of vagus nerve and intravenous acetylcholine administration. The degree of structural heart damage was assessed by the percentage of damaged cardiomyocytes in the ventricles of myocardium. It was found that one of the mechanisms of bradycardia in merkazolil-induced hypothyroidism is an increase of the sensitivity of sinus node cholinergic receptors and release of more quanta of acetylcholine from stimulated nerves vagus endings, what was more intense in females. The intensity of bradycardia in hypothyroidism was more significant in gonadectomized animals than in individuals with preserved gonads. The mechanisms of its occurrence in males consist of release of greater amount of acetylcholine from the endings of the nerves vagus, and in females it was the result of significant increase of the sensitivity of sinus node cholinergic receptors. Regardless of the gonads activity, structural damage of the myocardium in merkazolil-induced hypothyroidism was more intensive in female rats.

System Engineering for J-2X Development: The Simpler, the Better

NASA Technical Reports Server (NTRS)

Kelly, William M.; Greasley, Paul; Greene, William D.; Ackerman, Peter

2008-01-01

The Ares I and Ares V Vehicles will utilize the J-2X rocket engine developed for NASA by the Pratt and Whitney Rocketdyne Company (PWR) as the upper stage engine (USE). The J-2X is an improved higher power version of the original J-2 engine used for Apollo. System Engineering (SE) facilitates direct and open discussions of issues and problems. This simple idea is often overlooked in large, complex engineering development programs. Definition and distribution of requirements from the engine level to the component level is controlled by Allocation Reports which breaks down numerical design objectives (weight, reliability, etc.) into quanta goals for each component area. Linked databases of design and verification requirements help eliminate redundancy and potential mistakes inherent in separated systems. Another tool, the Architecture Design Description (ADD), is used to control J-2X system architecture and effectively communicate configuration changes to those involved in the design process. But the proof of an effective process is in successful program accomplishment. SE is the methodology being used to meet the challenge of completing J-2X engine certification 2 years ahead of any engine program ever developed at PWR. This paper describes the simple, better SE tools and techniques used to achieve this success.

Effect of solvents on the fluorescence spectra of bacterial luciferase

NASA Astrophysics Data System (ADS)

Sukovataya, Irina E.; Tyulkova, Natalya A.; Kaykova, Elisaveta V.

2006-08-01

Bacteria luciferases catalyze the oxidation reaction of the long-chain aliphatic aldehyde and reduced flavinmononucleotide involving molecular oxygen to a respective fatty acid emitting light quanta in the visible spectrum. Fluorescence emission of luciferases from Photobacterium leiognathi dissolved in organic solvent-water mixtures was investigated. Methanol, acetone, dimethyl sulfoxide and formamide were used as organic solvents. As the methanol and acetone concentration is increased the emission maximum peak is decrease. In contrast, with dimethyl sulfoxide and formamide addition induced a increasing of the emission maximum intensity. The values of wavelength maximum (λ max) at the addition of this solvent can shows the spectra shifted to the red by about 12 nm. These increasing in the fluorescence intensity and in the λ max may be due to luciferase denaturation, resulting from the more intensive contact of chromospheres of luciferase with the solvent. At all used concentrations of methanol, acetone and formamide the shape of the fluorescence spectra was not changed. These studies demonstrate that the luciferase tryptophan fluorescence is sensitive to changes of physical-chemical property of enzyme environment. A comparison of activation/inactivation and fluorescence spectra of luciferase in methanol or acetone solutions shows that the extent of inactivation is larger than the extent of fluorescence changes at the same methanol or acetone concentration.

Variance analysis of x-ray CT sinograms in the presence of electronic noise background.

PubMed

Ma, Jianhua; Liang, Zhengrong; Fan, Yi; Liu, Yan; Huang, Jing; Chen, Wufan; Lu, Hongbing

2012-07-01

Low-dose x-ray computed tomography (CT) is clinically desired. Accurate noise modeling is a fundamental issue for low-dose CT image reconstruction via statistics-based sinogram restoration or statistical iterative image reconstruction. In this paper, the authors analyzed the statistical moments of low-dose CT data in the presence of electronic noise background. The authors first studied the statistical moment properties of detected signals in CT transmission domain, where the noise of detected signals is considered as quanta fluctuation upon electronic noise background. Then the authors derived, via the Taylor expansion, a new formula for the mean-variance relationship of the detected signals in CT sinogram domain, wherein the image formation becomes a linear operation between the sinogram data and the unknown image, rather than a nonlinear operation in the CT transmission domain. To get insight into the derived new formula by experiments, an anthropomorphic torso phantom was scanned repeatedly by a commercial CT scanner at five different mAs levels from 100 down to 17. The results demonstrated that the electronic noise background is significant when low-mAs (or low-dose) scan is performed. The influence of the electronic noise background should be considered in low-dose CT imaging.

Variance analysis of x-ray CT sinograms in the presence of electronic noise background

PubMed Central

Ma, Jianhua; Liang, Zhengrong; Fan, Yi; Liu, Yan; Huang, Jing; Chen, Wufan; Lu, Hongbing

2012-01-01

Purpose: Low-dose x-ray computed tomography (CT) is clinically desired. Accurate noise modeling is a fundamental issue for low-dose CT image reconstruction via statistics-based sinogram restoration or statistical iterative image reconstruction. In this paper, the authors analyzed the statistical moments of low-dose CT data in the presence of electronic noise background. Methods: The authors first studied the statistical moment properties of detected signals in CT transmission domain, where the noise of detected signals is considered as quanta fluctuation upon electronic noise background. Then the authors derived, via the Taylor expansion, a new formula for the mean–variance relationship of the detected signals in CT sinogram domain, wherein the image formation becomes a linear operation between the sinogram data and the unknown image, rather than a nonlinear operation in the CT transmission domain. To get insight into the derived new formula by experiments, an anthropomorphic torso phantom was scanned repeatedly by a commercial CT scanner at five different mAs levels from 100 down to 17. Results: The results demonstrated that the electronic noise background is significant when low-mAs (or low-dose) scan is performed. Conclusions: The influence of the electronic noise background should be considered in low-dose CT imaging. PMID:22830738

The East, the West and the universal machine.

PubMed

Marchal, Bruno

2017-12-01

After reviewing the basic of theology of Universal Numbers/Machines, as detailed in Marchal (2007), I illustrate how that body of thought might be used to shed some light upon the apparent dichotomy in Eastern/Western spirituality. This paper relies entirely on my previous interdisciplinary work in mathematical logic, computer science and machine's theology, where "theology" is used here in the sense of Plato: it is the truth, or the "truth-theory" (in the sense of logicians) about a machine that the machine can either deduce from some of its primitive beliefs, or can be intuited in some sense that eventually is made clear through the modal logic of machine self-reference. Such a theology appears to be testable, because it has been shown that physics has to be necessarily retrieved from it when we assume the mechanist hypothesis in the cognitive sciences, and this in a unique precise (introspective) way, so that we only need to compare the physics of the introspective machine with the physics inferred from the human observation; and up to now, it is the only theory known to fit both the existence of personal "consciousness" (undoubtable yet unjustifiable truth) and quanta and quantum relationships (Marchal, 1998; Marchal, 2004; Marchal, 2013; Marchal, 2015). Copyright © 2017 Elsevier Ltd. All rights reserved.

Efficiency of synaptic transmission of single-photon events from rod photoreceptor to rod bipolar dendrite.

PubMed

Schein, Stan; Ahmad, Kareem M

2006-11-01

A rod transmits absorption of a single photon by what appears to be a small reduction in the small number of quanta of neurotransmitter (Q(count)) that it releases within the integration period ( approximately 0.1 s) of a rod bipolar dendrite. Due to the quantal and stochastic nature of release, discrete distributions of Q(count) for darkness versus one isomerization of rhodopsin (R*) overlap. We suggested that release must be regular to narrow these distributions, reduce overlap, reduce the rate of false positives, and increase transmission efficiency (the fraction of R* events that are identified as light). Unsurprisingly, higher quantal release rates (Q(rates)) yield higher efficiencies. Focusing here on the effect of small changes in Q(rate), we find that a slightly higher Q(rate) yields greatly reduced efficiency, due to a necessarily fixed quantal-count threshold. To stabilize efficiency in the face of drift in Q(rate), the dendrite needs to regulate the biochemical realization of its quantal-count threshold with respect to its Q(count). These considerations reveal the mathematical role of calcium-based negative feedback and suggest a helpful role for spontaneous R*. In addition, to stabilize efficiency in the face of drift in degree of regularity, efficiency should be approximately 50%, similar to measurements.

Arbuscular mycorrhizal fungal spores host bacteria that affect nutrient biodynamics and biocontrol of soil-borne plant pathogens

PubMed Central

Cruz, Andre Freire; Ishii, Takaaki

2012-01-01

Summary The aim of this research was to isolate and characterize bacteria from spores of arbuscular mycorrhizal fungi (AMF). We designated these bacteria ‘probable endobacteria’ (PE). Three bacterial strains were isolated from approximately 500 spores of Gigaspora margarita (Becker and Hall) using a hypodermic needle (diameter, 200 μm). The bacteria were identified by morphological methods and on the basis of ribosomal gene sequences as Bacillus sp. (KTCIGM01), Bacillus thuringiensis (KTCIGM02), and Paenibacillus rhizospherae (KTCIGM03). We evaluated the effect of these probable endobacteria on antagonistic activity to the soil-borne plant pathogens (SBPPs) Fusarium oxysporum f. sp. lactucae MAFF 744088, Rosellinia necatrix, Rhizoctonia solani MAFF 237426, and Pythium ultimum NBRC 100123. We also tested whether these probable endobacteria affected phosphorus solubilization, ethylene production, nitrogenase activity (NA), and stimulation of AMF hyphal growth. In addition, fresh samples of spores and hyphae were photographed using an in situ scanning electron microscope (SEM) (Quanta 250FEG; FEI Co., Japan). Bacterial aggregates (BAs), structures similar to biofilms, could be detected on the surface of hyphae and spores. We demonstrate that using extraction with an ultrathin needle, it is possible to isolate AMF-associated bacterial species that are likely derived from inside the fungal spores. PMID:23213368

[THE CHARACTERISTICS OF MORPHOLOGY OF BIOFILM OF PERIODONTIUM UNDER INFLAMMATORY DISEASES OF GUMS (CHRONIC CATARRHAL GINGIVITIS, CHRONIC PERIODONTITIS, CANDIDA-ASSOCIATED PERIODONTITIS) ACCORDING RESULTS OF ELECTRONIC MICROSCOPY].

PubMed

Ippolitov, E V; Didenko, L V; Tzarev, V N

2015-12-01

The study was carried out to analyze morphology of biofilm of periodontium and to develop electronic microscopic criteria of differentiated diagnostic of inflammatory diseases of gums. The scanning electronic microscopy was applied to analyze samples of bioflm of periodont from 70 patients. Including ten patients with every nosologic form of groups with chronic catarrhal periodontitis. of light, mean and severe degree, chronic catarrhal gingivitis, Candida-associated paroperiodontitis and 20 healthy persons with intact periodontium. The analysis was implemented using dual-beam scanning electronic microscope Quanta 200 3D (FEI company, USA) and walk-through electronic micJEM 100B (JEOL, Japan). To detect marker DNA of periodont pathogenic bacteria in analyzed samples the kit of reagentsfor polymerase chain reaction "MultiDent-5" ("GenLab", Russia). The scanning electronic microscopy in combination with transmission electronic microscopy and polymerase chain reaction permits analyzing structure, composition and degree of development of biofilm of periodontium and to apply differentiated diagnostic of different nosologic forms of inflammatory diseases of periodontium, including light form of chronic periodontitis and gingivitis. The electronic microscopical indications of diseases ofperiodontium of inflammatory character are established: catarrhal gingivitis, (coccal morphological alternate), chronic periodontitis (bacillary morphological alternate), Candida-associated periodontitis (Candida morphological alternate of biofilm ofperiodontium).

Gravitationally Induced Entanglement between Two Massive Particles is Sufficient Evidence of Quantum Effects in Gravity

NASA Astrophysics Data System (ADS)

Marletto, C.; Vedral, V.

2017-12-01

All existing quantum-gravity proposals are extremely hard to test in practice. Quantum effects in the gravitational field are exceptionally small, unlike those in the electromagnetic field. The fundamental reason is that the gravitational coupling constant is about 43 orders of magnitude smaller than the fine structure constant, which governs light-matter interactions. For example, detecting gravitons—the hypothetical quanta of the gravitational field predicted by certain quantum-gravity proposals—is deemed to be practically impossible. Here we adopt a radically different, quantum-information-theoretic approach to testing quantum gravity. We propose witnessing quantumlike features in the gravitational field, by probing it with two masses each in a superposition of two locations. First, we prove that any system (e.g., a field) mediating entanglement between two quantum systems must be quantum. This argument is general and does not rely on any specific dynamics. Then, we propose an experiment to detect the entanglement generated between two masses via gravitational interaction. By our argument, the degree of entanglement between the masses is a witness of the field quantization. This experiment does not require any quantum control over gravity. It is also closer to realization than detecting gravitons or detecting quantum gravitational vacuum fluctuations.

Neutron flux measurements using scintillator-photodiode-preamplifier system and new types of scintillators

NASA Astrophysics Data System (ADS)

Ryzhikov, Vladimir D.; Burachas, S. F.; Volkov, V. G.; Danshin, Evgeniy A.; Lisetskaya, Elena K.; Piven, L. A.; Svishch, Vladimir M.; Chernikov, Vyacheslav V.; Filimonov, A. E.

1997-02-01

After the Chernobyl catastrophe among the problems of current concern a question arose of detection of 'hot' particles formed from plutonium alloys with carbon, nitrogen, silicon, etc. For this purpose, the instruments are needed, which would be able to detect not only alpha- particles and low energy gamma-radiation, but also neutrons and high energy gamma-quanta from ((alpha) , n(gamma) ) - reactions. At present for each kind of radiation detectors of different types are used. A general drawback of all these instruments is their narrow dynamic range of dose rates and energies, and especially impossibility to registrate n-flux in condition large background activity gamma-rays nuclei, which makes each of them applicable only under certain specific conditions. For detection of 'hot' particles, oxide and semiconductor scintillators were used, which contained elements with large capture cross section for thermal neutrons. In this paper we try to determine possibilities and limitations of solid-state neutron detectors based on CdS(Te), ZnSe(Te), CdWO4 (CWO), Gd2SiO5 (GSO) scintillators developed and produced by the Science and Technology Center for Radiation Instruments of the Institute for Single Crystals. The instruments developed by Center are based preferable on a very promising system 'scintillator- photodiode-preamplifier' matched with modern computer data processing techniques.

System responses to equal doses of photosynthetically usable radiation of blue, green, and red light in the marine diatom Phaeodactylum tricornutum.

PubMed

Valle, Kristin Collier; Nymark, Marianne; Aamot, Inga; Hancke, Kasper; Winge, Per; Andresen, Kjersti; Johnsen, Geir; Brembu, Tore; Bones, Atle M

2014-01-01

Due to the selective attenuation of solar light and the absorption properties of seawater and seawater constituents, free-floating photosynthetic organisms have to cope with rapid and unpredictable changes in both intensity and spectral quality. We have studied the transcriptional, metabolic and photo-physiological responses to light of different spectral quality in the marine diatom Phaeodactylum tricornutum through time-series studies of cultures exposed to equal doses of photosynthetically usable radiation of blue, green and red light. The experiments showed that short-term differences in gene expression and profiles are mainly light quality-dependent. Transcription of photosynthesis-associated nuclear genes was activated mainly through a light quality-independent mechanism likely to rely on chloroplast-to-nucleus signaling. In contrast, genes encoding proteins important for photoprotection and PSII repair were highly dependent on a blue light receptor-mediated signal. Changes in energy transfer efficiency by light-harvesting pigments were spectrally dependent; furthermore, a declining trend in photosynthetic efficiency was observed in red light. The combined results suggest that diatoms possess a light quality-dependent ability to activate photoprotection and efficient repair of photodamaged PSII. In spite of approximately equal numbers of PSII-absorbed quanta in blue, green and red light, the spectral quality of light is important for diatom responses to ambient light conditions.

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

Bagraev, N. T., E-mail: bagraev@mail.ioffe.ru; Grigoryev, V. Yu.; Klyachkin, L. E.

The negative-U impurity stripes confining the edge channels of semiconductor quantum wells are shown to allow the effective cooling inside in the process of the spin-dependent transport. The aforesaid also promotes the creation of composite bosons and fermions by the capture of single magnetic flux quanta at the edge channels under the conditions of low sheet density of carriers, thus opening new opportunities for the registration of quantum kinetic phenomena in weak magnetic fields at high temperatures up to the room temperature. As a certain version noted above, we present the first findings of the high temperature de Haas–van Alphenmore » (300 K) and quantum Hall (77 K) effects in the silicon sandwich structure that represents the ultranarrow, 2 nm, p-type quantum well (Si-QW) confined by the delta barriers heavily doped with boron on the n-type Si (100) surface. These data appear to result from the low density of single holes that are of small effective mass in the edge channels of p-type Si-QW because of the impurity confinement by the stripes consisting of the negative-U dipole boron centers which seems to give rise to the efficiency reduction of the electron–electron interaction.« less

Power Hardware-in-the-Loop-Based Anti-Islanding Evaluation and Demonstration

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

Schoder, Karl; Langston, James; Hauer, John

2015-10-01

The National Renewable Energy Laboratory (NREL) teamed with Southern California Edison (SCE), Clean Power Research (CPR), Quanta Technology (QT), and Electrical Distribution Design (EDD) to conduct a U.S. Department of Energy (DOE) and California Public Utility Commission (CPUC) California Solar Initiative (CSI)-funded research project investigating the impacts of integrating high-penetration levels of photovoltaics (PV) onto the California distribution grid. One topic researched in the context of high-penetration PV integration onto the distribution system is the ability of PV inverters to (1) detect islanding conditions (i.e., when the distribution system to which the PV inverter is connected becomes disconnected from themore » utility power connection) and (2) disconnect from the islanded system within the time specified in the performance specifications outlined in IEEE Standard 1547. This condition may cause damage to other connected equipment due to insufficient power quality (e.g., over-and under-voltages) and may also be a safety hazard to personnel that may be working on feeder sections to restore service. NREL teamed with the Florida State University (FSU) Center for Advanced Power Systems (CAPS) to investigate a new way of testing PV inverters for IEEE Standard 1547 unintentional islanding performance specifications using power hardware-in-loop (PHIL) laboratory testing techniques.« less

Controlling Photons, Qubits and their Interactions in Superconducting Electronic Circuits

NASA Astrophysics Data System (ADS)

Wallraff, Andreas

2009-03-01

A combination of ideas from atomic physics, quantum optics and solid state physics allows us to investigate the fundamental interaction of matter and light on the level of single quanta in electronic circuits. In an approach known as circuit quantum electrodynamics, we coherently couple individual photons stored in a high quality microwave frequency resonator to a fully controllable superconducting two-level system (qubit) realized in a macroscopic electronic circuit [1]. In particular, we have recently observed the simultaneous interaction of one, two and three photons with a single qubit. In these experiments, we have probed the quantum nonlinearity of the qubit/light interaction governed by the Jaynes-Cummings hamiltonian, clearly demonstrating the quantization of the radiation field in the on-chip cavity. We have also performed quantum optics experiments with no photons at all. In this situation, i.e. in pure vacuum, we have resolved the renormalization of the qubit transition frequency - known as the Lamb shift - due to its non-resonant interaction with the cavity vacuum fluctuations [3].[4pt] [1] A. Wallraff et al., Nature (London) 431, 162 (2004)[0pt] [2] J. Fink et al., Nature (London) 454, 315 (2008)[0pt] [3] A. Fragner et al., Science 322, 1357 (2008)

Analysis of Femtosecond Laser Assisted Capsulotomy Cutting Edges and Manual Capsulorhexis Using Environmental Scanning Electron Microscopy

PubMed Central

Serrao, Sebastiano; Lombardo, Giuseppe; Desiderio, Giovanni; Buratto, Lucio; Schiano-Lomoriello, Domenico; Pileri, Marco; Lombardo, Marco

2014-01-01

Purpose. To investigate the structure and irregularity of the capsulotomy cutting edges created by two femtosecond (FS) laser platforms in comparison with manual continuous circular capsulorhexis (CCC) using environmental scanning electron microscopy (eSEM). Methods. Ten anterior capsulotomies were obtained using two different FS laser cataract platforms (LenSx, n = 5, and Victus, n = 5). In addition, five manual CCC (n = 5) were obtained using a rhexis forceps. The specimens were imaged by eSEM (FEI Quanta 400, OR, USA). Objective metrics, which included the arithmetic mean deviation of the surface (Sa) and the root-mean-square deviation of the surface (Sq), were used to evaluate the irregularity of both the FS laser capsulotomies and the manual CCC cutting edges. Results. Several microirregularities were shown across the FS laser capsulotomy cutting edges. The edges of manually torn capsules were shown, by comparison of Sa and Sq values, to be smoother (P < 0.05) than the FS laser capsulotomy edges. Conclusions. Work is needed to understand whether the FS laser capsulotomy edge microirregularities, not seen in manual CCC, may act as focal points for the concentration of stress that would increase the risk of capsular tear during phacoemulsification as recently reported in the literature. PMID:25505977

Analysis of femtosecond laser assisted capsulotomy cutting edges and manual capsulorhexis using environmental scanning electron microscopy.

PubMed

Serrao, Sebastiano; Lombardo, Giuseppe; Desiderio, Giovanni; Buratto, Lucio; Schiano-Lomoriello, Domenico; Pileri, Marco; Lombardo, Marco

2014-01-01

Purpose. To investigate the structure and irregularity of the capsulotomy cutting edges created by two femtosecond (FS) laser platforms in comparison with manual continuous circular capsulorhexis (CCC) using environmental scanning electron microscopy (eSEM). Methods. Ten anterior capsulotomies were obtained using two different FS laser cataract platforms (LenSx, n = 5, and Victus, n = 5). In addition, five manual CCC (n = 5) were obtained using a rhexis forceps. The specimens were imaged by eSEM (FEI Quanta 400, OR, USA). Objective metrics, which included the arithmetic mean deviation of the surface (Sa) and the root-mean-square deviation of the surface (Sq), were used to evaluate the irregularity of both the FS laser capsulotomies and the manual CCC cutting edges. Results. Several microirregularities were shown across the FS laser capsulotomy cutting edges. The edges of manually torn capsules were shown, by comparison of Sa and Sq values, to be smoother (P < 0.05) than the FS laser capsulotomy edges. Conclusions. Work is needed to understand whether the FS laser capsulotomy edge microirregularities, not seen in manual CCC, may act as focal points for the concentration of stress that would increase the risk of capsular tear during phacoemulsification as recently reported in the literature.

Probing 1D superlattices at the LaAlO3 / SrTiO3 interface

NASA Astrophysics Data System (ADS)

Briggeman, M.; Huang, M.; Tylan-Tyler, A.; Irvin, P.; Levy, J.; Lee, J.-W.; Lee, H.; Eom, C.-B.

Complex oxides and other quantum systems exhibit behavior that is currently too complex to be understood using analytic or computational methods. One approach is to use a configurable quantum system whose Hamiltonian can be mapped onto the system of interest. This approach, known as quantum simulation, requires a rich physical system whose quanta and interactions can be controlled precisely, at the level of single electrons and other degrees of freedom. Here we describe steps toward developing a quantum simulation platform, using the complex oxide heterostructure LaAlO3 / SrTiO3 , by creating quantum systems with features comparable to the mean spacing between electrons. This interface has strong, sign changing, gate-tunable electron-electron interactions that can strongly influence the quantum ground state. We explore the magnetotransport properties of 1D superlattices, where periodic modulation produces reproducible dispersive features not seen in control structures. The results of these experiments can be compared with effective 1D model Hamiltonians to bridge experiment and theory and enable quantum simulation of more complex systems. We gratefully acknowledge financial support from AFOSR (FA9550-12-1- 0057 (JL) and FA9550-12-1-0342 (CBE)), ONR N00014-15-1-2847 (JL), and NSF DMR-1234096 (CBE).

Novel method for hit-position reconstruction using voltage signals in plastic scintillators and its application to Positron Emission Tomography

NASA Astrophysics Data System (ADS)

Raczyński, L.; Moskal, P.; Kowalski, P.; Wiślicki, W.; Bednarski, T.; Białas, P.; Czerwiński, E.; Kapłon, Ł.; Kochanowski, A.; Korcyl, G.; Kowal, J.; Kozik, T.; Krzemień, W.; Kubicz, E.; Molenda, M.; Moskal, I.; Niedźwiecki, Sz.; Pałka, M.; Pawlik-Niedźwiecka, M.; Rudy, Z.; Salabura, P.; Sharma, N. G.; Silarski, M.; Słomski, A.; Smyrski, J.; Strzelecki, A.; Wieczorek, A.; Zieliński, M.; Zoń, N.

2014-11-01

Currently inorganic scintillator detectors are used in all commercial Time of Flight Positron Emission Tomograph (TOF-PET) devices. The J-PET collaboration investigates a possibility of construction of a PET scanner from plastic scintillators which would allow for single bed imaging of the whole human body. This paper describes a novel method of hit-position reconstruction based on sampled signals and an example of an application of the method for a single module with a 30 cm long plastic strip, read out on both ends by Hamamatsu R4998 photomultipliers. The sampling scheme to generate a vector with samples of a PET event waveform with respect to four user-defined amplitudes is introduced. The experimental setup provides irradiation of a chosen position in the plastic scintillator strip with an annihilation gamma quanta of energy 511 keV. The statistical test for a multivariate normal (MVN) distribution of measured vectors at a given position is developed, and it is shown that signals sampled at four thresholds in a voltage domain are approximately normally distributed variables. With the presented method of a vector analysis made out of waveform samples acquired with four thresholds, we obtain a spatial resolution of about 1 cm and a timing resolution of about 80 ps (σ).

Gravitationally Induced Entanglement between Two Massive Particles is Sufficient Evidence of Quantum Effects in Gravity.

PubMed

Marletto, C; Vedral, V

2017-12-15

All existing quantum-gravity proposals are extremely hard to test in practice. Quantum effects in the gravitational field are exceptionally small, unlike those in the electromagnetic field. The fundamental reason is that the gravitational coupling constant is about 43 orders of magnitude smaller than the fine structure constant, which governs light-matter interactions. For example, detecting gravitons-the hypothetical quanta of the gravitational field predicted by certain quantum-gravity proposals-is deemed to be practically impossible. Here we adopt a radically different, quantum-information-theoretic approach to testing quantum gravity. We propose witnessing quantumlike features in the gravitational field, by probing it with two masses each in a superposition of two locations. First, we prove that any system (e.g., a field) mediating entanglement between two quantum systems must be quantum. This argument is general and does not rely on any specific dynamics. Then, we propose an experiment to detect the entanglement generated between two masses via gravitational interaction. By our argument, the degree of entanglement between the masses is a witness of the field quantization. This experiment does not require any quantum control over gravity. It is also closer to realization than detecting gravitons or detecting quantum gravitational vacuum fluctuations.

Black Hole on a Chip: Proposal for a Physical Realization of the Sachdev-Ye-Kitaev model in a Solid-State System

NASA Astrophysics Data System (ADS)

Pikulin, D. I.; Franz, M.

2017-07-01

A system of Majorana zero modes with random infinite-range interactions—the Sachdev-Ye-Kitaev (SYK) model—is thought to exhibit an intriguing relation to the horizons of extremal black holes in two-dimensional anti-de Sitter space. This connection provides a rare example of holographic duality between a solvable quantum-mechanical model and dilaton gravity. Here, we propose a physical realization of the SYK model in a solid-state system. The proposed setup employs the Fu-Kane superconductor realized at the interface between a three-dimensional topological insulator and an ordinary superconductor. The requisite N Majorana zero modes are bound to a nanoscale hole fabricated in the superconductor that is threaded by N quanta of magnetic flux. We show that when the system is tuned to the surface neutrality point (i.e., chemical potential coincident with the Dirac point of the topological insulator surface state) and the hole has sufficiently irregular shape, the Majorana zero modes are described by the SYK Hamiltonian. We perform extensive numerical simulations to demonstrate that the system indeed exhibits physical properties expected of the SYK model, including thermodynamic quantities and two-point as well as four-point correlators, and discuss ways in which these can be observed experimentally.

Microwave amplification with nanomechanical resonators.

PubMed

Massel, F; Heikkilä, T T; Pirkkalainen, J-M; Cho, S U; Saloniemi, H; Hakonen, P J; Sillanpää, M A

2011-12-14

The sensitive measurement of electrical signals is at the heart of modern technology. According to the principles of quantum mechanics, any detector or amplifier necessarily adds a certain amount of noise to the signal, equal to at least the noise added by quantum fluctuations. This quantum limit of added noise has nearly been reached in superconducting devices that take advantage of nonlinearities in Josephson junctions. Here we introduce the concept of the amplification of microwave signals using mechanical oscillation, which seems likely to enable quantum-limited operation. We drive a nanomechanical resonator with a radiation pressure force, and provide an experimental demonstration and an analytical description of how a signal input to a microwave cavity induces coherent stimulated emission and, consequently, signal amplification. This generic scheme, which is based on two linear oscillators, has the advantage of being conceptually and practically simpler than the Josephson junction devices. In our device, we achieve signal amplification of 25 decibels with the addition of 20 quanta of noise, which is consistent with the expected amount of added noise. The generality of the model allows for realization in other physical systems as well, and we anticipate that near-quantum-limited mechanical microwave amplification will soon be feasible in various applications involving integrated electrical circuits.

Retinex at 50: color theory and spatial algorithms, a review

NASA Astrophysics Data System (ADS)

McCann, John J.

2017-05-01

Retinex Imaging shares two distinct elements: first, a model of human color vision; second, a spatial-imaging algorithm for making better reproductions. Edwin Land's 1964 Retinex Color Theory began as a model of human color vision of real complex scenes. He designed many experiments, such as Color Mondrians, to understand why retinal cone quanta catch fails to predict color constancy. Land's Retinex model used three spatial channels (L, M, S) that calculated three independent sets of monochromatic lightnesses. Land and McCann's lightness model used spatial comparisons followed by spatial integration across the scene. The parameters of their model were derived from extensive observer data. This work was the beginning of the second Retinex element, namely, using models of spatial vision to guide image reproduction algorithms. Today, there are many different Retinex algorithms. This special section, "Retinex at 50," describes a wide variety of them, along with their different goals, and ground truths used to measure their success. This paper reviews (and provides links to) the original Retinex experiments and image-processing implementations. Observer matches (measuring appearances) have extended our understanding of how human spatial vision works. This paper describes a collection very challenging datasets, accumulated by Land and McCann, for testing algorithms that predict appearance.

On discrete symmetries for a whole Abelian model

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

Chauca, J.; Doria, R.; Aprendanet, Petropolis, 25600

Considering the whole concept applied to gauge theory a nonlinear abelian model is derived. A next step is to understand on the model properties. At this work, it will be devoted to discrete symmetries. For this, we will work based in two fields reference systems. This whole gauge symmetry allows to be analyzed through different sets which are the constructor basis {l_brace}D{sub {mu}},X{sup i}{sub {mu}}{r_brace} and the physical basis {l_brace}G{sub {mu}I}{r_brace}. Taking as fields reference system the diagonalized spin-1 sector, P, C, T and PCT symmetries are analyzed. They show that under this systemic model there are conservation laws drivenmore » for the parts and for the whole. It develops the meaning of whole-parity, field-parity and so on. However it is the whole symmetry that rules. This means that usually forbidden particles as pseudovector photons can be introduced through such whole abelian system. As result, one notices that the fields whole {l_brace}G{sub {mu}I}{r_brace} manifest a quanta diversity. It involves particles with different spins, masses and discrete quantum numbers under a same gauge symmetry. It says that without violating PCT symmetry different possibilities on discrete symmetries can be accommodated.« less

Measurement of the prompt fissionγ-ray spectrum of 242Pu

NASA Astrophysics Data System (ADS)

Urlass, Sebastian; Beyer, Roland; Junghans, Arnd Rudolf; Kögler, Toni; Schwengner, Ronald; Wagner, Andreas

2018-03-01

The prompt γ-ray spectrum of fission fragments is important in understanding the dynamics of the fission process, as well as for nuclear engineering in terms of predicting the γ-ray heating in nuclear reactors. The γ-ray spectrum measured from the fission fragments of the spontaneous fission of 242Pu will be presented here. A fission chamber containing in total 37mg of 242Pu was used as active sample. The γ-quanta were detected with high time- and energy-resolution using LaBr3 and HPGe detectors, respectively, in coincidence with spontaneous fission events detected by the fission chamber. The acquired γ-ray spectra were corrected for the detector response using the spectrum stripping method. About 70 million fission events were detected which results in a very low statistical uncertainty and a wider energy range covered compared to previous measurements. The prompt fission γ-ray spectrum measured with the HPGe detectors shows structures that allow conclusions about the nature of γ-ray transitions in the fission fragments. The average photon multiplicity of 8.2 and the average total energy release by prompt photons per fission event of about 6.8 MeV were determined for both detector types.

Detection of gamma-neutron radiation by solid-state scintillation detectors. Detection of gamma-neutron radiation by novel solid-state scintillation detectors

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

Ryzhikov, V.; Grinyov, B.; Piven, L.

It is known that solid-state scintillators can be used for detection of both gamma radiation and neutron flux. In the past, neutron detection efficiencies of such solid-state scintillators did not exceed 5-7%. At the same time it is known that the detection efficiency of the gamma-neutron radiation characteristic of nuclear fissionable materials is by an order of magnitude higher than the efficiency of detection of neutron fluxes alone. Thus, an important objective is the creation of detection systems that are both highly efficient in gamma-neutron detection and also capable of exhibiting high gamma suppression for use in the role ofmore » detection of neutron radiation. In this work, we present the results of our experimental and theoretical studies on the detection efficiency of fast neutrons from a {sup 239}Pu-Be source by the heavy oxide scintillators BGO, GSO, CWO and ZWO, as well as ZnSe(Te, O). The most probable mechanism of fast neutron interaction with nuclei of heavy oxide scintillators is the inelastic scattering (n, n'γ) reaction. In our work, fast neutron detection efficiencies were determined by the method of internal counting of gamma-quanta that emerge in the scintillator from (n, n''γ) reactions on scintillator nuclei with the resulting gamma energies of ∼20-300 keV. The measured efficiency of neutron detection for the scintillation crystals we considered was ∼40-50 %. The present work included a detailed analysis of detection efficiency as a function of detector and area of the working surface, as well as a search for new ways to create larger-sized detectors of lower cost. As a result of our studies, we have found an unusual dependence of fast neutron detection efficiency upon thickness of the oxide scintillators. An explanation for this anomaly may involve the competition of two factors that accompany inelastic scattering on the heavy atomic nuclei. The transformation of the energy spectrum of neutrons involved in the (n, n'γ) reactions

EDITORIAL: The nonstationary Casimir effect and quantum systems with moving boundaries

NASA Astrophysics Data System (ADS)

Barton, Gabriel; Dodonov, Victor V.; Man'ko, Vladimir I.

2005-03-01

This topical issue of Journal of Optics B: Quantum and Semiclassical Optics contains 16 contributions devoted to quantum systems with moving boundaries. In a broad sense, the papers continue the studies opened exactly 100 years ago by Einstein in his seminal work on the electrodynamics of moving bodies and the quantum nature of light. Another jubilee which we wish to celebrate by launching this issue is the 80th anniversary of the publication of two papers, where the first solutions of the classical Maxwell equations in a one-dimensional cavity with moving boundaries were obtained, by T H Havelock (1924 Some dynamical illustrations of the pressure of radiation and of adiabatic invariance Phil. Mag. 47 754-71) and by E L Nicolai (1925 On a dynamical illustration of the pressure of radiation Phil. Mag. 49 171-7). As was shown by Einstein, studying the fluctuations of the electromagnetic field inevitably leads one to its quantum (corpuscular) nature. Many papers in this issue deal with problems where moving boundaries produce parametric excitation of vacuum fluctuations of the field, which could result in several different observable effects, like the modification of the famous Casimir force, or the creation of real quanta from the vacuum. It is worth emphasizing that these phenomena, frequently referred to as nonstationary (or dynamical) Casimir effects, are no longer the province only of pure theorists: some experimental groups have already started long-term work aimed at observing such effects in the laboratory. Of course, many difficult problems remain to be resolved before this dream becomes reality. Several papers here show both important progress in this direction, and possible difficulties still to be tackled. Problems that have been considered include, in particular, decoherence, entanglement, and the roles of geometry and polarization. Other papers deal with fundamental problems like the Unruh effect, the interaction of accelerated relativistic atoms with

Non-resonant excitation of rare-earth ions via virtual Auger process

NASA Astrophysics Data System (ADS)

Yassievich, I. N.

2011-05-01

The luminescence of rare-earth ions (REI) is often intensified by defects associated with REIs or excitons bound to these defects. In this paper we show that the presence of such a state opens the possibility of non-resonance optical pumping via the process involving virtual Auger transition. It is the second order perturbation process when an electron arrives in an virtual intermediate state due to the optical transition (the first step) and the Auger transition is the second one. We have calculated the cross-section of such an excitation process when the optical transition is accompanied by creation of the exciton bound to the defect associated with REI and obtained a simple analytical expression for the cross-section. The excess energy of the excitation quanta is taken away by multiphonon emission. The electron-phonon interaction with local phonon vibrations of the bound exciton is assumed to determine the multiphonon process. It is shown that the probability of the process under study exceeds considerably the probability of direct optical 4f-4f absorption even in the case when the energy distance between the excitation quantum energy and the exciton energy is about 0.1 of the exciton energy. The excitation mechanism considered leads to the appearance of a broad unsymmetrical band in the excitation spectrum with the red side much wider and flatter than the blue one.

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

Lomdahl, P.S.; Kerr, W.C.

The original proposal by Professor A.S. Davydov of a soliton mechanism for localization and transport of energy along linear chain molecules provided the impetus for several research efforts which have explored the properties of these nonlinear entities in differing degrees of realism. The general conclusion from all of this work is that the nonlinear equations of motion which have been used to describe these systems have soliton-like solutions when they are solved in the deterministic limit. This limit corresponds to the absolute zero of temperature, because it ignores the influence of random thermal perturbations on the system. However, the questionsmore » of existence and importance of the Davydov soliton remain controversial when non-zero temperature effects are taken into account, because numerical simulations and theoretical calculations done by independent research groups have reached diametrically opposed conclusions. Our 1985 paper was the first to simulate thermal perturbations at biologically relevant temperature (300 K). Since publishing that paper, we have done simulations for collisions of phonon wave packets with Davydov solitons and have also taken into account the presence of multiple quanta of the high frequency oscillator field in the Davydov equations of motion. We present these results here. However, for the major question about the temperature effects on the Davydov soliton, our conclusions remain unchanged. 5 refs., 6 figs., 1 tab.« less

Particle physics meets cosmology - The search for decaying neutrinos

NASA Technical Reports Server (NTRS)

Henry, R. C.

1982-01-01

The fundamental physical implications of the possible detection of massive neutrinos are discussed, with an emphasis on the Grand Unified Theories (GUTs) of matter. The Newtonian and general-relativistic pictures of the fundamental forces are compared, and the reduction of electromagnetic and weak forces to one force in the GUTs is explained. The cosmological consequences of the curved-spacetime gravitation concept are considered. Quarks, leptons, and neutrinos are characterized in a general treatment of elementary quantum mechanics. The universe is described in terms of quantized fields, the noninteractive 'particle' fields and the force fields, and cosmology becomes the study of the interaction of gravitation with the other fields, of the 'freezing out' of successive fields with the expansion and cooling of the universe. While the visible universe is the result of the clustering of the quark and electron fields, the distribution of the large number of quanta in neutrino field, like the mass of the neutrino, are unknown. Cosmological models which attribute anomalies in the observed motions of galaxies and stars to clusters or shells of massive neutrinos are shown to be consistent with a small but nonzero neutrino mass and a universe near the open/closed transition point, but direct detection of the presence of massive neutrinos by the UV emission of their decay is required to verify these hypotheses.

Berry phase and anomalous transport of the composite fermions at the half-filled Landau level

NASA Astrophysics Data System (ADS)

Pan, W.; Kang, W.; Baldwin, K. W.; West, K. W.; Pfeiffer, L. N.; Tsui, D. C.

2017-12-01

The fractional quantum Hall effect (FQHE) in two-dimensional electron systems is an exotic, superfluid-like matter with an emergent topological order. From the consideration of the Aharonov-Bohm interaction between electrons and magnetic field, the ground state of a half-filled lowest Landau level is mathematically transformed to a Fermi sea of composite objects of electrons bound to two flux quanta, termed composite fermions (CFs). A strong support for the CF theories comes from experimental confirmation of the predicted Fermi surface at ν = 1/2 (where ν is the Landau level filling factor) from the detection of the Fermi wavevector in semi-classical geometrical resonance experiments. Recent developments in the theory of CFs have led to the prediction of a π Berry phase for the CF circling around the Fermi surface at half-filling. In this paper we provide experimental evidence for the detection of the Berry phase of CFs in the fractional quantum Hall effect. Our measurements of the Shubnikov-de Haas oscillations of CFs as a function carrier density at a fixed magnetic field provide strong support for the existence of a π Berry phase at ν = 1/2. We also discover that the conductivity of composite fermions at ν = 1/2 displays an anomalous linear density dependence, whose origin remains mysterious yet tantalizing.

Quantum-limited detection of millimeter waves using superconducting tunnel junctions

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

Mears, Carl Atherton

1991-09-01

The quasiparticle tunneling current in a superconductor-insulator- superconductor (SIS) tunnel junction is highly nonlinear. Such a nonlinearity can be used to mix two millimeter wave signals to produce a signal at a much lower intermediate frequency. We have constructed several millimeter and sub-millimeter wave SIS mixers in order to study high frequency response of the quasiparticle tunneling current and the physics of high frequency mixing. We have made the first measurement of the out-of-phase tunneling currents in an SIS tunnel junction. We have developed a method that allows us to determine the parameters of the high frequency embedding circuit bymore » studying the details of the pumped I-V curve. We have constructed a 80--110 GHz waveguide-based mixer test apparatus that allows us to accurately measure the gain and added noise of the SIS mixer under test. Using extremely high quality tunnel junctions, we have measured an added mixer noise of 0.61 ± 0.36 quanta, which is within 25 percent of the quantum limit imposed by the Heisenberg uncertainty principle. This measured performance is in excellent agreement with that predicted by Tucker`s theory of quantum mixing. We have also studied quasioptically coupled millimeter- and submillimeter-wave mixers using several types of integrated tuning elements. 83 refs.« less

Quantum-limited detection of millimeter waves using superconducting tunnel junctions

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

Mears, C.A.

1991-09-01

The quasiparticle tunneling current in a superconductor-insulator- superconductor (SIS) tunnel junction is highly nonlinear. Such a nonlinearity can be used to mix two millimeter wave signals to produce a signal at a much lower intermediate frequency. We have constructed several millimeter and sub-millimeter wave SIS mixers in order to study high frequency response of the quasiparticle tunneling current and the physics of high frequency mixing. We have made the first measurement of the out-of-phase tunneling currents in an SIS tunnel junction. We have developed a method that allows us to determine the parameters of the high frequency embedding circuit bymore » studying the details of the pumped I-V curve. We have constructed a 80--110 GHz waveguide-based mixer test apparatus that allows us to accurately measure the gain and added noise of the SIS mixer under test. Using extremely high quality tunnel junctions, we have measured an added mixer noise of 0.61 {plus minus} 0.36 quanta, which is within 25 percent of the quantum limit imposed by the Heisenberg uncertainty principle. This measured performance is in excellent agreement with that predicted by Tucker's theory of quantum mixing. We have also studied quasioptically coupled millimeter- and submillimeter-wave mixers using several types of integrated tuning elements. 83 refs.« less

The chloroplast NADPH thioredoxin reductase C, NTRC, controls non-photochemical quenching of light energy and photosynthetic electron transport in Arabidopsis.

PubMed

Naranjo, Belén; Mignée, Clara; Krieger-Liszkay, Anja; Hornero-Méndez, Dámaso; Gallardo-Guerrero, Lourdes; Cejudo, Francisco Javier; Lindahl, Marika

2016-04-01

High irradiances may lead to photooxidative stress in plants, and non-photochemical quenching (NPQ) contributes to protection against excess excitation. One of the NPQ mechanisms, qE, involves thermal dissipation of the light energy captured. Importantly, plants need to tune down qE under light-limiting conditions for efficient utilization of the available quanta. Considering the possible redox control of responses to excess light implying enzymes, such as thioredoxins, we have studied the role of the NADPH thioredoxin reductase C (NTRC). Whereas Arabidopsis thaliana plants lacking NTRC tolerate high light intensities, these plants display drastically elevated qE, have larger trans-thylakoid ΔpH and have 10-fold higher zeaxanthin levels under low and medium light intensities, leading to extremely low linear electron transport rates. To test the impact of the high qE on plant growth, we generated an ntrc-psbs double-knockout mutant, which is devoid of qE. This double mutant grows faster than the ntrc mutant and has a higher chlorophyll content. The photosystem II activity is partially restored in the ntrc-psbs mutant, and linear electron transport rates under low and medium light intensities are twice as high as compared with plants lacking ntrc alone. These data uncover a new role for NTRC in the control of photosynthetic yield. © 2015 John Wiley & Sons Ltd.

Energy flow along the medium-induced parton cascade

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

Blaizot, J.-P., E-mail: jean-paul.blaizot@cea.fr; Mehtar-Tani, Y., E-mail: ymehtar@uw.edu

2016-05-15

We discuss the dynamics of parton cascades that develop in dense QCD matter, and contrast their properties with those of similar cascades of gluon radiation in vacuum. We argue that such cascades belong to two distinct classes that are characterized respectively by an increasing or a constant (or decreasing) branching rate along the cascade. In the former class, of which the BDMPS, medium-induced, cascade constitutes a typical example, it takes a finite time to transport a finite amount of energy to very soft quanta, while this time is essentially infinite in the latter case, to which the DGLAP cascade belongs.more » The medium induced cascade is accompanied by a constant flow of energy towards arbitrary soft modes, leading eventually to the accumulation of the initial energy of the leading particle at zero energy. It also exhibits scaling properties akin to wave turbulence. These properties do not show up in the cascade that develops in vacuum. There, the energy accumulates in the spectrum at smaller and smaller energy as the cascade develops, but the energy never flows all the way down to zero energy. Our analysis suggests that the way the energy is shared among the offsprings of a splitting gluon has little impact on the qualitative properties of the cascades, provided the kernel that governs the splittings is not too singular.« less

Arrangement Analysis of Leaves Optimized on Photon Flux Density or Photosynthetic Rate

NASA Astrophysics Data System (ADS)

Obara, Shin'ya; Tanno, Itaru

By clarifying a plant evolutive process, useful information may be obtained on engineering. Consequently, an analysis algorithm that investigates the optimal arrangement of plant leaves was developed. In the developed algorithm, the Monte Carlo method is introduced and sunlight is simulated. Moreover, the arrangement optimization of leaves is analyzed using a Genetic Algorithm (GA). The number of light quanta (photon flux density) that reaches leaves, or the average photosynthetic rate of the same was set as the objective function, and leaf models of a dogwood and a ginkgo tree were analyzed. The number of leaf models was set between two to four, and the position of the leaf was expressed in terms of the angle of direction, elevation angle, rotation angle, and the representative length of the branch of a leaf. The chromosome model introduced into GA consists of information concerning the position of the leaf. Based on the analysis results, the characteristics of the leaf of an actual plant could be simulated by ensuring the algorithm had multiple constrained conditions. The optimal arrangement of leaves differs in maximization of the photon flux density, and that of the average value of a photosynthetic rate. Furthermore, the leaf form affecting the optimal arrangement of leave and also having a significant influence also on a photosynthetic rate was shown.

Effects of group velocity and multiplasmon resonances on the modulation of Langmuir waves in a degenerate plasma

NASA Astrophysics Data System (ADS)

Misra, Amar P.; Chatterjee, Debjani; Brodin, Gert

2017-11-01

We study the nonlinear wave modulation of Langmuir waves (LWs) in a fully degenerate plasma. Using the Wigner-Moyal equation coupled to the Poisson equation and the multiple scale expansion technique, a modified nonlocal nonlinear Schrödinger (NLS) equation is derived which governs the evolution of LW envelopes in degenerate plasmas. The nonlocal nonlinearity in the NLS equation appears due to the group velocity and multiplasmon resonances, i.e., resonances induced by the simultaneous particle absorption of multiple wave quanta. We focus on the regime where the resonant velocity of electrons is larger than the Fermi velocity and thereby the linear Landau damping is forbidden. As a result, the nonlinear wave-particle resonances due to the group velocity and multiplasmon processes are the dominant mechanisms for wave-particle interaction. It is found that in contrast to classical or semiclassical plasmas, the group velocity resonance does not necessarily give rise the wave damping in the strong quantum regime where ℏ k ˜m vF with ℏ denoting the reduced Planck's constant, m the electron mass, and vF the Fermi velocity; however, the three-plasmon process plays a dominant role in the nonlinear Landau damping of wave envelopes. In this regime, the decay rate of the wave amplitude is also found to be higher compared to that in the modest quantum regime where the multiplasmon effects are forbidden.

The Schiff angular bremsstrahlung distribution from composite media

NASA Astrophysics Data System (ADS)

Taylor, M. L.; Dalton, B.; Franich, R. D.

2012-12-01

The Schiff differential for the angular distribution of bremsstrahlung is widely employed, but calculations involving composite materials (i.e. compounds and mixtures) are often undertaken in a somewhat ad hoc fashion. In this work, we suggest an alternative approach to power-law estimates of the effective atomic number utilising Seltzer and Berger's combined approach in order to generate single-valued effective atomic numbers applicable over a large energy range (in the worst case deviation from constancy of about 2% between 10 keV and 1 GeV). Differences with power-law estimates of Z for composites are potentially significant, particularly for low-Z media such as biological or surrogate materials as relevant within the context of medical physics. As an example, soft tissue differs by >70% and cortical bone differs by >85%, while for high-Z composites such as a tungsten-rhenium alloy the difference is of the order of 1%. Use of the normalised Schiff formula for shape only does not exhibit strong Z dependence. Consequently, in such contexts the differences are negligible - the power-law approach overestimates the magnitude by 1.05% in the case of water and underestimates it by <0.1% for the high-Z alloys. The differences in the distribution are most pronounced for small angles and where the bremsstrahlung quanta are low energy.

Separability and Non-Individuality: Is It Possible to Conciliate (At Least A Form Of) Einstein's Realism with Quantum Mechanics?

NASA Astrophysics Data System (ADS)

Krause, Décio; Arenhart, Jonas R. B.

2014-12-01

In this paper we argue that physical theories, including quantum mechanics, refer to some kind of `objects', even if only implicitly. We raise questions about the logico-mathematical apparatuses commonly employed in such theories, bringing to light some metaphysical presuppositions underlying such apparatuses. We point out to some incongruities in the discourse holding that quantum objects would be entities of some `new kind' while still adhering to the logico-mathematical framework we use to deal with classical objects. The use of such apparatus would hinder us from being in complete agreement with the ontological novelties the theories of quanta seem to advance. Thus, we join those who try to investigate a `logic of quantum mechanics', but from a different point of view: looking for a formal foundation for a supposed new ontology. As a consequence of this move, we can revisit Einstein's ideas on physical reality and propose that, by considering a new kind of object traditionally termed `non-individuals', it is possible to sustain that they still obey some of Einstein's conditions for `physical realities', so that it will be possible to talk of a `principle of separability' in a sense which is not in complete disagreement with quantum mechanics. So, Einstein's departure from quantum mechanics might be softened at least concerning a form of his realism, which sees separated physical objects as distinct `physical realities'.

FRAMING Linguistics: ``SEANCES"(!!!) Martin-Bradshaw-Siegel ``Buzzwordism, Bandwagonism, Sloganeering For:Fun, Profit, Survival, Ego": Rampant UNethics Sociological-DYSfunctionality!!!

NASA Astrophysics Data System (ADS)

Bradshaw, John; Siegel, E.

2010-03-01

``Sciences''/SEANCES(!!!) rampant UNethics!!! WITNESS: Yau v Perelman Poincare-conj.-pf. [Naser, NewYorker(8/06)]; digits log- law Siegel[AMS Nat.Mtg.(02)-Abs.973-60-124] inversion to ONLY BEQS: Newcomb(1881)<<quanta/bosons=digits!!!; Wolf(DARPA)-Awshalom(UCSB) (so MIS- called) ``spintronics'' copy of Overhauser(54)-(Slichter)-effect: 54<<<90s!!!; Siegel [AMS Nat.Mtg.(02)-Abs.973-03-126] proof: Fermat's: Last-Theorem = Least-Action Ppl:64<<<94(Wiles); ``Bak''/BNL (so called) ``SOC''= F=ma REdiscovery, copying Siegel [PSS(71);...] acoustic-emission:71<<<88: ``Per Bak''?, PRE Bak!!!; ``Bednorz''(v Raveau-Chu) high-Tc cuprate SC Nobel; ``Emery''(˜93)/ BNL high-Tc SC 3-band Hubbard-model v Siegel generic multi-(2- 10)-band spin-orbital-degeneracy(SOD)[Ph.D.,MSU(70);PSS(72;73); JMMM(76-80);World Cong.SC,Munich(92)]:70<<<93!!!; Anderson [1/3<1] failed cuprate high-Tc SC ``RVB'' v Overhauser correct cuprates/pnictides SSDWs:[(60s)<<<(87)];(so called) ``Anderson'' [1/3<1;PRL(58)] localization REdiscovery v Rayleigh(1881)``short- CUT'' graph-theory method[Doyle-Snell, Random-Walks/Electric-Nets (81)]: 1881<<<58; ``Fert''[PRL(88)] 07-Nobel copying v Siegel[at flickr.com,search on ``GMR''; google: ``If Leaks Could Kill'']: [(78)<<<(88)]!!!: Marti[google: ``Brian Martin'']-Bradshaw [Healing the SHAME that BINDS You(80s)]: Ethics? SHMETHICS!!!

Upconversion-pumped luminescence efficiency of rare-earth-doped hosts sensitized with trivalent ytterbium

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

Page, R.H.; Schaffers, K.I.; Waide, P.A.

We discuss the upconversion luminescence efficiencies of phosphors that generate red, green, and blue light. The phosphors studied are single crystals and powders co-doped with Er{sup 3+} and Yb{sup 3+}, and with Tm{sup 3+} and Yb{sup 3+}. The Yb ions are pumped near 980 nm; transfers of two or three quanta to the co-doped rare earth ion generate visible luminescence. The main contribution embodied in this work is the quantitative measurement of this upconversion efficiency, based on the use of a calibrated integrating sphere, determination of the fraction of pump light absorbed, and careful control of the pump laser beammore » profile. The green phosphors are the most efficient, yielding efficiency values as high as 4 %, with the red and blue materials giving 1 - 2 %. Saturation was observed in all cases, suggesting that populations of upconversion steps of the ions are maximized at higher power. Quasi-CW modeling of the intensity- dependent upconversion efficiency was attempted; input data included level lifetimes, transition cross sections, and cross-relaxation rate coefficients. The saturation of the Yb,Er:fluoride media is explained as the pumping of Er{sup 3+} ions into a bottleneck (long-lived state)- the {sup 4}I{sub 13/2} metastable level, making them unavailable for further excitation transfer. 32 refs., 5 figs., 3 tabs.« less

Prospects and fundamental limitations of room temperature, non-avalanche, semiconductor photon-counting sensors (Conference Presentation)

NASA Astrophysics Data System (ADS)

Ma, Jiaju; Zhang, Yang; Wang, Xiaoxin; Ying, Lei; Masoodian, Saleh; Wang, Zhiyuan; Starkey, Dakota A.; Deng, Wei; Kumar, Rahul; Wu, Yang; Ghetmiri, Seyed Amir; Yu, Zongfu; Yu, Shui-Qing; Salamo, Gregory J.; Fossum, Eric R.; Liu, Jifeng

2017-05-01

This research investigates the fundamental limits and trade-space of quantum semiconductor photodetectors using the Schrödinger equation and the laws of thermodynamics.We envision that, to optimize the metrics of single photon detection, it is critical to maximize the optical absorption in the minimal volume and minimize the carrier transit process simultaneously. Integration of photon management with quantum charge transport/redistribution upon optical excitation can be engineered to maximize the quantum efficiency (QE) and data rate and minimize timing jitter at the same time. Due to the ultra-low capacitance of these quantum devices, even a single photoelectron transfer can induce a notable change in the voltage, enabling non-avalanche single photon detection at room temperature as has been recently demonstrated in Si quanta image sensors (QIS). In this research, uniform III-V quantum dots (QDs) and Si QIS are used as model systems to test the theory experimentally. Based on the fundamental understanding, we also propose proof-of-concept, photon-managed quantum capacitance photodetectors. Built upon the concepts of QIS and single electron transistor (SET), this novel device structure provides a model system to synergistically test the fundamental limits and tradespace predicted by the theory for semiconductor detectors. This project is sponsored under DARPA/ARO's DETECT Program: Fundamental Limits of Quantum Semiconductor Photodetectors.

Spin, mass, and symmetry

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

Peskin, M.E.

1994-12-01

When the strong interactions were a mystery, spin seemed to be just a complication on top of an already puzzling set of phenomena. But now that particle physicists have understood the strong, weak, and electromagnetic interactions, to be gauge theories, with matter built of quarks and leptons, it is recognized that the special properties of spin 1/2 and spin 1 particles have taken central role in the understanding of Nature. The lectures in this summer school will be devoted to the use of spin in unravelling detailed questions about the fundamental interactions. Thus, why not begin by posing a deepermore » question: Why is there spin? More precisely, why do the basic pointlike constituents of Nature carry intrinsic nonzero quanta of angular momentum? Though the authos has found no definite answer to this question, the pursuit of an answer has led through a wonderful tangle of speculations on the deep structure of Nature. Is spin constructed or is it fundamental? Is it the requirement of symmetry? In the furthest flights taken, it seems that space-time itself is too restrictive a notion, and that this must be generalized in order to gain a full appreciation of spin. In any case, there is no doubt that spin must play a central role in unlocking the mysteries of fundamental physics.« less

Magnon-mediated current drag across a magnetic insulator

NASA Astrophysics Data System (ADS)

Shi, Jing

Electric current transmission can occur in a magnetic insulator via spin current inter-conversions at heavy metal/magnetic insulator interfaces. In magnetic insulators, spin current is carried by spin wave excitations or their quanta, magnons. This marvelous phenomenon was first theoretically predicted and dubbed as the magnon-mediated current drag in 2012 by Zhang et al.. Following a breakthrough in materials growth, i.e. yttrium iron garnet films or YIG ranging from 30 to 80 nm in thickness sandwiched between two heavy metal films, we successfully showed the nonlocal DC current transmission in such sandwich structures via spin current rather than charge current. To exclude the leakage effect, the experiments are conducted at temperatures below 250 K where the resistance between the metal layers exceeds 20 Gohms. In addition, by replacing the top Pt electrode with beta-Ta which is known to reverse the sign in the spin Hall angle, we found that the nonlocal signal reverses the polarity, which is a direct demonstration of the spin current nature. Furthermore, the temperature dependence of the nonlocal signal confirms the role of magnons in this effect. The work was supported as part of the SHINES, an Energy Frontier Research Center funded by the US Department of Energy, Office of Science, Basic Energy Sciences under Award No. SC0012670.

Failed CTL/NK cell killing and cytokine hypersecretion are directly linked through prolonged synapse time

PubMed Central

Rudd-Schmidt, Jesse A.; Lopez, Jamie A.; Ramsbottom, Kelly M.; Mannering, Stuart I.; Andrews, Daniel M.; Voskoboinik, Ilia

2015-01-01

Failure of cytotoxic T lymphocytes (CTLs) or natural killer (NK) cells to kill target cells by perforin (Prf)/granzyme (Gzm)-induced apoptosis causes severe immune dysregulation. In familial hemophagocytic lymphohistiocytosis, Prf-deficient infants suffer a fatal “cytokine storm” resulting from macrophage overactivation, but the link to failed target cell death is not understood. We show that prolonged target cell survival greatly amplifies the quanta of inflammatory cytokines secreted by CTLs/NK cells and that interferon-γ (IFN-γ) directly invokes the activation and secondary overproduction of proinflammatory IL-6 from naive macrophages. Furthermore, using live cell microscopy to visualize hundreds of synapses formed between wild-type, Prf-null, or GzmA/B-null CTLs/NK cells and their targets in real time, we show that hypersecretion of IL-2, TNF, IFN-γ, and various chemokines is linked to failed disengagement of Prf- or Gzm-deficient lymphocytes from their targets, with mean synapse time increased fivefold, from ∼8 to >40 min. Surprisingly, the signal for detachment arose from the dying target cell and was caspase dependent, as delaying target cell death with various forms of caspase blockade also prevented their disengagement from fully competent CTLs/NK cells and caused cytokine hypersecretion. Our findings provide the cellular mechanism through which failed killing by lymphocytes causes systemic inflammation involving recruitment and activation of myeloid cells. PMID:25732304

Polarization-polarization correlation measurement --- Experimental test of the PPCO methods

NASA Astrophysics Data System (ADS)

Droste, Ch.; Starosta, K.; Wierzchucka, A.; Morek, T.; Rohoziński, S. G.; Srebrny, J.; Wesolowski, E.; Bergstrem, M.; Herskind, B.

1998-04-01

A significant fraction of modern multidetector arrays used for "in-beam" gamma-ray spectroscopy consist of a detectors which are sensitive to linear polarization of gamma quanta. This yields the opportunity to carry out correlation measurements between the gamma rays registered in polarimeters to get information concerning spins and parities of excited nuclear states. The aim of the present work was to study the ability of the polarization- polarization correlation method (the PPCO method). The correlation between the linear polarization of one gamma quantum and the polarization of the second quantum emitted in a cascade from an oriented nucleus (due to a heavy ion reaction) was studied in detail. The appropriate formulae and methods of analysis are presented. The experimental test of the method was performed using the EUROGAM II array. The CLOVER detectors are the parts of the array used as polarimeters. The ^164Yb nucleus was produced via the ^138Ba(^30Si, 4n) reaction. It was found that the PPCO method together with the standard DCO analysis and the polarization- direction correlation method (PDCO) can be helpful for spin, parity and multipolarity assignments. The results suggest that the PPCO method can be applied to modern spectrometers in which a large number of detectors (e.g. CLOVER) are sensitive to polarization of gamma rays.

Thz and Long Path Fourier Transform Spectroscopy of Methanol; Torsionally Coupled High-K Levels

NASA Astrophysics Data System (ADS)

Pearson, John C.; Yu, Shanshan; Drouin, Brian J.; Lees, Ronald M.; Xu, Li-Hong; Billinghurst, Brant E.

2012-06-01

Methanol is nearly ubiquitous in the interstellar gas. The presence of both a-type and b-type dipole moments, asymmetry, and internal rotation assure that any small astronomical observation window will contain multiple methanol transitions. This often allows a great deal about the local physical conditions to be deduced, but only insofar as the spectra are characterized. The Herschel Space Observatory has detected numerous, clearly beam diluted, methanol transitions with quanta surpassing J = 35 in many regions. Unfortunately, observations of methanol often display strong non-thermal behavior whose modeling requires many additional levels to be included in a radiative transfer analysis. Additionally, the intensities of many more highly excited transitions are strongly dependent on the accuracy of the wave functions used in the calculation. We report a combined Fourier Transform Infrared and THz study targeting the high J and K transitions in the ground torsional manifold. Microwave accuracy energy levels have been derived to J > 40 and K as high as 20. These levels illuminate a number of strongly resonant torsional interactions that dominate the high K spectrum of the molecule. Comparison with levels calculated from the rho-axis method Hamiltonian suggest that the rho-axis method should be able to model v_t = 0, 1 and probably v_t = 2 to experimental accuracy. The challenges in determining methanol wave functions to experimental accuracy will be discussed.

Evaluation of classical and novel autoantibodies for the diagnosis of Primary Biliary Cholangitis-Autoimmune Hepatitis Overlap Syndrome (PBC-AIH OS).

PubMed

Nguyen, Henry H; Shaheen, Abdel Aziz; Baeza, Natalia; Lytvyak, Ellina; Urbanski, Stefan J; Mason, Andrew L; Norman, Gary L; Fritzler, Marvin J; Swain, Mark G

2018-01-01

Up to 20% of Primary Biliary Cholangitis (PBC) patients are estimated to have features that overlap with Autoimmune Hepatitis (AIH). Patients with PBC-AIH overlap syndrome (PBC-AIH OS) have been reported to exhibit suboptimal responses to ursodeoxycholic acid therapy, and are more likely to progress to cirrhosis. Anti-double stranded DNA (anti-dsDNA) and anti-p53 have been previously suggested to be potential autoantibodies for identifying patients with PBC-AIH OS. In our well defined PBC patient cohorts, a comprehensive assessment of various classical and novel autoantibodies was evaluated for their utility in identifying PBC-AIH OS patients. PBC-AIH OS was classified according to the Paris criteria and PBC as per the European Association for the Study of the Liver guidelines. Biobanked serum samples from 197 patients at the University of Calgary Liver Unit and the University of Alberta were analyzed for classical and novel autoantibodies. Anti-dsDNA was measured by the Crithidia luciliae immunofluorescence (CLIFT) assay (1:20 dilution) and chemiluminescence (CIA: QUANTA Flash®, Inova Diagnostics, San Diego). Anti-p53, anti-Ro52/TRIM21, anti-YB 1, anti-GW182, anti-Ge-1, and anti-Ago 2 were measured by either an addressable laser bead immunoassay (ALBIA) or line immunoassay (LIA). Autoantibodies against MIT3, gp210, sp100, LKM1, SLA, and the novel autoantibodies Hexokinase-1 (HK-1), and Kelch like protein 12 (KLHL-12) were measured using QUANTA Lite® ELISA assays. We applied non-parametric methods to compare the biomarkers frequencies between study groups. We used multivariate adjusted models and AUROC to compare the diagnostic accuracy of the different autoantibodies alone or in combination with serum biochemistry. 16 out of 197 PBC patients (8.1%) were classified as PBC-AIH OS. Compared to PBC patients, PBC-AIH OS patients were similar in age (median: 59 vs. 63, P = 0.21) and female predominance (94% vs. 89%, P = 1.00). Anti-dsDNA-by CLIFT (37.5% in PBC-AIH OS

Complex temperature dependence of coupling and dissipation of cavity magnon polaritons from millikelvin to room temperature

NASA Astrophysics Data System (ADS)

Boventer, Isabella; Pfirrmann, Marco; Krause, Julius; Schön, Yannick; Kläui, Mathias; Weides, Martin

2018-05-01

Hybridized magnonic-photonic systems are key components for future information processing technologies such as storage, manipulation, or conversion of data both in the classical (mostly at room temperature) and quantum (cryogenic) regime. In this work, we investigate a yttrium-iron-garnet sphere coupled strongly to a microwave cavity over the full temperature range from 290 K to 30 mK . The cavity-magnon polaritons are studied from the classical to the quantum regimes where the thermal energy is less than one resonant microwave quanta, i.e., at temperatures below 1 K . We compare the temperature dependence of the coupling strength geff(T ) , describing the strength of coherent energy exchange between spin ensemble and cavity photon, to the temperature behavior of the saturation magnetization evolution Ms(T ) and find strong deviations at low temperatures. The temperature dependence of magnonic disspation is governed at intermediate temperatures by rare-earth impurity scattering leading to a strong peak at 40 K . The linewidth κm decreases to 1.2 MHz at 30 mK , making this system suitable as a building block for quantum electrodynamics experiments. We achieve an electromagnonic cooperativity in excess of 20 over the entire temperature range, with values beyond 100 in the millikelvin regime as well as at room temperature. With our measurements, spectroscopy on strongly coupled magnon-photon systems is demonstrated as versatile tool for spin material studies over large temperature ranges. Key parameters are provided in a single measurement, thus simplifying investigations significantly.

Vibrational relaxation in liquid chloroform following ultrafast excitation of the CH stretch fundamental

NASA Astrophysics Data System (ADS)

Sibert, Edwin L.; Rey, Rossend

2002-01-01

Vibrational energy flow in liquid chloroform that follows the ultrafast excitation of the CH stretch fundamental is modeled using semiclassical methods. Relaxation rates are calculated using Landau-Teller theory and a time-dependent method both of which consider a quantum mechanical CHCl3 solute molecule coupled to a classical bath of CHCl3 solvent molecules. Probability flow is examined for several potentials to determine the sensitivity of calculated relaxation rates to the parameters that describe the model potentials. Three stages of relaxation are obtained. Probability is calculated to decay initially to a single acceptor state, a combination state of the solute molecule with two quanta of excitation in the CH bend and one in the CCl stretch, in 13-23 ps depending on the potential model employed. This is followed by rapid and complex intramolecular energy flow into the remaining vibrational degrees of freedom. During this second stage the lowest frequency Cl-C-Cl bend is found to serve as a conduit for energy loss to the solvent. The bottleneck for relaxation back to the ground state is predicted to be the slow 100-200 ps relaxation of the CH bend and CCl stretch fundamentals. Several aspects of the incoherent anti-Stokes scattering that follows strong infrared excitation of the CH fundamental as observed by Graener, Zürl, and Hoffman [J. Phys. Chem. B 101, 1745 (1997)] are elucidated in the present study.

W-Z-top-quark bags

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

Crichigno, Marcos P.; Shuryak, Edward; Flambaum, Victor V.

2010-10-01

We discuss a new family of multiquanta-bound states in the standard model which exist due to the mutual Higgs-based attraction of the heaviest members of the standard model, namely, gauge quanta W, Z, and (anti)top quarks, t, t. We use a self-consistent mean-field approximation, up to a rather large particle number N. In this paper we do not focus on weakly bound, nonrelativistic bound states, but rather on 'bags' in which the Higgs vacuum expectation value is significantly modified or depleted. The minimal number N above which such states appear strongly depends on the ratio of the Higgs mass tomore » the masses of W, Z, t, t: For a light Higgs mass, m{sub H{approx}}50 GeV, bound states start from N{approx}O(10), but for a ''realistic'' Higgs mass, m{sub H{approx}}100 GeV, one finds metastable/bound W, Z bags only for N{approx}O(1000). We also found that in the latter case pure top bags disappear for all N, although top quarks can still be well bound to the W bags. Anticipating the cosmological applications (discussed in the following Article [Phys. Rev. D 82, 073019]) of these bags as 'doorway states' for baryosynthesis, we also consider here the existence of such metastable bags at finite temperatures, when standard-model parameters such as Higgs, gauge, and top masses are significantly modified.« less

G protein betagamma-subunits activated by serotonin mediate presynaptic inhibition by regulating vesicle fusion properties.

PubMed

Photowala, Huzefa; Blackmer, Trillium; Schwartz, Eric; Hamm, Heidi E; Alford, Simon

2006-03-14

Neurotransmitters are thought to be released as quanta, where synaptic vesicles deliver packets of neurotransmitter to the synaptic cleft by fusion with the plasma membrane. However, synaptic vesicles may undergo incomplete fusion. We provide evidence that G protein-coupled receptors inhibit release by causing such incomplete fusion. 5-hydroxytryptamine (5-HT) receptor signaling potently inhibits excitatory postsynaptic currents (EPSCs) between lamprey reticulospinal axons and their postsynaptic targets by a direct action on the vesicle fusion machinery. We show that 5-HT receptor-mediated presynaptic inhibition, at this synapse, involves a reduction in EPSC quantal size. Quantal size was measured directly by comparing unitary quantal amplitudes of paired EPSCs before and during 5-HT application and indirectly by determining the effect of 5-HT on the relationship between mean-evoked EPSC amplitude and variance. Results from FM dye-labeling experiments indicate that 5-HT prevents full fusion of vesicles. 5-HT reduces FM1-43 staining of vesicles with a similar efficacy to its effect on the EPSC. However, destaining of FM1-43-labeled vesicles is abolished by lower concentrations of 5-HT that leave a substantial EPSC. The use of a water-soluble membrane impermeant quenching agent in the extracellular space reduced FM1-43 fluorescence during stimulation in 5-HT. Thus vesicles contact the extracellular space during inhibition of synaptic transmission by 5-HT. We conclude that 5-HT, via free Gbetagamma, prevents the collapse of synaptic vesicles into the presynaptic membrane.

Pyridostigmine but not 3,4-diaminopyridine exacerbates ACh receptor loss and myasthenia induced in mice by muscle-specific kinase autoantibody.

PubMed

Morsch, Marco; Reddel, Stephen W; Ghazanfari, Nazanin; Toyka, Klaus V; Phillips, William D

2013-05-15

In myasthenia gravis, the neuromuscular junction is impaired by the antibody-mediated loss of postsynaptic acetylcholine receptors (AChRs). Muscle weakness can be improved upon treatment with pyridostigmine, a cholinesterase inhibitor, or with 3,4-diaminopyridine, which increases the release of ACh quanta. The clinical efficacy of pyridostigmine is in doubt for certain forms of myasthenia. Here we formally examined the effects of these compounds in the antibody-induced mouse model of anti-muscle-specific kinase (MuSK) myasthenia gravis. Mice received 14 daily injections of IgG from patients with anti-MuSK myasthenia gravis. This caused reductions in postsynaptic AChR densities and in endplate potential amplitudes. Systemic delivery of pyridostigmine at therapeutically relevant levels from days 7 to 14 exacerbated the anti-MuSK-induced structural alterations and functional impairment at motor endplates in the diaphragm muscle. No such effect of pyridostigmine was found in mice receiving control human IgG. Mice receiving smaller amounts of MuSK autoantibodies did not display overt weakness, but 9 days of pyridostigmine treatment precipitated generalised muscle weakness. In contrast, one week of treatment with 3,4-diaminopyridine enhanced neuromuscular transmission in the diaphragm muscle. Both pyridostigmine and 3,4-diaminopyridine increase ACh in the synaptic cleft yet only pyridostigmine potentiated the anti-MuSK-induced decline in endplate ACh receptor density. These results thus suggest that ongoing pyridostigmine treatment potentiates anti-MuSK-induced AChR loss by prolonging the activity of ACh in the synaptic cleft.

Dynamic screening in a two-species asymmetric exclusion process

NASA Astrophysics Data System (ADS)

Kim, Kyung Hyuk; den Nijs, Marcel

2007-08-01

The dynamic scaling properties of the one-dimensional Burgers equation are expected to change with the inclusion of additional conserved degrees of freedom. We study this by means of one-dimensional (1D) driven lattice gas models that conserve both mass and momentum. The most elementary version of this is the Arndt-Heinzel-Rittenberg (AHR) process, which is usually presented as a two-species diffusion process, with particles of opposite charge hopping in opposite directions and with a variable passing probability. From the hydrodynamics perspective this can be viewed as two coupled Burgers equations, with the number of positive and negative momentum quanta individually conserved. We determine the dynamic scaling dimension of the AHR process from the time evolution of the two-point correlation functions, and find numerically that the dynamic critical exponent is consistent with simple Kardar-Parisi-Zhang- (KPZ) type scaling. We establish that this is the result of perfect screening of fluctuations in the stationary state. The two-point correlations decay exponentially in our simulations and in such a manner that in terms of quasiparticles, fluctuations fully screen each other at coarse grained length scales. We prove this screening rigorously using the analytic matrix product structure of the stationary state. The proof suggests the existence of a topological invariant. The process remains in the KPZ universality class but only in the sense of a factorization, as (KPZ)2 . The two Burgers equations decouple at large length scales due to the perfect screening.

Deep learning as a tool to distinguish between high orbital angular momentum optical modes

NASA Astrophysics Data System (ADS)

Knutson, E. M.; Lohani, Sanjaya; Danaci, Onur; Huver, Sean D.; Glasser, Ryan T.

2016-09-01

The generation of light containing large degrees of orbital angular momentum (OAM) has recently been demon- strated in both the classical and quantum regimes. Since there is no fundamental limit to how many quanta of OAM a single photon can carry, optical states with an arbitrarily high difference in this quantum number may, in principle, be entangled. This opens the door to investigations into high-dimensional entanglement shared between states in superpositions of nonzero OAM. Additionally, making use of non-zero OAM states can allow for a dramatic increase in the amount of information carried by a single photon, thus increasing the information capacity of a communication channel. In practice, however, it is difficult to differentiate between states with high OAM numbers with high precision. Here we investigate the ability of deep neural networks to differentiate between states that contain large values of OAM. We show that such networks may be used to differentiate be- tween nearby OAM states that contain realistic amounts of noise, with OAM values of up to 100. Additionally, we examine how the classification accuracy scales with the signal-to-noise ratio of images that are used to train the network, as well as those being tested. Finally, we demonstrate the simultaneous classification of < 100 OAM states with greater than 70 % accuracy. We intend to verify our system with experimentally-produced classi- cal OAM states, as well as investigate possibilities that would allow this technique to work in the few-photon quantum regime.

Frontal Theta Links Prediction Errors to Behavioral Adaptation in Reinforcement Learning

PubMed Central

Cavanagh, James F.; Frank, Michael J.; Klein, Theresa J.; Allen, John J.B.

2009-01-01

Investigations into action monitoring have consistently detailed a fronto-central voltage deflection in the Event-Related Potential (ERP) following the presentation of negatively valenced feedback, sometimes termed the Feedback Related Negativity (FRN). The FRN has been proposed to reflect a neural response to prediction errors during reinforcement learning, yet the single trial relationship between neural activity and the quanta of expectation violation remains untested. Although ERP methods are not well suited to single trial analyses, the FRN has been associated with theta band oscillatory perturbations in the medial prefrontal cortex. Medio-frontal theta oscillations have been previously associated with expectation violation and behavioral adaptation and are well suited to single trial analysis. Here, we recorded EEG activity during a probabilistic reinforcement learning task and fit the performance data to an abstract computational model (Q-learning) for calculation of single-trial reward prediction errors. Single-trial theta oscillatory activities following feedback were investigated within the context of expectation (prediction error) and adaptation (subsequent reaction time change). Results indicate that interactive medial and lateral frontal theta activities reflect the degree of negative and positive reward prediction error in the service of behavioral adaptation. These different brain areas use prediction error calculations for different behavioral adaptations: with medial frontal theta reflecting the utilization of prediction errors for reaction time slowing (specifically following errors), but lateral frontal theta reflecting prediction errors leading to working memory-related reaction time speeding for the correct choice. PMID:19969093

Anharmonic vibrational analysis of s-trans and s-cis conformers of acryloyl fluoride using numerical-analytic Van Vleck operator perturbation theory

NASA Astrophysics Data System (ADS)

Krasnoshchekov, Sergey V.; Craig, Norman C.; Koroleva, Lidiya A.; Stepanov, Nikolay F.

2018-01-01

A new gas-phase infrared (IR) spectrum of acryloyl fluoride (ACRF, CH2dbnd CHsbnd CFdbnd O) with a resolution of 0.1 cm- 1 in the range 4000-450 cm- 1 was measured. Theoretical ab initio molecular structures, full quartic potential energy surfaces (PES), and cubic surfaces of dipole moments and polarizability tensor components (electro-optical properties, EOP) of the s-trans and s-cis conformers of the ACRF were calculated by the second-order Møller-Plesset electronic perturbation theory with a correlation consistent Dunning triple-ζ basis set. The numerical-analytic implementation of the second-order operator canonical Van Vleck perturbation theory was employed for predicting anharmonic IR and Raman scattering (RS) spectra of ACRF. To improve the anharmonic predictions, harmonic frequencies were replaced by their counterparts evaluated with the higher-level CCSD(T)/cc-pVTZ model, to form a ;hybrid; PES. The original operator representation of the Hamiltonian is analytically reduced to a quasi-diagonal form, integrated in the harmonic oscillator basis and diagonalized to account for strong resonance couplings. Double canonical transformations of EOP expansions enabled prediction of integral intensities of both fundamental and multi-quanta transitions in IR/RS spectra. Enhanced band shape analysis reinforced the assignments. A thorough interpretation of the new IR experimental spectra and existing matrix-isolation literature data for the mixture of two conformers of ACRF was accomplished, and a number of assignments clarified.

Line Parameters of Ethane (12C_2H_6) at 12 μm with Constrained Multispectrum Fitting

NASA Astrophysics Data System (ADS)

Devi, V. Malathy; Benner, D. Chris; Rinsland, C. P.; Smith, M. A. H.; Sams, R. L.; Blake, T. A.; Flaud, J.-M.; Sung, K.; Brown, L. R.; Mantz, A. W.

2010-06-01

A multispectrum nonlinear least squares technique was applied to simultaneously fit 43 infrared absorption spectra of C_2H_6 between 795 and 850 cm-1. The high resolution (0.0016-0.005 cm-1) spectra were recorded with two different Bruker Fourier transform spectrometers at PNNL and JPL to support Earth and planetary atmosphere studies, e.g. Titan's cold stratosphere. Accurate line positions and absolute intensities at room temperature were retrieved for over 1750 transitions of ν_9. N_2- and self-broadened halfwidth coefficients with their temperature dependences were obtained for over 1330 lines using sample temperatures between ˜150 and 298 K. Constraints to intensity ratios, torsional splittings, halfwidth coefficients and their temperature dependence exponents were incorporated in the analysis to determine these parameters for both torsional split components. The variations of the observed halfwidth coefficients and their temperature dependences with respect to J, K quanta are discussed. No pressure-induced shifts were measured or even required to fit the spectra to their noise levels. Present results are compared with previously reported measurements and predictions. D. Chris Benner, C. P. Rinsland, V. M. Devi, M. A. H. Smith, and D. A. Atkins, JQSRT 1995;53:705-21. Part of the research described in this paper was performed at the Jet Propulsion Laboratory, California Institute of Technology, the College of William and Mary, Connecticut College, and NASA Langley Research Center under contracts and cooperative agreements with the National Aeronautics and Space Administration.

microPMT-A New Photodetector for Gamma Spectrometry and Fast Timing?

NASA Astrophysics Data System (ADS)

Szczęśniak, T.; Grodzicka, M.; Moszyński, M.; Szawłowski, M.; Baszak, J.

2014-10-01

A micro photomultiplier (microPMT or μPMT) works like a classic photomultiplier but the whole device is made directly in a silicon wafer sandwiched between two glass layers. A microPMT has dimensions of only 13x10x2 mm and its photocathode has a size of 3x1 mm. The aim of the work is to check usefulness of a microPMT in gamma spectrometry with scintillators and fast timing. In the first part of the study analysis of the energy resolution obtained with 3x3x1 mm LSO, BGO and CsI(Tl) scintillators is made. The recorded values for 662 keV are equal to 22.9% and 13.5% for CsI and LSO, respectively. The light pulse shapes of a single photoelectron and scintillation signal of LSO are also shown. The important part of the study is measurement of the number of photoelectrons and estimation of the excess noise factor. Only 2200 phe/MeV were obtained for LSO coupled with the tested microPMT. The calculated excess noise factor is equal to 1.4. In the second part, measurements of the time jitter and timing resolution with LSO crystal for 511 keV annihilation quanta are reported. The timing characteristics of the tested device is poor. Its time jitter equals to 1.5 ns, whereas timing resolution for 22Na is 620 ps. All the results are compared with data obtained with classic PMTs.

Contrasting Photophysiological Characteristics of Phytoplankton Assemblages in the Northern South China Sea.

PubMed

Jin, Peng; Gao, Guang; Liu, Xin; Li, Futian; Tong, Shanying; Ding, Jiancheng; Zhong, Zhihai; Liu, Nana; Gao, Kunshan

2016-01-01

The growth of phytoplankton and thus marine primary productivity depend on photophysiological performance of phytoplankton cells that respond to changing environmental conditions. The South China Sea (SCS) is the largest marginal sea of the western Pacific and plays important roles in modulating regional climate and carbon budget. However, little has been documented on photophysiological characteristics of phytoplankton in the SCS. For the first time, we investigated photophysiological characteristics of phytoplankton assemblages in the northern South China Sea (NSCS) using a real-time in-situ active chlorophyll a fluorometry, covering 4.0 × 105 km2. The functional absorption cross section of photosystem II (PSII) in darkness (σPSII) or under ambient light (σPSII') (A2 quanta-1) increased from the surface to deeper waters at all the stations during the survey period (29 July to 23 August 2012). While the maximum (Fv/Fm, measured in darkness) or effective (Fq'/Fm', measured under ambient light) photochemical efficiency of PSII appeared to increase with increasing depth at most stations, it showed inverse relationship with depth in river plume areas. The functional absorption cross section of PSII changes could be attributed to light-adapted genotypic feature due to niche-partition and the alteration of photochemical efficiency of PSII could be attributed to photo-acclimation. The chlorophyll a fluorometry can be taken as an analog to estimate primary productivity, since areas of higher photochemical efficiency of PSII coincided with those of higher primary productivity reported previously in the NSCS.

A Phenomenological Synapse Model for Asynchronous Neurotransmitter Release

PubMed Central

Wang, Tao; Yin, Luping; Zou, Xiaolong; Shu, Yousheng; Rasch, Malte J.; Wu, Si

2016-01-01

Neurons communicate with each other via synapses. Action potentials cause release of neurotransmitters at the axon terminal. Typically, this neurotransmitter release is tightly time-locked to the arrival of an action potential and is thus called synchronous release. However, neurotransmitter release is stochastic and the rate of release of small quanta of neurotransmitters can be considerably elevated even long after the ceasing of spiking activity, leading to asynchronous release of neurotransmitters. Such asynchronous release varies for tissue and neuron types and has been shown recently to be pronounced in fast-spiking neurons. Notably, it was found that asynchronous release is enhanced in human epileptic tissue implicating a possibly important role in generating abnormal neural activity. Current neural network models for simulating and studying neural activity virtually only consider synchronous release and ignore asynchronous transmitter release. Here, we develop a phenomenological model for asynchronous neurotransmitter release, which, on one hand, captures the fundamental features of the asynchronous release process, and, on the other hand, is simple enough to be incorporated in large-size network simulations. Our proposed model is based on the well-known equations for short-term dynamical synaptic interactions and includes an additional stochastic term for modeling asynchronous release. We use experimental data obtained from inhibitory fast-spiking synapses of human epileptic tissue to fit the model parameters, and demonstrate that our model reproduces the characteristics of realistic asynchronous transmitter release. PMID:26834617

Optical Trapping of Ion Coulomb Crystals

NASA Astrophysics Data System (ADS)

Schmidt, Julian; Lambrecht, Alexander; Weckesser, Pascal; Debatin, Markus; Karpa, Leon; Schaetz, Tobias

2018-04-01

The electronic and motional degrees of freedom of trapped ions can be controlled and coherently coupled on the level of individual quanta. Assembling complex quantum systems ion by ion while keeping this unique level of control remains a challenging task. For many applications, linear chains of ions in conventional traps are ideally suited to address this problem. However, driven motion due to the magnetic or radio-frequency electric trapping fields sometimes limits the performance in one dimension and severely affects the extension to higher-dimensional systems. Here, we report on the trapping of multiple barium ions in a single-beam optical dipole trap without radio-frequency or additional magnetic fields. We study the persistence of order in ensembles of up to six ions within the optical trap, measure their temperature, and conclude that the ions form a linear chain, commonly called a one-dimensional Coulomb crystal. As a proof-of-concept demonstration, we access the collective motion and perform spectrometry of the normal modes in the optical trap. Our system provides a platform that is free of driven motion and combines advantages of optical trapping, such as state-dependent confinement and nanoscale potentials, with the desirable properties of crystals of trapped ions, such as long-range interactions featuring collective motion. Starting with small numbers of ions, it has been proposed that these properties would allow the experimental study of many-body physics and the onset of structural quantum phase transitions between one- and two-dimensional crystals.

Spin-triplet electron transport in hybrid superconductor heterostructures with a composite ferromagnetic interlayer

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

Sheyerman, A. E., E-mail: karen@hitech.cplire.ru; Constantinian, K. Y.; Ovsyannikov, G. A.

2015-06-15

Hybrid YBa{sub 2}Cu{sub 3}O{sub 7−x}/SrRuO{sub 3}/La{sub 0.7}Sr{sub 0.3}MnO{sub 3}/Au-Nb superconductor mesastructures with a composite manganite-ruthenate ferromagnetic interlayer are studied using electrophysical, magnetic, and microwave methods. The supercurrent in the mesastructure is observed when the interlayer thickness is much larger than the coherence length of ferromagnetic materials. The peak on the dependence of the critical current density on the interlayer material thickness corresponds to the coherence length, which is in qualitative agreement with theoretical predictions for a system with spit-triplet superconducting correlations. The magnetic-field dependence of the critical current is determined by penetration of magnetic flux quanta and by the magneticmore » domain structure, as well as by the field dependence of disorientation of the magnetization vectors of the layers in the composite magnetic interlayer. It is found that the supercurrent exists in magnetic fields two orders of magnitude stronger than the field corresponding to entry of a magnetic flux quantum into the mesastructure. The current-phase relation (CPR) of the supercurrent of mesastructures is investigated upon a change in the magnetic field from zero to 30 Oe; the ratio of the second CPR harmonic to the first, determined from the dependence of the Shapiro steps on the microwave radiation amplitude, does not exceed 50%.« less

Cation Binding to Xanthorhodopsin: Electron Paramagnetic Resonance and Magnetic Studies.

PubMed

Smolensky Koganov, Elena; Leitus, Gregory; Rozin, Rinat; Weiner, Lev; Friedman, Noga; Sheves, Mordechai

2017-05-04

Xanthorhodopsin (xR) is a member of the retinal protein family and acts as a proton pump in the cell membranes of the extremely halophilic eubacterium Salinibacter ruber. In addition to the retinal chromophore, xR contains a carotenoid, which acts as a light-harvesting antenna as it transfers 40% of the quanta it absorbs to the retinal. Our previous studies have shown that the CD and absorption spectra of xR are dramatically affected due to the protonation of two different residues. It is still unclear whether xR can bind cations. Electron paramagnetic resonance (EPR) spectroscopy used in the present study revealed that xR can bind divalent cations, such as Mn 2+ and Ca 2+ , to deionized xR (DI-xR). We also demonstrate that xR can bind 1 equiv of Mn 2+ to a high-affinity binding site followed by binding of ∼40 equiv in cooperative manner and ∼100 equiv of Mn 2+ that are weakly bound. SQUID magnetic studies suggest that the high cooperative binding of Mn 2+ cations to xR is due to the formation of Mn 2+ clusters. Our data demonstrate that Ca 2+ cations bind to DI-xR with a lower affinity than Mn 2+ , supporting the assumption that binding of Mn 2+ occurs through cluster formation, because Ca 2+ cations cannot form clusters in contrast to Mn 2+ .

Ultraviolet radiation from the pulsed corona discharge in water

NASA Astrophysics Data System (ADS)

Lukes, Petr; Clupek, Martin; Babicky, Vaclav; Sunka, Pavel

2008-05-01

Quantitative analysis of ultraviolet radiation from the pulsed corona discharge in water with needle-plate electrode geometry (~1-3 J pulse-1) was performed using the potassium ferrioxalate actinometry. Photon flux J190-280 and radiant energy Q190-280 of the UV light emitted from the discharge at spectral region 190-280 nm was determined in dependence on the applied voltage (17-29 kV, positive polarity) and the solution conductivity (100-500 µS cm-1). The intensity of the UV radiation strongly increased with increasing water conductivity and applied voltage. Depending on the applied voltage the determined photon flux varied by more than two orders of magnitude within the range of solution conductivities 100-500 µS cm-1. It was found that photon flux from the discharge may be directly related to the discharge pulse mean power Pp as J190-280 = 44.33 P_p^{2.11} (quanta pulse-1). A significant role of UV radiation in the production of hydrogen peroxide and bacterial inactivation by the corona discharge in water has been identified. As the solution conductivity increased the yield of H2O2 produced by the discharge decreased due to increasing photolysis of H2O2 accounting for up to 14% of the total decomposition rate of H2O2. As regards bactericidal effects, it was estimated that the UV radiation contributes about 30% to the overall inactivation of Escherichia coli.

Interactions between the visual and the magnetoreception system: different effects of bichromatic light regimes on the directional behavior of migratory birds.

PubMed

Wiltschko, Roswitha; Dehe, Lars; Gehring, Dennis; Thalau, Peter; Wiltschko, Wolfgang

2013-01-01

When magnetic compass orientation of migratory robins was tested, the birds proved well oriented under low intensity monochromatic light of shorter wavelengths up to 565 nm green; from 583 nm yellow onward, they were disoriented. In the present study, we tested robins under bichromatic lights composed (1) of 424 nm blue and 565 nm green and (2) of 565 nm green and 583 nm yellow at two intensities. Under dim blue-green light with a total quantal flux of ca. 8 × 10(15)quanta/sm(2), the birds were well oriented in their migratory direction by their inclination compass; under blue-green light of twice this intensity, their orientation became axial. In both cases, the magnetic directional information was mediated by the radical pair processes in the eye. When green and yellow light were combined, however, the nature of the behavior changed. Under green-yellow light of the higher intensity, the birds showed a 'fixed direction' response that was polar, no longer controlled by the normal inclination compass; under dim green-yellow light, the response became axial. Under these two light conditions, the respective directional information was mediated by the magnetite-based receptors in the skin of the upper beak. Apparently, yellow light leads to a change from one magnetoreception system to the other. How this change is effected is still unknown; it appears to reflect complex interactions between the visual and the two magnetoreception systems. Copyright © 2012 Elsevier Ltd. All rights reserved.

Zonal-flow dynamics from a phase-space perspective

NASA Astrophysics Data System (ADS)

Ruiz, D. E.; Parker, J. B.; Shi, E. L.; Dodin, I. Y.

2017-10-01

The wave kinetic equation (WKE) describing drift-wave (DW) turbulence is widely used in the studies of zonal flows (ZFs) emerging from DW turbulence. However, this formulation neglects the exchange of enstrophy between DWs and ZFs and also ignores effects beyond the geometrical-optics (GO) limit. Here we present a new theory that captures both of these effects, while still treating DW quanta (``driftons'') as particles in phase space. In this theory, the drifton dynamics is described by an equation of the Wigner-Moyal type, which is analogous to the phase-space formulation of quantum mechanics. The ``Hamiltonian'' and the ``dissipative'' parts of the DW-ZF interactions are clearly identified. Moreover, this theory can be interpreted as a phase-space representation of the second-order cumulant expansion (CE2). In the GO limit, this formulation features additional terms missing in the traditional WKE that ensure conservation of the total enstrophy of the system, in addition to the total energy, which is the only conserved invariant in previous theories based on the traditional WKE. Numerical simulations are presented to illustrate the importance of these additional terms. Supported by the U.S. DOE through Contract Nos. DE-AC02-09CH11466 and DE-AC52-07NA27344, by the NNSA SSAA Program through DOE Research Grant No. DE-NA0002948, and by the U.S. DOD NDSEG Fellowship through Contract No. 32-CFR-168a.

The photon-plasmon transitions and diagnostics of the space plasma turbulence

NASA Astrophysics Data System (ADS)

Glushkov, Alexander; Glushkov, Alexander; Khetselius, Olga

We present a new approach to treating the space plasma turbulence, based on using to make diagnostic data regarding the photon-plasmon transitions. The theoretical definition of characteristics for these transitions is caried out within consistent theoretical approach, based on the Gell-Mann and Low formalism (energy approach in QED theory).We apply it to calculation of such transitions (Ps) with emission of photon and Langmuir quanta. It is well known that the hfs states of positronium Ps Ps differ in spin S, life time t and mode of annihilation. As a rule, probabilities of the cascade radiation transitions are more than the annihilation probability. The ortho-Ps atom has a metastable state 23s1 and probability of two-photon radiation transition from this state into 13s1 state (1.8•10(-3) 1/s) is significantly less than probability of the three-photon annihilation directly from 23s1level 8.9•10(5) s(-1), i.e. it is usually supposed that the ortho-Ps annihilates from 23s1state. Another situation may take place in plasma, where it is arisen the competition process of destruction of the metastable level - the photonplasmon transition 23s1-13s1with emission of photon and Langmuir quanta. In this paper we carried out the calculation of the probability of the Ps photon-plasmon transition and propose tu use it for diagnostics of the space plasma (dusty one etc.).Standard S-matrix calculation with using an expression for tensor of dielectric permeability of the isotropic space plasma and dispersion relationships for transverse and Langmuir waves [3] allows getting the corresponding probability P(ph-pl). Numerical value of P(ph-pl) is 5.2•10(6)•UL(s-1), where UL is density of the Langmuir waves energy. Our value is correlated with estimate, available in literature [3]: P(phpl)= 6•10(6)•UL (s-1). Comparison of the obtained probability with the life time t(3) allows getting the condition of predominance of the photon-plasmon transition over three

A hypothetical mathematical construct explaining the mechanism of biological amplification in an experimental model utilizing picoTesla (PT) electromagnetic fields.

PubMed

Saxena, Anjali; Jacobson, Jerry; Yamanashi, William; Scherlag, Benjamin; Lamberth, John; Saxena, Brij

2003-06-01

We seek to answer the conundrum: What is the fundamental mechanism by which very weak, low frequency Electromagnetic fields influence biosystems? In considering the hydrophobicity of intramembranous protein (IMP) H-bonds which cross the phospholipid bilayer of plasma membranes, and the necessity for photonic recycling in cell surface interactions after dissipation of energetic states, present models lack structure and thermodynamic properties to maintain (DeltaE) sufficient energy sources necessary for amplifications by factors of 10(12). Even though one accepts that the ligand-receptor association alters the conformation of extracellular, extruding portions of IMP's at the cell surface, and that this change can be transmitted to the cytoplasm by the transmembranous helical segments by nonlinear vibrations of proteins with generation of soliton waves, one is still unable to account for repair and balanced function. Indeed, responses of critical molecules to certain magnetic field signals may include enhanced vibrational amplitudes, increased quanta of thermal energies and order inducing interactions. We may accept that microtrabecular reticulum-receptor is associated with actin filaments and ATP molecules which contribute to the activation of the cyclase enzyme system through piezoelectricity. Magnetic fields will pass through the membrane which sharply attenuates the electric field component of an EM field, due to its high impedance. Furthermore, EM oscillations are converted to mechanical vibrations; i.e., photon-phonon transduction, to induce molecular vibrations of frequencies specifically responsible for bioamplifications of weak triggers at the membrane surface, as well as GAP junctions. The hydrogen bonds of considerable importance are those in proteins (10(12)Hz) and DNA (10(11)Hz) and may be viewed as centers of EM radiation emission in the range from the mm microwaves to the far IR. However, classical electrodynamical theory does not yield a model for

Experiment Pamir-3. Coplanar emission of high energy gamma-quanta at interaction of hadrons with nuclei of air atoms at energies above 10 to the 7th power GeV

NASA Technical Reports Server (NTRS)

Asatiani, T. L.; Genina, L. E.; Zatsepin, G. T.

1985-01-01

A systematic analysis of large gamma families, detected in X-ray emulsion chambers, cases of multicore halos have been observed, and among them five events in which the halo is divided into three of four separate cores with their alignment observed in the target diagram (coplanarity of axes of corresponding electron photon cascades). The halo alignment (tendency to the straight line) leads to the aximuthal asymmetry (thrust). The analysis of lateral and momentum distributions of particles in these families shows that they also have thrust that correlates with the direction of the halo core alignment.

[THE EFFECT OF ACID RAIN ON ULTRASTRUCTURE AND FUNCTIONAL PARAMETERS OF PHOTOSYNTHETIC APPARATUS OF PEA LEAVES].

PubMed

Polishchuk, A V; Vodka, M V; Belyavskaya, N A; Khomochkin, A P; Zolotareva, E K

2016-01-01

The effects of simulated acid rain (SAR) on the ultrastructure and functional parameters of the photosynthetic apparatus were studied using 14-day-old pea leaves as test system. Pea plants were sprayed with an aqueous solution containing NaNO₃(0.2 mM) and Na₂SO₄(0.2 mM) (pH 5.6, a control variant), or with the same solution, which was acidified to pH 2.5 (acid variant). Functional characteristics were determined by chlorophyll fluorescence analysis. Acid rain application caused reduction in the efficiency of the photosynthetic electron transport by 25%, which was accompanied by an increase by 85% in the quantum yield of thermal dissipation of excess light quanta. Ultrastructural changes in chloroplast were registered by transmission electron microscopy (TEM) after two days of the SAR-treatment of pea leaves. In this case, the changes in the structure of grana, heterogeneity of thylakoids packaging in granum, namely, the increase of intra-thylakoid gaps and thickness of granal thylakoids compared to the control were found. The migration of protein complexes in thylakoid membranes of chloroplasts isolated from leaves treated with SAR was suppressed. It was shown also that carbonic anhydrase activity was inhibited in chloroplast preparations isolated from SAR-treated pea leaves. We proposed a hypothesis on the possible inactivation of thylakoid carbonic anhydrase under SAR and its involvement in the inhibition of photochemical activity of chloroplasts. The data obtained allows to suggest that acid rains negatively affect the photosynthetic apparatus disrupting the membrane system of chloroplast.

X-ray microscopy using reflection targets based on SEM with tungsten filament

NASA Astrophysics Data System (ADS)

Liu, Junbiao; Ma, Yutian; Zhao, Weixia; Niu, Geng; Chu, Mingzhang; Yin, Bohua; Han, Li; Liu, Baodong

2016-10-01

X-ray MicroandNano imaging is developed based on the conventional x-ray tomography, it can not only provide nondestructive testing with higher resolution measurement, but also be used to examine the material or the structure with low atomic number and low density. The source with micro-focal spot size is one of the key components of x-ray MicroandNano imaging. The focused electron beam from SEM bombarding the metal target can generate x-ray with ultra-small size. It is convenient to set up x-ray microscopy based on SEM for laboratory use. This paper describes a new x-ray microscopy using reflection targets based on FEI Quanta600 SEM with tungsten filament. The flat panel detector is placed outside of the vacuum chamber with 300μm thickness Be-window to isolate vacuum from the air. A stage with 3 DOFs is added to adjust the positions of the target, the SEM's sample stage is used to move sample. And the shape of target is designed as cone with 60° half cone angle to get the maximum x-ray dosage. The attenuation coefficient of Bewindow for x-ray is about 25%. Finally, the line pair card is used to evaluate the resolution and the result shows that the resolution of the system can receive less than 750nm, when the acceleration voltage is 30keV, the beam current is 160nA, the SEM working distance is 5mm and the acquisition time of the detector is 60s.

Rubisco activity is associated with photosynthetic thermotolerance in a wild rice (Oryza meridionalis).

PubMed

Scafaro, Andrew P; Yamori, Wataru; Carmo-Silva, A Elizabete; Salvucci, Michael E; von Caemmerer, Susanne; Atwell, Brian J

2012-09-01

Oryza meridionalis is a wild species of rice, endemic to tropical Australia. It shares a significant genome homology with the common domesticated rice Oryza sativa. Exploiting the fact that the two species are highly related but O. meridionalis has superior heat tolerance, experiments were undertaken to identify the impact of temperature on key events in photosynthesis. At an ambient CO(2) partial pressure of 38 Pa and irradiance of 1500 µmol quanta m(-2) s(-1), the temperature optimum of photosynthesis was 33.7 ± 0.8°C for O. meridionalis, significantly higher than the 30.6 ± 0.7°C temperature optimum of O. sativa. To understand the basis for this difference, we measured gas exchange and rubisco activation state between 20 and 42°C and modeled the response to determine the rate-limiting steps of photosynthesis. The temperature response of light respiration (R(light)) and the CO(2) compensation point in the absence of respiration (Γ(*)) were determined and found to be similar for the two species. C3 photosynthesis modeling showed that despite the difference in susceptibility to high temperature, both species had a similar temperature-dependent limitation to photosynthesis. Both rice species were limited by ribulose-1,5-bisphosphate (RuBP) regeneration at temperatures of 25 and 30°C but became RuBP carboxylation limited at 35 and 40°C. The activation state of rubisco in O. meridionalis was more stable at higher temperatures, explaining its greater heat tolerance compared with O. sativa. Copyright © Physiologia Plantarum 2012.

Pyridostigmine but not 3,4-diaminopyridine exacerbates ACh receptor loss and myasthenia induced in mice by muscle-specific kinase autoantibody

PubMed Central

Morsch, Marco; Reddel, Stephen W; Ghazanfari, Nazanin; Toyka, Klaus V; Phillips, William D

2013-01-01

In myasthenia gravis, the neuromuscular junction is impaired by the antibody-mediated loss of postsynaptic acetylcholine receptors (AChRs). Muscle weakness can be improved upon treatment with pyridostigmine, a cholinesterase inhibitor, or with 3,4-diaminopyridine, which increases the release of ACh quanta. The clinical efficacy of pyridostigmine is in doubt for certain forms of myasthenia. Here we formally examined the effects of these compounds in the antibody-induced mouse model of anti-muscle-specific kinase (MuSK) myasthenia gravis. Mice received 14 daily injections of IgG from patients with anti-MuSK myasthenia gravis. This caused reductions in postsynaptic AChR densities and in endplate potential amplitudes. Systemic delivery of pyridostigmine at therapeutically relevant levels from days 7 to 14 exacerbated the anti-MuSK-induced structural alterations and functional impairment at motor endplates in the diaphragm muscle. No such effect of pyridostigmine was found in mice receiving control human IgG. Mice receiving smaller amounts of MuSK autoantibodies did not display overt weakness, but 9 days of pyridostigmine treatment precipitated generalised muscle weakness. In contrast, one week of treatment with 3,4-diaminopyridine enhanced neuromuscular transmission in the diaphragm muscle. Both pyridostigmine and 3,4-diaminopyridine increase ACh in the synaptic cleft yet only pyridostigmine potentiated the anti-MuSK-induced decline in endplate ACh receptor density. These results thus suggest that ongoing pyridostigmine treatment potentiates anti-MuSK-induced AChR loss by prolonging the activity of ACh in the synaptic cleft. PMID:23440963

State-to-state time-of-flight measurements of NO scattering from Au(111): direct observation of translation-to-vibration coupling in electronically nonadiabatic energy transfer.

PubMed

Golibrzuch, Kai; Shirhatti, Pranav R; Altschäffel, Jan; Rahinov, Igor; Auerbach, Daniel J; Wodtke, Alec M; Bartels, Christof

2013-09-12

Translational motion is believed to be a spectator degree of freedom in electronically nonadiabatic vibrational energy transfer between molecules and metal surfaces, but the experimental evidence available to support this view is limited. In this work, we have experimentally determined the translational inelasticity in collisions of NO molecules with a single-crystal Au(111) surface-a system with strong electronic nonadiabaticity. State-to-state molecular beam surface scattering was combined with an IR-UV double resonance scheme to obtain high-resolution time-of-flight data. The measurements include vibrationally elastic collisions (v = 3→3, 2→2) as well as collisions where one or two quanta of molecular vibration are excited (2→3, 2→4) or de-excited (2→1, 3→2, 3→1). In addition, we have carried out comprehensive measurements of the effects of rotational excitation on the translational energy of the scattered molecules. We find that under all conditions of this work, the NO molecules lose a large fraction (∼0.45) of their incidence translational energy to the surface. Those molecules that undergo vibrational excitation (relaxation) during the collision recoil slightly slower (faster) than vibrationally elastically scattered molecules. The amount of translational energy change depends on the surface temperature. The translation-to-rotation coupling, which is well-known for v = 0→0 collisions, is found to be significantly weaker for vibrationally inelastic than elastic channels. Our results clearly show that the spectator view of the translational motion in electronically nonadiabatic vibrational energy transfer between NO and Au(111) is only approximately correct.

Quantum dynamics of the vibrations of helium bound to the nanosurface of a large planar organic molecule: phthalocyanine . He van der Waals complex.

PubMed

Gibbons, Brittney R; Xu, Minzhong; Bacić, Zlatko

2009-04-23

We report rigorous quantum three-dimensional calculations of highly excited intermolecular vibrational states of the van der Waals (vdW) complex phthalocyanine.He (Pc.He). The Pc molecule was treated as rigid and the intermolecular potential energy surface (IPES) was represented as a sum of atom-atom Lennard-Jones pair potentials. The IPES has four equivalent global minima on the diagonals of the square-shaped Pc, inside its five-membered rings, and four slightly shallower local minima between them, creating a distinctive corrugation pattern of the molecular nanosurface. The vdW vibrational states analyzed in this work extend to about two-thirds of the well depth of the IPES. For the assignment of the in-plane (xy) vdW vibrational excitations it was necessary to resort to two sets of quantum numbers, the Cartesian quantum numbers [nu(x), nu(y)] and the quantum numbers (v, l) of the 2D isotropic oscillator, depending on the nodal structure and the symmetry of the wave functions. The delocalization of the He atom parallel to the molecular surface is large already in the ground vdW state. It increases rapidly with the number of quanta in the in-plane vdW vibrations, with the maximum root-mean-square amplitudes Deltax and Deltay of about 7 au at the excitation energies around 40 cm(-1). The wave functions of the highly excited states tend to be delocalized over the entire nanosurface and often have a square shape, reflecting that of the substrate.

Linking structure and vibrational mode coupling using high-resolution infrared spectroscopy: A comparison of gauche and trans 1-chloro-2-fluoroethane

NASA Astrophysics Data System (ADS)

Miller, C. Cameron; Stone, Stephen C.; Philips, Laura A.

1995-01-01

The high-resolution infrared spectrum of 1-chloro-2-fluoroethane in a molecular beam was collected over the 2975-2994 cm-1 spectral region. The spectral region of 2975-2981 cm-1 contains a symmetric C-H stretching vibrational band of the gauche conformer containing the 35Cl isotope. The spectral region of 2985-2994 cm-1 contains three vibrational bands of the trans conformer. Two of the three bands are assigned as an antisymmetric C-H stretch of each of the two different chlorine isotopes. The third band is assigned as a symmetric C-H stretch of the 35Cl isotope. The gauche conformer of 1-chloro-2-fluoroethane showed doublet patterns similar to those previously observed in 1,2-difluoroethane. The model for 1,2-difluoroethane is further refined in the present work. These refinements suggest that the coupling dark state in 1,2-difluoroethane is composed of 1 quantum C-H bend, 1 quantum C-C stretch, and 12 quanta of torsion. For 1-chloro-2-fluoroethane the dark state could not be identified due to a small data set. The trans conformer of 1-chloro-2-fluoroethane showed no evidence of mode coupling in the three vibrational bands. Including 2-fluoroethanol in this series of molecules, the extent of vibrational mode coupling did not correlate with the density of states available for coupling. Therefore, density of states alone is insufficient to explain the observed trend. A correlation was observed between the degree of intramolecular interaction and vibrational mode coupling.

The Post-Illumination Pupil Response Is Reduced in Glaucoma Patients

PubMed Central

Kankipati, Laxmikanth; Girkin, Christopher A.; Gamlin, Paul D.

2011-01-01

Purpose. The post-illumination pupil response (PIPR), which is driven by the intrinsic response of melanopsin-containing, intrinsically photosensitive retinal ganglion cells, has previously been characterized in healthy eyes. The present study examined whether the PIPR is affected in patients with glaucoma compared with healthy subjects. Methods. Sixteen glaucoma patients (mean age, 63.7 years) were tested by presenting a 60°, 10-second light stimulus (13 log quanta/cm2/s retinal irradiance) of either 470 nm (blue) or 623 nm (red) to one eye after dilation. The consensual pupil response of the fellow undilated eye was recorded by infrared pupillometry for 50 seconds after light offset. These pupillary responses were compared with those of 19 age-matched controls (mean age, 59 years). Results. The glaucoma patients displayed a net PIPR (blue PIPR minus red PIPR) that was significantly (t-test, P < 0.001) smaller (0.6 mm, SEM 0.12; P < 0.05) than in age-matched controls (1.3 mm, SEM 0.16; P < 0.001). For the patient population, the magnitude of the net PIPR was inversely correlated with the measured visual field loss (mean deviation) of the tested eye. Conclusions. This study demonstrates that there is a significant decrease in the ipRGC-mediated PIPR in glaucomatous patients when compared to age-matched controls. As the severity of the glaucomatous neuropathy increases, there is a correlated decrease in the PIPR. Therefore, this test has the potential for use as a clinical tool in evaluating patients with glaucoma. PMID:21212172

Arctic Tundra Vegetation Functional Types Based on Photosynthetic Physiology and Optical Properties

NASA Technical Reports Server (NTRS)

Huemmrich, Karl F.; Gamon, John; Tweedie, Craig; Campbell, Petya P. K.; Landis, David; Middleton, Elizabeth

2012-01-01

Climate change in tundra regions may alter vegetation species composition and ecosystem carbon balance. Remote sensing provides critical tools for monitoring these changes as optical signals provide a way to scale from plot measurements to regional patterns. Gas exchange measurements of pure patches of key vegetation functional types (lichens, mosses, and vascular plants) in sedge tundra at Barrow AK, show three significantly different values of light use efficiency (LUE) with values of 0.013+/-0.001, 0.0018+/-0.0002, and 0.0012 0.0001 mol C/mol absorbed quanta for vascular plants, mosses and lichens, respectively. Further, discriminant analysis of patch reflectance identifies five spectral bands that can separate each vegetation functional type as well as nongreen material (bare soil, standing water, and dead leaves). These results were tested along a 100 m transect where midsummer spectral reflectance and vegetation coverage were measured at one meter intervals. Area-averaged canopy LUE estimated from coverage fractions of the three functional types varied widely, even over short distances. Patch-level statistical discriminant functions applied to in situ hyperspectral reflectance successfully unmixed cover fractions of the vegetation functional types. These functions, developed from the tram data, were applied to 30 m spatial resolution Earth Observing-1 Hyperion imaging spectrometer data to examine regional variability in distribution of the vegetation functional types and from those distributions, the variability of LUE. Across the landscape, there was a fivefold variation in tundra LUE that was correlated to a spectral vegetation index developed to detect vegetation chlorophyll content.

Indirect-detection single-photon-counting x-ray detector for breast tomosynthesis

NASA Astrophysics Data System (ADS)

Jiang, Hao; Kaercher, Joerg; Durst, Roger

2016-03-01

X-ray mammography is a crucial screening tool for early identification of breast cancer. However, the overlap of anatomical features present in projection images often complicates the task of correctly identifying suspicious masses. As a result, there has been increasing interest in acquisition of volumetric information through digital breast tomosynthesis (DBT) which, compared to mammography, offers the advantage of depth information. Since DBT requires acquisition of many projection images, it is desirable that the noise in each projection image be dominated by the statistical noise of the incident x-ray quanta and not by the additive noise of the imaging system (referred to as quantum-limited imaging) and that the cumulative dose be as low as possible (e.g., no more than for a mammogram). Unfortunately, the electronic noise (~2000 electrons) present in current DBT systems based on active matrix, flat-panel imagers (AMFPIs) is still relatively high compared with modest x-ray gain of the a-Se and CsI:Tl x-ray converters often used. To overcome the modest signal-to-noise ratio (SNR) limitations of current DBT systems, we have developed a large-area x-ray imaging detector with the combination of an extremely low noise (~20 electrons) active-pixel CMOS and a specially designed high resolution scintillator. The high sensitivity and low noise of such system provides better SNR by at least an order of magnitude than current state-of-art AMFPI systems and enables x-ray indirect-detection single photon counting (SPC) at mammographic energies with the potential of dose reduction.

Application of two-dimensional NMR spectroscopy and molecular dynamics simulations to the conformational analysis of oligosaccharides corresponding to the cell-wall polysaccharide of Streptococcus group A.

PubMed

Kreis, U C; Varma, V; Pinto, B M

1995-06-01

This paper describes the use of a protocol for conformational analysis of oligosaccharide structures related to the cell-wall polysaccharide of Streptococcus group A. The polysaccharide features a branched structure with an L-rhamnopyranose (Rhap) backbone consisting of alternating alpha-(1-->2) and alpha-(1-->3) links and D-N-acetylglucosamine (GlcpNAc) residues beta-(1-->3)-connected to alternating rhamnose rings: [formula: see text] Oligomers consisting of three to six residues have been synthesized and nuclear magnetic resonance (NMR) assignments have been made. The protocol for conformational analysis of the solution structure of these oligosaccharides involves experimental and theoretical methods. Two-dimensional NMR spectroscopy methods (TOCSY, ROESY and NOESY) are utilized to obtain chemical shift data and proton-proton distances. These distances are used as constraints in 100 ps molecular dynamics simulations in water using QUANTA and CHARMm. In addition, the dynamics simulations are performed without constraints. ROE build-up curves are computed from the averaged structures of the molecular dynamics simulations using the CROSREL program and compared with the experimental curves. Thus, a refinement of the initial structure may be obtained. The alpha-(1-->2) and the beta-(1-->3) links are unambiguously defined by the observed ROE cross peaks between the A-B',A'-B and C-B,C'-B' residues, respectively. The branch-point of the trisaccharide CBA' is conformationally well-defined. Assignment of the conformation of the B-A linkage (alpha-(1-->3)) was problematic due to TOCSY relay, but could be solved by NOESY and T-ROESY techniques. A conformational model for the polysaccharide is proposed.

An investigation of automatic exposure control calibration for chest imaging with a computed radiography system.

PubMed

Moore, C S; Wood, T J; Avery, G; Balcam, S; Needler, L; Beavis, A W; Saunderson, J R

2014-05-07

The purpose of this study was to examine the use of three physical image quality metrics in the calibration of an automatic exposure control (AEC) device for chest radiography with a computed radiography (CR) imaging system. The metrics assessed were signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR) and mean effective noise equivalent quanta (eNEQm), all measured using a uniform chest phantom. Subsequent calibration curves were derived to ensure each metric was held constant across the tube voltage range. Each curve was assessed for its clinical appropriateness by generating computer simulated chest images with correct detector air kermas for each tube voltage, and grading these against reference images which were reconstructed at detector air kermas correct for the constant detector dose indicator (DDI) curve currently programmed into the AEC device. All simulated chest images contained clinically realistic projected anatomy and anatomical noise and were scored by experienced image evaluators. Constant DDI and CNR curves do not appear to provide optimized performance across the diagnostic energy range. Conversely, constant eNEQm and SNR do appear to provide optimized performance, with the latter being the preferred calibration metric given as it is easier to measure in practice. Medical physicists may use the SNR image quality metric described here when setting up and optimizing AEC devices for chest radiography CR systems with a degree of confidence that resulting clinical image quality will be adequate for the required clinical task. However, this must be done with close cooperation of expert image evaluators, to ensure appropriate levels of detector air kerma.

Topologically protected unidirectional edge spin waves

NASA Astrophysics Data System (ADS)

Wang, Xiang Rong; Wang, Xiansi; Su, Ying

Magnetic materials are highly correlated spin systems that do not respect the time-reversal symmetry. The low-energy excitations of magnetic materials are spin waves whose quanta are magnons. Like electronic materials that can be topologically nontrivial, a magnetic material can also be topologically nontrivial with topologically protected unidirectional edge states. These edge states should be superb channels of processing and manipulating spin waves because they are robust against perturbations and geometry changes, unlike the normal spin wave states that are very sensitive to the system changes and geometry. Therefore, the magnetic topological matter is of fundamental interest and technologically useful in magnonics. Here, we show that ferromagnetically interacting spins on a two-dimensional honeycomb lattice with nearest-neighbour interactions and governed by the Landau-Lifshitz-Gilbert equation, can be topologically nontrivial with gapped bulk spin waves and gapless edge spin waves. These edge spin waves are indeed very robust against defects under topological protection. Because of the unidirectional nature of these topologically protected edge spin waves, an interesting functional magnonic device called beam splitter can be made out of a domain wall in a strip. It is shown that an in-coming spin wave beam along one edge splits into two spin wave beams propagating along two opposite directions on the other edge after passing through a domain wall. This work was supported by Hong Kong GRF Grants (Nos. 163011151 and 16301816) and the Grant from NNSF of China (No. 11374249). X.S.W acknowledge support from UESTC.

Coherent and conventional gravidynamic quantum 1/f noise

NASA Astrophysics Data System (ADS)

Handel, Peter H.; George, Thomas F.

2008-04-01

Quantum 1/f noise is a fundamental fluctuation of currents, physical cross sections or process rates, caused by infrared coupling of the current carriers to very low frequency (soft) quanta, also known as infraquanta. The latter are soft gravitons in the gravidynamic case with the coupling constant g= pGM2/Nch considered here -- soft photons in the electrodynamic case and soft transversal piezo-phonons in the lattice-dynamical case. Here p=3.14 and F=psi. Quantum 1/f noise is a new aspect of quantum mechanics expressed mainly through the coherent quantum 1/f effect 2g/pf derived here for large systems, and mainly through the conventional quantum 1/f effect for small systems or individual particles. Both effects are present in general, and their effects are superposed in a first approximation with the help of a coherence (weight) parameter s" that will be derived elsewhere for the gravitational case. The spectral density of fractional fluctuations S(dj/j,f) for j=e(hk/2pm)|F|2 is S(F2,f)/<|F|2> = S(j,f)/2 = [4ps"/(1+s")]GM2/pfNch = 4.4 10E9 M2/(pfNgram2). Here s" = 2N'GM/c2=N'rs, where N' is the number of particles of mass M per unit length of the current, rs their Schwarzschild radius, and s" is our coherence (weight) parameter giving the ratio of coherent to conventional quantum 1/f contributions.

An investigation of automatic exposure control calibration for chest imaging with a computed radiography system

NASA Astrophysics Data System (ADS)

Moore, C. S.; Wood, T. J.; Avery, G.; Balcam, S.; Needler, L.; Beavis, A. W.; Saunderson, J. R.

2014-05-01

The purpose of this study was to examine the use of three physical image quality metrics in the calibration of an automatic exposure control (AEC) device for chest radiography with a computed radiography (CR) imaging system. The metrics assessed were signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR) and mean effective noise equivalent quanta (eNEQm), all measured using a uniform chest phantom. Subsequent calibration curves were derived to ensure each metric was held constant across the tube voltage range. Each curve was assessed for its clinical appropriateness by generating computer simulated chest images with correct detector air kermas for each tube voltage, and grading these against reference images which were reconstructed at detector air kermas correct for the constant detector dose indicator (DDI) curve currently programmed into the AEC device. All simulated chest images contained clinically realistic projected anatomy and anatomical noise and were scored by experienced image evaluators. Constant DDI and CNR curves do not appear to provide optimized performance across the diagnostic energy range. Conversely, constant eNEQm and SNR do appear to provide optimized performance, with the latter being the preferred calibration metric given as it is easier to measure in practice. Medical physicists may use the SNR image quality metric described here when setting up and optimizing AEC devices for chest radiography CR systems with a degree of confidence that resulting clinical image quality will be adequate for the required clinical task. However, this must be done with close cooperation of expert image evaluators, to ensure appropriate levels of detector air kerma.

Electromagnetic information transfer through aqueous system.

PubMed

Foletti, Alberto; Ledda, Mario; Lolli, Maria Grazia; Grimaldi, Settimio; Lisi, Antonella

2017-01-01

Several beneficial effects of the electromagnetic information transfer through aqueous system (EMITTAS) procedure have previously been reported in vitro. The clinical potential of this procedure has also started to be evaluated. Information flow in biological systems can be investigated through chemical and molecular approaches or by a biophysical approach focused on endogenous electrodynamic activities. Electromagnetic signals are endogenously generated at different levels of the biological organization and, likely, play an active role in synchronizing internal cell function or local/systemic adaptive response. Consequently, each adaptive response can be described by its specific electromagnetic pattern and, therefore, correlates with a unique and specific electromagnetic signature. A biophysical procedure synchronously integrating the EMITTAS procedure has already been applied for the treatment of articular pain, low-back pain, neck pain and mobility, fluctuating asymmetry, early-stage chronic kidney disease, refractory gynecological infections, minor anxiety and depression disorders. This clinical strategy involves a single treatment, since the EMITTAS procedure allows the patient to continue his/her own personal treatment at home by means of self-administration of the recorded aqueous system. A significant and long-lasting improvement has been reported, showing a potential beneficial use of this biophysical procedure in the management of common illnesses in an efficient, effective and personalized way. Data from recent studies suggest that aqueous systems may play a key role in providing the basis for recording, storing, transferring and retrieving clinically effective quanta of biological information. These features likely enable to trigger local and systemic self-regulation and self-regeneration potential of the organism.

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

Kim, K. S.; Nakae, L. F.; Prasad, M. K.

Here, we solve a simple theoretical model of time evolving fission chains due to Feynman that generalizes and asymptotically approaches the point model theory. The point model theory has been used to analyze thermal neutron counting data. This extension of the theory underlies fast counting data for both neutrons and gamma rays from metal systems. Fast neutron and gamma-ray counting is now possible using liquid scintillator arrays with nanosecond time resolution. For individual fission chains, the differential equations describing three correlated probability distributions are solved: the time-dependent internal neutron population, accumulation of fissions in time, and accumulation of leaked neutronsmore » in time. Explicit analytic formulas are given for correlated moments of the time evolving chain populations. The equations for random time gate fast neutron and gamma-ray counting distributions, due to randomly initiated chains, are presented. Correlated moment equations are given for both random time gate and triggered time gate counting. There are explicit formulas for all correlated moments are given up to triple order, for all combinations of correlated fast neutrons and gamma rays. The nonlinear differential equations for probabilities for time dependent fission chain populations have a remarkably simple Monte Carlo realization. A Monte Carlo code was developed for this theory and is shown to statistically realize the solutions to the fission chain theory probability distributions. Combined with random initiation of chains and detection of external quanta, the Monte Carlo code generates time tagged data for neutron and gamma-ray counting and from these data the counting distributions.« less

Time Evolving Fission Chain Theory and Fast Neutron and Gamma-Ray Counting Distributions

DOE PAGES

Kim, K. S.; Nakae, L. F.; Prasad, M. K.; ...

2015-11-01

Here, we solve a simple theoretical model of time evolving fission chains due to Feynman that generalizes and asymptotically approaches the point model theory. The point model theory has been used to analyze thermal neutron counting data. This extension of the theory underlies fast counting data for both neutrons and gamma rays from metal systems. Fast neutron and gamma-ray counting is now possible using liquid scintillator arrays with nanosecond time resolution. For individual fission chains, the differential equations describing three correlated probability distributions are solved: the time-dependent internal neutron population, accumulation of fissions in time, and accumulation of leaked neutronsmore » in time. Explicit analytic formulas are given for correlated moments of the time evolving chain populations. The equations for random time gate fast neutron and gamma-ray counting distributions, due to randomly initiated chains, are presented. Correlated moment equations are given for both random time gate and triggered time gate counting. There are explicit formulas for all correlated moments are given up to triple order, for all combinations of correlated fast neutrons and gamma rays. The nonlinear differential equations for probabilities for time dependent fission chain populations have a remarkably simple Monte Carlo realization. A Monte Carlo code was developed for this theory and is shown to statistically realize the solutions to the fission chain theory probability distributions. Combined with random initiation of chains and detection of external quanta, the Monte Carlo code generates time tagged data for neutron and gamma-ray counting and from these data the counting distributions.« less

Phonon counting and intensity interferometry of a nanomechanical resonator

NASA Astrophysics Data System (ADS)

Cohen, Justin D.; Meenehan, Seán M.; Maccabe, Gregory S.; Gröblacher, Simon; Safavi-Naeini, Amir H.; Marsili, Francesco; Shaw, Matthew D.; Painter, Oskar

2015-04-01

In optics, the ability to measure individual quanta of light (photons) enables a great many applications, ranging from dynamic imaging within living organisms to secure quantum communication. Pioneering photon counting experiments, such as the intensity interferometry performed by Hanbury Brown and Twiss to measure the angular width of visible stars, have played a critical role in our understanding of the full quantum nature of light. As with matter at the atomic scale, the laws of quantum mechanics also govern the properties of macroscopic mechanical objects, providing fundamental quantum limits to the sensitivity of mechanical sensors and transducers. Current research in cavity optomechanics seeks to use light to explore the quantum properties of mechanical systems ranging in size from kilogram-mass mirrors to nanoscale membranes, as well as to develop technologies for precision sensing and quantum information processing. Here we use an optical probe and single-photon detection to study the acoustic emission and absorption processes in a silicon nanomechanical resonator, and perform a measurement similar to that used by Hanbury Brown and Twiss to measure correlations in the emitted phonons as the resonator undergoes a parametric instability formally equivalent to that of a laser. Owing to the cavity-enhanced coupling of light with mechanical motion, this effective phonon counting technique has a noise equivalent phonon sensitivity of 0.89 +/- 0.05. With straightforward improvements to this method, a variety of quantum state engineering tasks using mesoscopic mechanical resonators would be enabled, including the generation and heralding of single-phonon Fock states and the quantum entanglement of remote mechanical elements.

Quasiparticle breakdown in a quantum spin liquid.

PubMed

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

2006-03-09

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

Very-high energy gamma-ray astronomy. A 23-year success story in high-energy astroparticle physics

NASA Astrophysics Data System (ADS)

Lorenz, E.; Wagner, R.

2012-08-01

Very-high energy (VHE) gamma quanta contribute only a minuscule fraction - below one per million - to the flux of cosmic rays. Nevertheless, being neutral particles they are currently the best "messengers" of processes from the relativistic/ultra-relativistic Universe because they can be extrapolated back to their origin. The window of VHE gamma rays was opened only in 1989 by the Whipple collaboration, reporting the observation of TeV gamma rays from the Crab nebula. After a slow start, this new field of research is now rapidly expanding with the discovery of more than 150 VHE gamma-ray emitting sources. Progress is intimately related with the steady improvement of detectors and rapidly increasing computing power. We give an overview of the early attempts before and around 1989 and the progress after the pioneering work of the Whipple collaboration. The main focus of this article is on the development of experimental techniques for Earth-bound gamma-ray detectors; consequently, more emphasis is given to those experiments that made an initial breakthrough rather than to the successors which often had and have a similar (sometimes even higher) scientific output as the pioneering experiments. The considered energy threshold is about 30 GeV. At lower energies, observations can presently only be performed with balloon or satellite-borne detectors. Irrespective of the stormy experimental progress, the success story could not have been called a success story without a broad scientific output. Therefore we conclude this article with a summary of the scientific rationales and main results achieved over the last two decades.

Joint experimental-theoretical investigation of the lower bound states of the NO(X2Pi)-Kr complex.

PubMed

Wen, Bo; Meyer, Henning; Kłos, Jacek; Alexander, Millard H

2009-07-02

We describe the first measurement of the near IR spectrum of the NO-Kr van der Waals complex. A variant of IR-REMPI double-resonance spectroscopy is employed in which the IR and UV lasers are scanned simultaneously in such a way that throughout the scan the sum of the two photon energies is kept constant, matching a UV resonance of the system. In the region of the first overtone vibration of the NO monomer, we observe several rotationally resolved bands for the NO-Kr complex. In addition to the origin band located at 3723.046 cm(-1), we observe excited as well as hot bands involving the excitation of one or two quanta of z-axis rotation. Another band is assigned to the excitation of one quantum of bending vibration. The experimental spectra are compared with results of bound-state calculations for a new set of potential energy surfaces calculated at the spin-restricted coupled cluster level. For the average vibration-rotation energies, there is excellent agreement between the theoretical results based on the coupled states (CS) approximation and the full close-coupling (CC) treatment. Finer details like the electrostatic splitting and the P-type doubling of the rotational levels are accounted for only within the CC formalism. The comparison of the CC results with the measured spectra confirms the high quality of the PESs. However, the high resolution of the experiments is sufficient to identify some inaccuracies in the difference between the potential energy surfaces of A' and A'' reflection symmetry.

An approach for quantitative image quality analysis for CT

NASA Astrophysics Data System (ADS)

Rahimi, Amir; Cochran, Joe; Mooney, Doug; Regensburger, Joe

2016-03-01

An objective and standardized approach to assess image quality of Compute Tomography (CT) systems is required in a wide variety of imaging processes to identify CT systems appropriate for a given application. We present an overview of the framework we have developed to help standardize and to objectively assess CT image quality for different models of CT scanners used for security applications. Within this framework, we have developed methods to quantitatively measure metrics that should correlate with feature identification, detection accuracy and precision, and image registration capabilities of CT machines and to identify strengths and weaknesses in different CT imaging technologies in transportation security. To that end we have designed, developed and constructed phantoms that allow for systematic and repeatable measurements of roughly 88 image quality metrics, representing modulation transfer function, noise equivalent quanta, noise power spectra, slice sensitivity profiles, streak artifacts, CT number uniformity, CT number consistency, object length accuracy, CT number path length consistency, and object registration. Furthermore, we have developed a sophisticated MATLAB based image analysis tool kit to analyze CT generated images of phantoms and report these metrics in a format that is standardized across the considered models of CT scanners, allowing for comparative image quality analysis within a CT model or between different CT models. In addition, we have developed a modified sparse principal component analysis (SPCA) method to generate a modified set of PCA components as compared to the standard principal component analysis (PCA) with sparse loadings in conjunction with Hotelling T2 statistical analysis method to compare, qualify, and detect faults in the tested systems.

Nanofiber quantum photonics

NASA Astrophysics Data System (ADS)

Nayak, Kali P.; Sadgrove, Mark; Yalla, Ramachandrarao; Le Kien, Fam; Hakuta, Kohzo

2018-07-01

Recent advances in the coherent control of single quanta of light, photons, is a topic of prime interest, and is discussed under the banner of quantum photonics. In the last decade, the subwavelength diameter waist of a tapered optical fiber, referred to as an optical nanofiber, has opened promising new avenues in the field of quantum optics, paving the way toward a versatile platform for quantum photonics applications. The key feature of the technique is that the optical field can be tightly confined in the transverse direction while propagating over long distances as a guided mode and enabling strong interaction with the surrounding medium in the evanescent region. This feature has led to surprising possibilities to manipulate single atoms and fiber-guided photons, e.g. the efficient channeling of emission from single atoms and solid-state quantum emitters into the fiber-guided modes, high optical depth with a few atoms around the nanofiber, trapping atoms around a nanofiber, and atomic memories for fiber-guided photons. Furthermore, implementing a moderate longitudinal confinement in nanofiber cavities has enabled the strong coupling regime of cavity quantum electrodynamics to be reached, and the long-range dipole–dipole interaction between quantum emitters mediated by the nanofiber offers a platform for quantum nonlinear optics with an ensemble of atoms. In addition, the presence of a longitudinal component of the guided field has led to unique capabilities for chiral light–matter interactions on nanofibers. In this article, we review the key developments of the nanofiber technology toward a vision for quantum photonics on an all-fiber interface.

A comparison of the imaging characteristics of the new Kodak Hyper Speed G film with the current T-MAT G/RA film and the CR 9000 system.

PubMed

Monnin, P; Gutierrez, D; Bulling, S; Lepori, D; Verdun, F R

2005-10-07

Three standard radiation qualities (RQA 3, RQA 5 and RQA 9) and two screens, Kodak Lanex Regular and Insight Skeletal, were used to compare the imaging performance and dose requirements of the new Kodak Hyper Speed G and the current Kodak T-MAT G/RA medical x-ray films. The noise equivalent quanta (NEQ) and detective quantum efficiencies (DQE) of the four screen-film combinations were measured at three gross optical densities and compared with the characteristics for the Kodak CR 9000 system with GP (general purpose) and HR (high resolution) phosphor plates. The new Hyper Speed G film has double the intrinsic sensitivity of the T-MAT G/RA film and a higher contrast in the high optical density range for comparable exposure latitude. By providing both high sensitivity and high spatial resolution, the new film significantly improves the compromise between dose and image quality. As expected, the new film has a higher noise level and a lower signal-to-noise ratio than the standard film, although in the high frequency range this is compensated for by a better resolution, giving better DQE results--especially at high optical density. Both screen-film systems outperform the phosphor plates in terms of MTF and DQE for standard imaging conditions (Regular screen at RQA 5 and RQA 9 beam qualities). At low energy (RQA 3), the CR system has a comparable low-frequency DQE to screen-film systems when used with a fine screen at low and middle optical densities, and a superior low-frequency DQE at high optical density.

A single-atom quantum memory.

PubMed

Specht, Holger P; Nölleke, Christian; Reiserer, Andreas; Uphoff, Manuel; Figueroa, Eden; Ritter, Stephan; Rempe, Gerhard

2011-05-12

The faithful storage of a quantum bit (qubit) of light is essential for long-distance quantum communication, quantum networking and distributed quantum computing. The required optical quantum memory must be able to receive and recreate the photonic qubit; additionally, it must store an unknown quantum state of light better than any classical device. So far, these two requirements have been met only by ensembles of material particles that store the information in collective excitations. Recent developments, however, have paved the way for an approach in which the information exchange occurs between single quanta of light and matter. This single-particle approach allows the material qubit to be addressed, which has fundamental advantages for realistic implementations. First, it enables a heralding mechanism that signals the successful storage of a photon by means of state detection; this can be used to combat inevitable losses and finite efficiencies. Second, it allows for individual qubit manipulations, opening up avenues for in situ processing of the stored quantum information. Here we demonstrate the most fundamental implementation of such a quantum memory, by mapping arbitrary polarization states of light into and out of a single atom trapped inside an optical cavity. The memory performance is tested with weak coherent pulses and analysed using full quantum process tomography. The average fidelity is measured to be 93%, and low decoherence rates result in qubit coherence times exceeding 180  microseconds. This makes our system a versatile quantum node with excellent prospects for applications in optical quantum gates and quantum repeaters.

Optical properties of Si and Ge nanocrystals: Parameter-free calculations

NASA Astrophysics Data System (ADS)

Ramos, L. E.; Weissker, H.-Ch.; Furthmüller, J.; Bechstedt, F.

2005-12-01

The cover picture of the current issue refers to the Edi-tor's Choice article of Ramos et al. [1]. The paper gives an overview of the electronic and optical properties of silicon and germanium nanocrystals determined by state-of-the-art ab initio methods. Nanocrystals have promising applications in opto-electronic devices, since they can be used to confine electrons and holes and facilitate radiative recombination. Since meas-urements for single nanoparticles are difficult to make, ab initio theoretical investigations become important to understand the mechanisms of luminescence.The cover picture shows nanocrystals of four sizes with tetrahedral coordination whose dangling bonds at the surface are passivated with hydrogen. As often observed in experiments, the nanocrystals are not perfectly spherical, but contain facets. Apart from the size of the nanocrystals, which determines the quantum confinement, the way their dangling bonds are passivated is relevant for their electronic and optical properties. For instance, the passivation with hydroxyls reduces the quantum confine-ment. On the other hand, the oxidation of the silicon nanocrys-tals increases the quantum confinement and reduces the effect of single surface terminations on the gap. Due to the oscillator strengths of the lowest-energy optical transitions, Ge nanocrys-tals are in principle more suitable for opto-electronic applica-tions than Si nanocrystals.The first author, Luis E. Ramos, is a postdoc at the Institute of Solid-State Physics and Optics (IFTO), Friedrich-Schiller University Jena, Germany. He investigates electronic and optical properties of semiconductor nanocrystallites and is a member of the European Network of Excellence NANO-QUANTA and of the European Theoretical Spectroscopy Facility (ETSF).

Detector, collimator and real-time reconstructor for a new scanning-beam digital x-ray (SBDX) prototype.

PubMed

Speidel, Michael A; Tomkowiak, Michael T; Raval, Amish N; Dunkerley, David A P; Slagowski, Jordan M; Kahn, Paul; Ku, Jamie; Funk, Tobias

Scanning-beam digital x-ray (SBDX) is an inverse geometry fluoroscopy system for low dose cardiac imaging. The use of a narrow scanned x-ray beam in SBDX reduces detected x-ray scatter and improves dose efficiency, however the tight beam collimation also limits the maximum achievable x-ray fluence. To increase the fluence available for imaging, we have constructed a new SBDX prototype with a wider x-ray beam, larger-area detector, and new real-time image reconstructor. Imaging is performed with a scanning source that generates 40,328 narrow overlapping projections from 71 × 71 focal spot positions for every 1/15 s scan period. A high speed 2-mm thick CdTe photon counting detector was constructed with 320×160 elements and 10.6 cm × 5.3 cm area (full readout every 1.28 μs), providing an 86% increase in area over the previous SBDX prototype. A matching multihole collimator was fabricated from layers of tungsten, brass, and lead, and a multi-GPU reconstructor was assembled to reconstruct the stream of captured detector images into full field-of-view images in real time. Thirty-two tomosynthetic planes spaced by 5 mm plus a multiplane composite image are produced for each scan frame. Noise equivalent quanta on the new SBDX prototype measured 63%-71% higher than the previous prototype. X-ray scatter fraction was 3.9-7.8% when imaging 23.3-32.6 cm acrylic phantoms, versus 2.3-4.2% with the previous prototype. Coronary angiographic imaging at 15 frame/s was successfully performed on the new SBDX prototype, with live display of either a multiplane composite or single plane image.

Dynamics of Photosystem II and Its Light Harvesting System in Response to Light Changes in the Halotolerant Alga Dunaliella salina1

PubMed Central

Pick, Uri; Gounaris, Kleoniki; Barber, James

1987-01-01

A photosystem two (PSII) core complex consisting of five major polypeptides (47, 40, 32, 30, and 10 kilodaltons) and a light harvesting chlorophyll a/b complex (LHC-2) have been isolated from the halotolerant alga Dunaliella salina. The chlorophyll and polypeptide composition of both complexes were compared in illuminated and dark-adapted cultures. Dark adaptation is accompanied by a decrease in the chlorophyll a to chlorophyll b (Chl a/Chl b) ratio of intact thylakoids without any change in total chlorophyll. These changes occur with a half-time of 3 hours and are reversed upon reillumination. Analyses of PSII enriched membrane fragments suggest that the decrease in the Chl a/Chl b is due partly to an increase in the Chl b content of LHC-2 and partly to changes in the relative levels of the two complexes. Apparently during dark adaptation there is: (a) a net synthesis of chlorophyll b, (b) removal of PSII core complexes resulting in a 2-fold drop in the PSII cores to LHC-2 chlorophyll ratio. These changes should dramatically increase the light harvesting capacity of the remaining PSII reaction centers. Presumably this adjustment of antenna size and composition is a physiological mechanism necessary for responding to shade conditions. Also detected, using 32P, are light-induced phosphorylation of the LHC-2 (consistent with the ability to undergo State transitions) and of the 40 and 30 kilodalton subunits of the PSII core complex. These observations indicate that additional mechanisms may also exist to help optimize the interception of quanta during rapid changes in illumination conditions. Images Fig. 4 PMID:16665656

Human development VIII: a theory of "deep" quantum chemistry and cell consciousness: quantum chemistry controls genes and biochemistry to give cells and higher organisms consciousness and complex behavior.

PubMed

Ventegodt, Søren; Hermansen, Tyge Dahl; Flensborg-Madsen, Trine; Nielsen, Maj Lyck; Merrick, Joav

2006-11-14

Deep quantum chemistry is a theory of deeply structured quantum fields carrying the biological information of the cell, making it able to remember, intend, represent the inner and outer world for comparison, understand what it "sees", and make choices on its structure, form, behavior and division. We suggest that deep quantum chemistry gives the cell consciousness and all the qualities and abilities related to consciousness. We use geometric symbolism, which is a pre-mathematical and philosophical approach to problems that cannot yet be handled mathematically. Using Occam's razor we have started with the simplest model that works; we presume this to be a many-dimensional, spiral fractal. We suggest that all the electrons of the large biological molecules' orbitals make one huge "cell-orbital", which is structured according to the spiral fractal nature of quantum fields. Consciousness of single cells, multi cellular structures as e.g. organs, multi-cellular organisms and multi-individual colonies (like ants) and human societies can thus be explained by deep quantum chemistry. When biochemical activity is strictly controlled by the quantum-mechanical super-orbital of the cell, this orbital can deliver energetic quanta as biological information, distributed through many fractal levels of the cell to guide form and behavior of an individual single or a multi-cellular organism. The top level of information is the consciousness of the cell or organism, which controls all the biochemical processes. By this speculative work inspired by Penrose and Hameroff we hope to inspire other researchers to formulate more strict and mathematically correct hypothesis on the complex and coherence nature of matter, life and consciousness.

Human Development VIII: A Theory of “Deep” Quantum Chemistry and Cell Consciousness: Quantum Chemistry Controls Genes and Biochemistry to Give Cells and Higher Organisms Consciousness and Complex Behavior

PubMed Central

Ventegodt, Søren; Hermansen, Tyge Dahl; Flensborg-Madsen, Trine; Nielsen, Maj Lyck; Merrick, Joav

2006-01-01

Deep quantum chemistry is a theory of deeply structured quantum fields carrying the biological information of the cell, making it able to remember, intend, represent the inner and outer world for comparison, understand what it “sees”, and make choices on its structure, form, behavior and division. We suggest that deep quantum chemistry gives the cell consciousness and all the qualities and abilities related to consciousness. We use geometric symbolism, which is a pre-mathematical and philosophical approach to problems that cannot yet be handled mathematically. Using Occams razor we have started with the simplest model that works; we presume this to be a many-dimensional, spiral fractal. We suggest that all the electrons of the large biological molecules orbitals make one huge “cell-orbital”, which is structured according to the spiral fractal nature of quantum fields. Consciousness of single cells, multi cellular structures as e.g. organs, multi-cellular organisms and multi-individual colonies (like ants) and human societies can thus be explained by deep quantum chemistry. When biochemical activity is strictly controlled by the quantum-mechanical super-orbital of the cell, this orbital can deliver energetic quanta as biological information, distributed through many fractal levels of the cell to guide form and behavior of an individual single or a multi-cellular organism. The top level of information is the consciousness of the cell or organism, which controls all the biochemical processes. By this speculative work inspired by Penrose and Hameroff we hope to inspire other researchers to formulate more strict and mathematically correct hypothesis on the complex and coherence nature of matter, life and consciousness. PMID:17115084

Post-illumination Pupil Response in Subjects without Ocular Disease

PubMed Central

Kankipati, Laxmikanth; Girkin, Christopher A.; Gamlin, Paul D.

2010-01-01

Purpose. A sustained pupilloconstriction is often observed after the cessation of a bright visual stimulus. This post-illumination pupil response (PIPR) is produced by the intrinsically photosensitive retinal ganglion cells (ipRGCs). The present study was designed to examine the characteristics of the PIPR in a normal population without ocular disease. Methods. Thirty-seven subjects (mean age, 48.6 years) were tested by presenting a 60°, 10-second light stimulus (13 log quanta/cm2/s retinal irradiance) and recording pupillary responses for 50 seconds after light cessation. The light stimuli (470 [blue] and 623 [red] nm) were presented by an optical system to one eye after dilation, while the consensual pupil response of the fellow, undilated eye was recorded by infrared pupillometry. Results. A positive PIPR was seen in all subjects tested. The population average of the PIPR for 470-nm light was 1.5 mm (SEM 0.10, P < 0.05) and the net PIPR (blue PIPR minus red PIPR) was 1.4 mm (SEM 0.09, P < 0.0001). The net PIPR correlated positively with baseline pupil diameter (P < 0.05), but not significantly with age, race, or sex (P > 0.05) in the test population. Conclusions. All normal subjects displayed a significant PIPR for a 10-second, 470-nm light stimulus, but not a 623-nm stimulus, which is consistent with the proposed melanopsin-mediated response. In most normal individuals, the amplitude of the PIPR was substantial. This test has the potential to be used as a tool in evaluating subjects with inner retinal dysfunction or melanopsin-related disorders. PMID:20007832

Surface topography study of prepared 3D printed moulds via 3D printer for silicone elastomer based nasal prosthesis

NASA Astrophysics Data System (ADS)

Abdullah, Abdul Manaf; Din, Tengku Noor Daimah Tengku; Mohamad, Dasmawati; Rahim, Tuan Noraihan Azila Tuan; Akil, Hazizan Md; Rajion, Zainul Ahmad

2016-12-01

Conventional prosthesis fabrication is highly depends on the hand creativity of laboratory technologist. The development in 3D printing technology offers a great help in fabricating affordable and fast yet esthetically acceptable prostheses. This study was conducted to discover the potential of 3D printed moulds for indirect silicone elastomer based nasal prosthesis fabrication. Moulds were designed using computer aided design (CAD) software (Solidworks, USA) and converted into the standard tessellation language (STL) file. Three moulds with layer thickness of 0.1, 0.2 and 0.3mm were printed utilizing polymer filament based 3D printer (Makerbot Replicator 2X, Makerbot, USA). Another one mould was printed utilizing liquid resin based 3D printer (Objet 30 Scholar, Stratasys, USA) as control. The printed moulds were then used to fabricate maxillofacial silicone specimens (n=10)/mould. Surface profilometer (Surfcom Flex, Accretech, Japan), digital microscope (KH77000, Hirox, USA) and scanning electron microscope (Quanta FEG 450, Fei, USA) were used to measure the surface roughness as well as the topological properties of fabricated silicone. Statistical analysis of One-Way ANOVA was employed to compare the surface roughness of the fabricated silicone elastomer. Result obtained demonstrated significant differences in surface roughness of the fabricated silicone (p<0.01). Further post hoc analysis also revealed significant differences in silicone fabricated using different 3D printed moulds (p<0.01). A 3D printed mould was successfully prepared and characterized. With surface topography that could be enhanced, inexpensive and rapid mould fabrication techniques, polymer filament based 3D printer is potential for indirect silicone elastomer based nasal prosthesis fabrication.