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Sample records for forbidden beta transitions

  1. Meson-Exchange Enhancement of First-Forbidden $\\beta$-Transitions in the Lead Region

    CERN Multimedia

    Delaure, B J P; Severijns, N

    2002-01-01

    Both on-line and off-line low temperature nuclear orientation is used to measure the $\\beta$-asymmetry parameter for the first-forbidden g.s. $\\rightarrow$~g.s. $\\beta$-transitions of $^{205}$Hg, $^{207,209}$Tl, $^{209}$Pb and $^{213}$Bi. From this, the ratio of the rank-zero and the rank-one strengths in these decays can be deduced, with the rank of a $\\beta$-transition being defined as the total angular momentum of the lepton system. Combining this result with the experimental ${ft}$-values yields for the first time a purely experimental determination of the rank-zero contribution in these $\\Delta$ J = 0 first-forbidden transitions. This provides an independent check of the large enhancement (of about 100% over the impulse approximation) of the rank-zero matrix element of $\\gamma_{5} $, caused by meson exchange currents (MEC), which was recently obtained from a comparison of calculated first-forbidden $\\beta$-decay rates with experimentally observed values for nuclei in the lead region (A = 205-212). Measur...

  2. First-forbidden transitions and stellar $\\beta$-decay rates of Zn and Ge isotopes

    CERN Document Server

    Nabi, Jameel-Un; Stoica, Sabin; Iftikhar, Zafar

    2016-01-01

    First-forbidden (FF) charge-changing transitions become relatively important for nuclei as their proton number increases. This is because the strength of allowed Gamow-Teller (GT) transitions decreases with increasing Z. The FF transitions play an important role in reducing the half-lives as against those calculated from taking the GT transitions alone into account. In this paper we calculate allowed GT as well as $0^{+} \\rightarrow 0^{-}$ and $0^{+} \\rightarrow 2^{-}$ transitions for neutron-rich Zn and Ge isotopes. Two different pn-QRPA models were used with a schematic separable interaction to calculate GT and FF transitions. Half-lives calculated after inclusion of FF transitions were in excellent agreement with the experimental data. Our calculations were also compared to previous QRPA calculations and were found to be in better agreement with measured data. Stellar $\\beta$-decay rates were calculated for these nuclei including allowed GT and unique FF transitions for astrophysical applications. $^{86,88...

  3. Study of once and twice forbidden {beta} transitions; Contribution a l'etude de transitions {beta} une fois et deux fois interdites

    Energy Technology Data Exchange (ETDEWEB)

    Hocquenghem, J.C. [Commissariat a l' Energie Atomique, Grenoble (France). Centre d' Etudes Nucleaires

    1967-09-01

    The realisation of an experimental set up for directional angular correlation measurements allowed us to determine {beta} - {gamma} angular correlations. These measurements together with the determination of the {beta} shape-factor have been made for the following transitions: the first forbidden {beta}{sup -} transitions of 386 keV in the {sup 177}Lu disintegration and of 352 keV in the {sup 175}Yb disintegration. The experimental results have been compared with theoretical predictions of the Nilsson's model; the twice forbidden {beta}{sup -} transition of 473 keV in the {sup 94}Nb disintegration. The {beta} transition nuclear matrix elements have been extracted from the experimental results. Comparison have been made with the theoretical values calculated by taking for nuclear wavefunctions those obtained by diagonalization of the residual interaction and assuming that protons and neutrons outside the {sup 90}Zr core are respectively on the 1 g 9/2 and 2 d 5/2 orbits. (author) [French] La realisation d'un ensemble de mesures de correlations angulaires directionnelles nous a permis la mesure de correlations {beta} - {gamma} en fonction de l'energie. En completant celles-ci par la mesure du facteur de forme du spectre {beta}, nous avons pu etudier ainsi: d'une part, les transitions {beta}{sup -} une fois interdites de 386 keV de la desintegration de {sup 177}Lu et de 352 keV de la desintegration de {sup 175}Yb, Les resultats experimentaux ont ete compares aux valeurs calculees dans le modele de Nilsson; d'autre part, la transition {beta}- deux fois interdite de 473 keV de la desintegration de {sup 94}Nb. Les elements de matrice nucleaire de la transition {beta}, extraits des resultats experimentaux, ont ete compares aux valeurs theoriques calculees. Les fonctions d'ondes nucleaires utilisees ont ete obtenues par diagonalisation de l'interaction residuelle en supposant que les protons et les neutrons, en dehors du coeur forme par

  4. Meson-exchange enhancement of the first forbidden $0^{+} \\leftrightarrow 0^{-} \\beta$-transitions

    CERN Multimedia

    2002-01-01

    In the frame of the standard model of the weak interaction, it has been suggested by Kubodera, Delorme and Rho, that pion exchange should have a large effect on the rank-zero time-like component of the axial current A$_{0}$. The best case for the study of A$ _{0}$ is $0^{-} \\leftrightarrow 0^{+} \\beta$-decay since in this process only rank zero matrix elements of the time-like and space-like components of the axial current contribute to the transition rate. $0^{-} \\leftrightarrow 0^{+}$ decays have been studied in the vicinity of doubly closed-shell nuclei such as $^{16}$O, $^{96}$Zr, and $^{208}$Pb where s$_{1/2} \\leftrightarrow$ p$_{1/2}$ matrix elements were involved. In these cases, the meson-exchange correction to the one-body axial-charge density is significant. ISOLDE offers the possibility to perform sensitive measurements of the $0^{-} \\leftrightarrow 0^{+}$ pseudoscalar decay in nuclei where the p$_{3/2} \\rightarrow$ d$_{3/2}$ matrix elements are involved. We therefore propose a search of the $^{38}...

  5. Large scale evaluation of beta-decay rates of r-process nuclei with the inclusion of first-forbidden transitions

    CERN Document Server

    Marketin, T; Martínez-Pinedo, G

    2015-01-01

    R-process nucleosynthesis models rely, by necessity, on nuclear structure models for input. Particularly important are beta-decay half-lives of neutron rich nuclei. At present only a single systematic calculation exists that provides values for all relevant nuclei making it difficult to test the sensitivity of nucleosynthesis models to this input. Additionally, even though there are indications that their contribution may be significant, the impact of first-forbidden transitions on decay rates has not been systematically studied within a consistent model. We use a fully self-consistent covariant density functional theory (CDFT) framework to provide a table of $\\beta$-decay half-lives and $\\beta$-delayed neutron emission probabilities, including first-forbidden transitions. We observe a significant contribution of the first-forbidden transitions to the total decay rate in nuclei far from the valley of stability. The experimental half-lives are in general well reproduced, both for even-even, odd-A and odd-odd n...

  6. Refinement of the gross theory of nuclear {beta}-decay, and hindrance of the first-forbidden transition of rank 1

    Energy Technology Data Exchange (ETDEWEB)

    Nakata, Hidehiko [Waseda Univ., Tokyo (Japan). Dept. of Physics; Tachibana, Takahiro; Yamada, Masami

    1997-03-01

    Recently the gross theory of nuclear {beta}-decay was refined for odd-odd nuclei. In this refinement, the effect of the selection rule of {beta}-transitions from the ground states of odd-odd nuclei to those of even-even nuclei was taken into account based on a statistical consideration. The transitions to the first 2{sup +} excited states in even-even nuclei were also taken into account according to the selection rule approximately. In that study, it was found that the transitions between 1{sup -} ground states of the odd-odd nuclei and 0{sup +} ground states of even-even nuclei, belonging to the first-forbidden transitions of rank 1, are strongly hindered. A reduction factor was introduced for the transitions to the ground states of even-even nuclei to take into account this hindrance. It was also found that the strength functions of the Gamow-Teller transitions obtained from the conventional gross theory are underestimated by a factor of about 3. In order to improve this underestimation, the Lorentz-type function was adopted for the one-particle strength function in the model instead of the hyperbolic-secant-type function. In the present study we have newly analyzed the experimental ft-values of odd-A nuclei, and found that the first-forbidden transitions of rank 1 are also considerably hindered between the ground states. Following the above refinement we have calculated the {beta}-ray spectra of some odd-odd short-lived fission products with the use of the refined gross theory. These results are compared not only with the experiments by Rudstam et al. but also with the conventional gross theory. (author)

  7. Turning Forbidden Transitions into Dominant Transitions

    CERN Document Server

    Rivera, Nicholas; Soljacic, Marin

    2016-01-01

    Surface phonon polaritons are hybrid modes of photons and optical phonons that can propagate on the surface of a polar dielectric. In this work, we show that the precise combination of confinement and bandwidth offered by surface phonon polaritons allows for the ability to take forbidden transitions and turn them into the primary means by which an electron emits light. We show that high-order multipolar transitions and two-photon emission processes can be over an order of magnitude faster than competing dipole transitions, as opposed to being as much as eight to ten orders of magnitude slower in free space. Our results have direct implications for the design of fundamentally new types of emitters in the mid and far IR: ones which prefer to change their angular momentum by large amounts and also ones that prefer to emit a relatively broad spectrum of entangled photons - potentially allowing for new sources of both single and multiple photons.

  8. First forbidden beta decay of some strongly deformed nuclei

    NARCIS (Netherlands)

    Werf, Siebren Ysbrand van der

    1971-01-01

    In this thesis we present measurements of the shape factors of the first forbidden beta decays of the nuclei Tm^170, Re^186, Re^188 and Lu^176m. For Lu^176m, also the beta gamma directionalcorrelation was measured. In chapter I formulas for the observable quantities in first forbidden beta decay and

  9. Doppler cooling and trapping on forbidden transitions.

    Science.gov (United States)

    Binnewies, T; Wilpers, G; Sterr, U; Riehle, F; Helmcke, J; Mehlstäubler, T E; Rasel, E M; Ertmer, W

    2001-09-17

    Ultracold atoms at temperatures close to the recoil limit have been achieved by extending Doppler cooling to forbidden transitions. A cloud of (40)Ca atoms has been cooled and trapped to a temperature as low as 6 microK by operating a magnetooptical trap on the spin-forbidden intercombination transition. Quenching the long-lived excited state with an additional laser enhanced the scattering rate by a factor of 15, while a high selectivity in velocity was preserved. With this method, more than 10% of precooled atoms from a standard magnetooptical trap have been transferred to the ultracold trap. Monte Carlo simulations of the cooling process are in good agreement with the experiments.

  10. Limits on Lorentz Violation from Forbidden beta Decays

    NARCIS (Netherlands)

    Noordmans, J.P.; Wilschut, H.W.; Timmermans, R.G.E.

    2013-01-01

    Forbidden (slow) beta decays offer new opportunities to test the invariance of the weak interaction under Lorentz transformations. Within a general effective field theory framework we analyze and reinterpret the only two relevant experiments, performed in the 1970s, dedicated to search for a

  11. Phase sensitive quantum interference on forbidden transition in ladder scheme

    CERN Document Server

    Koganov, Gennady A

    2014-01-01

    A three level ladder system is analyzed and the coherence of initially electric-dipole forbidden transition is calculated. Due to the presence of two laser fields the initially dipole forbidden transition becomes dynamically permitted due to ac Stark effect. It is shown that such transitions exhibit quantum-interference-related phenomena, such as electromagnetically induced transparency, gain without inversion and enhanced refractive index. Gain and dispersion characteristics of such transitions strongly depend upon the relative phase between the driving and the probe fields. Unlike allowed transitions, gain/absorption behavior of ac-Stark allowed transitions exhibit antisymmetric feature on the Rabi sidebands. It is found that absorption/gain spectra possess extremely narrow sub-natural resonances on these ac Stark allowed forbidden transitions. An interesting finding is simultaneous existence of gain and negative dispersion at Autler-Townes transition which may lead to both reduction of the group velocity a...

  12. Uncovering forbidden optical transitions in PbSe nanocrystals.

    Science.gov (United States)

    Peterson, Jeffrey J; Huang, Libai; Delerue, Christophe; Allan, Guy; Krauss, Todd D

    2007-12-01

    The 1S(h,e)-1P(e,h) exciton transition energy of PbSe nanocrystals was determined via two-photon photoluminescence excitation spectroscopy and was found to be in good agreement with predictions from a tight-binding calculation. The two-photon excitation peak occurs at energies very close to a strong feature in the one-photon absorption spectrum and suggests that it should be assigned as a formally forbidden S-P transition. Leading explanations for the unusual strength of the forbidden transition are discussed.

  13. Collision strengths and transition probabilities for Co III forbidden lines

    Science.gov (United States)

    Storey, P. J.; Sochi, Taha

    2016-07-01

    In this paper we compute the collision strengths and their thermally averaged Maxwellian values for electron transitions between the 15 lowest levels of doubly ionized cobalt, Co2+, which give rise to forbidden emission lines in the visible and infrared region of spectrum. The calculations also include transition probabilities and predicted relative line emissivities. The data are particularly useful for analysing the thermodynamic conditions of supernova ejecta.

  14. Collision strengths and transition probabilities for Co III forbidden lines

    CERN Document Server

    Storey, P J

    2016-01-01

    In this paper we compute the collision strengths and their thermally-averaged Maxwellian values for electron transitions between the fifteen lowest levels of doubly-ionised cobalt, Co^{2+}, which give rise to forbidden emission lines in the visible and infrared region of spectrum. The calculations also include transition probabilities and predicted relative line emissivities. The data are particularly useful for analysing the thermodynamic conditions of supernova ejecta.

  15. Allowed and forbidden transitions in artificial hydrogen and helium atoms.

    Science.gov (United States)

    Fujisawa, Toshimasa; Austing, David Guy; Tokura, Yasuhiro; Hirayama, Yoshiro; Tarucha, Seigo

    2002-09-19

    The strength of radiative transitions in atoms is governed by selection rules that depend on the occupation of atomic orbitals with electrons. Experiments have shown similar electron occupation of the quantized energy levels in semiconductor quantum dots--often described as artificial atoms. But unlike real atoms, the confinement potential of quantum dots is anisotropic, and the electrons can easily couple with phonons of the material. Here we report electrical pump-and-probe experiments that probe the allowed and 'forbidden' transitions between energy levels under phonon emission in quantum dots with one or two electrons (artificial hydrogen and helium atoms). The forbidden transitions are in fact allowed by higher-order processes where electrons flip their spin. We find that the relaxation time is about 200 micro s for forbidden transitions, 4 to 5 orders of magnitude longer than for allowed transitions. This indicates that the spin degree of freedom is well separated from the orbital degree of freedom, and that the total spin in the quantum dots is an excellent quantum number. This is an encouraging result for potential applications of quantum dots as basic entities for spin-based quantum information storage.

  16. Spin-forbidden transitions in flavone.

    Science.gov (United States)

    Marian, Christel M

    2009-07-01

    The ground and low-lying excited electronic states of flavone were investigated by means of quantum chemical methods including spin-orbit coupling. Minimum structures were determined employing (time-dependent) Kohn-Sham density functional theory. Spectral properties were computed utilizing a combined density functional and multi-reference configuration interaction (DFT/MRCI) method. Intersystem crossing (ISC) rate constants for the S1-->T1 transition were computed using a discretized Fermi golden rule approach. For the evaluation of phosphorescence lifetimes a multi-reference spin-orbit configuration interaction procedure (DFT/MRSOCI) was invoked. According to the calculations the phenyl ring is twisted out of the benzopyrone plane by 28 degrees in the electronic ground state whereas the nuclear frame is nearly planar in the lowest excited (npi*)1 (S1) state and is slightly V-shaped in the (pipi*)3 (T1) and (pipi*)1 (S2) states. The calculations clearly show that the T1 state has mainly pipi* character. The large spin-orbit coupling of the S1 and T1 states and their small energy gap explain the high S1-->T1 ISC rate for which a value of kISC approximately 3x10(11) s is computed, in good agreement with experimental build-up times of the Tn<--T1 absorption. In the absence of collisions and other nonradiative processes, the T1 state of flavone is predicted to be long-lived with a pure phosphorescence lifetime of tauP approximately 4 s, in qualitative agreement with low-temperature measurements. The much faster decay of triplet flavone observed in fluid solutions is ascribed to nonradiative processes.

  17. The calculation of vibrational intensities in forbidden electronic transitions.

    Science.gov (United States)

    Johnson, Philip M; Xu, Haifeng; Sears, Trevor J

    2006-10-28

    A method is described for the use of electronic structure and Franck-Condon factor programs in the calculation of the vibrational intensities in forbidden electronic transitions. Using the B 2B2-X 2B1 electronic transition of benzonitrile cation as a test case, transition moments were calculated using the symmetry adapted cluster/configuration interaction method at various points along the normal mode displacements of the molecule, from which transition moment derivatives were obtained. The transition moments were found to vary almost linearly with respect to the normal mode displacements. Using these, along with Franck-Condon factors, an expansion of the transition moment with respect to the normal coordinates provides a measure of vibrational intensities, including the effects of geometry change and Duschinsky rotation [Acta Physicochim. URSS 7, 551 (1937)]. Second order terms in the moment expansion are calculated, and it is determined that they must be included if the intensity of combination bands is to be properly obtained.

  18. Impact of the first-forbidden $\\beta$ decay on the production of $A \\sim 195$ r-process peak

    CERN Document Server

    Nishimura, Nobuya; Fang, Dong-Liang; Suzuki, Toshio

    2016-01-01

    We investigated the effects of first-forbidden transitions in $\\beta$ decays on the production of the r-process $A \\sim 195$ peak. The theoretical calculated $\\beta$-decay rates with $\\beta$-delayed neutron emission were examined using several astrophysical conditions. As the first-borbidden decay is dominant in $N \\sim 126$ neutron-rich nuclei, their inclusion shortens $\\beta$-decay lifetimes and shifts the abundance peak towards higher masses. Additionally, the inclusion of the $\\beta$-delayed neutron emission results in a wider abundance peak, and smoothens the mass distribution by removing the odd-even mass staggering. The effects are commonly seen in the results of all adopted astrophysical models. Nevertheless there are quantitative differences, indicating that remaining uncertainty in the determination of half-lives for $N=126$ nuclei is still significant in order to determine the production of the r-process peak.

  19. Shrinking light to allow forbidden transitions on the atomic scale

    Science.gov (United States)

    Rivera, Nicholas; Kaminer, Ido; Zhen, Bo; Joannopoulos, John D.; Soljačić, Marin

    2016-07-01

    The diversity of light-matter interactions accessible to a system is limited by the small size of an atom relative to the wavelength of the light it emits, as well as by the small value of the fine-structure constant. We developed a general theory of light-matter interactions with two-dimensional systems supporting plasmons. These plasmons effectively make the fine-structure constant larger and bridge the size gap between atom and light. This theory reveals that conventionally forbidden light-matter interactions—such as extremely high-order multipolar transitions, two-plasmon spontaneous emission, and singlet-triplet phosphorescence processes—can occur on very short time scales comparable to those of conventionally fast transitions. Our findings may lead to new platforms for spectroscopy, sensing, and broadband light generation, a potential testing ground for quantum electrodynamics (QED) in the ultrastrong coupling regime, and the ability to take advantage of the full electronic spectrum of an emitter.

  20. The K-Forbidden Beta Decay of Tb160

    DEFF Research Database (Denmark)

    Hansen, P. Gregers; Johnson, N. R.; Nielsen, H. L.

    1964-01-01

    The β decay of the odd nucleus Tb160(Iπ = 3−) is shown to populate the 2+ and 4+ states of the ground-state band of Dy160 in intensities of 0.34% and 0.12%, respectively. The ratio of the reduced transition probabilities and the absolute transition strength are both compared with theoretical...

  1. Study of an Isospin-Forbidden $0^{+} \\rightarrow 0^{+}$ Transition in $^{38m}$K

    CERN Multimedia

    2002-01-01

    There is at present a discrepancy between the precisely determined value of $V_{ud}^{2}$ obtained from $0^{+} \\rightarrow 0^{+} $ nuclear $\\beta$-decay and the less precisely determined value inferred from neutron decay. One possible explanation for this discrepancy involves the " Coulomb " corrections that must be applied to the nuclear decay rates. We propose to investigate one class of these corrections (for charge-dependent configuration-mixing) by measuring the isospin-forbidden $0^{+} \\rightarrow 0^{+}$ decay rate in $^{38m}$K. $^{38m}$K decay is particularly interesting because it is predicted to have the largest charge-dependent mixing correction of any of the transitions used in the $V_{ud}^{2}$ determination.

  2. Effect of layered nanostructures on the linewidth of forbidden E2 transitions

    Science.gov (United States)

    Guzatov, D. V.; Klimov, V. V.

    2017-08-01

    In the framework of classical electrodynamics, analytical expressions are derived and investigated for the linewidth of forbidden E2 transitions in an atom (molecule) located near layered metal – dielectric nanostructures. It is shown that the radiation intensity at the forbidden transition during detection in the halfspace behind a layered nanostructure can significantly exceed the intensity during detection in the half-space where an atom (molecule) is located.

  3. A semiclassical model for the calculation of nonadiabatic transition probabilities for classically forbidden transitions.

    Science.gov (United States)

    Dang, Phuong-Thanh; Herman, Michael F

    2009-02-01

    A semiclassical surface hopping model is presented for the calculation of nonadiabatic transition probabilities for the case in which the avoided crossing point is in the classically forbidden regions. The exact potentials and coupling are replaced with simple functional forms that are fitted to the values, evaluated at the turning point in the classical motion, of the Born-Oppenheimer potentials, the nonadiabatic coupling, and their first few derivatives. For the one-dimensional model considered, reasonably accurate results for transition probabilities are obtained down to around 10(-10). The possible extension of this model to many dimensional problems is discussed. The fact that the model requires only information at the turning point, a point that the trajectories encounter would be a significant advantage in many dimensional problems over Landau-Zener type models, which require information at the avoided crossing seam, which is in the forbidden region where the trajectories do not go.

  4. Analysis of unique beta transitions

    DEFF Research Database (Denmark)

    Eman, B.; Krmpotic, F.; Tadic, D;

    1967-01-01

    The Heidelberg group measurements [For abstr. see Phys. Rev. Nucl. Sci. Vol. 15 (1965)] of unique forbidden transitions have been analysed. It has been found that experimental shape factors can be reproduced only with the induced pseudoscalar form factor d ...-non-conserving tensor form factor b > 0. In the former case they contradict Daniel's results [See abstr. 1966A10720] for 0- rarr 0+ transitions, whereas in the latter they are in disagreement with other known analyses of mu-meson capture, allowed and forbidden transitions. The conclusion appears to be independent...

  5. Pumping of nuclear spins by optical excitation of spin-forbidden transitions in a quantum dot.

    Science.gov (United States)

    Chekhovich, E A; Makhonin, M N; Kavokin, K V; Krysa, A B; Skolnick, M S; Tartakovskii, A I

    2010-02-12

    We demonstrate that efficient optical pumping of nuclear spins in semiconductor quantum dots (QDs) can be achieved by resonant pumping of optically forbidden transitions. This process corresponds to one-to-one conversion of a photon absorbed by the dot into a polarized nuclear spin, and also has potential for initialization of hole spin in QDs. We find that by employing this spin-forbidden process, nuclear polarization of 65% can be achieved, markedly higher than from pumping the allowed transition, which saturates due to the low probability of electron-nuclear spin flip-flop.

  6. Giant modification of atomic transitions probabilities induced by magnetic field: forbidden transitions become predominant

    CERN Document Server

    Sargsyan, A; Hakhumyan, G; Papoyan, A; Mariotti, E; Sarkisyan, D

    2014-01-01

    Magnetic field-induced giant modification of probabilities for seven components of 6S1/2 (Fg=3) - 6P3/2 (Fe=5) transition of Cs D2 line forbidden by selection rules is observed experimentally for the first time. For the case of excitation with circularly-polarized laser radiation, the probability of Fg=3,mF=-3 - Fe=5,mF=-2 transition becomes the largest among 25 transitions of Fg=3 - Fe=2,3,4,5 group in a wide range of magnetic field 200 - 3200 G. Moreover, the modification is the largest among D2 lines of alkali metals. A half-wave-thick cell (length along the beam propagation axis L=426 nm) filled with Cs has been used in order to achieve sub-Doppler resolution which allows for separating the large number of atomic transitions that appear in the absorption spectrum when an external magnetic field is applied. For B > 3 kG the group of seven transitions Fg=3 - Fe=5 is completely resolved and is located at the high frequency wing of Fg=3 - Fe=2,3,4 transitions. The applied theoretical model very well describes...

  7. Forbidden transitions in a magneto-optical trap.

    Science.gov (United States)

    Bhattacharya, M; Haimberger, C; Bigelow, N P

    2003-11-21

    We report the first observation of a nondipole transition in an ultracold atomic vapor. We excite the 3P-4P electric quadrupole (E2) transition in 23Na confined in a magneto-optical trap, and we demonstrate its application to high-resolution spectroscopy by making the first measurement of the hyperfine structure of the 4P(1/2) level and extracting the magnetic dipole constant A=30.6+/-0.1 MHz. We use cw optical-optical double resonance accompanied by photoionization to probe the transition.

  8. Atomic data from the Iron Project. LIII. Relativistic allowed and forbidden transition probabilities for Fe XVII

    CERN Document Server

    Nahar, S N; Chen, G X; Pradhan, A K; Nahar, Sultana N.; Eissner, Werner; Chen, Guo-Xin; Pradhan, Anil K.

    2003-01-01

    An extensive set of fine structure levels and corresponding transition probabilities for allowed and forbidden transitions in Fe XVII is presented. A total of 490 bound energy levels of Fe XVII of total angular momenta 0 <= J <= 7 of even and odd parities with 2 <= n <= 10, 0 <= l <= 8, 0 <= L <= 8, and singlet and triplet multiplicities, are obtained. They translate to over 2.6 x 10^4 allowed (E1) transitions that are of dipole and intercombination type, and about 3000 forbidden transitions that include electric quadrupole (E2), magnetic dipole (M1), electric octopole (E3), and magnetic quadrupole (M2) type representing the most detailed calculations to date for the ion. Oscillator strengths f, line strengths S, and coefficients A of spontaneous emission for the E1 type transitions are obtained in the relativistic Breit-Pauli R-matrix approximation. A valus for the forbidden transitions are obtained from atomic structure calculations using codes SUPERSTRUCTURE and GRASP. The energy le...

  9. Employing Forbidden Transitions as Qubits in a Nuclear Spin-Free Chromium Complex.

    Science.gov (United States)

    Fataftah, Majed S; Zadrozny, Joseph M; Coste, Scott C; Graham, Michael J; Rogers, Dylan M; Freedman, Danna E

    2016-02-01

    The implementation of quantum computation (QC) would revolutionize scientific fields ranging from encryption to quantum simulation. One intuitive candidate for the smallest unit of a quantum computer, a qubit, is electronic spin. A prominent proposal for QC relies on high-spin magnetic molecules, where multiple transitions between the many MS levels are employed as qubits. Yet, over a decade after the original notion, the exploitation of multiple transitions within a single manifold for QC remains unrealized in these high-spin species due to the challenge of accessing forbidden transitions. To create a proof-of-concept system, we synthesized the novel nuclear spin-free complex [Cr(C3S5)3](3-) with precisely tuned zero-field splitting parameters that create two spectroscopically addressable transitions, with one being a forbidden transition. Pulsed electron paramagnetic resonance (EPR) measurements enabled the investigation of the coherent lifetimes (T2) and quantum control (Rabi oscillations) for two transitions, one allowed and one forbidden, within the S = (3)/2 spin manifold. This investigation represents a step forward in the development of high-spin species as a pathway to scalable QC systems within magnetic molecules.

  10. Pseudospin Symmetry and Forbidden Magnetic Dipole and Gamow-Teller Transitions

    Science.gov (United States)

    Ginocchio, Joseph

    1999-10-01

    Recently it has been shown that pseudospin symmetry has its origins in a relativistic symmetry of the Dirac Hamiltonian[1]. Using this symmetry we relate single - nucleon relativistic magnetic moments of states in a pseudospin doublet to the relativistic magnetic dipole transitions between the states in the doublet, and we relate single - nucleon relativistic Gamow - Teller transitions within states in the doublet. We apply these relationships to the Gamow - Teller transitions from ^39Ca to its mirror nucleus ^39K [2] and to the systematics of forbidden magnetic dipole transitions. 1. J. N. Ginocchio and A. Leviatan Phys. Lett. B 425, 1 (1998). 2. J. N. Ginocchio Phys. Rev. C 59, 2487 (1999).

  11. Dynamic Stark effect and forbidden-transition spectrallineshapes

    Energy Technology Data Exchange (ETDEWEB)

    Stalnaker, Jason E.; Budker, D.; Freedman, S.J.; Guzman, J.S.; Rochester, S.M.; Yashchuk, V.V.

    2005-12-15

    We report on an experimental and theoretical study of thedynamic (ac) Stark effect on a for bidden transition. A general frameworkfor parameterizing and describing off-resonant ac-Stark shifts ispresented. A model is developed to calculate spectral line shapesresulting from resonant excitation of atoms in an intense standinglight-wave in the presence of off-resonant ac-Stark shifts. The model isused in the analysis and interpretation of a measurement of the ac-Starkshifts of the static-electric-field-induced 6s2 1S0 -->5d6s 3D1transition at 408 nm in atomic Yb. The results are in agreement withestimates of the ac-Stark shift of the transition under the assumptionthat the shift is dominated by that of the 6s2 1S0 ground state. Adetailed description of the experiment and analysis is presented. Abi-product of this work is an ind ependent determination (from thesaturation behavior of the 408-nm transition) of the Stark transitionpolarizability, which is found to be in agreement with our earliermeasurement. This work is part of the ongoing effort aimed at a precisionmeasurement of atomic parity-violation effects in Yb.

  12. Beta spectrum of unique first-forbidden decays as a novel test for fundamental symmetries

    CERN Document Server

    Glick-Magid, Ayala; Mukul, Ish; Hass, Michael; Ron, Guy; Vaintraub, Sergey; Gazit, Doron

    2016-01-01

    Within the Standard Model, the weak interaction of quarks and leptons is characterized by certain symmetry properties, such as maximal breaking of parity and favored helicity. These are related to the $V-A$ structure of the weak interaction. These characteristics were discovered by studying correlations in the directions of the outgoing leptons in nuclear beta decays. These days, correlation measurements in nuclear beta decays are intensively studied to probe for signatures for deviations from these symmetries, which are an indication of Beyond Standard Model physics. We show that the structure of the energy spectrum of emitted electrons in unique first-forbidden $\\beta$-decays is sensitive to the symmetries of the weak interaction, and thus can be used as a novel probe of physics beyond the standard model. Furthermore, the energy spectrum gives constraints both in the case of right and left coupling of the new symmetry currents. We show that a measurement with modest energy resolution of about 20 keV is expe...

  13. Forbidden Vibrational Transitions in Cold Molecular Ions: Experimental Observation and Potential Applications.

    Science.gov (United States)

    Germann, Matthias; Tonga, Xin; Willitsch, Stefan

    2015-01-01

    A range of interesting fundamental scientific questions can be addressed by high-precision molecular spectroscopy. A promising way towards this goal is the measurement of dipole-forbidden vibrational transitions in molecular ions. We have recently reported the first such observation in a molecular ion. Here, we give an overview of our method and our results as well as an outlook on potential future applications.

  14. Strong Coupling on a Forbidden Transition in Strontium and Nondestructive Atom Counting

    CERN Document Server

    Norcia, Matthew A

    2015-01-01

    We observe strong collective coupling between an optical cavity and the forbidden spin singlet to triplet optical transition $^1$S$_0$ to $^3$P$_1$ in an ensemble of $^{88}$Sr. Despite the transition being 1000 times weaker than a typical dipole transition, we observe a well resolved vacuum Rabi splitting. We use the observed vacuum Rabi splitting to make non-destructive measurements of atomic population with the equivalent of projection-noise limited sensitivity and minimal heating ($<0.01$ photon recoils/atom). This technique may be used to enhance the performance of optical lattice clocks by generating entangled states and reducing dead time.

  15. Effect of a dimer of nanoparticles on the linewidth of forbidden E2 transitions

    Science.gov (United States)

    Guzatov, D. V.; Klimov, V. V.

    2016-07-01

    In the framework of classical electrodynamics we have obtained and investigated analytical expressions for the radiation linewidth of forbidden E2 transitions in an atom located near a dimer of spherical particles. It is shown that the material of particles, their location and size have a significant effect on the linewidth of the E2 transition in the atom. It is found that in the gap between metal spherical nanoparticles, the linewidth of E2 transitions in the atom can take on substantially larger values than in the case of an atom near a single metal nanoparticle.

  16. First-forbidden $\\mathbf{\\beta}$-decay rates, energy rates of $\\beta$-delayed neutrons and probability of $\\beta$-delayed neutron emissions for neutron-rich nickel isotopes

    CERN Document Server

    Nabi, Jameel-Un; Iftikhar, Zafar

    2016-01-01

    First-forbidden (FF) transitions can play an important role in decreasing the calculated half-lives specially in environments where allowed Gamow-Teller (GT) transitions are unfavored. Of special mention is the case of neutron-rich nuclei where, due to phase-space amplification, FF transitions are much favored. We calculate the allowed GT transitions in various pn-QRPA models for even-even neutron-rich isotopes of nickel. Here we also study the effect of deformation on the calculated GT strengths. The FF transitions for even-even neutron-rich isotopes of nickel are calculated assuming the nuclei to be spherical. Later we take into account deformation of nuclei and calculate GT + unique FF transitions, stellar $\\beta$-decay rates, energy rate of $\\beta$-delayed neutrons and probability of $\\beta$-delayed neutron emissions. The calculated half-lives are in excellent agreement with measured ones and might contribute in speeding-up of the $r$-matter flow.

  17. Investigation of forbidden transitions in argon ions. [in laboratory plasma for solar corona simulation

    Science.gov (United States)

    Jalufka, N. W.

    1976-01-01

    An attempt has been made to observe the visible forbidden argon coronal lines at 553.6 nm (Ar X), 691.7 nm (Ar XI), 847.6 nm (Ar XIII), and 441.2 nm (Ar XIV) in a deuterium-argon plasma produced in a large theta pinch. The electron temperature (250 eV) and the electron density (5 by 10 to the 16th power per cu cm) were measured by Thomson scattering of ruby laser radiation. This temperature is adequate to produce ionization stages up to Ar XIV, as was verified by photographic observation of Ar XIV lines. No line corresponding to the coronal lines was observed from the high-temperature plasma, but lines with wavelengths very nearly identical to those of two of the forbidden transitions were observed; these lines were due to allowed transitions of Ar II in a cooler portion of the plasma. Calculation of rate coefficients in the Coulomb-Born approximation shows that for laboratory experiments, electron collisions are much more important than radiative decay in depopulating the upper state of the forbidden lines.

  18. Theoretical investigation on dye sensitizer solar cell: Spin-forbidden transition

    Energy Technology Data Exchange (ETDEWEB)

    Imamura, Yutaka [RIKEN, Advanced Institute for Computational Science, 7-1-26, Minatojima-minami-machi, Chuo-ku, Kobe, Hyogo 650-0047RIKEN (Japan)

    2015-12-31

    We studied spin-forbidden transitions of metal polypyridyl sensitizers by two-component relativistic time-dependent density functional theory with the spin-orbit interaction based on Tamm-Dancoff approximation. The singlet-to-triplet transition, which is assigned to a metal-to-ligand charge-transfer type excitation, appears for a phosphine-coordinated Ru(II), DX1. Absorption spectra of the modified DX1 molecules, whose Ru is replaced with Fe and Os, were also calculated for examining the effects of metals on the spin-orbit interaction.

  19. Forbidden M1 and E2 transitions in monovalent atoms and ions

    CERN Document Server

    Safronova, U I; Johnson, W R

    2016-01-01

    We carried out a systematic high-precision relativistic study of the forbidden magnetic-dipole and electric-quadrupole transitions in Ca+, Rb, Sr+, Cs, Ba+, Fr, Ra+, Ac2+, and Th3+. This work is motivated by the importance of these transitions for tests of fundamental physics and precision measurements. The relative importance of the relativistic, correlation, Breit correction, and contributions of negative-energy states is investigated. Recommended values of reduced matrix elements are presented together with their uncertainties. The matrix elements and resulting lifetimes are compared with other theoretical values and with experiment where available.

  20. Intensity of d-d symmetry-forbidden electronic transition in Cr(CO)6.

    Science.gov (United States)

    Rocha, Alexandre B

    2007-05-31

    Absolute absorption intensities (oscillator strengths) are calculated for the d-d symmetry-forbidden transition in hexacarbonyl chromium. The vibronic coupling mechanism is taken into account in a way that represents an alternative to the traditional perturbative approach of Herzberg and Teller. In the so-called direct method, the electronic transition moment is directly expanded in a power series of the vibrational normal coordinates of suitable symmetry. In the present case, i.e., d-d ligand field transitions, or more specifically (1)A(1g) --> (1)T(1g) and (1)A(1g) --> (1)T(2g) transitions, the dipole selection rule is broken by vibronic interaction induced by normal modes that transform like T(1u) and T(2u) representations of the O(h) group. An analysis of the relative importance of normal modes in promoting electronic transitions is carried out.

  1. Forbidden atomic transitions driven by an intensity-modulated laser trap.

    Science.gov (United States)

    Moore, Kaitlin R; Anderson, Sarah E; Raithel, Georg

    2015-01-20

    Spectroscopy is an essential tool in understanding and manipulating quantum systems, such as atoms and molecules. The model describing spectroscopy includes the multipole-field interaction, which leads to established spectroscopic selection rules, and an interaction that is quadratic in the field, which is not often employed. However, spectroscopy using the quadratic (ponderomotive) interaction promises two significant advantages over spectroscopy using the multipole-field interaction: flexible transition rules and vastly improved spatial addressability of the quantum system. Here we demonstrate ponderomotive spectroscopy by using optical-lattice-trapped Rydberg atoms, pulsating the lattice light and driving a microwave atomic transition that would otherwise be forbidden by established spectroscopic selection rules. This ability to measure frequencies of previously inaccessible transitions makes possible improved determinations of atomic characteristics and constants underlying physics. The spatial resolution of ponderomotive spectroscopy is orders of magnitude better than the transition frequency would suggest, promising single-site addressability in dense particle arrays for quantum computing applications.

  2. Electron Impact Excitation of Forbidden and Allowed Transitions in O(II)

    Science.gov (United States)

    Tayal, S. S.

    2006-01-01

    The B-spline R-matrix method is used to investigate the electron impact excitation of forbidden and allowed transitions in singly ionized oxygen. The relativistic effects have been incorporated in the Breit-Pauli Hamiltonian. Flexible non-orthogonal sets of radial functions are used to obtain accurate target description and to represent the scattering functions. The 47 fine-structure levels of the 2s(sup 2)2p(sup 3), 2s2p(sup 4), 2s(sup 2)2p(sup 2)3s, 2s(sup 2)2p(sup 2)3p and 2s(sup 2)2p(sup 2)3d configurations have been included in the scattering calculation. A calculation with 62 levels in the close-coupling expansion using the Breit-Pauli R-matrix (BPRM) method with orthogonal radial functions has also been carried out to check electron correlation, relativistic and channel coupling effects. The present results are in good agreement with the previous 16-level BPRM calculation by Montenegro et a1 (2006 J. Phys. B: At. Mol. Opt. Phys. 39 1863-77) for the forbidden transitions, but differ from the 21-level BPRM calculation by McLaughlin and Bell (1998 J. Phys. B: At. Mol. Opt. Phys. 31 4317-29). Our cross sections for the first forbidden (sup 4)S(sup o)-(sup 2)D(sup o)and resonance (sup 4)S(sup o)-2s(sup 2)p(sup 4) (sup 4)P transitions are in reasonably good agreement with the electron energy-loss and merged-beams experiment.

  3. Theory of optically forbidden d-d transitions in strongly correlated crystals.

    Science.gov (United States)

    Katsnelson, M I; Lichtenstein, A I

    2010-09-29

    A general multiband formulation of the linear and nonlinear optical response functions for realistic models of correlated crystals is presented. Dipole-forbidden d-d optical transitions originate from vertex functions, which we consider assuming the locality of an irreducible four-leg vertex. The unified formulation for second- and third-order response functions in terms of the three-leg vertex is suitable for practical calculations in solids. We illustrate the general approach by consideration of intra-atomic spin-flip contributions, with an energy of 2J, where J is a Hund exchange, in the simplest two-orbital model.

  4. Direct observation of spin-forbidden transitions through the use of suitably polarized light.

    Science.gov (United States)

    Lévêque, Camille; Peláez, Daniel; Köppel, Horst; Taïeb, Richard

    2014-06-13

    The study of excited triplet states of a molecular system is a difficult task because accessing them involves forbidden transitions from the singlet ground state. Nevertheless, absorption spectra of many molecules present, at low energies, the weak fingerprint of these triplet states. At higher energies this information is usually masked by the intense signal of the singlet states. Here we show, for the specific case of the sulphur dioxide molecule, that the combined use of polarized light and molecular alignment can enhance the triplet part of the spectrum, even making it the only absorption process.

  5. Observation of forbidden exciton transitions mediated by Coulomb interactions in photoexcited semiconductor quantum wells.

    Science.gov (United States)

    Rice, W D; Kono, J; Zybell, S; Winnerl, S; Bhattacharyya, J; Schneider, H; Helm, M; Ewers, B; Chernikov, A; Koch, M; Chatterjee, S; Khitrova, G; Gibbs, H M; Schneebeli, L; Breddermann, B; Kira, M; Koch, S W

    2013-03-29

    We use terahertz pulses to induce resonant transitions between the eigenstates of optically generated exciton populations in a high-quality semiconductor quantum well sample. Monitoring the excitonic photoluminescence, we observe transient quenching of the 1s exciton emission, which we attribute to the terahertz-induced 1s-to-2p excitation. Simultaneously, a pronounced enhancement of the 2s exciton emission is observed, despite the 1s-to-2s transition being dipole forbidden. A microscopic many-body theory explains the experimental observations as a Coulomb-scattering mixing of the 2s and 2p states, yielding an effective terahertz transition between the 1s and 2s populations.

  6. Forbidden atomic transitions driven by an intensity-modulated laser trap

    CERN Document Server

    Moore, Kaitlin R; Raithel, Georg

    2014-01-01

    Spectroscopy is an essential tool in understanding and manipulating quantum systems, such as atoms and molecules. The model describing spectroscopy includes a multipole-field interaction, which leads to established spectroscopic selection rules, and an interaction that is quadratic in the field, which is often neglected. However, spectroscopy using the quadratic (ponderomotive) interaction promises two significant advantages over spectroscopy using the multipole-field interaction: flexible transition rules and vastly improved spatial addressability of the quantum system. For the first time, we demonstrate ponderomotive spectroscopy by using optical-lattice-trapped Rydberg atoms, pulsating the lattice light at a microwave frequency, and driving a microwave atomic transition that would otherwise be forbidden by established spectroscopic selection rules. This new ability to measure frequencies of previously inaccessible transitions makes possible improved determinations of atomic characteristics and constants un...

  7. Ab initio studies on the spin-forbidden cooling transitions of the LiRb molecule.

    Science.gov (United States)

    You, Yang; Yang, Chuan-Lu; Zhang, Qing-Qing; Wang, Mei-Shan; Ma, Xiao-Guang; Liu, Wen-Wang

    2016-07-20

    The spin-forbidden cooling of the LiRb molecule is investigated based on ab initio quantum chemistry calculations. The multireference configuration interaction method is used to generate the potential energy curves (PECs) of the ground state X(1)Σ(+) and the low-lying excited states a(3)Σ(+), B(1)Π, and b(3)Π. The spin-orbit coupling effects for the PECs and the transition dipole moments (TDMs) between the X(1)Σ(+), b(3)Π and a(3)Σ(+) states are also calculated. The analytical functions for the PECs are deduced. The rovibrational energy levels, the spectroscopic parameters and the Franck-Condon factors (FCF) are determined by solving the Schrödinger equation of nuclear movement with the obtained analytical functions. The b(3)Π0 ↔ X(1)Σ(+) and b(3)Π1 ↔ X(1)Σ(+) transitions have highly diagonal distributed FCFs and non-zero TDMs, demonstrating that the LiRb molecule could be a very promising candidate for laser cooling. Therefore, a three-cycle laser cooling scheme for the molecule has been proposed based on these two spin-forbidden transitions. Using the radiative lifetime and linewidth calculated from the obtained TDM functions, we present further analysis of the cooling of LiRb and the corresponding KRb molecule. The transition b(3)Π0 ↔ X(1)Σ(+) is found to be a practical transition to cool the LiRb molecule, and a sub-microkelvin cool temperature could be reached for the KRb molecule using a similar laser cooling scheme.

  8. Theoretical investigation on spin-forbidden cooling transitions of gallium hydride.

    Science.gov (United States)

    Zhang, Yun-Guang; Zhang, Hua; Song, Hai-Yang; Yu, You; Wan, Ming-Jie

    2017-09-20

    Herein, the spin-forbidden cooling of a gallium hydride molecule is investigated using ab initio quantum chemistry. The cooling transition and the corresponding potential energy curves including , a(3)Π0(-), a(3)Π0(+), a(3)Π1, a(3)Π2, A(1)Π1, , 1(3)Σ, , , and 2(3)Σ states are simulated based on the multi-reference configuration interaction approach plus Davidson corrections method. By solving the nuclear Schrödinger equation, we calculate the spectroscopic constants of these states, which are in good agreement with the available experimental values. Based on the transition data, there seems to be a theoretical puzzle: highly diagonally distributed Franck-Condon factor f00 for transitions , , and for the gallium hydride molecule but the intervening state A(1)Π1 for transition is prohibitive to laser cooling. In addition, the transition does not have a suitable rate of optical cycling owing to a large radiative lifetime for state. Our theoretical simulation indicates the solution to the puzzle: the transition has a high emission rate, and there is a suitable radiative lifetime for a(3)Π1 state, which can ensure rapid and efficient laser cooling of gallium hydride. The proposed laser drives transition by using three wavelengths (main pump laser λ00; two repumping lasers λ10 and λ21). These results demonstrate the possibility of laser-cooling the gallium hydride molecule, and a sub-microkelvin cool temperature can be reached for this molecule.

  9. Laser spectroscopy on forbidden transitions in trapped highly charged Ar(13+) ions.

    Science.gov (United States)

    Mäckel, V; Klawitter, R; Brenner, G; Crespo López-Urrutia, J R; Ullrich, J

    2011-09-30

    We demonstrate resonant fluorescence laser spectroscopy in highly charged ions (HCI) stored in an electron beam ion trap by investigating the dipole-forbidden 1s(2)2s(2)2p (2)P(3/2)-(2)P(1/2) transition in boronlike Ar(13+) ions. Forced evaporative cooling yielded a high resolving power, resulting in an accurate wavelength determination to λ=441.255 68(26)  nm. By applying stronger cooling and two-photon excitation, new optical frequency standards based upon ultrastable transitions in such HCI could be realized in the future, e.g., for the search of time variations of the fine-structure constant.

  10. Photopolymer material sensitized by xanthene dyes for holographic recording using forbidden singlet-triplet electronic transitions

    Science.gov (United States)

    Shelkovnikov, Vladimir; Vasiljev, Evgeny; Russkih, Vladimlen; Berezhnaya, Viktoria

    2016-07-01

    A new holographic photopolymer material is developed. The photopolymer material is sensitized by dyes of xanthene and thioxanthene series which contain iodine and bromine heavy atoms. Holographic recording was carried out during excitation of forbidden singlet-triplet electron transitions of dyes. Thioerythrosin triethylammonium was identified as the most effective sensitizer among a number of tested dyes. The spectral absorption area of the singlet-triplet electronic transition of the dye is conveyed in the red spectral range from 600 to 700 nm. The sensitivity of the photopolymer material to radiation with 633 nm wavelength is 180 mJ cm-2. Optimization of concentration of the main components of the photopolymer compositions was carried out in order to achieve maximum efficiency of holographic recording.

  11. Transition Probabilities for the 1815 and 3344 Å Forbidden Lines of Ne iii.

    Science.gov (United States)

    Daw; Parkinson; Smith; Calamai

    2000-04-20

    We have measured the radiative lifetime of the 2s22p4 1S0 metastable level of Ne2+ (Ne iii) to be 223+/-11 ms at the 90% confidence level by observing the photons emitted at 1815 Å by a decaying population of 1S0 Ne2+ ions produced and stored in a radio-frequency ion trap. This is the first lifetime measurement for an excited term of a ground configuration ion in the second row of the periodic table. The transition probabilities (A-values) for the forbidden transitions in the ground configurations of these ions are required for astrophysical line-ratio diagnostics. Using calculated branching ratios, we estimate that A&parl0;lambda1815&parr0;=1.94+/-0.17 and A&parl0;lambda3344&parr0;=2.55+/-0.19 s-1. Because these numbers have a sum with an experimentally determined uncertainty of 5%, they will provide more accurate results than the calculated A-values for determining electron temperature and density from astrophysical Ne iii line ratios.

  12. Forbidden Transition Induced by the Electrostatic Field%静电场诱发禁戒的跃迁

    Institute of Scientific and Technical Information of China (English)

    杨宁选; 杨坤; 范婷

    2016-01-01

    Base on the 《Theoretical study on sym metry of the Stark effect of Hydrogen atom》work , We discusses the hydrogen atomic electrostatic field induced forbidden transition 2s → 1s transition probability .Due to the superposition of States , the forbidden transitions are realization ,which cannot be achieved in the general approximation ,in under the action of electrostatic field .In this case ,the forbidden transition 2s → 1s the transition probability and 2p → 1s the transition probability is proportional to .%在文献[1]工作的基础上,讨论了氢原子静电场诱发的禁戒跃迁2s →1s 的跃迁几率,发现在静电场的作用下,由于态的叠加,实现了在一般近似下不可能实现的禁戒跃迁,且在这种情况下,禁戒跃迁2s →1s 的跃迁几率与2p →1s 的跃迁几率成正比。

  13. Forbidden transition probabilities for ground terms of ions with p or p5 configurations. [for solar atmosphere

    Science.gov (United States)

    Kastner, S. O.

    1976-01-01

    Forbidden transition probabilities are given for ground term transitions of ions in the isoelectronic sequences with outer configurations 2s2 2p (B I), 2p5 (F I), 3s2 3p (Al I), and 3p5 (Cl I). Tables give, for each ion, the ground term interval, the associated wavelength, the quadrupole radial integral, the electric quadrupole transition probability, and the magnetic dipole transition probability. Coronal lines due to some of these ions have been observed, while others are yet to be observed. The tales for the Al I and Cl I sequences include elements up to germanium.

  14. Communication: Proper treatment of classically forbidden electronic transitions significantly improves detailed balance in surface hopping.

    Science.gov (United States)

    Sifain, Andrew E; Wang, Linjun; Prezhdo, Oleg V

    2016-06-01

    Surface hopping is the most popular method for nonadiabatic molecular dynamics. Many have reported that it does not rigorously attain detailed balance at thermal equilibrium, but does so approximately. We show that convergence to the Boltzmann populations is significantly improved when the nuclear velocity is reversed after a classically forbidden hop. The proposed prescription significantly reduces the total number of classically forbidden hops encountered along a trajectory, suggesting that some randomization in nuclear velocity is needed when classically forbidden hops constitute a large fraction of attempted hops. Our results are verified computationally using two- and three-level quantum subsystems, coupled to a classical bath undergoing Langevin dynamics.

  15. Optically Forbidden Transition of A'3△u←X3Σ-g in Oxygen

    Institute of Scientific and Technical Information of China (English)

    ZHU Lin-Fan; XU Wei-Qing; SUN Jian-Min; ZHANG Wen-Yao

    2010-01-01

    @@ The electron energy loss spectra for the valence-shell excitations of oxygen are measured at an incident electron energy of 2500 eV and at scattering angles from 4°to 8.5°.The dipole-forbidden and octupole-allowed transition of the A'3△u←X3Σ-g is observed from the measured spectra,and it is found that the peak profile of the A'3△u←X3Σ-g excitation can be well represented by a Gaussin function.The energy position of 6.007±0.008 eV and Franck-Condon linewidth of 1.312±0.020 eV of the A△u←X3Σ-g,which are independent of the scattering condition,have been determined for the first time.The peak profiles of the A'3△u←X3Σ-g determined in this work provide a possibility to realize the spectral decomposition method of unfolding the Herzberg pseudocontinuum proposed by Campbell et al.[Phys.Rev.A 61 (2000) 022706

  16. Unique first-forbidden β-decay transitions in odd-odd and even-even heavy nuclei

    Science.gov (United States)

    Nabi, Jameel-Un; Çakmak, Necla; Majid, Muhammad; Selam, Cevad

    2017-01-01

    The allowed Gamow-Teller (GT) transitions are the most common weak nuclear processes of spin-isospin (στ) type. These transitions play a key role in numerous processes in the domain of nuclear physics. Equally important is their contribution in astrophysics, particularly in nuclear synthesis and supernova-explosions. In situations where allowed GT transitions are not favored, first-forbidden transitions become significant, specifically in medium heavy and heavy nuclei. For neutron-rich nuclei, first-forbidden transitions are favored mainly due to the phase-space amplification for these transitions. In this work we calculate the allowed GT as well as unique first-forbidden (U1F) | ΔJ | = 2 transitions strength in odd-odd and even-even nuclei in mass range 70 ≤ A ≤ 214. Two different pn-QRPA models were used with a schematic separable interaction to calculate GT and U1F transitions. The inclusion of U1F strength improved the overall comparison of calculated terrestrial β-decay half-lives in both models. The ft values and reduced transition probabilities for the 2- ⟷0+ transitions were also calculated. We compared our calculations with the previously reported correlated RPA calculation and experimental results. Our calculations are in better agreement with measured data. For stellar applications we further calculated the allowed GT and U1F weak rates. These include β±-decay rates and electron/positron capture rates of heavy nuclei in stellar matter. Our study shows that positron and electron capture rates command the total weak rates of these heavy nuclei at high stellar temperatures.

  17. Theoretical study on spin-forbidden transitions of osmium complexes by two-component relativistic time-dependent density functional theory

    Science.gov (United States)

    Imamura, Yutaka; Kamiya, Muneaki; Nakajima, Takahito

    2016-03-01

    We study spin-forbidden transitions of Os polypyridyl sensitizers by two-component relativistic time-dependent density functional theory with the spin-orbit interaction based on Tamm-Dancoff approximation. The absorption spectra, including spin-forbidden-transition peaks, for the Os complexes are reasonably reproduced in comparison with the experimental ones. The extension of the conjugated lengths in the Os complexes is investigated and found to be effective to enhance photo absorption for spin-allowed transitions as well as spin-forbidden ones. This study provides fruitful information for a design of new dyes in terms of conjugation lengths.

  18. The FERRUM Project: experimental and theoretical transition rates of forbidden [Sc II] lines and radiative lifetimes of metastable Sc II levels

    CERN Document Server

    Hartman, H; Lundin, P; Schef, P; Hibbert, A; Lundberg, H; Mannervik, S; Norlin, L -O; Royen, P

    2008-01-01

    Context. In many plasmas, long-lived metastable atomic levels are depopulated by collisions (quenched) before they decay radiatively. In low-density regions, however, the low collision rate may allow depopulation by electric dipole (E1) forbidden radiative transitions, so-called forbidden lines (mainly M1 and E2 transitions). If the atomic transition data are known, these lines are indicators of physical plasma conditions and used for abundance determination. Aims. Transition rates can be derived by combining relative intensities between the decay channels, so-called branching fractions (BFs), and the radiative lifetime of the common upper level. We use this approach for forbidden [Sc ii] lines, along with new calculations. Methods. Neither BFs for forbidden lines, nor lifetimes of metastable levels, are easily measured in a laboratory. Therefore, astrophysical BFs measured in Space Telescope Imaging Spectrograph (STIS) spectra of the strontium filament of Eta Carinae are combined with lifetime measurements u...

  19. Forbidden 2 P- nP and 2 P- nF transitions in the energy spectrum of ultracold Rydberg lithium-7 atoms

    Science.gov (United States)

    Zelener, B. B.; Saakyan, S. A.; Sautenkov, V. A.; Manykin, E. A.; Zelener, B. V.; Fortov, V. E.

    2016-04-01

    Forbidden 2 P- nP and 2 P- nF transitions in the ranges of the principal quantum number n = 42-114 and n = 38-48 have been detected in the optical spectra of ultracold highly excited lithium-7 atoms. The presence of forbidden transitions is due to induced external electric fields. The quantum defects and ionization energy obtained in various experiments and predicted theoretically have been discussed.

  20. Stark profiles of forbidden and allowed transitions in a dense, laser produced helium plasma.

    Science.gov (United States)

    Ya'akobi, B.; George, E. V.; Bekefi, G.; Hawryluk, R. J.

    1972-01-01

    Comparisons of experimental and theoretical Stark profiles of the allowed 2(1)P-3(1)D helium line at 6678 A and of the forbidden 2(1)P-3(1)P component at 6632 A in a dense plasma were carried out. The plasma was produced by optical breakdown of helium by means of a repetitive, high power CO2 laser. The allowed line shows good agreement with conventional theory, but discrepancies are found around the centre of the forbidden component. When normally neglected ion motions are taken into consideration, the observed discrepancies are partially removed. Tables of the Stark profiles for the pair of lines are given.

  1. Measurement of electric fields in a helium micro-hollow cathode discharge by forbidden transitions

    Science.gov (United States)

    Namba, Shinichi; Maki, Daisuke; Takiyama, Ken

    2013-09-01

    Micro-hollow cathode discharges operated at high pressure has been attracting a great deal of interest for various application, such as, excimer light sources, medical/biological fields and microchemical reactor. In the plasmas, the electric (E) field in the sheath region plays an important role to generate and sustain the plasmas. In order to determine the E field in the He microplasma, the emissions of allowed (He I 2P-4D: 492.19 nm) and forbidden (2P-4F: 492.06 nm) lines were observed. The cathode and anode were both made of brass, and ceramic disks were used to electrically insulate the electrodes. The cathode disk had inner hole diameter of 1.0 mm (length: 2.0 mm). The gas with a flow rate was 1.0 L/min. The discharge was operated at voltages of 250 V, currents of 8 mA and gas pressures up to 100 kPa. The plasmas in the cathode opening were observed using a visible spectrometer. The forbidden line associated with the level mixing of upper levels was observed in the cathode surface, indicating that the high E field was formed. As the intensity ratio of forbidden to the allowed lines is a function of the E field which is calculated by perturtabation theory, we derived the field strength of 18 kV/cm at 1.0 mm cathode surface.

  2. Oscillator strength of symmetry-forbidden d-d absorption of octahedral transition metal complex: theoretical evaluation.

    Science.gov (United States)

    Saito, Ken; Eishiro, Yoshinori; Nakao, Yoshihide; Sato, Hirofumi; Sakaki, Shigeyoshi

    2012-03-01

    The theoretical evaluation of the oscillator strength of a symmetry-forbidden d-d transition is not easy even nowadays. A new approximate method is proposed here and applied to octahedral complexes [Co(NH(3))(6)](3+) and [Rh(NH(3))(6)](3+) as an example. Our method incorporates the effects of geometry distortion induced by molecular vibration and the thermal distribution of such distorted geometries but does not need the Herzberg-Teller approximation. The calculated oscillator strengths of [Co(NH(3))(6)](3+) agree well with the experimental values in both (1)A(1g) → (1)T(1g) and (1)A(1g) → (1)T(2g) transitions. In the Rh analogue, though the calculated oscillator strengths are somewhat smaller than the experimental values, computational results reproduce well the experimental trends that the oscillator strengths of [Rh(NH(3))(6)](3+) are much larger than those of the Co analogue and the oscillator strength of the (1)A(1g) → (1)T(1g) transition is larger than that of the (1)A(1g) → (1)T(2g) transition. It is clearly shown that the oscillator strength is not negligibly small even at 0 K because the distorted geometry (or the uncertainty in geometry) by zero-point vibration contributes to the oscillator strength at 0 K. These results are discussed in terms of frequency of molecular vibration, extent of distortion induced by molecular vibration, and charge-transfer character involved in the d-d transition. The computational results clearly show that our method is useful in evaluating and discussing the oscillator strength of symmetry-forbidden d-d absorption of transition metal complex.

  3. Photoabsorption Spectrum and Optically Forbidden Transitions of Krypton by Electron Impact

    Institute of Scientific and Technical Information of China (English)

    苑震生; 朱林繁; 李文斌; 成华东; 徐克尊

    2002-01-01

    A high resolution fast electron energy loss spectrometer with multi-channel energy analysis was employed. The maxima just above the threshold 4p-1(2P1/2), which is regarded as a shape resonance, was obtained at 16.3 eV. The optically forbidden excitations of 4s electron were measured for the first time, and the energy positions are 23.75 eV(4s-15s), 25.66 eV (4s-16s/4d) and 26.60 eV(4s-17s/5d).

  4. Forbidden lines of the solar corona and transition zone - 975-3000 A

    Science.gov (United States)

    Sandlin, G. D.; Brueckner, G. E.; Tousey, R.

    1977-01-01

    Forbidden lines characteristic of plasmas at temperatures of 50,000 to 3 million K are observed in ATM UV spectra. Identifications, accurate wavelengths, ionization classes, intensities, and half-widths are presented. Coronal blends with He II at 1640 A are noted. Variations in nonthermal velocities with limb distance are observed. Doppler shifts in the coronal lines observed on the disk may be related to the solar wind. The coincidence of two lines with F IV(3P-5S) is evidence for atomic fluorine in the sun.

  5. Forbidden Electronic Transitions between the Singlet Ground State and the Triplet Excited State of Pt(II) Complexes.

    Science.gov (United States)

    Zheng, Greg Y.; Rillema, D. Paul; DePriest, Jeff; Woods, Clifton

    1998-07-13

    Direct access to the triplet emitting state from the ground state is observed for Pt(II) complexes containing heterocyclic (CwedgeC', CwedgeN, NwedgeN') and bis(diphenylphosphino)alkane (PwedgeP') ligands. Extinction coefficients for such transitions are in the range 4-25 M(-)(1) cm(-)(1). Emission quantum yields resulting from singlet-to-triplet excitation are as high as 61-77 times the emission quantum yields resulting from singlet-to-singlet excitation at 296 K. The intersystem crossing quantum yield from the singlet excited state to triplet emitting state is lower than 2% at 296 K but is greatly enhanced at 77 K. The forbidden electronic transition observed for Pt(II) complexes is attributed to result from spin-orbit coupling due to the presence of Pt(II) in the skeleton structure. The importance of excitation spectra on the computation of emission quantum yields is discussed.

  6. Design of spin-forbidden transitions for polypyridyl metal complexes by time-dependent density functional theory including spin-orbit interaction.

    Science.gov (United States)

    Kanno, Shohei; Imamura, Yutaka; Hada, Masahiko

    2016-05-25

    We explore spin-forbidden transitions for a Ru dye with an N3 skeleton and an Fe dye with a DX1 skeleton by time-dependent density functional theory with spin-orbit interaction. The modified N3-based Ru dye with iodine anions has an absorption edge in the long wavelength region which is not observed in the original N3 dye. The long wavelength absorption edge originates from the spin-orbit interaction with iodine. Although the Fe dye has a small spin-orbit interaction, because of less spin-orbit interaction from the light metal, spin-forbidden transitions also occur for DX1-based Fe dye systems with iodine anions. This result indicates that the introduction of iodine can strengthen the spin-orbit interaction for a dye sensitizer and offers a new approach for designing spin-forbidden transitions.

  7. The controlled excitation of forbidden transitions in the two-photon spectrum of strontium by using collisions and electric fields

    Science.gov (United States)

    Philip, G.; Connerade, J.-P.

    2007-11-01

    We present experimental results involving controlled configuration mixing in two-photon spectroscopy of highly-excited states by exploiting a weak external electric field and collisions. The method has allowed new extensions to high members of the two-photon forbidden J = 3 odd-parity 5snf 1F 3 and the J = 0, even-parity 5sns 1S 0 Rydberg series of neutral strontium to be observed. We achieve resonant two-photon transverse excitation of a high density atomic jet by using a narrow bandwidth tunable dye laser in a heat pipe setup with sensitive ionization detection. Experimental term values are extended for the 5sns 1S 0 series up to n = 46. By suitable exploitation of the composition and pressure of the buffer gases in conjunction with the electric field strength in the excitation region and the exciting laser beam intensity we have also extended observations up to n = 44 for the 5snf 1F 3 series and up to n = 46 for the 5snp 1P 1 series. Our results demonstrate a novel and remarkably simple experimental method to access high Rydberg states to which transitions are forbidden from the ground state by parity and other selection rules.

  8. Ab-Initio Based Computation of Rate Constants of Spin Forbidden Transitions in (Bio)inorganic Complexes and Metalloproteins

    Science.gov (United States)

    Ozkanlar, Abdullah; Rodriguez, Jorge H.

    2009-03-01

    Some (bio)chemical reactions are non-adiabatic processes whereby the total spin angular momentum, before and after the reaction, is not conserved. These are named spin- forbidden reactions. The application of spin density functional theory (SDFT) to the prediction of rate constants is a challenging task of fundamental and practical importance. We apply non-adiabatic transition state theory in conjunction with SDFT to predict the rate constant of the spin- forbidden dihydrogen binding to iron tetracarbonyl. To model the surface hopping probability between singlet and triplet states, the Landau-Zener formalism is used. The lowest energy point for singlet-triplet crossing, known as minimum energy crossing point (MECP), was located and used to compute, in a semi-quantum approach, reaction rate constants at 300 K. The predicted rates are in good agreement with experiment. In addition, we present results which are relevant to the ligand binding reactions of metalloproteins. This work is supported in part by NSF via CAREER award CHE-0349189 (JHR).

  9. Evidence for the virtual beta-gamma transition in 59Ni

    CERN Document Server

    Pfützner, M; Żylicz, J

    2015-01-01

    A novel theory of radiative electron capture in second forbidden non-unique transition, is applied to reanalyze experimental data obtained previously for the decay of 59Ni. The measured gamma spectrum is shown to be distorted at the high-energy end, presenting the first direct evidence for the virtual beta-gamma transition through the excited state in 59Co. The complete theoretical predictions, including both the direct and the virtual decay channels, as well as the interference between them, reproduce very well the experimental spectrum. The virtual nuclear component amounts to about 4% of the total gamma intensity.

  10. Magnetic field-induced spectroscopy of forbidden optical transitions with application to lattice-based optical atomic clocks.

    Science.gov (United States)

    Taichenachev, A V; Yudin, V I; Oates, C W; Hoyt, C W; Barber, Z W; Hollberg, L

    2006-03-01

    We develop a method of spectroscopy that uses a weak static magnetic field to enable direct optical excitation of forbidden electric-dipole transitions that are otherwise prohibitively weak. The power of this scheme is demonstrated using the important application of optical atomic clocks based on neutral atoms confined to an optical lattice. The simple experimental implementation of this method--a single clock laser combined with a dc magnetic field--relaxes stringent requirements in current lattice-based clocks (e.g., magnetic field shielding and light polarization), and could therefore expedite the realization of the extraordinary performance level predicted for these clocks. We estimate that a clock using alkaline-earth-like atoms such as Yb could achieve a fractional frequency uncertainty of well below 10(-17) for the metrologically preferred even isotopes.

  11. Allowed and forbidden d-d transitions in poly(3,5-dimethylpyrazolyl)methane complexes of nickel(II).

    Science.gov (United States)

    Nolet, Marie-Christine; Michaud, Annie; Bain, Cheryl; Zargarian, Davit; Reber, Christian

    2006-01-01

    Absorption spectra of four nickel(II) complexes with poly(pyrazolyl)methane ligands are presented in the NIR-VIS-UV region and the band system corresponding to the lowest-energy spin-allowed and spin-forbidden transitions is analyzed. A quantitative theoretical model involving coupled electronic states provides precise energies for the lowest-energy triplet and singlet excited states and allows comparisons between complexes with a variable number of nitrogen and oxygen ligator atoms. Singlet energies between 12,840 and 13,000 cm(-1) are determined for heteroleptic complexes. These energies are in an intermediate range between those for homoleptic complexes with either nitrogen or oxygen ligator atoms with singlet states at approximately 12,000 and 14,000 cm(-1), respectively. The new theoretical approach is compared to the traditional ligand-field parameters obtained from the maxima of the broad, spin-allowed absorption bands.

  12. Identification of forbidden transitions in the nu-4 band of (N-14)H3 by intracavity laser-Stark spectroscopy

    Science.gov (United States)

    Weber, W. H.; Cohen, E. A.

    1983-01-01

    These transitions are forbidden in the sense that they follow the selection rule delta K = + or - 2, which violates the usual rule that delta K = + or - 1 for a perpendicular band of a symmetric top, where K is the projection of the total angular momentum onto the molecular symmetry axis. The assignments are based for the most part on laser-Stark measurements made with a CO laser and an intracavity Stark cell. The procedure followed in making the assignments is described. Attention is called to the significance of these new lines in the analysis of the nu-4 vibrational state and in an improved determination of the ground-state rotational and centrifugal distortion constants.

  13. Transition moments, Franck-Condon factors, and lifetimes of forbidden transitions - Calculation of the intensity of the Cameron system of CO.

    Science.gov (United States)

    James, T. C.

    1971-01-01

    Discussion of the factors affecting the intensity of forbidden transitions in diatomic molecules. It is shown that using Franck-Condon factors to predict relative band intensities is less reliable for forbidden transitions than it is for allowed transitions. The intensity of the 0,0 and 1,0 bands of the a super 3 pi-super 1 sigma Cameron system of CO are calculated using perturbation theory. The intensity arises from spin-orbit mixing of the A super 1 pi state with the a super 3 pi state. From the known spin-orbit coupling constant of the a super 1 pi state and the known intensity of the fourth positive A super 1 pi-super 1 sigma transition, the oscillator strengths of the 0,0 and 1,0 bands are calculated to be 1.63 x 10 to the minus 7th power and 1.99 x 10 to the minus 7th power. Lifetimes of various rotational levels are shown to range from 2.9 to several hundred milliseconds.-

  14. Transition moments, Franck-Condon factors, and lifetimes of forbidden transitions - Calculation of the intensity of the Cameron system of CO.

    Science.gov (United States)

    James, T. C.

    1971-01-01

    Discussion of the factors affecting the intensity of forbidden transitions in diatomic molecules. It is shown that using Franck-Condon factors to predict relative band intensities is less reliable for forbidden transitions than it is for allowed transitions. The intensity of the 0,0 and 1,0 bands of the a super 3 pi-super 1 sigma Cameron system of CO are calculated using perturbation theory. The intensity arises from spin-orbit mixing of the A super 1 pi state with the a super 3 pi state. From the known spin-orbit coupling constant of the a super 1 pi state and the known intensity of the fourth positive A super 1 pi-super 1 sigma transition, the oscillator strengths of the 0,0 and 1,0 bands are calculated to be 1.63 x 10 to the minus 7th power and 1.99 x 10 to the minus 7th power. Lifetimes of various rotational levels are shown to range from 2.9 to several hundred milliseconds.-

  15. Precise Calculations of Astrophysically Important Allowed and Forbidden Transitions of Xe VIII

    Science.gov (United States)

    Bhowmik, Anal; Nath Dutta, Narendra; Roy, Sourav

    2017-02-01

    The present work reports transition line parameters for Xe viii, which are potentially important for astrophysics in view of recent observations of multiply ionized xenon in hot white dwarfs. The relativistic coupled-cluster method is employed here to calculate the E1, E2, and M1 transition line parameters with high accuracy. The E1 oscillator strengths and probabilities of E2 and M1 transitions are determined using theoretical amplitudes and experimental energy values. The calculated branching ratios and the lifetimes are supplemented to the transition parameters. The accurate presentation of these calculated data is crucial for density estimation in several stellar and interstellar media.

  16. Precise calculations of astrophysically important allowed and forbidden transitions of Xe VIII

    CERN Document Server

    Bhowmik, Anal; Roy, Sourav

    2016-01-01

    The present work reports astrophysically important transition line parameters for Xe VIII. The relativistic coupled-cluster method is employed here to calculate the E1, E2, and M1 transition line parameters with a high accuracy. The E1 oscillator strengths and probabilities of E2 and M1 transitions are determined using theoretical amplitudes and experimental energy values. The calculated branching ratios and the lifetimes are supplement to the transition parameters. The accurate presentations of these calculated data are crucial for the density estimations in several stellar and inter-stellar mediums.

  17. Fast-timing study of the l -forbidden 1 /2+→3 /2+ M 1 transition in 129Sn

    Science.gov (United States)

    Licǎ, R.; Mach, H.; Fraile, L. M.; Gargano, A.; Borge, M. J. G.; Mǎrginean, N.; Sotty, C. O.; Vedia, V.; Andreyev, A. N.; Benzoni, G.; Bomans, P.; Borcea, R.; Coraggio, L.; Costache, C.; De Witte, H.; Flavigny, F.; Fynbo, H.; Gaffney, L. P.; Greenlees, P. T.; Harkness-Brennan, L. J.; Huyse, M.; Ibáñez, P.; Judson, D. S.; Konki, J.; Korgul, A.; Kröll, T.; Kurcewicz, J.; Lalkovski, S.; Lazarus, I.; Lund, M. V.; Madurga, M.; Mǎrginean, R.; Marroquín, I.; Mihai, C.; Mihai, R. E.; Morales, A. I.; Nácher, E.; Negret, A.; Page, R. D.; Pakarinen, J.; Pascu, S.; Paziy, V.; Perea, A.; Pérez-Liva, M.; Picado, E.; Pucknell, V.; Rapisarda, E.; Rahkila, P.; Rotaru, F.; Swartz, J. A.; Tengblad, O.; Van Duppen, P.; Vidal, M.; Wadsworth, R.; Walters, W. B.; Warr, N.; IDS Collaboration

    2016-04-01

    The levels in 129Sn populated from the β- decay of 129In isomers were investigated at the ISOLDE facility of CERN using the newly commissioned ISOLDE Decay Station (IDS). The lowest 1 /2+ state and the 3 /2+ ground state in 129Sn are expected to have configurations dominated by the neutron s1 /2 (l =0 ) and d3 /2 (l =2 ) single-particle states, respectively. Consequently, these states should be connected by a somewhat slow l -forbidden M 1 transition. Using fast-timing spectroscopy we have measured the half-life of the 1 /2+ 315.3-keV state, T1 /2= 19(10) ps, which corresponds to a moderately fast M 1 transition. Shell-model calculations using the CD-Bonn effective interaction, with standard effective charges and g factors, predict a 4-ns half-life for this level. We can reconcile the shell-model calculations to the measured T1 /2 value by the renormalization of the M 1 effective operator for neutron holes.

  18. Fully relativistic study of forbidden transitions of OII : Electron density diagnosis for planetary nebulas

    Science.gov (United States)

    Chen, Shaohao; Qing, Bo; Li, Jiaming

    2007-10-01

    Using the multiconfiguration Dirac-Fock method, including the quantum electrodynamics corrections, especially with the Breit interactions, we calculate the electric quadrupole (E2) and magnetic dipole (M1) transition rates for the two transitions D5/2,3/2o2→S3/2o4 of OII . We show systematically that the correlation effects owing to core electron excitations and the Breit interactions are vitally important for the transition rates. We present a benchmark for the intensity ratio between the two transitions in the limit of high electron density in planetary nebulas, i.e., r(∞)=0.345-0.014+0.028 , which is in good agreement with modern astronomical observations.

  19. Collision strengths and transition probabilities for Co II infrared forbidden lines

    CERN Document Server

    Storey, P J; Sochi, Taha

    2016-01-01

    We calculate collision strengths and their thermally-averaged Maxwellian values for electron excitation and de-excitation between the fifteen lowest levels of singly-ionised cobalt, Co+, which give rise to emission lines in the near- and mid-infrared. Transition probabilities are also calculated and relative line intensities predicted for conditions typical of supernova ejecta. The diagnostic potential of the 10.52, 15.46 and 14.74 micro-metre transition lines is briefly discussed.

  20. Electronic states and spin-forbidden cooling transitions of AlH and AlF.

    Science.gov (United States)

    Wells, Nathan; Lane, Ian C

    2011-11-14

    The feasibility of laser cooling AlH and AlF is investigated using ab initio quantum chemistry. All the electronic states corresponding to the ground and lowest two excited states of the Al atom are calculated using multi-reference configuration interaction (MRCI) and the large AV6Z basis set for AlH. The smaller AVQZ basis set is used to calculate the valence electronic states of AlF. Theoretical Franck-Condon factors are determined for the A(1)Π→ X(1)Σ(+) transitions in both radicals and found to agree with the highly diagonal factors found experimentally, suggesting computational chemistry is an effective method for screening suitable laser cooling candidates. AlH does not appear to have a transition quite as diagonal as that in SrF (which has been laser cooled) but the A(1)Π→ X(1)Σ(+) transition transition of AlF is a strong candidate for cooling with just a single laser, though the cooling frequency is deep in the UV. Furthermore, the a(3)Π→ X(1)Σ(+) transitions are also strongly diagonal and in AlF is a practical method for obtaining very low final temperatures around 3 μK.

  1. Differential electron scattering cross sections for the first optically forbidden and resonance transitions in Mg II, Zn II and Cd II

    Science.gov (United States)

    Williams, I. D.; Chutjian, A.; Mawhorter, R. J.

    1986-01-01

    Differential electron scattering cross sections have been measured for dipole-forbidden and resonance transitions in Mg II, Zn II and Cd II in the angular range theta = 4-17 deg at 50 eV. These provide the first recorded angular distributions for an optically forbidden transition. It is found that while the cross section for excitation of the 4s (2)S-3d(9)4s(2) (2)D transition in Zn II is small, those for the 3s (2)S-3d (2)D, 4s (2)S (unresolved lines) in Mg II, and the 5s (2)S-4d(9)5s(2) D in Cd II are comparable in magnitude with the cross sections for resonance excitation. In addition, for Cd II it is found that the allowed and forbidden transitions have very similar angular distributions, and it is proposed that excitation to the 2D state may be dominated by a virtual 'double-dipole' transition via the 2P state. Also, the total excitation cross section of the resonance 2P state in Cd II is a factor of four higher than that predicted by the Gaunt factor approximation, suggesting that the accepted value for the oscillator strength may be too low.

  2. Study of the 5p3/2 -> 6p3/2 electric dipole forbidden transition in atomic rubidium using optical-optical double resonance spectroscopy

    CERN Document Server

    Ponciano-Ojeda, Francisco; López-Hernández, Oscar; Mojica-Casique, Cristian; Colín-Rodríguez, Ricardo; Ramírez-Martínez, Fernando; Flores-Mijangos, Jesús; Sahagún, Daniel; Jáuregui, Rocío; Jiménez-Mier, José

    2015-01-01

    Direct evidence of excitation of the 5p3/2 -> 6p3/2 electric dipole forbidden transition in atomic rubidium is presented. The experiments were performed in a room temperature rubidium cell with continuous wave extended cavity diode lasers. Optical-optical double resonance spectroscopy with counterpropagating beams allows the detection of the non-dipole transition free of Doppler broadening. The 5p3/2 state is prepared by excitation with a laser locked to the maximum F cyclic transition of the D2 line, and the forbidden transition is produced by excitation with a 911 nm laser. Production of the forbidden transition is monitored by detection of the 420 nm fluorescence that results from decay of the 6p3/2 state. Spectra with three narrow lines (~ 13 MHz FWHM) with the characteristic F - 1, F and F + 1 splitting of the 6p3/2 hyperfine structure in both rubidium isotopes were obtained. The results are in very good agreement with a direct calculation that takes into account the 5s -> 5p3/2 preparation dynamics, the...

  3. Forbidden Transition Probabilities of Astrophysical Interest among Low-lying States of V III

    Indian Academy of Sciences (India)

    Andrei Irimia

    2007-06-01

    Electric and magnetic multipole transitions among low-lying states of doubly ionized vanadium were computed using the multi-configuration Hartree–Fock (MCHF) method with Breit–Pauli (BP) corrections to a non-relativistic Hamiltonian. Energy levels were determined up to and including 32(1)4 b 27/2 and computed energies were found to be in good agreement with experiment and other theories. In addition to Einstein coefficients for some E2 and M1 transitions, lifetime data and selected weighted oscillator strengths are also reported.

  4. Detection of forbidden Singlet-Triplet Transitions of 12C16O

    CSIR Research Space (South Africa)

    Steenkamp, CM

    2010-09-01

    Full Text Available Twenty rovibronic transitions of the e(v'=5)-X(v''=0) band of the 12C16O which experimental wavelengths were previously unavailable were recently detected by vr induced fluorescence excitation spectroscopy. The data is important in astrophysical...

  5. An Improved Limit on Pauli-Exclusion-Principle Forbidden Atomic Transitions

    CERN Document Server

    Elliott, S R; Gehman, V M; Kidd, M F; Chen, M

    2011-01-01

    We have examined the atomic theory behind recent constraints on the violation of the Pauli Exclusion Principle derived from experiments that look for x rays emitted from conductors while a large current is present. We also re-examine the assumptions underlying such experiments. We use the results of these studies to assess pilot measurements to develop an improved test of the Principle. We present an improved limit of $(1/2)\\beta^2 < 2.6\\times10^{-39}$ on the Pauli Exclusion Principle. This limit is the best to date for interactions between a system of fermions and a fermion that has not previously interacted with that given system. That is, for systems that do not obviously violate the Messiah-Greenberg symmetrization-postulate selection rule.

  6. Analysis of the competition between forbidden and hyperfine-induced transitions in Ne-like ions

    Science.gov (United States)

    Andersson, Martin; Grumer, Jon; Brage, Tomas; Zou, Yaming; Hutton, Roger

    2016-03-01

    In this work we investigate the decay of the |2 p53 s P30> state in neon-like ions along the isoelectronic sequence ranging from Z =10 to Z =35 . In the absence of a nuclear spin, the magnetic dipole transition to |2 p53 s P31> is the dominating decay channel. However, for isotopes with a nuclear spin, the interaction between the nuclear magnetic dipole moment and the electronic field introduces a mixing of |2 p53 s P31> and |P11> into the |P30> state, which in turn opens up a competing hyperfine-induced electric dipole decay channel to the ground state. This hyperfine-induced transition channel clearly dominates over the magnetic dipole channel for the neutral end of the isoelectronic sequence, when present. We give values for the rates of both these competing channels and discuss how the introduction of the hyperfine-induced transition channel could have a dramatic influence on the spectrum, not only because it introduces a new line, but also since it can substantially decrease the intensity of the magnetic dipole 2 p53 s P30→2 p53 s P31 line and affect the predicted ionization balance in different plasmas.

  7. High precision wavelength measurements of QED-sensitive forbidden transitions in highly charged argon ions.

    Science.gov (United States)

    Draganić, I; Crespo López-Urrutia, J R; DuBois, R; Fritzsche, S; Shabaev, V M; Orts, R Soria; Tupitsyn, I I; Zou, Y; Ullrich, J

    2003-10-31

    We present the results of an experimental study of magnetic dipole (M1) transitions in highly charged argon ions (Ar X, Ar XI, Ar XIV, Ar XV) in the visible spectral range using an electron beam ion trap. Their wavelengths were determined with, for highly charged ions, unprecedented accuracy up to the sub-ppm level and compared with theoretical calculations. The QED contributions, calculated in this Letter, are found to be 4 orders of magnitude larger than the experimental error and are absolutely indispensable to bring theory and experiment to a good agreement. This method shows great potential for the study of QED effects in relativistic few-electron systems.

  8. A direct method for locating minimum-energy crossing points (MECPs) in spin-forbidden transitions and nonadiabatic reactions.

    Science.gov (United States)

    Chachiyo, Teepanis; Rodriguez, Jorge H

    2005-09-01

    An efficient computational method for locating minimum-energy crossing points (MECPs) between potential-energy surfaces in spin-crossover transitions and nonadiabatic spin-forbidden (bio)chemical reactions is introduced. The method has been tested on the phenyl cation and the computed MECP associated with its radiationless singlet-triplet spin crossover is in good agreement with available data. However, the convergence behavior of the present method is significantly more efficient than some alternative methods which allows us to study nonadiabatic processes in larger systems such as spin crossover in metal-containing compounds. The convergence rate of the method obeys a fast logarithmic law which has been verified on the phenyl cation. As an application of this new methodology, the MECPs of the ferrous complex [Fe(ptz)(6)](BF(4))(2), which exhibits light-induced excited spin state trapping, have been computed to identify their geometric and energetic parameters during spin crossover. Our calculations, in conjunction with spin-unrestricted density-functional calculations, show that the transition from the singlet ground state to a triplet intermediate and to the quintet metastable state of [Fe(ptz)(6)](BF(4))(2) is accompanied by unusually large bond-length elongations of the axial ligands ( approximately 0.26 and 0.23 A, respectively). Our results are consistent with crystallographic data available for the metastable quintet but also predict new structural and energetic information about the triplet intermediate and at the MECPs which is currently not available from experiment.

  9. Dipole-forbidden atomic transitions induced by superintense x-ray laser fields

    Science.gov (United States)

    Simonsen, Aleksander Skjerlie; Førre, Morten

    2016-06-01

    A hydrogen atom, initially prepared in the 2 s and/or 2 p (m =±1 ) states, is assumed irradiated by 0.8 keV (1.5 nm) photons in pulses of 1 -250 fs duration and intensities in the range 1020 to 1023W /cm2 . Solving the corresponding time-dependent Schrödinger equation from first principles, we show that the ionization and excitation dynamics of the laser-atom system is strongly influenced by interactions beyond the electric dipole approximation. A beyond-dipole two-photon Raman-like transition between the 2 s and 2 p (m =±1 ) states is found to completely dominate the underlying laser-matter interaction. It turns out that the large difference in the ionization rates of the 2 s and 2 p (m =±1 ) states is important in this context, effectively leading to a symmetry breaking in the corresponding (beyond-dipole) bound-bound dynamics with the result that a net population transfer between the states occurs throughout the laser-matter interaction period. Varying the x-ray exposure time as well as the laser intensity, we probe the phenomenon as the bound wave packet oscillates between having 2 s and 2 p (m =±1 ) character, eventually giving rise to a Rabi-like oscillation pattern in the populations.

  10. Measurement of dynamic Stark polarizabilities by analyzing spectral lineshapes of forbidden transitions

    CERN Document Server

    Dounas-Frazer, D R; Family, A; Budker, D

    2010-01-01

    We present a measurement of the dynamic scalar and tensor polarizabilities of the excited state 3D1 in atomic ytterbium. The polarizabilities were measured by analyzing the spectral lineshape of the 408-nm 1S0->3D1 transition driven by a standing wave of resonant light in the presence of static electric and magnetic fields. Due to the interaction of atoms with the standing wave, the lineshape has a characteristic polarizability-dependent distortion. A theoretical model was used to simulate the lineshape and determine a combination of the polarizabilities of the ground and excited states by fitting the model to experimental data. This combination was measured with a 13% uncertainty, only 3% of which is due to uncertainty in the simulation and fitting procedure. The scalar and tensor polarizabilities of the state 3D1 were measured for the first time by comparing two different combinations of polarizabilities. We show that this technique can be applied to similar atomic systems.

  11. Infrared spectrum involving forbidden transitions & coriolis interaction and identification of optically pumped far infrared laser lines in asymmetrically mono-deuterated methanol (Methanol-D1)

    Science.gov (United States)

    Mukhopadhyay, Indra

    2016-05-01

    In this paper new type of ΔK = 2 and 0 transitions have been identified in the Fourier Transform spectrum of Methanol-D1 (CH2DOH). These transitions are normally forbidden but a "Coriolis" type interaction with nearby states is believed to be contributing sufficient transition strength through intensity borrowing effect. This is the first time such forbidden transitions are reported to be identified in the excited states, in this molecule. The present conjecture is supported by observation of a many strong allowed transitions to upper terminating levels which are seen to be highly perturbed. This conclusion has been reached by comparing calculated energy levels using known molecular parameters (Pearson et al., 2012; Coudert et al., 2014; El Hilali et al., 2011; Quade et al., 1998; Richard Quade, 1998, 1999; Mukhopadhyay, 1997) and the actually observed FIR lines. The upper levels are seen to be upshifted from expected position. A closer look at the calculated energy values seems to indicate a possible interaction between the above states and other proximate torsional-rotational states could occur. The possible candidates for the interacting level manifolds are narrowed down through the presence of the forbidden transition. We also take the opportunity to propose alternate rotational quantum numbers for some of the assignments recently reported in the literature (El Hilali et al., 2011). Some ambiguities are pointed out on the data and the reported analysis. There remain too many such irregularities and we propose to gather a large body assigned transitions in a future catalog. Assignments and relevant comments on optically pumped FIR laser radiation are also made.

  12. Transition energies and oscillator strength calculated for d-s symmetry-forbidden electronic transition for Cu{sup +} impurities in sodium fluoride host lattice

    Energy Technology Data Exchange (ETDEWEB)

    Uhl, Elmar [Instituto de Quimica, Departamento de Fisico-Quimica, Universidade Federal do Rio de Janeiro, Cidade Universitaria, CT Bloco A. Rio de Janeiro, 21941-909 Rio de Janeiro (Brazil); Leitao, Alexandre A. [Departamento de Quimica, Universidade Federal de Juiz de Fora, Campus Universitario, Juiz de Fora, MG 36036-900 (Brazil); Rocha, Alexandre B., E-mail: rocha@iq.ufrj.br [Instituto de Quimica, Departamento de Fisico-Quimica, Universidade Federal do Rio de Janeiro, Cidade Universitaria, CT Bloco A. Rio de Janeiro, 21941-909 Rio de Janeiro (Brazil)

    2011-11-07

    Graphical abstract: Temperature dependence of oscillator strengths calculated through vibronic coupling for electronic transitions of Cu{sup +} impurity in NaF host, described by embedded cluster model. Highlights: Black-Right-Pointing-Pointer Embedded cluster model for impurity levels in the NaF:Cu{sup +} system. Black-Right-Pointing-Pointer Oscillator strengths (OSs) calculated by direct vibronic coupling method. Black-Right-Pointing-Pointer The dependence of the OS on temperature is reported. Black-Right-Pointing-Pointer OS and transition energies calculated at CASSCF and CASSCF/SOCI level. - Abstract: An embedded cluster model is used to describe electronic structure of Cu{sup +} ion in NaF host. Transition energies and oscillator strengths are calculated for the 3d{sup 10} {yields} 3d{sup 9}4s{sup 1} Cu{sup +} ligand field transitions. These are forbidden by dipole selection rules, which can, though, be broken by vibronic coupling. The basic model consists of a [CuF{sub 6}]{sup 5-} cluster surrounded by total ion potentials representing second, third and fourth neighbors to the central Cu{sup +}. The resulting structure is placed inside a cube of point charges to take long distance Coulomb interactions into account. Variations of this basic model needed especially to the calculation of transition energy. The oscillator strengths are calculated by the direct vibronic coupling method we have previously proposed. The effect of temperature on the value of the oscillator strength is calculated for the first time as well as their absolute value. Results are in good agreement with available experiment.

  13. Observation of strong anisotropic forbidden transitions in (001 InGaAs/GaAs single-quantum well by reflectance-difference spectroscopy and its behavior under uniaxial strain

    Directory of Open Access Journals (Sweden)

    Yu Jin-Ling

    2011-01-01

    Full Text Available Abstract The strong anisotropic forbidden transition has been observed in a series of InGaAs/GaAs single-quantum well with well width ranging between 3 nm and 7 nm at 80 K. Numerical calculations within the envelope function framework have been performed to analyze the origin of the optical anisotropic forbidden transition. It is found that the optical anisotropy of this transition can be mainly attributed to indium segregation effect. The effect of uniaxial strain on in-plane optical anisotropy (IPOA is also investigated. The IPOA of the forbidden transition changes little with strain, while that of the allowed transition shows a linear dependence on strain. PACS 78.66.Fd, 78.20.Bh, 78.20.Fm

  14. Observation of strong anisotropic forbidden transitions in (001) InGaAs/GaAs single-quantum well by reflectance-difference spectroscopy and its behavior under uniaxial strain.

    Science.gov (United States)

    Yu, Jin-Ling; Chen, Yong-Hai; Tang, Chen-Guang; Jiang, Chongyun; Ye, Xiao-Ling

    2011-03-10

    The strong anisotropic forbidden transition has been observed in a series of InGaAs/GaAs single-quantum well with well width ranging between 3 nm and 7 nm at 80 K. Numerical calculations within the envelope function framework have been performed to analyze the origin of the optical anisotropic forbidden transition. It is found that the optical anisotropy of this transition can be mainly attributed to indium segregation effect. The effect of uniaxial strain on in-plane optical anisotropy (IPOA) is also investigated. The IPOA of the forbidden transition changes little with strain, while that of the allowed transition shows a linear dependence on strain.PACS 78.66.Fd, 78.20.Bh, 78.20.Fm.

  15. Spin-forbidden and spin-enabled 4f(14)-->4f(13)5d(1) transitions of Yb(2+)-doped CsCaBr3.

    Science.gov (United States)

    Sánchez-Sanz, Goar; Seijo, Luis; Barandiarán, Zoila

    2009-07-14

    The lowest part of the 4f-->5d absorption spectrum of Yb(2+)-doped CsCaBr(3) crystals has been calculated using methods of quantum chemistry and it is presented here. A first, low-intensity band is found on the low energy side of the spectrum, followed by several strong absorption bands, in agreement with experimental observations in trivalent and divalent lanthanide ions of the second half of the lanthanide series, doped in crystals. Based on Hund's rule, these transitions are usually interpreted as "spin-forbidden" and "spin-allowed" transitions, but this interpretation has been recently questioned in the literature. Here, a two-step relativistic method has been used which reveals the spin composition of the excited state wave functions. The forbidden band is found to be due to spin-forbidden transitions involving "high-spin" excited states because their 1 (3)T(1u) character is 90%. However, the allowed bands cannot be described as spin-allowed transitions involving "low-spin" excited states. Rather, they correspond to "spin-enabled" transitions because they get their intensity from limited (smaller than 45%) electric dipole enabling low-spin (1)T(1u) character. Calculations using a spin-free Hamiltonian revealed that the difference in their electronic structures is related to the fact that the 4f(13)5d(t(2g))(1) manifold is split by an energy gap which separates the lowest (high-spin) 1 (3)T(1u) from the rest of terms, which, in turn, lie very close in energy from each other. As a consequence, the lowest spin-orbit components of 1 (3)T(1u) are shown to remain 90% pure when spin-orbit coupling is considered, whereas a strong spin-orbit coupling exists between the remaining 4f(13)5d(t(2g))(1) terms, among which the 1-3 (1)T(1u) enabling ones lie. As a result, there is a widespread electric dipole enabling (1)T(1u) character, which, although never higher than 45%, leads to a number of spin-enabled absorption bands.

  16. High-precision spectroscopy of the forbidden 2 3S1 - 2 1P1 transition in quantum degenerate metastable helium

    CERN Document Server

    Notermans, Remy

    2014-01-01

    We have measured the forbidden 2 3S1 - 2 1P1 transition at 887 nm in a quantum degenerate gas of metastable He-4 atoms confined in an optical dipole trap. The determined transition frequency is 338 133 594.4 (0.5) MHz, from which we obtain an ionization energy of the 2 1P1 state of 814 709 148.6 (0.5) MHz. This ionization energy is in disagreement by > 3 sigma with the most accurate quantum electrodynamics (QED) calculations available. Our measurements also provide a new determination of the lifetime of the 2 1P1 state of 0.551 (0.004)stat (+ 0.013,- 0.000)syst ns, which is the most accurate determination to date and in excellent agreement with theory.

  17. 1/sup -/(1. 9 MeV. beta. /sup -/)2/sup +/ transition in the decay of /sup 148/Pm

    Energy Technology Data Exchange (ETDEWEB)

    Rosso, O.A.; Szybisz, L.

    1983-04-01

    The non-unique first-forbidden 1/sup -/(1.9 MeV ..beta../sup -/)2/sup +/ transition in the decay of /sup 148/Pm is studied. The nuclear matrix elements are evaluated using for the ground state of the odd-odd /sup 148/Pm a phenomenological wave function derived in a previous work in the framework of the two-quasiparticle model and assuming that the first excited 2/sup +/ state in /sup 148/Sm can be described as the first quadrupole phonon state. This model provides nuclear matrix elements which are capable of describing experimental data like the spectrum shape factor, the longitudinal polarization of the electrons and a particular set of ..beta..-..gamma.. directional correlation coefficients, but it fails to interpret the large log ft value of this transition. In addition, the validity of the zeta-approximation is discussed.

  18. Determination of A0 and D0K of 13CH 3F from the Δ k = ±2 Forbidden Transitions to the v5 = 1 Vibrational Level

    Science.gov (United States)

    Papousek, D.; Papouskova, Z.; Hsu, Y. C.; Pracna, P.; Klee, S.; Winnewisser, M.; Demaison, J.

    1993-05-01

    The Fourier transform spectrum of the vibration-rotational bands ν2 and ν5 of gaseous fluoromethane 13CH3F was measured at an unapodized resolution 0.0041 cm-1. Among the assigned lines, 102 belonged to the Δk = ±2 perturbation-allowed transitions to the doubly degenerate vibrational state v5 = 1. Combination differences were generated for the ground state of 13CH3F from the wavenumbers of the allowed and forbidden vibration-rotational transitions to the v5 = 1 level. They were used in a simultaneous least squares fit with the previously measured microwave, submillimeterwave, and far infrared transition frequencies of the pure rotational transitions in the ground state and with the combination differences generated from the allowed transitions to the v3 = 1 state of 13CH3F (Pracna, Klee, Winnewisser, Papoušek, Yen-Chu Hsu, and Hann-Sen Chen, J. Mol. Spectrosc.156, 217-226 (1992). This made it possible to determine precisely for the first time A0 and D0K for 13CH3F: A0 = (5.1824246 ± 0.0000015) cm-1, D0K = (70.912 ± 0.033) × 10-6 cm-1.

  19. Half-life systematics across the N=126 shell closure: role of first-forbidden transitions in the β decay of heavy neutron-rich nuclei.

    Science.gov (United States)

    Morales, A I; Benlliure, J; Kurtukián-Nieto, T; Schmidt, K-H; Verma, S; Regan, P H; Podolyák, Z; Górska, M; Pietri, S; Kumar, R; Casarejos, E; Al-Dahan, N; Algora, A; Alkhomashi, N; Álvarez-Pol, H; Benzoni, G; Blazhev, A; Boutachkov, P; Bruce, A M; Cáceres, L S; Cullen, I J; Denis Bacelar, A M; Doornenbal, P; Estévez-Aguado, M E; Farrelly, G; Fujita, Y; Garnsworthy, A B; Gelletly, W; Gerl, J; Grebosz, J; Hoischen, R; Kojouharov, I; Kurz, N; Lalkovski, S; Liu, Z; Mihai, C; Molina, F; Mücher, D; Rubio, B; Shaffner, H; Steer, S J; Tamii, A; Tashenov, S; Valiente-Dobón, J J; Walker, P M; Wollersheim, H J; Woods, P J

    2014-07-11

    This Letter reports on a systematic study of β-decay half-lives of neutron-rich nuclei around doubly magic (208)Pb. The lifetimes of the 126-neutron shell isotone (204)Pt and the neighboring (200-202)Ir, (203)Pt, (204)Au are presented together with other 19 half-lives measured during the "stopped beam" campaign of the rare isotope investigations at GSI collaboration. The results constrain the main nuclear theories used in calculations of r-process nucleosynthesis. Predictions based on a statistical macroscopic description of the first-forbidden β strength reveal significant deviations for most of the nuclei with Nforbidden transitions reproduce more satisfactorily the trend in the measured half-lives for the nuclei in this region, where the r-process pathway passes through during β decay back to stability.

  20. Simultaneous analysis of the Ballik-Ramsay and Phillips systems of C2 and observation of forbidden transitions between singlet and triplet states.

    Science.gov (United States)

    Chen, Wang; Kawaguchi, Kentarou; Bernath, Peter F; Tang, Jian

    2015-02-14

    6229 lines of the Ballik-Ramsay system (b(3)Σg (-)-a(3)Πu) and the Phillips system (A(1)Πu-X(1)Σg (+)) of C2 up to v = 8 and J = 76, which were taken from the literature or assigned in the present work, were analyzed simultaneously by least-squares fitting with 82 Dunham-like molecular parameters and spin-orbit interaction constants between the b(3)Σg (-) and X(1)Σg (+) states with a standard deviation of 0.0037 cm(-1) for the whole data set. As a result of the deperturbation analysis, the spin-orbit interaction constant AbX was determined as 6.333(7) cm(-1) and the energy difference between the X(1)Σg (+) and a(3)Πu states was determined as 720.008(2) cm(-1) for the potential minima or 613.650(3) cm(-1) for the v = 0 levels with Merer and Brown's N(2) Hamiltonian for (3)Π states, which is about 3.3 cm(-1) larger than the previously determined value. Due to this sizable change, a new energy-level crossing was found at J = 2 for v = 3 (F1) of b(3)Σg (-) state and v = 6 of X(1)Σg (+) state, where the strong interaction causes a nearly complete mixing of the wave functions of the b(3)Σg (-) and X(1)Σg (+) states and the forbidden transitions become observable. Using the predictions of our deperturbation analysis, we were able to identify 16 forbidden transitions between the singlet and triplet states at the predicted frequencies with the expected intensities, which verifies our value for the energy difference between the X(1)Σg (+) and a(3)Πu states.

  1. Probing formally forbidden optical transitions in PbSe nanocrystals by time- and energy-resolved transient absorption spectroscopy

    NARCIS (Netherlands)

    Schins, J.M.; Trinh, M.T.; Houtepen, A.J.; Siebbeles, L.D.A.

    2009-01-01

    The first two peaks of the optical extinction spectrum of PbSe nanocrystals in solution have been assigned in the literature to the 1Sh1Se and 1Ph1Pe transitions. In the present work we assign the transitions causing extinction in the energy region between these two lowest-energy peaks. Our femtosec

  2. Remote sensing of atomic oxygen - Some observational difficulties in the use of the forbidden O I 1173-A and O I 1641-A transitions

    Science.gov (United States)

    Erdman, P. W.; Zipf, E. C.

    1987-01-01

    Recent sounding rocket and satellite studies suggest that simultaneous measurements of the O I 989-A and 1304-A resonance lines and of the forbidden 1172.6-A and 1641.3-A transitions would form the basis of a useful remote sensing technique for measuring the O I density and optical opacity of a planetary or stellar atmosphere. Because the 1172.6-A and 1641.3-A emissions are weak lines and are emitted in a wavelength region rich in spectral features, it is important to determine whether typical flight instruments can make measurements with sufficient spectral purity so that the remote sensing observations will yield accurate results. A detailed, high-resolution study of the far UV emission features in the regions surrounding the atomic oxygen transitions at 1172.6 and 1641.3 A was made. These spectra, which were excited by electron impact on O2 and N2, are presented in an attempt to display some potential sources of interference in aeronomical measurements of these O I lines. Both atomic and molecular emissions are found, and the spectral resolution necessary to make unambiguous measurements is discussed.

  3. Observation of the Forbidden Magnetic Dipole Transition 6{sup 2}P{sub ½} --> 7{sup 2}P{sub ½} in Atomic Thallium

    Science.gov (United States)

    Chu, S.

    1976-10-01

    A measurement of the 6{sup 2}P{sub ½} --> 7{sup 2}P{sub ½} forbidden magnetic dipole matrix element in atomic thallium is described. A pulsed, linearly polarized dye laser tuned to the transition frequency is used to excite the thallium vapor from the 6{sup 2}P{sub ½} ground state to the 7{sup 2}P{sub ½} excited state. Interference between the magnetic dipole M1 amplitude and a static electric field induced E1 amplitude results in an atomic polarization of the 7{sup 2}P{sub ½} state, and the subsequent circular polarization of 535 nm fluorescence. The circular polarization is seen to be proportional to / as expected, and measured for several transitions between hyperfine levels of the 6{sup 2}P{sub ½} and 7{sup 2}P{sub ½} states. The result is = -(2.11 +- 0.30) x 10{sup -5} parallel bar e parallel bar dirac constant/2mc, in agreement with theory.

  4. BETA SPECTRA. I. Negatrons spectra; ESPECTROS BETA. I. Espectros simples de negatrones

    Energy Technology Data Exchange (ETDEWEB)

    Grau Malonda, A.; Garcia-Torano, E.

    1978-07-01

    Using the Fermi theory of beta decay, the beta spectra for 62 negatrons emitters have been computed introducing a correction factor for unique forbidden transitions. These spectra are plotted vs. energy, once normal i sed, and tabulated with the related Fermi functions. The average and median energies are calculated. (Author)

  5. Observation of strongly forbidden solid effect dynamic nuclear polarization transitions via electron-electron double resonance detected NMR

    Energy Technology Data Exchange (ETDEWEB)

    Smith, Albert A.; Corzilius, Björn; Haze, Olesya; Swager, Timothy M.; Griffin, Robert G., E-mail: rgg@mit.edu [Department of Chemistry and Francis Bitter Magnet Laboratory, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States)

    2013-12-07

    We present electron paramagnetic resonance experiments for which solid effect dynamic nuclear polarization transitions were observed indirectly via polarization loss on the electron. This use of indirect observation allows characterization of the dynamic nuclear polarization (DNP) process close to the electron. Frequency profiles of the electron-detected solid effect obtained using trityl radical showed intense saturation of the electron at the usual solid effect condition, which involves a single electron and nucleus. However, higher order solid effect transitions involving two, three, or four nuclei were also observed with surprising intensity, although these transitions did not lead to bulk nuclear polarization—suggesting that higher order transitions are important primarily in the transfer of polarization to nuclei nearby the electron. Similar results were obtained for the SA-BDPA radical where strong electron-nuclear couplings produced splittings in the spectrum of the indirectly observed solid effect conditions. Observation of high order solid effect transitions supports recent studies of the solid effect, and suggests that a multi-spin solid effect mechanism may play a major role in polarization transfer via DNP.

  6. Observation of strongly forbidden solid effect dynamic nuclear polarization transitions via electron-electron double resonance detected NMR.

    Science.gov (United States)

    Smith, Albert A; Corzilius, Björn; Haze, Olesya; Swager, Timothy M; Griffin, Robert G

    2013-12-01

    We present electron paramagnetic resonance experiments for which solid effect dynamic nuclear polarization transitions were observed indirectly via polarization loss on the electron. This use of indirect observation allows characterization of the dynamic nuclear polarization (DNP) process close to the electron. Frequency profiles of the electron-detected solid effect obtained using trityl radical showed intense saturation of the electron at the usual solid effect condition, which involves a single electron and nucleus. However, higher order solid effect transitions involving two, three, or four nuclei were also observed with surprising intensity, although these transitions did not lead to bulk nuclear polarization--suggesting that higher order transitions are important primarily in the transfer of polarization to nuclei nearby the electron. Similar results were obtained for the SA-BDPA radical where strong electron-nuclear couplings produced splittings in the spectrum of the indirectly observed solid effect conditions. Observation of high order solid effect transitions supports recent studies of the solid effect, and suggests that a multi-spin solid effect mechanism may play a major role in polarization transfer via DNP.

  7. Ordinary muon capture as a probe of virtual transitions of $\\beta\\beta$ decay

    CERN Document Server

    Kortelainen, M

    2002-01-01

    A reliable theoretical description of double-beta-decay processes needs a possibility to test the involved virtual transitions against experimental data. Unfortunately, only the lowest virtual transition can be probed by the traditional electron-capture or $\\beta^-$-decay experiments. In this article we propose that calculated amplitudes for many virtual transitions can be probed by experiments measuring rates of ordinary muon capture (OMC) to the relevant intermediate states. The first results from such experiments are expected to appear soon. As an example we discuss the $\\beta\\beta$ decays of $^{76}$Ge and $^{106}$Cd and the corresponding OMC for the $^{76}$Se and $^{106}$Cd nuclei in the framework of the proton-neutron QRPA with realistic interactions. It is found that the OMC observables, just like the $2\

  8. FULLY RELATIVISTIC CALCULATIONS OF THE ENERGIES,OSCILLATOR STRENGTHS AND EINSTEIN COEFFICENTS OFTHE FORBIDDEN TRANSITIONS FOR Ne-LIKE SEQUENCES

    Institute of Scientific and Technical Information of China (English)

    LI XIANG-DONG; TAN MING-LIANG; YI YOU-GEN; ZHANG ZHI-HONG; ZHU ZHENG-HE; ZHANG ZHI-HONG

    2000-01-01

    We provide systematic calculations about the energy levels, Einstein coefficients and oscillator strengths for electricquadrupole (E2) and magnetic quadrupole (M2) transitions between n=3 and n=2 of Ne-like systems by using the fullyrelativistic multi-configuration Dirac-Fock method. The oscillator strengths of the E2 transitions under Coulomb andBabshkin gauges are compared with each other and show the differences from 1.2 to 12 percent. We also found that theM2 line (0.37429 nm) with the biggest oscillator strengths in Ne-like Ag37+ mixes with the line (2p5 3/23s1/23d5/2)3/2 →gs(0.37427 nm) emitted by the Na-like Ag36+.

  9. Luminescence spectroscopy of matrix-isolated atomic manganese: excitation of the "forbidden" a6D(J)a6S transitions.

    Science.gov (United States)

    Collier, Martin A; Ryan, Maryanne C; McCaffrey, John G

    2005-07-22

    Laser-induced excitation spectra recorded for the electric-quadrupole 3d(6)4s a6D(J)transitions of atomic Mn, allow assignment of the red emission features, previously observed in Mn/RG (RG=Ar, Kr and Xe) matrices with resonance 3d(5)4s4pz6P(5/2)transition from the J=9/2 spin-orbit level. Temperature dependent emission scans lead to the identification of the zero phonon line for the a6D(9/2)-->a6S(5/2) transition at 585.75 nm. The identified matrix-shift of +20 cm(-1) allows an assessment of the extent of the ground state stabilization in the red (secondary) site of atomic Mn isolation in solid Kr. Emission produced with direct a6D state excitation yielded both the 585.75 and 626 nm features. The former band arises for Mn atoms occupying the red site--the latter from blue site occupancy in solid Kr. The excitation linewidths recorded for these two sites differ greatly, with the blue site yielding a broad featureless profile, in contrast to the narrow, structured features of the red site. The corresponding red site a6D(J)a6S(5/2) transitions in Ar and Xe matrices are broader than in Kr--a difference considered to originate from the site sizes available in these hosts and the interatomic Mn x RG potentials. The millisecond decay times recorded for the red emission bands in the Mn/RG systems are all much shorter than the 3 s value predicted for the gas phase a6D(9/2)-->a6S(5/2) transition. This enhancement allows optical pumping of the forbidden a6D(J)a6S transitions with low laser powers when atomic manganese is isolated in the solid state. However all the emission decays are complex, exhibiting triple exponential decays. This behavior may be related to the dependence of the excitation linewidths on the J value, indicating removal of the J degeneracy due to weak matrix-induced, crystal field splitting.

  10. Ab initio study of the n-π* electronic transition in acetone: Symmetry-forbidden vibronic spectra

    Science.gov (United States)

    Liao, D. W.; Mebel, A. M.; Hayashi, M.; Shiu, Y. J.; Chen, Y. T.; Lin, S. H.

    1999-07-01

    Ab initio calculations of geometry and vibrational frequencies of the first singlet excited 1A2(1A″) state of acetone corresponding to the n-π* electronic transition have been carried out at the CASSCF/6-311G** level. The major geometry changes in this state as compared to the ground state involve CO out-of-plane wagging, CO stretch and torsion of the methyl groups, and the molecular symmetry changes from C2v to Cs. The most pronounced frequency changes in the 1A″ state are the decrease of the CO stretch frequency v3 by almost 500 cm-1 and the increase of the CH3 torsion frequency v12 from 22 to 170 cm-1. The optimized geometries and normal modes are used to compute the normal mode displacements which are applied for calculations of Franck-Condon factors. Transition matrix elements over the one-electron electric field operator at various atomic centers calculated at the state-average CASSCF/6-311+G** level are used to compute vibronic couplings between the ground 1A1, 1A2, and Rydberg 1B2(n-3s), 2 1A1(n-3py), 2 1A2(n-3px), 2 1B2(n-3pz), and 1B1(n-3dxy) electronic states, and the Herzberg-Teller expansion of the electronic wave function is applied to derive the transition dipole moment for 1A1→1A2 as a function of normal coordinates. The results show that the intensity for this transition is mostly borrowed from the allowed 1A1-1B2(n-3s) transition due to vibronic coupling between 1A2 and 1B2 through normal modes Q20, Q22, and Q23 and, to some extent, from the 1A1-1B1 transition due to Q19 (CO in-plane bend) which couples 1A2 with 1B1(n-3dxy). The calculated total oscillator strength for the n-π* transition through the intensity-borrowing mechanism, 3.62×10-4, is in close agreement with the experimental value of 4.14×10-4. Ninety-four percent of the oscillator strength comes from the perpendicular component (b1 inducing modes) and 6% from the parallel component (b2 modes). Calculated spectral origin, 30 115 cm-1 at the MRCI/6-311G** level, underestimates

  11. Forbidden singlet exciton transitions induced by localization in polymer light-emitting diodes in a strong electric field.

    Science.gov (United States)

    Sun, Zheng; Xu, Yuan-Ping; Li, Sheng; George, Thomas F

    2011-02-10

    Through combining the electron transition process and dipole moment evolution as well as electron-phonon coupling, molecular dynamics calculations show that the radiative decay of singlet excitons in a conjugated polymer, such as a polymer light-emitting diode (PLED), is largely determined by the evolution of the dipole moment. Without an electric field, the decay life of a singlet exciton is about 1 ns. Once an electric field is applied and exceeds a critical value, with electron-phonon coupling, the original lattice structure evolves into two new localized lattice distortions, consistent with the experimental results. Owing to the new lattice structure and self-trapping, the dipole moment rapidly decreases to zero within 5 fs, eliminating the radiative decay of the singlet exciton.

  12. Intramolecular sensitization of americium luminescence in solution: shining light on short-lived forbidden 5f transitions.

    Science.gov (United States)

    Sturzbecher-Hoehne, M; Yang, P; D'Aléo, A; Abergel, R J

    2016-06-14

    The photophysical properties and solution thermodynamics of water soluble trivalent americium (Am(III)) complexes formed with multidentate chromophore-bearing ligands, 3,4,3-LI(1,2-HOPO), Enterobactin, and 5-LIO(Me-3,2-HOPO), were investigated. The three chelators were shown to act as antenna chromophores for Am(III), generating sensitized luminescence emission from the metal upon complexation, with very short lifetimes ranging from 33 to 42 ns and low luminescence quantum yields (10(-3) to 10(-2)%), characteristic of Near Infra-Red emitters in similar systems. The specific emission peak of Am(III) assigned to the (5)D1 → (7)F1 f-f transition was exploited to characterize the high proton-independent stability of the complex formed with the most efficient sensitizer 3,4,3-LI(1,2-HOPO), with a log β110 = 20.4 ± 0.2 value. In addition, the optical and solution thermodynamic features of these Am(III) complexes, combined with density functional theory calculations, were used to probe the influence of electronic structure on coordination properties across the f-element series and to gain insight into ligand field effects.

  13. Measurement of the radiative lifetime of the 2s(2)2p(4) (1)S(0) metastable level of neon; a study of forbidden transitions of astrophysical interest

    Science.gov (United States)

    Daw, Adrian Nigel

    The radiative lifetime of the 2s22 p4 1S0 metastable level of Ne2+ (Ne III) has been measured to be 223 +/- 11 ms at the 90% confidence level by observing the photons emitted at 1815 Å (181.5 nm) by a decaying population of 1 S0 Ne2+ ions stored in a radio frequency ion trap. This thesis describes the first use of a method to account for any ions lost from the trap and determine the radiative lifetime. Metastable ions were produced by electron bombardment of Ne gas, and rate coefficients for Ne2+ + Ne collisions were also determined. The lifetime measurement is in good agreement with recent calculated values, and has a lower uncertainty than the calculated values. This is the first lifetime measurement for an excited term of a ground configuration ion in the second row of the periodic table. The transition probabilities (A-values) for the forbidden transitions in the ground configurations of these ions are required for astrophysical spectral line intensity ratio diagnostics. Using calculated branching ratios, we estimate that, at the 90% confidence level, A(3P1 - 1S0) = 1.94 +/- 0.17 s-1 for the forbidden line of Ne III at 1815 Å, and A(1D2 - 1S0) = 2.55 +/- 0.19 s-1 for the forbidden line of Ne III at 3344 Å.

  14. Enabling Forbidden Dark Matter

    OpenAIRE

    Cline, James; Liu, Hongwan; Slatyer, Tracy; Xue, Wei

    2017-01-01

    The thermal relic density of dark matter is conventionally set by two-body annihilations. We point out that in many simple models, $3 \\to 2$ annihilations can play an important role in determining the relic density over a broad range of model parameters. This occurs when the two-body annihilation is kinematically forbidden, but the $3\\to 2$ process is allowed; we call this scenario "Not-Forbidden Dark Matter". We illustrate this mechanism for a vector portal dark matter model, showing that fo...

  15. Beta relaxation of nonpolymeric liquids close to the glass transition

    DEFF Research Database (Denmark)

    Olsen, Niels Boye; Christensen, Tage Emil; Dyre, Jeppe

    2000-01-01

    Dielectric beta relaxation in a pyridine-toluene solution is studied close to the glass transition. Loss peak frequency and maximum loss both exhibit thermal hysteresis. An annealing-state-independent parameter involving loss and loss peak frequency is identified. This parameter has a simple Arrh...... Arrhenius temperature dependence. The same behavior is found for four other viscous liquids, indicating that the phenomenon is possibly general....

  16. The Forbidden Quantum Adder

    Science.gov (United States)

    Alvarez-Rodriguez, U.; Sanz, M.; Lamata, L.; Solano, E.

    2015-01-01

    Quantum information provides fundamentally different computational resources than classical information. We prove that there is no unitary protocol able to add unknown quantum states belonging to different Hilbert spaces. This is an inherent restriction of quantum physics that is related to the impossibility of copying an arbitrary quantum state, i.e., the no-cloning theorem. Moreover, we demonstrate that a quantum adder, in absence of an ancillary system, is also forbidden for a known orthonormal basis. This allows us to propose an approximate quantum adder that could be implemented in the lab. Finally, we discuss the distinct character of the forbidden quantum adder for quantum states and the allowed quantum adder for density matrices. PMID:26153134

  17. Decay times of the spin-forbidden and spin-enabled transitions of Yb(2+) doped in CsCaX3 and CsSrX3 (X = Cl, Br, I).

    Science.gov (United States)

    Suta, Markus; Senden, Tim; Olchowka, Jacob; Adlung, Matthias; Meijerink, Andries; Wickleder, Claudia

    2017-03-08

    In this paper, a systematic study of the decay times of the spin-enabled and spin-forbidden transitions of Yb(2+) doped into the halidoperovskites CsMX3 (M = Ca, Sr; X = Cl, Br, I) is presented. The spin-forbidden transitions are characterized by ms decay times, which are typical for Yb(2+). On the contrary, the spin-enabled transitions show much shorter decay times in the range of μs and have so far only been rarely observed. These results allow detailed conclusions about systematics of the decay times of Yb(2+) doped in similar compounds and their correlation to the local structure of the coordination sphere of Yb(2+) as well as the role of vibrational interaction between the excited high spin (HS) and low spin (LS) states. The halidoperovskites are ideally suited as host lattices in this context and may work as text book examples due to their comparable structures, which allows a detailed interpretation of the decay times in relation to the local structure. An understanding of the impact of the composition and structure of the host material on the decay times of Yb(2+) will be of relevance for future applications of this activator in scintillators or lighting materials.

  18. Double Resonance Sub-Doppler Study of the Allowed and DeltaK = -3 Forbidden Q(3, 3) Transitions to the nu2 Vibrational State of 14NH3.

    Science.gov (United States)

    Fichoux; Khelkhal; Rusinek; Legrand; Herlemont; Urban

    1998-11-01

    The IR-IR sub-Doppler double resonance and standard saturation sideband spectroscopy have been used to measure the allowed and Deltak = -3 forbidden transitions to the nu2 vibrational level of 14NH3. The IR-IR double resonance technique has made it possible to observe quadrupole hyperfine structures which correspond to the sums as well as differences of the -3Q(3, 3) and Q(3, 3) hyperfine components. The "sum" and "difference" double resonance frequencies have been measured with accuracy better than 30 and 5 kHz, respectively. In addition to this, the hyperfine structure of the allowed Q(3, 3) transition has been independently measured using the "standard" saturation sideband spectroscopy with accuracy better than 15 kHz. A simultaneous analysis of all measured data provides an improved set of effective nuclear quadrupole and spin-rotation parameters for the excited nu2 vibrational state and frequencies of the "pure" rotation-vibration transitions deperturbed from the hyperfine effects at the experimental sample pressure of about 3 mTorr, including a very precise zero pressure value of the "forbidden" spacing between energies of the nu2 ||s, J = 3, K = 3> and ||s, J = 3, K = 0> pure rotational levels of 2883.6795(19) MHz [0.096189194(63) cm-1]. Copyright 1998 Academic Press.

  19. Decay law of allowed and forbidden transitions inβ--decay half-lives%β-衰变中容许跃迁和禁戒跃迁的衰变规律∗

    Institute of Scientific and Technical Information of China (English)

    张绍庆; 谢娟; 张小平; 支启军

    2016-01-01

    β-decay half-lives are not only important parameters for studying the structures and decay properties of the exotic nucleus far from stability, but also basic parameters for understanding the astrophysical phenomenon. Astrophysicists need exact data ofβ-decay half-lives as input to build nucleosynthesis models for understanding the elements abundances of our universe and solar system. For nuclei far from stability, experimental synthesis and further measurements on their half-lives are rather difficult due to the rarity and radioactivity of target material for synthesizing these nuclei. In theoretical respect, although there are many models such as finite-range droplet model plus quasi-particle random-phase approximation (QRPA), microscopic density functional theory plus QRPA, Hatree-Fock-Bogoliubov theory plus QRPA, and shell model etc., it is still a challenge to calculate β-decay half-lives in a reliable way for nuclei far from the β-stable line, partly because of the intrinsic complexity of nuclear multi-body problem. In empirical respect, Sargent made an empirical study of β-decay half-lives in 1933 and discovered a law which is consistent with the Fermi β-decay theory proposed one year later. From then on, there have been a few parametric models based on some of real physical behaviors, which describe complex quantum many-body systems, such as the Kratz–Herrmann formula and the gross theory. Recently, Zhang et al. discovered an exponential law describing β-decay half-lives and the nucleon number (Z, N ) of parent nuclei far from the stable line. A formula is proposed to calculate the β-decay half-lives of nuclei far from stability, which can describe experimental data reasonably well. However, the differences between allowed transitions and forbidden transitions are not fully considered in this formula. Zhang et al. used a set of parameters to describe both allowed transitions and forbidden transitions. In this paper, we consider the different

  20. The Forbidden Signs

    DEFF Research Database (Denmark)

    Kilstrup, Mogens

    2016-01-01

    is an important addition that offers insight into the hardware requirements for bio-semiosis. As any type of semiosis must be dependent upon Semiotic scaffolds, I recently argued that the process of semiosis has to be divided into two separate processes of sign establishment and sign interpretation....... I also show that biological semiosis offers examples of forbidden signs, where the faulty interpretation of signs may lead to decimation of whole evolutionary lines of organisms. A new concept of Evolutionary memory which is applicable to both human and biological semiosis is explained...

  1. Calculation of parity violating effects in the 6/sup 2/P/sub 1/2/-7/sup 2/P/sub 1/2/ forbidden M1 transition in thallium. [E1 amplitude, circular dichroism, parity violation, hyperfine structure

    Energy Technology Data Exchange (ETDEWEB)

    Neuffer, D.B.

    1977-05-01

    Calculations are presented of the E1 amplitude expected in forbidden M1 transitions of Tl and Cs if parity is violated in the neutral weak e-N interaction, as proposed in a number of gauge models, including that of Weinberg and Salam. Valence electron wave functions are generated as numerical solutions to the Dirac equation in a modified Tietz central potential. These wave functions are used to calculate allowed E1 transition rates, hfs splittings, and Stark E1 transition ampitudes. These results are compared with experiment and the agreement is generally good. The relativistic Tl 6/sup 2/P/sub 1/2/-7/sup 2/P/sub 1/2/ M1 transition amplitude M is also calculated, and corrections due to interconfiguration interaction, Breit interaction, and hfs mixing are included. The parity violating E1 amplitude E/sub PV/ is calculated and a value for the circular dichroism in the Weinberg model delta = -2.6 x 10/sup -3/ is obtained. Parity violating effects in other Tl transitions are discussed. Contributions to the M1 amplitude for the forbidden Cs 6/sup 2/S/sub 1/2/-7/sup 2/S/sub 1/2/ and 6/sup 2/S/sub 1/2/-8/sup 2/S/sub 1/2/ transitions and to the Cs 6/sup 2/S/sub 1/2/ g-factor anomaly from relativistic effects, Breit interaction, interconfiguration interaction, and hfs mixing are calculated, and it is found that this current theoretical description is not entirely adequate. The parity violating E1 amplitude E/sub PV/ for the 6S/sub 1/2/-7/sup 2/S/sub 1/2/ and 6S/sub 1/2/-8/sup 2/S/sub 1/2/ transitions is evaluated. With a measured value M/sub expt/ and the Weinberg value Q/sub W/ = -99, a circular dichroism delta = 1.64 x 10/sup -4/ for the 6/sup 2/S/sub 1/2/-7/sup 2/S/sub 1/2/ transition is found.

  2. The Forbidden Quantum Adder

    CERN Document Server

    Alvarez-Rodriguez, U; Lamata, L; Solano, E

    2014-01-01

    Addition plays a central role in mathematics and physics, while adders are ubiquitous devices in computation and electronics. In this sense, usual sum operations can be realized by classical Turing machines and also, with a suitable algorithm, by quantum Turing machines. Moreover, the sum of state vectors in the same Hilbert space, known as quantum superposition, is at the core of quantum physics. In fact, entanglement and the promised exponential speed-up of quantum computing are based on such superpositions. Here, we consider the existence of a quantum adder, defined as a unitary operation mapping two unknown quantum states encoded in different quantum systems onto their sum codified in a single one. The surprising answer is that this quantum adder is forbidden and it has the quantum cloning machine as a special case. This no-go result is of fundamental nature and its deep implications should be further studied.

  3. Recent status of the studies of nuclear masses and {beta}-decay

    Energy Technology Data Exchange (ETDEWEB)

    Yamada, Masami [Waseda Univ., Tokyo (Japan). Advanced Research Center for Science and Engineering

    1996-05-01

    The recent status of the above studies was explained, especially, nuclear masses were described from the aspect of probability theory and that of {beta}-decay suggested that the first forbidden transition was hindered between the ground states. We have to study various systematics in order to know the mass surface, Way-Yamada-Matumoto type systematics is better to check the experimental nuclear masses. The gross theory is very useful to understand the general aspect of {beta}-decay. The understanding method of mass surface, systematic check of mass and hindrance of the first forbidden transition at rank 1 were explained. (S.Y.)

  4. Absolute Intensities Measurements in the nu(4) + nu(5) Band of (12)C(2)H(2): Analysis of Herman-Wallis Effects and Forbidden Transitions.

    Science.gov (United States)

    Vander Auwera J

    2000-05-01

    We measured absolute line intensities in two bands of (12)C(2)H(2) near 7.5 µm, namely the nu(4) + nu(5)(Sigma(+)(u))-0(Sigma(+)(g)) and nu(4) + nu(5)(Delta(u))-0(Sigma(+)(g)) bands, using Fourier transform spectroscopy with an accuracy estimated to be better than 2%. Using theoretical predictions from Watson [J. K. G. Watson, J. Mol. Spectrosc. 188, 78 (1998)], the observation of the forbidden nu(4) + nu(5)(Delta(u))-0(Sigma(+)(g)) band and the Herman-Wallis behavior exhibited by its rotational lines were studied quantitatively in terms of two types of interactions affecting the levels involved by the band: l-type resonance and Coriolis interaction. In the case of the nu(4) + nu(5)(Sigma(+)(u))-0(Sigma(+)(g)) band, the influence of l-type resonance is also confirmed. We also attributed the intensity asymmetry observed between the R and P branches of that latter band to a Coriolis interaction with l = 1 levels. We did not observe the nu(4) + nu(5)(Sigma(-)(u))-0(Sigma(+)(g)) band, consisting only of a Q branch, in agreement with Watson's prediction. Copyright 2000 Academic Press.

  5. A Forbidden Web in a Quasi-Dissipative System

    Institute of Scientific and Technical Information of China (English)

    DAI Jun; WANG Wen-Xiu; JIANG Yu-Mei; HE Yue; CHEN Wen; HE Da-Ren

    2005-01-01

    @@ A simultaneous transition of the system nature from everywhere smooth and conservative to piecewise smooth and quasi-dissipative is observed in a kicked billiard when adjusting single controlling parameter.The transition induces the appearance of a special kind of fat fractal forbidden web, which grows up and cuts off more parts from the original conservative stochastic web so that the remnant transient web becomes increasingly thinner.We numerically show a power law σ∝βν, where σ is the fractal exponent of the forbidden web,β is the control parameter, and the scaling exponent ν = 0.288 ± 0.007, which describes this process.

  6. Forbidden second order optical nonlinearity of graphene

    CERN Document Server

    Cheng, J L; Sipe, J E

    2016-01-01

    We present a practical scheme to separate the contributions of the electric quadrupole-like and the magnetic dipole-like effects to the forbidden second order optical nonlinear response of graphene, and give analytic expressions for the second order optical conductivities, calculated from the independent particle approximation, with relaxation described in a phenomenological way. We predict strong second order nonlinear effects, including second harmonic generation, photon drag, and difference frequency generation. We discuss in detail the controllablity of these responses by tuning the chemical potential, where the interband optical transitions play a dominant role.

  7. Ab Initio Multiple Spawning Method for Intersystem Crossing Dynamics: Spin-Forbidden Transitions between (3)B1 and (1)A1 States of GeH2.

    Science.gov (United States)

    Fedorov, Dmitry A; Pruitt, Spencer R; Keipert, Kristopher; Gordon, Mark S; Varganov, Sergey A

    2016-05-12

    Dynamics at intersystem crossings are fundamental to many processes in chemistry, physics, and biology. The ab initio multiple spawning (AIMS) method was originally developed to describe internal conversion dynamics at conical intersections where derivative coupling is responsible for nonadiabatic transitions between electronic states with the same spin multiplicity. Here, the applicability of the AIMS method is extended to intersystem crossing dynamics in which transitions between electronic states with different spin multiplicities are mediated by relativistic spin-orbit coupling. In the direct AIMS dynamics, the nuclear wave function is expanded in the basis of frozen multidimensional Gaussians propagating on the coupled electronic potential energy surfaces calculated on the fly. The AIMS method for intersystem crossing is used to describe the nonadiabatic transitions between the (3)B1 and (1)A1 states of GeH2. The potential energies and gradients were obtained at the CASSCF(6,6)/6-31G(d) level of theory. The spin-orbit coupling matrix elements were calculated with the configuration interaction method using the two-electron Breit-Pauli Hamiltonian. The excited (3)B1 state lifetime and intersystem crossing rate constants were estimated by fitting the AIMS state population with the first-order kinetics equation for a reversible unimolecular reaction. The obtained rate constants are compared with the values predicted by the statistical nonadiabatic transition state theory with transition probabilities calculated using the Landau-Zener and weak coupling formulas.

  8. Spin-orbit relativistic long-range corrected time-dependent density functional theory for investigating spin-forbidden transitions in photochemical reactions.

    Science.gov (United States)

    Nakata, Ayako; Tsuneda, Takao; Hirao, Kimihiko

    2011-12-14

    A long-range corrected (LC) time-dependent density functional theory (TDDFT) incorporating relativistic effects with spin-orbit couplings is presented. The relativistic effects are based on the two-component zeroth-order regular approximation Hamiltonian. Before calculating the electronic excitations, we calculated the ionization potentials (IPs) of alkaline metal, alkaline-earth metal, group 12 transition metal, and rare gas atoms as the minus orbital (spinor) energies on the basis of Koopmans' theorem. We found that both long-range exchange and spin-orbit coupling effects are required to obtain Koopmans' IPs, i.e., the orbital (spinor) energies, quantitatively in DFT calculations even for first-row transition metals and systems containing large short-range exchange effects. We then calculated the valence excitations of group 12 transition metal atoms and the Rydberg excitations of rare gas atoms using spin-orbit relativistic LC-TDDFT. We found that the long-range exchange and spin-orbit coupling effects significantly contribute to the electronic spectra of even light atoms if the atoms have low-lying excitations between orbital spinors of quite different electron distributions.

  9. Spin-forbidden transitions in the vicinity of the 2 (1)pi(u) <-- X (1)sigma(g)+ band system of Rb2.

    Science.gov (United States)

    Lee, Yonghoon; Lee, Sungyul; Kim, Bongsoo

    2008-07-31

    We have investigated the Rb2 475 nm system by resonance enhanced two-photon ionization spectroscopy in a pulsed molecular beam. Strong extra bands accompanying the 2 (1)Pi(u) v' = 5 - 8 transitions observed in this spectral region, intensity borrowing was most effective when the 2 (3)Pi(u)(1 u) levels were close to the 3 (3)Sigma(u)(+)(1 u) levels. A deperturbation fit for the perturbing bands has provided the 2 (1)Pi(u)-3 (3)Sigma(u)(+)(1 u) coupling constants.

  10. An Upper Bound on the Strongly Forbidden $6S_{1/2} \\leftrightarrow 5D_{3/2}$ Magnetic Dipole Transition Moment in {Ba}$^{+}$

    CERN Document Server

    Williams, Spencer R; Hoffman, Matthew R; Blinov, Boris B; Fortson, E N

    2016-01-01

    We report the results from our first-generation experiment to measure the magnetic-dipole transition moment (M1) between the $6S_{1/2}$ and $5D_{3/2}$ manifolds in Ba$^{+}$. Knowledge of M1 is crucial for the proposed parity-nonconservation experiment in the ion \\cite{Fortson93}, where M1 will be a leading source of systematic error. To date, no measurement of M1 has been made in Ba$^{+}$, and moreover, the sensitivity of the moment to electron-electron correlations has confounded accurate theoretical predictions. A precise measurement may help to resolve the theoretical discrepancies while providing essential information for planning a future PNC measurement in Ba$^{+}$. We demonstrate our technique for measuring M1 - including a method for calibrating for stress-induced birefringence introduced by the scientific apparatus - and place an upper bound of $\\mathrm{M1} < 93 \\pm 39 \\times 10^{-5} \\mu_{B}$.

  11. Search for the CP forbidden decay eta-->4pi(0)

    Science.gov (United States)

    Prakhov; Tippens; Allgower; Bekrenev; Berger; Briscoe; Clajus; Comfort; Craig; Grosnick; Huber; Isenhower; Knecht; Koetke; Koulbardis; Kozlenko; Kruglov; Kycia; Lolos; Lopatin; Manley; Marusic; Manweiler; McDonald; Nefkens; Olmsted

    2000-05-22

    We report the first determination of the upper limit for the branching ratio of the CP forbidden decay eta-->4pi(0). No events were observed in a sample of 3.0x10(7) eta decays. The experiment was performed with the Crystal Ball multiphoton spectrometer installed in a separated pi(-) beam at the AGS (Alternating Gradient Synchrotron). At the 90% confidence limit, B(eta-->4pi(0))

  12. ``Forbidden'' phonon in the iron chalcogenide series

    Science.gov (United States)

    Fobes, David M.; Zaliznyak, Igor A.; Xu, Zhijun; Gu, Genda; Tranquada, John M.

    2015-03-01

    Recently, we uncovered evidence for the formation of a bond-order wave (BOW) leading to ferro-orbital order at low temperature, acting to stabilize the bicollinear AFM order, in the iron-rich parent compound, Fe1+yTe. Investigating the inelastic spectra centered near (100) in Fe1+yTe, a signature peak for the BOW formation in the monoclinic phase, we observed an acoustic phonon dispersion in both tetragonal and monoclinic phases. While a structural Bragg peak accompanies the mode in the monoclinic phase, in the tetragonal phase Bragg scattering at this Q is forbidden by symmetry, and we observed no elastic peak. This phonon mode was also observed in superconducting FeTe0.6Se0.4, where structural and magnetic transitions are suppressed. LDA frozen phonon calculations suggested that this mode could result from a spin imbalance between neighboring Fe atoms, but polarized neutron measurements revealed no additional magnetic scattering. We propose that this ``forbidden'' phonon mode may originate from dynamically broken symmetry, perhaps related to the strong dynamic spin correlations in these materials. Work at BNL was supported by BES, US DOE, under Contract No. DE-AC02-98CH10886. Research at ORNL's HFIR and SNS sponsored by Scientific User Facilities Division, BES, US DOE. We acknowledge the support of NIST, in providing neutron research facilities.

  13. Systematic comparison of beta spectra calculations using improved analytical screening correction with experimental shape factors.

    Science.gov (United States)

    Mougeot, X

    2016-03-01

    From a review of the available literature, a database of experimental shape factors from measured beta spectra was created in previous work. Classical assumptions applied in beta spectra calculations which avoid the determination of the electron and nuclear wave functions were tested by comparison with each measured spectrum present in the database. From this systematic comparison, it was demonstrated that the typical assumption λk=1 is inappropriate for all forbidden unique transitions. Moreover, the equally common ξ-approximation was also proved to be incorrect for about half of the listed first forbidden non-unique transitions and for all second non-unique ones. In present work, this study has been performed once again using an improved analytical screening correction. General results from previous study still remain the same. Except for allowed transitions, the mean energies in current nuclear databases are expected to be erroneous. Some selected beta spectra are also given to illustrate these results.

  14. Microscopic study of muon-capture transitions in nuclei involved in double-beta-decay processes

    CERN Document Server

    Kortelainen, M

    2003-01-01

    Total and partial ordinary muon-capture (OMC) rates to 1 sup + and 2 sup - states are calculated in the framework of the proton-neutron quasiparticle random-phase approximation (pnQRPA) for several nuclei involved in double-beta-decay processes. The aim is to obtain information on intermediate states involved in double-beta-decay transitions having these nuclei as either daughter or parent nuclei. It is found that the OMC observables, just like the 2 nu beta beta-decay amplitudes, strongly depend on the particle-particle part of the proton-neutron interaction. First experiments measuring the partial OMC rates for nuclei involved in double beta decays have recently been performed.

  15. Anecdotes of the Forbidden City

    Institute of Scientific and Technical Information of China (English)

    ZUOYUANBO; ZHANGXUEYING

    2005-01-01

    Everyone who passes through Beijing's Forbidden City leaves the grounds with two words on their lips: magnificent and awe-inspiring. The seat of imperial power during the Ming and Qing dynasties (1368 - 1911), some twenty-four emperors ruled the nation from within these walls. Now more commonly known as the Palace Museum, the Forbidden City lies at the center of the Chinese capital. Extending 750 meters from east to west and 960 meters from north to south, the 720,000-square-meter city is the largest palatial complex in the world. Guarding the city is a 52-meter-wide, six-meter-deep moat, and a huge wall, which runs three kilometers around the city and stands 10 meters high. Construction lasted 15 years, involving 100,000 artisans and some one million civilians. If the bricks that make up the Forbidden City could speak, they would have many an interesting story to tell. Here are just a few anecdotes.

  16. Signatures of transition region explosive events in hydrogen Ly-beta profiles

    CERN Document Server

    Zhang, M; Tian, H; Chen, Y

    2010-01-01

    We search for signatures of transition region explosive events (EEs) in hydrogen Ly-beta profiles. Two rasters made by the SUMER (Solar Ultraviolet Measurements of Emitted Radiation) instrument on board SOHO in a quiet-Sun region and an equatorial coronal hole are selected for our study. Transition region explosive events are identified from profiles of C II 1037 Angstrom and O VI 1032 Angstrom, respectively. We compare Ly-beta profiles during EEs with those averaged in the entire quiet-Sun and coronal-hole regions. The relationship between the peak emission of Ly-beta profiles and the wing emission of C II and O VI during EEs is investigated. We find that the central part of Ly-beta profiles becomes more reversed and the distance of the two peaks becomes larger during EEs, both in the coronal hole and in the quiet Sun. The average Ly-beta profile of the EEs detected by C II has an obvious stronger blue peak. During EEs, there is a clear correlation between the increased peak emission of Ly-beta profiles and ...

  17. IL-1 beta and TGF beta 2 synergistically induce endothelial to mesenchymal transition in an NF kappa B-dependent manner

    NARCIS (Netherlands)

    Maleszewska, Monika; Moonen, Jan-Renier A. J.; Huijkman, Nicolette; van de Sluis, Bart; Krenning, Guido; Harmsen, Martin C.

    2013-01-01

    Endothelial to mesenchymal transition (EndMT) contributes to fibrotic diseases. The main inducer of EndMT is TGF beta signaling. TGF beta 2 is the dominant isoform in the physiological embryonic EndMT, but its role in the pathological EndMT in the context of inflammatory co-stimulation is not known.

  18. Preliminary study of feasibility of an experiment looking for excited state double beta transitions in Tin

    CERN Document Server

    Das, Soumik; Raina, P K; Singh, A K; Rath, P K; Cappella, F; Cerulli, R; Laubenstein, M; Belli, P; Bernabei, R

    2015-01-01

    A first attempt to study the feasibility of an experiment to search for double beta decay in $^{124}$Sn and $^{112}$Sn was carried out by using ultra-low background HPGe detector (244 cm$^{3}$) inside the Gran Sasso National Laboratory (LNGS) of the INFN (Italy). A small sample of natural Sn was examined for 2367.5 h. The radioactive contamination of the sample has been estimated. The data has also been considered to calculate the present sensitivity for the proposed search; half-life limits $\\sim$ $10^{17} - 10^{18}$ years for $\\beta^{+}$EC and EC-EC processes in $^{112}$Sn and $\\sim$ $10^{18}$ years for $\\beta^{-}\\beta^{-}$ transition in $^{124}$Sn were measured. In the last section of the paper the enhancement of the sensitivity for a proposed experiment with larger mass to reach theoretically estimated values of half-lives is discussed.

  19. Thermally Induced Alpha-Helix to Beta-Sheet Transition in Regenerated Silk Fibers and Films

    Energy Technology Data Exchange (ETDEWEB)

    Drummy,L.; Phillips, D.; Stone, M.; Farmer, B.; Naik, R.

    2005-01-01

    The structure of thin films cast from regenerated solutions of Bombyx mori cocoon silk in hexafluoroisopropyl alcohol (HFIP) was studied by synchrotron X-ray diffraction during heating. A solid-state conformational transition from an alpha-helical structure to the well-known beta-sheet silk II structure occurred at a temperature of approximately 140 degrees C. The transition appeared to be homogeneous, as both phases do not coexist within the resolution of the current study. Modulated differential scanning calorimetry (DSC) of the films showed an endothermic melting peak followed by an exothermic crystallization peak, both occurring near 140 degrees C. Oriented fibers were also produced that displayed this helical molecular conformation. Subsequent heating above the structural transition temperature produced oriented beta-sheet fibers very similar in structure to B. mori cocoon fibers. Heat treatment of silk films at temperatures well below their degradation temperature offers a controllable route to materials with well-defined structures and mechanical behavior.

  20. Computer simulation of reactions in beta-cyclodextrin molecular reactors: transition state recognition.

    Science.gov (United States)

    Yeguas, Violeta; López, Ramón; Lambert, Alexandrine; Monard, Gérald; Ruiz-López, Manuel F

    2010-10-07

    Cyclodextrins have attracted much interest in recent years because of their potential use as molecular reactors allowing organic reactions in aqueous solution. To better understand their effect on reaction mechanisms, we have carried out a computational study of a prototypical process (neutral ester hydrolysis) in a beta-cyclodextrin (beta-CD). Two models have been used for the reactor. The first and simpler one assumes that the medium can be described by a polarizable dielectric continuum. The second one takes into account the discrete nature of the beta-CD and water molecules thanks to a computational approach that combines the use of Quantum Mechanics, Molecular Mechanics and Molecular Dynamics techniques. We focus on neutral pH processes for which either acceleration or inhibition has experimentally been observed depending on ester derivatives. Our calculations rationalize such observations by showing that the two reaction mechanisms usually invoked for hydrolysis, stepwise (involving two transitions states with formation of a -C(OH)(2)OR tetrahedral intermediate) and concerted, undergo opposite effects in the beta-CD environment. The results highlight the role played by molecular shape recognition. Thus, in spite of a higher polarity exhibited by the three transition states with respect to the reactants, the interactions with the beta-CD cavity may either increase or decrease the activation barrier due to different 3D-arrangements of the chemical structures.

  1. 49 CFR 173.54 - Forbidden explosives.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 2 2010-10-01 2010-10-01 false Forbidden explosives. 173.54 Section 173.54... SHIPMENTS AND PACKAGINGS Definitions, Classification and Packaging for Class 1 § 173.54 Forbidden explosives. Unless otherwise provided in this subchapter, the following explosives shall not be offered for...

  2. Symmetry forbidden vibronic spectra and internal conversion in benzene.

    Science.gov (United States)

    Li, Jun; Lin, Chih-Kai; Li, Xiang Yuan; Zhu, Chao Yuan; Lin, Sheng Hsien

    2010-12-07

    The spectra of symmetry-forbidden transitions and internal conversion were investigated in the present work. Temperature dependence was taken into account for the spectra simulation. The vibronic coupling, essential in the two processes, was calculated based on the Herzberg-Teller theory within the Born-Oppenheimer approximation. The approach was employed for the symmetry-forbidden absorption/fluorescence, and internal conversion between 1(1)A(1g) and 1(1)B(2u) states in benzene. Vibrational frequencies, normal coordinates, electronic transition dipole moments, and non-adiabatic coupling matrix elements were obtained by ab initio quantum chemical methods. The main peaks, along with the weak peaks, were in good agreement with the observed ones. The rate constant of the 1(1)A(1g)← 1(1)B(2u) internal conversion was estimated within the order of 10(3) s(-1). This could be regarded as the lower limit (about 4.8 × 10(3) s(-1)) of the internal conversion. It is stressed that the distortion effect was taken into account both in the symmetry-forbidden absorption/fluorescence, and the rate constants of internal conversion in the present work. The distortion effects complicate the spectra and increase the rate constants of internal conversion.

  3. Isophotes of a field in the Cygnus Loop photographed in the forbidden O III and forbidden N II + H-alpha lines

    Science.gov (United States)

    Sitnik, T. G.; Toropova, M. S.

    1982-12-01

    From interference-filter image-tube photographs of a 9 arc min field in the western part of the Cygnus Loop supernova remnant, taken in the 5007 forbidden O III and 6584, 6563 forbidden N II + H-alpha lines, sets of isophotes are derived by an equidensitometry technique based on the Sabattier effect. The emission regions in these lines exhibit a relatively displacement, interpreted as evidence for radiative cooling of the gas behind the shock generated in the supernova outburst. An explanation is offered for the differing morphology of the nebular filaments in the forbiddden O III and forbidden N II + H-alpha lines. The anomalously high I (O III)/I(H-beta) intensity ratio may reflect a spatial separation of the corresponding emission zones.

  4. Search for $\\beta$-transitions with the lowest decay energy for a determination of the neutrino mass

    CERN Multimedia

    From a variety of $\\beta$-transitions only those with decay energies of a few keV and smaller are considered suitable for a determination of the neutrino mass on a sub-eV level. The decay energy of a transition can be very small, if, e.g., in an allowed $\\beta$-decay or electron-capture transition, a nuclear excited state of the daughter nuclide is populated whose energy is very close to the mass difference of the transition nuclides. Investigation of these transitions can also be useful for the assessment of a validity of the current $\\beta$-decay theory in the region of vanishingly small decay energies. The authors of this proposal have found several such $\\beta$-transitions whose decay energies are expected to be extremely small. In order to assess the suitability of these $\\beta$-transitions for the determination of the neutrino mass, measurements of the mass differences of the transition nuclides must be carried out with a sub-keV uncertainty. Presently, only high-precision Penning-trap mass spectrometry...

  5. First principles calculation of mixing enthalpy of {beta}-Ti with transition elements

    Energy Technology Data Exchange (ETDEWEB)

    Chandran, Mahesh, E-mail: Mahesh.chandran@ge.com [GE Global Research, John F Welch Technology Centre, Bangalore 560066 (India); Subramanian, P.R.; Gigliotti, Michael F. [GE Global Research, 1 Research Circle, Niskayuna, NY 12309 (United States)

    2013-02-15

    Highlights: Black-Right-Pointing-Pointer Compares the accuracy of SQS with parametric method to determine {Delta}H for binary alloys which has not been done before. Black-Right-Pointing-Pointer Trends in {Delta}H for {beta}-Ti-X alloys where X is 3d-, 4d- and 5d-transition series are presented. Black-Right-Pointing-Pointer The design space for new {beta}-Ti alloys is determined by combining {Delta}H with Hume-Rothery rules. - Abstract: The mixing enthalpy {Delta}H{sub mix}(x) of body-centered cubic (BCC) {beta}-Ti with transition elements was calculated using first-principles methods based on density functional theory (DFT). The solid solution effect was treated by two different approaches, viz. special quasi-random structures (SQS) and the parametric method. The SQS-N method uses direct DFT to calculate energy of structures containing N atoms which approximate the correlation of an ideal solid solution up to some distance, whereas the parametric method employs a polynomial representation for {Delta}H{sub mix}(x) and the coefficients are calculated using DFT. Comparison of the two methods shows fair agreement for most alloys though differences as high as 40% can also be seen among some of the alloys. The trends in {Delta}F{sub mix}(x), obtained by adding entropy contribution from ideal solution model to {Delta}H{sub mix}(x) for 3d-, 4d- and 5d-transition series were analyzed in terms of e/a, the ratio of number of valence electrons to atoms. The early transition elements, between Group 4-7, was found to have very small {Delta}F{sub mix}(x) over a wide range of concentration. Stability of the alloys is analyzed by combining {Delta}F{sub mix}(x) with Hume-Rothery rules.

  6. SOX4 Mediates TGF-beta-Induced Expression of Mesenchymal Markers during Mammary Cell Epithelial to Mesenchymal Transition

    NARCIS (Netherlands)

    Vervoort, Stephin J.; Lourenco, Ana Rita; van Boxtel, Ruben; Coffer, Paul J.

    2013-01-01

    The epithelial to mensenchymal transition program regulates various aspects of embryonic development and tissue homeostasis, but aberrant activation of this pathway in cancer contributes to tumor progression and metastasis. TGF-beta potently induces an epithelial to mensenchymal transition in cancer

  7. Connecting the X(5)-$\\beta^2$, X(5)-$\\beta^4$, and X(3) models to the shape/phase transition region of the interacting boson model

    CERN Document Server

    McCutchan, E A; Zamfir, N V; Bonatsos, Dennis

    2006-01-01

    The parameter independent (up to overall scale factors) predictions of the X(5)-$\\beta^2$, X(5)-$\\beta^4$, and X(3) models, which are variants of the X(5) critical point symmetry developed within the framework of the geometric collective model, are compared to two-parameter calculations in the framework of the interacting boson approximation (IBA) model. The results show that these geometric models coincide with IBA parameters consistent with the phase/shape transition region of the IBA for boson numbers of physical interest (close to 10). Nuclei within the rare-earth region and select Os and Pt isotopes are identified as good examples of X(3), X(5)-$\\beta^2$, and X(5)-$\\beta^4$ behavior.

  8. Radiative lifetimes of spin forbidden a1Δ → X3Σ- and spin allowed A3Π → X3Σ- transitions and complete basis set extrapolated ab initio potential energy curves for the ground and excited states of CH-.

    Science.gov (United States)

    Srivastava, Saurabh; Sathyamurthy, N

    2012-12-01

    The spin forbidden transition a(1)Δ → X(3)Σ(-) in CH(-) has been studied using the Breit-Pauli Hamiltonian for a large number of geometries. This transition acquires intensity through spin-orbit coupling with singlet and triplet Π states. The transition moment matrix including more than one singlet and triplet Π states was calculated at the multi-reference configuration interaction/aug-cc-pV6Z level of theory. The computed radiative lifetime of 5.63 s is in good agreement with the experimental (5.9 s) and other theoretical (6.14 s) results. Transition moment values of the spin allowed A(3)Π → X(3)Σ(-) transition have also been calculated at the same level of theory. Calculations show that the corresponding radiative lifetime is considerably low, 2.4 × 10(-7) s. Complete basis set extrapolated potential energy curves for the ground state of CH and the ground state and six low lying excited states (a(1)Δ, b(1)Σ(+), two (3)Π, and two (1)Π) of CH(-) are reported. These curves are then used to calculate the vibrational bound states for CH and CH(-). The computed electron affinity of CH supports the electron affinity bounds reported by Okumura et al. [J. Chem. Phys. 85, 1971 (1986)].

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

    Science.gov (United States)

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

    1995-01-01

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

  10. Contribution to the study of {beta} disintegration and of nuclear structure using experiments on certain {beta}-{gamma} cascades: 198{sub Au}, 86{sub Rb}, 170{sub Tm}; Contribution a l'etude de la desintegration beta et a l'etude de la structure nucleaire a l'aide d'experiences sur certaines cascades beta-gamma: 198{sub Au}, 86{sub Rb}, 170{sub Tm}

    Energy Technology Data Exchange (ETDEWEB)

    Lachkar, J. [Commissariat a l' Energie Atomique, Bruyeres-le-Chatel (France). Centre d' Etudes; Paris-11 Univ., fabulte des Sciences 91 - Orsay (France)

    1969-07-01

    {beta}{gamma} directional angular correlations and shapes of inner beta spectra leading to the first excited level of the final nucleus enable one to determine the nuclear matrix elements typical of the {beta} transition. In the three observed first forbidden cases: {sup 170}Tm, {sup 86}Rb, {sup 198}Au, these matrix elements do not confirm the independent shell model theory. Other hypotheses are then suggested and discussed. (author) [French] Les experiences de correlation angulaire {beta}{gamma} et l'etude du spectre {beta} conduisant au premier niveau excite du noyau final permettent de determiner les elements de matrices nucleaires caracteristiques de cette transition. Dans les trois cas etudies (transitions une fois interdites): {sup 170}Tm, {sup 86}Rb, {sup 198}Au, ces elements de matrices ne peuvent etre retrouves a l'aide du modele en couches et a particules independantes. D'autres hypotheses sont alors emises et discutees. (auteur)

  11. A Revised Scheme for the Beta Decay of 115-Day Ta182

    DEFF Research Database (Denmark)

    Hansen, P. Gregers; Nielsen, H. L.; Wilsky, K.

    1964-01-01

    V and not, as hitherto believed, to the 1222 keV level. The investigation has further revealed two new β components of higher energy: 591 keV (0.9±0.5% )and 1708 keV (0.05±0.01%). The 1708 keV transition represents a new example of K-forbidden 3−→2+ beta transitions in the rare-earth region.......A six-gap beta spectrometer, a xenon-filled proportional counter, scintillation equipment, and coincidence techniques have been used in a reinvestigation of the beta transitions to the known levels in W182. The main beta component of 522 keV (65%) is shown to proceed to the level at 1290 ke...

  12. Relativistic ab initio spectroscopy study of forbidden lines of singly ionized zinc

    NARCIS (Netherlands)

    Dixit, Gopal; Sahoo, Bijaya K.; Chaudhuri, Rajat K.; Majumder, Sonjoy

    2009-01-01

    The ab initio calculation has been carried out to study the astrophysically important forbidden electromagnetic transition rates of singly ionized zinc (Zn II). Electron correlations are considered to all orders using coupled-cluster theory in the relativistic framework. Calculated excitation energi

  13. Relativistic ab initio spectroscopy study of forbidden lines of singly ionized zinc

    NARCIS (Netherlands)

    Dixit, Gopal; Sahoo, Bijaya K.; Chaudhuri, Rajat K.; Majumder, Sonjoy

    2009-01-01

    The ab initio calculation has been carried out to study the astrophysically important forbidden electromagnetic transition rates of singly ionized zinc (Zn II). Electron correlations are considered to all orders using coupled-cluster theory in the relativistic framework. Calculated excitation

  14. Theoretical half-life for beta decay of {sup 96}Zr

    Energy Technology Data Exchange (ETDEWEB)

    Heiskanen, H; Mustonen, M T; Suhonen, J [Department of Physics, University of Jyvaeskylae, PO Box 35, FIN-40351, Jyvaeskylae (Finland)

    2007-05-15

    Highly forbidden {beta}{sup -} decay of the 0{sup +} ground state of {sup 96}Zr is studied. Partial half-lives to the lowest 6{sup +}, 5{sup +} and 4{sup +} states of {sup 96}Nb have been computed using the proton-neutron quasiparticle random-phase approximation (pnQRPA) with realistic two-body interactions in a large single-particle space. We find that the decay is dominated by the unique fourth-forbidden transition to the 5{sup +} state with the half-life 2.4 x 10{sup 20} y. This half-life is an order of magnitude longer than the one measured for the double beta decay of {sup 96}Zr.

  15. Order-disorder transition in conflicting dynamics leading to rank-frequency generalized beta distributions

    Science.gov (United States)

    Alvarez-Martinez, R.; Martinez-Mekler, G.; Cocho, G.

    2011-01-01

    The behavior of rank-ordered distributions of phenomena present in a variety of fields such as biology, sociology, linguistics, finance and geophysics has been a matter of intense research. Often power laws have been encountered; however, their validity tends to hold mainly for an intermediate range of rank values. In a recent publication (Martínez-Mekler et al., 2009 [7]), a generalization of the functional form of the beta distribution has been shown to give excellent fits for many systems of very diverse nature, valid for the whole range of rank values, regardless of whether or not a power law behavior has been previously suggested. Here we give some insight on the significance of the two free parameters which appear as exponents in the functional form, by looking into discrete probabilistic branching processes with conflicting dynamics. We analyze a variety of realizations of these so-called expansion-modification models first introduced by Wentian Li (1989) [10]. We focus our attention on an order-disorder transition we encounter as we vary the modification probability p. We characterize this transition by means of the fitting parameters. Our numerical studies show that one of the fitting exponents is related to the presence of long-range correlations exhibited by power spectrum scale invariance, while the other registers the effect of disordering elements leading to a breakdown of these properties. In the absence of long-range correlations, this parameter is sensitive to the occurrence of unlikely events. We also introduce an approximate calculation scheme that relates this dynamics to multinomial multiplicative processes. A better understanding through these models of the meaning of the generalized beta-fitting exponents may contribute to their potential for identifying and characterizing universality classes.

  16. Effect of first forbidden decays on the shape of neutrino spectra

    CERN Document Server

    Fang, Dong-Liang

    2015-01-01

    We examine the effect of First Forbidden (FF) decays on $\\beta$-decay neutrino spectra by performing microscopic nuclear structure calculations. By analyzing the FF decay branches of even-even nuclei we conclude that FF decays may be responsible for part of the missing neutrinos in the so called "Reactor Neutrino Anomaly". Further calculations and more experimental data are needed for a firm conclusion.

  17. Effects of chain length and Au spin-orbit coupling on 3(pi pi*) emission from bridging Cn2- units: theoretical characterization of spin-forbidden radiative transitions in metal-capped one-dimensional carbon chains [H3PAu(C[triple bond]C)nAuPH3].

    Science.gov (United States)

    Cao, Zexing; Zhang, Qianer

    2004-04-19

    Density functional theory and CASSCF calculations have been used to optimize the geometries of binuclear gold(I) complexes [H(3)PAu(C[triple bond]C)(n)AuPH(3)] (n=1-6) in their ground states and selected lowest energy (3)(pi pi*) excited states. Vertical excitation energies obtained by time-dependent density functional calculations for the spin-forbidden singlet-triplet transitions have exponential-decay size dependence. The predicted singlet-triplet splitting limit of [H(3)PAu(C[triple bond]C)(proportional/variant)AuPH(3)] is about 8317 cm(-1). Calculated singlet-triplet transition energies are in reasonable agreement with available experimental observations. The effect of the heavy atom Au spin-orbit coupling on the (3)(pi pi*) emission of these metal-capped one-dimensional carbon allotropes has been investigated by MRCI calculations. The contribution of the spin- and dipole-allowed singlet excited state to the spin-orbit-coupling wave function of the (3)(pi pi*) excited state makes the low-lying acetylenic triplet excited states become sufficiently allowed so as to appear in both electronic absorption and emission.

  18. Effect of graphene oxide on the conformational transitions of amyloid beta peptide: A molecular dynamics simulation study.

    Science.gov (United States)

    Baweja, Lokesh; Balamurugan, Kanagasabai; Subramanian, Venkatesan; Dhawan, Alok

    2015-09-01

    The interactions between nanomaterials (NMs) and amyloid proteins are central to the nanotechnology-based diagnostics and therapy in neurodegenerative disorders such as Alzheimer's and Parkinson's. Graphene oxide (GO) and its derivatives have shown to modulate the aggregation pattern of disease causing amyloid beta (Aβ) peptide. However, the mechanism is still not well understood. Using molecular dynamics simulations, the effect of graphene oxide (GO) and reduced graphene oxide (rGO) having carbon:oxygen ratio of 4:1 and 10:1, respectively, on the conformational transitions (alpha-helix to beta-sheet) and the dynamics of the peptide was investigated. GO and rGO decreased the beta-strand propensity of amino acid residues in Aβ. The peptide displayed different modes of adsorption on GO and rGO. The adsorption on GO was dominated by electrostatic interactions, whereas on rGO, both van der Waals and electrostatic interactions contributed in the adsorption of the peptide. Our study revealed that the slight increase in the hydrophobic patches on rGO made it more effective inhibitor of conformational transitions in the peptide. Alpha helix-beta sheet transition in Aβ peptide could be one of the plausible mechanism by which graphene oxide may inhibit amyloid fibrillation.

  19. Transition from embryonic to adult epidermis in reptiles occurs by the production of corneous beta-proteins.

    Science.gov (United States)

    Alibardi, Lorenzo

    2014-01-01

    The adaptation of the epidermis in amniote vertebrates to life on land took place by a drastic change from an embryonic epidermis made of two-four periderm layers to a terrestrial-proof epidermis. This transition occurred by the increase in types and number of specialized corneous proteins coded by genes of the Epidermal Differentiation Complex. The prevalent types of corneous proteins produced in the reptilian epidermis contain a beta-sheet region of high amino acid homology which allows their polymerization into a meshwork of filaments forming the hard corneous material of scales and claws. The present immunogold ultrastructural study shows that this transition occurs with the synthesis of glycine-rich corneous beta-proteins (formerly indicated as beta-keratins) that are added to the initial framework of acidic intermediate filaments produced in the embryonic epidermis of lizards, snake, alligator and turtle. These corneous beta-proteins are accumulated in the transitional and definitive layers of reptilian epidermis formed underneath the transitory two-four layered embryonic epidermis. In the more specialized reptiles capable of shedding the epidermis as a single unit, such as lizards and snakes, special glycine-cysteine rich beta-proteins are initially produced in a single layer immediately formed beneath the embryonic epidermis, the oberhautchen. The latter layer allows the in ovo shedding of the embryonic epidermis in preparation for hatching, and in the following shedding cycles of the adult epidermis. The production of specialized corneous-specific beta-proteins in addition to intermediate filament keratins was probably an essential addition for terrestrial life during the evolution of reptiles into different lineages, including birds. The increase of glycine and cysteine in epidermal proteins enhanced the hydrophobicity, insolubility and mechanical strength of the stratum corneum in these amniotes.

  20. Ionizing Radiation Promotes Migration and Invasion of Cancer Cells Through Transforming Growth Factor-Beta-Mediated Epithelial-Mesenchymal Transition

    Energy Technology Data Exchange (ETDEWEB)

    Zhou Yongchun [Department of Radiation Oncology, Xijing Hospital Fourth Military Medical University, Xi' an (China); Department of Radiation Medicine, College of Preventive Medicine, Xijing Hospital Fourth Military Medical University, Xi' an (China); Liu Junye; Li Jing; Zhang Jie [Department of Radiation Medicine, College of Preventive Medicine, Xijing Hospital Fourth Military Medical University, Xi' an (China); Xu Yuqiao [Department of Pathology, Xijing Hospital Fourth Military Medical University, Xi' an (China); Zhang Huawei; Qiu Lianbo; Ding Guirong [Department of Radiation Medicine, College of Preventive Medicine, Xijing Hospital Fourth Military Medical University, Xi' an (China); Su Xiaoming [Department of Radiation Oncology, 306th Hospital of PLA, Beijing (China); Mei Shi [Department of Radiation Oncology, Xijing Hospital Fourth Military Medical University, Xi' an (China); Guo Guozhen, E-mail: guozhenguo@hotmail.com [Department of Radiation Medicine, College of Preventive Medicine, Xijing Hospital Fourth Military Medical University, Xi' an (China)

    2011-12-01

    Purpose: To examine whether ionizing radiation enhances the migratory and invasive abilities of cancer cells through transforming growth factor (TGF-{beta})-mediated epithelial-mesenchymal transition (EMT). Methods and Materials: Six cancer cell lines originating from different human organs were irradiated by {sup 60}Co {gamma}-ray at a total dose of 2 Gy, and the changes associated with EMT, including morphology, EMT markers, migration and invasion, were observed by microscope, Western blot, immunofluorescence, scratch assay, and transwell chamber assay, respectively. Then the protein levels of TGF-{beta} in these cancer cells were detected by enzyme-linked immunosorbent assay, and the role of TGF-{beta} signaling pathway in the effect of ionizing radiation on EMT was investigate by using the specific inhibitor SB431542. Results: After irradiation with {gamma}-ray at a total dose of 2 Gy, cancer cells presented the mesenchymal phenotype, and compared with the sham-irradiation group the expression of epithelial markers was decreased and of mesenchymal markers was increased, the migratory and invasive capabilities were strengthened, and the protein levels of TGF-{beta} were enhanced. Furthermore, events associated with EMT induced by IR in A549 could be reversed through inhibition of TGF-{beta} signaling. Conclusions: These results suggest that EMT mediated by TGF-{beta} plays a critical role in IR-induced enhancing of migratory and invasive capabilities in cancer cells.

  1. Beta Decays of Isotones with Neutron Magic Number of N=126 and R-process Nucleosynthesis

    CERN Document Server

    Suzuki, Toshio; Kajino, Toshitaka; Otsuka, Takaharu

    2011-01-01

    Beta decays of the isotones with N=126 are studied by shell model calculations taking into account both the Gamow-Teller (GT) and first-forbidden (FF) transitions. The FF transitions are found to be important to reduce the half-lives, by nearly twice to several times, from those by the GT contributions only. Possible implications of the short half-lives of the waiting point nuclei on the r-process nucleosynthesis during the supernova explosions are discussed. A slight shift of the third peak of the element abundances in the r-process toward higher mass region is found.

  2. Research of TGF-beta1 Inducing Lung Adencarcinoma PC9 Cells to Mesenchymal Cells Transition

    Directory of Open Access Journals (Sweden)

    Xiaofeng CHEN

    2010-01-01

    Full Text Available Background and objective It has been proven that epithelial-mesenchymal transition (EMT not only correlated with embryonic development but also could promote tumor invasion and metastasis. Transforming growth factor beta-1 (TGF-β1 has been identified as the main inducer of tumor EMT. The aim of this study was to investigate the effects of TGF-β1 on EMT and PI3K/AKT signaling pathway in lung adencarcinoma PC9 cells. Methods Cultured PC9 cells were treated with different concentrations of TGF-β1 for 48 h. The morphological changes were observed under phase-contrast microscopy; EMT relative marker protein changes were assessed by Western blot and immunoflurescence staining. In addition, the expression of AKT and P-AKT were also measured by Western blot. Results The data showed that TGF-β1 could induce PC9 morphological alteration from epithelial to mesenchymal and upregulate the expression of mesenchymal maker protein Fibronectin. Obviously, the expression of P-AKT was downregulated by TGF-β1 treatment for 48 h. Conclusion TGF-β1 might induce EMT of PC9 cells , accompanied by the changes of PI3K/AKT signaling pathway.

  3. Light Dark Matter from Forbidden Channels.

    Science.gov (United States)

    D'Agnolo, Raffaele Tito; Ruderman, Joshua T

    2015-08-01

    Dark matter (DM) may be a thermal relic that annihilates into heavier states in the early universe. This forbidden DM framework accommodates a wide range of DM masses from keV to weak scales. An exponential hierarchy between the DM mass and the weak scale follows from the exponential suppression of the thermally averaged cross section. Stringent constraints from the cosmic microwave background are evaded because annihilations turn off at late times. We provide an example where DM annihilates into dark photons, which is testable through large DM self-interactions and direct detection.

  4. D rare/forbidden decays at BESIII

    CERN Document Server

    Zhao, Ming-Gang

    2016-01-01

    In this document we present the latest result on rare/forbidden decays for D mesons at the BESIII experiment. Based on 2.92/fb data taken at the center-of-mass energy 3.773 GeV with the BESIII detector, the flavor-changing neutral current process of neutral D decays into two gammas is searched using a double tag technique, while the decays of charged D decays into a charged kaon/pion plus two electrons/positrons are studied based on a single tag method. The resulting upper limits are still above the Standard Model predictions.

  5. On the alpha --> beta transition of carbon-coated highly oriented PVDF ultrathin film induced by melt recrystallization.

    Science.gov (United States)

    Wang, Jijun; Li, Huihui; Liu, Jichun; Duan, Yongxin; Jiang, Shidong; Yan, Shouke

    2003-02-12

    Poly(vinylidene fluoride) (PVDF) is one of the polymers which exhibit pronounced polymorphic crystalline forms, depending on crystallization conditions. Four different crystalline modifications, i.e., alpha, beta, gamma, and delta, have been reported so far. Among them, even though the alpha-form is the most common one, the beta-phase is the one that has attracted the widest interest due to its extensive piezo- and pyroelectric applications. During the past few decades, a substantial amount of work has been done in attempts to characterize these crystal modifications and transformations among them. It was well documented that the alpha-form PVDF can be easily obtained through melt crystallization of the PVDF at atmospheric pressure. Its beta-counterpart can, however, only be directly obtained by growth from solution, molecular epitaxy on the surface of potassium bromide, melt crystallization at high pressures, or by applying with a strong electric field. Transformation from its alpha-phase to beta-phase has been achieved by mechanical deformation, while the retransformation could be conducted through melt recrystallization at atmospheric pressure. In the present work, the recrystallization behavior of carbon-coated melt-drawn oriented PVDF ultrathin films at atmospheric pressure was studied by means of transmission electron microscopy and electron diffraction. The results indicate that through vacuum evaporating a thin carbon layer on the surface of highly oriented alpha-PVDF ultrathin film, not only has its high orientation been preserved after a complete melting and recrystallization process, but an alpha --> beta transition of PVDF has also been achieved through melt recrystallization at atmospheric pressure. This technique can be successfully used for preparing highly oriented beta-PVDF ultrathin films, especially patterned microstructures of PVDF with its highly oriented polar beta-phase and nonoriented nonpolar alpha-phase.

  6. Alpha5beta1 integrin-fibronectin interactions specify liquid to solid phase transition of 3D cellular aggregates.

    Directory of Open Access Journals (Sweden)

    Carlos E Caicedo-Carvajal

    Full Text Available BACKGROUND: Tissue organization during embryonic development and wound healing depends on the ability of cells on the one hand to exchange adhesive bonds during active rearrangement and on the other to become fixed in place as tissue homeostasis is reached. Cells achieve these contradictory tasks by regulating either cell-cell adhesive bonds, mediated by cadherins, or cell-extracellular matrix (ECM connections, regulated by integrins. Integrin alpha5beta1 and soluble fibronectin (sFN are key players in cell-ECM force generation and in ECM polymerization. Here, we explore the interplay between integrin alpha5beta1 and sFN and its influence on tissue mechanical properties and cell sorting behavior. METHODOLOGY/PRINCIPAL FINDINGS: We generated a series of cell lines varying in alpha5beta1 receptor density. We then systematically explored the effects of different sFN concentrations on aggregate biomechanical properties using tissue surface tensiometry. We found previously unreported complex behaviors including the observation that interactions between fibronectin and integrin alpha5beta1 generates biphasic tissue cohesion profiles. Specifically, we show that at constant sFn concentration, aggregate cohesion increases linearly as alpha5beta1 receptor density is increased from low to moderate levels, producing a transition from viscoelastic-liquid to pseudo viscoelastic-solid behavior. However, further increase in receptor density causes an abrupt drop in tissue cohesion and a transition back to viscoelastic-liquid properties. We propose that this may be due to depletion of sFn below a critical value in the aggregate microenvironment at high alpha5beta1 levels. We also show that differential expression of alpha5beta1 integrin can promote phase-separation between cells. CONCLUSIONS/SIGNIFICANCE: The interplay between alpha5-integrin and sFn contributes significantly to tissue cohesion and, depending on their level of expression, can mediate a shift

  7. Forbidden Zones for Numerically-Controlled Machine Tools

    Science.gov (United States)

    Philpot, D.

    1986-01-01

    Computer-controlled machine tool prevented from striking and damaging protruding members on workpiece by creating forbidden zone in control program. With aid of computer graphics, tool profile and coordinates of forbidden zone digitized and stored in computer memory as part of tool path.

  8. Beta decay and muon capture rates in a self-consistent relativistic framework

    Energy Technology Data Exchange (ETDEWEB)

    Marketin, Tomislav; Paar, Nils; Niksic, Tamara; Vretenar, Dario [Physics Department, Faculty of Science, University of Zagreb (Croatia); Ring, Peter [Physik-Department, Technische Universitaet Muenchen, D-85748 Muenchen (Germany)

    2009-07-01

    A fully consistent calculation of muon capture and beta decay rates is presented, based on a microscopic theoretical framework describing the semileptonic weak interaction processes. Nuclear ground state is determined using the Relativistic Hartree-Bogolyubov (RHB) model with density dependent meson-nucleon coupling constants, and transition rates are calculated via proton-neutron relativistic quasiparticle RPA using the same interaction as in the RHB equations. Muon capture rates are calculated for a wide range of nuclei along the valley of stability, from {sup 12}C to {sup 244}Pu, with accuracy of approximately 30%, using the interaction DD-ME2. Previous studies of beta decay rates have only taken into account Gamow-Teller transitions. We extend this approach by including forbidden transitions and systematically study their contribution to decay rates of exotic nuclei along the r-process path, which are important for constraining the conditions in which nucleosynthesis takes place.

  9. Laser-induced atomic fragment fluorescence spectroscopy: a facile technique for molecular spectroscopy of spin-forbidden states.

    Science.gov (United States)

    Zhang, Qun; Chen, Yang; Keil, Mark

    2009-03-01

    Spectra of spin-forbidden and spin-allowed transitions in the mixed b (3)Pi(u) approximately A (1)Sigma(u)(+) state of Na(2) are measured separately by two-photon excitation using a single tunable dye laser. The two-photon excitation produces Na(*)(3p) by photodissociation, which is easily and sensitively detected by atomic fluorescence. At low laser power, only the A (1)Sigma(u)(+) state is excited, completely free of triplet excitation. At high laser power, photodissociation via the intermediate b (3)Pi(u) triplet state becomes much more likely, effectively "switching" the observations from singlet spectroscopy to triplet spectroscopy with only minor apparatus changes. This technique of perturbation-assisted laser-induced atomic fragment fluorescence may therefore be especially useful as a general vehicle for investigating perturbation-related physics pertinent to the spin-forbidden states, as well as for studying allowed and forbidden states of other molecules.

  10. Beta decay of the fission product 125Sb and a new complete evaluation of absolute gamma ray transition intensities

    Science.gov (United States)

    Rajput, M. U.; Ali, N.; Hussain, S.; Mujahid, S. A.; MacMahon, D.

    2012-04-01

    The radionuclide 125Sb is a long-lived fission product, which decays to 125Te by negative beta emission with a half-life of 1008 day. The beta decay is followed by the emission of several gamma radiations, ranging from low to medium energy, that can suitably be used for high-resolution detector calibrations, decay heat calculations and in many other applications. In this work, the beta decay of 125Sb has been studied in detail. The complete published experimental data of relative gamma ray intensities in the beta decay of the radionuclide 125Sb has been compiled. The consistency analysis was performed and discrepancies found at several gamma ray energies. Evaluation of the discrepant data was carried out using Normalized Residual and RAJEVAL methods. The decay scheme balance was carried out using beta branching ratios, internal conversion coefficients, populating and depopulating gamma transitions to 125Te levels. The work has resulted in the consistent conversion factor equal to 29.59(13) %, and determined a new evaluated set of the absolute gamma ray emission probabilities. The work has also shown 22.99% of the delayed intensity fraction as outgoing from the 58 d isomeric 144 keV energy level and 77.01% of the prompt intensity fraction reaching to the ground state from the other excited states. The results are discussed and compared with previous evaluations. The present work includes additional experimental data sets which were not included in the previous evaluations. A new set of recommended relative and absolute gamma ray emission probabilities is presented.

  11. Optically Forbidden Excitations of 2s Electron of Neon Studied by Fast Electron Impact

    Institute of Scientific and Technical Information of China (English)

    GE Min; ZHU Lin-Fan; LIU Cun-Ding; XU Ke-Zun

    2008-01-01

    The electron energy loss spectrum in the energy region of 42-48.5 eV of neon is measured with an angle-resolved fast-electron energy-loss spectrometer at an incident electron energy of 2500eV. Besides the dipole-allowed autoionization transitions of 2s-1np (n = 3, 4) and 2p-23s3p, the dipole-forbidden ones of 2s-1ns (n = 3 - 6) and 2s-13d are observed. The line profile parameters, i.e. ET, F and q for these transitions, are determined, and the momentum transfer dependence behaviour is discussed.

  12. Anomalous pressure dependence of the superconducting transition temperature of beta-pyrochlore AOs2O6 oxides.

    Science.gov (United States)

    Muramatsu, T; Takeshita, N; Terakura, C; Takagi, H; Tokura, Y; Yonezawa, S; Muraoka, Y; Hiroi, Z

    2005-10-14

    High-pressure effects on the superconducting transitions of beta-pyrochlore oxide superconductors AOs(2)O(6) (A = Cs,Rb,K) are studied by measuring resistivity under high pressures up to 10 GPa. The superconducting transition temperature T(c) first increases with increasing pressure in every compound and then exhibits a broad maximum at 7.6 K (6 GPa), 8.2 K (2 GPa), and 10 K (0.6 GPa) for A = Cs, Rb, and K, respectively. Finally, the superconductivity is suppressed completely at a critical pressure near 7 GPa and 6 GPa for A = Rb and K and probably above 10 GPa for A = Cs. Characteristic changes in the coefficient A of the T(2) term in resistivity and residual resistivity are observed, both of which are synchronized with the corresponding change in T(c).

  13. The First Estimates of Kinematically Forbidden D Meson Decays

    CERN Document Server

    Verma, R C; Odagiri, Kosuke

    2015-01-01

    The weak hadronic decay D^+ -> K^0\\bar a_1^+ is kinematically forbidden at the peak mass values of the particles involved. However, occurrence of this decay has been reported with branching fraction (9.1 \\plusminus 1.8) \\cross 10^{-3} in the analysis of D^+ -> K^\\bar0 4 \\pi decay data. This is due to smearing effects on this decay caused mainly by the large width of a_1-resonance, which extends the phase space and allows this decay. Using a factorization model to evaluate decay amplitudes for external and internal W-emission diagrams, and incorporating Breit-Wigner smearing using the total a_1 width of 400 MeV, we obtain the first estimate for branching fraction of this decay to be 3.3 \\cross 10^{-3} and 7.0 \\cross 10^{-3}, for |V_1^{Da1} (0)|=0.40 and 1.50 respectively corresponding to different theoretical models, where |V_1^{Da1} (q^2)| is the vector form factor appearing in the D -> a_1 s-wave transition. The estimates are of the desired order of magnitude. We also predict branching fractions of its count...

  14. Beta-decay rate and beta-delayed neutron emission probability of improved gross theory

    Science.gov (United States)

    Koura, Hiroyuki

    2014-09-01

    A theoretical study has been carried out on beta-decay rate and beta-delayed neutron emission probability. The gross theory of the beta decay is based on an idea of the sum rule of the beta-decay strength function, and has succeeded in describing beta-decay half-lives of nuclei overall nuclear mass region. The gross theory includes not only the allowed transition as the Fermi and the Gamow-Teller, but also the first-forbidden transition. In this work, some improvements are introduced as the nuclear shell correction on nuclear level densities and the nuclear deformation for nuclear strength functions, those effects were not included in the original gross theory. The shell energy and the nuclear deformation for unmeasured nuclei are adopted from the KTUY nuclear mass formula, which is based on the spherical-basis method. Considering the properties of the integrated Fermi function, we can roughly categorized energy region of excited-state of a daughter nucleus into three regions: a highly-excited energy region, which fully affect a delayed neutron probability, a middle energy region, which is estimated to contribute the decay heat, and a region neighboring the ground-state, which determines the beta-decay rate. Some results will be given in the presentation. A theoretical study has been carried out on beta-decay rate and beta-delayed neutron emission probability. The gross theory of the beta decay is based on an idea of the sum rule of the beta-decay strength function, and has succeeded in describing beta-decay half-lives of nuclei overall nuclear mass region. The gross theory includes not only the allowed transition as the Fermi and the Gamow-Teller, but also the first-forbidden transition. In this work, some improvements are introduced as the nuclear shell correction on nuclear level densities and the nuclear deformation for nuclear strength functions, those effects were not included in the original gross theory. The shell energy and the nuclear deformation for

  15. Spectral shapes and a beta-gamma directional correlation in the beta decay of 172Tm (Jpi = 2-)

    DEFF Research Database (Denmark)

    Gregers Hansen, P.; Loft Nielsen, H.; Wilsky, K.;

    1966-01-01

    shape factor plots are taken relative to the 90Y shape factor measured in the same circumstances, and it is concluded that on this basis the shapes of all three 172Tm beta groups agree with the theoretical shape for a first-forbidden unique transition. The directional correlation for the 2-(beta)2......+(gamma)0+ cascade has been measured at six energies from 1010 to 1550 keV and these results too are consistent with the assumption that the 2- rarr 2+ beta transition is purely of tensor rank 2. The data for the 2- rarr 2+ transition are analysed on the basis of the modified Bij approximation, which...... defines parameters X and Y corresponding to the relative contributions of tensor ranks 0 and 1 respectively. The shape measurement provides the limit X2 + Y2 les 0.10, whereas the angular correlation measurement gives Y = 1.64X + (0.02 plusmn0.03). The reduced transition probabilities (f1t)-1 can...

  16. Observation of optically forbidden states in PC60BM due to interfacial distortion

    Science.gov (United States)

    Shah, Hemant; Alphenaar, Bruce

    2011-03-01

    PCBM is a fullerene derivative used extensively in organic solar cells. PC60 BM shows strong absorbance at wavelengths below 400 nm. A series of sub-gap transitions exist, but are symmetry forbidden in C60 , and only weakly observed in the PC60 BM absorbance. Recent theoretical calculations predict that the symmetry rules for C60 can be lifted by the proximity of a metallic substrate due to perturbation of the electronic spatial distribution. Here we describe capacitive photocurrent measurements of PC60 BM in which the optically forbidden features are strongly observed. In agreement with the theoretical predictions, this is thought to be due to the influence of a high conductivity ITO layer in contact with the PC60 BM. The influence of the ITO is tested by introducing a thin insulator (Al 2 O3) of varying thickness between the PC60 BM and the ITO. The photocurrent due to the symmetry forbidden states drops strongly compared to the above gap photocurrent with increasing separation. Implications of these results on the polythiophene/fullerene blends will also be discussed. DOE-3048103802-08-073, NSF- DMR-0906961

  17. Ab-Initio Based Computation of Rate Constants for Spin Forbidden Metalloprotein-Substrate Reactions

    Science.gov (United States)

    Ozkanlar, Abdullah; Rodriguez, Jorge H.

    2007-03-01

    Some chemical and biochemical reactions are non-adiabatic processes whereby the total spin angular momentum, before and after the reaction, is not conserved. These are named spin- forbidden reactions. The application of ab-initio methods, such as spin density functional theory (SDFT), to the prediction of rate constants is a challenging task of fundamental and practical importance. We apply non-adiabatic transition state theory (NA-TST) in conjuntion with SDFT to predict the rate constant of the spin- forbidden recombination of carbon monoxide with iron tetracarbonyl. To model the surface hopping probability between singlet and triplet states, the Landau-Zener formalism is used. The lowest energy point for singlet-triplet crossing, known as minimum energy crossing point (MECP), was located and used to compute, in a semi-quantum approach, reaction rate constants at 300 K. The predicted rates are in very good agreement with experiment. In addition, we present results for the spin- forbidden ligand binding reactions of iron-containing heme proteins such as myoglobin.

  18. TGF-beta 1-induced epithelial-to-mesenchymal transition and therapeutic intervention in diabetic nephropathy

    OpenAIRE

    Hills, Claire E.; Squires, Paul E.

    2010-01-01

    Background/Aims: Epithelial-to-mesenchymal cell transformation (EMT) is the trans-differentiation of tubular epithelial cells into myofibroblasts, an event underlying progressive chronic kidney disease in diabetes, resulting in fibrosis. Mainly reported in proximal regions of the kidney, EMT is now recognized as a key contributor to the loss of renal function throughout the nephron in diabetic nephropathy (DN). Concomitant upregulation of TGF-beta in diabetes makes this pro-fibrotic cytokine ...

  19. Semi-emprical and ab initio study of lanthanide and transition metal ions doped in hexagonol beta-NaYF4

    Science.gov (United States)

    Yao, Ge

    Lanthanide and transition metal doped hexagonal beta-NaYF4 nanocrystals have a wide variety of applications in bioimaging, solar concentrators, display panel technology, photodynamic therapy, and security printing. This dissertation research employed two complementary approaches to characterizing the photoactive properties of lanthanides and transition metals doped in beta-NaYF 4. One approach was a semi-empirical method, based on Judd-Ofelt theory, used to calculate the optical transition intensity parameters for Er 3+ doped in beta-phase NaYF4:Yb3+ from measured emission intensity ratios and the diffuse reflectance spectrum. The second approach was based on first-principles density functional theory, investigating the effect of doping on the electronic structure of the materials of interest. In this latter approach, models of beta-NaYF4 with different numbers of atoms in supercells were built, where supercells were reproduced through translational symmetry creating periodic boundary conditions. The models were tested for convergence of local structure and energy as a function of supercell size. First, a converged model for the un-doped "parent" structure of the host material was developed using the Perdew-Burke-Ernzerhof (PBE) functional. Then, a systematic investigation of the optimized geometry and electronic structure of the doped beta-NaYF4: Ln3+ nanocrystals, was conducted using both spin-polarized DFT and non-collinear-spin DFT. For transition metal doping, the relationship between site symmetry and spin state with different doping concentrations was also demonstrated.

  20. Liver cancer-derived hepatitis C virus core proteins shift TGF-beta responses from tumor suppression to epithelial-mesenchymal transition.

    Directory of Open Access Journals (Sweden)

    Serena Battaglia

    Full Text Available BACKGROUND: Chronic hepatitis C virus (HCV infection and associated liver cirrhosis represent a major risk factor for hepatocellular carcinoma (HCC development. TGF-beta is an important driver of liver fibrogenesis and cancer; however, its actual impact in human cancer progression is still poorly known. The aim of this study was to investigate the role of HCC-derived HCV core natural variants on cancer progression through their impact on TGF-beta signaling. PRINCIPAL FINDINGS: We provide evidence that HCC-derived core protein expression in primary human or mouse hepatocyte alleviates TGF-beta responses in terms or growth inhibition or apoptosis. Instead, in these hepatocytes TGF-beta was still able to induce an epithelial to mesenchymal transition (EMT, a process that contributes to the promotion of cell invasion and metastasis. Moreover, we demonstrate that different thresholds of Smad3 activation dictate the TGF-beta responses in hepatic cells and that HCV core protein, by decreasing Smad3 activation, may switch TGF-beta growth inhibitory effects to tumor promoting responses. CONCLUSION/SIGNIFICANCE: Our data illustrate the capacity of hepatocytes to develop EMT and plasticity under TGF-beta, emphasize the role of HCV core protein in the dynamic of these effects and provide evidence for a paradigm whereby a viral protein implicated in oncogenesis is capable to shift TGF-beta responses from cytostatic effects to EMT development.

  1. Structures of ceftazidime and its transition-state analogue in complex with AmpC beta-lactamase: Implications for resistance mutations and inhibitor design

    Energy Technology Data Exchange (ETDEWEB)

    Powers, R.A.; Caselli, E.; Focia, P.J.; Prati, F.; Shoichet, B.K.

    2010-03-08

    Third-generation cephalosporins are widely used {beta}-lactam antibiotics that resist hydrolysis by {beta}-lactamases. Recently, mutant {beta}-lactamases that rapidly inactivate these drugs have emerged. To investigate why third-generation cephalosporins are relatively stable to wild-type class C {beta}-lactamases and how mutant enzymes might overcome this, the structures of the class C {beta}-lactamase AmpC in complex with the third-generation cephalosporin ceftazidime and with a transition-state analogue of ceftazidime were determined by X-ray crystallography to 2.0 and 2.3 {angstrom} resolution, respectively. Comparison of the acyl-enzyme structures of ceftazidime and loracarbef, a {beta}-lactam substrate, reveals that the conformation of ceftazidime in the active site differs from that of substrates. Comparison of the structures of the acyl-enzyme intermediate and the transition-state analogue suggests that ceftazidime blocks formation of the tetrahedral transition state, explaining why it is an inhibitor of AmpC. Ceftazidime cannot adopt a conformation competent for catalysis due to steric clashes that would occur with conserved residues Val211 and Tyr221. The X-ray crystal structure of the mutant {beta}-lactamase GC1, which has improved activity against third-generation cephalosporins, suggests that a tandem tripeptide insertion in the {Omega} loop, which contains Val211, has caused a shift of this residue and also of Tyr221 that would allow ceftazidime and other third-generation cephalosporins to adopt a more catalytically competent conformation. These structural differences may explain the extended spectrum activity of GC1 against this class of cephalosporins. In addition, the complexed structure of the transition-state analogue inhibitor (K{sub i} 20 nM) with AmpC reveals potential opportunities for further inhibitor design.

  2. Direct mass measurements of cadmium and palladium isotopes and their double-beta transition $Q$-values

    CERN Document Server

    Smorra, C; Blaum, K; Block, M; Düllmann, Ch E; Eberhardt, K; Eibach, M; Eliseev, S; Nagy, Sz; Nörtershäuser, W; Renisch, D

    2012-01-01

    The $Q$-value of the double-electron capture in $^{108}$Cd has been determined to be (272.04 $\\pm$ 0.55) keV in a direct measurement with the double-Penning trap mass spectrometer TRIGA-TRAP. Based on this result a resonant enhancement of the decay rate of $^{108}$Cd is excluded. We have confirmed the double-beta transition $Q$-values of $^{106}$Cd and $^{110}$Pd recently measured with the Penning-trap mass spectrometers SHIPTRAP and ISOLTRAP, respectively. Furthermore, the atomic masses of the involved nuclides ($^{106, 108, 110}$Cd, $^{106, 108, 110}$Pd) have been directly linked to the atomic mass standard.

  3. The Orbit and Transit Prospects for $\\beta$ Pictoris b constrained with One Milliarcsecond Astrometry

    CERN Document Server

    Wang, Jason J; Pueyo, Laurent; Kalas, Paul; Millar-Blanchaer, Maxwell A; Ruffio, Jean-Baptiste; De Rosa, Robert J; Ammons, S Mark; Arriaga, Pauline; Bailey, Vanessa P; Barman, Travis S; Bulger, Joanna; Burrows, Adam S; Cardwell, Andrew; Chen, Christine H; Chilcote, Jeffrey K; Cotten, Tara; Fitzgerald, Michael P; Follette, Katherine B; Doyon, René; Duchêne, Gaspard; Greenbaum, Alexandra Z; Hibon, Pascale; Hung, Li-Wei; Ingraham, Patrick; Konopacky, Quinn M; Larkin, James E; Macintosh, Bruce; Maire, Jérôme; Marchis, Franck; Marley, Mark S; Marois, Christian; Metchev, Stanimir; Nielsen, Eric L; Oppenheimer, Rebecca; Palmer, David W; Patel, Rahul; Patience, Jenny; Perrin, Marshall D; Poyneer, Lisa A; Rajan, Abhijith; Rameau, Julien; Rantakyrö, Fredrik T; Savransky, Dmitry; Sivaramakrishnan, Anand; Song, Inseok; Soummer, Remi; Thomas, Sandrine; Vasisht, Gautam; Vega, David; Wallace, J Kent; Ward-Duong, Kimberly; Wiktorowicz, Sloane J; Wolff, Schuyler G

    2016-01-01

    A principal scientific goal of the Gemini Planet Imager (GPI) is obtaining milliarcsecond astrometry to constrain exoplanet orbits. However, astrometry of directly imaged exoplanets is subject to biases, systematic errors, and speckle noise. Here we describe an analytical procedure to forward model the signal of an exoplanet that accounts for both the observing strategy (angular and spectral differential imaging) and the data reduction method (Karhunen-Lo\\`eve Image Projection algorithm). We use this forward model to measure the position of an exoplanet in a Bayesian framework employing Gaussian processes and Markov chain Monte Carlo (MCMC) to account for correlated noise. In the case of GPI data on $\\beta$ Pic b, this technique, which we call Bayesian KLIP-FM Astrometry (BKA), outperforms previous techniques and yields 1$\\sigma$-errors at or below the one milliarcsecond level. We validate BKA by fitting a Keplerian orbit to twelve GPI observations along with previous astrometry from other instruments. The st...

  4. Relativistic pn-QRPA to the double beta decay

    Energy Technology Data Exchange (ETDEWEB)

    Conti, Claudio de [Universidade Estadual Paulista (UNESP), Itapeva, SP (Brazil). Campus Experimental de Itapeva; Krmpotic, F. [Universidad Nacional de La Plata (Argentina). Facultad de Ciencias Astronomicas y Geofisicas; Carlson, Brett Vern [Centro Tecnico Aeroespacial (CTA/ITA), Sao Jose dos Campos, SP (Brazil). Inst. Tecnologico de Aeronautica. Dept. de Fisica

    2010-07-01

    Full text: In nature there are about 50 nuclear systems where the single beta-decay is energetically forbidden, and double- beta decay turns out to be only possible mode of disintegration. It is the nuclear pairing force which causes such an 'anomaly', by making the mass of the odd-odd isobar, (N - 1;Z + 1), to be greater than the masses of its even-even neighbors, (N;Z) and (N - 2;Z +2). The modes by which the double-beta decay can take place are connected with the neutrino and antineutrino distinction. In case the lepton number is strictly conserved the neutrino is a Dirac fermion and the two-neutrino mode is the only possible mode of disintegration. On the other hand, if this conservation is violated, the neutrino is a Majorana particle and neutrinoless double-beta decay also can occur. Both two-neutrino and neutrinoless double-beta decay processes have attracted much attention, because a comparison between experiment and theory for the first, provides a measure of confidence one may have in the nuclear wave function employed for extracting the unknown parameters from neutrinoless lifetime measurements. The proton-neutron (pn) quasiparticle random phase approximation (QRPA) has turned out be the most simple model for calculating the nuclear wave function involved in the double-beta decay transitions. In this work the transition matrix elements for 0{sup +} -> 0{sup +} double-beta decay are calculated for {sup 48}Ca, {sup 76}Ge, {sup 82}Se, {sup 100}Mo, {sup 128}Te and {sup 130}Te nuclei, using a relativistic pn-QRPA based on Hartree-Bogoliubov approximation to the single-particle motion. (author)

  5. Shell-model half-lives for r-process waiting point nuclei including first-forbidden contributions

    CERN Document Server

    Zhi, Q; Cuenca-García, J J; Langanke, K; Martínez-Pinedo, G; Sieja, K

    2013-01-01

    We have performed large-scale shell-model calculations of the half-lives and neutron-branching probabilities of the r-process waiting point nuclei at the magic neutron numbers N=50, 82, and 126. The calculations include contributions from allowed Gamow-Teller and first-forbidden transitions. We find good agreement with the measured half-lives for the N=50 nuclei with charge numbers Z=28-32 and for the N=82 nuclei 129Ag and 130Cd. The contribution of forbidden transitions reduce the half-lives of the N=126 waiting point nuclei significantly, while they have only a small effect on the half-lives of the N=50 and 82 r-process nuclei.

  6. Synthetic beta-K(0.33)V2O5 nanorods: a metal-insulator transition in vanadium oxide bronze.

    Science.gov (United States)

    Zhang, Xiaodong; Yan, Wensheng; Xie, Yi

    2011-12-02

    We found a linear relationship between the metal-insulator transition (MIT) temperature and the A(+) ionic radius of the beta-A(0.33)V(2)O(5) bronze family, leading our attention to beta-K(0.33)V(2)O(5) which has been neglected for a long time. We have introduced a facile hydrothermal method to obtain the single-crystalline beta-K(0.33)V(2)O(5) nanorods. As expected, both the temperature-dependence of the resistivity and magnetization demonstrated MITs at about 72 K for beta-K(0.33)V(2)O(5), thus matching well with the linear relationship described above. The beta-K(0.33)V(2)O(5) was assigned as a new member of the beta-A(0.33)V(2)O(5) bronze family for their similar crystal and electronic structures and their MIT property; this addition enriches the beta-A(0.33)V(2)O(5) bronze family.

  7. Optical properties of beta-iron silicide, ruthenium silicide and osmium silicide: Semiconducting transition metal silicides

    Science.gov (United States)

    Birdwell, Anthony Glen

    2001-09-01

    Various optical techniques were used to study the semiconducting transition metal silicides of β- FeSi2, Ru2Si3, and OsSi2. The Raman spectra of ion beam synthesized (IBS) β-FeSi 2 were shown to provide evidence of a net tensile stress in these IBS materials. Possible origins of the observed stress were suggested and a simple model was proposed in order to calculate a value of the observed stress. A correlation between the tensile stress, the nature of the band gap, and the resulting light emitting properties of IBS β-FeSi2 was suggested. The photoreflectance (PR) spectra of IBS β- FeSi2 reveals a direct gap at 0.815 eV and were shown to agree with the band gap value obtained by photoluminescence (PL) once the adjustments for the temperature difference and trap related recombination effects were made. This provides very convincing evidence for intrinsic light emission from IBS β- FeSi2. Furthermore, a model was developed that helps to clarify the variety of inconsistent results obtained by optical absorption measurements. When the results of PL and PR were inserted into this model, a good agreement was obtained with our measured optical absorption results. We also obtained PR spectra of β-FeSi 2 thin films grown by molecular beam epitaxy. These spectra reveal the multiple direct transitions near the fundamental absorption edge of β-FeSi 2 that were predicted by theory. We suggest an order of these critical point transitions following the trends reported in the theoretical investigations. Doping these β-FeSi2 thin films with small amounts of chromium was shown to have a measurable effect on the interband optical spectra. We also report on the effects of alloying β- FeSi2 with cobalt. A decrease in the critical point transitions nearest the fundamental absorption edge was observed as the cobalt concentration increased. Finally, Raman spectroscopy was used to study the vibrational properties of β-FeSi2. The measured Raman spectra agreed very well with the

  8. Limits on Lorentz violation from forbidden β decays.

    Science.gov (United States)

    Noordmans, J P; Wilschut, H W; Timmermans, R G E

    2013-10-25

    Forbidden (slow) β decays offer new opportunities to test the invariance of the weak interaction under Lorentz transformations. Within a general effective field theory framework we analyze and reinterpret the only two relevant experiments, performed in the 1970s, dedicated to search for a preferred direction in space in first- and second-forbidden β decays. We show that the results of these experiments put strong and unique limits on Lorentz violation, and in particular on the presence of several interactions in the modern Lorentz-violating standard model extension. We discuss prospects to improve on these limits.

  9. Forbidden substrings, Kolmogorov complexity and almost periodic sequences

    CERN Document Server

    Rumyantsev, Andrey

    2010-01-01

    Assume that for some $\\alpha<1$ and for all nutural $n$ a set $F_n$ of at most $2^{\\alpha n}$ "forbidden" binary strings of length $n$ is fixed. Then there exists an infinite binary sequence $\\omega$ that does not have (long) forbidden substrings. We prove this combinatorial statement by translating it into a statement about Kolmogorov complexity and compare this proof with a combinatorial one based on Laslo Lovasz local lemma. Then we construct an almost periodic sequence with the same property (thus combines the results of Levin and Muchnik-Semenov-Ushakov). Both the combinatorial proof and Kolmogorov complexity argument can be generalized to the multidimensional case.

  10. Synthesis, spectral and extended spectrum beta-lactamase studies of transition metal tetraaza macrocyclic complexes.

    Science.gov (United States)

    Kumar, Dinesh; Sharma, Nutan; Nair, Manjula

    2017-01-18

    Urinary tract infections commonly occur in humans due to microbial pathogens invading the urinary tract, which can bring about a range of clinical symptoms and potentially fatal sequelae. The present study is aimed at addressing the development of a new antimicrobial agent against extended spectrum beta lactamase (ESBL) producing E. coli bacteria. We have synthesised some biologically potent (NNNN) donor macrocycles (L 1  = dibenzo[f,n]dipyrido[3,4-b:4',3'-j][1,4,9,12]tetraazacyclohexadecine-6,11,18,23(5H,12H, 7H, 24H)-tetraone, and L 2  = 6,12,19,25-tetraoxo-4,6,11,12,16,18,23,24-octahydrotetrabenzo [b,g,k,p][1,5,10,14]tetra azacyclooctadecine-2,13-dicarboxylic acid) and their Ti and Zr metal complexes in alcoholic media using microwave protocol. Macrocyclic ligands were synthesised by incorporating of 3,5-diaminobenzoic acid, phthalic acid and 3,4-diaminopyridine in 1:1:1 molar ratio. The macrocyclic ligands and their metal complexes have been characterised by elemental analysis, conductance measurement, magnetic measurement and their structure configurations have been determined by various spectroscopic (FTIR, (1)H/(13)C NMR, UV-Vis, LC-MS mass, XRD and TGA) techniques. [ZrL2Cl2]Cl2 metal complex shows excellent antibacterial activity against ESBLs. A zone of inhibition and minimum inhibitory concentration was determined by McFarland and the dilution method, respectively. The spectral studies confirm the binding sites of the nitrogen atom of the macrocycles. An octahedral geometry has been assigned to the metal complexes based on the findings.

  11. Novel Insights Into The Mode of Inhibition of Class A SHV-1 Beta-Lactamases Revealed by Boronic Acid Transition State Inhibitors

    Energy Technology Data Exchange (ETDEWEB)

    W Ke; J Sampson; C Ori; F Prati; S Drawz; C Bethel; R Bonomo; F van den Akker

    2011-12-31

    Boronic acid transition state inhibitors (BATSIs) are potent class A and C {beta}-lactamase inactivators and are of particular interest due to their reversible nature mimicking the transition state. Here, we present structural and kinetic data describing the inhibition of the SHV-1 {beta}-lactamase, a clinically important enzyme found in Klebsiella pneumoniae, by BATSI compounds possessing the R1 side chains of ceftazidime and cefoperazone and designed variants of the latter, compounds 1 and 2. The ceftazidime and cefoperazone BATSI compounds inhibit the SHV-1 {beta}-lactamase with micromolar affinity that is considerably weaker than their inhibition of other {beta}-lactamases. The solved crystal structures of these two BATSIs in complex with SHV-1 reveal a possible reason for SHV-1's relative resistance to inhibition, as the BATSIs adopt a deacylation transition state conformation compared to the usual acylation transition state conformation when complexed to other {beta}-lactamases. Active-site comparison suggests that these conformational differences might be attributed to a subtle shift of residue A237 in SHV-1. The ceftazidime BATSI structure revealed that the carboxyl-dimethyl moiety is positioned in SHV-1's carboxyl binding pocket. In contrast, the cefoperazone BATSI has its R1 group pointing away from the active site such that its phenol moiety moves residue Y105 from the active site via end-on stacking interactions. To work toward improving the affinity of the cefoperazone BATSI, we synthesized two variants in which either one or two extra carbons were added to the phenol linker. Both variants yielded improved affinity against SHV-1, possibly as a consequence of releasing the strain of its interaction with the unusual Y105 conformation.

  12. Effect of Transition Metals on Optical Properties of {beta}-Ga{sub 2}O{sub 3}: Time-Resolved Spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Yasukawa, D; Wakai, H; Oda, H; Yamanaka, A, E-mail: a-yamana@photon.chitose.ac.jp [Chitose Institute of Science and Technology, Bibi 758-65, Chitose, Hokkaido 066-8655 (Japan)

    2011-05-15

    Time-resolved spectroscopy has investigated in single-crystals of transition-metal-doped {beta}-Ga{sub 2}O{sub 3} at room temperature, particularly focused on the Cr-doping effects on the photoluminescence due to donor-acceptor recombination. It turns out that the visible photoluminescence exhibits a non-exponential decay, basically similar to that observed in nominally pure {beta}-Ga{sub 2}O{sub 3}. Detailed inspection indicates that doped Cr ions greatly reduce slower components of the radiative recombination and such the effect is nearly independent of the energy of the donor-acceptor pair.

  13. Search for Detour Transitions in the Radiative EC Decay of $^{81}$Kr

    CERN Multimedia

    Rykaczewski, K

    2002-01-01

    % IS355 \\\\ \\\\ It is proposed to produce at ISOLDE the $^{81}$Kr activity and to study its 1-st forbidden unique (1u) radiative electron-capture decay in low background conditions available in Warsaw. The intensity of the photon spectrum will be compared to predictions of the internal-bremsstrahlung theory. A question is whether an excess of the intensity will be observed, indicating the role of detour $\\gamma$/$\\beta$ transitions via intermediate virtual nuclear states, as detected already for the 1u radiative decay of $^{41}$Ca.

  14. Beta decay rates of neutron-rich nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Marketin, Tomislav, E-mail: marketin@phy.hr [Department of Physics, Faculty of Science, University of Zagreb, 10000 Zagreb (Croatia); Huther, Lutz [Institut für Kernphysik (Theoriezentrum), Technische Universität Darmstadt, 64289 Darmstadt (Germany); Martínez-Pinedo, Gabriel [Institut für Kernphysik (Theoriezentrum), Technische Universität Darmstadt, 64289 Darmstadt (Germany); GSI Helmholtzzentrum für Schwerioneneforschung, Planckstraße 1, 64291 Darmstadt (Germany)

    2015-10-15

    Heavy element nucleosynthesis models involve various properties of thousands of nuclei in order to simulate the intricate details of the process. By necessity, as most of these nuclei cannot be studied in a controlled environment, these models must rely on the nuclear structure models for input. Of all the properties, the beta-decay half-lives are one of the most important ones due to their direct impact on the resulting abundance distributions. Currently, a single large-scale calculation is available based on a QRPA calculation with a schematic interaction on top of the Finite Range Droplet Model. In this study we present the results of a large-scale calculation based on the relativistic nuclear energy density functional, where both the allowed and the first-forbidden transitions are studied in more than 5000 neutron-rich nuclei.

  15. Integrated statistical rate function for superallowed Fermi. beta. -decays

    Energy Technology Data Exchange (ETDEWEB)

    Szybisz, L. (Koeln Univ. (Germany, F.R.). Inst. fuer Theoretische Physik)

    1984-09-27

    The impact that recently pointed out differences between the two sets of integrated statistical rate functions, i.e. f-values, calculated according to the widely adopted methods of Behrens, Jaenecke and Buehring and Towner and Hardy have on the internal consistency of Ft-values of the eight best measured superallowed Fermi ..beta..-transitions is analyzed. We find that, due to the dramatic improvement in the accuracy of experimental data, both sets of Ft-values show a statistical difference. In addition, we evaluate the second-forbidden corrections using an alternative way proposed by Jaus. This latter prescription yields results in good agreement with those obtained using the procedure of Behrens, Jaenecke and Buehring.

  16. Beta decay rates of neutron-rich nuclei

    Science.gov (United States)

    Marketin, Tomislav; Huther, Lutz; Petković, Jelena; Paar, Nils; Martínez-Pinedo, Gabriel

    2016-06-01

    Heavy element nucleosynthesis models involve various properties of thousands of nuclei in order to simulate the intricate details of the process. By necessity, as most of these nuclei cannot be studied in a controlled environment, these models must rely on the nuclear structure models for input. Of all the properties, the beta-decay half-lives are one of the most important ones due to their direct impact on the resulting abundance distributions. In this study we present the results of a large-scale calculation based on the relativistic nuclear energy density functional, where both the allowed and the first-forbidden transitions are studied in more than 5000 neutron-rich nuclei. Aside from the astrophysical applications, the results of this calculation can also be employed in the modeling of the electron and antineutrino spectra from nuclear reactors.

  17. E-cigarettes forbidden in offices and closed areas

    CERN Multimedia

    2013-01-01

    Be reminded that all people on the CERN site must comply with the following notice from the Medical Service: “In the same manner as for ordinary cigarettes, the use of e-cigarettes is forbidden in all offices and closed areas.” If you have any question, please write to medical.service@cern.ch HSE Unit/ GS-ME Department

  18. Generalization of Suppression in Norma Khouri's "Forbidden Love"

    Science.gov (United States)

    Mariam, Olya; Rana, Sidra

    2014-01-01

    The aim of this research is to critique the repercussions of over-generalization of a social issue as depicted in Norma Khouri's "Forbidden Love." The novel/memoir has been written against the 9/11 backdrop and as such serves as means of sensationalizing and exploiting a cultural event which unfortunately echoes in the East. The…

  19. First Detection of Sign-reversed Linear Polarization from the Forbidden [O I] 630.03 nm Line

    Science.gov (United States)

    de Wijn, A. G.; Socas-Navarro, H.; Vitas, N.

    2017-02-01

    We report on the detection of linear polarization of the forbidden [O i] 630.03 nm spectral line. The observations were carried out in the broader context of the determination of the solar oxygen abundance, an important problem in astrophysics that still remains unresolved. We obtained spectro-polarimetric data of the forbidden [O i] line at 630.03 nm as well as other neighboring permitted lines with the Solar Optical Telescope of the Hinode satellite. A novel averaging technique was used, yielding very high signal-to-noise ratios in excess of 105. We confirm that the linear polarization is sign-reversed compared to permitted lines as a result of the line being dominated by a magnetic dipole transition. Our observations open a new window for solar oxygen abundance studies, offering an alternative method to disentangle the Ni i blend from the [O i] line at 630.03 nm that has the advantage of simple LTE formation physics.

  20. A computational protocol for the study of circularly polarized phosphorescence and circular dichroism in spin-forbidden absorption

    DEFF Research Database (Denmark)

    Kaminski, Maciej; Cukras, Janusz; Pecul, Magdalena

    2015-01-01

    We present a computational methodology to calculate the intensity of circular dichroism (CD) in spinforbidden absorption and of circularly polarized phosphorescence (CPP) signals, a manifestation of the optical activity of the triplet–singlet transitions in chiral compounds. The protocol is based...... on the response function formalism and is implemented at the level of time-dependent density functional theory. It has been employed to calculate the spin-forbidden circular dichroism and circularly polarized phosphorescence signals of valence n - p* and n ’ p* transitions, respectively, in several chiral enones...

  1. First observation of the strongly forbidden transition {sup 1}S{sub 0} - {sup 3}P{sub 0} in Strontium, for an atomic clock with trapped atoms; Premiere observation de la transition fortement interdite {sup 1}S{sub 0} - {sup 3}P{sub 0} du strontium, pour une horloge optique a atomes pieges

    Energy Technology Data Exchange (ETDEWEB)

    Courtillot, I

    2003-11-01

    This thesis reports the first results towards the realization of an optical clock using trapped strontium atoms. This set up would combine advantages of the different approaches commonly used to develop an atomic frequency standard. The first part describes the cold atoms source which is implemented. A magneto-optical trap operating on the {sup 1}S{sub 0}-{sup 1}P{sub 1} transition at 461 nm is loaded from an atomic beam decelerated by a Zeeman slower. The 461 nm laser is obtained by sum-frequency mixing in a potassium titanyl phosphate (KTP) crystal. The second part is devoted to the different stages developed to achieve the direct excitation of the {sup 1}S{sub 0}-{sup 3}P{sub 0} clock transition in {sup 87}Sr. This line has a theoretical natural width of 10{sup -3} Hz. Before this detection, we obtained an estimate of the resonance frequency by measuring absolute frequencies of several allowed optical transitions. (author)

  2. Forbidden phonon: Dynamical signature of bond symmetry breaking in the iron chalcogenides

    Science.gov (United States)

    Fobes, David M.; Zaliznyak, Igor A.; Tranquada, John M.; Xu, Zhijun; Gu, Genda; He, Xu-Gang; Ku, Wei; Zhao, Yang; Matsuda, Masaaki; Garlea, V. Ovidiu; Winn, Barry

    2016-09-01

    Investigation of the inelastic neutron scattering spectra in Fe1 +yTe1 -xSex near a signature wave vector Q =(1 ,0 ,0 ) for the bond-order wave (BOW) formation of parent compound Fe1 +yTe [D. Fobes et al., Phys. Rev. Lett. 112, 187202 (2014), 10.1103/PhysRevLett.112.187202] reveals an acoustic-phonon-like dispersion present in all structural phases. While a structural Bragg peak accompanies the mode in the low-temperature phase of Fe1 +yTe , it is absent in the high-temperature tetragonal phase, where Bragg scattering at this Q is forbidden by symmetry. Notably, this mode is also observed in superconducting FeTe0.55Se0.45 , where structural and magnetic transitions are suppressed, and no BOW has been observed. The presence of this "forbidden" phonon indicates that the lattice symmetry is dynamically or locally broken by magneto-orbital BOW fluctuations, which are strongly coupled to lattice in these materials.

  3. GSTA3 Attenuates Renal Interstitial Fibrosis by Inhibiting TGF-Beta-Induced Tubular Epithelial-Mesenchymal Transition and Fibronectin Expression.

    Science.gov (United States)

    Xiao, Yun; Liu, Jishi; Peng, Yu; Xiong, Xuan; Huang, Ling; Yang, Huixiang; Zhang, Jian; Tao, Lijian

    2016-01-01

    Tubular epithelial-mesenchymal transition (EMT) has been widely accepted as the underlying mechanisms of renal interstitial fibrosis (RIF). The production of reactive oxygen species (ROS) plays a vital role in tubular EMT process. The purpose of this study was to investigate the involved molecular mechanisms in TGF-beta-induced EMT and identify the potential role of glutathione S-transferase alpha 3 (GSTA3) in this process. The iTRAQ screening was performed to identify protein alterations of the rats underwent unilateral-ureteral obstruction (UUO). Protein expression of GSTA3 in patients with obstructive nephropathy and UUO rats was detected by immunohistochemistry. Protein and mRNA expression of GSTA3 in UUO rats and NRK-52E cells were determined by Western blot and RT-PCR. siRNA and overexpression plasmid were transfected specifically to assess the role of GSTA3 in RIF. The generation of ROS was measured by dichlorofluorescein fluorescence analysis. GSTA3 protein and mRNA expression was significantly reduced in UUO rats. Immunohistochemical analysis revealed that GSTA3 expression was reduced in renal cortex in UUO rats and patients with obstructive nephropathy. Treating with TGF-β1 down-regulated GSTA3 expression in NRK-52E cells, which have been found to be correlated with the decreased expression in E-cadherin and megalin and increased expression in α-smooth muscle actin. Furthermore, knocking down GSTA3 in NRK-52 cells led to increased production of ROS and tubular EMT, whereas overexpressing GSTA3 ameliorated ROS production and prevented the occurrence of tubular EMT. GSTA3 plays a protective role against tubular EMT in renal fibrosis, suggesting GSTA3 is a potential therapeutic target for RIF.

  4. Search for the CP Forbidden Decay η-->4π0

    Science.gov (United States)

    Prakhov, S.; Tippens, W. B.; Allgower, C.; Bekrenev, V.; Berger, E.; Briscoe, W. J.; Clajus, M.; Comfort, J. R.; Craig, K.; Grosnick, D.; Huber, G. M.; Isenhower, D.; Knecht, N.; Koetke, D.; Koulbardis, A.; Kozlenko, N.; Kruglov, S.; Kycia, T.; Lolos, G. J.; Lopatin, I.; Manley, D. M.; MarušiĆ, A.; Manweiler, R.; McDonald, S.; Nefkens, B. M.; Olmsted, J.; Papandreou, Z.; Peaslee, D.; Peterson, G. J.; Phaisangittisakul, N.; Pulver, M.; Ramirez, A. F.; Sadler, M. E.; Shafi, A.; Šlaus, I.; Spinka, H.; Stanislaus, S.; Starostin, A.; Staudenmaier, H. M.; Supek, I.; Wong, C. W.

    2000-05-01

    We report the first determination of the upper limit for the branching ratio of the CP forbidden decay η-->4π0. No events were observed in a sample of 3.0×107 η decays. The experiment was performed with the Crystal Ball multiphoton spectrometer installed in a separated π- beam at the AGS (Alternating Gradient Synchrotron). At the 90% confidence limit, B\\(η-->4π0\\)<=6.9×10-7.

  5. The rise and fall of horror autotoxicus and forbidden clones.

    Science.gov (United States)

    Jennette, J Charles; Falk, Ronald J

    2010-09-01

    Cui and associates show that healthy individuals have natural autoantibodies (NAAs) specific for myeloperoxidase, proteinase 3, and glomerular basement membrane (GBM) with the same specificity as anti-neutrophil cytoplasmic antibodies and anti-GBM antibodies that are pathogenic. Although Ehrlich proposed horror autotoxicus and Burnet envisioned elimination of forbidden clones, NAAs are present in all healthy individuals and play beneficial homeostatic roles. Pathogenic autoimmunity is dysregulation of natural homeostatic autoimmunity rather than onset of a previously absent self-recognition.

  6. A novel isomorphic phase transition in beta-pyrochlore oxide KOs{sub 2}O{sub 6}: a study using high resolution neutron powder diffraction

    Energy Technology Data Exchange (ETDEWEB)

    Sasai, Kenzo; Kofu, Maiko; Yamaura, Jun-ichi; Hiroi, Zenji; Yamamuro, Osamu [Institute for Solid State Physics, University of Tokyo, Kashiwa, Chiba 277-8581 (Japan); Ibberson, Richard M [ISIS Facility, STFC-Rutherford Appleton Laboratory, Chilton, Didcot OX11 0QX (United Kingdom); Hirota, Kazuma, E-mail: yamamuro@issp.u-tokyo.ac.j [Department of Earth and Space Science, Faculty of Science, Osaka University, Toyonaka, Osaka 560-0043 (Japan)

    2010-01-13

    We have carried out adiabatic calorimetric and neutron powder diffraction experiments on the beta-pyrochlore oxide KOs{sub 2}O{sub 6}, which has a superconducting transition at T{sub c} = 9.6 K and another novel transition at T{sub p} = 7.6 K. A characteristic feature of this compound is that the K ions exhibit rattling vibrations in the cages formed by O atoms even at very low temperatures. The temperature and entropy of the T{sub p} transition is in good agreement with previous data measured using a heat relaxation method, indicating that the present sample is of high purity and the transition entropy, 0.296 J K{sup -1} mol{sup -1}, does not depend on the calorimetric method used. The neutron powder diffraction data show no peak splitting nor extra peaks over the temperature range between 2 and 295 K, suggesting that the T{sub p} transition is a rather unusual isomorphic transition. Rietveld analysis revealed an anomalous expansion of the lattice and a deformation of the O atom cage below 7.6 K. In the low-temperature phase, the distribution of scattering density corresponding to the K ions becomes broader whilst maintaining its maximum at the cage center. Based on these findings, we suggest that the T{sub p} transition is due to the expansion of the cage volume and cooperative condensation of the K ions into the ground state of the rattling motion.

  7. A magnetic boundary layer creating a quasi-cylindrical substructure within a propagating flux rope leading to a plasma beta transition

    CERN Document Server

    Savani, Neel P; Shiota, D; Linton, M G; Kusano, K; Lugaz, N; Rouillard, A P

    2013-01-01

    We present a 2.5D MHD simulation of a magnetic flux rope (FR) propagating in the heliosphere and investigate the cause of the observed sharp plasma beta transition. Specifically, we consider a strong internal magnetic field and an explosive fast start, such that the plasma beta is significantly lower in the FR than the sheath region that is formed ahead. This leads to an unusual FR morphology in the first stage of propagation, while the more traditional view (e.g. from space weather simulations like Enlil) of a `pancake' shaped FR is observed as it approaches 1 AU. We investigate how an equipartition line, defined by a magnetic Weber number, surrounding a core region of a propagating FR can demarcate a boundary layer where there is a sharp transition in the plasma beta. The substructure affects the distribution of toroidal flux, with the majority of the flux remaining in a small core region which maintains a quasi-cylindrical structure. Quantitatively, we investigate a locus of points where the kinetic energy...

  8. Spin-forbidden deprotonation of aqueous nitroxyl (HNO).

    Science.gov (United States)

    Shafirovich, Vladimir; Lymar, Sergei V

    2003-05-28

    The first mechanistic study of a spin-forbidden proton-transfer reaction in aqueous solution is reported. Laser flash photolysis of alkaline trioxodinitrate (N(2)O(3)(2)(-), Angeli's anion) is used to generate a nitroxyl anion in its excited singlet state ((1)NO(-)). Through rapid partitioning between protonation by water and electronic relaxation, (1)NO(-) produces (1)HNO (ground state, yield 96%) and (3)NO(-) (ground state, yield 4%), which comprise a unique conjugate acid-base couple with different ground-state multiplicities. Using the large difference between reactivities of (1)HNO and (3)NO(-) in the peroxynitrite-forming reaction with (3)O(2), the kinetics of spin-forbidden deprotonation reaction (1)HNO + OH(-) --> (3)NO(-) + H(2)O is investigated in H(2)O and D(2)O. Consistent with proton transfer, this reaction exhibits primary kinetic hydrogen isotope effect k(H)/k(D) = 3.1 at 298 K, which is found to be temperature-dependent. Arrhenius pre-exponential factors and activation energies of the second-order rate constant are found to be: log(A, M(-)(1) s(-)(1)) = 10.0 +/- 0.2 and E(a) = 30.0 +/- 1.1 kJ/mol for proton transfer and log(A, M(-)(1) s(-)(1)) = 10.4 +/- 0.1 and E(a) = 35.1 +/- 0.7 kJ/mol for deuteron transfer. Collectively, these data are interpreted to show that the nuclear reorganization requirements arising from the spin prohibition necessitate significant activation before spin change can take place, but the spin change itself must occur extremely rapidly. It is concluded that a synergy between the spin prohibition and the reaction energetics creates an intersystem barrier and is responsible for slowness of the spin-forbidden deprotonation of (1)HNO by OH(-); the spin prohibition alone plays a minor role.

  9. The satellites and hypersatellites of L{alpha}{sub 12} and L{beta}{sub 1} x-ray transitions in zirconium excited by oxygen and neon ions

    Energy Technology Data Exchange (ETDEWEB)

    Czarnota, M; Pajek, M; Banas, D [Institute of Physics, Jan Kochanowski University, 25-406 Kielce (Poland); Dousse, J-Cl; Berset, M; Mauron, O; Maillard, Y-P; Raboud, P A; Hoszowska, J [Department of Physics, University of Fribourg, CH-1700 Fribourg (Switzerland); Polasik, M; Slabkowska, K [Faculty of Chemistry, Nicholas Copernicus University, 87-100 Torun (Poland); Chmielewska, D; Rzadkiewicz, J; Sujkowski, Z, E-mail: marcin@ujk.kielce.p [Soltan Institute for Nuclear Studies, 05-400 Otwock-Swierk (Poland)

    2009-11-01

    The interpretation of L-shell satellites and hypersatellites for L{alpha}{sub 1,2} (L{sub 3{yields}}M{sub 4,5}) and L{beta}{sub 1} (L{sub 2{yields}}M{sub 4}) x-ray transitions in zirconium multiply ionized by oxygen and neon ions is reported. The x-ray spectra were measured with a high-resolution von Hamos spectrometer and interpreted in terms the relativistic multi-configuration Dirac-Fock (MCDF) calculations. The ionization probabilities of L- and M-shell derived from the data are compared with the predictions of the semiclassical approximation (SCA) calculations.

  10. Forbidden nonunique β decays and effective values of weak coupling constants

    Science.gov (United States)

    Haaranen, M.; Srivastava, P. C.; Suhonen, J.

    2016-03-01

    Forbidden nonunique β decays feature shape functions that are complicated combinations of different nuclear matrix elements and phase-space factors. Furthermore, they depend in a very nontrivial way on the values of the weak coupling constants, gV for the vector part and gA for the axial-vector part. In this work we include also the usually omitted second-order terms in the shape functions to see their effect on the computed decay half-lives and electron spectra (β spectra). As examples we study the fourth-forbidden nonunique ground-state-to-ground-state β- decay branches of 113Cd and 115In using the microscopic quasiparticle-phonon model and the nuclear shell model. A striking new feature that is reported in this paper is that the calculated shape of the β spectrum is quite sensitive to the values of gV and gA and hence comparison of the calculated with the measured spectrum shape opens a way to determine the values of these coupling constants. This article is designed to show the power of this comparison, coined spectrum-shape method (SSM), by studying the two exemplary β transitions within two different nuclear-structure frameworks. While the SSM seems to confine the gV values close to the canonical value gV=1.0 , the values of gA extracted from the half-life data and by the SSM emerge contradictory in the present calculations. This calls for improved nuclear-structure calculations and more measured data to systematically employ SSM for determination of the effective value of gA in the future.

  11. Analysis of the noise-induced bursting-spiking transition in a pancreatic beta-cell model

    DEFF Research Database (Denmark)

    Aguirre, J.; Mosekilde, Erik; Sanjuan, M.A.F.

    2004-01-01

    A stochastic model of the electrophysiological behavior of the pancreatic beta cell is studied, as a paradigmatic example of a bursting biological cell embedded in a noisy environment. The analysis is focused on the distortion that a growing noise causes to the basic properties of the membrane po...

  12. Negotiating the COAPRT Learning Outcomes Transition Using Quality Management Tools: A Case Study of the COAPRT Beta Test Site

    Science.gov (United States)

    Ellis, Gary D.

    2014-01-01

    This paper is a case study. It tells the story of the process that the Council on Accreditation for Parks, Recreation, Tourism and Related Professions beta test site created its learning outcomes assessment program. A planning process was used that has evolved from quality management philosophy and practice: DMADV. Use of DMADV required precise…

  13. Beta-elemene blocks epithelial-mesenchymal transition in human breast cancer cell line MCF-7 through Smad3-mediated down-regulation of nuclear transcription factors.

    Directory of Open Access Journals (Sweden)

    Xian Zhang

    Full Text Available Epithelial-mesenchymal transition (EMT is the first step required for breast cancer to initiate metastasis. However, the potential of drugs to block and reverse the EMT process are not well explored. In the present study, we investigated the inhibitory effect of beta-elemene (ELE, an active component of a natural plant-derived anti-neoplastic agent in an established EMT model mediated by transforming growth factor-beta1 (TGF-β1. We found that ELE (40 µg/ml blocked the TGF-β1-induced phenotypic transition in the human breast cancer cell line MCF-7. ELE was able to inhibit TGF-β1-mediated upregulation of mRNA and protein expression of nuclear transcription factors (SNAI1, SNAI2, TWIST and SIP1, potentially through decreasing the expression and phosphorylation of Smad3, a central protein mediating the TGF-β1 signalling pathway. These findings suggest a potential therapeutic benefit of ELE in treating basal-like breast cancer.

  14. Warm Dark Matter Sterile Neutrinos in Electron Capture and Beta Decay Spectra

    Directory of Open Access Journals (Sweden)

    O. Moreno

    2016-01-01

    Full Text Available We briefly review the motivation to search for sterile neutrinos in the keV mass scale, as dark matter candidates, and the prospects to find them in beta decay or electron capture spectra, with a global perspective. We describe the fundamentals of the neutrino flavor-mass eigenstate mismatch that opens the possibility of detecting sterile neutrinos in such ordinary nuclear processes. Results are shown and discussed for the effect of heavy neutrino emission in electron capture in Holmium 163 and in two isotopes of Lead, 202 and 205, as well as in the beta decay of Tritium. We study the deexcitation spectrum in the considered cases of electron capture and the charged lepton spectrum in the case of Tritium beta decay. For each of these cases, we define ratios of integrated transition rates over different regions of the spectrum under study and give new results that may guide and facilitate the analysis of possible future measurements, paying particular attention to forbidden transitions in Lead isotopes.

  15. Large difference between two methods of calculating the integrated Fermi function in superallowed. beta. -decays

    Energy Technology Data Exchange (ETDEWEB)

    Szybisz, L. (Koeln Univ. (Germany, F.R.). Inst. fuer Theoretische Kernphysik); Silbergleit, V.M. (Buenos Aires Univ. Nacional (Argentina). Dept. de Fisica); Sidelnik, J.I. (Comision Nacional de Energia Atomica, Buenos Aires (Argentina). Dept. de Reactores)

    1983-03-03

    The integrated statistical rates for superallowed O/sup +/ - O/sup +/ ..beta..-transitions evaluated according to the most widely used methods proposed by Behrens-Jaenecke-Buehring and Towner-Hardy are compared. It is shown that both calculations are in essential agreement up to mass A=38. However, for heavier nuclei there is a discrepancy. The disagreement, which increases with increasing Z, ranges from 0.07% for /sup 42/Sc to as much as 0.13% for /sup 54/Co and is larger than the errors attached for f-values due to uncertainties in W/sub 0/ (these being about 0.03-0.04%). Moreover, such differences are either comparable to or even larger than the uncertainties in t and deltasub(c). The disagreement is attributed to the different evaluations of the second-forbidden nuclear matrix elements. The choice of the parameters used in both methods is also discussed.

  16. Natural widths and Coster-Kronig transitions of L X-ray spectra in elements between Pd and Sb

    Energy Technology Data Exchange (ETDEWEB)

    Sakakura, Shusuke [Laboratory of Atomic and Molecular Physics, Institute for Chemical Research, Kyoto University, Uji, Kyoto 611 (Japan)]. E-mail: caligula@scl.kyoto-u.ac.jp; Oohashi, Hirofumi [Laboratory of Atomic and Molecular Physics, Institute for Chemical Research, Kyoto University, Uji, Kyoto 611 (Japan); Ito, Yoshiaki [Laboratory of Atomic and Molecular Physics, Institute for Chemical Research, Kyoto University, Uji, Kyoto 611 (Japan); Tochio, Tatsunori [Keihanna Interaction Plaza Inc., 1-7 Seika-cho, Soraku-gun, Kyoto 619-0237 (Japan); Vlaicu, Aurel M. [National Institute of Material Science, SPring-8, Mikazuki, Hyogo 679-5198 (Japan); Yoshikawa, Hideki [National Institute of Material Science, SPring-8, Mikazuki, Hyogo 679-5198 (Japan); Ikenaga, Eiji [Japan Synchrotron Radiation Research Institute (JASRI), 1-1-1 Kouto, Mikazuki-cho, Sayo-gun, Hyogo 679-5198 (Japan); Kobayashi, Keisuke [Japan Synchrotron Radiation Research Institute (JASRI), 1-1-1 Kouto, Mikazuki-cho, Sayo-gun, Hyogo 679-5198 (Japan)

    2006-11-15

    The L{alpha} and L{beta} X-ray emission spectra in the elements between Pd (Z=46) and Sb (Z=51) were measured using a high-resolution double-crystal vacuum spectrometer. The relative intensities of satellite structures, which originate in L {sub 1} L {sub 3} M {sub 4,5} Coster-Kronig transitions, were estimated to that of each diagram line, and compared with calculated values. According to the work of Chen et al. [1977a. Theoretical L-shell Coster-Kronig energies 11{<=}Z{<=}103. At. Data Nucl. Data Tables 19, 97-151], Salgueiro et al. [1987. J. Phys. (Paris) 48 Colloq. C9, 609] and Vlaicu et al. [1998. Investigation of the 74W L emission spectra and satellites. Phys. Rev. A 58, 3544] L {sub 1} L {sub 3} M {sub 4} Coster-Kronig transition is forbidden for 50{<=}Z{<=}77, and L {sub 1} L {sub 3} M {sub 5} Coster-Kronig transition is forbidden for 50{<=}Z{<=}73. The results suggest that L {sub 1} L {sub 3} M {sub 4,5} Coster-Kronig transitions may be allowed even for Sn (Z=50) and Sb (Z=51)

  17. Experimental Sensitivities on Searching for Rare and Forbidden Decays of Charm Mesons at BES-Ⅲ

    Institute of Scientific and Technical Information of China (English)

    ZHAO Ming-Gang; RONG Gang; MA Hai-Long

    2009-01-01

    We discuss the Monte Carlo studies of searching for the rare and forbidden pure-leptonic and semi-leptonic decays of D,0 and D+8 mesons, based on a full Monte Carlo simulation for the BES-Ⅲ detector, with the BES-Ⅲ Offline Software System. The experimental sensitivities of searching for 36 rare and forbidden charm meson decays are estimated.

  18. Generalization of Suppression in Norma Khouri’s Forbidden Love

    Directory of Open Access Journals (Sweden)

    Olya Mariam

    2014-12-01

    Full Text Available The aim of this research is to critique the repercussions of over-generalization of a social issue as depicted in Norma Khouri’s Forbidden Love. The novel/memoir has been written against the 9/11 backdrop and as such serves as means of sensationalizing and exploiting a cultural event which unfortunately echoes in the East. The objective of this research is to highlight the responsibility of the writer in raising or negating awareness.  Investigative journalism such as Anna Broinowski and Malcolm Knox’s helps to highlight the repercussions of such canonship. Michel Foucault’s theory of Discourse Analysis and E Ann Kaplan’s Imperial Gaze have been employed to exploit the core text. The research proves that writers can fictionalize and fabricate events to sensationalize a social practice/ cultural dimension to over generalize and market a given perception. Thereby, helping to develop a condescending attitude amongst (Western audience and reader.

  19. Can $\\beta$-decay probe excited state halos?

    CERN Multimedia

    2002-01-01

    In the first experiment at the newly constructed ISOLDE Facility the first-forbidden $\\beta$-decay of $^{17}$Ne into the first excited state of $^{17}$F has been measured. It is a factor two faster than the corresponding mirror decay and thus gives one of the largest recorded asymmetries for $\\beta$-decays feeding bound final states. Shell-model calculations can only reproduce the asymmetry if the halo structure of the $^{17}$F state is taken into account.

  20. The expression of syndecan-1 and -2 is associated with Gleason score and epithelial-mesenchymal transition markers, E-cadherin and beta-catenin, in prostate cancer.

    Science.gov (United States)

    Contreras, Hector R; Ledezma, Rodrigo A; Vergara, Jorge; Cifuentes, Federico; Barra, Cristina; Cabello, Pablo; Gallegos, Ivan; Morales, Bernardo; Huidobro, Christian; Castellón, Enrique A

    2010-01-01

    The epithelial-mesenchymal transition (EMT) is considered a key step in tumor progression, where the invasive cancer cells change from epithelial to mesenchymal phenotype. During this process, a decrease or loss in adhesion molecules expression and an increase in migration molecules expression are observed. The aim of this work was to determine the expression and cellular distribution of syndecan-1 and -2 (migration molecules) and E-cadherin and beta-catenin (adhesion molecules) in different stages of prostate cancer progression. A quantitative immunohistochemical study of these molecules was carried out in tissue samples from benign prostatic hyperplasia and prostate carcinoma, with low and high Gleason score, obtained from biopsies archives of the Clinic Hospital of the University of Chile and Dipreca Hospital. Polyclonal specific antibodies and amplification system of estreptavidin-biotin peroxidase and diaminobenzidine were used. Syndecan-1 was uniformly expressed in basolateral membranes of normal epithelium, changing to a granular cytoplasmatic expression pattern in carcinomas. Syndecan-2 was observed mainly in a cytoplasmatic granular pattern, with high immunostaining intensity in areas of low Gleason score. E-cadherin was detected in basolateral membrane of normal epithelia showing decreased expression in high Gleason score samples. beta-Catenin was found in cell membranes of normal epithelia changing its distribution toward the nucleus and cytoplasm in carcinoma samples. We concluded that changes in expression and cell distribution of E-cadherin and beta-catenin correlated with the progression degree of prostate adenocarcinoma, suggesting a role of these molecules as markers of progression and prognosis. Furthermore, changes in the pattern expression of syndecan-1 and -2 indicate that both molecules may be involved in the EMT and tumor progression of prostate cancer.

  1. Protective spin-labeled fluorenes maintain amyloid beta peptide in small oligomers and limit transitions in secondary structure

    Energy Technology Data Exchange (ETDEWEB)

    Altman, Robin [Univ. of California, Davis, CA (United States). Dept. of Biochemistry and Molecular Medicine; Ly, Sonny [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States). Physical and Life Science Directorate; Hilt, Silvia [Univ. of California, Davis, CA (United States). Dept. of Biochemistry and Molecular Medicine; Petrlova, Jitka [Univ. of California, Davis, CA (United States). Dept. of Biochemistry and Molecular Medicine; Maezawa, Izumi [Univ. of California Davis, Sacramento, CA (United States). MIND Inst. and Dept. of Pathology and Laboratory Medicine; Kálai, Tamás [Univ. of Pecs (Hungary). Inst. of Organic and Medicinal Chemistry; Hideg, Kálmán [Univ. of Pecs (Hungary). Inst. of Organic and Medicinal Chemistry; Jin, Lee-Way [Univ. of California Davis, Sacramento, CA (United States). MIND Inst. and Dept. of Pathology and Laboratory Medicine; Laurence, Ted A. [Univ. of California, Davis, CA (United States). Dept. of Biochemistry and Molecular Medicine; Voss, John C. [Univ. of California, Davis, CA (United States). Dept. of Biochemistry and Molecular Medicine

    2015-12-01

    Alzheimer’s disease is characterized by the presence of extracellular plaques comprised of amyloid beta (Aβ) peptides. Soluble oligomers of the Aβ peptide underlie a cascade of neuronal loss and dysfunction associated with Alzheimer's disease. Single particle analyses of Aβ oligomers in solution by fluorescence correlation spectroscopy (FCS) were used to provide real-time descriptions of how spin-labeled fluorenes (SLFs; bi-functional small molecules that block the toxicity of Aβ) prevent and disrupt oligomeric assemblies of Aβ in solution. The FCS results, combined with electron paramagnetic resonance spectroscopy and circular dichroism spectroscopy, demonstrate SLFs can inhibit the growth of Aβ oligomers and disrupt existing oligomers while retaining Aβ in a largely disordered state. Furthermore, while the ability of SLF to block Aβ toxicity correlates with a reduction in oligomer size, our results suggest the conformation of Aβ within the oligomer determines the toxicity of the species. Attenuation of Aβ toxicity, which has been associated primarily with the soluble oligomeric form, can be achieved through redistribution of the peptides into smaller oligomers and arrest of the fractional increase in beta secondary structure.

  2. Structures and phase transitions of the A7PSe6 (A = Ag, Cu) argyrodite-type ionic conductors. II. Beta- and gamma-Cu7PSe6

    Science.gov (United States)

    Gaudin; Boucher; Petricek; Taulelle; Evain

    2000-06-01

    The crystal structures of two of the three polymorphic forms of the Cu7PSe6 argyrodite compound are determined by means of single-crystal X-ray diffraction. In the high-temperature form, at 353 K, i.e. 33 K above the first phase transition, gamma-Cu7PSe6 crystallizes in cubic symmetry, space group F43m. The full-matrix least-squares refinement of the structure leads to the residual factors R = 0.0201 and wR = 0.0245 for 31 parameters and 300 observed independent reflections. In the intermediate form, at room temperature, beta-Cu7PSe6 crystallizes again in cubic symmetry, but with space group P2(1)3. Taking into account a merohedric twinning, the refinement of the beta-Cu7PSe6 structure leads to the residual factors R = 0.0297 and wR = 0.0317 for 70 parameters and 874 observed, independent reflections. The combination of a Gram-Charlier development of the Debye-Waller factor and a split model for copper cations reveals the possible diffusion paths of the d10 species in the gamma-Cu7PSe6 ionic conducting phase. The partial ordering of the Cu+ d10 element at the phase transition is found in concordance with the highest probability density sites of the high-temperature phase diffusion paths. A comparison between the two Cu7PSe6 and Ag7PSe6 analogues is carried out, stressing the different mobility of Cu+ and Ag+ and their relative stability in low-coordination chalcogenide environments.

  3. First observation of the beta decay of neutron-rich $^{218}Bi$ by the pulsed-release technique and resonant laser ionization

    CERN Document Server

    De Witte, H; Borzov, I N; Caurier, E; Cederkäll, J; De Smet, A; Eckhaudt, S; Fedorov, D V; Fedosseev, V; Franchoo, S; Górska, M; Grawe, H; Huber, G; Huyse, M; Janas, Z; Köster, U; Kurcewicz, W; Kurpeta, J; Plochocki, A; Van Duppen, P; Van de Vel, K; Weissman, L

    2004-01-01

    The neutron-rich isotope /sup 218/Bi has been produced in proton- induced spallation of a uranium carbide target at the ISOLDE facility at CERN, extracted from the ion source by the pulsed-release technique and resonant laser ionization, and its beta decay is studied for the first time. A half-life of 33(1)s was measured and is discussed in the self-consistent continuum-quasi particle-random- phase approximation framework that includes Gamow-Teller and first- forbidden transitions. A level scheme was constructed for /sup 218 /Po, and a deexcitation pattern of stretched E2 transitions 8/sup +/ to 6/sup +/ to 4/sup +/ to 2/sup +/ to 0/sup +/ to the ground state is suggested. Shell-model calculations based on the Kuo-Herling interaction reproduce the experimental results satisfactorily. (28 refs).

  4. A Distributed Activation Energy Model of Thermodynamically Inhibited Nucleation and Growth Reactions and its Application to the beta-delta Phase Transition of HMX

    Energy Technology Data Exchange (ETDEWEB)

    Burnham, A K; Weese, R K; Weeks, B L

    2004-06-18

    Detailed and global models are presented for thermodynamically inhibited nucleation-growth reactions and applied to the {beta}-{delta} Phase Transition of HMX (nitramine octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine). The detailed model contains separate kinetic parameters for the nucleation process, including an activation energy distribution resulting from a distribution of defect energies, and for movement of the resulting reaction interface within a single particle. A thermodynamic inhibition term is added to both processes so that the rates go to zero at the transition temperature. The global model adds the thermodynamic inhibition term to the extended Prout-Tompkins nucleation-growth formalism for single particles or powders. Model parameters are calibrated from differential scanning calorimetry data. The activation energy for nucleation (333 kJ/mol) is substantially higher than that for growth (29.3 kJ/mol). Use of a small activation energy distribution ({approx}400 J/mol) for the defects improves the fit to a powered sample for both the early and late stages of the transition. The effective overall activation energy for the global model (208.8 kJ/mol) is in between that of nucleation and growth. Comparison of the two models with experiment indicates the thermodynamic inhibition term is more important than the energy distribution feature for this transition. Based on the applicability of the Prout-Tompkins kinetics approach to a wide range of organic and inorganic materials, both models should have equally broad applicability for thermodynamically constrained reactions.

  5. Bad Beta, Good Beta

    OpenAIRE

    Campbell, John; Vuolteenaho, Tuomo

    2003-01-01

    This paper explains the size and value "anomalies" in stock returns using an economically motivated two-beta model. We break the beta of a stock with the market portfolio into two components, one reflecting news about the market's future cash flows and one reflecting news about the market's discount rates. Intertemporal asset pricing theory suggests that the former should have a higher price of risk; thus beta, like cholesterol, comes in "had" and "good" varieties. Empirically, we find that v...

  6. Tracing Slow Winds from T Tauri Stars via Low Velocity Forbidden Line Emission

    CERN Document Server

    Simon, M N; Edwards, S; Feng, W; Gorti, U; Hollenbach, D; Rigliaco, E; Keane, J T

    2016-01-01

    Using Keck/HIRES spectra {\\Delta}v ~ 7 km/s, we analyze forbidden lines of [O I] 6300 {\\AA}, [O I] 5577 {\\AA} and [S II] 6731 {\\AA} from 33 T Tauri stars covering a range of disk evolutionary stages. After removing a high velocity component (HVC) associated with microjets, we study the properties of the low velocity component (LVC). The LVC can be attributed to slow disk winds that could be magnetically (MHD) or thermally (photoevaporative) driven. Both of these winds play an important role in the evolution and dispersal of protoplanetary material. LVC emission is seen in all 30 stars with detected [O I] but only in 2 out of eight with detected [S II] , so our analysis is largely based on the properties of the [O I] LVC. The LVC itself is resolved into broad (BC) and narrow (NC) kinematic components. Both components are found over a wide range of accretion rates and their luminosity is correlated with the accretion luminosity, but the NC is proportionately stronger than the BC in transition disks. The FWHM of...

  7. Foreign gas broadening and shift of the strongly ``forbidden'' lead line at 1278.9nm

    Science.gov (United States)

    Horvatic, Vlasta; Veza, Damir; Movre, Mladen; Niemax, Kay; Vadla, Cedomil

    2008-06-01

    The collisional broadening and shift rate coefficients of the "forbidden" 6p 2 3P 0 → 6p 2 3P 1 transition in lead were determined by diode laser absorption measurements performed simultaneously in two resistively heated hot-pipes. One hot-pipe contained Pb vapor and noble gas (Ar or He) at low pressure, while the other was filled with Pb and noble gas at variable pressure. The measurements were performed at temperatures of 1220 K and 1290 K, i.e., lead number densities of 4.8 × 10 15 cm - 3 and 1.2 × 10 16 cm - 3 . The broadening rates were obtained by fitting the experimental collisionally broadened absorption line shapes to theoretical Voigt profiles. The shift rates were determined by measuring the difference between the peak absorption positions in the spectra measured simultaneously in the heat pipe filled with noble gas at reference pressure and the one with noble gas at variable pressure. The following data for the broadening and shift rate coefficients due to collisions with Ar and He were obtained: γBAr = (3.4 ± 0.1) × 10 - 10 cm 3 s - 1 , γBHe = (3.8 ± 0.1) × 10 - 10 cm 3 s - 1 , γSAr = (- 7.3 ± 0.8) × 10 - 11 cm 3 s - 1 , γSHe = (- 6.5 ± 0.7) × 10 - 11 cm 3 s - 1 .

  8. Forbidden and intercombination lines of RR Telescopii: wavelength measurements and energy levels

    CERN Document Server

    Young, P R; Lobel, A

    2011-01-01

    Ultraviolet and visible spectra of the symbiotic nova RR Telescopii are used to derive reference wavelengths for many forbidden and intercombination transitions of ions +1 to +6 of elements C, N, O, Ne, Na, Mg, Al, Si, P, S, Cl, Ar, K and Ca. The wavelengths are then used to determine new energy values for the levels within the ions' ground configurations or first excited configuration. The spectra were measured by the Space Telescope Imaging Spectrograph of the Hubble Space Telescope and the UltraViolet Echelle Spectrograph of the European Southern Observatory in 2000 and 1999, respectively, and cover 1140 to 6915 A. Particular care was taken to assess the accuracy of the wavelength scale between the two instruments. An investigation of the profiles of the emission lines reveals that the nebula consists of at least two plasma components at different velocities. The components have different densities, and a simple model of the lines' emissions demonstrates that most of the lines principally arise from the hi...

  9. The Life of Pi Star: Exploring the Exciting and Forbidden Worlds of the Benzophenone Photophore.

    Science.gov (United States)

    Dormán, György; Nakamura, Hiroyuki; Pulsipher, Abigail; Prestwich, Glenn D

    2016-12-28

    The widespread applications of benzophenone (BP) photochemistry in biological chemistry, bioorganic chemistry, and material science have been prominent in both academic and industrial research. BP photophores have unique photochemical properties: upon n-π* excitation at 365 nm, a biradicaloid triplet state is formed reversibly, which can abstract a hydrogen atom from accessible C-H bonds; the radicals subsequently recombine, creating a stable covalent C-C bond. This light-directed covalent attachment process is exploited in many different ways: (i) binding/contact site mapping of ligand (or protein)-protein interactions; (ii) identification of molecular targets and interactome mapping; (iii) proteome profiling; (iv) bioconjugation and site-directed modification of biopolymers; (v) surface grafting and immobilization. BP photochemistry also has many practical advantages, including low reactivity toward water, stability in ambient light, and the convenient excitation at 365 nm. In addition, several BP-containing building blocks and reagents are commercially available. In this review, we explore the "forbidden" (transitions) and excitation-activated world of photoinduced covalent attachment of BP photophores by touring a colorful palette of recent examples. In this exploration, we will see the pros and cons of using BP photophores, and we hope that both novice and expert photolabelers will enjoy and be inspired by the breadth and depth of possibilities.

  10. $\\beta$-delayed neutrons from oriented $^{137,139}$I and $^{87,89}$Br nuclei

    CERN Multimedia

    We propose a world-first measurement of the angular distribution of $\\beta$‐delayed n and $\\gamma$-radiation from oriented $^{137, 139}$I and $^{87,89}$Br nuclei, polarised at low temperature at the NICOLE facility. $\\beta$­-delayed neutron emission is an increasingly important decay mechanism as the drip line is approached and its detailed understanding is essential to phenomena as fundamental as the r‐process and practical as the safe operation of nuclear power reactors. The experiments offer sensitive tests of theoretical input concerning the allowed and first­‐forbidden $\\beta$‐decay strength, the spin-density of neutron emitting states and the partial wave barrier penetration as a function of nuclear deformation. In $^{137}$I and $^{87}$Br the decay feeds predominantly the ground state of the daughters $^{136}$Xe and $^{86}$Kr whereas in $^{139}$I and $^{89}$Br we will explore the use of n-$\\gamma$- coincidence to study neutron transitions to the first and second excited states in the daughters...

  11. $\\beta$-delayed neutrons from oriented $^{137,139}$I and $^{87,89}$Br nuclei

    CERN Document Server

    Grzywacz, Robert; Stone, Nicholas; Köster, Ulli; Singh, Barlaj; Bingham, Carrol; Gaulard, S; Kolos, Karolina; Madurga, Miguel; Nikolov, J; Otsubo, T; Roccia, S; Veskovic, Miroslav; Walker, Phil; Walters, William

    2013-01-01

    We propose a world-­‐first measurement of the angular distribution of $\\beta$-­‐delayed n and $\\gamma$- radiation from oriented $^{137, 139}$I and $^{87,89}$Br nuclei, polarised at low temperature at the NICOLE facility. $\\beta$-­‐delayed neutron emission is an increasingly important decay mechanism as the drip line is approached and its detailed understanding is essential to phenomena as fundamental as the r‐process and practical as the safe operation of nuclear power reactors. The experiments offer sensitive tests of theoretical input concerning the allowed and first-­‐forbidden $\\beta$‐decay strength, the spin-­‐density of neutron emitting states and the partial wave barrier penetration as a function of nuclear deformation. In $^{137}$I and $^{87}$Br the decay feeds predominantly the ground state of the daughters $^{136}$Xe and $^{86}$Kr whereas in $^{139}$I and $^{89}$Br we will explore the use of n-$\\gamma$- coincidence to study neutron transitions to the first and second excited state...

  12. Forbidden oxygen lines in comets at various heliocentric distances

    CERN Document Server

    Decock, A; Hutsemékers, D; Manfroid, J

    2012-01-01

    We present a study of the three forbidden oxygen lines [OI] located in the optical region (i.e., 5577.339 {\\AA}, 6300.304 {\\AA} and 6363.776 {\\AA}) in order to better understand the production of these atoms in cometary atmospheres. The analysis is based on 48 high-resolution and high signal-to-noise spectra collected with UVES at the ESO VLT between 2003 and 2011 referring to 12 comets of different origins observed at various heliocentric distances. The flux ratios I_6300/I_6364 and G/R=I_5577/(I_6300+I_6364) are evaluated to determine the parent species of the oxygen atoms by comparison with theoretical models. This analysis confirms that, at around 1 AU, H2O is the main parent molecule producing oxygen atoms. At heliocentric distances > 2.5 AU, the G/R ratio is changing rapidly, an indication that other molecules are starting to contribute. CO and CO2, the most abundant species after H2O in the coma, are good candidates and the G/R ratio is used to estimate their abundances. We found that the CO2 abundance...

  13. Searches for Rare or Forbidden Semileptonic Charm Decays

    Energy Technology Data Exchange (ETDEWEB)

    Lees, J.P.

    2011-08-15

    We present searches for rare or forbidden charm decays of the form X{sub c}{sup +} {yields} h{sup {+-}}{ell}{sup {-+}}{ell}{sup ({prime})+}, where X{sub c}{sup +} is a charm hardron (D{sup +}, D{sub s}{sup +}, or {Lambda}{sub c}{sup +}), h{sup {+-}} is a pion, kaon, or proton, and {ell}{sup ({prime}){+-}} is an electron or muon. The analysis is based on 384 fb{sup -1} of e{sup +}e{sup -} annihilation data collected at or close to the {Upsilon}(4S) resonance with the BABAR detector at the SLAC National Accelerator Laboratory. No significant signal is observed for any of the 35 decay modes that are investigated. We establish 90% confidence-level upper limits on the branching fractions between 1 x 10{sup -6} and 44 x 10{sup -6} depending on the channel. In most cases, these results represent either the first limits or significant improvements on existing limits for the decay modes studied.

  14. Exocometary gas structure, origin and physical properties around $\\beta$ Pictoris through ALMA CO multi-transition observations

    CERN Document Server

    Matrà, L; Wyatt, M C; Kral, Q; Wilner, D J; Panić, O; Hughes, A M; de Gregorio-Monsalvo, I; Hales, A; Augereau, J -C; Greaves, J; Roberge, A

    2016-01-01

    Recent ALMA observations unveiled the structure of CO gas in the 23 Myr-old $\\beta$ Pictoris planetary system, a component that has been discovered in many similarly young debris disks. We here present ALMA CO J=2-1 observations, at an improved spectro-spatial resolution and sensitivity compared to previous CO J=3-2 observations. We find that 1) the CO clump is radially broad, favouring the resonant migration over the giant impact scenario for its dynamical origin, 2) the CO disk is vertically tilted compared to the main dust disk, at an angle consistent with the scattered light warp. We then use position-velocity diagrams to trace Keplerian radii in the orbital plane of the disk. Assuming a perfectly edge-on geometry, this shows a CO scale height increasing with radius as $R^{0.75}$, and an electron density (derived from CO line ratios through NLTE analysis) in agreement with thermodynamical models. Furthermore, we show how observations of optically thin line ratios can solve the primordial versus secondary ...

  15. Permitted and forbidden sets in discrete-time linear threshold recurrent neural networks.

    Science.gov (United States)

    Yi, Zhang; Zhang, Lei; Yu, Jiali; Tan, Kok Kiong

    2009-06-01

    The concepts of permitted and forbidden sets enable a new perspective of the memory in neural networks. Such concepts exhibit interesting dynamics in recurrent neural networks. This paper studies the basic theories of permitted and forbidden sets of the linear threshold discrete-time recurrent neural networks. The linear threshold transfer function has been regarded as an adequate transfer function for recurrent neural networks. Networks with this transfer function form a class of hybrid analog and digital networks which are especially useful for perceptual computations. Networks in discrete time can directly provide algorithms for efficient implementation in digital hardware. The main contribution of this paper is to establish foundations of permitted and forbidden sets. Necessary and sufficient conditions for the linear threshold discrete-time recurrent neural networks are obtained for complete convergence, existence of permitted and forbidden sets, as well as conditionally multiattractivity, respectively. Simulation studies explore some possible interesting practical applications.

  16. Impact of the first-forbidden β decay on the production of A ∼ 195 r-process peak

    Science.gov (United States)

    Nishimura, Nobuya; Podolyák, Zsolt; Fang, Dong-Liang; Suzuki, Toshio

    2016-05-01

    We investigated the effects of first-forbidden transitions in β decays on the production of the r-process A ∼ 195 peak. The theoretical calculated β-decay rates with β-delayed neutron emission were examined using several astrophysical conditions. As the FF decay is dominant in N ∼ 126 neutron-rich nuclei, their inclusion shortens β-decay lifetimes and shifts the abundance peak towards higher masses. Additionally, the inclusion of the β-delayed neutron emission results in a wider abundance peak, and smoothens the mass distribution by removing the odd-even mass staggering. The effects are commonly seen in the results of all adopted astrophysical models. Nevertheless there are quantitative differences, indicating that remaining uncertainty in the determination of half-lives for N = 126 nuclei is still significant in order to determine the production of the r-process peak.

  17. Impact of the first-forbidden β decay on the production of A∼195 r-process peak

    Directory of Open Access Journals (Sweden)

    Nobuya Nishimura

    2016-05-01

    Full Text Available We investigated the effects of first-forbidden transitions in β decays on the production of the r-process A∼195 peak. The theoretical calculated β-decay rates with β-delayed neutron emission were examined using several astrophysical conditions. As the FF decay is dominant in N∼126 neutron-rich nuclei, their inclusion shortens β-decay lifetimes and shifts the abundance peak towards higher masses. Additionally, the inclusion of the β-delayed neutron emission results in a wider abundance peak, and smoothens the mass distribution by removing the odd–even mass staggering. The effects are commonly seen in the results of all adopted astrophysical models. Nevertheless there are quantitative differences, indicating that remaining uncertainty in the determination of half-lives for N=126 nuclei is still significant in order to determine the production of the r-process peak.

  18. Long Non-Coding RNA MALAT1 Mediates Transforming Growth Factor Beta1-Induced Epithelial-Mesenchymal Transition of Retinal Pigment Epithelial Cells.

    Directory of Open Access Journals (Sweden)

    Shuai Yang

    Full Text Available To study the role of long non-coding RNA (lncRNA MALAT1 in transforming growth factor beta 1 (TGF-β1-induced epithelial-mesenchymal transition (EMT of retinal pigment epithelial (RPE cells.ARPE-19 cells were cultured and exposed to TGF-β1. The EMT of APRE-19 cells is confirmed by morphological change, as well as the increased expression of alpha-smooth muscle actin (αSMA and fibronectin, and the down-regulation of E-cadherin and Zona occludin-1(ZO-1 at both mRNA and protein levels. The expression of lncRNA MALAT1 in RPE cells were detected by quantitative real-time PCR. Knockdown of MALAT1 was achieved by transfecting a small interfering RNA (SiRNA. The effect of inhibition of MALAT1 on EMT, migration, proliferation, and TGFβ signalings were observed. MALAT1 expression was also detected in primary RPE cells incubated with proliferative vitreoretinopathy (PVR vitreous samples.The expression of MALAT1 is significantly increased in RPE cells incubated with TGFβ1. MALAT1 silencing attenuates TGFβ1-induced EMT, migration, and proliferation of RPE cells, at least partially through activating Smad2/3 signaling. MALAT1 is also significantly increased in primary RPE cells incubated with PVR vitreous samples.LncRNA MALAT1 is involved in TGFβ1-induced EMT of human RPE cells and provides new understandings for the pathogenesis of PVR.

  19. Beta Thalassemia

    Science.gov (United States)

    Beta thalassemia is found in people of Mediterranean, Middle Eastern, African, South Asian (Indian, Pakistani, etc.), Southeast Asian and Chinese descent. 1 Beta Thalassemia ßß Normal beta globin genes found on chromosomes ...

  20. O( Ⅰ ,Ⅱ) 禁戒线极光及其光化学反应%O(Ⅰ,Ⅱ) Forbidden Lines Aurora and Their Photochemical Reaction

    Institute of Scientific and Technical Information of China (English)

    唐远河; 陈光德; 张淳民; 刘汉臣; 竹有章

    2005-01-01

    利用干涉成像光谱技术被动探测上层大气风场所使用的光源主要是氧禁戒线极光.讨论了禁戒跃迁出现较强谱线需要的两个条件,对满足上述条件的上层大气中的原子氧(OⅠ)和离子氧(OⅡ)的可见光波段禁戒线进行了详细的计算,并对应指出产生这些O(Ⅰ , Ⅱ)禁戒线的光化学反应.得出的结论是被动探测上层大气风场所用极光源可以使用所指认的10条O(Ⅰ , Ⅱ)禁戒线和允许线: 557.7 nm, 630.0/636.4/639.3 nm, 672.8 nm, 732.2/733.2 nm, 777.7/777.6/777.4 nm, 比加拿大的风成像光谱干涉仪(WINDII)使用的极光谱线增添了5条: 639.3 nm, 672.8 nm, 777.7/777.6/777.4 nm,扩展了成像光谱干涉仪的波段范围.%To detect wind field in the upper atmosphere passive methods was used with imaging interferometer technique the main source is O(Ⅰ,Ⅱ) forbidden aurora. For stronger forbidden transition line, two necessary conditions of theoretical calculation are metastable and enough small electron density. O (Ⅰ, Ⅱ) satisfies the conditions and its forbidden lines are indicated. Then the corresponding photochemical reaction of O (Ⅰ, Ⅱ) forbidden aurora was investigated. The conclusion is that 10 forbidden (allowed) lines (557.7 nm, 630.0/636.4/639.3 nm, 672.8 nm, 732.2/733.2 nm,777.7/777.6/777.4 nm) can be used to detect upper atmospheric wind field, 5 lines (639.3 nm, 672.8 nm, 777.7/777.6/777.4 nm) increased comparing to WINDII, the visible wavelengths aurora is enlarged for imaging interferometer.

  1. Multidimensional Effects in Nonadiabatic Statistical Theories of Spin-Forbidden Kinetics: A Case Study of (3)O + CO → CO2.

    Science.gov (United States)

    Jasper, Ahren W

    2015-07-16

    The appropriateness of treating crossing seams of electronic states of different spins as nonadiabatic transition states in statistical calculations of spin-forbidden reaction rates is considered. We show that the spin-forbidden reaction coordinate, the nuclear coordinate perpendicular to the crossing seam, is coupled to the remaining nuclear degrees of freedom. This coupling gives rise to multidimensional effects that are not typically included in statistical treatments of spin-forbidden kinetics. Three qualitative categories of multidimensional effects may be identified: static multidimensional effects due to the geometry-dependence of the local shape of the crossing seam and of the spin-orbit coupling, dynamical multidimensional effects due to energy exchange with the reaction coordinate during the seam crossing, and nonlocal (history-dependent) multidimensional effects due to interference of the electronic variables at second, third, and later seam crossings. Nonlocal multidimensional effects are intimately related to electronic decoherence, where electronic dephasing acts to erase the history of the system. A semiclassical model based on short-time full-dimensional trajectories that includes all three multidimensional effects as well as a model for electronic decoherence is presented. The results of this multidimensional nonadiabatic statistical theory (MNST) for the (3)O + CO → CO2 reaction are compared with the results of statistical theories employing one-dimensional (Landau-Zener and weak coupling) models for the transition probability and with those calculated previously using multistate trajectories. The MNST method is shown to accurately reproduce the multistate decay-of-mixing trajectory results, so long as consistent thresholds are used. The MNST approach has several advantages over multistate trajectory approaches and is more suitable in chemical kinetics calculations at low temperatures and for complex systems. The error in statistical

  2. Forbidden Dark Matter at the Weak Scale via the Top Portal

    CERN Document Server

    Delgado, Antonio; Raj, Nirmal

    2016-01-01

    At the tail of its velocity distribution, cold dark matter (DM) can annihilate at finite temperature to states heavier than itself. We explore the possibility that DM freezeout is dictated by these "forbidden annihilations" at the electroweak scale. Demanding that annihilation products be Standard Model particles, we find that for the forbidden mechanism to primarily set the DM relic abundance, DM must couple predominantly, if not solely, to top quarks. This can be arranged by invoking a non-trivial flavor structure such as Minimal Flavor Violation. We avail two avenues to achieve the correct thermal cross-section, requiring a mediator exchanged in the $s$- or $t$-channel. These simplified models submit easily to direct detection and collider searches, and necessarily hide from indirect detection signals. Viable supersymmetric spectra involving the forbidden mechanism may be found if combined with co-annihilation.

  3. Forbidden dark matter at the weak scale via the top portal

    Science.gov (United States)

    Delgado, Antonio; Martin, Adam; Raj, Nirmal

    2017-02-01

    At the tail of its velocity distribution, cold dark matter (DM) can annihilate at finite temperature to states heavier than itself. We explore the possibility that DM freeze-out is dictated by these "forbidden annihilations" at the electroweak scale. Demanding that annihilation products be Standard Model particles, we find that for the forbidden mechanism to primarily set the DM relic abundance, DM must couple predominantly, if not solely, to top quarks. This can be arranged by invoking a nontrivial flavor structure such as minimal flavor violation. We avail two avenues to achieve the correct thermal cross section, requiring a mediator exchanged in the s - or t -channel. These simplified models submit easily to direct detection and collider searches, and necessarily hide from indirect detection signals. Viable supersymmetric spectra involving the forbidden mechanism may be found if combined with coannihilation.

  4. Beta-ray angular distributions of spin aligned {sup 8}Li and {sup 8}B

    Energy Technology Data Exchange (ETDEWEB)

    Sumikama, T. [Department of Physics, Osaka University, Toyonaka, Osaka 560-0043 (Japan); Iwakoshi, T. [Department of Physics, Osaka University, Toyonaka, Osaka 560-0043 (Japan); Nagatomo, T. [Department of Physics, Osaka University, Toyonaka, Osaka 560-0043 (Japan); Ogura, M. [Department of Physics, Osaka University, Toyonaka, Osaka 560-0043 (Japan); Nakashima, Y. [Department of Physics, Osaka University, Toyonaka, Osaka 560-0043 (Japan); Fujiwara, H. [Department of Physics, Osaka University, Toyonaka, Osaka 560-0043 (Japan); Matsuta, K. [Department of Physics, Osaka University, Toyonaka, Osaka 560-0043 (Japan); Minamisono, T. [Department of Physics, Osaka University, Toyonaka, Osaka 560-0043 (Japan); Mihara, M. [Department of Physics, Osaka University, Toyonaka, Osaka 560-0043 (Japan); Fukuda, M. [Department of Physics, Osaka University, Toyonaka, Osaka 560-0043 (Japan); Minamisono, K. [TRIUMF, 4004 Wesbrook Mall, Vancouver, British Columbia, V6T 2A3 (Canada); Yamaguchi, T. [Gesellschaft fuer Schwerionenforschung, Planckstrasse 1, D-64291 Darmstadt (Germany)

    2004-12-27

    The alignment correlation terms in the {beta}-ray angular distributions from spin aligned {sup 8}Li and {sup 8}B have been measured precisely. The difference of these terms between the mirror pair is compared with the prediction. As a result, the G-parity violating induced tensor term is found to be small. The significant contribution from the second-forbidden matrix elements is shown by comparing with the {beta}-{alpha} correlation coefficients.

  5. Is Articulation from Two- to Four-Year Colleges an Allowed or a Forbidden Transition?

    Science.gov (United States)

    Susskind, Tamar Y.

    1997-01-01

    Argues that patterns of student flow between two- and four-year institutions are not linear and that the permutations of student situations affect the datasets that are used to both defend and question the effectiveness and transferability of two-year programs. (DDR)

  6. Comparison of the Electronic Transitions of Unconjugated Thiones and Imines: An Exercise in the Application of Symmetry Selection Rules

    Science.gov (United States)

    Worman, James J.; And Others

    1978-01-01

    The purpose of this paper is to show how symmetry selection rules can be used to determine whether certain of the electronic transitions exhibited by the title compounds are allowed or forbidden by symmetry. (Author/CP)

  7. Forbidden reflections from the aramid PPTA—A novel correlation with stacking faults

    Indian Academy of Sciences (India)

    Anjana Jain; Kalyani Vijayan

    2004-02-01

    The occurrence of space group forbidden reflections in the X-ray diffraction patterns from the aramid PPTA has been correlated with the presence of stacking faults. The fraction of sample affected by the presence of such faults has also been estimated.

  8. Detection of forbidden line components of lithium-like carbon in stellar spectra

    CERN Document Server

    Werner, K; Hoyer, D; Quinet, P

    2016-01-01

    We report the first identification of forbidden line components from an element heavier than helium in the spectrum of astrophysical plasmas. As yet, these components were identified only in laboratory plasmas and not in astrophysical objects. Forbidden components are well known for neutral helium lines in hot stars, particularly in helium-rich post-AGB stars and white dwarfs. We discovered that two hitherto unidentified lines in the ultraviolet spectra of hot hydrogen-deficient (pre-) white dwarfs can be identified as forbidden line components of triply ionized carbon (C IV). The forbidden components (3p-4f and 3d-4d) appear in the blue and red wings of the strong, Stark broadened 3p-4d and 3d-4f lines at 1108 Angstroem and 1169 Angstroem, respectively. They are visible over a wide effective temperature range (60,000-200,000 K) in helium-rich (DO) white dwarfs and PG1159 stars that have strongly oversolar carbon abundances.

  9. On proton excitation of forbidden lines in positive ions

    Energy Technology Data Exchange (ETDEWEB)

    Burgess, Alan [Department of Applied Mathematics and Theoretical Physics, Wilberforce Road, Cambridge CB3 0WA (United Kingdom); Tully, John A [Observatoire de la Cote d' Azur, Departement Cassiopee, BP 4229, 06304 Nice Cedex 4 (France)

    2005-08-14

    The semi-classical impact parameter approximations used by Bahcall and Wolf and by Bely and Faucher, for proton excitation of electric quadrupole transitions in positive ions, both fail at high energies, giving cross sections which do not fall off correctly as constant/E. This is in contrast with the pioneering example of Seaton for Fe{sup +13} and of Reid and Schwarz for S{sup +3}, both of whom achieve the correct functional form, but do not ensure the correct constant of proportionality. By combining the Born and semi-classical approximations one can obtain cross sections which have the full correct behaviour as E {yields} {infinity}, and hence, rate coefficients which have the correct high temperature behaviour ({approx}C/T{sup 1/2} with the correct value of C). We provide a computer program for calculating these. An error in Faucher's derivation of the Born formula is also discussed.

  10. First-forbidden β -decay rates, energy rates of β -delayed neutrons and probability of β -delayed neutron emissions for neutron-rich nickel isotopes

    Energy Technology Data Exchange (ETDEWEB)

    Nabi, Jameel-Un; Iftikhar, Zafar [GIK Institute of Engineering Sciences and Technology, Faculty of Engineering Sciences, Khyber Pakhtunkhwa (Pakistan); Cakmak, Necla [Karabuek University, Department of Physics, Karabuek (Turkey)

    2016-01-15

    First-forbidden (FF) transitions can play an important role in decreasing the calculated half-lives specially in environments where allowed Gamow-Teller (GT) transitions are unfavored. Of special mention is the case of neutron-rich nuclei where, due to phase-space amplification, FF transitions are much favored. We calculate the allowed GT transitions in various pn-QRPA models for even-even neutron-rich isotopes of nickel. Here we also study the effect of deformation on the calculated GT strengths. The FF transitions for even-even neutron-rich isotopes of nickel are calculated assuming the nuclei to be spherical. Later we take into account deformation of nuclei and calculate GT + unique FF transitions, stellar β -decay rates, energy rate of β -delayed neutrons and probability of β -delayed neutron emissions. The calculated half-lives are in excellent agreement with measured ones and might contribute in speeding-up of the r-matter flow. (orig.)

  11. Relations between forbidden line Fe/H and delta Mone for F and early-G stars

    Science.gov (United States)

    McNamara, D. H.; Powell, J. M.

    1985-11-01

    The new catalog of forbidden line Fe/H determinations of Cayrel de Strobel et al. (1985) have been used to calibrate forbidden line Fe/H in terms of the metal abundance parameter delta mone. Three relations were found corresponding to F1-F5 stars, F5-F8 stars, and F8-G2 stars. Quadratic equations were found necessary to represent the data of the two early groups. Serious errors in forbidden line Fe/H determinations of early metal-poor F stars can result if the previous linear calibrations are used.

  12. Contribution of forbidden orbits in the photoabsorption spectra of atoms and molecules in a magnetic field

    Science.gov (United States)

    Matzkin, A.; Dando, P. A.; Monteiro, T. S.

    2003-02-01

    In a previous work [Phys. Rev. A 66, 013410 (2002)], we noted a partial disagreement between quantum R matrix and semiclassical calculations of photoabsorption spectra of molecules in a magnetic field. We show that this disagreement is due to a nonvanishing contribution of processes, which are forbidden according to the usual semiclassical formalism. Formulas to include these processes are obtained by using a refined stationary phase approximation. The resulting higher order in ħ contributions also account for previously unexplained “recurrences without closed orbits.” Quantum and semiclassical photoabsorption spectra for Rydberg atoms and molecules in a magnetic field are calculated and compared to assess the validity of the first-order forbidden orbit contributions.

  13. Contribution of forbidden orbits in the photoabsorption spectra of atoms and molecules in a magnetic field

    CERN Document Server

    Matzkin, A; Monteiro, T S

    2003-01-01

    In a previous work [Phys. Rev. A \\textbf{66}, 0134XX (2002)] we noted a partial disagreement between quantum R-matrix and semiclassical calculations of photoabsorption spectra of molecules in a magnetic field. We show this disagreement is due to a non-vanishing contribution of processes which are forbidden according to the usual semiclassical formalism. Formulas to include these processes are obtained by using a refined stationary phase approximation. The resulting higher order in $\\hbar$ contributions also account for previously unexplained ``recurrences without closed-orbits''. Quantum and semiclassical photoabsorption spectra for Rydberg atoms and molecules in a magnetic field are calculated and compared to assess the validity of the first-order forbidden orbit contributions.

  14. A Block Based Adaptive Video Data Hiding Method Using Forbidden Zone Data Hiding

    DEFF Research Database (Denmark)

    Banoth, Rajkumar

    2013-01-01

    -Data hiding is a process of embedding information into some sort of host media. Especially video data hiding has become an important research topic as it is complex when compared data hiding process in other media. This paper proposes a new method based on erasure correction capability of RA codes...... using forbidden zone data hiding. This method finds suitable host signals that are useful for data hiding. The proposed method also overcomes the problems of frame drop and inserts attacks. The simulation results reveal that this video data hiding framework can be used in data hiding applications...... of the real world. Key Words – RA codes, selective embedding, watermarking, forbidden zone data hiding, simulation, selective embedding, erasure handling, block partitioning...

  15. A minisum model with forbidden regions for locating a semi-desirable facility in the plane

    DEFF Research Database (Denmark)

    Juel, Henrik; Brimberg, Jack

    1998-01-01

    Most facilities in today's technological society may be classified as semi-desirable. That is, the facility provides a benefit or service to society, while adversely affecting the quality of life or social values in a number of possible ways. The paper proposes a location model for a new semi......-desirable facility that accounts for the service costs by a standard minisum objective with arbitrary travel distance function. The social costs are imputed by specifying around each demand point or population center a convex forbidden region, also defined by an arbitrary distance metric, in which the new facility...... may not be located. A general solution algorithm is suggested, and the methodology is applied to circular forbidden regions and special travel distance functions....

  16. A minisum model with forbidden regions for locating a semi-desirable facility in the plane

    DEFF Research Database (Denmark)

    Brimberg, Jack; Juel, Henrik

    Most facilities in today's technological society may be classified as semi-desirable. That is, the facility provides a benefit or service to society, while adversely affecting the quality of life or social values in a number of possible ways. The paper proposes a location model for a new semi......-desirable facility which accounts for the service costs by a standard minisum objective with arbitrary travel distance function. The social costs are imputed by specifying around each demand point or population center a convex forbidden region, also defined by an arbitrary distance metric, in which the new facility...... may not be located. A general solution algorithm is suggested, and the methodology applied to circular forbidden regions and special travel distance functions....

  17. Can Cosmological Constant be a Forbidden Zone (GAP) in Quantum Vacuum

    CERN Document Server

    Pankovic, Vladan; Ciganovic, Simo

    2008-01-01

    In this work we suggest, without detailed mathematical analysis, a hypothesis on the physical meaning of cosmological constant. It is primarily based on a conceptual analogy with energy characteristics of the crystal lattice structure, i.e. energy zones theory in solid state physics. Namely, according to some theories (holographic principle, emergent gravity etc.) it is supposed that empty space, i.e. quantum vacuum holds a structure like to crystal lattice. It implies a possibility of the existence of totally occupied zones consisting of many levels of the negative energies as well as at least one negative energy forbidden zone, i.e. negative energy gap without any (occupied or empty) level of the negative energy. We suppose that given negative energy forbidden zone in the quantum vacuum represents effectively a positive energy zone without quantum particles that corresponds to cosmological constant. Also we suggest some other (less extravagant) model of the cosmological constant. Here cosmological constant ...

  18. Spin-polarized x-ray emission of 3d transition-metal ions : A comparison via K alpha and K beta detection

    NARCIS (Netherlands)

    Wang, Xin; deGroot, F.M.F.; Cramer, SP

    1997-01-01

    This paper demonstrates that spin-polarized x-ray-excitation spectra can be obtained using K alpha emission as well as K beta lines. A spin-polarized analysis of K alpha x-ray emission and the excitation spectra by K alpha detection on a Ni compound is reported. A systematic analysis of the first-ro

  19. Spin-polarized x-ray emission of 3d transition-metal ions : A comparison via K alpha and K beta detection

    NARCIS (Netherlands)

    Wang, Xin; deGroot, F.M.F.; Cramer, SP

    1997-01-01

    This paper demonstrates that spin-polarized x-ray-excitation spectra can be obtained using K alpha emission as well as K beta lines. A spin-polarized analysis of K alpha x-ray emission and the excitation spectra by K alpha detection on a Ni compound is reported. A systematic analysis of the

  20. Analysis of Infrared Divergence in OZI-Forbidden Decays of Orthoquarkonia

    Institute of Scientific and Technical Information of China (English)

    ZHAO Shu-Min; PANG Xue-Xia; LIU Li-Quan; LI Yong-Hui

    2009-01-01

    It is interesting to investigate the OZI-forbidden decays of orthoquarkoknium, J/ψ→γπ0(γη,γη'), J/ψ→ π+π-(π0π0). At first glance, there is infrared divergence in the above processes. In this work, to clear the mist we use the factorization method with the light cone wavefunction of the final state light meson. We prove straightforwardly that the infrared divergence can be eliminated completely.

  1. Optically Forbidden Excitations of 3s Electron of Argon by Fast Electron Impact

    Institute of Scientific and Technical Information of China (English)

    朱林繁; 成华东; 刘小井; 田鹏; 苑震生; 李文斌; 徐克尊

    2003-01-01

    The electron energy loss spectrum of argon in the energy region of 24.5-30.5eV was measured at 2.5 keV impact energy. The line profile parameters of the optically forbidden excitations of 3s-1ns (n = 4-6) and 3s-1nd (n = 3-7) of argon, I.e.,Eγ,Г,q and p,were determined.

  2. Contribution of a pure NCG forbidden process to the Z associated Higgs production

    Energy Technology Data Exchange (ETDEWEB)

    Bradji, O.; Mebarki, N. [Theoretical Phys. Lab., Faculty of Physics -USTHBB. P. 32 Bab Ezzouar 16079, Algiers (Algeria); Laboratoire de Physique Mathematique et Subatomique, Mentouri University, Constantine (Algeria)

    2012-06-27

    The contribution of the pure NCG forbidden subprocess gg{yields}ZHis calculated. It is shown that the cross section becomes important at the LHC energies and depends strongly on the choice of the noncommutativity parameter. Because of the gluons luminosity inside the proton, it becomes comparable to that of the commutative standard model subprocess qq(bar sign)ZH for reasonable values of the NCG parameter.

  3. Creation of graphic database specifying android arm mechanism work envelope taking into account forbidden zones position

    Science.gov (United States)

    Pritykin, F. N.; Nebritov, V. I.

    2017-06-01

    The structure of graphic database specifying the shape and the work envelope projection position of an android arm mechanism with various positions of the known in advance forbidden zones is proposed. The technique of analytical assignment of the work envelope based on the methods of analytical geometry and theory of sets is represented. The conducted studies can be applied in creation of knowledge bases for intellectual systems of android control functioning independently in the sophisticated environment.

  4. Spectroscopic Diagnostics of Solar Magnetic Flux Ropes Using Iron Forbidden Line

    CERN Document Server

    Cheng, X

    2016-01-01

    In this Letter, we present Interface Region Imaging Spectrograph Fe XXI 1354.08 A forbidden line emission of two magnetic flux ropes (MFRs) that caused two fast coronal mass ejections with velocities of $\\ge$1000 km s$^{-1}$ and strong flares (X1.6 and M6.5) on 2014 September 10 and 2015 June 22, respectively. The EUV images at the 131 A and 94 A passbands provided by the Atmospheric Imaging Assembly on board Solar Dynamics Observatory reveal that both MFRs initially appear as suspended hot channel-like structures. Interestingly, part of the MFRs is also visible in the Fe XXI 1354.08 forbidden line, even prior to the eruption, e.g., for the SOL2014-09-10 event. However, the line emission is very weak and that only appears at a few locations but not the whole structure of the MFRs. This implies that the MFRs could be comprised of different threads with different temperatures and densities, based on the fact that the formation of the Fe XXI forbidden line requires a critical temperature ($\\sim$11.5 MK) and dens...

  5. Spectroscopic Diagnostics of Solar Magnetic Flux Ropes Using Iron Forbidden Line

    Science.gov (United States)

    Cheng, X.; Ding, M. D.

    2016-05-01

    In this Letter, we present Interface Region Imaging Spectrograph Fe xxi 1354.08 Å forbidden line emission of two magnetic flux ropes (MFRs) that caused two fast coronal mass ejections with velocities of ≥1000 km s-1 and strong flares (X1.6 and M6.5) on 2014 September 10 and 2015 June 22, respectively. The extreme-ultraviolet images at the 131 and 94 Å passbands provided by the Atmospheric Imaging Assembly on board Solar Dynamics Observatory reveal that both MFRs initially appear as suspended hot channel-like structures. Interestingly, part of the MFRs is also visible in the Fe xxi 1354.08 forbidden line, even prior to the eruption, e.g., for the SOL2014-09-10 event. However, the line emission is very weak and that only appears at a few locations but not the whole structure of the MFRs. This implies that the MFRs could be comprised of different threads with different temperatures and densities, based on the fact that the formation of the Fe xxi forbidden line requires a critical temperature (˜11.5 MK) and density. Moreover, the line shows a non-thermal broadening and a blueshift in the early phase. It suggests that magnetic reconnection at that time has initiated; it not only heats the MFR and, at the same time, produces a non-thermal broadening of the Fe xxi line but also produces the poloidal flux, leading to the ascension of the MFRs.

  6. A Far Ultraviolet Spectroscopic Explorer Survey of Coronal Forbidden Lines in Late-Type Stars

    CERN Document Server

    Redfield, S; Linsky, J L; Ake, T B; Dupree, A K; Robinson, R D; Young, P R; Redfield, Seth; Ayres, Thomas R.; Linsky, Jeffrey L.; Ake, Thomas B.; Robinson, Richard D.; Young, Peter R.

    2002-01-01

    We present a survey of coronal forbidden lines detected in Far Ultraviolet Spectroscopic Explorer (FUSE) spectra of nearby stars. Two strong coronal features, Fe XVIII 974 A and Fe XIX 1118 A, are observed in 10 of the 26 stars in our sample. Various other coronal forbidden lines, observed in solar flares, also were sought but not detected. The Fe XVIII feature, formed at log T (K) = 6.8, appears to be free of blends, whereas the Fe XIX line can be corrupted by a C I multiplet. FUSE observations of these forbidden iron lines at spectral resolution R ~ 15,000 provides the opportunity to study dynamics of hot coronal plasmas. We find that the velocity centroid of the Fe XVIII feature deviates little from the stellar rest frame, confirming that the hot coronal plasma is confined. The observed line widths generally are consistent with thermal broadening at the high temperatures of formation and show little indication of additional turbulent broadening. The fastest rotating stars, 31 Com, alpha Aur Ab, and AB Dor,...

  7. Getting Information on |Ue3|2 from Neutrinoless Double Beta Decay

    Directory of Open Access Journals (Sweden)

    Alexander Merle

    2007-01-01

    neutrinoless double beta decay. We show that typically a lower limit on |Ue3| as a function of the smallest neutrino mass can be set. Furthermore, we give the values of the sum of neutrino masses and |Ue3| which are allowed and forbidden by an experimental upper limit on the effective mass. Alternative explanations for neutrinoless double beta decay, Dirac neutrinos or unexplained cosmological features would be required if future measurements showed that the values lie in the respective regions. Moreover, we show that a measurement of |Ue3| from neutrinoless double beta decay is very difficult due to the expected errors on the effective mass and the oscillation parameters.

  8. High-resolution spectroscopy of the 2(2)Piuforbidden transitions of C2+.

    Science.gov (United States)

    Tarsitano, Christopher G; Neese, Christopher F; Oka, Takeshi

    2004-10-01

    The electronic absorption spectrum of the (0,2), (1,3), and (6,9) bands of the B4Sigmau(-)-X4Sigmag- system of C2+ was obtained using the velocity modulation technique in conjunction with heterodyne detection. The rotationally resolved spectrum shows perturbations, which are attributed to the 2(2)Piu state. The mixing between the B4Sigmau- state and the 2(2)Piu state for nearly degenerate levels generated enough intensity borrowing to observe twenty 2(2)Piuforbidden transitions. The parameters of a model Hamiltonian were fit to the bands and their corresponding forbidden transitions. Line position measurements, line strength factors, and expectation values for the orbital angular momentum Lambda' for the forbidden transitions are reported. Molecular parameters from the global fit of each band, including their corresponding forbidden transitions, are reported.

  9. Data supporting beta-amyloid dimer structural transitions and protein–lipid interactions on asymmetric lipid bilayer surfaces using MD simulations on experimentally derived NMR protein structures

    Directory of Open Access Journals (Sweden)

    Sara Y. Cheng

    2016-06-01

    Full Text Available This data article supports the research article entitled “Maximally Asymmetric Transbilayer Distribution of Anionic Lipids Alters the Structure and interaction with Lipids of an Amyloidogenic Protein Dimer Bound to the Membrane Surface” [1]. We describe supporting data on the binding kinetics, time evolution of secondary structure, and residue-contact maps of a surface-absorbed beta-amyloid dimer protein on different membrane surfaces. We further demonstrate the sorting of annular and non-annular regions of the protein/lipid bilayer simulation systems, and the correlation of lipid-number mismatch and surface area per lipid mismatch of asymmetric lipid membranes.

  10. Strengths of gamma-ray transitions in A = 6–44 nuclei (III)

    NARCIS (Netherlands)

    Endt, P.M.

    1979-01-01

    The present tables list the strengths (in Weisskopf units) of over 2400 γ-ray transitions in A = 6–44 nuclei, classified according to character (electric or magnetic, multipolarity, isospin forbiddenness). Selected transitions from unbound states are included. The strengths for isovector E1 and M1 t

  11. Search for the CP forbidden decay {nu} {yields} 4{pi}{sup 0}.

    Energy Technology Data Exchange (ETDEWEB)

    Prakhov, S.; Tippens, W. B.; Allgower, C.; Bekrenev, V.; Berger, E.; Spinka, H.; High Energy Physics; Univ. of California; Petersburg Nuclear Physics Inst.

    2000-05-22

    We report the first determination of the upper limit for the branching ratio of the CP forbidden decay {eta}{yields}4{pi}{sup 0}. No events were observed in a sample of 3.0 x 10{sup 7} {eta} decays. The experiment was performed with the Crystal Ball multiphoton spectrometer installed in a separated {pi}{sup -} beam at the AGS (Alternating Gradient Synchrotron). At the 90% confidence limit, B({eta}{yields}4{pi}{sup 0}){<=}6.9x10{sup -7}.

  12. Search for the CP Forbidden Decay {eta}{yields}4{pi}{sup 0}

    Energy Technology Data Exchange (ETDEWEB)

    Prakhov, S. [University of California, Los Angeles, Los Angeles, California 90095-1547 (United States); Tippens, W. B. [University of California, Los Angeles, Los Angeles, California 90095-1547 (United States); Allgower, C. [Argonne National Laboratory, Argonne, Illinois 60439 (United States); Bekrenev, V. [Petersburg Nuclear Physics Institute, Gatchina, Leningrad District, Russia 188350 (Russian Federation); Berger, E. [University of California, Los Angeles, Los Angeles, California 90095-1547 (United States); Briscoe, W. J. [George Washington University, Washington, D.C. 20052 (United States); Clajus, M. [University of California, Los Angeles, Los Angeles, California 90095-1547 (United States); Comfort, J. R. [Arizona State University, Tempe, Arizona 85287-1504 (United States); Craig, K. [Arizona State University, Tempe, Arizona 85287-1504 (United States); Grosnick, D. [Valparaiso University, Valparaiso, Indiana 46383 (United States)] (and others)

    2000-05-22

    We report the first determination of the upper limit for the branching ratio of the CP forbidden decay {eta}{yields}4{pi}{sup 0} . No events were observed in a sample of 3.0x10{sup 7} {eta} decays. The experiment was performed with the Crystal Ball multiphoton spectrometer installed in a separated {pi}{sup -} beam at the AGS (Alternating Gradient Synchrotron). At the 90% confidence limit, B({eta}{yields}4{pi}{sup 0}){<=} 6.9x10{sup -7} . (c) 2000 The American Physical Society.

  13. The Inclination, Pitch Angle and Forbidden Radius of Spiral Arms of PGC 35105

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    We have studied some properties including surface brightness in the u, g,r, i, and z bands of the nearly face-on galaxy PGC 35105. By subtracting a model surface brightness distribution from the observed image we obtain the residual image that shows only the spiral arms freed from the contamination by the bulge. From this we measured the the inclination, pitch angle, and forbidden radius (identified with the innermost point of the arm) for each of the two arms; and that for each of the five observing bands. We found these three parameters are largely independent of the observing band.

  14. Spectroscopic Diagnostics of Solar Magnetic Flux Ropes Using Iron Forbidden Line

    OpenAIRE

    Cheng, X; Ding, M. D.

    2016-01-01

    In this Letter, we present Interface Region Imaging Spectrograph Fe XXI 1354.08 A forbidden line emission of two magnetic flux ropes (MFRs) that caused two fast coronal mass ejections with velocities of $\\ge$1000 km s$^{-1}$ and strong flares (X1.6 and M6.5) on 2014 September 10 and 2015 June 22, respectively. The EUV images at the 131 A and 94 A passbands provided by the Atmospheric Imaging Assembly on board Solar Dynamics Observatory reveal that both MFRs initially appear as suspended hot c...

  15. Evolution of outer membrane beta-barrels from an ancestral beta beta hairpin.

    Science.gov (United States)

    Remmert, M; Biegert, A; Linke, D; Lupas, A N; Söding, J

    2010-06-01

    Outer membrane beta-barrels (OMBBs) are the major class of outer membrane proteins from Gram-negative bacteria, mitochondria, and plastids. Their transmembrane domains consist of 8-24 beta-strands forming a closed, barrel-shaped beta-sheet around a central pore. Despite their obvious structural regularity, evidence for an origin by duplication or for a common ancestry has not been found. We use three complementary approaches to show that all OMBBs from Gram-negative bacteria evolved from a single, ancestral beta beta hairpin. First, we link almost all families of known single-chain bacterial OMBBs with each other through transitive profile searches. Second, we identify a clear repeat signature in the sequences of many OMBBs in which the repeating sequence unit coincides with the structural beta beta hairpin repeat. Third, we show that the observed sequence similarity between OMBB hairpins cannot be explained by structural or membrane constraints on their sequences. The third approach addresses a longstanding problem in protein evolution: how to distinguish between a very remotely homologous relationship and the opposing scenario of "sequence convergence." The origin of a diverse group of proteins from a single hairpin module supports the hypothesis that, around the time of transition from the RNA to the protein world, proteins arose by amplification and recombination of short peptide modules that had previously evolved as cofactors of RNAs.

  16. Low to high confinement transition theory of finite-beta drift-wave driven shear flow and its comparison with data from DIII-D

    Science.gov (United States)

    Guzdar, P. N.; Kleva, R. G.; Groebner, R. J.; Gohil, P.

    2004-03-01

    Shear flow stabilization of edge turbulence in tokamaks has been the accepted paradigm for the improvement in confinement observed in high (H) confinement mode plasmas. Results on the generation of zonal flow and fields in finite β plasmas are presented. This theory yields a criterion for bifurcation from low to high (L-H) confinement mode, proportional to Te/√Ln , where Te is the electron temperature and Ln is the density scale-length at the steepest part of the density gradient. When this parameter exceeds a critical value (mostly determined by the strength of the toroidal magnetic field), the transition occurs. The predicted threshold based on this parameter shows good agreement with edge measurements on discharges undergoing L-H transitions in DIII-D [J. L. Luxon, R. Anderson, F. Batty et al., in Proceedings of the 11th Conference on Plasma Physics and Controlled Fusion Research, 1986 (International Atomic Energy Agency, Vienna, 1987), Vol. I, p. 159]. The observed differences in the transitions with the reversal of the toroidal magnetic field are reconciled in terms of this critical parameter due to the differences in the density gradient scale-lengths in the edge. The theory also provides a possible explanation for lowered threshold power, pellet injection H modes in DIII-D, thereby providing a unified picture of the varied observations on the L-H transition.

  17. Gamow-Teller strengths of the inverse beta transition Yb-176 -> Lu-176 for spectroscopy of proton-proton and other sub-MeV solar neutrinos

    NARCIS (Netherlands)

    Fujiwara, M; Akimune, H; van den Berg, AM; Cribier, M; Daito, [No Value; Ejiri, H; Fujimura, H; Fujita, Y; Goodman, CD; Hara, K; Harakeh, MN; Ihara, E; Ishikawa, T; Janecke, J; Kawabata, T; Raghavan, RS; Schwarz, K; Tanaka, M; Yamanaka, T; Yosoi, M; Zegers, RGT

    2000-01-01

    Discrete Gamow-Teller (GT) transitions Yb-176 --> Lu-176 at low excitation energies have been measured via the (He-3, t) reaction at 450 MeV and at 0 degrees. For Yb-176, two low-lying states are observed, setting low thresholds Q(nu) = 301 and 445 keV for neutrino (nu) capture. Capture rates estima

  18. High-resolution, far-ultraviolet study of Beta Draconis (G2 Ib-II) - Transition region structure and energy balance

    Science.gov (United States)

    Brown, A.; Jordan, C.; Stencel, R. E.; Linsky, J. L.; Ayres, T. R.

    1984-01-01

    High-resolution far ultraviolet spectra of the star Beta Draconis have been obtained with the IUE satellite. The observations and emission line data from the spectra are presented, the interpretation of the emission line widths and shifts is discussed, and the implications are given in terms of atmospheric properties. The emission measure distribution is derived, and density diagnostics involving both line ratios and line opacity arguments is investigated. The methods for calculating spherically symmetric models of the atmospheric structure are outlined, and several such models are presented. The extension of these models to log T(e) greater than 5.3 using the observed X-ray flux is addressed, the energy balance of an 'optimum' model is investigated, and possible models of energy transport and deposition are discussed.

  19. The interstellar carbon abundance. II - Rho Ophiuchi and Beta Scorpii

    Science.gov (United States)

    Welty, D. E.; York, D. G.; Hobbs, L. M.

    1986-01-01

    A procedure designed to obtain increased sensitivity from high-dispersion IUE spectra by using a flat-field spectrum to remove nonrandom noise due to the response pattern of the SEC vidicon detector is described. Application of this procedure to spectra of Rho Oph and Beta(1) Sco near the spin-forbidden interstellar 2325 line of C II yields 2 sigma upper limits on absorption of W (lambda) not greater than about 4 mA. The resulting depletion of carbon from the interstellar gas toward Rho Oph exceeds a factor of 1.4.

  20. Faint HI 21-cm Emission Line Wings at Forbidden-Velocities

    CERN Document Server

    Kang, Ji-hyun

    2007-01-01

    We present the results of a search for faint HI 21-cm emission line wings at velocities forbidden by Galactic rotation in the Galactic plane using the Leiden/Dwingeloo HI Survey data and the HI Southern Galactic Plane Survey data. These ``forbidden-velocity wings (FVWs)'' appear as protruding excessive emission in comparison with their surroundings in limited (< 2 deg) spatial regions over velocity extent more than ~20 km/s in large-scale (l-v) diagrams. Their high-velocities imply that there should be some dynamical phenomena associated. We have identified 87 FVWs. We present their catalog, and discuss their distribution and statistical properties. We found that 85% of FVWs are not coincident with known supernova remnants (SNRs), galaxies, or high-velocity clouds. Their natures are currently unknown. We suspect that many of them are fast-moving HI shells and filaments associated with the oldest SNRs that are essentially invisible except via their HI line emission. We discuss other possible origins.

  1. Plant species forbidden in health food and their toxic constituents, toxicology and detoxification.

    Science.gov (United States)

    Xu, Xi-Lin; Shang, Yu; Jiang, Jian-Guo

    2016-02-01

    Many plants with pharmacological efficacies are widely used as ingredients in so-called "health foods", but many of them are toxic. In order to ensure the safety of "health food", the Chinese Ministry of Health has listed 59 materials that are forbidden from being used in health food and are called health food forbidden species (HFFS). This review focuses on 47 plants among the HFFS to discuss research regarding their pharmacology, toxicology, and detoxification methods. According to the literature published in the last 2 decades, the main constituents and the pharmacology of such plants are described here, especially their toxic constituents and toxicology. The toxicity mechanisms of several typical toxic components from the 47 plants are outlined and some effective detoxification methods are introduced. Although all HFFS are poisonous, they are considered to be useful in the treatment of many diseases. How to keep their pharmacological effects and at the same time decrease their toxicity is a great challenge. In the future, more attention should be paid to the application of modern science and technology in the exploration of the toxicology and detoxification of HFFS.

  2. Implications of Two-component Dark Matter Induced by Forbidden Channels and Thermal Freeze-out

    CERN Document Server

    Aoki, Mayumi

    2016-01-01

    We consider a model of two-component dark matter based on a hidden $U(1)_D$ symmetry, in which relic densities of the dark matter are determined by forbidden channels and thermal freeze-out. The hidden $U(1)_D$ symmetry is spontaneously broken to a residual $\\mathbb{Z}_4$ symmetry, and the lightest $\\mathbb{Z}_4$ charged particle can be a dark matter candidate. Moreover, depending on the mass hierarchy in the dark sector, we have two-component dark matter. We show that the relic density of the lighter dark matter component can be determined by forbidden annihilation channels which require larger couplings compared to the normal freeze-out mechanism. As a result, a large self-interaction of the lighter dark matter component can be induced, which may solve small scale problems of $\\Lambda$CDM model. On the other hand, the heavier dark matter component is produced by normal freeze-out mechanism. We find that interesting implications emerge between the two dark matter components in this framework. We explore dete...

  3. Understanding the rate of spin-forbidden thermolysis of HN3 and CH3N3

    Science.gov (United States)

    Besora, Maria; Harvey, Jeremy Noel

    2008-07-01

    The pyrolysis of the simplest azides HN3 and CH3N3 has been studied computationally. Nitrogen extrusion leads to the production of NH or CH3N. The azides have singlet ground states but the nitrenes CH3N and NH have triplet ground states. The competition between spin-allowed decomposition to the excited state singlet nitrenes and the spin-forbidden N2 loss is explored using accurate electronic structure methods (CASSCF/cc-pVTZ and MR-AQCC/cc-pVTZ) as well as statistical rate theories. Nonadiabatic rate theories are used for the dissociation leading to the triplet nitrenes. For HN3, 3NH formation is predicted to dominate at low energy, and the calculated rate constant agrees very well with energy-resolved experimental measurements. Under thermal conditions, however, the singlet and triplet pathways are predicted to occur competitively, with the spin-allowed product increasingly favored at higher temperatures. For CH3N3 thermolysis, spin-allowed dissociation to form 1CH3N should largely dominate at all temperatures, with spin-forbidden formation of 3CH3N almost negligible. Singlet methyl nitrene is very unstable and should rearrange to CH2NH immediately upon formation, and the latter species may lose H2 competitively with vibrational cooling, depending on temperature and pressure.

  4. Single-Molecule Surface-Enhanced Raman Scattering Spectrum of Non-Resonant Aromatic Amine Showing Raman Forbidden Bands

    CERN Document Server

    Yamamoto, Yuko S; Ozaki, Yukihiro; Zhang, Zhenglong; Kozu, Tomomi; Itoh, Tamitake; Nakanishi, Shunsuke

    2016-01-01

    We present the experimentally obtained single-molecule (SM) surface-enhanced Raman scattering (SERS) spectrum of 4-aminibenzenethiol (4-ABT), also known as para-aminothiophenol (PATP). Measured at a 4-ABT concentration of 8 * 10^-10 M, the spectra show Raman forbidden modes. The SM-SERS spectrum of 4-ABT obtained using a non-resonant visible laser is different from the previously reported SERS spectra of 4-ABT, and could not be reconstructed using quantum mechanical calculations. Careful classical assignments (not based on quantum-mechanical calculations) are reported, and indicate that differences in the reported spectra of 4-ABT are mainly due to the appearance of Raman forbidden bands. The presence of Raman forbidden bands can be explained by the charge-transfer (CT) effect of 4-ABT adsorbed on the silver nanostructures, indicating a breakdown of Raman selection rules at the SERS hotspot.

  5. Beta and muon decays

    Energy Technology Data Exchange (ETDEWEB)

    Galindo, A.; Pascual, P.

    1967-07-01

    These notes represent a series of lectures delivered by the authors in the Junta de Energia Nuclear, during the Spring term of 1965. They were devoted to graduate students interested in the Theory of Elementary Particles. Special emphasis was focussed into the computational problems. Chapter I is a review of basic principles (Dirac equation, transition probabilities, final state interactions.) which will be needed later. In Chapter II the four-fermion punctual Interaction is discussed, Chapter III is devoted to the study of beta-decay; the main emphasis is given to the deduction of the formulae corresponding to electron-antineutrino correlation, electron energy spectrum, lifetimes, asymmetry of electrons emitted from polarized nuclei, electron and neutrino polarization and time reversal invariance in beta decay. In Chapter IV we deal with the decay of polarized muons with radiative corrections. Chapter V is devoted to an introduction to C.V.C. theory. (Author)

  6. Percolation transitions with nonlocal constraint.

    Science.gov (United States)

    Shim, Pyoung-Seop; Lee, Hyun Keun; Noh, Jae Dong

    2012-09-01

    We investigate percolation transitions in a nonlocal network model numerically. In this model, each node has an exclusive partner and a link is forbidden between two nodes whose r-neighbors share any exclusive pair. The r-neighbor of a node x is defined as a set of at most N(r) neighbors of x, where N is the total number of nodes. The parameter r controls the strength of a nonlocal effect. The system is found to undergo a percolation transition belonging to the mean-field universality class for r1/2, the system undergoes a peculiar phase transition from a nonpercolating phase to a quasicritical phase where the largest cluster size G scales as G~N(α) with α=0.74(1). In the marginal case with r=1/2, the model displays a percolation transition that does not belong to the mean-field universality class.

  7. Recent progress report on DNA B-Z transition modulated by rare earth-amino acid complex and Alzheimer's disease amyloid beta

    Institute of Scientific and Technical Information of China (English)

    GENG

    2010-01-01

    Rare earth dements have unique physical, magnetic, luminescent and catalytic properties. They have been successfully used as medicine and probes in luminescent resonance energy transfer (LRET) for bioassays, as well as reagents for diagnosis in magnetic resonance imaging (MRI). In this progress report, we will focus on recent progress on how rare earth amino complexes bind to DNA and change DNA structure, especially on DNA B-Z transition induced by rare earth amino acid complex and its potential impact on Alzheimer's disease (AD).

  8. Minimal forbidden induced subgraphs of graphs of bounded clique-width and bounded linear clique-width

    OpenAIRE

    Meister, Daniel; Rotics, Udi

    2013-01-01

    In the study of full bubble model graphs of bounded clique-width and bounded linear clique-width, we determined complete sets of forbidden induced subgraphs, that are minimal in the class of full bubble model graphs. In this note, we show that (almost all of) these graphs are minimal in the class of all graphs. As a corollary, we can give sets of minimal forbidden induced subgraphs for graphs of bounded clique-width and for graphs of bounded linear clique-width for arbitrary bounds.

  9. CCAAT/enhancer binding protein beta (C/EBPβ) isoform balance as a regulator of epithelial-mesenchymal transition in mouse mammary epithelial cells

    Energy Technology Data Exchange (ETDEWEB)

    Miura, Yuka; Hagiwara, Natsumi [Department of Bioscience, Graduate School of Science and Technology, Kwansei Gakuin University, Hyogo, 2-1 Gakuen, Sanda 669-1337 Japan (Japan); Radisky, Derek C. [Department of Cancer Biology, Mayo Clinic, Jacksonville, FL 32225 (United States); Hirai, Yohei, E-mail: y-hirai@kwansei.ac.jp [Department of Bioscience, Graduate School of Science and Technology, Kwansei Gakuin University, Hyogo, 2-1 Gakuen, Sanda 669-1337 Japan (Japan)

    2014-09-10

    Activation of the epithelial-mesenchymal transition (EMT) program promotes cell invasion and metastasis, and is reversed through mesenchymal-epithelial transition (MET) after formation of distant metastases. Here, we show that an imbalance of gene products encoded by the transcriptional factor C/EBPβ, LAP (liver-enriched activating protein) and LIP (liver-enriched inhibitory protein), can regulate both EMT- and MET-like phenotypic changes in mouse mammary epithelial cells. By using tetracycline repressive LIP expression constructs, we found that SCp2 cells, a clonal epithelial line of COMMA1-D cells, expressed EMT markers, lost the ability to undergo alveolar-like morphogenesis in 3D Matrigel, and acquired properties of benign adenoma cells. Conversely, we found that inducible expression of LAP in SCg6 cells, a clonal fibroblastic line of COMMA1-D cells, began to express epithelial keratins with suppression of proliferation. The overexpression of the C/EBPβ gene products in these COMMA1-D derivatives was suppressed by long-term cultivation on tissue culture plastic, but gene expression was maintained in cells grown on Matrigel or exposed to proteasome inhibitors. Thus, imbalances of C/EBPβ gene products in mouse mammary epithelial cells, which are affected by contact with basement membrane, are defined as a potential regulator of metastatic potential. - Highlights: • We created a temporal imbalance of C/EBPβ gene products in the mammary model cells. • The temporal up-regulation of LIP protein induced EMT-like cell behaviors. • The temporal up-regulation of LAP protein induced MET-like cell behaviors. • Excess amount of C/EBPβ gene products were eliminated by proteasomal-degradation. • Basement membrane components attenuated proteasome-triggered protein elimination.

  10. Coupling-induced excitation of a forbidden surface plasmon mode of a gold nanorod

    Institute of Scientific and Technical Information of China (English)

    YAO HaoMin; LI Zhi; GONG QiHuang

    2009-01-01

    Using the finite-difference time-domain (FDTD) method, we simulate the coupling between a gold nanorod and gold nanoparticles with different plasmonic resonant frequencies/volumes as well as that between the nanorod and a dielectric nanosphere. The influences of coupling with different nanoparti-cles on the excitation of a forbidden longitudinal surface plasmon mode of the nanorod under normal incidence are investigated. It is found that the cause of this excitation is the broken symmetry of the local electric field experienced by the nanorod resulting from the charge pileup on the other nanopar-ticle. This result is valuable for understanding the near-field optical characterization of plasmonic metal nanoparticles.

  11. Coupling-induced excitation of a forbidden surface plasmon mode of a gold nanorod

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    Using the finite-difference time-domain(FDTD) method,we simulate the coupling between a gold nanorod and gold nanoparticles with different plasmonic resonant frequencies/volumes as well as that between the nanorod and a dielectric nanosphere.The influences of coupling with different nanoparticles on the excitation of a forbidden longitudinal surface plasmon mode of the nanorod under normal incidence are investigated.It is found that the cause of this excitation is the broken symmetry of the local electric field experienced by the nanorod resulting from the charge pileup on the other nanoparticle.This result is valuable for understanding the near-field optical characterization of plasmonic metal nanoparticles.

  12. Generalized laws of refraction that can lead to wave-optically forbidden light-ray fields.

    Science.gov (United States)

    Courtial, Johannes; Tyc, Tomáš

    2012-07-01

    The recent demonstration of a metamaterial phase hologram so thin that it can be classified as an interface in the effective-medium approximation [Science 334, 333 (2011)] has dramatically increased interest in generalized laws of refraction. Based on the fact that scalar wave optics allows only certain light-ray fields, we divide generalized laws of refraction into two categories. When applied to a planar cross section through any allowed light-ray field, the laws in the first category always result in a cross section through an allowed light-ray field again, whereas the laws in the second category can result in a cross section through a forbidden light-ray field.

  13. Precision half-life measurement of the 4-fold forbidden β decay of V50

    Science.gov (United States)

    Dombrowski, H.; Neumaier, S.; Zuber, K.

    2011-05-01

    A sensitive search of the 4-fold forbidden nonunique decay of V50 has been performed. A total mass measuring time product of 186 kg d has been accumulated. A reliable half-life value with the highest precision so far of (2.29±0.25)×1017 years of the electron capture decay of V50 into the first excited state of Ti50 could be obtained. A photon emission line following the β decay into the first excited state of Cr50 could not be observed, resulting in a lower limit on the half-life of the β-decay branch of 1.7×1018 years. This is not in good agreement with a claimed observation of this decay branch published in 1989.

  14. The forbidden quest and the analytic ideal: the superego and insight.

    Science.gov (United States)

    Blum, H P

    1981-10-01

    As is evident in the history of civilization, in myths and dreams, and in Freud's self-analysis, insight has been both prohibited and heroically sought. Psychoanalytic insight into unconscious processes and contents involves a gradual transformation of inner interdictions and ideals through the tolerance of previously forbidden curiosity and knowledge. The analytic process depends upon relaxation of censorship and analysis of the motives and modes of self-criticism and self-punishment. While the superego may also uphold truth, the ideal of insight into psychic reality is relatively rare. The formation and consolidation of an analytic ideal of insight is an outgrowth of and contribution to analysis and analytic education. Analytic education should result in freedom from inner constraints on insight, in independent thought and judgement, and in a continuing "after-education."

  15. Resisting temptation: effects of exposure to a forbidden food on eating behaviour.

    Science.gov (United States)

    Soetens, Barbara; Braet, Caroline; Van Vlierberghe, Leen; Roets, Arne

    2008-07-01

    The study tests existing evidence on the paradoxical effects of exposure to a forbidden snack. Sixty-eight females were assigned randomly to one of two conditions: a temptation group, who were given the instruction to abstain from a favourite snack for 24h while being exposed to it, or a control group, who were given no specific instructions. A further distinction was made between high-restraint/high-disinhibition (n=21), high-restraint/low-disinhibition (n=20) and low-restraint participants (n=27) based on DEBQ subscale scores. After exposure to the foods, all participants were given free access to the food. Participants ate more of the snack after abstinence with exposure. The high-restraint/high-disinhibition group in particular displayed a substantial disinhibition effect. Results indicate that prohibition with exposure may backfire and increase the risk of loss of control over eating behaviour, particularly in at-risk groups of disinhibited restrained eaters.

  16. T-forbidden excitation of isobaric analogue states in the 37Cl(p, α0)34S reaction

    NARCIS (Netherlands)

    Bosnjakovic, B.; Leun, C. van der

    1966-01-01

    The analogues of the two lowest levels of 38Cl, with Jπ=3- and 5-, were excited in the T-forbidden reaction 37Cl(p, αo)34S. The Jπ=3- analogue state is split into several components which form a micro-giant resonance.

  17. Inhibition of pirfenidone on TGF-beta2 induced proliferation, migration and epithlial-mesenchymal transition of human lens epithelial cells line SRA01/04.

    Directory of Open Access Journals (Sweden)

    Yangfan Yang

    Full Text Available BACKGROUND: Posterior capsular opacification (PCO is a common complication of cataract surgery. Transforming growth factor-β2 (TGF-β2 plays important roles in the development of PCO. The existing pharmacological treatments are not satisfactory and can have toxic side effects. METHODOLOGIES/PRINCIPAL FINDINGS: We evaluated the effect of pirfenidone on proliferation, migration and epithlial-mesenchymal transition of human lens epithelial cell line SRA01/04 (HLECs in vitro. After treatment with 0, 0.25, and 0.5 mg/ml pirfenidone, cell proliferation was measured by MTT assay. Cell viability was determined by trypan blue exclusion assay and measurement of lactate dehydrogenase (LDH activity released from the damaged cells. And cell migration was measured by scratch assay in the absence or presence of transforming growth factor-β2 (TGF-β2. The expressions of TGF-β2 and SMADs were evaluated with real-time RT-PCR, western blot, and immunofluorescence analyses. The mesenchymal phenotypic marker fibronectin (FN was demonstrated by Immunocytofluorescence analyses. The cells had high viability, which did not vary across different concentrations of pirfenidone (0 [control] 0.3, 0.5 or 1.0 mg/ml after 24 hours. Pirfenidone (0∼0.5 mg/ml had no significant cytotoxicity effect on SRA01/04 by LDH assay. Pirfenidone significantly inhibited the proliferation and TGF-β2-induced cell migration and the effects were dose-dependent, and inhibited TGF-β2-induced fibroblastic phenotypes and TGF-β2-induced expression of FN in SRA01/04 cells. The cells showed dose-dependent decreases in mRNA and protein levels of TGF-β2 and SMADs. Pirfenidone also depressed the TGF-β2-induced expression of SMADs and blocked the nuclear translocation of SMADs in cells. CONCLUSION: Pirfenidone inhibits TGF-β2-induced proliferation, migration and epithlial-mesenchymal transition of human lens epithelial cells line SRA01/04 at nontoxic concentrations. This effect may be achieved by

  18. Oxygen isotope fractionation during spin-forbidden photolysis of CO2: Relevance to the atmosphere of Mars

    Science.gov (United States)

    Lyons, J. R.; Stark, G.; Pack, A.; de Oliveira, N.; Nahon, L.

    2015-12-01

    The oxygen isotope composition of the Martian atmosphere is of interest for comparison with recent MSL SAM results, and to understand the origin of oxygen isotope anomalies (i.e., mass-independent fractionation or MIF) in secondary minerals in SNC meteorites. Our focus here is on spin-forbidden photolysis of CO2, CO2 + hv (>167 nm) → CO(X1S) + O(3P). The spin-forbidden photolysis of CO2 is unusual in the Martian atmosphere because of its high reaction rate from the upper atmosphere (80 km) all the way to the ground. This range of altitudes spans 4 orders of magnitude in atmospheric pressure, and occurs because of the gradual decrease in the CO2 cross sections from 167 to ~200 nm. Previous laboratory photolysis experiments on CO2 in the spin-allowed and spin-forbidden regions have yielded a remarkably large MIF signature (17O excess ~ 100 permil) in O2 product for photolysis at 185 nm. Recent theoretical cross sections for CO2 isotopologues argue for a much smaller MIF signature from spin-forbidden photolysis. Here, we report the results of photolysis experiments on CO2 at the Soleil synchrotron DESIRS beamline. High purity, natural isotope abundance CO2 was placed in a 20 cm photocell with MgF2 windows. Experiments were performed at 3 wavelengths (7% FWHM): 160 nm (spin-allowed), and at 175 nm and 185 nm (spin-forbidden). After VUV exposure, aliquots of the photolyzed CO2 were sent to the Department of Isotope Geology at the University of Goettingen for O isotope analysis. The isotope results show that the spin-allowed photolysis yields normal, mass-dependent fractionation in agreement with earlier work. Photolysis at 175 nm, which is mostly spin-forbidden, yields a small positive (or zero) MIF signature. Photolysis at 185 nm, which is entirely spin-forbidden, yields O2 with a negative MIF signature (D17O ~ -8 to -10 permil). The results at 185 nm disagree in magnitude and sign with the very large positive MIF signature previously reported, and provides support

  19. Epithelial-mesenchymal transition involved in pulmonary fibrosis induced by multi-walled carbon nanotubes via TGF-beta/Smad signaling pathway.

    Science.gov (United States)

    Chen, Tian; Nie, Haiyu; Gao, Xin; Yang, Jinglin; Pu, Ji; Chen, Zhangjian; Cui, Xiaoxing; Wang, Yun; Wang, Haifang; Jia, Guang

    2014-04-21

    Multi-walled carbon nanotubes (MWCNT) are a typical nanomaterial with a wide spectrum of commercial applications. Inhalation exposure to MWCNT has been linked with lung fibrosis and mesothelioma-like lesions commonly seen with asbestos. In this study, we examined the pulmonary fibrosis response to different length of MWCNT including short MWCNT (S-MWCNT, length=350-700nm) and long MWCNT (L-MWCNT, length=5-15μm) and investigated whether the epithelial-mesenchymal transition (EMT) occurred during MWCNT-induced pulmonary fibrosis. C57Bl/6J male mice were intratracheally instilled with S-MWCNT or L-WCNT by a single dose of 60μg per mouse, and the progress of pulmonary fibrosis was evaluated at 7, 28 and 56 days post-exposure. The in vivo data showed that only L-MWCNT increased collagen deposition and pulmonary fibrosis significantly, and approximately 20% of pro-surfactant protein-C positive epithelial cells transdifferentiated to fibroblasts at 56 days, suggesting the occurrence of EMT. In order to understand the mechanism, we used human pulmonary epithelial cell line A549 to investigate the role of TGF-β/p-Smad2 signaling pathway in EMT. Our results showed that L-MWCNT downregulated E-cadherin and upregulated α-smooth muscle actin (α-SMA) protein expression in A549 cells. Taken together, both in vivo and in vitro study demonstrated that respiratory exposure to MWCNT induced length dependent pulmonary fibrosis and epithelial-derived fibroblasts via TGF-β/Smad pathway.

  20. Gufa, a unique cultural ritual--a tale of forbidden sun and a girl

    Science.gov (United States)

    Shrestha, Pritisha

    2015-08-01

    Gufa, one of the traditional rituals has been performed in Nepal since time immemorial by an especial indigenous Newar people. Gufa, in its literal translation means cave. Just like in the cave where darkness seeps deep within its wall as the sun’s ray cannot penetrate, in the ritual of Gufa, a young girl who just had her first period is hidden in a dark room for twelve consecutive days. The girl, by strict custom and ritual performance stays in the room, protected from the sun’s light. From her female elders, she also receives informal education on family and societal values and norms.Sun, the reason behind our existence, is forbidden for the girl to observe. This very aspect of purely shunning away from the sun has become the crucial aspect for delving into the explanations offered by cultural astronomy. The present paper would argue that astronomy and astronomy education should not only focus on looking into the future, but also should go back to the ancient civilization to comprehend ritual performance our forefathers had learned from gazing the sky.After twelve days, the girl is carefully brought out to an open space where she sees the forbidden sun and symbolically marries the star via ritual. The logic behind the union after a pure restriction is to protect her sensitive young body and to ward off any harm to her reproductive parts from the sun’s harsh rays.From astronomical point, this logic behind protecting the girl from the effects of then deemed harmful rays should be studied. In ancient times, who with which instruments could have possibly fathom the life-giving sun could harness harmful solar rays. Although it looks like a primitive custom of hiding the girl immediately during her first period, there are logical social, cultural and scientific reasons for doing it even today in modern, urban and among the educated Newar households of Nepal and abroad.The paper would expound the importance of traditional ritual performance and its nexus with

  1. Asymptotic Structure in the Classically Forbidden Region of the Hooke's Atoms

    Science.gov (United States)

    Wang, Xue-Mei

    2013-05-01

    The two-electron Hooke's atom — a quantum mechanical system with two electrons bound in a harmonic potential — is well known for its exact analytical properties at certain oscillator strengths. The Hooke's atoms with more than two electrons offer more scope for valuable practical applications. In this work, we study the asymptotic structure of these Hooke's atoms in the classically forbidden region. The leading-order term of the long-range expression for the KS exchange-correlation potential vxc(r) is shown to be -1/r. The second and third higher order terms are also exactly obtained. Various components of vxc(r) are also studied. It is shown that the leading term of O(1/r) in vxc(r) is due to the pure Pauli correlation, while the leading contribution of the Coulomb correlation is of O(1/r3). Neither of them makes contribution to the term of O(1/r2), which is shown to be solely due to the kinetic correlation effect. Results for the two-electron Hooke's atom were obtained before in the literature. Our results reduce to those of the two-electron Hooke's atom as a special case.

  2. Theoretical optimization of complete forbidden bands in woodpile-type photonic crystals

    Institute of Scientific and Technical Information of China (English)

    ZHAN Yi; ZHENG Yi; LI Xiu-Xia

    2008-01-01

    Based on the plane-wave method, the optical properties of complete forbidden bands of woodpile structure photonic crystal with an entire lattice rotation of 45°in the x-y plane were theoretically studied in terms ofheight-to-pitch ratios, filling factors, and rotation angles. The calculated results show that the gap to mid-gap ratio changes slightly with a filling fraction ranging from 0.25 to 0.30. The optimum height-to-pitch ratio is about 1.3. The gap to mid-gap ratio reaches more than 0.18 when the rotation angle increases from 40°to 50°and the maximum gap to mid-gap ratio of 0.2 remains unchanged for the rotation angle from 42°to 48°with a constant height-to-pitch ratio of 1.3. The gap to mid-gap ratio reaches the maximum value of 0.2 when the height-to-pitch ratio is 1.3. This woodpile-type photonic crystal can provide large band gaps within a wider parameter range, which makes it convenient to manufacture three-dimensional photonic crystals in the laboratory.

  3. On forbidden high-energy electrons as a source of background in X-ray and gamma-ray observations

    CERN Document Server

    Suvorova, Alla V

    2014-01-01

    The study is devoted to a problem of electron-induced contaminant to X-ray and gamma-ray astrophysical measurements on board low-orbiting satellites. We analyzed enhancements of electron fluxes in energy range 100 - 300 keV observed at equatorial and low latitudes by a fleet of NOAA/POES low-orbiting satellites over the time period from 2003 to 2005. It was found that 100-300 keV electron fluxes in the forbidden zone below the inner radiation belt enhanced by several orders of magnitude during geomagnetic storms and/or under strong compressions of the magnetosphere. The enhancements are related to high substorm activity and occurred at any local time. Intense fluxes of the energetic electrons in the forbidden zone can be considered as an essential contaminant to X-ray and gamma-ray measurements at low-latitude and low-altitude orbits.

  4. Beta Thalassemia (For Parents)

    Science.gov (United States)

    ... Kids to Be Smart About Social Media Beta Thalassemia KidsHealth > For Parents > Beta Thalassemia Print A A ... Complications Symptoms Diagnosis Treatment en español Beta talasemia Thalassemias Thalassemias are a group of blood disorders that ...

  5. Reinvestigation of the beta-decay of {sup 110}Mo

    Energy Technology Data Exchange (ETDEWEB)

    Wang, J.C.; Dendooven, P.; Hankonen, S.; Huikari, J.; Jokinen, A.; Kolhinen, V.S.; Lhersonneau, G.; Nieminen, A.; Peraejaervi, K.; Rinta-Antila, S.; Aeystoe, J. [Department of Physics, University of Jyvaeskylae, FIN-40351, Jyvaeskylae (Finland)

    2004-01-01

    The beta-decay of the neutron-rich nucleus {sup 110}Mo, separated by the IGISOL on-line mass separator from other fission products, has been investigated by using beta-gamma and gamma-gamma coincidence techniques. The decay scheme of {sup 110}Mo has been revised, including 3 new excited states and 7 new {gamma} transitions in {sup 110}Tc. The {beta}-feedings were measured and log ft values and B(GT) values were deduced based on a Q{sub {beta}}-value from systematics. Three excited 1{sup +} states in {sup 110}Tc fed by spin-flip allowed-unhindered beta transitions were identified. The deduced beta-decay strengths are compared with the Gamow-Teller strength distribution obtained from a macroscopic-microscopic calculation. The role of the asymptotic quantum numbers in the context of the allowed beta-decay is discussed. (orig.)

  6. Quantum-chemical studies of quasi-one-dimensional electron systems. Part 2. Cumulenes and origin of the forbidden zone

    Directory of Open Access Journals (Sweden)

    Yuriy Kruglyak

    2015-06-01

    Full Text Available This review is devoted to the basic problem in quantum theory of quasi-one-dimensional electron systems like polyenes (Part 1 and cumulenes (Part 2 – physical origin of the forbidden zone in these and analogous 1D electron systems due to two possible effects – Peierls instability (bond alternation and Mott instability (electron correlation. Both possible contradiction and coexistence of the Mott and Peierls instabilities are summerized on the basis of the Kiev quantum chemistry team research projects.

  7. Counting forbidden patterns in irregularly sampled time series. II. Reliability in the presence of highly irregular sampling

    Science.gov (United States)

    Sakellariou, Konstantinos; McCullough, Michael; Stemler, Thomas; Small, Michael

    2016-12-01

    We are motivated by real-world data that exhibit severe sampling irregularities such as geological or paleoclimate measurements. Counting forbidden patterns has been shown to be a powerful tool towards the detection of determinism in noisy time series. They constitute a set of ordinal symbolic patterns that cannot be realised in time series generated by deterministic systems. The reliability of the estimator of the relative count of forbidden patterns from irregularly sampled data has been explored in two recent studies. In this paper, we explore highly irregular sampling frequency schemes. Using numerically generated data, we examine the reliability of the estimator when the sampling period has been drawn from exponential, Pareto and Gamma distributions of varying skewness. Our investigations demonstrate that some statistical properties of the sampling distribution are useful heuristics for assessing the estimator's reliability. We find that sampling in the presence of large chronological gaps can still yield relatively accurate estimates as long as the time series contains sufficiently many densely sampled areas. Furthermore, we show that the reliability of the estimator of forbidden patterns is poor when there is a high number of sampling intervals, which are larger than a typical correlation time of the underlying system.

  8. Milk Intolerance, Beta-Casein and Lactose

    Directory of Open Access Journals (Sweden)

    Sebely Pal

    2015-08-01

    Full Text Available True lactose intolerance (symptoms stemming from lactose malabsorption is less common than is widely perceived, and should be viewed as just one potential cause of cows’ milk intolerance. There is increasing evidence that A1 beta-casein, a protein produced by a major proportion of European-origin cattle but not purebred Asian or African cattle, is also associated with cows’ milk intolerance. In humans, digestion of bovine A1 beta-casein, but not the alternative A2 beta-casein, releases beta-casomorphin-7, which activates μ-opioid receptors expressed throughout the gastrointestinal tract and body. Studies in rodents show that milk containing A1 beta-casein significantly increases gastrointestinal transit time, production of dipeptidyl peptidase-4 and the inflammatory marker myeloperoxidase compared with milk containing A2 beta-casein. Co-administration of the opioid receptor antagonist naloxone blocks the myeloperoxidase and gastrointestinal motility effects, indicating opioid signaling pathway involvement. In humans, a double-blind, randomized cross-over study showed that participants consuming A1 beta-casein type cows’ milk experienced statistically significantly higher Bristol stool values compared with those receiving A2 beta-casein milk. Additionally, a statistically significant positive association between abdominal pain and stool consistency was observed when participants consumed the A1 but not the A2 diet. Further studies of the role of A1 beta-casein in milk intolerance are needed.

  9. Milk Intolerance, Beta-Casein and Lactose.

    Science.gov (United States)

    Pal, Sebely; Woodford, Keith; Kukuljan, Sonja; Ho, Suleen

    2015-08-31

    True lactose intolerance (symptoms stemming from lactose malabsorption) is less common than is widely perceived, and should be viewed as just one potential cause of cows' milk intolerance. There is increasing evidence that A1 beta-casein, a protein produced by a major proportion of European-origin cattle but not purebred Asian or African cattle, is also associated with cows' milk intolerance. In humans, digestion of bovine A1 beta-casein, but not the alternative A2 beta-casein, releases beta-casomorphin-7, which activates μ-opioid receptors expressed throughout the gastrointestinal tract and body. Studies in rodents show that milk containing A1 beta-casein significantly increases gastrointestinal transit time, production of dipeptidyl peptidase-4 and the inflammatory marker myeloperoxidase compared with milk containing A2 beta-casein. Co-administration of the opioid receptor antagonist naloxone blocks the myeloperoxidase and gastrointestinal motility effects, indicating opioid signaling pathway involvement. In humans, a double-blind, randomized cross-over study showed that participants consuming A1 beta-casein type cows' milk experienced statistically significantly higher Bristol stool values compared with those receiving A2 beta-casein milk. Additionally, a statistically significant positive association between abdominal pain and stool consistency was observed when participants consumed the A1 but not the A2 diet. Further studies of the role of A1 beta-casein in milk intolerance are needed.

  10. $\\mu^+e^- <---> \\mu^- e^+$ Transitions via Neutral Scalar Bosons

    OpenAIRE

    Hou, Wei-Shu; Wong, Gwo-Guang

    1995-01-01

    With $\\mu\\to e\\gamma$ decay forbidden by multiplicative lepton number conservation, we study muonium--antimuonium transitions induced by neutral scalar bosons. Pseudoscalars do not induce conversion for triplet muonium, while for singlet muonium, pseudoscalar and scalar contributions add constructively. This is in contrast to the usual case of doubly charged scalar exchange, where the conversion rate is the same for both singlet and triplet muonium. Complementary to muonium conversion studies...

  11. The theory of beta-decay

    CERN Document Server

    Strachan, Charles

    1969-01-01

    The Theory of Beta-Decay covers the formulas, theories, probabilities, and spectra of beta-decay. This book is divided into 2 parts compassing 12 chapters, and starts with the introduction to the neutrino and the quantum theoretical background, explaining the basic phenomenon of beta-decay and the emission of electrons. The subsequent chapters deal with the interaction and the transition probability, as well as formulas of solutions. These topics are followed by discussions on the developments in the non-conservation of parity and helicity, the two-component theory of the neutrino, possible i

  12. In-trap decay spectroscopy for {beta}{beta} decays

    Energy Technology Data Exchange (ETDEWEB)

    Brunner, Thomas

    2011-01-18

    The presented work describes the implementation of a new technique to measure electron-capture (EC) branching ratios (BRs) of intermediate nuclei in {beta}{beta} decays. This technique has been developed at TRIUMF in Vancouver, Canada. It facilitates one of TRIUMF's Ion Traps for Atomic and Nuclear science (TITAN), the Electron Beam Ion Trap (EBIT) that is used as a spectroscopy Penning trap. Radioactive ions, produced at the radioactive isotope facility ISAC, are injected and stored in the spectroscopy Penning trap while their decays are observed. A key feature of this technique is the use of a strong magnetic field, required for trapping. It radially confines electrons from {beta} decays along the trap axis while X-rays, following an EC, are emitted isotropically. This provides spatial separation of X-ray and {beta} detection with almost no {beta}-induced background at the X-ray detector, allowing weak EC branches to be measured. Furthermore, the combination of several traps allows one to isobarically clean the sample prior to the in-trap decay spectroscopy measurement. This technique has been developed to measure ECBRs of transition nuclei in {beta}{beta} decays. Detailed knowledge of these electron capture branches is crucial for a better understanding of the underlying nuclear physics in {beta}{beta} decays. These branches are typically of the order of 10{sup -5} and therefore difficult to measure. Conventional measurements suffer from isobaric contamination and a dominating {beta} background at theX-ray detector. Additionally, X-rays are attenuated by the material where the radioactive sample is implanted. To overcome these limitations, the technique of in-trap decay spectroscopy has been developed. In this work, the EBIT was connected to the TITAN beam line and has been commissioned. Using the developed beam diagnostics, ions were injected into the Penning trap and systematic studies on injection and storage optimization were performed. Furthermore, Ge

  13. Forbidden Zones for Circular Regular Orbits of the Moons in Solar System, R3BP

    Indian Academy of Sciences (India)

    Sergey V. Ershkov;

    2017-03-01

    Previously, we have considered the equations of motion of the three-body problem in a Lagrange form (which means a consideration of relative motions of 3-bodies in regard to each other). Analysing such a system of equations, we considered the case of small-body motion of negligible mass m3 around the second of two giant-bodies $m_1$, $m_2$ (which are rotating around their common centre of masses on Kepler’s trajectories), the mass of which is assumed to be less than the mass of central body. In the current development, we have derived a key parameter $\\eta$ that determines the character of quasi-circular motion of the small third body $m_3$ relative to the second body $m_2$ (planet). Namely, by making several approximations in the equations of motion of the three-body problem, such the system could be reduced to the key governing Riccati-type ordinary differential equations. Under assumptions of R3BP (restricted three-body problem), we additionally note that Riccati-type ODEs above should have the invariant form if the key governing (dimensionless) parameter $\\eta$ remains in the range $10^{−2}$ ∻ $10^{−3}$. Such an amazing fact let us evaluate the forbidden zones for Moon’s orbits in the inner solar system or the zones of distances (between Moon and Planet) for which the motion of small body could be predicted to be unstable according to basic features of the solutions of Riccati-type.

  14. Beta decay and other processes in strong electromagnetic fields

    CERN Document Server

    Akhmedov, Evgeny

    2011-01-01

    We consider effects of the fields of strong electromagnetic waves on various characteristics of quantum processes. After a qualitative discussion of the effects of external fields on the energy spectra and angular distributions of the final-state particles as well as on the total probabilities of the processes (such as decay rates and total cross sections), we present a simple method of calculating the total probabilities of processes with production of non-relativistic charged particles. Using nuclear beta-decay as an example, we study the weak and strong field limits, as well as the field-induced beta-decay of nuclei stable in the absence of the external fields, both in the tunneling and multi-photon regimes. We also consider the possibility of accelerating forbidden nuclear beta-decays by lifting the forbiddeness due to the interaction of the parent or daughter nuclei with the field of a strong electromagnetic wave. It is shown that for currently attainable electromagnetic fields all effects on total beta-...

  15. Beta-spectroscopy of long lived nuclides with a PIPS detector-setup

    Directory of Open Access Journals (Sweden)

    Domula Alexander R.

    2017-01-01

    Full Text Available Several applications in modern nuclear physics, research and engineering are limited by a lack of precise knowledge in spectral shape data for beta-decays. Specifically the interest aims to study spectral data for forbidden decays with respectively long half-lives, which is one of the central activities of our group. For the investigation of those rare beta-decays the group operates a setup of six PIPS detectors in a vacuum chamber built out of low-radioactivity materials. In the long term the setup will be used as low-background-detector for the investigation of rare beta-decays. In order to reduce the measuring-background a muon veto was installed. The characterization of the setup in the energy-range from 20..1000 keV using conversion-electrons is described. A set of useful calibration-nuclides was established to determine energy calibration and efficiencies.

  16. Beta-spectroscopy of long lived nuclides with a PIPS detector-setup

    Science.gov (United States)

    Domula, Alexander R.; Thurn, Jan; Zuber, Kai

    2017-09-01

    Several applications in modern nuclear physics, research and engineering are limited by a lack of precise knowledge in spectral shape data for beta-decays. Specifically the interest aims to study spectral data for forbidden decays with respectively long half-lives, which is one of the central activities of our group. For the investigation of those rare beta-decays the group operates a setup of six PIPS detectors in a vacuum chamber built out of low-radioactivity materials. In the long term the setup will be used as low-background-detector for the investigation of rare beta-decays. In order to reduce the measuring-background a muon veto was installed. The characterization of the setup in the energy-range from 20..1000 keV using conversion-electrons is described. A set of useful calibration-nuclides was established to determine energy calibration and efficiencies.

  17. Nuclear structure of tellurium 133 via beta decay and shell model calculations in the doubly magic tin 132 region. [J,. pi. , transition probabilities, neutron and proton separation, g factors

    Energy Technology Data Exchange (ETDEWEB)

    Lane, S.M.

    1979-08-01

    An experimental investigation of the level structure of /sup 133/Te was performed by spectroscopy of gamma-rays following the beta-decay of 2.7 min /sup 133/Sb. Multiscaled gamma-ray singles spectra and 2.5 x 10/sup 7/ gamma-gamma coincidence events were used in the assignment of 105 of the approximately 400 observed gamma-rays to /sup 133/Sb decay and in the construction of the /sup 133/Te level scheme with 29 excited levels. One hundred twenty-two gamma-rays were identified as originating in the decay of other isotopes of Sb or their daughter products. The remaining gamma-rays were associated with the decay of impurity atoms or have as yet not been identified. A new computer program based on the Lanczos tridiagonalization algorithm using an uncoupled m-scheme basis and vector manipulations was written. It was used to calculate energy levels, parities, spins, model wavefunctions, neutron and proton separation energies, and some electromagnetic transition probabilities for the following nuclei in the /sup 132/Sn region: /sup 128/Sn, /sup 129/Sn, /sup 130/Sn, /sup 131/Sn, /sup 130/Sb, /sup 131/Sb, /sup 132/Sb, /sup 133/Sb, /sup 132/Te, /sup 133/Te, /sup 134/Te, /sup 134/I, /sup 135/I, /sup 135/Xe, and /sup 136/Xe. The results are compared with experiment and the agreement is generally good. For non-magic nuclei: the lg/sub 7/2/, 2d/sub 5/2/, 2d/sub 3/2/, 1h/sub 11/2/, and 3s/sub 1/2/ orbitals are available to valence protons and the 2d/sub 5/2/, 2d/sub 3/2/, 1h/sub 11/2/, and 3s/sub 1/2/ orbitals are available to valence neutron holes. The present CDC7600 computer code can accommodate 59 single particle states and vectors comprised of 30,000 Slater determinants. The effective interaction used was that of Petrovich, McManus, and Madsen, a modification of the Kallio-Kolltveit realistic force. Single particle energies, effective charges and effective g-factors were determined from experimental data for nuclei in the /sup 132/Sn region. 116 references.

  18. Response gene to complement-32 enhances metastatic phenotype by mediating transforming growth factor beta-induced epithelial-mesenchymal transition in human pancreatic cancer cell line BxPC-3

    Directory of Open Access Journals (Sweden)

    Zhu Liang

    2012-03-01

    Full Text Available Abstract Background Response gene to complement-32 (RGC-32 is comprehensively expressed in many kinds of tissues and has been reported to be expressed abnormally in different kinds of human tumors. However, the role of RGC-32 in cancer remains controversial and no reports have described the effect of RGC-32 in pancreatic cancer. The present study investigated the expression of RGC-32 in pancreatic cancer tissues and explored the role of RGC-32 in transforming growth factor-beta (TGF-β-induced epithelial-mesenchymal transition (EMT in human pancreatic cancer cell line BxPC-3. Methods Immunohistochemical staining of RGC-32 and E-cadherin was performed on specimens from 42 patients with pancreatic cancer, 12 with chronic pancreatitis and 8 with normal pancreas. To evaluate the role of RGC-32 in TGF-β-induced EMT in pancreatic cancer cells, BxPC-3 cells were treated with TGF-β1, and RGC-32 siRNA silencing and gene overexpression were performed as well. The mRNA expression and protein expression of RGC-32 and EMT markers such E-cadherin and vimentin were determined by quantitative reverse transcription-PCR (qRT-PCR and western blot respectively. Finally, migration ability of BxPC-3 cells treated with TGF-β and RGC-32 siRNA transfection was examined by transwell cell migration assay. Results We found stronger expression of RGC-32 and higher abnormal expression rate of E-cadherin in pancreatic cancer tissues than those in chronic pancreatitis tissues and normal pancreatic tissues. Immunohistochemical analysis revealed that both RGC-32 positive expression and E-cadherin abnormal expression in pancreatic cancer were correlated with lymph node metastasis and TNM staging. In addition, a significant and positive correlation was found between positive expression of RGC-32 and abnormal expression of E-cadherin. Furthermore, in vitro, we found sustained TGF-β stimuli induced EMT and up-regulated RGC-32 expression in BxPC-3 cells. By means of si

  19. Superradiance on the mHz linewidth clock transition in 87Sr

    Science.gov (United States)

    Norcia, Matthew; Winchester, Matthew; Cline, Julia; Thompson, James

    2016-05-01

    In this talk, I will discuss our recent experimental explorations of superradiant emission from the mHz linewidth clock transition in an ensemble of cold 87 Sr atoms confined within a high-finesse optical cavity. Recent proposals suggest that superradiant lasers based on such dipole-forbidden transitions in alkaline earth atoms could achieve linewidths below the current state of the art, with reduced sensitivity to environmental perturbations.

  20. Exact electronic properties in the classically forbidden region of a metal surface

    Science.gov (United States)

    Qian, Zhixin; Sahni, Viraht

    We derive exact properties of the inhomogeneous electron gas in the asymptotic classically forbidden region at a metal-vacuum interface within the framework of local effective potential energy theory. We derive a new expression for the asymptotic structure of the Kohn-Sham density functional theory (KS-DFT) exchange-correlation potential energy vxc(r) in terms of the irreducible electron self-energy. We also derive the exact asymptotic structure of the orbitals, density, the Dirac density matrix, the kinetic energy density, and KS exchange energy density. We further obtain the exact expression for the Fermi hole and demonstrate its structure in this asymptotic limit. The exchange-correlation potential energy is derived to be vxc(z → ∞) = -αKS,xc/z, and its exchange and correlation components to be vx(z → ∞) = -αKS,x/z and vc(z → ∞) = -αKS,c/z, respectively. The analytical expressions for the coefficients αKS,xc and αKS,x show them to be dependent on the bulk-metal Wigner-Seitz radius and the barrier height at the surface. The coefficient αKS,c = 1/4 is determined in the plasmon-pole approximation and is independent of these metal parameters. Thus, the asymptotic structure of vxc(z) in the vacuum region is image-potential-like but not the commonly accepted one of -1/4z. Furthermore, this structure depends on the properties of the metal. Additionally, an analysis of these results via quantal density functional theory (Q-DFT) shows that both the Pauli Wx(z → ∞) and lowest-order correlation-kinetic W (1)t c(z → ∞) components of the exchange potential energy vx(z → ∞), and the Coulomb Wc(z → ∞) and higher-order correlation-kinetic components of the correlation potential energy vc(z → ∞), all contribute terms of O(1/z) to the structure. Hence correlations attributable to the Pauli exclusion principle, Coulomb repulsion, and correlation-kinetic effects all contribute to the asymptotic structure of the effective potential energy at a

  1. Satellites of Xe transitions induced by infrared active vibrational modes of CF4 and C2F6 molecules.

    Science.gov (United States)

    Alekseev, Vadim A; Schwentner, Nikolaus

    2011-07-28

    Absorption and luminescence excitation spectra of Xe/CF(4) mixtures were studied in the vacuum UV region at high resolution using tunable synchrotron radiation. Pressure-broadened resonance bands and bands associated with dipole-forbidden states of the Xe atom due to collision-induced breakdown of the optical selection rules are reported. The spectra display in addition numerous satellite bands corresponding to transitions to vibrationally excited states of a Xe-CF(4) collisional complex. These satellites are located at energies of Xe atom transition increased by one quantum energy in the IR active v(3) vibrational mode of CF(4) (v(3) = 1281 cm(-1)). Satellites of both resonance and dipole-forbidden transitions were observed. Satellites of low lying resonance states are spectrally broad bands closely resembling in shape their parent pressure-broadened resonance bands. In contrast, satellites of dipole-forbidden states and of high lying resonance states are spectrally narrow bands (FWHM ∼10 cm(-1)). The satellites of dipole-forbidden states are orders of magnitude stronger than transitions to their parent states due to collision-induced breakdown of the optical selection rules. These satellites are attributed to a coupling of dipole-forbidden and resonance states induced by the electric field of the transient CF(4) (v(3) = 0 ↔ v(3) = 1) dipole. Similar satellites are present in spectra of Xe/C(2)F(6) mixtures where these bands are induced by the IR active v(10) mode of C(2)F(6). Transitions to vibrationally excited states of Xe-CF(4)(C(2)F(6)) collision pairs were also observed in two-photon LIF spectra.

  2. Beta-carotene

    Science.gov (United States)

    ... patches on the tongue and mouth called oral leukoplakia. Taking beta-carotene by mouth for up to 12 months seems to decrease symptoms of oral leukoplakia. Osteoarthritis. Beta-carotene taken by mouth may prevent ...

  3. Energetic, Structural, and Antimicrobial Analyses of [beta]-Lactam Side Chain Recognition by [beta]-Lactamases

    Energy Technology Data Exchange (ETDEWEB)

    Caselli, E.; Powers, R.A.; Blaszczak, L.C.; Wu, C.Y.E.; Prati, F.; Shoichet, B.K. (NWU)

    2010-03-05

    Penicillins and cephalosporins are among the most widely used and successful antibiotics. The emergence of resistance to these {beta}-lactams, most often through bacterial expression of {beta}-lactamases, threatens public health. To understand how {beta}-lactamases recognize their substrates, it would be helpful to know their binding energies. Unfortunately, these have been difficult to measure because {beta}-lactams form covalent adducts with {beta}-lactamases. This has complicated functional analyses and inhibitor design. To investigate the contribution to interaction energy of the key amide (R1) side chain of {beta}-lactam antibiotics, eight acylglycineboronic acids that bear the side chains of characteristic penicillins and cephalosporins, as well as four other analogs, were synthesized. These transition-state analogs form reversible adducts with serine {beta}-lactamases. Therefore, binding energies can be calculated directly from K{sub i} values. The K{sub i} values measured span four orders of magnitude against the Group I {beta}-lactamase AmpC and three orders of magnitude against the Group II {beta}-lactamase TEM-1. The acylglycineboronic acids have K{sub i} values as low as 20 nM against AmpC and as low as 390 nM against TEM-1. The inhibitors showed little activity against serine proteases, such as chymotrypsin. R1 side chains characteristic of {beta}-lactam inhibitors did not have better affinity for AmpC than did side chains characteristic of {beta}-lactam substrates. Two of the inhibitors reversed the resistance of pathogenic bacteria to {beta}-lactams in cell culture. Structures of two inhibitors in their complexes with AmpC were determined by X-ray crystallography to 1.90 {angstrom} and 1.75 {angstrom} resolution; these structures suggest interactions that are important to the affinity of the inhibitors. Acylglycineboronic acids allow us to begin to dissect interaction energies between {beta}-lactam side chains and {beta}-lactamases. Surprisingly

  4. Optical Dark-Field and Electron Energy Loss Imaging and Spectroscopy of Symmetry-Forbidden Modes in Loaded Nanogap Antennas.

    Science.gov (United States)

    Brintlinger, Todd; Herzing, Andrew A; Long, James P; Vurgaftman, Igor; Stroud, Rhonda; Simpkins, B S

    2015-06-23

    We have produced large numbers of hybrid metal-semiconductor nanogap antennas using a scalable electrochemical approach and systematically characterized the spectral and spatial character of their plasmonic modes with optical dark-field scattering, electron energy loss spectroscopy with principal component analysis, and full wave simulations. The coordination of these techniques reveal that these nanostructures support degenerate transverse modes which split due to substrate interactions, a longitudinal mode which scales with antenna length, and a symmetry-forbidden gap-localized transverse mode. This gap-localized transverse mode arises from mode splitting of transverse resonances supported on both antenna arms and is confined to the gap load enabling (i) delivery of substantial energy to the gap material and (ii) the possibility of tuning the antenna resonance via active modulation of the gap material's optical properties. The resonant position of this symmetry-forbidden mode is sensitive to gap size, dielectric strength of the gap material, and is highly suppressed in air-gapped structures which may explain its absence from the literature to date. Understanding the complex modal structure supported on hybrid nanosystems is necessary to enable the multifunctional components many seek.

  5. gA-driven shapes of electron spectra of forbidden β decays in the nuclear shell model

    Science.gov (United States)

    Kostensalo, Joel; Suhonen, Jouni

    2017-08-01

    The evolution of the shape of the electron spectra of 16 forbidden β- decays as a function of gA was studied using the nuclear shell model in appropriate single-particle model spaces with established, well-tested nuclear Hamiltonians. The β spectra of 94Nb(6+) →94Mo(4+) and 98Tc(6+) →98Ru(4+) were found to depend strongly on gA, which makes them excellent candidates for the determination of the effective value of gA with the spectrum-shape method (SSM). A strong gA dependence is also seen in the spectrum of 96Zr(0+) →96Nb(6+) . This decay could be used for determining the quenching of gA in sixth-forbidden decays in the future, when the measurement of the spectrum becomes experimentally feasible. The calculated shell-model electron spectra of the ground-state-to-ground-state decays of 87Rb, 99Tc, and 137Cs and the decay of 137Cs to the isomeric 11 /2- state in 137Ba were found to be in excellent agreement with the spectra previously calculated using the microscopic quasiparticle-phonon model. This is further evidence of the robust nature of the SSM observed in the previous studies.

  6. Betting Against Beta

    DEFF Research Database (Denmark)

    Frazzini, Andrea; Heje Pedersen, Lasse

    .S. equities, 20 international equity markets, Treasury bonds, corporate bonds, and futures; (2) A betting-against-beta (BAB) factor, which is long leveraged low beta assets and short high-beta assets, produces significant positive risk-adjusted returns; (3) When funding constraints tighten, the return...

  7. Phase transitions and topology in 2+k XY mean-field models.

    Science.gov (United States)

    Angelani, L; Ruocco, G

    2007-11-01

    The thermodynamics and topology of mean-field models with 2+k body interaction terms (generalizing XY model) are derived. Focusing on two particular cases (2+4 and 2+6 body interaction terms), a comparison between thermodynamic (phase transition energy, thermodynamically forbidden energy regions) and topological (singularity and curvature of saddle entropy) properties is performed. We find that (i) a topological change is present at the phase transition energy; however, (ii) only one topological change occurs, also for those models exhibiting two phase transitions; (iii) the order of a phase transition is not completely signaled by the curvature of topological quantities.

  8. Forward-Looking Betas

    DEFF Research Database (Denmark)

    Christoffersen, Peter; Jacobs, Kris; Vainberg, Gregory

    Few issues are more important for finance practice than the computation of market betas. Existing approaches compute market betas using historical data. While these approaches differ in terms of statistical sophistication and the modeling of the time-variation in the betas, they are all backward......-looking. This paper introduces a radically different approach to estimating market betas. Using the tools in Bakshi and Madan (2000) and Bakshi, Kapadia and Madan (2003) we employ the information embedded in the prices of individual stock options and index options to compute our forward-looking market beta...

  9. Control of atomic transition rates via laser light shaping

    CERN Document Server

    Jauregui, R

    2015-01-01

    A modular systematic analysis of the feasibility of modifying atomic transition rates by tailoring the electromagnetic field of an external coherent light source is presented. The formalism considers both the center of mass and internal degrees of freedom of the atom, and all properties of the field: frequency, angular spectrum, and polarization. General features of recoil effects for internal forbidden transitions are discussed. A comparative analysis of different structured light sources is explicitly worked out. It includes spherical waves, Gaussian beams, Laguerre-Gaussian beams, and propagation invariant beams with closed analytical expressions. It is shown that increments in the order of magnitude of the transition rates for Gaussian and Laguerre-Gaussian beams, with respect to those obtained in the paraxial limit, requires waists of the order of the wavelength, while propagation invariant modes may considerably enhance transition rates under more favorable conditions. For transitions that can be natura...

  10. Les dépenses interdites des collectivités locales The Forbidden Expenses of Local Entities

    Directory of Open Access Journals (Sweden)

    Jean-François Boudet

    2009-09-01

    Full Text Available Les différentes réformes dites de « décentralisation » entreprises en France notamment depuis 1982 laisseraient entendre que les collectivités locales ont toute latitude dans la gestion de leurs compétences et de leurs finances. Il n’en rien, car, au-delà de dépenses obligatoires, les collectivités locales se voient interdire certaines dépenses. Le caractère unitaire de l’Etat expliquerait cette interdiction.In France, since 1982, the so-called “decentralisation” reforms would imply that local governments are independent with regard to the management of their resources and budget. This is not the case: aside from mandatory expenses, a few expenditures are forbidden to local governments. The unitary character of the State would explain this interdiction.

  11. A New Model for the Error Detection Delay of Finite Precision Binary Arithmetic Codes with a Forbidden Symbol

    Science.gov (United States)

    Pang, Yuye; Sun, Jun; Wang, Jia; Wang, Peng

    In this paper, the statistical characteristic of the Error Detection Delay (EDD) of Finite Precision Binary Arithmetic Codes (FPBAC) is discussed. It is observed that, apart from the probability of the Forbidden Symbol (FS) inserted into the list of the source symbols, the probability of the source sequence and the operation precision as well as the position of the FS in the coding interval can affect the statistical characteristic of the EDD. Experiments demonstrate that the actual distribution of the EDD of FPBAC is quite different from the geometric distribution of infinite precision arithmetic codes. This phenomenon is researched deeply, and a new statistical model (gamma distribution) of the actual distribution of the EDD is proposed, which can make a more precise prediction of the EDD. Finally, the relation expressions between the parameters of gamma distribution and the related factors affecting the distribution are given.

  12. The cultural significance of"The Starbucks in the Forbidden City"%故宫“星巴克”的文化意义

    Institute of Scientific and Technical Information of China (English)

    罗筱华

    2012-01-01

      The reason why the Starbucks mustn’t open in the Forbidden City lies in that the Starbucks spoils the integrity of the Forbidden City;Starbucks destroyed the palace as a museum output cultural image of the original, the harmonious sex and integrity;Starbucks and the Forbidden City aren’t fit for the function of service facilities. The cultural significance of"The Starbucks in the Forbidden City"highlights the conflicts between Chinese and foreign cultures, commerce development and traditional cultures.%  故宫内不可以开设星巴克,在于它破坏了故宫作为文化遗产的整体性;星巴克破坏了故宫作为博物馆所输出文化形象的原生性、和谐性和整体性;星巴克与故宫所需要的服务设施功能不符。故宫内的星巴克的文化意义,在于中外文化交流时引起的冲突以及当下商业对传统文化的冲击。

  13. Forward-Looking Betas

    DEFF Research Database (Denmark)

    Christoffersen, Peter; Jacobs, Kris; Vainberg, Gregory

    -looking. This paper introduces a radically different approach to estimating market betas. Using the tools in Bakshi and Madan (2000) and Bakshi, Kapadia and Madan (2003) we employ the information embedded in the prices of individual stock options and index options to compute our forward-looking market beta......Few issues are more important for finance practice than the computation of market betas. Existing approaches compute market betas using historical data. While these approaches differ in terms of statistical sophistication and the modeling of the time-variation in the betas, they are all backward...... at the daily frequency. This beta can be computed using option data for a single day, and is able to reflect sudden changes in the structure of the underlying company. Based on an empirical investigation of daily cross-sections of option contracts on thirty underlying companies, we conclude that these forward...

  14. Betting against Beta

    DEFF Research Database (Denmark)

    Frazzini, Andrea; Heje Pedersen, Lasse

    2014-01-01

    We present a model with leverage and margin constraints that vary across investors and time. We find evidence consistent with each of the model's five central predictions: (1) Because constrained investors bid up high-beta assets, high beta is associated with low alpha, as we find empirically for......, the return of the BAB factor is low. (4) Increased funding liquidity risk compresses betas toward one. (5) More constrained investors hold riskier assets....... for US equities, 20 international equity markets, Treasury bonds, corporate bonds, and futures. (2) A betting against beta (BAB) factor, which is long leveraged low-beta assets and short high-beta assets, produces significant positive risk-adjusted returns. (3) When funding constraints tighten...

  15. Betting Against Beta

    DEFF Research Database (Denmark)

    Frazzini, Andrea; Heje Pedersen, Lasse

    We present a model with leverage and margin constraints that vary across investors and time. We find evidence consistent with each of the model’s five central predictions: (1) Since constrained investors bid up high-beta assets, high beta is associated with low alpha, as we find empirically for U...... of the BAB factor is low; (4) Increased funding liquidity risk compresses betas toward one; (5) More constrained investors hold riskier assets........S. equities, 20 international equity markets, Treasury bonds, corporate bonds, and futures; (2) A betting-against-beta (BAB) factor, which is long leveraged low beta assets and short high-beta assets, produces significant positive risk-adjusted returns; (3) When funding constraints tighten, the return...

  16. Electric Monopole Transition Strengths in 62Ni

    Science.gov (United States)

    Evitts, L. J.; Garnsworthy, A. B.; Kibédi, T.; Moukaddam, M.; Alshahrani, B.; Eriksen, T. K.; Holt, J. D.; Hota, S. S.; Lane, G. J.; Lee, B. Q.; McCormick, B. P.; Palalani, N.; Reed, M. W.; Stroberg, S. R.; Stuchbery, A. E.

    2016-09-01

    Excited states in 62Ni were populated with a (p, p') reaction using the 14UD Pelletron accelerator at the Australian National University. Electric monopole transition strengths, ρ2(E0), were measured through simultaneous detection of the internal conversion electrons and γ rays emitted from the de-excitation of populated states, using the Super-e spectrometer coupled with a germanium detector. The strength of the 02+ to 01+ transition has been measured to be 77-34+23 × 10-3 and agrees with previously reported values. Upper limits have been placed on the 03+ to 01+ and 03+ to 02+ transitions. The measured ρ2(E0) value of the 22+ to 21+ transition in 62Ni has been measured for the first time and found to be one of the largest ρ2(E0) values measured to date in nuclei heavier than Ca. The low-lying states of 62Ni have previously been classified as one- and two-phonon vibrational states based on level energies. The measured electric quadrupole transition strengths are consistent with this interpretation. However as electric monopole transitions are forbidden between states which differ by one phonon number, the simple harmonic quadrupole vibrational picture is not suffcient to explain the large ρ2(E0) value for the 22+ to 21+ transition.

  17. Electric Monopole Transition Strengths in 62Ni

    Directory of Open Access Journals (Sweden)

    Evitts L. J.

    2016-01-01

    Full Text Available Excited states in 62Ni were populated with a (p, p’ reaction using the 14UD Pelletron accelerator at the Australian National University. Electric monopole transition strengths, ρ2(E0, were measured through simultaneous detection of the internal conversion electrons and γ rays emitted from the de-excitation of populated states, using the Super-e spectrometer coupled with a germanium detector. The strength of the 02+ to 01+ transition has been measured to be 77−34+23 × 10−3 and agrees with previously reported values. Upper limits have been placed on the 03+ to 01+ and 03+ to 02+ transitions. The measured ρ2(E0 value of the 22+ to 21+ transition in 62Ni has been measured for the first time and found to be one of the largest ρ2(E0 values measured to date in nuclei heavier than Ca. The low-lying states of 62Ni have previously been classified as one- and two-phonon vibrational states based on level energies. The measured electric quadrupole transition strengths are consistent with this interpretation. However as electric monopole transitions are forbidden between states which differ by one phonon number, the simple harmonic quadrupole vibrational picture is not suffcient to explain the large ρ2(E0 value for the 22+ to 21+ transition.

  18. Imperfect World of $\\beta\\beta$-decay Nuclear Data Sets

    CERN Document Server

    Pritychenko, B

    2015-01-01

    The precision of double-beta ($\\beta\\beta$) decay experimental half lives and their uncertainties is reanalyzed. The method of Benford's distributions has been applied to nuclear reaction, structure and decay data sets. First-digit distribution trend for $\\beta\\beta$-decay T$_{1/2}^{2\

  19. Non-Pauli transitions from spacetime noncommutativity.

    Science.gov (United States)

    Balachandran, A P; Joseph, Anosh; Padmanabhan, Pramod

    2010-07-30

    The consideration of noncommutative spacetimes in quantum theory can be plausibly advocated from physics at the Planck scale. Typically, this noncommutativity is controlled by fixed "vectors" or "tensors" with numerical entries like θμν for the Moyal spacetime. In approaches enforcing Poincaré invariance, these deform or twist the method of (anti)symmetrization of identical particle state vectors. We argue that the Earth's rotation and movements in the cosmos are "sudden" events to Pauli-forbidden processes. This induces (twisted) bosonic components in state vectors of identical spinorial particles. These components induce non-Pauli transitions. From known limits on such transitions, we infer that the energy scale for noncommutativity is ≳10(24)  TeV. This suggests a new energy scale beyond the Planck scale.

  20. Electric field allowed molecular transitions for one and two photon excitation microscopy.

    Science.gov (United States)

    Mondal, Partha Pratim; Diaspro, Alberto

    2008-07-01

    We propose an excitation technique for observing single and two photon excitation in those molecules for which such transitions are forbidden by the selection rules. This is possible by the application of an external electric field that perturbs the molecular orbitals, thereby resulting in a significant shift of energy levels. Such a shift of energy levels may bring those levels in resonance with the radiation field which is normally forbidden by selection rules. Further, parity of the these states may significantly improve the emission process. The external electric field results in the mixing of excited (short lifetime) and metastable states (long lifetime), thus reducing the lifetime of metastable (or near metastable) states. This may provide an effective channel for allowing transition from the metastable states. An application of electric field may result in the excitation of poorly excitable biomolecules. This excitation technique may find applications in single- and multi-photon fluorescence microscopy, bioimaging and optical devices.

  1. Measurement of 2 characteristics of metastable helium important for laser cooling: loss rates due to collisions in presence of quasi-resonant laser radiation and transition rates for 2 forbidden transitions: 2{sup 3}P{sub 1} {yields} 1{sup 1}S{sub 0} and 2{sup 3}P{sub 2} {yields} 1{sup 1}S{sub 0}; Mesure de deux caracteristiques de l'helium metastable importantes pour le refroidissement radiatif: taux de pertes par collisions en presence de lumiere quasi-resonante et taux de transition des raies interdites 2{sup 3}P{sub 1} {yields} 1{sup 1}S{sub 0} et 2{sup 3}P{sub 2} {yields} 1{sup 1}S{sub 0}

    Energy Technology Data Exchange (ETDEWEB)

    Poupard, J

    2000-11-15

    This thesis presents the study of 2 characteristics of metastable helium that are important for laser cooling. First, we measure two-body losses in a magneto-optical trap. The losses, enhanced by nearly resonant laser radiation, are mainly due to ionizing collisions. We measure the loss rate by observing the decay of the number of trapped atoms using either atomic fluorescence or ion production. We study the loss rate as a function of the trapping laser parameters. The second part of the thesis concerns experiments to measure the transition rates of the intercombination lines: 2{sup 3}P{sub 1} to 1{sup 1}S{sub 0} and 2{sup 3}P{sub 2} to 1{sup 1}S{sub 0}. The first of these rates is measured by exciting a small fraction of the atoms in a magneto-optical trap to the 2{sup 3}P{sub 1} state and observing the decrease in the trap lifetime. We then measure the ratio of the transition rates for 2{sup 3}P{sub 1} and 2{sup 3}P{sub 2} towards the 1{sup 1}S{sub 0} ground state by monitoring the flux of UV photons associated with the transition. (author)

  2. Acetylcholinesterase, a senile plaque component, affects the fibrillogenesis of amyloid-beta-peptides.

    Science.gov (United States)

    Alvarez, A; Bronfman, F; Pérez, C A; Vicente, M; Garrido, J; Inestrosa, N C

    1995-12-01

    Acetylcholinesterase (AChE) colocalizes with amyloid-beta peptide (A beta) deposits present in the brain of Alzheimer's patients. Recent studies showed that A beta 1-40 can adopt two different conformational states in solution (an amyloidogenic conformer, A beta ac, and a non-amyloidogenic conformer, A beta nac) which have distinct abilities to form amyloid fibrils. We report here that AChE binds A beta nac and accelerates amyloid formation by the same peptide. No such effect was observed with A beta ac, the amyloidogenic conformer, suggesting that AChE acts as a 'pathological chaperone' inducing a conformational transition from A beta nac into A beta ac in vitro.

  3. 1 and 2 transitions in the ground-state configuration of atomic manganese

    Indian Academy of Sciences (India)

    S Kabakçi; B Karaçoban Usta; L Özdemir

    2015-10-01

    Using the multiconfiguration Hartree–Fock approximation within the framework of the Breit–Pauli Hamiltonian (MCHF+BP) and the relativistic Hartree–Fock (HFR) approximation, we have calculated the forbidden transition (1 and 2) parameters such as transition energies, logarithmic weighted oscillator strengths and transition probabilities between the fine-structure levels in the ground-state configuration of 3d5 4s2 for atomic manganese (Mn I, Z =25). A discussion of these calculations for manganese using MCHF+BP and HFR methods is given here.

  4. Control of Optical Transitions with Magnetic Fields in Weakly Bound Molecules

    CERN Document Server

    McGuyer, B H; Iwata, G Z; Skomorowski, W; Moszynski, R; Zelevinsky, T

    2015-01-01

    Forbidden optical transitions in weakly bound $^{88}$Sr$_2$ molecules become strongly enabled with moderate applied magnetic fields. We report the control of transition strengths by five orders of magnitude and measurements of highly nonlinear Zeeman shifts, which we explain with an accurate {\\it ab initio} model. Mixed quantization in an optical lattice enables the experimental procedure. Our observation of formerly inaccessible $f$-parity excited states offers a new avenue for improving theoretical models for divalent atom dimers. Furthermore, magnetically enabled transitions may lead to an extremely precise subradiant molecular lattice clock.

  5. Study of coupled-cluster correlations on electromagnetic transitions and hyperfine structure constants of W VI

    CERN Document Server

    Bhowmik, Anal; Roy, Sourav; Majumder, Sonjoy

    2016-01-01

    This work presents precise calculations of important electromagnetic transition amplitudes along with detail of their many-body correlations using relativistic coupled cluster method. Studies of hyperfine interaction constants, useful for plasma diagnostic, with this correlation exhaustive many-body approach are another important area of this work. The calculated oscillator strengths of allowed transitions, amplitudes of forbidden transitions and lifetimes are compared with the other theoretical results wherever available and they show a good agreement. Hyperfine constants of ?different isotopes of W VI, presented in this paper will be helpful to get accurate picture of abundances of this element in different astronomical bodies.

  6. Negative Beta Encoder

    CERN Document Server

    Kohda, Tohru; Aihara, Kazuyuki

    2008-01-01

    A new class of analog-digital (A/D), digital-analog (D/A) converters as an alternative to conventional ones, called $\\beta$-encoder, has been shown to have exponential accuracy in the bit rates while possessing self-correction property for fluctuations of amplifier factor $\\beta$ and quantizer threshold $\

  7. Double beta decay experiments

    CERN Document Server

    Barabash, A S

    2011-01-01

    The present status of double beta decay experiments is reviewed. The results of the most sensitive experiments are discussed. Proposals for future double beta decay experiments with a sensitivity to the $$ at the level of (0.01--0.1) eV are considered.

  8. Sorting out Downside Beta

    NARCIS (Netherlands)

    G.T. Post (Thierry); P. van Vliet (Pim); S.D. Lansdorp (Simon)

    2009-01-01

    textabstractDownside risk, when properly defined and estimated, helps to explain the cross-section of US stock returns. Sorting stocks by a proper estimate of downside market beta leads to a substantially larger cross-sectional spread in average returns than sorting on regular market beta. This

  9. Electron Capture and Beta-Decay Rates for the Collapse of O+Ne+Mg Cores

    Directory of Open Access Journals (Sweden)

    Hua Lam Yi

    2014-03-01

    Full Text Available We present a new set of electron (e− capture and β-decay rates that improves previous calculations by Takahara et al. and Oda et al. by: (a incorporation of recent charge-exchange and β-decay data, (b contributions of forbidden transitions, and (c inclusion of e− screening corrections. The experimental nuclear input is supplemented by theoretical data based on large-scale shell model calculations in the full sd-shell space using the USDB interaction. The impact of these new rates on the late-stage stellar evolution of 8.8M⊙ star is demonstrated.

  10. Genetics Home Reference: beta thalassemia

    Science.gov (United States)

    ... Facebook Twitter Home Health Conditions beta thalassemia beta thalassemia Printable PDF Open All Close All Enable Javascript to view the expand/collapse boxes. Description Beta thalassemia is a blood disorder that reduces the production ...

  11. Rapid synthesis of beta zeolites

    Science.gov (United States)

    Fan, Wei; Chang, Chun -Chih; Dornath, Paul; Wang, Zhuopeng

    2015-08-18

    The invention provides methods for rapidly synthesizing heteroatom containing zeolites including Sn-Beta, Si-Beta, Ti-Beta, Zr-Beta and Fe-Beta. The methods for synthesizing heteroatom zeolites include using well-crystalline zeolite crystals as seeds and using a fluoride-free, caustic medium in a seeded dry-gel conversion method. The Beta zeolite catalysts made by the methods of the invention catalyze both isomerization and dehydration reactions.

  12. Minimal model for beta relaxation in viscous liquids

    DEFF Research Database (Denmark)

    Dyre, Jeppe; Olsen, Niels Boye

    2003-01-01

    Contrasts between beta relaxation in equilibrium viscous liquids and glasses are rationalized in terms of a double-well potential model with structure-dependent asymmetry, assuming structure is described by a single order parameter. The model is tested for tripropylene glycol where it accounts...... for the hysteresis of the dielectric beta loss peak frequency and magnitude during cooling and reheating through the glass transition....

  13. beta. -. gamma. directional correlations in the. beta. -decay of /sup 208/Tl

    Energy Technology Data Exchange (ETDEWEB)

    Rosso, O.A.; Krmpotic, F.; Szybisz, L.

    1984-02-13

    The relevance of the quenching effects induced by charge-exchange collective fields and ..delta..-isobar-hole excitations is discussed in the case of the ..beta..-..gamma.. angular correlations in the decay of /sup 208/Tl to the 5/sup -//sub 1/, 4/sup -//sub 1/ and 5/sup -//sub 2/ levels in /sup 208/Pb. It is found that, although these effects give rise to a large hindrance of the ..beta..-moments, they influence the anisotropy factor only very weakly. Satisfactory agreement between theoretical predictions and experimental data is obtained for all the transitions.

  14. The Promiscuity of [beta]-Strand Pairing Allows for Rational Design of [beta]-Sheet Face Inversion

    Energy Technology Data Exchange (ETDEWEB)

    Makabe, Koki; Koide, Shohei (UC)

    2009-06-17

    Recent studies suggest the dominant role of main-chain H-bond formation in specifying {beta}-sheet topology. Its essentially sequence-independent nature implies a large degree of freedom in designing {beta}-sheet-based nanomaterials. Here we show rational design of {beta}-sheet face inversions by incremental deletions of {beta}-strands from the single-layer {beta}-sheet of Borrelia outer surface protein A. We show that a {beta}-sheet structure can be maintained when a large number of native contacts are removed and that one can design large-scale conformational transitions of a {beta}-sheet such as face inversion by exploiting the promiscuity of strand-strand interactions. High-resolution X-ray crystal structures confirmed the success of the design and supported the importance of main-chain H-bonds in determining {beta}-sheet topology. This work suggests a simple but effective strategy for designing and controlling nanomaterials based on {beta}-rich peptide self-assemblies.

  15. Near-threshold search for the isospin-forbidden d+darrow^4He+π^0 reaction.

    Science.gov (United States)

    Stephenson, E. J.; Allgower, C.; Bacher, A. D.; Doskow, J.; Lavelle, C.; Nann, H.; Olmsted, J.; Rinckel, T.; Pickar, M. A.; Pancella, P. V.; Smith, A.; Spinka, H. M.; Rapaport, J.

    2002-10-01

    We will discuss our search at 228.5 MeV for the isospin-forbidden ddarrow^4Heπ^0 reaction, which constrains charge symmetry breaking contributions from the down-up quark mass difference and electromagnetic effects. The forward-going ^4He nuclei, which lie inside a θ_lab=1.2^rc cone, are separated from the deuteron beam in a 6^rc bending magnet and captured and identified in a magnetic channel. Separation of ^4Heπ^0 events depends on a reconstruction of the pion missing mass from channel position and time of flight in order to distinquish them from double radiative capture ^4Heγγ events. Two detector systems observe d+d elastic scattering at θ_c.m.=9.1^rc and 90^rc as a monitor of the luminosity ( ˜ 2× 10^31 /cm^2/s) given by the circulating IUCF Cooler beam and a cold D2 jet target. The d+d cross sections are scaled from p+d elastic cross sections by observing both during a run with a molecular HD target. Following two d+d commissioning runs, production began in early June 2002 and is planned to continue in July.

  16. {beta} decay of 129Cd and excited states in 129In

    Energy Technology Data Exchange (ETDEWEB)

    Taprogge, J.; Jungclaus, A.; Grawe, H.; Nishimura, S.; Doornenbal, P.; Lorusso, G.; Simpson, G. S.; Soderstrom, P. A.; Sumikama, T.; Xu, Z. Y.; Kondev, F. G.

    2015-05-26

    The β decay of Cd 129 , produced in the relativistic fission of a U 238 beam, was experimentally studied at the RIBF facility at the RIKEN Nishina Center. From the γ radiation emitted after the β decays, a level scheme of In 129 was established comprising 31 excited states and 69 γ -ray transitions. The experimentally determined level energies are compared to state-of-the-art shell-model calculations. The half-lives of the two β -decaying states in Cd 129 were deduced and the β feeding to excited states in In 129 were analyzed. It is found that, as in most cases in the Z<50 , N≤82 region, both decays are dominated by the ν0g 7/2 →π0g 9/2 Gamow–Teller transition, although the contribution of first-forbidden transitions cannot be neglected.

  17. Finite Amplitude Method for Charge-Changing Transitions in Axially-Deformed Nuclei

    CERN Document Server

    Mustonen, M T; Zenginerler, Z; Engel, J

    2014-01-01

    We describe and apply a version of the finite amplitude method for obtaining the charge-changing nuclear response in the quasiparticle random phase approximation. The method is suitable for calculating strength functions and beta-decay rates, both allowed and forbidden, in axially-deformed open-shell nuclei. We demonstrate the speed and versatility of the code through a preliminary examination of the effects of tensor terms in Skyrme functionals on beta decay in a set of spherical and deformed open-shell nuclei. Like the isoscalar pairing interaction, the tensor terms systematically increase allowed beta-decay rates. This finding generalizes previous work in semimagic nuclei and points to the need for a comprehensive study of time-odd terms in nuclear density functionals.

  18. Neutrinoless double beta decay

    Indian Academy of Sciences (India)

    Kai Zuber

    2012-10-01

    The physics potential of neutrinoless double beta decay is discussed. Furthermore, experimental considerations as well as the current status of experiments are presented. Finally, an outlook towards the future, work on nuclear matrix elements and alternative processes is given.

  19. Theoretical studies of nonadiabatic and spin-forbidden processes: Investigations of the reactions and spectroscopy of radical species relevant to combustion reactions and diagnostics

    Energy Technology Data Exchange (ETDEWEB)

    Yarkony, D.R. [Johns Hopkins Univ., Baltimore, MD (United States)

    1993-12-01

    This research program focusses on studies of spin-forbidden and electronically nonadiabatic processes involving radical species relevant to combustion reactions and combustion diagnostics. To study the electronic structure aspects of these processes a unique and powerful system of electronic structure programs, developed over the past nine years, the BROOKLYN codes, is employed. These programs enable the authors to address questions basic to the understanding of elementary combustion processes not tractable using more standard quantum chemistry codes.

  20. Measurement of the spin-forbidden decay rate (3s3d)1D2¿(3s3p)3 P2,1 in 24Mg

    DEFF Research Database (Denmark)

    Therkildsen, K. T.; Jensen, Brian Bak; Ryder, C. P.;

    2009-01-01

    We have measured the spin-forbidden decay rate from (3s3d)D12¿(3s3p)P32,1 in M24g atoms trapped in a magneto-optical trap. The total decay rate, summing up both exit channels (3s3p)P31 and (3s3p)P32 , yields 196±10s-1 in excellent agreement with resent relativistic many-body calculations of Porsev...

  1. Beta-thalassemia

    OpenAIRE

    Origa Raffaella; Galanello Renzo

    2010-01-01

    Abstract Beta-thalassemias are a group of hereditary blood disorders characterized by anomalies in the synthesis of the beta chains of hemoglobin resulting in variable phenotypes ranging from severe anemia to clinically asymptomatic individuals. The total annual incidence of symptomatic individuals is estimated at 1 in 100,000 throughout the world and 1 in 10,000 people in the European Union. Three main forms have been described: thalassemia major, thalassemia intermedia and thalassemia minor...

  2. Alpha and Beta Determinations

    CERN Document Server

    Dunietz, Isard

    1999-01-01

    Because the Bd -> J/psi Ks asymmetry determines only sin(2 beta), a discrete ambiguity in the true value of beta remains. This note reviews how the ambiguity can be removed. Extractions of the CKM angle alpha are discussed next. Some of the methods require very large data samples and will not be feasible in the near future. In the near future, semi-inclusive CP-violating searches could be undertaken, which are reviewed last.

  3. {beta} - amyloid imaging probes

    Energy Technology Data Exchange (ETDEWEB)

    Jeong, Jae Min [Seoul National University College of Medicine, Seoul (Korea, Republic of)

    2007-04-15

    Imaging distribution of {beta} - amyloid plaques in Alzheimer's disease is very important for early and accurate diagnosis. Early trial of the {beta} -amyloid plaques includes using radiolabeled peptides which can be only applied for peripheral {beta} - amyloid plaques due to limited penetration through the blood brain barrier (BBB). Congo red or Chrysamine G derivatives were labeled with Tc-99m for imaging {beta} - amyloid plaques of Alzheimer patient's brain without success due to problem with BBB penetration. Thioflavin T derivatives gave breakthrough for {beta} - amyloid imaging in vivo, and a benzothiazole derivative [C-11]6-OH-BTA-1 brought a great success. Many other benzothiazole, benzoxazole, benzofuran, imidazopyridine, and styrylbenzene derivatives have been labeled with F-18 and I-123 to improve the imaging quality. However, [C-11]6-OH-BTA-1 still remains as the best. However, short half-life of C-11 is a limitation of wide distribution of this agent. So, it is still required to develop an Tc-99m, F-18 or I-123 labeled agent for {beta} - amyloid imaging agent.

  4. Beta cell dynamics: beta cell replenishment, beta cell compensation and diabetes.

    Science.gov (United States)

    Cerf, Marlon E

    2013-10-01

    Type 2 diabetes, characterized by persistent hyperglycemia, arises mostly from beta cell dysfunction and insulin resistance and remains a highly complex metabolic disease due to various stages in its pathogenesis. Glucose homeostasis is primarily regulated by insulin secretion from the beta cells in response to prevailing glycemia. Beta cell populations are dynamic as they respond to fluctuating insulin demand. Beta cell replenishment and death primarily regulate beta cell populations. Beta cells, pancreatic cells, and extra-pancreatic cells represent the three tiers for replenishing beta cells. In rodents, beta cell self-replenishment appears to be the dominant source for new beta cells supported by pancreatic cells (non-beta islet cells, acinar cells, and duct cells) and extra-pancreatic cells (liver, neural, and stem/progenitor cells). In humans, beta cell neogenesis from non-beta cells appears to be the dominant source of beta cell replenishment as limited beta cell self-replenishment occurs particularly in adulthood. Metabolic states of increased insulin demand trigger increased insulin synthesis and secretion from beta cells. Beta cells, therefore, adapt to support their physiology. Maintaining physiological beta cell populations is a strategy for targeting metabolic states of persistently increased insulin demand as in diabetes.

  5. Connexin 36 is expressed in beta and connexins 26 and 32 in acinar cells at the end of the secondary transition of mouse pancreatic development and increase during fetal and perinatal life.

    Science.gov (United States)

    Pérez-Armendariz, Elia Martha; Cruz-Miguel, Lourdes; Coronel-Cruz, Cristina; Esparza-Aguilar, Marcelino; Pinzon-Estrada, Enrique; Rancaño-Camacho, Elizabeth; Zacarias-Climaco, Gerardo; Olivares, Paola Fernández; Espinosa, Ana Maria; Becker, Ingeborg; Sáez, Juan C; Berumen, Jaime; Pérez-Palacios, Gregorio

    2012-06-01

    To identify when during fetal development connexins (Cxs) 26 (Cx26) 32 (Cx32), and 36 (Cx36) begin to be expressed, as well as to characterize their spatial distribution, real time polymerase chain reaction and immunolabeling studies were performed. Total RNA from mouse pancreases at 13 and 18 days postcoitum (dpc) and 3 days postpartum (dpp) was analyzed. In addition, pancreatic sections of mouse at 13, 14, 15, 16, 18 dpc and 3 dpp and of rat at term were double labeled with either anti-insulin or anti-α-amylase and anti-Cx26 or -Cx32 or -Cx36 antibodies and studied with confocal microscopy. From day 13 dpc, Cxs 26, 32, and 36 transcripts were identified and their levels increased with age. At 13-14 dpc, Cxs 26 and 32 were localized in few acinar cells, whereas Cx36 was distributed in small beta cell clumps. From day 14 dpc onwards, the number of labeled cells and relative immunofluorescent reactivity of all three Cxs at junctional membranes of the respective cell types increased. Cxs 26 and 32 colocalized in fetal acinar cells. In rat pancreas at term, a similar connexin distribution was found. Relative Cxs levels evaluated by immunoblotting also increased (two-fold) in pancreas homogenates from day 18 dpc to 3 dpp. The early cell specific, wide distribution, and age dependent expression of Cxs 26, 32, and 36 during fetal pancreas ontogeny suggests their possible involvement in pancreas differentiation and prenatal maturation.

  6. Electromagnetic transitions in multiple chiral doublet bands

    CERN Document Server

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

    2016-01-01

    Multiple chiral doublet bands (M$\\chi$D) in the $80$, 130 and $190$ mass regions are studied by the model of $\\gamma$=90$^{\\circ}$ triaxial rotor coupled with identical symmetric proton-neutron configurations. By selecting the suitable basis, the calculated wave functions are explicitly exhibited to be symmetric under the operator $\\hat{A}$, which is defined as rotation by $90^{\\circ}$ about 3-axis with the exchange of valance proton and neutron. We found that both $M1$ and $E2$ transitions are allowed between the levels with different values of $A$, while are forbidden between the levels with same values of $A$. Such a selection rule holds true for M$\\chi$D in different mass regions.

  7. Boosted beta regression.

    Directory of Open Access Journals (Sweden)

    Matthias Schmid

    Full Text Available Regression analysis with a bounded outcome is a common problem in applied statistics. Typical examples include regression models for percentage outcomes and the analysis of ratings that are measured on a bounded scale. In this paper, we consider beta regression, which is a generalization of logit models to situations where the response is continuous on the interval (0,1. Consequently, beta regression is a convenient tool for analyzing percentage responses. The classical approach to fit a beta regression model is to use maximum likelihood estimation with subsequent AIC-based variable selection. As an alternative to this established - yet unstable - approach, we propose a new estimation technique called boosted beta regression. With boosted beta regression estimation and variable selection can be carried out simultaneously in a highly efficient way. Additionally, both the mean and the variance of a percentage response can be modeled using flexible nonlinear covariate effects. As a consequence, the new method accounts for common problems such as overdispersion and non-binomial variance structures.

  8. The omega --> pi0 gamma* and phi --> pi0 gamma* transition form factors in dispersion theory

    CERN Document Server

    Schneider, Sebastian P; Niecknig, Franz

    2012-01-01

    We calculate the omega --> pi0 gamma* and phi --> pi0 gamma* electromagnetic transition form factors based on dispersion theory, relying solely on a previous dispersive analysis of the corresponding three-pion decays and the pion vector form factor. We compare our findings to recent measurements of the omega --> pi0 mu+ mu- decay spectrum by the NA60 collaboration, and strongly encourage experimental investigation of the Okubo-Zweig-Iizuka-forbidden phi --> pi0 l+ l- decays in order to understand the strong deviations from vector-meson dominance found in these transition form factors.

  9. Study of structural and optical properties of lead borate glasses containing transition metal ion

    Science.gov (United States)

    Sanjay, Kaushik, A.; Kishore, N.; Agarwal, A.; Pal, I.; Dhar, R.

    2012-06-01

    Glasses with compositions xFe2O3.(40-x)PbO.60B2O3: V2O5 (2 mol%) have been prepared by the standard melt-quenching technique. Various properties such as glass transition temperature, density, IR spectra and optical band gap energy have been studied. The structural changes in these glasses have been monitored by IR spectroscopy. The values of optical band gap for indirect allowed and indirect forbidden transitions have been determined using available theories. The Urbach's energy is used to characterize the degree of disorder in amorphous solids.

  10. Double Beta Decay

    CERN Document Server

    Elliott, Steven R

    2011-01-01

    At least one neutrino has a mass of about 50 meV or larger. However, the absolute mass scale for the neutrino remains unknown. Furthermore, the critical question: Is the neutrino its own antiparticle? is unanswered. Studies of double beta decay offer hope for determining the absolute mass scale. In particular, zero-neutrino double beta decay (\\BBz) can address the issues of lepton number conservation, the particle-antiparticle nature of the neutrino, and its mass. A summary of the recent results in \\BBz, and the related technologies will be discussed in the context of the future \\BBz\\ program.

  11. Beta and Gamma Gradients

    DEFF Research Database (Denmark)

    Løvborg, Leif; Gaffney, C. F.; Clark, P. A.;

    1985-01-01

    Experimental and/or theoretical estimates are presented concerning, (i) attenuation within the sample of beta and gamma radiation from the soil, (ii) the gamma dose within the sample due to its own radioactivity, and (iii) the soil gamma dose in the proximity of boundaries between regions...... of differing radioactivity. It is confirmed that removal of the outer 2 mm of sample is adequate to remove influence from soil beta dose and estimates are made of the error introduced by non-removal. Other evaluations include variation of the soil gamma dose near the ground surface and it appears...

  12. Systematics of Gamow-Teller beta decay "Southeast" of Sn-100

    NARCIS (Netherlands)

    Batist, L.; Gorska, M.; Grawe, H.; Janas, Z.; Kavatsyuk, M.; Karny, M.; Kirchner, R.; La Commara, M.; Mukha, I.; Plochocki, A.; Roeckl, E.

    2010-01-01

    The energy centroids and integrated strengths of Gamow-Teller transitions in the beta(+) and electron-capture decay are analyzed for nuclei whose proton number Z and neutron number N are restricted to 44

  13. Molecular analysis of the beta-globin gene cluster in the Niokholo Mandenka population reveals a recent origin of the beta(S) Senegal mutation.

    Science.gov (United States)

    Currat, Mathias; Trabuchet, Guy; Rees, David; Perrin, Pascale; Harding, Rosalind M; Clegg, John B; Langaney, André; Excoffier, Laurent

    2002-01-01

    A large and ethnically well-defined Mandenka sample from eastern Senegal was analyzed for the polymorphism of the beta-globin gene cluster on chromosome 11. Five RFLP sites of the 5' region were investigated in 193 individuals revealing the presence of 10 different haplotypes. The frequency of the sickle-cell anemia causing mutation (beta(S)) in the Mandenka estimated from this sample is 11.7%. This mutation was found strictly associated with the single Senegal haplotype. Approximately 600 bp of the upstream region of the beta-globin gene were sequenced for a subset of 94 chromosomes, showing the presence of four transversions, five transitions, and a composite microsatellite polymorphism. The sequence of 22 beta(S) chromosomes was also identical to the previously defined Senegal haplotype, suggesting that this mutation is very recent. Monte Carlo simulations (allowing for a specific balancing selection model, a logistic growth of the population, and variable initial frequencies of the Senegal haplotype) were used to estimate the age of the beta(S) mutation. Resulting maximum-likelihood estimates are 45-70 generations (1,350-2,100 years) for very different demographic scenarios. Smallest confidence intervals (25-690 generations) are obtained under the hypothesis that the Mandenka population is large (N(e) >5,000) and stationary or that it has undergone a rapid demographic expansion to a current size of >5,000 reproducing individuals, which is quite likely in view of the great diversity found on beta(A) chromosomes.

  14. The pleiotropic roles of transforming growth factor beta inhomeostasis and carcinogenesis of endocrine organs.

    Energy Technology Data Exchange (ETDEWEB)

    Fleisch, Markus C.; Maxwell, Christopher A.; Barcellos-Hoff,Mary-Helen

    2006-01-13

    Transforming growth factor beta (TGF-beta) is a ubiquitous cytokine that plays a critical role in numerous pathways regulating cellular and tissue homeostasis. TGF-beta is regulated by hormones and is a primary mediator of hormone response in uterus, prostate and mammary gland. This review will address the role of TGF-beta in regulating hormone dependent proliferation and morphogenesis. The subversion of TGF-beta regulation during the processes of carcinogenesis, with particular emphasis on its effects on genetic stability and epithelial to mesenchymal transition (EMT), will also be examined. An understanding of the multiple and complex mechanisms of TGF-beta regulation of epithelial function, and the ultimate loss of TGF-beta function during carcinogenesis, will be critical in the design of novel therapeutic interventions for endocrine-related cancers.

  15. Neutrinoless double beta decay from a modern perspective

    CERN Document Server

    Vergados, J D

    2002-01-01

    Neutrinoless double beta decay is a very important process both from the particle and nuclear physics point of view. From the elementary particle point of view it pops up in almost every model. giving rise, among others, to the following mechanisms: a) The traditional contributions like the light neutrino mass mechanism . b) The exotic R-parity violating supersymmetric (SUSY) contributions. Similar considerations apply to its sister lepton and muon number violating muon to positron conversion. The observation of neutrinoless double beta decay will signal that the neutrinos are massive Majorana particles. For nuclear physics it is challenging, because: 1) The nuclei, which can undergo double beta decay, have complicated structure. 2) The energetically allowed transitions are suppressed. 3) One must cope with the short distance behavior of the transition operators. Thus novel effects (decay of pions in flight between nucleons etc) have to be considered. 4) One has to take into account possible momentum dependen...

  16. Chimpanzees share forbidden fruit.

    Directory of Open Access Journals (Sweden)

    Kimberley J Hockings

    Full Text Available The sharing of wild plant foods is infrequent in chimpanzees, but in chimpanzee communities that engage in hunting, meat is frequently used as a 'social tool' for nurturing alliances and social bonds. Here we report the only recorded example of regular sharing of plant foods by unrelated, non-provisioned wild chimpanzees, and the contexts in which these sharing behaviours occur. From direct observations, adult chimpanzees at Bossou (Republic of Guinea, West Africa very rarely transferred wild plant foods. In contrast, they shared cultivated plant foods much more frequently (58 out of 59 food sharing events. Sharing primarily consists of adult males allowing reproductively cycling females to take food that they possess. We propose that hypotheses focussing on 'food-for-sex and -grooming' and 'showing-off' strategies plausibly account for observed sharing behaviours. A changing human-dominated landscape presents chimpanzees with fresh challenges, and our observations suggest that crop-raiding provides adult male chimpanzees at Bossou with highly desirable food commodities that may be traded for other currencies.

  17. Trichoderma .beta.-glucosidase

    Science.gov (United States)

    Dunn-Coleman, Nigel; Goedegebuur, Frits; Ward, Michael; Yao, Jian

    2006-01-03

    The present invention provides a novel .beta.-glucosidase nucleic acid sequence, designated bgl3, and the corresponding BGL3 amino acid sequence. The invention also provides expression vectors and host cells comprising a nucleic acid sequence encoding BGL3, recombinant BGL3 proteins and methods for producing the same.

  18. Roughing up Beta

    DEFF Research Database (Denmark)

    Bollerslev, Tim; Li, Sophia Zhengzi; Todorov, Viktor

    Motivated by the implications from a stylized equilibrium pricing framework, we investigate empirically how individual equity prices respond to continuous, or \\smooth," and jumpy, or \\rough," market price moves, and how these different market price risks, or betas, are priced in the cross-section...

  19. Applied Beta Dosimetry

    Energy Technology Data Exchange (ETDEWEB)

    Rich, B.L.

    1986-01-01

    Measurements of beta and/or nonpenetrating exposure results is complicated and past techniques and capabilities have resulted in significant inaccuracies in recorded results. Current developments have resulted in increased capabilities which make the results more accurate and should result in less total exposure to the work force. Continued development of works in progress should provide equivalent future improvements.

  20. Beta thalassemia - a review

    Directory of Open Access Journals (Sweden)

    R Jha

    2014-09-01

    Full Text Available Thalassemia is a globin gene disorder that results in a diminished rate of synthesis of one or more of the globin chains. About 1.5% of the global population (80 to 90 million people are carriers of beta Thalassemia. More than 200 mutations are described in beta thalassemia. However not all mutations are common in different ethnic groups. The only effective way to reduce burden of thalassemia is to prevent birth of homozygotes. Diagnosis of beta thalassemia can be done by fetal DNA analysis for molecular defects of beta thalassemia or by fetal blood analysis. Hematopoietic stem cell transplantation is the only available curative approach for Thalassemia. Many patients with thalassemia in underdeveloped nations die in childhood or adolescence. Programs that provide acceptable care, including transfusion of safe blood and supportive therapy including chelation must be established.DOI: http://dx.doi.org/10.3126/jpn.v4i8.11609 Journal of Pathology of Nepal; Vol.4,No. 8 (2014 663-671

  1. Period change and stellar evolution of $\\beta$ Cephei stars

    CERN Document Server

    Neilson, Hilding R

    2015-01-01

    The $\\beta$ Cephei stars represent an important class of massive star pulsators probing the evolution of B-type stars and the transition from main sequence to hydrogen-shell burning evolution. By understanding $\\beta$ Cep stars, we gain insights into the detailed physics of massive star evolution such as rotational mixing, convective core overshooting, magnetic fields and stellar winds, all of which play important roles. Similarly, modeling their pulsation provides additional information into their interior structures. Furthermore, measurements of the rate of change of pulsation period offer a direct measure of $\\beta$ Cephei stellar evolution. In this work, we compute state-of-the-art stellar evolution models assuming different amounts of initial rotation and convective core overshoot and measure theoretical rates of period change for which we compare to rates previously measured for a sample of $\\beta$ Cephei stars. The results of this comparison are mixed. For three stars, the rates are too small to infer ...

  2. Beta cell adaptation in pregnancy

    DEFF Research Database (Denmark)

    Nielsen, Jens Høiriis

    2016-01-01

    Pregnancy is associated with a compensatory increase in beta cell mass. It is well established that somatolactogenic hormones contribute to the expansion both indirectly by their insulin antagonistic effects and directly by their mitogenic effects on the beta cells via receptors for prolactin...... and growth hormone expressed in rodent beta cells. However, the beta cell expansion in human pregnancy seems to occur by neogenesis of beta cells from putative progenitor cells rather than by proliferation of existing beta cells. Claes Hellerström has pioneered the research on beta cell growth for decades...... in the expansion of the beta cell mass in human pregnancy, and the relative roles of endocrine factors and nutrients....

  3. Magnitude of a conformational change in the glycine receptor beta1-beta2 loop is correlated with agonist efficacy

    DEFF Research Database (Denmark)

    Pless, Stephan Alexander; Lynch, Joseph W

    2009-01-01

    associated with the closed-flip transition in the alpha1-glycine receptor. We employed voltage-clamp fluorometry to compare ligand-binding domain conformational changes induced by the following agonists, listed from highest to lowest affinity and efficacy: glycine > beta-alanine > taurine. Voltage...

  4. TGF-beta and osteoarthritis.

    NARCIS (Netherlands)

    Blaney Davidson, E.N.; Kraan, P.M. van der; Berg, W.B. van den

    2007-01-01

    OBJECTIVE: Cartilage damage is a major problem in osteoarthritis (OA). Growth factors like transforming growth factor-beta (TGF-beta) have great potential in cartilage repair. In this review, we will focus on the potential therapeutic intervention in OA with TGF-beta, application of the growth facto

  5. Conditions for $\\beta$-perfectness

    NARCIS (Netherlands)

    Keijsper, J.C.M.; Tewes, M.

    2000-01-01

    A $\\beta$-perfect graph is a simple graph $G$ such that $\\chi(G')=\\beta(G')$ for every induced subgraph $G'$ of $G$, where $\\chi(G')$ is the chromatic number of $G'$, and $\\beta(G')$ is defined as the maximum over all induced subgraphs $H$ of $G'$ of the minimum vertex degree in $H$. The vertices of

  6. Misleading Betas: An Educational Example

    Science.gov (United States)

    Chong, James; Halcoussis, Dennis; Phillips, G. Michael

    2012-01-01

    The dual-beta model is a generalization of the CAPM model. In the dual-beta model, separate beta estimates are provided for up-market and down-market days. This paper uses the historical "Anscombe quartet" results which illustrated how very different datasets can produce the same regression coefficients to motivate a discussion of the…

  7. Differential regulation of chemoattractant-stimulated beta 2, beta 3, and beta 7 integrin activity.

    Science.gov (United States)

    Sadhu, C; Masinovsky, B; Staunton, D E

    1998-06-01

    Leukocyte adhesion to endothelium and extravasation are dynamic processes that require activation of integrins. Chemoattractants such as IL-8 and FMLP are potent activators of leukocyte integrins. To compare the chemoattractant-stimulated activation of three integrins, alpha 4 beta 7, alpha L beta 2, and alpha V beta 3, in the same cellular context, we expressed an IL-8 receptor (IL-8RA) and FMLP receptor (FPR) in the lymphoid cell line JY. Chemoattractants induced a rapid increase in alpha L beta 2- and alpha V beta 3-dependent JY adhesion within 5 min, and it was sustained for 30 min. In contrast, stimulation of alpha 4 beta 7-dependent adhesion was transient, returning to basal levels by 30 min. The activation profiles of the integrins were similar regardless of whether IL-8 or FMLP was used for induction. We also demonstrate that alpha 4 beta 7-dependent adhesion was uniquely responsive to the F actin-disrupting agent cytochalasin D and the protein kinase C (PKC) inhibitor chelerythrin. While alpha V beta 3- and alpha L beta 2-mediated cell adhesion was significantly reduced by cytochalasin D, alpha 4 beta 7-mediated adhesion was enhanced. Chelerythrin inhibited both the IL-8 and PMA activation of alpha L beta 2 and alpha V beta 3. In contrast, inducible alpha 4 beta 7 activity was unaffected, and basal activity was increased. These findings demonstrate that the mechanism of alpha 4 beta 7 regulation by chemoattractants is different from that of alpha L beta 2 and alpha V beta 3 and that it appears to involve distinct cytoskeletal and PKC dependencies. In addition, PKC activity may be a positive or negative regulator of integrin-dependent adhesion.

  8. Beta-thalassemia

    Directory of Open Access Journals (Sweden)

    Origa Raffaella

    2010-05-01

    Full Text Available Abstract Beta-thalassemias are a group of hereditary blood disorders characterized by anomalies in the synthesis of the beta chains of hemoglobin resulting in variable phenotypes ranging from severe anemia to clinically asymptomatic individuals. The total annual incidence of symptomatic individuals is estimated at 1 in 100,000 throughout the world and 1 in 10,000 people in the European Union. Three main forms have been described: thalassemia major, thalassemia intermedia and thalassemia minor. Individuals with thalassemia major usually present within the first two years of life with severe anemia, requiring regular red blood cell (RBC transfusions. Findings in untreated or poorly transfused individuals with thalassemia major, as seen in some developing countries, are growth retardation, pallor, jaundice, poor musculature, hepatosplenomegaly, leg ulcers, development of masses from extramedullary hematopoiesis, and skeletal changes that result from expansion of the bone marrow. Regular transfusion therapy leads to iron overload-related complications including endocrine complication (growth retardation, failure of sexual maturation, diabetes mellitus, and insufficiency of the parathyroid, thyroid, pituitary, and less commonly, adrenal glands, dilated myocardiopathy, liver fibrosis and cirrhosis. Patients with thalassemia intermedia present later in life with moderate anemia and do not require regular transfusions. Main clinical features in these patients are hypertrophy of erythroid marrow with medullary and extramedullary hematopoiesis and its complications (osteoporosis, masses of erythropoietic tissue that primarily affect the spleen, liver, lymph nodes, chest and spine, and bone deformities and typical facial changes, gallstones, painful leg ulcers and increased predisposition to thrombosis. Thalassemia minor is clinically asymptomatic but some subjects may have moderate anemia. Beta-thalassemias are caused by point mutations or, more rarely

  9. Beta-thalassemia.

    Science.gov (United States)

    Galanello, Renzo; Origa, Raffaella

    2010-05-21

    Beta-thalassemias are a group of hereditary blood disorders characterized by anomalies in the synthesis of the beta chains of hemoglobin resulting in variable phenotypes ranging from severe anemia to clinically asymptomatic individuals. The total annual incidence of symptomatic individuals is estimated at 1 in 100,000 throughout the world and 1 in 10,000 people in the European Union. Three main forms have been described: thalassemia major, thalassemia intermedia and thalassemia minor. Individuals with thalassemia major usually present within the first two years of life with severe anemia, requiring regular red blood cell (RBC) transfusions. Findings in untreated or poorly transfused individuals with thalassemia major, as seen in some developing countries, are growth retardation, pallor, jaundice, poor musculature, hepatosplenomegaly, leg ulcers, development of masses from extramedullary hematopoiesis, and skeletal changes that result from expansion of the bone marrow. Regular transfusion therapy leads to iron overload-related complications including endocrine complication (growth retardation, failure of sexual maturation, diabetes mellitus, and insufficiency of the parathyroid, thyroid, pituitary, and less commonly, adrenal glands), dilated myocardiopathy, liver fibrosis and cirrhosis). Patients with thalassemia intermedia present later in life with moderate anemia and do not require regular transfusions. Main clinical features in these patients are hypertrophy of erythroid marrow with medullary and extramedullary hematopoiesis and its complications (osteoporosis, masses of erythropoietic tissue that primarily affect the spleen, liver, lymph nodes, chest and spine, and bone deformities and typical facial changes), gallstones, painful leg ulcers and increased predisposition to thrombosis. Thalassemia minor is clinically asymptomatic but some subjects may have moderate anemia. Beta-thalassemias are caused by point mutations or, more rarely, deletions in the beta

  10. Beta-thalassemia

    Science.gov (United States)

    2010-01-01

    Beta-thalassemias are a group of hereditary blood disorders characterized by anomalies in the synthesis of the beta chains of hemoglobin resulting in variable phenotypes ranging from severe anemia to clinically asymptomatic individuals. The total annual incidence of symptomatic individuals is estimated at 1 in 100,000 throughout the world and 1 in 10,000 people in the European Union. Three main forms have been described: thalassemia major, thalassemia intermedia and thalassemia minor. Individuals with thalassemia major usually present within the first two years of life with severe anemia, requiring regular red blood cell (RBC) transfusions. Findings in untreated or poorly transfused individuals with thalassemia major, as seen in some developing countries, are growth retardation, pallor, jaundice, poor musculature, hepatosplenomegaly, leg ulcers, development of masses from extramedullary hematopoiesis, and skeletal changes that result from expansion of the bone marrow. Regular transfusion therapy leads to iron overload-related complications including endocrine complication (growth retardation, failure of sexual maturation, diabetes mellitus, and insufficiency of the parathyroid, thyroid, pituitary, and less commonly, adrenal glands), dilated myocardiopathy, liver fibrosis and cirrhosis). Patients with thalassemia intermedia present later in life with moderate anemia and do not require regular transfusions. Main clinical features in these patients are hypertrophy of erythroid marrow with medullary and extramedullary hematopoiesis and its complications (osteoporosis, masses of erythropoietic tissue that primarily affect the spleen, liver, lymph nodes, chest and spine, and bone deformities and typical facial changes), gallstones, painful leg ulcers and increased predisposition to thrombosis. Thalassemia minor is clinically asymptomatic but some subjects may have moderate anemia. Beta-thalassemias are caused by point mutations or, more rarely, deletions in the beta

  11. Realized Beta GARCH

    DEFF Research Database (Denmark)

    Hansen, Peter Reinhard; Lunde, Asger; Voev, Valeri Radkov

    2014-01-01

    We introduce a multivariate generalized autoregressive conditional heteroskedasticity (GARCH) model that incorporates realized measures of variances and covariances. Realized measures extract information about the current levels of volatilities and correlations from high-frequency data, which...... is particularly useful for modeling financial returns during periods of rapid changes in the underlying covariance structure. When applied to market returns in conjunction with returns on an individual asset, the model yields a dynamic model specification of the conditional regression coefficient that is known...... as the beta. We apply the model to a large set of assets and find the conditional betas to be far more variable than usually found with rolling-window regressions based exclusively on daily returns. In the empirical part of the paper, we examine the cross-sectional as well as the time variation...

  12. Measurement of sin2{beta} in Tree Dominated B{sup 0} Decays and Ambiguity Removal

    Energy Technology Data Exchange (ETDEWEB)

    Lacker, H. [Institute of Nuclear and Particle Physics, Technical University Dresden, D-01062 Dresden (Germany)

    2007-08-15

    The most recent results from the B-factories on the time-dependent CP asymmetries measured in B{sup 0}-decays mediated by b{yields}cc-bar s quark-transitions are reviewed. The Standard Model interpretation of the results in terms of the parameter sin2{beta} leads to a four-fold ambiguity on the unitarity triangle {beta} which can be reduced to a two-fold ambiguity by measuring the sign of the parameter cos2{beta}. The results on cos2{beta} obtained so far are reviewed.

  13. Measurement of sin(2beta) in Tree-dominated B^0-Decays and Ambiguity Removal

    Energy Technology Data Exchange (ETDEWEB)

    Lacker, Heiko

    2007-03-05

    The most recent results from the B-factories on the time-dependent CP asymmetries measured in B{sup 0}-decays mediated by b {yields} c{bar c}s quark-transitions are reviewed. The Standard Model interpretation of the results in terms of the parameter sin 2{beta} leads to a four-fold ambiguity on the unitarity triangle {beta} which can be reduced to a two-fold ambiguity by measuring the sign of the parameter cos 2{beta}. The results on cos 2{beta} obtained so far are reviewed.

  14. Measurement of Sin(2beta) in Tree Dominated B0 Decays And Ambiguity Removal

    Energy Technology Data Exchange (ETDEWEB)

    Lacker, H.; /Dresden, Tech. U.

    2007-11-20

    The most recent results from the B-factories on the time-dependent CP asymmetries measured in B{sup 0}-decays mediated by b {yields} c{bar c}s quark-transitions are reviewed. The Standard Model interpretation of the results in terms of the parameter sin 2{beta} leads to a four-fold ambiguity on the unitarity triangle {beta} which can be reduced to a two-fold ambiguity by measuring the sign of the parameter cos 2{beta}. The results on cos2{beta} obtained so far are reviewed.

  15. Theoretical study of the NO beta system

    Science.gov (United States)

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

    1991-01-01

    A theoretical determination of the transition moment functions (TMFs) for the beta system of NO is presented. High levels of correlation treatment are required to show the changing degree of Rydberg character in the B2II with decreasing r values. The state-averaged complete-active-space self-consistent-field multireference configuration-interaction method is used for the determination. Previous lifetime measurements made with laser-induced fluorescence, varying between 2 and 0.85 microns, are discussed in terms of the calculated lifetimes for v-prime values 0-6, which vary from 2.12-1.17 microns. When larger r values are used for the transition moment function, the calculated lifetimes correlate with experimental lifetimes. The Einstein coefficients agree with experimental results, although limitations in the calibration of the spectrometer can account for systematic differences. The correlation with earlier experimental results suggests that radiative lifetimes are in the range of 1-2 microns.

  16. Magic Baseline Beta Beam

    CERN Document Server

    Agarwalla, Sanjib Kumar; Raychaudhuri, Amitava

    2007-01-01

    We study the physics reach of an experiment where neutrinos produced in a beta-beam facility at CERN are observed in a large magnetized iron calorimeter (ICAL) at the India-based Neutrino Observatory (INO). The CERN-INO distance is close to the so-called "magic" baseline which helps evade some of the parameter degeneracies and allows for a better measurement of the neutrino mass hierarchy and $\\theta_{13}$.

  17. Coroutine Sequencing in BETA

    DEFF Research Database (Denmark)

    Kristensen, Bent Bruun; Madsen, Ole Lehrmann; Møller-Pedersen, Birger;

    In object-oriented programming, a program execution is viewed as a physical model of some real or imaginary part of the world. A language supporting object-oriented programming must therefore contain comprehensive facilities for modeling phenomena and concepts form the application domain. Many ap...... applications in the real world consist of objects carrying out sequential processes. Coroutines may be used for modeling objects that alternate between a number of sequential processes. The authors describe coroutines in BETA...

  18. Regulation of beta cell replication

    DEFF Research Database (Denmark)

    Lee, Ying C; Nielsen, Jens Høiriis

    2008-01-01

    Beta cell mass, at any given time, is governed by cell differentiation, neogenesis, increased or decreased cell size (cell hypertrophy or atrophy), cell death (apoptosis), and beta cell proliferation. Nutrients, hormones and growth factors coupled with their signalling intermediates have been...... suggested to play a role in beta cell mass regulation. In addition, genetic mouse model studies have indicated that cyclins and cyclin-dependent kinases that determine cell cycle progression are involved in beta cell replication, and more recently, menin in association with cyclin-dependent kinase...... inhibitors has been demonstrated to be important in beta cell growth. In this review, we consider and highlight some aspects of cell cycle regulation in relation to beta cell replication. The role of cell cycle regulation in beta cell replication is mostly from studies in rodent models, but whether...

  19. Coefficient of Thermal Expansion of the Beta and Delta Polymorphs of HMX

    Energy Technology Data Exchange (ETDEWEB)

    Weese, R K; Burnham, A K; Maienschein, J L

    2004-08-05

    Dimensional changes related to temperature cycling of the beta and delta polymorphs of HMX (octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine) are important for a variety of applications. The coefficient of thermal expansion (CTE) of the beta and delta phases are measured and reported in this work over a temperature range of -20 C to 215 C. In addition, dimensional changes associated with the phase transition were measured, both through the transition and back down. Initially, differential scanning calorimetry (DSC) was used to investigate back conversion of the delta phase to the beta phase polymorph. The most successful approach was first to measure the amount of the beta to delta conversion, then after a given cooling period a repeat analysis, to measure the heat consumed by a second pass through the beta to delta phase transition. In addition, TMA is used to measure the dimensional change of a 0.20-gram sample of HMX during its initial heating and then three days later during a 2nd heating. This HMX shows the beta to delta phase transition a second time, thereby confirming the back conversion from delta to beta phase HMX.

  20. LHCb: $2\\beta_s$ measurement at LHCb

    CERN Multimedia

    Conti, G

    2009-01-01

    A measurement of $2\\beta_s$, the phase of the $B_s-\\bar{B_s}$ oscillation amplitude with respect to that of the ${\\rm b} \\rightarrow {\\rm c^{+}}{\\rm W^{-}}$ tree decay amplitude, is one of the key goals of the LHCb experiment with first data. In the Standard Model (SM), $2\\beta_s$ is predicted to be $0.0360^{+0.0020}_{-0.0016} \\rm rad$. The current constraints from the Tevatron are: $2\\beta_{s}\\in[0.32 ; 2.82]$ at 68$\\%$CL from the CDF experiment and $2\\beta_{s}=0.57^{+0.24}_{-0.30}$ from the D$\\oslash$ experiment. Although the statistical uncertainties are large, these results hint at the possible contribution of New Physics in the $B_s-\\bar{B_s}$ box diagram. After one year of data taking at LHCb at an average luminosity of $\\mathcal{L}\\sim2\\cdot10^{32}\\rm cm^{-2} \\rm s^{-1}$ (integrated luminosity $\\mathcal{L}_{\\rm int}\\sim 2 \\rm fb^{-1}$), the expected statistical uncertainty on the measurement is $\\sigma(2\\beta_s)\\simeq 0.03$. This uncertainty is similar to the $2\\beta_s$ value predicted by the SM.

  1. Application of rock- chiseling hammer in explosive- forbidden project%凿岩棒在禁爆项目中的应用

    Institute of Scientific and Technical Information of China (English)

    陈开堤; 石全贵; 林文电

    2016-01-01

    凿岩棒破岩清礁是一种简便、环保的施工工艺,对改建码头附近原有建筑物或设施破坏性小。文章从施工原理、施工工艺、施工质量控制和应用情况等方面阐述了凿岩棒在禁爆项目中的应用。在码头改建项目中,破岩清礁效果良好。%The application of rock-chiseling hammer in breaking rock and clearing reef is a convenient and environmental-friendly construction technique, which has such advantages as minimized destruction to the existing structures and facilities adjacent to the quay to be reconstructed, convenient, and easy operation maneuver. We elaborate on the application of rock-chiseling hammer in rock-breaking and reef-clearing during construction of foundation bed in explosive-forbidden project by expounding the construction theory, construction technique, quality control and the result of its application for the purpose of serving as a valuable reference for explosive-forbidden project such as reconstruction and extension projects.

  2. Beta decay of {sup 101}Sn

    Energy Technology Data Exchange (ETDEWEB)

    Kavatsyuk, O.; Kavatsyuk, M. [Gesellschaft fuer Schwerionenforschung, Damrstadt (Germany); National Taras Shevchenko Univ. of Kyiv (Ukraine); Mazzocchi, C. [Gesellschaft fuer Schwerionenforschung, Damrstadt (Germany); Univ. of Tennessee, Knoxville (United States); Janas, Z.; Karny, M.; Miernik, K.; Plochocki, A.; Zylicz, J. [University of Warsaw (Poland); Banu, A.; Becker, F.; Bruechle, W.; Doering, J.; Gorska, M.; Grawe, H.; Klepper, O.; Kirchner, R.; Plettner, C.; Roeckl, E.; Schaedel, M. [Gesellschaft fuer Schwerionenforschung, Darmstadt, Darmstadt (Germany); Batist, L. [St. Petersburg Nuclear Physics Institute (Russian Federation); Blazhev, A. [Gesellschaft fuer Schwerionenforschung, Damrstadt (Germany); Univ. of Sofia (Bulgaria); Faestermann, T. [Technische Universitaet Muenchen (Germany); Jungclaus, A. [Instituto Estructura de la Materia, CSIC (Spain); Departamento de Fisica Teorica, UAM, Madrid (Spain); La Commara, M.; Romoli, M. [Universita ' ' Federico II' ' , Napoli (Italy); INFN, Napoli (Italy); Mukha, I. [Gesellschaft fuer Schwerionenforschung, Damrstadt (Germany); Kurchatov Inst., Moscow (Russian Federation); Rykaczewski, K. [Oak Ridge National Laboratory, Oak Ridge (United States); Schmidt, K. [Continental Teves AG and Co., Frankfurt am Main (Germany); Schwengner, R. [Institut fuer Kern- und Hadronenphysik, Forschungszentrum Rossendorf, Dresden (Germany)

    2007-03-15

    The {beta} decay of the very neutron-deficient isotope {sup 101}Sn was studied at the GSI on-line mass separator using silicon detectors for recording charged particles and germanium detectors for {gamma}-ray spectroscopy. Based on the {beta}-delayed proton data the production cross-section of {sup 101}Sn in the {sup 50}Cr+{sup 58}Ni fusion-evaporation reaction was determined to be about 60nb. The half-life of {sup 101}Sn was measured to be 1.9(3)s. For the first time {beta}-delayed {gamma}-rays of {sup 101}Sn were tentatively identified, yielding weak evidence for a cascade of 352 and 1065keV transitions in {sup 101}In. The results for the {sup 101}Sn decay as well as those from previous work on the {sup 103}Sn decay are discussed by comparing them to predictions obtained from shell model calculations employing a new interaction in the {sup 88}Sr to {sup 132}Sn model space. (orig.)

  3. Forbidden energy band gap in diluted a-Ge{sub 1-x}Si{sub x}:N films

    Energy Technology Data Exchange (ETDEWEB)

    Guarneros, C.; Rebollo-Plata, B. [Posgrado en Fisica Aplicada, Facultad de Ciencias Fisico-Matematicas, Benemerita Universidad Autonoma de Puebla, Blvd. 14 Sur 6301, Col. San Manuel, 72570, Puebla (Mexico); Lozada-Morales, R., E-mail: rlozada@fcfm.buap.mx [Posgrado en Fisica Aplicada, Facultad de Ciencias Fisico-Matematicas, Benemerita Universidad Autonoma de Puebla, Blvd. 14 Sur 6301, Col. San Manuel, 72570, Puebla (Mexico); Espinosa-Rosales, J.E. [Posgrado en Fisica Aplicada, Facultad de Ciencias Fisico-Matematicas, Benemerita Universidad Autonoma de Puebla, Blvd. 14 Sur 6301, Col. San Manuel, 72570, Puebla (Mexico); Portillo-Moreno, J. [Facultad de Ciencias Quimicas, Benemerita Universidad Autonoma de Puebla, Blvd. 14 Sur 6301, Col. San Manuel, 72570, Puebla (Mexico); Zelaya-Angel, O. [Departamento de Fisica, Centro de Investigacion y de Estudios Avanzados del IPN, PO Box 14-740, Mexico 07360 D.F. (Mexico)

    2012-06-01

    By means of electron gun evaporation Ge{sub 1-x}Si{sub x}:N thin films, in the entire range 0 {<=} x {<=} 1, were prepared on Si (100) and glass substrates. The initial vacuum reached was 6.6 Multiplication-Sign 10{sup -4} Pa, then a pressure of 2.7 Multiplication-Sign 10{sup -2} Pa of high purity N{sub 2} was introduced into the chamber. The deposition time was 4 min. Crucible-substrate distance was 18 cm. X-ray diffraction patterns indicate that all the films were amorphous (a-Ge{sub 1-x}Si{sub x}:N). The nitrogen concentration was of the order of 1 at% for all the films. From optical absorption spectra data and by using the Tauc method the energy band gap (E{sub g}) was calculated. The Raman spectra only reveal the presence of Si-Si, Ge-Ge, and Si-Ge bonds. Nevertheless, infrared spectra demonstrate the existence of Si-N and Ge-N bonds. The forbidden energy band gap (E{sub g}) as a function of x in the entire range 0 {<=} x {<=} 1 shows two well defined regions: 0 {<=} x {<=} 0.67 and 0.67 {<=} x {<=} 1, due to two different behaviors of the band gap, where for x > 0.67 exists an abruptly change of E{sub g}(x). In this case E{sub g}(x) versus x is different to the variation of E{sub g} in a-Ge{sub 1-x}Si{sub x} and a-Ge{sub 1-x}Si{sub x}:H. This fact can be related to the formation of Ge{sub 3}N{sub 4} and GeSi{sub 2}N{sub 4} when x {<=} 0.67, and to the formation of Si{sub 3}N{sub 4} and GeSi{sub 2}N{sub 4} for 0.67 {<=} x. - Highlights: Black-Right-Pointing-Pointer Nitrogen doped amorphous Ge{sub 1-x}Si{sub x} thin films are grown by electron gun technique. Black-Right-Pointing-Pointer Nitrogen atoms on E{sub g} of the a-Ge{sub 1-x}Si{sub x} films in the 0 Pound-Sign x Pound-Sign 1 range are analyzed. Black-Right-Pointing-Pointer Variation in 0 Pound-Sign x Pound-Sign 1 range shows a warped change of E{sub g} in 1.0 - 3.6 eV range. Black-Right-Pointing-Pointer The change in E{sub g}(x) behavior when x {approx} 0.67 was associated with Ge{sub 2}SiN{sub 4

  4. Characterizing the Superconducting-to-Normal Transition in Mo/Au Transition-Edge Sensor Bilayers

    Science.gov (United States)

    Smith, Stephen J.; Bandler, Simon R.; Brown, Ari. -D.; Chervenak, Jay A.; Finkbeiner, Fred M.; Iyomoto, Naoko; Kelley, Richard L.; Kilbourne, Caroline A.; Porter, Frederick S.; Sadleir, John E.

    2007-01-01

    We are developing arrays of Mo/Au bilayer transition-edge sensors (TES's) for applications in future X-ray astronomy missions such as NASA's Constellation-X. The physical properties of the superconducting-to-normal transition in our TES bilayers, while often reproducible and characterized, are not well understood. The addition of normal metal features on top of the bilayer are found to change the shape and temperature of the transition, and they typically reduce the unexplained 'excess' noise. In order to understand and potentially optimize the properties of the transition, we have been studying the temperature, widths and current dependence of these transitions. We report on the characterization of devices both deposited on silicon substrates and suspended on thin silicon nitride membranes. This includes key device parameters such as the logarithmic resistance sensitivity with temperature alpha, and the logarithmic resistance sensitivity with current beta, of the phase-transition. We investigate alpha and beta as a function of current, both at fixed and varying bias points in the transition. Using Ginzburg-Landau theory for the current dependence of the superconducting transition temperature, we investigate the relationship between alpha and beta and compare our measured and theoretical estimates.

  5. Targeted molecular dynamics reveals overall common conformational changes upon hybrid domain swing-out in beta3 integrins.

    Science.gov (United States)

    Provasi, Davide; Murcia, Marta; Coller, Barry S; Filizola, Marta

    2009-11-01

    The beta3 integrin family members alphaIIbeta3 and alphaVbeta3 signal bidirectionally through long-range allosteric changes, including a transition from a bent unliganded-closed low-affinity state to an extended liganded-open high-affinity state. To obtain an atomic-level description of this transition in an explicit solvent, we carried out targeted molecular dynamics simulations of the headpieces of alphaIIbeta3 and alphaVbeta3 integrins. Although minor differences were observed between these receptors, our results suggest a common transition pathway in which the hybrid domain swing-out is accompanied by conformational changes within the beta3 betaA (I-like) domain that propagate through the alpha7 helix C-terminus, and are followed by the alpha7 helix downward motion and the opening of the beta6-alpha7 loop. Breaking of contact interactions between the beta6-alpha7 loop and the alpha1 helix N-terminus results in helix straightening, internal rearrangements of the specificity determining loop (SDL), movement of the beta1-alpha1 loop toward the metal ion dependent adhesion site (MIDAS), and final changes at the interfaces between the beta3 betaA (I-like) domain and either the hybrid or the alpha beta-propeller domains. Taken together, our results suggest novel testable hypotheses of intradomain and interdomain interactions responsible for beta3 integrin activation.

  6. Absolute Transition Probabilities from the 453.1 keV Level in {sup 183}W

    Energy Technology Data Exchange (ETDEWEB)

    Malmskog, S.G.

    1966-10-15

    The half life of the 453.1 keV level in {sup 183}W has been measured by the delayed coincidence method to 18.4 {+-} 0.5 nsec. This determines twelve absolute M1 and E2 transition probabilities, out of which nine are K-forbidden. All transition probabilities are compared with the single particle estimate. The three K-allowed E2, {delta}K = 2 transition rates to the 1/2{sup -} (510) rotational band are furthermore compared with the Nilsson model. An attempt to give a quantitative explanation of the observed transition rates has been made by including the effects from admixtures into the single particle wave functions.

  7. Band structure and optical transitions in LaFeO3: theory and experiment.

    Science.gov (United States)

    Scafetta, Mark D; Cordi, Adam M; Rondinelli, James M; May, Steven J

    2014-12-17

    The optical absorption properties of LaFeO(3) (LFO) have been calculated using density functional theory and experimentally measured from several high quality epitaxial films using variable angle spectroscopic ellipsometry. We have analyzed the calculated absorption spectrum using different Tauc models and find the model based on a direct-forbidden transition gives the best agreement with the ab initio band gap energies and band dispersions. We have applied this model to the experimental data and determine the band gap of epitaxial LFO to be ∼2.34 eV, with a slight dependence on strain state. This approach has also been used to analyze the higher indirect transition at ∼3.4 eV. Temperature dependent ellipsometry measurements further confirm our theoretical analysis of the nature of the transitions. This works helps to provide a general approach for accurate determination of band gaps and transition energies in complex oxide materials.

  8. Branching ratios for the beta decay of 21Na

    CERN Document Server

    Iacob, V E; Gagliardi, C A; Goodwin, J; Nica, N; Park, H I; Tabacaru, G; Trache, L; Tribble, R; Zhai, Y; Towner, I S

    2006-01-01

    We have measured the beta-decay branching ratio for the transition from 21Na to the first excited state of 21Ne. A recently published test of the standard model, which was based on a measurement of the beta-nu correlation in the decay of 21Na, depended on this branching ratio. However, until now only relatively imprecise (and, in some cases, contradictory) values existed for it. Our new result, 4.74(4)%, reduces but does not remove the reported discrepancy with the standard model.

  9. Exogenous modulation of TGF-{beta}{sub 1} influences TGF-{beta}R-III-associated vascularization during wound healing in irradiated tissue

    Energy Technology Data Exchange (ETDEWEB)

    Wehrhan, F.; Schultze-Mosgau, S. [University of Erlangen-Nuremberg (Germany). Department of Oral and Maxillofacial Surgery; Grabenbauer, G.G.; Roedel, F. [University of Erlangen-Nuremberg (Germany). Department of Radiation Oncology; Amann, K. [University of Erlangen-Nuremberg (Germany). Institute of Pathology

    2004-08-01

    Background and purpose: Following preoperative radiotherapy prior to ablative surgery of squamous epithelial cell carcinomas of the head and neck region, wound-healing disorders occur. Previous experimental studies showed altered expression of transforming growth factor-(TGF-){beta} isoforms following surgery in irradiated graft beds. Altered levels of TGF-{beta}{sub 1} are reported to promote fibrosis and to suppress vascularization during wound healing, whereas expression of TGF-{beta} receptor-III (TGF-{beta}R-III) is associated with vascularization. The aim of the study was to analyze the influence of anti-TGF-{beta}{sub 1} treatment on TGF-{beta}R-III-associated vascularization in the transition area between irradiated graft bed and graft. Material and methods: Wistar rats (male, weight 300-500 g) underwent preoperative irradiation of the head and neck region with 40 Gy (four fractions of 10 Gy each; n=16 animals). A free myocutaneous gracilis flap taken from the groin was then transplanted to the neck in all rats. The time interval between operation and transplantation was 4 weeks. Eight animals received 1 {mu}g anti-TGF-{beta}{sub 1} into the graft bed by intradermal injection on days 1-7 after surgery. On days 3, 7, 14, 28, 56, and 120, skin samples were taken from the transition area between transplant and graft bed and from the graft bed itself. Immunohistochemistry was performed using the ABC-POX method to analyze the TGF-{beta}R-III and E-selection expression. Histomorphometry was performed to analyze the percentage and the area of positively stained vessels. Results: A significantly higher expression of TGF-{beta}R-III was seen in the irradiated and anti-TGF-{beta}{sub 1}-treated graft bed in comparison to the group receiving preoperative irradiation followed by transplantation alone. The percentage of TGF-{beta}R-III positively staining capillaries from the total amount of capillaries in the anti-TGF-{beta}{sub 1}-treated graft bed was higher than in

  10. Simultaneous beta and gamma spectroscopy

    Science.gov (United States)

    Farsoni, Abdollah T.; Hamby, David M.

    2010-03-23

    A phoswich radiation detector for simultaneous spectroscopy of beta rays and gamma rays includes three scintillators with different decay time characteristics. Two of the three scintillators are used for beta detection and the third scintillator is used for gamma detection. A pulse induced by an interaction of radiation with the detector is digitally analyzed to classify the type of event as beta, gamma, or unknown. A pulse is classified as a beta event if the pulse originated from just the first scintillator alone or from just the first and the second scintillator. A pulse from just the third scintillator is recorded as gamma event. Other pulses are rejected as unknown events.

  11. Transitions between beta and gamma rhythms in neural systems

    DEFF Research Database (Denmark)

    Sosnovtseva, Olga; Setsinsky, D; Fausbøll, Anders;

    2002-01-01

    We study the coexistence of different rhythms in a local network of one inhibitory and two excitatory nerve cells for a wide range of the excitatory synapse strength and of the slow K+-channel conductance. The dynamic features of spike trains in the presence of noise are discussed. It is found th...

  12. Phase transitions

    CERN Document Server

    Solé, Ricard V

    2011-01-01

    Phase transitions--changes between different states of organization in a complex system--have long helped to explain physics concepts, such as why water freezes into a solid or boils to become a gas. How might phase transitions shed light on important problems in biological and ecological complex systems? Exploring the origins and implications of sudden changes in nature and society, Phase Transitions examines different dynamical behaviors in a broad range of complex systems. Using a compelling set of examples, from gene networks and ant colonies to human language and the degradation o

  13. Beta section Beta: biogeographical patterns of variation and taxonomy.

    NARCIS (Netherlands)

    Letschert, J.P.W.

    1993-01-01

    In Chapter 1 an account is given of the historical subdivision of the genus Beta and its sections, and the relations of the sections are discussed. Emphasis is given to the taxonomic treatment of wild section Beta by various authors. The Linnaean names B. vulgaris L. and B. maritima L. are lectotypi

  14. Theoretical studies of the atomic transitions in boron-like ions: Mg VIII, Si X and S XII

    Energy Technology Data Exchange (ETDEWEB)

    Nataraj, H S [Non-Accelerator Particle Physics Group, Indian Institute of Astrophysics, Bangalore-34 (India); Sahoo, B K [Max Planck Institute for the Physics of Complex Systems, Noethnitzer Street 38, D-01187 Dresden (Germany); Das, B P [Non-Accelerator Particle Physics Group, Indian Institute of Astrophysics, Bangalore-34 (India); Chaudhuri, R K [Non-Accelerator Particle Physics Group, Indian Institute of Astrophysics, Bangalore-34 (India); Mukherjee, D [Department of Physical Chemistry, Indian Association for Cultivation of Science, Kolkata-700 032 (India)

    2007-08-14

    In this paper, we have carried out the calculations of the weighted oscillator strengths and the transition probabilities for a few low-lying transitions of boron-like ions: Mg VIII, Si X and S XII, which are astrophysically important, particularly in the atmosphere of the solar corona. We have employed an all-order relativistic many-body theory called the relativistic coupled-cluster theory to calculate very precisely these atomic quantities of astrophysical interest. We have reported for the first time the transition probabilities for some forbidden transitions which are unavailable in the literature, either theoretically or experimentally. We also discuss the physical effects associated with these transitions. Our data can be used for the identification of spectral lines arising from the coronal atmospheres of the Sun and Sun-like stars having an extended corona.

  15. Cyclic modular beta-sheets.

    Science.gov (United States)

    Woods, R Jeremy; Brower, Justin O; Castellanos, Elena; Hashemzadeh, Mehrnoosh; Khakshoor, Omid; Russu, Wade A; Nowick, James S

    2007-03-07

    The development of peptide beta-hairpins is problematic, because folding depends on the amino acid sequence and changes to the sequence can significantly decrease folding. Robust beta-hairpins that can tolerate such changes are attractive tools for studying interactions involving protein beta-sheets and developing inhibitors of these interactions. This paper introduces a new class of peptide models of protein beta-sheets that addresses the problem of separating folding from the sequence. These model beta-sheets are macrocyclic peptides that fold in water to present a pentapeptide beta-strand along one edge; the other edge contains the tripeptide beta-strand mimic Hao [JACS 2000, 122, 7654] and two additional amino acids. The pentapeptide and Hao-containing peptide strands are connected by two delta-linked ornithine (deltaOrn) turns [JACS 2003, 125, 876]. Each deltaOrn turn contains a free alpha-amino group that permits the linking of individual modules to form divalent beta-sheets. These "cyclic modular beta-sheets" are synthesized by standard solid-phase peptide synthesis of a linear precursor followed by solution-phase cyclization. Eight cyclic modular beta-sheets 1a-1h containing sequences based on beta-amyloid and macrophage inflammatory protein 2 were synthesized and characterized by 1H NMR. Linked cyclic modular beta-sheet 2, which contains two modules of 1b, was also synthesized and characterized. 1H NMR studies show downfield alpha-proton chemical shifts, deltaOrn delta-proton magnetic anisotropy, and NOE cross-peaks that establish all compounds but 1c and 1g to be moderately or well folded into a conformation that resembles a beta-sheet. Pulsed-field gradient NMR diffusion experiments show little or no self-association at low (

  16. Beta-delayed neutron decay of {sup 33}Na

    Energy Technology Data Exchange (ETDEWEB)

    Radivojevic, Z. E-mail: zoran.radivojevic@phys.jyu.fi; Baumann, P.; Caurier, E.; Cederkaell, J.; Courtin, S.; Dessagne, Ph.; Jokinen, A.; Knipper, A.; Scornet, G.L.G. Le; Lyapin, V.; Miehe, Ch.; Nowacki, F.; Nummela, S.; Oinonen, M.; Poirier, E.; Ramdhane, M.; Trzaska, W.H.; Walter, G.; Aeystoe, J

    2002-04-01

    Beta-delayed neutron decay of {sup 33}Na has been studied using the on-line mass separator ISOLDE. The delayed neutron spectra were measured by time-of-flight technique using fast scintillators. Two main neutron groups at 800(60) and 1020(80) keV were assigned to the {sup 33}Na decay, showing evidence for strong feeding of states at about 4 MeV in {sup 33}Mg. By simultaneous {beta}-{gamma}-n counting the delayed neutron emission probabilities P{sub 1n}=47(6)% and P{sub 2n}=13(3)% were determined. The half-life value for {sup 33}Na, T{sub 1/2}=8.0(3) ms, was measured by three different techniques, one employing identifying gamma transitions and two employing beta and neutron counting.

  17. Study of $\\beta$-delayed neutron decay of $^{8}$He

    CERN Multimedia

    The goal of the present proposal is to study $\\beta$-delayed neutron decay branch of $^{8}$He. The energy spectra of the emitted neutrons will be measured in the energy range of 0.1 – 6 MeV using the VANDLE spectrometer. Using coincident $\\gamma$-ray measurement, components of the spectrum corresponding to transitions to the ground- and first- excited states of $^{7}$Li will be disentangled. The new data will allow us to get a more complete picture of the $\\beta$-decay of $^{8}$He and to clarify the discrepancy between the B(GT) distributions derived from the $\\beta$-decay and $^{8}$He(p, n)$^{8}$Li reaction studies.

  18. Beta Decay of 101Sn

    Energy Technology Data Exchange (ETDEWEB)

    Kavatsyuk, O. [Gesellschaft fur Schwerionenforschung (GSI), Germany; Mazzocchi, C. [Gesellschaft fur Schwerionenforschung (GSI), Germany; Janas, Z. [University of Warsaw; Banu, A. [Gesellschaft fur Schwerionenforschung (GSI), Germany; Batist, L. [St. Petersburg Nuclear Physics Institute; Becker, F. [Gesellschaft fur Schwerionenforschung (GSI), Germany; Blazhev, A. [Gesellschaft fur Schwerionenforschung (GSI), Germany; Bruchle, W. [Gesellschaft fur Schwerionenforschung (GSI), Germany; Doring, J. [Gesellschaft fur Schwerionenforschung (GSI), Germany; Faestermann, T. [Technische Universitat Munchen; Gorska, M. [Gesellschaft fur Schwerionenforschung (GSI), Germany; Grawe, H. [GSI-Hemholtzzentrum fur Schwerionenforschung, Darmstadt, Germany; Jungclaus, A. [Instituto Estructura de la Materia, Madrid; Karny, M. [University of Warsaw; Kavatsyuk, M. [Gesellschaft fur Schwerionenforschung (GSI), Germany; Klepper, O. [Gesellschaft fur Schwerionenforschung (GSI), Germany; Kirchner, R. [Gesellschaft fur Schwerionenforschung (GSI), Germany; La Commara, M. [Universita Federico II and INFN Napoli; Miernik, K. [University of Warsaw; Mukha, I. [Gesellschaft fur Schwerionenforschung (GSI), Germany; Plettner, C. [Gesellschaft fur Schwerionenforschung (GSI), Germany; Plochocki, A. [University of Warsaw; Roeckl, E. [Gesellschaft fur Schwerionenforschung (GSI), Germany; Romoli, M. [Universita Federico II and INFN Napoli; Rykaczewski, Krzysztof Piotr [ORNL; Schadel, M. [Gesellschaft fur Schwerionenforschung (GSI), Germany; Schmidt, K. [Continental Teves AG & Co., Frankfurt am Main, Germany; Schwengner, R. [Forschungszentrum Rossendorf, Dresden, Germany; Zylicz, J. [University of Warsaw

    2007-01-01

    The {beta} decay of the very neutron-deficient isotope 101Sn was studied at the GSI on-line mass separator using silicon detectors for recording charged particles and germanium detectors for {gamma}-ray spectroscopy. Based on the {beta}-delayed proton data the production cross-section of 101Sn in the 50Cr + 58Ni fusion-evaporation reaction was determined to be about 60nb. The half-life of 101Sn was measured to be 1.9(3)s. For the first time {beta}-delayed {gamma}-rays of 101Sn were tentatively identified, yielding weak evidence for a cascade of 352 and 1065keV transitions in 101In. The results for the 101Sn decay as well as those from previous work on the 103Sn decay are discussed by comparing them to predictions obtained from shell model calculations employing a new interaction in the 88Sr to 132Sn model space.

  19. Noncovalent Interaction Energies in Covalent Complexes: TEM-1 beta-Lactamase and beta-Lactams

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Xiaojun; Minasov, George; Shoichet, Brian K. (NWU)

    2010-03-08

    The class A {beta}-lactamase TEM-1 is a key bacterial resistance enzyme against {beta}-lactam antibiotics, but little is known about the energetic bases for complementarity between TEM-1 and its inhibitors. Most inhibitors form a covalent adduct with the catalytic Ser70, making the measurement of equilibriumconstants, and hence interaction energies, technically difficult. This study evaluates noncovalent interactions withincovalent complexes by examining the differential stability of TEM-1 and its inhibitor adducts. The thermal denaturation of TEM-1 follows a two-state, reversible model with a melting temperature (T{sub m}) of 51.6 C and a van't Hoff enthalpy of unfolding ({Delta}H{sub VH}) of 146.2 kcal/mol at pH 7.0. The stability of the enzyme changes on forming an inhibitor adduct. As expected, some inhibitors stabilize TEM-1; transition-state analogues increase the T{sub m} by up to 3.7 C(1.7 kcal/mol). Surprisingly, all {beta}-lactam covalent acyl-enzyme complexes tested destabilize TEM-1 significantly relative to the apoenzyme. For instance, the clinically used inhibitor clavulanic acid and the {beta}-lactamase-resistant {beta}-lactams moxalactam and imipenem destabilize TEM-1 by over 2.6 C (1.2 kcal/mol) in their covalent adducts. Based on the structure of the TEM-1/imipenem complex (Maveyraud et al., J Am Chem Soc 1998;120:9748-52), destabilization by moxalactam and imipenem is thought to be caused by a steric clash between the side-chain of Asn132 and the 6(7)-{alpha} group of these {beta}-lactams. To test this hypothesis, the mutant enzyme N132A was made. In contrast with wild-type, the covalent complexes between N132A and both imipenem and moxalactam stabilize the enzyme, consistent with the hypothesis. To investigate the structural bases of this dramatic change instability, the structure of N132A/imipenem was determined by X-ray crystallography. In the complex with N132A, imipenemadopts a very different conformation from that observed in the wild

  20. PGC-1alpha and PGC-1beta have both similar and distinct effects on myofiber switching toward an oxidative phenotype

    DEFF Research Database (Denmark)

    Mortensen, Ole Hartvig; Frandsen, Lis; Schjerling, Peter

    2006-01-01

    Peroxisome proliferator-activated receptor-gamma coactivator-1alpha and -1beta (PGC-1alpha and PGC-1beta) were overexpressed by adenovirus-mediated gene transfer in cultures of primary rat skeletal muscle cells derived from neonatal myoblasts. Effects on muscle fiber type transition and metabolism...

  1. SUSY and the Electroweak Phase Transition

    CERN Document Server

    Farrar, Glennys R S; Farrar, Glennys R.; Losada, Marta

    1996-01-01

    We analyze the effective 3 dimensional theory previously constructed for the MSSM and multi-Higgs models to determine the regions of parameter space in which the electroweak phase transition is sufficiently strong for a $B+L$ asymmetry to survive in the low temperature phase. We find that the inclusion of all supersymmetric scalars and all 1-loop corrections has the effect of enhancing the strength of the phase transition. Without a light stop or extension of the MSSM the phase transition is sufficiently first order only if the lightest Higgs mass $M_{h}\\lsi 70$ GeV and $tan\\beta\\lsi 1.75$.

  2. The best-beta CAPM

    NARCIS (Netherlands)

    Zou, L.

    2006-01-01

    The issue of 'best-beta' arises as soon as potential errors in the Sharpe-Lintner-Black capital asset pricing model (CAPM) are acknowledged. By incorporating a target variable into the investor preferences, this study derives a best-beta CAPM (BCAPM) that maintains the CAPM's theoretical appeal and

  3. Beta decay of Cu-56

    NARCIS (Netherlands)

    Borcea, R; Aysto, J; Caurier, E; Dendooven, P; Doring, J; Gierlik, M; Gorska, M; Grawe, H; Hellstrom, M; Janas, Z; Jokinen, A; Karny, M; Kirchner, R; La Commara, M; Langanke, K; Martinez-Pinedo, G; Mayet, P; Nieminen, A; Nowacki, F; Penttila, H; Plochocki, A; Rejmund, M; Roeckl, E; Schlegel, C; Schmidt, K; Schwengner, R; Sawicka, M

    2001-01-01

    The proton-rich isotope Cu-56 was produced at the GSI On-Line Mass Separator by means of the Si-28(S-32, p3n) fusion-evaporation reaction. Its beta -decay properties were studied by detecting beta -delayed gamma rays and protons. A half-Life of 93 +/- 3 ms was determined for Cu-56. Compared to the p

  4. Integration of BETA with Eclipse

    DEFF Research Database (Denmark)

    Andersen, Peter; Madsen, Ole Lehrmann; Enevoldsen, Mads Brøgger

    2004-01-01

    This paper presents language interoperability issues appearing in order to implement support for the BETA language in the Java-based Eclipse integrated development environment. One of the challenges is to implement plug-ins in BETA and be able to load them in Eclipse. In order to do this, some form...

  5. Beta cell adaptation in pregnancy

    DEFF Research Database (Denmark)

    Nielsen, Jens Høiriis

    2016-01-01

    Pregnancy is associated with a compensatory increase in beta cell mass. It is well established that somatolactogenic hormones contribute to the expansion both indirectly by their insulin antagonistic effects and directly by their mitogenic effects on the beta cells via receptors for prolactin and...

  6. Measurements of sin 2 $\\beta$

    CERN Document Server

    Tricomi, A

    2000-01-01

    A review of the most recent measurements of the CP violating parameter sin 2 beta from LEP and CDF is reported. These yield an average value of sin 2 beta =0.91+or-0.35, giving a confidence level that CP violation in the B system has been observed of almost 99%. (10 refs).

  7. Beta-hemolytic streptococcal bacteremia

    DEFF Research Database (Denmark)

    Nielsen, Hans Ulrik; Kolmos, Hans Jørn; Frimodt-Møller, Niels

    2002-01-01

    Bacteremia with beta-hemolytic Streptococci groups A, B, C and G has a mortality rate of approximately 20%. In this study we analyzed the association of various patient risk factors with mortality. Records from 241 patients with beta-hemolytic streptococcal bacteremia were reviewed with particular...

  8. Beta Function and Anomalous Dimensions

    DEFF Research Database (Denmark)

    Pica, Claudio; Sannino, Francesco

    2011-01-01

    We demonstrate that it is possible to determine the coefficients of an all-order beta function linear in the anomalous dimensions using as data the two-loop coefficients together with the first one of the anomalous dimensions which are universal. The beta function allows to determine the anomalou...

  9. RAVEN Beta Release

    Energy Technology Data Exchange (ETDEWEB)

    Rabiti, Cristian [Idaho National Lab. (INL), Idaho Falls, ID (United States); Alfonsi, Andrea [Idaho National Lab. (INL), Idaho Falls, ID (United States); Cogliati, Joshua Joseph [Idaho National Lab. (INL), Idaho Falls, ID (United States); Mandelli, Diego [Idaho National Lab. (INL), Idaho Falls, ID (United States); Kinoshita, Robert Arthur [Idaho National Lab. (INL), Idaho Falls, ID (United States); Wang, Congjian [Idaho National Lab. (INL), Idaho Falls, ID (United States); Maljovec, Daniel Patrick [Idaho National Lab. (INL), Idaho Falls, ID (United States); Talbot, Paul William [Idaho National Lab. (INL), Idaho Falls, ID (United States)

    2016-02-01

    This documents the release of the Risk Analysis Virtual Environment (RAVEN) code. A description of the RAVEN code is provided, and discussion of the release process for the M2LW-16IN0704045 milestone. The RAVEN code is a generic software framework to perform parametric and probabilistic analysis based on the response of complex system codes. RAVEN is capable of investigating the system response as well as the input space using Monte Carlo, Grid, or Latin Hyper Cube sampling schemes, but its strength is focused toward system feature discovery, such as limit surfaces, separating regions of the input space leading to system failure, using dynamic supervised learning techniques. RAVEN has now increased in maturity enough for the Beta 1.0 release.

  10. Beta systems error analysis

    Science.gov (United States)

    1984-01-01

    The atmospheric backscatter coefficient, beta, measured with an airborne CO Laser Doppler Velocimeter (LDV) system operating in a continuous wave, focussed model is discussed. The Single Particle Mode (SPM) algorithm, was developed from concept through analysis of an extensive amount of data obtained with the system on board a NASA aircraft. The SPM algorithm is intended to be employed in situations where one particle at a time appears in the sensitive volume of the LDV. In addition to giving the backscatter coefficient, the SPM algorithm also produces as intermediate results the aerosol density and the aerosol backscatter cross section distribution. A second method, which measures only the atmospheric backscatter coefficient, is called the Volume Mode (VM) and was simultaneously employed. The results of these two methods differed by slightly less than an order of magnitude. The measurement uncertainties or other errors in the results of the two methods are examined.

  11. Beta-decay half-lives of new neutron-rich isotopes of Re, Os and Ir approaching the r-process path near N = 126

    Energy Technology Data Exchange (ETDEWEB)

    Kurtukian-Nieto, T.; Benlliure, J.; Casarejos, E.; Fernandez-Ordonez, M.; Pereira, J. [Universidade de Santiago de Compostela, Departamento de Fisica de Particulas, Santiago de Compostela (Spain); Schmidt, K.H.; Becker, F.; Borzov, I.N.; Henzlova, D.; Yordanov, O. [GSI-Helmholtzzentrum fuer Schwerionenforschung GmbH, Darmstadt (Germany); Audouin, L. [Institut de Physique Nucleaire, Orsay (France); Blank, B.; Giovinazzo, J.; Jurado, B. [CNRS/IN2P3-Universite de Bordeaux, Centre d' Etudes Nucleaires de Bordeaux-Gradignan, Gradignan (France); Farget, F. [GANIL, CAEN Cedex 5 (France); Langanke, K.; Martinez-Pinedo, G. [GSI-Helmholtzzentrum fuer Schwerionenforschung GmbH, Darmstadt (Germany); TU Darmstadt, Institut fuer Kernphysik, Darmstadt (Germany)

    2014-09-15

    Heavy neutron-rich nuclei close to N = 126 were produced by fragmentation of a 1A GeV {sup 208}Pb beam at the FRS at GSI. The β-decay half-lives of 7 nuclides have been determined using a novel numerical analysis method. The half-lives of {sup 202,199}Ir, {sup 200,199}Os and {sup 196}Re are reported for the first time. The comparison of the data with model calculations provides indications on the importance of first-forbidden transitions on the β-decay of nuclei around N = 126 and Z < 82. (orig.)

  12. Hb Santa Clara (beta 97His-->Asn), a human haemoglobin variant: functional characterization and structure modelling.

    Science.gov (United States)

    De Rosa, Maria Cristina; Carelli Alinovi, Cristiana; Schininà, Maria Eugenia; Clementi, Maria Elisabetta; Amato, Antonio; Cappabianca, Maria Pia; Pezzotti, Michela; Giardina, Bruno

    2007-10-01

    This study examines the functional and structural effects of amino acid substitution at alpha(1)beta(2) interface of Hb Santa Clara (beta 97His-->Asn). We have characterized the variation by a combination of electrospray ionisation mass spectrometry and DNA sequence analysis followed by oxygen-binding experiments. Functional studies outlined an increased oxygen affinity, reduced effect of organic phosphates and a reduced Bohr effect with respect to HbA. In view of the primary role of this interface in the cooperative quaternary transition from the T to R conformational state, a theoretical three-dimensional model of Hb Santa Clara was generated. Structural investigations suggest that replacement of Asn for His beta 97 results in a significant stabilization of the high affinity R-state of the haemoglobin molecule with respect to the low affinity T-state. The role of beta FG4 position has been further examined by computational models of known beta FG4 variants, namely Hb Malmö (beta 97His-->Gln), Hb Wood (beta 97His-->Leu), Hb Nagoya (beta 97His-->Pro) and Hb Moriguchi (beta 97His-->Tyr). These findings demonstrate that, among the various residues at the alpha(1)beta(2) (and alpha(2)beta(1)) intersubunit interface, His beta FG4 contributes significantly to the quaternary constraints that are responsible for the low oxygen affinity of human deoxyhaemoglobin.

  13. Some aspects of pressure-induced omega -> beta transformation in group IVB elements

    CERN Document Server

    Joshi, K D; Gupta, S C; Sikka, S K

    2002-01-01

    The omega (hexagonal) to beta (bcc) transformation in Zr and Hf occurs at 30 and 71 GPa under static pressures. This transition has not been found in Ti up to 87 GPa. On the basis of full-potential linearized augmented plane wave calculations aided with thermal and entropy correction we predict an omega -> beta transition in Ti at around 102 GPa along the 300 K isotherm. In addition to this, we calculate the omega -> beta transitions in Zr and Hf at around 27 and 65 GPa respectively, which are in excellent agreement with the experimental values. The omega -> beta transition pressures, 102, 27 and 65 GPa for Ti, Zr and Hf respectively, do not follow the trend implied by the principle of corresponding states. We have analysed the causes for this anomalous trend. We observe that the omega -> beta transition depends on how the increased d-population due to s-d transfer under pressure is distributed in the different d-substates. For example, at ambient conditions, the bcc phase is unstable and the difference betwe...

  14. Decreased beta-band activity is correlated with disambiguation of hidden figures.

    Science.gov (United States)

    Minami, Tetsuto; Noritake, Yosuke; Nakauchi, Shigeki

    2014-04-01

    Insight is commonly described as sudden comprehension, sometimes called an "Aha! moment." In everyday life, we apply the process of insight to problems that are difficult to solve at first glance or that we perceive as ambiguous; however the brain dynamics underlying the disambiguation process remains elusive. Beta-band oscillatory brain activity has been hypothesized to reflect the transition of cognitive states. To elucidate the neural mechanism of insight, we recorded electroencephalograms while subjects were presented with hidden figures followed by unambiguous, gray images. We identified oscillatory activity to detect temporal changes, and compared brain activity that occurred during a perceptual transition with activity that occurred when no perceptual transition occurred. Statistical comparison confirmed stronger beta-power decrease during perceptual transition. Source analysis indicated that the beta-power decrease was around the parietal-posterior regions, mainly in the precuneus. We propose that beta-band desynchronization in the parietal-posterior regions reflects the disambiguation process, and our findings provide additional support for the theory that beta-band activity is related to the transition of cognitive state.

  15. [Serum beta 2 microglobulin (beta 2M) following renal transplantation].

    Science.gov (United States)

    Pacheco-Silva, A; Nishida, S K; Silva, M S; Ramos, O L; Azjen, H; Pereira, A B

    1994-01-01

    Although there was an important improvement in graft and patient survival the last 10 years, graft rejection continues to be a major barrier to the success of renal transplantation. Identification of a laboratory test that could help to diagnose graft rejection would facilitate the management of renal transplanted patients. PURPOSE--To evaluate the utility of monitoring serum beta 2M in recently transplanted patients. METHODS--We daily determined serum beta 2M levels in 20 receptors of renal grafts (10 from living related and 10 from cadaveric donors) and compared them to their clinical and laboratory evolution. RESULTS--Eight patients who presented immediate good renal function following grafting and did not have rejection had a mean serum beta 2M of 3.7 mg/L on the 4th day post transplant. The sensitivity of the test for the diagnosis of acute rejection was 87.5%, but the specificity was only 46%. Patients who presented acute tubular necrosis (ATN) without rejection had a progressive decrease in their serum levels of beta 2M, while their serum creatinine changed as they were dialyzed. In contrast, patients with ATN and concomitance of acute rejection or CSA nephrotoxicity presented elevated beta 2M and creatinine serum levels. CONCLUSION--Daily monitoring of serum beta 2M does not improve the ability to diagnose acute rejection in patients with good renal function. However, serum beta 2M levels seemed to be useful in diagnosing acute rejection or CSA nephrotoxicity in patients with ATN.

  16. Neutrinoless double beta decay studied with configuration mixing methods

    CERN Document Server

    Rodriguez, Tomas R

    2010-01-01

    We study neutrinoless double beta decay of several isotopes with state-of-the-art beyond self-consistent mean field methods to compute the nuclear matrix elements (NME). Generating coordinate method with particle number and angular momentum projection (GCM+PNAMP) is used for finding mother and granddaughter states and evaluating transition operators between different nuclei. We analyze explicitly the role of the deformation, pairing and configuration mixing in the evaluation of the NME.

  17. Beta decay of 252Cf on the way to scission from the exit point

    CERN Document Server

    Pomorski, K; Quentin, P

    2015-01-01

    Upon increasing significantly the nuclear elongation, the beta-decay energy grows. This paper investigates within a simple yet partly microscopic approach, the transition rate of the beta decay of the 252Cf nucleus on the way to scission from the exit point for a spontaneous fission process. A rather crude classical approximation is made for the corresponding damped collective motion assumed to be one dimensional. Given these assumptions, we only aim in this paper at providing the order of magnitudes of such a phenomenon. At each deformation the energy available for beta decay, is determined from such a dynamical treatment. Then, for a given elongation, transition rates for the allowed (Fermi) beta decay are calculated from pair correlated wave functions obtained within a macroscopic-microscopic approach and then integrated over the time corresponding to the whole descent from exit to scission. The results are presented as a function of the damping factor (inverse of the characteristic damping time) in use in...

  18. Long-Term Stability of Underground Operated CZT Detectors Based on the Analysis of Intrinsic $^{113}$Cd \\beta$^{-}$-Decay

    CERN Document Server

    Ebert, J; Gehre, D; Hagner, C; Heidrich, N; Klingenberg, R; Kroeninger, K; Nitsch, C; Oldorf, C; Quante, T; Rajek, S; Rebber, H; Rohatsch, K; Tebruegge, J; Temminghoff, R; Theinert, R; Timm, J; Wonsak, B; Zatschler, S; Zuber, K

    2015-01-01

    The COBRA collaboration operates a demonstrator setup at the underground facility LNGS (Laboratori Nazionali del Gran Sasso, located in Italy) to prove the technological capabilities of this concept for the search for neutrinoless double beta-decay. The setup consists of 64 $(1\\times\\!1\\times\\!1)$ cm$^{3}$ CZT detectors in CPG configuration. One purpose of this demonstrator is to test if reliable long-term operation of CZT-CPG detectors in such a setup is possible. The demonstrator has been operated under ultra low-background conditions since more than three years and collected data corresponding to an exposure of 218 kg$\\cdot$days. The presented study focuses on the long-term stability of CZT detectors by analyzing the intrinsic, fourfold forbidden non-unique $^{113}$Cd single beta-decay. It can be shown that CZT detectors can be operated stably for long periods of time and that the $^{113}$Cd single beta-decay can be used as an internal monitor of the detector performance during the runtime of the experimen...

  19. Instabilities near the QCD phase transition in the holographic models

    CERN Document Server

    Gursoy, Umut; Shuryak, Edward

    2013-01-01

    The paper discusses phenomena close to the critical QCD temperature, using the holographic model. One issue studied is the overcooled high-T phase, in which we calculate quasi normal sound modes. We do not find instabilities associated with other first order phase transitions, but nevertheless observe drastic changes in sound propagation/dissipation. The rest of the paper considers a cluster of the high-T phase in the UV in coexistence with the low-T phase, in a simplified ansatz in which the wall separating them is positioned only in the holographic coordinate. This allows to find the force on the wall and classical motion of the cluster. When classical motion is forbidden, we evaluate tunneling probability through the remaining barrier.

  20. Experiments on double beta decay

    Energy Technology Data Exchange (ETDEWEB)

    Busto, J. [Neuchatel Univ. (Switzerland). Inst. de Physique

    1996-11-01

    The Double Beta Decay, and especially ({beta}{beta}){sub 0{nu}} mode, is an excellent test of Standard Model as well as of neutrino physics. From experimental point of view, a very large number of different techniques are or have been used increasing the sensitivity of this experiments quite a lot (the factor of 10{sup 4} in the last 20 years). In future, in spite of several difficulties, the sensitivity would be increased further, keeping the interest of this very important process. (author) 4 figs., 5 tabs., 21 refs.

  1. Dosimetry of {beta} extensive sources; Dosimetria de fuentes {beta} extensas

    Energy Technology Data Exchange (ETDEWEB)

    Rojas C, E.L.; Lallena R, A.M. [Departamento de Fisica Moderna, Universidad de Granada, E-18071 Granada (Spain)

    2002-07-01

    In this work, we have been studied, making use of the Penelope Monte Carlo simulation code, the dosimetry of {beta} extensive sources in situations of spherical geometry including interfaces. These configurations are of interest in the treatment of the called cranealfaringyomes of some synovia leisure of knee and other problems of interest in medical physics. Therefore, its application can be extended toward problems of another areas with similar geometric situation and beta sources. (Author)

  2. Efficient inhibition of the Alzheimer's disease beta-secretase by membrane targeting.

    Science.gov (United States)

    Rajendran, Lawrence; Schneider, Anja; Schlechtingen, Georg; Weidlich, Sebastian; Ries, Jonas; Braxmeier, Tobias; Schwille, Petra; Schulz, Jörg B; Schroeder, Cornelia; Simons, Mikael; Jennings, Gary; Knölker, Hans-Joachim; Simons, Kai

    2008-04-25

    beta-Secretase plays a critical role in beta-amyloid formation and thus provides a therapeutic target for Alzheimer's disease. Inhibitor design has usually focused on active-site binding, neglecting the subcellular localization of active enzyme. We have addressed this issue by synthesizing a membrane-anchored version of a beta-secretase transition-state inhibitor by linking it to a sterol moiety. Thus, we targeted the inhibitor to active beta-secretase found in endosomes and also reduced the dimensionality of the inhibitor, increasing its local membrane concentration. This inhibitor reduced enzyme activity much more efficiently than did the free inhibitor in cultured cells and in vivo. In addition to effectively targeting beta-secretase, this strategy could also be used in designing potent drugs against other membrane protein targets.

  3. Effect of beta-cyclodextrin nanocavity confinement on the photophysics of robinetin.

    Science.gov (United States)

    Banerjee, Anwesha; Basu, Kaushik; Sengupta, Pradeep K

    2007-12-14

    We have studied the confinement of robinetin, a therapeutically active plant flavonol, in cyclodextrin (CDx) nanocavities, using steady state and time resolved fluorescence spectroscopy. Enhanced tautomer emission (arising from excited state intramolecular proton transfer (ESIPT)) as well as dramatically blue shifted (approximately 10 nm in beta-CDx and approximately 33 nm in SHP beta-CDx) normal fluorescence observed upon addition of the beta-CDxs indicate that robinetin readily enters the doughnut-shaped hydrophobic cavity of beta-CDx where the chromone moiety is well shielded from external hydrogen bonding perturbations. Detailed analyses of the fluorescence data (emission profile, anisotropy, decay times) indicate that robinetin forms 1:1 inclusion complexes with both natural and chemically modified beta-cyclodextrins (beta-CDx and SHP beta-CDx) with affinity constant values K=195+/-17 M(-1) and 1055+/-48 M(-1) respectively, indicating the prospective utility of SHP beta-CDx in particular as an effective drug carrier. Unlike beta-CDxs, alpha-CDxs do not form inclusion complexes with robinetin. To further characterize the robinetin/beta-CDxs complexes, circular dichroism (CD) spectroscopic studies have been performed, which reveal that incorporation of robinetin molecules in the chiral environment of the beta-CDxs strongly affects the electronic transitions of robinetin leading to the occurrence of positive induced circular dichroism (ICD) bands in the near ultra-violet (UV) region. Molecular mechanics calculations show that the inclusion complex with the chromone ring inserted into the beta-CDx cavity is most favorable, in agreement with our spectroscopic data.

  4. High-pressure behavior of beta-Ga2O3 nanocrystals

    DEFF Research Database (Denmark)

    Wang, H.; He, Y.; Chen, W.

    2010-01-01

    Freestanding nanocrystalline beta-Ga2O3 particles with an average grain size of 14 nm prepared by chemical method was investigated by angle-dispersive synchrotron x-ray diffraction in diamond-anvil cell up to 64.9 GPa at ambient temperature. The evolution of x-ray diffraction patterns indicated...... that nanocrystalline monoclinic beta-Ga2O3 underwent a phase transition to rhombohedral alpha-Ga2O3. It was found that beta- to alpha-Ga2O3 transition began at about 13.6-16.4 GPa, and extended up to 39.2 GPa. At the highest pressure used, only alpha-Ga2O3 was present, which remained after pressure release. A Birch......-Murnaghan fit to the P-V data yielded a zero-pressure bulk modulus at fixed B-0(')=4: B-0=228(9) GPa and B-0=333(19) GPa for beta-Ga2O3 and alpha-Ga2O3 phases, respectively. We compared our results with bulk beta-Ga2O3, and concluded that the phase-transition pressure and bulk modulus of nanocrystalline beta...

  5. Tessellations & Transitions.

    Science.gov (United States)

    Cassidy, Joan

    1998-01-01

    Describes two sixth-grade lessons on the work of M. C. Escher: (1) the first lesson instructs students on tessellations, or tiles that interlock in a repeated pattern; (2) the second lesson explores Escher's drawings of transitions from two- to three-dimensional space. (DSK)

  6. Presidential Transitions

    Science.gov (United States)

    2006-06-09

    Morton Mintz and Stuart Auerbach, “Ford Solicits Suggestions on No. 2 Man,” Washington Post, Aug. 11, 1974, p. A1. 64 Fred Austin, “Ford Begins Move...representatives of the federal departments and agencies to ensure a smooth transition. Management and organizational issues should be CRS-23 105 Carl Brauer

  7. New Calculations for Phase Space Factors Involved in Double Beta Decay

    CERN Document Server

    Stoica, Sabin

    2013-01-01

    We present new results for the phase space factors involved in double beta decay for beta-beta- transitions to ground states and excited 0+1 states, for isotopes of experimental interest. The Coulomb distortion of the electron wave functions is treated by solving numerically the Dirac equation with inclusion of the finite nuclear size and electron screening effects, and using a Coulomb potential derived from a realistic proton density distribution in the daughter nucleus. Our results are compared with other results from literature, obtained in different approximations, and possible causes that can give differences are discussed.

  8. Beta-2 Microglobulin Tumor Marker

    Science.gov (United States)

    ... services. Advertising & Sponsorship: Policy | Opportunities Beta-2 Microglobulin Tumor Marker Share this page: Was this page helpful? Also ... Microglobulin, Serum, Urine, or CSF Related tests: Albumin , Tumor Markers , CSF Analysis All content on Lab Tests Online ...

  9. Questions Students Ask: Beta Decay.

    Science.gov (United States)

    Koss, Jordan; Hartt, Kenneth

    1988-01-01

    Answers a student's question about the emission of a positron from a nucleus. Discusses the problem from the aspects of the uncertainty principle, beta decay, the Fermi Theory, and modern physics. (YP)

  10. Deconfinement and the Hagedorn transition in string theory.

    Science.gov (United States)

    Chaudhuri, S

    2001-03-05

    We introduce a new definition of the thermal partition function in string theory. With this new definition, the thermal partition functions of all of the string theories obey thermal duality relations with self-dual Hagedorn temperature beta(2)(H) = 4pi(2)alpha('). A beta-->beta(2)(H)/beta transformation maps the type I theory into a new string theory (type I) with thermal D p-branes, spatial hypersurfaces supporting a p-dimensional finite temperature non-Abelian Higgs-gauge theory for p< or =9. We demonstrate a continuous phase transition in the behavior of the static heavy quark-antiquark potential for small separations r(2)(*)transitioning through a precise inverse power law at a critical temperature T(D) = T(H)r(*)/(2alpha('))(1/2)pi.

  11. Some aspects of pressure-induced {omega} {yields} {beta} transformation in group IVB elements

    Energy Technology Data Exchange (ETDEWEB)

    Joshi, K D; Jyoti, G; Gupta, Satish C; Sikka, S K [High Pressure Physics Division, Bhabha Atomic Research Centre, Mumbai 400085 (India)

    2002-11-11

    The {omega} (hexagonal) to {beta} (bcc) transformation in Zr and Hf occurs at 30 and 71 GPa under static pressures. This transition has not been found in Ti up to 87 GPa. On the basis of full-potential linearized augmented plane wave calculations aided with thermal and entropy correction we predict an {omega} {yields} {beta} transition in Ti at around 102 GPa along the 300 K isotherm. In addition to this, we calculate the {omega} {yields} {beta} transitions in Zr and Hf at around 27 and 65 GPa respectively, which are in excellent agreement with the experimental values. The {omega} {yields} {beta} transition pressures, 102, 27 and 65 GPa for Ti, Zr and Hf respectively, do not follow the trend implied by the principle of corresponding states. We have analysed the causes for this anomalous trend. We observe that the {omega} {yields} {beta} transition depends on how the increased d-population due to s-d transfer under pressure is distributed in the different d-substates. For example, at ambient conditions, the bcc phase is unstable and the difference between the average charges in the bcc stabilizing d-t{sub 2g} state and the destabilizing d-e{sub g} state are 0.008, 0.082 and 0.013 for Ti, Zr and Hf respectively. Compression increases this difference and stabilizes the bcc structure when it becomes about 0.1. The charge transfer needed for stabilizing the {beta} structure is highest for Ti followed by Hf and then Zr, in line with the trend in transition pressures.

  12. Beta Function and Anomalous Dimensions

    CERN Document Server

    Pica, Claudio

    2010-01-01

    We demonstrate that it is possible to determine the coefficients of an all-order beta function linear in the anomalous dimensions using as data the two-loop coefficients together with the first one of the anomalous dimensions which are universal. The beta function allows to determine the anomalous dimension of the fermion masses at the infrared fixed point, and the resulting values compare well with the lattice determinations.

  13. Expression of transforming growth factor-beta (TGF-beta) receptors, TGF-beta 1 and TGF-beta 2 production and autocrine growth control in osteosarcoma cells.

    Science.gov (United States)

    Kloen, P; Jennings, C L; Gebhardt, M C; Springfield, D S; Mankin, H J

    1994-08-01

    Transforming growth factor-beta (TGF-beta) is a polypeptide with multiple physiological functions. Isoforms of this growth factor have important roles in control of the cell cycle, in regulation of cell-cell interactions and in growth and development. Malignant transformation has been shown to be associated with increased expression of TGF-beta. Since bone is the largest storage site and producer of TGF-beta, we speculated on the existence of an autocrine mechanism in osteosarcoma, a malignant bone tumor. Expression of TGF-beta cell surface receptors, effects on growth of TGF-beta and TGF-beta antibodies and production of 2 TGF-beta isoforms were studied in a panel of 7 osteosarcoma cell lines. In contrast to most previous reports on the effects of TGF-beta on osteosarcoma cell growth, we found a mitogenic effect of TGF-beta 1 in 4 of 7 osteosarcoma cell lines. Receptor profiles for TGF-beta were aberrant in 5 of the 7 cell lines tested, and production of TGF-beta 1 and TGF-beta 2 varied among cell lines. Addition of anti-TGF-beta antagonized the effects of endogenous TGF-beta. Our results suggest a potential role of TGF-beta in autocrine growth control of osteosarcoma cells.

  14. Polypeptides having beta-glucosidase activity, beta-xylosidase activity, or beta-glucosidase and beta-xylosidase activity and polynucleotides encoding same

    Energy Technology Data Exchange (ETDEWEB)

    Morant, Marc

    2017-02-07

    The present invention relates to isolated polypeptides having beta-glucosidase activity, beta-xylosidase activity, or beta-glucosidase and beta-xylosidase activity and isolated polynucleotides encoding the polypeptides. The invention also relates to nucleic acid constructs, vectors, and host cells comprising the polynucleotides as well as methods of producing and using the polypeptides.

  15. The phase transitions between Zn×Zn bosonic topological phases in 1+1D, and a constraint on the central charge for the critical points between bosonic symmetry protected topological phases

    Directory of Open Access Journals (Sweden)

    Lokman Tsui

    2017-06-01

    Full Text Available The study of continuous phase transitions triggered by spontaneous symmetry breaking has brought revolutionary ideas to physics. Recently, through the discovery of symmetry protected topological phases, it is realized that continuous quantum phase transition can also occur between states with the same symmetry but different topology. Here we study a specific class of such phase transitions in 1+1 dimensions – the phase transition between bosonic topological phases protected by Zn×Zn. We find in all cases the critical point possesses two gap opening relevant operators: one leads to a Landau-forbidden symmetry breaking phase transition and the other to the topological phase transition. We also obtained a constraint on the central charge for general phase transitions between symmetry protected bosonic topological phases in 1+1D.

  16. Sustainable Transition

    DEFF Research Database (Denmark)

    2014-01-01

    What. The chapter addresses designing for sustainability as interventions in socio-technical systems and social practices of users and communities. It calls for reflexive design practices challenging dominant regimes and shaping alternative design spaces. The specific case is the reconfiguration...... of agendas/vision, technologies, actors and institutions in the emergent design of an urban mobility system based on an electric car sharing system. Why. Designing for sustainability is a fundamental challenge for future design practices; designers have to obtain an ability to contribute to sustainable...... transition processes. Where. Addresses design processes aimed at sustainable transition enacted in complex social settings, socio-technical systems involving many different actors and agendas. How. The chapter outlines a conceptual and analytic framework for a reflexive design practice for sustainability...

  17. Transition Operators

    CERN Document Server

    Alcock-Zeilinger, Judith

    2016-01-01

    In this paper, we give a generic algorithm of the transition operators between Hermitian Young projection operators corresponding to equivalent irreducible representations of SU(N), using the compact expressions of Hermitian Young projection operators derived in a companion paper. We show that the Hermitian Young projection operators together with their transition operators constitute a fully orthogonal basis for the algebra of invariants of $V^{\\otimes m}$ that exhibits a systematically simplified multiplication table. We discuss the full algebra of invariants over $V^{\\otimes 3}$ and $V^{\\otimes 4}$ as explicit examples. In our presentation we make use of various standard concepts such as Young projection operators, Clebsch-Gordan operators, and invariants (in birdtrack notation). We tie these perspectives together and use them to shed light on each other.

  18. Shear induced phase transitions induced in edible fats

    Science.gov (United States)

    Mazzanti, Gianfranco; Welch, Sarah E.; Marangoni, Alejandro G.; Sirota, Eric B.; Idziak, Stefan H. J.

    2003-03-01

    The food industry crystallizes fats under different conditions of temperature and shear to obtain products with desired crystalline phases. Milk fat, palm oil, cocoa butter and chocolate were crystallized from the melt in a temperature controlled Couette cell. Synchrotron x-ray diffraction studies were conducted to examine the role of shear on the phase transitions seen in edible fats. The shear forces on the crystals induced acceleration of the alpha to beta-prime phase transition with increasing shear rate in milk fat and palm oil. The increase was slow at low shear rates and became very strong above 360 s-1. In cocoa butter the acceleration between beta-prime-III and beta-V phase transition increased until a maximum of at 360 s-1, and then decreased, showing competition between enhanced heat transfer and viscous heat generation.

  19. The Magnetically-Tuned Transition-Edge Sensor

    Science.gov (United States)

    Sadleir, John E.; Lee, Sang-Jun; Smith, Stephen J.; Busch, Sarah E.; Bandler, Simon R.; Adams, Joseph S.; Eckart, Megan E.; Chevenak, James A.; Kelley, Richard L.; Kilbourne, Caroline A.; Porter, Frederick S.; Porst, Jan-Patrick

    2014-01-01

    We present the first measurements on the proposed magnetically-tuned superconducting transition-edge sensor (MTES) and compare the modified resistive transition with the theoretical prediction. A TES's resistive transition is customarily characterized in terms of the unit less device parameters alpha and beta corresponding to the resistive response to changes in temperature and current respectively. We present a new relationship between measured IV quantities and the parameters alpha and beta and use these relations to confirm we have stably biased a TES with negative beta parameter with magnetic tuning. Motivated by access to this new unexplored parameter space, we investigate the conditions for bias stability of a TES taking into account both self and externally applied magnetic fields.

  20. The GERDA experiment on 0{nu}{beta}{beta} decay

    Energy Technology Data Exchange (ETDEWEB)

    Freund, Kai [Eberhard Karls Universitaet Tuebingen (Germany); Collaboration: GERDA-Collaboration

    2012-07-01

    The Gerda (Germanium Detector Array) collaboration searches for the neutrinoless double beta decay (0{nu}{beta}{beta}) of {sup 76}Ge. The existence of this decay would give rise to the assumption that the neutrino is a Majorana particle, i.e. its own antiparticle. A measured half-life could be used to determine the effective neutrino mass and hence resolve the neutrino mass hierarchy problem. Germanium diodes, isotopically enriched in {sup 76}Ge, are used as both source and detector. Due to the low rate of this decay (T{sub 1/2}>10{sup 25} y), the experimental background must be reduced to a level of 10{sup -2}counts/(kg y keV) or better in the region around Q{sub {beta}{beta}}. To minimize background from cosmogenically produced secondary particles, a low Z shielding is employed. Thus, the naked diodes are operated in a liquid argon cryostat, which is surrounded by a water tank acting as both passive shield and active muon Cherenkov veto. Gerda started the commissioning runs in 2010 and in November 2011, the first phase of data taking with enriched detectors has begun. In this talk, the first year of the experiment is summarized.

  1. Testing Lorentz invariance in orbital electron capture

    NARCIS (Netherlands)

    Vos, K. K.; Wilschut, H. W.; Timmermans, R. G. E.

    2015-01-01

    Searches for Lorentz violation were recently extended to the weak sector, in particular neutron and nuclear beta decay [Noordmans, Wilschut, and Timmermans, Phys. Rev. C 87, 055502 (2013)]. From experiments on forbidden beta-decay transitions, strong limits in the range of 10(-6) to 10(-8) were obta

  2. Nanomolar Inhibitors of AmpC [beta]-Lactamase

    Energy Technology Data Exchange (ETDEWEB)

    Morandi, Federica; Caselli, Emilia; Morandi, Stefania; Focia, Pamela J.; Blazquez, Jesus; Shoichet, Brian K.; Prati, Fabio (Degali); (NIH); (NWU); (UCSF)

    2010-03-08

    {beta}-lactamases are the most widespread resistance mechanism to {beta}-lactam antibiotics, such as the penicillins and the cephalosporins. In an effort to combat these enzymes, a combination of stereoselective organic synthesis, enzymology, microbiology, and X-ray crystallography was used to design and evaluate new carboxyphenyl-glycylboronic acid transition-state analogue inhibitors of the class C {beta}-lactamase AmpC. The new compounds improve inhibition by over 2 orders of magnitude compared to analogous glycylboronic acids, with K{sub i} values as low as 1 nM. On the basis of the differential binding of different analogues, the introduced carboxylate alone contributes about 2.1 kcal/mol in affinity. This carboxylate corresponds to the ubiquitous C3(4)' carboxylate of {beta}-lactams, and this energy represents the first thermodynamic measurement of the importance of this group in molecular recognition by class C {beta}-lactamases. The structures of AmpC in complex with two of these inhibitors were determined by X-ray crystallography at 1.72 and 1.83 {angstrom} resolution. These structures suggest a structural basis for the high affinity of the new compounds and provide templates for further design. The highest affinity inhibitor was 5 orders of magnitude more selective for AmpC than for characteristic serine proteases, such as chymotrypsin. This inhibitor reversed the resistance of clinical pathogens to the third generation cephalosporin ceftazidime; it may serve as a lead compound for drug discovery to combat bacterial resistance to {beta}-lactam antibiotics.

  3. Tumor-produced, active Interleukin-1 {beta} regulates gene expression in carcinoma-associated fibroblasts

    Energy Technology Data Exchange (ETDEWEB)

    Dudas, Jozsef, E-mail: Jozsef.Dudas@i-med.ac.at [Department of Otorhinolaryngology, Medical University Innsbruck, Anichstrasse 35, A-6020 Innsbruck (Austria); Fullar, Alexandra, E-mail: fullarsz@gmail.com [Department of Otorhinolaryngology, Medical University Innsbruck, Anichstrasse 35, A-6020 Innsbruck (Austria); 1st Institute of Pathology and Experimental Cancer Research, Semmelweis University, Ulloei ut 26, H-1085 Budapest (Hungary); Bitsche, Mario, E-mail: Mario.Bitsche@i-med.ac.at [Department of Otorhinolaryngology, Medical University Innsbruck, Anichstrasse 35, A-6020 Innsbruck (Austria); Schartinger, Volker, E-mail: Volker.Schartinger@i-med.ac.at [Department of Otorhinolaryngology, Medical University Innsbruck, Anichstrasse 35, A-6020 Innsbruck (Austria); Kovalszky, Ilona, E-mail: koval@korb1.sote.hu [1st Institute of Pathology and Experimental Cancer Research, Semmelweis University, Ulloei ut 26, H-1085 Budapest (Hungary); Sprinzl, Georg Mathias, E-mail: Georg.Sprinzl@i-med.ac.at [Department of Otorhinolaryngology, Medical University Innsbruck, Anichstrasse 35, A-6020 Innsbruck (Austria); Riechelmann, Herbert, E-mail: Herbert.Riechelmann@i-med.ac.at [Department of Otorhinolaryngology, Medical University Innsbruck, Anichstrasse 35, A-6020 Innsbruck (Austria)

    2011-09-10

    Recently we described a co-culture model of periodontal ligament (PDL) fibroblasts and SCC-25 lingual squamous carcinoma cells, which resulted in conversion of normal fibroblasts into carcinoma-associated fibroblasts (CAFs), and in epithelial-mesenchymal transition (EMT) of SCC-25 cells. We have found a constitutive high interleukin-1{beta} (IL1-{beta}) expression in SCC-25 cells in normal and in co-cultured conditions. In our hypothesis a constitutive IL1-{beta} expression in SCC-25 regulates gene expression in fibroblasts during co-culture. Co-cultures were performed between PDL fibroblasts and SCC-25 cells with and without dexamethasone (DEX) treatment; IL1-{beta} processing was investigated in SCC-25 cells, tumor cells and PDL fibroblasts were treated with IL1-{beta}. IL1-{beta} signaling was investigated by western blot and immunocytochemistry. IL1-{beta}-regulated genes were analyzed by real-time qPCR. SCC-25 cells produced 16 kD active IL1-{beta}, its receptor was upregulated in PDL fibroblasts during co-culture, which induced phosphorylation of interleukin-1 receptor-associated kinase-1 (IRAK-1), and nuclear translocalization of NF{kappa}B{alpha}. Several genes, including interferon regulatory factor 1 (IRF1) interleukin-6 (IL-6) and prostaglandin-endoperoxide synthase 2 (COX-2) were induced in CAFs during co-culture. The most enhanced induction was found for IL-6 and COX-2. Treatment of PDL fibroblasts with IL1-{beta} reproduced a time- and dose-dependent upregulation of IL1-receptor, IL-6 and COX-2. A further proof was achieved by DEX inhibition for IL1-{beta}-stimulated IL-6 and COX-2 gene expression. Constitutive expression of IL1-{beta} in the tumor cells leads to IL1-{beta}-stimulated gene expression changes in tumor-associated fibroblasts, which are involved in tumor progression. -- Graphical abstract: SCC-25 cells produce active, processed IL1-{beta}. PDL fibroblasts possess receptor for IL1-{beta}, and its expression is increased 4.56-times in the

  4. Measurements of $L_{31}, L_{3}\\alpha, L_{3}\\beta, L_{2}\\beta, L_{2} \\gamma, L_{1}\\beta, L_{1}\\gamma, L_{\\beta}, L_{\\gamma}, L_{1x}, L_{2x}$ and $L_{3x}$ X-ray production cross sections and L subshell fluorescence

    CERN Document Server

    Ertugrul, M

    2001-01-01

    The L/sub 3l/, L/sub 3 alpha /, L/sub 3 beta /, L/sub 2 beta /, L/sub 2 gamma /, L/sub 1 beta /, L/sub 1 gamma /, L/sub beta /, L/sub gamma /, L/sub 1x/, L/sub 2x/ and L/sub 3x/ X-ray production cross sections in Re, W and Ta have been measured using the 59.5 keV incident photon energy. The measurements were performed using an Am-241 radioisotope as the photon source and a Si(Li) detector. The L X-rays are resolved with a new analytical method. The obtained L/sub l/, L/sub alpha /, L /sub 3 beta /, L/sub 2 beta /, L/sub 2 gamma /, L/sub 1 beta /, L/sub 1 gamma /, L/sub beta /, L/sub gamma /, L/sub 1x/, L/sub 2x/ and L /sub 3x/ X-rays are compared with the theoretical calculations using the most reliable theoretical values of L/sub i/ (i=1, 2, 3) subshell photoionization cross sections, fluorescence yields, X-ray emission rates and Coster-Kronig transition probabilities. The results in the present paper are found to be in good agreement with the calculated values. (23 refs).

  5. Associating a prototypical forbidden food item with guilt or celebration: relationships with indicators of (un)healthy eating and the moderating role of stress and depressive symptoms.

    Science.gov (United States)

    Kuijer, Roeline G; Boyce, Jessica A; Marshall, Emma M

    2015-01-01

    The increase in obesity and the many educational messages prompting us to eat a healthy diet have heightened people's concerns about the effects of food choice on health and weight. An unintended side effect may be that such awareness fuels feelings of guilt and worry about food. Although guilt has the potential to motivate behaviour change, it may also lead to feelings of helplessness and loss of control. The current study examined the relationship between a default association of either 'guilt' or 'celebration' with a prototypical forbidden food item (chocolate cake), indicators of healthy eating and choosing food for mood regulation reasons. Following a 'diathesis-stress' perspective, the moderating roles of depressive symptoms and stress were examined. Although a default association of guilt was found to be harmless under some circumstances (i.e. under low stress), those who associated chocolate cake with guilt (vs. celebration) reported unhealthier eating habits and lower levels of perceived behavioural control over healthy eating when under stress, rated mood regulation reasons for food choice as important irrespective of their current affective state, and did not have more positive attitudes towards healthy eating. Implications for public health messages and interventions will be discussed.

  6. The development of loop-mediated isothermal amplification (LAMP) assays for the rapid authentication of five forbidden vegetables in strict vegetarian diets.

    Science.gov (United States)

    Lee, Meng-Shiou; Su, Ting-Ying; Lien, Yi-Yang; Sheu, Shyang-Chwen

    2017-03-14

    Plant-based food ingredients such as garlic, Chinese leek, Chinese onion, green onion and onion are widely used in many cuisines around the world. However, these ingredients known as the "five forbidden vegetables" (FFVs) are not allowed in some vegetarian diets. In this study, a loop-mediated isothermal amplification (LAMP) assay was developed for the detection of FFVs using five respective LAMP primer sets. The specific primers targeted the ITS1-5.8S-ITS2 nuclear ribosomal DNA sequence regions among the five vegetables. The results demonstrated that the identification of FFVs using the newly developed LAMP assay is more sensitive than the traditional PCR method. Using pepper, basil, parsley, chili and ginger as references, established LAMP primer sets showed high specificity for the identification of the FFV species. Moreover, when FFVs were mixed with other plant ingredients at different ratios (100:0, 50:50, 20:80, 10:90, 5:95, 2:98, and 1:99), no cross-reactivity was evident using LAMP. Finally, genomic DNAs extracted from boiled and steamed FFVs in processed foods were used as templates; the performance of the LAMP reaction was not influenced using validated LAMP primers. Not only can FFV ingredients be identified but commercial foods containing FFVs can also be authenticated. This LAMP method will be useful for the authentication of FFVs in practical food markets in the future.

  7. Study of Milli-Jansky Seyfert Galaxies with Strong Forbidden High-Ionization Lines Using the Very Large Array Survey Images

    CERN Document Server

    Lal, Dharam V

    2016-01-01

    We study the radio properties at 1.4 GHz of Seyfert galaxies with strong forbidden high-ionization lines (FHILs), selected from the Sloan Digital Sky Survey - a large-sized sample containing nearly equal proportion of diverse range of Seyfert galaxies showing similar redshift distributions compiled by Gelbord et al. (2009) using the Very Large Array survey images. The radio detection rate is low, 49%, which is lower than the detection rate of several other known Seyfert galaxy samples. These galaxies show low star formation rates and the radio emission is dominated by the active nucleus with $\\le$10% contribution from thermal emission, and possibly, none show evidence for relativistic beaming. The radio detection rate, distributions of radio power, and correlations between radio power and line luminosities or X-ray luminosity for narrow-line Seyfert 1 (NLS1), Seyfert 1 and Seyfert 2 galaxies are consistent with the predictions of the unified scheme hypothesis. Using correlation between radio and [O\\,III]\\,$\\l...

  8. Effect of cooler electrons on a compressive ion acoustic solitary wave in a warm ion plasma — Forbidden regions, double layers, and supersolitons

    Energy Technology Data Exchange (ETDEWEB)

    Ghosh, S. S., E-mail: sukti@iigs.iigm.res.in [Indian Institute of Geomagnetism, New Panvel, Navi Mumbai 410218 (India); Sekar Iyengar, A. N. [Plasma Physics Division, Saha Institute of Nuclear Physics, Kolkata 700064 (India)

    2014-08-15

    It is observed that the presence of a minority component of cooler electrons in a three component plasma plays a deterministic role in the evolution of solitary waves, double layers, or the newly discovered structures called supersolitons. The inclusion of the cooler component of electrons in a single electron plasma produces sharp increase in nonlinearity in spite of a decrease in the overall energy of the system. The effect maximizes at certain critical value of the number density of the cooler component (typically 15%–20%) giving rise to a hump in the amplitude variation profile. For larger amplitudes, the hump leads to a forbidden region in the ambient cooler electron concentration which dissociates the overall existence domain of solitary wave solutions in two distinct parameter regime. It is observed that an inclusion of the cooler component of electrons as low as < 1% affects the plasma system significantly resulting in compressive double layers. The solution is further affected by the cold to hot electron temperature ratio. In an adequately hotter bulk plasma (i.e., moderately low cold to hot electron temperature ratio), the parameter domain of compressive double layers is bounded by a sharp discontinuity in the corresponding amplitude variation profile which may lead to supersolitons.

  9. [Screening method for 29 forbidden or limited synthetic pigments in cheese by liquid chromatography/quadrupole time-of-flight mass spectrometry].

    Science.gov (United States)

    Zhao, Yansheng; Yang, Minli; Zhang, Feng; Feng, Feng; Chu, Xiaogang; Dong, Ying

    2011-07-01

    A screening method for 29 forbidden or limited synthetic pigments in cheese samples was established by liquid chromatography/quadrupole time-of-flight mass spectrometry (LC/Q-TOF MS). The pigments were extracted by n-hexane/water (3:1, v/v). After extraction, the n-hexane extract, water extract and residue, were obtained. The n-hexane extract was then cleaned-up by gel permeation chromatography (GPC). The water extract was extracted by acetonitrile, and the residue by ammonia water/methanol (1:99, v/v). The results showed that the 29 synthetic pigments with a wide range of polarities were extracted effectively with the recoveries between 70% and 95%, and matched well by Q-TOF MS precision mass searching to the mass spectral library with matching scores between 59. 66 and 99. 47. The quantitative analysis of the 29 pigments was carried out by Target MS/MS. The limits of detection (LODs) for 8 Sudan dyes were 0.4-2.5 micro/kg while for 21 water-soluble synthetic pigments were 20-80 microg/kg. The screening method is suitable for a wide range of synthetic pigments, and can be applied to food samples with proteins and fat in matrix.

  10. Forbidden Coherence Transfer of 19F Nuclei to Quantitatively Measure the Dynamics of a CF3-Containing Ligand in Receptor-Bound States

    Directory of Open Access Journals (Sweden)

    Yuji Tokunaga

    2017-09-01

    Full Text Available The dynamic property of a ligand in the receptor-bound state is an important metric to characterize the interactions in the ligand–receptor interface, and the development of an experimental strategy to quantify the amplitude of motions in the bound state is of importance to introduce the dynamic aspect into structure-guided drug development (SGDD. Fluorine modifications are frequently introduced at the hit-to-lead optimization stage to enhance the binding potency and other characteristics of a ligand. However, the effects of fluorine modifications are generally difficult to predict, owing to the pleiotropic nature of the interactions. In this study, we report an NMR-based approach to experimentally evaluate the local dynamics of trifluoromethyl (CF3-containing ligands in the receptor-bound states. For this purpose, the forbidden coherence transfer (FCT analysis, which has been used to study the dynamics of methyl moieties in proteins, was extended to the 19F nuclei of CF3-containing ligands. By applying this CF3–FCT analysis to a model interaction system consisting of a ligand, AST-487, and a receptor, p38α, we successfully quantified the amplitude of the CF3 dynamics in the p38α-bound state. The strategy would bring the CF3-containing ligands within the scope of dynamic SGDD to improve the affinity and specificity for the drug-target receptors.

  11. The development of loop-mediated isothermal amplification (LAMP) assays for the rapid authentication of five forbidden vegetables in strict vegetarian diets

    Science.gov (United States)

    Lee, Meng-Shiou; Su, Ting-Ying; Lien, Yi-Yang; Sheu, Shyang-Chwen

    2017-01-01

    Plant-based food ingredients such as garlic, Chinese leek, Chinese onion, green onion and onion are widely used in many cuisines around the world. However, these ingredients known as the “five forbidden vegetables” (FFVs) are not allowed in some vegetarian diets. In this study, a loop-mediated isothermal amplification (LAMP) assay was developed for the detection of FFVs using five respective LAMP primer sets. The specific primers targeted the ITS1-5.8S-ITS2 nuclear ribosomal DNA sequence regions among the five vegetables. The results demonstrated that the identification of FFVs using the newly developed LAMP assay is more sensitive than the traditional PCR method. Using pepper, basil, parsley, chili and ginger as references, established LAMP primer sets showed high specificity for the identification of the FFV species. Moreover, when FFVs were mixed with other plant ingredients at different ratios (100:0, 50:50, 20:80, 10:90, 5:95, 2:98, and 1:99), no cross-reactivity was evident using LAMP. Finally, genomic DNAs extracted from boiled and steamed FFVs in processed foods were used as templates; the performance of the LAMP reaction was not influenced using validated LAMP primers. Not only can FFV ingredients be identified but commercial foods containing FFVs can also be authenticated. This LAMP method will be useful for the authentication of FFVs in practical food markets in the future. PMID:28290475

  12. Screening of preservatives by HPLC-PDA-ESI/MS: A focus on both allowed and recently forbidden compounds in the new EU cosmetics regulation.

    Science.gov (United States)

    Lecce, Raffaele; Regazzoni, Luca; Mustazza, Carlo; Incarnato, Giampaolo; Porrà, Rita; Panusa, Alessia

    2016-06-05

    Commission regulation (EU) No 358/2014 amending the new regulation (EC) No 1223/2009 on cosmetics has prohibited the use of isopropyl-, isobutyl-, phenyl-, benzyl- and pentylparaben. Furthermore, Commission regulation (EU) No 1004/2014 has lowered the maximum permitted concentration of butyl- and propylparaben in cosmetics and it has also banned them in leave-on products designed for application on the nappy area of children under three years of age. A HPLC-PDA-ESI/MS method has been developed herein for the detection of seventeen preservatives, both the most utilised and the recently forbidden by the new EU regulations. The separation of these compounds, including benzoic acid and its derivatives in a 1.10 - 3.04 log Pow range, has been performed with a gradient elution on a Symmetry(®) C18 column (250×4.6mm i.d., particle size 5μm) with water and acetonitrile (0.1% formic acid) as mobile phase. Quantification has been carried out by HPLC-PDA. The method has been validated and successfully applied to the analysis of a large number of cosmetics with different functions like rinse-off and leave-on, or composition like skin, hair, face and oral products. Copyright © 2016 Elsevier B.V. All rights reserved.

  13. Analysis of betaS and betaA genes in a Mexican population with African roots.

    Science.gov (United States)

    Magaña, María Teresa; Ongay, Zoyla; Tagle, Juan; Bentura, Gilberto; Cobián, José G; Perea, F Javier; Casas-Castañeda, Maricela; Sánchez-López, Yoaly J; Ibarra, Bertha

    2002-01-01

    To investigate the origin of the beta(A) and beta(S) genes in a Mexican population with African roots and a high frequency of hemoglobin S, we analyzed 467 individuals (288 unrelated) from different towns in the states of Guerrero and Oaxaca in the Costa Chica region. The frequency of the sickle-cell trait was 12.8%, which may represent a public health problem. The frequencies of the beta-haplotypes were determined from 350 nonrelated chromosomes (313 beta(A) and 37 beta(S)). We observed 15 different beta(A) haplotypes, the most common of which were haplotypes 1 (48.9%), 2 (13.4%), and 3 (13.4%). The calculation of pairwise distributions and Nei's genetic distance analysis using 32 worldwide populations showed that the beta(A) genes are more closely related to those of Mexican Mestizos and North Africans. Bantu and Benin haplotypes and haplotype 9 were related to the beta(S) genes, with frequencies of 78.8, 18.2, and 3.0%, respectively. Comparison of these haplotypes with 17 other populations revealed a high similitude with the population of the Central African Republic. These data suggest distinct origins for the beta(A) and beta(S) genes in Mexican individuals from the Costa Chica region.

  14. Supra-transmission and bistability in nonlinear media with a photonic and electronic forbidden band gap; Supratransmission et bistabilite nonlineaire dans les milieux a bandes interdites photoniques et electroniques

    Energy Technology Data Exchange (ETDEWEB)

    Chevriaux, D

    2007-06-15

    We study wave scattering in different nonlinear media possessing a natural forbidden band gap. In particular, we show the existence of a bistable behavior in media governed by the sine-Gordon equation (short pendular chain, Josephson junction array, quantum Hall bilayer), or the nonlinear Schroedinger equation (Kerr and Bragg media), in discrete and continuous models. These different media are submitted to periodic boundary conditions with a frequency in the forbidden band gap and an amplitude that determines their stability states. Indeed, for a sufficient amplitude (supra-transmission), the medium switches from reflector to transmitter, hence allowing the output signal to jump from evanescent to large values. We give a complete analytical description of the bistability that allows to understand the different stationary states observed and to predict the switch of one state to the other. (author)

  15. Beta-blockers for hypertension

    Science.gov (United States)

    Wiysonge, Charles S; Bradley, Hazel A; Volmink, Jimmy; Mayosi, Bongani M; Opie, Lionel H

    2017-01-01

    Background Beta-blockers refer to a mixed group of drugs with diverse pharmacodynamic and pharmacokinetic properties. They have shown long-term beneficial effects on mortality and cardiovascular disease (CVD) when used in people with heart failure or acute myocardial infarction. Beta-blockers were thought to have similar beneficial effects when used as first-line therapy for hypertension. However, the benefit of beta-blockers as first-line therapy for hypertension without compelling indications is controversial. This review is an update of a Cochrane Review initially published in 2007 and updated in 2012. Objectives To assess the effects of beta-blockers on morbidity and mortality endpoints in adults with hypertension. Search methods The Cochrane Hypertension Information Specialist searched the following databases for randomized controlled trials up to June 2016: the Cochrane Hypertension Specialised Register, the Cochrane Central Register of Controlled Trials (CENTRAL) (2016, Issue 6), MEDLINE (from 1946), Embase (from 1974), and ClinicalTrials.gov. We checked reference lists of relevant reviews, and reference lists of studies potentially eligible for inclusion in this review, and also searched the the World Health Organization International Clinical Trials Registry Platform on 06 July 2015. Selection criteria Randomised controlled trials (RCTs) of at least one year of duration, which assessed the effects of beta-blockers compared to placebo or other drugs, as first-line therapy for hypertension, on mortality and morbidity in adults. Data collection and analysis We selected studies and extracted data in duplicate, resolving discrepancies by consensus. We expressed study results as risk ratios (RR) with 95% confidence intervals (CI) and conducted fixed-effect or random-effects meta-analyses, as appropriate. We also used GRADE to assess the certainty of the evidence. GRADE classifies the certainty of evidence as high (if we are confident that the true effect lies

  16. CdWO4 bolometers for Double Beta Decay search

    CERN Document Server

    Gironi, L; Capelli, S; Cremonesi, O; Pavan, M; Pessina, G; Pirro, S

    2008-01-01

    In the field of Double Beta Decay (DBD) searches the possibility to have high resolution detectors in which background can be discriminated is very appealing. This very interesting possibility can be largely fulfilled in the case of a scintillating bolometer containing a Double Beta Decay emitter whose transition energy exceeds the one of the natural gamma line of 208Tl. We present the latest results obtained in the development of such a kind of scintillating bolometer. For the first time an array of five CdWO4 (116Cd has a Double Beta Decay transition energy of 2805 keV) crystals is tested. The array consists of a plane of four 3x3x3 cm3 crystals and a second plane consisting of a single 3x3x6 cm3 crystal. This setup is mounted in hall C of the National Laboratory of Gran Sasso inside a lead shielding in order to reduce as far as possible the environmental background. The aim of this test is to demonstrate the technical feasibility of this technique through an array of detectors and perform a long background...

  17. Beta-Thioxoketones

    DEFF Research Database (Denmark)

    Carlsen, Lars; Duus, Fritz

    1980-01-01

    ,π*), 415 (OC=CC=S π,π*), and 520 nm (C=S n,π*), respectively. The β-thioxoketones are converted by sodium hydroxide into the corresponding anions. CNDO/B Calculations predict that the negative charge in the β-thioxoketonates is delocalized over the OCCCS system, suggesting simultaneously sickles or W...... shaped conformations. Two characteristic absorption bands found for the β-thioxoketonates at ca. 275 and 400 nm are assigned to π,π* transitions involving the Ar–C[horiz bar, triple dot above]C[horiz bar, triple dot above]C–Ar′ and S[horiz bar, triple dot above]C[horiz bar, triple dot above]C[horiz bar......, triple dot above]C[horiz bar, triple dot above]O chromophores, respectively. The enol–enethiol tautomeric equilibrium has been studied by means of low temperature spectroscopy. At room temperature equilibrium constants (K293) of 3–5 have been found corresponding to a 4 : 1 enol–enethiol concentration...

  18. beta (+)-Thalassaemia in the Po river delta region (northern Italy): genotype and beta globin synthesis.

    Science.gov (United States)

    Del Senno, L; Pirastu, M; Barbieri, R; Bernardi, F; Buzzoni, D; Marchetti, G; Perrotta, C; Vullo, C; Kan, Y W; Conconi, F

    1985-01-01

    Six beta(+)-thalassaemic patients from the Po river delta region have been studied. Using synthetic oligonucleotides as specific hybridisation probes, the beta(+) IVS I mutation (G----A at position 108) was demonstrated. This lesion and the enzyme polymorphism pattern in the subjects examined are the same as have been described for other Mediterranean beta(+)-thalassaemias. Antenatal diagnosis through DNA analysis of beta(+)-thalassaemia is therefore possible. The production of beta globin in a beta(+), homozygote and in a beta (+), beta(0) 39 (nonsense mutation at codon 39) double heterozygote is approximately 20% and 10% respectively of total non-alpha globin synthesis. Despite some overlapping of the results, similar beta globin synthesis levels have been obtained in 43 beta(+)-thalassaemia patients. This suggests that in the Po river delta region the most common thalassaemic genes are beta(0) 39 and beta(+) IVS I. Images PMID:2580095

  19. Conformational Transitions

    Science.gov (United States)

    Czerminski, Ryszard; Roitberg, Adrian; Choi, Chyung; Ulitsky, Alexander; Elber, Ron

    1991-10-01

    Two computational approaches to study plausible conformations of biological molecules and the transitions between them are presented and discussed. The first approach is a new search algorithm which enhances the sampling of alternative conformers using a mean field approximation. It is argued and demonstrated that the mean field approximation has a small effect on the location of the minima. The method is a combination of the LES protocol (Locally Enhanced Sampling) and simulated annealing. The LES method was used in the past to study the diffusion pathways of ligands from buried active sites in myoglobin and leghemoglobin to the exterior of the protein. The present formulation of LES and its implementation in a Molecular Dynamics program is described. An application for side chain placement in a tetrapeptide is presented. The computational effort associated with conformational searches using LES grows only linearly with the number of degrees of freedom, whereas in the exact case the computational effort grows exponentially. Such saving is of course associated with a mean field approximation. The second branch of studies pertains to the calculation of reaction paths in large and flexible biological systems. An extensive mapping of minima and barriers for two different tetrapeptides is calculated from the known minima and barriers of alanine tetrapeptide which we calculated recently.1 The tetrapeptides are useful models for the formation of secondary structure elements since they are the shortest possible polymers of this type which can still form a complete helical turn. The tetrapeptides are isobutyryl-val(χ1=60)-ala-ala and isobutyryl-val(χ1=-60)-ala-ala. Properties of the hundreds of minima and of the hundreds intervening barriers are discussed. Estimates for thermal transition times between the many conformers (and times to explore the complete phase space) are calculated and compared. It is suggested that the most significant effect of the side chain size is

  20. Rapid transitions

    Energy Technology Data Exchange (ETDEWEB)

    Hamrin, J.G.

    1980-01-01

    Solar energy programs are entering a critical transitional period as we move from the initial marketing of solar technologies into a phase of widespread commercialization. We face the dual challenge of trying to get enough solar systems in place fast enough to prove solar is a viable alternative, while trying to ensure the systems are designed and installed properly, proving the energy savings as promised. This is a period of both great opportunity and high risk as the field becomes crowded with new solar cheerleaders and supporters but seldom enough competent players. The status of existing and proposed programs for the accelerated commercialization of solar energy in California is described.

  1. Transit space

    DEFF Research Database (Denmark)

    Raahauge, Kirsten Marie

    2008-01-01

    This article deals with representations of one specific city, Århus, Denmark, especially its central district. The analysis is based on anthropological fieldwork conducted in Skåde Bakker and Fedet, two well-off neighborhoods. The overall purpose of the project is to study perceptions of space...... and the interaction of cultural, social, and spatial organizations, as seen from the point of view of people living in Skåde Bakker and Fedet. The focus is on the city dwellers’ representations of the central district of Århus with specific reference to the concept of transit space. When applied to various Århusian...

  2. Understanding epidemiological transition in India

    Science.gov (United States)

    Yadav, Suryakant; Arokiasamy, Perianayagam

    2014-01-01

    Background Omran's theory explains changing disease patterns over time predominantly from infectious to chronic noncommunicable diseases (NCDs). India's epidemiological transition is characterized by dual burden of diseases. Kumar addressed low mortality and high morbidity in Kerala, which seems also to be true for India as a country in the current demographic scenario. Methods NSS data (1986–1987, 1995–1996, 2004) and aggregated data on causes of death provided by Registrar General India (RGI) were used to examine the structural changes in morbidity and causes of death. A zero-inflated poisson (ZIP) regression model and a beta-binomial model were used to corroborate the mounting age pattern of morbidity. Measures, namely the 25th and 75th percentiles of age-at-death and modal age-at-death, were used to examine the advances in mortality transition. Objective This study addressed the advances in epidemiological transition via exploring the structural changes in pattern of diseases and progress in mortality transition. Results The burden of NCDs has been increasing in old age without replacing the burden of communicable diseases. The manifold rise of chronic diseases in recent decades justifies the death toll and is responsible for transformation in the age pattern of morbidity. Over time, deaths have been concentrated near the modal age-at-death. Modal age-at-death increased linearly by 5 years for females (r2=0.9515) and males (r2=0.9020). Significant increase in modal age-at-death ascertained the dominance of old age mortality over the childhood/adult age mortality. Conclusions India experiences a dual burden of diseases associated with a remarkable transformation in the age pattern of morbidity and mortality, contemporaneous with structural changes in disease patterns. Continued progress in the pattern of diseases and mortality transition, accompanied by a linear rise in ex, unravels a compelling variation in advances found so far in epidemiological

  3. Smart Beta or Smart Alpha

    DEFF Research Database (Denmark)

    Winther, Kenneth Lillelund; Steenstrup, Søren Resen

    2016-01-01

    Smart beta has become the flavor of the decade in the investment world with its low fees, easy access to rewarded risk premiums, and appearance of providing good investment results relative to both traditional passive benchmarks and actively managed funds. Although we consider it well documented...... that smart beta investing probably will do better than passive market capitalization investing over time, we believe many are coming to a conclusion too quickly regarding active managers. Institutional investors are able to guide managers through benchmarks and risk frameworks toward the same well......-documented smart beta risk premiums and still motivate active managers to avoid value traps, too highly priced small caps, defensives, etc. By constructing the equity portfolios of active managers that resemble the most widely used risk premiums, we show that the returns and risk-adjusted returns measures...

  4. Beta emitters and radiation protection

    DEFF Research Database (Denmark)

    Jødal, Lars

    2009-01-01

    , and 90Y, using data from a freely available database. Bremsstrahlung yields were calculated for 90Y shielded by lead, aluminium, or perspex. Bremsstrahlung spectrum from 90Y shielded by perspex was measured, and attenuation of spectrum by lead was calculated. Whole-body and finger doses to persons...... preparing 90Y-Zevalin were measured. CONCLUSIONS. Good laboratory practice is important to keep radiation doses low. To reduce bremsstrahlung, 90Y should not be shielded by lead but instead perspex (10 mm) or aluminium (5 mm). Bremsstrahlung radiation can be further reduced by adding a millimetre of lead......BACKGROUND. Beta emitters, such as 90Y, are increasingly being used for cancer treatment. However, beta emitters demand other precautions than gamma emitters during preparation and administration, especially concerning shielding. AIM. To discuss practical precautions for handling beta emitters...

  5. Narrow-line diode laser system for laser cooling of strontium atoms on the intercombination transition

    Science.gov (United States)

    Li, Y.; Ido, T.; Eichler, T.; Katori, H.

    We report a diode laser system developed for narrow-line cooling and trapping on the 1S0-3P1 intercombination transition of neutral strontium atoms. Doppler cooling on this spin-forbidden transition with a line width of Γ/2π=7.1 kHz enables us to achieve sub-μK temperatures in a two-step cooling process. The required reduction of the laser line width to the kHz level was achieved by locking the laser to a tunable Fabry-Pérot cavity. The long-term drift (>0.1 s) of the reference cavity was compensated by employing the saturated absorption signal obtained from Sr vapor in a heat pipe of novel design. We demonstrate the potential of the system by performing spectroscopy of Sr atoms confined to the Lamb-Dicke regime in a one-dimensional optical lattice.

  6. Relativistic coupled cluster calculations on hyperfine structures and electromagnetic transition amplitudes of In III

    CERN Document Server

    Roy, Sourav; Majumder, Sonjoy

    2014-01-01

    Hyperfine constants and anomalies of ground as well as few low lying excited states of $^{113,115,117}$In III are studied with highly correlated relativistic coupled-cluster theory. The ground state hyperfine splitting of $^{115}$In III is estimated to be 106.8 GHz. A shift of almost 1.9 GHz of the above frequency has been calculated due to modified nuclear dipole moment. This splitting result shows its applicability as communication band and frequency standards at $10^{-11}$ sec. Correlations study of hyperfine constants indicates a few distinct features of many-body effects in the wave-functions in and near the nuclear region of this ion. Astrophysically important forbidden transition amplitudes are estimated for the first time in the literature to our knowledge. The calculated oscillator strengths of few allowed transitions are compared with recent experimental and theoretical results wherever available.

  7. Splitting between bright and dark excitons in transition metal dichalcogenide monolayers

    Science.gov (United States)

    Echeverry, J. P.; Urbaszek, B.; Amand, T.; Marie, X.; Gerber, I. C.

    2016-03-01

    The optical properties of transition metal dichalcogenide monolayers such as the two-dimensional semiconductors MoS2 and WSe2 are dominated by excitons, Coulomb bound electron-hole pairs. The light emission yield depends on whether the electron-hole transitions are optically allowed (bright) or forbidden (dark). By solving the Bethe-Salpeter equation on top of G W wave functions in density functional theory calculations, we determine the sign and amplitude of the splitting between bright and dark exciton states. We evaluate the influence of the spin-orbit coupling on the optical spectra and clearly demonstrate the strong impact of the intra-valley Coulomb exchange term on the dark-bright exciton fine structure splitting.

  8. Multifractality at non-Anderson disorder-driven transitions in Weyl semimetals and other systems

    Science.gov (United States)

    Syzranov, S. V.; Gurarie, V.; Radzihovsky, L.

    2016-10-01

    Systems with the power-law quasiparticle dispersion ɛk ∝kα exhibit non-Anderson disorder-driven transitions in dimensions d > 2 α, as exemplified by Weyl semimetals, 1D and 2D arrays of ultracold ions with long-range interactions, quantum kicked rotors, and semiconductor models in high dimensions. We study the wavefunction structure in such systems and demonstrate that at these transitions they exhibit fractal behaviour with an infinite set of multifractal exponents. The multifractality persists even when the wavefunction localisation is forbidden by symmetry or topology and occurs as a result of elastic scattering between all momentum states in the band on length scales shorter than the mean free path. We calculate explicitly the multifractal spectra in semiconductors and Weyl semimetals using one-loop and two-loop renormalisation-group approaches slightly above the marginal dimension d = 2 α.

  9. The crisis induced by the property transition of a system

    Institute of Scientific and Technical Information of China (English)

    Dai Jun; Wang Wen-Xiu; Jiang Yu-Mei; He Yue; Chen Wen; He Da-Ren

    2005-01-01

    A simultaneous transition in the property of a system from everywhere smooth and conservative to piecewise smooth and quasi-dissipative is observed in a kicked billiard when adjusting a single controlling parameter. The transition induces a special kind of crisis, which signifies a sudden change of a typical conservative stochastic web into a transient web formed by the forward image set of the discontinuity borderline of the system function. Iterations on the transient web finally fall in an escaping hole composed of an elliptic island chain, which appears right after the threshold of the property transition. The size of the hole becomes larger as the controlling parameter increases so that the iterations escape faster. The averaged lifetime of the iterations in the transient web therefore follows a power-law with a special scaling exponent. At the same time, a fat fractal forbidden web, which appears also at the threshold,grows up and cuts off more and more parts from the original conservative stochastic web so that the remnant transient web becomes thinner and thinner. We numerically show that another power law can also describe this.

  10. Incommensurate Chirality Density Wave Transition in a Hybrid Molecular Framework

    Science.gov (United States)

    Hill, Joshua A.; Christensen, Kirsten E.; Goodwin, Andrew L.

    2017-09-01

    Using single-crystal x-ray diffraction we characterize the 235 K incommensurate phase transition in the hybrid molecular framework tetraethylammonium silver(I) dicyanoargentate, [NEt4]Ag3(CN )4 . We demonstrate the transition to involve spontaneous resolution of chiral [NEt4]+ conformations, giving rise to a state in which molecular chirality is incommensurately modulated throughout the crystal lattice. We refer to this state as an incommensurate chirality density wave (XDW) phase, which represents a fundamentally new type of chiral symmetry breaking in the solid state. Drawing on parallels to the incommensurate ferroelectric transition of NaNO2 , we suggest the XDW state arises through coupling between acoustic (shear) and molecular rotoinversion modes. Such coupling is symmetry forbidden at the Brillouin zone center but symmetry allowed for small but finite modulation vectors q =[0 ,0 ,qz]* . The importance of long-wavelength chirality modulations in the physics of this hybrid framework may have implications for the generation of mesoscale chiral textures, as required for advanced photonic materials.

  11. Neutrinoless double beta decay experiments

    CERN Document Server

    Zuber, K

    2006-01-01

    The study of neutrinoless double beta decay is of outmost importance for neutrino physics. It is considered to be the gold plated channel to probe the fundamental character of neutrinos and to determine the neutrino mass. From the experimental point about nine different isotopes are explored for the search. After a general introduction follows a short discussion on nuclear matrix element calculations and supportive measurements. The current experimental status of double beta searches is presented followed by a short discussion of the ideas and proposals for large scale experiments.

  12. The microbial oxidation of (-)-beta-pinene by Botrytis cinerea.

    Science.gov (United States)

    Farooq, Afgan; Choudhary, M Iqbal; Tahara, Satoshi; Rahman, Atta-ur; Başer, K Hüsnü Can; Demirci, Fatih

    2002-01-01

    (-)-beta-pinene, a flavor and fragrance monoterpene is an important constituent of essential oils of many aromatic plants. It was oxidized by a plant-pathogenic fungus, Botrytis cinerea to afford four metabolites characterized as (-)-6a-hydroxy-beta-pinene, (-)-4beta,5beta-dihydroxy-beta-pinene, (-)-2beta,3beta-dihydroxypinane, and (-)-4beta-hydroxy-beta-pinene-6-one by detailed spectroscopic studies along with other known metabolites.

  13. A {beta} - {gamma} coincidence; Metodo de coincidencias {beta} - {gamma}

    Energy Technology Data Exchange (ETDEWEB)

    Agullo, F.

    1960-07-01

    A {beta} - {gamma} coincidence method for absolute counting is given. The fundamental principles are revised and the experimental part is detailed. The results from {sup 1}98 Au irradiated in the JEN 1 Swimming pool reactor are given. The maximal accuracy is 1 per cent. (Author) 11 refs.

  14. Pressure-induced phase transitions of indium selenide

    Science.gov (United States)

    Rasmussen, Anya Marie

    In2Se3 has potential as a phase-change material for memory applications. Understanding its phase diagram is important to achieve controlled switching between phases. Pressure-dependent phase transitions of In2Se3 bulk powders and nanowire samples were studied at room temperature and at elevated temperatures using synchrotron x-ray diffraction and diamond-anvil cells (DACs). alpha-In2Se3 transforms into the beta phase at 0.7 GPa, an order of magnitude lower than phase-transition critical pressures in typical semiconductors. The bulk moduli are reported and the c/a ratio for the beta phase is shown to have a highly nonlinear dependence on pressure. gamma-In2Se3, metastable under ambient conditions, transforms into to the high-pressure beta phase between 2.8 GPa and 3.2 GPa in bulk powder samples and at slightly higher pressures, between 3.2 GPa and 3.7 GPa in nanowire samples. While the gamma phase bulk modulus is similar to that of the beta phase, the decrease due to pressure in the unit cell parameter ratio, c/a, is less than half the decrease seen in the beta phase. Using high-temperature DACs, we investigated how elevated temperatures and pressures affect the crystal structure of In 2Se3. From these measurements, the high-pressure beta phase was found to be metastable. The high-pressure beta phase transitions into the high-temperature beta phase at temperatures above 380 °C.

  15. Beta thalassaemia mutations in Turkish Cypriots.

    Science.gov (United States)

    Sozuoz, A; Berkalp, A; Figus, A; Loi, A; Pirastu, M; Cao, A

    1988-01-01

    Using oligonucleotide hybridisation or restriction endonuclease analysis, we have characterised the molecular defect in 94 patients with thalassaemia major and four with thalassaemia intermedia of Turkish Cypriot descent. We found that four mutations, namely beta+ IVS-1 nt 110, beta zero IVS-1 nt, beta+ IVS-1 nt 6, and beta+ IVS-2 nt 745 were prevalent, accounting for 69.9%, 11.7%, 8.7%, and 5.6% respectively of the beta thalassaemia chromosomes. This information may help in the organisation of a large scale prevention programme based on fetal diagnosis of beta thalassaemia by DNA analysis in the Turkish population. PMID:3236356

  16. A new perspective on beta-sheet structures using vibrational Raman optical activity: From poly(L-lysine) to the prion protein

    DEFF Research Database (Denmark)

    McColl, L.H.; Blanch, E.W.; Gill, A.C.;

    2003-01-01

    The vibrational Raman optical activity (ROA) spectrum of a polypeptide in a model beta-sheet conformation, that of poly(L-lysine), was measured for the first time, and the alpha-helix --> beta-sheet transition monitored as a function of temperature in H2O and D2O. Although no significant populati...

  17. Dynamic Hysteresis Probes High-{\\beta} Nanolaser Emission Regimes

    CERN Document Server

    Pan, Si Hui; Amili, Abdelkrim El; Vallini, Felipe; Fainman, Yeshaiahu

    2016-01-01

    The quest for an integrated light source that promises high energy efficiency and fast modulation for high-performance photonic circuits has led to the development of room-temperature telecom-wavelength nanoscale laser with high spontaneous emission factors, \\beta. The coherence characterization of this type of lasers is inherently difficult with the conventional measurement of output light intensity versus input pump intensity due to the diminishing kink in the measurement curve. We demonstrate the transition from chaotic to coherent emission of a high-{\\beta} pulse-pump metallo-dielectric nanolaser can be determined by examining the width of a second order intensity correlation peak, which shrinks below and broadens above threshold. Photon fluctuation study, first one ever reported for this type of nanolaser, confirms the validity of this measurement technique. Additionally, we show that the width variation above threshold results from the delayed threshold phenomenon, providing the first indirect observati...

  18. Precision Nuclear Beta Spectroscopy as a Probe for BSM Physics

    Science.gov (United States)

    Sprow, Aaron

    2017-01-01

    The shape of nuclear beta decay spectra is sensitive to new physics such as scalar and tensor currents, and weak magnetism. By selecting an appropriate nuclear species, it is possible to disentangle these effects. 45Ca, which undergoes a predominantly Gamow-Teller transition with an end-point energy of 256 keV, is an excellent probe for tensor couplings. Recently, the 45Ca beta decay spectrum was measured in the Caltech/UCNA 4 π magnetic spectrometer instrumented with large, highly-pixelated Si detectors at the Los Alamos National Laboratory UCN facility. This detection system, in conjunction with an extremely thin foil source preparation, allows for a full reconstruction of events to build a precise spectrum. Preliminary results of the analysis of this data will be presented.

  19. MONDian dynamical modeling of NGC 288 with $\\beta \

    CERN Document Server

    Hernandez, X; Scarpa, R

    2016-01-01

    NGC 288 is a diffuse Galactic globular cluster, it is remarkable in that its low density results in internal accelerations being below the critical MOND $a_{0}$ acceleration throughout. This makes it an ideal testing ground for MONDian gravity, as the details of the largely unknown transition function between the Newtonian and modified regimes become unimportant. Further, exact analytical solutions exist for isothermal spherical equilibrium structures in MOND, allowing for arbitrary values of the anisotropy parameter, $\\beta$. In this paper we use observations of the velocity dispersion profile of NGC 288, which is in fact isothermal, as dynamical constraints on MONDian models for this cluster, where the remaining free parameters are adjusted to fit the observed surface brightness profile. We find the optimal fit requires $\\beta =0$, an isotropic solution with a total mass of $3.5 \\pm 1.1 \\times 10^{4} M_{\\odot}$.

  20. Frequency shifts in an optical lattice clock due to magnetic-dipole and electric-quadrupole transitions.

    Science.gov (United States)

    Taichenachev, A V; Yudin, V I; Ovsiannikov, V D; Pal'chikov, V G; Oates, C W

    2008-11-01

    We report a hitherto undiscovered frequency shift for forbidden J = 0-->J = 0 clock transitions excited in atoms confined to an optical lattice. These shifts result from magnetic-dipole and electric-quadrupole transitions, which have a spatial dependence in an optical lattice that differs from that of the stronger electric-dipole transitions. In combination with the residual translational motion of atoms in an optical lattice, this spatial mismatch leads to a frequency shift via differential energy level spacing in the lattice wells for ground state and excited state atoms. We estimate that this effect could lead to fractional frequency shifts as large as 10(-16), which might prevent lattice-based optical clocks from reaching their predicted performance levels. Moreover, these effects could shift the magic wavelength in lattice clocks in three dimensions by as much as 100 MHz, depending on the lattice configuration.