Strain mediated interaction of adatom dimers
Kappus, Wolfgang
2013-01-01
An earlier model for substrate strain mediated interactions between monomer adatoms is extended to the interaction of monomers with dimers and the interaction of dimers. While monomers (sitting on high symmetric sites) are supposed to create isotropic stress on the substrate, dimers would create anisotropic stress caused by stretching their bond. Resulting interactions are strongly angle dependent and also reflect the elastic anisotropy of the substrate. The applicability of a continuum elast...
DEFF Research Database (Denmark)
Ferrighi, Lara; Madsen, Georg Kent Hellerup; Hammer, Bjørk
2010-01-01
The interaction energies of a series of n-alkane dimers, from methane to decane, have been investigated with Density Functional Theory (DFT), using the MGGA-M06-L density functional. The results are compared both to the available wavefunction-based values as well as to dispersion corrected DFT...... values. The MGGA-M06-L density functional is a semi-local functional designed and has proven to provide accurate estimates of dispersion interactions for several systems at moderate computational cost. In the present application, it reproduces the trends obtained by the more expensive wavefunction...
International Nuclear Information System (INIS)
Froissart, Marcel
1976-01-01
Strong interactions are introduced by their more obvious aspect: nuclear forces. In hadron family, the nucleon octet, OMEGA - decuplet, and quark triply are successively considered. Pion wave having been put at the origin of nuclear forces, low energy phenomena are described, the force being explained as an exchange of structure corresponding to a Regge trajectory in a variable rotating state instead of the exchange of a well defined particle. At high energies the concepts of pomeron, parton and stratons are introduced, pionization and fragmentation are briefly differentiated [fr
Testing strong interaction theories
International Nuclear Information System (INIS)
Ellis, J.
1979-01-01
The author discusses possible tests of the current theories of the strong interaction, in particular, quantum chromodynamics. High energy e + e - interactions should provide an excellent means of studying the strong force. (W.D.L.)
Itoh, Tamitake; Yamamoto, Yuko S.
2017-11-01
Electronic transition rates of a molecule located at a crevasse or a gap of a plasmonic nanoparticle (NP) dimer are largely enhanced up to the factor of around 106 due to electromagnetic (EM) coupling between plasmonic and molecular electronic resonances. The coupling rate is determined by mode density of the EM fields at the crevasse and the oscillator strength of the local electronic resonance of a molecule. The enhancement by EM coupling at a gap of plasmonic NP dimer enables us single molecule (SM) Raman spectroscopy. Recently, this type of research has entered a new regime wherein EM enhancement effects cannot be treated by conventional theorems, namely EM mechanism. Thus, such theorems used for the EM enhancement effect should be re-examined. We here firstly summarize EM mechanism by using surface-enhanced Raman scattering (SERS), which is common in EM enhancement phenomena. Secondly, we focus on recent two our studies on probing SM fluctuation by SERS within the spatial resolution of sub-nanometer scales. Finally, we discuss the necessity of re-examining the EM mechanism with respect to two-fold breakdowns of the weak coupling assumption: the breakdown of Kasha's rule induced by the ultra-fast plasmonic de-excitation and the breakdown of the weak coupling by EM coupling rates exceeding both the plasmonic and molecular excitonic dephasing rates.
Strongly interacting Fermi gases
Directory of Open Access Journals (Sweden)
Bakr W.
2013-08-01
Full Text Available Strongly interacting gases of ultracold fermions have become an amazingly rich test-bed for many-body theories of fermionic matter. Here we present our recent experiments on these systems. Firstly, we discuss high-precision measurements on the thermodynamics of a strongly interacting Fermi gas across the superfluid transition. The onset of superfluidity is directly observed in the compressibility, the chemical potential, the entropy, and the heat capacity. Our measurements provide benchmarks for current many-body theories on strongly interacting fermions. Secondly, we have studied the evolution of fermion pairing from three to two dimensions in these gases, relating to the physics of layered superconductors. In the presence of p-wave interactions, Fermi gases are predicted to display toplogical superfluidity carrying Majorana edge states. Two possible avenues in this direction are discussed, our creation and direct observation of spin-orbit coupling in Fermi gases and the creation of fermionic molecules of 23Na 40K that will feature strong dipolar interactions in their absolute ground state.
Strongly interacting Higgs bosons
International Nuclear Information System (INIS)
Appelquist, T.; Bernard, C.
1980-01-01
The sensitivity of present-energy weak interactions to a strongly interacting heavy-Higgs-boson sector is discussed. The gauged nonlinear sigma model, which is the limit of the linear model as the Higgs-boson mass goes to infinity, is used to organize and catalogue all possible heavy-Higgs-boson effects. As long as the SU(2)/sub L/ x SU(2)/sub R/ symmetry of the Higgs sector is preserved, these effects are found to be small, of the order of the square of the gauge coupling times logarithms (but not powers) of the Higgs-boson mass divided by the W mass. We work in the context of a simplified model with gauge group SU(2)/sub L/; the extension to SU(2)/sub L/ x U(1) is briefly discussed
Strong-interaction nonuniversality
International Nuclear Information System (INIS)
Volkas, R.R.; Foot, R.; He, X.; Joshi, G.C.
1989-01-01
The universal QCD color theory is extended to an SU(3) 1 direct product SU(3) 2 direct product SU(3) 3 gauge theory, where quarks of the ith generation transform as triplets under SU(3)/sub i/ and singlets under the other two factors. The usual color group is then identified with the diagonal subgroup, which remains exact after symmetry breaking. The gauge bosons associated with the 16 broken generators then form two massive octets under ordinary color. The interactions between quarks and these heavy gluonlike particles are explicitly nonuniversal and thus an exploration of their physical implications allows us to shed light on the fundamental issue of strong-interaction universality. Nonuniversality and weak flavor mixing are shown to generate heavy-gluon-induced flavor-changing neutral currents. The phenomenology of these processes is studied, as they provide the major experimental constraint on the extended theory. Three symmetry-breaking scenarios are presented. The first has color breaking occurring at the weak scale, while the second and third divorce the two scales. The third model has the interesting feature of radiatively induced off-diagonal Kobayashi-Maskawa matrix elements
Strong interaction phenomenology
International Nuclear Information System (INIS)
Giffon, M.
1989-01-01
A brief review of high energy hadronic data (Part I)is followed by an introduction to the standard (Weinberg Salam Glashow) model of electroweak interactions and its extension to the hadrons (Part II). Rudiments of QCD and of the parton model area given in Part III together with a quick review of the spectroscopy of heavy flavours whereas Part IV is devoted to the introduction to deep inelastic scattering and to the so-called EMC effects. (author)
Pair Interaction of Catalytical Sphere Dimers in Chemically Active Media
Directory of Open Access Journals (Sweden)
Jing-Min Shi
2018-01-01
Full Text Available We study the pair dynamics of two self-propelled sphere dimers in the chemically active medium in which a cubic autocatalytic chemical reaction takes place. Concentration gradient around the dimer, created by reactions occurring on the catalytic sphere surface and responsible for the self-propulsion, is greatly influenced by the chemical activities of the environment. Consequently, the pair dynamics of two dimers mediated by the concentration field are affected. In the particle-based mesoscopic simulation, we combine molecular dynamics (MD for potential interactions and reactive multiparticle collision dynamics (RMPC for solvent flow and bulk reactions. Our results indicate three different configurations between a pair of dimers after the collision, i.e., two possible scenarios of bound dimer pairs and one unbound dimer pair. A phase diagram is sketched as a function of the rate coefficients of the environment reactions. Since the pair interactions are the basic elements of larger scale systems, we believe the results may shed light on the understanding of the collective dynamics.
Study of molybdenum(VI) dimerization equilibrium in strongly acidic medium
International Nuclear Information System (INIS)
Esbelin, E.
2000-01-01
Molybdenum (VI) was investigated spectro-photometrically in non complexing and strongly acidic medium for the first time by Krumenacker. Cationic species of molybdenum were identified by electrophoresis on cellulose paper in highly acidic solutions. From these early results using absorption spectrophotometry, Krumenacker postulated the condensation of molybdenum in this medium. He studied the polymeric species by measuring diffusion coefficients and identified the polymeric form as a dimer. He described the system by equations (1) and (2). Cruywagen later added two equations (3) and (4) to supplement the description of the system. The aim of this work was to re-examine the conditional dimerization equilibrium between the various species of molybdenum(VI) in strongly acid medium by focussing on the influence of the medium. All Mo solution concentrations were analyzed by ICP-AES. Absorbance of the solutions were measured with a VARIAN model CARY5 spectrophotometer in double beam mode with air as reference; blank solutions contained all reagents except molybdenum. The quartz cell path length was 1 mm. The dimerization of monomeric molybdenum(VI) was investigated spectro-photometrically at perchloric acid concentrations of 0.5, 1.0, 2.0 and 3 M at 25 deg C. Two absorption bands at 215 and 245 nm were observed and attributed to monomeric and dimeric forms respectively. The variations in the conditional molar absorption coefficient of molybdenum with total molybdenum(VI) concentration is indicative of several molybdenum forms involved in the total absorbance. Dimerization equilibrium is defined by equation (5). By using the additivity of absorbance and mass conservation of molybdenum, a descriptive equation of the 'spectrochemical' system is developed. This equation is linearized into two forms (6) et (7). From them, two refinement methods were used to estimate the conditional dimerization constant K' d for various medium concentrations. This numerical procedure offers
Conformational study of the protegrin-1 (PG-1 dimer interaction with lipid bilayers and its effect
Directory of Open Access Journals (Sweden)
Nussinov Ruth
2007-04-01
Full Text Available Abstract Background Protegrin-1 (PG-1 is known as a potent antibiotic peptide; it prevents infection via an attack on the membrane surface of invading microorganisms. In the membrane, the peptide forms a pore/channel through oligomerization of multiple subunits. Recent experimental and computational studies have increasingly unraveled the molecular-level mechanisms underlying the interactions of the PG-1 β-sheet motifs with the membrane. The PG-1 dimer is important for the formation of oligomers, ordered aggregates, and for membrane damaging effects. Yet, experimentally, different dimeric behavior has been observed depending on the environment: antiparallel in the micelle environment, and parallel in the POPC bilayer. The experimental structure of the PG-1 dimer is currently unavailable. Results Although the β-sheet structures of the PG-1 dimer are less stable in the bulk water environment, the dimer interface is retained by two intermolecular hydrogen bonds. The formation of the dimer in the water environment implies that the pathway of the dimer invasion into the membrane can originate from the bulk region. In the initial contact with the membrane, both the antiparallel and parallel β-sheet conformations of the PG-1 dimer are well preserved at the amphipathic interface of the lipid bilayer. These β-sheet structures illustrate the conformations of PG-1 dimer in the early stage of the membrane attack. Here we observed that the activity of PG-1 β-sheets on the bilayer surface is strongly correlated with the dimer conformation. Our long-term goal is to provide a detailed mechanism of the membrane-disrupting effects by PG-1 β-sheets which are able to attack the membrane and eventually assemble into the ordered aggregates. Conclusion In order to understand the dimeric effects leading to membrane damage, extensive molecular dynamics (MD simulations were performed for the β-sheets of the PG-1 dimer in explicit water, salt, and lipid bilayers
Strong interactions at high energy
International Nuclear Information System (INIS)
Anselmino, M.
1995-01-01
Spin effects in strong interaction high energy processes are subtle phenomena which involve both short and long distance physics and test perturbative and non perturbative aspects of QCD. Moreover, depending on quantities like interferences between different amplitudes and relative phases, spin observables always test a theory at a fundamental quantum mechanical level; it is then no surprise that spin data are often difficult to accommodate within the existing models. A report is made on the main issues and contributions discussed in the parallel Session on the open-quote open-quote Strong interactions at high energy close-quote close-quote in this Conference. copyright 1995 American Institute of Physics
The colours of strong interaction
International Nuclear Information System (INIS)
1995-01-01
The aim of this session is to draw a consistent framework about the different ways to consider strong interaction. A large part is dedicated to theoretical work and the latest experimental results obtained at the first electron collider HERA are discussed. (A.C.)
Fe65-PTB2 Dimerization Mimics Fe65-APP Interaction
Directory of Open Access Journals (Sweden)
Lukas P. Feilen
2017-05-01
Full Text Available Physiological function and pathology of the Alzheimer’s disease causing amyloid precursor protein (APP are correlated with its cytosolic adaptor Fe65 encompassing a WW and two phosphotyrosine-binding domains (PTBs. The C-terminal Fe65-PTB2 binds a large portion of the APP intracellular domain (AICD including the GYENPTY internalization sequence fingerprint. AICD binding to Fe65-PTB2 opens an intra-molecular interaction causing a structural change and altering Fe65 activity. Here we show that in the absence of the AICD, Fe65-PTB2 forms a homodimer in solution and determine its crystal structure at 2.6 Å resolution. Dimerization involves the unwinding of a C-terminal α-helix that mimics binding of the AICD internalization sequence, thus shielding the hydrophobic binding pocket. Specific dimer formation is validated by nuclear magnetic resonance (NMR techniques and cell-based analyses reveal that Fe65-PTB2 together with the WW domain are necessary and sufficient for dimerization. Together, our data demonstrate that Fe65 dimerizes via its APP interaction site, suggesting that besides intra- also intermolecular interactions between Fe65 molecules contribute to homeostatic regulation of APP mediated signaling.
Fe65-PTB2 Dimerization Mimics Fe65-APP Interaction.
Feilen, Lukas P; Haubrich, Kevin; Strecker, Paul; Probst, Sabine; Eggert, Simone; Stier, Gunter; Sinning, Irmgard; Konietzko, Uwe; Kins, Stefan; Simon, Bernd; Wild, Klemens
2017-01-01
Physiological function and pathology of the Alzheimer's disease causing amyloid precursor protein (APP) are correlated with its cytosolic adaptor Fe65 encompassing a WW and two phosphotyrosine-binding domains (PTBs). The C-terminal Fe65-PTB2 binds a large portion of the APP intracellular domain (AICD) including the GYENPTY internalization sequence fingerprint. AICD binding to Fe65-PTB2 opens an intra-molecular interaction causing a structural change and altering Fe65 activity. Here we show that in the absence of the AICD, Fe65-PTB2 forms a homodimer in solution and determine its crystal structure at 2.6 Å resolution. Dimerization involves the unwinding of a C-terminal α-helix that mimics binding of the AICD internalization sequence, thus shielding the hydrophobic binding pocket. Specific dimer formation is validated by nuclear magnetic resonance (NMR) techniques and cell-based analyses reveal that Fe65-PTB2 together with the WW domain are necessary and sufficient for dimerization. Together, our data demonstrate that Fe65 dimerizes via its APP interaction site, suggesting that besides intra- also intermolecular interactions between Fe65 molecules contribute to homeostatic regulation of APP mediated signaling.
Strongly interacting light dark matter
International Nuclear Information System (INIS)
Bruggisser, Sebastian; Riva, Francesco; Urbano, Alfredo
2016-07-01
In the presence of approximate global symmetries that forbid relevant interactions, strongly coupled light Dark Matter (DM) can appear weakly coupled at small-energy and generate a sizable relic abundance. Fundamental principles like unitarity restrict these symmetries to a small class, where the leading interactions are captured by effective operators up to dimension-8. Chiral symmetry, spontaneously broken global symmetries and non-linearly realized supersymmetry are examples of this. Their DM candidates (composite fermions, pseudo-Nambu-Goldstone Bosons and Goldstini) are interesting targets for LHC missing-energy searches.
Scalar strong interaction hadron theory
Hoh, Fang Chao
2015-01-01
The scalar strong interaction hadron theory, SSI, is a first principles' and nonlocal theory at quantum mechanical level that provides an alternative to low energy QCD and Higgs related part of the standard model. The quark-quark interaction is scalar rather than color-vectorial. A set of equations of motion for mesons and another set for baryons have been constructed. This book provides an account of the present state of a theory supposedly still at its early stage of development. This work will facilitate researchers interested in entering into this field and serve as a basis for possible future development of this theory.
Effective lagrangian for strong interactions
International Nuclear Information System (INIS)
Jain, P.
1988-01-01
We attempt to construct a realistic phenomenological Lagrangian in order to describe strong interactions. This is in general a very complicated problem and we shall explore its various aspects. We first include the vector mesons by writing down the most general chiral invariant terms proportional to the Levi-Civita symbol ε μναβ . These terms involve three unknown coefficients, which are calculated by using the experimental results of strong interaction processes. We then calculate the static nucleon properties by finding the solitonic excitations of this model. The results turn out to be, as is also the case for most other vector-pseudoscalar Lagrangians, better than the Skyrme model but are still somewhat different from the experiments. Another aspect that we shall study is the incorporation of scale anomaly of QCD into the Skyrme model. We thus introduce a scalar glueball in our Lagrangian. Here we find an interesting result that the effective glue field dynamically forms a bag for the soliton. Depending on the values of the parameters, we get either a deep bag or a shallow bag. However by including the scalar meson, we find that to get realistic scalar sector we must have the shallow bag. Finally we show some intriguing connections between the chiral quark model, in which the nucleon is described as a solitonic excitation, and the ordinary potential binding quark model
Strongly interacting W's and Z's
International Nuclear Information System (INIS)
Gaillard, M.K.
1984-01-01
The study focussed primarily on the dynamics of a strongly interacting W, Z(SIW) sector, with the aim of sharpening predictions for total W, Z yield and W, Z multiplicities expected from WW fusion for various scenarios. Specific issues raised in the context of the general problem of modeling SIW included the specificity of the technicolor (or, equivalently, QCD) model, whether or not a composite scalar model can be evaded, and whether the standard model necessarily implies an I = J = O state (≅ Higgs particle) that is relatively ''light'' (M ≤ hundreds of TeV). The consensus on the last issue was that existing arguments are inconclusive. While the author shall briefly address compositeness and alternatives to the technicolor model, quantitative estimates will be of necessity based on technicolor or an extrapolation of pion data
International Nuclear Information System (INIS)
Hirayama, H.; Mizuno, H.; Yoshida, R.
2002-01-01
We studied Ge coverage (θ Ge ) dependent quenching, reactivation of the flip-flop motion, and interaction with dimer vacancy lines (DVLs) of dimers on Ge/Si(001) surfaces using a scanning tunneling microscope (STM) combined with a molecular beam epitaxy apparatus. Deposition of ∼0.3 ML (monolayer) Ge quenched the flip-flop motion, making all dimers asymmetric. Further deposition introduced DVLs at θ Ge ≥∼0.5 ML, and symmetric dimer domains appeared again locally at θ≥1.5 ML. High-resolution STM images indicated that asymmetric dimer rows always invert their phase in alternation with buckled dimer's up-end at the DVLs. Low-temperature STM images indicated that the symmetric dimer domains were due to flip-flopping of asymmetric dimers activated by large θ Ge at room temperature. The symmetric dimer domains extended along the dimer rows over the DVLs due to the phase correlation
Strongly interacting photons and atoms
International Nuclear Information System (INIS)
Alge, W.
1999-05-01
This thesis contains the main results of the research topics I have pursued during the my PhD studies at the University of Innsbruck and partly in collaboration with the Institut d' Optique in Orsay, France. It is divided into three parts. The first and largest part discusses the possibility of using strong standing waves as a tool to cool and trap neutral atoms in optical cavities. This is very important in the field of nonlinear optics where several successful experiments with cold atoms in cavities have been performed recently. A discussion of the optical parametric oscillator in a regime where the nonlinearity dominates the evolution is the topic of the second part. We investigated mainly the statistical properties of the cavity output of the three interactive cavity modes. Very recently a system has been proposed which promises fantastic properties. It should exhibit a giant Kerr nonlinearity with negligible absorption thus leading to a photonic turnstile device based on cold atoms in cavity. We have shown that this model suffers from overly simplistic assumptions and developed several more comprehensive approaches to study the behavior of this system. Apart from the division into three parts of different contents the thesis is divided into publications, supplements and invisible stuff. The intention of the supplements is to reach researchers which work in related areas and provide them with more detailed information about the concepts and the numerical tools we used. It is written especially for diploma and PhD students to give them a chance to use the third part of our work which is actually the largest one. They consist of a large number of computer programs we wrote to investigate the behavior of the systems in parameter regions where no hope exists to solve the equations analytically. (author)
Strong interactions in low dimensions
Baeriswyl, D
2007-01-01
This book provides an attempt to convey the colorful facets of condensed matter systems with reduced dimensionality. Some of the specific features predicted for interacting one-dimensional electron systems, such as charge- and spin-density waves, have been observed in many quasi-one-dimensional materials. The two-dimensional world is even richer: besides d-wave superconductivity and the Quantum Hall Effect - perhaps the most spectacular phases explored during the last two decades - many collective charge and spin states have captured the interest of researchers, such as charge stripes or spont
Remnants of strong tidal interactions
International Nuclear Information System (INIS)
Mcglynn, T.A.
1990-01-01
This paper examines the properties of stellar systems that have recently undergone a strong tidal shock, i.e., a shock which removes a significant fraction of the particles in the system, and where the shocked system has a much smaller mass than the producer of the tidal field. N-body calculations of King models shocked in a variety of ways are performed, and the consequences of the shocks are investigated. The results confirm the prediction of Jaffe for shocked systems. Several models are also run where the tidal forces on the system are constant, simulating a circular orbit around a primary, and the development of tidal radii under these static conditions appears to be a mild process which does not dramatically affect material that is not stripped. The tidal radii are about twice as large as classical formulas would predict. Remnant density profiles are compared with a sample of elliptical galaxies, and the implications of the results for the development of stellar populations and galaxies are considered. 38 refs
Zhang, C.; Feng, T.; Raabe, N.; Rottke, H.
2018-02-01
Strong-field ionization (SFI) of the homonuclear noble gas dimer Xe2 is investigated and compared with SFI of the Xe atom and of the ArXe heteronuclear dimer by using ultrashort Ti:sapphire laser pulses and photoelectron momentum spectroscopy. The large separation of the two nuclei of the dimer allows the study of two-equivalent-center interference effects on the photoelectron momentum distribution. Comparing the experimental results with a new model calculation, which is based on the strong-field approximation, actually reveals the influence of interference. Moreover, the comparison indicates that the presence of closely spaced gerade and ungerade electronic state pairs of the Xe2 + ion at the Xe2 ionization threshold, which are strongly dipole coupled, affects the photoelectron momentum distribution.
Physics challenges in the strong interactions
International Nuclear Information System (INIS)
Ellis, S.D.
1992-01-01
The study of strong interactions is now a mature field for which scientist now know that the correct underlying theory is QCD. Here, an overview of the challenges to be faced in the area of the strong interactions during the 1990's is presented. As an illustrative example special attention is given to the analysis of jets as studied at hadron colliders
Physics challenges in the strong interactions
Energy Technology Data Exchange (ETDEWEB)
Ellis, S.D. [Univ. of Washington, Seattle (United States)
1992-12-31
The study of strong interactions is now a mature field for which scientist now know that the correct underlying theory is QCD. Here, an overview of the challenges to be faced in the area of the strong interactions during the 1990`s is presented. As an illustrative example special attention is given to the analysis of jets as studied at hadron colliders.
Algebra of strong and electroweak interactions
International Nuclear Information System (INIS)
Bolokhov, S.V.; Vladimirov, Yu.S.
2004-01-01
The algebraic approach to describing the electroweak and strong interactions is considered within the frames of the binary geometrophysics, based on the principles of the Fokker-Feynman direct interparticle interaction theories of the Kaluza-Klein multidimensional geometrical models and the physical structures theory. It is shown that in this approach the electroweak and strong elementary particles interaction through the intermediate vector bosons, are characterized by the subtypes of the algebraic classification of the complex 3 x 3-matrices [ru
DEFF Research Database (Denmark)
Petaja, Tuukka; Sipila, Mikko; Paasonen, Pauli
2011-01-01
rate was clearly higher than the measured new particle formation rate at similar to 1.5 nmsuggesting that the rate limiting step for the nucleation takes place after the dimerization step. The quantum chemical calculations suggested that even in the ultraclean conditions there exist (a) stabilizing...... compound(s) with (a) concentration(s) high enough to prevent the dimer evaporation. Such a stabilizing compound should be abundant enough in any natural environment and would therefore not limit the formation of sulfuric acid dimers in the atmosphere....
Physics challenges in the strong interactions
Energy Technology Data Exchange (ETDEWEB)
Ellis, S.D.
1991-01-01
An overview of the challenges to be faced in the area of the strong interactions during the 1990`s is presented. As an illustrative example special attention is given to the analysis of jets as studied at hadron colliders.
Physics challenges in the strong interactions
International Nuclear Information System (INIS)
Ellis, S.D.
1991-01-01
An overview of the challenges to be faced in the area of the strong interactions during the 1990's is presented. As an illustrative example special attention is given to the analysis of jets as studied at hadron colliders
Strong interaction effects in hadronic atoms
International Nuclear Information System (INIS)
Kaufmann, W.B.
1977-01-01
The WKB method is applied to the calculation of strong interaction-induced level widths and shifts of hadronic atoms. The calculation, while elementary enough for undergraduate quantum mechanics students, gives a good account of kaonic and antiprotonic atom data
The Charm and Beauty of Strong Interactions
El-Bennich, Bruno
2018-01-01
We briefly review common features and overlapping issues in hadron and flavor physics focussing on continuum QCD approaches to heavy bound states, their mass spectrum and weak decay constants in different strong interaction models.
Dual field theory of strong interactions
International Nuclear Information System (INIS)
Akers, D.
1987-01-01
A dual field theory of strong interactions is derived from a Lagrangian of the Yang-Mills and Higgs fields. The existence of a magnetic monopole of mass 2397 MeV and Dirac charge g = (137/2)e is incorporated into the theory. Unification of the strong, weak, and electromagnetic forces is shown to converge at the mass of the intermediate vector boson W/sup +/-/. The coupling constants of the strong and weak interactions are derived in terms of the fine-structure constant α = 1/137
A theory of the strong interactions
International Nuclear Information System (INIS)
Gross, D.J.
1979-01-01
The most promising candidate for a fundamental microscopic theory of the strong interactions is a gauge theory of colored quarks-Quantum Chromodynamics (QCD). There are many excellent reasons for believing in this theory. It embodies the broken symmetries, SU(3) and chiral SU(3)xSU(3), of the strong interactions and reflects the success of (albeit crude) quark models in explaining the spectrum of the observed hadrons. The hidden quantum number of color, necessary to account for the quantum numbers of the low lying hadrons, plays a fundamental role in this theory as the SU(3) color gauge vector 'gluons' are the mediators of the strong interactions. The absence of physical quark states can be 'explained' by the hypothesis of color confinement i.e. that hadrons are permanently bound in color singlet bound states. Finally this theory is unique in being asymptotically free, thus accounting for the almost free field theory behvior of quarks observed at short distances. (Auth.)
Interaction of strong electromagnetic fields with atoms
International Nuclear Information System (INIS)
Brandi, H.S.; Davidovich, L.; Zagury, N.
1982-06-01
Several non-linear processes involvoing the interaction of atoms with strong laser fields are discussed, with particular emphasis on the ionization problem. Non-perturbative methods which have been proposed to tackle this problem are analysed, and shown to correspond to an expansion in the intra-atomic potential. The relation between tunneling and multiphoton absorption as ionization mechanisms, and the generalization of Einstein's photoelectric equation to the strong-field case are discussed. (Author) [pt
International Nuclear Information System (INIS)
Al-Mawsawi, Laith Q.; Hombrouck, Anneleen; Dayam, Raveendra; Debyser, Zeger; Neamati, Nouri
2008-01-01
HIV-1 integrase (IN) is an essential enzyme for viral infection. Here, we report an extensive π electron orbital interaction between four amino acids, W132, M178, F181 and F185, located at the dimeric interface of IN that is critical for the strand transfer activity alone. Catalysis of nine different mutant IN proteins at these positions were evaluated. Whereas the 3'-processing activity is predominantly strong, the strand transfer activity of each enzyme was completely dependent on an intact π electron orbital interaction at the dimeric interface. Four representative IN mutants were constructed in the context of the infectious NL4.3 HIV-1 viral clone. Whereas viruses with an intact π electron orbital interaction at the IN dimeric interface replicated comparable to wild type, viruses containing an abolished π interaction were non-infectious. Q-PCR analysis of viral DNA forms during viral replication revealed pleiotropic effects of most mutations. We hypothesize that the π interaction is a critical contact point for the assembly of functional IN multimeric complexes, and that IN multimerization is required for a functional pre-integration complex. The rational design of small molecule inhibitors targeting the disruption of this π-π interaction should lead to powerful anti-retroviral drugs
Physics challenges in the strong interactions
Energy Technology Data Exchange (ETDEWEB)
Ellis, S.D.
1991-01-01
An overview of the challenges to be faced in the area of the strong interactions during the 1990's is presented. As an illustrative example special attention is given to the analysis of jets as studied at hadron colliders.
Unification of electromagnetic, strong and weak interaction
International Nuclear Information System (INIS)
Duong Van Phi; Duong Anh Duc
1993-09-01
The Unification of Electromagnetic, Strong and Weak Interactions is realized in the framework of the Quantum Field Theory, established in an 8-dimensional Unified Space. Two fundamental, spinor and vector field equations are considered. The first of the matter particles and the second is of the gauge particles. Interaction Lagrangians are formed from the external and internal currents and the external and internal vector field operators. Generators of the local gauge transformations are the combinations of the matrices of the first field equation. (author). 15 refs
Super symmetry in strong and weak interactions
International Nuclear Information System (INIS)
Seshavatharam, U.V.S.; Lakshminarayana, S.
2010-01-01
For strong interaction two new fermion mass units 105.32 MeV and 11450 MeV are assumed. Existence of "Integral charge quark bosons", "Integral charge effective quark fermions", "Integral charge (effective) quark fermi-gluons" and "Integral charge quark boso-gluons" are assumed and their masses are estimated. It is noticed that, characteristic nuclear charged fermion is X s · 105.32 = 938.8 MeV and corresponding charged boson is X s (105.32/x) = 415.0 where X s = 8.914 is the inverse of the strong coupling constant and x = 2.26234 is a new number by using which "super symmetry" can be seen in "strong and weak" interactions. 11450 MeV fermion and its boson of mass = 11450/x = 5060 MeV plays a crucial role in "sub quark physics" and "weak interaction". 938.8 MeV strong fermion seems to be the proton. 415 MeV strong boson seems to be the mother of the presently believed 493,496 and 547 MeV etc, strange mesons. With 11450 MeV fermion "effective quark-fermi-gluons" and with 5060 MeV boson "quark boso-gluon masses" are estimated. "Effective quark fermi-gluons" plays a crucial role in ground state charged baryons mass generation. Light quark bosons couple with these charged baryons to form doublets and triplets. "Quark boso-gluons" plays a crucial role in ground state neutral and charged mesons mass generation. Fine and super-fine rotational levels can be given by [I or (I/2)] power(1/4) and [I or (I/2)] power(1/12) respectively. Here, I = n(n+1) and n = 1, 2, 3, … (author)
Strongly interacting matter in magnetic fields
Landsteiner, Karl; Schmitt, Andreas; Yee, Ho-Ung
2013-01-01
The physics of strongly interacting matter in an external magnetic field is presently emerging as a topic of great cross-disciplinary interest for particle, nuclear, astro- and condensed matter physicists. It is known that strong magnetic fields are created in heavy ion collisions, an insight that has made it possible to study a variety of surprising and intriguing phenomena that emerge from the interplay of quantum anomalies, the topology of non-Abelian gauge fields, and the magnetic field. In particular, the non-trivial topological configurations of the gluon field induce a non-dissipative electric current in the presence of a magnetic field. These phenomena have led to an extended formulation of relativistic hydrodynamics, called chiral magnetohydrodynamics. Hitherto unexpected applications in condensed matter physics include graphene and topological insulators. Other fields of application include astrophysics, where strong magnetic fields exist in magnetars and pulsars. Last but not least, an important ne...
Strong plasmonic enhancement of single molecule photostability in silver dimer optical antennas
Directory of Open Access Journals (Sweden)
Kaminska Izabela
2018-02-01
Full Text Available Photobleaching is an effect terminating the photon output of fluorophores, limiting the duration of fluorescence-based experiments. Plasmonic nanoparticles (NPs can increase the overall fluorophore photostability through an enhancement of the radiative rate. In this work, we use the DNA origami technique to arrange a single fluorophore in the 12-nm gap of a silver NP dimer and study the number of emitted photons at the single molecule level. Our findings yielded a 30× enhancement in the average number of photons emitted before photobleaching. Numerical simulations are employed to rationalize our results. They reveal the effect of silver oxidation on decreasing the radiative rate enhancement.
A strongly interacting polaritonic quantum dot
Jia, Ningyuan; Schine, Nathan; Georgakopoulos, Alexandros; Ryou, Albert; Clark, Logan W.; Sommer, Ariel; Simon, Jonathan
2018-06-01
Polaritons are promising constituents of both synthetic quantum matter1 and quantum information processors2, whose properties emerge from their components: from light, polaritons draw fast dynamics and ease of transport; from matter, they inherit the ability to collide with one another. Cavity polaritons are particularly promising as they may be confined and subjected to synthetic magnetic fields controlled by cavity geometry3, and furthermore they benefit from increased robustness due to the cavity enhancement in light-matter coupling. Nonetheless, until now, cavity polaritons have operated only in a weakly interacting mean-field regime4,5. Here we demonstrate strong interactions between individual cavity polaritons enabled by employing highly excited Rydberg atoms as the matter component of the polaritons. We assemble a quantum dot composed of approximately 150 strongly interacting Rydberg-dressed 87Rb atoms in a cavity, and observe blockaded transport of photons through it. We further observe coherent photon tunnelling oscillations, demonstrating that the dot is zero-dimensional. This work establishes the cavity Rydberg polariton as a candidate qubit in a photonic information processor and, by employing multiple resonator modes as the spatial degrees of freedom of a photonic particle, the primary ingredient to form photonic quantum matter6.
New strong interactions above the electroweak scale
International Nuclear Information System (INIS)
White, A.R.
1994-01-01
Theoretical arguments for a new higher-color quark sector, based on Pomeron physics in QCD, are briefly described. The electroweak symmetry-breaking, Strong CP conservation, and electroweak scale CP violation, that is naturally produced by this sector is also outlined. A further consequence is that above the electroweak scale there will be a radical change in the strong interaction. Electroweak states, in particular multiple W's and Z's, and new, semi-stable, very massive, baryons, will be commonly produced. The possible correlation of expected phenomena with a wide range of observed Cosmic Ray effects at and above the primary spectrum knee is described. Related phenomena that might be seen in the highest energy hard scattering events at the Fermilab Tevatron, some of which could be confused with top production, are also briefly discussed
Many Body Structure of Strongly Interacting Systems
Arenhövel, Hartmuth; Drechsel, Dieter; Friedrich, Jörg; Kaiser, Karl-Heinz; Walcher, Thomas; Symposium on 20 Years of Physics at the Mainz Microtron MAMI
2006-01-01
This carefully edited proceedings volume provides an extensive review and analysis of the work carried out over the past 20 years at the Mainz Microtron (MAMI). This research centered around the application of Quantum Chromodynamics in the strictly nonperturbative regime at hadronic scales of about 1 fm. Due to the many degrees of freedom in hadrons at this scale the leitmotiv of this research is "Many body structure of strongly interacting systems". Further, an outlook on the research with the forthcoming upgrade of MAMI is given. This volume is an authoritative source of reference for everyone interested in the field of the electro-weak probing of the structure of hadrons.
Strong Interaction Studies with PANDA at FAIR
Schönning, Karin
2016-10-01
The Facility for Antiproton and Ion Research (FAIR) in Darmstadt, Germany, provides unique possibilities for a new generation of nuclear-, hadron- and atomic physics experiments. The future PANDA experiment at FAIR will offer a broad physics programme with emphasis on different aspects of hadron physics. Understanding the strong interaction in the perturbative regime remains one of the greatest challenges in contemporary physics and hadrons provide several important keys. In these proceedings, PANDA will be presented along with some high-lights of the planned physics programme.
Strong Interaction Studies with PANDA at FAIR
International Nuclear Information System (INIS)
Schönning, Karin
2016-01-01
The Facility for Antiproton and Ion Research (FAIR) in Darmstadt, Germany, provides unique possibilities for a new generation of nuclear-, hadron- and atomic physics experiments. The future PANDA experiment at FAIR will offer a broad physics programme with emphasis on different aspects of hadron physics. Understanding the strong interaction in the perturbative regime remains one of the greatest challenges in contemporary physics and hadrons provide several important keys. In these proceedings, PANDA will be presented along with some high-lights of the planned physics programme
Strongly interacting Higgs sector without technicolor
International Nuclear Information System (INIS)
Liu Chuan; Kuti, J.
1994-12-01
Simulation results are presented on Higgs mass calculations in the spontaneously broken phase of the Higgs sector in the minimal Standard Model with a higher derviative regulator. A heavy Higgs particle is found in the TeV mass range in the presence of a complex conjugate ghost pair at higher energies. The ghost pair evades easy experimental detection. As a finite and unitary theory in the continuum, this model serves as an explicit and simple example of a strong interacting Higgs sector without technicolor. (orig.)
Strong Interactions Physics at BaBar
Energy Technology Data Exchange (ETDEWEB)
Pioppi, M.
2005-03-14
Recent results obtained by BABAR experiment and related to strong interactions physics are presented, with particular attention to the extraction of the first four hadronic-mass moments and the first three lepton-energy moments in semileptonic decays. From a simultaneous fit to the moments, the CKM element |V{sub cb}|, the inclusive B {yields} X{sub c}lv and other heavy quark parameters are derived. The second topic is the ambiguity-free measurement of cos(2{beta}) in B {yields} J/{Psi}K* decays. With approximately 88 million of B{bar B} pairs, negative solutions for cos(2{beta}) are excluded at 89%.
Strong Interactive Massive Particles from a Strong Coupled Theory
DEFF Research Database (Denmark)
Yu. Khlopov, Maxim; Kouvaris, Christoforos
2008-01-01
(-2). These excessive techniparticles are all captured by $^4He$, creating \\emph{techni-O-helium} $tOHe$ ``atoms'', as soon as $^4He$ is formed in Big Bang Nucleosynthesis. The interaction of techni-O-helium with nuclei opens new paths to the creation of heavy nuclei in Big Bang Nucleosynthesis. Due...
Finite temperature system of strongly interacting baryons
International Nuclear Information System (INIS)
Bowers, R.L.; Gleeson, A.M.; Pedigo, R.D.; Wheeler, J.W.
1976-07-01
A fully relativistic finite temperature many body theory is constructed and used to examine the bulk properties of a system of strongly interacting baryons. The strong interactions are described by a two parameter phenomenological model fit to a simple description of nuclear matter at T = 0. The zero temperature equation of state for such a system which has already been discussed in the literature was developed to give a realistic description of nuclear matter. The model presented here is the exact finite temperature extension of that model. The effect of the inclusion of baryon pairs for T greater than or equal to 2mc 2 /k is discussed in detail. The phase transition identified with nuclear matter vanishes for system temperatures in excess of T/sub C/ = 1.034 x 10 11 0 K. All values of epsilon (P,T) correspond to systems that are causal in the sense that the locally determined speed of sound never exceeds the speed of light
Finite temperature system of strongly interacting baryons
Energy Technology Data Exchange (ETDEWEB)
Bowers, R.L.; Gleeson, A.M.; Pedigo, R.D.; Wheeler, J.W.
1976-07-01
A fully relativistic finite temperature many body theory is constructed and used to examine the bulk properties of a system of strongly interacting baryons. The strong interactions are described by a two parameter phenomenological model fit to a simple description of nuclear matter at T = 0. The zero temperature equation of state for such a system which has already been discussed in the literature was developed to give a realistic description of nuclear matter. The model presented here is the exact finite temperature extension of that model. The effect of the inclusion of baryon pairs for T greater than or equal to 2mc/sup 2//k is discussed in detail. The phase transition identified with nuclear matter vanishes for system temperatures in excess of T/sub C/ = 1.034 x 10/sup 11/ /sup 0/K. All values of epsilon (P,T) correspond to systems that are causal in the sense that the locally determined speed of sound never exceeds the speed of light.
Combinatorial description of space and strong interactions
International Nuclear Information System (INIS)
Zenczykowski, P.
1988-01-01
A reinterpretation is given of a successful phenomenological approach to hadron self-energy effects known as the unitarized quark model. General arguments are given that the proper description of strong interactions may require abandoning the assignment of a primary role to continuous concepts such as position and momentum in favor of discrete ones such as spin or W-spin. The reinterpretation exploits an analogy between the W-spin diagrams occurring in the calculations of hadronic loop effects and the spin network idea of Penrose. A connection between the S-matrix approach to hadron masses and the purely algebraic approach characteristic of the quark model is indicated. Several hadron mass relations generated by a resulting SU(6)/sub w/-group-theoretic expression are presented and discussed. Results of an attempt to generalize the scheme to the description of hadron vertices are reported
Intermolecular interaction potentials of the methane dimer from the local density approximation
International Nuclear Information System (INIS)
Chen Xiangrong; Bai Yulin; Zhu Jun; Yang Xiangdong
2004-01-01
The intermolecular interaction potentials of methane (CH 4 ) dimer are calculated within the density functional theory in the local density approximation (LDA). It is found that the calculated potentials have minima when the intermolecular distance of CH 4 dimer is about 7.0 a.u., which is in good agreement with the experiment. The depth of the potential is 0.017 eV. The results obtained by our LDA calculations seem to agree well with those obtained by MP2, MP3, and CCSD from the Moeller-Plesset and coupled cluster methods by Tsuzuki et al. and with the experimental data
Fornés, José A
2010-01-15
We use the Brownian dynamics with hydrodynamic interactions simulation in order to describe the movement of a elastically coupled dimer Brownian motor in a ratchet potential. The only external forces considered in our system were the load, the random thermal noise and an unbiased thermal fluctuation. For a given set of parameters we observe direct movement against the load force if hydrodynamic interactions were considered.
Transport coefficients of strongly interacting matter
International Nuclear Information System (INIS)
Heckmann, Klaus
2011-01-01
In this thesis, we investigate the dissipative transport phenomena of strongly interacting matter. The special interest is in the shear viscosity and its value divided by entropy density. The performed calculations are based on effective models for Quantum Chromodynamics, mostly focused on the 2-flavor Nambu-Jona-Lasinio model. This allows us to study the hadronic sector as well as the quark sector within one single model. We expand the models up to next-to-leading order in inverse numbers of colors. We present different possibilities of calculating linear transport coefficients and give an overview over qualitative properties as well as over recent ideas concerning ideal fluids. As present methods are not able to calculate the quark two-point function in Minkowski space-time in the self-consistent approximation scheme of the Nambu-Jona-Lasinio model, a new method for this purpose is developed. This self-energy parametrization method is applied to the expansion scheme, yielding the quark spectral function with meson back-coupling effects. The usage of this spectral function in the transport calculation is only one result of this work. We also test the application of different transport approaches in the NJL model, and find an interesting behavior of the shear viscosity at the critical end point of the phase diagram. We also use the NJL model to calculate the viscosity of a pion gas in the dilute regime. After an analysis of other models for pions and their interaction, we find that the NJL-result leads to an important modification of transport properties in comparison with the calculations which purely rely on pion properties in the vacuum. (orig.)
Huang, Yong-Heng; Jankowski, Aleksander; Cheah, Kathryn S E; Prabhakar, Shyam; Jauch, Ralf
2015-05-27
The SOXE transcription factors SOX8, SOX9 and SOX10 are master regulators of mammalian development directing sex determination, gliogenesis, pancreas specification and neural crest development. We identified a set of palindromic SOX binding sites specifically enriched in regulatory regions of melanoma cells. SOXE proteins homodimerize on these sequences with high cooperativity. In contrast to other transcription factor dimers, which are typically rigidly spaced, SOXE group proteins can bind cooperatively at a wide range of dimer spacings. Using truncated forms of SOXE proteins, we show that a single dimerization (DIM) domain, that precedes the DNA binding high mobility group (HMG) domain, is sufficient for dimer formation, suggesting that DIM : HMG rather than DIM:DIM interactions mediate the dimerization. All SOXE members can also heterodimerize in this fashion, whereas SOXE heterodimers with SOX2, SOX4, SOX6 and SOX18 are not supported. We propose a structural model where SOXE-specific intramolecular DIM:HMG interactions are allosterically communicated to the HMG of juxtaposed molecules. Collectively, SOXE factors evolved a unique mode to combinatorially regulate their target genes that relies on a multifaceted interplay between the HMG and DIM domains. This property potentially extends further the diversity of target genes and cell-specific functions that are regulated by SOXE proteins.
Huang, Yong-Heng; Jankowski, Aleksander; Cheah, Kathryn S. E.; Prabhakar, Shyam; Jauch, Ralf
2015-01-01
The SOXE transcription factors SOX8, SOX9 and SOX10 are master regulators of mammalian development directing sex determination, gliogenesis, pancreas specification and neural crest development. We identified a set of palindromic SOX binding sites specifically enriched in regulatory regions of melanoma cells. SOXE proteins homodimerize on these sequences with high cooperativity. In contrast to other transcription factor dimers, which are typically rigidly spaced, SOXE group proteins can bind cooperatively at a wide range of dimer spacings. Using truncated forms of SOXE proteins, we show that a single dimerization (DIM) domain, that precedes the DNA binding high mobility group (HMG) domain, is sufficient for dimer formation, suggesting that DIM : HMG rather than DIM:DIM interactions mediate the dimerization. All SOXE members can also heterodimerize in this fashion, whereas SOXE heterodimers with SOX2, SOX4, SOX6 and SOX18 are not supported. We propose a structural model where SOXE-specific intramolecular DIM:HMG interactions are allosterically communicated to the HMG of juxtaposed molecules. Collectively, SOXE factors evolved a unique mode to combinatorially regulate their target genes that relies on a multifaceted interplay between the HMG and DIM domains. This property potentially extends further the diversity of target genes and cell-specific functions that are regulated by SOXE proteins. PMID:26013289
Strong and Electromagnetic Interactions at SPS Energies
Ribicki, Andrzej
2009-01-01
Particle production in peripheral Pb+Pb collisions has been measured at a beam energy of 158 GeV per nucleon, corresponding to psNN 17.3 GeV. The measurements provide full double differential coverage in a wide range of longitudinal and transverse momenta, including the central (“mid-rapidity”) area and extending far into the projectile fragmentation region. The resulting analysis shows the heavy ion reaction as a mixture of different processes. In particular, surprising phenomena, like the presence of large and strongly varying structures in the shape of the double differential cross section d2s /dxFd pT , are induced by the final state electromagnetic interaction between produced particles and the charged spectator system. This effect is largest at low transverse momenta, where it results in a deep valley in the xF -dependence of the produced p+/p− ratio. The basic characteristics of the electromagnetic phenomenon described above agree with the results of a theoretical analysis, performed by means of ...
Conduction properties of strongly interacting Fermions
Brantut, Jean-Philippe; Stadler, David; Krinner, Sebastian; Meineke, Jakob; Esslinger, Tilman
2013-05-01
We experimentally study the transport process of ultracold fermionic atoms through a mesoscopic, quasi two-dimensional channel connecting macroscopic reservoirs. By observing the current response to a bias applied between the reservoirs, we directly access the resistance of the channel in a manner analogous to a solid state conduction measurement. The resistance is further controlled by a gate potential reducing the atomic density in the channel, like in a field effect transistor. In this setup, we study the flow of a strongly interacting Fermi gas, and observe a striking drop of resistance with increasing density in the channel, as expected at the onset of superfluidity. We relate the transport properties to the in-situ evolution of the thermodynamic potential, providing a model independant thermodynamic scale. The resistance is compared to that of an ideal Fermi gas in the same geometry, which shows an order of magnitude larger resistance, originating from the contact resistance between the channel and the reservoirs. The extension of this study to a channel containing a tunable disorder is briefly outlined.
Toward a Strongly Interacting Scalar Higgs Particle
International Nuclear Information System (INIS)
Shalaby, Abouzeid M.; El-Houssieny, M.
2008-01-01
We calculate the vacuum energy of the non-Hermitian and PT symmetric (-gφ 4 ) 2+1 scalar field theory. Rather than the corresponding Hermitian theory and due to the asymptotic freedom property of the theory, the vacuum energy does not blow up for large energy scales which is a good sign to solve the hierarchy problem when using this model to break the U(1)xSU(2) symmetry in the standard model. The theory is strongly interacting and in fact, all the dimensionful parameters in the theory like mass and energy are finite even for very high energy scales. Moreover, relative to the vacuum energy for the Hermitian φ 4 theory, the vacuum energy of the non-Hermitian and PT symmetric (-gφ 4 ) 2+1 theory is tiny, which is a good sign toward the solution of the cosmological constant problem. Remarkably, these features of the non-Hermitian and PT symmetric (-gφ 4 ) 2+1 scalar field theory make it very plausible to be employed as a Higgs mechanism in the standard model instead of the problematic Hermitian Higgs mechanism
Ryno, Sean; Risko, Chad; Bredas, Jean-Luc
2016-01-01
of charge penetration, which is shown to account for up to 50% of the total interaction energy in dimers extracted from the experimental single crystals; in the case of the most stable co-facial model dimers, this contribution is even larger than the total
Strong field interaction of laser radiation
International Nuclear Information System (INIS)
Pukhov, Alexander
2003-01-01
The Review covers recent progress in laser-matter interaction at intensities above 10 18 W cm -2 . At these intensities electrons swing in the laser pulse with relativistic energies. The laser electric field is already much stronger than the atomic fields, and any material is instantaneously ionized, creating plasma. The physics of relativistic laser-plasma is highly non-linear and kinetic. The best numerical tools applicable here are particle-in-cell (PIC) codes, which provide the most fundamental plasma model as an ensemble of charged particles. The three-dimensional (3D) PIC code Virtual Laser-Plasma Laboratory runs on a massively parallel computer tracking trajectories of up to 10 9 particles simultaneously. This allows one to simulate real laser-plasma experiments for the first time. When the relativistically intense laser pulses propagate through plasma, a bunch of new physical effects appears. The laser pulses are subject to relativistic self-channelling and filamentation. The gigabar ponderomotive pressure of the laser pulse drives strong currents of plasma electrons in the laser propagation direction; these currents reach the Alfven limit and generate 100 MG quasistatic magnetic fields. These magnetic fields, in turn, lead to the mutual filament attraction and super-channel formation. The electrons in the channels are accelerated up to gigaelectronvolt energies and the ions gain multi-MeV energies. We discuss different mechanisms of particle acceleration and compare numerical simulations with experimental data. One of the very important applications of the relativistically strong laser beams is the fast ignition (FI) concept for the inertial fusion energy (IFE). Petawatt-class lasers may provide enough energy to isochorically ignite a pre-compressed target consisting of thermonuclear fuel. The FI approach would ease dramatically the constraints on the implosion symmetry and improve the energy gain. However, there is a set of problems to solve before the FI
Two interacting active dimers on a rigid track
Mayett, David; Das, Moumita; Schwarz, J. M.
Cell migration in morphogenesis and cancer metastasis typically involves an interplay between different cell types. The rules governing such interplay remain largely unknown; however, a recent experiment studying the interaction between neural crest (NC) cells and placodal cells reveals an example of such rules. The study found that NC cells chase the placodal cells by chemotaxis, while placodal cells run away from NC cells when contacted by them. Motivated by this observation, we construct and study a minimal one-dimensional cell-cell model comprised of two cells with each cell represented by two-beads-connected-by-an-active spring. The active spring for each moving cell models the stress fibers with their myosin-driven Contractility (and alpha-actinin extendability), while the friction coefficients of the beads describe the catch/slip bond behavior of the integrins in focal adhesions. We also include a dynamic contact interaction between the two cells to decipher the chase-and-run dynamics observed in the experiment. We then use our model to construct a ''phase diagram'' consisting of chase-and-run behavior, clumping (of the two cells) with repolarization behavior and clumping with no repolarization behavior that can be qualitatively compared to experiments.
Fe dimers: a theoretical study of the hyperfine interactions
International Nuclear Information System (INIS)
Guenzburger, D.J.R.; Saitovitch, E.M.B.
1981-01-01
The electronic structures of diatomic molecules Fe 2 and FeM, where M = Mn, Co, Ni and Cu, are investigated by molecular orbitals calculations using a discrete variational method and a local approximation for the exchange interaction. The one-electron wave functions obtained are used to calculate electric field gradients, electronic charge and spin densities at the Fe nucleus and spin-dipolar hyperfine fields, which are related to measured hyperfine parameters reported from experiments in solid inert-gas matrices. Molecular orbitals energy schemes and population analysis are presented. These and other aspects of the electronic structure of the FeM molecules are used in a qualitative interpretation of the hyperfine data; in some cases, are given suggestions for the ground-state configuration. (Author) [pt
Quenching points of dimeric single-molecule magnets: Exchange interaction effects
International Nuclear Information System (INIS)
Florez, J.M.; Nunez, Alvaro S.; Vargas, P.
2010-01-01
We study the quenched energy-splitting (Δ E ) of a single-molecule magnet (SMM) conformed by two exchange coupled giant-spins. An assessment of two nontrivial characteristics of this quenching is presented: (i) The quenching-points of a strongly exchange-coupled dimer differ from the ones of their respective giant-spin modeled SMM and such a difference can be well described by using the Solari-Kochetov extra phase; (ii) the dependence on the exchange coupling of the magnetic field values at the quenching-points when Δ E passes from monomeric to dimeric behavior. The physics behind these exchange-modified points, their relation with the Δ E -oscillations experimentally obtained by the Landau-Zener method and with the diabolical-plane of a SMM, is discussed.
Quenching points of dimeric single-molecule magnets: Exchange interaction effects
Energy Technology Data Exchange (ETDEWEB)
Florez, J.M., E-mail: juanmanuel.florez@alumnos.usm.c [Departamento de Fisica, Universidad Tecnica Federico Santa Maria, P.O. Box 110-V, Valparaiso (Chile); Nunez, Alvaro S., E-mail: alnunez@dfi.uchile.c [Departamento de Fisica, Facultad de Ciencias Fisicas y Matematicas, Universidad de Chile, Casilla 487-3, Santiago (Chile); Vargas, P., E-mail: patricio.vargas@usm.c [Departamento de Fisica, Universidad Tecnica Federico Santa Maria, P.O. Box 110-V, Valparaiso (Chile)
2010-11-15
We study the quenched energy-splitting ({Delta}{sub E}) of a single-molecule magnet (SMM) conformed by two exchange coupled giant-spins. An assessment of two nontrivial characteristics of this quenching is presented: (i) The quenching-points of a strongly exchange-coupled dimer differ from the ones of their respective giant-spin modeled SMM and such a difference can be well described by using the Solari-Kochetov extra phase; (ii) the dependence on the exchange coupling of the magnetic field values at the quenching-points when {Delta}{sub E} passes from monomeric to dimeric behavior. The physics behind these exchange-modified points, their relation with the {Delta}{sub E}-oscillations experimentally obtained by the Landau-Zener method and with the diabolical-plane of a SMM, is discussed.
De Sitter vacua of strongly interacting QFT
Energy Technology Data Exchange (ETDEWEB)
Buchel, Alex [Department of Applied Mathematics, University of Western Ontario,London, Ontario N6A 5B7 (Canada); Department of Physics and Astronomy, University of Western Ontario,London, Ontario N6A 5B7 (Canada); Perimeter Institute for Theoretical Physics,Waterloo, Ontario N2J 2W9 (Canada); Karapetyan, Aleksandr [Department of Applied Mathematics, University of Western Ontario,London, Ontario N6A 5B7 (Canada)
2017-03-22
We use holographic correspondence to argue that Euclidean (Bunch-Davies) vacuum is a late-time attractor of the dynamical evolution of quantum gauge theories at strong coupling. The Bunch-Davies vacuum is not an adiabatic state, if the gauge theory is non-conformal — the comoving entropy production rate is nonzero. Using the N=2{sup ∗} gauge theory holography, we explore prospects of explaining current accelerated expansion of the Universe as due to the vacuum energy of a strongly coupled QFT.
Electromagnetic probes of strongly interacting matter
Indian Academy of Sciences (India)
2015-05-07
May 7, 2015 ... Collisions between two nuclei at relativistic energies will create charged particles – either in .... The thermal cutting rules give a systematic procedure to express ...... mesons due to its interaction with the thermal partons [80] and employment of running .... [16] J Deng, Q Wang, N Xu and P Zhuang, Phys. Lett.
Relativistic rapprochement of electromagnetic and strong interactions
International Nuclear Information System (INIS)
Strel'tsov, V.N.
1995-01-01
On the basis of the Lienard-Wiechert potential and the relativistic Yukawa potential it is shown that the corresponding interactions with velocity growth increase differently (the electromagnetic one increases faster). According to preliminary estimations they are equivalent, at distances of the 'action radius' of nuclear forces, at γ≅ 960, where γ is the Lorentz factor. 2 refs
Resonance tuning due to Coulomb interaction in strong near-field coupled metamaterials
International Nuclear Information System (INIS)
Roy Chowdhury, Dibakar; Xu, Ningning; Zhang, Weili; Singh, Ranjan
2015-01-01
Coulomb's law is one of the most fundamental laws of physics that describes the electrostatic interaction between two like or unlike point charges. Here, we experimentally observe a strong effect of Coulomb interaction in tightly coupled terahertz metamaterials where the split-ring resonator dimers in a unit cell are coupled through their near fields across the capacitive split gaps. Using a simple analytical model, we evaluated the Coulomb parameter that switched its sign from negative to positive values indicating the transition in the nature of Coulomb force from being repulsive to attractive depending upon the near field coupling between the split ring resonators. Apart from showing interesting effects in the strong coupling regime between meta-atoms, Coulomb interaction also allows an additional degree of freedom to achieve frequency tunable dynamic metamaterials
Structure-Function Model for Kissing Loop Interactions That Initiate Dimerization of Ty1 RNA
Directory of Open Access Journals (Sweden)
Eric R. Gamache
2017-04-01
Full Text Available The genomic RNA of the retrotransposon Ty1 is packaged as a dimer into virus-like particles. The 5′ terminus of Ty1 RNA harbors cis-acting sequences required for translation initiation, packaging and initiation of reverse transcription (TIPIRT. To identify RNA motifs involved in dimerization and packaging, a structural model of the TIPIRT domain in vitro was developed from single-nucleotide resolution RNA structural data. In general agreement with previous models, the first 326 nucleotides of Ty1 RNA form a pseudoknot with a 7-bp stem (S1, a 1-nucleotide interhelical loop and an 8-bp stem (S2 that delineate two long, structured loops. Nucleotide substitutions that disrupt either pseudoknot stem greatly reduced helper-Ty1-mediated retrotransposition of a mini-Ty1, but only mutations in S2 destabilized mini-Ty1 RNA in cis and helper-Ty1 RNA in trans. Nested in different loops of the pseudoknot are two hairpins with complementary 7-nucleotide motifs at their apices. Nucleotide substitutions in either motif also reduced retrotransposition and destabilized mini- and helper-Ty1 RNA. Compensatory mutations that restore base-pairing in the S2 stem or between the hairpins rescued retrotransposition and RNA stability in cis and trans. These data inform a model whereby a Ty1 RNA kissing complex with two intermolecular kissing-loop interactions initiates dimerization and packaging.
Relativistic rapprochement of weak and strong interactions
International Nuclear Information System (INIS)
Strel'tsov, V.N.
1995-01-01
On the basis of the relativistic Yukawa potentials for the nuclear (quark) field and the field of intermediate vector W-, Z-bosons, it is shown that the interactions described by them increase differently with growing velocity (the weak one increases more rapidly). According to the estimates, they are compared (at distances of the 'action radius' of nuclear forces) at an energy of about 10 12 GeV (10 6 GeV for the pion field) what is smaller than the corresponding value in the model of 'grand unification'. 3 refs., 2 tabs
Strong Interactions, (De)coherence and Quarkonia
Bellucci, Stefano; Tiwari, Bhupendra Nath
2011-01-01
Quarkonia are the central objects to explore the non-perturbative nature of non-abelian gauge theories. We describe the confinement-deconfinement phases for heavy quarkonia in a hot QCD medium and thereby the statistical nature of the inter-quark forces. In the sense of one-loop quantum effects, we propose that the "quantum" nature of quark matters follows directly from the thermodynamic consideration of Richardson potential. Thereby we gain an understanding of the formation of hot and dense states of quark gluon plasma matter in heavy ion collisions and the early universe. In the case of the non-abelian theory, the consideration of the Sudhakov form factor turns out to be an efficient tool for soft gluons. In the limit of the Block-Nordsieck resummation, the strong coupling obtained from the Sudhakov form factor yields the statistical nature of hadronic bound states, e.g. kaons and Ds particles.
Strong and electromagnetic interactions in hadron systems
International Nuclear Information System (INIS)
Aissat, N.; Amghar, A.; Cano, F.; Gonzalez, F.; Noguera, S.; Carbonell, J.; Desplanques, B.; Silvestre-Brac, B.; Karmanov, V.; Mathiot, J.F.
1997-01-01
The pionic strong decay amplitudes of baryon resonances are studied in a constituent quark model. Particular attention is given to the operator describing the transition. The nucleon form factors are calculated in a non-relativistic approach, with emphasis on the highest momentum transfers. The aim is to determine the ingredients that are essential in getting correct results and are likely to be required for a more realistic estimate in a fully relativistic approach. The deuteron form factors have been calculated in the light-front approach using wave functions determined in a perturbative way. The derivation of the neutron charge form factor from the deuteron structure function, A(q 2 ), is reanalyzed including further mesonic exchange contributions. (authors)
"Strong interaction" for particle physics laboratories
2003-01-01
A new Web site pooling the communications resources of particle physics centres all over the world has just been launched. The official launching of the new particle physics website Interactions.org during the Lepton-Proton 2003 Conference at the American laboratory Fermilab was accompanied by music and a flurry of balloons. On the initiative of Fermilab, the site was created by a collaboration of communication teams from over fifteen of the world's particle physics laboratories, including KEK, SLAC, INFN, JINR and, of course, CERN, who pooled their efforts to develop the new tool. The spectacular launching of the new particle physics website Interactions.org at Fermilab on 12 August 2003. A real gateway to particle physics, the site not only contains all the latest news from the laboratories but also offers images, graphics and a video/animation link. In addition, it provides information about scientific policies, links to the universities, a very useful detailed glossary of particle physics and astrophysic...
Supersymmetry and weak, electromagnetic and strong interactions
International Nuclear Information System (INIS)
Fayet, P.
1977-01-01
A supersymmetric theory of particle interactions is discussed. It is based on the earlier model which involves gauge (or vector) superfields, and matter (or chiral) superfields; each of them describes a vector and a Majorana spinor in the first case, or a two-component Dirac spinor and a complex scalar in the second case. The new theory suggests the possible existence of spin - 1/2 gluons and heavy spin-0 quarks, besides spin - 1 gluons and spin - 1/2 quarks. To prevent scalar particles to be exchanged in processes such as μ or β decays a new class of leptons with its own quantum number is introduced; it includes charged leptons and a ''photonic neutrino''
Signatures for strongly interacting W's and Z's
International Nuclear Information System (INIS)
Gaillard, M.K.
1985-09-01
The observed structure of the electroweak interactions is understood in terms of a spontaneously broken gauge theory. Although we have as yet no experimental indication as to the nature of the phenomenon responsible for symmetry breaking, general theoretical arguments set an upper limit of 1 or 2 TeV on the energy scale at which some manifestation of this phenomenon must occur. This scale defines a target for the effective hard collision energy that should be achieved in the next accelerator facility; the work reported here was aimed at sharpening this requirement by studying the minimal manifestations of electroweak symmetry breaking that can be expected to occur in the TeV energy region if a Higgs particle with m/sub H/ < 1 TeV is not found. While we used the minimal Higgs model as a guide, the results obtained are of far more general validity. Our analysis relied on three tools, briefly discussed. These are: the equivalence at high energies of longitudinally polarized W's and Z's to their scalar counterparts, the Goldstone bosons; the symmetries of the scalar sector; and the vector boson fusion process. 8 refs
QCD : the theory of strong interactions Conference MT17
2001-01-01
The theory of strong interactions,Quantum Chromodynamics (QCD), predicts that the strong interaction is transmitted by the exchange of particles called gluons. Unlike the messengers of electromagnetism photons, which are electrically neutral - gluons carry a strong charge associated with the interaction they mediate. QCD predicts that the strength of the interaction between quarks and gluons becomes weaker at higher energies. LEP has measured the evolution of the strong coupling constant up to energies of 200 GeV and has confirmed this prediction.
Spin-orbit interaction driven dimerization in one dimensional frustrated magnets
Zhang, Shang-Shun; Batista, Cristian D.
Spin nematic ordering has been proposed to emerge near the saturation of field of a class of frustrated magnets. The experimental observation of this novel phase is challenging for the traditional experimental probes. Nematic spin ordering is expected to induce a local quadrupolar electric moment via the spin-orbit coupling. However, a finite spin-orbit interaction explicitly breaks the U(1) symmetry of global spin rotations down to Z2, which renders the traditional nematic order no longer well-defined. In this work we investigate the relevant effect of spin-orbit interaction on the 1D frustrated J1 -J2 model. The real and the imaginary parts of the nematic order parameter belong to different representations of the discrete symmetry group of the new Hamiltonian. We demonstrate that spin-orbit coupling stabilizes the real component and simultaneously induces bond dimerization in most of the phase diagram. Such a bond dimerization can be observed with X-rays or nuclear magnetic resonance. In addition, an incommensurate bond-density wave (ICBDW) appears for smaller values of J2 / |J1 | . The experimental fingerprint of the ICBDW is a double-horn shape of the the NMR line. These conclusions can shed light on the experimental search of this novel phase.
Dynamics of Strong Interactions and the S-Matrix
Energy Technology Data Exchange (ETDEWEB)
Omnes, R. [Laboratoire de Physique Theorique et Hautes Energies, Universite de Paris, Orsay (France)
1969-08-15
The physical principles underlying the S-matrix theory of strong interactions are reviewed. In particular, the problem of whether these principles are sufficient to completely determine the S-matrix, i.e. to yield a dynamical theory of strong interactions, is discussed. (author)
Strong enhancement of transport by interaction on contact links
DEFF Research Database (Denmark)
Bohr, Dan; Schmitteckert, P.
2007-01-01
Strong repulsive interactions within a one-dimensional Fermi system in a two-probe configuration normally lead to a reduced off-resonance conductance. We show that if the repulsive interaction extends to the contact regions, a strong increase of the conductance may occur, even for systems where o...
QCD : the theory of strong interactions Exhibition LEPFest 2000
2000-01-01
The theory of strong interactions,Quantum Chromodynamics (QCD),predicts that the strong interac- tion is transmitted by the exchange of particles called glu- ons.Unlike the messengers of electromagnetism -pho- tons,which are electrically neutral -gluons carry a strong charge associated with the interaction they mediate. QCD predicts that the strength of the interaction between quarks and gluons becomes weaker at higher energies.LEP has measured the evolution of the strong coupling constant up to energies of 200 GeV and has confirmed this prediction.
Non-additive non-interacting kinetic energy of rare gas dimers
Jiang, Kaili; Nafziger, Jonathan; Wasserman, Adam
2018-03-01
Approximations of the non-additive non-interacting kinetic energy (NAKE) as an explicit functional of the density are the basis of several electronic structure methods that provide improved computational efficiency over standard Kohn-Sham calculations. However, within most fragment-based formalisms, there is no unique exact NAKE, making it difficult to develop general, robust approximations for it. When adjustments are made to the embedding formalisms to guarantee uniqueness, approximate functionals may be more meaningfully compared to the exact unique NAKE. We use numerically accurate inversions to study the exact NAKE of several rare-gas dimers within partition density functional theory, a method that provides the uniqueness for the exact NAKE. We find that the NAKE decreases nearly exponentially with atomic separation for the rare-gas dimers. We compute the logarithmic derivative of the NAKE with respect to the bond length for our numerically accurate inversions as well as for several approximate NAKE functionals. We show that standard approximate NAKE functionals do not reproduce the correct behavior for this logarithmic derivative and propose two new NAKE functionals that do. The first of these is based on a re-parametrization of a conjoint Perdew-Burke-Ernzerhof (PBE) functional. The second is a simple, physically motivated non-decomposable NAKE functional that matches the asymptotic decay constant without fitting.
Numerical Calculation of the Phase Space Density for the Strong-Strong Beam-Beam Interaction
International Nuclear Information System (INIS)
Sobol, A.; Ellison, J.A.
2003-01-01
We developed a parallel code to calculate the evolution of the 4D phase space density of two colliding beams, which are coupled via the collective strong-strong beam-beam interaction, in the absence of diffusion and damping, using the Perron-Frobenius (PF) operator technique
Ryno, Sean
2016-05-18
Non-covalent interactions determine in large part the thermodynamic aspects of molecular packing in organic crystals. Using a combination of symmetry-adapted perturbation theory (SAPT) and classical multipole electrostatics, we describe the interaction potential energy surfaces for dimers of the oligoacene family, from benzene to hexacene. An analysis of these surfaces and a thorough assessment of dimers extracted from the reported crystal structures underline that high-order interactions (i.e., three-body non-additive interactions) must be considered in order to rationalize the details of the crystal structures. A comparison of the SAPT electrostatic energy with the multipole interaction energy demonstrates the importance of the contribution of charge penetration, which is shown to account for up to 50% of the total interaction energy in dimers extracted from the experimental single crystals; in the case of the most stable co-facial model dimers, this contribution is even larger than the total interaction energy. Our results highlight the importance of taking account of charge penetration in studies of the larger oligoacenes.
Chang, Chih-Kang; Teng, Kuo-Hsun; Lin, Sheng-Wei; Chang, Tao-Hsin; Liang, Po-Huang
2013-04-23
Previously we showed that yeast geranylgeranyl diphosphate synthase (GGPPS) becomes an inactive monomer when the first N-terminal helix involved in dimerization is deleted. This raises questions regarding why dimerization is required for GGPPS activity and which amino acids in the dimer interface are essential for dimerization-mediated activity. According to the GGPPS crystal structure, three amino acids (N101, N104, and Y105) located in the helix F of one subunit are near the active site of the other subunit. As presented here, when these residues were replaced individually with Ala caused insignificant activity changes, N101A/Y105A and N101A/N104A but not N104A/Y105A showed remarkably decreased k(cat) values (200-250-fold). The triple mutant N101A/N104A/Y105A displayed no detectable activity, although dimer was retained in these mutants. Because N101 and Y105 form H-bonds with H139 and R140 in the other subunit, respectively, we generated H139A/R140A double mutant and found it was inactive and became monomeric. Therefore, the multiple mutations apparently influence the integrity of the catalytic site due to the missing H-bonding network. Moreover, Met111, also on the highly conserved helix F, was necessary for dimer formation and enzyme activity. When Met111 was replaced with Glu, the negative-charged repulsion converted half of the dimer into a monomer. In conclusion, the H-bonds mainly through N101 for maintaining substrate binding stability and the hydrophobic interaction of M111 in dimer interface are essential for activity of yeast GGPPS.
International Nuclear Information System (INIS)
Figueiredo, Rute Cunha; Meyer, Nadia Burkowski; Prado, Maria Auxiliadora Fontes; Alves, Ricardo Jose; Rojo, Javier
2009-01-01
The synthesis of two new D-galactose-based dimers having a 1,4-butanediamine spacer is reported aiming at the evaluation of their interaction with the Erythrina cristagalli lectin. The title compounds were prepared in four and five steps from 2,3,4,6-tetra-O-acetyl-β-D-galactopyranoside bromide, in 20 % and 15 % overall yield, respectively, using the Doebner modification of the Koenavenagel reaction as the key sep. The lectin-carbohydrate interaction could be evaluated for only one dimer, due to solubility problems. A twofold enhancement of affinity was observed, compared to the corresponding monovalent ligand. (author)
Directory of Open Access Journals (Sweden)
Yoshitomo Hamada
2015-10-01
Full Text Available Proanthocyanidins, which are composed of oligomeric flavan-3-ol units, are contained in various foodstuffs (e.g., fruits, vegetables, and drinks and are strongly biologically active compounds. We investigated which element of the proanthocyanidin structure is primarily responsible for this functionality. In this study, we elucidate the importance of the upper-unit of 4–8 condensed dimeric flavan-3-ols for antimicrobial activity against Saccharomyces cerevisiae (S. cerevisiae and cervical epithelioid carcinoma cell line HeLa S3 proliferation inhibitory activity. To clarify the important constituent unit of proanthocyanidin, we synthesized four dimeric compounds, (−-epigallocatechin-[4,8]-(+-catechin, (−-epigallocatechin-[4,8]-(−-epigallocatechin, (−-epigallocatechin-[4,8]-(−-epigallocatechin-3-O-gallate, and (+-catechin-[4,8]-(−-epigallocatechin and performed structure–activity relationship (SAR studies. In addition to antimicrobial activity against S. cerevisiae and proliferation inhibitory activity on HeLa S3 cells, the correlation of 2,2-diphenyl-l-picrylhydrazyl radical scavenging activity with the number of phenolic hydroxyl groups was low. On the basis of the results of our SAR studies, we concluded that B-ring hydroxyl groups of the upper-unit of the dimer are crucially important for strong and effective activity.
Prospects for strong interaction physics at ISABELLE. [Seven papers
Energy Technology Data Exchange (ETDEWEB)
Sidhu, D P; Trueman, T L
1977-01-01
Seven papers are presented resulting from a conference intended to stimulate thinking about how ISABELLE could be used for studying strong interactions. A separate abstract was prepared for each paper for inclusion in DOE Energy Research Abstracts (ERA). (PMA)
A theory of strong interactions ''from'' general relativity
International Nuclear Information System (INIS)
Caldirola, P.; Recami, E.
1979-01-01
In this paper a previous letter (where, among other things, a classical ''quark confinement'' was derived from general relativity plus dilatation-covariance), is completed by showing that the theory is compatible also with quarks ''asymptotic freedom''. Then -within a bi-scale theory of gravitational and strong interactions- a classical field theory is proposed for the (strong) interactions between hadrons. Various consequences are briefly analysed
Measurement of strong interaction effects in antiprotonic helium atoms
International Nuclear Information System (INIS)
Davies, J.D.; Gorringe, T.P.; Lowe, J.; Nelson, J.M.; Playfer, S.M.; Pyle, G.J.; Squier, G.T.A.
1984-01-01
The strong interaction shift and width for the 2 p level and the width for the 3d level have been measured for antiprotonic helium atoms. The results are compared with optical model calculations. The possible existence of strongly bound antiproton states in nuclei is discussed. (orig.)
Interaction between Electron Holes in a Strongly Magnetized Plasma
DEFF Research Database (Denmark)
Lynov, Jens-Peter; Michelsen, Poul; Pécseli, Hans
1980-01-01
The interaction between electron holes in a strongly magnetized, plasma-filled waveguide is investigated by means of computer simulation. Two holes may or may not coalesce, depending on their amplitudes and velocities. The interaction between holes and Trivelpiece-Gould solitons is demonstrated...
Quark imprisonment as the origin of strong interactions
Amati, Daniele
1974-01-01
A formal scheme is suggested in which the only dynamical ingredients are weak and electro-magnetic interactions with quarks and leptons treated on the same footing. Strong interactions are generated by the requirement that quarks do not appear physically. (7 refs).
Substructure and strong interactions at the TeV scale
International Nuclear Information System (INIS)
Peskin, M.E.
1985-12-01
A review is given of the current status of the three main theoretical ideas relevant to strong-interaction 1 TeV physics. These are composite vector bosons, Higgs bosons (''Technicolor''), and matter fermions. All involve the assumption that some object which is assumed to be fundamental in the standard model actually has dynamical internal structure. Complex, mechanistic models of the new physics are discussed. A brief digression is then made on how the weak interaction allows probing for this new structure. Direct manifestations of new 1 TeV strong interactions are discussed. 125 refs., 18 figs
Semicalssical quantization of interacting anyons in a strong magnetic field
International Nuclear Information System (INIS)
Levit, S.; Sivan, N.
1992-01-01
We represent a semiclassical theory of charged interacting anyons in strong magnetic fields. We apply this theory to a number of few anyons systems including two interacting anyons in the presence of an impurity and three interacting anyons. We discuss the dependence of their energy levels on the statistical parameter and find regions in which this dependence follows very different patterns. The semiclassical arguments allow to correlate these patterns with the change in the character of the classical motion of the system. (author)
Analysis of hepatitis C virus RNA dimerization and core–RNA interactions
Ivanyi-Nagy, Roland; Kanevsky, Igor; Gabus, Caroline; Lavergne, Jean-Pierre; Ficheux, Damien; Penin, François; Fossé, Philippe; Darlix, Jean-Luc
2006-01-01
The core protein of hepatitis C virus (HCV) has been shown previously to act as a potent nucleic acid chaperone in vitro, promoting the dimerization of the 3′-untranslated region (3′-UTR) of the HCV genomic RNA, a process probably mediated by a small, highly conserved palindromic RNA motif, named DLS (dimer linkage sequence) [G. Cristofari, R. Ivanyi-Nagy, C. Gabus, S. Boulant, J. P. Lavergne, F. Penin and J. L. Darlix (2004) Nucleic Acids Res., 32, 2623–2631]. To investigate in depth HCV RNA dimerization, we generated a series of point mutations in the DLS region. We find that both the plus-strand 3′-UTR and the complementary minus-strand RNA can dimerize in the presence of core protein, while mutations in the DLS (among them a single point mutation that abolished RNA replication in a HCV subgenomic replicon system) completely abrogate dimerization. Structural probing of plus- and minus-strand RNAs, in their monomeric and dimeric forms, indicate that the DLS is the major if not the sole determinant of UTR RNA dimerization. Furthermore, the N-terminal basic amino acid clusters of core protein were found to be sufficient to induce dimerization, suggesting that they retain full RNA chaperone activity. These findings may have important consequences for understanding the HCV replicative cycle and the genetic variability of the virus. PMID:16707664
Analysis of hepatitis C virus RNA dimerization and core-RNA interactions.
Ivanyi-Nagy, Roland; Kanevsky, Igor; Gabus, Caroline; Lavergne, Jean-Pierre; Ficheux, Damien; Penin, François; Fossé, Philippe; Darlix, Jean-Luc
2006-01-01
The core protein of hepatitis C virus (HCV) has been shown previously to act as a potent nucleic acid chaperone in vitro, promoting the dimerization of the 3'-untranslated region (3'-UTR) of the HCV genomic RNA, a process probably mediated by a small, highly conserved palindromic RNA motif, named DLS (dimer linkage sequence) [G. Cristofari, R. Ivanyi-Nagy, C. Gabus, S. Boulant, J. P. Lavergne, F. Penin and J. L. Darlix (2004) Nucleic Acids Res., 32, 2623-2631]. To investigate in depth HCV RNA dimerization, we generated a series of point mutations in the DLS region. We find that both the plus-strand 3'-UTR and the complementary minus-strand RNA can dimerize in the presence of core protein, while mutations in the DLS (among them a single point mutation that abolished RNA replication in a HCV subgenomic replicon system) completely abrogate dimerization. Structural probing of plus- and minus-strand RNAs, in their monomeric and dimeric forms, indicate that the DLS is the major if not the sole determinant of UTR RNA dimerization. Furthermore, the N-terminal basic amino acid clusters of core protein were found to be sufficient to induce dimerization, suggesting that they retain full RNA chaperone activity. These findings may have important consequences for understanding the HCV replicative cycle and the genetic variability of the virus.
Excitonic Behavior of Rhodamine Dimers: A Single-Molecule Study
Hernando Campos, J.; van der Schaaf, Martijn; van Dijk, E.M.H.P.; Sauer, Markus; Garcia Parajo, M.F.; van Hulst, N.F.
2003-01-01
The optical behavior of a dimer of tetramethylrhodamine-5-isothiocyanate has been investigated by means of single-molecule measurements. Bulk absorption and fluorescence spectra show the existence of two populations of the dimer molecule that exhibit distinct excitonic interactions (strong and weak
Mixtures of Strongly Interacting Bosons in Optical Lattices
International Nuclear Information System (INIS)
Buonsante, P.; Penna, V.; Giampaolo, S. M.; Illuminati, F.; Vezzani, A.
2008-01-01
We investigate the properties of strongly interacting heteronuclear boson-boson mixtures loaded in realistic optical lattices, with particular emphasis on the physics of interfaces. In particular, we numerically reproduce the recent experimental observation that the addition of a small fraction of 41 K induces a significant loss of coherence in 87 Rb, providing a simple explanation. We then investigate the robustness against the inhomogeneity typical of realistic experimental realizations of the glassy quantum emulsions recently predicted to occur in strongly interacting boson-boson mixtures on ideal homogeneous lattices
DEFF Research Database (Denmark)
Mikkelsen, J G; Lund, Anders Henrik; Duch, M
1998-01-01
during minus-strand DNA synthesis occurred within defined areas of the genome and did not lead to misincorporations at the crossover site. The nonrandom distribution of recombination sites did not reflect a bias for specific sites due to selection at the level of marker gene expression. We address...... whether template switching is affected by the length of sequence identity, by palindromic sequences, and/or by putative stem-loop structures. Sixteen of 24 sites of recombination colocalized with the kissing-loop dimerization region, and we propose that RNA-RNA interactions between palindromic sequences...
New results on strong-interaction effects in antiprotonic hydrogen
Gotta, D; Augsburger, M A; Borchert, G L; Castelli, C M; Chatellard, D; El-Khoury, P; Egger, J P; Gorke, H; Hauser, P R; Indelicato, P J; Kirch, K; Lenz, S; Nelms, N; Rashid, K; Schult, O W B; Siems, T; Simons, L M
1999-01-01
Lyman and Balmer transitions of antiprotonic hydrogen and deuterium have been measured at the low-energy antiproton ring LEAR at CERN in order to determine the strong interaction effects. The X-rays were detected using charge-coupled devices (CCDs) and a reflection type crystal spectrometer. The results of the measurements support the meson-exchange models describing the medium and long range part of the nucleon-antinucleon interaction. (33 refs).
New results on strong-interaction effects in antiprotonic hydrogen
International Nuclear Information System (INIS)
Anagnostopoulos, D. F.; Augsburger, M.; Borchert, G.; Castelli, C.; Chatellard, D.; El-Khoury, P.; Egger, J.-P.; Gorke, H.; Gotta, D.; Hauser, P.; Indelicato, P.; Kirch, K.; Lenz, S.; Nelms, N.; Rashid, K.; Schult, O. W. B.; Siems, Th.; Simons, L. M.
1999-01-01
Lyman and Balmer transitions of antiprotonic hydrogen and deuterium have been measured at the Low-Energy Antiproton Ring LEAR at CERN in order to determine the strong interaction effects. The X-rays were detected using Charge-Coupled Devices (CCDs) and a reflection type crystal spectrometer. The results of the measurements support the meson-exchange models describing the medium and long range part of the nucleon-antinucleon interaction
Godfrey-Kittle, Andrew; Cafiero, Mauricio
We present density functional theory (DFT) interaction energies for the sandwich and T-shaped conformers of substituted benzene dimers. The DFT functionals studied include TPSS, HCTH407, B3LYP, and X3LYP. We also include Hartree-Fock (HF) and second-order Møller-Plesset perturbation theory calculations (MP2), as well as calculations using a new functional, P3LYP, which includes PBE and HF exchange and LYP correlation. Although DFT methods do not explicitly account for the dispersion interactions important in the benzene-dimer interactions, we find that our new method, P3LYP, as well as HCTH407 and TPSS, match MP2 and CCSD(T) calculations much better than the hybrid methods B3LYP and X3LYP methods do.
H. David Politzer, Asymptotic Freedom, and Strong Interaction
dropdown arrow Site Map A-Z Index Menu Synopsis H. David Politzer, Asymptotic Freedom, and Strong Interaction Resources with Additional Information H. David Politzer Photo Credit: California Institute of Technology H. David Politzer has won the 2004 Nobel Prize in Physics 'for the discovery of asymptotic freedom
Emergence of junction dynamics in a strongly interacting Bose mixture
DEFF Research Database (Denmark)
Barfknecht, Rafael Emilio; Foerster, Angela; Zinner, Nikolaj Thomas
We study the dynamics of a one-dimensional system composed of a bosonic background and one impurity in single- and double-well trapping geometries. In the limit of strong interactions, this system can be modeled by a spin chain where the exchange coefficients are determined by the geometry of the...
Interplay of Anderson localization and strong interaction in disordered systems
International Nuclear Information System (INIS)
Henseler, Peter
2010-01-01
We study the interplay of disorder localization and strong local interactions within the Anderson-Hubbard model. Taking into account local Mott-Hubbard physics and static screening of the disorder potential, the system is mapped onto an effective single-particle Anderson model, which is studied within the self-consistent theory of electron localization. For fermions, we find rich nonmonotonic behavior of the localization length ξ, particularly in two-dimensional systems, including an interaction-induced exponential enhancement of ξ for small and intermediate disorders and a strong reduction of ξ due to hopping suppression by strong interactions. In three dimensions, we identify for half filling a Mott-Hubbard-assisted Anderson localized phase existing between the metallic and the Mott-Hubbard-gapped phases. For small U there is re-entrant behavior from the Anderson localized phase to the metallic phase. For bosons, the unrestricted particle occupation number per lattice site yields a monotonic enhancement of ξ as a function of decreasing interaction, which we assume to persist until the superfluid Bose-Einstein condensate phase is entered. Besides, we study cold atomic gases expanding, by a diffusion process, in a weak random potential. We show that the density-density correlation function of the expanding gas is strongly affected by disorder and we estimate the typical size of a speckle spot, i.e., a region of enhanced or depleted density. Both a Fermi gas and a Bose-Einstein condensate (in a mean-field approach) are considered. (orig.)
Interplay of Anderson localization and strong interaction in disordered systems
Energy Technology Data Exchange (ETDEWEB)
Henseler, Peter
2010-01-15
We study the interplay of disorder localization and strong local interactions within the Anderson-Hubbard model. Taking into account local Mott-Hubbard physics and static screening of the disorder potential, the system is mapped onto an effective single-particle Anderson model, which is studied within the self-consistent theory of electron localization. For fermions, we find rich nonmonotonic behavior of the localization length {xi}, particularly in two-dimensional systems, including an interaction-induced exponential enhancement of {xi} for small and intermediate disorders and a strong reduction of {xi} due to hopping suppression by strong interactions. In three dimensions, we identify for half filling a Mott-Hubbard-assisted Anderson localized phase existing between the metallic and the Mott-Hubbard-gapped phases. For small U there is re-entrant behavior from the Anderson localized phase to the metallic phase. For bosons, the unrestricted particle occupation number per lattice site yields a monotonic enhancement of {xi} as a function of decreasing interaction, which we assume to persist until the superfluid Bose-Einstein condensate phase is entered. Besides, we study cold atomic gases expanding, by a diffusion process, in a weak random potential. We show that the density-density correlation function of the expanding gas is strongly affected by disorder and we estimate the typical size of a speckle spot, i.e., a region of enhanced or depleted density. Both a Fermi gas and a Bose-Einstein condensate (in a mean-field approach) are considered. (orig.)
Quantum transport in strongly interacting one-dimensional nanostructures
Agundez, R.R.
2015-01-01
In this thesis we study quantum transport in several one-dimensional systems with strong electronic interactions. The first chapter contains an introduction to the concepts treated throughout this thesis, such as the Aharonov-Bohm effect, the Kondo effect, the Fano effect and quantum state transfer.
Discriminative deep inelastic tests of strong interaction field theories
International Nuclear Information System (INIS)
Glueck, M.; Reya, E.
1979-02-01
It is demonstrated that recent measurements of ∫ 0 1 F 2 (x, Q 2 )dx eliminate already all strong interaction field theories except QCD. A detailed study of scaling violations of F 2 (x, Q 2 ) in QCD shows their insensitivity to the gluon content of the hadron at presently measured values of Q 2 . (orig.) [de
Two-dimensional QCD as a model for strong interaction
International Nuclear Information System (INIS)
Ellis, J.
1977-01-01
After an introduction to the formalism of two-dimensional QCD, its applications to various strong interaction processes are reviewed. Among the topics discussed are spectroscopy, deep inelastic cross-sections, ''hard'' processes involving hadrons, ''Regge'' behaviour, the existence of the Pomeron, and inclusive hadron cross-sections. Attempts are made to abstracts features useful for four-dimensional QCD phenomenology. (author)
Measurement of strong interaction parameters in antiprotonic hydrogen and deuterium
Augsburger, M A; Borchert, G L; Chatellard, D; Egger, J P; El-Khoury, P; Gorke, H; Gotta, D; Hauser, P R; Indelicato, P J; Kirch, K; Lenz, S; Siems, T; Simons, L M
1999-01-01
In the PS207 experiment at CERN, X-rays from antiprotonic hydrogen and deuterium have been measured at low pressure. The strong interaction shift and the broadening of the K/sub alpha / transition in antiprotonic hydrogen were $9 determined. Evidence was found for the individual hyperfine components of the protonium ground state. (7 refs).
A systematic study of the strong interaction with PANDA
Messchendorp, J. G.; Hosaka, A; Khemchandani, K; Nagahiro, H; Nawa, K
2011-01-01
The theory of Quantum Chromo Dynamics (QCD) reproduces the strong interaction at distances much shorter than the size of the nucleon. At larger distance scales, the generation of hadron masses and confinement cannot yet be derived from first principles on basis of QCD. The PANDA experiment at FAIR
Intermolecular Interactions in the TMEM16A Dimer Controlling Channel Activity.
Scudieri, Paolo; Musante, Ilaria; Gianotti, Ambra; Moran, Oscar; Galietta, Luis J V
2016-12-08
TMEM16A and TMEM16B are plasma membrane proteins with Ca 2+ -dependent Cl - channel function. By replacing the carboxy-terminus of TMEM16A with the equivalent region of TMEM16B, we obtained channels with potentiation of channel activity. Progressive shortening of the chimeric region restricted the "activating domain" to a short sequence close to the last transmembrane domain and led to TMEM16A channels with high activity at very low intracellular Ca 2+ concentrations. To elucidate the molecular mechanism underlying this effect, we carried out experiments based on double chimeras, Forster resonance energy transfer, and intermolecular cross-linking. We also modeled TMEM16A structure using the Nectria haematococca TMEM16 protein as template. Our results indicate that the enhanced activity in chimeric channels is due to altered interaction between the carboxy-terminus and the first intracellular loop in the TMEM16A homo-dimer. Mimicking this perturbation with a small molecule could be the basis for a pharmacological stimulation of TMEM16A-dependent Cl - transport.
Okuda, Hiroko; Yonezawa, Yasushige; Takano, Yu; Okamura, Yasushi; Fujiwara, Yuichiro
2016-01-01
The voltage-gated H+ channel (Hv) is a voltage sensor domain-like protein consisting of four transmembrane segments (S1?S4). The native Hv structure is a homodimer, with the two channel subunits functioning cooperatively. Here we show that the two voltage sensor S4 helices within the dimer directly cooperate via a ?-stacking interaction between Trp residues at the middle of each segment. Scanning mutagenesis showed that Trp situated around the original position provides the slow gating kineti...
On the strong crack-microcrack interaction problem
Gorelik, M.; Chudnovsky, A.
1992-07-01
The problem of the crack-microcrack interaction is examined with special attention given to the iterative procedure described by Chudnovsky and Kachanov (1983), Chudnovsky et al. (1984), and Horii and Nemat-Nasser (1983), which yields erroneous results as the crack tips become closer (i.e., for strong crack interaction). To understand the source of error, the traction distributions along the microcrack line on the n-th step of iteration representing the exact and asymptotic stress fields are compared. It is shown that the asymptotic solution gives a gross overestimation of the actual traction.
Konarev, Dmitri V; Khasanov, Salavat S; Shestakov, Alexander F; Fatalov, Alexey M; Batov, Mikhail S; Otsuka, Akihiro; Yamochi, Hideki; Kitagawa, Hiroshi; Lyubovskaya, Rimma N
2017-10-24
Reaction of decamethylchromocene (Cp* 2 Cr) with thioindigo (TI) yields a coordination complex {[TI-(μ 2 -O), (μ-O)]Cp*Cr} 2 ·C 6 H 14 (1) in which one Cp* ligand in Cp* 2 Cr is substituted by TI. TI adopts cis-conformation in 1 allowing the coordination of both carbonyl groups to chromium. Additionally, one oxygen atom of TI becomes a μ 2 -bridge for two chromium atoms to form {[TI-(μ 2 -O), (μ-O)]Cp*Cr} 2 dimers with a CrCr distance of 3.12 Å. According to magnetic data, diamagnetic TI 2- dianions and two Cr 3+ atoms with a high S = 3/2 spin state are present in a dimer allowing strong antiferromagnetic coupling between two Cr 3+ spins with an exchange interaction of -35.4 K and the decrease of molar magnetic susceptibility below 140 K. Paramagnetic TI˙ - radical anions with the S = 1/2 spin state have also been obtained and studied in crystalline {cryptand[2,2,2](Na + )}(TI˙ - ) (2) salt showing that both radical anion and dianion states are accessible for TI.
Ruling out a strongly interacting standard Higgs model
International Nuclear Information System (INIS)
Riesselmann, K.; Willenbrock, S.
1997-01-01
Previous work has suggested that perturbation theory is unreliable for Higgs- and Goldstone-boson scattering, at energies above the Higgs-boson mass, for relatively small values of the Higgs quartic coupling λ(μ). By performing a summation of nonlogarithmic terms, we show that perturbation theory is in fact reliable up to relatively large coupling. This eliminates the possibility of a strongly interacting standard Higgs model at energies above the Higgs-boson mass, complementing earlier studies which excluded strong interactions at energies near the Higgs-boson mass. The summation can be formulated in terms of an appropriate scale in the running coupling, μ=√(s)/e∼√(s)/2.7, so it can be incorporated easily in renormalization-group-improved tree-level amplitudes as well as higher-order calculations. copyright 1996 The American Physical Society
Atom-Pair Kinetics with Strong Electric-Dipole Interactions.
Thaicharoen, N; Gonçalves, L F; Raithel, G
2016-05-27
Rydberg-atom ensembles are switched from a weakly to a strongly interacting regime via adiabatic transformation of the atoms from an approximately nonpolar into a highly dipolar quantum state. The resultant electric dipole-dipole forces are probed using a device akin to a field ion microscope. Ion imaging and pair-correlation analysis reveal the kinetics of the interacting atoms. Dumbbell-shaped pair-correlation images demonstrate the anisotropy of the binary dipolar force. The dipolar C_{3} coefficient, derived from the time dependence of the images, agrees with the value calculated from the permanent electric-dipole moment of the atoms. The results indicate many-body dynamics akin to disorder-induced heating in strongly coupled particle systems.
The hadronic standard model for strong and electroweak interactions
International Nuclear Information System (INIS)
Raczka, R.
1993-01-01
We propose a new model for strong and electro-weak interactions. First, we review various QCD predictions for hadron-hadron and lepton-hadron processes. We indicate that the present formulation of strong interactions in the frame work of Quantum Chromodynamics encounters serious conceptual and numerical difficulties in a reliable description of hadron-hadron and lepton-hadron interactions. Next we propose to replace the strong sector of Standard Model based on unobserved quarks and gluons by the strong sector based on the set of the observed baryons and mesons determined by the spontaneously broken SU(6) gauge field theory model. We analyse various properties of this model such as asymptotic freedom, Reggeization of gauge bosons and fundamental fermions, baryon-baryon and meson-baryon high energy scattering, generation of Λ-polarization in inclusive processes and others. Finally we extend this model by electro-weak sector. We demonstrate a remarkable lepton and hadron anomaly cancellation and we analyse a series of important lepton-hadron and hadron-hadron processes such as e + + e - → hadrons, e + + e - → W + + W - , e + + e - → p + anti-p, e + p → e + p and p + anti-p → p + anti-p processes. We obtained a series of interesting new predictions in this model especially for processes with polarized particles. We estimated the value of the strong coupling constant α(M z ) and we predicted the top baryon mass M Λ t ≅ 240 GeV. Since in our model the proton, neutron, Λ-particles, vector mesons like ρ, ω, φ, J/ψ ect. and leptons are elementary most of experimentally analysed lepton-hadron and hadron-hadron processes in LEP1, LEP2, LEAR, HERA, HERMES, LHC and SSC experiments may be relatively easily analysed in our model. (author). 252 refs, 65 figs, 1 tab
A connection between the strong and weak interactions
International Nuclear Information System (INIS)
Treiman, S.B.
1989-01-01
By studying weak scattering reactions (such as pion-nucleon scattering), the author and his colleague Marvin L Goldberger became renowned in the 1950s for work on dispersion relations. As a result of their collaboration a remarkable and unexpected connection was found between strong and weak interaction quantities. Agreement with experiment was good. Work by others found the same result, but via the partially conserved axial reactor current relation between the axial current divergence and the canonical pion field. (UK)
Avetissian, Hamlet
2006-01-01
This book covers a large class of fundamental investigations into Relativistic Nonlinear Electrodynamics. It explores the interaction between charged particles and strong laser fields, mainly concentrating on contemporary problems of x-ray lasers, new type small set-up high-energy accelerators of charged particles, as well as electron-positron pair production from super powerful laser fields of relativistic intensities. It will also discuss nonlinear phenomena of threshold nature that eliminate the concurrent inverse processes in the problems of Laser Accelerator and Free Electron Laser, thus creating new opportunities for solving these problems.
The Electron-Phonon Interaction in Strongly Correlated Systems
International Nuclear Information System (INIS)
Castellani, C.; Grilli, M.
1995-01-01
We analyze the effect of strong electron-electron repulsion on the electron-phonon interaction from a Fermi-liquid point of view and show that the electron-electron interaction is responsible for vertex corrections, which generically lead to a strong suppression of the electron-phonon coupling in the v F q/ω >>1 region, while such effect is not present when v F q/ω F is the Fermi velocity and q and ω are the transferred momentum and frequency respectively. In particular the e-ph scattering is suppressed in transport properties which are dominated by low-energy-high-momentum processes. On the other hand, analyzing the stability criterion for the compressibility, which involves the effective interactions in the dynamical limit, we show that a sizable electron-phonon interaction can push the system towards a phase-separation instability. Finally a detailed analysis of these ideas is carried out using a slave-boson approach for the infinite-U three-band Hubbard model in the presence of a coupling between the local hole density and a dispersionless optical phonon. (author)
Small, David W; Head-Gordon, Martin
2017-07-14
The Coupled Cluster Valence Bond (CCVB) method, previously presented for closed-shell (CS) systems, is extended to open-shell (OS) systems. The theoretical development is based on embedding the basic OS CCVB wavefunction in a fictitious singlet super-system. This approach reveals that the OS CCVB amplitude equations are quite similar to those of CS CCVB, and thus that OS CCVB requires the same level of computational effort as CS CCVB, which is an inexpensive method. We present qualitatively correct CCVB potential energy curves for all low-lying spin states of P 2 and Mn 2 + . CCVB is successfully applied to the low-lying spin states of some model linear polycarbenes, systems that appear to be a hindrance to standard density functionals. We examine an octa-carbene dimer in a side-by-side orientation, which, in the monomer dissociation limit, exhibits maximal strong correlation over the length of the polycarbene.
Kumar Pal, Santanu
2017-01-01
This book covers in-depth discussion of design principles, synthesis and thermal behavior of all types of liquid crystal (LC) dimers. The text presents recent advances in the field of LC dimers consisting of different mesogenic units such as calamitic, discotic and bent-core molecules. It starts with a chapter on the introduction of liquid crystal dimers, including their odd-even behavior, basic classification of dimers and common mesophases in dimers. The text shows how the molecular architectures are being used to develop new materials to study a range of interesting phenomena such as the biaxial nematic phase containing rod-like and disc-like mesogenic units. Finally, the text presents perspectives related to technological relevance of these dimers such as dopants in LC display mixtures exhibiting faster relaxation time, strong flexoelectric coupling and others to effect control over the properties of these materials.
Joule-Thomson Coefficient for Strongly Interacting Unitary Fermi Gas
International Nuclear Information System (INIS)
Liao Kai; Chen Jisheng; Li Chao
2010-01-01
The Joule-Thomson effect reflects the interaction among constituent particles of macroscopic system. For classical ideal gas, the corresponding Joule-Thomson coefficient is vanishing while it is non-zero for ideal quantum gas due to the quantum degeneracy. In recent years, much attention is paid to the unitary Fermi gas with infinite two-body scattering length. According to universal analysis, the thermodynamical law of unitary Fermi gas is similar to that of non-interacting ideal gas, which can be explored by the virial theorem P = 2E/3V. Based on previous works, we further study the unitary Fermi gas properties. The effective chemical potential is introduced to characterize the nonlinear levels crossing effects in a strongly interacting medium. The changing behavior of the rescaled Joule-Thomson coefficient according to temperature manifests a quite different behavior from that for ideal Fermi gas. (general)
Experimental reduction in interaction intensity strongly affects biotic selection.
Sletvold, Nina; Ågren, Jon
2016-11-01
The link between biotic interaction intensity and strength of selection is of fundamental interest for understanding biotically driven diversification and predicting the consequences of environmental change. The strength of selection resulting from biotic interactions is determined by the strength of the interaction and by the covariance between fitness and the trait under selection. When the relationship between trait and absolute fitness is constant, selection strength should be a direct function of mean population interaction intensity. To test this prediction, we excluded pollinators for intervals of different length to induce five levels of pollination intensity within a single plant population. Pollen limitation (PL) increased from 0 to 0.77 across treatments, accompanied by a fivefold increase in the opportunity for selection. Trait-fitness covariance declined with PL for number of flowers, but varied little for other traits. Pollinator-mediated selection on plant height, corolla size, and spur length increased by 91%, 34%, and 330%, respectively, in the most severely pollen-limited treatment compared to open-pollinated plants. The results indicate that realized biotic selection can be predicted from mean population interaction intensity when variation in trait-fitness covariance is limited, and that declines in pollination intensity will strongly increase selection on traits involved in the interaction. © 2016 by the Ecological Society of America.
Directory of Open Access Journals (Sweden)
Toya Nath Baral
Full Text Available Single-domain antibodies (sdAbs derived from human V(H are considered to be less soluble and prone to aggregate which makes it difficult to determine the crystal structures. In this study, we isolated and characterized two anti-human epidermal growth factor receptor-2 (HER2 sdAbs, Gr3 and Gr6, from a synthetic human V(H phage display library. Size exclusion chromatography and surface plasmon resonance analyses demonstrated that Gr3 is a monomer, but that Gr6 is a strict dimer. To understand this different molecular behavior, we solved the crystal structure of Gr6 to 1.6 Å resolution. The crystal structure revealed that the homodimer assembly of Gr6 closely mimics the V(H-V(L heterodimer of immunoglobulin variable domains and the dimerization interface is dominated by hydrophobic interactions.
Nonperturbative Dynamics of Strong Interactions from Gauge/Gravity Duality
Energy Technology Data Exchange (ETDEWEB)
Grigoryan, Hovhannes [Louisiana State Univ., Baton Rouge, LA (United States)
2008-08-01
This thesis studies important dynamical observables of strong interactions such as form factors. It is known that Quantum Chromodynamics (QCD) is a theory which describes strong interactions. For large energies, one can apply perturbative techniques to solve some of the QCD problems. However, for low energies QCD enters into the nonperturbative regime, where di erent analytical or numerical tools have to be applied to solve problems of strong interactions. The holographic dual model of QCD is such an analytical tool that allows one to solve some nonperturbative QCD problems by translating them into a dual ve-dimensional theory de ned on some warped Anti de Sitter (AdS) background. Working within the framework of the holographic dual model of QCD, we develop a formalism to calculate form factors and wave functions of vector mesons and pions. As a result, we provide predictions of the electric radius, the magnetic and quadrupole moments which can be directly veri ed in lattice calculations or even experimentally. To nd the anomalous pion form factor, we propose an extension of the holographic model by including the Chern-Simons term required to reproduce the chiral anomaly of QCD. This allows us to nd the slope of the form factor with one real and one slightly o -shell photon which appeared to be close to the experimental ndings. We also analyze the limit of large virtualities (when the photon is far o -shell) and establish that predictions of the holographic model analytically coincide with those of perturbative QCD with asymptotic pion distribution amplitude. We also study the e ects of higher dimensional terms in the AdS/QCD model and show that these terms improve the holographic description towards a more realistic scenario. We show this by calculating corrections to the vector meson form factors and corrections to the observables such as electric radii, magnetic and quadrupole moments.
International Nuclear Information System (INIS)
Solimannejad, Mohammad; Massahi, Shokofeh; Alkorta, Ibon
2009-01-01
Ab initio calculations at MP2/aug-cc-pVTZ level were used to analyze the interactions between nitrosyl hydride (HNO) dimers and trimers. The structures obtained have been analyzed with the Atoms in Molecules (AIMs) and Natural Bond Orbital (NBO) methodologies. Four minima were located on the potential energy surface of the dimers. Nine different structures have been obtained for the trimers. Three types of interactions are observed, NH···N and NH···O hydrogen bonds and orthogonal interaction between the lone pair of the oxygen with the electron-deficient region of the nitrogen atom. Stabilization energies of dimers and trimers including BSSE and ZPE are in the range 4-8 kJ mol -1 and 12-19 kJ mol -1 , respectively. Blue shift of NH bond upon complex formation in the ranges between 30-80 and 14,114 cm -1 is predicted for dimers and trimers, respectively.
Solimannejad, Mohammad; Massahi, Shokofeh; Alkorta, Ibon
2009-07-01
Ab initio calculations at MP2/aug-cc-pVTZ level were used to analyze the interactions between nitrosyl hydride (HNO) dimers and trimers. The structures obtained have been analyzed with the Atoms in Molecules (AIMs) and Natural Bond Orbital (NBO) methodologies. Four minima were located on the potential energy surface of the dimers. Nine different structures have been obtained for the trimers. Three types of interactions are observed, NH⋯N and NH⋯O hydrogen bonds and orthogonal interaction between the lone pair of the oxygen with the electron-deficient region of the nitrogen atom. Stabilization energies of dimers and trimers including BSSE and ZPE are in the range 4-8 kJ mol -1 and 12-19 kJ mol -1, respectively. Blue shift of NH bond upon complex formation in the ranges between 30-80 and 14,114 cm -1 is predicted for dimers and trimers, respectively.
The hadronic standard model for strong and electroweak interactions
Energy Technology Data Exchange (ETDEWEB)
Raczka, R. [Soltan Inst. for Nuclear Studies, Otwock-Swierk (Poland)
1993-12-31
We propose a new model for strong and electro-weak interactions. First, we review various QCD predictions for hadron-hadron and lepton-hadron processes. We indicate that the present formulation of strong interactions in the frame work of Quantum Chromodynamics encounters serious conceptual and numerical difficulties in a reliable description of hadron-hadron and lepton-hadron interactions. Next we propose to replace the strong sector of Standard Model based on unobserved quarks and gluons by the strong sector based on the set of the observed baryons and mesons determined by the spontaneously broken SU(6) gauge field theory model. We analyse various properties of this model such as asymptotic freedom, Reggeization of gauge bosons and fundamental fermions, baryon-baryon and meson-baryon high energy scattering, generation of {Lambda}-polarization in inclusive processes and others. Finally we extend this model by electro-weak sector. We demonstrate a remarkable lepton and hadron anomaly cancellation and we analyse a series of important lepton-hadron and hadron-hadron processes such as e{sup +} + e{sup -} {yields} hadrons, e{sup +} + e{sup -} {yields} W{sup +} + W{sup -}, e{sup +} + e{sup -} {yields} p + anti-p, e + p {yields} e + p and p + anti-p {yields} p + anti-p processes. We obtained a series of interesting new predictions in this model especially for processes with polarized particles. We estimated the value of the strong coupling constant {alpha}(M{sub z}) and we predicted the top baryon mass M{sub {Lambda}{sub t}} {approx_equal} 240 GeV. Since in our model the proton, neutron, {Lambda}-particles, vector mesons like {rho}, {omega}, {phi}, J/{psi} ect. and leptons are elementary most of experimentally analysed lepton-hadron and hadron-hadron processes in LEP1, LEP2, LEAR, HERA, HERMES, LHC and SSC experiments may be relatively easily analysed in our model. (author). 252 refs, 65 figs, 1 tab.
The hadronic standard model for strong and electroweak interactions
Energy Technology Data Exchange (ETDEWEB)
Raczka, R [Soltan Inst. for Nuclear Studies, Otwock-Swierk (Poland)
1994-12-31
We propose a new model for strong and electro-weak interactions. First, we review various QCD predictions for hadron-hadron and lepton-hadron processes. We indicate that the present formulation of strong interactions in the frame work of Quantum Chromodynamics encounters serious conceptual and numerical difficulties in a reliable description of hadron-hadron and lepton-hadron interactions. Next we propose to replace the strong sector of Standard Model based on unobserved quarks and gluons by the strong sector based on the set of the observed baryons and mesons determined by the spontaneously broken SU(6) gauge field theory model. We analyse various properties of this model such as asymptotic freedom, Reggeization of gauge bosons and fundamental fermions, baryon-baryon and meson-baryon high energy scattering, generation of {Lambda}-polarization in inclusive processes and others. Finally we extend this model by electro-weak sector. We demonstrate a remarkable lepton and hadron anomaly cancellation and we analyse a series of important lepton-hadron and hadron-hadron processes such as e{sup +} + e{sup -} {yields} hadrons, e{sup +} + e{sup -} {yields} W{sup +} + W{sup -}, e{sup +} + e{sup -} {yields} p + anti-p, e + p {yields} e + p and p + anti-p {yields} p + anti-p processes. We obtained a series of interesting new predictions in this model especially for processes with polarized particles. We estimated the value of the strong coupling constant {alpha}(M{sub z}) and we predicted the top baryon mass M{sub {Lambda}{sub t}} {approx_equal} 240 GeV. Since in our model the proton, neutron, {Lambda}-particles, vector mesons like {rho}, {omega}, {phi}, J/{psi} ect. and leptons are elementary most of experimentally analysed lepton-hadron and hadron-hadron processes in LEP1, LEP2, LEAR, HERA, HERMES, LHC and SSC experiments may be relatively easily analysed in our model. (author). 252 refs, 65 figs, 1 tab.
Results from ATLAS and CMS: Strong Interactions and New Physics
AUTHOR|(INSPIRE)INSPIRE-00179262
2016-01-01
Measurements on global properties and precision results on fundamental parameters related to the Strong Interaction sector of the Standard Model of particle physics, and searches for new phenomena beyond the Standard Model, performed by the two large multi-purpose particle detectors at the Large Hadron Collider (LHC), are summarised in this review. Special attention is payed to the new data obtained at $\\sqrt{s}$ = 13~TeV in 2015, which offer a first glimpse at the large physics potential offered by the high-energy running of the LHC.
The kaon factory - towards the physics of strongly interacting systems
International Nuclear Information System (INIS)
Vogt, Erich
1988-01-01
With the advent of the standard model for quarks and leptons and unified forces there are profound new questions for the physics of strongly interacting systems: the nature of the nucleon, the physics of quark confinement, fundamental symmetries governing hadron decay and the effect of quarks and gluons on nuclear behaviour. Of the new large facilities now planned to respond to these questions the kaon factory is central. It uses very intense (∼100 μA) primary proton beams (∼30 GeV) to generate intense secondary beams of various hadrons and leptons. (author)
Strongly modified plasmon-matter interaction with mesoscopic quantum emitters
DEFF Research Database (Denmark)
Andersen, Mads Lykke; Stobbe, Søren; Søndberg Sørensen, Anders
2011-01-01
Semiconductor quantum dots (QDs) provide useful means to couple light and matter in applications such as light-harvesting1, 2 and all-solid-state quantum information processing3, 4. This coupling can be increased by placing QDs in nanostructured optical environments such as photonic crystals...... or metallic nanostructures that enable strong confinement of light and thereby enhance the light–matter interaction. It has thus far been assumed that QDs can be described in the same way as atomic photon emitters—as point sources with wavefunctions whose spatial extent can be disregarded. Here we demonstrate...
Discriminative deep inelastic tests of strong interaction field theories
International Nuclear Information System (INIS)
Glueck, M.; Reya, E.
1979-02-01
It is demonstrated that recent measurements of F 2 (x,Q 2 ) dx eliminate already all strong interaction field theories which do not include colored quarks as well as colored vector gluons. Detailed studies of scaling violations in F 2 (x,Q 2 ) cannot discriminate between a local gauge invariant theory (QCD) and one which has no local color gauge invariance, i.e. no triple-gluon coupling. This implies that all calculations on scaling violations done so far are insensitive to the gluon self-coupling, the latter might perhaps be delineated with future ep colliding beam facilities. (orig.) [de
Directory of Open Access Journals (Sweden)
Xiaolei Wang
2013-12-01
Full Text Available We carried out molecular dynamics simulations and free energy calculations for a series of binary and ternary models of the cisplatin, transplatin and oxaliplatin agents binding to a monomeric Atox1 protein and a dimeric Atox1 protein to investigate their interaction mechanisms. All three platinum agents could respectively combine with the monomeric Atox1 protein and the dimeric Atox1 protein to form a stable binary and ternary complex due to the covalent interaction of the platinum center with the Atox1 protein. The results suggested that the extra interaction from the oxaliplatin ligand–Atox1 protein interface increases its affinity only for the OxaliPt + Atox1 model. The binding of the oxaliplatin agent to the Atox1 protein might cause larger deformation of the protein than those of the cisplatin and transplatin agents due to the larger size of the oxaliplatin ligand. However, the extra interactions to facilitate the stabilities of the ternary CisPt + 2Atox1 and OxaliPt + 2Atox1 models come from the α1 helices and α2-β4 loops of the Atox1 protein–Atox1 protein interface due to the cis conformation of the platinum agents. The combinations of two Atox1 proteins in an asymmetric way in the three ternary models were analyzed. These investigations might provide detailed information for understanding the interaction mechanism of the platinum agents binding to the Atox1 protein in the cytoplasm.
A strong viscous–inviscid interaction model for rotating airfoils
DEFF Research Database (Denmark)
Ramos García, Néstor; Sørensen, Jens Nørkær; Shen, Wen Zhong
2014-01-01
Two-dimensional (2D) and quasi-three dimensional (3D), steady and unsteady, viscous–inviscid interactive codes capable of predicting the aerodynamic behavior of wind turbine airfoils are presented. The model is based on a viscous–inviscid interaction technique using strong coupling between...... a boundary-layer trip or computed using an en envelope transition method. Validation of the incompressible 2D version of the code is carried out against measurements and other numerical codes for different airfoil geometries at various Reynolds numbers, ranging from 0.9 ⋅ 106 to 8.2 ⋅ 106. In the quasi-3D...... version, a parametric study on rotational effects induced by the Coriolis and centrifugal forces in the boundary-layer equations shows that the effects of rotation are to decrease the growth of the boundary-layer and delay the onset of separation, hence increasing the lift coefficient slightly while...
Dynamical equilibration in strongly-interacting parton-hadron matter
Directory of Open Access Journals (Sweden)
Gorenstein M.
2011-04-01
Full Text Available We study the kinetic and chemical equilibration in 'infinite' parton-hadron matter within the Parton-Hadron-String Dynamics transport approach, which is based on a dynamical quasiparticle model for partons matched to reproduce lattice-QCD results – including the partonic equation of state – in thermodynamic equilibrium. The 'infinite' matter is simulated within a cubic box with periodic boundary conditions initialized at different baryon density (or chemical potential and energy density. The transition from initially pure partonic matter to hadronic degrees of freedom (or vice versa occurs dynamically by interactions. Different thermody-namical distributions of the strongly-interacting quark-gluon plasma (sQGP are addressed and discussed.
On the mixed phase of strongly interacting matter
International Nuclear Information System (INIS)
Suleymanov, M.K.; Abdinov, O.B.; Belashev, B.Z.; Guseynaliyev, Y.G.; Vodoplanov, A.S.
2005-01-01
Full text : The studying of the behavior of some characteristics of hadron-nuclear and nuclear-nuclear interactions as a function of the collision centrality Q is an important experimental method to get information about the changes of nuclear matter phase, because the increasing of the centrality could lead to the growth of the nuclear matter baryon density. The regime change in the behavior of some centrality depending characteristics of events is expected by the varying the Q. It would be the signal about the phase transition. This method is considered as the best tool reaching the quark-gluon plasma phase of strongly interacting matter. Some experimental results demonstrate already the existence of the regime changes in the event characteristics behavior as a function of collision centrality
Local condensate depletion at trap center under strong interactions
Yukalov, V. I.; Yukalova, E. P.
2018-04-01
Cold trapped Bose-condensed atoms, interacting via hard-sphere repulsive potentials are considered. Simple mean-field approximations show that the condensate distribution inside a harmonic trap always has the shape of a hump with the maximum condensate density occurring at the trap center. However, Monte Carlo simulations at high density and strong interactions display the condensate depletion at the trap center. The explanation of this effect of local condensate depletion at trap center is suggested in the frame of self-consistent theory of Bose-condensed systems. The depletion is shown to be due to the existence of the anomalous average that takes into account pair correlations and appears in systems with broken gauge symmetry.
Universal structure of a strongly interacting Fermi gas
Energy Technology Data Exchange (ETDEWEB)
Kuhnle, Eva; Dyke, Paul; Hoinka, Sascha; Mark, Michael; Hu Hui; Liu Xiaji; Drummond, Peter; Hannaford, Peter; Vale, Chris, E-mail: cvale@swin.edu.au [ARC Centre of Excellence for Quantum Atom Optics, Swinburne University of Technology, Hawthorn 3122 (Australia)
2011-01-10
This paper presents studies of the universal properties of strongly interacting Fermi gases using Bragg spectroscopy. We focus on pair-correlations, their relationship to the contact C introduced by Tan, and their dependence on both the momentum and temperature. We show that short-range pair correlations obey a universal law, first derived by Tan through measurements of the static structure factor, which displays a universal scaling with the ratio of the contact to the momentum C/q. Bragg spectroscopy of ultracold {sup 6}Li atoms is employed to measure the structure factor for a wide range of momenta and interaction strengths, providing broad confirmation of this universal law. We show that calibrating our Bragg spectra using the f-sum rule leads to a dramatic improvement in the accuracy of the structure factor measurement. We also measure the temperature dependence of the contact in a unitary gas and compare our results to calculations based on a virial expansion.
Theoretical Studies of Strongly Interacting Fine Particle Systems
Fearon, Michael
Available from UMI in association with The British Library. A theoretical analysis of the time dependent behaviour of a system of fine magnetic particles as a function of applied field and temperature was carried out. The model used was based on a theory assuming Neel relaxation with a distribution of particle sizes. This theory predicted a linear variation of S_{max} with temperature and a finite intercept, which is not reflected by experimental observations. The remanence curves of strongly interacting fine-particle systems were also investigated theoretically. It was shown that the Henkel plot of the dc demagnetisation remanence vs the isothermal remanence is a useful representation of interactions. The form of the plot was found to be a reflection of the magnetic and physical microstructure of the material, which is consistent with experimental data. The relationship between the Henkel plot and the noise of a particulate recording medium, another property dependent on the microstructure, is also considered. The Interaction Field Factor (IFF), a single parameter characterising the non-linearity of the Henkel plot, is investigated. These results are consistent with a previous experimental study. Finally the results of the noise power spectral density for erased and saturated recording media are presented, so that characterisation of interparticle interactions may be carried out with greater accuracy.
Non-equilibrium magnetic interactions in strongly correlated systems
Energy Technology Data Exchange (ETDEWEB)
Secchi, A., E-mail: a.secchi@science.ru.nl [Institute for Molecules and Materials, Radboud University Nijmegen, 6525 AJ Nijmegen (Netherlands); Brener, S.; Lichtenstein, A.I. [Institut für Theoretische Physik, Universitat Hamburg, Jungiusstraße 9, D-20355 Hamburg (Germany); Katsnelson, M.I. [Institute for Molecules and Materials, Radboud University Nijmegen, 6525 AJ Nijmegen (Netherlands)
2013-06-15
We formulate a low-energy theory for the magnetic interactions between electrons in the multi-band Hubbard model under non-equilibrium conditions determined by an external time-dependent electric field which simulates laser-induced spin dynamics. We derive expressions for dynamical exchange parameters in terms of non-equilibrium electronic Green functions and self-energies, which can be computed, e.g., with the methods of time-dependent dynamical mean-field theory. Moreover, we find that a correct description of the system requires, in addition to exchange, a new kind of magnetic interaction, that we name twist exchange, which formally resembles Dzyaloshinskii–Moriya coupling, but is not due to spin–orbit, and is actually due to an effective three-spin interaction. Our theory allows the evaluation of the related time-dependent parameters as well. -- Highlights: •We develop a theory for magnetism of strongly correlated systems out of equilibrium. •Our theory is suitable for laser-induced ultrafast magnetization dynamics. •We write time-dependent exchange parameters in terms of electronic Green functions. •We find a new magnetic interaction, a “twist exchange”. •We give general expressions for magnetic noise in itinerant-electron systems.
Directory of Open Access Journals (Sweden)
Katarzyna Marta Bocian-Ostrzycka
2015-10-01
Full Text Available Helicobacter pylori does not encode the classical DsbA/DsbB oxidoreductases that are crucial for oxidative folding of extracytoplasmic proteins. Instead, this microorganism encodes an untypical two proteins playing a role in disulfide bond formation – periplasmic HP0231, which structure resembles that of EcDsbC/DsbG, and its redox partner, a membrane protein HpDsbI (HP0595 with a -propeller structure. The aim of presented work was to assess relations between HP0231 structure and function.We showed that HP0231 is most closely related evolutionarily to the catalytic domain of DsbG, even though it possesses a catalytic motif typical for canonical DsbA proteins. Similarly, the highly diverged N-terminal dimerization domain is homologous to the dimerization domain of DsbG. To better understand the functioning of this atypical oxidoreductase, we examined its activity using in vivo and in vitro experiments. We found that HP0231 exhibits oxidizing and chaperone activities but no isomerizing activity, even though H. pylori does not contain a classical DsbC. We also show that HP0231 is not involved in the introduction of disulfide bonds into HcpC (Helicobacter cysteine-rich protein C, a protein involved in the modulation of the H. pylori interaction with its host. Additionally, we also constructed a truncated version of HP0231 lacking the dimerization domain, denoted HP0231m, and showed that it acts in E. coli cells in a DsbB-dependent manner. In contrast, HP0231m and classical monomeric EcDsbA (Escherichia coli DsbA protein were both unable to complement the lack of HP0231 in H. pylori cells, though they exist in oxidized forms. HP0231m is inactive in the insulin reduction assay and possesses high chaperone activity, in contrast to EcDsbA. In conclusion, HP0231 combines oxidative functions characteristic of DsbA proteins and chaperone activity characteristic of DsbC/DsbG, and it lacks isomerization activity.
Effective interactions in strongly-coupled quantum systems
International Nuclear Information System (INIS)
Chen, J.M.C.
1986-01-01
In this thesis, they study the role of effective interactions in strongly-coupled Fermi systems where the short-range correlations introduce difficulties requiring special treatment. The correlated basis function method provides the means to incorporate the short-range correlations and generate the matrix elements of the Hamiltonian and identity operators in a nonorthogonal basis of states which are so important to their studies. In the first half of the thesis, the particle-hole channel is examined to elucidate the effects of collective excitations. Proceeding from a least-action principle, a generalization of the random-phase approximation is developed capable of describing such strongly-interacting Fermi systems as nuclei, nuclear matter, neutron-star matter, and liquid 3 He. A linear response of dynamically correlated system to a weak external perturbation is also derived based on the same framework. In the second half of the thesis, the particle-particle channel is examined to elucidate the effects of pairing in nuclear and neutron-star matter
Strong interactions and electromagnetism in low-energy hadron physics
International Nuclear Information System (INIS)
Kubis, B.
2002-10-01
In the present work, we study various aspects of the entanglement of the strong and electromagnetic interactions as it is manifest in low-energy hadron physics. In the framework of chiral perturbation theory, two aspects are investigated: the test of the structure of baryons as probed by external electromagnetic currents, and the modification of reactions mediated by the strong interactions in the presence of internal (virtual) photons. In the first part of this work, we study the electromagnetic form factors of nucleons and the ground state baryon octet, as well as strangeness form factors of the nucleon. Emphasis is put on the comparison of a new relativistic scheme for the calculation of loop diagrams to the heavy-baryon formalism, and on the convergence of higher-order corrections in both schemes. The new scheme is shown to yield both a phenomenologically more successful description of the data and better convergence behaviour. In the second part, we study isospin violation in pion-kaon scattering as mediated by virtual photon effects and the light quark mass difference. This investigation is of particular importance for the extraction of scattering lengths from measurements of lifetime and energy levels in pion-kaon atoms. The isospin breaking corrections are shown to be small and sufficiently well under control. (orig.)
Relativistic strings and dual models of strong interactions
International Nuclear Information System (INIS)
Marinov, M.S.
1977-01-01
The theory of strong interactions,based on the model depicting a hardon as a one-dimentional elastic relativistic system(''string'') is considered. The relationship between this model and the concepts of quarks and partons is discussed. Presented are the principal results relating to the Veneziano dual theory, which may be considered as the consequence of the string model, and to its modifications. The classical string theory is described in detail. Attention is focused on questions of importance to the construction of the quantum theory - the Hamilton mechanisms and conformal symmetry. Quantization is described, and it is shown that it is not contradictory only in the 26-dimentional space and with a special requirement imposed on the spectrum of states. The theory of a string with a distributed spin is considered. The spin is introduced with the aid of the Grassman algebra formalism. In this case quantization is possible only in the 10-dimentional space. The strings interact by their ruptures and gluings. A method for calculating the interaction amplitudes is indicated
Fragment-Based Protein-Protein Interaction Antagonists of a Viral Dimeric Protease.
Gable, Jonathan E; Lee, Gregory M; Acker, Timothy M; Hulce, Kaitlin R; Gonzalez, Eric R; Schweigler, Patrick; Melkko, Samu; Farady, Christopher J; Craik, Charles S
2016-04-19
Fragment-based drug discovery has shown promise as an approach for challenging targets such as protein-protein interfaces. We developed and applied an activity-based fragment screen against dimeric Kaposi's sarcoma-associated herpesvirus protease (KSHV Pr) using an optimized fluorogenic substrate. Dose-response determination was performed as a confirmation screen, and NMR spectroscopy was used to map fragment inhibitor binding to KSHV Pr. Kinetic assays demonstrated that several initial hits also inhibit human cytomegalovirus protease (HCMV Pr). Binding of these hits to HCMV Pr was also confirmed by NMR spectroscopy. Despite the use of a target-agnostic fragment library, more than 80 % of confirmed hits disrupted dimerization and bound to a previously reported pocket at the dimer interface of KSHV Pr, not to the active site. One class of fragments, an aminothiazole scaffold, was further explored using commercially available analogues. These compounds demonstrated greater than 100-fold improvement of inhibition. This study illustrates the power of fragment-based screening for these challenging enzymatic targets and provides an example of the potential druggability of pockets at protein-protein interfaces. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
Noise in strong laser-atom interactions: Phase telegraph noise
International Nuclear Information System (INIS)
Eberly, J.H.; Wodkiewicz, K.; Shore, B.W.
1984-01-01
We discuss strong laser-atom interactions that are subjected to jump-type (random telegraph) random-phase noise. Physically, the jumps may arise from laser fluctuations, from collisions of various kinds, or from other external forces. Our discussion is carried out in two stages. First, direct and partially heuristic calculations determine the laser spectrum and also give a third-order differential equation for the average inversion of a two-level atom on resonance. At this stage a number of general features of the interaction are able to be studied easily. The optical analog of motional narrowing, for example, is clearly predicted. Second, we show that the theory of generalized Poisson processes allows laser-atom interactions in the presence of random telegraph noise of all kinds (not only phase noise) to be treated systematically, by means of a master equation first used in the context of quantum optics by Burshtein. We use the Burshtein equation to obtain an exact expression for the two-level atom's steady-state resonance fluorescence spectrum, when the exciting laser exhibits phase telegraph noise. Some comparisons are made with results obtained from other noise models. Detailed treatments of the effects ofmly jumps, or as a model of finite laser bandwidth effects, in which the laser frequency exhibits random jumps. We show that these two types of frequency noise can be distinguished in light-scattering spectra. We also discuss examples which demonstrate both temporal and spectral motional narrowing, nonexponential correlations, and non-Lorentzian spectra. Its exact solubility in finite terms makes the frequency-telegraph noise model an attractive alternative to the white-noise Ornstein-Uhlenbeck frequency noise model which has been previously applied to laser-atom interactions
Extreme states of matter in strong interaction physics an introduction
Satz, Helmut
2018-01-01
This book is a course-tested primer on the thermodynamics of strongly interacting matter – a profound and challenging area of both theoretical and experimental modern physics. Analytical and numerical studies of statistical quantum chromodynamics provide the main theoretical tool, while in experiments, high-energy nuclear collisions are the key for extensive laboratory investigations. As such, the field straddles statistical, particle and nuclear physics, both conceptually and in the methods of investigation used. The book addresses, above all, the many young scientists starting their scientific research in this field, providing them with a general, self-contained introduction that highlights the basic concepts and ideas and explains why we do what we do. Much of the book focuses on equilibrium thermodynamics: first it presents simplified phenomenological pictures, leading to critical behavior in hadronic matter and to a quark-hadron phase transition. This is followed by elements of finite temperature latti...
Stability of Dirac Liquids with Strong Coulomb Interaction.
Tupitsyn, Igor S; Prokof'ev, Nikolay V
2017-01-13
We develop and apply the diagrammatic Monte Carlo technique to address the problem of the stability of the Dirac liquid state (in a graphene-type system) against the strong long-range part of the Coulomb interaction. So far, all attempts to deal with this problem in the field-theoretical framework were limited either to perturbative or random phase approximation and functional renormalization group treatments, with diametrically opposite conclusions. Our calculations aim at the approximation-free solution with controlled accuracy by computing vertex corrections from higher-order skeleton diagrams and establishing the renormalization group flow of the effective Coulomb coupling constant. We unambiguously show that with increasing the system size L (up to ln(L)∼40), the coupling constant always flows towards zero; i.e., the two-dimensional Dirac liquid is an asymptotically free T=0 state with divergent Fermi velocity.
Screening important inputs in models with strong interaction properties
International Nuclear Information System (INIS)
Saltelli, Andrea; Campolongo, Francesca; Cariboni, Jessica
2009-01-01
We introduce a new method for screening inputs in mathematical or computational models with large numbers of inputs. The method proposed here represents an improvement over the best available practice for this setting when dealing with models having strong interaction effects. When the sample size is sufficiently high the same design can also be used to obtain accurate quantitative estimates of the variance-based sensitivity measures: the same simulations can be used to obtain estimates of the variance-based measures according to the Sobol' and the Jansen formulas. Results demonstrate that Sobol' is more efficient for the computation of the first-order indices, while Jansen performs better for the computation of the total indices.
Screening important inputs in models with strong interaction properties
Energy Technology Data Exchange (ETDEWEB)
Saltelli, Andrea [European Commission, Joint Research Centre, 21020 Ispra, Varese (Italy); Campolongo, Francesca [European Commission, Joint Research Centre, 21020 Ispra, Varese (Italy)], E-mail: francesca.campolongo@jrc.it; Cariboni, Jessica [European Commission, Joint Research Centre, 21020 Ispra, Varese (Italy)
2009-07-15
We introduce a new method for screening inputs in mathematical or computational models with large numbers of inputs. The method proposed here represents an improvement over the best available practice for this setting when dealing with models having strong interaction effects. When the sample size is sufficiently high the same design can also be used to obtain accurate quantitative estimates of the variance-based sensitivity measures: the same simulations can be used to obtain estimates of the variance-based measures according to the Sobol' and the Jansen formulas. Results demonstrate that Sobol' is more efficient for the computation of the first-order indices, while Jansen performs better for the computation of the total indices.
Towards a unified gauge theory of gravitational and strong interactions
International Nuclear Information System (INIS)
Hehl, F.W.; Sijacki, D.
1980-01-01
The space-time properties of leptons and hadrons is studied and it is found necessary to extend general relativity to the gauge theory based on the four-dimensional affine group. This group translates and deforms the tetrads of the locally Minkowskian space-time. Its conserved currents, momentum, and hypermomentum, act as sources in the two field equations of gravity. A Lagrangian quadratic in torsion and curvature allows for the propagation of two independent gauge fields: translational e-gravity mediated by the tetrad coefficients, and deformational GAMMA-gravity mediated by the connection coefficients. For macroscopic matter e-gravity coincides with general relativity up to the post-Newtonian approximation of fourth order. For microscopic matter GAMMA-gravity represents a strong Yang-Mills type interaction. In the linear approximation, for a static source, a confinement potential is found. (author)
Are Higgs particles strongly interacting(question mark)
International Nuclear Information System (INIS)
Shanker, O.
1982-02-01
The order of magnitude of Yukawa couplings in some theories with flavour violating Higgs particles is estimated. Based on these couplings, mass bounds for flavour violating Higgs particles are derived from the Ksub(L)-Ksub(S) mass difference. The Higgs particles have to be very heavy, implying that the Higgs sector quartic couplings are very large. Thus, these theories seem to require a strongly interacting Higgs sector unless one adjusts to the Higgs-fermion Yukawa couplings to within two orders of magnitude, so as to suppress the coupling of Higgs particles to the flavour-violating anti sd current. Most models with flavour violating Higgs particles have the same general features, so the conclusions are likely to hold for a wide class of models with flavour violating Higgs particles
Ion Motion in a Plasma Interacting with Strong Magnetic Fields
International Nuclear Information System (INIS)
Weingarten, A.; Grabowski, C.; Chakrabarti, N.; Maron, Y.; Fruchtmant, A.
1999-01-01
The interaction of a plasma with strong magnetic fields takes place in many laboratory experiments and astrophysical plasmas. Applying a strong magnetic field to the plasma may result in plasma displacement, magnetization, or the formation of instabilities. Important phenomena in plasma, such as the energy transport and the momentum balance, take a different form in each case. We study this interaction in a plasma that carries a short-duration (80-ns) current pulse, generating a magnetic field of up to 17 kG. The evolution of the magnetic field, plasma density, ion velocities, and electric fields are determined before and during the current pulse. The dependence of the plasma limiting current on the plasma density and composition are studied and compared to theoretical models based on the different phenomena. When the plasma collisionality is low, three typical velocities should be taken into consideration: the proton and heavier-ion Alfven velocities (v A p and v A h , respectively) and the EMHD magnetic-field penetration velocity into the plasma (v EMHD ). If both Alfven velocities are larger than v EMHD the plasma is pushed ahead of the magnetic piston and the magnetic field energy is dissipated into ion kinetic energy. If v EMHD is the largest of three velocities, the plasma become magnetized and the ions acquire a small axial momentum only. Different ion species may drift in different directions along the current lines. In this case, the magnetic field energy is probably dissipated into electron thermal energy. When vs > V EMHD > vi, as in the case of one of our experiments, ion mass separation occurs. The protons are pushed ahead of the piston while the heavier-ions become magnetized. Since the plasma electrons are unmagnetized they cannot cross the piston, and the heavy ions are probably charge-neutralized by electrons originating from the cathode that are 'born' magnetized
Kaonic atoms – studies of the strong interaction with strangeness
Directory of Open Access Journals (Sweden)
Marton J.
2014-01-01
Full Text Available The strong interaction of charged antikaons (K− with nucleons and nuclei in the low-energy regime is a fascinating topic. The antikaon plays a peculiar role in hadron physics due to the strong attraction antikaon-nucleon which is a key question for possible kaonic nuclear bound states. A rather direct experimental access to the antikaon-nucleon scattering lengths is provided by precision X-ray spectroscopy of transitions to low-lying states in light kaonic atoms like kaonic hydrogen and deuterium. After the successful completion of precision measurements on kaonic hydrogen and helium isotopes by SIDDHARTA at DAΦNE/LNF, new X-ray studies with the focus on kaonic deuterium are in preparation (SIDDHARTA2. In the future with kaonic deuterium data the antikaon-nucleon isospin-dependent scattering lengths can be extracted for the first time. An overview of the experimental results of SIDDHARTA and an outlook to future perspectives in the SIDDHARTA2 experiments in this frontier research field will be given.
Chemical Evolution of Strongly Interacting Quark-Gluon Plasma
International Nuclear Information System (INIS)
Pan, Ying-Hua; Zhang, Wei-Ning
2014-01-01
At very initial stage of relativistic heavy ion collisions a wave of quark-gluon matter is produced from the break-up of the strong color electric field and then thermalizes at a short time scale (~1 fm/c). However, the quark-gluon plasma (QGP) system is far out of chemical equilibrium, especially for the heavy quarks which are supposed to reach chemical equilibrium much late. In this paper a continuing quark production picture for strongly interacting QGP system is derived, using the quark number susceptibilities and the equation of state; both of them are from the results calculated by the Wuppertal-Budapest lattice QCD collaboration. We find that the densities of light quarks increase by 75% from the temperature T=400 MeV to T=150 MeV, while the density of strange quark annihilates by 18% in the temperature region. We also offer a discussion on how this late production of quarks affects the final charge-charge correlations
Universal contact of strongly interacting fermions at finite temperatures
Energy Technology Data Exchange (ETDEWEB)
Hu Hui; Liu Xiaji; Drummond, Peter D, E-mail: hhu@swin.edu.au, E-mail: xiajiliu@swin.edu.au, E-mail: pdrummond@swin.edu.au [ARC Centre of Excellence for Quantum-Atom Optics, Centre for Atom Optics and Ultrafast Spectroscopy, Swinburne University of Technology, Melbourne 3122 (Australia)
2011-03-15
The recently discovered universal thermodynamic behavior of dilute, strongly interacting Fermi gases also implies a universal structure in the many-body pair-correlation function at short distances, as quantified by the contact I. Here, we theoretically calculate the temperature dependence of this universal contact for a Fermi gas in free space and in a harmonic trap. At high temperatures above the Fermi degeneracy temperature, T{approx}>T{sub F}, we obtain a reliable non-perturbative quantum virial expansion up to third order. At low temperatures, we compare different approximate strong-coupling theories. These make different predictions, which need to be tested either by future experiments or by advanced quantum Monte Carlo simulations. We conjecture that in the universal unitarity limit, the contact or correlation decreases monotonically with increasing temperature, unless the temperature is significantly lower than the critical temperature, T<
Energy Technology Data Exchange (ETDEWEB)
Zhong, Rong-Lin; Li, Zhi-Ru, E-mail: hlxu@nenu.edu.cn, E-mail: lzr@jlu.edu.cn [Institute of Theoretical Chemistry, Jilin University, Changchun 130023 (China); Xu, Hong-Liang, E-mail: hlxu@nenu.edu.cn, E-mail: lzr@jlu.edu.cn [Institute of Functional Material Chemistry, Faculty of Chemistry, Northeast Normal University, Changchun, Jilin 130024 (China)
2016-08-07
An increasing number of chemists have focused on the two-electron/multicenter bond (2e/mc) that was first introduced to interpret the bonding mechanism of radical dimers. Herein, we report the polar two-electron/twelve center (2e/12c) bonding character in a series of phenalenyl-azaphenalenyl radical hetero-dimers. Interestingly, the bonding energy of weaker polar hetero-dimer (P-TAP) is dominated by the overlap of the two different singly occupied molecular orbital of radicals, while that of stronger polar hetero-dimer (P-HAP) is dominated by the electrostatic attraction. Results show that the difference between the electronegativity of the monomers plays a prominent role in the essential attribution of the polar 2e/12c bond. Correspondingly, a stronger stacking interaction in the hetero-dimer could be effectively achieved by increasing the difference of nitrogen atoms number between the monomers. It is worthy of note that an interesting interlayer charge transfer character is induced in the polar hetero-dimers, which is dependent on the difference between the electronegativity of the monomers. It is our expectation that the new knowledge about the bonding nature of radical hetero-dimers might provide important information for designing radical based functional materials with various applications.
Air-sea interactions during strong winter extratropical storms
Nelson, Jill; He, Ruoying; Warner, John C.; Bane, John
2014-01-01
A high-resolution, regional coupled atmosphere–ocean model is used to investigate strong air–sea interactions during a rapidly developing extratropical cyclone (ETC) off the east coast of the USA. In this two-way coupled system, surface momentum and heat fluxes derived from the Weather Research and Forecasting model and sea surface temperature (SST) from the Regional Ocean Modeling System are exchanged via the Model Coupling Toolkit. Comparisons are made between the modeled and observed wind velocity, sea level pressure, 10 m air temperature, and sea surface temperature time series, as well as a comparison between the model and one glider transect. Vertical profiles of modeled air temperature and winds in the marine atmospheric boundary layer and temperature variations in the upper ocean during a 3-day storm period are examined at various cross-shelf transects along the eastern seaboard. It is found that the air–sea interactions near the Gulf Stream are important for generating and sustaining the ETC. In particular, locally enhanced winds over a warm sea (relative to the land temperature) induce large surface heat fluxes which cool the upper ocean by up to 2 °C, mainly during the cold air outbreak period after the storm passage. Detailed heat budget analyses show the ocean-to-atmosphere heat flux dominates the upper ocean heat content variations. Results clearly show that dynamic air–sea interactions affecting momentum and buoyancy flux exchanges in ETCs need to be resolved accurately in a coupled atmosphere–ocean modeling framework.
Fossé, P; Motté, N; Roumier, A; Gabus, C; Muriaux, D; Darlix, J L; Paoletti, J
1996-12-24
Retroviral genomes consist of two identical RNA molecules joined noncovalently near their 5'-ends. Recently, two models have been proposed for RNA dimer formation on the basis of results obtained in vitro with human immunodeficiency virus type 1 RNA and Moloney murine leukemia virus RNA. It was first proposed that viral RNA dimerizes by forming an interstrand quadruple helix with purine tetrads. The second model postulates that RNA dimerization is initiated by a loop-loop interaction between the two RNA molecules. In order to better characterize the dimerization process of retroviral genomic RNA, we analyzed the in vitro dimerization of avian sarcoma-leukosis virus (ASLV) RNA using different transcripts. We determined the requirements for heterodimer formation, the thermal dissociation of RNA dimers, and the influence of antisense DNA oligonucleotides on dimer formation. Our results strongly suggest that purine tetrads are not involved in dimer formation. Data show that an autocomplementary sequence located upstream from the splice donor site and within a major packaging signal plays a crucial role in ASLV RNA dimer formation in vitro. This sequence is able to form a stem-loop structure, and phylogenetic analysis reveals that it is conserved in 28 different avian sarcoma and leukosis viruses. These results suggest that dimerization of ASLV RNA is initiated by a loop-loop interaction between two RNA molecules and provide an additional argument for the ubiquity of the dimerization process via loop-loop interaction.
International Nuclear Information System (INIS)
Bishop, Raymond F; Krueger, Sven E
2003-01-01
The coupled cluster method (CCM) of microscopic quantum many-body theory has become an ab initio method of first choice in quantum chemistry and many fields of nuclear, subnuclear and condensed matter physics, when results of high accuracy are required. In recent years it has begun to be applied with equal success to strongly correlated systems of electrons or quantum spins defined on a regular spatial lattice. One regularly finds that the CCM is able to describe accurately the various zero-temperature phases and the quantum phase transitions between them, even when frustration is present and other methods such as quantum Monte Carlo often fail. We illustrate the use and powerfulness of the method here by applying it to a square-lattice spin-half Heisenberg model where frustration is introduced by competing nearest neighbour bonds. The model exhibits the physically interesting phenomenon of competition between magnetic order and dimerization. Results obtained for the model with the CCM are compared with those found from spin-wave theory and from extrapolating the results of exact diagonalizations of small lattices. We show that the CCM is essentially unique among available methods in being able both to describe accurately all phases of this complex model and to provide accurate predictions of the various phase boundaries and the order of the corresponding transitions
Inverse problem for the mean-field monomer-dimer model with attractive interaction
International Nuclear Information System (INIS)
Contucci, Pierluigi; Luzi, Rachele; Vernia, Cecilia
2017-01-01
The inverse problem method is tested for a class of monomer-dimer statistical mechanics models that contain also an attractive potential and display a mean-field critical point at a boundary of a coexistence line. The inversion is obtained by analytically identifying the parameters in terms of the correlation functions and via the maximum-likelihood method. The precision is tested in the whole phase space and, when close to the coexistence line, the algorithm is used together with a clustering method to take care of the underlying possible ambiguity of the inversion. (paper)
Peter, Bradley; Polyansky, Anton A; Fanucchi, Sylvia; Dirr, Heini W
2014-01-14
Chloride intracellular channel protein 1 (CLIC1) is a dual-state protein that can exist either as a soluble monomer or in an integral membrane form. The oligomerization of the transmembrane domain (TMD) remains speculative despite it being implicated in pore formation. The extent to which electrostatic and van der Waals interactions drive folding and association of the dimorphic TMD is unknown and is complicated by the requirement of interactions favorable in both aqueous and membrane environments. Here we report a putative Lys37-Trp35 cation-π interaction and show that it stabilizes the dimeric form of the CLIC1 TMD in membranes. A synthetic 30-mer peptide comprising a K37M TMD mutant was examined in 2,2,2-trifluoroethanol, sodium dodecyl sulfate micelles, and 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine liposomes using far-ultraviolet (UV) circular dichroism, fluorescence, and UV absorbance spectroscopy. Our data suggest that Lys37 is not implicated in the folding, stability, or membrane insertion of the TMD peptide. However, removal of this residue impairs the formation of dimers and higher-order oligomers. This is accompanied by a 30-fold loss of chloride influx activity, suggesting that dimerization modulates the rate of chloride conductance. We propose that, within membranes, individual TMD helices associate via a Lys37-mediated cation-π interaction to form active dimers. The latter findings are also supported by results of modeling a putative TMD dimer conformation in which Lys37 and Trp35 form cation-π pairs at the dimer interface. Dimeric helix bundles may then associate to form fully active ion channels. Thus, within a membrane-like environment, aromatic interactions involving a polar lysine side chain provide a thermodynamic driving force for helix-helix association.
Theoretical & Experimental Research in Weak, Electromagnetic & Strong Interactions
Energy Technology Data Exchange (ETDEWEB)
Nandi, Satyanarayan [Oklahoma State Univ., Stillwater, OK (United States); Babu, Kaladi [Oklahoma State Univ., Stillwater, OK (United States); Rizatdinova, Flera [Oklahoma State Univ., Stillwater, OK (United States); Khanov, Alexander [Oklahoma State Univ., Stillwater, OK (United States); Haley, Joseph [Oklahoma State Univ., Stillwater, OK (United States)
2015-09-17
The conducted research spans a wide range of topics in the theoretical, experimental and phenomenological aspects of elementary particle interactions. Theory projects involve topics in both the energy frontier and the intensity frontier. The experimental research involves energy frontier with the ATLAS Collaboration at the Large Hadron Collider (LHC). In theoretical research, novel ideas going beyond the Standard Model with strong theoretical motivations were proposed, and their experimental tests at the LHC and forthcoming neutrino facilities were outlined. These efforts fall into the following broad categories: (i) TeV scale new physics models for LHC Run 2, including left-right symmetry and trinification symmetry, (ii) unification of elementary particles and forces, including the unification of gauge and Yukawa interactions, (iii) supersummetry and mechanisms of supersymmetry breaking, (iv) superworld without supersymmetry, (v) general models of extra dimensions, (vi) comparing signals of extra dimensions with those of supersymmetry, (vii) models with mirror quarks and mirror leptons at the TeV scale, (viii) models with singlet quarks and singlet Higgs and their implications for Higgs physics at the LHC, (ix) new models for the dark matter of the universe, (x) lepton flavor violation in Higgs decays, (xi) leptogenesis in radiative models of neutrino masses, (xii) light mediator models of non-standard neutrino interactions, (xiii) anomalous muon decay and short baseline neutrino anomalies, (xiv) baryogenesis linked to nucleon decay, and (xv) a new model for recently observed diboson resonance at the LHC and its other phenomenological implications. The experimental High Energy Physics group has been, and continues to be, a successful and productive contributor to the ATLAS experiment at the LHC. Members of the group performed search for gluinos decaying to stop and top quarks, new heavy gauge bosons decaying to top and bottom quarks, and vector-like quarks
DEFF Research Database (Denmark)
Lyngsø, Christina; Erikstrup, Niels; Hansen, Jakob L
2008-01-01
. The importance of the RAS is clearly emphasised by the widespread use of drugs targeting this system in clinical practice. These include, renin inhibitors, angiotensin II receptor type I blockers, and inhibitors of the angiotensin converting enzyme. Some of the important effectors within the system are 7...... be important for receptor function, and in the development of cardiovascular diseases. This is very significant, since "dimers" may provide pharmacologists with novel targets for improved drug therapy. However, we know that 7TM receptors can mediate signals as monomeric units, and so far it has been very......The Renin-Angiotensin System (RAS) is important for the regulation of cardiovascular physiology, where it controls blood pressure, and salt- and water homeostasis. Dysregulation of RAS can lead to severe diseases including hypertension, diabetic nephropathy, and cardiac arrhythmia, and -failure...
Effective Field Theories and Strong Interactions. Final Technical Report
International Nuclear Information System (INIS)
Fleming, Sean
2011-01-01
The framework of Effective Field Theories (EFTs) allows us to describe strong interactions in terms of degrees of freedom relevant to the energy regimes of interest, in the most general way consistent with the symmetries of QCD. Observables are expanded systematically in powers of M lo /M hi , where M lo (M hi ) denotes a low-(high-)energy scale. This organizational principle is referred to as 'power counting'. Terms of increasing powers in the expansion parameter are referred to as leading order (LO), next-to-leading order (NLO), etc. Details of the QCD dynamics not included explicitly are encoded in interaction parameters, or 'low-energy constants' (LECs), which can in principle be calculated from an explicit solution of QCD - for example via lattice simulations- but can also be determined directly from experimental data. QCD has an intrinsic scale M QCD ≅ 1 GeV, at which the QCD coupling constant α s (M QCD ) becomes large and the dynamics becomes non-perturbative. As a consequence M QCD sets the scale for the masses of most hadrons, such as the nucleon mass m N ≅ 940 MeV. EFTs can roughly be divided into two categories: those that can be matched onto QCD in perturbation theory, which we call high-energy EFTs, and those that cannot be matched perturbatively, which we call low-energy EFTs. In high-energy EFTs, M QCD typically sets the low-energy scale, and all the dynamics associated with this scale reside in matrix elements of EFT operators. These non-perturbative matrix elements are the LECs and are also referred to as long-distance contributions. Each matrix element is multiplied by a short-distance coefficient, which contains the dynamics from the high scale M hi . Since M hi >> M QCD , α s (M hi ) hi ∼ M Q , the heavy-quark mass, and in addition to M QCD there are low scales associated with the typical relative momentum ∼ M Q v and energy ∼ M Q v 2 of the heavy quarks. Depending on the sizes of M Q and the heavy-quark velocity v these scales can
Phases of strongly-interacting matter with functional methods
International Nuclear Information System (INIS)
Mitter, M.
2012-01-01
Non-perturbative aspects of strongly-interacting matter, in particular at non-vanishing temperatures, are investigated with functional methods. The consequences of confinement in terms of a linearly rising static quark potential arising from an infrared singular quark 4-point function are studied. Such a singularity is only consistent for a specific color structure and implies the existence of similar singularities in special color structures of n-point functions with n>3. A simple explanation for Casimir scaling is found within this mechanism of confinement.The deconfinement transition of fundamentally charged scalar and quark matter is investigated in terms of center symmetry. Novel dual order parameters are introduced that can be obtained from the corresponding matter propagators. In the case of quark matter the new order parameter compares well with the dual chiral condensate, with the advantage that no regularization is necessary even at non-vanishing quark masses.The influence of the axial anomaly on the chiral transition is studied in terms of a 't Hooft determinant with quarks and mesons as effective degrees of freedom in the functional renormalization group. In the case of two quark flavors, the calculated temperature dependent determinant results in a decrease of the anomalous eta'-mass close to the chiral transition temperature. This is connected to a partial Z(2) restoration at the chiral transition instead of the restoration of full axial U(1). With 2+1 quark flavors and a temperature independent 't Hooft term, the chiral transition is found to be of second order with three dimensional O(4) critical exponents in the limit of vanishing up and down quark mass, whereas a first-order transition is seen without U(1) violation. (author) [de
Takashi, Tonegawa; Makoto, Kaburagi; Takeshi, Nakao; Department of Physics, Faculty of Science, Kobe University; Faculty of Cross-Cultural Studies, Kobe University; Department of Physics, Faculty of Science, Kobe University
1995-01-01
The Haldane to dimer phase transition is studied in the spin-1 Haldane system with bond-alternating nearest-neighbor and uniform next-nearest-neighbor exchange interactions, where both interactions are antiferromagnetic and thus compete with each other. By using a method of exact diagonalization, the ground-state phase diagram on the ratio of the next-nearest-neighbor interaction constant to the nearest-neighbor one versus the bond-alternation parameter of the nearest-neighbor interactions is...
Directory of Open Access Journals (Sweden)
Carl eDiehl
2016-02-01
Full Text Available Streptococcus pyogenes is one of the most significant bacterial pathogens in the human population mostly causing superficial and uncomplicated infections (pharyngitis and impetigo but also invasive and life-threatening disease. We have previously identified a virulence determinant, protein sHIP, which is secreted at higher levels by an invasive compared to a non-invasive strain of S. pyogenes. The present work presents a further characterization of the structural and functional properties of this bacterial protein. Biophysical and structural studies have shown that protein sHIP forms stable tetramers both in the crystal and in solution. The tetramers are composed of four helix-loop-helix motifs with the loop regions connecting the helices displaying a high degree of flexibility. Owing to interactions at the tetramer interface, the observed tetramer can be described as a dimer of dimers. We identified three residues at the tetramer interface (Leu84, Leu88, Tyr95, which due to largely non-polar side-chains, could be important determinants for protein oligomerization. Based on these observations, we produced a sHIP variant in which these residues were mutated to alanines. Biophysical experiments clearly indicated that the sHIP mutant appear only as dimers in solution confirming the importance of the interfacial residues for protein oligomerisation. Furthermore, we could show that the sHIP mutant interacts with intact histidine-rich glycoprotein (HRG and the histidine-rich repeats in HRG, and inhibits their antibacterial activity to the same or even higher extent as compared to the wild type protein sHIP. We determined the crystal structure of the sHIP mutant, which, as a result of the high quality of the data, allowed us to improve the existing structural model of the protein. Finally, by employing NMR spectroscopy in solution, we generated a model for the complex between the sHIP mutant and an HRG-derived heparin-binding peptide, providing further
Guyett, Paul J; Gloss, Lisa M
2012-01-20
The H2A-H2B histone heterodimer folds via monomeric and dimeric kinetic intermediates. Within ∼5 ms, the H2A and H2B polypeptides associate in a nearly diffusion limited reaction to form a dimeric ensemble, denoted I₂ and I₂*, the latter being a subpopulation characterized by a higher content of nonnative structure (NNS). The I₂ ensemble folds to the native heterodimer, N₂, through an observable, first-order kinetic phase. To determine the regions of structure in the I₂ ensemble, we characterized 26 Ala mutants of buried hydrophobic residues, spanning the three helices of the canonical histone folds of H2A and H2B and the H2B C-terminal helix. All but one targeted residue contributed significantly to the stability of I₂, the transition state and N₂; however, only residues in the hydrophobic core of the dimer interface perturbed the I₂* population. Destabilization of I₂* correlated with slower folding rates, implying that NNS is not a kinetic trap but rather accelerates folding. The pattern of Φ values indicated that residues forming intramolecular interactions in the peripheral helices contributed similar stability to I₂ and N₂, but residues involved in intermolecular interactions in the hydrophobic core are only partially folded in I₂. These findings suggest a dimerize-then-rearrange model. Residues throughout the histone fold contribute to the stability of I₂, but after the rapid dimerization reaction, the hydrophobic core of the dimer interface has few fully native interactions. In the transition state leading to N₂, more native-like interactions are developed and nonnative interactions are rearranged. Copyright © 2011 Elsevier Ltd. All rights reserved.
The colours of strong interaction; L`interaction forte sous toutes ses couleurs
Energy Technology Data Exchange (ETDEWEB)
NONE
1996-12-31
The aim of this session is to draw a consistent framework about the different ways to consider strong interaction. A large part is dedicated to theoretical work and the latest experimental results obtained at the first electron collider HERA are discussed. (A.C.)
The colours of strong interaction; L`interaction forte sous toutes ses couleurs
Energy Technology Data Exchange (ETDEWEB)
NONE
1995-12-31
The aim of this session is to draw a consistent framework about the different ways to consider strong interaction. A large part is dedicated to theoretical work and the latest experimental results obtained at the first electron collider HERA are discussed. (A.C.)
DEFF Research Database (Denmark)
Diehl, Carl; Wisniewska, Magdalena; Frick, Inga-Maria
2016-01-01
HIP, which is secreted at higher levels by an invasive compared to a non-invasive strain of S. pyogenes. The present work presents a further characterization of the structural and functional properties of this bacterial protein. Biophysical and structural studies have shown that protein sHIP forms stable...... clearly indicated that the sHIP mutant appear only as dimers in solution confirming the importance of the interfacial residues for protein oligomerisation. Furthermore, we could show that the sHIP mutant interacts with intact histidine-rich glycoprotein (HRG) and the histidine-rich repeats in HRG......, and inhibits their antibacterial activity to the same or even higher extent as compared to the wild type protein sHIP. We determined the crystal structure of the sHIP mutant, which, as a result of the high quality of the data, allowed us to improve the existing structural model of the protein. Finally...
Properties of hot and dense strongly interacting matter
Energy Technology Data Exchange (ETDEWEB)
Almasi, Gabor Andras
2017-06-19
In this thesis we consider effective models of quantum chromodynamics to learn about the chiral- and deconfinement phase transitions. In Chapter 1 we review basic properties of strongly interacting matter and the foundations of finite temperature field theory. We review furthermore the nonperturbative functional renormalization group (FRG) approach. In Chapter 2 we introduce the quark-meson (QM) model and its extensions including the Polyakov-loop variables and repulsive vector interactions between quarks. We then discuss features of the model both in the mean-field approximation and in the renormalization group treatment. A novel method to solve the renormalization group equations based on the Chebyshev polynomials is presented at the end of the chapter. In Chapter 3 the scaling behavior of the order parameter at the chiral phase transition is studied within effective models. We explore universal and nonuniversal structures near the critical point. These include the scaling functions, the leading corrections to scaling and the corresponding size of the scaling window as well as their dependence on an external symmetry breaking field. We consider two models in the mean-field approximation, the QM and the Polyakov-loop-extended quark-meson (PQM) models, and compare their critical properties with a purely bosonic theory, the O(N) linear sigma model in the N → ∞ limit. In these models the order parameter scaling function is found analytically using the high temperature expansion of the thermodynamic potential. The effects of a gluonic background on the nonuniversal scaling parameters are studied within the PQM model. Furthermore, numerical calculations of the scaling function and the scaling window are performed in the QM model using the FRG. Chapter 4 contains a study of the critical properties of net-baryon-number fluctuations at the chiral restoration transition in a medium at finite temperature and net baryon density. The chiral dynamics of quantum
Two Methods For Simulating the Strong-Strong Beam-Beam Interaction in Hadron Colliders
International Nuclear Information System (INIS)
Warnock, Robert L.
2002-01-01
We present and compare the method of weighted macro particle tracking and the Perron-Frobenius operator technique for simulating the time evolution of two beams coupled via the collective beam-beam interaction in 2-D and 4-D (transverse) phase space. The coherent dipole modes, with and without lattice nonlinearities and external excitation, are studied by means of the Vlasov-Poisson system
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.
Intensities and strong interaction attenuation of kaonic x-rays
Backenstoss, Gerhard; Koch, H; Povel, H P; Schwitter, A; Tauscher, Ludwig
1974-01-01
Relative intensities of numerous kaonic X-ray transitions have been measured for the elements C, P, S, and Cl, from which level widths due to the strong K-nucleus absorption have been determined. From these and earlier published data, optical potential parameters have been derived and possible consequences on the nuclear matter distribution are discussed. (10 refs).
Interaction of neutral particles with strong laser fields
Energy Technology Data Exchange (ETDEWEB)
Meuren, Sebastian; Keitel, Christoph H.; Di Piazza, Antonino [Max-Planck-Institut fuer Kernphysik, Saupfercheckweg 1, D-69117 Heidelberg (Germany)
2013-07-01
Since the invention of the laser in the 1960s the experimentally available field strengths have continuously increased. The current peak intensity record is 2 x 10{sup 22} W/cm{sup 2} and next generation facilities such as ELI, HiPER and XCELS plan to reach even intensities of the order of 10{sup 24} W/cm{sup 2}. Thus, modern laser facilities are a clean source for very strong external electromagnetic fields and promise new and interesting high-energy physics experiments. In particular, strong laser fields could be used to test non-linear effects in quantum field theory. Earlier we have investigated how radiative corrections modify the coupling of a charged particle inside a strong plane-wave electromagnetic background field. However, a charged particle couples already at tree level to electromagnetic radiation. Therefore, we have now analyzed how the coupling between neutral particles and radiation is affected by a very strong plane-wave electromagnetic background field, when loop corrections are taken into account. In particular, the case of neutrinos is discussed.
Low energy p anti p strong interactions: theoretical perspective
International Nuclear Information System (INIS)
Dover, C.B.
1985-01-01
Several of the frontier problems in low energy nucleon-antinucleon phenomenology are addressed. Spin observables and dynamical selection rules in N anti N annihilation are used as examples of phenomena which offer particularly strong constraints on theoretical models, formulated either in terms of meson and baryon exchange or as effective operators in a non-perturbative quark-gluon picture. 24 refs
On the strong influence of molecular interactions over large distances
Pfennig, Andreas
2018-03-01
Molecular-dynamics simulations of liquid water show deterministic chaos, i.e. an intentionally introduced molecular position shift of an individual molecule increases exponentially by a factor of 10 in 0.23 ps. This is a Lyaponov instability. As soon as it reaches molecular scale, the direction of the resulting shift in molecular motions is unpredictable. The influence of any individual distant particle on an observed molecule will be minute, but the effect will quickly increase to molecular scale and beyond due to this exponential growth. Consequently, any individual particle in the universe will affect the behavior of any molecule within at most 33 ps after the interaction reaches it. A larger distance of the faraway particle does not decrease the influence on an observed molecule, but the effect reaches molecular scale only some ps later. Thus in evaluating the interactions, nearby and faraway molecules have to be equally accounted for. The consequences of this quickly reacting network of interactions on universal scale are fundamental. Even in a strictly deterministic view, molecular behavior is principally unpredictable, and thus has to be regarded random. Corresponding statements apply for any particles interacting. This result leads to a fundamental rethinking of the structure of interactions of molecules and particles as well as the behavior of reality.
Strong-coupling interaction in high-Tc superconductors
International Nuclear Information System (INIS)
Ray, D.K.
1991-01-01
Extensive experimental and theoretical work have been done to understand the mechanisms of superconductivity. Until 1986 when Bednorz and Muller discovered superconductivity in the copper oxide perovskite, the principal mechanism was found to be electron-phonon interaction and the characteristics of superconductivity vary depending on the strength of the electron-phonon interaction and the electronic structure. The essential characteristic of these conventional superconductors could be divided into two groups: wide band metals with low density of states N(E F ) at the Fermi energy E F and a rather weak electron-phonon coupling V obeying the universal characteristics of the BCS theory and narrow d band metals, compounds, and alloys with high values of N(E F ), electron-phonon coupling V and non negligible Coulomb interaction between the electrons. In this paper a short summary and the important results of these theories are discussed. The inherent limitations of these theories based on electron-phonon interaction will be discussed. The authors indicate the major characteristics of the new superconductors. These characteristics are difficult to explain on the basis of either the conventional electron-phonon theory or theories based on magnetic interactions alone
DEFF Research Database (Denmark)
Andersen, Tonni Grube; Nintemann, Sebastian; Marek, Magdalena
2016-01-01
When investigating interactions between two proteins with complementary reporter tags in yeast two-hybrid or split GFP assays, it remains troublesome to discriminate true-from false-negative results and challenging to compare the level of interaction across experiments. This leads to decreased se...
Magnetic dynamics of weakly and strongly interacting hematite nanoparticles
DEFF Research Database (Denmark)
Hansen, Mikkel Fougt; Bender Koch, Christian; Mørup, Steen
2000-01-01
The magnetic dynamics of two differently treated samples of hematite nanoparticles from the same batch with a particle size of about 20 nm have been studied by Mossbauer spectroscopy. The dynamics of the first sample, in which the particles are coated and dispersed in water, is in accordance with...... down by interparticle interactions and a magnetically split spectrum is retained at room temperature. The temperature variation or the magnetic hyperfine field, corresponding to different quantiles in the hyperfine field distribution, can be consistently described by a mean field model...... for "superferromagnetism" in which the magnetic anisotropy is included. The coupling between the particles is due to exchange interactions and the interaction strength can be accounted for by just a few exchange bridges between surface atoms in neighboring crystallites....
Magnetic interactions in strongly correlated systems: Spin and orbital contributions
Energy Technology Data Exchange (ETDEWEB)
Secchi, A., E-mail: a.secchi@science.ru.nl [Radboud University, Institute for Molecules and Materials, 6525 AJ Nijmegen (Netherlands); Lichtenstein, A.I. [Universitat Hamburg, Institut für Theoretische Physik, Jungiusstraße 9, D-20355 Hamburg (Germany); Katsnelson, M.I. [Radboud University, Institute for Molecules and Materials, 6525 AJ Nijmegen (Netherlands)
2015-09-15
We present a technique to map an electronic model with local interactions (a generalized multi-orbital Hubbard model) onto an effective model of interacting classical spins, by requiring that the thermodynamic potentials associated to spin rotations in the two systems are equivalent up to second order in the rotation angles, when the electronic system is in a symmetry-broken phase. This allows to determine the parameters of relativistic and non-relativistic magnetic interactions in the effective spin model in terms of equilibrium Green’s functions of the electronic model. The Hamiltonian of the electronic system includes, in addition to the non-relativistic part, relativistic single-particle terms such as the Zeeman coupling to an external magnetic field, spin–orbit coupling, and arbitrary magnetic anisotropies; the orbital degrees of freedom of the electrons are explicitly taken into account. We determine the complete relativistic exchange tensors, accounting for anisotropic exchange, Dzyaloshinskii–Moriya interactions, as well as additional non-diagonal symmetric terms (which may include dipole–dipole interaction). The expressions of all these magnetic interactions are determined in a unified framework, including previously disregarded features such as the vertices of two-particle Green’s functions and non-local self-energies. We do not assume any smallness in spin–orbit coupling, so our treatment is in this sense exact. Finally, we show how to distinguish and address separately the spin, orbital and spin–orbital contributions to magnetism, providing expressions that can be computed within a tight-binding Dynamical Mean Field Theory.
Energy Technology Data Exchange (ETDEWEB)
Solimannejad, Mohammad, E-mail: m-solimannejad@araku.ac.ir [Quantum Chemistry Group, Department of Chemistry, Arak University, 38156-879 Arak (Iran, Islamic Republic of); Massahi, Shokofeh [Quantum Chemistry Group, Department of Chemistry, Arak University, 38156-879 Arak (Iran, Islamic Republic of); Alkorta, Ibon, E-mail: ibon@iqm.csic.es [Instituto de Quimica Medica (CSIC), Juan de la Cierva, 3, 28006 Madrid (Spain)
2009-07-30
Ab initio calculations at MP2/aug-cc-pVTZ level were used to analyze the interactions between nitrosyl hydride (HNO) dimers and trimers. The structures obtained have been analyzed with the Atoms in Molecules (AIMs) and Natural Bond Orbital (NBO) methodologies. Four minima were located on the potential energy surface of the dimers. Nine different structures have been obtained for the trimers. Three types of interactions are observed, NH{center_dot}{center_dot}{center_dot}N and NH{center_dot}{center_dot}{center_dot}O hydrogen bonds and orthogonal interaction between the lone pair of the oxygen with the electron-deficient region of the nitrogen atom. Stabilization energies of dimers and trimers including BSSE and ZPE are in the range 4-8 kJ mol{sup -1} and 12-19 kJ mol{sup -1}, respectively. Blue shift of NH bond upon complex formation in the ranges between 30-80 and 14,114 cm{sup -1} is predicted for dimers and trimers, respectively.
Strongly-Interacting Fermi Gases in Reduced Dimensions
2015-11-16
12 2012): 0. doi: 10.1103/PhysRevA.86.063625 Allan Adams , Lincoln D Carr, Thomas Schäfer, Peter Steinberg, John E Thomas. Strongly correlated quantum...Physics (NCSU, 2013) Received Book Chapter TOTAL: PERCENT_SUPPORTEDNAME FTE Equivalent: Total Number: Discipline Willie Ong 1.00 Chingyun Cheng 0.50...PERCENT_SUPPORTEDNAME FTE Equivalent: Total Number: NAME Total Number: NAME Total Number: Willie Ong 1 PERCENT_SUPPORTEDNAME FTE Equivalent: Total
Coulomb plus strong interaction bound states - momentum space numerical solutions
International Nuclear Information System (INIS)
Heddle, D.P.; Tabakin, F.
1985-01-01
The levels and widths of hadronic atoms are calculated in momentum space using an inverse algorithm for the eigenvalue problem. The Coulomb singularity is handled by the Lande substraction method. Relativistic, nonlocal, complex hadron-nucleus interactions are incorporated as well as vacuum polarization and finite size effects. Coordinate space wavefunctions are obtained by employing a Fourier Bessel transformation. (orig.)
Strong light-matter interaction in graphene - Invited talk
DEFF Research Database (Denmark)
Xiao, Sanshui
Graphene has attracted lots of attention due to its remarkable electronic and optical properties, thus providing great promise in photonics and optoelectronics. However, the performance of these devices is generally limited by the weak light-matter interaction in graphene. The combination...
Strongly anisotropic RKKY interaction in monolayer black phosphorus
Zare, Moslem; Parhizgar, Fariborz; Asgari, Reza
2018-06-01
We theoretically study the Ruderman-Kittel-Kasuya-Yosida (RKKY) interaction in two-dimensional black phosphorus, phosphorene. The RKKY interaction enhances significantly for the low levels of hole doping owing to the nearly valence flat band. Remarkably, for the hole-doped phosphorene, the highest RKKY interaction occurs when two impurities located along the zigzag direction and it tends to a minimum value with changing the direction from the zigzag to the armchair direction. We show that the interaction is highly anisotropic and the magnetic ground-state of two magnetic adatoms can be tuned by changing the rotational configuration of impurities. Owing to the anisotropic band dispersion, the oscillatory behavior with respect to the angle of the rotation and the distance of two magnetic impurities, R is well-described by sin (2kF R) , where the Fermi wavelength kF changes in different directions. We also find that the tail of the RKKY oscillations falls off as 1 /R2 at large distances.
Grishina, E. S.; Makarova, A. S.; Kudrik, E. V.; Makarov, S. V.; Koifman, O. I.
2016-03-01
The iron phthalocyaninate μ-nitrido dimer radical cation, as well as the μ-nitrido dimer complexes of iron phthalocyaninate, was found to have high catalytic activity in the oxidation of organic compounds. It was concluded that this compound is of interest as a model of active intermediates—catalase and oxidase enzymes.
Interaction of a strong vortex with decaying turbulence
International Nuclear Information System (INIS)
Terry, P.W.
1988-01-01
The evolution of a localized, axially symmetric vortex under the action of shear stresses associated with decaying two-dimensional turbulent vorticity which is inhomogeneous in the presence of the vortex is studied analytically. For a vortex which is sufficiently strong relative to the coefficient of turbulent eddy viscosity, it is shown that turbulent fluctuations in the vortex interior and diffusion of coherent vorticity by the turbulence localize to the vortex periphery. It is also found that the coefficient of diffusion is small compared to the coefficient of eddy viscosity. 8 refs
The hard-sphere model of strongly interacting fermion systems
Mecca, Angela
2016-01-01
The formalism based on Correlated Basis Functions (CBF) and the cluster-expansion technique has been recently employed to derive an effective interaction from a realistic nuclear Hamiltonian. One of the main objectives of the work described in this Thesis is establishing the accuracy of this novel approach--that allows to combine the flexibility of perturbation theory in the basis of eigenstates of the noninteracting system with a realistic description of short-range correlations in coordinat...
Bose-Einstein-condensed gases with arbitrary strong interactions
International Nuclear Information System (INIS)
Yukalov, V. I.; Yukalova, E. P.
2006-01-01
Bose-condensed gases are considered with an effective interaction strength varying in the whole range of the values between zero and infinity. The consideration is based on the usage of a representative statistical ensemble for Bose systems with broken global gauge symmetry. Practical calculations are illustrated for a uniform Bose gas at zero temperature, employing a self-consistent mean-field theory, which is both conserving and gapless
Colliding winds: Interaction regions with strong heat conduction
International Nuclear Information System (INIS)
Imamura, J.N.; Chevalier, R.A.
1984-01-01
The interaction of fast stellar wind with a slower wind from previous mass loss gives rise to a region of hot, shocked gas. We obtain self-similar solutions for the interaction region under the assumptions of constant mass loss rate and wind velocity for the two winds, conversion of energy in the shock region, and either isothermal electrons and adiabatic ions or isothermal electrons ad ions in the shocked region. The isothermal assumption is intended to show the effects of strog heat conduction. The solutions have no heat conduction through the shock waves and assume that the electron and ion temperatures are equilibriated in the shock waves. The one-temperature isothermal solutions have nearly constant density through the shocked region, while the two-temperature solutions are intermediate between the one-temperature adiabatic and isothermal solutions. In the two-temperature solutions, the ion temperature goes to zero at the point where the gas comoves with the shocked region and the density peaks at this point. The solution may qualitatively describe the effects of heat conduction on interaction regions in the solar wind. It will be important to determine whether the assumption of no thermal waves outside the shocked region applies to shock waves in the solar wind
Strongly-interacting mirror fermions at the LHC
Directory of Open Access Journals (Sweden)
Triantaphyllou George
2017-01-01
Full Text Available The introduction of mirror fermions corresponding to an interchange of leftwith right-handed fermion quantum numbers of the Standard Model can lead to a model according to which the BEH mechanism is just an effective manifestation of a more fundamental theory while the recently-discovered Higgs-like particle is composite. This is achieved by a non-abelian gauge symmetry encompassing three mirror-fermion families strongly coupled at energies near 1 TeV. The corresponding non-perturbative dynamics lead to dynamical mirror-fermion masses between 0.14 - 1.2 TeV. Furthermore, one expects the formation of composite states, i.e. “mirror mesons”, with masses between 0.1 and 3 TeV. The number and properties of the resulting new degrees of freedom lead to a rich and interesting phenomenology, part of which is analyzed in the present work.
Interaction of Energetic Particles with Discontinuities Upstream of Strong Shocks
Malkov, Mikhail; Diamond, Patrick
2008-11-01
Acceleration of particles in strong astrophysical shocks is known to be accompanied and promoted by a number of instabilities which are driven by the particles themselves. One of them is an acoustic (also known as Drury's) instability driven by the pressure gradient of accelerated particles upstream. The generated sound waves naturally steepen into shocks thus forming a shocktrain. Similar magnetoacoustic or Alfven type structures may be driven by pick-up ions, for example. We consider the solutions of kinetic equation for accelerated particles within the shocktrain. The accelerated particles are assumed to be coupled to the flow by an intensive pitch-angle scattering on the self-generated Alfven waves. The implications for acceleration and confinement of cosmic rays in this shock environment will be discussed.
Spin effects in strong-field laser-electron interactions
International Nuclear Information System (INIS)
Ahrens, S; Bauke, H; Müller, T-O; Villalba-Chávez, S; Müller, C
2013-01-01
The electron spin degree of freedom can play a significant role in relativistic scattering processes involving intense laser fields. In this contribution we discuss the influence of the electron spin on (i) Kapitza-Dirac scattering in an x-ray laser field of high intensity, (ii) photo-induced electron-positron pair production in a strong laser wave and (iii) multiphoton electron-positron pair production on an atomic nucleus. We show that in all cases under consideration the electron spin can have a characteristic impact on the process properties and their total probabilities. To this end, spin-resolved calculations based on the Dirac equation in the presence of an intense laser field are performed. The predictions from Dirac theory are also compared with the corresponding results from the Klein-Gordon equation.
Strong delayed interactive effects of metal exposure and warming
DEFF Research Database (Denmark)
Debecker, Sara; Dinh, Khuong Van; Stoks, Robby
2017-01-01
’ ranges could lead to an important underestimation of the risks. We addressed all three mechanisms by studying effects of larval exposure to zinc and warming before, during, and after metamorphosis in Ischnura elegans damselflies from high- and lowlatitude populations. By integrating these mechanisms...... into a single study, we could identify two novel patterns. First, during exposure zinc did not affect survival, whereas it induced mild to moderate postexposure mortality in the larval stage and at metamorphosis, and very strongly reduced adult lifespan. This severe delayed effect across metamorphosis...... was especially remarkable in high-latitude animals, as they appeared almost insensitive to zinc during the larval stage. Second, the well-known synergism between metals and warming was manifested not only during the larval stage but also after metamorphosis, yet notably only in low-latitude damselflies...
A non-linear theory of strong interactions
International Nuclear Information System (INIS)
Skyrme, T.H.R.
1994-01-01
A non-linear theory of mesons, nucleons and hyperons is proposed. The three independent fields of the usual symmetrical pseudo-scalar pion field are replaced by the three directions of a four-component field vector of constant length, conceived in an Euclidean four-dimensional isotopic spin space. This length provides the universal scaling factor, all other constants being dimensionless; the mass of the meson field is generated by a φ 4 term; this destroys the continuous rotation group in the iso-space, leaving a 'cubic' symmetry group. Classification of states by this group introduces quantum numbers corresponding to isotopic spin and to 'strangeness'; one consequences is that, at least in elementary interactions, charge is only conserved module 4. Furthermore, particle states have not a well-defined parity, but parity is effectively conserved for meson-nucleon interactions. A simplified model, using only two dimensions of space and iso-space, is considered further; the non-linear meson field has solutions with particle character, and an indication is given of the way in which the particle field variables might be introduced as collective co-ordinates describing the dynamics of these particular solutions of the meson field equations, suggesting a unified theory based on the meson field alone. (author). 7 refs
Strong Constraints on Aerosol-Cloud Interactions from Volcanic Eruptions
Malavelle, Florent F.; Haywood, Jim M.; Jones, Andy; Gettelman, Andrew; Clarisse, Lieven; Bauduin, Sophie; Allan, Richard P.; Karset, Inger Helene H.; Kristjansson, Jon Egill; Oreopoulos, Lazaros;
2017-01-01
Aerosols have a potentially large effect on climate, particularly through their interactions with clouds, but the magnitude of this effect is highly uncertain. Large volcanic eruptions produce sulfur dioxide, which in turn produces aerosols; these eruptions thus represent a natural experiment through which to quantify aerosol-cloud interactions. Here we show that the massive 2014-2015 fissure eruption in Holuhraun, Iceland, reduced the size of liquid cloud droplets - consistent with expectations - but had no discernible effect on other cloud properties. The reduction in droplet size led to cloud brightening and global-mean radiative forcing of around minus 0.2 watts per square metre for September to October 2014. Changes in cloud amount or cloud liquid water path, however, were undetectable, indicating that these indirect effects, and cloud systems in general, are well buffered against aerosol changes. This result will reduce uncertainties in future climate projections, because we are now able to reject results from climate models with an excessive liquid-water-path response.
Light and neutron scattering study of strongly interacting ionic micelles
International Nuclear Information System (INIS)
Degiorgio, V.; Corti, M.; Piazza, R.
1989-01-01
Dilute solutions of ionic micelles formed by biological glycolipids (gangliosides) have been investigated at various ionic strengths by static and dynamic light scaterring and by small-angle neutron scattering. The size and shape of the micelle is not appreciably affected by the added salt concentration in the range 0-100 mM NaCL. From the measured intensity of scattered light we derive the electric charge Z of the micelle by fitting the data to a theoretical calculation which uses a screened Coulomb potential for the intermicellar interaction, and the hypernetted chain approximation for the calculation of the radial distribution function. The correlation function derived from dynamic light scattering shows the long time contribution typical of concentrated polydisperse systems (author). 15 refs.; 6 figs
Natural cold baryogenesis from strongly interacting electroweak symmetry breaking
Energy Technology Data Exchange (ETDEWEB)
Konstandin, Thomas; Servant, Géraldine, E-mail: tkonstan@cern.ch, E-mail: geraldine.servant@cern.ch [CERN Physics Department, Theory Division, CH-1211 Geneva 23 (Switzerland)
2011-07-01
The mechanism of ''cold electroweak baryogenesis'' has been so far unpopular because its proposal has relied on the ad-hoc assumption of a period of hybrid inflation at the electroweak scale with the Higgs acting as the waterfall field. We argue here that cold baryogenesis can be naturally realized without the need to introduce any slow-roll potential. Our point is that composite Higgs models where electroweak symmetry breaking arises via a strongly first-order phase transition provide a well-motivated framework for cold baryogenesis. In this case, reheating proceeds by bubble collisions and we argue that this can induce changes in Chern-Simons number, which in the presence of new sources of CP violation commonly lead to baryogenesis. We illustrate this mechanism using as a source of CP violation an effective dimension-six operator which is free from EDM constraints, another advantage of cold baryogenesis compared to the standard theory of electroweak baryogenesis. Our results are general as they do not rely on any particular UV completion but only on a stage of supercooling ended by a first-order phase transition in the evolution of the universe, which can be natural if there is nearly conformal dynamics at the TeV scale. Besides, baryon-number violation originates from the Standard Model only.
Natural Cold Baryogenesis from Strongly Interacting Electroweak Symmetry Breaking
Konstandin, Thomas
2011-01-01
The mechanism of "cold electroweak baryogenesis" has been so far unpopular because its proposal has relied on the ad-hoc assumption of a period of hybrid inflation at the electroweak scale with the Higgs acting as the waterfall field. We argue here that cold baryogenesis can be naturally realized without the need to introduce any slow-roll potential. Our point is that composite Higgs models where electroweak symmetry breaking arises via a strongly first-order phase transition provide a well-motivated framework for cold baryogenesis. In this case, reheating proceeds by bubble collisions and we argue that this can induce changes in Chern-Simons number, which in the presence of new sources of CP violation commonly lead to baryogenesis. We illustrate this mechanism using as a source of CP violation an effective dimension-six operator which is free from EDM constraints, another advantage of cold baryogenesis compared to the standard theory of electroweak baryogenesis. Our results are general as they do not rely on...
Natural cold baryogenesis from strongly interacting electroweak symmetry breaking
International Nuclear Information System (INIS)
Konstandin, Thomas; Servant, Géraldine
2011-01-01
The mechanism of ''cold electroweak baryogenesis'' has been so far unpopular because its proposal has relied on the ad-hoc assumption of a period of hybrid inflation at the electroweak scale with the Higgs acting as the waterfall field. We argue here that cold baryogenesis can be naturally realized without the need to introduce any slow-roll potential. Our point is that composite Higgs models where electroweak symmetry breaking arises via a strongly first-order phase transition provide a well-motivated framework for cold baryogenesis. In this case, reheating proceeds by bubble collisions and we argue that this can induce changes in Chern-Simons number, which in the presence of new sources of CP violation commonly lead to baryogenesis. We illustrate this mechanism using as a source of CP violation an effective dimension-six operator which is free from EDM constraints, another advantage of cold baryogenesis compared to the standard theory of electroweak baryogenesis. Our results are general as they do not rely on any particular UV completion but only on a stage of supercooling ended by a first-order phase transition in the evolution of the universe, which can be natural if there is nearly conformal dynamics at the TeV scale. Besides, baryon-number violation originates from the Standard Model only
Strongly coupled semiclassical plasma: interaction model and some properties
International Nuclear Information System (INIS)
Baimbetov, N.F.; Bekenov, N.A.
1999-01-01
In the report a fully ionized strongly coupled hydrogen plasma is considered. The density number is considered within range n=n e =n i ≅(10 21 -2·10 25 )sm -3 , and the temperature domian is T≅(5·10 4 -10 6 ) K. The coupling parameter Γ is defined by Γ=e 2 /αk B T, where k B is the Boltzmann constant and e is electrical charge, α=(3/4πn) 1/3 is the average distance between the particles (Wigner-Seitz radius). The dimensionless density parameter r s =α/α B is given in terms of the Bohr radius α B =ℎ 2 /me 2 ∼0.529·10 - 8 sm. The degeneracy parameter for the electron was defined by the ratio between the thermal energy k B T and the Fermi energy E F :Θ=k B T/E F ∼0.54·r s /Γ. The intermediate temperature-density region, where Γ≥1; Θ≅1; T>13.6 eV is examined. A semiclassical effective potential which account for the short-range, quantum diffraction and symmetry effects of charge carriers screening
Gray solitons in a strongly interacting superfluid Fermi gas
International Nuclear Information System (INIS)
Spuntarelli, Andrea; Pieri, Pierbiagio; Strinati, Giancarlo C; Carr, Lincoln D
2011-01-01
The Bardeen-Cooper-Schrieffer (BCS) to Bose-Einstein condensate (BEC) crossover problem is solved for stationary gray solitons via the Boguliubov-de Gennes equations at zero temperature. These crossover solitons exhibit a localized notch in the gap and a characteristic phase difference across the notch for all interaction strengths, from BEC to BCS regimes. However, they do not follow the well-known Josephson-like sinusoidal relationship between velocity and phase difference except in the far BEC limit: at unitarity, the velocity has a nearly linear dependence on phase difference over an extended range. For a fixed phase difference, the soliton is of nearly constant depth from the BEC limit to unitarity and then grows progressively shallower into the BCS limit, and on the BCS side, Friedel oscillations are apparent in both gap amplitude and phase. The crossover soliton appears fundamentally in the gap; we show, however, that the density closely follows the gap, and the soliton is therefore observable. We develop an approximate power-law relationship to express this fact: the density of gray crossover solitons varies as the square of the gap amplitude in the BEC limit and as a power of about 1.5 at unitarity.
Exact tensor network ansatz for strongly interacting systems
Zaletel, Michael P.
It appears that the tensor network ansatz, while not quite complete, is an efficient coordinate system for the tiny subset of a many-body Hilbert space which can be realized as a low energy state of a local Hamiltonian. However, we don't fully understand precisely which phases are captured by the tensor network ansatz, how to compute their physical observables (even numerically), or how to compute a tensor network representation for a ground state given a microscopic Hamiltonian. These questions are algorithmic in nature, but their resolution is intimately related to understanding the nature of quantum entanglement in many-body systems. For this reason it is useful to compute the tensor network representation of various `model' wavefunctions representative of different phases of matter; this allows us to understand how the entanglement properties of each phase are expressed in the tensor network ansatz, and can serve as test cases for algorithm development. Condensed matter physics has many illuminating model wavefunctions, such as Laughlin's celebrated wave function for the fractional quantum Hall effect, the Bardeen-Cooper-Schrieffer wave function for superconductivity, and Anderson's resonating valence bond ansatz for spin liquids. This thesis presents some results on exact tensor network representations of these model wavefunctions. In addition, a tensor network representation is given for the time evolution operator of a long-range one-dimensional Hamiltonian, which allows one to numerically simulate the time evolution of power-law interacting spin chains as well as two-dimensional strips and cylinders.
Energy Technology Data Exchange (ETDEWEB)
Hambright, P; Rishnamurthy, M K
1975-01-01
The kinetics of cyanide addition to the water-soluble oxybridged iron dimer of tetra (p-sulophenyl) porphin indicate that HCN is the reactant. The rate law is of the form: Rate = (3.8 +- 0.2) x 10/sup 4/ (Fe dimer) (HCN)/(1 + (3.1 +- 0.3) x 10/sup 10/ (H/sup +/)) at 25/sup 0/ ..mu.. = 0.7 (NaNO/sub 3/). The cyano iron dimer dissociates into dicyano iron monomers by two pathways, one first order in (H/sup +/), and one proportional to (H/sup +/)(CN/sup -/)/sup 2/. The mechanism of this dimer reaction is compared to iron porphyrin monomer systems.
Interacting active elastic dimers: Two cells moving on a rigid track
Das, Moumita; Mayett, David; Schwarz, J. M.
2015-03-01
Cell migration in morphogenesis and cancer metastasis typically involves an interplay between different cell types. The rules governing such interplay remain largely unknown, however, a recent experiment studying the interaction between neural crest (NC) cells and placodal cells reveals an example of such rules. The study found that NC cells chase the placodal cells by chemotaxis, while placodal cells run away from NC cells when contacted by them. Motivated by this observation, we construct and study a minimal one-dimensional cell-cell model comprised of two cells with each cell represented by two-beads-connected-by-an-active spring. The active spring for each moving cell models the stress fibers with their myosin-driven contractility (and alpha-actinin extendability), while the friction coefficients of the beads describe the catch/slip bond behavior of the integrins in focal adhesions. We also include a dynamic contact interaction between the two cells, as well as a chemotactic potential, to decipher the chase-and-run dynamics observed in the experiment. We then use our modeling to further generalize the rules governing the interplay between different cell types during collective cell migration.
Interactions between tetrathiafulvalene units in dimeric structures – the influence of cyclic cores
Directory of Open Access Journals (Sweden)
Huixin Jiang
2015-06-01
Full Text Available A selection of cyclic and acyclic acetylenic scaffolds bearing two tetrathiafulvalene (TTF units was prepared by different metal-catalyzed coupling reactions. The bridge separating the two TTF units was systematically changed from linearly conjugated ethyne, butadiyne and tetraethynylethene (trans-substituted units to a cross-conjugated tetraethynylethene unit, placed in either acyclic or cyclic arrangements. The cyclic structures correspond to so-called radiaannulenes having both endo- and exocyclic double bonds. Interactions between two redox-active TTF units in these molecules were investigated by cyclic voltammetry, UV–vis–NIR and EPR absorption spectroscopical methods of the electrochemically generated oxidized species. The electron-accepting properties of the acetylenic cores were also investigated electrochemically.
DEFF Research Database (Denmark)
Hanni, Matti; Lantto, Perttu; Ilias, Miroslav
2007-01-01
Relativistic effects on the 129Xe nuclear magnetic resonance shielding and 131Xe nuclear quadrupole coupling (NQC) tensors are examined in the weakly bound Xe2 system at different levels of theory including the relativistic four-component Dirac-Hartree-Fock (DHF) method. The intermolecular...... interaction-induced binary chemical shift d, the anisotropy of the shielding tensor ?s, and the NQC constant along the internuclear axis ?ll are calculated as a function of the internuclear distance. DHF shielding calculations are carried out using gauge-including atomic orbitals. For comparison, the full...... is obtained for d and ?s in Xe2. For these properties, the currently most complete theoretical description is obtained by a piecewise approximation where the uncorrelated relativistic DHF results obtained close to the basis-set limit are corrected, on the one hand, for NR correlation effects and, on the other...
Photoionization of helium dimers
International Nuclear Information System (INIS)
Havermeier, Tilo
2010-01-01
The helium dimer is one of the most weakly bound systems in the universe. This makes it an interesting quantum mechanical object for investigation. These Van der Waals Clusters can be produced in an expansion of a cryogenic gas jet through a small nozzle into vacuum. In the present experiment we examine the interaction of He dimers with synchrotron radiation at an energy range from 64 to 78 eV. We observed different pathways leading to single ionization of both He atoms of the dimer compound. This two close standing ions begin now to dissociate in cause of their coulomb potential. All charged fragments were detected in coincidence with a COLTRIMS system. Especially Interatomic Coulombic Decay (ICD) and the two step process (TS1) were clearly identified. Furthermore a distribution of the internuclear distance was obtained from the measured Kinetic Energy Release (KER). (orig.)
Hanni, Matti; Lantto, Perttu; Ilias, Miroslav; Jensen, Hans Jorgen Aagaard; Vaara, Juha
2007-10-28
Relativistic effects on the (129)Xe nuclear magnetic resonance shielding and (131)Xe nuclear quadrupole coupling (NQC) tensors are examined in the weakly bound Xe(2) system at different levels of theory including the relativistic four-component Dirac-Hartree-Fock (DHF) method. The intermolecular interaction-induced binary chemical shift delta, the anisotropy of the shielding tensor Deltasigma, and the NQC constant along the internuclear axis chi( parallel) are calculated as a function of the internuclear distance. DHF shielding calculations are carried out using gauge-including atomic orbitals. For comparison, the full leading-order one-electron Breit-Pauli perturbation theory (BPPT) is applied using a common gauge origin. Electron correlation effects are studied at the nonrelativistic (NR) coupled-cluster singles and doubles with perturbational triples [CCSD(T)] level of theory. The fully relativistic second-order Moller-Plesset many-body perturbation (DMP2) theory is used to examine the cross coupling between correlation and relativity on NQC. The same is investigated for delta and Deltasigma by BPPT with a density functional theory model. A semiquantitative agreement between the BPPT and DHF binary property curves is obtained for delta and Deltasigma in Xe(2). For these properties, the currently most complete theoretical description is obtained by a piecewise approximation where the uncorrelated relativistic DHF results obtained close to the basis-set limit are corrected, on the one hand, for NR correlation effects and, on the other hand, for the BPPT-based cross coupling of relativity and correlation. For chi( parallel), the fully relativistic DMP2 results obtain a correction for NR correlation effects beyond MP2. The computed temperature dependence of the second virial coefficient of the (129)Xe nuclear shielding is compared to experiment in Xe gas. Our best results, obtained with the piecewise approximation for the binary chemical shift combined with the
Hyperspherical Treatment of Strongly-Interacting Few-Fermion Systems in One Dimension
DEFF Research Database (Denmark)
Volosniev, A. G.; Fedorov, D. V.; Jensen, A. S.
2015-01-01
We examine a one-dimensional two-component fermionic system in a trap, assuming that all particles have the same mass and interact through a strong repulsive zero-range force. First we show how a simple system of three strongly interacting particles in a harmonic trap can be treated using...
Search for strongly interacting massive particles using semiconductor detectors on the ground
International Nuclear Information System (INIS)
Derbin, A.V.; Egorov, A.I.; Bakhlanov, S.V.; Muratova, V.N.
1999-01-01
Using signals from recoil nucleus in semiconductor detectors, search for strongly interacting massive particles, as a possible candidate for dark matter, is continued. Experimental installation and the experimental results are given. New limits on the possible masses and cross sections of strongly interacting massive particles are presented [ru
International Nuclear Information System (INIS)
Säkkinen, Niko; Leeuwen, Robert van; Peng, Yang; Appel, Heiko
2015-01-01
We study ground-state properties of a two-site, two-electron Holstein model describing two molecules coupled indirectly via electron-phonon interaction by using both exact diagonalization and self-consistent diagrammatic many-body perturbation theory. The Hartree and self-consistent Born approximations used in the present work are studied at different levels of self-consistency. The governing equations are shown to exhibit multiple solutions when the electron-phonon interaction is sufficiently strong, whereas at smaller interactions, only a single solution is found. The additional solutions at larger electron-phonon couplings correspond to symmetry-broken states with inhomogeneous electron densities. A comparison to exact results indicates that this symmetry breaking is strongly correlated with the formation of a bipolaron state in which the two electrons prefer to reside on the same molecule. The results further show that the Hartree and partially self-consistent Born solutions obtained by enforcing symmetry do not compare well with exact energetics, while the fully self-consistent Born approximation improves the qualitative and quantitative agreement with exact results in the same symmetric case. This together with a presented natural occupation number analysis supports the conclusion that the fully self-consistent approximation describes partially the bipolaron crossover. These results contribute to better understanding how these approximations cope with the strong localizing effect of the electron-phonon interaction
Extension of lattice cluster theory to strongly interacting, self-assembling polymeric systems.
Freed, Karl F
2009-02-14
A new extension of the lattice cluster theory is developed to describe the influence of monomer structure and local correlations on the free energy of strongly interacting and self-assembling polymer systems. This extension combines a systematic high dimension (1/d) and high temperature expansion (that is appropriate for weakly interacting systems) with a direct treatment of strong interactions. The general theory is illustrated for a binary polymer blend whose two components contain "sticky" donor and acceptor groups, respectively. The free energy is determined as an explicit function of the donor-acceptor contact probabilities that depend, in turn, on the local structure and both the strong and weak interactions.
International Nuclear Information System (INIS)
Nam, Keekwon; Kim, Bongsoo; Park, Sangwoong; Lee, Sung Jong
2011-01-01
We present a numerical study on an interacting monomer–dimer model with nearest neighbor repulsion on a square lattice, which possesses two symmetric absorbing states. The model is observed to exhibit two nearby continuous transitions: the Z 2 symmetry-breaking order–disorder transition and the absorbing transition with directed percolation criticality. We find that the symmetry-breaking transition shows a non-Ising critical behavior, and that the absorbing phase becomes critical, in the sense that the critical decay of the dimer density observed at the absorbing transition persists even within the absorbing phase. Our findings call for further studies on microscopic models and the corresponding continuum description belonging to the generalized voter university class. (letter)
Energy Technology Data Exchange (ETDEWEB)
Rho, H.; Jones, C.N.; Rose, R.B. (NCSU)
2010-12-07
The two disparate functions of DCoH1 (dimerization cofactor of HNF-1)/PCD (pterin-4a-carbinolamine dehydratase) are associated with a change in oligomeric state. DCoH dimers enhance the activity of the diabetes-associated transcription factor HNF-1{alpha} (hepatocyte nuclear factor-1{alpha}), while the PCD activity of DCoH1 homotetramers aids in aromatic amino acid metabolism. These complexes compete for the same interface of the DCoH dimer. Formation of the DCoH1/HNF-1{alpha} complex requires cofolding. The homotetramer of the DCoH1 paralogue, DCoH2, interacts with HNF-1{alpha} through simple mixing. To further investigate regulation of DCoH/HNF-1{alpha} complex formation, we measured the stability of the DCoH1 homotetramer through unfolding studies by intrinsic tryptophan fluorescence. DCoH2 unfolding is reversible. Surprisingly, the DCoH1 homotetramer is resistant to guanidine unfolding but refolds at a much lower guanidine concentration. We show that a point mutation at the DCoH1 tetramer interface, Thr 51 Ser, overcomes the dissociation barrier of the homotetramer and increases the interaction with HNF-1{alpha}. The 1.8 {angstrom} resolution crystal structure of DCoH1 T51S shows the presence of an ordered water molecule at the tetramer interface, as in DCoH2, which may destabilize the homotetramer. The equilibrium unfolding data were fit to a two-state model with no apparent intermediate. Folding intermediates were detectable by size exclusion chromatography. For wild-type DCoH1 the intermediates changed with time, suggesting a kinetic origin for the unfolding barrier of the homotetramer. We propose an unfolding pathway in which the tetramer unfolds slowly, but the dimer folds reversibly. Implications for regulation of DCoH1/HNF-1{alpha} complex formation are discussed.
Nava, Marco; Palazzesi, Ferruccio; Perego, Claudio; Parrinello, Michele
2017-02-14
Sampling complex potential energies is one of the most pressing challenges of contemporary computational science. Inspired by recent efforts that use quantum effects and discretized Feynman's path integrals to overcome large barriers we propose a replica exchange method that we expect to be effective at least for systems of up to 150 atoms roughly. In each replica two copies of the same system with halved potential strengths interact via inelastic springs. The strength of the spring is varied in the different replicas so as to bridge the gap between the infinitely strong spring, that corresponds to the Boltzmann replica, and the less tight ones. We enhance the spring length fluctuations using Metadynamics. We test the method on simple yet challenging problems.
Deducing T, C, and P invariance for strong interactions in topological particle theory
International Nuclear Information System (INIS)
Jones, C.E.
1985-01-01
It is shown here how the separate discrete invariances [time reversal (T), charge conjugation (C), and parity (P)] in strong interactions can be deduced as consequences of other S-matrix requirements in topological particle theory
Czech Academy of Sciences Publication Activity Database
Řezáč, Jan; Hobza, Pavel
2014-01-01
Roč. 10, č. 8 (2014), s. 3066-3073 ISSN 1549-9618 R&D Projects: GA ČR GBP208/12/G016 Grant - others:Operational Program Research and Development for Innovations(XE) CZ 1.05/2.1.00/03/0058 Institutional support: RVO:61388963 Keywords : correlated molecular calculations * gaussian basis set * water dimer Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 5.498, year: 2014
Effects of interaction imbalance in a strongly repulsive one-dimensional Bose gas
DEFF Research Database (Denmark)
Barfknecht, Rafael Emilio; Zinner, Nikolaj Thomas; Foerster, Angela
2018-01-01
We calculate the spatial distributions and the dynamics of a few-body two-component strongly interacting Bose gas confined to an effectively one-dimensional trapping potential. We describe the densities for each component in the trap for different interaction and population imbalances. We calculate...
DEFF Research Database (Denmark)
Özvegy-Laczka, Csilla; Laczkó, Rozália; Hegedűs, Csilla
2008-01-01
D3 monoclonal antibody shows a function-dependent reactivity to an extracellular epitope of the ABCG2 transporter. In the current experiments we have further characterized the 5D3-ABCG2 interaction. The effect of chemical cross-linking and the modulation of extracellular S-S bridges...... on the transporter function and 5D3 reactivity of ABCG2 were investigated in depth. We found that several protein cross-linkers greatly increased 5D3 labeling in ABCG2 expressing HEK cells; however, there was no correlation between covalent dimer formation, the inhibition of transport activity, and the increase in 5...
International Nuclear Information System (INIS)
Riedl, S.
2009-01-01
This thesis explores the dynamics in an ultracold strongly interacting Fermi gas. Therefore we perform measurements on collective excitation modes and rotational properties of the gas. The strongly interacting gas is realized using an optically trapped Fermi gas of 6 Li atoms, where the interactions can be tuned using a broad Feshbach resonance. Our measurements allow to test the equation of state of the gas, study the transition from hydrodynamic to collisionless behavior, reveal almost ideal hydrodynamic behavior in the nonsuperfluid phase, investigate the lifetime of angular momentum, and show superfluidity through the quenching of the moment of inertia. (author)
Relativistic stability of interacting Fermi gas in a strong magnetic field
International Nuclear Information System (INIS)
Wang Lilin; Tian Jincheng; Men Fudian; Zhang Yipeng
2013-01-01
By means of the single particle energy spectrum of weak interaction between fermions and Poisson formula, the thermodynamic potential function of relativistic Fermi gas in a strong magnetic field is derived. Based on this, we obtained the criterion of stability for the system. The results show that the mechanics stability of a Fermi gas with weak interacting is influenced by the interacting. While the magnetic field is able to regulate the influence and the relativistic effect has almost no effect on it. (authors)
Effects of Interaction Imbalance in a Strongly Repulsive One-Dimensional Bose Gas
Barfknecht, R. E.; Foerster, A.; Zinner, N. T.
2018-05-01
We calculate the spatial distributions and the dynamics of a few-body two-component strongly interacting Bose gas confined to an effectively one-dimensional trapping potential. We describe the densities for each component in the trap for different interaction and population imbalances. We calculate the time evolution of the system and show that, for a certain ratio of interactions, the minority population travels through the system as an effective wave packet.
Gauge unification of basic forces particularly of gravitation with strong interactions
International Nuclear Information System (INIS)
Salam, A.
1977-01-01
Corresponding to the two known types of gauge theories, Yang-Mills with spin-one mediating particles and Einstein Weyl with spin-two mediating particles, it is speculated that two distinct gauge unifications of the basic forces appear to be taking place. One is the familiar Yang-Mills unification of weak and electromagnetic forces with the strong. The second is the less familiar gauge unification of gravitation with spin-two tensor-dominated aspects of strong interactions. It is proposed that there are strongly interacting spin-two strong gravitons obeying Einstein's equations, and their existence gives a clue to an understanding of the (partial) confinement of quarks, as well as of the concept of hadronic temperature, through the use of Schwarzschild de-Sitter-like partially confining solitonic solutions of the strong gravity Einstein equation
Wave, particle-family duality and the conservation of discrete symmetries in strong interaction
International Nuclear Information System (INIS)
van der Spuy, E.
1984-01-01
This paper starts from a nonlinear fermion field equation of motion with a strongly coupled self-interaction. Nonperturbative quark solutions of the equation of motion are constructed in terms of a Reggeized infinite component free spinor field. Such a field carries a family of strongly interacting unstable compounds lying on a Regge locus in the analytically continued quark spin. Such a quark field is naturally confined and also possesses the property of asymptotic freedom. Furthermore, the particular field self-regularizes the interactions and naturally breaks the chiral invariance of the equation of motion. We show why and how the existence of such a strongly coupled solution and its particle-family, wave duality forces a change in the field equation of motion such that it conserves C,P,T, although its individual interaction terms are of V-A and thus C,P nonconserving type
Strong coupling of two interacting excitons confined in a nanocavity-quantum dot system
International Nuclear Information System (INIS)
Cardenas, Paulo C; RodrIguez, Boris A; Quesada, Nicolas; Vinck-Posada, Herbert
2011-01-01
We present a study of the strong coupling between radiation and matter, considering a system of two quantum dots, which are in mutual interaction and interact with a single mode of light confined in a semiconductor nanocavity. We take into account dissipative mechanisms such as the escape of the cavity photons, decay of the quantum dot excitons by spontaneous emission, and independent exciton pumping. It is shown that the mutual interaction between the dots can be measured off-resonance only if the strong coupling condition is reached. Using the quantum regression theorem, a reasonable definition of the dynamical coupling regimes is introduced in terms of the complex Rabi frequency. Finally, the emission spectrum for relevant conditions is presented and compared with the above definition, demonstrating that the interaction between the excitons does not affect the strong coupling.
arXiv Recent results from the strong interactions program of NA61/SHINE
Pulawski, Szymon
2017-01-01
The NA61/SHINE experiment studies hadron production in hadron+hadron, hadron+nucleus and nucleus+nucleus collisions. The strong interactions program has two main purposes: study the properties of the onset of deconfinement and search for the signatures of the critical point of strongly interacting matter. This aim is pursued by performing a two-dimensional scan of the phase diagram by varying the energy/momentum (13A-158A GeV/c) and the system size (p+p, Be+Be, Ar+Sc, Xe+La) of the collisions. This publication reviews recent results from p+p, Be+Be and Ar+Sc interactions. Measured particle spectra are discussed and compared to NA49 results from Pb+Pb collisions. The results illustrate the progress towards scanning the phase diagram of strongly interacting matter.
Experimental and numerical study of the strong interaction between wakes of cylindrical obstacles
International Nuclear Information System (INIS)
Brun, Ch.
1998-01-01
In the context of thermal-hydraulics of nuclear reactors, strong interaction between wakes is encountered in the bottom of reactor vessels where control and measurement rods of variable size and disposition interact with the overall wakes generated in these flow zones. This study deals with the strong interaction between two wakes developed downstream of two parallel cylinders with a small spacing. The analysis focusses on the effect of the Reynolds regime which controls the equilibrium between the inertia and viscosity forces of the fluid and influences the large scale behaviour of the flow with the development of hydrodynamic instabilities and turbulence. The document is organized as follows: the characteristic phenomena of wakes formation downstream of cylindrical obstacles are recalled in the first chapter (single cylinder, interaction between two tubes, case of a bundle of tubes perpendicular to the flow). The experimental setup (hydraulic loop, velocity and pressure measurement instrumentation) and the statistical procedures applied to the signals measured are detailed in chapters 2 and 3. Chapter 4 is devoted to the experimental study of the strong interaction between two tubes. Laser Doppler velocity measurements in the wakes close to cylinders and pressure measurements performed on tube walls are reported in this chapter. In chapter 5, a 2-D numerical simulation of two typical cases of interaction (Re = 1000 and Re = 5000) is performed. In the last chapter, a more complex application of strong interactions inside and downstream of a bunch of staggered tubes is analyzed experimentally for equivalent Reynolds regimes. (J.S.)
Strong excitonic interactions in the oxygen K-edge of perovskite oxides
Energy Technology Data Exchange (ETDEWEB)
Tomita, Kota; Miyata, Tomohiro [Institute of Industrial Science, The University of Tokyo, 4-6-1 Komaba, Meguro, Tokyo 153-8505 (Japan); Olovsson, Weine [Department of Physics, Chemistry and Biology (IFM), Linköping University, SE-581 83 Linköping (Sweden); Mizoguchi, Teruyasu, E-mail: teru@iis.u-tokyo.ac.jp [Institute of Industrial Science, The University of Tokyo, 4-6-1 Komaba, Meguro, Tokyo 153-8505 (Japan)
2017-07-15
Excitonic interactions of the oxygen K-edge electron energy-loss near-edge structure (ELNES) of perovskite oxides, CaTiO{sub 3}, SrTiO{sub 3}, and BaTiO{sub 3}, together with reference oxides, MgO, CaO, SrO, BaO, and TiO{sub 2}, were investigated using a first-principles Bethe–Salpeter equation calculation. Although the transition energy of oxygen K-edge is high, strong excitonic interactions were present in the oxygen K-edge ELNES of the perovskite oxides, whereas the excitonic interactions were negligible in the oxygen K-edge ELNES of the reference compounds. Detailed investigation of the electronic structure suggests that the strong excitonic interaction in the oxygen K-edge ELNES of the perovskite oxides is caused by the directionally confined, low-dimensional electronic structure at the Ti–O–Ti bonds. - Highlights: • Excitonic interaction in oxygen-K edge is investigated. • Strong excitonic interaction is found in the oxygen-K edge of perovskite oxides. • The strong excitonic interaction is ascribed to the low-dimensional and confined electronic structure.
Sil, Debangsu; Rath, Sankar Prasad
2015-10-07
Interaction between heme centers has been cleverly implemented by Nature in order to regulate different properties of multiheme cytochromes, thereby allowing them to perform a wide variety of functions. Our broad interest lies in unmasking the roles played by heme-heme interactions in modulating different properties viz., metal spin state, redox potential etc., of the individual heme centers using an ethane-bridged porphyrin dimer as a synthetic model of dihemes. The large differences in the structure and properties of the diheme complexes, as compared to the monoheme analogs, provide unequivocal evidence of the role played by heme-heme interactions in the dihemes. This Perspective provides a brief account of our recent efforts to explore these interesting aspects and the subsequent outcomes.
Shankar, Akshaya; Jagota, Anand; Mittal, Jeetain
2012-10-11
Single- and double-stranded DNA are increasingly being paired with surfaces and nanoparticles for numerous applications, such as sensing, imaging, and drug delivery. Unlike the majority of DNA structures in bulk that are stabilized by canonical Watson-Crick pairing between Ade-Thy and Gua-Cyt, those adsorbed on surfaces are often stabilized by noncanonical base pairing, quartet formation, and base-surface stacking. Not much is known about these kinds of interactions. To build an understanding of the role of non-Watson-Crick pairing on DNA behavior near surfaces, one requires basic information on DNA base pair stacking and hydrogen-bonding interactions. All-atom molecular simulations of DNA bases in two cases--in bulk water and strongly adsorbed on a graphite surface--are conducted to study the relative strengths of stacking and hydrogen bond interactions for each of the 10 possible combinations of base pairs. The key information obtained from these simulations is the free energy as a function of distance between two bases in a pair. We find that stacking interactions exert the dominant influence on the stability of DNA base pairs in bulk water as expected. The strength of stability for these stacking interactions is found to decrease in the order Gua-Gua > Ade-Gua > Ade-Ade > Gua-Thy > Gua-Cyt > Ade-Thy > Ade-Cyt > Thy-Thy > Cyt-Thy > Cyt-Cyt. On the other hand, mutual interactions of surface-adsorbed base pairs are stabilized mostly by hydrogen-bonding interactions in the order Gua-Cyt > Ade-Gua > Ade-Thy > Ade-Ade > Cyt-Thy > Gua-Gua > Cyt-Cyt > Ade-Cyt > Thy-Thy > Gua-Thy. Interestingly, several non-Watson-Crick base pairings, which are commonly ignored, have similar stabilization free energies due to interbase hydrogen bonding as Watson-Crick pairs. This clearly highlights the importance of non-Watson-Crick base pairing in the development of secondary structures of oligonucleotides near surfaces.
Quantum magnetism in strongly interacting one-dimensional spinor Bose systems
DEFF Research Database (Denmark)
Salami Dehkharghani, Amin; Volosniev, A. G.; Lindgren, E. J.
2015-01-01
-range inter-species interactions much larger than their intra-species interactions and show that they have novel energetic and magnetic properties. In the strongly interacting regime, these systems have energies that are fractions of the basic harmonic oscillator trap quantum and have spatially separated......Strongly interacting one-dimensional quantum systems often behave in a manner that is distinctly different from their higher-dimensional counterparts. When a particle attempts to move in a one-dimensional environment it will unavoidably have to interact and 'push' other particles in order...... ground states with manifestly ferromagnetic wave functions. Furthermore, we predict excited states that have perfect antiferromagnetic ordering. This holds for both balanced and imbalanced systems, and we show that it is a generic feature as one crosses from few- to many-body systems....
Fano resonances in heterogeneous dimers of silicon and gold nanospheres
Zhao, Qian; Yang, Zhong-Jian; He, Jun
2018-06-01
We theoretically investigate the optical properties of dimers consisting of a gold nanosphere and a silicon nanosphere. The absorption spectrum of the gold sphere in the dimer can be significantly altered and exhibits a pronounced Fano profile. Analytical Mie theory and numerical simulations show that the Fano profile is induced by constructive and destructive interference between the incident electric field and the electric field of the magnetic dipole mode of the silicon sphere in a narrow wavelength range. The effects of the silicon sphere size, distance between the two spheres, and excitation configuration on the optical responses of the dimers are studied. Our study reveals the coherent feature of the electric fields of magnetic dipole modes in dielectric nanostructures and the strong interactions of the coherent fields with other nanophotonic structures.
Spectral asymptotics of a strong δ′ interaction supported by a surface
International Nuclear Information System (INIS)
Exner, Pavel; Jex, Michal
2014-01-01
Highlights: • Attractive δ ′ interactions supported by a smooth surface are considered. • Surfaces can be either infinite and asymptotically planar, or compact and closed. • Spectral asymptotics is determined by the geometry of the interaction support. - Abstract: We derive asymptotic expansion for the spectrum of Hamiltonians with a strong attractive δ ′ interaction supported by a smooth surface in R 3 , either infinite and asymptotically planar, or compact and closed. Its second term is found to be determined by a Schrödinger type operator with an effective potential expressed in terms of the interaction support curvatures
Wave, particle-family duality and the conservation of discrete symmetries in strong interaction
International Nuclear Information System (INIS)
Van der Spuy, E.
1984-01-01
This paper starts from a nonlinear fermion field equation of motion with a strongly coupled selfinteraction. Nonperturbative quark solutions of the equation of motion are constructed in terms of a Reggeized infinite component free spinor field. Such a field carries a family of strongly interacting unstable compounds lying on a Regge locus in the analytically continued quark spin. Such a quark field is naturally confined and also possesses the property of asymptotic freedom. Furthermore the particular field selfregularizes the interactions and naturally breaks the chiral invariance of the equation of motion. We show why and how the existence of such a strongly coupled solution and its particle-family, wave duality forces a change in the field equation of motion such that it conserves C, P, T although its individual interaction terms are of V - A and thus C, P nonconserving type
International Nuclear Information System (INIS)
Chan, J.; DePorcel, L.; Dixon, L.
1997-06-01
This conference explored the role of the strong interaction in the physics of hadrons and partons. The Institute attracted 239 physicists from 16 countries to hear lectures on the underlying theory of Quantum Chromodynamics, modern theoretical calculational techniques, and experimental investigation of the strong interaction as it appears in various phenomena. Different regimes in which one can calculate reliably in QCD were addressed in series of lectures on perturbation theory, lattice gauge theories, and heavy quark expansions. Studies of QCD in hadron-hadron collisions, electron-positron annihilation, and electron-proton collisions all give differing perspectives on the strong interaction--from low-x to high-Q 2 . Experimental understanding of the production and decay of heavy quarks as well as the lighter meson states has continued to evolve over the past years, and these topics were also covered at the School. Selected papers have been indexed separately for inclusion in the Energy Science and Technology Database
Strong field QED in lepton colliders and electron/laser interactions
Hartin, Anthony
2018-05-01
The studies of strong field particle physics processes in electron/laser interactions and lepton collider interaction points (IPs) are reviewed. These processes are defined by the high intensity of the electromagnetic fields involved and the need to take them into account as fully as possible. Thus, the main theoretical framework considered is the Furry interaction picture within intense field quantum field theory. In this framework, the influence of a background electromagnetic field in the Lagrangian is calculated nonperturbatively, involving exact solutions for quantized charged particles in the background field. These “dressed” particles go on to interact perturbatively with other particles, enabling the background field to play both macroscopic and microscopic roles. Macroscopically, the background field starts to polarize the vacuum, in effect rendering it a dispersive medium. Particles encountering this dispersive vacuum obtain a lifetime, either radiating or decaying into pair particles at a rate dependent on the intensity of the background field. In fact, the intensity of the background field enters into the coupling constant of the strong field quantum electrodynamic Lagrangian, influencing all particle processes. A number of new phenomena occur. Particles gain an intensity-dependent rest mass shift that accounts for their presence in the dispersive vacuum. Multi-photon events involving more than one external field photon occur at each vertex. Higher order processes which exchange a virtual strong field particle resonate via the lifetimes of the unstable strong field states. Two main arenas of strong field physics are reviewed; those occurring in relativistic electron interactions with intense laser beams, and those occurring in the beam-beam physics at the interaction point of colliders. This review outlines the theory, describes its significant novel phenomenology and details the experimental schema required to detect strong field effects and the
Computational strong-field quantum dynamics. Intense light-matter interactions
Energy Technology Data Exchange (ETDEWEB)
Bauer, Dieter (ed.) [Rostock Univ. (Germany). Inst. fuer Physik
2017-09-01
This graduate textbook introduces the computational techniques to study ultra-fast quantum dynamics of matter exposed to strong laser fields. Coverage includes methods to propagate wavefunctions according to the time dependent Schroedinger, Klein-Gordon or Dirac equation, the calculation of typical observables, time-dependent density functional theory, multi configurational time-dependent Hartree-Fock, time-dependent configuration interaction singles, the strong-field approximation, and the microscopic particle-in-cell approach.
Storti, Mario A.; Nigro, Norberto M.; Paz, Rodrigo R.; Dalcín, Lisandro D.
2009-03-01
In this paper some results on the convergence of the Gauss-Seidel iteration when solving fluid/structure interaction problems with strong coupling via fixed point iteration are presented. The flow-induced vibration of a flat plate aligned with the flow direction at supersonic Mach number is studied. The precision of different predictor schemes and the influence of the partitioned strong coupling on stability is discussed.
Computational strong-field quantum dynamics. Intense light-matter interactions
International Nuclear Information System (INIS)
Bauer, Dieter
2017-01-01
This graduate textbook introduces the computational techniques to study ultra-fast quantum dynamics of matter exposed to strong laser fields. Coverage includes methods to propagate wavefunctions according to the time dependent Schroedinger, Klein-Gordon or Dirac equation, the calculation of typical observables, time-dependent density functional theory, multi configurational time-dependent Hartree-Fock, time-dependent configuration interaction singles, the strong-field approximation, and the microscopic particle-in-cell approach.
Computational strong-field quantum dynamics intense light-matter interactions
2017-01-01
This graduate textbook introduces the computational techniques to study ultra-fast quantum dynamics of matter exposed to strong laser fields. Coverage includes methods to propagate wavefunctions according to the time-dependent Schrödinger, Klein-Gordon or Dirac equation, the calculation of typical observables, time-dependent density functional theory, multi-configurational time-dependent Hartree-Fock, time-dependent configuration interaction singles, the strong-field approximation, and the microscopic particle-in-cell approach.
International Nuclear Information System (INIS)
Drechsler, W.
1977-01-01
A Lagrangian formalism invariant under the gauge group U 1 xUSpsub(2.2) is set up in terms of spinor fields defined on a fiber bundle with Cartan connexion. The fiber of the Cartan bundle over space-time associated with strong interactions is characterized by an elementary length parameter R related to the range of the strong forces, and the structural group USpsub(2.2) of the bundle (being the covering group of the SOsub(4.1) de Sitter group) implies a gauge description of strong interactions based on the noncompact gauge group USpsub(2.2). The U 1 factor in the total gauge group corresponds to the usual gauge formulation for the electromagnetic interactions. The positivity of the energy associated with stable extended one-particle states in this dualistic description of charged hadronic matter immersed in the fiber geometry (this dualism is called strong fiber dynamics (SFD)) requires hadrons to be assigned to representations of the compact subgroup SU 2 xSU 2 of the strong-interaction gauge group USpsub(2.2). A brief discussion of the point-particle limit R→O is given by linking the presented SFD formalism for extended hadrons to an idealized description in terms of operators in a local quantum field theory
Capdevila-Cortada, Marçal; Novoa, Juan J
2012-04-23
The properties of tetrathiafulvalene dimers ([TTF](2)(2+)) and the functionalized ring-shaped bispropargyl (BPP)-functionalized TTF dimers, [BPP-TTF](2)(2+), found at room temperature in charged [3]catenanes, were evaluated by M06L calculations. The results showed that their isolated [TTF](2)(2+) and [BPP-TTF](2)(2+) dimers are energetically unstable towards dissociation. When enclosed in the 4(+)-charged central cyclophane ring of charged [3]catenanes (CBPQT(4+)), [TTF](2)(2+) and [BPP-TTF](2)(2+) dimers are also energetically unstable with respect to leaving the CBPQT(4+) ring; since the barrier for the exiting process is only about 3 kcal mol(-1), that is, within the reach of thermal energies at room temperature (neutral [TTF](2)(0) dimers are stable within the CBPQT(4+) ring). However, the [BPP-TTF](2)(2+) dimers in charged [3]catenanes cannot exit, because this would imply breaking the covalent bonds of the BPP-TTF(+) macrocycle. Finally, it was shown that the [TTF](2)(2+), [BPP-TTF](2)(2+) dimers, and charged [3]catenanes are energetically stable in solution and in crystals of their salts, in the first case due to the interactions with the solvent, and in the second case mostly due to cation-anion interactions. In these environmental conditions at room temperature the TTF units of the [BPP-TTF](2)(2+) dimers make short contacts, thus allowing their SOMO orbitals to overlap: a room-temperature multicenter long bond is formed, similar to those previously found in other [TTF](2)(2+) salts and their solutions. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
International Nuclear Information System (INIS)
Shukla, Nitin; Shukla, P.K.
2011-01-01
The dispersion relation for the dust acoustic wave (DAW) in an unmagnetized dusty plasma cylindrical waveguide is derived, accounting for strong electrostatic interactions between charged dust grains. It is found that the boundary effect limits the radial extent of the DAW. The present result should be helpful for understanding the frequency spectrum of the DAW in a dusty plasma waveguide with strongly coupled charged dust grains. - Highlights: → We study the dust acoustic wave (DAW) in a bounded plasma. → We account for interactions between dust grains. → The boundary effect limits the radial extent of the DAW.
Proceedings of Summer Institute of Particle Physics, July 27-August 7, 1981: the strong interactions
Energy Technology Data Exchange (ETDEWEB)
Mosher, A. (ed.)
1982-01-01
The ninth SLAC Summer Institute on Particle Physics was held in the period July 27 to August 7, 1981. The central topic was the strong interactions with the first seven days spent in a pedagogic mode and the last three in a topical conference. In addition to the morning lectures on experimental and theoretical aspects of the strong interactions, three were lectures on machine physics; this year it was electron-positron colliding beam machines, both storage rings and linear colliders. Twenty-three individual items from the meeting were prepared separately for the data base. (GHT)
Marsh, Lorraine
2015-01-01
Many systems in biology rely on binding of ligands to target proteins in a single high-affinity conformation with a favorable ΔG. Alternatively, interactions of ligands with protein regions that allow diffuse binding, distributed over multiple sites and conformations, can exhibit favorable ΔG because of their higher entropy. Diffuse binding may be biologically important for multidrug transporters and carrier proteins. A fine-grained computational method for numerical integration of total binding ΔG arising from diffuse regional interaction of a ligand in multiple conformations using a Markov Chain Monte Carlo (MCMC) approach is presented. This method yields a metric that quantifies the influence on overall ligand affinity of ligand binding to multiple, distinct sites within a protein binding region. This metric is essentially a measure of dispersion in equilibrium ligand binding and depends on both the number of potential sites of interaction and the distribution of their individual predicted affinities. Analysis of test cases indicates that, for some ligand/protein pairs involving transporters and carrier proteins, diffuse binding contributes greatly to total affinity, whereas in other cases the influence is modest. This approach may be useful for studying situations where "nonspecific" interactions contribute to biological function.
Quasi-particles and effective mean field in strongly interacting matter
International Nuclear Information System (INIS)
Levai, P.; Ko, C.M.
2010-01-01
We introduce a quasi-particle model of strongly interacting quark-gluon matter and explore the possible connection to an effective field theoretical description consisting of a scalar σ field by introducing a dynamically generated mass, M(σ), and a self-consistently determined interaction term, B(σ). We display a possible connection between the two types of effective description, using the Friedberg-Lee model.
Constraining strong baryon-dark-matter interactions with primordial nucleosynthesis and cosmic rays
International Nuclear Information System (INIS)
Cyburt, Richard H.; Fields, Brian D.; Pavlidou, Vasiliki; Wandelt, Benjamin
2002-01-01
Self-interacting dark matter (SIDM) was introduced by Spergel and Steinhardt to address possible discrepancies between collisionless dark matter simulations and observations on scales of less than 1 Mpc. We examine the case in which dark matter particles not only have strong self-interactions but also have strong interactions with baryons. The presence of such interactions will have direct implications for nuclear and particle astrophysics. Among these are a change in the predicted abundances from big bang nucleosynthesis (BBN) and the flux of γ rays produced by the decay of neutral pions which originate in collisions between dark matter and galactic cosmic rays (CR). From these effects we constrain the strength of the baryon-dark-matter interactions through the ratio of baryon-dark-matter interaction cross section to dark matter mass, s. We find that BBN places a weak upper limit on this ratio (less-or-similar sign)10 8 cm 2 g -1 . CR-SIDM interactions, however, limit the possible DM-baryon cross section to (less-or-similar sign)5x10 -3 cm 2 g -1 ; this rules out an energy-independent interaction, but not one which falls with center-of-mass velocity s∝1/v or steeper
The universal sound velocity formula for the strongly interacting unitary Fermi gas
International Nuclear Information System (INIS)
Liu Ke; Chen Ji-Sheng
2011-01-01
Due to the scale invariance, the thermodynamic laws of strongly interacting limit unitary Fermi gas can be similar to those of non-interacting ideal gas. For example, the virial theorem between pressure and energy density of the ideal gas P = 2E/3V is still satisfied by the unitary Fermi gas. This paper analyses the sound velocity of unitary Fermi gases with the quasi-linear approximation. For comparison, the sound velocities for the ideal Boltzmann, Bose and Fermi gas are also given. Quite interestingly, the sound velocity formula for the ideal non-interacting gas is found to be satisfied by the unitary Fermi gas in different temperature regions. (general)
Strong FANCA/FANCG but weak FANCA/FANCC interaction in the yeast 2-hybrid system.
Reuter, T; Herterich, S; Bernhard, O; Hoehn, H; Gross, H J
2000-01-15
Three of at least 8 Fanconi anemia (FA) genes have been cloned (FANCA, FANCC, FANCG), but their functions remain unknown. Using the yeast 2-hybrid system and full-length cDNA, the authors found a strong interaction between FANCA and FANCG proteins. They also obtained evidence for a weak interaction between FANCA and FANCC. Neither FANCA nor FANCC was found to interact with itself. These results support the notion of a functional association between the FA gene products. (Blood. 2000;95:719-720)
Cutolo, Pasquale; Basdevant, Nathalie; Bernadat, Guillaume; Bachelerie, Françoise; Ha-Duong, Tâp
2017-02-01
Despite the recent resolutions of the crystal structure of the chemokine receptor CXCR4 in complex with small antagonists or viral chemokine, a description at the molecular level of the interactions between the full-length CXCR4 and its endogenous ligand, the chemokine CXCL12, in relationship with the receptor recognition and activation, is not yet completely elucidated. Moreover, since CXCR4 is able to form dimers, the question of whether the CXCR4-CXCL12 complex has a 1:1 or 2:1 preferential stoichiometry is still an open question. We present here results of coarse-grained protein-protein docking and molecular dynamics simulations of CXCL12 in association with CXCR4 in monomeric and dimeric states. Our proposed models for the 1:1 and 2:1 CXCR4-CXCL12 quaternary structures are consistent with recognition and activation motifs of both partners provided by the available site-directed mutagenesis data. Notably, we observed that in the 2:1 complex, the chemokine N-terminus makes more steady contacts with the receptor residues critical for binding and activation than in the 1:1 structure, suggesting that the 2:1 stoichiometry would favor the receptor signaling activity with respect to the 1:1 association.
Engineering the Dynamics of Effective Spin-Chain Models for Strongly Interacting Atomic Gases
DEFF Research Database (Denmark)
Volosniev, A. G.; Petrosyan, D.; Valiente, M.
2015-01-01
We consider a one-dimensional gas of cold atoms with strong contact interactions and construct an effective spin-chain Hamiltonian for a two-component system. The resulting Heisenberg spin model can be engineered by manipulating the shape of the external confining potential of the atomic gas. We...
Superfluid quenching of the moment of inertia in a strongly interacting Fermi gas
Riedl, S.; Sánchez Guajardo, E. R.; Kohstall, C.; Hecker Denschlag, J.; Grimm, R.
2011-03-01
We report on the observation of a quenched moment of inertia resulting from superfluidity in a strongly interacting Fermi gas. Our method is based on setting the hydrodynamic gas in slow rotation and determining its angular momentum by detecting the precession of a radial quadrupole excitation. The measurements distinguish between the superfluid and collisional origins of hydrodynamic behavior, and show the phase transition.
Interaction of a neutral composite particle with a strong Coulomb field
International Nuclear Information System (INIS)
Wong, Cheuk-Yin.
1988-01-01
The author discusses the interaction of the quasi-composite (e/sup /plus//e/sup /minus//) system with an external electromagnetic field. This problem addresses the question of the origin of strong positron lines in quasi-elastic heavy-ion reactions. 3 refs
International Nuclear Information System (INIS)
Li Bingan
1988-01-01
In this letter it is shown that even in m π ≠ 0 case the Goldberger-Treiman relation is still hold in the Skyrme model. The mean square radius of strong interaction of nucleon 2 > s 1/2 is computed in the Skyrme model
Czech Academy of Sciences Publication Activity Database
Exner, Pavel; Pankrashkin, K.
2014-01-01
Roč. 39, č. 2 (2014), s. 193-212 ISSN 0360-5302 R&D Projects: GA ČR GAP203/11/0701 Institutional support: RVO:61389005 Keywords : Eigenvalue * Schrödinger operator * singular interaction * strong coupling * 35Q40 * 35P15 * 35J10 Subject RIV: BE - Theoretical Physics Impact factor: 1.013, year: 2014
Spectral asymptotics of a strong delta ' interaction supported by a surface
Czech Academy of Sciences Publication Activity Database
Exner, Pavel; Jex, M.
2014-01-01
Roč. 378, 30-31 (2014), s. 2091-2095 ISSN 0375-9601 R&D Projects: GA ČR(CZ) GA14-06818S Institutional support: RVO:61389005 Keywords : delta ' surface interaction * strong coupling expansion Subject RIV: BE - Theoretical Physics Impact factor: 1.683, year: 2014
On eigenvalue asymptotics for strong delta-interactions supported by surfaces with boundaries
Czech Academy of Sciences Publication Activity Database
Dittrich, Jaroslav; Exner, Pavel; Kuhn, C.; Pankrashkin, K.
2016-01-01
Roč. 97, 1-2 (2016), s. 1-25 ISSN 0921-7134 R&D Projects: GA ČR(CZ) GA14-06818S Institutional support: RVO:61389005 Keywords : singular Schrodinger operator * delta-interaction * strong coupling * eigenvalue Subject RIV: BE - Theoretical Physics Impact factor: 0.933, year: 2016
Finster, Felix
2014-01-01
The causal action principle is analyzed for a system of relativistic fermions composed of massive Dirac particles and neutrinos. In the continuum limit, we obtain an effective interaction described by classical gravity as well as the strong and electroweak gauge fields of the standard model.
Lim, Seng Koon; Sandén, Camilla; Selegård, Robert; Liedberg, Bo; Aili, Daniel
2016-02-01
Membrane active peptides are of large interest for development of drug delivery vehicles and therapeutics for treatment of multiple drug resistant infections. Lack of specificity can be detrimental and finding routes to tune specificity and activity of membrane active peptides is vital for improving their therapeutic efficacy and minimize harmful side effects. We describe a de novo designed membrane active peptide that partition into lipid membranes only when specifically and covalently anchored to the membrane, resulting in pore-formation. Dimerization with a complementary peptide efficiently inhibits formation of pores. The effect can be regulated by proteolytic digestion of the inhibitory peptide by the matrix metalloproteinase MMP-7, an enzyme upregulated in many malignant tumors. This system thus provides a precise and specific route for tuning the permeability of lipid membranes and a novel strategy for development of recognition based membrane active peptides and indirect enzymatically controlled release of liposomal cargo.
The effect of strong intermolecular and chemical interactions on the compatibility of polymers
International Nuclear Information System (INIS)
Askadskii, Andrei A
1999-01-01
The data on compatibility and on the properties of polymer blends are generalised. The emphasis is placed on the formation of strong intermolecular interactions (dipole-dipole interaction and hydrogen bonding) between the components of blends, as well as on the chemical reactions between them. A criterion for the prediction of compatibility of polymers is described in detail. Different cases of compatibility are considered and the dependences of the glass transition temperatures on the composition of blends are analysed. The published data on the effect of strong intermolecular interactions between the blend components on the glass transition temperature are considered. The preparation of interpolymers is described whose macromolecules are composed of incompatible polymers, which leads to the so-called 'forced compatibility.' The bibliography includes 80 references.
Strongly interacting fermion systems. Progress report, November 15, 1994--November 14, 1995
International Nuclear Information System (INIS)
1994-01-01
This paper is the progress report for the period November 15, 1993 to November 14, 1994 for a program which relates to studies of strongly interacting fermion systems. The author has made significant progress in three areas, which are discussed in the report. These are: (1) optical properties in the open-quotes electronic structure program,close quotes calculating optical properties of quartz and urea; (2) quasi-one-dimensional systems, discussing the tuning of the large-density-wave or Peierls distortion in transition-metal linear chain compounds and the universal subgap optical absorptance of classes of quasi-one-dimensional compounds; and (3) other strongly interaction fermion systems, emphasizing the study of the effect of many-body interactions on the low-temperature properties of metals and superconductors
Exact results relating spin-orbit interactions in two-dimensional strongly correlated systems
Kucska, Nóra; Gulácsi, Zsolt
2018-06-01
A 2D square, two-bands, strongly correlated and non-integrable system is analysed exactly in the presence of many-body spin-orbit interactions via the method of Positive Semidefinite Operators. The deduced exact ground states in the high concentration limit are strongly entangled, and given by the spin-orbit coupling are ferromagnetic and present an enhanced carrier mobility, which substantially differs for different spin projections. The described state emerges in a restricted parameter space region, which however is clearly accessible experimentally. The exact solutions are provided via the solution of a matching system of equations containing 74 coupled, non-linear and complex algebraic equations. In our knowledge, other exact results for 2D interacting systems with spin-orbit interactions are not present in the literature.
The strong interaction in e{sup +}e{sup -} annihilation and deep inelastic scattering
Energy Technology Data Exchange (ETDEWEB)
Samuelsson, J
1996-01-01
Various aspects of strong interactions are considered. Correlation effects in the hadronization process in a string model are studied. A discrete approximation scheme to the perturbative QCD cascade in e{sup +}e{sup -} annihilation is formulated. The model, Discrete QCD, predicts a rather low phase space density of `effective gluons`. This is related to the properties of the running coupling constant. It provides us with a simple tool for studies of the strong interaction. It is shown that it reproduces well-known properties of parton cascades. A new formalism for the Deep Inelastic Scattering (DIS) process is developed. The model which is called the Linked Dipole Chain Model provides an interpolation between regions of high Q{sup 2} (DGLAP) and low x-moderate Q{sup 2} (BFKL). It gives a unified treatment of the different interaction channels an a DIS process. 17 figs.
The strong interaction in e+e- annihilation and deep inelastic scattering
International Nuclear Information System (INIS)
Samuelsson, J.
1996-01-01
Various aspects of strong interactions are considered. Correlation effects in the hadronization process in a string model are studied. A discrete approximation scheme to the perturbative QCD cascade in e + e - annihilation is formulated. The model, Discrete QCD, predicts a rather low phase space density of 'effective gluons'. This is related to the properties of the running coupling constant. It provides us with a simple tool for studies of the strong interaction. It is shown that it reproduces well-known properties of parton cascades. A new formalism for the Deep Inelastic Scattering (DIS) process is developed. The model which is called the Linked Dipole Chain Model provides an interpolation between regions of high Q 2 (DGLAP) and low x-moderate Q 2 (BFKL). It gives a unified treatment of the different interaction channels an a DIS process. 17 figs
DEFF Research Database (Denmark)
Petrosyan, David; Molmer, Klaus
2013-01-01
We study two-photon excitation of Rydberg states of atoms under stimulated adiabatic passage with delayed laser pulses. We find that the combination of strong interaction between the atoms in Rydberg state and the spontaneous decay of the intermediate exited atomic state leads to the Rydberg exci...... for deterministic creation and, possibly, extraction of Rydberg atoms or ions one at a time. The sympathetic monitoring via decay of ancilla particles may find wider applications for state preparation and probing of interactions in dissipative many-body systems.......We study two-photon excitation of Rydberg states of atoms under stimulated adiabatic passage with delayed laser pulses. We find that the combination of strong interaction between the atoms in Rydberg state and the spontaneous decay of the intermediate exited atomic state leads to the Rydberg...
Han, Jun; Song, Qin-Qin; Sun, Peng; Zhang, Jin; Wang, Xu; Song, Juan; Li, Gong-Qi; Liu, Ying-Hui; Mei, Guo-Yong; Shi, Qi; Tian, Chan; Chen, Cao; Gao, Chen; Zhao, Bo; Dong, Xiao-Ping
2014-02-01
Proteins of the 14-3-3 family are universal participate in multiple cellular processes. However, their exact role in the pathogenesis of prion diseases remains unclear. In this study, we proposed that human PrP was able to form molecular complex with 14-3-3β. The domains responsible for the interactions between PrP and 14-3-3β were mapped at the segments of amino acid (aa) residues 106-126 within PrP and aa 1-38 within 14-3-3β. Homology modeling revealed that the key aa residues for molecular interaction were D22 and D23 in 14-3-3β as well as K110 in PrP. Mutations in these aa residues inhibited the interaction between the two proteins in vitro. Our results also showed that recombinant PrP encouraged 14-3-3β dimer formation, whereas PrP106-126 peptide inhibited it. Recombinant 14-3-3β disaggregated the mature PrP106-126 fibrils in vitro. Moreover, the PrP-14-3-3 protein complexes were observed in the brain tissues of normal and scrapie agent 263K infected hamsters. Colocalization of PrP and 14-3-3 was seen in the cytoplasm of human neuroblastoma cell line SH-SY5Y, as well as human cervical cancer cell line HeLa transiently expressing full-length human PrP. Our current data suggest the neuroprotection of PrPC and neuron damage caused by PrPSc may be associated with their functions of 14-3-3 dimerization regulation. Copyright © 2013 Elsevier Ltd. All rights reserved.
Energy Technology Data Exchange (ETDEWEB)
Figueiredo, Rute Cunha; Meyer, Nadia Burkowski; Prado, Maria Auxiliadora Fontes; Alves, Ricardo Jose [Universidade Federal de Minas Gerais (UFMG), Belo Horizonte, MG (Brazil). Faculdade de Farmacia. Dept. de Produtos Farmaceuticos], e-mail: ricardodylan@farmacia.ufmg.br; Rojo, Javier [Consejo Superior de Investigaciones Cientificas (CSIC), Sevilla (Spain). Inst. de Investigaciones Quimicas. Grupo de Carbohidratos
2009-07-01
The synthesis of two new D-galactose-based dimers having a 1,4-butanediamine spacer is reported aiming at the evaluation of their interaction with the Erythrina cristagalli lectin. The title compounds were prepared in four and five steps from 2,3,4,6-tetra-O-acetyl-{beta}-D-galactopyranoside bromide, in 20 % and 15 % overall yield, respectively, using the Doebner modification of the Koenavenagel reaction as the key sep. The lectin-carbohydrate interaction could be evaluated for only one dimer, due to solubility problems. A twofold enhancement of affinity was observed, compared to the corresponding monovalent ligand. (author)
Elaboration of the recently proposed test of Pauli's principle under strong interactions
International Nuclear Information System (INIS)
Ktorides, C.N.; Myung, H.C.; Santilli, R.M.
1980-01-01
The primary objective of this paper is to stimulate the experimental verification of the validity or invalidity of Pauli's principle under strong interactions. We first outline the most relevant steps in the evolution of the notion of particle. The spin as well as other intrinsic characteristics of extended, massive, particles under electromagnetic interactions at large distances might be subjected to a mutation under additional strong interactions at distances smaller than their charge radius. These dynamical effects can apparently be conjectured to account for the nonpointlike nature of the particles, their necessary state of penetration to activate the strong interactions, and the consequential emergence of broader forces which imply the breaking of the SU(2)-spin symmetry. We study a characterization of the mutated value of the spin via the transition from the associative enveloping algebra of SU(2) to a nonassociative Lie-admissible form. The departure from the original associative product then becomes directly representative of the breaking of the SU(2)-spin symmetry, the presence of forces more general than those derivable from a potential, and the mutated value of the spin. In turn, such a departure of the spin from conventional quantum-mechanical values implies the inapplicability of Pauli's exclusion principle under strong interactions, because, according to this hypothesis, particles that are fermions under long-range electromagnetic interactions are no longer fermions under these broader, short-range, forces. In nuclear physics possible deviations from Pauli's exclusion principle can at most be very small. These experimental data establish that, for the nuclei considered, nucleons are in a partial state of penetration of their charge volumes although of small statistical character
Heavy quark mass effects and improved tests of the flavor independence of strong interactions
Energy Technology Data Exchange (ETDEWEB)
Burrows, P.N. [Univ. of Oxford (United Kingdom); SLD Collaboration
1998-08-01
A review is given of latest results on tests of the flavor independence of strong interactions. Heavy quark mass effects are evident in the data and are now taken into account at next-to-leading order in QCD perturbation theory. The strong-coupling ratios {alpha}{sub s}{sup b}/{alpha}{sub s}{sup uds} and {alpha}{sub s}{sup c}/{alpha}{sub s}{sup uds} are found to be consistent with unity. Determinations of the b-quark mass m{sub b} (M{sub Z}) are discussed.
International Nuclear Information System (INIS)
Sivan, N.; Levit, S.
1992-01-01
We present a semiclassical theory of charged interacting anyons in a strong magnetic field. We derive the appropriate generalization of the WKB quantization conditions and determine the corresponding wave functions for non separable integrable anyonic systems. This theory is applies to a system of two interacting anyons, two interacting anyons in the presence of an impurity and three interacting anyons. We calculate the dependence of the semiclassical energy levels on the statistical parameter and find regions in which dependence follows very different patterns. The semiclassical treatment allows to find the correlation between these patterns and the change in the character of the classical motion of the system. We also test the accuracy of the mean field approximation for low and high energy states of the three anyons. (author)
Strong constraints on self-interacting dark matter with light mediators
International Nuclear Information System (INIS)
Bringmann, Torsten; Walia, Parampreet
2017-04-01
Coupling dark matter to light new particles is an attractive way to combine thermal production with strong velocity-dependent self-interactions. Here we point out that in such models the dark matter annihilation rate is generically enhanced by the Sommerfeld effect, and we derive the resulting constraints from the Cosmic Microwave Background and other indirect detection probes. For the frequently studied case of s-wave annihilation these constraints exclude the entire parameter space where the self-interactions are large enough to address the small-scale problems of structure formation.
Nonlinear interaction of strong microwave beam with the ionosphere MINIX rocket experiment
Energy Technology Data Exchange (ETDEWEB)
Kaya, N.; Matsumoto, H.; Miyatake, S.; Kimura, I.; Nagatomo, M.; Obayashi, T.
1986-01-01
A rocket-borne experiment called MINIX was carried out to investigate the nonlinear interaction of a strong microwave energy beam with the ionosphere. The MINIX stands for Microwave-Ionosphere Nonlinear Interaction Experiment and was carried out on August 29, 1983. The objectives of the MINIX is to study possible impacts of the SPS microwave energy beam on the ionosphere such as the Ohmic heating and plasma wave excitation. The experiment showed that the microwave with f = 2.45 GHz nonlinearly excites various electrostatic plasma waves, though no Ohmic heating effects were detected. 4 figures.
Nonlinear interaction of strong microwave beam with the ionosphere MINIX rocket experiment
Kaya, N.; Matsumoto, H.; Miyatake, S.; Kimura, I.; Nagatomo, M.
A rocket-borne experiment called 'MINIX' was carried out to investigate the nonlinear interaction of a strong microwave energy beam with the ionosphere. The MINIX stands for Microwave-Ionosphere Nonlinear Interaction eXperiment and was carried out on August 29, 1983. The objective of the MINIX is to study possible impacts of the SPS microwave energy beam on the ionosphere, such as the ohmic heating and plasma wave excitation. The experiment showed that the microwave with f = 2.45 GHz nonlinearly excites various electrostatic plasma waves, though no ohmic heating effects were detected.
Nonlinear interaction of strong microwave beam with the ionosphere MINIX rocket experiment
International Nuclear Information System (INIS)
Kaya, N.; Matsumoto, H.; Miyatake, S.; Kimura, I.; Nagatomo, M.; Obayashi, T.
1986-01-01
A rocket-borne experiment called MINIX was carried out to investigate the nonlinear interaction of a strong microwave energy beam with the ionosphere. The MINIX stands for Microwave-Ionosphere Nonlinear Interaction Experiment and was carried out on August 29, 1983. The objectives of the MINIX is to study possible impacts of the SPS microwave energy beam on the ionosphere such as the Ohmic heating and plasma wave excitation. The experiment showed that the microwave with f = 2.45 GHz nonlinearly excites various electrostatic plasma waves, though no Ohmic heating effects were detected. 4 figures
Metastability and coherence of repulsive polarons in a strongly interacting Fermi mixture
DEFF Research Database (Denmark)
Kohstall, Cristoph; Zaccanti, Mattheo; Jag, Matthias
2012-01-01
show that a well-defined quasiparticle exists for strongly repulsive interactions. We measure the energy and the lifetime of this ‘repulsive polaron’9, 12, 13, and probe its coherence properties by measuring the quasiparticle residue. The results are well described by a theoretical approach that takes...... into account the finite effective range of the interaction in our system. We find that when the effective range is of the order of the interparticle spacing, there is a substantial increase in the lifetime of the quasiparticles. The existence of such a long-lived, metastable many-body state offers intriguing...
Strong constraints on self-interacting dark matter with light mediators
Energy Technology Data Exchange (ETDEWEB)
Bringmann, Torsten; Walia, Parampreet [Oslo Univ. (Norway). Dept. of Physics; Kahlhoefer, Felix; Schmidt-Hoberg, Kai [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany)
2017-04-15
Coupling dark matter to light new particles is an attractive way to combine thermal production with strong velocity-dependent self-interactions. Here we point out that in such models the dark matter annihilation rate is generically enhanced by the Sommerfeld effect, and we derive the resulting constraints from the Cosmic Microwave Background and other indirect detection probes. For the frequently studied case of s-wave annihilation these constraints exclude the entire parameter space where the self-interactions are large enough to address the small-scale problems of structure formation.
Universal Behavior of Pair Correlations in a Strongly Interacting Fermi Gas
International Nuclear Information System (INIS)
Kuhnle, E. D.; Hu, H.; Liu, X.-J.; Dyke, P.; Mark, M.; Drummond, P. D.; Hannaford, P.; Vale, C. J.
2010-01-01
We show that short-range pair correlations in a strongly interacting Fermi gas follow a simple universal law described by Tan's relations. This is achieved through measurements of the static structure factor which displays a universal scaling proportional to the ratio of Tan's contact to the momentum C/q. Bragg spectroscopy of ultracold 6 Li atoms from a periodic optical potential is used to measure the structure factor for a wide range of momenta and interaction strengths, providing broad confirmation of this universal law. We calibrate our Bragg spectra using the f-sum rule, which is found to improve the accuracy of the structure factor measurement.
International Nuclear Information System (INIS)
Arnold, R.C.
1975-12-01
A systematic calculus of long-range Regge cut effects in multiparticle production is constructed in the form of an infrared-divergent stochastic field theory. Total cross sections and two-body overlap integrals in such a theory may depend very sensitively upon internal quantum-numbers of incident particles, resulting in a strong symmetry breaking at ultra-high energies. Such symmetry violations will influence low energy processes through dispersion relations, and a bootstrap of weak interactions becomes possible. A rough analytic estimate of the scale of thresholds for such effects yields a BCS-type gap equation, which expresses the scale of weak and electromagnetic couplings in terms of purely strong-interaction parameters
On the Frequency Distribution of Neutral Particles from Low-Energy Strong Interactions
Directory of Open Access Journals (Sweden)
Federico Colecchia
2017-01-01
Full Text Available The rejection of the contamination, or background, from low-energy strong interactions at hadron collider experiments is a topic that has received significant attention in the field of particle physics. This article builds on a particle-level view of collision events, in line with recently proposed subtraction methods. While conventional techniques in the field usually concentrate on probability distributions, our study is, to our knowledge, the first attempt at estimating the frequency distribution of background particles across the kinematic space inside individual collision events. In fact, while the probability distribution can generally be estimated given a model of low-energy strong interactions, the corresponding frequency distribution inside a single event typically deviates from the average and cannot be predicted a priori. We present preliminary results in this direction and establish a connection between our technique and the particle weighting methods that have been the subject of recent investigation at the Large Hadron Collider.
Gauge unification of basic forces, particularly of gravitation with strong interactions
International Nuclear Information System (INIS)
Salam, A.
1977-01-01
An attempt is made to present a case for the use of both the Einstein--Weyl spin-two and the Yang--Mills spin-one gauge structures for describing strong interactions. By emphasizing both spin-one and -two aspects of this force, it is hoped that a unification of this force, on the one hand, with gravity theory and, on the other, with the electromagnetic and weak interactions can be achieved. A Puppi type of tetrahedral interralation of fundamental forces, with the strong force playing a pivotal role due to its mediation through both spin-one and -two quanta, is proposed. It is claimed that the gauge invariance of gravity theory permits the use of ambuguity-free nonpolynomial techniques and thereby the securing of relistic regularization in gravity-modified field theories with the Newtonian constant G/sub N/ providing a relistic cutoff. 37 references
Les Houches Summer School : Strongly Interacting Quantum Systems out of Equilibrium
Millis, Andrew J; Parcollet, Olivier; Saleur, Hubert; Cugliandolo, Leticia F
2016-01-01
Over the last decade new experimental tools and theoretical concepts are providing new insights into collective nonequilibrium behavior of quantum systems. The exquisite control provided by laser trapping and cooling techniques allows us to observe the behavior of condensed bose and degenerate Fermi gases under nonequilibrium drive or after quenches' in which a Hamiltonian parameter is suddenly or slowly changed. On the solid state front, high intensity short-time pulses and fast (femtosecond) probes allow solids to be put into highly excited states and probed before relaxation and dissipation occur. Experimental developments are matched by progress in theoretical techniques ranging from exact solutions of strongly interacting nonequilibrium models to new approaches to nonequilibrium numerics. The summer school Strongly interacting quantum systems out of equilibrium' held at the Les Houches School of Physics as its XCIX session was designed to summarize this progress, lay out the open questions and define dir...
Anisotropy of the magnetoviscous effect in a cobalt ferrofluid with strong interparticle interaction
Energy Technology Data Exchange (ETDEWEB)
Linke, J.M., E-mail: julia.linke@tu-dresden.de; Odenbach, S.
2015-12-15
The anisotropy of the magnetoviscous effect (MVE) of a cobalt ferrofluid has been studied in a slit die viscometer for three orientations of the applied magnetic field: in the direction of the fluid flow (Δη{sub 1}), the velocity gradient (Δη{sub 2}), and the vorticity (Δη{sub 3}). The majority of the cobalt particles in the ferrofluid exhibit a strong dipole–dipole interaction, which corresponds to a weighted interaction parameter of λ{sub w}≈10.6. Thus the particles form extended microstructures inside the fluid which lead to enhanced MVE ratios Δη{sub 2}/Δη{sub 1}>3 and Δη{sub 3}/Δη{sub 1}>0.3 even for strong shearing and weak magnetic fields compared to fluids which contain non-interacting spherical particles with Δη{sub 2}/Δη{sub 1}≈1 and Δη{sub 3}/Δη{sub 1}=0. Furthermore, a non-monotonic increase has been observed in the shear thinning behavior of Δη{sub 2} for weak magnetic fields <10 kA/m, which cannot be explained solely by the magnetization of individual particles and the formation and disintegration of linear particle chains but indicates the presence of heterophase structures. - Highlights: • The magnetoviscous effect in a ferrofluid with strong interaction is anisotropic. • The strongest effects are found in a magnetic field parallel to the shear gradient. • In strong magnetic fields the microstructure of the fluid is stable against shearing. • In weak fields the fluid behavior indicates the presence of heterophase structures.
Quasi-particle description of strongly interacting matter: Towards a foundation
International Nuclear Information System (INIS)
Bluhm, M.; Kaempfer, B.; Schulze, R.; Seipt, D.
2007-01-01
We confront our quasi-particle model for the equation of state of strongly interacting matter with recent first-principle QCD calculations. In particular, we test its applicability at finite baryon densities by comparing with Taylor expansion coefficients of the pressure for two quark flavours. We outline a chain of approximations starting from the Φ-functional approach to QCD which motivates the quasi-particle picture. (orig.)
Limitations due to strong head-on beam-beam interactions (MD 1434)
Buffat, Xavier; Iadarola, Giovanni; Papadopoulou, Parthena Stefania; Papaphilippou, Yannis; Pellegrini, Dario; Pojer, Mirko; Crockford, Guy; Salvachua Ferrando, Belen Maria; Trad, Georges; Barranco Garcia, Javier; Pieloni, Tatiana; Tambasco, Claudia; CERN. Geneva. ATS Department
2017-01-01
The results of an experiment aiming at probing the limitations due to strong head on beam-beam interactions are reported. It is shown that the loss rates significantly increase when moving the working point up and down the diagonal, possibly due to effects of the 10th and/or 14th order resonances. Those limitations are tighter for bunches with larger beam-beam parameters, a maximum total beam-beam tune shift just below 0.02 could be reached.
Fractional energy states of strongly-interacting bosons in one dimension
DEFF Research Database (Denmark)
Zinner, Nikolaj Thomas; G. Volosniev, A.; V. Fedorov, D.
2014-01-01
We study two-component bosonic systems with strong inter-species and vanishing intra-species interactions. A new class of exact eigenstates is found with energies that are {\\it not} sums of the single-particle energies with wave functions that have the characteristic feature that they vanish over...... than three particles. The states can be probed using the same techniques that have recently been used for fermionic few-body systems in quasi-1D.......We study two-component bosonic systems with strong inter-species and vanishing intra-species interactions. A new class of exact eigenstates is found with energies that are {\\it not} sums of the single-particle energies with wave functions that have the characteristic feature that they vanish over...... extended regions of coordinate space. This is demonstrated in an analytically solvable model for three equal mass particles, two of which are identical bosons, which is exact in the strongly-interacting limit. We numerically verify our results by presenting the first application of the stochastic...
Strong excitonic interactions in the oxygen K-edge of perovskite oxides.
Tomita, Kota; Miyata, Tomohiro; Olovsson, Weine; Mizoguchi, Teruyasu
2017-07-01
Excitonic interactions of the oxygen K-edge electron energy-loss near-edge structure (ELNES) of perovskite oxides, CaTiO 3 , SrTiO 3 , and BaTiO 3 , together with reference oxides, MgO, CaO, SrO, BaO, and TiO 2 , were investigated using a first-principles Bethe-Salpeter equation calculation. Although the transition energy of oxygen K-edge is high, strong excitonic interactions were present in the oxygen K-edge ELNES of the perovskite oxides, whereas the excitonic interactions were negligible in the oxygen K-edge ELNES of the reference compounds. Detailed investigation of the electronic structure suggests that the strong excitonic interaction in the oxygen K-edge ELNES of the perovskite oxides is caused by the directionally confined, low-dimensional electronic structure at the Ti-O-Ti bonds. Copyright © 2016 Elsevier B.V. All rights reserved.
arXiv Recent results and future of the NA61/SHINE strong interactions program
Lysakowski, Bartosz
2018-01-01
NA61/SHINE is a fixed target experiment at the CERN Super-Proton- Synchrotron. The main goals of the experiment are to discover the critical point of strongly interacting matter and study the properties of the onset of deconfnement. In order to reach these goals the collaboration studies hadron production properties in nucleus-nucleus, proton-proton and proton-nucleus interactions. In this talk, recent results on particle production in p+p interactions, as well as Be+Be and Ar+Sc collisions in the SPS energy range are reviewed. The results are compared with available world data. The future of the NA61/SHINE scientifc program is also presented.
Interacting Electrons and Holes in Quasi-2D Quantum Dots in Strong Magnetic Fields
Hawrylak, P.; Sheng, W.; Cheng, S.-J.
2004-09-01
Theory of optical properties of interacting electrons and holes in quasi-2D quantum dots in strong magnetic fields is discussed. In two dimensions and the lowest Landau level, hidden symmetries control the interaction of the interacting system with light. By confining electrons and holes into quantum dots hidden symmetries can be removed and the excitation spectrum of electrons and excitons can be observed. We discuss a theory electronic and of excitonic quantum Hall droplets at a filling factorν=2. For an excitonic quantum Hall droplet the characteristic emission spectra are predicted to be related to the total spin of electron and hole configurations. For the electronic droplet the excitation spectrum of the droplet can be mapped out by measuring the emission for increasing number of electrons.
Interacting electrons and holes in quasi-2D quantum dots in strong magnetic fields
International Nuclear Information System (INIS)
Hawrylak, P.; Sheng, W.; Cheng, S.-J.
2004-01-01
Theory of optical properties of interacting electrons and holes in quasi-2D quantum dots in strong magnetic fields is discussed. In two dimensions and the lowest Landau level, hidden symmetries control the interaction of the interacting system with light. By confining electrons and holes into quantum dots hidden symmetries can be removed and the excitation spectrum of electrons and excitons can be observed. We discuss a theory electronic and excitonic quantum Hall droplets at a filling factor υ = 2. For an excitonic quantum Hall droplet the characteristic emission spectra are predicted to be related to the total spin of electron and hole configurations. For the electronic droplet the excitation spectrum of the droplet can be mapped out by measuring the emission for increasing number of electrons. (author)
Strong late-time circumstellar interaction in the peculiar supernova iPTF14hls
Andrews, Jennifer E.; Smith, Nathan
2018-06-01
We present a moderate-resolution spectrum of the peculiar Type II supernova (SN) iPTF14hls taken on day 1153 after discovery. This spectrum reveals the clear signature of shock interaction with dense circumstellar material (CSM). We suggest that this CSM interaction may be an important clue for understanding the extremely unusual photometric and spectroscopic evolution seen over the first 600 d of iPTF14hls. The late-time spectrum shows a double-peaked intermediate-width H α line indicative of expansion speeds around 1000 km s-1, with the double-peaked shape hinting at a disc-like geometry in the CSM. If the CSM were highly asymmetric, perhaps in a disc or torus that was ejected from the star 3-6 yr prior to explosion, the CSM interaction could have been overrun and hidden below the SN ejecta photosphere from a wide range of viewing angles. In that case, CSM interaction luminosity would have been thermalized well below the photosphere, potentially sustaining the high luminosity without exhibiting the traditional observational signatures of strong CSM interaction (narrow H α emission and X-rays). Variations in density structure of the CSM could account for the multiple rebrightenings of the light curve. We propose that a canonical 1 × 1051 erg explosion energy with enveloped CSM interaction as seen in some recent SNe, rather than an entirely new explosion mechanism, may be adequate to explain the peculiar evolution of iPTF14hls.
Dovzhenko, D S; Ryabchuk, S V; Rakovich, Yu P; Nabiev, I R
2018-02-22
Resonance interaction between a molecular transition and a confined electromagnetic field can reach the coupling regime where coherent exchange of energy between light and matter becomes reversible. In this case, two new hybrid states separated in energy are formed instead of independent eigenstates, which is known as Rabi splitting. This modification of the energy spectra of the system offers new possibilities for controlled impact on various fundamental properties of coupled matter (such as the rate of chemical reactions and the conductivity of organic semiconductors). To date, the strong coupling regime has been demonstrated in many configurations under different ambient conditions. However, there is still no comprehensive approach to determining parameters for achieving the strong coupling regime for a wide range of practical applications. In this review, a detailed analysis of various systems and corresponding conditions for reaching strong coupling is carried out and their advantages and disadvantages, as well as the prospects for application, are considered. The review also summarizes recent experiments in which the strong coupling regime has led to new interesting results, such as the possibility of collective strong coupling between X-rays and matter excitation in a periodic array of Fe isotopes, which extends the applications of quantum optics; a strong amplification of the Raman scattering signal from a coupled system, which can be used in surface-enhanced and tip-enhanced Raman spectroscopy; and more efficient second-harmonic generation from the low polaritonic state, which is promising for nonlinear optics. The results reviewed demonstrate great potential for further practical applications of strong coupling in the fields of photonics (low-threshold lasers), quantum communications (switches), and biophysics (molecular fingerprinting).
Mohapatra, Swagat K; Fonari, Alexandr; Risko, Chad; Yesudas, Kada; Moudgil, Karttikay; Delcamp, Jared H; Timofeeva, Tatiana V; Brédas, Jean-Luc; Marder, Seth R; Barlow, Stephen
2014-11-17
The dimers of some Group 8 metal cyclopentadienyl/arene complexes and Group 9 metallocenes can be handled in air, yet are strongly reducing, making them useful n-dopants in organic electronics. In this work, the X-ray molecular structures are shown to resemble those of Group 8 metal cyclopentadienyl/pentadienyl or Group 9 metal cyclopentadienyl/diene model compounds. Compared to those of the model compounds, the DFT HOMOs of the dimers are significantly destabilized by interactions between the metal and the central CC σ-bonding orbital, accounting for the facile oxidation of the dimers. The lengths of these CC bonds (X-ray or DFT) do not correlate with DFT dissociation energies, the latter depending strongly on the monomer stabilities. Ru and Ir monomers are more reducing than their Fe and Rh analogues, but the corresponding dimers also exhibit much higher dissociation energies, so the estimated monomer cation/neutral dimer potentials are, with the exception of that of [RhCp2 ]2 , rather similar (-1.97 to -2.15 V vs. FeCp2 (+/0) in THF). The consequences of the variations in bond strength and redox potentials for the reactivity of the dimers are discussed. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
Mohapatra, Swagat Kumar
2014-10-03
The dimers of some Group 8 metal cyclopentadienyl/ arene complexes and Group 9 metallocenes can be handled in air, yet are strongly reducing, making them useful n-dopants in organic electronics. In this work, the Xray molecular structures are shown to resemble those of Group 8 metal cyclopentadienyl/pentadienyl or Group 9 metal cyclopentadienyl/diene model compounds. Compared to those of the model compounds, the DFT HOMOs of the dimers are significantly destabilized by interactions between the metal and the central C-C σ-bonding orbital, accounting for the facile oxidation of the dimers. The lengths of these C-C bonds (X-ray or DFT) do not correlate with DFT dissociation energies, the latter depending strongly on the monomer stabilities. Ru and Ir monomers are more reducing than their Fe and Rh analogues, but the corresponding dimers also exhibit much higher dissociation energies, so the estimated monomer cation/neutral dimer potentials are, with the exception of that of [RhCp2]2, rather similar (-1.97 to-2.15 V vs. FeCp2 +/0 in THF). The consequences of the variations in bond strength and redox potentials for the reactivity of the dimers are discussed.
Mohapatra, Swagat Kumar; Fonari, Alexandr; Risko, Chad; Yesudas, Kada; Moudgil, Karttikay; Delcamp, Jared Heath; Timofeeva, Tatiana V.; Bredas, Jean-Luc; Marder, Seth R.; Barlow, Stephen J.
2014-01-01
The dimers of some Group 8 metal cyclopentadienyl/ arene complexes and Group 9 metallocenes can be handled in air, yet are strongly reducing, making them useful n-dopants in organic electronics. In this work, the Xray molecular structures are shown to resemble those of Group 8 metal cyclopentadienyl/pentadienyl or Group 9 metal cyclopentadienyl/diene model compounds. Compared to those of the model compounds, the DFT HOMOs of the dimers are significantly destabilized by interactions between the metal and the central C-C σ-bonding orbital, accounting for the facile oxidation of the dimers. The lengths of these C-C bonds (X-ray or DFT) do not correlate with DFT dissociation energies, the latter depending strongly on the monomer stabilities. Ru and Ir monomers are more reducing than their Fe and Rh analogues, but the corresponding dimers also exhibit much higher dissociation energies, so the estimated monomer cation/neutral dimer potentials are, with the exception of that of [RhCp2]2, rather similar (-1.97 to-2.15 V vs. FeCp2 +/0 in THF). The consequences of the variations in bond strength and redox potentials for the reactivity of the dimers are discussed.
Błoński, Piotr; Hafner, Jürgen
2014-04-09
The structural and magnetic properties of mixed PtCo, PtFe, and IrCo dimers in the gas phase and supported on a free-standing graphene layer have been calculated using density-functional theory, both in the scalar-relativistic limit and self-consistently including spin-orbit coupling. The influence of the strong magnetic moments of the 3d atoms on the spin and orbital moments of the 5d atoms, and the influence of the strong spin-orbit coupling contributed by the 5d atom on the orbital moments of the 3d atoms have been studied in detail. The magnetic anisotropy energy is found to depend very sensitively on the nature of the eigenstates in the vicinity of the Fermi level, as determined by band filling, exchange splitting and spin-orbit coupling. The large magnetic anisotropy energy of free PtCo and IrCo dimers relative to the easy direction parallel to the dimer axis is coupled to a strong anisotropy of the orbital magnetic moments of the Co atom for both dimers, and also on the Ir atom in IrCo. In contrast the PtFe dimer shows a weak perpendicular anisotropy and only small spin and orbital anisotropies of opposite sign on the two atoms. For dimers supported on graphene, the strong binding within the dimer and the stronger interaction of the 3d atom with the substrate stabilizes an upright geometry. Spin and orbital moments on the 3d atom are strongly quenched, but due to the weaker binding within the dimer the properties of the 5d atom are more free-atom-like with increased spin and orbital moments. The changes in the magnetic moment are reflected in the structure of the electronic eigenstates near the Fermi level, for all three dimers the easy magnetic direction is now parallel to the dimer axis and perpendicular to the graphene layer. The already very large magnetic anisotropy energy (MAE) of IrCo is further enhanced by the interaction with the support, the MAE of PtFe changes sign, and that of the PtCo dimer is reduced. These changes are discussed in relation to
Magnetized Langmuir wave packets excited by a strong beam-plasma interaction
International Nuclear Information System (INIS)
Pelletier, G.; Sol, H.; Asseo, E.
1988-01-01
The physics of beam-plasma interaction, which has been investigated for a long time mostly in relation with solar bursts, is now more widely invoked in various astrophysical contexts such as pulsars, active galactic nuclei, close binaries, cataclysmic variables, γ bursters, and so on. In these situations the interaction is more likely in the spirit of strong Langmuir turbulence rather than in the spirit of quasilinear theory. Many investigations have been done for two opposite extremes, namely, in very weak and in very strong magnetic fields. Very few properties of the strong Langmuir turbulence are known in the most usual astrophysical situation where the magnetic field plays a significant role but is not strong enough to force the electrons into one-dimensional motion. For this case, we analyze the dynamics of Langmuir wave packets and provide new results about the stability of the solitons against transverse perturbations. It turns out that both the averaged Lagrangian method and the adiabatic perturbation method derived from the inverse scattering transform give exactly the same results (which is not obvious in soliton perturbation theory). In particular, they predict the stability of the solitons as long as the electron gyrofrequency is greater than the plasma frequency (strong magnetic field) and their instability against transverse self-modulation in the opposite case (weak magnetic field); moreover, they allow one to deduce the self-similar collapsing oblate cavitons in the latter case. The laws governing the collapse of the wave packets determine the relaxation of the beam in the surrounding medium and we derive a useful formula giving the power loss of the beam. We outline the astrophysical consequences of this investigation
Directory of Open Access Journals (Sweden)
Aditi Gupta
2016-03-01
Full Text Available Epistatic interactions between residues determine a protein's adaptability and shape its evolutionary trajectory. When a protein experiences a changed environment, it is under strong selection to find a peak in the new fitness landscape. It has been shown that strong selection increases epistatic interactions as well as the ruggedness of the fitness landscape, but little is known about how the epistatic interactions change under selection in the long-term evolution of a protein. Here we analyze the evolution of epistasis in the protease of the human immunodeficiency virus type 1 (HIV-1 using protease sequences collected for almost a decade from both treated and untreated patients, to understand how epistasis changes and how those changes impact the long-term evolvability of a protein. We use an information-theoretic proxy for epistasis that quantifies the co-variation between sites, and show that positive information is a necessary (but not sufficient condition that detects epistasis in most cases. We analyze the "fossils" of the evolutionary trajectories of the protein contained in the sequence data, and show that epistasis continues to enrich under strong selection, but not for proteins whose environment is unchanged. The increase in epistasis compensates for the information loss due to sequence variability brought about by treatment, and facilitates adaptation in the increasingly rugged fitness landscape of treatment. While epistasis is thought to enhance evolvability via valley-crossing early-on in adaptation, it can hinder adaptation later when the landscape has turned rugged. However, we find no evidence that the HIV-1 protease has reached its potential for evolution after 9 years of adapting to a drug environment that itself is constantly changing. We suggest that the mechanism of encoding new information into pairwise interactions is central to protein evolution not just in HIV-1 protease, but for any protein adapting to a changing
International Nuclear Information System (INIS)
Chen Yu; Araki, Yasuyuki; Dini, Danilo; Liu Ying; Ito, Osamu; Fujitsuka, Mamoru
2006-01-01
The steady-state and time-resolved photophysical properties and some molecular orbital calculation results of a dimeric indium phthalocyanine complex with an indium-indium bond, i.e., [tBu 4 PcIn] 2 .2tmed, have been described. The results regarding triplet excited state lifetimes can be ascribed to strong intramolecular interactions existing only in the excited state of this dimer because no significant difference in the absorption spectra of the tBu 4 PcInCl monomer and the [tBu 4 PcIn] 2 .2tmed dimer is observed, suggesting that no ground-state interaction can be assessed. The deactivation processes of the excited singlet state of [tBu 4 PcIn] 2 .2tmed are apparently faster than that of μ-oxo-bridged PcIn dimer [tBu 4 PcIn] 2 O. Molecular orbital calculation on the PcIn dimer shows no node between two indium atoms was found in the HOMO - 2 of the PcIn-InPc dimer, suggesting that bonding electrons distribute between two indium atoms
Ghodrat, Malihe; Naji, Ali; Komaie-Moghaddam, Haniyeh; Podgornik, Rudolf
2015-05-07
We study the effective interaction mediated by strongly coupled Coulomb fluids between dielectric surfaces carrying quenched, random monopolar charges with equal mean and variance, both when the Coulomb fluid consists only of mobile multivalent counterions and when it consists of an asymmetric ionic mixture containing multivalent and monovalent (salt) ions in equilibrium with an aqueous bulk reservoir. We analyze the consequences that follow from the interplay between surface charge disorder, dielectric and salt image effects, and the strong electrostatic coupling that results from multivalent counterions on the distribution of these ions and the effective interaction pressure they mediate between the surfaces. In a dielectrically homogeneous system, we show that the multivalent counterions are attracted towards the surfaces with a singular, disorder-induced potential that diverges logarithmically on approach to the surfaces, creating a singular but integrable counterion density profile that exhibits an algebraic divergence at the surfaces with an exponent that depends on the surface charge (disorder) variance. This effect drives the system towards a state of lower thermal 'disorder', one that can be described by a renormalized temperature, exhibiting thus a remarkable antifragility. In the presence of an interfacial dielectric discontinuity, the singular behavior of counterion density at the surfaces is removed but multivalent counterions are still accumulated much more strongly close to randomly charged surfaces as compared with uniformly charged ones. The interaction pressure acting on the surfaces displays in general a highly non-monotonic behavior as a function of the inter-surface separation with a prominent regime of attraction at small to intermediate separations. This attraction is caused directly by the combined effects from charge disorder and strong coupling electrostatics of multivalent counterions, which dominate the surface-surface repulsion due to
International Nuclear Information System (INIS)
Lee, J. Y.; Guan, X. W.; Batchelor, M. T.; Lee, C.
2009-01-01
We investigate magnetism and quantum phase transitions in a one-dimensional system of integrable spin-1 bosons with strongly repulsive density-density interaction and antiferromagnetic spin-exchange interaction via the thermodynamic Bethe ansatz method. At zero temperature, the system exhibits three quantum phases: (i) a singlet phase of boson pairs when the external magnetic field H is less than the lower critical field H c1 ; (ii) a ferromagnetic phase of atoms in the hyperfine state |F=1, m F =1> when the external magnetic field exceeds the upper critical field H c2 ; and (iii) a mixed phase of singlet pairs and unpaired atoms in the intermediate region H c1 c2 . At finite temperatures, the spin fluctuations affect the thermodynamics of the model through coupling the spin bound states to the dressed energy for the unpaired m F =1 bosons. However, such spin dynamics is suppressed by a sufficiently strong external field at low temperatures. Thus the singlet pairs and unpaired bosons may form a two-component Luttinger liquid in the strong coupling regime.
Liber, Miran; Tomov, Toma E; Tsukanov, Roman; Berger, Yaron; Popov, Mary; Khara, Dinesh C; Nir, Eyal
2018-06-01
Organizing DNA origami building blocks into higher order structures is essential for fabrication of large structurally and functionally diverse devices and molecular machines. Unfortunately, the yields of origami building block attachment reactions are typically not sufficient to allow programed assembly of DNA devices made from more than a few origami building blocks. To investigate possible reasons for these low yields, a detailed single-molecule fluorescence study of the dynamics of rectangular origami dimerization and origami dimer dissociation reactions is conducted. Reactions kinetics and yields are investigated at different origami and ion concentrations, for different ion types, for different lengths of bridging strands, and for the "sticky end" and "weaving welding" attachment techniques. Dimerization yields are never higher than 86%, which is typical for such systems. Analysis of the dynamic data shows that the low yield cannot be explained by thermodynamic instability or structural imperfections of the origami constructs. Atomic force microscopy and gel electrophoresis evidence reveal self-dimerization of the origami monomers, likely via blunt-end interactions made possible by the presence of bridging strands. It is suggested that this mechanism is the major factor that inhibits correct dimerization and means to overcome it are discussed. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
Electron gas interacting in a metal, submitted to a strong magnetic field
International Nuclear Information System (INIS)
Alcaraz, Francisco Castilho
1977-01-01
Using the propagator's technique in the grand ensemble developed by Montroll and Ward we investigate the magnetic properties of an interacting electron gas in a strong magnetic field. The free propagator properly constructed shows that the spin paramagnetism does not have a term with strong temperature dependence, contrary to the result of Isihara. Considering the electron density to be constant, the dHVA oscillations in the magnetic susceptibility and sound velocity, considering the effects of first exchange interactions, show only one phase in agreement with experimental result, while Ichimura and Isihara obtained two phases differing by π/2. The effects of first order exchange interactions in the dHVA oscillations of the magnetic susceptibility and sound velocity give rise to an exponential factor in the amplitudes of oscillator (Dingle factor), being the Dingle temperature linearly dependent of the Fermi velocity. The calculations of the ring diagram contribution to the grand partition function, show that the approximation used by Isihara for this calculations is not good and the dHVA oscillations of the contributions from the ring diagrams for the grand partition function have a phase differing by π/2 from that obtained by Isihara. (author)
Observation of Spin-Polarons in a strongly interacting Fermi liquid
Zwierlein, Martin
2009-03-01
We have observed spin-polarons in a highly imbalanced mixture of fermionic atoms using tomographic RF spectroscopy. Feshbach resonances allow to freely tune the interactions between the two spin states involved. A single spin down atom immersed in a Fermi sea of spin up atoms can do one of two things: For strong attraction, it can form a molecule with exactly one spin up partner, but for weaker interaction it will spread its attraction and surround itself with a collection of majority atoms. This spin down atom ``dressed'' with a spin up cloud constitutes the spin-polaron. We have observed a striking spectroscopic signature of this quasi-particle for various interaction strengths, a narrow peak in the spin down spectrum that emerges above a broad background. The narrow width signals a long lifetime of the spin-polaron, much longer than the collision rate with spin up atoms, as it must be for a proper quasi-particle. The peak position allows to directly measure the polaron energy. The broad pedestal at high energies reveals physics at short distances and is thus ``molecule-like'': It is exactly matched by the spin up spectra. The comparison with the area under the polaron peak allows to directly obtain the quasi-particle weight Z. We observe a smooth transition from polarons to molecules. At a critical interaction strength of 1/kFa = 0.7, the polaron peak vanishes and spin up and spin down spectra exactly match, signalling the formation of molecules. This is the same critical interaction strength found earlier to separate a normal Fermi mixture from a superfluid molecular Bose-Einstein condensate. The spin-polarons determine the low-temperature phase diagram of imbalanced Fermi mixtures. In principle, polarons can interact with each other and should, at low enough temperatures, form a superfluid of p-wave pairs. We will present a first indication for interactions between polarons.
Quantum criticality of one-dimensional multicomponent Fermi gas with strongly attractive interaction
International Nuclear Information System (INIS)
He, Peng; Jiang, Yuzhu; Guan, Xiwen; He, Jinyu
2015-01-01
Quantum criticality of strongly attractive Fermi gas with SU(3) symmetry in one dimension is studied via the thermodynamic Bethe ansatz (TBA) equations. The phase transitions driven by the chemical potential μ, effective magnetic field H 1 , H 2 (chemical potential biases) are analyzed at the quantum criticality. The phase diagram and critical fields are analytically determined by the TBA equations in the zero temperature limit. High accurate equations of state, scaling functions are also obtained analytically for the strong interacting gases. The dynamic exponent z=2 and correlation length exponent ν=1/2 read off the universal scaling form. It turns out that the quantum criticality of the three-component gases involves a sudden change of density of states of one cluster state, two or three cluster states. In general, this method can be adapted to deal with the quantum criticality of multicomponent Fermi gases with SU(N) symmetry. (paper)
Studies of the strong and electroweak interactions at the Z0 pole
International Nuclear Information System (INIS)
Hildreth, M.D.
1995-03-01
This thesis presents studies of the strong and electroweak forces, two of the fundamental interactions that govern the behavior of matter at high energies. The authors have used the hadronic decays of Z 0 bosons produced with the unique experimental apparatus of the e + e - Linear Collider at the Stanford Linear Accelerator Center (SLAC) and the SLAC Large Detector (SLD) for these measurements. Employing the precision tracking capabilities of the SLD, they isolated samples of Z 0 events containing primarily the decays of the Z 0 to a chosen quark type. With an inclusive selection technique, they have tested the flavor independence of the strong coupling, α s by measuring the rates of multi-jet production in isolated samples of light (uds), c, and b quark events. They find: α s uds /α s all 0.987 ± 0.027(stat) ± 0.022(syst) ± 0.022(theory), α s c /α s all = 1.012 ± 0.104(stat) ± 0.102(syst) ± 0.096(theory), α s b /α s all = 1.026 ± 0.041(stat) ± 0.030(theory), which implies that the strong interaction is independent of quark flavor within the present experimental sensitivity. They have also measured the extent of parity-violation in the Z 0 c bar c coupling, given by the parameter A c 0 , using a sample of fully and partially reconstructed D* and D + meson decays and the longitudinal polarization of the SLC electron beam. This sample of charm quark events was derived with selection techniques based on their kinematic properties and decay topologies. They find A c 0 = 0.73 ± 0.22(stat) ± 0.10(syst). This value is consistent with that expected in the electroweak standard model of particle interactions
Azar, R Julian; Horn, Paul Richard; Sundstrom, Eric Jon; Head-Gordon, Martin
2013-02-28
The problem of describing the energy-lowering associated with polarization of interacting molecules is considered in the overlapping regime for self-consistent field wavefunctions. The existing approach of solving for absolutely localized molecular orbital (ALMO) coefficients that are block-diagonal in the fragments is shown based on formal grounds and practical calculations to often overestimate the strength of polarization effects. A new approach using a minimal basis of polarized orthogonal local MOs (polMOs) is developed as an alternative. The polMO basis is minimal in the sense that one polarization function is provided for each unpolarized orbital that is occupied; such an approach is exact in second-order perturbation theory. Based on formal grounds and practical calculations, the polMO approach is shown to underestimate the strength of polarization effects. In contrast to the ALMO method, however, the polMO approach yields results that are very stable to improvements in the underlying AO basis expansion. Combining the ALMO and polMO approaches allows an estimate of the range of energy-lowering due to polarization. Extensive numerical calculations on the water dimer using a large range of basis sets with Hartree-Fock theory and a variety of different density functionals illustrate the key considerations. Results are also presented for the polarization-dominated Na(+)CH4 complex. Implications for energy decomposition analysis of intermolecular interactions are discussed.
Thermodynamics of strongly interacting system from reparametrized Polyakov-Nambu-Jona-Lasinio model
International Nuclear Information System (INIS)
Bhattacharyya, Abhijit; Ghosh, Sanjay K.; Maity, Soumitra; Raha, Sibaji; Ray, Rajarshi; Saha, Kinkar; Upadhaya, Sudipa
2017-01-01
The Polyakov-Nambu-Jona-Lasinio model has been quite successful in describing various qualitative features of observables for strongly interacting matter, that are measurable in heavy-ion collision experiments. The question still remains on the quantitative uncertainties in the model results. Such an estimation is possible only by contrasting these results with those obtained from rst principles using the lattice QCD framework. Recently a variety of lattice QCD data were reported in the realistic continuum limit. Here we make a first attempt at reparametrizing the model so as to reproduce these lattice data
Atomic wavefunctions probed through strong-field light-matter interaction
Energy Technology Data Exchange (ETDEWEB)
Mairesse, Y; Villeneuve, D M; Corkum, P B; Dudovich, N [Natl Res Council Canada, Ottawa, ON K1A 0R6 (Canada); Shafir, D; Dudovich, N [Weizmann Inst Sci, Dept Phys Complex Syst, IL-76100 Rehovot, (Israel); Mairesse, Y [Univ Bordeaux 1, CELIA, CNRS, UMR 5107, CEA, F-33405 Talence (France)
2009-07-01
Strong-field light-matter interactions can encode the spatial properties of the electronic wavefunctions that contribute to the process. In particular, the broadband harmonic spectra, measured for a series of molecular alignments, can be used to create a tomographic reconstruction of molecular orbitals. Here, we present an extension of the tomography approach to systems that cannot be naturally aligned. We demonstrate this ability by probing the two-dimensional properties of atomic wavefunctions. By manipulating an electron-ion re-collision process, we are able to resolve the symmetry of the atomic wavefunction with high contrast. (authors)
Mishmash, Ryan V.
Experiments on strongly correlated quasi-two-dimensional electronic materials---for example, the high-temperature cuprate superconductors and the putative quantum spin liquids kappa-(BEDT-TTF)2Cu2(CN)3 and EtMe3Sb[Pd(dmit)2]2---routinely reveal highly mysterious quantum behavior which cannot be explained in terms of weakly interacting degrees of freedom. Theoretical progress thus requires the introduction of completely new concepts and machinery beyond the traditional framework of the band theory of solids and its interacting counterpart, Landau's Fermi liquid theory. In full two dimensions, controlled and reliable analytical approaches to such problems are severely lacking, as are numerical simulations of even the simplest of model Hamiltonians due to the infamous fermionic sign problem. Here, we attempt to circumvent some of these difficulties by studying analogous problems in quasi-one dimension. In this lower dimensional setting, theoretical and numerical tractability are on much stronger footing due to the methods of bosonization and the density matrix renormalization group, respectively. Using these techniques, we attack two problems: (1) the Mott transition between a Fermi liquid metal and a quantum spin liquid as potentially directly relevant to the organic compounds kappa-(BEDT-TTF)2Cu 2(CN)3 and EtMe3Sb[Pd(dmit)2] 2 and (2) non-Fermi liquid metals as strongly motivated by the strange metal phase observed in the cuprates. In both cases, we are able to realize highly exotic quantum phases as ground states of reasonable microscopic models. This lends strong credence to respective underlying slave-particle descriptions of the low-energy physics, which are inherently strongly interacting and also unconventional in comparison to weakly interacting alternatives. Finally, working in two dimensions directly, we propose a new slave-particle theory which explains in a universal way many of the intriguing experimental results of the triangular lattice organic spin
Evidence for strong Breit interaction in dielectronic recombination of highly charged heavy ions.
Nakamura, Nobuyuki; Kavanagh, Anthony P; Watanabe, Hirofumi; Sakaue, Hiroyuki A; Li, Yueming; Kato, Daiji; Currell, Fred J; Ohtani, Shunsuke
2008-02-22
Resonant strengths have been measured for dielectronic recombination of Li-like iodine, holmium, and bismuth using an electron beam ion trap. By observing the atomic number dependence of the state-resolved resonant strength, clear experimental evidence has been obtained that the importance of the generalized Breit interaction (GBI) effect on dielectronic recombination increases as the atomic number increases. In particular, it has been shown that the GBI effect is exceptionally strong for the recombination through the resonant state [1s2s(2)2p(1/2)](1).
Volkov basis for simulation of interaction of strong laser pulses and solids
Kidd, Daniel; Covington, Cody; Li, Yonghui; Varga, Kálmán
2018-01-01
An efficient and accurate basis comprised of Volkov states is implemented and tested for time-dependent simulations of interactions between strong laser pulses and crystalline solids. The Volkov states are eigenstates of the free electron Hamiltonian in an electromagnetic field and analytically represent the rapidly oscillating time-dependence of the orbitals, allowing significantly faster time propagation than conventional approaches. The Volkov approach can be readily implemented in plane-wave codes by multiplying the potential energy matrix elements with a simple time-dependent phase factor.
Residual correlation in two-proton interferometry from Λ-proton strong interactions
International Nuclear Information System (INIS)
Wang, Fuqiang
1999-01-01
We investigate the residual effect of Λp strong interactions in pp correlations with one proton from Λ decays. It is found that the residual correlation is about 10% of the Λp correlation strength, and has a broad distribution centered around q≅40 MeV/c. The residual correlation cannot explain the observed structure on the tail of the recently measured pp correlation function in central Pb+Pb collisions by NA49 at the Super Proton Synchrotron. (c) 1999 The American Physical Society
Partial widths of boson resonances in the quark-gluon model of strong interactions
International Nuclear Information System (INIS)
Kaidalov, A.B.; Volkovitsky, P.E.
1981-01-01
The quark-gluon model of strong interactions based on the topological expansion and the string model ib used for the calculation of the partial widths of boson resonances in the channels with two pseudoscalar mesons. The partial widths of mesons with arbitrary spins lying on the vector and tensor Regge trajectories are expressed in terms of the only rho-meson width. The violation of SU(3) symmetry increases with the growth of the spin of the resonance. The theoretical predictions are in a good agreement with experimental data [ru
Ovchinnikov, Sergey G.; Makarov, Ilya A.; Kozlov, Peter A.
2017-03-01
In this work dependences of the electron band structure and spectral function in the HTSC cuprates on magnitude of electron-phonon interaction (EPI) and temperature are investigated. We use three-band p-d model with diagonal and offdiagonal EPI with breathing and buckling phonon mode in the frameworks of polaronic version of the generalized tight binding (GTB) method. The polaronic quasiparticle excitation in the system with EPI within this approach is formed by a hybridization of the local multiphonon Franck-Condon excitations with lower and upper Hubbard bands. Increasing EPI leads to transfer of spectral weight to high-energy multiphonon excitations and broadening of the spectral function. Temperature effects are taken into account by occupation numbers of local excited polaronic states and variations in the magnitude of spin-spin correlation functions. Increasing the temperature results in band structure reconstruction, spectral weight redistribution, broadening of the spectral function peak at the top of the valence band and the decreasing of the peak intensity. The effect of EPI with two phonon modes on the polaron spectral function is discussed.
Mechanism for thermal relic dark matter of strongly interacting massive particles.
Hochberg, Yonit; Kuflik, Eric; Volansky, Tomer; Wacker, Jay G
2014-10-24
We present a new paradigm for achieving thermal relic dark matter. The mechanism arises when a nearly secluded dark sector is thermalized with the standard model after reheating. The freeze-out process is a number-changing 3→2 annihilation of strongly interacting massive particles (SIMPs) in the dark sector, and points to sub-GeV dark matter. The couplings to the visible sector, necessary for maintaining thermal equilibrium with the standard model, imply measurable signals that will allow coverage of a significant part of the parameter space with future indirect- and direct-detection experiments and via direct production of dark matter at colliders. Moreover, 3→2 annihilations typically predict sizable 2→2 self-interactions which naturally address the "core versus cusp" and "too-big-to-fail" small-scale structure formation problems.
Introduction to unified theories of weak, electromagnetic and strong interactions - SU(5)
International Nuclear Information System (INIS)
Billoire, Alain; Morel, Andre.
1980-11-01
These notes correspond to a series of lectures given at Salay during winter 1979-1980. They are meant to be an introduction to the so-called grand unified theories of weak, electromagnetic and strong interactions. In a first part, we recall in a very elementary way the standard SU(2) model of electroweak interactions, putting the emphasis on the questions which are left open by this model and which unified theories help to answer. In part II, we explain in a systematic way how unified theories can be constructed, and develop the SU(5) model in great detail. Other models, like SO(10) and E 6 , are not presented, because SU(5) is the simplest one and has been subject to the deepest investigations up to now. Also it appears that most concepts and general results are not specific to any particular symmetry group [fr
International Nuclear Information System (INIS)
Basini, G.
2003-01-01
Asymptotic freedom, as a natural result of a theory based on a general approach, derived by a new interpretation of phenomena like the EPR paradox, the black-hole formation and the absence of primary cosmic antimatter is presented. In this approach, conservation laws are considered always and absolutely valid, leading to the possibility of topology changes, and recovering the mutual influence between fundamental forces. Moreover, a new consideration of time arrows leads to asymptotic freedom as a necessary consequence. In fact, asymptotic freedom of strong interactions seems to be a feature common also to gravitational interaction, if induced-gravity theories (t → ∞) are taken into account and a symmetric-time dynamics is recovered in the light of a general conservation principle. (authors)
Energy Technology Data Exchange (ETDEWEB)
Basini, G. [Istituto Nazionale di Fisica Nucleare, Frascati (Italy). Lab. Nazionale di Frascati; Capozziello, S. [E.R. Caianiello, Dipt. di Fisica, Roma (Italy); Istituto Nazionale di Fisica Nucleare, Sezione di Napoli, Universita di Salerno, Boronissi, SA (Italy)
2003-09-01
Asymptotic freedom, as a natural result of a theory based on a general approach, derived by a new interpretation of phenomena like the EPR paradox, the black-hole formation and the absence of primary cosmic antimatter is presented. In this approach, conservation laws are considered always and absolutely valid, leading to the possibility of topology changes, and recovering the mutual influence between fundamental forces. Moreover, a new consideration of time arrows leads to asymptotic freedom as a necessary consequence. In fact, asymptotic freedom of strong interactions seems to be a feature common also to gravitational interaction, if induced-gravity theories (t {yields} {infinity}) are taken into account and a symmetric-time dynamics is recovered in the light of a general conservation principle. (authors)
Quasiparticle Energy in a Strongly Interacting Homogeneous Bose-Einstein Condensate.
Lopes, Raphael; Eigen, Christoph; Barker, Adam; Viebahn, Konrad G H; Robert-de-Saint-Vincent, Martin; Navon, Nir; Hadzibabic, Zoran; Smith, Robert P
2017-05-26
Using two-photon Bragg spectroscopy, we study the energy of particlelike excitations in a strongly interacting homogeneous Bose-Einstein condensate, and observe dramatic deviations from Bogoliubov theory. In particular, at large scattering length a the shift of the excitation resonance from the free-particle energy changes sign from positive to negative. For an excitation with wave number q, this sign change occurs at a≈4/(πq), in agreement with the Feynman energy relation and the static structure factor expressed in terms of the two-body contact. For a≳3/q we also see a breakdown of this theory, and better agreement with calculations based on the Wilson operator product expansion. Neither theory explains our observations across all interaction regimes, inviting further theoretical efforts.
Many-body Anderson localization of strongly interacting bosons in random lattices
International Nuclear Information System (INIS)
Katzer, Roman
2015-05-01
In the present work, we investigate the problem of many-body localization of strongly interacting bosons in random lattices within the disordered Bose-Hubbard model. This involves treating both the local Mott-Hubbard physics as well as the non-local quantum interference processes, which give rise to the phenomenon of Anderson localization, within the same theory. In order to determine the interaction induced transition to the Mott insulator phase, it is necessary to treat the local particle interaction exactly. Therefore, here we use a mean-field approach that approximates only the kinetic term of the Hamiltonian. This way, the full problem of interacting bosons on a random lattice is reduced to a local problem of a single site coupled to a particle bath, which has to be solved self-consistently. In accordance to previous works, we find that a finite disorder width leads to a reduced size of the Mott insulating regions. The transition from the superfluid phase to the Bose glass phase is driven by the non-local effect of Anderson localization. In order to describe this transition, one needs to work within a theory that is non-local as well. Therefore, here we introduce a new approach to the problem. Based on the results for the local excitation spectrum obtained within the mean-field theory, we reduce the full, interacting model to an effective, non-interacting model by applying a truncation scheme to the Hilbert space. Evaluating the long-ranged current density within this approximation, we identify the transition from the Bose glass to the superfluid phase with the Anderson transition of the effective model. Resolving this transition using the self-consistent theory of localization, we obtain the full phase diagram of the disordered Bose-Hubbard model in the regime of strong interaction and larger disorder. In accordance to the theorem of inclusions, we find that the Mott insulator and the superfluid phase are always separated by the compressible, but insulating
Effective model with strong Kitaev interactions for α -RuCl3
Suzuki, Takafumi; Suga, Sei-ichiro
2018-04-01
We use an exact numerical diagonalization method to calculate the dynamical spin structure factors of three ab initio models and one ab initio guided model for a honeycomb-lattice magnet α -RuCl3 . We also use thermal pure quantum states to calculate the temperature dependence of the heat capacity, the nearest-neighbor spin-spin correlation function, and the static spin structure factor. From the results obtained from these four effective models, we find that, even when the magnetic order is stabilized at low temperature, the intensity at the Γ point in the dynamical spin structure factors increases with increasing nearest-neighbor spin correlation. In addition, we find that the four models fail to explain heat-capacity measurements whereas two of the four models succeed in explaining inelastic-neutron-scattering experiments. In the four models, when temperature decreases, the heat capacity shows a prominent peak at a high temperature where the nearest-neighbor spin-spin correlation function increases. However, the peak temperature in heat capacity is too low in comparison with that observed experimentally. To address these discrepancies, we propose an effective model that includes strong ferromagnetic Kitaev coupling, and we show that this model quantitatively reproduces both inelastic-neutron-scattering experiments and heat-capacity measurements. To further examine the adequacy of the proposed model, we calculate the field dependence of the polarized terahertz spectra, which reproduces the experimental results: the spin-gapped excitation survives up to an onset field where the magnetic order disappears and the response in the high-field region is almost linear. Based on these numerical results, we argue that the low-energy magnetic excitation in α -RuCl3 is mainly characterized by interactions such as off-diagonal interactions and weak Heisenberg interactions between nearest-neighbor pairs, rather than by the strong Kitaev interactions.
Kinetics of DNA tile dimerization.
Jiang, Shuoxing; Yan, Hao; Liu, Yan
2014-06-24
Investigating how individual molecular components interact with one another within DNA nanoarchitectures, both in terms of their spatial and temporal interactions, is fundamentally important for a better understanding of their physical behaviors. This will provide researchers with valuable insight for designing more complex higher-order structures that can be assembled more efficiently. In this report, we examined several spatial factors that affect the kinetics of bivalent, double-helical (DH) tile dimerization, including the orientation and number of sticky ends (SEs), the flexibility of the double helical domains, and the size of the tiles. The rate constants we obtained confirm our hypothesis that increased nucleation opportunities and well-aligned SEs accelerate tile-tile dimerization. Increased flexibility in the tiles causes slower dimerization rates, an effect that can be reversed by introducing restrictions to the tile flexibility. The higher dimerization rates of more rigid tiles results from the opposing effects of higher activation energies and higher pre-exponential factors from the Arrhenius equation, where the pre-exponential factor dominates. We believe that the results presented here will assist in improved implementation of DNA tile based algorithmic self-assembly, DNA based molecular robotics, and other specific nucleic acid systems, and will provide guidance to design and assembly processes to improve overall yield and efficiency.
Cheng, Sara Y; Chou, George; Buie, Creighton; Vaughn, Mark W; Compton, Campbell; Cheng, Kwan H
2016-03-01
We used molecular dynamics simulations to explore the effects of asymmetric transbilayer distribution of anionic phosphatidylserine (PS) lipids on the structure of a protein on the membrane surface and subsequent protein-lipid interactions. Our simulation systems consisted of an amyloidogenic, beta-sheet rich dimeric protein (D42) absorbed to the phosphatidylcholine (PC) leaflet, or protein-contact PC leaflet, of two membrane systems: a single-component PC bilayer and double PC/PS bilayers. The latter comprised of a stable but asymmetric transbilayer distribution of PS in the presence of counterions, with a 1-component PC leaflet coupled to a 1-component PS leaflet in each bilayer. The maximally asymmetric PC/PS bilayer had a non-zero transmembrane potential (TMP) difference and higher lipid order packing, whereas the symmetric PC bilayer had a zero TMP difference and lower lipid order packing under physiologically relevant conditions. Analysis of the adsorbed protein structures revealed weaker protein binding, more folding in the N-terminal domain, more aggregation of the N- and C-terminal domains and larger tilt angle of D42 on the PC leaflet surface of the PC/PS bilayer versus the PC bilayer. Also, analysis of protein-induced membrane structural disruption revealed more localized bilayer thinning in the PC/PS versus PC bilayer. Although the electric field profile in the non-protein-contact PS leaflet of the PC/PS bilayer differed significantly from that in the non-protein-contact PC leaflet of the PC bilayer, no significant difference in the electric field profile in the protein-contact PC leaflet of either bilayer was evident. We speculate that lipid packing has a larger effect on the surface adsorbed protein structure than the electric field for a maximally asymmetric PC/PS bilayer. Our results support the mechanism that the higher lipid packing in a lipid leaflet promotes stronger protein-protein but weaker protein-lipid interactions for a dimeric protein on
Sigma- versus Pi-Dimerization Modes of Triangulene.
Mou, Zhongyu; Kertesz, Miklos
2018-04-20
We show that the diradicaloid triangulene, a graphene nano-flake molecule, can aggregate in a variety of dimerization modes. We found by density functional theory modeling a number of triangulene dimers including six doubly bonded σ-dimers in addition to the previously reported six pancake bonded π-dimer isomers. The σ-dimers display a wide range of stabilities: the interaction energy of the most stable σ-dimer is -25.17 kcal mol -1 . Besides the doubly bonded σ-dimers with closed shell ground states, we also found an open-shell singly σ-bonded diradicaloid dimer. We found an interesting isomerization route between a doubly bonded σ-dimer, a singly bonded σ-dimer with a low-lying triplet state and two π-bonded dimers with low-lying quintet states. Derivatives of triangulene, trioxo-triangulenes (TOTs) have been previously characterized experimentally. Here, we show the reasons why so far only the π-dimer but not the σ-dimer was experimentally observed for all TOTs. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.
Structural insights into the intertwined dimer of fyn SH2.
Huculeci, Radu; Garcia-Pino, Abel; Buts, Lieven; Lenaerts, Tom; van Nuland, Nico
2015-12-01
Src homology 2 domains are interaction modules dedicated to the recognition of phosphotyrosine sites incorporated in numerous proteins found in intracellular signaling pathways. Here we provide for the first time structural insight into the dimerization of Fyn SH2 both in solution and in crystalline conditions, providing novel crystal structures of both the dimer and peptide-bound structures of Fyn SH2. Using nuclear magnetic resonance chemical shift analysis, we show how the peptide is able to eradicate the dimerization, leading to monomeric SH2 in its bound state. Furthermore, we show that Fyn SH2's dimer form differs from other SH2 dimers reported earlier. Interestingly, the Fyn dimer can be used to construct a completed dimer model of Fyn without any steric clashes. Together these results extend our understanding of SH2 dimerization, giving structural details, on one hand, and suggesting a possible physiological relevance of such behavior, on the other hand. © 2015 The Protein Society.
Simulation of Quantum Many-Body Dynamics for Generic Strongly-Interacting Systems
Meyer, Gregory; Machado, Francisco; Yao, Norman
2017-04-01
Recent experimental advances have enabled the bottom-up assembly of complex, strongly interacting quantum many-body systems from individual atoms, ions, molecules and photons. These advances open the door to studying dynamics in isolated quantum systems as well as the possibility of realizing novel out-of-equilibrium phases of matter. Numerical studies provide insight into these systems; however, computational time and memory usage limit common numerical methods such as exact diagonalization to relatively small Hilbert spaces of dimension 215 . Here we present progress toward a new software package for dynamical time evolution of large generic quantum systems on massively parallel computing architectures. By projecting large sparse Hamiltonians into a much smaller Krylov subspace, we are able to compute the evolution of strongly interacting systems with Hilbert space dimension nearing 230. We discuss and benchmark different design implementations, such as matrix-free methods and GPU based calculations, using both pre-thermal time crystals and the Sachdev-Ye-Kitaev model as examples. We also include a simple symbolic language to describe generic Hamiltonians, allowing simulation of diverse quantum systems without any modification of the underlying C and Fortran code.
International Nuclear Information System (INIS)
Recami, E.; Tonin Zanchin, V.; Martinez, J.M.
1986-01-01
A unified geometrical approach to strong and gravitational interactions has been recently proposed, based on the classical methods of General Relativity. According to it, hadrons can be regarded as black-hole type solutions of new field equations describing two tensorial metric-field (the ordinary gravitational field, and the strong one). In this paper, we first seize the opportunity for an improved exposition of some elements of the theory relevant to our present scope. Secondly, by extending the Bekenstein-Hawking thermodynamics to the above mentioned strong black-holes (SBH), it is shown: 1) that SBH thermodynamics seems to require a new expansion of our cosmos after its Big Crunch (i.e. that a recontraction of our cosmos has to be followed by a new creation); 2) that a collapsing star with mass M approximately in the range 3 to 5 solar masses, once reached the neutron-star density, could re-explode tending to form a (radiating) object with a diameter of the order of 1 light-day: thus failing to create a gravitational black-hole
Kinoshita, Ryo; Ishima, Yu; Chuang, Victor T G; Nakamura, Hideaki; Fang, Jun; Watanabe, Hiroshi; Shimizu, Taro; Okuhira, Keiichiro; Ishida, Tatsuhiro; Maeda, Hiroshi; Otagiri, Masaki; Maruyama, Toru
2017-09-01
In the latest trend of anticancer chemotherapy research, there were many macromolecular anticancer drugs developed based on enhanced permeability and retention (EPR) effect, such as albumin bound paclitaxel nanoparticle (nab- PTX, also called Abraxane ® ). However, cancers with low vascular permeability posed a challenge for these EPR based therapeutic systems. Augmenting the intrinsic EPR effect with an intrinsic vascular modulator such as nitric oxide (NO) could be a promising strategy. S-nitrosated human serum albumin dimer (SNO-HSA Dimer) shown promising activity previously was evaluated for the synergistic effect when used as a pretreatment agent in nab-PTX therapy against various tumor models. In the high vascular permeability C26 murine colon cancer subcutaneous inoculation model, SNO-HSA Dimer enhanced tumor selectivity of nab-PTX, and attenuated myelosuppression. SNO-HSA Dimer also augmented the tumor growth inhibition of nab-PTX in low vascular permeability B16 murine melanoma subcutaneous inoculation model. Furthermore, nab-PTX therapy combined with SNO-HSA Dimer showed higher antitumor activity and improved survival rate of SUIT2 human pancreatic cancer orthotopic model. In conclusion, SNO-HSA Dimer could enhance the therapeutic effect of nab-PTX even in low vascular permeability or intractable pancreatic cancers. The possible underlying mechanisms of action of SNO-HSA Dimer were discussed. Copyright © 2017 Elsevier Ltd. All rights reserved.
Tubman, Norm; Whaley, Birgitta
The development of exponential scaling methods has seen great progress in tackling larger systems than previously thought possible. One such technique, full configuration interaction quantum Monte Carlo, allows exact diagonalization through stochastically sampling of determinants. The method derives its utility from the information in the matrix elements of the Hamiltonian, together with a stochastic projected wave function, which are used to explore the important parts of Hilbert space. However, a stochastic representation of the wave function is not required to search Hilbert space efficiently and new deterministic approaches have recently been shown to efficiently find the important parts of determinant space. We shall discuss the technique of Adaptive Sampling Configuration Interaction (ASCI) and the related heat-bath Configuration Interaction approach for ground state and excited state simulations. We will present several applications for strongly correlated Hamiltonians. This work was supported through the Scientific Discovery through Advanced Computing (SciDAC) program funded by the U.S. Department of Energy, Office of Science, Advanced Scientific Computing Research and Basic Energy Sciences.
Investigation of the hydrated 7-hydroxy-4-methylcoumarin dimer by combined IR/UV spectroscopy
International Nuclear Information System (INIS)
Stamm, A.; Schwing, K.; Gerhards, M.
2014-01-01
The first molecular beam investigations on a coumarin dimer and clusters of a coumarin dimer with water both in the neutral (S 0 ) and cationic (D 0 ) electronic ground state are performed. The structure and structural changes due to ionization of the isolated 7-hydroxy-4-methylcoumarin dimer (7H4MC) 2 as well as its mono- and dihydrate (7H4MC) 2 (H 2 O) 1-2 are analyzed by applying combined IR/UV spectroscopy compared with density functional theory calculations. In case of the neutral dimer of 7H4MC a doubly hydrogen-bonded structure is formed. This doubly hydrogen-bonded arrangement opens to a singly hydrogen-bonded structure in the ion presenting a rearrangement reaction within an isolated dimer. By attaching one or two water molecules to the neutral 7H4MC dimer water is inserted into the hydrogen bonds. In contrast to the non-hydrated species this general binding motif with water in a bridging function does not change via ionization but especially for the dihydrate the spatial arrangement of the two 7H4MC units changes strengthening the interaction between the aromatic chromophores. The presented analyses illustrate the strong dependence of binding motifs as a function of successive hydration and charge including a rearrangement reaction
Studies of the strong and electroweak interactions at the Z^{0} pole
Energy Technology Data Exchange (ETDEWEB)
Hildreth, Michael Douglas [Stanford Univ., CA (United States)
1995-03-01
This thesis presents studies of the strong and electroweak forces, two of the fundamental interactions that govern the behavior of matter at high energies. The authors have used the hadronic decays of Z^{0} bosons produced with the unique experimental apparatus of the e^{+}e^{-} Linear Collider at the Stanford Linear Accelerator Center (SLAC) and the SLAC Large Detector (SLD) for these measurements. Employing the precision tracking capabilities of the SLD, they isolated samples of Z^{0} events containing primarily the decays of the Z^{0} to a chosen quark type. With an inclusive selection technique, they have tested the flavor independence of the strong coupling, α_{s} by measuring the rates of multi-jet production in isolated samples of light (uds), c, and b quark events. They find: α$s\\atop{uds}$/α$s\\atop{all}$ 0.987 ± 0.027(stat) ± 0.022(syst) ± 0.022(theory), α$c\\atop{s}$/α$all\\atop{s}$ = 1.012 ± 0.104(stat) ± 0.102(syst) ± 0.096(theory), α$b\\atop{s}$/α$all\\atop{s}$ = 1.026 {+-} 0.041(stat) ± 0.030(theory), which implies that the strong interaction is independent of quark flavor within the present experimental sensitivity. They have also measured the extent of parity-violation in the Z^{0} c$\\bar{c}$ coupling, given by the parameter A $0\\atop{c}$, using a sample of fully and partially reconstructed D* and D^{+} meson decays and the longitudinal polarization of the SLC electron beam. This sample of charm quark events was derived with selection techniques based on their kinematic properties and decay topologies. They find A$0\\atop{c}$ = 0.73 ± 0.22(stat) ± 0.10(syst). This value is consistent with that expected in the electroweak standard model of particle interactions.
Effects of strong and electromagnetic correlations on neutrino interactions in dense matter
International Nuclear Information System (INIS)
Reddy, S.; Prakash, M.; Lattimer, J.M.; Reddy, S.; Pons, J.A.
1999-01-01
An extensive study of the effects of correlations on both charged and neutral current weak interaction rates in dense matter is performed. Both strong and electromagnetic correlations are considered. The propagation of particle-hole interactions in the medium plays an important role in determining the neutrino mean free paths. The effects due to Pauli blocking and density, spin, and isospin correlations in the medium significantly reduce the neutrino cross sections. As a result of the lack of experimental information at high density, these correlations are necessarily model dependent. For example, spin correlations in nonrelativistic models are found to lead to larger suppressions of neutrino cross sections compared to those of relativistic models. This is due to the tendency of the nonrelativistic models to develop spin instabilities. Notwithstanding the above caveats, and the differences between nonrelativistic and relativistic approaches such as the spin- and isospin-dependent interactions and the nucleon effective masses, suppressions of order 2 - 3, relative to the case in which correlations are ignored, are obtained. Neutrino interactions in dense matter are especially important for supernova and early neutron star evolution calculations. The effects of correlations for protoneutron star evolution are calculated. Large effects on the internal thermodynamic properties of protoneutron stars, such as the temperature, are found. These translate into significant early enhancements in the emitted neutrino energies and fluxes, especially after a few seconds. At late times, beyond about 10 s, the emitted neutrino fluxes decrease more rapidly compared to simulations without the effects of correlations, due to the more rapid onset of neutrino transparency in the protoneutron star. copyright 1999 The American Physical Society
On the diffusion and self-trapping of surface dimers
Kappus, W.
1982-03-01
The theory of elastic interactions between surface atoms which are caused by substrate strains is applied to the interaction of dimers on the (211) surface of tungsten. From the comparison of theoretical and experimental interactions which were derived from the diffusion behaviour of dimers, conclusions are drawn on the nature of the adatom-substrate bond.
DEFF Research Database (Denmark)
Loft, Niels Jakob Søe; Kristensen, Lasse Bjørn; Thomsen, Anders
2016-01-01
We consider a one-dimensional system of particles with strong zero-range interactions. This system can be mapped onto a spin chain of the Heisenberg type with exchange coefficients that depend on the external trap. In this paper, we present an algorithm that can be used to compute these exchange...... coefficients. We introduce an open source code CONAN (Coefficients of One-dimensional N-Atom Networks) which is based on this algorithm. CONAN works with arbitrary external potentials and we have tested its reliability for system sizes up to around 35 particles. As illustrative examples, we consider a harmonic...... trap and a box trap with a superimposed asymmetric tilted potential. For these examples, the computation time typically scales with the number of particles as O(N3.5±0.4). Computation times are around 10 s for N=10 particles and less than 10 min for N=20 particles....
Fluctuation instability of the Dirac Sea in quark models of strong interactions
Zinovjev, G. M.; Molodtsov, S. V.
2016-03-01
A number of exactly integrable (quark) models of quantum field theory that feature an infinite correlation length are considered. An instability of the standard vacuum quark ensemble, a Dirac sea (in spacetimes of dimension higher than three), is highlighted. It is due to a strong ground-state degeneracy, which, in turn, stems from a special character of the energy distribution. In the case where the momentumcutoff parameter tends to infinity, this distribution becomes infinitely narrow and leads to large (unlimited) fluctuations. A comparison of the results for various vacuum ensembles, including a Dirac sea, a neutral ensemble, a color superconductor, and a Bardeen-Cooper-Schrieffer (BCS) state, was performed. In the presence of color quark interaction, a BCS state is unambiguously chosen as the ground state of the quark ensemble.
Fluctuation instability of the Dirac Sea in quark models of strong interactions
International Nuclear Information System (INIS)
Zinovjev, G. M.; Molodtsov, S. V.
2016-01-01
A number of exactly integrable (quark) models of quantum field theory that feature an infinite correlation length are considered. An instability of the standard vacuum quark ensemble, a Dirac sea (in spacetimes of dimension higher than three), is highlighted. It is due to a strong ground-state degeneracy, which, in turn, stems from a special character of the energy distribution. In the case where the momentumcutoff parameter tends to infinity, this distribution becomes infinitely narrow and leads to large (unlimited) fluctuations. A comparison of the results for various vacuum ensembles, including a Dirac sea, a neutral ensemble, a color superconductor, and a Bardeen–Cooper–Schrieffer (BCS) state, was performed. In the presence of color quark interaction, a BCS state is unambiguously chosen as the ground state of the quark ensemble.
Fluctuation instability of the Dirac Sea in quark models of strong interactions
Energy Technology Data Exchange (ETDEWEB)
Zinovjev, G. M., E-mail: Gennady.Zinovjev@cern.ch [National Academy of Sciences of Ukraine, Bogolyubov Institute for Theoretical Physics (Ukraine); Molodtsov, S. V. [Joint Institute for Nuclear Research (Russian Federation)
2016-03-15
A number of exactly integrable (quark) models of quantum field theory that feature an infinite correlation length are considered. An instability of the standard vacuum quark ensemble, a Dirac sea (in spacetimes of dimension higher than three), is highlighted. It is due to a strong ground-state degeneracy, which, in turn, stems from a special character of the energy distribution. In the case where the momentumcutoff parameter tends to infinity, this distribution becomes infinitely narrow and leads to large (unlimited) fluctuations. A comparison of the results for various vacuum ensembles, including a Dirac sea, a neutral ensemble, a color superconductor, and a Bardeen–Cooper–Schrieffer (BCS) state, was performed. In the presence of color quark interaction, a BCS state is unambiguously chosen as the ground state of the quark ensemble.
Electron-muon correlation as a new probe of strongly interacting quark-gluon plasma
International Nuclear Information System (INIS)
Akamatsu, Yukinao; Hatsuda, Tetsuo; Hirano, Tetsufumi
2009-01-01
As a new and clean probe to the strongly interacting quark-gluon plasma (sQGP), we propose an azimuthal correlation of an electron and a muon that originate from the semileptonic decay of charm and bottom quarks. By solving the Langevin equation for the heavy quarks under the hydrodynamic evolution of the hot plasma, we show that substantial quenching of the away-side peak in the electron-muon correlation can be seen if the sQGP drag force acting on heavy quarks is large enough as suggested from the gauge/gravity correspondence. The effect could be detected in high-energy heavy ion collisions at the Relativistic Heavy Ion Collider and the Large Hadron Collider.
Thermal dark matter co-annihilating with a strongly interacting scalar
Biondini, S.; Laine, M.
2018-04-01
Recently many investigations have considered Majorana dark matter co-annihilating with bound states formed by a strongly interacting scalar field. However only the gluon radiation contribution to bound state formation and dissociation, which at high temperatures is subleading to soft 2 → 2 scatterings, has been included. Making use of a non-relativistic effective theory framework and solving a plasma-modified Schrödinger equation, we address the effect of soft 2 → 2 scatterings as well as the thermal dissociation of bound states. We argue that the mass splitting between the Majorana and scalar field has in general both a lower and an upper bound, and that the dark matter mass scale can be pushed at least up to 5…6TeV.
Phase transitions, nonequilibrium dynamics, and critical behavior of strongly interacting systems
International Nuclear Information System (INIS)
Mottola, E.; Bhattacharya, T.; Cooper, F.
1998-01-01
This is the final report of a three-year, Laboratory Directed Research and Development project at Los Alamos National Laboratory. In this effort, large-scale simulations of strongly interacting systems were performed and a variety of approaches to the nonequilibrium dynamics of phase transitions and critical behavior were investigated. Focus areas included (1) the finite-temperature quantum chromodynamics phase transition and nonequilibrium dynamics of a new phase of matter (the quark-gluon plasma) above the critical temperature, (2) nonequilibrium dynamics of a quantum fields using mean field theory, and (3) stochastic classical field theoretic models with applications to spinodal decomposition and structural phase transitions in a variety of systems, such as spin chains and shape memory alloys
Phase transitions, nonequilibrium dynamics, and critical behavior of strongly interacting systems
Energy Technology Data Exchange (ETDEWEB)
Mottola, E.; Bhattacharya, T.; Cooper, F. [and others
1998-12-31
This is the final report of a three-year, Laboratory Directed Research and Development project at Los Alamos National Laboratory. In this effort, large-scale simulations of strongly interacting systems were performed and a variety of approaches to the nonequilibrium dynamics of phase transitions and critical behavior were investigated. Focus areas included (1) the finite-temperature quantum chromodynamics phase transition and nonequilibrium dynamics of a new phase of matter (the quark-gluon plasma) above the critical temperature, (2) nonequilibrium dynamics of a quantum fields using mean field theory, and (3) stochastic classical field theoretic models with applications to spinodal decomposition and structural phase transitions in a variety of systems, such as spin chains and shape memory alloys.
Directory of Open Access Journals (Sweden)
Szymański Maciej
2015-01-01
Full Text Available In this article, the analysis of baryon-antibaryon femtoscopic correlations is presented. In particular, it is shown that taking into account residual correlations is crucial for the description of pΛ¯$\\bar \\Lambda $ and p̄Λ correlation functions measured by the STAR experiment in Au–Au collisions at the centre-of-mass energy per nucleon pair √sNN = 200 GeV. This approach enables to obtain pΛ¯$\\bar \\Lambda $ (p̄Λ source size consistent with the sizes extracted from correlations in pΛ (p̄Λ¯$\\bar \\Lambda $ and lighter pair systems as well as with model predictions. Moreover, with this analysis it is possible to derive the unknown parameters of the strong interaction potential for baryon-antibaryon pairs under several assumptions.
Particle-Hole Character of the Higgs and Goldstone Modes in Strongly Interacting Lattice Bosons
Di Liberto, M.; Recati, A.; Trivedi, N.; Carusotto, I.; Menotti, C.
2018-02-01
We study the low-energy excitations of the Bose-Hubbard model in the strongly interacting superfluid phase using a Gutzwiller approach. We extract the single-particle and single-hole excitation amplitudes for each mode and report emergent mode-dependent particle-hole symmetry on specific arc-shaped lines in the phase diagram connecting the well-known Lorentz-invariant limits of the Bose-Hubbard model. By tracking the in-phase particle-hole symmetric oscillations of the order parameter, we provide an answer to the long-standing question about the fate of the pure amplitude Higgs mode away from the integer-density critical point. Furthermore, we point out that out-of-phase symmetric oscillations in the gapless Goldstone mode are responsible for a full suppression of the condensate density oscillations. Possible detection protocols are also discussed.
Mutations in the DNA-binding domain of NR2E3 affect in vivo dimerization and interaction with CRX.
Directory of Open Access Journals (Sweden)
Raphael Roduit
Full Text Available BACKGROUND: NR2E3 (PNR is an orphan nuclear receptor essential for proper photoreceptor determination and differentiation. In humans, mutations in NR2E3 have been associated with the recessively inherited enhanced short wavelength sensitive (S- cone syndrome (ESCS and, more recently, with autosomal dominant retinitis pigmentosa (adRP. NR2E3 acts as a suppressor of the cone generation program in late mitotic retinal progenitor cells. In adult rod photoreceptors, NR2E3 represses cone-specific gene expression and acts in concert with the transcription factors CRX and NRL to activate rod-specific genes. NR2E3 and CRX have been shown to physically interact in vitro through their respective DNA-binding domains (DBD. The DBD also contributes to homo- and heterodimerization of nuclear receptors. METHODOLOGY/PRINCIPAL FINDINGS: We analyzed NR2E3 homodimerization and NR2E3/CRX complex formation in an in vivo situation by Bioluminescence Resonance Energy Transfer (BRET(2. NR2E3 wild-type protein formed homodimers in transiently transfected HEK293T cells. NR2E3 homodimerization was impaired in presence of disease-causing mutations in the DBD, except for the p.R76Q and p.R104W mutant proteins. Strikingly, the adRP-linked p.G56R mutant protein interacted with CRX with a similar efficiency to that of NR2E3 wild-type and p.R311Q proteins. In contrast, all other NR2E3 DBD-mutant proteins did not interact with CRX. The p.G56R mutant protein was also more effective in abolishing the potentiation of rhodospin gene transactivation by the NR2E3 wild-type protein. In addition, the p.G56R mutant enhanced the transrepression of the M- and S-opsin promoter, while all other NR2E3 DBD-mutants did not. CONCLUSIONS/SIGNIFICANCE: These results suggest different disease mechanisms in adRP- and ESCS-patients carrying NR2E3 mutations. Titration of CRX by the p.G56R mutant protein acting as a repressor in trans may account for the severe clinical phenotype in adRP patients.
New precision era of experiments on strong interaction with strangeness at DAFNE/LNF-INFN
Directory of Open Access Journals (Sweden)
Ishiwatari T.
2014-03-01
Full Text Available The strong-interaction shifts and widths of kaonic hydrogen, deuterium, 3He, and 4He were measured in the SIDDHARTA experiment. The most precise values of the shift and width of the kaonic hydrogen 1s state were determined to be ϵ1s = −283 ± 36(stat±6(syst eV and Γ1s = 541±89(stat±22(syst eV. The upper limit of the kaonic deuterium Kα yield was found to be ≤ 0.39%. In addition, the shifts and widths of the kaonic 3He and 4He 2p states were determined to be ϵ2p(3He = −2 ± 2(stat ± 4(syst eV and Γ2p(3He = 6 ± 6(stat ± 7(syst eV; ϵ2p(4He = +5 ± 3(stat ± 4(syst eV and Γ2p(4He = 14 ± 8(stat ± 5(syst eV. These values are important for the constraints of the low-energy K¯N$\\bar KN$ interaction in theoretical approaches.
Debecker, Sara; Dinh, Khuong V; Stoks, Robby
2017-02-21
As contaminants are often more toxic at higher temperatures, predicting their impact under global warming remains a key challenge for ecological risk assessment. Ignoring delayed effects, synergistic interactions between contaminants and warming, and differences in sensitivity across species' ranges could lead to an important underestimation of the risks. We addressed all three mechanisms by studying effects of larval exposure to zinc and warming before, during, and after metamorphosis in Ischnura elegans damselflies from high- and low-latitude populations. By integrating these mechanisms into a single study, we could identify two novel patterns. First, during exposure zinc did not affect survival, whereas it induced mild to moderate postexposure mortality in the larval stage and at metamorphosis, and very strongly reduced adult lifespan. This severe delayed effect across metamorphosis was especially remarkable in high-latitude animals, as they appeared almost insensitive to zinc during the larval stage. Second, the well-known synergism between metals and warming was manifested not only during the larval stage but also after metamorphosis, yet notably only in low-latitude damselflies. These results highlight that a more complete life-cycle approach that incorporates the possibility of delayed interactions between contaminants and warming in a geographical context is crucial for a more realistic risk assessment in a warming world.
The water dimer II: Theoretical investigations
Energy Technology Data Exchange (ETDEWEB)
Mukhopadhyay, Anamika; Xantheas, Sotiris S.; Saykally, Richard J.
2018-03-29
As the archetype of hydrogen bonding between water molecules, the water dimer has been extensively studied by both theory and experiment for nearly seven decades. In this article, we present a detailed chronological review of the theoretical advances using electronic structure methods pertaining to the structure, hydrogen bonding and vibrational spectroscopy of the water dimer as well as the role of its potential energy surface in the development of classical force fields to describe intermolecular interaction in clusters and liquid water.
Directory of Open Access Journals (Sweden)
Sadeghi Pedram
2017-06-01
Full Text Available We report on the fabrication and dark-field spectroscopy characterization of Au dimer nanoantennas placed on top of SiO2 nanopillars. The reported process enables the fabrication of nanopillar dimers with gaps down to 15 nm and heights up to 1 μm. A clear dependence of the plasmonic resonance position on the dimer gap is observed for smaller pillar heights, showing the high uniformity and reproducibility of the process. It is shown how increasing the height of nanopillars significantly affects the recorded elastic scattering spectra from Au nanoantennas. The results are compared to finite-difference time-domain (FDTD and finite-element method (FEM simulations. Additionally, measured spectra are accompanied by dark-field microscopy images of the dimers, showing the pronounced change in color. Placing nanoantennas on nanopillars with a height comparable to the in-plane dimer dimensions results in an enhancement of the scattering response, which can be understood through reduced interaction of the near-fields with the substrate. When increasing the pillar height further, scattering by the pillars themselves manifests itself as a strong tail at lower wavelengths. Additionally, strong directional scattering is expected as a result of the interface between the nanoantennas and nanopillars, which is taken into account in simulations. For pillars of height close to the plasmonic resonance wavelength, the scattering spectra become more complex due to additional scattering peaks as a result of larger geometrical nonuniformities.
Xu, Defeng; Chen, Qiulu; Liu, Yalin; Wen, Xingqiao
2017-12-01
Androgen receptor (AR) plays a critical role in prostate cancer (PCa) development and progression. Androgen deprivation therapy with antiandrogens to reduce androgen biosynthesis or prevent androgens from binding to AR are widely used to suppress AR-mediated PCa growth. However, most of ADT may eventually fail with development of the castration resistance after 12-24 months. Here we found that a natural product baicalein can effectively suppress the PCa progression via targeting the androgen-induced AR transactivation with little effect to AR protein expression. PCa cells including LNCaP, CWR22Rv1, C4-2, PC-3, and DU145, were treated with baicalein and luciferase assay was used to evaluate their effect on the AR transactivation. Cell growth and IC 50 were determined by MTT assay after 48 hrs treatment. RT-PCR was used to evaluate the mRNA levels of AR target genes including PSA, TMPRSS2, and TMEPA1. Western blot was used to determine AR and PSA protein expression. The natural product of baicalein can selectively inhibit AR transactivation with little effect on the other nuclear receptors, including ERα, and GR. At a low concentration, 2.5 μM of baicalein effectively suppresses the growth of AR-positive PCa cells, and has little effect on AR-negative PCa cells. Mechanism dissection suggest that baicalein can suppress AR target genes (PSA, TMPRSS2, and TMEPA1) expression in both androgen responsive LNCaP cells and castration resistant CWR22Rv1 cells, that may involve the inhibiting the AR N/C dimerization and AR-coactivators interaction. Baicalein may be developed as an effective anti-AR therapy via its ability to inhibit AR transactivation and AR-mediated PCa cell growth.
Numerical simulation of wave-current interaction under strong wind conditions
Larrañaga, Marco; Osuna, Pedro; Ocampo-Torres, Francisco Javier
2017-04-01
Although ocean surface waves are known to play an important role in the momentum and other scalar transfer between the atmosphere and the ocean, most operational numerical models do not explicitly include the terms of wave-current interaction. In this work, a numerical analysis about the relative importance of the processes associated with the wave-current interaction under strong off-shore wind conditions in Gulf of Tehuantepec (the southern Mexican Pacific) was carried out. The numerical system includes the spectral wave model WAM and the 3D hydrodynamic model POLCOMS, with the vertical turbulent mixing parametrized by the kappa-epsilon closure model. The coupling methodology is based on the vortex-force formalism. The hydrodynamic model was forced at the open boundaries using the HYCOM database and the wave model was forced at the open boundaries by remote waves from the southern Pacific. The atmospheric forcing for both models was provided by a local implementation of the WRF model, forced at the open boundaries using the CFSR database. The preliminary analysis of the model results indicates an effect of currents on the propagation of the swell throughout the study area. The Stokes-Coriolis term have an impact on the transient Ekman transport by modifying the Ekman spiral, while the Stokes drift has an effect on the momentum advection and the production of TKE, where the later induces a deepening of the mixing layer. This study is carried out in the framework of the project CONACYT CB-2015-01 255377 and RugDiSMar Project (CONACYT 155793).
International Nuclear Information System (INIS)
Belvedere, Riccardo; Pugliese, Daniela; Rueda, Jorge A.; Ruffini, Remo; Xue, She-Sheng
2012-01-01
We formulate the equations of equilibrium of neutron stars taking into account strong, weak, electromagnetic, and gravitational interactions within the framework of general relativity. The nuclear interactions are described by the exchange of the σ, ω, and ρ virtual mesons. The equilibrium conditions are given by our recently developed theoretical framework based on the Einstein–Maxwell–Thomas–Fermi equations along with the constancy of the general relativistic Fermi energies of particles, the “Klein potentials”, throughout the configuration. The equations are solved numerically in the case of zero temperatures and for selected parameterizations of the nuclear models. The solutions lead to a new structure of the star: a positively charged core at supranuclear densities surrounded by an electronic distribution of thickness ∼ℏ/(m e c)∼10 2 ℏ/(m π c) of opposite charge, as well as a neutral crust at lower densities. Inside the core there is a Coulomb potential well of depth ∼m π c 2 /e. The constancy of the Klein potentials in the transition from the core to the crust, imposes the presence of an overcritical electric field ∼(m π /m e ) 2 E c , the critical field being E c =m e 2 c 3 /(eℏ). The electron chemical potential and the density decrease, in the boundary interface, until values μ e crust e core and ρ crust core . For each central density, an entire family of core–crust interface boundaries and, correspondingly, an entire family of crusts with different mass and thickness, exist. The configuration with ρ crust =ρ drip ∼4.3×10 11 gcm −3 separates neutron stars with and without inner crust. We present here the novel neutron star mass–radius for the especial case ρ crust =ρ drip and compare and contrast it with the one obtained from the traditional Tolman–Oppenheimer–Volkoff treatment.
Introduction to gauge theories of the strong, weak, and electromagnetic interactions
International Nuclear Information System (INIS)
Quigg, C.
1980-07-01
The plan of these notes is as follows. Chapter 1 is devoted to a brief evocative review of current beliefs and prejudices that form the context for the discussion to follow. The idea of Gauge Invariance is introduced in Chapter 2, and the connection between conservation laws and symmetries of the Lagrangian is recalled. Non-Abelian gauge field theories are constructed in Chapter 3, by analogy with the familiar case of electromagnetism. The Yang-Mills theory based upon isospin symmetry is constructed explicitly, and the generalization is made to other gauge groups. Chapter 4 is concerned with spontaneous symmetry breaking and the phenomena that occur in the presence or absence of local gauge symmetries. The existence of massless scalar fields (Goldstone particles) and their metamorphosis by means of the Higgs mechanism are illustrated by simple examples. The Weinberg-Salam model is presented in Chapter 5, and a brief resume of applications to experiment is given. Quantum Chromodynamics, the gauge theory of colored quarks and gluons, is developed in Chapter 6. Asymptotic freedom is derived schematically, and a few simple applications of perturbative QCD ae exhibited. Details of the conjectured confinement mechanism are omitted. The strategy of grand unified theories of the strong, weak, and electromagnetic interactions is laid out in Chapter 7. Some properties and consequences of the minimal unifying group SU(5) are presented, and the gauge hierarchy problem is introduced in passing. The final chapter contains an essay on the current outlook: aspirations, unanswered questions, and bold scenarios
Strong interactions between learned helplessness and risky decision-making in a rat gambling model.
Nobrega, José N; Hedayatmofidi, Parisa S; Lobo, Daniela S
2016-11-18
Risky decision-making is characteristic of depression and of addictive disorders, including pathological gambling. However it is not clear whether a propensity to risky choices predisposes to depressive symptoms or whether the converse is the case. Here we tested the hypothesis that rats showing risky decision-making in a rat gambling task (rGT) would be more prone to depressive-like behaviour in the learned helplessness (LH) model. Results showed that baseline rGT choice behaviour did not predict escape deficits in the LH protocol. In contrast, exposure to the LH protocol resulted in a significant increase in risky rGT choices on retest. Unexpectedly, control rats subjected only to escapable stress in the LH protocol showed a subsequent decrease in riskier rGT choices. Further analyses indicated that the LH protocol affected primarily rats with high baseline levels of risky choices and that among these it had opposite effects in rats exposed to LH-inducing stress compared to rats exposed only to the escape trials. Together these findings suggest that while baseline risky decision making may not predict LH behaviour it interacts strongly with LH conditions in modulating subsequent decision-making behaviour. The suggested possibility that stress controllability may be a key factor should be further investigated.
Inhomogeneous chiral symmetry breaking in isospin-asymmetric strong-interaction matter
Energy Technology Data Exchange (ETDEWEB)
Nowakowski, Daniel
2017-07-01
In this thesis we investigate the effects of an isospin asymmetry on inhomogeneous chiral symmetry breaking phases, which are characterized by spatially modulated quarkantiquark condensates. In order to determine the relevance of such phases for the phase diagram of strong-interaction matter, a two-flavor Nambu-Jona-Lasinio model is used to study the properties of the ground state of the system. Confirming the presence of inhomogeneous chiral symmetry breaking in isospin-asymmetric matter for a simple Chiral Density Wave, we generalize the modulation of the quark-antiquark pairs to more complicated shapes and study the effects of different degrees of flavor-mixing on the inhomogeneous phase at non-zero isospin asymmetry. Then, we investigate the occurrence of crystalline chiral symmetry breaking phases in charge-neutral matter, from which we determine the influence of crystalline phases on a quark star by calculating mass-radius sequences. Finally, our model is extended through color-superconducting phases and we study the interplay of these phases with inhomogeneous chiral-symmetry breaking at non-vanishing isospin asymmetry, before we discuss our findings.
Electron-photon and electron-electron interactions in the presence of strong electromagnetic fields
International Nuclear Information System (INIS)
Surzhykov, A.; Fritzsche, S.; Stoehlker, Th.
2010-01-01
During the last decade, photon emission from highly-charged, heavy ions has been in the focus of intense studies at the GSI accelerator and storage ring facility in Darmstadt. These studies have revealed unique information about the electron-electron and electron-photon interactions in the presence of extremely strong nuclear fields. Apart from the radiative electron capture processes, characteristic photon emission following collisional excitation of projectile ions has also attracted much interest. In this contribution, we summarize the recent theoretical studies on the production of excited ionic states and their subsequent radiative decay. We will pay special attention to the angular and polarization properties of Kα emission from helium-like ions produced by means of dielectronic recombination. The results obtained for this (resonant) capture process will be compared with the theoretical predictions for the characteristic X-rays following Coulomb excitation and radiative recombination of few-electron, heavy ions. Work is supported by Helmholtz Association and GSl under the project VH-NG--421. (author)
Compact X-ray sources. Simulating the electron/strong laser interaction
Energy Technology Data Exchange (ETDEWEB)
Hartin, Anthony [DESY, CFEL, Hamburg (Germany)
2016-07-01
The collision of an intense laser with an electron bunch can be used to produce X-rays via the inverse Compton scattering (ICS) mechanism. The ICS can be simulated via either a classical theory in which electrons and photons are treated in terms of classical electromagnetic waves - or a quantum theory in which charged particles interact with strong electromagnetic fields. The laser intensity used in a practical ICS collision is likely to be at such a level that quantum effects may be significant and the use of quantum theory may become a necessity. A simulation study is presented here comparing the classical and quantum approaches to the ICS. A custom particle-in-cell (PIC) software code, with photon generation by monte carlo of the exact quantum transition probability is used to simulate the quantum treatment. Peak resonant energies and the angular distribution of the X-rays are obtained and compared with those predicted by the classical theory. The conditions under which significant differences between the two theories emerges is obtained.
Lattice QCD results on soft and hard probes of strongly interacting matter
Kaczmarek, Olaf
2017-11-01
We present recent results from lattice QCD relevant for the study of strongly interacting matter as it is produced in heavy ion collision experiments. The equation of state at non-vanishing density from a Taylor expansion up to 6th order will be discussed for a strangeness neutral system and using the expansion coefficients of the series limits on the critical point are estimated. Chemical freeze-out temperatures from the STAR and ALICE Collaborations will be compared to lines of constant physics calculated from the Taylor expansion of QCD bulk thermodynamic quantities. We show that qualitative features of the √{sNN} dependence of skewness and kurtosis ratios of net proton-number fluctuations measured by the STAR Collaboration can be understood from QCD results for cumulants of conserved baryon-number fluctuations. As an example for recent progress towards the determination of spectral and transport properties of the QGP from lattice QCD, we will present constraints on the thermal photon rate determined from a spectral reconstruction of continuum extrapolated lattice correlation functions in combination with input from most recent perturbative calculations.
International Nuclear Information System (INIS)
Dubovitskii, V.A.; Pavlov, G.A.; Krasnikov, Yu.G.
1996-01-01
Thermodynamic analysis of media with strong interparticle (Coulomb) interaction is presented. A method for constructing isotherms is proposed for a medium described by a closed multicomponent thermodynamic model. The method is based on choosing an appropriate nondegenerate frame of reference in the extended space of thermodynamic variables and provides efficient thermodynamic calculations in a wide range of parameters, for an investigation of phase transitions of the first kind, and for determining both the number of phases and coexistence curves. A number of approximate thermodynamic models of hydrogen plasma are discussed. The approximation corresponding to the n5/2 law, in which the effects of particle attraction and repulsion are taken into account qualitatively, is studied. This approximation allows studies of thermodynamic properties of a substance for a wide range of parameters. In this approximation, for hydrogen at a constant temperature, various properties of the degree of ionization are revealed. In addition, the parameters of the second critical point are found under conditions corresponding to the Jovian interior
Alvarado, John Jeff; Tarafdar, Sreya; Yeh, Joanne I; Smithgall, Thomas E
2014-10-10
HIV-1 Nef supports high titer viral replication in vivo and is essential for AIDS progression. Nef function depends on interactions with multiple host cell effectors, including Hck and other Src-family kinases. Here we describe the x-ray crystal structure of Nef in complex with the Hck SH3-SH2 regulatory region to a resolution of 1.86 Å. The complex crystallized as a dimer of complexes, with the conserved Nef PXXPXR motif engaging the Hck SH3 domain. A new intercomplex contact was found between SH3 Glu-93, and Nef Arg-105. Mutagenesis of Hck SH3 Glu-93 interfered with Nef·Hck complex formation and kinase activation in cells. The Hck SH2 domains impinge on the N-terminal region of Nef to stabilize a dimer conformation that exposes Asp-123, a residue critical for Nef function. Our results suggest that in addition to serving as a kinase effector for Nef, Hck binding may reorganize the Nef dimer for functional interaction with other signaling partners. © 2014 by The American Society for Biochemistry and Molecular Biology, Inc.
Alvarado, John Jeff; Tarafdar, Sreya; Yeh, Joanne I.; Smithgall, Thomas E.
2014-01-01
HIV-1 Nef supports high titer viral replication in vivo and is essential for AIDS progression. Nef function depends on interactions with multiple host cell effectors, including Hck and other Src-family kinases. Here we describe the x-ray crystal structure of Nef in complex with the Hck SH3-SH2 regulatory region to a resolution of 1.86 Å. The complex crystallized as a dimer of complexes, with the conserved Nef PXXPXR motif engaging the Hck SH3 domain. A new intercomplex contact was found between SH3 Glu-93, and Nef Arg-105. Mutagenesis of Hck SH3 Glu-93 interfered with Nef·Hck complex formation and kinase activation in cells. The Hck SH2 domains impinge on the N-terminal region of Nef to stabilize a dimer conformation that exposes Asp-123, a residue critical for Nef function. Our results suggest that in addition to serving as a kinase effector for Nef, Hck binding may reorganize the Nef dimer for functional interaction with other signaling partners. PMID:25122770
International Nuclear Information System (INIS)
Carruthers, P.; Thews, R.L.
1988-01-01
This paper contains progress information on the following topics in High Energy Physics: strong, electromagnetic, and weak interactions; aspects of quark-gluon models for hadronic interactions, decays, and structure; the dynamical generation of a mass gap and the role and truthfulness of perturbation theory; statistical and dynamical aspects of hadronic multiparticle production; and realization of chiral symmetry and temperature effects in supersymmetric theories
DEFF Research Database (Denmark)
Bach, Anders*; Clausen, Bettina H; Møller, Magda
2012-01-01
Inhibition of the ternary protein complex of the synaptic scaffolding protein postsynaptic density protein-95 (PSD-95), neuronal nitric oxide synthase (nNOS), and the N-methyl-d-aspartate (NMDA) receptor is a potential strategy for treating ischemic brain damage, but high-affinity inhibitors are ...... of Tat-N-dimer (3 nmol/g) to mice subjected to focal cerebral ischemia reduces infarct volume with 40% and restores motor functions. Thus, Tat-N-dimer is a highly efficacious neuroprotective agent with therapeutic potential in stroke....
Sivalingam, Kantharuban; Krupicka, Martin; Auer, Alexander A.; Neese, Frank
2016-08-01
Multireference (MR) methods occupy an important class of approaches in quantum chemistry. In many instances, for example, in studying complex magnetic properties of transition metal complexes, they are actually the only physically satisfactory choice. In traditional MR approaches, single and double excitations are performed with respect to all reference configurations (or configuration state functions, CSFs), which leads to an explosive increase of computational cost for larger reference spaces. This can be avoided by the internal contraction scheme proposed by Meyer and Siegbahn, which effectively reduces the number of wavefunction parameters to their single-reference counterpart. The "fully internally contracted" scheme (FIC) is well known from the popular CASPT2 approach. An even shorter expansion of the wavefunction is possible with the "strong contraction" (SC) scheme proposed by Angeli and Malrieu in their NEVPT2 approach. Promising multireference configuration interaction formulations (MRCI) employing internal contraction and strong contraction have been reported by several authors. In this work, we report on the implementation of the FIC-MRCI and SC-MRCI methodologies, using a computer assisted implementation strategy. The methods are benchmarked against the traditional uncontracted MRCI approach for ground and excited states of small molecules (N2, O2, CO, CO+, OH, CH, and CN). For ground states, the comparison includes the "partially internally contracted" MRCI based on the Celani-Werner ansatz (PC-MRCI). For the three contraction schemes, the average errors range from 2% to 6% of the uncontracted MRCI correlation energies. Excitation energies are reproduced with ˜0.2 eV accuracy. In most cases, the agreement is better than 0.2 eV, even in cases with very large differential correlation contributions as exemplified for the d-d and ligand-to-metal charge transfer transitions of a Cu [NH 3 ] 4 2 + model complex. The benchmark is supplemented with the
International Nuclear Information System (INIS)
Deursen, A.P.J. van; Reuss, J.
1976-01-01
An attempt has been made to detect mixed dimers in nozzle beams of mixtures; NeAr and HeNe dimers were observed with sufficient intensity to determine the total collision cross section. A similar attempt for H 2 Ar was partially hampered by the circumstance that the corresponding HAr + ion must be detected on the wing of the thousand times larger Ar + peak. The search for H 2 He, H 2 Ne and HeAr dimers was not successful, due to masking ion peaks, H 5 + for HHe + , 21 Ne + for H 20 Ne + , and CO 2 + for HeAr + . (Auth.)
DEFF Research Database (Denmark)
Bakarić, Danijela; Spanget-Larsen, Jens
2018-01-01
are used to study possible 2-EP dimer structures as well as their distribution in an inert solvent such as tetrachloroethene. Experimentally, the ≡C–H stretching vibration of the 2-EPmonomer absorbs close to 3300 cm−1, whereas a broad band withmaximum around 3215 cm−1 emerges as the concentration rises...... model with counterpoise correction predict that the two most stable dimers are of the pi-stacked variety, closely followed by dimers with intermolecular ≡C–H···N hydrogen bonding; the predicted red shifts of the ≡C–H stretching wavenumbers due to hydrogen bonding are in the range 54 – 120 cm–1...
... 1997). Taber's Cyclopedic Medical Dictionary. F.A. Davis Company, Philadelphia, PA [18th Edition]. Pagana, Kathleen D. & Pagana, ... www.itxm.org . Titus, K. (2003 January). Identity crisis persists: which D-dimer? CAP Today , In the ...
Theoretical analysis of bimetallic nanorod dimer biosensors for label-free molecule detection
Das, Avijit; Talukder, Muhammad Anisuzzaman
2018-02-01
In this work, we theoretically analyze a gold (Au) core within silver (Ag) shell (Au@Ag) nanorod dimer biosensor for label-free molecule detection. The incident light on an Au@Ag nanorod strongly couples to localized surface plasmon modes, especially around the tip region. The field enhancement around the tip of a nanorod or between the tips of two longitudinally aligned nanorods as in a dimer can be exploited for sensitive detection of biomolecules. We derive analytical expressions for the interactions of an Au@Ag nanorod dimer with the incident light. We also study the detail dynamics of an Au@Ag nanorod dimer with the incident light computationally using finite difference time domain (FDTD) technique when core-shell ratio, relative position of the nanorods, and angle of incidence of light change. We find that the results obtained using the developed analytical model match well with that obtained using FDTD simulations. Additionally, we investigate the sensitivity of the Au@Ag nanorod dimer, i.e., shift in the resonance wavelength, when a target biomolecule such as lysozyme (Lys), human serum albumin (HSA), anti-biotin (Abn), human catalase (CAT), and human fibrinogen (Fb) protein molecules are attached to the tips of the nanorods.
Lushnikov, A. A.; Kulmala, M.
1998-09-01
The dimer stage of nucleation may affect considerably the rate of the nucleation process at high supersaturation of the nucleating vapor. Assuming that the dimer formation limits the nucleation rate, the kinetics of the particle formation-growth process is studied starting with the definition of dimers as bound states of two associating molecules. The partition function of dimer states is calculated by summing the Boltzmann factor over all classical bound states, and the equilibrium population of dimers is found for two types of intermolecular forces: the Lennard-Jones (LJ) and rectangular well+hard core (RW) potentials. The principle of detailed balance is used for calculating the evaporation rate of dimers. The kinetics of the particle formation-growth process is then investigated under the assumption that the trimers are stable with respect to evaporation and that the condensation rate is a power function of the particle mass. If the power exponent λ=n/(n+1) (n is a non-negative integer), the kinetics of the process is described by a finite set of moments of particle mass distribution. When the characteristic time of the particle formation by nucleation is much shorter than that of the condensational growth, n+2 universal functions of a nondimensional time define the kinetic process. These functions are calculated for λ=2/3 (gas-to-particle conversion in the free molecular regime) and λ=1/2 (formation of islands on surfaces).
Coupling of tt̄ and γγ with a strongly interacting Electroweak Symmetry Breaking Sector
Directory of Open Access Journals (Sweden)
Delgado Rafael L.
2017-01-01
Full Text Available We report the coupling of an external γγ or tt̄ state to a strongly interacting EWSBS satisfying unitarity. We exploit perturbation theory for those coupling of the external state, whereas the EWSBS is taken as strongly interacting. We use a modified version of the IAM unitarization procedure to model such a strongly interacting regime. The matrix elements VLVL → VLVL, VLVL ↔ hh, hh → hh, VLVL ↔ {γγ, tt̄}, hh ↔ {γγ, tt̄} are all computed to NLO in perturbation theory with the Nonlinear Effective Field Theory of the EWSBS, within the Equivalence Theorem. This allows us to describe resonances of the electroweak sector that may be found at the LHC and their effect on other channels such as γγ or tt̄ where they may be discovered.
Energy Technology Data Exchange (ETDEWEB)
Chan, J.; DePorcel, L.; Dixon, L. [eds.
1997-06-01
This conference explored the role of the strong interaction in the physics of hadrons and partons. The Institute attracted 239 physicists from 16 countries to hear lectures on the underlying theory of Quantum Chromodynamics, modern theoretical calculational techniques, and experimental investigation of the strong interaction as it appears in various phenomena. Different regimes in which one can calculate reliably in QCD were addressed in series of lectures on perturbation theory, lattice gauge theories, and heavy quark expansions. Studies of QCD in hadron-hadron collisions, electron-positron annihilation, and electron-proton collisions all give differing perspectives on the strong interaction--from low-x to high-Q{sup 2}. Experimental understanding of the production and decay of heavy quarks as well as the lighter meson states has continued to evolve over the past years, and these topics were also covered at the School. Selected papers have been indexed separately for inclusion in the Energy Science and Technology Database.
International Nuclear Information System (INIS)
Boreham, B. W.; Hora, H.
1997-01-01
We have recently developed a correspondence principle for electromagnetic interaction. When applied to laser interactions with electrons this correspondence principle identifies a critical laser intensity I*. This critical intensity is a transition intensity separating classical mechanical and quantum mechanical interaction regimes. In this paper we discuss the further application of I* to the interaction of bound electrons in atoms. By comparing I* with the ionisation threshold intensities as calculated from a cycle-averaged simple-atom model we conclude that I* can be usefully interpreted as a lower bound to the classical regime in studies of ionisation of gas atoms by intense laser beams
International Nuclear Information System (INIS)
Konijn, J.; Panman, J.K.; Koch, J.H.; Doesburg, W. van; Ewan, G.T.; Johansson, T.; Tibell, G.; Fransson, K.; Tauscher, L.
1979-01-01
Owing to a powerful Compton-suppression technique it was possible to observe for the first time the pionic 4f→3d X-ray transition in elements heavier than A=150. The strong interaction monopole shifts epsilon 0 and widths GAMMA 0 as well as the quadrupole splitting of the 3d levels have been measured in Ta, Re and Bi. Thus in addition to the strongly shifted and broadened 5g→4f transitions, a second, strongly affected line is available for these elements. For the pionic 4f levels, standard optical potentials fit the strong interaction shifts and broadenings quite well. The now observed, deeper-lying 3d states in Ta, Re and Bi have shifts and widths that differ by a factor of 2 or more from the standard optical potential predictions. From the observed relative X-ray intensities of the pionic cascade the strong interaction widths of the 5g and 4f levels are also extracted. (Auth.)
Radiation chemistry of aromatic dimer radical cations
International Nuclear Information System (INIS)
Okamoto, Kazumasa; Tagawa, Seiichi
2009-01-01
π-π Interactions of aromatic molecules are paid attention much in many fields, especially biology, chemistry, and applied physics, represented as protein, DNA, electron donor-accepter complexes, charge transfers, and self assembly molecules. Aromatic molecules including benzene rings are the simplest case to study the π-π interactions. To interpret the charge resonance (CR) structure in the dimer radical cations, spectroscopic and ESR methods have been carried out. The spectroscopic study on the dimer radical ion of molecules with two chromophores would be profitable to identify the electronic and configurational properties. In this article, dynamics of the dimer radical cation of benzenes, polystyrenes, and resist polymers is described on the basis of direct observation of CR band by the nanosecond pulse radiolysis and low temperature γ-radiolysis methods. (author)
The Quantum-to-Classical Transition in Strongly Interacting Nanoscale Systems
Benatov, Latchezar Latchezarov
This thesis comprises two separate but related studies, dealing with two strongly interacting nanoscale systems on the border between the quantum and classical domains. In Part 1, we use a Born-Markov approximated master equation approach to study the symmetrized-in-frequency current noise spectrum and the oscillator steady state of a nanoelectromechanical system where a nanoscale resonator is coupled linearly via its momentum to a quantum point contact (QPC). Our current noise spectra exhibit clear signatures of the quantum correlations between the QPC current and the back-action force on the oscillator at a value of the relative tunneling phase where such correlations are expected to be maximized. We also show that the steady state of the oscillator obeys a classical Fokker-Planck equation, but can experience thermomechanical noise squeezing in the presence of a momentum-coupled detector bath and a position-coupled environmental bath. Besides, the full master equation clearly shows that half of the detector back-action is correlated with electron tunneling, indicating a departure from the model of the detector as an effective bath and suggesting that a future calculation valid at lower bias voltage, stronger tunneling and/or stronger coupling might reveal interesting quantum effects in the oscillator dynamics. In the second part of the thesis, we study the subsystem dynamics and thermalization of an oscillator-spin star model, where a nanomechanical resonator is coupled to a few two-level systems (TLS's). We use a fourth-order Runge-Kutta numerical algorithm to integrate the Schrodinger equation for the system and obtain our results. We find that the oscillator reaches a Boltzmann steady state when the TLS bath is initially in a thermal state at a temperature higher than the oscillator phonon energy. This occurs in both chaotic and integrable systems, and despite the small number of spins (only six) and the lack of couplings between them. At the same time, pure
International Nuclear Information System (INIS)
Zaikin, Yu.A.; Koztaeva, U.P.
2002-01-01
In earlier papers the internal friction (IF) method was applied to studies of structural relaxation in different types of polymer-based composite materials (glass-cloth, paper-based and foiled laminates impregnated by epoxy and phenolic resins) irradiated by 2 MeV electrons in the dose range of 0.1-50.0 MGy. Selectivity and high sensibility of the internal friction method allowed to distinguish glassy transitions in different structural components of the composites. The relaxation processes observed were identified and attributed to structural alterations in the polymer filler, the binder and the boundary layers. It was shown that changes in the parameters of relaxation maximums during irradiation can be considered as quantitative characteristics for the degree of radiation-induced degradation or cross-linking of polymer molecules. This paper deals with specific features of IF spectra in paper-based laminates where both the filler fibers and the binder are strongly interacting polymers. Anisotropy of viscous and elastic properties is very weak for this kind of materials, so that IF measurements give nearly the same result independently on the filler fiber orientation in the sample. The main reasons for it are the rigid chain structure of fillers (polyethylene-terephthalate and cellulose) and the good adhesion strengthened by diffusion of the epoxy or phenolic binder to defect regions of the filler.The IF temperature dependence observed in paper-based laminates is represented by superposition of two very broad relaxation maximums associated with transitions from glassy to high-elastic state in structural components, each based on one of the polymers. The inflection points characteristic for IF temperature dependence in paper-based laminates give a reason to treat them as a superposition of α-peaks associated with transitions from glassy to high-elastic state in structural components of a composite based on the binder and the filler, respectively. Another
Peculiarities of MCD C-term saturation behavior of the exchange coupled Co(II) dimers
International Nuclear Information System (INIS)
Ostrovsky, S.M.
2011-01-01
Graphical abstract: The change of sign of the MCD signal with temperature and magnetic field increase can take place. The origin of this peculiarity is explained by the strong orbital contribution. Highlights: → MCD C-term saturation behavior of the exchange coupled cobalt dimer. → Strong orbital contribution to the magneto-optical behavior. → Change of sign of the MCD signal with temperature and magnetic field increase. - Abstract: The MCD C-term saturation behavior of the exchange coupled octahedrally coordinated cobalt dimers is studied for different types of distortion of the local surrounding of each interacting ion. It was found that in the case of antiferromagnetic exchange interaction the change of sign of the MCD signal with temperature and magnetic field increase can take place. This signal behavior is not the result of overlapping of different electronic transitions and it is characteristic of an individual MCD line. The origin of this magneto-optical behavior is explained by the strong contribution coming from the unquenched orbital angular momenta of interacting cobalt ions. The found peculiarity is inherent to complexes composed of nonequivalent cobalt ions as well as to the dimeric complexes with the equivalent Co ions with nonparallel local axes.
International Nuclear Information System (INIS)
Maskin, Laura; Frankel, Nicolas; Gudesblat, Gustavo; Demergasso, Maria J.; Pietrasanta, Lia I.; Iusem, Norberto D.
2007-01-01
The Asr gene family is present in Spermatophyta. Its members are generally activated under water stress. We present evidence that tomato ASR1, one of the proteins of the family, accumulates in seed during late stages of embryogenesis, a physiological process characterized by water loss. In vitro, electrophoretic assays show a homo-dimeric structure for ASR1 and highlight strong non-covalent interactions between monomers prone to self-assemble. Direct visualization of single molecules by atomic force microscopy (AFM) confirms that ASR1 forms homodimers and that uncovers both monomers and dimers bind double stranded DNA
Two Populations Mean-Field Monomer-Dimer Model
Alberici, Diego; Mingione, Emanuele
2018-04-01
A two populations mean-field monomer-dimer model including both hard-core and attractive interactions between dimers is considered. The pressure density in the thermodynamic limit is proved to satisfy a variational principle. A detailed analysis is made in the limit of one population is much smaller than the other and a ferromagnetic mean-field phase transition is found.
Structures and energetics of lithium adatom and its dimer on graphene–a DFT study
International Nuclear Information System (INIS)
Kaur, Gagandeep; Gupta, Shuchi; Dharamvir, Keya
2015-01-01
Highlights: • For single Li adatom adsorption on graphene, it prefers H-site followed by B-site. • By the examination of the calculated cohesive energies, it is possible to conclude that both Li/Li 2 binds strongly to graphene which corroborate previous results. • The calculations showed that the interaction between Li and graphene has minimal effects on the electronic states of the graphene sheet, in agreement with previous calculations. • Charge transfer (0.338e)upon adsorption also induces significant electric dipole moments and affect total magnetic moment at B-site and T-site. • For the Li dimer adsorption, we found that horizontal orientation is favored over the vertical. • Adsorption of lithium dimer to the HH-site alters graphene sheet only by small amount ∼0.0022 Å–0.0034 Å. • The methodology demonstrated in this paper maybe applied to larger lithium clusters on graphene sheet. - Abstract: We performed a systematic density functional theory (DFT) study of the adsorption of Lithium adatom and its dimer on graphene using SIESTA package [1], in the generalized gradient approximation (GGA). The adsorption energy, geometry, charge transfer and density of states of adatom/dimer-graphene system are calculated. The calculations showed that the interaction between Li adatom and graphene is strong (∼1.07 eV) and it prefers to adsorb on H-site. Further calculations of both horizontally and vertically aligned dimers show that the adsorption is also weak for the latter orientation. The preferred orientation of each dimer was found to be parallel to graphene sheet with the two atoms of the dimer occupying adjacent H-sites on the graphene. Significant charge transfer (∼0.388e) from Li adatom to graphene will induce electric dipole moments in the adatom/graphene system. We also calculated DOS for the stable Li -graphene system. The Fermi energy is seen to lie above the Dirac point inside the conduction band indicating that appreciable electrons
International Nuclear Information System (INIS)
Zhou, Yongxi; Ernzerhof, Matthias; Bahmann, Hilke
2015-01-01
Drawing on the adiabatic connection of density functional theory, exchange-correlation functionals of Kohn-Sham density functional theory are constructed which interpolate between the extreme limits of the electron-electron interaction strength. The first limit is the non-interacting one, where there is only exchange. The second limit is the strong correlated one, characterized as the minimum of the electron-electron repulsion energy. The exchange-correlation energy in the strong-correlation limit is approximated through a model for the exchange-correlation hole that is referred to as nonlocal-radius model [L. O. Wagner and P. Gori-Giorgi, Phys. Rev. A 90, 052512 (2014)]. Using the non-interacting and strong-correlated extremes, various interpolation schemes are presented that yield new approximations to the adiabatic connection and thus to the exchange-correlation energy. Some of them rely on empiricism while others do not. Several of the proposed approximations yield the exact exchange-correlation energy for one-electron systems where local and semi-local approximations often fail badly. Other proposed approximations generalize existing global hybrids by using a fraction of the exchange-correlation energy in the strong-correlation limit to replace an equal fraction of the semi-local approximation to the exchange-correlation energy in the strong-correlation limit. The performance of the proposed approximations is evaluated for molecular atomization energies, total atomic energies, and ionization potentials
International Nuclear Information System (INIS)
Benisti, D.
2011-01-01
This manuscript provides a theoretical description, sometimes illustrated by experimental results, of several examples of field-matter interaction in various domains of physics, showing how the same basic concepts and theoretical methods may be used in very different physics situations. The issues addressed here are nonlinear field-matter interaction in plasma physics within the framework of classical mechanics (with a particular emphasis on wave-particle interaction), the linear analysis of beam-plasma instabilities in the relativistic regime, and the quantum description of laser-atom interaction, including quantum electrodynamics. Novel methods are systematically introduced in order to solve some very old problems, like the nonlinear counterpart of the Landau damping rate in plasma physics, for example. Moreover, our results directly apply to inertial confinement fusion, laser propagation in an atomic vapor, ion acceleration in a magnetized plasma and the physics of the Reversed Field Pinch for magnetic fusion. (author)
Evidence for a strong sulfur-aromatic interaction derived from crystallographic data.
Zauhar, R J; Colbert, C L; Morgan, R S; Welsh, W J
2000-03-01
We have uncovered new evidence for a significant interaction between divalent sulfur atoms and aromatic rings. Our study involves a statistical analysis of interatomic distances and other geometric descriptors derived from entries in the Cambridge Crystallographic Database (F. H. Allen and O. Kennard, Chem. Design Auto. News, 1993, Vol. 8, pp. 1 and 31-37). A set of descriptors was defined sufficient in number and type so as to elucidate completely the preferred geometry of interaction between six-membered aromatic carbon rings and divalent sulfurs for all crystal structures of nonmetal-bearing organic compounds present in the database. In order to test statistical significance, analogous probability distributions for the interaction of the moiety X-CH(2)-X with aromatic rings were computed, and taken a priori to correspond to the null hypothesis of no significant interaction. Tests of significance were carried our pairwise between probability distributions of sulfur-aromatic interaction descriptors and their CH(2)-aromatic analogues using the Smirnov-Kolmogorov nonparametric test (W. W. Daniel, Applied Nonparametric Statistics, Houghton-Mifflin: Boston, New York, 1978, pp. 276-286), and in all cases significance at the 99% confidence level or better was observed. Local maxima of the probability distributions were used to define a preferred geometry of interaction between the divalent sulfur moiety and the aromatic ring. Molecular mechanics studies were performed in an effort to better understand the physical basis of the interaction. This study confirms observations based on statistics of interaction of amino acids in protein crystal structures (R. S. Morgan, C. E. Tatsch, R. H. Gushard, J. M. McAdon, and P. K. Warme, International Journal of Peptide Protein Research, 1978, Vol. 11, pp. 209-217; R. S. Morgan and J. M. McAdon, International Journal of Peptide Protein Research, 1980, Vol. 15, pp. 177-180; K. S. C. Reid, P. F. Lindley, and J. M. Thornton, FEBS
International Nuclear Information System (INIS)
Zhang Zhaoxi
2005-01-01
The 2004 Nobel Prize in Physics was awarded to David J. Gross, Frank Wilczek and H. David Politzer for their decisive contributions to the theory of the asymptotic freedom of the strong interaction (a fundamental interaction). The fundamental elements of quantum chromodynamics (QCD) and the theory of the strong interaction are briefly reviewed in their historical context. How to achieve asymptotic freedom is introduced and its physical meaning explained. The latest experimental tests of asymptotic freedom are presented, and it is shown that the theoretical prediction agrees excellently with the experimental measurements. Perturbative QCD which is based on the asymptotic freedom is outlined. It is pointed out that the theoretical discovery and experimental proof of the asymptotic freedom are crucial for QCD to be the correct theory of strong interaction. Certain frontier research areas of QCD, such as 'color confinement', are mentioned. The discovery and confirmation of asymptotic freedom has indeed deeply affected particle physics, and has led to QCD becoming a main content of the standard model, and to further development of the so-called grand unification theories of interactions. (author)
Systematics of interaction and strong absorption radii determined from heavy-ion elastic scattering
International Nuclear Information System (INIS)
Birkelund, J.R.; Huizenga, J.R.
1977-01-01
Various methods for determining the strong absorption radius for light and intermediate mass nuclei are discussed. It is found that this determination in terms of the half-density radii of the target and projectile is more accurate over the whole range of available data than the other simple parametrizations. 62 references
Veljković, Dušan Ž
2018-03-01
Energies of CH/O interactions between water molecule and polycyclic aromatic hydrocarbons with a different number of aromatic rings were calculated using ab initio calculations at MP2/cc-PVTZ level. Results show that an additional aromatic ring in structure of polycyclic aromatic hydrocarbons significantly strengthens CH/O interactions. Calculated interaction energies in optimized structures of the most stable tetracene/water complex is -2.27 kcal/mol, anthracene/water is -2.13 kcal/mol and naphthalene/water is -1.97 kcal/mol. These interactions are stronger than CH/O contacts in benzene/water complex (-1.44 kcal/mol) while CH/O contacts in tetracene/water complex are even stronger than CH/O contacts in pyridine/water complexes (-2.21 kcal/mol). Electrostatic potential maps for different polycyclic aromatic hydrocarbons were calculated and used to explain trends in the energies of interactions. Copyright © 2017 Elsevier Inc. All rights reserved.
A model-independent description of few-body system with strong interaction
International Nuclear Information System (INIS)
Simenog, I.V.
1985-01-01
In this contribution, the authors discuss the formulation of equations that provide model-independent description of systems of three and more nucleons irrespective of the details of the interaction, substantiate the approach, estimate the correction terms with respect to the force range, and give basic qualitative results obtained by means of the model-independent procedure. They consider three nucleons in the doublet state (spin S=I/2) taking into account only S-interaction. The elastic nd-scattering amplitude may be found from the model-independent equations that follow from the Faddeev equations in the short-range-force limit. They note that the solutions of several model-independent equations and basic results obtained with the use of this approach may serve both as a standard solution and starting point in the discussion of various conceptions concerning the details of nuclear interactions
Motion of Rydberg atoms with strong permanent-electric-dipole interactions
International Nuclear Information System (INIS)
Gonçalves, Luís Felipe; Thaicharoen, Nithiwadee; Raithel, Georg
2016-01-01
Using classical trajectories simulations, we investigate the dynamics of a cold sample of Rydberg atoms with high permanent electric dipole moments. The dipolar state can be created using an adiabatic passage through an avoided crossing between an S-like state and a linear Stark state. The simulations yield the pair-correlation functions (PCF) of the atom samples, which allow us to extract the motion of Rydberg-atom pairs in the many-body system. The results reveal the strength and the anisotropic character of the underlying interaction. The simulation is employed to test the suitability of experimental methods designed to derive interaction parameters from PCF. Insight is obtained about the stability of the method against variation of experimentally relevant parameters. Transient correlations due to interaction-induced heating are observed. (paper)
Magnetic and superconducting competition within the Hubbard dimer. Exact solution
International Nuclear Information System (INIS)
Matlak, M.; Slomska, T.; Grabiec, B.
2005-01-01
We express the Hubbard dimer Hamiltonian H d =Σ 16 α=1 E α vertical stroke E α right angle left angle E α vertical stroke in the second quantization with the use of the Hubbard and spin operators. We consider the case of positive and negative U. We decompose the resulting Hamiltonian into several parts collecting all the terms belonging to the same energy level. Such a decomposition visualizes explicitly all intrinsic interactions competing together and deeply hidden in the original form of the dimer Hamiltonian. Among them are competitive ferromagnetic and antiferromagnetic interactions. There are also hopping terms present which describe Cooper pairs hopping between sites 1 and 2 with positive and negative coupling constants (similar as in Kulik-Pedan, Penson-Kolb models). We show that the competition between intrinsic interactions strongly depends on the model parameters and the averaged occupation number of electrons n element of [0, 4] resulting in different regimes of the model (as e.g. t-J model regime, etc.). (copyright 2005 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)
Karakostas, Vassilios; Papadimitriou, Eleftheria; Jin, Xueshen; Liu, Zhihui; Paradisopoulou, Parthena; He, Zhang
2013-10-01
Northeast China, a densely populated area, is affected by intense seismic activity, which includes large events that caused extensive disaster and tremendous loss of life. For contributing to the continuous efforts for seismic hazard assessment, the earthquake potential from the active faults near the cities of Zhangjiakou and Langfang in Hebei Province is examined. We estimate the effect of the coseismic stress changes of strong (M ⩾ 5.0) earthquakes on the major regional active faults, and mapped Coulomb stress change onto these target faults. More importantly our calculations reveal that positive stress changes caused by the largest events of the 1976 Tangshan sequence make the Xiadian and part of Daxing fault, thus considered the most likely sites of the next strong earthquake in the study area. The accumulated static stress changes that reached a value of up to 0.4 bar onto these faults, were subsequently incorporated in earthquake probability estimates for the next 30 years.
RAMAN LIGHT SCATTERING IN PSEUDOSPIN-ELECTRON MODEL AT STRONG PSEUDOSPIN-ELECTRON INTERACTION
Directory of Open Access Journals (Sweden)
T.S.Mysakovych
2004-01-01
Full Text Available Anharmonic phonon contributions to Raman scattering in locally anharmonic crystal systems in the framework of the pseudospin-electron model with tunneling splitting of levels are investigated. The case of strong pseudospin-electron coupling is considered. Pseudospin and electron contributions to scattering are taken into account. Frequency dependences of Raman scattering intensity for different values of model parameters and for different polarization of scattering and incident light are investigated.
Spectral asymptotics of a strong delta ' interaction on a planar loop
Czech Academy of Sciences Publication Activity Database
Exner, Pavel; Jex, M.
2013-01-01
Roč. 46, č. 34 (2013), s. 345201 ISSN 1751-8113 R&D Projects: GA ČR GAP203/11/0701 Institutional support: RVO:61389005 Keywords : Schrodinger operators * strong coupling asymptotics Subject RIV: BE - Theoretical Physics Impact factor: 1.687, year: 2013 http://iopscience.iop.org/1751-8121/46/34/345201/pdf/1751-8121_46_34_345201.pdf
Periodicity and chaos in strongly perturbed classical orbitals for Coulomb interactions
Energy Technology Data Exchange (ETDEWEB)
Klar, H
1986-01-01
Within the framework of classical mechanics two prototypes of strongly perturbed orbitals, the diamagnetism in hydrogen and electronic double excitation, are analyzed near critical phase space points (fixed points). The motion of the hydrogen electron under the joint influence of the Coulomb field and the magnetic field is periodic for any field strengths. For a two-electron atom however the author finds a chaotic time evolution of the electron pair correlation, causing presumably irregular spectral patterns. (Auth.).
The hyperfine spectrum of hydrogen dimers
International Nuclear Information System (INIS)
Verberne, J.F.C.
1979-01-01
The authors' aim was to obtain the level scheme for the hydrogen dimers and to investigate the angle dependent interactions by analyzing the zero magnetic field hyperfine spectrum of the ortho-ortho and ortho-para species. The results were tested by several recent semi-empirical and ab initio potentials. (Auth.)
Numerical investigation into strong axis bending shear interaction in rolled I-shaped steel sections
Dekker, R.W.A.; Snijder, B.H.; Maljaars, J.
2016-01-01
Clause 6.2.8 of EN 1993-1-1 covers the design rules on bending-shear resistance, taking presence of shear into account by a reduced yield stress for the shear area. Numerical research on bending-shear interaction by means of the Abaqus Finite Element modelling soft-ware is presented. The numerical
Numerical investigation into strong axis bending-shear interaction in rolled I-shaped steel sections
Dekker, R.W.A.; Snijder, H.H.; Maljaars, J.; Dubina, Dan; Ungureanu, Viorel
2016-01-01
Clause 6.2.8 of EN 1993-1-1 covers the design rules on bending-shear resistance, taking presence of shear into account by a reduced yield stress for the shear area. Numerical research on bending-shear interaction by means of the Abaqus Finite Element modelling software is presented. The numerical
Directory of Open Access Journals (Sweden)
Jens Madsen
Full Text Available The protein deleted in malignant brain tumors (DMBT1 and the trefoil factor (TFF proteins have all been proposed to have roles in epithelial cell growth and cell differentiation and shown to be up regulated in inflammatory bowel diseases. A panel of monoclonal antibodies was raised against human DMBT1(gp340. Analysis of lung washings and colon tissue extracts by Western blotting in the unreduced state, two antibodies (Hyb213-1 and Hyb213-6 reacted with a double band of 290 kDa in lung lavage. Hyb213-6, in addition, reacted against a double band of 270 kDa in colon extract while Hyb213-1 showed no reaction. Hyb213-6 showed strong cytoplasmic staining in epithelial cells of both the small and large intestine whereas no staining was seen with Hyb213-1. The number of DMBT1(gp340 positive epithelial cells, stained with Hyb213-6, was significantly up regulated in inflammatory colon tissue sections from patients with ulcerative colitis (p<0.0001 and Crohn's disease (p = 0.006 compared to normal colon tissue. Immunohistochemical analysis of trefoil factor TFF1, 2 and 3 showed that TFF1 and 3 localized to goblet cells in both normal colon tissue and in tissue from patients with ulcerative colitis or Crohn's disease. No staining for TFF2 was seen in goblet cells in normal colon tissue whereas the majority of tissue sections in ulcerative colitis and Crohn's disease showed sparse and scattered TFF2 positive goblet cells. DMBT1 and TFF proteins did therefore not co-localize in the same cells but localized in adjacent cells in the colon. The interaction between DMBT1(gp340 and trefoil TFFs proteins was investigated using an ELISA assay. DMBT1(gp340 bound to solid-phase bound recombinant dimeric TFF3 in a calcium dependent manner (p<0.0001 but did not bind to recombinant forms of monomeric TFF3, TFF2 or glycosylated TFF2. This implies a role for DMBT1 and TFF3 together in inflammatory bowel disease.
Interaction of N-hydroxyurea with strong proton donors: HCl and HF
International Nuclear Information System (INIS)
Sałdyka, Magdalena
2014-01-01
Highlights: • 1:1 and 1:2 N-hydroxyurea complexes with HCl and HF are trapped in argon matrices. • The complexes are stabilized by strong X–H⋯O bond. • Hydrogen bonds in the cyclic 1:2 complexes show strong cooperativity. • The C=O group is the strongest proton acceptor centre in the N-hydroxyurea molecule. - Abstract: An infrared spectroscopic and MP2/6-311++G(2d,2p) study of strong hydrogen bonded complexes of N-hydroxyurea (NH 2 CONHOH) with hydrogen halides (HCl and HF) trapped in solid argon matrices is reported. 1:1 and 1:2 complexes between N-hydroxyurea and hydrogen chloride, hydrogen fluoride have been identified in the NH 2 CONHOH/HCl/Ar, NH 2 CONHOH/HF/Ar matrices, respectively; their structures were determined by comparison of the spectra with the results of calculations. In the 1:1 complexes, identified for both hydrogen halide molecules, the cyclic structure stabilized by the X–H⋯O and N–H⋯X bonds is present; for the NH 2 CONHOH⋯HF system another isomeric 1:1 complex is also observed. Two 1:2 complexes were identified for the N-hydroxyurea–hydrogen chloride system characterised by the Cl–H⋯O and N–H⋯Cl bonds. The results of the study evidence that N-hydroxyurea is an oxygen base in the gas-phase with the carbonyl group as the strongest proton acceptor centre in the molecule
Interaction of N-hydroxyurea with strong proton donors: HCl and HF
Energy Technology Data Exchange (ETDEWEB)
Sałdyka, Magdalena, E-mail: magdalena.saldyka@chem.uni.wroc.pl
2014-11-24
Highlights: • 1:1 and 1:2 N-hydroxyurea complexes with HCl and HF are trapped in argon matrices. • The complexes are stabilized by strong X–H⋯O bond. • Hydrogen bonds in the cyclic 1:2 complexes show strong cooperativity. • The C=O group is the strongest proton acceptor centre in the N-hydroxyurea molecule. - Abstract: An infrared spectroscopic and MP2/6-311++G(2d,2p) study of strong hydrogen bonded complexes of N-hydroxyurea (NH{sub 2}CONHOH) with hydrogen halides (HCl and HF) trapped in solid argon matrices is reported. 1:1 and 1:2 complexes between N-hydroxyurea and hydrogen chloride, hydrogen fluoride have been identified in the NH{sub 2}CONHOH/HCl/Ar, NH{sub 2}CONHOH/HF/Ar matrices, respectively; their structures were determined by comparison of the spectra with the results of calculations. In the 1:1 complexes, identified for both hydrogen halide molecules, the cyclic structure stabilized by the X–H⋯O and N–H⋯X bonds is present; for the NH{sub 2}CONHOH⋯HF system another isomeric 1:1 complex is also observed. Two 1:2 complexes were identified for the N-hydroxyurea–hydrogen chloride system characterised by the Cl–H⋯O and N–H⋯Cl bonds. The results of the study evidence that N-hydroxyurea is an oxygen base in the gas-phase with the carbonyl group as the strongest proton acceptor centre in the molecule.
Strong electron-phonon interaction in the high-Tc superconductors: Evidence from the infrared
International Nuclear Information System (INIS)
Timusk, T.; Porter, C.D.; Tanner, D.B.
1991-01-01
We show that low-frequency structure in the infrared reflectance of the high-temperature superconductor YBa 2 Cu 3 O 7 results from the electron-phonon interaction. Characteristic antiresonant line shapes are seen in the phonon region of the spectrum and the frequency-dependent scattering rate of the mid-infrared electronic continuum has peaks at 150 cm -1 (19 meV) and at 360 cm -1 (45 meV) in good agreement with phonon density-of-states peaks in neutron time-of-flight spectra that develop in superconducting samples. The interaction between the phonons and the charge carriers can be understood in terms of a charged-phonon model
Directory of Open Access Journals (Sweden)
Anders Friberg
2015-05-01
Full Text Available Epstein-Barr virus (EBV is a γ-herpesvirus that may cause infectious mononucleosis in young adults. In addition, epidemiological and molecular evidence links EBV to the pathogenesis of lymphoid and epithelial malignancies. EBV has the unique ability to transform resting B cells into permanently proliferating, latently infected lymphoblastoid cell lines. Epstein-Barr virus nuclear antigen 2 (EBNA-2 is a key regulator of viral and cellular gene expression for this transformation process. The N-terminal region of EBNA-2 comprising residues 1-58 appears to mediate multiple molecular functions including self-association and transactivation. However, it remains to be determined if the N-terminus of EBNA-2 directly provides these functions or if these activities merely depend on the dimerization involving the N-terminal domain. To address this issue, we determined the three-dimensional structure of the EBNA-2 N-terminal dimerization (END domain by heteronuclear NMR-spectroscopy. The END domain monomer comprises a small fold of four β-strands and an α-helix which form a parallel dimer by interaction of two β-strands from each protomer. A structure-guided mutational analysis showed that hydrophobic residues in the dimer interface are required for self-association in vitro. Importantly, these interface mutants also displayed severely impaired self-association and transactivation in vivo. Moreover, mutations of solvent-exposed residues or deletion of the α-helix do not impair dimerization but strongly affect the functional activity, suggesting that the EBNA-2 dimer presents a surface that mediates functionally important intra- and/or intermolecular interactions. Our study shows that the END domain is a novel dimerization fold that is essential for functional activity. Since this specific fold is a unique feature of EBNA-2 it might provide a novel target for anti-viral therapeutics.
DEFF Research Database (Denmark)
Dreiser, Jan; Wäckerlin, Christian; Ali, Md. Ehesan
2014-01-01
We present a comprehensive study of Er(trensal) single-ion magnets deposited in ultrahigh vacuum onto metallic surfaces. X-ray photoelectron spectroscopy reveals that the molecular structure is preserved after sublimation, and that the molecules are physisorbed on Au(111) while they are chemisorbed...... on a Ni thin film on Cu(100) single-crystalline surfaces. X-ray magnetic circular dichroism (XMCD) measurements performed on Au(111) samples covered with molecular monolayers held at temperatures down to 4 K suggest that the easy axes of the strongly anisotropic molecules are randomly oriented...... pathways toward optical addressing of surface-deposited single-ion magnets....
CLEO-c and CESR-c: A new frontier in strong and weak interactions
Energy Technology Data Exchange (ETDEWEB)
Richichi, Stephen J
2003-06-01
We report on the physics potential of a charm and QCD factory, based on a proposal for the conversion of the existing CESR machine and CLEO detector: ''CESR-c and OLEO-c''. Such a facility will make major contributions to the field of quark flavor physics in this decade. It may also provide the best chance for understanding non-perturbative QCD, which is essential to understanding the strongly-coupled sectors of the new physics that lies beyond the Standard Model.
CLEO-c and CESR-c: A new frontier in strong and weak interactions
Richichi, Stephen J.
2003-06-01
We report on the physics potential of a charm and QCD factory, based on a proposal for the conversion of the existing CESR machine and CLEO detector: "CESR-c and OLEO-c". Such a facility will make major contributions to the field of quark flavor physics in this decade. It may also provide the best chance for understanding non-perturbative QCD, which is essential to understanding the strongly-coupled sectors of the new physics that lies beyond the Standard Model.
CLEO-c and CESR-c: A new frontier in strong and weak interactions
International Nuclear Information System (INIS)
Richichi, Stephen J.
2003-01-01
We report on the physics potential of a charm and QCD factory, based on a proposal for the conversion of the existing CESR machine and CLEO detector: ''CESR-c and OLEO-c''. Such a facility will make major contributions to the field of quark flavor physics in this decade. It may also provide the best chance for understanding non-perturbative QCD, which is essential to understanding the strongly-coupled sectors of the new physics that lies beyond the Standard Model
Two-Fluid Description of Wave-Particle Interactions in Strong Buneman Turbulence
Che, H.
2014-01-01
To understand the nature of anomalous resistivity in magnetic reconnection, we investigate turbulence-induced momentum transport and energy dissipation while a plasma is unstable to the Buneman instability in force-free current sheets. Using 3D particle-in-cell simulations, we find that the macroscopic effects generated by wave-particle interactions in Buneman instability can be approximately described by a set of electron fluid equations. We show that both energy dissipation and momentum tra...
Second sound in a two-dimensional Bose gas: From the weakly to the strongly interacting regime
Ota, Miki; Stringari, Sandro
2018-03-01
Using Landau's theory of two-fluid hydrodynamics, we investigate first and second sounds propagating in a two-dimensional (2D) Bose gas. We study the temperature and interaction dependence of both sound modes and show that their behavior exhibits a deep qualitative change as the gas evolves from the weakly interacting to the strongly interacting regime. Special emphasis is placed on the jump of both sounds at the Berezinskii-Kosterlitz-Thouless transition, caused by the discontinuity of the superfluid density. We find that the excitation of second sound through a density perturbation becomes weaker and weaker as the interaction strength increases as a consequence of the decrease in the thermal expansion coefficient. Our results could be relevant for future experiments on the propagation of sound on the Bose-Einstein condensate (BEC) side of the BCS-BEC crossover of a 2D superfluid Fermi gas.
Energy Technology Data Exchange (ETDEWEB)
Quinn, John
2009-11-30
Work related to this project introduced the idea of an effective monopole strength Q* that acted as the effective angular momentum of the lowest shell of composite Fermions (CF). This allowed us to predict the angular momentum of the lowest band of energy states for any value of the applied magnetic field simply by determining N{sub QP} the number of quasielectrons (QE) or quasiholes (QH) in a partially filled CF shell and adding angular momenta of the N{sub QP} Fermions excitations. The approach reported treated the filled CF level as a vacuum state which could support QE and QH excitations. Numerical diagonalization of small systems allowed us to determine the angular momenta, the energy, and the pair interaction energies of these elementary excitations. The spectra of low energy states could then be evaluated in a Fermi liquid-like picture, treating the much smaller number of quasiparticles and their interactions instead of the larger system of N electrons with Coulomb interactions.
Photoionization of helium dimers; Photoionisation von Heliumdimeren
Energy Technology Data Exchange (ETDEWEB)
Havermeier, Tilo
2010-06-09
The helium dimer is one of the most weakly bound systems in the universe. This makes it an interesting quantum mechanical object for investigation. These Van der Waals Clusters can be produced in an expansion of a cryogenic gas jet through a small nozzle into vacuum. In the present experiment we examine the interaction of He dimers with synchrotron radiation at an energy range from 64 to 78 eV. We observed different pathways leading to single ionization of both He atoms of the dimer compound. This two close standing ions begin now to dissociate in cause of their coulomb potential. All charged fragments were detected in coincidence with a COLTRIMS system. Especially Interatomic Coulombic Decay (ICD) and the two step process (TS1) were clearly identified. Furthermore a distribution of the internuclear distance was obtained from the measured Kinetic Energy Release (KER). (orig.)
Aspects of the flipped unification of strong, weak and electromagnetic interactions
Energy Technology Data Exchange (ETDEWEB)
Ellis, J.; Hagelin, J.S.; Kelley, S.; Nanopoulos, D.V.
1988-12-19
We explore phenomenological aspects of a recently proposed flipped SU(5) x U(1) supersymmetric GUT which incorporates an economical and natural mechanism for splitting Higgs doublets and triplets, and can be derived from string theory. Using experimental values of sin/sup 2/theta/sub W/ and the strong QCD coupling, we estimate the grand unification scale M/sub G/, where the strong and weak coupling strengths are equal, and the superunification scale M/sub SU/, where all couplings are equal. We find typical values of M/sub G/ approx. = 10/sup 15/ to 10/sup 17/ GeV, with M/sub SU/ somewhat higher and close to the value suggested by string models. We discuss different mechanisms for baryon decay, finding that the dominant one is gauge-boson exchange giving rise to p -> e/sup +/ /sup 0/, anti /sup +/ and n -> e/sup +/ /sup -/, anti /sup 0/ with partial lifetimes approx. = 10/sup 35+-2/ y. We show that a large GUT symmetry-breaking scale M/sub G/ is naturally generated by radiative corrections to the effective potential if a small amount approx. = m/sub W/ of soft supersymmetry breaking is generated dynamically at a large scale. We analyze the low-energy effective theory obtained using the renormalization group equations, demonstrating that electroweak symmetry breaking is obtained if m/sub t/ approx. = 60 to 90 GeV. We analyze the spectrum of sparticles, with particular attention to neutralinos.
Bozeman, Trevor C; Nanjunda, Rupesh; Tang, Chenhong; Liu, Yang; Segerman, Zachary J; Zaleski, Paul A; Wilson, W David; Hecht, Sidney M
2012-10-31
Recent studies involving DNAs bound strongly by bleomycins have documented that such DNAs are degraded by the antitumor antibiotic with characteristics different from those observed when studying the cleavage of randomly chosen DNAs in the presence of excess Fe·BLM. In the present study, surface plasmon resonance has been used to characterize the dynamics of BLM B(2) binding to a strongly bound hairpin DNA, to define the effects of Fe(3+), salt, and temperature on BLM-DNA interaction. One strong primary DNA binding site, and at least one much weaker site, were documented. In contrast, more than one strong cleavage site was found, an observation also made for two other hairpin DNAs. Evidence is presented for BLM equilibration between the stronger and weaker binding sites in a way that renders BLM unavailable to other, less strongly bound DNAs. Thus, enhanced binding to a given site does not necessarily result in increased DNA degradation at that site; i.e., for strongly bound DNAs, the facility of DNA cleavage must involve other parameters in addition to the intrinsic rate of C-4' H atom abstraction from DNA sugars.
Metastability and avalanche dynamics in strongly correlated gases with long-range interactions
Hruby, Lorenz; Dogra, Nishant; Landini, Manuele; Donner, Tobias; Esslinger, Tilman
2018-03-01
We experimentally study the stability of a bosonic Mott insulator against the formation of a density wave induced by long-range interactions and characterize the intrinsic dynamics between these two states. The Mott insulator is created in a quantum degenerate gas of 87-Rubidium atoms, trapped in a 3D optical lattice. The gas is located inside and globally coupled to an optical cavity. This causes interactions of global range, mediated by photons dispersively scattered between a transverse lattice and the cavity. The scattering comes with an atomic density modulation, which is measured by the photon flux leaking from the cavity. We initialize the system in a Mott-insulating state and then rapidly increase the global coupling strength. We observe that the system falls into either of two distinct final states. One is characterized by a low photon flux, signaling a Mott insulator, and the other is characterized by a high photon flux, which we associate with a density wave. Ramping the global coupling slowly, we observe a hysteresis loop between the two states—a further signature of metastability. A comparison with a theoretical model confirms that the metastability originates in the competition between short- and global-range interactions. From the increasing photon flux monitored during the switching process, we find that several thousand atoms tunnel to a neighboring site on the timescale of the single-particle dynamics. We argue that a density modulation, initially forming in the compressible surface of the trapped gas, triggers an avalanche tunneling process in the Mott-insulating region.
Gravity as a dynamical consequence of the strong, weak, and electromagnetic interactions
International Nuclear Information System (INIS)
Zee, A.
1981-12-01
A coherent and reasonable account of gravitational physics is shown to be possible. The three non-gravitational interactions are described by a scale and conformal invariant and asymptotically free Yang-Mills theory with massless fermions. Conformal invariance is required so that the gravitational sector of the theory is given by the Weyl action. The theory is renormalizable and has a unitary S-matrix. Possible breakdown of causality is observable only at the Planck length. In this theory, Einstein's theory of gravity is induced as an effective long-distance theory. An R 2 term is also induced with a finite and physically desired sign
Probing non nucleonic degrees of freedom with strong and electromagnetic interactions
International Nuclear Information System (INIS)
Frois, B.
1985-10-01
In this talk, I would like to examine our present view on non-nucleonic degrees of freedom with a few typical experimental results obtained recently both with hadronic and electromagnetic probes at intermediate energies. It is the first generation of experimental data which has probed mesonic degrees of freedom with a spatial resolution of the order of 0.5 fm. This has made possible for example the measurement of the size of the pion-nucleon interaction region. This is very stimulating progress and we begin to have a coherent overview on the various reaction mechanisms which are induced by hadronic and electromagnetic probes
International Nuclear Information System (INIS)
Yu Zengqiang; Zhai Hui; Zhang Shizhong
2011-01-01
We study the properties of dilute bosons immersed in a single-component Fermi sea across a broad boson-fermion Feshbach resonance. The stability of the mixture requires that the bare interaction between bosons exceeds a critical value, which is a universal function of the boson-fermion scattering length, and exhibits a maximum in the unitary region. We calculate the quantum depletion, momentum distribution, and the boson contact parameter across the resonance. The transition from condensate to molecular Fermi gas is also discussed.
Energy Technology Data Exchange (ETDEWEB)
Schriber, Jeffrey B.; Evangelista, Francesco A. [Department of Chemistry and Cherry L. Emerson Center for Scientific Computation, Emory University, Atlanta, Georgia 30322 (United States)
2016-04-28
We introduce a new procedure for iterative selection of determinant spaces capable of describing highly correlated systems. This adaptive configuration interaction (ACI) determines an optimal basis by an iterative procedure in which the determinant space is expanded and coarse grained until self-consistency. Two importance criteria control the selection process and tune the ACI to a user-defined level of accuracy. The ACI is shown to yield potential energy curves of N{sub 2} with nearly constant errors, and it predicts singlet-triplet splittings of acenes up to decacene that are in good agreement with the density matrix renormalization group.
Energy Technology Data Exchange (ETDEWEB)
Daily, Michael D.; Baer, Marcel D.; Mundy, Christopher J.
2016-03-10
The description of peptides and the use of molecular dynamics simulations to refine structures and investigate the dynamics on an atomistic scale are well developed. Through a consensus in this community over multiple decades, parameters were developed for molecular interactions that only require the sequence of amino-acids and an initial guess for the three-dimensional structure. The recent discovery of peptoids will require a retooling of the currently available interaction potentials in order to have the same level of confidence in the predicted structures and pathways as there is presently in the peptide counterparts. Here we present modeling of peptoids using a combination of ab initio molecular dynamics (AIMD) and atomistic resolution classical forcefield (FF) to span the relevant time and length scales. To properly account for the dominant forces that stabilize ordered structures of peptoids, namely steric-, electrostatic, and hydrophobic interactions mediated through sidechain-sidechain interactions in the FF model, those have to be first mapped out using high fidelity atomistic representations. A key feature here is not only to use gas phase quantum chemistry tools, but also account for solvation effects in the condensed phase through AIMD. One major challenge is to elucidate ion binding to charged or polar regions of the peptoid and its concomitant role in the creation of local order. Here, similar to proteins, a specific ion effect is observed suggesting that both the net charge and the precise chemical nature of the ion will need to be described. MDD was supported by MS3 (Materials Synthesis and Simulation Across Scales) Initiative at Pacific Northwest National Laboratory. Research was funded by the Laboratory Directed Research and Development program at Pacific Northwest National Laboratory. MDB acknowledges support from US Department of Energy, Office of Science, Office of Basic Energy Sciences, Division of Material & Engineering. CJM acknowledges
Wan, Sijie; Peng, Jingsong; Li, Yuchen; Hu, Han; Jiang, Lei; Cheng, Qunfeng
2015-10-27
Graphene is the strongest and stiffest material, leading to the development of promising applications in many fields. However, the assembly of graphene nanosheets into macrosized nanocomposites for practical applications remains a challenge. Nacre in its natural form sets the "gold standard" for toughness and strength, which serves as a guide to the assembly of graphene nanosheets into high-performance nanocomposites. Here we show the strong, tough, conductive artificial nacre based on graphene oxide through synergistic interactions of hydrogen and covalent bonding. Tensile strength and toughness was 4 and 10 times higher, respectively, than that of natural nacre. The exceptional integrated strong and tough artificial nacre has promising applications in aerospace, artificial muscle, and tissue engineering, especially for flexible supercapacitor electrodes due to its high electrical conductivity. The use of synergistic interactions is a strategy for the development of high-performance nanocomposites.
Equilibration of a strongly interacting plasma: holographic analysis of local and nonlocal probes
Directory of Open Access Journals (Sweden)
Bellantuono Loredana
2016-01-01
Full Text Available The relaxation of a strongly coupled plasma towards the hydrodynamic regime is studied by analyzing the evolution of local and nonlocal observables in the holographic approach. The system is driven in an initial anisotropic and far-from equilibrium state through an impulsive time-dependent deformation (quench of the boundary spacetime geometry. Effective temperature and entropy density are related to the position and area of a black hole horizon, which has formed as a consequence of the distortion. The behavior of stress-energy tensor, equal-time correlation functions and Wilson loops of different shapes is examined, and a hierarchy among their thermalization times emerges: probes involving shorter length scales thermalize faster.
Nonlinear interaction of charged particles with strong laser pulses in a gaseous media
Directory of Open Access Journals (Sweden)
H. K. Avetissian
2007-07-01
Full Text Available The charged particles nonlinear dynamics in the field of a strong electromagnetic wave pulse of finite duration and certain form of the envelope, in the refractive medium with a constant and variable refraction indexes, is investigated by means of numerical integration of the classical relativistic equations of motion. The particle energy dependence on the pulse intensity manifests the nonlinear threshold phenomenon of a particle reflection and capture by actual laser pulses in dielectric-gaseous media that takes place for a plane electromagnetic wave in the induced Cherenkov process. Laser acceleration of the particles in the result of the reflection from the pulse envelope and in the capture regime with the variable refraction index along the pulse propagation direction is investigated.
International Nuclear Information System (INIS)
Bulanov, S.V.; Esirkepov, T.Zh.; Kamenets, F.F.; Naumova, N.M.
1995-01-01
The paper presents the results of a numeric modelling of the propagation of ultra short relativistically strong laser pulses in a rarefied plasma by the 'particle in cell'. Primary attention is paid to the process of the formation of electromagnetic solitons which can not be described in the approximation of envelopes. It is found that under certain conditions a significant portion of pulse energy can transform is solitons. The soliton excitation mechanism is related to a decrease of local frequency of electromagnetic radiation due to the generation of wave plasma waves. From one soliton to a stub of solitons can be generated in the wake of a relatively long pulse depending on the parameters of laser pulse in plasma. Particles are effectively accelerated forwards radiation propagation in the electric field of wake plasma waves. 22 refs., 7 figs
Strongly coupled interaction between a ridge of fluid and an inviscid airflow
Paterson, C.
2015-07-01
© 2015 AIP Publishing LLC. The behaviour of a steady thin sessile or pendent ridge of fluid on an inclined planar substrate which is strongly coupled to the external pressure gradient arising from an inviscid airflow parallel to the substrate far from the ridge is described. When the substrate is nearly horizontal, a very wide ridge can be supported against gravity by capillary and/or external pressure forces; otherwise, only a narrower (but still wide) ridge can be supported. Classical thin-aerofoil theory is adapted to obtain the governing singular integro-differential equation for the profile of the ridge in each case. Attention is focused mainly on the case of a very wide sessile ridge. The effect of strengthening the airflow is to push a pinned ridge down near to its edges and to pull it up near to its middle. At a critical airflow strength, the upslope contact angle reaches the receding contact angle at which the upslope contact line de-pins, and continuing to increase the airflow strength beyond this critical value results in the de-pinned ridge becoming narrower, thicker, and closer to being symmetric in the limit of a strong airflow. The effect of tilting the substrate is to skew a pinned ridge in the downslope direction. Depending on the values of the advancing and receding contact angles, the ridge may first de-pin at either the upslope or the downslope contact line but, in general, eventually both contact lines de-pin. The special cases in which only one of the contact lines de-pins are also considered. It is also shown that the behaviour of a very wide pendent ridge is qualitatively similar to that of a very wide sessile ridge, while the important qualitative difference between the behaviour of a very wide ridge and a narrower ridge is that, in general, for the latter one or both of the contact lines may never de-pin.
DEFF Research Database (Denmark)
Loft, N. J. S.; Marchukov, O. V.; Petrosyan, D.
2016-01-01
We have developed an efficient computational method to treat long, one-dimensional systems of strongly-interacting atoms forming self-assembled spin chains. Such systems can be used to realize many spin chain model Hamiltonians tunable by the external confining potential. As a concrete...... demonstration, we consider quantum state transfer in a Heisenberg spin chain and we show how to determine the confining potential in order to obtain nearly-perfect state transfer....
International Nuclear Information System (INIS)
Bobrov, V.B.; Triger, S.A.
1994-01-01
The effective collision frequency method developed earlier by the authors for Coulomb systems characterized by strong interion interaction is developed further. An explicit expression is obtained for the effective electron collision frequency on the basis of the exact diagram representation obtained in Part I and the use of the model of a one-component plasma as initial approximation. The description of plasma structure in the corresponding approximation is considered. 25 refs
Cao, G.; Terzic, J.; Zhao, H. D.; Zheng, H.; De Long, L. E.; Riseborough, Peter S.
2018-01-01
Electrical control of structural and physical properties is a long-sought, but elusive goal of contemporary science and technology. We demonstrate that a combination of strong spin-orbit interactions (SOI) and a canted antiferromagnetic Mott state is sufficient to attain that goal. The antiferromagnetic insulator Sr2IrO4 provides a model system in which strong SOI lock canted Ir magnetic moments to IrO6 octahedra, causing them to rigidly rotate together. A novel coupling between an applied electrical current and the canting angle reduces the Néel temperature and drives a large, nonlinear lattice expansion that closely tracks the magnetization, increases the electron mobility, and precipitates a unique resistive switching effect. Our observations open new avenues for understanding fundamental physics driven by strong SOI in condensed matter, and provide a new paradigm for functional materials and devices.
International Nuclear Information System (INIS)
Laat, C.T.A.M. de; Taal, A.; Duinker, W.; Konijn, J.; Petitjean, C.; Reist, H.W.; Mueller, W.; Commission of the European Communities, Geel
1987-01-01
The X-ray spectrum of muonic and pionic 237 Np has been investigated with muons and pions stopped in a NpO 2 target. The nuclear spectroscopic quadrupole moment was determined to be Q=3.886±0.006 b from the splittings of the muonic 5g→4f hyperfine complexes. The B(E2)↓-values for the first and second excited states were evaluated as 3.17±0.08 and 2.77±0.10 e 2 b 2 , respectively. A comparison between the muonic and pionic 5g→4f hyperfine complexes yields the strong interaction parameter for the pionic 4f state. For the first time a change of sign as function of Z for the strong interaction quadrupole shift ε 2 (4f) has been observed. The standard optical model predictions agree reasonably well with the measured strong interaction monopole shift, ε 0 (4f), and width, Γ 0 (4f), while they disagree with the experimental value for ε 2 . A stronger s-wave repulsion in the optical potential could explain this effect. (orig.)
International Nuclear Information System (INIS)
Armour, E A G; Liu, Y; Vigier, A
2005-01-01
The aim of experimentalists currently working on the preparation of antihydrogen is to trap it at very low temperatures so that its properties can be studied. Any process that can lead to loss of antihydrogen is thus of great concern to them. In view of this, we have carried out a calculation of the antiproton annihilation cross section in very low-energy hydrogen-antihydrogen scattering using a complex potential to represent the strong interaction that brings about the annihilation. The potential takes into account the isotopic spin state of the proton and the antiproton and the possibility that they may be in either a singlet or a triplet spin state. The results for the annihilation cross section and the percentage change in the elastic cross section due to the inclusion of the strong interaction are similar to those obtained in a recent calculation (Jonsell et al 2004 J. Phys. B: At. Mol. Opt. Phys. 37 1195), using an effective range expansion. They are smaller by a factor of 2 and 3, respectively, than those obtained in an earlier calculation (Voronin and Carbonell 2001 Nucl. Phys. A 689 529c), using a coupled channel method and a complex strong interaction potential. (letter to the editor)
International Nuclear Information System (INIS)
Caldirola, P.; Recami, E.
1978-01-01
By assuming covariance of physical laws under (discrete) dilatations, strong and gravitational interactions have been described in a unified way. In terms of the (additional, discrete) ''dilatational'' degree of freedom, our cosmos as well as hadrons can be considered as different states of the same system, or rather as similar systems. Moreover, a discrete hierarchy can be defined of ''universes'' which are governed by force fields with strengths inversely proportional to the ''universe'' radii. Inside each ''universe'' an equivalence principle holds, so that its characteristic field can be geometrized there. It is thus easy to derive a whole ''numerology'', i.e. relations among numbers analogous to the so-called Weyl-Eddington-Dirac ''large numbers''. For instance, the ''Planck mass'' happens to be nothing but the (average) magnitude of the strong charge of the hadron quarks. However, our ''numerology'' connects the (gravitational) macrocosmos with the (strong) microcosmos, rather than with the electromagnetic ones (as, e.g., in Dirac's version). Einstein-type scaled equations (with ''cosmological'' term) are suggested for the hadron interior, which - incidentally - yield a (classical) quark confinement in a very natural way and are compatible with the ''asymptotic freedom''. At last, within a ''bi-scale'' theory, further equations are proposed that provide a priori a classical field theory of strong interactions (between different hadrons). The relevant sections are 5.2, 7 and 8. (author)
On a low energy, strong interaction model, unifying mesons and baryons
International Nuclear Information System (INIS)
Kalafatis, D.
1993-03-01
This thesis is concerned with the study of a unified theory of mesons and baryons. An effective Lagrangian with the low mass mesons, generalizing the Skyrme model, is constructed. The vector meson fields are introduced as gauge fields in the linear sigma model instead of the non linear sigma model. Topological soliton solutions of the model are examined and the nucleon-nucleon interaction in the product approximation is investigated. The leading correction to the classical skyrmion mass, the Casimir energy, is evaluated. The problem of the stability of topological solitons when vector fields enter the chiral Lagrangian is also studied. It is shown that the soliton is stable in very much the same way as with the ωmeson and that peculiar classical doublet solutions do not exist
RADIO AND X-RAY OBSERVATIONS OF SN 2006jd: ANOTHER STRONGLY INTERACTING TYPE IIn SUPERNOVA
Energy Technology Data Exchange (ETDEWEB)
Chandra, Poonam [Department of Physics, Royal Military College of Canada, Kingston, ON K7K 7B4 (Canada); Chevalier, Roger A.; Irwin, Christopher M. [Department of Astronomy, University of Virginia, P.O. Box 400325, Charlottesville, VA 22904-4325 (United States); Chugai, Nikolai [Institute of Astronomy of Russian Academy of Sciences, Pyatnitskaya Street 48, 109017 Moscow (Russian Federation); Fransson, Claes [Department of Astronomy, Stockholm University, AlbaNova, SE-106 91 Stockholm (Sweden); Soderberg, Alicia M. [Smithsonian Astrophysical Observatory, 60 Garden Street, MS-20, Cambridge, MA 02138 (United States); Chakraborti, Sayan [Department of Astronomy and Astrophysics, Tata Institute of Fundamental Research, 1 Homi Bhabha Road, Colaba, Mumbai 400005 (India); Immler, Stefan, E-mail: Poonam.Chandra@rmc.ca [Astrophysics Science Division, NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States)
2012-08-20
We report four years of radio and X-ray monitoring of the Type IIn supernova SN 2006jd at radio wavelengths with the Very Large Array, Giant Metrewave Radio Telescope, and Expanded Very Large Array; at X-ray wavelengths with Chandra, XMM-Newton, and Swift-XRT. We assume that the radio and X-ray emitting particles are produced by shock interaction with a dense circumstellar medium. The radio emission shows an initial rise that can be attributed to free-free absorption by cool gas mixed into the nonthermal emitting region; external free-free absorption is disfavored because of the shape of the rising light curves and the low gas column density inferred along the line of sight to the emission region. The X-ray luminosity implies a preshock circumstellar density {approx}10{sup 6} cm{sup -3} at a radius r {approx} 2 Multiplication-Sign 10{sup 16} cm, but the column density inferred from the photoabsorption of X-rays along the line of sight suggests a significantly lower density. The implication may be an asymmetry in the interaction. The X-ray spectrum shows Fe line emission at 6.9 keV that is stronger than is expected for the conditions in the X-ray emitting gas. We suggest that cool gas mixed into the hot gas plays a role in the line emission. Our radio and X-ray data both suggest the density profile is flatter than r{sup -2} because of the slow evolution of the unabsorbed emission.
Interaction of N-hydroxyurea with strong proton donors: HCl and HF
Sałdyka, Magdalena
2014-11-01
An infrared spectroscopic and MP2/6-311++G(2d,2p) study of strong hydrogen bonded complexes of N-hydroxyurea (NH2CONHOH) with hydrogen halides (HCl and HF) trapped in solid argon matrices is reported. 1:1 and 1:2 complexes between N-hydroxyurea and hydrogen chloride, hydrogen fluoride have been identified in the NH2CONHOH/HCl/Ar, NH2CONHOH/HF/Ar matrices, respectively; their structures were determined by comparison of the spectra with the results of calculations. In the 1:1 complexes, identified for both hydrogen halide molecules, the cyclic structure stabilized by the X-H⋯O and N-H⋯X bonds is present; for the NH2CONHOH⋯HF system another isomeric 1:1 complex is also observed. Two 1:2 complexes were identified for the N-hydroxyurea-hydrogen chloride system characterised by the Cl-H⋯O and N-H⋯Cl bonds. The results of the study evidence that N-hydroxyurea is an oxygen base in the gas-phase with the carbonyl group as the strongest proton acceptor centre in the molecule.
Inelastic strong interactions at high energies. Annual progress report, June 1, 1979-May 1, 1980
International Nuclear Information System (INIS)
Suranyi, P.
1980-02-01
Investigations in the area of Grand Unified Field Theories were begun. Various ways of breaking the SU(5) symmetric theory of Georgi and Glashow were studied. As usual, an approx. 24 of Higgs breaks the symmetry from SU(5) to SU(3)/sub c/xSU(2)xU(1). It was found that an approx. 45 of Higgs is acceptable for breaking the symmetry from SU(3)/sub c/xSU(2)xU(1) to SU(3)/sub c/xU(1)/sub em/. In addition phenomenologically correct quark-lepton mass ratios are obtained by use of renormalization-group techniques if there are 6 generations of particles in the theory. Efforts directed at the development of approximate methods for extracting information from quantum field theories were continued. The quantum mechanics of polynomial potentials as a model for quantum field theories was investigated. A perturbation expansion for the energy levels and wave functions was constructed and has been proven to be convergent for arbitrary values of the coupling constants, in contrast to ordinary perturbation expansions that have a zero radius of convergence. The physical significance of the new perturbation expansions was explored both in the weak and strong coupling limits
DFT Study of dimers of dimethyl sulfoxide in gas phase
Directory of Open Access Journals (Sweden)
Reza Fazaeli
2014-10-01
Full Text Available Density functional (DFT calculations at M05-2x/aug-cc-pVDZ level were used to analyze the interactions between dimethyl sulfoxide (DMSO dimers. The structures obtained have been ana-lyzed with the Atoms in Molecules (AIMs and Natural Bond Orbital (NBO methodologies. Four minima were located on the potential energy surface of the dimers. Three types of interac-tions are observed, CH•••O, CH•••S hydrogen bonds and orthogonal interaction between the lone pair of the oxygen with the electron-deficient region of the sulfur atom. Stabilization energies of dimers including BSSE and ZPE are in the range 27–40 kJmol-1. The most stable conformers of dimers at DFT level is cyclic structure with antiparallel orientation of S=O groups pairing with three C–H∙∙∙O and a S∙∙∙O interactions.
International Nuclear Information System (INIS)
Yang, Yi; Steup, M.
1990-01-01
From leaves of Spinacia oleracea L. or from Pisum sativum L. and from cotyledons of germinating pea seeds a high molecular weight polysaccharide fraction was isolated. The apparent size of the fraction, as determined by gel filtration, was similar to that of dextran blue. Following acid hydrolysis the monomer content of the polysaccharide preparation was studied using high pressure liquid and thin layer chromatography. Glucose, galactose, arabinose, and ribose were the main monosaccharide compounds. The native polysaccharide preparation interacted strongly with the cytosolic isozyme of phosphorylase (EC 2.4.1.1). Interaction with the plastidic phosphorylase isozyme(s) was by far weaker. Interaction with the cytosolic isozyme was demonstrated by affinity electrophoresis, kinetic measurements, and by 14 C-labeling experiments in which the glucosyl transfer from [ 14 C]glucose 1-phosphate to the polysaccharide preparation was monitored
International Nuclear Information System (INIS)
Sherman, A.; Schreiber, M.
1995-01-01
We use the Eliashberg formalism for calculating T c in a model of cuprate perovskites with pairing mediated by both magnons and apex-oxygen vibrations. The influence of strong correlations on the energy spectrum is taken into account in the spin-wave approximation. It is shown that the hole-magnon interaction alone cannot yield high T c . But together with a moderate hole-phonon interaction it does lead to d-wave superconductivity at temperatures and hole concentrations observed in cuprates. High T c are connected with a large density of states due to extended Van Hove singularities, a conformity of the two interactions for the d symmetry, and high phonon frequencies
Effects of Dimers on Cooperation in the Spatial Prisoner's Dilemma Game
International Nuclear Information System (INIS)
Li Haihong; Cheng Hongyan; Dai Qionglin; Ju Ping; Yang Junzhong; Zhang Mei
2011-01-01
We investigate the evolutionary prisoner's dilemma game in structured populations by introducing dimers, which are defined as that two players in each dimer always hold a same strategy. We find that influences of dimers on cooperation depend on the type of dimers and the population structure. For those dimers in which players interact with each other, the cooperation level increases with the number of dimers though the cooperation improvement level depends on the type of network structures. On the other hand, the dimers, in which there are not mutual interactions, will not do any good to the cooperation level in a single community, but interestingly, will improve the cooperation level in a population with two communities. We explore the relationship between dimers and self-interactions and find that the effects of dimers are similar to that of self-interactions. Also, we find that the dimers, which are established over two communities in a multi-community network, act as one type of interaction through which information between communities is communicated by the requirement that two players in a dimer hold a same strategy. (general)
Powers, Lydia
The National Museum of Play at The Strong's Dancing Wings Butterfly Garden is a tropical rainforest that allows visitors to step into the world of butterflies, but lacks a more comprehensive educational element to teach visitors additional information about butterflies. Flutter-by Interactive Butterfly is a thesis project designed to enhance younger visitors' experience of the Dancing Wings Butterfly Garden with an interactive educational application that aligns with The Strong's mission of encouraging learning, creativity, and discovery. This was accomplished through a series of fun and educational games and animations, designed for use as a kiosk outside the garden and as a part of The Strong's website. Content, planning, and organization of this project has been completed through research and observation of the garden in the following areas: its visitors, butterflies, best usability practices for children, and game elements that educate and engage children. Flutter-by Interactive Butterfly teaches users about the butterfly's life cycle, anatomy, and characteristics as well as their life in the Dancing Wings Butterfly Garden. Through the use of the design programs Adobe Illustrator, Flash, and After Effects; the programming language ActionScript3.0; a child-friendly user interface and design; audio elements and user takeaways, Flutter-by Interactive Butterfly appeals to children of all ages, interests, and learning styles. The project can be viewed at lydiapowers.com/Thesis/FlutterByButterfly.html
Exploring effects of strong interactions in enhancing masses of dynamical origin
International Nuclear Information System (INIS)
Cabo Montes de Oca, Alejandro
2011-01-01
A previous study of the dynamical generation of masses in massless QCD is considered from another viewpoint. The quark mass is assumed to have a dynamical origin and is substituted for by a scalar field without self-interaction. The potential for the new field background is evaluated up to two loops. Expressing the running coupling in terms of the scale parameter μ, the potential minimum is chosen to fix m top =175 GeV when μ 0 =498 MeV. The second derivative of the potential predicts a scalar field mass of 126.76 GeV. This number is close to the value 114 GeV, which preliminary data taken at CERN suggested to be associated with the Higgs particle. However, the simplifying assumptions limit the validity of the calculations done, as indicated by the large value of α=(g 2 )/(4π)=1.077 obtained. However, supporting statements about the possibility of improving the scheme come from the necessary inclusion of weak and scalar field couplings and mass counterterms in the renormalization procedure, in common with the seemingly needed consideration of the massive W and Z fields, if the real conditions of the SM model are intended to be approached. (orig.)
Some issues linked to the description of systems in strong interaction
International Nuclear Information System (INIS)
Theussl, L.
2001-06-01
In the first part of this work we have dealt with some issues that are relevant in the area of nucleonic resonances within different constituent quark models. In this context we have concentrated on the theoretical description of Pi and Nu decays for N and Delta resonances. The results obtained point to the necessity of a more microscopic description of the dynamics which is at the same time responsible for the binding of quarks inside baryons and the decay of the latter ones. In the second part we have contributed to the study of crossed two-boson exchanges in the Bethe-Salpeter equation as well as to the investigation of different three-dimensional approaches that follow from the Bethe-Salpeter equation in a certain non-relativistic reduction scheme. These one include in particular an equation whose interaction depends on the total energy of the system. It was shown that such an equation is able to account for a certain number of properties of Bethe-Salpeter equation, in particular, that there also arise abnormal solutions in such an approach. (author)
Electron Fluid Description of Wave-Particle Interactions in Strong Buneman Turbulence
Che, Haihong
2013-10-01
To understand the nature of anomalous resistivity in magnetic reconnection, we investigate turbulence-induced momentum transport and energy dissipation associated with electron heating in Buneman instability. Using 3D particle-in-cell simulations, we find that the macroscopic effects generated by wave-particle interactions can be described by a set of electron fluid equations. These equations show that the energy dissipation and momentum transports in Buneman instability are locally quasi-static but globally non-static and irreversible. Turbulence drag dissipates both the bulk energy of electron streams and the associated magnetic energy. The decrease of magnetic field maintains an inductive electric field that re-accelerates electrons. The net loss of streaming energy is converted into electron heat and increases the electron Boltzmann entropy. The growth of self-sustained Buneman waves satisfies a Bernoulli-like equation which relates the turbulence-induced convective momentum transport and thermal momentum transport. Electron trapping and de-trapping drives local momentum transports, while phase mixing converts convective momentum into thermal momentum.These two local momentum transports sustain the Buneman waves and act as the micro-macro link in the anomalous heating process. This research is supported by the NASA Postdoctoral Program at NASA/GSFC administered by Oak Ridge Associated Universities through a contract with NASA.
Directed diffusion of reconstituting dimers
International Nuclear Information System (INIS)
Barma, Mustansir; Grynberg, Marcelo D; Stinchcombe, Robin B
2007-01-01
We discuss the dynamical aspects of an asymmetric version of assisted diffusion of hard core particles on a ring studied by Menon et al (1997 J. Stat. Phys. 86 1237). The asymmetry brings in phenomena like kinematic waves and effects of the Kardar-Parisi-Zhang non-linearity, which combine with the feature of strongly broken ergodicity, a characteristic of the model. A central role is played by a single non-local invariant, the irreducible string, whose interplay with the driven motion of reconstituting dimers, arising from the assisted hopping, determines the asymptotic dynamics and scaling regimes. These are investigated both analytically and numerically through sector-dependent mappings to the asymmetric simple exclusion process
Directed diffusion of reconstituting dimers
Energy Technology Data Exchange (ETDEWEB)
Barma, Mustansir [Department of Theoretical Physics, Tata Institute of Fundamental Research, Mumbai 400005 (India); Grynberg, Marcelo D [Departamento de Fisica, Universidad Nacional de La Plata (1900) La Plata (Argentina); Stinchcombe, Robin B [Isaac Newton Institute for Mathematical Sciences, 20 Clarkson Road, Cambridge CB3 0EH (United Kingdom)
2007-02-14
We discuss the dynamical aspects of an asymmetric version of assisted diffusion of hard core particles on a ring studied by Menon et al (1997 J. Stat. Phys. 86 1237). The asymmetry brings in phenomena like kinematic waves and effects of the Kardar-Parisi-Zhang non-linearity, which combine with the feature of strongly broken ergodicity, a characteristic of the model. A central role is played by a single non-local invariant, the irreducible string, whose interplay with the driven motion of reconstituting dimers, arising from the assisted hopping, determines the asymptotic dynamics and scaling regimes. These are investigated both analytically and numerically through sector-dependent mappings to the asymmetric simple exclusion process.
Two-fluid description of wave-particle interactions in strong Buneman turbulence
Energy Technology Data Exchange (ETDEWEB)
Che, H. [NASA/Goddard Space Flight Center, Greenbelt, Maryland 20771 (United States)
2014-06-15
To understand the nature of anomalous resistivity in magnetic reconnection, we investigate turbulence-induced momentum transport and energy dissipation while a plasma is unstable to the Buneman instability in force-free current sheets. Using 3D particle-in-cell simulations, we find that the macroscopic effects generated by wave-particle interactions in Buneman instability can be approximately described by a set of electron fluid equations. We show that both energy dissipation and momentum transport along electric current in the current layer are locally quasi-static, but globally dynamic and irreversible. Turbulent drag dissipates both the streaming energy of the current sheet and the associated magnetic energy. The net loss of streaming energy is converted into the electron component heat conduction parallel to the magnetic field and increases the electron Boltzmann entropy. The growth of self-sustained Buneman waves satisfies a Bernoulli-like equation that relates the turbulence-induced convective momentum transport and thermal momentum transport. Electron trapping and de-trapping drive local momentum transports, while phase mixing converts convective momentum into thermal momentum. The drag acts like a micro-macro link in the anomalous heating processes. The decrease of magnetic field maintains an inductive electric field that re-accelerates electrons, but most of the magnetic energy is dissipated and converted into the component heat of electrons perpendicular to the magnetic field. This heating process is decoupled from the heating of Buneman instability in the current sheets. Ion heating is weak but ions play an important role in assisting energy exchanges between waves and electrons. Cold ion fluid equations together with our electron fluid equations form a complete set of equations that describes the occurrence, growth, saturation and decay of the Buneman instability.
Two-fluid description of wave-particle interactions in strong Buneman turbulence
Che, H.
2014-06-01
To understand the nature of anomalous resistivity in magnetic reconnection, we investigate turbulence-induced momentum transport and energy dissipation while a plasma is unstable to the Buneman instability in force-free current sheets. Using 3D particle-in-cell simulations, we find that the macroscopic effects generated by wave-particle interactions in Buneman instability can be approximately described by a set of electron fluid equations. We show that both energy dissipation and momentum transport along electric current in the current layer are locally quasi-static, but globally dynamic and irreversible. Turbulent drag dissipates both the streaming energy of the current sheet and the associated magnetic energy. The net loss of streaming energy is converted into the electron component heat conduction parallel to the magnetic field and increases the electron Boltzmann entropy. The growth of self-sustained Buneman waves satisfies a Bernoulli-like equation that relates the turbulence-induced convective momentum transport and thermal momentum transport. Electron trapping and de-trapping drive local momentum transports, while phase mixing converts convective momentum into thermal momentum. The drag acts like a micro-macro link in the anomalous heating processes. The decrease of magnetic field maintains an inductive electric field that re-accelerates electrons, but most of the magnetic energy is dissipated and converted into the component heat of electrons perpendicular to the magnetic field. This heating process is decoupled from the heating of Buneman instability in the current sheets. Ion heating is weak but ions play an important role in assisting energy exchanges between waves and electrons. Cold ion fluid equations together with our electron fluid equations form a complete set of equations that describes the occurrence, growth, saturation and decay of the Buneman instability.
Two-fluid description of wave-particle interactions in strong Buneman turbulence
International Nuclear Information System (INIS)
Che, H.
2014-01-01
To understand the nature of anomalous resistivity in magnetic reconnection, we investigate turbulence-induced momentum transport and energy dissipation while a plasma is unstable to the Buneman instability in force-free current sheets. Using 3D particle-in-cell simulations, we find that the macroscopic effects generated by wave-particle interactions in Buneman instability can be approximately described by a set of electron fluid equations. We show that both energy dissipation and momentum transport along electric current in the current layer are locally quasi-static, but globally dynamic and irreversible. Turbulent drag dissipates both the streaming energy of the current sheet and the associated magnetic energy. The net loss of streaming energy is converted into the electron component heat conduction parallel to the magnetic field and increases the electron Boltzmann entropy. The growth of self-sustained Buneman waves satisfies a Bernoulli-like equation that relates the turbulence-induced convective momentum transport and thermal momentum transport. Electron trapping and de-trapping drive local momentum transports, while phase mixing converts convective momentum into thermal momentum. The drag acts like a micro-macro link in the anomalous heating processes. The decrease of magnetic field maintains an inductive electric field that re-accelerates electrons, but most of the magnetic energy is dissipated and converted into the component heat of electrons perpendicular to the magnetic field. This heating process is decoupled from the heating of Buneman instability in the current sheets. Ion heating is weak but ions play an important role in assisting energy exchanges between waves and electrons. Cold ion fluid equations together with our electron fluid equations form a complete set of equations that describes the occurrence, growth, saturation and decay of the Buneman instability
International Nuclear Information System (INIS)
Voskresenskaya, O.O.
2002-01-01
It is shown that the relations between probabilities of A 2π -atoms creation in ns-states, derived with neglecting of the strong interaction between pions, hold practically unchanged if the strong interaction is taken into account in the first order of the perturbation theory. The formulation of Deser equation for the energy levels shift of the hadronic atoms (HA) is given in terms of the effective range of the strong interaction and relative correction to the Coulomb wave function of HA at origin, caused by the strong interaction. (author)
Cirhin up-regulates a canonical NF-{kappa}B element through strong interaction with Cirip/HIVEP1
Energy Technology Data Exchange (ETDEWEB)
Yu, Bin; Mitchell, Grant A. [Genetique Medicale, Centre de Recherche CHU Sainte-Justine, Departement de Pediatrie, Universite de Montreal, Montreal, QC (Canada); Richter, Andrea, E-mail: andrea.richter@umontreal.ca [Genetique Medicale, Centre de Recherche CHU Sainte-Justine, Departement de Pediatrie, Universite de Montreal, Montreal, QC (Canada)
2009-11-01
North American Indian childhood cirrhosis (NAIC/CIRH1A) is a severe autosomal recessive intrahepatic cholestasis. All NAIC patients have a homozygous mutation in CIRH1A that changes conserved Arg565 to Trp (R565W) in Cirhin, a nucleolar protein of unknown function. Subcellular localization is unaffected by the mutation. Yeast two-hybrid screening identified Cirip (Cirhin interaction protein) and found that interaction between Cirip and R565W-Cirhin was weakened. Co-immunoprecipitation of the two proteins from nuclear extracts of HeLa cells strongly supports the yeast two hybrid results. Cirip has essentially the same sequence as the C-terminal of HIVEP1, a regulator of a canonical NF-{kappa}B sequence. Since Cirip has the zinc fingers required for this interaction, we developed an in vitro assay based on this element in mammalian cells to demonstrate functional Cirhin-Cirip interaction. The strong positive effect of Cirip on the NF-{kappa}B sequence was further increased by both Cirhin and R565W-Cirhin. Importantly, the effect of R565W-Cirhin was weaker than that of the wild type protein. We observed increased levels of Cirhin-Cirip complex in nuclear extracts in the presence of this NF-{kappa}B sequence. Our hypothesis is that Cirhin is a transcriptional regulatory factor of this NF-{kappa}B sequence and could be a participant in the regulation of other genes with NF-{kappa}B responsive elements. Since the activities of genes regulated through NF-{kappa}B responsive elements are especially important during development, this interaction may be a key to explain the perinatal appearance of NAIC.
Cirhin up-regulates a canonical NF-κB element through strong interaction with Cirip/HIVEP1
International Nuclear Information System (INIS)
Yu, Bin; Mitchell, Grant A.; Richter, Andrea
2009-01-01
North American Indian childhood cirrhosis (NAIC/CIRH1A) is a severe autosomal recessive intrahepatic cholestasis. All NAIC patients have a homozygous mutation in CIRH1A that changes conserved Arg565 to Trp (R565W) in Cirhin, a nucleolar protein of unknown function. Subcellular localization is unaffected by the mutation. Yeast two-hybrid screening identified Cirip (Cirhin interaction protein) and found that interaction between Cirip and R565W-Cirhin was weakened. Co-immunoprecipitation of the two proteins from nuclear extracts of HeLa cells strongly supports the yeast two hybrid results. Cirip has essentially the same sequence as the C-terminal of HIVEP1, a regulator of a canonical NF-κB sequence. Since Cirip has the zinc fingers required for this interaction, we developed an in vitro assay based on this element in mammalian cells to demonstrate functional Cirhin-Cirip interaction. The strong positive effect of Cirip on the NF-κB sequence was further increased by both Cirhin and R565W-Cirhin. Importantly, the effect of R565W-Cirhin was weaker than that of the wild type protein. We observed increased levels of Cirhin-Cirip complex in nuclear extracts in the presence of this NF-κB sequence. Our hypothesis is that Cirhin is a transcriptional regulatory factor of this NF-κB sequence and could be a participant in the regulation of other genes with NF-κB responsive elements. Since the activities of genes regulated through NF-κB responsive elements are especially important during development, this interaction may be a key to explain the perinatal appearance of NAIC.
International Nuclear Information System (INIS)
Lundberg, Pernilla; Koskinen, Cecilia; Baldock, Paul A.; Loethgren, Hanna; Stenberg, Asa; Lerner, Ulf H.; Oldenborg, Per-Arne
2007-01-01
Physical interaction between the cell surface receptors CD47 and signal regulatory protein alpha (SIRPα) was reported to regulate cell migration, phagocytosis, cytokine production, and macrophage fusion. However, it is unclear if the CD47/SIRPα-interaction can also regulate macrophage colony-stimulating factor (M-CSF) and receptor activator of nuclear factor (NF)-κB ligand (RANKL)-stimulated formation of osteoclasts. Here, we show that functional blocking antibodies to either CD47 or SIRPα strongly reduced formation of multinucleated tartrate-resistant acid phosphatase (TRAP) + osteoclasts in cultures of murine hematopoietic cells, stimulated in vitro by M-CSF and RANKL. In addition, the numbers of osteoclasts formed in M-CSF/RANKL-stimulated bone marrow macrophage cultures from CD47 -/- mice were strongly reduced, and bones of CD47 -/- mice exhibited significantly reduced osteoclast numbers, as compared with wild-type controls. We conclude that the CD47/SIRPα interaction is important for M-CSF/RANKL-stimulated osteoclast formation both in vivo and in vitro, and that absence of CD47 results in decreased numbers of osteoclasts in CD47 -/- mice
Hargart, F.; Roy-Choudhury, K.; John, T.; Portalupi, S. L.; Schneider, C.; Höfling, S.; Kamp, M.; Hughes, S.; Michler, P.
2016-12-01
In this work we present an extensive experimental and theoretical investigation of different regimes of strong field light-matter interaction for cavity-driven quantum dot (QD) cavity systems. The electric field enhancement inside a high-Q micropillar cavity facilitates exceptionally strong interaction with few cavity photons, enabling the simultaneous investigation for a wide range of QD-laser detuning. In case of a resonant drive, the formation of dressed states and a Mollow triplet sideband splitting of up to 45 μeV is measured for a mean cavity photon number ≤slant 1. In the asymptotic limit of the linear AC Stark effect we systematically investigate the power and detuning dependence of more than 400 QDs. Some QD-cavity systems exhibit an unexpected anomalous Stark shift, which can be explained by an extended dressed 4-level QD model. We provide a detailed analysis of the QD-cavity systems properties enabling this novel effect. The experimental results are successfully reproduced using a polaron master equation approach for the QD-cavity system, which includes the driving laser field, exciton-cavity and exciton-phonon interactions.
International Nuclear Information System (INIS)
Gao Xianlong
2008-01-01
Using the Bethe-ansatz density-functional theory, we study a one-dimensional Hubbard model of confined attractively interacting fermions in the presence of a uniformly distributed disorder. The strongly correlated Luther-Emery nature of the attractive one-dimensional Hubbard model is fully taken into account as the reference system in the density-functional theory. The effects of the disorder are investigated on the atomic density waves in the weak-to-intermediate attractive interaction and on the spin-singlet dimers of doubly occupied sites in the strongly attractive regime. It is found that atomic density waves are sensitive to the disorder and the spin-singlet dimers of doubly occupied sites are quite unstable against the disorder. We also show that a very weak disorder could smear the singularities in the stiffness, thus, suppresses the spin-singlet pairs
Next-to-leading order strong interaction corrections to the ΔF = 2 effective Hamiltonian in the MSSM
International Nuclear Information System (INIS)
Ciuchini, Marco; Franco, E.; Guadagnoli, D.; Lubicz, Vittorio; Porretti, V.; Silvestrini, L.
2006-01-01
We compute the next-to-leading order strong interaction corrections to gluino-mediated ΔF = 2 box diagrams in the Minimal Supersymmetric Standard Model. These corrections are given by two loop diagrams which we have calculated in three different regularization schemes in the mass insertion approximation. We obtain the next-to-leading order Wilson coefficients of the ΔF = 2 effective Hamiltonian relevant for neutral meson mixings. We find that the matching scale uncertainty is largely reduced at the next-to-leading order, typically from about 10-15% to few percent
International Nuclear Information System (INIS)
Perali, A.; Palestini, F.; Pieri, P.; Strinati, G. C.; Stewart, J. T.; Gaebler, J. P.; Drake, T. E.; Jin, D. S.
2011-01-01
Wave-vector resolved radio frequency spectroscopy data for an ultracold trapped Fermi gas are reported for several couplings at T c , and extensively analyzed in terms of a pairing-fluctuation theory. We map the evolution of a strongly interacting Fermi gas from the pseudogap phase into a fully gapped molecular Bose gas as a function of the interaction strength, which is marked by a rapid disappearance of a remnant Fermi surface in the single-particle dispersion. We also show that our theory of a pseudogap phase is consistent with a recent experimental observation as well as with quantum Monte Carlo data of thermodynamic quantities of a unitary Fermi gas above T c .
International Nuclear Information System (INIS)
Faenov, A.; Dyakin, V.; Magunov, A.; Pikuz, T.; Skobelev, I.; Pikuz, S.; Pisarczyk, T.; Wolowski, J.; Zielinska, E.
1996-01-01
A dense jet of a plasma consisting of multiply charged ions was generated in the interaction of a laser plasma with a strong external axial magnetic field. It is shown that using the high-luminosity X-ray spectroheliograph technique allows to measure plasma emission spectra with 2-dimensional spatial resolution even in the cases when these spectra have small intensities. The X-ray spectroscopy and interferometry methods are used to measure plasma parameter distributions. The dependencies of N e (z) and T e (z) measured in this paper can be used to calculate the evolution of plasma ionization state during plasma expansion. The quasihomogeneous laser jet, which appears when a laser plasma interacts with an external magnetic field can be used not only to form an active medium of a short wavelength laser, but probably also to tackle the urgent problem of transport in a laser ion injector. (orig.)
Energy Technology Data Exchange (ETDEWEB)
Faenov, A. [MISDC of VNIIFTRI, Mendeleevo (Russian Federation); Dyakin, V. [MISDC of VNIIFTRI, Mendeleevo (Russian Federation); Magunov, A. [MISDC of VNIIFTRI, Mendeleevo (Russian Federation); Pikuz, T. [MISDC of VNIIFTRI, Mendeleevo (Russian Federation); Skobelev, I. [MISDC of VNIIFTRI, Mendeleevo (Russian Federation); Pikuz, S. [Rossijskaya Akademiya Nauk, Moscow (Russian Federation). Fizicheskij Inst.; Kasperczyk, A. [Institute of Plasma Physics and Laser Microfusion, Warsaw (Poland); Pisarczyk, T. [Institute of Plasma Physics and Laser Microfusion, Warsaw (Poland); Wolowski, J. [Institute of Plasma Physics and Laser Microfusion, Warsaw (Poland); Zielinska, E. [Institute of Plasma Physics and Laser Microfusion, Warsaw (Poland)
1996-08-01
A dense jet of a plasma consisting of multiply charged ions was generated in the interaction of a laser plasma with a strong external axial magnetic field. It is shown that using the high-luminosity X-ray spectroheliograph technique allows to measure plasma emission spectra with 2-dimensional spatial resolution even in the cases when these spectra have small intensities. The X-ray spectroscopy and interferometry methods are used to measure plasma parameter distributions. The dependencies of N{sub e}(z) and T{sub e}(z) measured in this paper can be used to calculate the evolution of plasma ionization state during plasma expansion. The quasihomogeneous laser jet, which appears when a laser plasma interacts with an external magnetic field can be used not only to form an active medium of a short wavelength laser, but probably also to tackle the urgent problem of transport in a laser ion injector. (orig.).
Ghalla, Houcine; Issaoui, Noureddine; Castillo, María Victoria; Brandán, Silvia Antonia; Flakus, Henryk T.
2014-03-01
The structural and vibrational properties of cyclic dimer of 2-furoic acid (2FA) were predicted by combining the available experimental infrared and Raman spectra in the solid phase and ab initio calculations based on density functional theory (DFT) with Pople's basis sets. The calculations show that there are two cyclic dimers for the title molecule that have been theoretically determined in the gas phase, and that only one of them, cis conformer, is present in the solid phase. The complete assignment of the 66 normal vibrational modes for the cis cyclic dimer was performed using the Pulay's Scaled Quantum Mechanics Force Field (SQMFF) methodology. Four strong bands in the infrared spectrum at 1583, 1427, 1126 and 887 cm-1 and the group of bands in the Raman spectrum at 1464, 1452, 1147, 1030, 885, 873, 848, 715 and 590 cm-1 are characteristic of the dimeric form of 2FA in the solid phase. In this work, the calculated structural and vibrational properties of both dimeric species were analyzed and compared between them. In addition, three types of atomic charges, bond orders, possible charge transfer, topological properties of the furan rings, Natural Bond Orbital (NBO) and Atoms in Molecules (AIM) theory calculations were employed to study the stabilities and intermolecular interactions of the both dimers of 2FA.
Klinkusch, Stefan; Tremblay, Jean Christophe
2016-05-14
In this contribution, we introduce a method for simulating dissipative, ultrafast many-electron dynamics in intense laser fields. The method is based on the norm-conserving stochastic unraveling of the dissipative Liouville-von Neumann equation in its Lindblad form. The N-electron wave functions sampling the density matrix are represented in the basis of singly excited configuration state functions. The interaction with an external laser field is treated variationally and the response of the electronic density is included to all orders in this basis. The coupling to an external environment is included via relaxation operators inducing transition between the configuration state functions. Single electron ionization is represented by irreversible transition operators from the ionizing states to an auxiliary continuum state. The method finds its efficiency in the representation of the operators in the interaction picture, where the resolution-of-identity is used to reduce the size of the Hamiltonian eigenstate basis. The zeroth-order eigenstates can be obtained either at the configuration interaction singles level or from a time-dependent density functional theory reference calculation. The latter offers an alternative to explicitly time-dependent density functional theory which has the advantage of remaining strictly valid for strong field excitations while improving the description of the correlation as compared to configuration interaction singles. The method is tested on a well-characterized toy system, the excitation of the low-lying charge transfer state in LiCN.
Energy Technology Data Exchange (ETDEWEB)
Klinkusch, Stefan; Tremblay, Jean Christophe [Institute for Chemistry and Biochemistry, Freie Universität Berlin, Takustr. 3, D-14195 Berlin (Germany)
2016-05-14
In this contribution, we introduce a method for simulating dissipative, ultrafast many-electron dynamics in intense laser fields. The method is based on the norm-conserving stochastic unraveling of the dissipative Liouville-von Neumann equation in its Lindblad form. The N-electron wave functions sampling the density matrix are represented in the basis of singly excited configuration state functions. The interaction with an external laser field is treated variationally and the response of the electronic density is included to all orders in this basis. The coupling to an external environment is included via relaxation operators inducing transition between the configuration state functions. Single electron ionization is represented by irreversible transition operators from the ionizing states to an auxiliary continuum state. The method finds its efficiency in the representation of the operators in the interaction picture, where the resolution-of-identity is used to reduce the size of the Hamiltonian eigenstate basis. The zeroth-order eigenstates can be obtained either at the configuration interaction singles level or from a time-dependent density functional theory reference calculation. The latter offers an alternative to explicitly time-dependent density functional theory which has the advantage of remaining strictly valid for strong field excitations while improving the description of the correlation as compared to configuration interaction singles. The method is tested on a well-characterized toy system, the excitation of the low-lying charge transfer state in LiCN.
Strong interactions - quark models
International Nuclear Information System (INIS)
Goto, M.; Ferreira, P.L.
1979-01-01
The variational method is used for the PSI and upsilon family spectra reproduction from the quark model, through several phenomenological potentials, viz.: linear, linear plus coulomb term and logarithmic. (L.C.) [pt
International Nuclear Information System (INIS)
Vugman, N.V.
1973-08-01
The radiation effects in ]Ir III (CN) 6 ] 3- diamagnetic complexe inserted in the KCl lattice and irradiated with electrons of 2MeV by electron spin resonance (ESR) are analysed. Formulas for g and A tensors in the ligand field approximation, are derivated to calculate non coupling electron density in the metal. The X polarization field of inner shells is positive, indicating a 6s function mixture in the non coupling electron molecular orbital. The observed hyperfine structure is assigned to 4 equivalent nitrogen and one non equivalent nitrogen. This hypothesis is verified by experience of isotope substitution with 15 N. The s and p spin density in ligands are calculated and discussed in terms of molecular obitals. The effects of strong quadrupole interaction into the EPR spectra of ]Ir II (CN) 5 ] 3- complex are analysed by MAGNSPEC computer program to diagonalize the Spin Hamiltonian of the system. Empiric rules for EPR espectrum interpretation with strong quadrupole interaction. A review of EPR technique and a review of main concepts of crystal-field and ligand field theories, are also presented. (M.C.K.) [pt
Liu, Hongfeng; Panmai, Mingcheng; Peng, Yuanyuan; Lan, Sheng
2017-05-29
We investigated theoretically and numerically the optical pulling and pushing forces acting on silicon (Si) nanospheres (NSs) with strong coherent interaction between electric and magnetic resonances. We examined the optical pulling and pushing forces exerted on Si NSs by two interfering waves and revealed the underlying physical mechanism from the viewpoint of electric- and magnetic-dipole manipulation. As compared with a polystyrene (PS) NS, it was found that the optical pulling force for a Si NS with the same size is enlarged by nearly two orders of magnitude. In addition to the optical pulling force appearing at the long-wavelength side of the magnetic dipole resonance, very large optical pushing force is observed at the magnetic quadrupole resonance. The correlation between the optical pulling/pushing force and the directional scattering characterized by the ratio of the forward to backward scattering was revealed. More interestingly, it was found that the high-order electric and magnetic resonances in large Si NSs play an important role in producing optical pulling force which can be generated by not only s-polarized wave but also p-polarized one. Our finding indicates that the strong coherent interaction between the electric and magnetic resonances existing in nanoparticles with large refractive indices can be exploited to manipulate the optical force acting on them and the correlation between the optical force and the directional scattering can be used as guidance. The engineering and manipulation of optical forces will find potential applications in the trapping, transport and sorting of nanoparticles.
Biocompatible Amphiphilic Hydrogel-Solid Dimer Particles as Colloidal Surfactants.
Chen, Dong; Amstad, Esther; Zhao, Chun-Xia; Cai, Liheng; Fan, Jing; Chen, Qiushui; Hai, Mingtan; Koehler, Stephan; Zhang, Huidan; Liang, Fuxin; Yang, Zhenzhong; Weitz, David A
2017-12-26
Emulsions of two immiscible liquids can slowly coalesce over time when stabilized by surfactant molecules. Pickering emulsions stabilized by colloidal particles can be much more stable. Here, we fabricate biocompatible amphiphilic dimer particles using a hydrogel, a strongly hydrophilic material, and achieve large contrast in the wetting properties of the two bulbs, resulting in enhanced stabilization of emulsions. We generate monodisperse single emulsions of alginate and shellac solution in oil using a flow-focusing microfluidics device. Shellac precipitates from water and forms a solid bulb at the periphery of the droplet when the emulsion is exposed to acid. Molecular interactions result in amphiphilic dimer particles that consist of two joined bulbs: one hydrogel bulb of alginate in water and the other hydrophobic bulb of shellac. Alginate in the hydrogel compartment can be cross-linked using calcium cations to obtain stable particles. Analogous to surfactant molecules at the interface, the resultant amphiphilic particles stand at the water/oil interface with the hydrogel bulb submerged in water and the hydrophobic bulb in oil and are thus able to stabilize both water-in-oil and oil-in-water emulsions, making these amphiphilic hydrogel-solid particles ideal colloidal surfactants for various applications.
Jin, Shouwen; Wang, Daqi
2014-05-01
Eight crystalline organic acid-base adducts derived from alkane bridged bis(N-benzimidazole) and organic acids (2,4,6-trinitrophenol, p-nitrobenzoic acid, m-nitrobenzoic acid, 3,5-dinitrobenzoic acid, 5-sulfosalicylic acid and oxalic acid) were prepared and characterized by X-ray diffraction analysis, IR, mp, and elemental analysis. Of the eight compounds five are organic salts (1, 4, 6, 7 and 8) and the other three (2, 3, and 5) are cocrystals. In all of the adducts except 1 and 8, the ratio of the acid and the base is 2:1. All eight supramolecular assemblies involve extensive intermolecular classical hydrogen bonds as well as other noncovalent interactions. The role of weak and strong noncovalent interactions in the crystal packing is ascertained. These weak interactions combined, all the complexes displayed 3D framework structure. The results presented herein indicate that the strength and directionality of the classical N+-H⋯O-, O-H⋯O, and O-H⋯N hydrogen bonds (ionic or neutral) and other nonbonding associations between acids and ditopic benzimidazoles are sufficient to bring about the formation of cocrystals or organic salts.
Zwoliński, K M; Eilmes, J
2016-03-14
The first known homoleptic cofacial dimers, based on covalently linked dibenzotetraaza[14]annulenes, were synthesized in reasonable 35-40% yields, without recourse to high-dilution techniques. Dinuclear zinc(ii) dimer showed strong binding affinity toward DABCO. Site-selective monometallation of the dimer, triggered by the linkers' structure, was observed, allowing access to heterobimetallic co-receptors.
Selective amine catalysed steroidal dimerization
Indian Academy of Sciences (India)
of cholesterol is the formation of a green colour in concentrated sulphuric acid, and this was shown to be due to a polyenyl steroidal dimer carbocation.7–9 Many dimeric and oligomeric steroids exhibit interesting micellular, detergent and liquid crystal behaviour.10,11. Most of the steroidal dimmers are also well-known.
International Nuclear Information System (INIS)
Sahoo, Pragati; Tiwari, Swatantra Kumar; De, Sudipan; Sahoo, Raghunath
2017-01-01
The main perspectives of Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory are to study the properties of the strongly interacting matter and to explore the conjectured Quantum Chromodynamics (QCD) phase diagram. Lattice QCD (lQCD) predicts a smooth crossover at vanishing baryon chemical potential (μ B ) and other QCD based theoretical models predicts first order phase transition at large μB. Searching of the Critical Point in the QCD phase diagram, finding the evidence and nature of phase transition, studying the properties of the matter formed in nuclear collisions as a function of √sNN are the main goals of RHIC. To investigate the nature of the matter produced at heavy-ion collisions, the thermodynamical and transport quantities like: energy density, shear viscosity etc. are studied. It is expected that the ratio of shear viscosity (η) to entropy density (s) would exhibit a minimum value near the QCD critical point
Magnetic properties of a classical XY spin dimer in a “planar” magnetic field
Energy Technology Data Exchange (ETDEWEB)
Ciftja, Orion, E-mail: ogciftja@pvamu.edu [Department of Physics, Prairie View A& M University, Prairie View, TX 77446 (United States); Prenga, Dode [Department of Physics, Faculty of Natural Sciences, University of Tirana, Bul. Zog I, Tirana (Albania)
2016-10-15
Single-molecule magnetism originates from the strong intra-molecular magnetic coupling of a small number of interacting spins. Such spins generally interact very weakly with the neighboring spins in the other molecules of the compound, therefore, inter-molecular spin couplings are negligible. In certain cases the number of magnetically coupled spins is as small as a dimer, a system that can be considered the smallest nanomagnet capable of storing non-trivial magnetic information on the molecular level. Additional interesting patterns arise if the spin motion is confined to a two-dimensional space. In such a scenario, clusters consisting of spins with large-spin values are particularly attractive since their magnetic interactions can be described well in terms of classical Heisenberg XY spins. In this work we calculate exactly the magnetic properties of a nanomagnetic dimer of classical XY spins in a “planar” external magnetic field. The problem is solved by employing a mathematical approach whose idea is the introduction of auxiliary spin variables into the starting expression of the partition function. Results for the total internal energy, total magnetic moment, spin–spin correlation function and zero-field magnetic susceptibility can serve as a basis to understand the magnetic properties of large-spin dimer building blocks. - Highlights: • Exact magnetic properties of a dimer system of classical XY spins in magnetic field. • Partition function in nonzero magnetic field obtained in closed-form. • Novel exact analytic results are important for spin models in a magnetic field. • Result provides benchmarks to gauge the accuracy of computational techniques.
Directory of Open Access Journals (Sweden)
Dokter Wim
2010-06-01
Full Text Available Abstract Background Glucocorticoids (GCs control expression of a large number of genes via binding to the GC receptor (GR. Transcription may be regulated either by binding of the GR dimer to DNA regulatory elements or by protein-protein interactions of GR monomers with other transcription factors. Although the type of regulation for a number of individual target genes is known, the relative contribution of both mechanisms to the regulation of the entire transcriptional program remains elusive. To study the importance of GR dimerization in the regulation of gene expression, we performed gene expression profiling of livers of prednisolone-treated wild type (WT and mice that have lost the ability to form GR dimers (GRdim. Results The GR target genes identified in WT mice were predominantly related to glucose metabolism, the cell cycle, apoptosis and inflammation. In GRdim mice, the level of prednisolone-induced gene expression was significantly reduced compared to WT, but not completely absent. Interestingly, for a set of genes, involved in cell cycle and apoptosis processes and strongly related to Foxo3a and p53, induction by prednisolone was completely abolished in GRdim mice. In contrast, glucose metabolism-related genes were still modestly upregulated in GRdim mice upon prednisolone treatment. Finally, we identified several novel GC-inducible genes from which Fam107a, a putative histone acetyltransferase complex interacting protein, was most strongly dependent on GR dimerization. Conclusions This study on prednisolone-induced effects in livers of WT and GRdim mice identified a number of interesting candidate genes and pathways regulated by GR dimers and sheds new light onto the complex transcriptional regulation of liver function by GCs.
International Nuclear Information System (INIS)
Richter-Was, E.; Was, Z.
2016-01-01
Among the physics goals of LHC experiments, precision tests of the Standard Model in the Strong and Electroweak sectors play an important role. Because of nature of the proton-proton processes, observables based on the measurement of the direction and energy of leptons provide the most precise signatures. In the present paper, we concentrate on the angular distribution of Drell-Yan process leptons, in the lepton-pair rest-frame. The vector nature of the intermediate state imposes that distributions are to a good precision described by spherical polynomials of at most second order. We show that with the proper choice of the coordinate frames, only one coefficient in this polynomial decomposition remains sizable, even in the presence of one or two high p T jets. The necessary stochastic choice of the frames relies on probabilities independent from any coupling constants. This remains true when one or two partons accompany the lepton pairs. In this way electroweak effects can be better separated from strong interaction ones for the benefit of the interpretation of the measurements. Our study exploits properties of single gluon emission matrix elements which are clearly visible if a conveniently chosen form of their representation is used. We rely also on distributions obtained from matrix element based Monte Carlo generated samples of events with two leptons and up to two additional partons in test samples. Incoming colliding protons' partons are distributed accordingly to PDFs and are strictly collinear to the corresponding beams. (orig.)
Dynamics of the water dimer + nitric oxide collision
Energy Technology Data Exchange (ETDEWEB)
Ree, Jong Baik [Dept. of Chemistry Education, Chonnam National University, Gwangju (Korea, Republic of); Kim, Yoo Hang [Dept. of Chemistry, Inha University, Incheon (Korea, Republic of); Shin, Hyung Kyu [Dept. of Chemistry, University of Nevada, Nevada (Korea, Republic of)
2017-02-15
Collision-induced intermolecular energy transfer and intramolecular vibrational redistribution in the collision of a water dimer and nitric oxide are studied by use of quasiclassical procedures. Intermolecular energy flow is shown to occur mainly through a direct-mode mechanism transferring relatively large amounts in strong collisions. About a quarter of the energy initially deposited in the dimer transfers to the ground state NO, while the rest redistributes among internal motions of the collision system. The main portion of initial energy deposited in the dimer redistributes in the stretches of the donor monomer through the 1:1 resonance followed by in the bend through the 1:2 resonance. Energy transfer from the excited NO to the ground-state dimer is equally efficient, transferring more than half the initial excitation to the donor monomer, the efficiency that is attributed to the internal modes operating as energy reservoirs. The hydrogen bond shares about 15% of the initial excitation stored in both dimer-to-NO and NO-to-dimer processes as a result of strong coupling of the hydrogen bond with the proton-donor OH bond of the monomer. A small fraction of collisions proceeds through a complex-mode mechanism and lead to NO dissociation, the dissociated O atom showing a propensity to form a new hydrogen bond.
Shi, Ruoyu; Gao, Lei; Lu, Hongliang; Li, Qunyang; Ma, Tian-Bao; Guo, Hui; Du, Shixuan; Feng, Xi-Qiao; Zhang, Shuai; Liu, Yanmin; Cheng, Peng; Hu, Yuan-Zhong; Gao, Hong-Jun; Luo, Jianbin
2017-06-01
Two dimensional (2D) materials often exhibit novel properties due to various coupling effects with their supporting substrates. Here, using friction force microscopy (FFM), we report an unusual moiré superlattice-level stick-slip instability on monolayer graphene epitaxially grown on Ru(0 0 0 1) substrate. Instead of smooth friction modulation, a significant long-range stick-slip sawtooth modulation emerges with a period coinciding with the moiré superlattice structure, which is robust against high external loads and leads to an additional channel of energy dissipation. In contrast, the long-range stick-slip instability reduces to smooth friction modulation on graphene/Ir(1 1 1) substrate. The moiré superlattice-level slip instability could be attributed to the large sliding energy barrier, which arises from the morphological corrugation of graphene on Ru(0 0 0 1) surface as indicated by density functional theory (DFT) calculations. The locally steep humps acting as obstacles opposing the tip sliding, originates from the strong interfacial electronic interaction between graphene and Ru(0 0 0 1). This study opens an avenue for modulating friction by tuning the interfacial atomic interaction between 2D materials and their substrates.
Czech Academy of Sciences Publication Activity Database
Sitkiewicz, S. P.; Mikolajczyk, M. M.; Toman, Petr; Zalesny, R.; Bartkowiak, W.
2013-01-01
Roč. 566, 12 April (2013), s. 67-70 ISSN 0009-2614 R&D Projects: GA ČR(CZ) GAP205/10/2280 Grant - others:AV ČR(CZ) M200501204 Program:M Institutional research plan: CEZ:AV0Z40500505 Institutional support: RVO:61389013 Keywords : poly-3-alkylthiophenes * intermolecular interactions * interaction energy decomposition Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.991, year: 2013
Effects of strong interactions between Ti and ceria on the structures of Ti/CeO2.
Yao, Xiao-Dan; Zhu, Kong-Jie; Teng, Bo-Tao; Yu, Cao-Ming; Zhang, Yun-Lei; Liu, Ya; Fan, Maohong; Wen, Xiao-Dong
2016-11-30
The effects of strong interactions between Ti and ceria on the structures of Ti/CeO 2 (111) are systematically investigated by density functional theory calculation. To our best knowledge, the adsorption energy of a Ti atom at the hollow site of CeO 2 is the highest value (-7.99 eV) reported in the literature compared with those of Au (-0.88--1.26 eV), Ag (-1.42 eV), Cu (-2.69 eV), Pd (-1.75 eV), Pt (-2.62 eV) and Sn (-3.68 eV). It is very interesting to find that Ti adatoms disperse at the hollow site of CeO 2 (111) to form surface TiO x species, instead of aggregating to form Ti metal clusters for the Ti-CeO 2 interactions that are much stronger than those of Ti-Ti ones. Ti adatoms are completely oxidized to Ti 4+ ions if they are monatomically dispersed on the next near hollow sites of CeO 2 (111) (xTi-NN-hollow); while Ti 3+ ions are observed when they locate at the near hollow sites (xTi-N-hollow). Due to the electronic repulsive effects among Ti 3+ ions, the adsorption energies of xTi-N-hollow are slightly weaker than those of xTi-NN-hollow. Simultaneously, the existence of unstable Ti 3+ ions on xTi-N-hollow also leads to the restructuring of xTi-N-hollow by surface O atoms of ceria transferring to the top of Ti 3+ ions, or oxidation by O 2 adsorption and dissociation. Both processes improve the stability of the xTi/CeO 2 system by Ti 3+ oxidation. Correspondingly, surface TiO 2 -like species form. This work sheds light into the structures of metal/CeO 2 catalysts with strong interactions between the metal and the ceria support.
Dimer-based model for heptaspanning membrane receptors.
Franco, Rafael; Casadó, Vicent; Mallol, Josefa; Ferré, Sergi; Fuxe, Kjell; Cortés, Antonio; Ciruela, Francisco; Lluis, Carmen; Canela, Enric I
2005-07-01
The existence of intramembrane receptor-receptor interactions for heptaspanning membrane receptors is now fully accepted, but a model considering dimers as the basic unit that binds to two ligand molecules is lacking. Here, we propose a two-state-dimer model in which the ligand-induced conformational changes from one component of the dimer are communicated to the other. Our model predicts cooperativity in binding, which is relevant because the other current models fail to address this phenomenon satisfactorily. Our two-state-dimer model also predicts the variety of responses elicited by full or partial agonists, neutral antagonists and inverse agonists. This model can aid our understanding of the operation of heptaspanning receptors and receptor channels, and, potentially, be important for improving the treatment of cardiovascular, neurological and neuropsychyatric diseases.
Attah, Isaac K; Platt, Sean P; Meot-Ner Mautner, Michael; El-Shall, M Samy; Peverati, Roberto; Head-Gordon, Martin
2015-04-02
The binding energy of the naphthalene(+•)(benzene) heterodimer cation has been determined to be 7.9 ± 1 kcal/mol for C10H8(+•)(C6H6) and 8.1 ± 1 kcal/mol for C10H8(+•)(C6D6) by equilibrium thermochemical measurements using the mass-selected drift cell technique. A second benzene molecule binds to the C10H8(+•)(C6D6) dimer with essentially the same energy (8.4 ± 1 kcal/mol), suggesting that the two benzene molecules are stacked on opposite sides of the naphthalene cation in the (C6D6)C10H8(+•)(C6D6) heterotrimer. The lowest-energy isomers of the C10H8(+•)(C6D6) and (C6D6)C10H8(+•)(C6D6) dimer and trimer calculated using the M11/cc-pVTZ method have parallel stacked structures with enthalpies of binding (-ΔH°) of 8.4 and 9.0 kcal/mol, respectively, in excellent agreement with the experimental values. The stacked face-to-face class of isomers is calculated to have substantial charge-transfer stabilization of about 45% of the total interaction energy despite the large difference between the ionization energies of benzene and naphthalene. Similarly, significant delocalization of the positive charge is found among all three fragments of the (C6D6)C10H8(+•)(C6D6) heterotrimer, thus leaving only 46% of the total charge on the central naphthalene moiety. This unexpectedly high charge-transfer component results in activating two benzene molecules in the naphthalene(+•)(benzene)2 heterotrimer cation to associate with a third benzene molecule at 219 K to form a benzene trimer cation and a neutral naphthalene molecule. The global minimum of the C10H8(+•)(C6H6)2 heterotrimer is found to be the one where the naphthalene cation is sandwiched between two benzene molecules. It is remarkable, and rather unusual, that the binding energy of the second benzene molecule is essentially the same as that of the first. This is attributed to the enhanced charge-transfer interaction in the stacked trimer radical cation.
Zhao, Kailou; Yang, Li; Wang, Xuejiao; Bai, Quan; Yang, Fan; Wang, Fei
2012-08-30
We have explored a novel dual-function stationary phase which combines both strong cation exchange (SCX) and hydrophobic interaction chromatography (HIC) characteristics. The novel dual-function stationary phase is based on porous and spherical silica gel functionalized with ligand containing sulfonic and benzyl groups capable of electrostatic and hydrophobic interaction functionalities, which displays HIC character in a high salt concentration, and IEC character in a low salt concentration in mobile phase employed. As a result, it can be employed to separate proteins with SCX and HIC modes, respectively. The resolution and selectivity of the dual-function stationary phase were evaluated under both HIC and SCX modes with standard proteins and can be comparable to that of conventional IEC and HIC columns. More than 96% of mass and bioactivity recoveries of proteins can be achieved in both HIC and SCX modes, respectively. The results indicated that the novel dual-function column could replace two individual SCX and HIC columns for protein separation. Mixed retention mechanism of proteins on this dual-function column based on stoichiometric displacement theory (SDT) in LC was investigated to find the optimal balance of the magnitude of electrostatic and hydrophobic interactions between protein and the ligand on the silica surface in order to obtain high resolution and selectivity for protein separation. In addition, the effects of the hydrophobicity of the ligand of the dual-function packings and pH of the mobile phase used on protein separation were also investigated in detail. The results show that the ligand with suitable hydrophobicity to match the electrostatic interaction is very important to prepare the dual-function stationary phase, and a better resolution and selectivity can be obtained at pH 6.5 in SCX mode. Therefore, the dual-function column can replace two individual SCX and HIC columns for protein separation and be used to set up two-dimensional liquid
Wang, H.; Kravitz, B.; Rasch, P. J.; Morrison, H.; Solomon, A.
2014-12-01
Previous process-oriented modeling studies have highlighted the dependence of effectiveness of cloud brightening by aerosols on cloud regimes in warm marine boundary layer. Cloud microphysical processes in clouds that contain ice, and hence the mechanisms that drive aerosol-cloud interactions, are more complicated than in warm clouds. Interactions between ice particles and liquid drops add additional levels of complexity to aerosol effects. A cloud-resolving model is used to study aerosol-cloud interactions in the Arctic triggered by strong aerosol emissions, through either geoengineering injection or concentrated sources such as shipping and fires. An updated cloud microphysical scheme with prognostic aerosol and cloud particle numbers is employed. Model simulations are performed in pure super-cooled liquid and mixed-phase clouds, separately, with or without an injection of aerosols into either a clean or a more polluted Arctic boundary layer. Vertical mixing and cloud scavenging of particles injected from the surface is still quite efficient in the less turbulent cold environment. Overall, the injection of aerosols into the Arctic boundary layer can delay the collapse of the boundary layer and increase low-cloud albedo. The pure liquid clouds are more susceptible to the increase in aerosol number concentration than the mixed-phase clouds. Rain production processes are more effectively suppressed by aerosol injection, whereas ice precipitation (snow) is affected less; thus the effectiveness of brightening mixed-phase clouds is lower than for liquid-only clouds. Aerosol injection into a clean boundary layer results in a greater cloud albedo increase than injection into a polluted one, consistent with current knowledge about aerosol-cloud interactions. Unlike previous studies investigating warm clouds, the impact of dynamical feedback due to precipitation changes is small. According to these results, which are dependent upon the representation of ice nucleation
Yamada, Kana; Noguchi, Chisato; Kamitori, Kazuyo; Dong, Youyi; Hirata, Yuko; Hossain, Mohammad A; Tsukamoto, Ikuko; Tokuda, Masaaki; Yamaguchi, Fuminori
2012-02-01
Oxidative stress modulates the osteoclast differentiation via redox systems, and thioredoxin 1 (Trx) promotes the osteoclast formation by regulating the activity of transcription factors. The function of Trx is known to be regulated by its binding partner, thioredoxin-interacting protein (TXNIP). We previously reported that the expression of TXNIP gene is strongly induced by a rare sugar D-allose. In this study, we tested the hypothesis that D-allose could inhibit the osteoclast differentiation by regulating the Trx function. We used a murine Raw264 cell line that differentiates to the osteoclast by the receptor activator of nuclear factor-κB ligand (RANKL) treatment. The effect of sugars was evaluated by tartrate-resistant acid phosphatase staining. The expression and localization of TXNIP and Trx protein were examined by Western blotting and immunohistochemisty. The activity of the nuclear factor-κB, nuclear factor of activated T cells, and activator protein 1 transcription factors was measured by the luciferase reporter assay. The addition of D-allose (25 mmol/L) inhibited the osteoclast differentiation down to 9.53% ± 1.27% of a receptor activator of nuclear factor-κB ligand-only treatment. During the osteoclast differentiation, a significant increase of TNXIP was observed by D-allose treatment. The immunohistochemical analysis showed that both Trx and TXNIP existed in the nucleus in preosteoclasts and osteoclasts. Overexpression of TXNIP by plasmid transfection also inhibited the osteoclast formation, indicating the functional importance of TXNIP for the osteoclast differentiation. Transcriptional activity of the activator protein 1, nuclear factor-κB, and nuclear factor of activated T cells, known to be modulated by Trx, were inhibited by D-allose. In conclusion, our data indicate that D-allose is a strong inhibitor of the osteoclast differentiation, and this effect could be caused by TXNIP induction and a resulting inhibition of the Trx function
Czech Academy of Sciences Publication Activity Database
Granatier, Jaroslav; Pitoňák, M.; Hobza, Pavel
2012-01-01
Roč. 8, č. 7 (2012), s. 2282-2292 ISSN 1549-9618 Grant - others:APVV(SK) APVV-0059-10 Institutional research plan: CEZ:AV0Z40550506 Keywords : intermolecular interaction energies * Plesset perturbation-theory * molecular-orbital methods * protein rubredoxin Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 5.389, year: 2012
Czech Academy of Sciences Publication Activity Database
Pandiyan, B. V.; Deepa, Palanisamy; Kolandaivel, P.
2014-01-01
Roč. 16, č. 37 (2014), s. 19928-19940 ISSN 1463-9076 Institutional support: RVO:61388963 Keywords : hydrogen bonding interactions * density functional theory * circular dichroism Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 4.493, year: 2014
Gálvez, Loli; González, Esther M; Arrese-Igor, Cesar
2005-09-01
Symbiotic N2 fixation in legume nodules declines under a wide range of environmental stresses. A high correlation between N2 fixation decline and sucrose synthase (SS; EC 2.4.1.13) activity down-regulation has been reported, although it has still to be elucidated whether a causal relationship between SS activity down-regulation and N2 fixation decline can be established. In order to study the likely C/N interactions within nodules and the effects on N2 fixation, pea plants (Pisum sativum L. cv. Sugar snap) were subjected to progressive water stress by withholding irrigation. Under these conditions, nodule SS activity declined concomitantly with apparent nitrogenase activity. The levels of UDP-glucose, glucose-1-phosphate, glucose-6-phosphate, and fructose-6-phosphate decreased in water-stressed nodules compared with unstressed nodules. Drought also had a marked effect on nodule concentrations of malate, succinate, and alpha-ketoglutarate. Moreover, a general decline in nodule adenylate content was detected. NADP+-dependent isocitrate dehydrogenase (ICDH; EC 1.1.1.42) was the only enzyme whose activity increased as a result of water deficit, compensating for a possible C/N imbalance and/or supplying NADPH in circumstances that the pentose phosphate pathway was impaired, as suggested by the decline in glucose-6-phosphate dehydrogenase (G6PDH; EC 1.1.1.49) activity. The overall results show the occurrence of strong C/N interactions in nodules subjected to water stress and support a likely limitation of carbon flux that might be involved in the decline of N2 fixation under drought.
Directory of Open Access Journals (Sweden)
Laura J Falkenberg
Full Text Available Foundation species, such as kelp, exert disproportionately strong community effects and persist, in part, by dominating taxa that inhibit their regeneration. Human activities which benefit their competitors, however, may reduce stability of communities, increasing the probability of phase-shifts. We tested whether a foundation species (kelp would continue to inhibit a key competitor (turf-forming algae under moderately increased local (nutrient and near-future forecasted global pollution (CO(2. Our results reveal that in the absence of kelp, local and global pollutants combined to cause the greatest cover and mass of turfs, a synergistic response whereby turfs increased more than would be predicted by adding the independent effects of treatments (kelp absence, elevated nutrients, forecasted CO(2. The positive effects of nutrient and CO(2 enrichment on turfs were, however, inhibited by the presence of kelp, indicating the competitive effect of kelp was stronger than synergistic effects of moderate enrichment of local and global pollutants. Quantification of physicochemical parameters within experimental mesocosms suggests turf inhibition was likely due to an effect of kelp on physical (i.e. shading rather than chemical conditions. Such results indicate that while forecasted climates may increase the probability of phase-shifts, maintenance of intact populations of foundation species could enable the continued strength of interactions and persistence of communities.
Measurement of the strong interaction coupling constant αs by jet study in the H1 experiment
International Nuclear Information System (INIS)
Squinabol, F.
1997-01-01
The H1 experiment allows to study hadronic jets produced in deep inelastic lepton (27.5 GeV) scattering off protons (820 GeV). The coupling constant of the strong interaction α s can be extracted from the measurement of the 2-jets rate in the final state. The use of the JADE algorithm is optimal for events with high energy transfer (100-4,000 GeV 2 ), corresponding to the 1994 and 1995 data. The error on α s (M Z 0 2 ) is dominated by the uncertainty from the hadronic energy measurement and the experimental resolution effects on jets. The theoretical error is dominated by the renormalization scale dependence. The final result is (M Z 0 2 ) 0.118 -0.008 +0.008 . This analysis is extended to smaller momentum transfers (25-100 GeV 2 ) using the factorizable K t algorithm, taking the transferred momentum as energy scale of the particle re-clustering. The result α s (M Z 0 2 ) 0.117 -0.008 +0.009 is compatible with the previous one. The precision of the measurement performed in this thesis is 7%. A precision of 4% could be achieved after progresses in the theoretical framework and/or after a significant increase of the luminosity. (author)
Energy Technology Data Exchange (ETDEWEB)
Liao, J. [Brookhaven National Lab. (BNL), Upton, NY (United States); Venugopalan, R. [Brookhaven National Lab. (BNL), Upton, NY (United States); Berges, J. [Brookhaven National Lab. (BNL), Upton, NY (United States); Blaizot, J. -P. [Brookhaven National Lab. (BNL), Upton, NY (United States); Gelis, F. [Brookhaven National Lab. (BNL), Upton, NY (United States)
2014-04-09
The RIKEN BNL Research Center (RBRC) was established in April 1997 at Brookhaven National Laboratory*. It is funded by the ''Rikagaku Kenkyusho'' (RIKEN, The Institute of Physical and Chemical Research) of Japan and the U. S. Department of Energy’s Office of Science. The RBRC is dedicated to the study of strong interactions, including spin physics, lattice QCD, and RHIC physics through the nurturing of a new generation of young physicists. The RBRC has theory, lattice gauge computing and experimental components. It is presently exploring the possibility of an astrophysics component being added to the program. The purpose of this Workshop is to critically review the recent progress on the theory and phenomenology of early time dynamics in relativistic heavy ion collisions from RHIC to LHC energies, to examine the various approaches on thermalization and existing issues, and to formulate new research efforts for the future. Topics slated to be covered include Experimental evidence for equilibration/isotropization, comparison of various approaches, dependence on the initial conditions and couplings, and turbulent cascades and Bose-Einstein condensation.
Energy Technology Data Exchange (ETDEWEB)
Ruhl, Hartmut [Munich Univ. (Germany). Chair for Computational and Plasma Physics
2016-11-01
Since the installation of SuperMUC phase 2 the 9216 nodes of phase 1 are more easily available for large scale runs allowing for the thin foil and AWAKE simulations. Besides phase 2 could be used in parallel for high throughput of the ion acceleration simulations. Challenging to our project were the full-volume checkpoints required by PIC that strained the I/O-subsystem of SuperMUC to its limits. New approaches considered for the next generation system, like burst buffers could overcome this bottleneck. Additionally, as the FDTD solver in PIC is strongly bandwidth bound, PSC will benefit profoundly from high-bandwidth memory (HBM) that most likely will be available in future HPC machines. This will be of great advantage as in 2018 phase II of AWAKE should begin, with a longer plasma channel further increasing the need for additional computing resources. Last but not least, it is expected that our methods used in plasma physics (many body interaction with radiation) will be more and more adapted for medical diagnostics and treatments. For this research field we expect centimeter sized volumes with necessary resolutions of tens of micro meters resulting in boxes of >10{sup 12} voxels (100-200 TB) on a regular basis. In consequence the demand for computing time and especially for data storage and data handling capacities will also increase significantly.
Tsuchimochi, Takashi
2015-10-14
Spin-flip approaches capture static correlation with the same computational scaling as the ordinary single reference methods. Here, we extend spin-flip configuration interaction singles (SFCIS) by projecting out intrinsic spin-contamination to make it spin-complete, rather than by explicitly complementing it with spin-coupled configurations. We give a general formalism of spin-projection for SFCIS, applicable to any spin states. The proposed method is viewed as a natural unification of SFCIS and spin-projected CIS to achieve a better qualitative accuracy at a low computational cost. While our wave function ansatz is more compact than previously proposed spin-complete SF approaches, it successfully offers more general static correlation beyond biradicals without sacrificing good quantum numbers. It is also shown that our method is invariant with respect to open-shell orbital rotations, due to the uniqueness of spin-projection. We will report benchmark calculations to demonstrate its qualitative performance on strongly correlated systems, including conical intersections that appear both in ground-excited and excited-excited degeneracies.
International Nuclear Information System (INIS)
Jansson, Kristina; Warringer, Jonas; Farewell, Anne; Park, Han-Oh; Hoe, Kwang-Lae; Kim, Dong-Uk; Hayles, Jacqueline; Sunnerhagen, Per
2008-01-01
The DNA glycosylase MutY is strongly conserved in evolution, and homologs are found in most eukaryotes and prokaryotes examined. This protein is implicated in repair of oxidative DNA damage, in particular adenine mispaired opposite 7,8-dihydro-8-oxoguanine. Previous investigations in Escherichia coli, fission yeast, and mammalian cells show an association of mutations in MutY homologs with a mutator phenotype and carcinogenesis. Eukaryotic MutY homologs physically associate with several proteins with a role in replication, DNA repair, and checkpoint signaling, specifically the trimeric 9-1-1 complex. In a genetic investigation of the fission yeast MutY homolog, myh1 + , we show that the myh1 mutation confers a moderately increased UV sensitivity alone and in combination with mutations in several DNA repair genes. The myh1 rad1, and to a lesser degree myh1 rad9, double mutants display a synthetic interaction resulting in enhanced sensitivity to DNA damaging agents and hydroxyurea. UV irradiation of myh1 rad1 double mutants results in severe chromosome segregation defects and visible DNA fragmentation, and a failure to activate the checkpoint. Additionally, myh1 rad1 double mutants exhibit morphological defects in the absence of DNA damaging agents. We also found a moderate suppression of the slow growth and UV sensitivity of rhp51 mutants by the myh1 mutation. Our results implicate fission yeast Myh1 in repair of a wider range of DNA damage than previously thought, and functionally link it to the checkpoint pathway
Anti-parallel dimer and tetramer formation of propylene carbonate
Directory of Open Access Journals (Sweden)
Ayana Tagawa
2017-09-01
Full Text Available Raman scattering and infrared (IR absorption spectra of enantiopure (R-propylene carbonate ((RPC and racemic propylene carbonate (PC were recorded at room temperature, 25 °C, in benzene (Bz solution and in the pure liquid state to investigate the presence of dimers and other higher order intermolecular associations. (RPC and PC both demonstrated a strong C=O stretching vibrational band. The band exhibited changes in its shape and resonance wavenumber highly dependent on the concentrations of PCs, whereas a difference between the chirality of (RPC and PC had little influence. In an extremely dilute condition, doubly split bands were observed at 1807 and 1820 cm-1 in both Raman and IR spectra, which are assigned to the characteristic bands of isolated monomeric PCs. An additional band appeared at 1795 cm-1 in a dilute to concentrated regime, and its magnitude strengthened with increasing concentrations accompanied with slight increasing in the magnitude of 1807 cm-1 band in Raman spectra, while an increase in the magnitude of 1807 cm-1 band was clearly greater than that of 1795 cm-1 band in IR spectra. The spectrum changes at 1795 and 1807 cm-1 were attributed to characteristics of anti-parallel dimer formation of PCs caused by strong dipole-dipole interactions between C=O groups. Moreover, another additional signal was clearly observed at 1780-1790 cm-1 in a concentrated regime, and became the primary signal in the pure liquid state with slight increasing in the intensity of 1795 cm-1 band in Raman spectra. On the other hand, in IR spectra the observed increasing of 1780-1790 cm-1 band was much less than that of 1795 cm-1 band. These newly found spectrum changes in the concentrated regime are attributed to the formation of anti-parallel tetramers of PCs based on the characteristics of band selection rule found in Raman and IR spectra. Equilibrium constants for the anti-parallel dimer (KD and tetramer formation (KT of PCs in Bz solution and in
Optical properties of electrically connected plasmonic nanoantenna dimer arrays
Zimmerman, Darin T.; Borst, Benjamin D.; Carrick, Cassandra J.; Lent, Joseph M.; Wambold, Raymond A.; Weisel, Gary J.; Willis, Brian G.
2018-02-01
We fabricate electrically connected gold nanoantenna arrays of homodimers and heterodimers on silica substrates and present a systematic study of their optical properties. Electrically connected arrays of plasmonic nanoantennas make possible the realization of novel photonic devices, including optical sensors and rectifiers. Although the plasmonic response of unconnected arrays has been studied extensively, the present study shows that the inclusion of nanowire connections modifies the device response significantly. After presenting experimental measurements of optical extinction for unconnected dimer arrays, we compare these to measurements of dimers that are interconnected by gold nanowire "busbars." The connected devices show the familiar dipole response associated with the unconnected dimers but also show a second localized surface plasmon resonance (LSPR) that we refer to as the "coupled-busbar mode." Our experimental study also demonstrates that the placement of the nanowire along the antenna modifies the LSPR. Using finite-difference time-domain simulations, we confirm the experimental results and investigate the variation of dimer gap and spacing. Changing the dimer gap in connected devices has a significantly smaller effect on the dipole response than it does in unconnected devices. On the other hand, both LSPR modes respond strongly to changing the spacing between devices in the direction along the interconnecting wires. We also give results for the variation of E-field strength in the dimer gap, which will be important for any working sensor or rectenna device.
Dimerization of 3He in 3He-4He mixture films
International Nuclear Information System (INIS)
Bashkin, E.
1994-01-01
3 He atoms dissolved in superfluid 4 He may form dimers ( 3 He) 2 in two-dimensional geometries. Dimer formation is studied in films of dilute 3 He- 4 He mixture. After designing a schematic 3 He- 3 He interaction potential, the dimer binding energy is calculated for various substrates. It is shown that 3 He impurity states localized near the substrate give rise to the highest magnitudes of the binding energy. (author). 32 refs., 6 figs.,; 1 tab
Collisional properties of weakly bound heteronuclear dimers
Marcelis, B.; Kokkelmans, S.J.J.M.F.; Shlyapnikov, G.V.; Petrov, D.S.
2008-01-01
We consider collisional properties of weakly bound heteronuclear molecules (dimers) formed in a two-species mixture of atoms with a large mass difference. We focus on dimers containing light fermionic atoms as they manifest collisional stability due to an effective dimer-dimer repulsion originating
Dimer pair correlations on the brick lattice
International Nuclear Information System (INIS)
Yokoi, C.S.O.; Nagle, J.F.; Sulinas, S.R.
1986-01-01
Using exact methods, pair-correlation functions are studied in the dimer model defined on a brick lattice. At long distances these functions exhibit strongly anisotropic algebraic decay and, near criticality, the length scales diverge differently in the two principal directions. The critical exponents are v /sub x/ =1/2 and v /sub y/ =1. These results are in agreement with deductions drawn from recent exact finite-size scaling calculations. We also interpret our results in the light of domain wall theories of commensurate-incommensurate transitions, and in particular we study the relation of the present model to the discrete version of the Pokrovsky-Talapov model introduced by Villain