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A proposed method for controlling the shape and orientation of very large shallow dish type receiver/reflectors to be used in communication, radiometry and in electronic orbital based mail systems involves connecting a rigid light weight dumbell with heavy tip masses to the shell at its apex by a spring loaded double gimballed joint with dampling. To completely damp the system transient motion in all of the important lower frequency modes, an active control system is required. A mathematical model is extended to include the effects of point actuators located at preselected positions on the shell surface. The formulation of the uncontrolled dynamics assumes an a priori knowledge of the frequencies of all the elastic modes to be incorporated within the system model. As an example, three rigid body modes and six elastic modes are included in the model and six actuators are assumed, none of which lies on a nodal line or circle.

A proposed method for controlling the shape and orientation of very large shallow dish type receiver/reflectors to be used in communication, radiometry and in electronic orbital based mail systems involves connecting a rigid light weight dumbell with heavy tip masses to the shell at its apex by a spring loaded double gimballed joint with dampling. To completely damp the system transient motion in all of the important lower frequency modes, an active control system is required. A mathematical model is extended to include the effects of point actuators located at preselected positions on the shell surface. The formulation of the uncontrolled dynamics assumes an a priori knowledge of the frequencies of all the elastic modes to be incorporated within the system model. As an example, three rigid body modes and six elastic modes are included in the model and six actuators are assumed, none of which lies on a nodal line or circle.

A proposed method for controlling the shape and orientation of very large shallow dish type receiver/reflectors to be used in communication, radiometry and in electronic orbital based mail systems involves connecting a rigid light weight dumbell with heavy tip masses to the shell at its apex by a spring loaded double gimballed joint with dampling. To completely damp the system transient motion in all of the important lower frequency modes, an active control system is required. A mathematical model is extended to include the effects of point actuators located at preselected positions on the shell surface. The formulation of the uncontrolled dynamics assumes an a priori knowledge of the frequencies of all the elastic modes to be incorporated within the system model. As an example, three rigid body modes and six elastic modes are included in the model and six actuators are assumed, none of which lies on a nodal line or circle.

A proposed method for controlling the shape and orientation of very large shallow dish type receiver/reflectors to be used in communication, radiometry and in electronic orbital based mail systems involves connecting a rigid light weight dumbell with heavy tip masses to the shell at its apex by a spring loaded double gimballed joint with dampling. To completely damp the system transient motion in all of the important lower frequency modes, an active control system is required. A mathematical model is extended to include the effects of point actuators located at preselected positions on the shell surface. The formulation of the uncontrolled dynamics assumes an a priori knowledge of the frequencies of all the elastic modes to be incorporated within the system model. As an example, three rigid body modes and six elastic modes are included in the model and six actuators are assumed, none of which lies on a nodal line or circle.

Recently, the fragment yield ratios were investigated in the fission of 238,233U targets induced by 14 MeV neutrons [1]. The effect of the deformed shell structure around N=64 on the dynamics of scission was suggested as an explanation of the observed breakdown of the isoscaling behavior. As an alternative explanation, the effect of binding energy of final fragments, in particular the neutron shell closure of the complementary fragment around N=82, was suggested by Friedman [2]. When applying that concept consistently, the observed two breakdowns of the isoscaling behavior around N=62 and N=80 signal the effect of two shell closures (N=82 and N=64) on the dynamics of scission. To separate the two effects, we examine the isoscaling plots obtained using fission fragment yield data from the spontaneous fission of the heavier nuclei 248,244Cm and find that the breakdown of isoscaling around N=64 persists even if it can not be related to shell closure of the complementary fragment and thus it manifests the effect of the deformed shell structure in the scission configuration.

Recently, the fragment yield ratios were investigated in the fission of 238,233U targets induced by 14 MeV neutrons [1]. The effect of the deformed shell structure around N=64 on the dynamics of scission was suggested as an explanation of the observed breakdown of the isoscaling behavior. As an alternative explanation, the effect of binding energy of final fragments, in particular the neutron shell closure of the complementary fragment around N=82, was suggested by Friedman [2]. When applying that concept consistently, the observed two breakdowns of the isoscaling behavior around N=62 and N=80 signal the effect of two shell closures (N=82 and N=64) on the dynamics of scission. To separate the two effects, we examine the isoscaling plots obtained using fission fragment yield data from the spontaneous fission of the heavier nuclei 248,244Cm and find that the breakdown of isoscaling around N=64 persists even if it can not be related to shell closure of the complementary fragment and thus it manifests the effect of the deformed shell structure in the scission configuration.

Recently, the fragment yield ratios were investigated in the fission of 238,233U targets induced by 14 MeV neutrons [1]. The effect of the deformed shell structure around N=64 on the dynamics of scission was suggested as an explanation of the observed breakdown of the isoscaling behavior. As an alternative explanation, the effect of binding energy of final fragments, in particular the neutron shell closure of the complementary fragment around N=82, was suggested by Friedman [2]. When applying that concept consistently, the observed two breakdowns of the isoscaling behavior around N=62 and N=80 signal the effect of two shell closures (N=82 and N=64) on the dynamics of scission. To separate the two effects, we examine the isoscaling plots obtained using fission fragment yield data from the spontaneous fission of the heavier nuclei 248,244Cm and find that the breakdown of isoscaling around N=64 persists even if it can not be related to shell closure of the complementary fragment and thus it manifests the effect of the deformed shell structure in the scission configuration.

Spin-isospin response in exotic nuclear systems is investigated. It is found that in some nuclei excitations with pionic quantum numbers (0-, 1+, 2-, ...) appear at very low energies with large transition probabilities, which is an indication of the vicinity of the onset of pion condensation. As an example, 2- components of the spin-dipole resonance in 78-Ni and 132-Sn are considered. The existence of such modes points out to the necessity of taking into account their coupling to other elementary modes of excitation, e.g. single-quasiparticle ones. This coupling is introduced in the theory for the first time. Thereby, pion-exchange contribution to the nucleon-nucleon interaction is included in the relativistic framework beyond the Hartree-Fock approximation. Namely, classes of Feynman diagrams are selected according to their significance for nuclear spectroscopic characteristics, such as single-particle energies and strength functions, and included into the nucleonic self-energy in all orders of meson-exchange. As an illustration, the impact of these new contributions on the single-particle energies of 100-Sn is discussed.

We discuss the on-shell diagrammatic representation of theories less special than maximally supersymmetric Yang-Mills. In particular, we focus on planar $\mathcal{N}\,\le\,2$ gauge theories, including pure Yang-Mills. For such a class of theories, the on-shell diagrammatics is endowed with a decoration which carries the information on the helicity of the coherent states. In the first part of the paper we extensively discuss the properties of this decorated diagrammatics. Particular relevance have the helicity flows that the decoration induces on the diagrams, which allows to identify the different classes of singularities and, consequentely, the singularity structure of the on-shell processes. The second part of the paper establishes a link between the decorated on-shell diagrammatics and the scattering amplitudes for the theories under examination. We prove that an all-loop recursion relation at integrand level holds also for $\mathcal{N}\,=\,1,\,2$, while for $\mathcal{N}\,=\,0$ we are able to set up a preliminary analysis at one loop. In both supersymmetric and non-supersymmetric case, the treatment of the forward limit is subtle. We provide a fully on-shell analysis of it which is crucial for the proof of the all-loop recursion relation and for the analysis of pure Yang-Mills.

The dynamics of orbiting shallow flexible spherical shell structures under the influence of control actuators was studied. Control laws are developed to provide both attitude and shape control of the structure. The elastic modal frequencies for the fundamental and lower modes are closely grouped due to the effect of the shell curvature. The shell is gravity stabilized by a spring loaded dumbbell type damper attached at its apex. Control laws are developed based on the pole clustering techniques. Savings in fuel consumption can be realized by using the hybrid shell dumbbell system together with point actuators. It is indicated that instability may result by not including the orbital and first order gravity gradient effects in the plant prior to control law design.

Rankine-Hugoniot shock adiabats are calculated in the pressure range 1 Mbar-10 Gbar with two atomic-structure models: the atom in a spherical cell and the atom in a jellium of charges. These quantum self-consistent-field models include shell effects, which have a strong impact on pressure and shock velocity along the shock adiabat. Comparisons with experimental data are presented and quantum effects are interpreted in terms of electronic specific heat. A simple analytical estimate for the maximum compression is proposed, depending on initial density, atomic weight and atomic number.

Rankine-Hugoniot shock adiabats are calculated in the pressure range 1 Mbar-10 Gbar with two atomic-structure models: the atom in a spherical cell and the atom in a jellium of charges. These quantum self-consistent-field models include shell effects, which have a strong impact on pressure and shock velocity along the shock adiabat. Comparisons with experimental data are presented and quantum effects are interpreted in terms of electronic specific heat. A simple analytical estimate for the maximum compression is proposed, depending on initial density, atomic weight and atomic number.

Rankine-Hugoniot shock adiabats are calculated in the pressure range 1 Mbar-10 Gbar with two atomic-structure models: the atom in a spherical cell and the atom in a jellium of charges. These quantum self-consistent-field models include shell effects, which have a strong impact on pressure and shock velocity along the shock adiabat. Comparisons with experimental data are presented and quantum effects are interpreted in terms of electronic specific heat. A simple analytical estimate for the maximum compression is proposed, depending on initial density, atomic weight and atomic number.

The folding transition of single, long semiflexible polymers was studied with special emphasis on the chain length effect using Monte Carlo simulations. While a relatively short chain (10-25 Kuhn segments) undergoes a large discrete transiton between swollen coil and compact toroid conformations, a long chain (50 Kuhn segments) exhibits an intrachain segregated state between the disordered coil and ordered toroid.

The folding transition of single, long semiflexible polymers was studied with special emphasis on the chain length effect using Monte Carlo simulations. While a relatively short chain (10-25 Kuhn segments) undergoes a large discrete transiton between swollen coil and compact toroid conformations, a long chain (50 Kuhn segments) exhibits an intrachain segregated state between the disordered coil and ordered toroid.

A recent paper [M. Rashdan, Phys. Rev. C 63, 044303 (2001)] introduces the new parameterization NL-RA1 of the relativistic mean-field model which is claimed to give a better description of nuclear properties than earlier ones. Using this model ^{298}114 is predicted to be a doubly-magic nucleus. As will be shown in this comment these findings are to be doubted as they are obtained with an unrealistic parameterization of the pairing interaction and neglecting ground-state deformation.

The shell structure underlying shape changes in neutron-rich nuclei near N=28 has been investigated by a novel application of the transient field technique to measure the first-excited state g factors in 38S and 40S produced as fast radioactive beams. There is a fine balance between proton and neutron contributions to the magnetic moments in both nuclei. The g factor of deformed 40S does not resemble that of a conventional collective nucleus because spin contributions are more important than usual.

The shell structure underlying shape changes in neutron-rich nuclei near N=28 has been investigated by a novel application of the transient field technique to measure the first-excited state g factors in 38S and 40S produced as fast radioactive beams. There is a fine balance between proton and neutron contributions to the magnetic moments in both nuclei. The g factor of deformed 40S does not resemble that of a conventional collective nucleus because spin contributions are more important than usual.

The shell structure underlying shape changes in neutron-rich nuclei near N=28 has been investigated by a novel application of the transient field technique to measure the first-excited state g factors in 38S and 40S produced as fast radioactive beams. There is a fine balance between proton and neutron contributions to the magnetic moments in both nuclei. The g factor of deformed 40S does not resemble that of a conventional collective nucleus because spin contributions are more important than usual.

The shell structure underlying shape changes in neutron-rich nuclei near N=28 has been investigated by a novel application of the transient field technique to measure the first-excited state g factors in 38S and 40S produced as fast radioactive beams. There is a fine balance between proton and neutron contributions to the magnetic moments in both nuclei. The g factor of deformed 40S does not resemble that of a conventional collective nucleus because spin contributions are more important than usual.

The shell structure underlying shape changes in neutron-rich nuclei near N=28 has been investigated by a novel application of the transient field technique to measure the first-excited state g factors in 38S and 40S produced as fast radioactive beams. There is a fine balance between proton and neutron contributions to the magnetic moments in both nuclei. The g factor of deformed 40S does not resemble that of a conventional collective nucleus because spin contributions are more important than usual.

The shell structure underlying shape changes in neutron-rich nuclei between N=20 and N=28 has been investigated by a novel application of the transient field technique to measure the first-excited state g factors in S-38 and S-40 produced as fast radioactive beams. Details of the new methodology are presented. In both S-38 and S-40 there is a fine balance between the proton and neutron contributions to the magnetic moments. Shell model calculations which describe the level schemes and quadrupole properties of these nuclei also give a satisfactory explanation of the g factors. In S-38 the g factor is extremely sensitive to the occupation of the neutron p3/2 orbit above the N=28 shell gap as occupation of this orbit strongly affects the proton configuration. The g factor of deformed S-40 does not resemble that of a conventional collective nucleus because spin contributions are more important than usual.

The shell structure underlying shape changes in neutron-rich nuclei between N=20 and N=28 has been investigated by a novel application of the transient field technique to measure the first-excited state g factors in S-38 and S-40 produced as fast radioactive beams. Details of the new methodology are presented. In both S-38 and S-40 there is a fine balance between the proton and neutron contributions to the magnetic moments. Shell model calculations which describe the level schemes and quadrupole properties of these nuclei also give a satisfactory explanation of the g factors. In S-38 the g factor is extremely sensitive to the occupation of the neutron p3/2 orbit above the N=28 shell gap as occupation of this orbit strongly affects the proton configuration. The g factor of deformed S-40 does not resemble that of a conventional collective nucleus because spin contributions are more important than usual.

We discuss differences between on-shell and off-shell treatments in the search for anomalous neutral triple gauge couplings in $\mathrm{e^+ e^-}$ collisions. We find that the usual on-shell framework represents an optimal starting point, covering all scenarios in which a reasonable experimental sensitivity is expected. We show that off-shell effects lead to negligible deviations at the experimental level, provided that $\mathrm{e^+ e^-}\to\mathrm{f}\bar{\mathrm{f}}\gamma$ and $\mathrm{e^+ e^-}\to\mathr performed in regions where $\mathrm{Z}^*\to\mathrm{f}\bar{\mathrm{f}},\mathrm{f^\prime}\math production is dominant. For consistency reasons, we advocate the use of a natural extension of the on-shell definitions, which takes into account the correct off-shell dependences. Contrary to what has been recently suggested in the literature, we find that no $SU(2)_L\times U(1)_Y$ constraints among neutral triple gauge couplings can be imposed in a general case.

We discuss differences between on-shell and off-shell treatments in the search for anomalous neutral triple gauge couplings in $\mathrm{e^+ e^-}$ collisions. We find that the usual on-shell framework represents an optimal starting point, covering all scenarios in which a reasonable experimental sensitivity is expected. We show that off-shell effects lead to negligible deviations at the experimental level, provided that $\mathrm{e^+ e^-}\to\mathrm{f}\bar{\mathrm{f}}\gamma$ and $\mathrm{e^+ e^-}\to\mathr performed in regions where $\mathrm{Z}^*\to\mathrm{f}\bar{\mathrm{f}},\mathrm{f^\prime}\math production is dominant. For consistency reasons, we advocate the use of a natural extension of the on-shell definitions, which takes into account the correct off-shell dependences. Contrary to what has been recently suggested in the literature, we find that no $SU(2)_L\times U(1)_Y$ constraints among neutral triple gauge couplings can be imposed in a general case.

We discuss differences between on-shell and off-shell treatments in the search for anomalous neutral triple gauge couplings in $\mathrm{e^+ e^-}$ collisions. We find that the usual on-shell framework represents an optimal starting point, covering all scenarios in which a reasonable experimental sensitivity is expected. We show that off-shell effects lead to negligible deviations at the experimental level, provided that $\mathrm{e^+ e^-}\to\mathrm{f}\bar{\mathrm{f}}\gamma$ and $\mathrm{e^+ e^-}\to\mathr performed in regions where $\mathrm{Z}^*\to\mathrm{f}\bar{\mathrm{f}},\mathrm{f^\prime}\math production is dominant. For consistency reasons, we advocate the use of a natural extension of the on-shell definitions, which takes into account the correct off-shell dependences. Contrary to what has been recently suggested in the literature, we find that no $SU(2)_L\times U(1)_Y$ constraints among neutral triple gauge couplings can be imposed in a general case.

"Observations on the Microscopic Shell Structure of Spirifer Cuspidatus, Sowerby, and Some Similar American Forms" is an article from Proceedings of the Academy of Natural Sciences of Philadelphia, Volume 17 . View more articles from Proceedings of the Academy of Natural Sciences of Philadelphia . View this article on JSTOR . View this article's JSTOR metadata . You may also retrieve all of this items metadata in JSON at the following URL: https://archive.org/metadata/jstor-4624052

Recent efforts to classify representations of supersymmetry with no central charge have focused on supermultiplets that are aptly depicted by Adinkras, wherein every supersymmetry generator transforms each component field into precisely one other component field or its derivative. Herein, we study gauge-quotients of direct sums of Adinkras by a supersymmetric image of another Adinkra and thus solve a puzzle from Ref.[2]: The so-defined supermultiplets do not produce Adinkras but more general types of supermultiplets, each depicted as a connected network of Adinkras. Iterating this gauge-quotient construction then yields an indefinite sequence of ever larger supermultiplets, reminiscent of Weyl's construction that is known to produce all finite-dimensional unitary representations in Lie algebras.

Influence of semiconductor/insulator/semiconductor structure on the photo-catalytic activity of Fe3O4/SiO2/polythiophene core/shell submicron composite 作者： Zhang, F [Zhang, Fan][ 1 ] 1 Shi, YJ [Shi, Yuanji][ 2 ] 1 Zhao, ZS [Zhao, Zongshan][ 3 ] 1 Song, WJ [Song, Weijie][ 4 ] 1 Cheng, Y [Cheng, Yang][ 5 ] 1 作者单位： 1. College of Science, Nanjing Agricultural University, Nanjing 210095, PR China 提交时间： 2017-05-02 摘要: The Fe3O4/SiO2/polythiophene [FSP] submicron composite [SC] with a structure of semiconductor/insulator/semiconductor [SIS] was obtained. The characterization results showed that the FSP SC had a spherical core/shell shape with an average diameter of 506 nm. The high saturated magnetization value (∼39 emu/g) ensured the easy separation of FSP SC from aqueous solution. The photo-catalytic activity of the FSP SC was evaluated by the degradation of methyl orange (MO) under UV-irradiation in the presence of H2O2. Due to the SIS structure, the degradation rate constant by FSP SC (0.02177min−1) was 6.4, 1.6, and 2.5 times higher than that of Fe3O4/polythiophene (FP), polythiophene (P), and TiO2, respectively. The repetition results suggested the good photochemical stability of FSP SC. The mecha- nism was proposed by investigating the energy band variation of the SIS structure, the transfer of light generated carriers and the formation of effective hydroxyl radicals in the photo-catalysis progress. Abstract: The Fe3O4/SiO2/polythiophene [FSP] submicron composite [SC] with a structure of semiconductor/insulator/semiconductor [SIS] was obtained. The characterization results showed that the FSP SC had a spherical core/shell shape with an average diameter of 506 Submicron composite Core/shell Photocatalytic activity SIS structure Magnetic recovery 期刊： APPLIED CATALYSIS B-ENVIRONMENTAL 分类： 物理学 >> 普通物理:统计和量子力学,量子信息等 引用： ChinaXiv:201705.00416 (或此版本 ChinaXiv:201705.00416V1 ) doi:10.12074/201705.00416 CSTR:32003.36.ChinaXiv.201705.00416.V1 推荐引用方式： Zhang, F [Zhang, Fan][ 1 ],Shi, YJ [Shi, Yuanji][ 2 ],Zhao, ZS [Zhao, Zongshan][ 3 ],Song, WJ [Song, Weijie][ 4 ],Cheng, Y [Cheng, Yang][ 5 ].(2017).Influence of semiconductor/insulator/semiconductor structure on the photo-catalytic activity of Fe3O4/SiO2/polythiophene core/shell submicron composite.APPLIED CATALYSIS B-ENVIRONMENTAL.[ChinaXiv:201705.00416] 版本历史 [V1] 2017-05-02 12:34:40 ChinaXiv:201705.00416V1 下载全文

The relativistic particle-vibration coupling (RPVC) model is extended by the inclusion of spin- and isospin-flip excitation modes into the phonon space, introducing a new mechanism of dynamical interaction between nucleons with different isospin in the nuclear medium. Protons and neutrons exchange by collective modes which are formed by isovector $\pi$ and $\rho$-mesons, in turn, softened considerably because of coupling to nucleons of the medium. These modes are investigated within the proton-neutron relativistic random phase approximation (pn-RRPA) and relativistic proton-neutron time blocking approximation (pn-RTBA). The appearance of isospin-flip states with sizable transition probabilities at low energies points out that they are likely to couple to the single-particle degrees of freedom and, in addition to isoscalar low-lying phonons, to modify their spectroscopic characteristics. Such a coupling is quantified for the shell structure of $^{100,132}$Sn and found significant for the location of the dominant single-particle states.

The relativistic particle-vibration coupling (RPVC) model is extended by the inclusion of spin- and isospin-flip excitation modes into the phonon space, introducing a new mechanism of dynamical interaction between nucleons with different isospin in the nuclear medium. Protons and neutrons exchange by collective modes which are formed by isovector $\pi$ and $\rho$-mesons, in turn, softened considerably because of coupling to nucleons of the medium. These modes are investigated within the proton-neutron relativistic random phase approximation (pn-RRPA) and relativistic proton-neutron time blocking approximation (pn-RTBA). The appearance of isospin-flip states with sizable transition probabilities at low energies points out that they are likely to couple to the single-particle degrees of freedom and, in addition to isoscalar low-lying phonons, to modify their spectroscopic characteristics. Such a coupling is quantified for the shell structure of $^{100,132}$Sn and found significant for the location of the dominant single-particle states.

The Wess-Zumino term of the spinning string is constructed in terms of their anomalies using an extended field-antifield formalism. A new feature appears from a fact that the non-anomalous transformations do not form a sub-group. The algebra of the extended variables closes only using the equations of motion derived from the WZ term.

We use density functional theory (DFT) to investigate the electronic structure and chemical properties of gold nanoparticles. Different structural families of clusters are compared. For up to 60 atoms we optimize structures using DFT-based simulated annealing. Cluster geometries are found to distort considerably, creating large band gaps at the Fermi level. For up to 200 atoms we consider structures generated with a simple EMT potential and clusters based on cuboctahedra and icosahedra. All types of cluster geometry exhibit jellium-like electronic shell structure. We calculate adsorption energies of several atoms on the cuboctahedral clusters. Adsorption energies are found to vary abruptly at magic numbers. Using a Newns-Anderson model we find that the effect of magic numbers on adsorption energy can be understood from the location of adsorbate-induced states with respect to the cluster Fermi level.

We use density functional theory (DFT) to investigate the electronic structure and chemical properties of gold nanoparticles. Different structural families of clusters are compared. For up to 60 atoms we optimize structures using DFT-based simulated annealing. Cluster geometries are found to distort considerably, creating large band gaps at the Fermi level. For up to 200 atoms we consider structures generated with a simple EMT potential and clusters based on cuboctahedra and icosahedra. All types of cluster geometry exhibit jellium-like electronic shell structure. We calculate adsorption energies of several atoms on the cuboctahedral clusters. Adsorption energies are found to vary abruptly at magic numbers. Using a Newns-Anderson model we find that the effect of magic numbers on adsorption energy can be understood from the location of adsorbate-induced states with respect to the cluster Fermi level.

We use density functional theory (DFT) to investigate the electronic structure and chemical properties of gold nanoparticles. Different structural families of clusters are compared. For up to 60 atoms we optimize structures using DFT-based simulated annealing. Cluster geometries are found to distort considerably, creating large band gaps at the Fermi level. For up to 200 atoms we consider structures generated with a simple EMT potential and clusters based on cuboctahedra and icosahedra. All types of cluster geometry exhibit jellium-like electronic shell structure. We calculate adsorption energies of several atoms on the cuboctahedral clusters. Adsorption energies are found to vary abruptly at magic numbers. Using a Newns-Anderson model we find that the effect of magic numbers on adsorption energy can be understood from the location of adsorbate-induced states with respect to the cluster Fermi level.

An account of the approach used in design of a large sandwich construction nose cone is given. The areas in which analytical methods are needed are discussed and a theoretical procedure is proposed.

An account of the approach used in design of a large sandwich construction nose cone is given. The areas in which analytical methods are needed are discussed and a theoretical procedure is proposed.

We analyze several problems related to off-shell structure of open string sigma model by using a combination of derivative expansion and expansion in powers of the fields. According to the sigma model approach to bosonic open string theory, the tachyon effective action $S(T)$ coincides with the renormalized partition function $Z(T)$ of sigma model on a disk, up to a term vanishing on shell. On the other hand, $Z(T)$ is a generating functional of perturbative open string scattering amplitudes. If $S(T) = Z(T)$, then there should be no contribution of exchange diagrams to string amplitudes computed using $S(T)$. We compute the cubic term in the effective action, and show that it vanishes if some but not all external legs are on shell, and, therefore, any exchange diagram involving the cubic term vanishes too. Then, we discuss a problem of turning on nonrenormalizable boundary interactions, corresponding to massive string modes. We compute the quadratic term for a symmetric tensor field, and show that despite nonrenormalizability of the model one can consistently remove all divergent terms, and obtain a quadratic action reproducing the on-shell condition for the field. We also briefly discuss fermionic (NS) sigma model, compute the tachyon quadratic term, and show that it reproduces the correct tachyon mass. We note that turning on a massive symmetric tensor field leads to the appearance of a term linear in it, which can be removed by adding a higher-derivative term to the boundary of the disc.

We analyze several problems related to off-shell structure of open string sigma model by using a combination of derivative expansion and expansion in powers of the fields. According to the sigma model approach to bosonic open string theory, the tachyon effective action $S(T)$ coincides with the renormalized partition function $Z(T)$ of sigma model on a disk, up to a term vanishing on shell. On the other hand, $Z(T)$ is a generating functional of perturbative open string scattering amplitudes. If $S(T) = Z(T)$, then there should be no contribution of exchange diagrams to string amplitudes computed using $S(T)$. We compute the cubic term in the effective action, and show that it vanishes if some but not all external legs are on shell, and, therefore, any exchange diagram involving the cubic term vanishes too. Then, we discuss a problem of turning on nonrenormalizable boundary interactions, corresponding to massive string modes. We compute the quadratic term for a symmetric tensor field, and show that despite nonrenormalizability of the model one can consistently remove all divergent terms, and obtain a quadratic action reproducing the on-shell condition for the field. We also briefly discuss fermionic (NS) sigma model, compute the tachyon quadratic term, and show that it reproduces the correct tachyon mass. We note that turning on a massive symmetric tensor field leads to the appearance of a term linear in it, which can be removed by adding a higher-derivative term to the boundary of the disc.

The interaction between thin structures and incompressible Newtonian fluids is ubiquitous both in nature and in industrial applications. In this paper we present an isogeometric formulation of such problems which exploits a boundary integral formulation of Stokes equations to model the surrounding flow, and a non linear Kirchhoff-Love shell theory to model the elastic behaviour of the structure. We propose three different coupling strategies: a monolithic, fully implicit coupling, a staggered, elasticity driven coupling, and a novel semi-implicit coupling, where the effect of the surrounding flow is incorporated in the non-linear terms of the solid solver through its damping characteristics. The novel semi-implicit approach is then used to demonstrate the power and robustness of our method, which fits ideally in the isogeometric paradigm, by exploiting only the boundary representation (B-Rep) of the thin structure middle surface.