T-dualization of type II superstring theory in double space

In this article we offer the new interpretation of T-dualization procedure of type II superstring theory in double space framework. We use the ghost free action of type II superstring in pure spinor formulation in approximation of constant background fields up to the quadratic terms. T-dualization along any subset of the initial coordinates, $x^a$, is equivalent to the permutation of this subset with subset of the corresponding T-dual coordinates, $y_a$, in double space coordinate $Z^M=(x^\mu,y_\mu)$. Demanding that the T-dual transformation law after exchange $x^a\leftrightarrow y_a$ has the same form as initial one, we obtain the T-dual NS-NS and NS-R background fields. The T-dual R-R field strength is determined up to one arbitrary constant under some assumptions. The compatibility between supersymmetry and T-duality produces change of bar spinors and R-R field strength. If we dualize odd number of dimensions $x^a$, such change flips type IIA/B to type II B/A. If we T-dualize time-like direction, one imaginary unit $i$ maps type II superstring theories to type $II^\star$ ones.Comment: Fermionic correction for bar variables and fields is clarified. Section 2 is substantially improved; Additional explanations added in the Introductio

T-duality diagram for a weakly curved background

In one of our previous papers we generalized the Buscher T-dualization procedure. Here we will investigate the application of this procedure to the theory of a bosonic string moving in the weakly curved background. We obtain the complete T-dualization diagram, connecting the theories which are the result of the T-dualizations over all possible choices of the coordinates. We distinguish three forms of the T-dual theories: the initial theory, the theory obtained T-dualizing some of the coordinates of the initial theory and the theory obtained T-dualizing all of the initial coordinates. While the initial theory is geometric, all the other theories are non geometric and additionally nonlocal. We find the T-dual coordinate transformation laws connecting these theories and show that the set of all T-dualizations forms an Abelian group

Spin-transfer torque and spin-polarization in topological-insulator/ferromagnet vertical heterostructures

We predict an unconventional spin-transfer torque (STT) acting on the magnetization of a free ferromagnetic (F) layer within N/TI/F vertical heterostructures which originates from strong spin-orbit coupling (SOC) on the surface of a three-dimensional topological insulator (TI), as well as from charge current becoming spin-polarized in the direction of transport as it flows from the normal metal (N) across the bulk of the TI slab. Unlike conventional STT in symmetric F'/I/F magnetic tunnel junctions, where only the in-plane STT component is non-zero in the linear response, both the in-plane and perpendicular torque are sizable in N/TI/F junctions while not requiring fixed F' layer as spin-polarizer which is advantageous for spintronic applications. Using the nonequilibrium Born-Oppenheimer treatment of interaction between fast conduction electrons and slow magnetization, we derive a general Keldysh Green function-based STT formula which makes it possible to analyze torque in the presence of SOC either in the bulk or at the interface of the free F layer.Comment: 5 pages, 3 figures, PDFLaTe

Shot Noise Probing of Magnetic Ordering in Zigzag Graphene Nanoribbons

The nonequilibrium time-dependent fluctuations of charge current have recently emerged as a sensitive experimental tool to probe ballistic transport through evanescent wave functions introduced into clean wide and short graphene strips by the attached metallic electrodes. We demonstrate that such "pseudo-diffusive" shot noise can be substantially modified in zigzag graphene nanoribbon (ZGNR) due to the topology of its edges responsible for localized states that facilitate ferromagnetic ordering along the edge when Coulomb interaction is taken into account. Thus, the shot noise enhancement of unpolarized, and even more sensitively of spin-polarized, charge currents injected into ZGNR will act as an all-electrical and edge-sensitive probe of such low-dimensional magnetism.Comment: 5 pages, 3 color figures; references update

Chemometric characterization of the hydrogen bonding complexes of secondary amides and aromatic hydrocarbons

The paper reports the results of the study of hydrogen bonding complexes between secondary amides and various aromatic hydrocarbons. The possibility of using chemometric methods was investigated in order to characterize N-H•••π hydrogen bonded complexes. Hierarchical clustering and Principal Component Analysis (PCA) have been applied on infrared spectroscopic and Taft parameters of 43 N-substituted amide complexes with different aromatic hydrocarbons. Results obtained in this report are in good agreement with conclusions of other spectroscopic and thermodynamic analysis

Penicillin-induced cutaneous necrotizing eosinophilic vasculitis with cryofibrinogenemia

Cutaneous necrotizing eosinophilic vasculitis (CNEV) is a rare type of vasculitis. Eosinophilic vasculitis is a necrotizing vasculitis with eosinophilic vascular infiltration, in which eosinophils mediate vascular damage in the disease process. We present a case of an 18-year-old girl who developed palpable purpura and hemorrhagic bullae over the lower extremities associated with itching, 7 days after the commencement of penicillin therapy. Plasma cryofibrinogen was positive. Histopathology showed an infiltration of eosinophils within and around the vessel walls and a complete absence of nuclear dust and neutrophils. Oral prednisone at 1 mg/kg induced remission in 2 weeks; the prednisone dose was tapered and discontinued after 2.5 months. There was no evidence of recurrence after 37 months of follow-up. Our patient represents a rare case of drug/penicillin-induced CNEV associated with cryofibrinogenemia, without systemic organ involvement. , and histopathological features of the lesion. Moreover, the possible complications of surgical approaches, namely healing defects, failure of skin grafts, and wound infection, should be considered. In this review we discuss the management of BCC localized on the face and scalp, according to the currently available treatment options.  </p

Shot Noise of Spin-Decohering Transport in Spin-Orbit Coupled Nanostructures

We generalize the scattering theory of quantum shot noise to include the full spin-density matrix of electrons injected from a spin-filtering or ferromagnetic electrode into a quantum-coherent nanostructure governed by various spin-dependent interactions. This formalism yields the spin-resolved shot noise power for different experimental measurement setups--with ferromagnetic source and ferromagnetic or normal drain electrodes--whose evaluation for the diffusive multichannel quantum wires with the Rashba (SO) spin-orbit coupling shows how spin decoherence and dephasing lead to substantial enhancement of charge current fluctuations (characterized by Fano factors $> 1/3$). However, these processes and the corresponding shot noise increase are suppressed in narrow wires, so that charge transport experiments measuring the Fano factor $F_{\uparrow \to \uparrow \downarrow}$ in a ferromagnet/SO-coupled-wire/paramagnet setup also quantify the degree of phase-coherence of transported spin--we predict a one-to-one correspondence between the magnitude of the spin polarization vector and $F_{\uparrow \to \uparrow \downarrow}$.Comment: 8 pages, 3 figure; enhanced with 2 new figure