Singular Modes of the Electromagnetic Field

We show that the mode corresponding to the point of essential spectrum of the electromagnetic scattering operator is a vector-valued distribution representing the square root of the three-dimensional Dirac's delta function. An explicit expression for this singular mode in terms of the Weyl sequence is provided and analyzed. An essential resonance thus leads to a perfect localization (confinement) of the electromagnetic field, which in practice, however, may result in complete absorption.Comment: 14 pages, no figure

Activity of immunoproteasome inhibitor ONX-0914 in acute lymphoblastic leukemia expressing MLL–AF4 fusion protein

Proteasome inhibitors bortezomib and carfilzomib are approved for the treatment of multiple myeloma and mantle cell lymphoma and have demonstrated clinical efficacy for the treatment of acute lymphoblastic leukemia (ALL). The t(4;11)(q21;q23) chromosomal translocation that leads to the expression of MLL–AF4 fusion protein and confers a poor prognosis, is the major cause of infant ALL. This translocation sensitizes tumor cells to proteasome inhibitors, but toxicities of bortezomib and carfilzomib may limit their use in pediatric patients. Many of these toxicities are caused by on-target inhibition of proteasomes in non-lymphoid tissues (e.g., heart muscle, gut, testicles). We found that MLL–AF4 cells express high levels of lymphoid tissue-specific immunoproteasomes and are sensitive to pharmacologically relevant concentrations of specific immunoproteasome inhibitor ONX-0914, even in the presence of stromal cells. Inhibition of multiple active sites of the immunoproteasomes was required to achieve cytotoxicity against ALL. ONX-0914, an inhibitor of LMP7 (ß5i) and LMP2 (ß1i) sites of the immunoproteasome, and LU-102, inhibitor of proteasome ß2 sites, exhibited synergistic cytotoxicity. Treatment with ONX-0914 significantly delayed the growth of orthotopic ALL xenograft tumors in mice. T-cell ALL lines were also sensitive to pharmacologically relevant concentrations of ONX-0914. This study provides a strong rationale for testing clinical stage immunoproteasome inhibitors KZ-616 and M3258 in ALL

Subterahertz chaos generation by coupling a superlattice to a linear resonator

We investigate the effects of a linear resonator on the high-frequency dynamics of electrons in devices exhibiting negative differential conductance. We show that the resonator strongly affects both the dc and ac transport characteristics of the device, inducing quasiperiodic and high-frequency chaotic current oscillations. The theoretical findings are confirmed by experimental measurements of a GaAs=AlAs miniband semiconductor superlattice coupled to a linear microstrip resonator. Our results are applicable to other active solid state devices and provide a generic approach for developing modern chaos-based high-frequency technologies including broadband chaotic wireless communication and superfast random-number generation

Drug-Initiated Synthesis of Cladribine-Based Polymer Prodrug Nanoparticles: Biological Evaluation and Structure Activity Relationships

International audienceBy using two reversible deactivation radical polymerization techniques, either nitroxide-mediated polymerization or reversible addition-fragmentation chain transfer polymerization, the "drug-initiated" approach was applied to cladribine (CdA) as an anticancer drug to synthesize small libraries of well-defined and self-stabilized CdA-based polymer prodrug nanoparticles, differing from the nature and the molar mass of the grown polymer, and the nature of the linker between CdA and the polymer, thus allowing structure-cytotoxicity relationships to be determined. Their biological evaluation was investigated in vitro on L1210 cancer cells. The preparation of fluorescent CdA-based nanoparticles with excellent imaging ability was also reported by applying the "drug-initiated" approach to an aggregation-induced emission-active dye

A coaxial spiral antenna with increased gain

The raise of the gain of cylindrical spiral antenna (CSA), which is excited in axial radiation mode, is usually reached by extension of axial length of the spiral [1]. However CSA gain at large (more than 15) number of coils depends on magnitude of the angle of the spiral winding [2]; when the angle of winding is close to 14°, it is increased practically linearly with growth of coils number. Increasing of CSA gain of limited axial length is received by the putting of the metal cylinder inside of a spiral [3]. When common length of antenna is equal 1.58λ, gain is more than 13 dB