5,585 research outputs found

    The ground state of a spin-1/2 neutral particle with anomalous magnetic moment in a Aharonov-Casher configuration

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    We determine the (bound) ground state of a spin 1/2 chargless particle with anomalous magnetic moment in certain Aharonov-Casher configurations. We recast the description of the system in a supersymmetric form. Then the basic physical requirements for unbroken supersymmetry are established. We comment on the possibility of neutron trapping in these systems

    Unbroken supersymmetry in the Aharonov-Casher effect

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    We consider the problem of the bound states of a spin 1/2 chargless particle in a given Aharonov-Casher configuration. To this end we recast the description of the system in a supersymmetric form. Then the basic physical requirements for unbroken supersymmetry are established. We comment on the possibility of neutron confinement in this system

    Inuloxin E, a New Seco-Eudesmanolide Isolated from Dittrichia viscosa, Stimulating Orobanche cumana Seed Germination

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    A new sesquiterpenoid belonging to the subgroup seco-eudesmanolides and named inuloxin E was isolated from Dittrichia viscosa, together with the already known sesquiterpenoids inuloxins A–D and -costic acid. Inuloxin E was characterized by spectroscopic data (essentially NMR and ESIMS) as 3-methylene-6-(1-methyl-4-oxo-pentyl)-3a,4,7,7a-tetrahydro-3H-benzofuran-2-one. Its relative configuration was determined by comparison with the closely related inuloxin D and chemical conversion of inuloxin E into inuloxin D and by the observed significant correlation in the NOESY spectrum. Both inuloxins D and E induced germination of the parasitic weed Orobanche cumana, but were inactive on the seeds of Orobanche minor and Phelipanche ramosa. The germination activity of some hemisynthetic esters of inuloxin D was also investigated

    Persistent spin and mass currents and Aharonov-Casher effect

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    Spin-orbit interaction produces persistent spin and mass currents in the ring via the Aharonov-Casher effect. The experiment in 3He−A1^3He-A_1 phase, in which this effect leads to the excitation of mass and spin supercurrent is proposed.Comment: 10 page

    The role of a new class of long noncoding RNAs transcribed from ultraconserved regions in cancer

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    Ultraconserved regions (UCRs) represent a relatively new class of non-coding genomic sequences highly conserved between human, rat and mouse genomes. These regions can reside within exons of protein-coding genes, despite the vast majority of them localizes within introns or intergenic regions. Several studies have undoubtedly demonstrated that most of these regions are actively transcribed in normal cells/tissues, where they contribute to regulate many cellular processes. Interestingly, these non-coding RNAs exhibit aberrant expression levels in human cancer cells and their expression profiles have been used as prognostic factors in human malignancies, as well as to unambiguously distinguish among distinct cancer types. In this review, we first describe their identification, then we provide some updated information about their genomic localization and classification. More importantly, we discuss about the available literature describing an overview of the mechanisms through which some transcribed UCRs (T-UCR) contribute to cancer progression or to the metastatic spread. To date, the interplay between T-UCRs and microRNAs is the most convincing evidence linking T-UCRs and tumorigenesis. The limitations of these studies and the future challenges to be addressed in order to understand the biological role of T-UCRs are also discussed herein. We envision that future efforts are needed to convincingly include this class of ncRNAs in the growing area of cancer therapeutics

    Neutron Acceleration in Uniform Electromagnetic Fields

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    The question as to whether neutron acceleration can occur in uniform electromagnetic fields is examined. Although such an effect has been predicted using the canonical equations of motion some doubt has been raised recently as to whether it is in principle observable for a spin 1/2 particle. To resolve this issue a gedanken experiment is proposed and analyzed using a wave packet construction for the neutron beam. By allowing arbitrary orientation for the neutron spin as well as for the electric and magnetic fields a non vanishing acceleration of the center of the neutron wave packet is found which confirms the predictions of the canonical formalism.Comment: 11 page
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