71 research outputs found

    Some new monogenean species and genera of the family Mazocraeidae

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    The morphological peculiarities of the Mazocraeidae, in particular the clamp structures, are discussed and a Latin nomenclature for the elements of the clamp skeleton is suggested. 3 new genera and 6 new species are then describe

    Strain-Compensated AlInGaAs-GaAsP Superlattices for Highly-Polarized Electron Emission

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    Spin-polarized electron emission from the first superlattice photocathodes developed with strain compensation is investigated. An opposite strain in the quantum well and barrier layers is complished using an InAlGaAs/GaAsP superlattice structure. The measured values of maximum polarization and quantum yield for the structure with a 0.18 um-thick working layer are close to the best results reported for any strained superlattice photocathode structure, demonstrating the high potential of strain compensation for future photocathode applications. An analysis of the photoemission spectra is used to estimate the parameters responsible for the polarization losses.Comment: 10 pages, 2 figure

    РЕАКЦІЯ ВОДИ НА ПРИРОДНІ ТА ШТУЧНІ ФІЗИЧНІ ФАКТОРИ НАДНИЗЬКОЇ ІНТЕНСИВНОСТІ

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    The researching of the water reaction was done - the changing of its spontaneous oscillation by the influence of the external factors, which have the low intensity. It is shown that the state of the water depends of the Moon phases and the influence of the electromagnetic field which has nonthermal intensity.Проведено исследование реакции воды - изменение ее спонтанных колебаний при влиянии внешних факторов крайне низкой интенсивности. Показано, что состояния воды могут зависеть от изменений фаз Луны, а также от воздействия электромагнитных полей нетепловой интенсивности.Проведено дослідження реакції води - зміна її спонтанних коливань при впливі зовнішніх факторів наднизької інтенсивності. Показано, що стани води можуть залежати від фаз Місяця, а також від впливу електромагнітних полів нетеплової інтенсивності

    Creation, doubling, and splitting, of vortices in intracavity second harmonic generation

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    We demonstrate generation and frequency doubling of unit charge vortices in a linear astigmatic resonator. Topological instability of the double charge harmonic vortices leads to well separated vortex cores that are shown to rotate, and become anisotropic, as the resonator is tuned across resonance

    Cosmological Landscape From Nothing: Some Like It Hot

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    We suggest a novel picture of the quantum Universe -- its creation is described by the {\em density matrix} defined by the Euclidean path integral. This yields an ensemble of universes -- a cosmological landscape -- in a mixed state which is shown to be dynamically more preferable than the pure quantum state of the Hartle-Hawking type. The latter is dynamically suppressed by the infinitely large positive action of its instanton, generated by the conformal anomaly of quantum fields within the cosmological bootstrap (the self-consistent back reaction of hot matter). This bootstrap suggests a solution to the problem of boundedness of the on-shell cosmological action and eliminates the infrared catastrophe of small cosmological constant in Euclidean quantum gravity. The cosmological landscape turns out to be limited to a bounded range of the cosmological constant ΛminΛΛmax\Lambda_{\rm min}\leq \Lambda \leq \Lambda_{\rm max}. The domain Λ<Λmin\Lambda<\Lambda_{\rm min} is ruled out by the back reaction effect which we analyze by solving effective Euclidean equations of motion. The upper cutoff is enforced by the quantum effects of vacuum energy and the conformal anomaly mediated by a special ghost-avoidance renormalization of the effective action. They establish a new quantum scale Λmax\Lambda_{\rm max} which is determined by the coefficient of the topological Gauss-Bonnet term in the conformal anomaly. This scale is realized as the upper bound -- the limiting point of an infinite sequence of garland-type instantons which constitute the full cosmological landscape. The dependence of the cosmological constant range on particle phenomenology suggests a possible dynamical selection mechanism for the landscape of string vacua.Comment: Final version, to appear in JCA

    Omanicotyle heterospina n. gen. et n. comb. (Monogenea: Microcotylidae) from the gills of Argyrops spinifer (Forsskal) (Teleostei: Sparidae) from the Sea of Oman

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    Background: The Sultanate of Oman's aquaculture industry is expanding with an on-going assessment of potential new fish species for culture. The king soldier bream, Argyrops spinifer (Forssk&aring;l) (Sparidae), is one such species that is under consideration. During a routine health assessment of specimens caught in the Sea of Oman throughout the period November 2009 to March 2011, a number of gill polyopisthocotylean monogeneans were recovered. Methods: A subsequent study of the monogeneans using a range of morphology-based approaches indicated that these were Bivagina heterospina Mamaev et Parukhin, 1974. In the absence of pre-existing molecular data, an expanded description of this species is provided, including a differential diagnosis with other species and genera belonging to the subfamily Microcotylinae Monticelli, 1892 with the subsequent movement of this species to a new genus to accommodate it. Results: The polyopisthocotyleans collected from the gills of A. spinifer appear to be unique within the family Microcotylidae Taschenberg, 1879 in that, morphologically, they possess a pair of large, muscular vaginae each armed with a full crown of 16-18 robust spines and a unique dorsal region of folded tegument, which permits their discrimination from species of Bivagina Yamaguti, 1963. Sequencing of the SSU rDNA (complete 1968 bp) and LSU rDNA (partial 949 bp) places the specimens collected during this study within the subfamily Microcotylinae, but the LSU rDNA sequence differs from Bivagina and also from other microcotylid genera. Morphological features of B. heterospina sensu Mamaev et Parukhin, 1974 and the specimens collected from the current study are consistent with one another and represent a single species. The vaginal armature of these worms is unique and differs from all other genera within the Microcotylinae, including Bivagina, and its movement to Omanicotyle n. gen. to accommodate this species is proposed. Conclusions: A new genus, Omanicotyle n. gen., is erected to accommodate Omanicotyle [Bivagina] heterospina n. comb. which represents the first monogenean to be described from Omani marine waters. Given the pathogenic potential of microcotylids on captive held fish stocks, a full assessment of Omanicotyle heterospina n. gen. et n. comb. is now required before large-scale production commences

    Ultra-High Energy Cosmic Rays, Superheavy Long-Living Particles, and Matter Creation after Inflation

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    The highest energy cosmic rays, above the Greisen-Zatsepin-Kuzmin cut-off of cosmic ray spectrum, may be produced in decays of superheavy long-living X-particles. We conjecture that these particles may be produced naturally in the early Universe from vacuum fluctuations during inflation and may constitute a considerable fraction of Cold Dark Matter. We predict a new cut-off in the UHE cosmic ray spectrum E_{cut-off} < m_inflaton \approx 10^{13} GeV, the exact position of the cut-off and the shape of the cosmic ray spectrum beyond the GZK cut-off being determined by the QCD quark/gluon fragmentation. The Pierre Auger Project installation might discover this phenomenon.Comment: LaTeX, 8 page

    Modulational instability of bright solitary waves in incoherently coupled nonlinear Schr\"odinger equations

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    We present a detailed analysis of the modulational instability (MI) of ground-state bright solitary solutions of two incoherently coupled nonlinear Schr\"odinger equations. Varying the relative strength of cross-phase and self-phase effects we show existence and origin of four branches of MI of the two-wave solitary solutions. We give a physical interpretation of our results in terms of the group velocity dispersion (GVD) induced polarization dynamics of spatial solitary waves. In particular, we show that in media with normal GVD spatial symmetry breaking changes to polarization symmetry breaking when the relative strength of the cross-phase modulation exceeds a certain threshold value. The analytical and numerical stability analyses are fully supported by an extensive series of numerical simulations of the full model.Comment: Physical Review E, July, 199
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