1,791 research outputs found

    A Note on Diogmitae

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    published or submitted for publicatio

    Μαρτυρία для Аполлония Тианского

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    Автор ставит задачу проанализировать одно из т.н. писем Аполлония Тианского. Исследователь доказывает, что письмо это точно соответствует форме официального "свидетельства о заслугах", и делает попытку подтвердить существующее в историографии наблюдение, что автором письма был не император Клавдий, а некий римский гражданин, имя которого было вычеркнуто из текста

    A guide to the construction of the DGSM Nottingham Melton Lithoframe 50K Colston Bassett Gocad model

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    This report describes the rationale behind the construction of the Nottingham Melton Lithoframe 50K GOCAD model for the Colston Bassett area. This work was carried out between April 2001-March 2005, as part of the Nottingham Melton DGSM-UK project (E1362S96 Task 06). This model comprises part of the area covered by the Melton 50K geological map sheet (142)

    Fields Annihilation and Particles Creation in DBI inflation

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    We consider a model of DBI inflation where two stacks of mobile branes are moving ultra relativistically in a warped throat. The stack closer to the tip of the throat is annihilated with the background anti-branes while inflation proceeds by the second stack. The effects of branes annihilation and particles creation during DBI inflation on the curvature perturbations power spectrum and the scalar spectral index are studied. We show that for super-horizon scales, modes which are outside the sound horizon at the time of branes collision, the spectral index has a shift to blue spectrum compared to the standard DBI inflation. For small scales the power spectrum approaches to its background DBI inflation value with the decaying superimposed oscillatory modulations.Comment: First revision: minor changes, the background spectral index is corrected, new references are added. Second revision: minor changes, new references are added, accepted for publication in JCA

    Inflation on Fractional Branes: D--Brane Inflation as D--Term Inflation

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    We describe a D--brane inflation model which consists of two fractional D3 branes separated on a transverse T2×K3T^2 \times K3. Inflation arises due to the resolved orbifold singularity of K3K3 which corresponds to an anomalous D--term on the brane. We show that D--brane inflation in the bulk corresponds to D--term inflation on the brane. The inflaton and the trigger field parametrize the interbrane distances on T2T^2 an K3K3 respectively. After inflation the branes reach a supersymmetric configuration in which they are at the origin of T2T^2 but separated along the K3K3 directions.Comment: 15 pages in phyzzx.tex; minor corrections including all factors of 2\pi; v3: more minor correction

    Cosmology and two-body problem of D-branes

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    In this paper, we investigate the dynamics and the evolution of the scale factor of a probe Dp-brane which move in the background of source Dp-branes. Action of the probe brane is described by the Born-Infeld action and the interaction with the background R-R field. When the probe brane moves away from the source branes, it expands by power law, whose index depends on the dimension of the brane. If the energy density of the gauge field on the brane is subdominant, the expansion is decelerating irrespective of the dimension of the brane. On the other hand, when the probe brane is a Nambu-Goto brane, the energy density of the gauge field can be dominant, in which case accelerating expansion occurs for p4p \leq 4. The accelerating expansion stops when the brane has expanded sufficiently so that the energy density of the gauge field become subdominant.Comment: 6 pages, 7 figures, reference added, accepted for publication in PR

    Inflation in Realistic D-Brane Models

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    We find successful models of D-brane/anti-brane inflation within a string context. We work within the GKP-KKLT class of type IIB string vacua for which many moduli are stabilized through fluxes, as recently modified to include `realistic' orbifold sectors containing standard-model type particles. We allow all moduli to roll when searching for inflationary solutions and find that inflation is not generic inasmuch as special choices must be made for the parameters describing the vacuum. But given these choices inflation can occur for a reasonably wide range of initial conditions for the brane and antibrane. We find that D-terms associated with the orbifold blowing-up modes play an important role in the inflationary dynamics. Since the models contain a standard-model-like sector after inflation, they open up the possibility of addressing reheating issues. We calculate predictions for the CMB temperature fluctuations and find that these can be consistent with observations, but are generically not deep within the scale-invariant regime and so can allow appreciable values for dns/dlnkdn_s/d\ln k as well as predicting a potentially observable gravity-wave signal. It is also possible to generate some admixture of isocurvature fluctuations.Comment: 39 pages, 21 figures; added references; identified parameters combining successful inflation with strong warping, as needed for consistency of the approximation

    Syncytial nuclear aggregates in normal placenta show increased nuclear condensation, but apoptosis and cytoskeletal redistribution are uncommon

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    AbstractIntroductionSyncytial nuclear aggregates (SNAs) are increased in pregnancy complications; however, little is known about their origin or function. This study aimed to characterise SNAs in more detail than has been reported previously.MethodsImmunohistochemistry and morphological examination at the light and ultrastructural level were used to determine the nature and structure of SNAs.ResultsSNAs comprising bridges and syncytial knots had similar frequency with 974 per mm3 of villous tissue (IQR 717–1193) and 833 per mm3 (IQR 766–1190), respectively while there were approximately four times as many sectioning artefacts than knots and bridges combined. SNAs had increased proportions of condensed nuclei compared to the remaining syncytiotrophoblast (33.3% vs. 8.9%) and decreased proportions of euchromatic nuclei (0.0% vs. 16.2%), as assessed by examination of an electron micrograph archive. SNAs showed little evidence of apoptosis, with weak positivity for the apoptosis markers M30-neoepitope at 16.6% and TUNEL at 10.0%; strong staining was rarely seen for either marker. Immunofluorescence demonstrated rare association of actin (α, β or γ) with SNAs, whereas tubulin was in close proximity to SNAs and cytokeratin was seen within and surrounding SNAs.DiscussionM30-positive SNAs traced through serial sections were significantly more likely to be syncytial knots or sectioning artefacts than bridges. Nuclei within SNAs showed signs consistent with degeneration; however, this is unlikely to be an apoptotic process. There are few changes in configuration of cytoskeletal proteins around SNAs.ConclusionsThese data suggest that the biogenesis and functional significance of SNAs still require resolution
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