Moduli of vortices and Grassmann manifolds

We use the framework of Quot schemes to give a novel description of the moduli spaces of stable n-pairs, also interpreted as gauged vortices on a closed Riemann surface with target Mat(r x n, C), where n >= r. We then show that these moduli spaces embed canonically into certain Grassmann manifolds, and thus obtain natural Kaehler metrics of Fubini-Study type; these spaces are smooth at least in the local case r=n. For abelian local vortices we prove that, if a certain "quantization" condition is satisfied, the embedding can be chosen in such a way that the induced Fubini-Study structure realizes the Kaehler class of the usual L^2 metric of gauged vortices.Comment: 22 pages, LaTeX. Final version: last section removed, typos corrected, two references added; to appear in Commun. Math. Phy

Molecular gas in QSO host galaxies

We present the results of a survey for CO line emission from a sample of nearby QSO hosts taken from the Hamburg/ESO survey (HES) and the Veron-Cetty and Veron quasar catalogue. From a total of 39 observed sources we clearly detected 5 objects with >10sigma signals (HE 0108-4743, HE 0224-2834, J035818.7-612407, HE 1029-1831, HE 2211-3903). Further 6 sources show marginal detections on the 2sigma level.Comment: 4 pages, 1 figure, submitted to "QSO Hosts: Evolution and Environment", P.D. Barthel, D.B. Sanders, eds., August 2005, Leiden University (The Netherlands), New Astr. Re

Deliquescence, efflorescence, and phase miscibility of mixed particles of ammonium sulfate and isoprene-derived secondary organic material

The hygroscopic phase transitions of ammonium sulfate mixed with isoprene-derived secondary organic material were investigated in aerosol experiments. The organic material was produced by isoprene photo-oxidation at 40% and 60% relative humidity. The low volatility fraction of the photo-oxidation products condensed onto ammonium sulfate particles. The particle-phase organic material had oxygen-to-carbon ratios of 0.67 to 0.74 (±0.2) for mass concentrations of 20 to 30 μg m<sup>−3</sup>. The deliquescence, efflorescence, and phase miscibility of the mixed particles were investigated using a dual arm tandem differential mobility analyzer. The isoprene photo-oxidation products induced deviations in behavior relative to pure ammonium sulfate. Compared to an efflorescence relative humidity (ERH) of 30 to 35% for pure ammonium sulfate, efflorescence was eliminated for aqueous particles having organic volume fractions <i>ϵ</i> of 0.6 and greater. Compared to a deliquescence relative humidity (DRH) of 80% for pure ammonium sulfate, the DRH steadily decreased with increasing <i>ϵ</i>, approaching a DRH of 40% for <i>ϵ</i> of 0.9. Parameterizations of the DRH(<i>ϵ</i>) and ERH(<i>ϵ</i>) curves were as follows: DRH(<i>ϵ</i>)= ∑<sub><i>i</i></sub> <i>c</i><sub><i>i,d</i></sub> <i>ϵ</i><sup><i>i</i></sup> valid for 0 ≤ <i>ϵ</i> ≤0.86 and ERH(<i>ϵ</i>)= ∑ <sub><i>i</i></sub> <i>c</i><sub><i>i,e</i></sub> <i>ϵ</i><sup><i>i</i></sup> valid for 0 ≤ <i>ϵ</i> ≤ 0.55 for the coefficients <i>c</i><sub>0,<i>d</i></sub>= 80.67, <i>c</i><sub>0,<i>e</i></sub> = 28.35, <i>c</i><sub>1,<i>d</i></sub> = −11.45, <i>c</i><sub>1,<i>e</i></sub> = −13.66, <i>c</i><sub>2,<i>d</i></sub> = 0, <i>c</i><sub>2,<i>e</i></sub> = 0, <i>c</i><sub>3,<i>d</i></sub> = 57.99, <i>c</i><sub>3,<i>e</i></sub> = -83.80, <i>c</i><sub>4,<i>d</i></sub> = −106.80, and <i>c</i><sub>4,<i>e</i></sub> = 0. The molecular description that is thermodynamically implied by these strongly sloped DRH(<i>ϵ</i>) and ERH(<i>ϵ</i>) curves is that the organic isoprene photo-oxidation products, the inorganic ammonium sulfate, and water form a miscible liquid phase even at low relative humidity. This phase miscibility is in contrast to the liquid-liquid separation that occurs for some other types of secondary organic material. These differences in liquid-liquid separation are consistent with a prediction recently presented in the literature that the bifurcation between liquid-liquid phase separation versus mixing depends on the oxygen-to-carbon ratio of the organic material. The conclusions are that the influence of secondary organic material on the hygroscopic properties of ammonium sulfate varies with organic composition and that the degree of oxygenation of the organic material, which is a measurable characteristic of complex organic materials, is an important variable influencing the hygroscopic properties of mixed organic-inorganic particles

Brauer group of moduli spaces of pairs

We show that the Brauer group of any moduli space of stable pairs with fixed determinant over a curve is zero.Comment: 12 pages. Final version, accepted in Communications in Algebr

A C3(H20) recycling pathway is a component of the intracellular complement system

An intracellular complement system (ICS) has recently been described in immune and nonimmune human cells. This system can be activated in a convertase-independent manner from intracellular stores of the complement component C3. The source of these stores has not been rigorously investigated. In the present study, Western blotting identified a band corresponding to C3 in freshly isolated human peripheral blood cells that was absent in corresponding cell lines. One difference between native cells and cell lines was the time absent from a fluid-phase complement source; therefore, we hypothesized that loading C3 from plasma was a route of establishing intracellular C3 stores. We found that many types of human cells specifically internalized C3(H(2)O), the hydrolytic product of C3, and not native C3, from the extracellular milieu. Uptake was rapid, saturable, and sensitive to competition with unlabeled C3(H(2)O), indicating a specific mechanism of loading. Under steady-state conditions, approximately 80% of incorporated C3(H(2)O) was returned to the extracellular space. These studies identify an ICS recycling pathway for C3(H(2)O). The loaded C3(H(2)O) represents a source of C3a, and its uptake altered the cytokine profile of activated CD4(+) T cells. Importantly, these results indicate that the impact of soluble plasma factors should be considered when performing in vitro studies assessing cellular immune function

Efficient single-photon emission from electrically driven InP quantum dots epitaxially grown on Si(001)

The heteroepitaxy of III-V semiconductors on silicon is a promising approach for making silicon a photonic platform for on-chip optical interconnects and quantum optical applications. Monolithic integration of both material systems is a long-time challenge, since different material properties lead to high defect densities in the epitaxial layers. In recent years, nanostructures however have shown to be suitable for successfully realising light emitters on silicon, taking advantage of their geometry. Facet edges and sidewalls can minimise or eliminate the formation of dislocations, and due to the reduced contact area, nanostructures are little affected by dislocation networks. Here we demonstrate the potential of indium phosphide quantum dots as efficient light emitters on CMOS-compatible silicon substrates, with luminescence characteristics comparable to mature devices realised on III-V substrates. For the first time, electrically driven single-photon emission on silicon is presented, meeting the wavelength range of silicon avalanche photo diodes' highest detection efficiency

Jobseekers Regime and Flexible New Deal, the Six Month Offer and Support for the Newly Unemployed evaluations: An early process study

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