317 research outputs found

    The influence of laser relative intensity noise in the Laser Interferometer Space Antenna

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    LISA is an upcoming ESA mission that will detect gravitational waves in spaceby interferometrically measuring the separation between free-falling testmasses at picometer precision. To reach the desired performance, LISA willemploy the noise reduction technique time-delay interferometry (TDI), in whichmultiple raw interferometric readouts are time shifted and combined into thefinal scientific observables. Evaluating the performance in terms of these TDIvariables requires careful tracking of how different noise sources propagatethrough TDI, as noise correlations might affect the performance in unexpectedways. One example of such potentially correlated noise is the relativeintensity noise (RIN) of the six lasers aboard the three LISA satellites, whichwill couple into the interferometric phase measurements. In this article, wecalculate the expected RIN levels based on the current mission architecture andthe envisaged mitigation strategies. We find that strict requirements on thetechnical design reduce the effect from approximately 8.7 pm/rtHz perinter-spacecraft interferometer to that of a much lower sub-1 pm/rtHz noise,with typical characteristics of an uncorrelated readout noise after TDI. Ourinvestigations underline the importance of sufficient balanced detection of theinterferometric measurements.<br

    On birational involutions of P3P^3

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    Let XX be a rationally connected three-dimensional algebraic variety and let τ\tau be an element of order two in the group of its birational selfmaps. Suppose that there exists a non-uniruled divisorial component of the τ\tau-fixed point locus. Using the equivariant minimal model program we give a rough classification of such elements.Comment: 24 pages, late

    Crossover from spin accumulation into interface states to spin injection in the germanium conduction band

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    Electrical spin injection into semiconductors paves the way for exploring new phenomena in the area of spin physics and new generations of spintronic devices. However the exact role of interface states in spin injection mechanism from a magnetic tunnel junction into a semiconductor is still under debate. In this letter, we demonstrate a clear transition from spin accumulation into interface states to spin injection in the conduction band of nn-Ge. We observe spin signal amplification at low temperature due to spin accumulation into interface states followed by a clear transition towards spin injection in the conduction band from 200 K up to room temperature. In this regime, the spin signal is reduced down to a value compatible with spin diffusion model. More interestingly, we demonstrate in this regime a significant modulation of the spin signal by spin pumping generated by ferromagnetic resonance and also by applying a back-gate voltage which are clear manifestations of spin current and accumulation in the germanium conduction band.Comment: 5 pages, 4 figure

    Spinoza

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    "Spinoza", second edition. Encyclopedia entry for the Springer Encyclopedia of EM Phil and the Sciences, ed. D. Jalobeanu and C. T. Wolfe

    Interacting Preformed Cooper Pairs in Resonant Fermi Gases

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    We consider the normal phase of a strongly interacting Fermi gas, which can have either an equal or an unequal number of atoms in its two accessible spin states. Due to the unitarity-limited attractive interaction between particles with different spin, noncondensed Cooper pairs are formed. The starting point in treating preformed pairs is the Nozi\`{e}res-Schmitt-Rink (NSR) theory, which approximates the pairs as being noninteracting. Here, we consider the effects of the interactions between the Cooper pairs in a Wilsonian renormalization-group scheme. Starting from the exact bosonic action for the pairs, we calculate the Cooper-pair self-energy by combining the NSR formalism with the Wilsonian approach. We compare our findings with the recent experiments by Harikoshi {\it et al.} [Science {\bf 327}, 442 (2010)] and Nascimb\`{e}ne {\it et al.} [Nature {\bf 463}, 1057 (2010)], and find very good agreement. We also make predictions for the population-imbalanced case, that can be tested in experiments.Comment: 10 pages, 6 figures, accepted version for PRA, discussion of the imbalanced Fermi gas added, new figure and references adde

    Sinteza i biološko djelovanje novih supstituiranih derivata tiazolin-kinolina

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    5-Acyl-8-hydroxyquinoline-2-(3\u27-substituted-4\u27-aryl-2,3-dihydrothiazol-2\u27-ylide- ne)hydrazones, 5a-e to 10a-c, were prepared by the reaction of the appropriate 5-acyl-8-hydroxyquinoline-4-substituted thiosemicarbazones 3a-e and phenacyl bromides 4a-e. Structures of the new compounds were verified on the basis of spectral and elemental analyses. Twenty-eight new compounds were tested for their possible antimicrobial activities. Most of the tested compounds showed weak to moderate antibacterial activity against most of the bacterial strains used in comparison with gatifloxacin as a reference drug. The test compounds showed weak to moderate antifungal activity against tested fungi in comparison with ketoconazole as a reference drug. On the other hand, the newly synthesized compounds were tested for their anti-inflammatory effects and most of them showed good to excellent anti-inflammatory activity compared to indomethacin. Moreover, ulcerogenicity and the median lethal dose (LD50) of the most active anti-inflammatory compounds 6b and 9e were determined in mice; they were non-toxic at doses up to 400 mg kg-1 after i.p. administration.5-Acil-8-hidroksikinolin-2-(3\u27-supstituirani-4\u27-aril-2,3-dihidrotiazol-2\u27-ilid- ne)hidrazoni 5a-e do 10a-c pripravljeni su reakcijom odgovarajućih 5-acil-8-hidroksikinolin-4-supstituiranih tiosemikarbazona 3a-e i fenacil bromida 4a-e. Strukture novih spojeva potvrđene su na temelju spektralnih i elementarnih analiza. Dvadeset osam novih spojeva testirano je na potencijalno antimikrobno djelovanje. Većina spojeva pokazuje slabo do umjereno antibakterijsko djelovanje protiv većine testiranih bakterijskih sojeva u usporedbi s gatifloksacinom kao referentim lijekom, te slabo do umjereno antifungalno djelovanje protiv gljivica u usporedbi s ketokonazolom kao referentnim lijekom. Testovi na protuupalno djelovanje pokazuju da većina spojeva posjeduje dobro ili snažno protuupalno djelovanje u usporedbi s indometacinom. Ulcerogeno djelovanje i srednje letalne doze (LD50) najaktivnijih spojeva 6b i 9e određeni su na miševima. Rezultati pokazuju da su netoksični u dozama do 400 mg kg-1 nakon i.p. primjene

    Structure and inhibitory effects on angiogenesis and tumor development of a new vascular endothelial growth inhibitor

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    Blocking angiogenesis is an attractive strategy to inhibit tumor growth, invasion, and metastasis. We describe here the structure and the biological action of a new cyclic peptide derived from vascular endothelial growth factor (VEGF). This 17-amino acid molecule designated cyclopeptidic vascular endothelial growth inhibitor (cyclo-VEGI, CBO-P11) encompasses residues 79-93 of VEGF which are involved in the interaction with VEGF receptor-2. In aqueous solution, cyclo-VEGI presents a propensity to adopt a helix conformation that was largely unexpected because only \u3b2-sheet structures or random coil conformations have been observed for macrocyclic peptides. Cyclo-VEGI inhibits binding of iodinated VEGF165 to endothelial cells, endothelial cells proliferation, migration, and signaling induced by VEGF165. This peptide also exhibits anti-angiogenic activity in vivo on the differentiated chicken chorioallantoic membrane. Furthermore, cyclo-VEGI significantly blocks the growth of established intracranial glioma in nude and syngeneic mice and improves survival without side effects. Taken together, these results suggest that cyclo-VEGI is an attractive candidate for the development of novel angiogenesis inhibitor molecules useful for the treatment of cancer and other angiogenesis-related diseases
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