690 research outputs found

    On stirling numbers of the second kind

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    AbstractWe first find inequalities between the Stirling numbers S(n, r) for fixed n, then introduce functions L and U such that L(n, r)≤S(n, r)≤U(n, r), and finally obtain the asymptotic value n/log n for the value of r for which S(n, r) is maximal

    Collisionless hydrodynamics for 1D motion of inhomogeneous degenerate electron gases: equivalence of two recent descriptions

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    Recently I. Tokatly and O. Pankratov (''TP'', Phys. Rev. B 60, 15550 (1999)) used velocity moments of a semiclassical kinetic equation to derive a hydrodynamic description of electron motion in a degenerate electron gas. Independently, the present authors (Theochem 501-502, 327 (2000)) used considerations arising from the Harmonic Potential Theorem (Phys. Rev. Lett. 73, 2244 (1994)) to generate a new form of high-frequency hydrodynamics for inhomogeneous degenerate electron gases (HPT-N3 hydrodynamics). We show here that TP hydrodynamics yields HPT-N3 hydrodynamics when linearized about a Thomas-Fermi groundstate with one-dimensional spatial inhomnogeneity.Comment: 17p

    Eimeria chinchillae De Vos & Van der Westhuizen, 1968 and other Eimeria spp. from three South African rodent species

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    Eimeria chinchillae De Vos & Van der Westhuizen, 1968, an organism originally described from the chinchilla and subsequently shown to be transmissible to other rodents, was found to occur naturally in Rhabdomys pumilio (Sparrman, 1784) in South Africa. The morphology of the oocysts, the site of development of the endogenous stages and the prepatent period of the infection were similar to those of E. chinchillae obtained from chinchillas and transmitted experimentally to R. pumilio. The identity of the organism was confirmed by the successful infection of chinchillas. Three additional Eimeria spp. were found in R. pumilio. Oocysts of Eimeria pumilioi n. sp. measured 18 by 12 µ, those of Eimeria rhabdomyis n. sp., 13 by 12 µ and those of Eimeria pretoriensis n. sp., 24 by 19 µ. Two Eimeria spp. were also found in Praomys (Mastomys) natalensis (Smith, 1834). Oocysts of Eimeria mastomyis n. sp. measured 27 by 21 µ and those of Eimeria theileri n. sp. 20 by 17 µ. A single Eimeria sp., Eimeria otomyis n. sp., was found in Otomys irroratus (Brants, 1827). The oocysts measured 20 by 15 µ.The journals have been scanned in colour with a HP 5590 scanner; 600 dpi. Adobe Acrobat v.11 was used to OCR the text and also for the merging and conversion to the final presentation PDF-format..mn201

    Distributed Generation and Resilience in Power Grids

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    We study the effects of the allocation of distributed generation on the resilience of power grids. We find that an unconstrained allocation and growth of the distributed generation can drive a power grid beyond its design parameters. In order to overcome such a problem, we propose a topological algorithm derived from the field of Complex Networks to allocate distributed generation sources in an existing power grid.Comment: proceedings of Critis 2012 http://critis12.hig.no

    Microfluidics for Small-Angle X-ray Scattering

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    Small-angle X-ray scattering is a well-established biophysical technique, whilst micro-fluidics is proving to be a convenient technology for creating miniaturised multifunctional devices. Both fields are highly versatile and find use in multiple scientific disciplines. Together, they offer the potential to obtain structural information on biomacromolecules, nanoparticles and condensed matter, in a high-throughput manner and with enhanced time-resolution capabilities. This chapter provides practical design considerations for X-ray-based microfluidic systems and examines some of the existing microfluidic platforms used in conjunction with small-angle X-ray scattering. As the exclusive advantages of microfluidics become recognised and accessible, the prevalence of microfluidic sample environments in X-ray scattering measurements will hopefully increase

    Statistical inaccuracies over use of facial skin care products and sunscreens in the aetiology of frontal fibrosing alopecia: reply from authors.

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    We did not perform a matched one-to-one comparison between FFA subjects and controls, we compared two groups with similar ages. The only continuous variable was age. The responses to the questions posed were categorical. We therefore maintain that a Fisher's exact test rather than a McNemar's test was an appropriate method for analyzing the results

    The SF3B1 inhibitor spliceostatin A (SSA) elicits apoptosis in chronic lymphocytic leukemia cells through downregulation of Mcl-1

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    The pro-survival Bcl-2 family member Mcl-1 is expressed in chronic lymphocytic leukemia (CLL), with high expression correlated with progressive disease. The spliceosome inhibitor spliceostatin A (SSA), is known to regulate Mcl-1 and so here we assessed the ability of SSA to elicit apoptosis in CLL. SSA induced apoptosis of CLL cells at low nanomolar concentrations in a dose- and time-dependent manner, but independently of SF3B1 mutational status, IGHV status and CD38 or ZAP70 expression. However, normal B and T cells were less sensitive than CLL cells (P=0.006 and P<0.001, respectively). SSA altered the splicing of anti-apoptotic MCL-1L to MCL-1s in CLL cells coincident with induction of apoptosis. Overexpression studies in Ramos cells suggested Mcl-1 was important for SSA-induced killing since its expression inversely correlated with apoptosis (P=0.001). IL4 and CD40L, present in patient lymph nodes, are known to protect tumor cells from apoptosis and significantly inhibited SSA, ABT-263 and ABT-199 induced killing following administration to CLL cells (P=0.008). However, by combining SSA with the Bcl-2/Bcl-xL antagonists ABT-263 or ABT-199, we were able to overcome this pro-survival effect. We conclude that SSA combined with Bcl-2/Bcl-xL antagonists may have therapeutic utility for CL

    Spin Resolution of the Electron-Gas Correlation Energy: Positive same-spin contribution

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    The negative correlation energy per particle of a uniform electron gas of density parameter rsr_s and spin polarization ζ\zeta is well known, but its spin resolution into up-down, up-up, and down-down contributions is not. Widely-used estimates are incorrect, and hamper the development of reliable density functionals and pair distribution functions. For the spin resolution, we present interpolations between high- and low-density limits that agree with available Quantum Monte Carlo data. In the low-density limit for ζ=0\zeta = 0, we find that the same-spin correlation energy is unexpectedly positive, and we explain why. We also estimate the up and down contributions to the kinetic energy of correlation.Comment: new version, to appear in PRB Rapid Communicatio

    Genomic Deletion Marking an Emerging Subclone of Francisella tularensis subsp. holarctica in France and the Iberian Peninsula

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    P. 7465-7470Francisella tularensis subsp. holarctica is widely disseminated in North America and the boreal and temperate regions of the Eurasian continent. Comparative genomic analyses identified a 1.59-kb genomic deletion specific to F. tularensis subsp. holarctica isolates from Spain and France. Phylogenetic analysis of strains carrying this deletion by multiple-locus variable-number tandem repeat analysis showed that the strains comprise a highly related set of genotypes, implying that these strains were recently introduced or recently emerged by clonal expansion in France and the Iberian PeninsulaS
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