Within- and between-pen transmission of Classical Swine Fever Virus: a new method to estimate the basic reproduction ratio from transmission experiments

We present a method to estimate basic reproduction ratio R0 from transmission experiments. By using previously published data of experiments with Classical Swine Fever Virus more extensively, we obtained smaller confidence intervals than the martingale method used in the original papers. Moreover, our method allows simultaneous estimation of a reproduction ratio within pens R0w and a modified reproduction ratio between pens R'0b. Resulting estimates of R0w and R'0b for weaner pigs were 100 (95% CI 54.4-186) and 7.77 (4.68-12.9), respectively. For slaughter pigs they were 15.5 (6.20-38.7) and 3.39 (1.54-7.45), respectively. We believe, because of the smaller confidence intervals we were able to obtain, that the method presented here is better suited for use in future experiments

Sustainable Soesterkwartier

The municipality of Amersfoort wants to construct an endurable and sustainable eco-town in the Soesterkwartier neighbourhood, by taking future climate change into account. The impact of climate change at the location of the proposed eco-town was studied by a literature review

Electronic orders near the type-II van Hove singularity in BC3_3

Using the functional renormalization group, we investigate the electron instability in the single-sheet BC$_3$ when the electron filling is near a type-II van Hove singularity. For a finite Hubbard interaction, the ferromagnetic-like spin density wave order dominates in the immediate vicinity of the singularity. Elsewhere near the singularity the p-wave superconductivity prevails. We also find that a small nearest-neighbor Coulomb repulsion can enhance the superconductivity. Our results show that BC$_3$ would be a promising candidate to realize topological $p+ip'$ superconductivity, but the transition temperature is practically sizable only if the local interaction is moderately strong.Comment: 6 pages, 6 color figures. arXiv admin note: text overlap with arXiv:1503.0047

Split-gate quantum point contacts with tunable channel length

We report on developing split-gate quantum point contacts (QPCs) that have a tunable length for the transport channel. The QPCs were realized in a GaAs/AlGaAs heterostructure with a two- dimensional electron gas (2DEG) below its surface. The conventional design uses 2 gate fingers on the wafer surface which deplete the 2DEG underneath when a negative gate voltage is applied, and this allows for tuning the width of the QPC channel. Our design has 6 gate fingers and this provides additional control over the form of the electrostatic potential that defines the channel. Our study is based on electrostatic simulations and experiments and the results show that we developed QPCs where the effective channel length can be tuned from about 200 nm to 600 nm. Length-tunable QPCs are important for studies of electron many-body effects because these phenomena show a nanoscale dependence on the dimensions of the QPC channel

Transport of interacting electrons in arrays of quantum dots and diffusive wires

We develop a detailed theoretical investigation of the effect of Coulomb interaction on electron transport in arrays of chaotic quantum dots and diffusive metallic wires. Employing the real time path integral technique we formulate a new Langevin-type of approach which exploits a direct relation between shot noise and interaction effects in mesoscopic conductors. With the aid of this approach we establish a general expression for the Fano factor of 1D quantum dot arrays and derive a complete formula for the interaction correction to the current which embraces all perturbative results previously obtained for various quasi-0D and quasi-1D disordered conductors and extends these results to yet unexplored regimes.Comment: 12 pages, 2 figure

Stabilizing nuclear spins around semiconductor electrons via the interplay of optical coherent population trapping and dynamic nuclear polarization

We experimentally demonstrate how coherent population trapping (CPT) for donor-bound electron spins in GaAs results in autonomous feedback that prepares stabilized states for the spin polarization of nuclei around the electrons. CPT was realized by excitation with two lasers to a bound-exciton state. Transmission studies of the spectral CPT feature on an ensemble of electrons directly reveal the statistical distribution of prepared nuclear spin states. Tuning the laser driving from blue to red detuned drives a transition from one to two stable states. Our results have importance for ongoing research on schemes for dynamic nuclear spin polarization, the central spin problem and control of spin coherence.Comment: 5 pages, 4 figure

Self-Regulation of Star Formation in Low Metallicity Clouds

We investigate the process of self-regulated star formation via photodissociation of hydrogen molecules in low metallicity clouds. We evaluate the influence region's scale of a massive star in low metallicity gas clouds whose temperatures are between 100 and 10000 Kelvin. A single O star can photodissociate hydrogen molecules in the whole of the host cloud. If metallicity is smaller than about 10^{-2.5} of the solar metallicity, the depletion of coolant of the the host cloud is very serious so that the cloud cannot cool in a free-fall time, and subsequent star formation is almost quenched. On the contrary, if metallicity is larger than about 10^{-1.5} of the solar metallicity, star formation regulation via photodissociation is not efficient. The typical metallicity when this transition occurs is about 1/100 of the solar metallicity. This indicates that stars do not form efficiently before the metallicity becomes larger than about 1/100 of the solar metallicity and we considered that this value becomes the lower limit of the metallicity of luminous objects such as galaxies.Comment: 14 pages, including 5 figures, To appear in ApJ, Vol. 53

Effects of Local Fields on Electron Beam Voltage Measurement Accuracy

Voltages at various levels have been measured on unpassivated aluminum lines in an integrated circuit (IC) test structure with widths and spacings ranging from 1.5 μm to 8 μm. For the measurements a pulsed electron beam (e-beam) system with 1 keV electrons was used in conjunction with a planar retarding field analyzer. Examination of the results shows that the voltage measurement accuracy is affected by local fields created by the potential differences between neighboring conductors on the IC. They also reveal how these fields and measurement errors are related to the conductor line width and spacing, the supply voltage level and the strength of the extraction field above the circuit

Morphological Evolution of Distant Galaxies from Adaptive Optics Imaging

We report here on a sample of resolved, infrared images of galaxies at z~0.5 taken with the 10-m Keck Telescope's Adaptive Optics (AO) system. We regularly achieve a spatial resolution of 0.05'' and are thus able to resolve both the disk and bulge components. We have extracted morphological information for ten galaxies and compared their properties to those of a local sample. The selection effects of both samples were explicitly taken into account in order to derive the unbiased result that disks at z~0.5 are ~0.6 mag arcsec^-2 brighter than, and about the same size as, local disks. The no-luminosity-evolution case is ruled out at 90% confidence. We also find, in a more qualitative analysis, that the bulges of these galaxies have undergone a smaller amount of surface brightness evolution and have also not changed significantly in size from z~0.5 to today. This is the first time this type of morphological evolution has been measured in the infrared and it points to the unique power of AO in exploring galaxy evolution.Comment: 27 pages, 7figures, 2 tables. Accepted for publication in the Astrophysical Journa