Partition dimension of projective planes

We determine the partition dimension of the incidence graph G(Πq) of the projective plane Πq up to a constant factor 2 as (2+o(1))log2q≤pd(G(Πq))≤(4+o(1))log2q. © 2017 Elsevier Lt

Evolution of locally excited avalanches in semiconductors

We show that semiconductor avalanche photodiodes can exhibit diminutive amplification noise during the early evolution of avalanches. The noise is so low that the number of locally excited charges that seed each avalanche can be resolved. These findings constitute an important first step towards realization of a solid-state noiseless amplifier. Moreover, we believe that the experimental setup used, \textit{i.e.}, time-resolving locally excited avalanches, will become a useful tool for optimizing the number resolution

Efficient photon number detection with silicon avalanche photodiodes

We demonstrate an efficient photon number detector for visible wavelengths using a silicon avalanche photodiode. Under subnanosecond gating, the device is able to resolve up to four photons in an incident optical pulse. The detection efficiency at 600 nm is measured to be 73.8%, corresponding to an avalanche probability of 91.1% of the absorbed photons, with a dark count probability below 1.1x10^{-6} per gate. With this performance and operation close to room temperature, fast-gated silicon avalanche photodiodes are ideal for optical quantum information processing that requires single-shot photon number detection

Continuous operation of high bit rate quantum key distribution

We demonstrate a quantum key distribution with a secure bit rate exceeding 1 Mbit/s over 50 km fiber averaged over a continuous 36-hours period. Continuous operation of high bit rates is achieved using feedback systems to control path length difference and polarization in the interferometer and the timing of the detection windows. High bit rates and continuous operation allows finite key size effects to be strongly reduced, achieving a key extraction efficiency of 96% compared to keys of infinite lengths.Comment: four pages, four figure

Sensitivity analysis of a land surface scheme using multicriteria methods

Attempts to model surface-atmosphere interactions with greater physical realism have resulted in complex land surface schemes (LSS) with large numbers of parameters. A companion paper describes a multicriteria calibration procedure for extracting plot-scale estimates of the preferred ranges of these parameters from the various observational data sets that are now available. A complementary procedure is presented in this paper that provides an objective determination of the multicriteria sensitivity of the modeled variables to the parameters, thereby allowing the number of calibration parameters and hence the computational effort to be reduced. Two case studies are reported for the BATS model using data sets of typical quality but very different location and climatological regime (ARM-CART and Tucson). The sensitivity results were found to be consistent with the physical properties of the different environments, thereby supporting the reasonableness of the model formulation. Further, when the insensitive parameters are omitted from the calibration process, there is little degradation in the quality of the model description and little change in the preferred range of the remaining parameters. Copyright 1999 by the American Geophysical Union

Parameter estimation of a land surface scheme using multicriteria methods

Attempts to create models of surface-atmosphere interactions with greater physical realism have resulted in land surface schemes (LSS) with large numbers of parameters. The hope has been that these parameters can be assigned typical values by inspecting the literature. The potential for using the various observational data sets that are now available to extract plot-scale estimates for the parameters of a complex LSS via advanced parameter estimation methods developed for hydrological models is explored in this paper. Results are reported for two case studies using data sets of typical quality but very different location and climatological regime (ARM-CART and Tucson). The traditional single-criterion methods were found to be of limited value. However, a multicriteria approach was found to be effective in constraining the parameter estimates into physically plausible ranges when observations on at least one appropriate heat flux and one properly selected state variable are available. Copyright 1999 by the American Geophysical Union

Probing higher order correlations of the photon field with photon number resolving avalanche photodiodes

We demonstrate the use of two high speed avalanche photodiodes in exploring higher order photon correlations. By employing the photon number resolving capability of the photodiodes the response to higher order photon coincidences can be measured. As an example we show experimentally the sensitivity to higher order correlations for three types of photon sources with distinct photon statistics. This higher order correlation technique could be used as a low cost and compact tool for quantifying the degree of correlation of photon sources employed in quantum information science

A forensic geoscience framework and practice

Appropriate and correct collection, analysis, interpretation, and presentation of geoforensic evidence are contingent upon understanding the specific context of the particular forensic investigation undertaken. To achieve this, the role of experimental studies in forensic geoscience must not be underestimated. In this article, we present two experimental studies that assess the spatial distribution of pollen in a living room and the nature of subsequent transfer of pollen onto clothing. The presence of cut flowers in a living room are shown to lead to a distribution of pollen grains onto all types of surface in that room that exhibits a distance–decay pattern with the greatest numbers of grains found in close proximity to the flowers. Once the transfer of pollen grains from a source location onto clothing has taken place, our second study demonstrates the nature of the persistence of that evidence for dry and damp clothing under active and inactive conditions. The level of activity after transfer is shown to have far more influence upon the persistence of this form of geoforensic evidence in comparison to the damp or dry conditions of the garment. We argue that these findings have implications for all stages of the forensic investigation–from sampling protocols to the interpretation of the presence/absence of geoforensic evidence. Whilst every contact does indeed leave a trace, it is imperative that there is an appreciation of the context of each forensic investigation, meaningful science take place and accurate and helpful crime reconstructions to be achieved

Pathogenecity of two strains of rice yellow mottle virus on aromatic rice cultivars

Development of rice cultivars with resistance to rice yellow mottle virus (RYMV) requires characterization of pathogenecity of existing strains against susceptible cultivars. The pathogenecity of two RYMV strains; S4 and S“New” identified in Tanzania were assessed against seven local and introduced rice genotypes including cultivars Zambia, ITA173 and TXD 88. The two virus strains showed similar effects on the rice cultivar Zambia killing all the plants at 25d after inoculation. The strains significantly reduced the plant height, panicle length, and number of tillers per pot and total dry matter of all the two cultivars. In another trial, the pathogenecity of the two strains was assessed against four aromatic rice cultivars M-69-9, Loya, Shingo ya mwali and Motisoro. The analysis of variance revealed significant differences only among cultivars for all plant parameters except for the disease severity, which showed significant statistical differences for cultivars, strains and their interactions. The strain S“New” caused more severe disease incidences on inoculated plants than S-4 strain indicating its appropriateness to use in screening for RYMV resistance due to its aggressiveness on susceptible rice genotypes. Tanzania Journal of Science Vol. 32 (1) 2006: pp. 53-6

CROSS SECTIONS FOR SCATTERING OF ELECTRONS ON BF3

We calculate cross sections for elastic scattering and electronic excitation of BF3 molecules by low energy electrons. The R-Matrix code Quantemol-N has been used for calculations. The cross sections indicate the presence of a shape resonance of symmetry B-1 (A(2)'' in D-3h) at around 4.5 eV