MMI partial extraction geochemistry for the resolution of anthropogenic activities across the archaeological Roman town of Calleva Atrebatum

Sixty three soils samples, fourteen samples of previously excavated archaeological material, and five background soil samples taken at the Silchester Roman Town of Calleva Atrebatum in the County of Hampshire, United Kingdom were analysed by the Mobile Metal Ion (MMI) method for a total of fifty three elements. Samples from within the town walls showed considerably higher concentrations than samples outside for many elements; Au, Ag, Cu and Sn were in extremely anomalous concentrations, Bi, Cd, Hg, Mo, P and Pb were anomalous and Sb and Zn in elevated concentrations. The overall pattern of element distribution is one of an annulus of higher elemental concentrations surrounding a centre of generally lower values centred on the previously excavated Forum basilica. The elements Zr, Ti, Th, Ti, Tl, Nb, Sn, Sc, Cr, Co, Sb, Bi, Ce, Nd (and all other REEs), show similar distributions to one another, and their distribution and that of the noble and base metals, as highlighted by various additive indices, is considered to be the result of metallurgical processing on site. The low values for most elements around the Forum basilica are the result of disturbance of the soil geochemical profile in this area by previous archaeological excavation

Discovery of Reflection Nebulosity Around Five Vega-like Stars

Coronagraphic optical observations of six Vega-like stars reveal reflection nebulosities, five of which were previously unknown. The nebulosities illuminated by HD 4881, HD 23362, HD 23680, HD 26676, and HD 49662 resemble that of the Pleiades, indicating an interstellar origin for dust grains. The reflection nebulosity around HD 123160 has a double-arm morphology, but no disk-like feature is seen as close as 2.5 arcsec from the star in K-band adaptive optics data. We demonstrate that uniform density dust clouds surrounding HD 23362, HD 23680 and HD 123160 can account for the observed 12-100 micron spectral energy distributions. For HD 4881, HD 26676, and HD 49662 an additional emission source, such as from a circumstellar disk or non-equilibrium grain heating, is required to fit the 12-25 micron data. These results indicate that in some cases, particularly for Vega-like stars located beyond the Local Bubble (>100 pc), the dust responsible for excess thermal emission may originate from the interstellar medium rather than from a planetary debris system.Comment: The Astrophysical Journal, in press for March, 2002 (32 pages, 13 figures

On the String Consensus Problem and the Manhattan Sequence Consensus Problem

In the Manhattan Sequence Consensus problem (MSC problem) we are given $k$ integer sequences, each of length $l$, and we are to find an integer sequence $x$ of length $l$ (called a consensus sequence), such that the maximum Manhattan distance of $x$ from each of the input sequences is minimized. For binary sequences Manhattan distance coincides with Hamming distance, hence in this case the string consensus problem (also called string center problem or closest string problem) is a special case of MSC. Our main result is a practically efficient $O(l)$-time algorithm solving MSC for $k\le 5$ sequences. Practicality of our algorithms has been verified experimentally. It improves upon the quadratic algorithm by Amir et al.\ (SPIRE 2012) for string consensus problem for $k=5$ binary strings. Similarly as in Amir's algorithm we use a column-based framework. We replace the implied general integer linear programming by its easy special cases, due to combinatorial properties of the MSC for $k\le 5$. We also show that for a general parameter $k$ any instance can be reduced in linear time to a kernel of size $k!$, so the problem is fixed-parameter tractable. Nevertheless, for $k\ge 4$ this is still too large for any naive solution to be feasible in practice.Comment: accepted to SPIRE 201

The Dust Disk around the Vega-Excess Star SAO 26804

We present multiwaveband observations of the K2 Vega-excess star SAO 26804 (= HD 233517). These include James Clerk Maxwell Telescope millimeter-wave photometry, plus spectra in the 8-13 microns and 18-24 microns atmospheric windows, an image at a wavelength of 10 microns through a broadband N filter and near-IR (JHKLL'M) photometry all taken at the United Kingdom Infrared Telescope. The source is resolved at 10 microns, and we can confirm with these observations that the IR excess seen in IRAS observations of this source is associated with the optical star. The image is consistent with the dust being confined to a disk with Full Width at Half Maximum (FWHM) 1.5 sec on the major axis, with an inclination angle of less than 30 deg away from edge-on. This represents the first confirmation that the dust in a Vega-excess star other than beta Pic is confined to a disk geometry. We present models of the source which show that many of the properties of the disk and the dust in it are similar to those which we have previously derived for the disk around SAO 179815, but that there are some very small grains in the disk around the star which give around SAO 179815, but that there are some very small grains in the disk around the star which give rise to a very prominent and narrow silicate dust feature at 9.7 microns and to so-called unidentified infrared bands in the 10 micron region. The larger grains are composed of a mixture of amorphous carbon and silicate with an abundance ratio consistent with an interstellar origin. The total mass of dust in the disk is 3.0 x 10-7 solar mass. Finally, our model suggests that there may be a substantial UV and/or soft X-ray flux from SAO 26804, consistent with it being a very young and rather active star

A Conformally Invariant Holographic Two-Point Function on the Berger Sphere

We apply our previous work on Green's functions for the four-dimensional quaternionic Taub-NUT manifold to obtain a scalar two-point function on the homogeneously squashed three-sphere (otherwise known as the Berger sphere), which lies at its conformal infinity. Using basic notions from conformal geometry and the theory of boundary value problems, in particular the Dirichlet-to-Robin operator, we establish that our two-point correlation function is conformally invariant and corresponds to a boundary operator of conformal dimension one. It is plausible that the methods we use could have more general applications in an AdS/CFT context.Comment: 1+49 pages, no figures. v2: Several typos correcte

A geospatial web-based integrative analytical tool for the water-energy-food nexus: the iWEF 1.0

Introduction The water-energy-food (WEF) nexus has evolved into an important transformative approach for facilitating the timely identification of trade-offs and synergies between interlinked sectors for informed intervention and decision-making. However, there is a growing need for a WEF nexus tool to support decision-making on integrated resources management toward sustainable development. Methods This study developed a geospatial web-based integrative analytical tool for the WEF nexus (the iWEF) to support integrated assessment of WEF resources to support resilience building and adaptation initiatives and strategies. The tool uses the Analytic Hierarchy Process (AHP) to establish numerical correlations among WEF nexus indicators and pillars, mainly availability, productivity, accessibility, and sufficiency. The tool was calibrated and validated with existing tools and data at varying spatio-temporal scales. Results The results indicate the applicability of the tool at any spatial scale, highlighting the moderate sustainability in the management of WEF resources at various scales. The developed iWEF tool has improved the existing integrative WEF nexus analytical tool in terms of processing time and providing geospatial capabilities. Discussion The iWEF tool is a digital platform that automatically guides policy and decision-making in managing risk from trade-offs and enhancing synergies holistically. It is developed to support policy and decision-making on timely interventions in priority areas that could be showing signs of stress

A young and complex binary star - HD 144432

The southern emission-line star HD 144432 has received considerable attention due to its relative brightness (V ~ 8.17), its late spectral type (late A-type or perhaps early F) and its relative isolation from a bona-fide active star formation region. We present new imaging and spectroscopic data of this star, which in the past has been classified as both evolved (post-AGB) object and an isolated Herbig Ae/Be star. We confirm the presence of a faint companion source located 1.4 arcseconds north, which appears physically associated with HD 144432. New infrared spectroscopy reveals this companion to be a late-type (early-mid K) star, devoid of any emission lines. Furthermore, we confirm the pre-main sequence nature of this object, report the detection of Li I 6707.8 AA absorption toward the HD 144432 system, and its apparent association with Sco OB2-2 located at 145 pc.Comment: 9 pages, 11 figures, accepted by A&

Breeding for increased nitrogen-use efficiency: a review for wheat (T. aestivum L.)

Nitrogen fertilizer is the most used nutrient source in modern agriculture and represents significant environmental and production costs. In the meantime, the demand for grain increases and production per area has to increase as new cultivated areas are scarce. In this context, breeding for an efficient use of nitrogen became a major objective. In wheat, nitrogen is required to maintain a photosynthetically active canopy ensuring grain yield and to produce grain storage proteins that are generally needed to maintain a high end-use quality. This review presents current knowledge of physiological, metabolic and genetic factors influencing nitrogen uptake and utilization in the context of different nitrogen management systems. This includes the role of root system and its interactions with microorganisms, nitrate assimilation and its relationship with photosynthesis as postanthesis remobilization and nitrogen partitioning. Regarding nitrogen-use efficiency complexity, several physiological avenues for increasing it were discussed and their phenotyping methods were reviewed. Phenotypic and molecular breeding strategies were also reviewed and discussed regarding nitrogen regimes and genetic diversity

Energetic Processing of Interstellar Silicate Grains by Cosmic Rays

While a significant fraction of silicate dust in stellar winds has a crystalline structure, in the interstellar medium nearly all of it is amorphous. One possible explanation for this observation is the amorphization of crystalline silicates by relatively 'low' energy, heavy ion cosmic rays. Here we present the results of multiple laboratory experiments showing that single-crystal synthetic forsterite (Mg{sub 2}SiO{sub 4}) amorphizes when irradiated by 10 MeV Xe{sup ++} ions at large enough fluences. Using modeling, we extrapolate these results to show that 0.1-5.0 GeV heavy ion cosmic rays can rapidly ({approx}70 Million yrs) amorphize crystalline silicate grains ejected by stars into the interstellar medium