Contours and Contouring in Hydrography Part II - Interpolation

In Part I of this series, the authors discussed those issues which we feel are fundamentally important and which must be addressed by any method which aims to mechanize the drawing of depth contours for hydrographic charts. In this article we begin the discussion of the How of contouring. In particular, we concentrate on some of the most common methods used in the interpolation of the synthetic surface upon which computed contours will lie

A Review of the Relationship of the ENC and DNC Hydrographic Vector Data Products

This document discusses the level of harmonization between the S-57 and DIGEST standards and the relationship between the ENC and DNC products. It is shown that the military and regulated commercial navigation have different needs, and that it is natural to have two different standards. However, in those areas where the needs overlap the standards should be equivalent. Commercial navigation requires "official" data whereas the military require a broad range of the "best available data". These needs are complementary. At the content level ENC data can be a pure subset of DNC data, however additional harmonization is required to achieve this

Systems biology of energetic and atomic costs in the yeast transcriptome, proteome, and metabolome

Proteins vary in their cost to the cell and natural selection may favour the use of proteins that are cheaper to produce. We develop a novel approach to estimate the amino acid biosynthetic cost based on genome-scale metabolic models, and directly investigate the effects of biosynthetic cost on transcriptomic, proteomic and metabolomic data in _Saccharomyces cerevisiae_. We find that our systems approach to formulating biosynthetic cost produces a novel measure that explains similar levels of variation in gene expression compared with previously reported cost measures. Regardless of the measure used, the cost of amino acid synthesis is weakly associated with transcript and protein levels, independent of codon usage bias. In contrast, energetic costs explain a large proportion of variation in levels of free amino acids. In the economy of the yeast cell, there appears to be no single currency to compute the cost of amino acid synthesis, and thus a systems approach is necessary to uncover the full effects of amino acid biosynthetic cost in complex biological systems that vary with cellular and environmental conditions

CLME: An R Package for Linear Mixed Effects Models under Inequality Constraints

In many applications researchers are typically interested in testing for inequality constraints in the context of linear fixed effects and mixed effects models. Although there exists a large body of literature for performing statistical inference under inequality constraints, user friendly statistical software implementing such methods is lacking, especially in the context of linear fixed and mixed effects models. In this article we introduce CLME, a package in the R language that can be used for testing a broad collection of inequality constraints. It uses residual bootstrap based methodology which is reasonably robust to non-normality as well as heteroscedasticity. The package is illustrated using two data sets. The package also contains a graphical user interface built using the shiny package

Impacts of Forage Cropping Decisions on Feed-Flows in Cool- Temperate Grazing Systems

Intensive cool-temperate grasslands often rely on adding forage crops to help supply feed when pasture growth is limited by cool temperatures and low sunlight. We tested the impacts of using single- or multi-graze crops to alter feed supply in either summer/autumn or winter on productivity in red deer farming systems in a cool-temperate environment. The choice of single-graze or multi-graze crops to provide forage in deer grazing systems had an impact on the feed flows and the amount of pasture available, with multi-graze crops supplying more feed during the dry summer months while single-graze crops supplying more feed during the cool winter months. The limited growth rates of young red deer, and the late calving of hinds meant that pasture covers could be low during the late winter and early spring without compromising animal production. Overall, the use of a multi-graze crop, especially when used early in autumn to promote weaner liveweight gain, increased overall productivity by 5% and increased feed conversion efficiency by 2.5% in the venison production system

PC1643+4631A,B: The Lyman-Alpha Forest at the Edge of Coherence

This is the first measurement and detection of coherence in the intergalactic medium (IGM) at substantially high redshift (z~3.8) and on large physical scales (~2.5 h^-1 Mpc). We perform the measurement by presenting new observations from Keck LRIS of the high redshift quasar pair PC 1643+4631A, B and their Ly-alpha absorber coincidences. This experiment extends multiple sightline quasar absorber studies to higher redshift, higher opacity, larger transverse separation, and into a regime where coherence across the IGM becomes weak and difficult to detect. We fit 222 discrete Ly-alpha absorbers to sightline A and 211 to sightline B. Relative to a Monte Carlo pairing test (using symmetric, nearest neighbor matching) the data exhibit a 4sigma excess of pairs at low velocity splitting (<150 km/s), thus detecting coherence on transverse scales of ~2.5 h^-1 Mpc. We use spectra extracted from an SPH simulation to analyze symmetric pair matching, transmission distributions as a function of redshift and compute zero-lag cross-correlations to compare with the quasar pair data. The simulations agree with the data with the same strength (~4sigma) at similarly low velocity splitting above random chance pairings. In cross-correlation tests, the simulations agree when the mean flux (as a function of redshift) is assumed to follow the prescription given by Kirkman et al. (2005). While the detection of flux correlation (measured through coincident absorbers and cross-correlation amplitude) is only marginally significant, the agreement between data and simulations is encouraging for future work in which even better quality data will provide the best insight into the overarching structure of the IGM and its understanding as shown by SPH simulations.Comment: 15 pages, 11 figures; accepted for publication in Astronomical Journa

The Stellar Populations and Evolution of Lyman Break Galaxies

Using deep near-IR and optical observations of the HDF-N from the HST NICMOS and WFPC2 and from the ground, we examine the spectral energy distributions (SEDs) of Lyman break galaxies (LBGs) at 2.0 < z < 3.5. The UV-to-optical rest-frame SEDs of the galaxies are much bluer than those of present-day spiral and elliptical galaxies, and are generally similar to those of local starburst galaxies with modest amounts of reddening. We use stellar population synthesis models to study the properties of the stars that dominate the light from LBGs. Under the assumption that the star-formation rate is continuous or decreasing with time, the best-fitting models provide a lower bound on the LBG mass estimates. LBGs with ``L*'' UV luminosities are estimated to have minimum stellar masses ~ 10^10 solar masses, or roughly 1/10th that of a present-day L* galaxy. By considering the effects of a second component of maximally-old stars, we set an upper bound on the stellar masses that is ~ 3-8 times the minimum estimate. We find only loose constraints on the individual galaxy ages, extinction, metallicities, initial mass functions, and prior star-formation histories. We find no galaxies whose SEDs are consistent with young (< 10^8 yr), dust-free objects, which suggests that LBGs are not dominated by ``first generation'' stars, and that such objects are rare at these redshifts. We also find that the typical ages for the observed star-formation events are significantly younger than the time interval covered by this redshift range (~ 1.5 Gyr). From this, and from the relative absence of candidates for quiescent, non-star-forming galaxies at these redshifts in the NICMOS data, we suggest that star formation in LBGs may be recurrent, with short duty cycles and a timescale between star-formation events of < 1 Gyr. [Abridged]Comment: LaTeX, 37 pages, 21 figures. Accepted for publication in the Astrophysical Journa