The sediment trapping efficiency of the macro-tidal Daly Estuary, tropical Australia

Field studies were carried out on the water and sediment dynamics in the tropical, macro-tidal, Daly Estuary. The estuary is shallow, very-turbid, about 100 km long, and the entrance is funnel-shape. In the wet, high flow season, normal tidal ranges can be suppressed in the estuary, depending on inflow rates, and freshwater becomes dominant up to the mouth. At that time a fraction of the fine sediment load is exported offshore as a bottom-tagging nepheloid layer after the sediment falls out of suspension of the thin, near-surface, river plume. The remaining fraction and the riverine coarse sediment form a large sediment bar 10 km long, up to 6 m in height and extending across the whole width of the channel near the mouth. This bar, as well as shoals in the estuary, partially pond the mid- to upper-estuary. This bar builds up from the deposition of riverine sediment during a wet season with high runoff and can raise mean water level by up to 2 m in the upper estuary in the low flow season. This ponding effect takes about three successive dry years to disappear by the sediment forming the bar being redistributed all over the estuary by tidal pumping of fine and coarse sediment in the dry season, which is the low flow season. The swift reversal of the tidal currents from ebb to flood results in macro-turbulence that lasts about 20 min. Bed load transport is preferentially landward and occurs only for water currents greater than 0.6 m s(-1). This high value of the threshold velocity suggests that the sand may be cemented by the mud. The Daly Estuary thus is a leaky sediment trap with an efficiency varying both seasonally and inter-annually. (c) 2006 Elsevier Ltd. All rights reserved.

Endgame table testing of studies - II

The van der Heijden Studies Database (Version III) has been reviewed to identify 'Win Studies' with sub-7-man positions in the main line which are not wins for White. Some studies were faulted, A number for the first time: 21 of the more interesting escapes by Black are highlighted, themed and discussed.

Estimating technical efficiency of Australian dairy farms using alternative frontier methodologies

Technical efficiency is estimated and examined for a cross-section of Australian dairy farms using various frontier methodologies; Bayesian and Classical stochastic frontiers, and Data Envelopment Analysis. The results indicate technical inefficiency is present in the sample data. Also identified are statistical differences between the point estimates of technical efficiency generated by the various methodologies. However, the rank of farm level technical efficiency is statistically invariant to the estimation technique employed. Finally, when confidence/credible intervals of technical efficiency are compared significant overlap is found for many of the farms' intervals for all frontier methods employed. The results indicate that the choice of estimation methodology may matter, but the explanatory power of all frontier methods is significantly weaker when interval estimate of technical efficiency is examined.

Examining the technical efficiency of rice producers in Bangladesh

Despite record national output in the early years of this decade there is widespread concern that rice yields in Bangladesh are below those attainable, and that given future population growth this may constrain achievement of food security and poverty reduction objectives. A frequent response to this problem is that farmers could close the gap between actual farm yields and potential yields identified in field trials if farmers who are technically inefficient could improve their current farming practices. This paper estimates and explains technical efficiency for a sample of rice farmers in Bangladesh employing Bayesian methods. The results provide insights into the distribution of technical efficiency and identify important influences on rice growing.

Profitability and technical efficiency of aquaculture systems in Pampanga, Philippines

We evaluate the profitability and technical efficiency of aquaculture in the Philippines. Farm-level data are used to compare two production systems corresponding to the intensive monoculture of tilapia in freshwater ponds and the extensive polyculture of shrimps and fish in brackish water ponds. Both activities are very lucrative, with brackish water aquaculture achieving the higher level of profit per farm. Stochastic frontier production functions reveal that technical efficiency is low in brackish water aquaculture, with a mean of 53%, explained primarily by the operator's experience and by the frequency of his visits to the farm. In freshwater aquaculture, the farms achieve a mean efficiency level of 83%. The results suggest that the provision of extension services to brackish water fish farms might be a cost-effective way of increasing production and productivity in that sector. By contrast, technological change will have to be the driving force of future productivity growth in freshwater aquaculture.

Application of a double bootstrap to investigation of determinants of technical efficiency of farms in Central Europe

The paper provides one of the first applications of the double bootstrap procedure (Simar and Wilson 2007) in a two-stage estimation of the effect of environmental variables on non-parametric estimates of technical efficiency. This procedure enables consistent inference within models explaining efficiency scores, while simultaneously producing standard errors and confidence intervals for these efficiency scores. The application is to 88 livestock and 256 crop farms in the Czech Republic, split into individual and corporate.

Application of a double bootstrap to investigation of determinants of technical efficiency of farms in Central Europe

The paper provides one of the first applications of the double bootstrap procedure (Simar and Wilson 2007) in a two-stage estimation of the effect of environmental variables on non-parametric estimates of technical efficiency. This procedure enables consistent inference within models explaining efficiency scores, while simultaneously producing standard errors and confidence intervals for these efficiency scores. The application is to 88 livestock and 256 crop farms in the Czech Republic, split into individual and corporate.

Effect of species and genotype on the efficiency of enrichment of poultry meat with n-3 polyunsaturated fatty acids

The effect of poultry species (broiler or turkey) and genotype (Wrolstad or BUT T8 turkeys and Ross 308 or Cobb 500 broilers) on the efficiency with which dietary longchain n-3 PUFA were incorporated into poultry meat was determined. Broilers and turkeys of both genotypes were fed one of six diets varying in FA composition (two replicates per genotype x diet interaction). Diets contained 50 g/kg added oil, which was either blended vegetable oil (control), or partially replaced with linseed oil (20 or 40 g/kg diet), fish oil (20 or 40 g/kg diet), or a mixture of the two (20 g linseed oil and 20 g fish oil/kg diet). Feeds and samples of skinless breast and thigh meat were analyzed for FA. Wrolstad dark meat was slightly more responsive than BUT T8 (P = 0.046) to increased dietary 18:3 concentrations (slopes of 0.570 and 0.465, respectively). The Ross 308 was also slightly more responsive than the Cobb 500 (P= 0.002) in this parameter (slopes of 0.557 and 0.449). There were no other significant differences between the genotypes. There was some evidence (based on the estimates of the slopes and their associated standard errors) that white turkey meat was more responsive than white chicken meat to 20:5 (slopes of 0.504 and 0.289 for turkeys and broilers, respectively). There was no relationship between dietary 18:3 n-3 content and meat 20:5 and 22:6 contents. If birds do convert 18:3 to higher FA, these acids are not then deposited in the edible tissues.

Evaluating the efficiency of sampling methods in assessing soil macrofauna communities in arable systems

The soil fauna is often a neglected group in many large-scale studies of farmland biodiversity due to difficulties in extracting organisms efficiently from the soil. This study assesses the relative efficiency of the simple and cheap sampling method of handsorting against Berlese-Tullgren funnel and Winkler apparatus extraction. Soil cores were taken from grassy arable field margins and wheat fields in Cambridgeshire, UK, and the efficiencies of the three methods in assessing the abundances and species densities of soil macroinver-tebrates were compared. Handsorting in most cases was as efficient at extracting the majority of the soil macrofauna as the Berlese-Tullgren funnel and Winkler bag methods, although it underestimated the species densities of the woodlice and adult beetles. There were no obvious biases among the three methods for the particular vegetation types sampled and no significant differences in the size distributions of the earthworms and beetles. Proportionally fewer damaged earthworms were recorded in larger (25 x 25 cm) soil cores when compared with smaller ones (15 x 15 cm). Handsorting has many benefits, including targeted extraction, minimum disturbance to the habitat and shorter sampling periods and may be the most appropriate method for studies of farmland biodiversity when a high number of soil cores need to be sampled. (C) 2008 Elsevier Masson SAS. All rights reserved.

Bayesian design and conduct of phase II single-arm clinical trials with binary outcomes: a tutorial

The aim of phase II single-arm clinical trials of a new drug is to determine whether it has sufficient promising activity to warrant its further development. For the last several years Bayesian statistical methods have been proposed and used. Bayesian approaches are ideal for earlier phase trials as they take into account information that accrues during a trial. Predictive probabilities are then updated and so become more accurate as the trial progresses. Suitable priors can act as pseudo samples, which make small sample clinical trials more informative. Thus patients have better chances to receive better treatments. The goal of this paper is to provide a tutorial for statisticians who use Bayesian methods for the first time or investigators who have some statistical background. In addition, real data from three clinical trials are presented as examples to illustrate how to conduct a Bayesian approach for phase II single-arm clinical trials with binary outcomes.

Immobilisation of eta(3)-allyidicarbonyl complexes of Mo-II with bidentate nitrogen ligands within aluminium-pillared clays

Molybdenum(II) complexes [MOX(CO)(2)(eta(3)-allyl)(CH3CN)(2)] (X = Cl or Br) were encapsulated in an aluminium-pillared natural clay or a porous clay heterostructure and allowed to react with bidentate diimine ligands. All the materials obtained were characterised by several solid-state techniques. Powder XRD, and Al-27 and Si-29 MAS NMR were used to investigate the integrity of the pillared clay during the modification treatments. C-13 CP MAS NMR, FTIR, elemental analyses and low-temperature nitrogen adsorption showed that the immobilisation of the precursor complexes was successful as well as the in situ ligand-substitution reaction. The new complex [MoBr(CO)(2)(eta(3)-allyl)(2-aminodipyridyl)] was characterised by single-crystal X-ray diffraction and spectroscopic techniques, and NMR studies were used to investigate its fluxional behaviour in solution. The prepared materials are active for the oxidation of cis-cyclooctene using tert-butyl hydroperoxide as oxidant, though the activity of the isolated complexes is higher. ((c) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008).

Structural and equilibrium studies on mixed ligand complexes of Co(II), Ni(II), Cu(II) and Zn(II) with N-(2-benzimidazolyl)methyliminodiacetic acid and typical N,N donor ligands

Mixed ligand complexes: [Co(L)(bipy)] (.) 3H(2)O (1), [Ni(L)(phen)] (.) H2O (2), [Cu(L)(phen)] (.) 3H(2)O (3) and [Zn(L)(bipy)] (.) 3H(2)O (4), where L2- = two -COOH deprotonated dianion of N-(2-benzimidazolyl)methyliminodiacetic acid (H(2)bzimida, hereafter, H,L), bipy = 2,2' bipyridine and phen = 1,10-phenanthroline have been isolated and characterized by elemental analysis, spectral and magnetic measurements and thermal studies. Single crystal X-ray diffraction studies show octahedral geometry for 1, 2 and 4 and square pyramidal geometry for 3. Equilibrium studies in aqueous solution (ionic strength I = 10(-1) mol dm(-3) (NaNO3), at 25 +/- 1 degrees C) using different molar proportions of M(II):H2L:B, where M = Co, Ni, Cu and Zn and B = phen, bipy and en (ethylene diamine), however, provides evidence of formation of mononuclear and binuclear binary and mixed ligand complexes: M(L), M(H-1L)(-), M(B)(2+), M(L)(B), M(H-1L)(B)(-), M-2(H-1L)(OH), (B)M(H-1L)M(B)(+), where H-1L3- represents two -COOH and the benzimidazole NI-H deprotonated quadridentate (O-, N, O-, N), or, quinquedentate (O-, N, O-, N, N-) function of the coordinated ligand H,L. Binuclear mixed ligand complex formation equilibria: M(L)(B) + M(B)(2+) = (B)M(H-1L)M(B)(+) + H+ is favoured with higher pi-acidity of the B ligands. For Co(II), Ni(II) and Cu(II), these equilibria are accompanied by blue shift of the electronic absorption maxima of M(II) ions, as a negatively charged bridging benzimidazolate moiety provides stronger ligand field than a neutral one. Solution stability of the mixed ligand complexes are in the expected order: Co(II) < Ni(II) < Cu(II) > Zn(II). The Delta logK(M) values are less negetive than their statistical values, indicating favoured formation of the mixed ligand complexes over the binary ones. (c) 2005 Elsevier B.V. All rights reserved.