Comparison of numerical solution strategies for gravity field recovery from GOCE SGG observations implemented on a parallel platform

International audienceThe recovery of a full set of gravity field parameters from satellite gravity gradiometry (SGG) is a huge numerical and computational task. In practice, parallel computing has to be applied to estimate the more than 90 000 harmonic coefficients parameterizing the Earth?s gravity field up to a maximum spherical harmonic degree of 300. Three independent solution strategies, i.e. two iterative methods (preconditioned conjugate gradient method, semi-analytic approach) and a strict solver (Distributed Non-approximative Adjustment), which are operational on a parallel platform (?Graz Beowulf Cluster?), are assessed and compared both theoretically and on the basis of a realistic-as-possible numerical simulation, regarding the accuracy of the results, as well as the computational effort. Special concern is given to the correct treatment of the coloured noise characteristics of the gradiometer. The numerical simulations show that there are no significant discrepancies among the solutions of the three methods. The newly proposed Distributed Nonapproximative Adjustment approach, which is the only one of the three methods that solves the inverse problem in a strict sense, also turns out to be a feasible method for practical applications.Key words. Spherical harmonics ? satellite gravity gradiometry ? GOCE ? parallel computing ? Beowulf cluste

Farm debt and financial viability

New Zealand Society of Farm Management Conference proceedings 1971.This bulletin has been produced by the Department of Farm Management and Rural Valuation of Lincoln College in association with the New Zealand Society of Farm Management. It consists of papers given at the Society of Farm Management section of the Annual Conference of the New Zealand Institute of Agriculture Science held at Lincoln College in August 1971. Deepening financial problems in the Sheep Industry have focussed attention on the need for a fuller understanding of the nature of these problems, and the policy measures needed to meet them. These papers make a contribution to this understanding

A SURVEY OF THE PINEAPPLE MEALYBUG IN PUERTO RICO AND PRELIMINARY STUDIES OF ITS CONTROL

A field survey of conditions in four main pineapple-growing districts of Puerto Rico revealed a mealybug infestation of 87.1 percent among pineapple plants ranging from 9 months to about 2 years of age. The infestation in individual fields varied from 66.7 to 100 percent of the plants examined, and about as many plants were found infested with the mealybug on the inside of the fields as along the edges

The Regulatory Effect of Semaphorin 7A on Proliferation and Migration in Human Umbilical Vein Endothelial Cells

Semaphorin 7A (SEMA 7A), a factor originally identified as regulating axon growth, has recently been implicated as a pro-angiogenic factor. The molecular mechanisms for this ability to stimulate angiogenesis have not been identified. This study examines if SEMA 7A can have a direct effect on vascular endothelial cells or whether it indirectly induces angiogenesis through stimulation and recruitment of macrophages as has been suggested. Using a human umbilical vein endothelial cells (HUVECs), the ability of SEMA 7A to affect proliferation and migration was examined. HUVECs were exposed to SEMA 7A directly or to conditioned media collected from macrophages exposed to SEMA 7A and a cell proliferation assay was performed. Additionally, the ability of the cells to migrate was also measured using a transwell and a scratch assay. Direct exposure of HUVECs to SEMA 7A resulted in a significant decrease in cell proliferation. Preliminary results also suggest that direct exposure also results in a slight inhibitory effect on the migration of HUVECs. SEMA 7A treatment of macrophages did not result in the production of factors that stimulate HUVECs to proliferate. Additionally, our results suggest that macrophages exhibited a slight stimulation of migration in response to SEMA 7A

Rmi1 stimulates decatenation of double Holliday junctions during dissolution by Sgs1-Top3

double Holliday junction (dHJ) is a central intermediate of homologous recombination that can be processed to yield crossover or non-crossover recombination products. To preserve genomic integrity, cells possess mechanisms to avoid crossing over. We show that Saccharomyces cerevisiae Sgs1 and Top3 proteins are sufficient to migrate and disentangle a dHJ to produce exclusively non-crossover recombination products, in a reaction termed "dissolution." We show that Rmi1 stimulates dHJ dissolution at low Sgs1-Top3 protein concentrations, although it has no effect on the initial rate of Holliday junction (HJ) migration. Rmi1 serves to stimulate DNA decatenation, removing the last linkages between the repaired and template DNA molecules. Dissolution of a dHJ is a highly efficient and concerted alternative to nucleolytic resolution that prevents crossing over of chromosomes during recombinational DNA repair in mitotic cells and thereby contributes to genomic integrity

Nonlinear analysis of orthotropic composite slabs in fire

In this study an orthotropic slab finite element is developed to model orthotropic slabs in fire, using a layered 9-noded isoparametric slab element and a 3-noded beam element. The element is assembled from a solid slab element which represents the continuous upper portion of the profile, and a special beam element which represents the ribbed lower portion. An equivalent width for the cross-section of this beam element is determined according to the dimensions of the solid slab element and the cross-section of the ribbed profile, and the beam shares the nodes of the solid slab element. The temperature within each layer of the slab element can vary between adjacent Gauss integration points so as to reflect temperature variations in the horizontal plane. Several fire tests on composite slabs have been modelled to validate the approach. Cases of orthotropic slabs with wide range of parameters defining the ribbed profile have been studied, which show that the orthotropic slab model is robust and effective in reflecting the influence of the shape of ribs on the thermal and structural performance of the slabs in fire. The study shows the influence of decking shape on the thermal and structural behaviours of orthotropic slabs. A simple evaluation method for profile selection is proposed

The mechanics of inelastic buckling using a Shanley-like model

This paper presents a study of the mechanics of inelastic buckling using a Shanley-like simplified column model. The model is an extension of the original Shanley model with multiple springs and two dampers. The inclusion of damping enables the dynamic response of the model under constant loading to be captured. The model has been evaluated against the tangent-modulus and reduced-modulus critical buckling loads, and has been found effective in representing the progressive change in the regions of loading and unloading during inelastic buckling. It is also able to simulate the extreme situations of inelastic buckling by varying the ratio of the two damping coefficients. It is seen that high rotational damping, relative to vertical damping, causes the buckling to move towards the reducedmodulus buckling load at much lower deflections than when the relationship is reversed

The magnetofection method: Using magnetic force to enhance gene delivery

In order to enhance and target gene delivery we have previously established a novel method, termed magnetofection, which uses magnetic force acting on gene vectors that are associated with magnetic particles. Here we review the benefits, the mechanism and the potential of the method with regard to overcoming physical limitations to gene delivery. Magnetic particle chemistry and physics are discussed, followed by a detailed presentation of vector formulation and optimization work. While magnetofection does not necessarily improve the overall performance of any given standard gene transfer method in vitro, its major potential lies in the extraordinarily rapid and efficient transfection at low vector doses and the possibility of remotely controlled vector targeting in vivo

What Comes Next? Evaluating Uncertainty in Neural Text Generators Against Human Production Variability

In Natural Language Generation (NLG) tasks, for any input, multiple communicative goals are plausible, and any goal can be put into words, or produced, in multiple ways. We characterise the extent to which human production varies lexically, syntactically, and semantically across four NLG tasks, connecting human production variability to aleatoric or data uncertainty. We then inspect the space of output strings shaped by a generation system’s predicted probability distribution and decoding algorithm to probe its uncertainty. For each test input, we measure the generator’s calibration to human production variability. Following this instance-level approach, we analyse NLG models and decoding strategies, demonstrating that probing a generator with multiple samples and, when possible, multiple references, provides the level of detail necessary to gain understanding of a model’s representation of uncertainty