bluuebunny/crossref_metadata_2025 huggingface dataset:
Clinical impact of variability in HbA1c as assessed by simultaneously measuring fructosamine and use of error grid analysis
Authors: Macdonald David R , Hanson Alison M , Holland Martin R , Singh Baldev M
Published: June 2008

Background

Haemoglobin A1c (HbA1c) is the only measure of glycaemic control used for many patients with diabetes, but it has limitations and might sometimes be misleading. HbA1c concentrations are influenced by conditions that alter red-cell life and there is evidence that biochemical variation in intracellular glycation rates also influence HbA1c concentrations. This paper is the first to propose a method of using simultaneously measured HbA1c and fructosamine, and error grid analysis, in the clinical setting, to gain a better understanding of glycaemic control.

Methods

Cross-sectional analytical study using HbA1c and fructosamine measures on the same blood sample from 1744 patients having blood taken for hospital diabetes clinic appointments. No other selection or exclusion criteria were applied.

Results

The fructosamine results were converted to a HbA1c equivalent which was then compared with the HbA1c. In an Altman-Bland plot, the paired result differences ranged between −6.9% and +5.5% HbA1c with 1139 (65%), 438 (25%), 130 (8%) and 37 (2%) being ≤1%, 1–2%, 2–3% or >3% of HbA1c difference, respectively. In clinical error grid analysis, 864 (50%) results had tight concordance for clinical interpretation, 761 (43%) had one block disunity of probably little clinical significance, but 105 (6%) were two blocks and 14 (1%) were three blocks discordant.

Conclusion

HbA1c may not accurately reflect glucose control. Our method, utilizing co-assessment with serum fructosamine, evaluates the possible clinical impact of this. We suggest the analysis used in this paper should be used routinely in diabetes practice.
Conserved RNA secondary structures promote alternative splicing
Authors: Shepard Peter J. , Hertel Klemens J.
Published: June 2008

Pre-mRNA splicing is carried out by the spliceosome, which identifies exons and removes intervening introns. Alternative splicing in higher eukaryotes results in the generation of multiple protein isoforms from gene transcripts. The extensive alternative splicing observed implies a flexibility of the spliceosome to identify exons within a given pre-mRNA. To reach this flexibility, splice-site selection in higher eukaryotes has evolved to depend on multiple parameters such as splice-site strength, splicing regulators, the exon/intron architecture, and the process of pre-mRNA synthesis itself. RNA secondary structures have also been proposed to influence alternative splicing as stable RNA secondary structures that mask splice sites are expected to interfere with splice-site recognition. Using structural and functional conservation, we identified RNA structure elements within the human genome that associate with alternative splice-site selection. Their frequent involvement with alternative splicing demonstrates that RNA structure formation is an important mechanism regulating gene expression and disease.
Serum osteoprotegerin concentrations are decreased in women with the polycystic ovary syndrome
Authors: Escobar-Morreale Héctor F , Botella-Carretero José I , Martínez-García Ma Ángeles , Luque-Ramírez Manuel , Álvarez-Blasco Francisco , Millán José L San
Published: June 2008

Objective

Osteoprotegerin (OPG), an inhibitor of osteoclastic bone resorption, has a variety of functions including anti-inflammatory effects and a possible cardiovascular protective role. Both low-grade chronic inflammation and cardiovascular risk are increased in women with the polycystic ovary syndrome (PCOS). We aimed to study serum OPG concentrations in PCOS patients.

Design

Case–control study including 40 PCOS patients matched with 40 non-hyperandrogenic women for age and body mass index.

Methods

Basal serum sampling and standard oral glucose tolerance test, and measurement of serum OPG concentrations by commercial ELISA.

Results

Serum OPG concentrations were lower in women with PCOS compared with those of controls (304±120 vs 363±105 pg/ml respectively; F=7.641, P=0.007) independently of obesity. No differences were observed in serum receptor activator of nuclear factor-κB ligand (RANKL) levels and in the RANKL/OPG molar ratio. A multivariate linear regression model (R2=0.208, F=6.579, P=0.001) showed that PCOS (β=−0.281, P=0.008), obesity (β=−0.245, P=0.022) and age (β=0.296, P=0.006) were predictive of serum OPG concentrations.

Conclusions

Serum OPG concentrations are reduced in PCOS patients independently of obesity. Considering the anti-inflammatory effects of OPG, its reduced serum concentrations might contribute to the proinflammatory state and cardiovascular risk of PCOS patients.
Interplay of DNA Repair Pathways Controls Methylation Damage Toxicity in Saccharomyces cerevisiae
Authors: Cejka Petr , Jiricny Josef
Published: June 2008

Methylating agents of SN1 type are widely used in cancer chemotherapy, but their mode of action is poorly understood. In particular, it is unclear how the primary cytotoxic lesion, O6-methylguanine (MeG), causes cell death. One hypothesis stipulates that binding of mismatch repair (MMR) proteins to MeG/T mispairs arising during DNA replication triggers cell-cycle arrest and cell death. An alternative hypothesis posits that MeG cytotoxicity is linked to futile processing of MeG-containing base pairs by the MMR system. In this study, we provide compelling genetic evidence in support of the latter hypothesis. Treatment of 4644 deletion mutants of Saccharomyces cerevisiae with the prototypic SN1-type methylating agent N-methyl-N′-nitro-N-nitrosoguanidine (MNNG) identified MMR as the only pathway that sensitizes cells to MNNG. In contrast, homologous recombination (HR), postreplicative repair, DNA helicases, and chromatin maintenance factors protect yeast cells against the cytotoxicity of this chemical. Notably, DNA damage signaling proteins played a protective rather than sensitizing role in the MNNG response. Taken together, this evidence demonstrates that MeG-containing lesions in yeast must be processed to be cytotoxic.
Identification of NR5A1 (SF-1/AD4BP) gene expression modulators by large-scale gain and loss of function studies
Authors: Sakai Noriko , Terami Hiromi , Suzuki Shinobu , Haga Megumi , Nomoto Ken , Tsuchida Nobuko , Morohashi Ken-ichirou , Saito Naoaki , Asada Maki , Hashimoto Megumi , Harada Daisuke , Asahara Hiroshi , Ishikawa Tetsuya , Shimada Fumiki , Sakurada Kazuhiro
Published: June 2008

Nuclear receptor subfamily 5, group A, member 1 (NR5A1 previously known as SF-1/AD4BP) is a transcription factor involved in the development of adrenal/gonadal tissues and steroidogenic linage cell differentiation in adult somatic stem cells. To understand the cellular signaling network that regulates NR5A1 gene expression, loss of function screening with an siRNA kinome library, and gain of function screening with an addressable full-length cDNA library representing one quarter of the human genome was carried out. The NR5A1 gene expression was activated in mesenchymal stem cells by siRNA directed against protein kinase C (PKC)-δ, erb-B3, RhoGAP (ARHGAP26), and hexokinase 2, none of which were previously known to be involved in the NR5A1 gene expression. Among these, we identified crosstalk between erb-B3 and PKC-δ signaling cascades. In addition, the gain of function studies indicated that sex-determining region Y (SRY)-box 15 (SOX15), TEA domain family member 4, KIAA1257 (a gene of unknown function), ADAM metallopeptidase with thrombospondin type 1 motif 6, Josephin domain containing 1, centromere protein, TATA box-binding protein-associated factor 5-like RNA polymerase, and inducible T-cell co-stimulator activate NR5A1 gene expression. These results provide new insights into the molecular mechanisms of NR5A1 gene expression.
The effect of the yield and plastic potential deviatoric surfaces on the failure height of an embankment
Authors: Grammatikopoulou A. , Zdravkovic L. , Potts D. M.
Published: June 2008

The paper investigates the effect of the deviatoric shape of the yield and plastic potential surfaces on the failure height of an embankment founded on a soft clay deposit. Different combinations of the shapes of the surfaces in the deviatoric plane are explored in a critical state model that predicts isotropic strength, and which is used in order to model the clay foundation. The shapes considered start from the widely used circular shape and move on to the Mohr–Coulomb hexagon and advanced shapes, such as the Lade shape. For all combinations the same undrained strength profile in triaxial compression is adopted for the clay foundation. Finite element analyses investigate the failure height of the embankment assuming plane-strain conditions. Moreover, two ways of modelling the fill material are adopted in the analyses, and the effect of each of these on the failure height of the embankment is explored.
An analysis of the triaxial apparatus using a mixed boundary three-dimensional discrete element model
Authors: Cui L. , O'Sullivan C. , O'Neill S.
Published: June 2008

The triaxial test is probably the most important fundamental laboratory test for geotechnical engineers. The objective of the study presented here was to gain insight into the micro-scale interactions experienced by particles during a triaxial test using the distinct element method (DEM). To achieve this objective, a novel DEM modelling environment to simulate triaxial tests on ideal granular materials was implemented, as described here. In this test environment, both the stress conditions and boundary conditions in the physical tests can be accurately reproduced. This approach was quantitatively validated by simulating a number of physical triaxial tests on specimens of steel spheres. A comparison between the circumferential periodic boundaries used here and the circumferential rigid boundaries used by other researchers emphasises the significance of maintaining a continuous particle–particle contact network orthogonal to the major principal stress direction. Results of an analysis of the micro-scale response in a triaxial simulation are analysed in detail, including the stresses, the distribution of contact forces, the evolution of fabric, the distribution of local strains, and the particle rotations. Significant non-uniformities in the stresses, strains and contact fabric were observed.
Thermo-hydro-mechanical modelling of an in situ heating experiment
Authors: Jia Y. , Wileveau Y. , Su K. , Duveau G. , Shao J. F.
Published: June 2008

In the context of a feasibility study for geological disposal of nuclear waste, an in situ heating experiment was performed in order to study the thermo-hydro-mechanical responses of a geological barrier to variation of temperature. The experiment was carried out at the Mont Terri underground research laboratory in Switzerland. This paper presents the numerical modelling of the experiment. An elasto-plastic damage model has been used to describe the mechanical behaviour of the geological formation (a mudstone). The constitutive model is extended to the description of the thermo-poro-mechanical behaviour of saturated porous media. A finite element method with fully coupled algorithm has been employed for the numerical solution of boundary value problems. Variations of temperature, pore pressure and deformation during heating phases have been evaluated and compared with in situ measurements. The numerical modelling allows the interpretation of coupled phenomena observed in the experiment.
Failure envelopes for offshore shallow foundations under general loading
Authors: Gourvenec S.
Published: June 2008

The interaction of vertical, horizontal and moment (VHM) loads acting on a shallow foundation is complex, and it is becoming increasingly popular to represent ultimate limit states under general VHM loading as failure envelopes in three-dimensional load space. General loading is of particular interest offshore, where harsh environmental conditions lead to large horizontal and moment foundation loads. Shallow foundations with peripheral skirts that penetrate into the seabed are used to resist large lateral and overturning forces. During undrained loading, tensile resistance can be mobilised on the underside of the base plate by suctions developed within the skirt compartment. This paper presents failure envelopes and kinematic mechanisms for undrained ultimate limit states of circular skirted foundations in uniform and heterogeneous deposits under general VHM loading based on finite element results. An approximating method is proposed that permits accurate prediction of ultimate limit states under a full range of general loading.
Simple prediction of the undrained displacement of a circular surface foundation on non-linear soil
Authors: Osman A. S. , White D. J. , Britto A. M. , Bolton M. D.
Published: June 2008

Textbooks and university courses teach elasticity and plasticity as separate methods for analysing the stiffness and strength of a shallow foundation. The behaviour of real soil is neither linear elastic nor perfectly plastic. In this paper, two simple techniques for incorporating non-linearity in routine design have been validated using finite element (FE) analysis. These two techniques—Atkinson's method and the mobilisable strength design (MSD) approach—assume that the responses of an individual soil element and the boundary value problem being considered are self-similar. Using this assumption, the soil element response can be scaled to predict the response of the boundary value problem. Atkinson's method is based on elasticity whereas MSD uses plasticity. Non-linearity has been captured in the FE analysis using a power law soil model. This approach uses minimal parameters, but is shown to capture accurately the undrained stress–strain response of typical clays under monotonic loading. Comparison with elastic and plastic solutions showed that the FE analysis was accurate to within < 5% at the elastic and plastic extremes of the loading range. The responses of the soil and the boundary value problem are shown to be sufficiently self-similar up to two-thirds of the failure load for the foundation response to be predicted simply by a linear scaling of the soil response. Previously reported scaling factors for vertical loading are confirmed, and new factors for horizontal and moment loading are derived. These results show that, for this particular boundary value problem, soil non-linearity can be captured with sufficient accuracy for routine design, without recourse to sophisticated numerical analysis. These self-similarity methods are simple enough to be taught to undergraduates, and could be incorporated in textbooks alongside the core sections on elasticity and plasticity, providing guidance on the application of these techniques to real non-linear soil.
A new discrete fracture modelling approach for rock masses
Authors: Pine R. J. , Owen D. R. J. , Coggan J. S. , Rance J. M.
Published: June 2008

A method for modelling discrete fracture in rock masses under tensile and compressive stress fields is presented, based on a Mohr–Coulomb failure surface in compression and three independent anisotropic rotating crack models in tension. Extension fracturing is modelled by coupling the softening of the anisotropic rotating crack failure criterion to the compressive plastic strain evolution. An explicitly time-integrated coupled discrete element/finite element approach is employed with an explicit Lagrangian contact algorithm to enforce non-penetration of the surfaces created when the tensile strength is depleted. The geomechanical model is applied to naturally fractured rock masses, which are characterised by field mapping and borehole data integrated in a stochastic 3D discrete fracture network model. This approach maximises the utility of the field data and provides a direct approach to the determination of rock mass strength and deformability. It also provides a realistic insight into complex failure mechanisms. Typical applications are mine pillars, roofs, hangingwalls and block caving. The model has also been used on rock slopes.
Determination of the anisotropic shear stiffness of an unsaturated decomposed soil
Authors: Ng C. W. W. , Yung S. Y.
Published: June 2008

The shear modulus at very small strains (0·001% or less), G0, is one of the most important parameters for predicting ground movements and dynamic responses of many engineering earth structures. With advances in the use of bender elements for soil testing, anisotropic shear moduli G0(ij)can now be evaluated by measuring the velocities of shear waves propagating in a soil specimen in different planes and polarisations. This leads to the determination of the stiffness anisotropy at very small strains. While almost all previous studies of anisotropic soil stiffness have been conducted with saturated soils, experimental results from unsaturated soils have rarely been reported in the literature. A new computer-controlled triaxial apparatus equipped with three pairs of bender elements was developed to measure shear wave velocities and hence to investigate the degree of stiffness anisotropy of recompacted completely decomposed tuff (CDT) under both saturated and unsaturated conditions. The axis-translation technique was applied to control matric suction. New state-dependent equations describing aniso-tropic moduli of unsaturated soil were derived and verified by experimental results. Based on the derived equations and measurements, it was possible to identify that there was an inherent shear stiffness anisotropy of about 1·03–1·04, due to sample preparation by moist tamping, for isotropic net mean stress varying from 110 to 400 kPa. When suction was increased from 0 kPa to the air-entry value of 50 kPa, suction-induced anisotropy in terms of the shear stiffness ratio, G0(hh)/G0(hv), ranged from about 1·06 to 1·09 for isotropic net mean stress varying from 110 to 500 kPa. No further significant increase in suction-induced stiffness anisotropy was observed at suctions higher than the air-entry value.
Physical characteristics of subglacial tills
Authors: Clarke B. G. , Hughes D. B. , Hashemi S.
Published: June 2008

A regional database of the physical properties of glacial tills has been interrogated to produce characteristic design values and baseline construction values. Glacioterrestrial glacial till, one of the most distributed deposits in the world, is typically a heterogeneous mixture of clays, silts, sands, gravels and cobbles, which can contain remnants of earlier till including glaciolacustrine and fluvioglacial deposits that have been gravitationally compacted and sheared. This results in a complex deposit, which is spatially variable both in composition and fabric to the extent that the selection of design profiles is challenging. A study of the intrinsic properties of the tills in the North East of England together with a statistical analysis has led to the identification of two distinctly different, heavily overconsolidated tills that have profiles of strength, water content and density that lead to characteristic values based on the regional database and baseline values based on the local database that provide a priori knowledge for future investigations. This a priori knowledge has been used to determine the characteristic and baseline values for a new dataset from the region after demonstrating that the data fit with the regional database.
Effect of embedment on the undrained capacity of shallow foundations under general loading
Authors: Gourvenec S.
Published: June 2008

Results of a finite element study addressing the effect of embedment on the undrained bearing capacity of shallow strip foundations under uniaxial and combined loading are reported. Uniaxial vertical (V), moment (M) and horizontal (H) capacity and combined VH, VM and general VMH capacity are assessed. Ultimate limit states and the kinematic mechanisms accompanying failure are presented. Ultimate limit states under combined loading are presented as failure envelopes expressed in terms of loads non-dimensionalised by the foundation geometry and soil undrained shear strength and loads normalised by the ultimate uniaxial limit load, in order to describe their size and shape respectively. The results presented in this paper show that the size and shape of failure envelopes defining the undrained capacity of shallow foundations under general loading are dependent on embedment ratio.
Pile and penetrometer end bearing resistance in two-layered soil profiles
Authors: Xu X. , Lehane B. M.
Published: June 2008

The paper examines the influence of soil strength and stiffness on the end resistance mobilised by a cone or displacement pile in a two-layered soil profile (i.e. strong soil overlying or underlying weak soil). The investigation involved a series of numerical analyses that idealise pile/cone penetration assuming the spherical cavity expansion analogue. It is shown how the end resistance mobilised by a penetrometer in a dense sand (i.e. strong soil) varies with the number of penetrometer diameters (D) from a weak soil (assumed here to be either a loose sand or soft clay), and depends on the ratio of the steady-state penetration resistances of the strong and weak layers. The penetrometer resistance in the weak soil is not affected by an adjacent strong layer at penetrations greater than 2D. A design procedure based on a numerical parametric study is proposed, and this is subsequently shown to compare well with centrifuge test data and with previous numerical research.
Quantifying and modelling fabric anisotropy of granular soils
Authors: Yang Z. X. , Li X. S. , Yang J.
Published: June 2008

This paper describes an integrated study of the effects of fabric anisotropy on granular soil response, in which the microscopic measurements are properly linked with the macroscopic modelling. Using an image-analysis-based technique and an appropriate mathematical approach, the inherent fabrics of sand specimens prepared in the laboratory using different sample preparation methods were measured, quantified and compared at a microscale level. It was found that the specimen prepared by the dry deposition method had a more anisotropic microstructure than the specimen prepared using the moist tamping method, which is considered directly associated with the experimental observation that different sample preparation methods produce samples with distinctive responses under otherwise identical conditions. An existing platform model was then extended so that the combined effects of initial fabric and shear mode dependence were accounted for in a simple yet rational manner. To calibrate and verify the model, a series of laboratory tests was conducted for Toyoura sand under various combinations of loading and sample preparation conditions. It is shown that the model is capable of simulating in a unified manner the experimental results reflecting the combined effects of sample preparation methods, loading paths, soil densities and confining pressures.
The influence of previous stress history and stress path direction on the surface settlement trough induced by tunnelling
Authors: Grammatikopoulou A. , Zdravkovic L. , Potts D. M.
Published: June 2008

The pre-failure behaviour of overconsolidated soils is well known to be non-linear and inelastic. Over the last two decades experimental work has shown that pre-failure behaviour is also dependent on the previous stress history of the soil. However, some research has also suggested that, if enough time is allowed for creep to take place, then there is no effect of recent stress history; moreover, what affects soil stiffness is the direction of the stress path relative to the gross yield surface. This paper investigates the effect of two scenarios on the surface settlement trough associated with tunnelling. The first assumes that the previous stress history of the soil has an effect on soil stiffness, whereas the second assumes that creep/ageing periods have erased any memory of the previous stress history, and it is only the stress path direction that influences soil stiffness. A three-surface kinematic hardening model, which can simulate both scenarios, is employed in finite element analyses of tunnel construction. The predictions of the kinematic hardening model for the simulation of each scenario are compared with predictions using a non-linear elastic model and with field measurements.
Forecasting the effects of accelerated sea‐level rise on tidal marsh ecosystem services
Authors: Craft Christopher , Clough Jonathan , Ehman Jeff , Joye Samantha , Park Richard , Pennings Steve , Guo Hongyu , Machmuller Megan
Published: June 2008

We used field and laboratory measurements, geographic information systems, and simulation modeling to investigate the potential effects of accelerated sea‐level rise on tidal marsh area and delivery of ecosystem services along the Georgia coast. Model simulations using the Intergovernmental Panel on Climate Change (IPCC) mean and maximum estimates of sea‐level rise for the year 2100 suggest that salt marshes will decline in area by 20% and 45%, respectively. The area of tidal freshwater marshes will increase by 2% under the IPCC mean scenario, but will decline by 39% under the maximum scenario. Delivery of ecosystem services associated with productivity (macrophyte biomass) and waste treatment (nitrogen accumulation in soil, potential denitrification) will also decline. Our findings suggest that tidal marshes at the lower and upper salinity ranges, and their attendant delivery of ecosystem services, will be most affected by accelerated sealevel rise, unless geomorphic conditions (ie gradual increase in elevation) enable tidal freshwater marshes to migrate inland, or vertical accretion of salt marshes to increase, to compensate for accelerated sea‐level rise.
Population viability management: ecological standards to guide adaptive management for rare species
Authors: Bakker Victoria J , Doak Daniel F
Published: June 2008

Many approaches to rare species management formulated by academics lack practicality and meaning for managers. Here, we propose an approach, which we refer to as population viability management (PVM), that is based on linking monitoring and management models with population models. By closely coordinating biological analyses with the range of decisions and actions considered by managers, the PVM approach ensures that population models reflect realistic management options and risk tolerances, and that adaptive conservation systems remain focused on population viability rather than statistical targets indirectly tied to population persistence. We summarize our use of PVM to formulate draft recovery criteria for the endangered island fox and to generate specific guidance for conserving this species. We argue that PVM can be widely adapted to provide more biologically justified and focused management and monitoring recommendations than those typically emerging from conventional population viability analyses. Overall, PVM represents an effective and understandable tool that enables managers to optimize monitoring effort and better control risk for species of concern.
The Albian (Vraconnian)-Cenomanian boundary at the western Tethyan margins (Central Tunisia and southeastern France)
Authors: Robaszynski Francis , Amédro Francis , González-Donoso Jose Maria , Linares Dolores
Published: June 2008

Through the description and interpretation of the position of macro- and microfossils in several sections of the Albian-Cenomanian boundary in SE France and Central Tunisia, a comparison is made between the north and south margins of the Tethyan Ocean by using the occurrences of marker bioevents. For the planktonic foraminifera, the criterions applicable for the accurate determination of Thalmanninella globotruncanoides (Sigal) – the marker species for the base of the Cenomanian stage – are discussed. The species Th. globotruncanoides and the intermediate forms with its ancestor Th. caroni (Ion) are illustrated. For the ammonites, two subjects are new. Firstly, the species Stoliczkaia (Shumarinaia) africana Pervinquiere is illustrated since it is choosen as the indice of the uppermost zone of the Albian (Vraconnian). In northern Africa it replaces Arrhaphoceras (Praeschloenbachia) briacensis (Scholz), the indice for northern Tethys, but restricted to the North European Province. Secondly, specimens of the two genera Graysonites and Utaturiceras – first found in the basal Cenomanian of northern Africa – are described and illustrated.

To allow a comparison between north and south Mediterranean sections, respectively Mont Risou and Marcoule for the north and Tunisia for the south, the stratigraphical position of several proxies from planktonic foraminifera, calcareous nannofossils and ammonites are discussed. A widening of the comparison is proposed by taking into account distant regions such as Madagascar and northern California.
The stratigraphic response to the Oligo-Miocene extension in the western Mediterranean from observations on the Sardinia graben system (Italy)
Authors: Cherchi Antonietta , Mancin Nicoletta , Montadert Lucien , Murru Marco , Putzu Maria Teresa , Schiavinotto Francesco , Verrubbi Vladimiro
Published: June 2008

The Sardinian Cainozoic rifted basin is a useful model for studying the stratigraphic response to the Oligo-Miocene structural extension in the western Mediterranean because it allows precise observations on the relationship between sedimentation and normal faulting based on outcrops and seismic reflection data. The purpose of this paper, essentially of stratigraphic nature is to propose a chronology as precise as possible of the tectonic events and of the sedimentary formations. Indeed the tectono-sedimentary framework is complex, characterized by an extreme facies variability, from continental to marginal transitional and to marine environments (shallow-water, hemipelagic). Rifting, active calc-alkaline volcanism and sea-level changes caused rapid physiographical evolution, which controlled progressive marine ingression. New chronobiostratigraphical data presented in this paper allow correlating the sequences, defining their environment and depth of deposition and specifying precisely the timing of pre-, syn-, and post-rift stages in the Oligo-Miocene graben system. In southwestern Sardinia during the middle-late Eocene, after the Pyrenean phase, a continental graben (Cixerri), W-E oriented, preceded the Oligo-Miocene extension, which reactivated inherited Eocene and Palaeozoic faults. The calc-alkaline volcanic activity ranging from 32 to 13 Ma, provides a good estimate for the time span of the west-dipping Apenninic subduction responsible for the continental extension and the oceanic accretion in the western Mediterranean. In Sardinia the Oligo-Miocene extensional tectonics started in a continental environment, preceding the earliest calc-alkaline volcanic products (32 Ma). The marine ingression is dated to the late Chattian-Aquitanian interval and corresponds to a rapid deepening of the Oligo-Miocene graben system of tectonic origin. The end of the rifting i.e. the end of normal faulting activity is pre-middle Burdigalian in age. When Sardinia was in the post-rift stage, extension continued until late Burdigalian – Langhian in the Algero-Provençal basin with oceanic accretion and rotation of the Corsica-Sardinia block (CSB).
Land Equivalent Ratios, Light Interception, and Water Use in Annual Intercrops in the Presence or Absence of In‐Crop Herbicides
Authors: Szumigalski Anthony R. , Van Acker Rene C.
Published: June 2008

Increased crop production (overyielding) often observed in intercrops compared to sole crops has been attributed to enhanced resource use. The objective of this study was to investigate intercropping complementarity of wheat (Triticum aestivum L.), canola (Brassica napus L.), and field pea (Pisum arvense L.) for light and water use. Sole crop and intercrop combinations were evaluated for effects on land equivalent ratios (LERs), canopy light interception, soil moisture, water use (WU), and water use efficiency (WUE), with or without in‐crop herbicides at two field sites in Manitoba, Canada. The mean LER was 1.1, but LERs varied greatly between site‐years and herbicide treatments, and were significantly greater than one in 22% of the site‐year‐treatment combinations. The wheat‐canola‐pea and canola‐pea intercrops showed the greatest frequency of overyielding for dry matter (50%) and grain yield (38%), respectively. Peak light interception tended to occur earlier with canola than with field pea, thus increasing the potential for light use complementarity between these crops. There was a positive correlation between LER and light interception in half of the site‐years with applied herbicides and a negative correlation between LER and weed biomass at most site‐years without herbicides. Although crop treatments used water differently within the soil profile, there were no differences in WU, but some differences in WUE, between crop treatments; however, WUE generally was not greater in intercrops compared to sole crops. In this study, overyielding in intercrops was inconsistent, and seemed to be related more to light interception than to water utilization.
Influence of Phosphorus, Nitrogen, and Potassium Chloride Placement and Rate on Durum Wheat Yield and Quality
Authors: May William E. , Fernandez Myriam R. , Holzapfel Christopher B. , Lafond Guy P.
Published: June 2008

Information regarding the impact of P and KCl rate and placement in conjunction with N rate on durum wheat (Triticum turgidum L. var. durum) is limited in the Great Plains. Our objectives were to determine the effects of N, P, and KCl fertilizer rate and P and KCl placement on grain yield and quality of durum wheat grown on low P soils. Nine combinations of N and P fertilizer and five combinations of N, P, and KCl applied with the seed and in a side band, were compared over 3 yr at Indian Head, SK, in fields with soil P levels <9 kg ha−1. Grain yield increased 15% as N application increased from 45 to 140 kg ha−1. Grain yield increased by 10% as the P rate increased from 0 to 17 kg ha−1 under dry conditions in 2003, but not in 2002 and 2004. No interaction was detected between N and P for grain yield. Grain yield was unaffected by KCl application and P or KCl placement, in the high K soils included in the study. Grain protein increased from 123 to 150 g kg−1 as N fertilizer rate increased, but decreased from 140 to 136 g kg−1 as more P was applied. However, Red smudge decreased as P increased. Results from this study indicate that N application does not affect the amount of P required by durum wheat and that yield responses to P can occur in soils low in P under dry conditions.
Impact of Fuel and Nitrogen Prices on Profitability of Selected Crops: A Case Study
Authors: Skalsky Sara A. , Jacobs James J. , Menkhaus Dale J. , Stevens W. Bart
Published: June 2008

Increasing prices for fuel and N fertilizer affect crop production decisions and profitability. Nitrogen response functions are estimated for corn (Zea mays L.), sugar beet (Beta vulgaris L.), dry bean (Phaseolus vulgaris L.), and malt barley (Hordeum vulgare L.) using data from field studies conducted in the Big Horn Basin of Wyoming. These N response functions are used to evaluate the impact of increases in N and fuel prices on the profitable level of N use. Enterprise budgets are developed for seven selected crops to determine return to management [Return to Management = Price × Yield – Total Cost (preplant, plant, growing, harvest, land, and other)] under price increases for fuel and N. Finally, a linear programming model is used to determine the impacts of increased prices for fuel and N on farm profit and crop mix. Results illustrate that impacts of increasing fuel and N prices on individual crops are quite different and also vary with the overall crop mix. In particular, adding alfalfa (Medicago sativa L.) and perennial ryegrass (Lolium spp.) seed production to the crop mix reduced the impacts of increasing fuel and N prices. This suggests producers should adjust production practices on individual crops and also analyze their crop mix when faced with rising fuel and N prices if they are to minimize impacts on profitability.
Environmental Influences on Seed Quality of Windmillgrass Ecotypes in South Texas
Authors: Herrera‐C. F. , Ocumpaugh W. R. , Ortega‐S. J. A. , Lloyd‐Reilley J. , Rasmussen G. A. , Maher S.
Published: June 2008

Hooded windmillgrass (Chloris cucullata Bisch.) and shortspike windmillgrass (C. subdolichostachya Muell.) are native grasses with potential for restoration of wildlife habitat. This study was conducted to characterize variability in windmillgrass seed quality as affected by temperature and precipitation. Seed‐fill was superior in 2005 with 18% compared with 10 and 5% obtained in 2003 and 2004, respectively. Hooded ecotypes had higher seed‐fill with 17% compared with 8% in shortspike ecotypes. No differences were found in seed viability among years, species, or ecotypes. Average seed dormancy was greatest in 2005 and 2003 with 82 and 81%, respectively, compared with 75% for 2004. Shortspike 9085283 (S‐283) and 9085260 (S‐260) ecotypes showed greater seed dormancy with values of 94 and 89%, respectively, compared to 73 and 62% for Hooded 9085313 (H‐313) and 9085301 (H‐301), respectively. Seed germination was highest in 2005 (83%), and the lowest (71%) in 2004. The H‐313 and H‐301 ecotypes showed the greatest seed germination with 86 and 83%, respectively, compared with 69 and 67% obtained by S‐283 and S‐260, respectively. We concluded that windmillgrasses are well adapted to variable environments and even when variability existed seed quality was acceptable.
Storage Efficiency of Off‐Season Irrigation
Authors: Stone Loyd R. , Lamm Freddie R. , Schlegel Alan J. , Klocke Norman L.
Published: June 2008

Water levels in the Ogallala aquifer are declining, and with the resultant decrease in water capacity of wells, irrigators face difficulty in meeting crop water needs. Off‐season irrigation is common in the region, although research has shown it is often inefficient. Storage efficiency of off‐season irrigation is affected primarily by the amount of water in the soil profile during storage. Because of much interest in off‐season irrigation, our objective was to describe the relationship between water storage efficiency and soil profile water content. Through use of simulation results from a water balance model, we calculated net water gain on 15 May that resulted from fall or spring irrigation. Storage efficiency was related with the maximum of soil water (SW) from irrigation to 15 May. Storage efficiency was 90 to 95% of spring, or 80 to 85% of fall net irrigation amount, with SW in the lower half of the available water (AW) zone. As SW increased above ≈55% AW for fall or ≈60% AW for spring irrigation, storage efficiency decreased and approached zero with SW near 100% AW. This analysis will help producers understand water storage efficiency of off‐season irrigation and how storage varies with SW.
Comparison of Stay‐Green and Conventional Sunflower Desiccation in the Northern Great Plains
Authors: Larson Tim D. , Johnson Burton L. , Henson Robert A.
Published: June 2008

Desiccant effectiveness in hastening sunflower (Helianthus annuus L.) harvest is based on research conducted for conventional sunflower hybrids; however, information is lacking regarding plant drydown response of more recently developed stay‐green hybrids to desiccation. Stay‐green and conventional sunflower hybrids were evaluated for plant drydown response to desiccant and control treatments in 2000 and 2001 at Carrington, Casselton, and Prosper, ND. The experiment was a randomized complete block arranged in a split‐split‐plot design with desiccation, hybrid, and harvest date representing main, sub‐, and sub‐subplot, respectively. Pioneer Hy‐Bred International oilseed hybrids ‘6338’ (stay‐green) and ‘63M91’ (conventional), and nonoilseed Seeds 2000 stay‐green hybrid ‘Bigfoot’ were evaluated for plant drydown response under natural (control) conditions and when desiccated with paraquat (1,1′‐dimethyl‐4,4′bipyridinium dichloride) applied at the labeled rate. Timing of desiccant application was based on visual characteristics of the capitulm and targeted at physiological maturity when achene moisture ≈ 350 g kg−1. Four harvest dates occurred at 7‐d intervals following desiccant application where achene, receptacle, and stalk moistures were evaluated. Results indicated hybrid achene‐moisture response across harvest dates was similar for the desiccated and control treatments, although desiccation hastened achene‐moisture loss to harvestable levels by 7 d. Harvestable achene and receptacle moistures were concurrent for the conventional hybrid 63M91, however, high receptacle moisture for the stay‐green hybrids 6338 and Bigfoot could prevent harvest even though achene moisture was at harvestable levels. Desiccation hastened hybrids 63M91, 6338, and Bigfoot receptacle drydown to harvestable levels by ≈7 d, however 63M91 reached harvestable moisture ≈5 d earlier than the stay‐green hybrids. Receptacle and stalk moisture differences indicated greater receptacle than stalk moisture differences between stay‐green and conventional hybrids. Desiccation is an important harvest management practice to hasten harvest especially for stay‐green hybrids where receptacle moisture determines harvestability. Increased levels of the stay‐green trait in sunflower may result in desiccation becoming a more common harvest management practice.
Cuphea Seed Yield Response to Harvest Methods Applied on Different Dates
Authors: Berti Marisol T. , Johnson Burton L. , Gesch Russ W. , Forcella Frank
Published: June 2008

Cuphea, Cuphea viscosissima Jacq. × C. lanceolata W.T. Aiton, is a new crop that produces seed containing oil rich in medium‐chain fatty acids. Because cuphea has an indeterminate growth habit, timing of harvest is difficult to determine. The objective of this study was to determine the optimum harvest time and technique for maximizing seed yield. This research was conducted at Prosper, ND, in 2005 and 2006; Carrington, ND, in 2005; and Morris, MN, in 2005 and 2006. The experimental factors were four harvest treatments, direct‐nondesiccated (DND), direct‐desiccated (DD), swathed (SW), and desiccated‐swathed (DSW) applied on three different dates (D1, D2, and D3). Maximum seed moisture was 544 g kg−1, but seed moisture decreased 181 g kg−1 as the harvest date was delayed for the DND‐harvest treatment. Seed moisture reduction for the SW‐harvest treatment compared with the DND‐harvest treatment was 216 g kg−1 for D1. Swathing would be a better method than direct harvest or desiccation to reduce seed moisture at harvest. The harvested seed yields were not significantly different (P ≤ 0.05) among the DND‐, DD‐, and SW‐harvest treatments. Harvested seed yield reduction was observed only for the DSW‐harvest treatment. Swathing is also acceptable since no significant seed yield reduction was observed. Based on the returns after harvest treatments, the DND‐harvest treatment may be the most cost effective method to harvest cuphea seeds; however, it is not the most practical due to clogging of harvesting equipment, which slows down harvest.
Yield and Disease Control on Hard Winter Wheat Cultivars with Foliar Fungicides
Authors: Ransom Joel K. , McMullen Marcia V.
Published: June 2008

Foliar diseases and Fusarium head blight (FHB) (caused by Fusarium graminearum Schwabe) frequently constrain hard winter wheat (HWW) production in the northern Great Plains of North America. Experiments were conducted in North Dakota (ND) to determine the agronomic and economic response of adapted hard winter wheat (HWW; Triticum aestivum L.) cultivars to foliarly applied fungicides. Experiments consisted of a factorial combination of winter wheat cultivars (12–18 depending on the year) and fungicides (no fungicide or fungicides applied) and were conducted in five environments from 2005 to 2007. Yield and disease development varied between environments, with the greatest disease pressure occurring in 2005 and the least in 2006. Within an environment and averaged across cultivars, fungicides improved yields by 5.5 to 44.0%. Cultivars differed significantly in their yield in each environment and cultivar by fungicide interactions for yield occurred in four of the five environments. In all but 2005, varieties that were most responsive to fungicides were those with the greatest disease susceptibility. In 2005, the year of the greatest disease pressure, cultivars that were the most responsive to fungicide were those with the best disease tolerance, indicating the value of integrating several control practices when disease pressure is high. Fungicides were very effective in reducing leaf spots and FHB and provided near complete control of leaf rust. Fungicides can be a valuable tool in increasing yields and profitability of winter wheat, especially if disease susceptible cultivars are grown and if disease pressure is only moderate. Combining fungicides with genetic resistance offers the best monetary return when disease pressure is high.
Comparison of Nitrification Rates in Conventional and Membrane‐Assisted Biological Nutrient Removal Processes
Authors: Monti Alessandro , Hall Eric R.
Published: June 2008

A membrane‐assisted and a conventional activated sludge system, both operated in an enhanced biological phosphorus removal (EBPR) mode and under identical operating conditions, were studied to investigate the effect of the membrane solids–liquid separation on nitrification activity. Both the membrane EBPR (MEBPR) and conventional EBPR (CEBPR) processes achieved stable and complete removal of ammonium‐nitrogen from the influent wastewater. However, when the intrinsic nitrification activity was assessed in offline batch tests, the CEBPR mixed liquor exhibited 15 to 75% greater nitrification potential than the MEBPR counterpart. These results were further validated by monitoring nitrification rates of conventional mixed liquor as it evolved toward a membrane mixed liquor. It was also demonstrated that the larger aerobic mass fraction of the MEBPR system could not be the only factor influencing the reduced intrinsic nitrification rate. The present study strongly suggests that the presence of a membrane solids–liquid separation per se may be sufficient to alter the nitrification kinetics of an EBPR mixed liquor and that this possibility should be considered in arriving at an appropriate process design.
Performance Comparison of Tin Oxide Anodes to Commercially Available Dimensionally Stable Anodes
Authors: Watts Richard J. , Finn Dennis D. , Wyeth Megan S. , Teel Amy L.
Published: June 2008

Dimensionally stable anodes (DSAs) demonstrate potential for the electrochemical treatment of industrial waste streams and disinfection of effluent. Oxidation by laboratory‐prepared tin oxide DSAs was compared with that of commercially available ruthenium oxide, iridium oxide, and mixed metal oxide DSAs, using hexanol as a probe molecule. The performance of the four anodes was similar in two‐chamber reactors, in which the anode cell was separated from the cathode cell by a Nafion membrane, which allows transmission of current between the chambers, but not passage of chemical constituents. The anodes were then evaluated in single‐cell reactors, which are more representative of potential treatment and disinfection applications. However, in the single‐cell reactors, the tin oxide anodes were significantly more effective at oxidation and generated higher quality cyclic voltammograms than the other DSAs. These results suggest that tin oxide anodes have greater potential than the three commercially available DSAs tested for industrial waste stream treatment and effluent disinfection.