132 research outputs found
Modelling forage yield and water productivity of continuous crop sequences in the Argentinian Pampas
In recent years, the use of forage crop sequences (FCS) has been increased as a main component into the animal rations of the Argentinian pasture-based livestock systems. However, it is unclear how year-by-year rainfall variability and interactions with soil properties affect FCS dry matter (DM) yield in these environments. Biophysical crop models, such as Agricultural Production Systems Simulator (APSIM), are tools that enable the evaluation of crop yield variability across a wide of environments. The objective of this study was to evaluate the APSIM ability to predict forage DM yield and water productivity (WP) of multiple continuous FCS. Thirteen continuous FCS, including winter and summer crops, were simulated by APSIM during two/three growing seasons in five locations across the Argentinian Pampas. Our modelling approach was based on the simulation of multiple continuous FCS, in which crop DM yields depend on the performance of the previous crop in the same sequence and the final soil variables of the previous crop are the initial conditions for the next crop. Overall, APSIM was able to accurately simulate FCS DM yield (0.93 and 3.2 Mg haâ1 for concordance correlation coefficient [CCC] and root mean square error [RMSE] respectively). On the other hand, the model predictions were better for annual (CCC = 0.94; RMSE = 0.4 g mâ2 mmâ1) than for seasonal WP (CCC = 0.71; RMSE = 1.9 g mâ2 mmâ1), i.e. at the crop level. The model performance to predict WP was associated with better estimations of the soil water dynamics over the long-term, i.e. at the FCS level, rather than the short-term, i.e. at the crop level. The ability of APSIM to predict WP decreased as seasonal WP values increased, i.e. for low water inputs. For seasonal water inputs, <200 mm, the model tended to under-predict WP, which was directly associated with crop DM yield under-predictions for frequently harvested crops. Even though APSIM showed some weaknesses in predicting seasonal DM yield and WP, i.e. at the crop level, it appears as a potential tool for further research on complementary forage crops based on multiple continuous FCS in the Argentinian livestock systems
Temperature-Driven Developmental Modulation of Yield Response to Nitrogen in Wheat and Maize
Nitrogen management is central to the economic and environmental dimensions of agricultural sustainability. Yield response to nitrogen fertilisation results from multiple interacting factors. Theoretical frameworks are lagging for the interaction between nitrogen and air temperature, the focus of this study. We analyse the relation between yield response to nitrogen fertiliser and air temperature in the critical period of yield formation for spring wheat in Australia, winter wheat in the US, and maize in both the US and Argentina. Our framework assumes (i) yield response to nitrogen fertiliser is primarily related to grain number per m2, (ii) grain number is a function of three traits: the duration of the critical period, growth rate during the critical period, and reproductive allocation, and (iii) all three traits vary non-linearly with temperature. We show that âhighâ nitrogen supply may be positive, neutral, or negative for yield under âhighâ temperature, depending on the part of the response curve captured experimentally. The relationship between yield response to nitrogen and mean temperature in the critical period was strong in wheat and weak in maize. Negative associations for both spring wheat in Australia and winter wheat with low initial soil nitrogen ( 120Â kg N ha-1) that favoured grain number and compromised grain fill, the relation between yield response to nitrogen and temperature was positive for winter wheat. The framework is particularly insightful where data did not match predictions; a non-linear function integrating development, carbon assimilation and reproductive partitioning bounded the pooled data for maize in the US and Argentina, where water regime, previous crop, and soil nitrogen overrode the effect of temperature on yield response to nitrogen fertilisation.Fil: Sadras, Victor O.. University of Adelaide; Australia. South Australian Research And Development Institute; AustraliaFil: Giordano, Nicolas. Kansas State University; Estados UnidosFil: Correndo, Adrian. Kansas State University; Estados UnidosFil: Cossani, C. Mariano. University of Adelaide; Australia. South Australian Research And Development Institute; AustraliaFil: Ferreyra, Juan M.. No especifĂca;Fil: Caviglia, Octavio Pedro. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas; Argentina. Universidad Nacional de Entre RĂos; ArgentinaFil: Coulter, Jeffrey A.. University of Minnesota; Estados UnidosFil: Ciampitti, Ignacio Antonio. Kansas State University; Estados UnidosFil: Lollato, Romulo P.. Kansas State University; Estados Unido
Tuning of metal-insulator transition of two-dimensional electrons at parylene/SrTiO interface by electric field
Electrostatic carrier doping using a field-effect-transistor structure is an
intriguing approach to explore electronic phases by critical control of carrier
concentration. We demonstrate the reversible control of the insulator-metal
transition (IMT) in a two dimensional (2D) electron gas at the interface of
insulating SrTiO single crystals. Superconductivity was observed in a
limited number of devices doped far beyond the IMT, which may imply the
presence of 2D metal-superconductor transition. This realization of a
two-dimensional metallic state on the most widely-used perovskite oxide is the
best manifestation of the potential of oxide electronics
Digital competence across boundaries - beyond a common Nordic model of the digitalisation of K-12 schools?
This paper explores policy related to digital competence and the digitalisation of Nordic K-12 schools. Anchored in some key transnational policies on digital competence, it describes some current Nordic movements in the national policies of Denmark, Finland, Norway and Sweden. The concept of boundary objects is used as an analytical lens, for understanding digital competence as a plastic and temporal concept that can be used to discuss the multi-dimensional translation of this concept in these Nordic countries. The paper ends with a discussion of the potential to view digital competence as a unifying boundary object that, with its plasticity, temporality and n-dimensionality, can show signs of common Nordic efforts in the K-12 school policy.Peer reviewe
Cooperative role of thrombopoietin and vascular endothelial growth factor-a in the progression of liver cirrhosis to hepatocellular carcinoma
Primary thrombopoietic mediator thrombopoietin (THPO) is mainly produced by the liver; it may act as a growth factor for hepatic progenitors. Principal angiogenesis inducer vascular endothelial growth factor-A (VEGF-A) is critical for the complex vascular network within the liver architecture. As a cross-regulatory loop between THPO and VEGF-A has been demonstrated in the hematopoietic system, the two growth factors were hypothesized to cooperatively contribute to the progression from liver cirrhosis (LC) to hepatocellular carcinoma (HCC). The mRNA and protein expression levels of THPO, VEGF-A, and their receptors were examined, compared, and correlated in paired cancerous and LC tissues from 26 cirrhosis-related HCC patients, using qRT-PCR and immunohistochemistry. THPO and VEGF-A were alternatively silenced by small interfering RNA (siRNA) in human liver cancer cell lines Huh7 and HepG2. THPO and VEGF-A expressions significantly increased in tumor versus LC tissues. HCC and paired LC cells expressed similar levels of THPO receptor (R), whereas vascular endothelial growth factor receptor (VEGFR) -1 and VEGFR-2 levels were higher in HCC than in corresponding LC tissue samples. A significant linear correlation emerged between THPO and VEGF-A transcripts in HCC and, at the protein level, THPO and THPOR were significantly correlated with VEGF-A in tumor tissues. Both HCC and LC expressed similar levels of gene and protein hypoxia inducible factor (HIF)-1α. Positive cross-regulation occurred with the alternative administration of siRNAs targeting THPO and those targeting VEGF-A in hypoxic liver cancer cell lines. These results suggest THPO and VEGF-A might act as interdependently regulated autocrine and/or paracrine systems for cellular growth in HCC. This might be clinically interesting, since new classes of THPOR agonistic/antagonistic drugs may provide novel therapeutic options to correct the frequent hemostatic abnormality seen in HCC patients
Rat Long Chain Acyl-CoA Synthetase 5, but Not 1, 2, 3, or 4, Complements Escherichia coli fadD
Long chain fatty acids are converted to acyl-CoAs by acyl-CoA synthetase (fatty acid CoA ligase: AMP forming, E.C. 6.2.1.3; ACS). Escherichia coli has a single ACS, FadD, that is essential for growth when fatty acids are the sole carbon and energy source. Rodents have five ACS isoforms that differ in substrate specificity, tissue expression, and subcellular localization and are believed to channel fatty acids toward distinct metabolic pathways. We expressed rat ACS isoforms 1-5 in an E. coli strain that lacked FadD. All rat ACS isoforms were expressed in E. coli fadD or fadDfadR and had ACS specific activities that were 1.6-20-fold higher than the wild type control strain expressing FadD. In the fadD background, the rat ACS isoforms 1, 2, 3, 4 and 5 oxidized [(14)C]oleate at 5 to 25% of the wild type levels, but only ACS5 restored growth on oleate as the sole carbon source. To ensure that enzymes of beta-oxidation were not limiting, assays of ACS activity, beta-oxidation, fatty acid transport, and phospholipid synthesis were also examined in a fadD fadR strain, thereby eliminating FadR repression of the transporter FadL and the enzymes of beta-oxidation. In this strain, fatty acid transport levels were low but detectable for ACS1, 2, 3, and 4 and were nearly 50% of wild type levels for ACS5. Despite increases in beta-oxidation, only ACS5 transformants were able to grow on oleate. These studies show that although ACS isoforms 1-4 variably supported moderate transport activity, beta-oxidation, and phospholipid synthesis and although their in vitro specific activities were greater than that of chromosomally encoded FadD, they were unable to substitute functionally for FadD regarding growth. Thus, membrane composition and protein-protein interactions may be critical in reconstituting bacterial ACS function
Alien Registration- Breton, Honore (Lewiston, Androscoggin County)
https://digitalmaine.com/alien_docs/30621/thumbnail.jp
Competing magnetostructural phases in a semiclassical system
The interplay between charge, structure, and magnetism gives rise to rich phase diagrams in complex materials with exotic properties emerging when phases compete. Molecule-based materials are particularly advantageous in this regard due to their low energy scales, flexible lattices, and chemical tunability. Here, we bring together high pressure Raman scattering, modeling, and first principles calculations to reveal the pressure-temperature-magnetic field phase diagram of Mn[N(CN)2]2. We uncover how hidden soft modes involving octahedral rotations drive two pressure-induced transitions triggering the low ??? high magnetic anisotropy crossover and a unique reorientation of exchange planes. These magnetostructural transitions and their mechanisms highlight the importance of spin-lattice interactions in establishing phases with novel magnetic properties in Mn(II)-containing systems
Adherence issues related to sublingual immunotherapy as perceived by allergists
Objectives: Sublingual immunotherapy (SLIT) is a viable alternative to subcutaneous immunotherapy to treat allergic rhinitis and asthma, and is widely used in clinical practice in many European countries. The clinical efficacy of SLIT has been established in a number of clinical trials and meta-analyses. However, because SLIT is self-administered by patients without medical supervision, the degree of patient adherence with treatment is still a concern. The objective of this study was to evaluate the perception by allergists of issues related to SLIT adherence. Methods: We performed a questionnaire-based survey of 296 Italian allergists, based on the adherence issues known from previous studies. The perception of importance of each item was assessed by a VAS scale ranging from 0 to 10. Results: Patient perception of clinical efficacy was considered the most important factor (ranked 1 by 54% of allergists), followed by the possibility of reimbursement (ranked 1 by 34%), and by the absence of side effects (ranked 1 by 21%). Patient education, regular follow-up, and ease of use of SLIT were ranked first by less than 20% of allergists. Conclusion: These findings indicate that clinical efficacy, cost, and side effects are perceived as the major issues influencing patient adherence to SLIT, and that further improvement of adherence is likely to be achieved by improving the patient information provided by prescribers. © 2010 Scurati et al, publisher and licensee Dove Medical Press Ltd
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