Journal articles on the topic 'COP rotational component'
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Ospina-Zamudio, J., B. Lefloch, C. Ceccarelli, C. Kahane, C. Favre, A. López-Sepulcre, and M. Montarges. "First hot corino detected around an isolated intermediate-mass protostar: Cep E-mm." Astronomy & Astrophysics 618 (October 2018): A145. http://dx.doi.org/10.1051/0004-6361/201832857.
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Context. Intermediate-mass (IM) protostars provide a bridge between the low- and high-mass protostars. Despite their relevance, little is known about their chemical diversity. Aims. We want to investigate the molecular richness towards the envelope of I-M protostars and to compare their properties with those of low- and high-mass sources. Methods. We have selected the isolated IM Class 0 protostar Cep E-mm to carry out an unbiased molecular survey with the IRAM 30 m telescope between 72 and 350 GHz with an angular resolution lying in the range 7–34″. Our goal is to obtain a census of the chemical content of the protostellar envelope. These data were complemented with NOEMA observations of the spectral bands 85.9–89.6 GHz and 216.8–220.4 GHz at angular resolutions of 2.3″ and 1.4″, respectively. Results. The 30 m spectra show bright emission of O- and N-bearing complex organic molecules (COMs): CH3OH and its rare isotopologues CH2DOH and 13CH3OH, CH3CHO, CH3OCH3, CH3COCH3, HCOOH, HCOOCH3, H2CCO, NH2CHO, CH3CN, C2H3CN, C2H5CN, HNCO and H2CO. We identify up to three components in the spectral signature of COMs: an extremely broad line (eBL) component associated with the outflowing gas (FWHM > 7kms−1), a narrow line (NL) component (FWHM < 3kms−1) associated with the cold envelope, and a broad line (BL) component (FWHM ≃ 5.5kms−1) which traces the signature of a hot corino. The eBL and NL components are detected only in molecular transitions of low excitation and dominate the emission of CH3OH. The BL component is detected in highly excited gas (Eup > 100 K). The NOEMA observations reveal Cep E-mm as a binary protostellar system, whose components, Cep E-A and Cep E-B, are separated by ≈1.7″. Cep E-A dominates the core continuum emission and powers the long-studied, well-known, high-velocity jet associated with HH377. The lower flux source Cep E-B powers another high-velocity molecular jet, reaching velocities of ≈80 km s−1, which propagates in a direction close to perpendicular with respect to the Cep E-A jet. Our interferometric maps show that the emission of COMs arises from a region of ≈0.7″ size around Cep E-A, and corresponds to the BL component detected with the IRAM 30 m telescope. On the contrary, no COM emission is detected towards Cep E-B. We have determined the rotational temperature (Trot) and the molecular gas column densities from a simple population diagram analysis or assuming a given excitation temperature. Rotational temperatures of COMs emission were found to lie in the range 20−40 K with column densities ranging from a few times 1015 cm−2 for O-bearing species, down to a few times 1014 cm−2 for N-bearing species. Molecular abundances are similar to those measured towards other low- and intermediate-mass protostars. Ketene (H2CCO) appears as an exception, as it is found significantly more abundant towards Cep E-A. High-mass hot cores are significantly less abundant in methanol and N-bearing species are more abundant by two to three orders of magnitude. Conclusions. Cep E-mm reveals itself as a binary protostellar system with a strong chemical differentiation between both cores. Only the brightest component of the binary is associated with a hot corino. Its properties are similar to those of low-mass hot corinos.
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Sergison, Darryl J., Tim Naylor, S. P. Littlefair, Cameron P. M. Bell, and C. D. H. Williams. "Characterizing the i-band variability of YSOs over six orders of magnitude in time-scale." Monthly Notices of the Royal Astronomical Society 491, no. 4 (December 4, 2019): 5035–55. http://dx.doi.org/10.1093/mnras/stz3398.
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ABSTRACT We present an i-band photometric study of over 800 young stellar objects in the OB association Cep OB3b, which samples time-scales from one minute to 10 yr. Using structure functions we show that on all time-scales (τ) there is a monotonic decrease in variability from Class I to Class II through the transition disc (TD) systems to Class III, i.e. the more evolved systems are less variable. The Class Is show an approximately power-law increase (τ0.8) in variability from time-scales of a few minutes to 10 yr. The Class II, TDs, and Class III systems show a qualitatively different behaviour with most showing a power-law increase in variability up to a time-scale corresponding to the rotational period of the star, with little additional variability beyond that time-scale. However, about a third of the Class IIs shows lower overall variability, but their variability is still increasing at 10 yr. This behaviour can be explained if all Class IIs have two primary components to their variability. The first is an underlying roughly power-law variability spectrum, which evidence from the infrared suggests is driven by accretion rate changes. The second component is approximately sinusoidal and results from the rotation of the star. We suggest that the systems with dominant longer time-scale variability have a smaller rotational modulation either because they are seen at low inclinations or have more complex magnetic field geometries. We derive a new way of calculating structure functions for large simulated data sets (the ‘fast structure function’), based on fast Fourier transforms.
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Hoeppner, J. W., M. H. Entz, B. G. McConkey, R. P. Zentner, and C. N. Nagy. "Energy use and efficiency in two Canadian organic and conventional crop production systems." Renewable Agriculture and Food Systems 21, no. 1 (March 2006): 60–67. http://dx.doi.org/10.1079/raf2005118.
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AbstractA goal in sustainable agriculture is to use fossil fuel energy more efficiently in crop production. This 12-year study investigated effects of two crop rotations and two crop production systems (organic versus conventional management) on energy use, energy output and energy-use efficiency. The grain-based rotation included wheat (Triticum aestivumL.)–pea (Pisum sativumL.)–wheat–flax (Linum usitatissimumL.), while the integrated rotation included wheat–alfalfa (Medicago sativaL.)–alfalfa–flax. Energy use was 50% lower with organic than with conventional management, and approximately 40% lower with integrated than with the grain-based rotation. Energy use across all treatments averaged 3420 MJ ha−1yr−1. Energy output (grain and alfalfa herbage only) across treatments averaged 49,947 MJ ha−1yr−1and was affected independently by production system and crop rotation. Energy output in the integrated rotation was three times that of the grain-based rotation; however, this difference was largely due to differences in crop type (whole plant alfalfa compared with grain seed). Energy output was 30% lower with organic than with conventional management. Energy efficiency (output energy/input energy) averaged to 17.4 and was highest in the organic and integrated rotations. A significant rotation by production system interaction (P<0.05) indicated that energy efficiency increases due to crop input reduction (i.e., shift from conventional to organic management) were greater in the integrated than in the grain-based rotation. Greater energy efficiency in the integrated rotation under organic management was attributed to the fact that the forage component was less sensitive to chemical input removal than grain crops.
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He, Dun-Chun, Yan-Li Ma, Zhuan-Zhuan Li, Chang-Sui Zhong, Zhao-Bang Cheng, and Jiasui Zhan. "Crop Rotation Enhances Agricultural Sustainability: From an Empirical Evaluation of Eco-Economic Benefits in Rice Production." Agriculture 11, no. 2 (January 21, 2021): 91. http://dx.doi.org/10.3390/agriculture11020091.
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Cropping systems greatly impact the productivity and resilience of agricultural ecosystems. However, we often lack an understanding of the quantitative interactions among social, economic and ecological components in each of the systems, especially with regard to crop rotation. Current production systems cannot guarantee both high profits in the short term and social and ecological benefits in the long term. This study combined statistic and economic models to evaluate the comprehensive effects of cropping systems on rice production using data collected from experimental fields between 2017 and 2018. The results showed that increasing agricultural diversity through rotations, particularly potato–rice rotation (PR), significantly increased the social, economic and ecological benefits of rice production. Yields, profits, profit margins, weighted dimensionless values of soil chemical and physical (SCP) and heavy metal (SHM) traits, benefits and externalities generated by PR and other rotations were generally higher than successive rice cropping. This suggests that agricultural diversity through rotations, particularly PR rotation, is worth implementing due to its overall benefits generated in rice production. However, due to various nutrient residues from preceding crops, fertilizer application should be rationalized to improve the resource and investment efficiency. Furthermore, we internalized the externalities (hidden ecological and social benefits/costs) generated by each of the rotation systems and proposed ways of incenting farmers to adopt crop rotation approaches for sustainable rice production.
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Mohr, R. M., D. A. Derksen, C. A. Grant, D. L. McLaren, M. A. Monreal, A. M. Moulin, M. Khakbazan, and R. B. Irvine. "Effect of nitrogen fertilizer rate, herbicide rate, and soil disturbance at seeding on the productivity of a wheat-pea rotation." Canadian Journal of Plant Science 87, no. 2 (April 1, 2007): 241–53. http://dx.doi.org/10.4141/p05-226.
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Rotational productivity is a function of the rotational crops and their interactions, as well as the management employed. Understanding the functioning of the overall production system, as well as its component parts, may contribute to improved management. Effects of nitrogen fertilizer rate (25, 50, 75, 100 kg N ha-1 as urea) and herbicide rate (66 or 100% of recommended) applied to wheat, and of the level of soil disturbance at seeding, on the productivity and N status of a 2-yr rotation of spring wheat (Triticum aestivum L.) and field pea (Pisum sativum L.) were assessed over two rotation cycles at two locations in southwestern Manitoba. Management factors typically acted independently to influence the cropping system. In both wheat and pea, high soil disturbance at seeding reduced or tended to reduce plant density in most site-years, resulting in reduced yields in about half of site-years. In 2 site-years where weed pressure was high, wheat yields for high disturbance treatments were less than 60% of low disturbance seeding, demonstrating the importance of adequate plant stands under sub-optimal growing conditions. The herbicide rate applied to wheat had few significant effects on wheat and pea. In most site-years, N fertilization had limited or negative effects on wheat yields due partly to relatively high soil NO3-N levels. Soil NO3-N levels declined over the years of the study, suggesting that N contributions from peas did not exceed crop N removal and/or N losses from the wheat-pea rotation. The N rate applied to wheat typically did not affect pea yields. Key words: Wheat, pea, rotation, herbicide, nitrogen, soil disturbance
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Arumugasamy, Prakash, and Dipanjan Mitra. "Evaluating the evidence of multipolar surface magnetic field in PSR J0108–1431." Monthly Notices of the Royal Astronomical Society 489, no. 4 (August 19, 2019): 4589–605. http://dx.doi.org/10.1093/mnras/stz2299.
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ABSTRACT PSR J0108–1431 is an old pulsar where the X-ray emission is expected to have a thermal component from the polar cap and a non-thermal component from the magnetosphere. Although the phase-integrated spectra are fit best with a single non-thermal component modelled with a power law (PL) of photon index Γ = 2.9, the X-ray pulse profiles do show the presence of phase-separated thermal and non-thermal components. The spectrum extracted from half the rotational phase away from the X-ray peak fits well with either a single blackbody (BB) or a neutron star atmosphere (NA) model, whereas the spectrum from the rest of the phase range is dominated by a PL. From Bayesian analysis, the estimated BB area is smaller than the expected polar cap area for a dipolar magnetic field with a probability of 86 per cent, whereas the area estimate from the NA model is larger with a probability of 80 per cent. Due to the ambiguity in the thermal emission model, the polar cap area cannot be reliably estimated and hence cannot be used to understand the nature of the surface magnetic field. Instead, we can infer the presence of multipolar magnetic field from the misalignment between the pulsar’s thermal X-ray peak and the radio emission peak. For J0108–1431, we estimated a phase-offset Δϕ > 0.1 between the thermal polar cap emission peak and the radio emission peak and argue that this is best explained by the presence of a multipolar surface magnetic field.
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Anderson, Randy L., Clair E. Stymiest, Bruce A. Swan, and John R. Rickertsen. "Weed Community Response to Crop Rotations in Western South Dakota." Weed Technology 21, no. 1 (March 2007): 131–35. http://dx.doi.org/10.1614/wt-06-011.1.
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Producers in the semiarid Great Plains are exploring alternative crop rotations, with the goal of replacing winter wheat–fallow. In 1993, a study was established to compare performance of eight rotations comprised of various combinations with winter wheat (W), spring wheat (SW), dry pea (Pea), safflower (Saf), corn (C), sunflower (Sun), proso millet (M), or fallow (F). After 8 years, we characterized weed communities by recording seedling emergence in each rotation. Seventeen species were observed, with downy brome, kochia, horseweed, and stinkgrass comprising 87% of the community. Rotations with the least number of weed seedlings were W–F and SW–W–C–Sun; in comparison, weed density was six-fold higher in W–M. Density of downy brome and kochia was highest in W–M compared with other rotations, whereas stinkgrass and green foxtail were prominent in proso millet of the W–M and W–C–M rotations. Horseweed established readily in safflower and dry pea. In the semiarid Great Plains, designing rotations in a cycle of four that includes cool- and warm-season crops can be a key component of integrated weed management.
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Wu, Teng, Fanting Kong, Lei Shi, Qing Xie, Yongfei Sun, and Changlin Chen. "Power Consumption Influence Test of Castor Disc-Cutting Device." Agriculture 12, no. 10 (September 23, 2022): 1535. http://dx.doi.org/10.3390/agriculture12101535.
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This study theoretically analyzed the cutting process of castor and determined the structural parameters of the key component of the castor disc-cutting device, aiming to obtain the optimal operation parameter combination and reduce the cutting resistance and power consumption during the harvesting process. The effects of the cutting-disc thickness, cutting-disc rotational speed, feeding speed, and edge angle on the cutting power consumption were studied using an orthogonal rotation combination experiment. The response surface method was used to optimize the parameters, and the mathematical relationship model between the cutting power consumption and each factor was established to determine the optimal parameter combination for disc cutting. The simulation results showed that the optimal combination of cutting parameters was cutting-disc thickness of 3 mm, cutting-disc rotational speed of 550 r/min, feeding speed of 0.6 m/s, and edge angle of 20°. Under these conditions, the cutting power consumption was 1.20375 J. The test results were basically consistent with the model prediction results. Therefore, this study provided a theoretical basis and reference for the design and improvement of castor harvesters.
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Blackshaw, Robert E. "Rotation Affects Downy Brome (Bromus tectorum) in Winter Wheat (Triticum aestivum)." Weed Technology 8, no. 4 (December 1994): 728–32. http://dx.doi.org/10.1017/s0890037x00028591.
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Downy brome control in winter wheat is often inadequate. The effects of three crop rotations and two tillage intensities on downy brome populations and associated crop yields were determined in an experiment at Lethbridge, Alberta from 1987 to 1993. Downy brome densities in continuous winter wheat increased from 24 to 970 plants/m2between 1988 and 1993; and were often higher with zero tillage. Inclusion of fallow or spring canola in rotation with winter wheat suppressed downy brome densities to less than 55 and 100 plants/m2, respectively, over the six years. In continuous winter wheat, yields decreased as downy brome densities increased progressively over years, indicating that monoculture winter wheat production will not be viable in regions where downy brome is prevalent unless effective herbicides are developed. In the more arid areas of the Canadian prairies, a winter wheat-fallow rotation may be most suitable but in higher precipitation areas, a winter wheat-canola rotation is a viable alternative. Crop rotation is a key component of an improved management system for control of downy brome.
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NEKRASENKO, L. A. "TAX INCENTIVES TO MANAGE LAND AS A NATURAL ASSET." Economic innovations 24, no. 1(82) (March 20, 2022): 122–29. http://dx.doi.org/10.31520/ei.2022.24.1(82).122-129.
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Topicality. Successful economic development of agriculture is one of the components of Ukraine's sustainable development. But this development very often leads to changes in natural and climatic conditions and to increased risks for doing business. Agricultural land is a natural asset and it should be taken into account that the change oflandscapes from natural vegetation to any other use can lead to loss, degradation, and fragmentation of the environment, all of which can have devastating consequences for biodiversity as a source of ecosystem services. Therefore, it is important to find ways to rationally manage the land.Aim and tasks. The purpose of our study was to substantiate the relevance of taxes for the management and rational use of land as a natural asset. As a tool, we consider a tax on crop rotation, which leads to a decrease in soil fertility and the release of carbon from dying plant residues. Crop rotation planning will help reprioritize crop selection, increase fertility and reduce carbon emissions.Research results. The main component of the sustainable development of the agricultural sector is soil fertility. At the same time, land use and agriculture are the main natural agents for reducing air pollution. Today, agriculture accounts for about 20% of greenhouse gas emissions, and humus losses range from 19% to 22% in different natural areas. Considering agricultural land as a natural asset, it should be taken into account that their irrational use leads to a change in natural and climatic conditions and an increase in risks for doing business. We have proposed to introduce carbon crop rotations as a tool for soil quality management. In our opinion, this should contribute to a change in priorities in the choice of agricultural crops, and as a result, an increase in fertility and an increase in carbon sequestration. To stimulate agricultural enterprises, we consider it expedient to introduce a tax on crop rotation. To substantiate this idea, we have created a model for the dependence of CO2 absorption/emission on the yield of various crops and a decision-making model for planning the costs of an agricultural enterprise.Conclusion. We have conducted a study of the relationship between the yield of various crops and the absorption/release of carbon dioxide. We put forward a hypothesis: there is a certain relationship between the yield of different crops and the balance of absorption/release of CO2. We have studied this connection. The model of dependence of CO2 uptake/emission on the yield of different crops shows that the ability to release carbon by plant residues of different agricultural crops has both a direct and inverse relationship with the yield of various crops. We have developed a decision-making model for planning the costs of an enterprise, subject to planning for environmental risks or paying a tax on carbon crop rotations. Thus, the problems of land use as a natural asset in agriculture can be solved by: the introduction of carbon crop rotations, which should help change priorities in the choice of agricultural crops, and the introduction of a balanced and evidence-based approach to the development and implementation of environmental taxes.
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Asgharifard-Sharabiani, P., A. Hannaneh, and M. Nikkhah-Bahrami. "Calculation of helical gear’s basic parameters using COP-data acquired by optical 3D digitizer." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 225, no. 12 (September 29, 2011): 2953–62. http://dx.doi.org/10.1177/0954406211409841.
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Gears are industrial components with a precise geometry. Identification of their basic parameters plays an important role in their reverse design and quality control process. This article describes a new approach for the calculation of helical gear’s basic parameters using optical data acquired by 3D digitizer. This approach is implemented by acquiring cloud-of-points data (COP-data) from the bearing seats and gear tooth surface. Cylinder surface fitting through COP-data acquired from bearing seats is performed for the determination of gear axis of rotation. In a final step, involute helicoid surface fitting through COP-data acquired from gear tooth surface determines the helical gear’s primary features. Particle swarm optimization algorithm as an efficient method is applied to perform the surface fitting process in this article.
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Raushan, Rakesh, and R. Chaubey. "Qualitative study of anisotropic cosmological models with dark sector coupling." Canadian Journal of Physics 95, no. 11 (November 2017): 1049–61. http://dx.doi.org/10.1139/cjp-2017-0088.
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In this paper, we study the dynamical evolution of locally rotationally symmetric (LRS) Bianchi type I cosmological model with coupling of dark sector. We investigate the phase-plane analysis when dark energy is modelled as exponential quintessence, and is coupled to dark energy matter via linear coupling between both dark components. The evolution of cosmological solutions is studied by using dynamical systems techniques. Stability and viability issues for three different physically viable linear couplings between both dark components are presented and discussed in detail.
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Loeppky, H. A., and D. A. Derksen. "Quackgrass suppression through crop rotation in conservation tillage systems." Canadian Journal of Plant Science 74, no. 1 (January 1, 1994): 193–97. http://dx.doi.org/10.4141/cjps94-039.
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Quackgrass [Elytrigia repens (L.) Nevski] is a widespread perennial weed traditionally controlled by tillage, a practice which can contribute to soil erosion and degradation. This study was initiated to determine the impact of integrated weed management strategies utilizing crop rotation, conservation tillage, and postemergence herbicides on quackgrass. Rotations of tall and semi-dwarf winter wheat (Triticum aestivum L. 'Norstar' and 'Norwin') or spring wheat (Triticum aestivum L. 'Katepwa' and 'HY320') with mustard (Brassica juncea 'Common Brown') and flax (Linum usitatissimum L. 'Norlin') were conducted at Indian Head, Saskatchewan for 4 yr to determine their effect on quackgrass shoot density, rhizome dry weight and rhizome node density. The presence or absence of winter wheat within the crop rotation had the greatest impact on quackgrass growth. During years when drought hampered winter wheat establishment, quackgrass growth was greater in winter wheat than in spring wheat, but under conditions favoring winter wheat establishment, the opposite occurred. Quackgrass growth in standard height wheat was similar to semi-dwarf wheat. Annual differences in quackgrass growth occurred between mustard and flax, but overall, no trend developed. Shoot density, rhizome biomass, and rhizome node density were not consistently correlated to crop yield. Crop rotation is a useful component of an integrated quackgrass management system. Key words: Integrated weed management (IWM), quackgrass, Elytrigia repens, crop rotation, conservation tillage
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Othman, Mohamed I. A., and Ibrahim A. Abbas. "Effect of rotation on plane waves in generalized thermomicrostretch elastic solid: comparison of different theories using finite element method." Canadian Journal of Physics 92, no. 10 (October 2014): 1269–77. http://dx.doi.org/10.1139/cjp-2013-0482.
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The present investigation is aimed at studying the effect of rotation on the thermomicrostretch elastic solid. The formulation is applied in the context of the generalized thermoelasticity Lord–Şhulman theory with one relaxation time and Green–Lindsay’s theory with two relaxation times, as well as the classical dynamical coupled theory. The problem has been solved numerically using a finite element method. Numerical results for the temperature distribution, the displacement components, the force stresses, the couple stresses, and the microstress distribution are represented graphically. The results indicate that the effects of rotation are very pronounced. Comparisons are made with the results in the presence and absence of rotation and in the presence and absence of microstretch constants between the two theories.
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Matheron, Michael E., and Martin Porchas. "Efficacy of Fungicides and Rotational Programs for Management of Powdery Mildew on Cantaloupe." Plant Disease 97, no. 2 (February 2013): 196–200. http://dx.doi.org/10.1094/pdis-04-12-0370-re.
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Powdery mildew of cucurbits, caused by Podosphaera xanthii (syn. Sphaerotheca fuliginia auct. p.p. (Schltdl.) Pollacci), is a common and often severe disease in most areas of the world. Field trials were conducted with cantaloupe to compare disease management success provided by conventional fungicides and biofungicides having different inherent efficacies and modes of action, when applied alone throughout the treatment period or as components of fungicide application programs. Additionally, the portion of total disease control provided by each component fungicide within selected rotational programs was determined. When applied alone throughout the treatment period, disease severity in 2008 and 2009 compared with nontreated plants was reduced by values of 100, 99.3, and 98.1% by wettable sulfur (Microthiol Disperss), triflumizole (Procure), and quinoxyfen (Quintec), respectively; 83.9, 76.4, and 57.4% by trifloxystrobin (Flint), pyraclostrobin (Cabrio), or azoxystrobin (Quadris), respectively; and 39.8, 31.1, 30.0, and 28.6% by thiophanate-methyl (Topsin M), potassium bicarbonate (Kaligreen), kresoxim-methyl (Sovran), and Bacillus subtilis (Serenade), respectively. Rotational application programs composed of Microthiol Disperss, Procure, and Quintec reduced powdery mildew severity on cantaloupe by 97.5 to 100% in both trials. In comparison, disease reduction of 86.0 to 100% was achieved when the first and third fungicide applications were Quintec or Procure and the second and fourth applications were Cabrio, Flint, Kaligreen, Quadris, Serenade, Sovran, or Topsin M. In field trials designed to elucidate the portion of total disease control provided by each component fungicide within a rotational program, application sequences of Procure, Streptomyces lydicus (Actinovate), Procure, and Actinovate or Procure, Kaligreen, Procure, and Kaligreen resulted in reductions in powdery mildew severity of 69.1 and 78.7%, respectively. In comparison, inclusion of only the two Procure applications brought about a mean disease reduction of 85%, whereas inclusion of only the two Actinovate or Kaligreen applications reduced the level of powdery mildew control to 17.6 and 12.9%, respectively. The usefulness of fungicides with low inherent efficacy as resistance management partners when applied with highly efficacious at-risk fungicides may be questioned; however, the importance of any fungicide as a resistance management partner should be measured by its ability to dilute the selection pressure of the at-risk fungicide and to inhibit the growth of any resistant biotypes that may arise, factors which may not be reflected by its inherent efficacy in controlling disease. Because less efficacious fungicides did not increase the overall level of disease control, encouraging growers and pest control advisors to incorporate them into powdery mildew treatment programs may be a challenge, because resistance management is not their top priority. An ongoing educational effort emphasizing the benefits of resistance management programs with respect to prolonging the effectiveness of single-site mode of action fungicides is essential.
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Futa, Barbara, Piotr Kraska, Sylwia Andruszczak, Paweł Gierasimiuk, and Monika Jaroszuk-Sierocińska. "Impact of Subsurface Application of Compound Mineral Fertilizer on Soil Enzymatic Activity under Reduced Tillage." Agronomy 11, no. 11 (October 31, 2021): 2213. http://dx.doi.org/10.3390/agronomy11112213.
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Soil biochemical properties shaping soil fertility and agro-ecosystem productivity depend on the reduced tillage system and the dose and method of application of fertilizer; therefore, the research hypothesis put forward proposes that under reduced tillage system conditions, the subsurface application of a multi-component mineral fertilizer would increase soil enzymatic activity, thus favourably influencing the biodiversity of the soil environment. The objective of the three-year study was to evaluate the impact of subsurface application of varying mineral fertilizer rates on soil enzymatic activity under reduced tillage system conditions in soybean, winter wheat and maize rotations. The field experiment was set up as a split-plot design in four replicates. The first experimental factor included two methods of mineral fertilization application: fertilizer broadcast over the soil surface (S); fertilizer applied deep (subsurface placed) using a specially designed cultivator (Sub-S). The other factor was the rates of the mineral fertilizer (NPKS): 85 kg∙ha−1 (F85) and 170 kg∙ha−1 (F170). The method of application and rate of mineral fertilizer did not have a significant effect on the organic carbon and total nitrogen content in the soil of the plots with all rotational crops. Subsurface application of fertilizer significantly increased available phosphorus content in soil under soybean and winter wheat crops; however, it significantly decreased soil pHKCl values within sites with all crops in the rotation compared to surface application. At the same time, deep application of mineral fertilizer significantly stimulated dehydrogenase activity in the soil under the winter wheat crops and acid phosphatase activity in the soil under all rotation crops. The higher level of mineral fertilization contributed to reduction of soil pHKCl under winter wheat and maize, and promoted an increase in the soil P content. Additionally, significant increases of dehydrogenases and urease activity in the soil under winter wheat and maize crops, alkaline phosphatase activity in the soil under all the studied crops, and acid phosphatase activity in the soil under the soybean crops were found, compared to mineral fertilizer in the amount of 85 kg NPKS∙ha−1. The results of the present study have demonstrated a positive effect of subsurface application of compound mineral fertilizer on the soil biochemical parameters in reduced tillage. This may be a recommendation for the subsurface use of multicomponent mineral fertilizers in sustainable agriculture. However, a full objective characterization of the soil environment processes induced by in-depth application of mineral fertilizer in reduced tillage requires long-term monitoring.
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Othman, Mohamed I. A., Magda E. M. Zidan, and Mohamed I. M. Hilal. "Effect of magnetic field on a rotating thermoelastic medium with voids under thermal loading due to laser pulse with energy dissipation." Canadian Journal of Physics 92, no. 11 (November 2014): 1359–71. http://dx.doi.org/10.1139/cjp-2013-0689.
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This investigation deals with the rotation of magneto-thermoelastic solid with voids subjected to thermal loading due to laser pulse. The bounding plane surface is heated by a non-Gaussian laser beam. The entire porous medium is rotated with a uniform angular velocity. The problem is studied in the context of Green–Naghdi (GN) theory of types II and III, with the effect of rotation, magnetic field, thermal loading and voids. Normal mode analysis is used to solve the physical problem to obtain the exact expressions for the displacement components, stresses, temperature distribution, and change in the volume fraction field, which have been shown graphically by comparison between two types of GN theory (types II and III) in the presence and the absence of rotation and magnetic field and for two values of time on thermoelastic material with voids.
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Curtin, D., H. Wang, F. Selles, C. A. Campbell, and R. P. Zentner. "Soil fertility effects on carbon fluxes under two spring wheat rotations in a semiarid agroecosystem." Canadian Journal of Soil Science 82, no. 2 (May 1, 2002): 155–63. http://dx.doi.org/10.4141/s01-038.
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Changes in soil C storage due to management practices are important in relation to soil quality and to the broader issue of atmospheric C sequestration. Our objective was to evaluate the effects of soil fertility management on C fluxes under two spring wheat (Triticum aestivum L.) rotations in semiarid southwestern Saskatchewan, i.e., continuous wheat (Cont W) and a rotation that included summerfallow every third year (F-W-W). Continuous wheat was grown under two fertility regimes since initiation of the experiment in 1967, i.e., fertilization with N+P (no nutrient limitation) or with P only. In F-W-W there were three fertility treatments: N+ P, N only, and P only. We measured soil CO2 emissions under all fertility treatments and rotation phases during the 1995 and 1996 cropping seasons (emissions were measured at about weekly intervals between spring and freeze-up in autumn). Inputs of C in straw were measured and a root:straw ratio of 0.59 was used to estimate root C inputs. Alleviation of nutrient limitations generally had a positive effect on wheat growth (and thus on C inputs), particularly in 1995, the wetter of the 2 yr (precipitation 14% greater than average). For example, C inputs in 1995 under Cont W were estimated at 2700 kg ha-1 in the N+P treatment compared with 1500 kg ha-1 in the P only treatment. Fertility treatments had little effect on CO2 emissions; e.g., for Cont W the mean flux for the 1995 monitoring period was 2.7 mmol CO2 m-2s-1 where N + P was applied and 2.6 mmol CO2 m-2s-1 where P only was applied. Greater C inputs, but similar outputs of CO2-C for the N + P treatment vs. the systems receiving N or P only, suggest that proper fertilization resulted in a gain in soil C. However, quantifying the fertility-induced C gain is problematic because of uncertainty regarding effects of fertility on several components of the C budget, particularly root-C inputs and the contribution of rhizosphere respiration to the measured CO2 flux. Key words: Carbon sequestration, N and P fertilization, CO2 emissions, C inputs in crop residues, spring wheat, summerfallow
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Akramieh, Elham, and Antonio Giuffrida. "Assessment of closed cycles operating with supercritical CO2 as bottoming of small combustion turbines." Journal of Physics: Conference Series 2385, no. 1 (December 1, 2022): 012106. http://dx.doi.org/10.1088/1742-6596/2385/1/012106.
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Abstract This work investigates the performance of supercritical CO2 power cycles bottoming small combustion turbines. As a matter of fact, the maximum power output of the topping cycle is limited to 10 MW, since there is a great number of commercial combustion turbine units for which the conventional combined cycle architecture with a bottoming steam power plant is not convenient. In detail, the partial heating cycle is the layout chosen for this study according to the interesting trade-off between heat recovery and cycle efficiency, with a limited number of components. Considering the investigated range of power production, single-stage radial turbomachines are selected and their efficiency values are not fixed at first glance but result from actual size and running conditions, based on flow rates, enthalpy variations as well as rotational speeds. Focusing on a number of cases, interesting considerations about the size of the components of the supercritical CO2 power cycle are possible thanks to the theory of similitude.
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Othman, Mohamed I. A., W. M. Hasona, and Elsayed M. Abd-Elaziz. "The effect of rotation on the problem of fiber-reinforced under generalized magnetothermoelasticity subject to thermal loading due to laser pulse: a comparison of different theories." Canadian Journal of Physics 92, no. 9 (September 2014): 1002–15. http://dx.doi.org/10.1139/cjp-2013-0321.
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In the present paper, we introduce the coupled theory, Lord–Schulman theory, and Green–Lindsay theory to study the influences of a magnetic field and rotation on a two-dimensional problem of fiber-reinforced thermoelasticity subject to thermal loading by a laser pulse. The material is a homogeneous isotropic elastic half-space and is heated by a non-Gaussian laser beam with pulse duration of 8 ps. The method applied here is to use normal mode analysis to solve a thermal shock problem. Deformation of a body depends on the nature of the force applied as well as the type of boundary conditions. Numerical results for the temperature, displacement, and thermal stress components are given and illustrated graphically in the absence and the presence of the magnetic field, rotation, reinforcement, and for two different values of time.
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Telles, Tiago S., Ana J. Righetto, Marco A. P. Lourenço, and Graziela M. C. Barbosa. "No-tillage system participatory quality index." Revista Brasileira de Engenharia Agrícola e Ambiental 24, no. 2 (February 2020): 128–33. http://dx.doi.org/10.1590/1807-1929/agriambi.v24n2p128-133.
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ABSTRACT The no-tillage system participatory quality index aims to evaluate the quality and efficiency of soil management under no-tillage systems and consists of a weighted sum of eight indicators: intensity of crop rotation, diversity of crop rotation, persistence of crop residues in the soil surface, frequency of soil tillage, use of agricultural terraces, evaluation of soil conservation, balance of soil fertilization and time of adoption of the no-tillage system. The aim of this study was to assess the extent to which these indicators correlate with the no-tillage system participatory quality index and to characterize the farmers who participated in the research. The data used were provided by ITAIPU Binacional for the indicators of the no-tillage system participatory quality index II. Descriptive analyses were performed, and the Pearson correlation coefficient between the index and each indicator was calculated. To assess the relationship between the indicators and the farmers’ behavior toward the indicators, principal component analysis and cluster analysis were performed. Although all correlations are significant at p-value ≤ 0.05, some correlations are weak, indicating a need for improvement of the index. The principal component analysis identified three principal components, which explained 66% of the variability of the data, and the cluster analysis separated the 121 farmers into five groups. It was verified that the no-tillage system participatory quality index II has some limitations and should therefore be reevaluated to increase its efficiency as an indicator of the quality of the no-tillage system.
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Magnago, Letícia Mayara, Marina Donária Chaves Arantes, Graziela Baptista Vidaurre, Jordão Cabral Moulin, and Paulo Fernando Trugilho. "ENERGY ESTIMATE AND CARBON STOCK IN SHORT-ROTATION EUCALYPTUS STANDS." CERNE 22, no. 4 (December 2016): 527–34. http://dx.doi.org/10.1590/01047760201622042209.
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ABSTRACT The use of biomass as an alternative energy source has been gaining attention because of its energy characteristics and environmental contribution and because it is renewable in short production periods. The aim of the present study was to evaluate the biomass production and carbon sequestration of eucalyptus grown under different conditions. The basic density of the wood, stem volume with and without bark and dry biomass, accumulated carbon, assimilated carbon dioxide and estimated energy for each shoot component were determined for two hybrid clones of E. grandis x E. urophylla at 6 and 12 months of age, grown at different spacing in two different areas, one with and one without irrigation. The highest dry biomass and carbon accumulation values were observed for plants grown at smaller spacing and with irrigation. A significant effect of irrigation on the variables quantified was only observed for 12-month-old plants. The amount of assimilated CO2 in the stem, leaves and branches was higher for 12-month-old plants grown at larger spacing and with irrigation. The estimated energy of the stem increased with increased spacing. Bark was the shoot component least influenced by spacing and irrigation.
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Saha, Bijan. "Spinor field in Bianchi type-IX space–time." Canadian Journal of Physics 96, no. 10 (October 2018): 1074–84. http://dx.doi.org/10.1139/cjp-2017-0711.
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Within the scope of Bianchi type-IX cosmological model we have studied the role of spinor field in the evolution of the Universe. It is found that unlike the diagonal Bianchi models in this case the components of energy–momentum tensor of spinor field along the principal axis are not the same (i.e., [Formula: see text]), even in the absence of spinor field nonlinearity. The presence of nontrivial non-diagonal components of energy–momentum tensor of the spinor field imposes severe restrictions both on geometry of space–time and on the spinor field itself. As a result the space–time turns out to be either locally rotationally symmetric or isotropic. In this paper we considered the Bianchi type-IX space–time both for a trivial b, that corresponds to standard Bianchi type-IX and the one with a non-trivial b. It was found that a positive self-coupling constant λ1 gives rise to an oscillatory mode of expansion, while a trivial λ1 leads to rapid expansion at the early stage of evolution.
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Aslan, Fadik, Laurent Langlois, Philippe Mangin, and Tudor Balan. "Identification of Drilling Parameters during the Flow Drill Screw Driving Process." Key Engineering Materials 767 (April 2018): 465–71. http://dx.doi.org/10.4028/www.scientific.net/kem.767.465.
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The automobile manufacturing industry, until recent years, has been using steel for car body components and the main method for joining these components has always been Resistance Spot Welding. However, since the global trends toward CO2 reduction and resource efficiency have significantly increased, the importance and usage of lightweight materials has enhanced as well. New lightweight materials such as aluminum and magnesium alloys, carbon-fiber-reinforced plastics, etc., have become a reality, thanks to the new fastening technologies. Flow drill screw driving (FDS) is a one–sided thermomechanical assembly process based on heat generation by frictional force and plastic deformation. A special screw, known as hole forming and self-tapping screw, is used in this process as both fastener and tool. Moreover, rotational and translation movements are applied to the screw to create special friction conditions with the workpiece. Furthermore, unlike traditional drilling and thread milling processes, there is no chip or waste of material in FDS and the machining operations are realized through plastic deformation. This paper explores flow drilling steps and the parameters which influence heating and local softening of the aluminum sheet 5182-0. An experimental study has been carried out by varying process parameters (rotational speed, drilling force), coating and geometry of the screw. As a result, an increase of rotational speed and drilling force allows significant reduction in drilling time and introduce an important variation of the torque installation. In addition, a strong dependence is observed between drilling time and torque on the one hand, and related to the screw parameters geometry and coating on the other hand. Finally, an evaluation of the heating effect on the thread forming operation is also undertaken.
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Rigoselli, Michela, and Sandro Mereghetti. "A new X-ray look into four old pulsars." Astronomy & Astrophysics 615 (July 2018): A73. http://dx.doi.org/10.1051/0004-6361/201732408.
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We report on the X-ray properties of four rotation-powered pulsars with characteristic ages in the range 0.3–5 Myr, derived from the analysis of XMM–Newton archival observations. We found convincing evidence of thermal emission only in the phase-averaged spectrum of PSR B0114+58, which is well fitted by a blackbody with temperature kT = 0.17 ± 0.02 keV and emitting radius R = 405+110−90 m, consistent with the size of its polar cap. The three other considered pulsars, PSR B0628−28, PSR B0919+06, and PSR B1133+16, have phase-averaged spectra that can be described well by single power laws with photon index Γ ~ 3. The 3σ upper limits on the bolometric luminosity of a possible thermal component with temperatures in the range ~0.05−2 keV are Lbol ≲ 3.2 × 1028 erg s−1 and Lbol ≲ 2.4 × 1029 erg s−1, for PSR B0628−28 and PSR B0919+06, respectively. On the other hand, we found possible evidence that the pulsed emission of PSR B0628−28 is thermal. Two absorption lines at ~0.22 keV and ~0.44 keV are detected in the spectrum of PSR B1133+16. They are best interpreted as proton cyclotron features, implying the presence of multipolar components with a field of a few 1013 G at the neutron star polar caps. We discuss our results in the context of high-energy emission models of old rotation-powered pulsars.
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Jaskulska, Iwona, Kestutis Romaneckas, Dariusz Jaskulski, and Piotr Wojewódzki. "A Strip-Till One-Pass System as a Component of Conservation Agriculture." Agronomy 10, no. 12 (December 21, 2020): 2015. http://dx.doi.org/10.3390/agronomy10122015.
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Conservation agriculture has three main pillars, i.e., minimum tillage, permanent soil cover, and crop rotation. Covering the soil surface with plant residues and minimum mechanical soil disturbance can all result from introducing a strip-till one-pass (ST-OP) system. The aim of this study was to determine the impact of the ST-OP technology on the management of plant residues, soil properties, inputs, and emissions related to crop cultivation. We compared the effect of a ST-OP system against conventional tillage (CT) using a plough, and against reduced, non-ploughing tillage (RT). Four field experiments were conducted for evaluating the covering of soil with plant residues of the previous crop, soil loss on a slope exposed to surface soil runoff, soil structure and aggregate stability, occurrence of soil organisms and glomalin content, soil moisture and soil water reserve during plant sowing, labour and fuel inputs, and CO2 emissions. After sowing plants using ST-OP, 62.7–82.0% of plant residues remained on the soil surface, depending on the previous crop and row spacing. As compared with CT, the ST-OP system increased the stability of soil aggregates of 0.25–2.0 mm diameter by 12.7%, glomalin content by 0.08 g·kg−1, weight of earthworms five-fold, bacteria and fungi counts, and moisture content in the soil; meanwhile, it decreased soil loss by 2.57–6.36 t·ha−1 year−1, labour input by 114–152 min·ha−1, fuel consumption by 35.9–45.8 l·ha−1, and CO2 emissions by 98.7–125.9 kg·ha−1. Significant favourable changes, as compared with reduced tillage (RT), were also found with respect to the stability index of aggregates of 2.0–10.0 mm diameter, the number and weight of earthworms, as well as bacteria and fungi counts.
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Gulden, Robert H., Sylvain Lerat, Robert E. Blackshaw, Jeff R. Powell, David J. Levy-Booth, Kari E. Dunfield, Jack T. Trevors, K. Peter Pauls, John N. Klironomos, and Clarence J. Swanton. "Factors Affecting the Presence and Persistence of Plant DNA in the Soil Environment in Corn and Soybean Rotations." Weed Science 56, no. 5 (October 2008): 767–74. http://dx.doi.org/10.1614/ws-08-044.1.
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This study investigated factors that influence occurrence and persistence of plant DNA in the soil environment in three crop rotations. In each rotation, soil was sampled in May before planting, in July and August while crops were growing, and in October after harvest. Total DNA was recovered from soil samples taken at two different depths in the soil profile and quantified. Three target plant genes (cornCP4 epsps, corn10-kD Zein, and soybeanCP4 epsps) also were quantified in these DNA extracts using species-specific quantitative real-time PCR assays. In general, total plant DNA content in the soil environment was greatest when the crop was growing in the field and decreased rapidly after harvest. Nevertheless, low levels of target plant DNA were often still detectable the following spring. Age of rotation did not influence target DNA quantities found in the soil environment. Data were collected for a combination of 10 location-years, which allowed for estimation of the variance components for six factors including time of sampling, year, location, crop, sampling depth, and herbicide to total and target DNA content in the soil samples. Mean target recombinant DNA content in soil was influenced most strongly by time of sampling and year (85 and 6%, respectively), whereas total soil DNA content was less dynamic and was most strongly influenced by location and year (49 and 25%, respectively). Over the duration of this study, no accumulation of transgenic plant DNA in the soil environment was observed.
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Mallama, A., T. A. Clark, and J. W. Ryan. "Consistency of CDP and IRIS VLBI Earth orientation results." Symposium - International Astronomical Union 128 (1988): 187–92. http://dx.doi.org/10.1017/s0074180900119473.
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This study compares the earth orientation results obtained by the NASA CDP and the NGS IRIS experiments. The results agree at about one combined formal error (two milliarcseconds) after small biases (one to three milliarcseconds) have been removed from each component. Furthermore the biases are found to correspond to small rotations between the reference frames, principally the terrestrial frame, for the two sets of experiments. In the past the CDP data has not been used in combined solutions of earth orientation parameters prepared by the data centers at the U.S.N.O. and the B.I.H. The authors propose that these data should be included because they are distinct from the IRIS data and represent an important supplement to those data. We also point out that the total number of observations is about equal in the CDP and IRIS experiment sets.
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Saha, Bijan. "Spinor field with polynomial nonlinearity in LRS Bianchi type-I space–time." Canadian Journal of Physics 94, no. 1 (January 2016): 116–21. http://dx.doi.org/10.1139/cjp-2015-0574.
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Within the scope of the locally rotationally symmetric (LRS) Bianchi type-I cosmological model the role of spinor field on the evolution of the Universe is investigated. In doing so, we have considered a polynomial type of nonlinearity. It is found that, depending on the sign of the self-coupling constant, the model allows either an accelerated mode of expansion or an oscillatory mode of evolution. While the non-diagonal components of the energy–momentum tensor of the spinor field in the case of a full Bianchi type-I model lead to the vanishing mass and nonlinear term in the spinor field Lagrangian, in the case of an LRS Bianchi type-I model neither the mass term nor the nonlinear term of the spinor field vanish.
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STASIV, OLEH, OKSANA KACHMAR, OKSANA VAVRYNOVYCH, and OLEKSANDR DUBYTSKYI. "Effect of Fertiliser on Changes in Labile and Water-Soluble Forms of Humus in Short-Term Rotations." Scientific Horizons 25, no. 4 (2022): 9–17. http://dx.doi.org/10.48077/scihor.25(4).2022.9-17.
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Mobile (labile and water-soluble) forms of humus are one of the basic components of effective soil fertility and a precondition for high productivity of crop rotations. As a result of fermentation, these forms of humus are mineralised and take part in plant nutrition, and some of them, being included in mobilisation processes, transition into stable humus substances. Therefore, it is important to investigate agrotechnological factors for managing their dynamics and redistribution in the soil environment during the growing season of agricultural crops. The purpose of the study: to investigate the effect of complex application of mineral and organic (conventional and alternative) fertilisers on the change of water-soluble and labile forms of humus during the growing season of agricultural crops grown in short-term rotations. The following research methods were used in this study: field, laboratory-analytical, computational-comparative, mathematicalstatistical. Higher level of labile accumulation (359.59 mg kg-1 of soil) and water-soluble (11.69 mg kg-1 of soil) humus forms under winter wheat crops occur when the predecessor of the crop in the crop rotation is meadow clover. The application of N60P90K90 specifically for winter wheat and 40 t/ha of manure in the conventional fertilisation system of grain-grass crop rotation contributes to the formation of 529.07 and 20.20 mg kg-1 of soil of the organic substances under study. The application of N120P100K100 and 40 t/ha of manure for corn for grain yields 567.42 and 22.55 mg kg-1 of soil, and N90P90K90 and 40 t/ha of manure for potatoes yields 543.66 and 21.75 mg kg-1 of mobile compounds humus. The obtained research results can serve as a basis for the development of highly efficient environmentally friendly farming systems and can be used for further scientific research on the development of ways and directions for managing humus-forming processes in the soil environment
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Kite, Geoff. "Analysing Hydrometeorological Time Series for Evidence of Climatic Change." Hydrology Research 24, no. 2-3 (April 1, 1993): 135–50. http://dx.doi.org/10.2166/nh.1993.0018.
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Considerable scientific attention has been focused on a measured increase in atmospheric CO2 and a suspected corresponding change in climate. Such a change in climate, if it occurred, might be expected to have a magnified effect on hydrologic time series and, indeed, projections have been made of major changes in water resources. If the climatic changes are indeed magnified in hydrologic time series then, by detecting trends in such series, it should be possible to work backwards and identify the causative climatic change. This paper looks at two data sets: 1) long-term temperature, precipitation and streamflow data from sites across Canada and 2) long-term levels of large lakes in Africa and North America. The study assumes that time series may be modelled by trend, periodic, autoregressive and random residual components. The trend component of a time series is generally associated with changes in the structure of the time series caused by cumulative natural or manmade phenomena. Periodicities in natural time series are usually due to astronomical cycles such as the earth's rotation around the sun. Autoregressive components reflect the tendency for an event to be dependent on the magnitude of the previous event(s), a memory effect. The analyses of temperature, precipitation and streamflow data show some significant linear trends but no pattern is apparent. The analyses of longterm lake levels also identify linear trends but these are all explainable without invoking climate change due to greenhouse gases.
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Miao, Xiao‐Gui, Wooil M. Moon, and B. Milkereit. "A multioffset, three‐component VSP study in the Sudbury Basin." GEOPHYSICS 60, no. 2 (March 1995): 341–53. http://dx.doi.org/10.1190/1.1443770.
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A multioffset, three‐component vertical seismic profiling (VSP) experiment was carried out in the Sudbury Basin, Ontario, as a part of the LITHOPROBE Sudbury Transect. The main objectives were determination of the shallow velocity structure in the middle of the Sudbury Basin, development of an effective VSP data processing flow, correlation of the VSP survey results with the surface seismic reflection data, and demonstration of the usefulness of the VSP method in a crystalline rock environment. The VSP data processing steps included rotation of the horizontal component data, traveltime inversion for velocity analysis, Radon transform for wavefield separation, and preliminary analysis of shear‐wave data. After wavefield separation, the flattened upgoing wavefields for both P‐waves and S‐waves display consistent reflection events from three depth levels. The VSP-CDP transformed section and corridor stacked section correlate well with the high‐resolution surface reflection data. In addition to obtaining realistic velocity models for both P‐ and S‐waves through least‐square inversion and synthetic seismic modeling for the Chelmsford area, the VSP experiment provided an independent estimation for the reflector dip using three component hodogram analysis, which indicates that the dip of the contact between the Chelmsford and Onwatin formations, at an approximate depth of 380 m in the Chelmsford borehole, is approximately 10.5° southeast. This study demonstrates that multioffset, three‐component VSP experiments can provide important constraints and auxiliary information for shallow crustal seismic studies in crystalline terrain. Thus, the VSP technique bridges the gap between the surface seismic‐reflection technique and well‐log surveys.
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Wang, Fengzhu, Jizhong Wang, Yuxi Ji, Bo Zhao, Yangchun Liu, Hanlu Jiang, and Wenhua Mao. "Research on the Measurement Method of Feeding Rate in Silage Harvester Based on Components Power Data." Agriculture 13, no. 2 (February 7, 2023): 391. http://dx.doi.org/10.3390/agriculture13020391.
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For existing problems, such as the complex interactions between a crop and a machine, the measuring difficulty and the limited measurement precision of the feeding quantity within the corn silage harvester, a method of feeding rate measurement based on key conditions data, working data cleaning, and multiple variate regression is proposed. Non-destructive rotation speed, rotation torque, and power consumption sensors are designed for the key mechanical components. The data conditions, such as rotating speed, rotating torque, power consumption, hydraulic pressure, and hydraulic flow for the key operation of parts including cutting, feeding, shredding, and throwing are monitored and collected in real-time during field harvesting. The working data are screened and preprocessed, and the Mann-Kendall boundary extraction algorithm is applied, as is multiple component time lag correction analysis, and the Grubbs exception detection method. Based on a Pearson correlation analysis results, one-factor and multiple-factor regression models are respectively developed to achieve an accurate measurement of the corn feeding rate. The field validation tests show that the working data boundary extraction results among the load-stabilizing components such as shredding roller and throwing blower are highly reliable, with a correct rate of 100%. The power monitoring data of the shredding roller and throwing blowers are significantly correlated with the crop feeding rate, with a max correlation coefficient of 0.97. The determination coefficient of the single-factor feeding rate model based on the shredding roller reaches 0.94, and the maximum absolute error of the multi-factor feeding rate model is 0.58 kg/s. The maximum relative error is ±5.84%, providing technical and data support for the automatic measuring and intelligent tuning of the feeding quantity in a silage harvester.
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Herzog, Johanna, Florian Göttfert, Christian Maurer-Grubinger, Fabian Holzgreve, Gerhard Oremek, David A. Groneberg, and Daniela Ohlendorf. "Improvement of cervical spine mobility and stance stability by wearing a custom-made mandibular splint in male recreational athletes." PLOS ONE 17, no. 12 (December 15, 2022): e0278063. http://dx.doi.org/10.1371/journal.pone.0278063.
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Objectives The range of motion (ROM) of the cervical spine and postural stability are important for an economical and motorically adequate adaptation of the body to any situation. Therefore, this study aims to analyze whether these two components of postural and movement control can be influenced by means of a splint in a centric position compared to habitual occlusion. Methods 38 recreational male athletes volunteered. Cervical spine ROM was recorded using an ultrasound system and the a pressure measuring plate for postural stability (length of center of pressure (CoP) movement, area of CoP). The two dental occlusion conditions employed were the habitual occlusion and wearing a splint in an idealized, condylar position close to the centric position. Level of significance was set at ρ ≤ 0.05. Results The cervical spine mobility increased significantly by wearing the splint regarding rotation to the left (+3.9%) and right (+2.7%) and lateral flexion to the left (+4.4%) and right (+6.7%). Wearing the splint reduced the area of sway deflections by about 31.5% in the bipedal stance and by about 2.4% (left) and 28.2% (right) in the unipedal stance. The CoP trace was reduced in the sagittal plane by approximately 8.2% in the right single-leg stance. Conclusions The major findings seem to demonstrate that wearing a splint that keeps the jaw close to the centric relation may increase the cervical ROM and may improve balance stability in male recreational athletes. Changing the jaw relation in athletes can possibly aid the release of performance potentials by improving coordination skills.
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Wang, Rongyan, Zhian Zheng, Lei Gao, Andi Chen, Shanyu Wang, and Yiyao Xu. "Development and Testing of a Cam Disc Comb-Type Picking Machine for Chrysanthemum (Dendranthema morifolium Ramat. Tzvelev)." Transactions of the ASABE 64, no. 6 (2021): 1967–76. http://dx.doi.org/10.13031/trans.14347.
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HighlightsA practical cam disc comb-type chrysanthemum picking machine was developed.A three-dimensional model of the picking machine was designed in SolidWorks.The working principle and motion trajectory of the picking comb teeth were analyzed.The best working parameters of the picking machine were obtained with field tests.Abstract. Aiming at the problems of labor, picking efficiency, and mechanization, a small practical cam disc comb-type chrysanthemum picking machine was designed. The picking machine, mainly composed of a wheeled frame, power transmission system, cam disc, picking comb, and cleaning comb sleeve, uses the pulling force of comb teeth to pick chrysanthemum flowers. The comb teeth rotate on a central shaft, and their swing angle is determined by a groove on the cam disc. One rotation of the comb teeth completes the process of picking, lifting, and unloading. In this study, the parameters of the cam profile were designed using an analytical method. To ensure reliability of the components, the trajectory of the comb teeth and their structure and motion parameters were analyzed, and the conditions for picking chrysanthemums were determined. The physical parameters of chrysanthemum plants were measured, and a prototype picking machine was built. Field tests were conducted using the comb rotational speed, comb teeth spacing, and comb working depth as the test factors and the picking rate, impurity rate, breakage rate, and drop rate as the evaluation indexes. The effects of each factor and the interaction of any two factors on the picking effectiveness were obtained. The test results suggested that the most effective harvesting was achieved when the comb rotational speed was 40 rpm, the comb teeth spacing was 8 mm, and the comb working depth was 200 mm. With these parameters, the picking rate was 93.28%, the breakage rate was 1.21%, the impurity rate was 8.38%, and the drop rate was 6.61%. The prototype machine achieved good picking effectiveness, and this study provides a technical foundation for the realization of mechanized chrysanthemum harvesting. Keywords: Cam, Chrysanthemum, Comb teeth, Motion track, Picking machine.
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Galasyuk, I. N., and O. V. Mitina. "The Interaction of the Parent with the Young Child: Structure and Dynamics of Parental Responsiveness." Cultural-Historical Psychology 16, no. 4 (2020): 72–86. http://dx.doi.org/10.17759/chp.2020160408.
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The article presents a theoretical justification of the concept of Parental Responsiveness (PR) based on the cultural and historical concept, the activity paradigm and the results of an empirical study, the purpose of which is to operationalize the psychological construct of parental responsiveness and build an explanatory model of the dynamic functioning of parental responsiveness. The study involved 55 mothers with children between the ages of 2.4 and 3.3 years, developing within the norm. The method "Evaluation of child-parent interaction (ECPI)", which provides video surveillance, was used. The data was processed using the Observer XT-14 computer program. The Principal component analyses the method with orthogonal rotation Varimax was used to identify generalizing categories that characterize PR and allows describing their variations. As a result, there were 4 categories (scales) that determine the manifestation of responsiveness by the parent: Dominance, Apathy, Sensitivity, and Support. Their stability was shown in the process of parent-child interaction. A profile of parental responsiveness is constructed for each parent, which determines the extend of each scale when interacting with the child. The developed dynamic multidimensional autoregressive model of Parental Responsiveness allows us to evaluate the dynamics of parental behavior and determine the nature of the relationship between scales during the session.
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Tokarek, Travis W., Charles A. Odame-Ankrah, Jennifer A. Huo, Robert McLaren, Alex K. Y. Lee, Max G. Adam, Megan D. Willis, et al. "Principal component analysis of summertime ground site measurements in the Athabasca oil sands with a focus on analytically unresolved intermediate-volatility organic compounds." Atmospheric Chemistry and Physics 18, no. 24 (December 14, 2018): 17819–41. http://dx.doi.org/10.5194/acp-18-17819-2018.
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Abstract. In this paper, measurements of air pollutants made at a ground site near Fort McKay in the Athabasca oil sands region as part of a multi-platform campaign in the summer of 2013 are presented. The observations included measurements of selected volatile organic compounds (VOCs) by a gas chromatograph–ion trap mass spectrometer (GC-ITMS). This instrument observed a large, analytically unresolved hydrocarbon peak (with a retention index between 1100 and 1700) associated with intermediate-volatility organic compounds (IVOCs). However, the activities or processes that contribute to the release of these IVOCs in the oil sands region remain unclear. Principal component analysis (PCA) with varimax rotation was applied to elucidate major source types impacting the sampling site in the summer of 2013. The analysis included 28 variables, including concentrations of total odd nitrogen (NOy), carbon dioxide (CO2), methane (CH4), ammonia (NH3), carbon monoxide (CO), sulfur dioxide (SO2), total reduced-sulfur compounds (TRSs), speciated monoterpenes (including α- and β-pinene and limonene), particle volume calculated from measured size distributions of particles less than 10 and 1 µm in diameter (PM10−1 and PM1), particle-surface-bound polycyclic aromatic hydrocarbons (pPAHs), and aerosol mass spectrometer composition measurements, including refractory black carbon (rBC) and organic aerosol components. The PCA was complemented by bivariate polar plots showing the joint wind speed and direction dependence of air pollutant concentrations to illustrate the spatial distribution of sources in the area. Using the 95 % cumulative percentage of variance criterion, 10 components were identified and categorized by source type. These included emissions by wet tailing ponds, vegetation, open pit mining operations, upgrader facilities, and surface dust. Three components correlated with IVOCs, with the largest associated with surface mining and likely caused by the unearthing and processing of raw bitumen.
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Rauw, Gregor, and Yaël Nazé. "Similar but different: the varied landscape of Onfp/Oef stars variability." Monthly Notices of the Royal Astronomical Society 500, no. 2 (October 27, 2020): 2096–111. http://dx.doi.org/10.1093/mnras/staa3310.
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ABSTRACT The Oef category gathers rapidly rotating and evolved O-stars displaying a centrally reversed He ii λ 4686 emission line. The origin of the variability of their photospheric and wind spectral lines is debated, with rotational modulation or pulsations as the main contenders. To shed new light on this question, we analysed high-quality and high-cadence Transiting Exoplanet Survey Satellite photometric time series for five Oef stars. We also collected a new time series of spectra for one target (λ Cep) which had been the subject of specific debates in the last years. These observations reveal the variety of Oef behaviours. While space-based photometric data reveal substantial red noise components in all targets, only ζ Pup seems to display a long-lived periodicity. In our sample, stars exhibit a dominant signal at low frequencies but it appears relatively short-lived. This is reminiscent of rotational modulations by transient photospheric spots, though this scenario is challenged by the case of HD 14 442, whose 1.230 d−1 signal significantly exceeds the critical rotational frequency. In parallel, no evidence of persistent p mode non-radial pulsations is found in either photometry or spectroscopy of the stars, only temporary excitation of g mode pulsations could offer an alternative explanation for the dominant signals. Finally, the revised luminosities of the stars using GAIA-DR2 show that they are not all supergiants as ζ Pup. The question then arises whether the Oef peculiarity denotes a homogeneous class of objects after all.
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Kim, Hea-Ran, Min-Sun Jang, Yeong-Gyun Nam, Yun-Seok Kim, Sang-Sun Yang, Yong-Jin Kim, and Jae-Won Jeong. "Enhanced Permeability of Fe-Based Amorphous Powder Cores Realized through Selective Incorporation of Carbonyl Iron Powders at Inter-Particle Voids." Metals 11, no. 8 (July 30, 2021): 1220. http://dx.doi.org/10.3390/met11081220.
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In this study, we demonstrate a hybrid multimodal soft magnetic composite (SMC) comprising gas-atomized spherical amorphous powder (AP) and carbonyl-iron powder (CIP), and present its enhanced electromagnetic properties. CIP is selectively incorporated into voids between AP, and deforms during compression, effectively reducing the pores, resulting in high packing density of the core, where CIP magnetically bridges AP and helps magnetic domain rotation much efficiently. The hybrid SMC with the addition of 20 wt.% CIP showed constant effective permeability of 57 up to 1 MHz, a remarkable 63% increase compared with the AP core, while DC bias superimposing retention level of 61% was secured with the help of high magnetization of CIP. In addition, the effect of SiO2 surface insulation, prepared by the sol-gel process, on the high-frequency magnetic properties of hybrid SMCs, was also evaluated. It is thus revealed that the high-frequency dynamic loss of the hybrid core, originating from intra-particle eddy current loss and anomalous loss component, and inter-particle eddy currents are negligibly small. We believe that our approach using AP/CIP multimodal hybrid SMCs is an effective way of achieving high permeability as well as high DC bias characteristics at high frequencies. This process will be highly beneficial for the miniaturization of power inductors.
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Bolotina, Nadezhda B., Pavel N. Gavryushkin, Andrey V. Korsakov, Sergey V. Rashchenko, Yurii V. Seryotkin, Alexander V. Golovin, Bertrand N. Moine, Anatoly N. Zaitsev, and Konstantin D. Litasov. "Incommensurately modulated twin structure of nyerereite Na1.64K0.36Ca(CO3)2." Acta Crystallographica Section B Structural Science, Crystal Engineering and Materials 73, no. 2 (March 29, 2017): 276–84. http://dx.doi.org/10.1107/s2052520616020680.
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The incommensurately modulated twin structure of nyerereite Na1.64K0.36Ca(CO3)2has been first determined in the (3 + 1)-dimensional symmetry groupCmcm(α00)00swith modulation vectorq= 0.383a*. Unit-cell values area= 5.062 (1),b= 8.790 (1),c= 12.744 (1) Å. Three orthorhombic components are related by threefold rotation about [001]. Discontinuous crenel functions are used to describe the occupation modulation of Ca and some CO3groups. The strong displacive modulation of the O atoms in vertexes of such CO3groups is described using x-harmonics in crenel intervals. The Na, K atoms occupy mixed sites whose occupation modulation is described in two ways using either complementary harmonic functions or crenels. The nyerereite structure has been compared both with the commensurately modulated structure of K-free Na2Ca(CO3)2and with the widely known incommensurately modulated structure of γ-Na2CO3.
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Bonalumi, Davide, Antonio Giuffrida, and Federico Sicali. "Thermo-economic analysis of a supercritical CO2-based waste heat recovery system." E3S Web of Conferences 312 (2021): 08022. http://dx.doi.org/10.1051/e3sconf/202131208022.
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This work investigates the performance of a supercritical CO2 cycle as the bottoming cycle of a commercial gas turbine with 4.7 MW of electric power output. In detail, the partial heating cycle is the layout chosen for the interesting trade-off between heat recovery and cycle efficiency with a limited number of components. Single-stage radial turbomachines are selected according to the theory of similitude. In particular, the compressor is a troublesome turbomachine as it works near the critical point where significant variations of the CO2 properties occur. Efficiency values for turbomachinery are not fixed at first glance but result from actual size and running conditions, based on flow rates, enthalpy variations as well as rotational speeds. In addition, a limit is set for the machine Mach numbers in order to avoid heavily loaded turbomachinery. The thermodynamic study of the bottoming cycle is carried out by means of the mass and energy balance equations. A parametric analysis is carried out with particular attention to a number of specific parameters. Considering the power output calculated for the supercritical CO2 cycle, economic calculations are also carried out and the related costs compared to those specific of organic Rankine cycles with similar power output.
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MELERO, S., K. VANDERLINDEN, J. CARLOS RUIZ, and E. MADEJÓN. "Soil biochemical response after 23 years of direct drilling under a dryland agriculture system in southwest Spain." Journal of Agricultural Science 147, no. 1 (November 19, 2008): 9–15. http://dx.doi.org/10.1017/s0021859608008204.
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SUMMARYSoil enzyme activities are widely utilized as rapid and sensitive indicators in discriminating among soil management effects. The objective of the present study was to compare the influence of conservation tillage, i.e. direct drilling (DD) (residue cover is left on the soil surface)v. conventional tillage (CT), on soil chemical and biochemical properties in a crop rotation (cereals–sunflower–legumes) under dryland production in a semi-arid Mediterranean Vertisol after 23 years. A randomized experimental design was established. Soil biological status was evaluated by measuring of enzymatic activities (dehydrogenase, β-glucosidase, alkaline phosphatase and protease). Total organic carbon (TOC) contents were greater in soils managed by DD than those found by CT. Except for protease activity, enzymatic activity values were approximately 2-fold higher in soils under DD than in soils under CT. The β-glucosidase, alkaline phosphatase and dehydrogenase values showed a high correlation (fromr=0·481 tor=0·886,P⩽0·01) with TOC contents and they were correlated with each other (fromr=0·664 tor=0·923,P⩽0·01). The coefficient of variation of biochemical properties was higher than those of chemical properties in both treatments. Principal component analysis (PCA) showed that two principal components explained 58% and 20% of the total variability. The first principal component was influenced mostly by β-glucosidase, dehydrogenase and TOC, whereas the second was influenced by pH. The first component effectively differentiated managed soil under both agriculture practices. In general, long-term soil conservation management by DD in a dryland farming system improved the quality of this Vertisol by enhancing its organic matter content and biochemical activity.
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Greiner, Cherry, Stephanie Grainger, Samantha Farrow, Alena Davis, Jimmy L. Su, Matthew D. Saybolt, Robert Wilensky, Sean Madden, and Stephen T. Sum. "Robust quantitative assessment of collagen fibers with picrosirius red stain and linearly polarized light as demonstrated on atherosclerotic plaque samples." PLOS ONE 16, no. 3 (March 18, 2021): e0248068. http://dx.doi.org/10.1371/journal.pone.0248068.
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Collagen is an important component in maintaining structural integrity and functionality of tissues and is modulated in various biological processes. Its visualization and possible quantification using histopathological stains can be important for understanding disease progression or therapeutic response. Visualization of collagen fiber with the histological stain picrosirius red (PSR) is enhanced with polarized light and quantitative analysis is possible using circular polarizers. However, linear polarizers are more commonly available and easier to optically align. The objective of the present study is to demonstrate a novel image acquisition technique and analysis method using linearly polarized light. The proposed imaging technique is based on image acquisition at multiple slide rotation angles, which are co-registered to form a composite image used for quantitative analysis by pixel intensity or pixel counting. The technique was demonstrated on multiple human coronary samples with varying histopathologies and developed specifically to analyze cap collagen in atherosclerotic plaque. Pixel counting image analysis was found to be reproducible across serial tissue sections and across different users and sufficiently sensitive to detect differences in cap structural integrity that are likely relevant to prediction of rupture risk. The benefit of slide rotation angle under linear polarization to acquire images represents a feasible and practical implementation for expanding the general utility of PSR for quantitative analysis.
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Jiang, Qianjing, Zhiming Qi, Chandra A. Madramootoo, Ward Smith, Naeem A. Abbasi, and Tiequan Zhang. "Comparison of RZWQM2 and DNDC Models to Simulate Greenhouse Gas Emissions under Combined Inorganic/Organic Fertilization in a Subsurface-Drained Field." Transactions of the ASABE 63, no. 4 (2020): 771–87. http://dx.doi.org/10.13031/trans.13668.
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HighlightsRZWQM2 was compared with DNDC to predict greenhouse gas emissions.RZWQM2 was applied to simulate the greenhouse gas emissions under manure application.RZWQM2 performed better than DNDC in simulating soil water content and CO2 emissions.Abstract. N management has the potential to mitigate greenhouse gas (GHG) emissions. Process-based models are promising tools for evaluating and developing management practices that may optimize sustainability goals as well as promote crop productivity. In this study, the GHG emission component of the Root Zone Water Quality Model (RZWQM2) was tested under two different types of N management and subsequently compared with the Denitrification-Decomposition (DNDC) model using measured data from a subsurface-drained field with a corn-soybean rotation in southern Ontario, Canada. Field-measured data included N2O and CO2 fluxes, soil temperature, and soil moisture content from a four-year field experiment (2012 to 2015). The experiment was composed of two N treatments: inorganic fertilizer (IF), and inorganic fertilizer combined with solid cattle manure (SCM). Both models were calibrated using the data from IF and validated with SCM. Statistical results indicated that both models predicted well the soil temperature, but RZWQM2 performed better than DNDC in simulating soil water content (SWC) because DNDC lacked a heterogeneous soil profile, had shallow simulation depth, and lacked crop root density functions. Both RZWQM2 and DNDC predicted the cumulative N2O and CO2 emissions within 15% error under all treatments, while the timing of daily CO2 emissions was more accurately predicted by RZWQM2 (RMSE = 0.43 to 0.54) than by DNDC (RMSE = 0.60 to 0.67). Modeling results for N management effects on GHG emissions showed consistency with the field measurements, indicating higher CO2 emissions under SCM than IF, higher N2O emissions under IF in corn years, but lower N2O emissions in soybean years. Overall, RZWQM2 required more experienced and intensive calibration and validation, but it provided more accurate predictions of soil hydrology and better timing of CO2 emissions than DNDC. Keywords: CO2 emission, Corn-soybean rotation, Inorganic fertilization, Manure application, N2O emission, Process-based modeling.
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KUNIYOSHI, YASUO, RYO FUKANO, TAKUYA OTANI, TAKUMI KOBAYASHI, and NOBUYUKI OTSU. "HAPTIC DETECTION OF OBJECT AFFORDANCES BY A MULTI-FINGERED ROBOT HAND." International Journal of Humanoid Robotics 02, no. 04 (December 2005): 415–35. http://dx.doi.org/10.1142/s0219843605000600.
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This paper proposes a learning method for detecting object affordances through haptic exploration by a multi-fingered robot hand. Learning how to remove a screw cap from a bottle is the present target task. Assuming that coarse manipulation strategy is given by other methods, such as visual observation of a model task, the system applies coarse grabbing actions to the target object. In response to the exploratory actions, the object moves (rotates, in this case) along the physical constraint (screw). The robot detects the resulting motion through proprioception of the compliant fingers. A non-supervised statistical learning method is applied to categorize the resulting motion. The method is a combination of high-order local autocorrelation (HLAC), principal components analysis (PCA), and mean-shift clustering. Experiments with a real multi-fingered robot hand and bottle caps of different diameters confirm that the proposed method can detect and categorize rotational constraints.
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Papadopoulos, Y. A., M. A. Price, L. F. Laflamme, N. R. Fulton, G. M. Hunter, C. D. Caldwell, and K. B. McRae. "Differences among orchardgrass cultivars in response to hay and rotational grazing management." Canadian Journal of Plant Science 75, no. 1 (January 1, 1995): 147–57. http://dx.doi.org/10.4141/cjps95-024.
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This study was conducted to compare orchardgrass (Dactylis glomerata L.) cultivar performance under contrasting management systems (hay vs. rotational grazing) during the first two production years. The trial consisted of eight orchardgrass cultivars broadcast seeded in a randomized complete-block design, with three replications. The perimeter of each replication was fenced, and the area was divided into two sections. The first section was managed as a simulated hay production system. The second section was managed by simulating a rotational grazing system using crossbred ewes. Dry matter (DM) yield was determined before harvesting or grazing. Tiller density (TD) and leaf area index (LAI) were measured on four cultivars prior to harvesting and grazing. Excellent DM yield and persistence were obtained from all cultivars in both years under hay management but varied considerably under grazing management. Cultivar ranking according to DM yield under hay management was different from ranking based on performance under pasture management. One group of four cultivars had a decrease in yield of 19.9% in the second year of grazing, over the first year, but yield of the remaining group increased by 5.7% (SED = 9.83). Production of hay was similar for both groups. Early-maturing cultivars yielded 7% more DM and had higher crop growth rates (CGR), LAI and TD than late-maturing cultivars. Growth characteristics of orchardgrass cultivars as measured by DM yield, CGR, LAI and TD were modified by management practice. As a result, evaluating orchardgrass varieties under a hay management system was not effective in determining their performance under grazing. Key words:Dactylis glomerata, cultivar evaluation, cultivar development, grazing, yield, yield components
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Zhang, Quan, Huimin Lei, Dawen Yang, Lihua Xiong, Pan Liu, and Beijing Fang. "Decadal variation in CO<sub>2</sub> fluxes and its budget in a wheat and maize rotation cropland over the North China Plain." Biogeosciences 17, no. 8 (April 22, 2020): 2245–62. http://dx.doi.org/10.5194/bg-17-2245-2020.
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Abstract. Carbon sequestration in agroecosystems has great potential to mitigate global greenhouse gas emissions. To assess the decadal trend of CO2 fluxes of an irrigated wheat–maize rotation cropland over the North China Plain, the net ecosystem exchange (NEE) with the atmosphere was measured by using an eddy covariance system from 2005 to 2016. To evaluate the detailed CO2 budget components of this representative cropland, a comprehensive experiment was conducted in the full 2010–2011 wheat–maize rotation cycle by combining the eddy covariance NEE measurements, plant carbon storage samples, and a soil respiration experiment that differentiated between heterotrophic and below-ground autotrophic respirations. Over the past decade (from 2005 to 2016), the cropland exhibited a statistically nonsignificant decreasing carbon sequestration capacity; the average of total NEE, gross primary productivity (GPP), and ecosystem respiration (ER), respectively, were −364, 1174, and 810 gC m−2 for wheat and −136, 1008, and 872 gC m−2 for maize. The multiple regression revealed that air temperature and groundwater depth showed pronounced correlations with the CO2 fluxes for wheat. However, in the maize season, incoming shortwave radiation and groundwater depth showed pronounced correlations with CO2 fluxes. For the full 2010–2011 agricultural cycle, the CO2 fluxes for wheat and maize were as follows: for NEE they were −438 and −239 gC m−2, for GPP 1078 and 780 gC m−2, for ER 640 and 541 gC m−2, for soil heterotrophic respiration 377 and 292 gC m−2, for below-ground autotrophic respiration 136 and 115 gC m−2, and for above-ground autotrophic respiration 128 and 133 gC m−2. The net biome productivity was 59 gC m−2 for wheat and 5 gC m−2 for maize, indicating that wheat was a weak CO2 sink and maize was close to CO2 neutral to the atmosphere for this agricultural cycle. However, when considering the total CO2 loss in the fallow period, the net biome productivity was −40 gC m−2 yr−1 for the full 2010–2011 cycle, implying that the cropland was a weak CO2 source. The investigations of this study showed that taking cropland as a climate change mitigation tool is challenging and that further studies are required for the CO2 sequestration potential of croplands.
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Jaradat, Abdullah A. "Covariance Structures in Conventional and Organic Cropping Systems." International Journal of Agronomy 2013 (2013): 1–8. http://dx.doi.org/10.1155/2013/494026.
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Guidelines are needed to develop proper statistical analyses procedures and select appropriate models of covariance structures in response to expected temporal variation in long-term experiments. Cumulative yield, its temporal variance, and coefficient of variation were used in estimating and describing covariance structures in conventional and organic cropping systems of a long-term field experiment in a randomized complete block design. An 8-year database on 16 treatments (conventional and organic cropping systems, crop rotations, and tillage) was subjected to geostatistical, covariance structure, variance components, and repeated measures multivariate analyses using six covariance models under restricted maximum likelihood. Differential buildup of the cumulative effects due to crop rotations being repeated over time was demonstrated by decreasing structured and unstructured variances and increasing range estimates in the geostatistical analyses. The magnitude and direction of relationships between cumulative yield and its temporal variance, and coefficient of variation shaped the covariance structures of both cropping systems, crop rotations, and phases within crop rotations and resulted in significant deviations of organic management practices from their conventional counterparts. The unstructured covariance model was the best to fit most factor-variable combinations; it was the most flexible, but most costly in terms of computation time and number of estimated parameters.
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Mazur, Piotr, Dariusz Gozdowski, Wojciech Stępień, and Elżbieta Wójcik-Gront. "Does Drone Data Allow the Assessment of Phosphorus and Potassium in Soil Based on Field Experiments with Winter Rye?" Agronomy 13, no. 2 (February 2, 2023): 446. http://dx.doi.org/10.3390/agronomy13020446.
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The evaluation of the nutrient content in the soil, such as potassium and phosphorus, is very important, especially in precision agriculture, where the fertilizer rate should be adjusted to field variability in terms of nutrient content. Soil chemical analysis is time-consuming and expensive, and dense soil sampling is not always possible. In recent years, remote sensing methods have been used to assess the within-field variability of soil and crop nutritional status. The main aim of this study was to evaluate the relationship between UAV-derived spectral reflectance for winter rye in a long-term experiment for different fertilization with phosphorus and potassium. The study was conducted in 2022 in two field experiments in which winter rye was cultivated in monoculture and with crop rotation. The experiments were located in central Poland in Skierniewice. Statistical analyses were performed using univariate and multivariate methods, e.g., analysis of correlation, regression, and principal component analysis (PCA). The effect of phosphorus and potassium fertilization on the UAV-derived spectral reflectance of winter rye was weak, weaker in comparison to the effect of nitrogen fertilization. The effect of phosphorus and potassium fertilization on spectral reflectance was stronger in the experiment with monoculture than in the experiment with crop rotation. On the basis of correlation coefficients and PCA, negative relationships were proven between available soil potassium and spectral reflectance in the range of blue, green, and red bands and positive with red edge and near-infrared bands. The first principal component (PC1) was very strongly correlated with almost all spectral bands, either positively or negatively. The correlation of potassium and phosphorus content was very weak with PC1 in the experiment with crop rotation, while in the experiment with rye monoculture, the correlation was slightly stronger, indicating a stronger effect of nutrient deficiency in monoculture.
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Ding, Zhengliang, Shaochun Ma, Jing Bai, Wenpeng Liang, and Xiadong Zhang. "Optimization Design and Test of Spike-Toothed Crop Divider." Agriculture 12, no. 10 (October 14, 2022): 1692. http://dx.doi.org/10.3390/agriculture12101692.
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The crop divider is a crucial component of the sugarcane chopper harvester that has an important effect on the lifting performance of lodged sugarcanes. However, tropical weather and climate result in severe sugarcane lodging, which seriously hinders the sugarcane lifting process. To improve the lifting performance of crop dividers, a variable-spiral spike-toothed crop divider was designed. Some structural parameters of the bench test were designed. In this study, the forward speed, the rotational speed of the scrolls, and the installation angle of the scrolls were selected as test factors and the lifting angle of the sugarcane was selected as the test index. Based on a single-factor test, we found the optimum range of these test factors: a forward speed of 0.4~0.8 m/s, a rotational speed of the inside scrolls of 100~140 r/min, and an installation angle of the inside scrolls of 55°~65°. An orthogonal test was conducted to identify the relationships of test index and test factors. The regression model was obtained by fitting the test data and the response surface was established to analysis the interaction of test factors. According to Design Expert 8.0.6, the optimal factor combination of parameters was: a forward speed was 0.74 m/s, a rotational speed of the inside scrolls of 134 r/min, and an installation angle of the inside scrolls of 63.5°. Finally, the regression model was verified by the bench test. The relative error of the regression model of the lifting angle was 4.94%, which showed that the regression model was reliable. This study is expected to provide valuable references for the design and improvement of crop dividers.