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1
Antos, Piotr, Tomasz Piechowiak, Krzysztof Tereszkiewicz, and Maciej Balawejder. "Utilization of Ozone for the Improvement of Mentha piperita L. Quality by Reduction of Microbial Load and Impact of the Process on the Herb Properties." Acta Universitatis Cibiniensis. Series E: Food Technology 24, no. 2 (December 1, 2020): 156–64. http://dx.doi.org/10.2478/aucft-2020-0014.
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Abstract Herbs can be contaminated with microorganisms, which affects their quality while increasing the risk of food poisoning. Thus, there is a need for efficient decontamination techniques. In this study, the microbial load was reduced in peppermint herb (Mentha piperita L.) exposed to ozone at 10 ppm for 60 minutes. The quality of the ozonated herb was assessed by the determination of microbial load and essential oils content. Total microbial content was reduced by 4 log cfu g−1 of the microorganisms whereas the contamination with molds was reduced from 10.07 log cfu g−1 of the microorganisms to zero. Moreover, sensory evaluation of the herb aroma was conducted. These characteristics were not significantly affected by the treatment. Therefore, ozone can be used to improve the peppermint herb quality by reduction of the microbial contamination of peppermint herb while having no adverse effect on the herb aroma.
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Yi, Yonghong, John S. Kimball, Richard H. Chen, Mahta Moghaddam, and Charles E. Miller. "Sensitivity of active-layer freezing process to snow cover in Arctic Alaska." Cryosphere 13, no. 1 (January 23, 2019): 197–218. http://dx.doi.org/10.5194/tc-13-197-2019.
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Abstract. The contribution of cold-season soil respiration to the Arctic–boreal carbon cycle and its potential feedback to the global climate remain poorly quantified, partly due to a poor understanding of changes in the soil thermal regime and liquid water content during the soil-freezing process. Here, we characterized the processes controlling active-layer freezing in Arctic Alaska using an integrated approach combining in situ soil measurements, local-scale (∼50 m) longwave radar retrievals from NASA airborne P-band polarimetric SAR (PolSAR) and a remote-sensing-driven permafrost model. To better capture landscape variability in snow cover and its influence on the soil thermal regime, we downscaled global coarse-resolution (∼0.5∘) MERRA-2 reanalysis snow depth data using finer-scale (500 m) MODIS snow cover extent (SCE) observations. The downscaled 1 km snow depth data were used as key inputs to the permafrost model, capturing finer-scale variability associated with local topography and with favorable accuracy relative to the SNOTEL site measurements in Arctic Alaska (mean RMSE=0.16 m, bias=-0.01 m). In situ tundra soil dielectric constant (ε) profile measurements were used for model parameterization of the soil organic layer and unfrozen-water content curve. The resulting model-simulated mean zero-curtain period was generally consistent with in situ observations spanning a 2∘ latitudinal transect along the Alaska North Slope (R: 0.6±0.2; RMSE: 19±6 days), with an estimated mean zero-curtain period ranging from 61±11 to 73±15 days at 0.25 to 0.45 m depths. Along the same transect, both the observed and model-simulated zero-curtain periods were positively correlated (R>0.55, p<0.01) with a MODIS-derived snow cover fraction (SCF) from September to October. We also examined the airborne P-band radar-retrieved ε profile along this transect in 2014 and 2015, which is sensitive to near-surface soil liquid water content and freeze–thaw status. The ε difference in radar retrievals for the surface (∼<0.1 m) soil between late August and early October was negatively correlated with SCF in September (R=-0.77, p<0.01); areas with lower SCF generally showed larger ε reductions, indicating earlier surface soil freezing. On regional scales, the simulated zero curtain in the upper (<0.4 m) soils showed large variability and was closely associated with variations in early cold-season snow cover. Areas with earlier snow onset generally showed a longer zero-curtain period; however, the soil freeze onset and zero-curtain period in deeper (>0.5 m) soils were more closely linked to maximum thaw depth. Our findings indicate that a deepening active layer associated with climate warming will lead to persistent unfrozen conditions in deeper soils, promoting greater cold-season soil carbon loss.
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Hui, Zhenzhen, Xuzhong Zuo, Longqiang Ye, Xuchun Wang, and Xuebin Zhu. "Solution Processable CrN Thin Films: Thickness-Dependent Electrical Transport Properties." Materials 13, no. 2 (January 16, 2020): 417. http://dx.doi.org/10.3390/ma13020417.
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Thickness is a very important parameter with which to control the microstructures, along with physical properties in transition-metal nitride thin films. In work presented here, CrN films with different thicknesses (from 26 to 130 nm) were grown by chemical solution deposition. The films are pure phase and polycrystalline. Thickness dependence of microstructures and electrical transport behavior were studied. With the increase of films thickness, grain size and nitrogen content are increased, while resistivity, zero-field sensitivity and magnetoresistance are decreased. In the temperature range of 5–350 K, all samples exhibited semiconductor-like properties with dρ/dT < 0. For the range above and below the Néel temperature, the resistivity can be fitted by the thermal activation model and the two-dimensional weak localization (2D-WL) model, respectively. The ultra-low magnetoresistance at a low temperature under high magnetic fields with a large zero-field sensitivity was observed in the CrN thin films. The zero-field sensitivity can be effectively tuned to 10−2 K−1 at 5 K with a magnetoresistance of less than 1% at 2 K under 14 T by reasonably controlling the thickness.
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Lee, Suhyeon, Junhyuk Hyun, Hongje Seong, and Euntai Kim. "Unsupervised Domain Adaptation for Semantic Segmentation by Content Transfer." Proceedings of the AAAI Conference on Artificial Intelligence 35, no. 9 (May 18, 2021): 8306–15. http://dx.doi.org/10.1609/aaai.v35i9.17010.
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In this paper, we tackle the unsupervised domain adaptation (UDA) for semantic segmentation, which aims to segment the unlabeled real data using labeled synthetic data. The main problem of UDA for semantic segmentation relies on reducing the domain gap between the real image and synthetic image. To solve this problem, we focused on separating information in an image into content and style. Here, only the content has cues for semantic segmentation, and the style makes the domain gap. Thus, precise separation of content and style in an image leads to effect as supervision of real data even when learning with synthetic data. To make the best of this effect, we propose a zero-style loss. Even though we perfectly extract content for semantic segmentation in the real domain, another main challenge, the class imbalance problem, still exists in UDA for semantic segmentation. We address this problem by transferring the contents of tail classes from synthetic to real domain. Experimental results show that the proposed method achieves the state-of-the-art performance in semantic segmentation on the major two UDA settings.
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Emerson, WW. "Water-retention, organic-C and soil texture." Soil Research 33, no. 2 (1995): 241. http://dx.doi.org/10.1071/sr9950241.
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Samples taken from the two textural phases of the surface soil of an irrigated natrixeralf and its clay subsoil were dried at wilting point and in air. Water retention increased linearly with C content, with values extrapolated to zero C content proportional to clay content. Emerson et al. (1994) (Aust. J. Soil Res., 32, 939-51) had already shown that water held by the surface samples at 10 kPa suction increased approximately linearly with C content, independently of clay content. Similar linear relations were deduced for other soils using values of field capacity and wilting point reported in the literature. A constant amount of water is considered to be held by portions of the silt/clay matrix. As the C content of the soil is increased, polysaccharide gels gradually fill additional 1-3 �m wide pores within the portions. It was calculated that, after a long period in grass, gel present increases available water on a weight basis, by 34% and 125% in loamy sand and sandy clay A horizons respectively. Where farmyard manure (FYM) was incorporated, gel only formed from the added C. Nevertheless the large increase in field capacity of a sandy loam produced by rotavation was temporarily preserved by prior addition of FYM. It is suggested that the gel here was mainly on microbial filaments.
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Kurzban, Robert, Amber Dukes, and Jason Weeden. "Sex, drugs and moral goals: reproductive strategies and views about recreational drugs." Proceedings of the Royal Society B: Biological Sciences 277, no. 1699 (June 16, 2010): 3501–8. http://dx.doi.org/10.1098/rspb.2010.0608.
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Humans, unlike most other species, show intense interest in the activities of conspecifics, even when the activities in question pose no obvious fitness threat or opportunity. Here, we investigate one content domain in which people show substantial interest, the use of drugs for non-medical purposes. Drawing from two subject populations—one undergraduate and one Internet-based—we look at the relationships among (i) abstract political commitments; (ii) attitudes about sexuality; and (iii) views surrounding recreational drugs. Whereas some theories suggest that drug views are best understood as the result of abstract political ideology, we suggest that these views can be better understood in the context of reproductive strategy. We show that, as predicted by a strategic construal, drug attitudes are best predicted by sexual items rather than abstract political commitments and, further, that the relationship between factors such as political ideology and drugs, while positive, are reduced to zero or nearly zero when items assessing sexuality are controlled for. We conclude that considering morality from the standpoint of strategic interests is a potentially useful way to understand why humans care about third party behaviour.
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Johnson, Gregory C., Sabine Mecking, Bernadette M. Sloyan, and Susan E. Wijffels. "Recent Bottom Water Warming in the Pacific Ocean*." Journal of Climate 20, no. 21 (November 1, 2007): 5365–75. http://dx.doi.org/10.1175/2007jcli1879.1.
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Abstract Decadal changes of abyssal temperature in the Pacific Ocean are analyzed using high-quality, full-depth hydrographic sections, each occupied at least twice between 1984 and 2006. The deep warming found over this time period agrees with previous analyses. The analysis presented here suggests it may have occurred after 1991, at least in the North Pacific. Mean temperature changes for the three zonal and three meridional hydrographic sections analyzed here exhibit abyssal warming often significantly different from zero at 95% confidence limits for this time period. Warming rates are generally larger to the south, and smaller to the north. This pattern is consistent with changes being attenuated with distance from the source of bottom water for the Pacific Ocean, which enters the main deep basins of this ocean southeast of New Zealand. Rough estimates of the change in ocean heat content suggest that the abyssal warming may amount to a significant fraction of upper World Ocean heat gain over the past few decades.
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Schnitzenlehner, S., and A. Essl. "Field data analysis of cytoplasmic inheritance of dairy and fitness-related traits in cattle." Animal Science 68, no. 3 (April 1999): 459–66. http://dx.doi.org/10.1017/s1357729800050463.
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AbstractField data of the Austrian Simmental population were analysed using restricted maximum likelihood (REML) with an animal model where additive direct, additive maternal and cytoplasmic effects were treated as random and the effect of the year of first calving as fixed. Traits analysed were milk yield, fat and protein content, persistency, days open and herd life. All dairy traits were pre-adjusted for best linear unbiased prediction (BLUP) herd-year effects, milk yield additionally for season, age at first calving and days open. After applying specific data restrictions, the number of records for the various traits ranged from 3360 to 51889. Identification of cow lineages was based on pedigree information from the official milk recording scheme, with a span of at least four and up to 16 generations. The number of lineages per trait varied and ranged from 484 to 3195, with an average size of 15 members (for herd life 7). Evaluations of the relevant variance components for the dairy and fitness-related traits investigated were separate for the first three lactations.The estimated variance components for cytoplasmic effects were close to zero for all dairy traits with the exception of first lactation milk yield, where a significant value of 2.0% of the total phenotypic variance was found. Significant contributions of cytoplasmic lineages to total variance in all lactations, however, were estimated for persistency (2·6 to 3.8%), days open (1·8 to 2.9%) and for both true and functional herd life (4.6% each). The portions of additive maternal variance and covariance between additive direct and additive maternal effects on total variance were very close to zero for all traits investigated. The maximum differences between BLUP lineage effects were 373 kg for first lactation milk yield, 44 days for days open (first lactation), 1·6 and 2·8 years for true and functional herd life and, on average, 1·0 kg for standard deviation of test day milk yields (persistency) of the first three lactations.Removing the cytoplasmic effect from the model led to increased estimates of the additive direct heritability. Further model aspects such as interaction between additive and cytoplasmic gene effects and possible confounding between cytoplasmic and herd effects are discussed.
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Chafe, Wallace. "Things We Can Learn From Repeated Tellings of the Same Experience." Narrative Inquiry 8, no. 2 (January 1, 1998): 269–85. http://dx.doi.org/10.1075/ni.8.2.03cha.
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The study of repeated tellings of the same experience by the same speaker has been a neglected source of insights into the human mind. The content of the mind (here termed underlying experience) cannot be equated with any particular verbalization of it. Language, mental imagery, and emotions provide different windows on it, but the very fact that repeated tellings differ shows that language is not in any one-to-one relation with it. The comparison of such tellings can, however, allow us to zero in on the nature of underlying experience by showing what is constant and what variable. Such comparisons suggest that experience is stored in terms of relatively large topics and relatively small foci that are activated, one at a time, as a topic is scanned. They suggest, too, that decisions regarding sentence boundaries are made as one is talking, so that sentences appear not to reflect units of memory. Whereas ideas of events and their participants show stability, the orientations to such ideas that are expressed by the inflectional elements of language are free to vary. The relative importance of ideas may be inferred from their constancy across repetitions. Chronology appears to be important when it is a relevant relation between ideas, but when it is not relevant there is room for random ordering. These points will be illustrated with a comparison of two tellings that were produced fifteen months apart. (Narrative Structure, Memory)
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Bang, Arti V., Radhika G. Purandare, and Archana K. Ratnaparkhi. "An algorithm for enhancement of audio content classification." Bulletin of Electrical Engineering and Informatics 12, no. 4 (August 1, 2023): 2262–68. http://dx.doi.org/10.11591/beei.v12i4.3663.
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Presently, fast proliferation of information enforces novel challenges on content management. Further, computerized audio classification along-with content description is considered as valuable method to manage audio contents. In general, classification involves two steps. First, is the processing of accessible data in economical ways to deliver explanatory features. Second is how accurate features of undetermined tests is evaluated to choose classifier. In this paper, k-neighbor algorithm with machine learning is proposed for feature extraction as well as content classification/description. This algorithm enhances Quality of Service parameters of classifiers. Here, development of training as well as testing data set is developed to increase the classifier accuracy. A test engine set-up bed using simulation tool MATLAB is designed to estimate the implementation performance of the algorithm. A range of features are studied to evaluate effectiveness in terms of accuracy, zero crossing rate (ZCR) and spectral roll frequency. From the experimentation results, it is observed that the proposed algorithm can achieve accuracy of 95.8% for 2 sec window length as compare with k-neighbor algorithm. A total enhancement of 11% is achieved with cross validation error of 29.6. A superior assortment of training fabric to extract few additional useful features can enhance accuracy further.
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Bang, Arti V., Radhika G. Purandare, and Archana K. Ratnaparkhi. "An algorithm for enhancement of audio content classification." Bulletin of Electrical Engineering and Informatics 12, no. 4 (August 1, 2023): 2262–68. http://dx.doi.org/10.11591/eei.v12i4.3663.
Full textAbstract:
Presently, fast proliferation of information enforces novel challenges on content management. Further, computerized audio classification along-with content description is considered as valuable method to manage audio contents. In general, classification involves two steps. First, is the processing of accessible data in economical ways to deliver explanatory features. Second is how accurate features of undetermined tests is evaluated to choose classifier. In this paper, k-neighbor algorithm with machine learning is proposed for feature extraction as well as content classification/description. This algorithm enhances Quality of Service parameters of classifiers. Here, development of training as well as testing data set is developed to increase the classifier accuracy. A test engine set-up bed using simulation tool MATLAB is designed to estimate the implementation performance of the algorithm. A range of features are studied to evaluate effectiveness in terms of accuracy, zero crossing rate (ZCR) and spectral roll frequency. From the experimentation results, it is observed that the proposed algorithm can achieve accuracy of 95.8% for 2 sec window length as compare with k-neighbor algorithm. A total enhancement of 11% is achieved with cross validation error of 29.6. A superior assortment of training fabric to extract few additional useful features can enhance accuracy further.
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Klöwer, Milan, Miha Razinger, Juan J. Dominguez, Peter D. Düben, and Tim N. Palmer. "Compressing atmospheric data into its real information content." Nature Computational Science 1, no. 11 (November 2021): 713–24. http://dx.doi.org/10.1038/s43588-021-00156-2.
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AbstractHundreds of petabytes are produced annually at weather and climate forecast centers worldwide. Compression is essential to reduce storage and to facilitate data sharing. Current techniques do not distinguish the real from the false information in data, leaving the level of meaningful precision unassessed. Here we define the bitwise real information content from information theory for the Copernicus Atmospheric Monitoring Service (CAMS). Most variables contain fewer than 7 bits of real information per value and are highly compressible due to spatio-temporal correlation. Rounding bits without real information to zero facilitates lossless compression algorithms and encodes the uncertainty within the data itself. All CAMS data are 17× compressed relative to 64-bit floats, while preserving 99% of real information. Combined with four-dimensional compression, factors beyond 60× are achieved. A data compression Turing test is proposed to optimize compressibility while minimizing information loss for the end use of weather and climate forecast data.
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Libman, Daniel, Gil Ariel, Mary Schaps, and Simi Haber. "Mutual Information between Order Book Layers." Entropy 24, no. 3 (February 27, 2022): 343. http://dx.doi.org/10.3390/e24030343.
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The order book is a list of all current buy or sell orders for a given financial security. The rise of electronic stock exchanges introduced a debate about the relevance of the information it encapsulates of the activity of traders. Here, we approach this topic from a theoretical perspective, estimating the amount of mutual information between order book layers, i.e., different buy/sell layers, which are aggregated by buy/sell orders. We show that (i) layers are not independent (in the sense that the mutual information is statistically larger than zero), (ii) the mutual information between layers is small (compared to the joint entropy), and (iii) the mutual information between layers increases when comparing the uppermost layers to the deepest layers analyzed (i.e., further away from the market price). Our findings, and our method for estimating mutual information, are relevant to developing trading strategies that attempt to utilize the information content of the limit order book.
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Stibal, Marek, Emily C. Lawson, Grzegorz P. Lis, Ka Man Mak, Jemma L. Wadham, and Alexandre M. Anesio. "Organic matter content and quality in supraglacial debris across the ablation zone of the Greenland ice sheet." Annals of Glaciology 51, no. 56 (2010): 1–8. http://dx.doi.org/10.3189/172756411795931958.
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AbstractQuantifying the biogeochemical cycling of carbon in glacial ecosystems is of great significance for regional, and potentially global, carbon flow estimations. The concentration and quality of organic carbon (OC) is an important indicator of biogeochemical and physical processes that prevail in an ice-sheet ecosystem. Here we determine the content and quality of OC in debris from the surface of the Greenland ice sheet (GrIS) using microscopic, chromatographic, spectrophotometric and high-temperature combustion techniques. The total OC content in the debris increased with distance from the edge of the ice sheet, from virtually zero to >6% dry weight at 50 km inland, and there was a peak in the carbohydrate proportion and the microbial abundance at ∼6km inland. The highest (galactose + mannose)/(arabinose + xylose) ratios, indicating maximum autochthonous microbial production, were found at >10km inland. We propose that three key processes influence the carbon cycling on the GrIS: aeolian input of microbial inoculum and nutrients, in situ biological C transformation and the wash-away of supraglacial debris by meltwaters. We show that all these processes have significant spatial variability. While the total OC content of the debris on the ice sheet is probably controlled by the physical processes of wind transport and wash-away by meltwater, the microbial abundance and the quantity of the labile cell-contained OC within the debris is likely to be driven by the balance between the wash-away and the microbial productivity.
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Shishkina, Viktoriya, Andrey Kostin, Artem Volodkin, Vera Samoilova, Igor Buchwalow, Markus Tiemann, and Dmitri Atiakshin. "The Remodeling of Dermal Collagen Fibrous Structures in Mice under Zero Gravity: The Role of Mast Cells." International Journal of Molecular Sciences 24, no. 3 (January 18, 2023): 1939. http://dx.doi.org/10.3390/ijms24031939.
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Mechanisms of adaptive rearrangements of the fibrous extracellular matrix of connective tissues under microgravity practically remain unexplored, despite the most essential functions of the stroma existing to ensure the physiological activity of internal organs. Here we analyzed the biomaterial (the skin dermis) of C57BL/6J mice from the Rodent Research-4 experiment after a long stay in space flight. The biomaterial was fixed onboard the International Space Station. It was found that weightlessness resulted in a relative increase in type III collagen-rich fibers compared to other fibrous collagens in the skin. The number of mast cells in the skin did not change, but their secretory activity increased. At the same time, co-localization of mast cells with fibroblasts, as well as impregnated fibers, was reduced. Potential molecular–cellular causes of changes in the activity of fibrillogenesis under zero-gravity conditions and the slowdown of the polymerization of tropocollagen molecules into supramolecular fibrous structures, as well as a relative decrease in the number of fibrous structures with a predominant content of type-I collagen, are discussed. The data obtained evidence of the different sensitivity levels of the fibrous and cellular components of a specific tissue microenvironment of the skin to zero-gravity conditions. The obtained data should be taken into account in the systematic planning of long-term space missions in order to improve the prevention of undesirable effects of weightlessness.
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Kabiesz, Jarosław, and Robert Kubica. "Optimizing the Recovery of Latent Heat of Condensation from the Flue Gas Stream through the Combustion of Solid Biomass with a High Moisture Content." Energies 17, no. 7 (April 1, 2024): 1670. http://dx.doi.org/10.3390/en17071670.
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This study focuses on a specific method of heat recovery in combustion systems especially dedicated to wet biomass. Solid biofuels such as woodchips or bark are sources of renewable energy, a substitute of fossil fuels, of dynamically growing importance due to the energy transformation towards a zero-emission economy. Various solutions are generally known, in particular those based on absorption and compressor heat pumps. The solution presented here eliminates the need for such expensive equipment while maintaining very high efficiency. It involves a system of several suitably configured scrubbers. Chemcad 8 simulation shows how the fluid flow rates affect the efficiency of the proposed solution. Optimal configuration of the system and adjustment of the process parameters (flow rates of water in scrubbers circuits) result in a thermal efficiency as high as 108.2%, close to the maximum theoretically achievable efficiency (111%). The system was compared with other existing solutions for efficiency. The performance of the system was examined under different operating conditions to determine the optimum. The effect of an increased fuel moisture content on efficiency was determined. It was shown that the key to achieving significant cost benefits for such a solution is to optimise the flow rates of the circulating fluids.
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Dvorkin, Jack, Amos Nur, and Caren Chaika. "Stress sensitivity of sandstones." GEOPHYSICS 61, no. 2 (March 1996): 444–55. http://dx.doi.org/10.1190/1.1443972.
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Our observations made on dry‐sandstone ultrasonic velocity data relate to the variation in velocity (or modulus) with effective stress, and the ability to predict a velocity for a rock under one effective pressure when it is known only under a different effective pressure. We find that the sensitivity of elastic moduli, and velocities, to effective hydrostatic stress increases with decreasing porosity. Specifically, we calculate the difference between an elastic modulus, [Formula: see text], of a sample of porosity ϕ at effective pressure [Formula: see text] and the same modulus, [Formula: see text], at effective pressure [Formula: see text]. If this difference, [Formula: see text], is plotted versus porosity for a suite of samples, then the scatter of ΔM is close to zero as porosity approaches the critical porosity value, and reaches its maximum as porosity approaches zero. The dependence of this scatter on porosity is close to linear. Critical porosity here is the porosity above which rock can exist only as a suspension—between 36% and 40% for sandstones. This stress‐sensitivity pattern of grain‐supported sandstones (clay content below 0.35) practically does not depend on clay content. In practical terms, the uncertainty of determining elastic moduli at a higher effective stress from the measurements at a lower effective stress is small at high porosity and increases with decreasing porosity. We explain this effect by using a combination of two heuristic models—the critical porosity model and the modified solid model. The former is based on the observation that the elastic‐modulus‐versus‐porosity relation can be approximated by a straight line that connects two points in the modulus‐porosity plane: the modulus of the solid phase at zero porosity and zero at critical porosity. The second one reflects the fact that at constant effective stress, low‐porosity sandstones (even with small amounts of clay) exhibit large variability in elastic moduli. We attribute this variability to compliant cracks that hardly affect porosity but strongly affect the stiffness. The above qualitative observation helps to quantitatively constrain P‐ and S‐wave velocities at varying stresses from a single measurement at a fixed stress. We also show that there are distinctive linear relations between Poisson’s ratios (ν) of sandstone measured at two different stresses. For example, in consolidated medium‐porosity sandstones [Formula: see text], where the subscripts indicate hydrostatic stress in MPa. Linear functions can also be used to relate the changes (with hydrostatic stress) in shear moduli to those in compressional moduli. For example, [Formula: see text], where [Formula: see text] is shear modulus and [Formula: see text] is compressional modulus, both in GPa, and the subscripts indicate stress in MPa.
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Hamad, Amar Ali Adam, Lixiao Ni, Hiba Shaghaleh, Elsayed Elsadek, and Yousef Alhaj Hamoud. "Effect of Carbon Content in Wheat Straw Biochar on N2O and CO2 Emissions and Pakchoi Productivity Under Different Soil Moisture Conditions." Sustainability 15, no. 6 (March 14, 2023): 5100. http://dx.doi.org/10.3390/su15065100.
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Agricultural soils are a primary source of greenhouse gas (GHG) emissions. Biochar is commonly used as a soil amendment to prevent climate change by reducing GHG production, increasing soil carbon storage, improving soil moisture retention, and enhancing crop productivity. However, the impact of biochar’s carbon content under subsurface drip irrigation (SDI) has not been well studied. Here, we investigated the effect of different carbon (C) contents in wheat biochar under different SDI depths on soil nitrous oxide (N2O), carbon dioxide (CO2), soil moisture distribution, and Pakchoi productivity. A pot experiment was conducted using three SDI depths, emitters buried at 0.05, 0.10, and 0.15 m below the soil’s surface, and three levels of C content named zero biochar (CK), 50% C (low (L)), and 95% C (high (H)) in greenhouse cultivation. The findings showed biochar significantly decreased N2O and CO2 emissions. Compared to CK, the L and H treatments decreased N2O by (18.20, 28.14%), (16.65, 17.51%), and 11.05, 18.65%) under SDI5, SDI10, and SDI15, respectively. Similarly, the L and H treatments decreased CO2 by (8.05, 31.46%), (6.96, 28.88%), and (2.97, 7.89%) under SDI5, SDI10, and SDI15, respectively. Compared to CK, L and H increased soil moisture content. All plant growth parameters and yield traits were enhanced under SDI5. In summary, biochar addition significantly decreased soil N2O and CO2 emissions compared to CK, and increased growth performance and yield, and maintained soil moisture content. The H treatment significantly reduced N2O and CO2 emissions, increased plant growth and yield, and maintained soil moisture content compared to the L treatment. Soil moisture was reduced vertically and horizontally with increased radial distance from the emitter.
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Meehl, Gerald A., Aixue Hu, Julie M. Arblaster, John Fasullo, and Kevin E. Trenberth. "Externally Forced and Internally Generated Decadal Climate Variability Associated with the Interdecadal Pacific Oscillation." Journal of Climate 26, no. 18 (September 9, 2013): 7298–310. http://dx.doi.org/10.1175/jcli-d-12-00548.1.
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Abstract Globally averaged surface air temperatures in some decades show rapid increases (accelerated warming decades), and in other decades there is no warming trend (hiatus decades). A previous study showed that the net energy imbalance at the top of the atmosphere of about 1 W m−2 is associated with greater increases of deep ocean heat content below 750 m during the hiatus decades, while there is little globally averaged surface temperature increase or warming in the upper ocean layers. Here the authors examine processes involved with accelerated warming decades and address the relative roles of external forcing from increasing greenhouse gases and internally generated decadal climate variability associated with interdecadal Pacific oscillation (IPO). Model results from the Community Climate System Model, version 4 (CCSM4), show that accelerated warming decades are characterized by rapid warming of globally averaged surface air temperature, greater increases of heat content in the upper ocean layers, and less heat content increase in the deep ocean, opposite to the hiatus decades. In addition to contributions from processes potentially linked to Antarctic Bottom Water (AABW) formation and the Atlantic meridional overturning circulation (AMOC), the positive phase of the IPO, adding to the response to external forcing, is usually associated with accelerated warming decades. Conversely, hiatus decades typically occur with the negative phase of the IPO, when warming from the external forcing is overwhelmed by internally generated cooling in the tropical Pacific. Internally generated hiatus periods of up to 15 years with zero global warming trend are present in the future climate simulations. This suggests that there is a chance that the current observed hiatus could extend for several more years.
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SHARMA, Sushma, and Dileep K. SINGH. "Influence of ammonium and moisture on survival and nifH transcription in the diazotrophic Pseudomonas mendocina S10." Notulae Scientia Biologicae 12, no. 1 (March 31, 2020): 114–23. http://dx.doi.org/10.15835/nsb12110545.
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Nitrogen is important for crop productivity and usually added in form of urea into the soil which negatively affects the environment. It is important to utilize nitrogen fixing bacteria for improving the nitrogen content of soil in India. Here, we have isolated nitrogen fixing-bacteria Pseudomonas mendocina S10 from rhizospheric soil and studied its nitrogenase activity along with its survival under sterile soil conditions. Enterobacterial Repetitive Intergenic Consensus (ERIC) PCR and Real-time quantitative PCR were employed to investigate the population and nifH transcripts level respectively in presence of ammonium and moisture additives. Strain S10 was capable of growth and expressing nifH transcripts in the presence of 2.5 mM ammonium and 20 percent water availability. Population of isolated strain and it’s nifH mRNA was found at low levels when exposed to 5 mM ammonium for 60 days of incubation period. However, viable bacterial count and nifH transcript levels remained low in the presence of 1.25 mM ammonium and zero percent water content. These findings indicate that isolated strain could tolerate ammonium up to 5 mM for 60 days and can maintained their cell viability in low moisture conditions. Results revealed the advantage of using gene expression to evaluate the physiological state of microorganism’s population in soil.
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Wang, Xinli, and Jin Li. "Facile Liquid-Phase Synthesis of a High-Performance Cd-Doped ZnO-Quantum-Dot-Based Photocatalyst." ECS Journal of Solid State Science and Technology 10, no. 12 (December 1, 2021): 124003. http://dx.doi.org/10.1149/2162-8777/ac4216.
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Doping is an effective functional modification method for improving the optical, electrical, and magnetic properties of semiconductors. Here, Cd-doped wurtzite ZnO-quantum-dot (ZQ) zero-dimensional nanomaterials were successfully prepared via liquid-phase synthesis. The experimental results showed that Cd doping can effectively shorten the bandgap, where the optical bandgap range of Cd-doping photocatalysts were 3.31–3.36 eV; in particular, the Cd5-ZQ (Cd contents of 0.5 wt%) sample reduced the bandgap from 3.39 to 3.31 eV compared to that of pure ZQ. This is consistent with the experimental results, where the simulation calculation results indicated the bandgap reduced from 3.107 to 2.912 eV after introducing Cd. Photoluminescence spectroscopy results confirmed the Cd-ion dopants efficiently capture excited electrons and further prolongs the charge lifetime. The degradation of a methylene blue solution under simulated solar light irradiation revealed that the photocatalytic properties of Cd-ZQ nanomaterial with suitable dopant concentration (Cd content 0.5 wt%) was significantly better than those of pure ZQ. The underlying mechanism involves a synergistic effect, and a reasonable and convenient strategy for uprate performance is presented.
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Smith, Liam D., Joseph Harper, Eliot Durand, Andrew Crayford, Mark Johnson, Hugh Coe, and Paul I. Williams. "Examination of the Influence of Alternative Fuels on Particulate Matter Properties Emitted from a Non-Proprietary Combustor." Atmosphere 15, no. 3 (February 29, 2024): 308. http://dx.doi.org/10.3390/atmos15030308.
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The aviation sector, like most other sectors, is moving towards becoming net zero. In the medium to long term, this will mean an increase in the use of sustainable aviation fuels. Research exists on the impact of fuel composition on non-volatile particulate matter (nvPM) emissions. However, there is more sparsity when considering the impact on volatile particulate matter (vPM) emissions. Here, nine different fuels were tested using an open-source design combustor rig. An aerosol mass spectrometer (AMS) was used to examine the mass-loading and composition of vPM, with a simple linear regression algorithm used to compare relative mass spectrum similarity. The diaromatic, cycloalkane and aromatic contents of the fuels were observed to correlate with the measured total number concentration and nvPM mass concentrations, resulting in an inverse correlation with increasing hydrogen content. The impacts of fuel properties on other physical properties within the combustion process and how they might impact the particulate matter (PM) are considered for future research. Unlike previous studies, fuel had a very limited impact on the organic aerosol’s composition at the combustor exit measurement location. Using a novel combination of Positive Matrix Factorization (PMF) and high-resolution AMS analysis, new insight has been provided into the organic composition. Both the alkane organic aerosol (AlkOA) and quenched organic aerosol (QOA) factors contained CnH2n+1, CnH2n−1 and CnH2n ion series, implying alkanes and alkenes in both, and approximately 12% oxygenated species in the QOA factor. These results highlight the emerging differences in the vPM compositional data observed between combustor rigs and full engines.
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Siton, Yarden, and Alon Kuperman. "Generalization of Split DC Link Voltages Behavior in Three-Phase-Level Converters Operating with Arbitrary Power Factor with Restricted Zero-Sequence Component." Electronics 12, no. 19 (September 27, 2023): 4063. http://dx.doi.org/10.3390/electronics12194063.
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This article examines the impact of a power factor on the behavior of partial DC link voltages in three-phase three-level AC/DC (or DC/AC) converters operating without additional balancing hardware. We consider the case in which the controller utilizes a bandwidth-restricted (DC in steady state) zero-sequence component to achieve average partial DC link voltage equalization since the injection of high-order zero-sequence components is impossible or forbidden. An assessment of partial split DC-link capacitor voltage behavior (particularly that of ripple magnitudes and phases) is necessary for, e.g., minimizing the values of DC link capacitances and selecting reference voltage values. Previous studies assessed the abovementioned behavior analytically for operation under a unity power factor based on third-harmonic-dominated split partial voltages’ ripple nature. However, it is shown here that deviation from the unity power factor introduces additional (to the third harmonic) non-negligible harmonic content, increasing partial voltage ripple magnitudes and shifting their phase (relative to the mains voltages). As a result, the third-harmonic-only assumption is no longer valid, and it is then nearly impossible to derive corresponding analytical expressions. Consequently, a numerical approach is used in this work to derive a generalized expression of normalized ripple energy as a function of the power factor, which can then easily be utilized for assessments of split DC link voltage behaviors for certain DC link capacitances and reference voltages. Simulations and experimental results validate the proposed methodology applied to a 10 kVA T-type converter prototype.
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Lyman, John M., and Gregory C. Johnson. "Estimating Global Ocean Heat Content Changes in the Upper 1800 m since 1950 and the Influence of Climatology Choice*." Journal of Climate 27, no. 5 (February 24, 2014): 1945–57. http://dx.doi.org/10.1175/jcli-d-12-00752.1.
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Abstract Ocean heat content anomalies are analyzed from 1950 to 2011 in five distinct depth layers (0–100, 100–300, 300–700, 700–900, and 900–1800 m). These layers correspond to historic increases in common maximum sampling depths of ocean temperature measurements with time, as different instruments—mechanical bathythermograph (MBT), shallow expendable bathythermograph (XBT), deep XBT, early sometimes shallower Argo profiling floats, and recent Argo floats capable of worldwide sampling to 2000 m—have come into widespread use. This vertical separation of maps allows computation of annual ocean heat content anomalies and their sampling uncertainties back to 1950 while taking account of in situ sampling advances and changing sampling patterns. The 0–100-m layer is measured over 50% of the globe annually starting in 1956, the 100–300-m layer starting in 1967, the 300–700-m layer starting in 1983, and the deepest two layers considered here starting in 2003 and 2004, during the implementation of Argo. Furthermore, global ocean heat uptake estimates since 1950 depend strongly on assumptions made concerning changes in undersampled or unsampled ocean regions. If unsampled areas are assumed to have zero anomalies and are included in the global integrals, the choice of climatological reference from which anomalies are estimated can strongly influence the global integral values and their trend: the sparser the sampling and the bigger the mean difference between climatological and actual values, the larger the influence.
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Monjo, Robert. "What if the Universe Expands Linearly? A Local General Relativity to Solve the “Zero Active Mass” Problem." Astrophysical Journal 967, no. 1 (May 1, 2024): 66. http://dx.doi.org/10.3847/1538-4357/ad3df7.
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Abstract Modern cosmology presents important challenges such as the Hubble Tension, El Gordo’s collision, or the impossible galaxies (z > 10). Slight modifications to the standard model propose new parameters (e.g., the early and dynamical dark energy). On the other hand, alternatives such as the coasting universes (e.g., the hyperconical model and the spatially flat R h = ct universe) are statistically compatible with most of the observational tests, but still present theoretical problems in matching the observed matter contents since they predict a “zero active gravitational mass.” To solve these open issues, we suggest that general relativity might be not valid at cosmic scales, but it would be valid at local scales. This proposal is addressed from two main features of the embedding hyperconical model: (1) the background metric would be independent of the matter content, and (2) the observed cosmic acceleration would be fictitious and because of a distorted stereographic projection of coordinates that produce an apparent radial inhomogeneity from homogeneous manifolds. Finally, to support the discussion, standard observational tests were updated here, showing that the hyperconical model is adequately fitted to Type Ia supernovae, quasars, galaxy clusters, baryon acoustic oscillations, and cosmic chronometer data sets.
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Holmes, Ryan M., Jan D. Zika, and Matthew H. England. "Reply to “Comments on ‘Diathermal Heat Transport in a Global Ocean Model’”." Journal of Physical Oceanography 49, no. 8 (August 2019): 2195–97. http://dx.doi.org/10.1175/jpo-d-19-0139.1.
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AbstractHochet and Tailleux (2019), in a comment on Holmes et al. (2019), argue that under the incompressible Boussinesq approximation the “sum of the volume fluxes through any kind of control volume must integrate to zero at all times.” They hence argue that the expression in Holmes et al. (2019) for the change in the volume of seawater warmer than a given temperature is inaccurate. Here we clarify what is meant by the term “volume flux” as used in Holmes et al. (2019) and also more generally in the water-mass transformation literature. Specifically, a volume flux across a surface can occur either due to fluid moving through a fixed surface, or due to the surface moving through the fluid. Interpreted in this way, we show using several examples that the statement from Hochet and Tailleux (2019) quoted above does not apply to the control volume considered in Holmes et al. (2019). Hochet and Tailleux (2019) then derive a series of expressions for the water-mass transformation or volume flux across an isotherm in the general, compressible case. In the incompressible Boussinesq limit these expressions reduce to a form (similar to that provided in Holmes et al. 2019) that involves the temperature derivative of the diabatic heat fluxes. Due to this derivative, can be difficult to robustly estimate from ocean model output. This emphasizes one of the advantages of the approach of Holmes et al. (2019), namely, does not appear in the internal heat content budget and is not needed to describe the flow of internal heat content into and around the ocean.
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Canning, Anat, and Gerald H. F. Gardner. "A two‐pass approximation to 3-D prestack migration." GEOPHYSICS 61, no. 2 (March 1996): 409–21. http://dx.doi.org/10.1190/1.1443969.
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A two‐pass approximation to 3-D Kirchhoff migration simplifies the migration procedure by reducing it to a succession of 2-D operations. This approach has proven very successful in the zero‐offset case. A two‐pass approximation to 3-D migration is described here for the prestack case. Compared to the one‐pass approach, the scheme presented here provides significant reduction in computation time and a relatively simple data manipulation scheme. The two‐pass method was designed using velocity independent prestack time migration (DMO‐PSI) applied in the crossline direction, followed by conventional prestack depth migration in the inline direction. Velocity analysis, an important part of prestack migration, is also included in the two‐pass scheme. It is carried out as a 2-D procedure after 3-D effects are removed from the data volume. The procedure presented here is a practical full volume 3-D prestack migration. One of its main benefits is a realistic and efficient iterative velocity analysis procedure in three dimensions. The algorithm was designed in the frequency domain and the computational scheme was optimized by processing individual frequency slices independently. Irregular trace distribution, a feature that characterizes most 3-D seismic surveys, is implicitly accounted for within the two‐pass algorithm. A numerical example tests the performance of the two‐pass 3-D prestack migration program in the presence of a vertical velocity gradient. A 3-D land survey from a fold and thrust belt region was used to demonstrate the algorithm in a complex geological setting. The results were compared with images from other 2-D and 3-D migration schemes and show improved resolution and higher signal content.
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Lee, ChungHyuk, Siddharth Komini Babu, Rangachary Mukundan, Rod L. Borup, and Jacob S. Spendelow. "Groovy Electrodes Enable Facile O2 and H+ Transport in PEMFCs." ECS Meeting Abstracts MA2022-01, no. 35 (July 7, 2022): 1420. http://dx.doi.org/10.1149/ma2022-01351420mtgabs.
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Polymer electrolyte membrane fuel cells (PEMFCs) are promising alternative to internal combustion engines, owing to their capability to produce on-demand power with zero local carbon emissions. However, PEMFCs suffer from limitations related to performance, particularly for heavy-duty vehicle applications [1]. A major contributor to the performance loss is the cathode electrode; uncontrolled conventional electrode structures lead to non-ideal transport pathways of O2 and H+ [2], subsequently leading to performance loss. Here, we report an alternative electrode structure termed groovy electrodes, fabricated via patterned Si templates. Si templates with desired patterns are fabricated through photolithography and deep-reactive ion etching techniques (Fig. 1a), and an electrode layer is coated onto the template and subsequently transferred to the membrane or the gas diffusion layer. The resulting electrode features ordered grooves with consistent depth and width (Fig. 1b-c). We will present how this alternative structure enables improved H+ transport (enabled by higher ionomer content) with grooves facilitating effective O2 transport to reaction sites. We will also demonstrate the benefits of a groovy electrode for the durability of PEMFCs. Reference Cullen et al., Nat. Energy, 6, 462 (2021). Ramaswamy et al., J. Electrochem. Soc., 167, 064515 (2020). Figure 1
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Kane, Peter F., William L. Hall, J. Bartos, R. Boles, M. Dupuis, E. Hasty, C. Kinsey, et al. "Determination of Arsenic, Cadmium, Cobalt, Chromium, Lead, Molybdenum, Nickel, and Selenium in Fertilizers by Microwave Digestion and Inductively Coupled Plasma-Optical Emission Spectrometry Detection: Collaborative Study." Journal of AOAC INTERNATIONAL 89, no. 6 (November 1, 2006): 1447–66. http://dx.doi.org/10.1093/jaoac/89.6.1447.
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Abstract There is increasing regulatory interest in the non-nutritive metals content of fertilizer materials, but at present there is no consensus analytical method for acid digestion and instrument detection of those elements in fertilizer matrixes. This lack of method standardization has resulted in unacceptable variability of results between fertilizer laboratories performing metals analysis. A method has been developed using microwave digestion with nitric acid at 200C, followed by inductively coupled plasma-optical emission spectrometry instrument detection, for the elements arsenic, cadmium, cobalt, chromium, molybdenum, nickel, lead, and selenium. The method has been collaboratively studied, and statistical results are here reported. Fourteen collaborators were sent 62 sample materials in a blind duplicate design. Materials represented a broad cross section of fertilizer types, including phosphateore, manufactured phosphate products, N-P-K blends, organic fertilizers, and micro-nutrient materials. As much as possible within the limit of the number of samples, materials were selected from different regions of the United States and the world. Limit of detection (LOD) was determined using synthetic fertilizers consisting of reagent grade chemicals with near zero levels of the non-nutritive elements, analyzed blindly. Samples with high iron content caused the most variability between laboratories. Most samples reasonably above LOD gave HorRat values within the range 0.5 to 2.0, indicating acceptable method performance according to AOAC guidelines for analyses in the mg/kg range. The method is recommended for AOAC Official First Action status.
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Neginal, Jyoti, and Ruksar Fatima. "Colour image steganography through channel transformation approach." IAES International Journal of Artificial Intelligence (IJ-AI) 12, no. 3 (September 1, 2023): 1062. http://dx.doi.org/10.11591/ijai.v12.i3.pp1062-1069.
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The interest in information security strategies is expanding due the quick expansion in the use of media content and transmission over the web employments. Accordingly, there is a need of special embedding procedure for steganography. The creator presents an original reversible data hiding (RDH) algorithm for colour pictures that further develops the inserting execution by applying a channel transformation function and a versatile expectation blunder extension prediction error expansion structure. The proposed calculation will bring the first colour picture with no information misfortune from the inserted picture (which is unique in addition to target picture). The evaluation is done here at the zero for the given base place for the histogram that marginally changes the pixel esteems for inserting the information. It can insert more information when contrasted with the majority of the current data hiding calculations. A hypothetical confirmation and various examinations state that the embedding capability of the proposed model which consistently is further noteworthy in comparison with other reversible data hiding techniques. The calculation has been applied to a wide scope of various colour pictures effectively. Some exploratory outcomes are introduced to show the legitimacy of the calculation.
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Lou, F., N. A. Curtin, and R. C. Woledge. "Isometric and isovelocity contractile performance of red musle fibres from the dogfishScyliorhinus canicula." Journal of Experimental Biology 205, no. 11 (June 1, 2002): 1585–95. http://dx.doi.org/10.1242/jeb.205.11.1585.
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SUMMARYMaximum isometric tetanic force produced by bundles of red muscle fibres from dogfish, Scyliorhinus canicula (L.), was 142.4±10.3 kN m-2 (N=35 fibre bundles); this was significantly less than that produced by white fibres 289.2±8.4 kN m-2(N=25 fibre bundles) (means ± S.E.M.). Part, but not all, of the difference is due to mitochondrial content. The maximum unloaded shortening velocity, 1.693±0.108 L0 s-1(N=6 fibre bundles), was measured by the slack-test method. L0 is the length giving maximum isometric force. The force/velocity relationship was investigated using a step-and-ramp protocol in seven red fibre bundles. The following equation was fitted to the data:[(P/P0)+(a/P0)](V+b)=[(P0*/P0)+(a/P0)]b,where P is force during shortening at velocity V,P0 is the isometric force before shortening, and a, band P0* are fitted constants. The fitted values were P0*/P0=1.228±0.053, Vmax=1.814±0.071 L0s-1, a/P0=0.269±0.024 and b=0.404±0.041 L0 s-1(N=7 for all values). The maximum power was 0.107±0.005P0Vmax and was produced during shortening at 0.297±0.012Vmax. Compared with white fibres from dogfish, the red fibres have a lower P0 (49%) and Vmax (48%), but the shapes of the force/velocity curves are similar. Thus, the white and red fibres have equal capacities to produce power within the limits set by the isometric force and maximum velocity of shortening of each fibre type. A step shortening of 0.050±0.003L0 (N=7) reduced the maximum isometric force in the red fibres' series elasticity to zero. The series elasticity includes all elastic structures acting in series with the attached cross-bridges. Three red fibre bundles were stretched at a constant velocity, and force (measured when length reached L0) was 1.519±0.032P0. In the range of velocities used here, -0.28 to -0.63Vmax, force varied little with the velocity.
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Ponomareva, Tatyana, and Tatyana Shumilova. "Magnetic Properties of Impact UHPHT Glasses, Melt Rocks, Suevitic Breccia and Target Rocks of the Giant Kara Meteorite Crater (Pay-Khoy, Arctic Seashore, Russia)." IOP Conference Series: Earth and Environmental Science 906, no. 1 (November 1, 2021): 012086. http://dx.doi.org/10.1088/1755-1315/906/1/012086.
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Abstract The shock waves can strongly change the physical properties of the target rock minerals including their density and magnetism which determine petrochemical properties of impactites finely as a rule are resulted in astroblemes contours on geophysical maps. Following to the aero-magnetic mapping data the non-magnetic sedimentary rocks of the Kara target create a zero and negative magnetic field with an average intensity of -1 nT, against the background the southwestern region of the Kara astrobleme provides the positive magnetic anomalies with an intensity of 1 to 3 nT which are in a good correspondence with the Pay-Khoy ridge structure general orientation. The Kara dome is characterised with an isometric negative anomaly of intensity -5 nT. Here we present the magnetic properties of the different kinds of the Kara impactites including impact ultra-high pressure high temperature (UHPHT) melt glasses, melt rocks and suevitic breccia compare to sedimentary target rocks. The petrophysical measurements presented the specific magnetic susceptibility of the impactites in the range of 8 to 48×10-8 SI units, where the UHPHT glasses have the limits from 9 to 38×10-8 SI units (15×10-8 SI units, in average). The sedimentary target is characterised with essentially lower level of magnetic susceptibility – no higher than 15×10-8 SI units, where limestone has it about zero. Following to the similar level of the iron content within the impactites and target rocks the magnetism of the Kara impact melts is explained rather by changing of magnetic properties by the impact process. One of the possible source of magnetism can be partially an iron-containing matter of the asteroid component in the form of pyrrhotine accompanied with Ni and Co impurities. Also, we cannot exclude partial presence of magnetic iron component directly within the quenched impact glasses including UHPHT variety.
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Swacha, Jakub, and Karolina Muszyńska. "Predicting Dropout in Programming MOOCs through Demographic Insights." Electronics 12, no. 22 (November 16, 2023): 4674. http://dx.doi.org/10.3390/electronics12224674.
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Massive Open Online Courses (MOOCs) have gained widespread popularity for their potential to offer education to an unlimited global audience. However, they also face a critical challenge in the form of high dropout rates. This paper addresses the need to identify students at risk of dropping out early in MOOCs, enabling course organizers to provide targeted support or adapt the course content to meet students’ expectations. In this context, zero-time dropout predictors, which utilize demographic data before the course commences, hold significant potential. Despite a lack of consensus in the existing literature regarding the efficacy of demographic data in dropout prediction, this study delves into this issue to contribute new insights to the ongoing discourse. Through an extensive review of prior research and a detailed analysis of data acquired from two programming MOOCs, we aim to shed light on the relationship between students’ demographic characteristics and their likelihood of early dropout from MOOCs, using logistic regression. This research extends the current understanding of the impact of demographic features on student retention. The results indicate that age, education level, student status, nationality, and disability can be used as predictors of dropout rate, though not in every course. The findings presented here are expected to affect the development of more effective strategies for reducing MOOC dropout rates, ultimately enhancing the educational experience for online learners.
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Sivuoja-Gunaratnam, Anne. "Voicing Le Neutre in the invisible choir in Richard Wagner’s Parsifal." Sign Systems Studies 36, no. 1 (December 31, 2008): 83–112. http://dx.doi.org/10.12697/sss.2008.36.1.06.
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Roland Barthes was suspicious about the ability of music and voice to signify, as revealed in many of his writings. However, his somewhat limited views on music and voice need not to restrain from profiting his semiotic theorising and his reasoning, which can be adapted for musical instances in ways not envisaged by Barthes. The Neutral (Le Neutre) is a recurrent topic in Barthes’s oeuvre from his first book, Writing Zero Degree (1953) up to his 1978 lecture series on The Neutral in Collège de France (published in 2002). This paper explores how Barthes’s Neutral may enhance a special kind of listening. The enigmatic sonorities emitted by the Invisible Choir in Richard Wagner’s Parsifal (1882) serve as the foil in this task, more precisely a phrase voiced by female altos and male tenors (“Nehmet hin meinen Leib [...]”, Act I). It is not its semantic content mediated by (written) language that is of interest here but how this phrase has been voiced, and furthermore, how Barthes’s Neutral may be heard in and beneath it. Several commercially available live recordings made in Bayreuth have offered playground for listening to and for The Neutral. As my analysis shows, the audible Neutral is not a separate entity but works in conjunction with other modes of signification: visual, textual, biographical, spatial.
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Jukić, Tina, and Blaž Svete. "The Use of Facebook in the Slovenian Local Self-Government: Empirical Evidence." Central European Public Administration Review 16, no. 2 (November 19, 2018): 7–22. http://dx.doi.org/10.17573/cepar.2018.2.01.
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The paper presents a contribution to the rapidly growing field of social networks usage in public administration organizations. Despite the increasing volume of research in this field, there is a lack of detailed empirical evidence. To address the issue, we aim here at comprehensive empirical analysis of the usage of Facebook as the most popular social networking site among Slovenian municipalities. The methodology of research is based on 21 indicators measuring usage, engagement, multichannel features, multi-media content, and the existence of a social networks usage strategy. The measurement has been performed in each of the 212 Slovenian municipalities. Their Facebook interaction has been observed in a period of six months, from November 2015 to May 2016. The analysis results reveal that only 36% of the Slovenian municipalities were present on Facebook in 2016, with almost a quarter having a zero interaction rate on their Facebook pages/profiles in the observed six-month period. In particular, one-way interaction was recorded on municipal Facebook pages, leaving considerable room for improvement as regards the usage of Facebook as a social network with the highest potential of reach and engagement in terms of number of its users. The results are useful for information and benchmarking purposes for Slovenian and foreign municipal managers.
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Corrêa, Raissa Lohanna Gomes Quintino, Renan dos Santos, Lindomar José Calumby Albuquerque, Gabriel Lima Barros de Araujo, Charlotte Jennifer Chante Edwards-Gayle, Fabio Furlan Ferreira, and Fanny Nascimento Costa. "Ciprofibrate-Loaded Nanoparticles Prepared by Nanoprecipitation: Synthesis, Characterization, and Drug Release." Polymers 13, no. 18 (September 18, 2021): 3158. http://dx.doi.org/10.3390/polym13183158.
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Ciprofibrate (CIP) is a highly lipophilic and poorly water-soluble drug, typically used for dyslipidemia treatment. Although it is already commercialized in capsules, no previous studies report its solid-state structure; thus, information about the correlation with its physicochemical properties is lacking. In parallel, recent studies have led to the improvement of drug administration, including encapsulation in polymeric nanoparticles (NPs). Here, we present CIP’s crystal structure determined by PXRD data. We also propose an encapsulation method for CIP in micelles produced from Pluronic P123/F127 and PEO-b-PCL, aiming to improve its solubility, hydrophilicity, and delivery. We determined the NPs’ physicochemical properties by DLS, SLS, ELS, SAXS and the loaded drug amount by UV-Vis spectroscopy. Micelles showed sizes around 10–20 nm for Pluronic and 35–45 nm for the PEO-b-PCL NPs with slightly negative surface charge and successful CIP loading, especially for the latter; a substantial reduction in ζ-potential may be evidenced. For Pluronic nanoparticles, we scanned different conditions for the CIP loading, and its encapsulation efficiency was reduced while the drug content increased in the nanoprecipitation protocol. We also performed in vitro release experiments; results demonstrate that probe release is driven by Fickian diffusion for the Pluronic NPs and a zero-order model for PEO-b-PCL NPs.
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Hünger, K. J., H. Wollgarn, R. Rathnow, and R. Frey. "Zum Reaktionsverhalten präkambrischer Grauwacken im alkalischen Milieu von Betonen / The reactions of precambrian greywackes in an alkaline pore solution of concretes." Restoration of Buildings and Monuments 4, no. 4 (August 1, 1998): 377–98. http://dx.doi.org/10.1515/rbm-1998-5291.
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Abstract Two precambrian greywackes GW1A and GW1C with different structures were investigated to describe their reaction behaviour in concrete. A portlandcement CEM I, 32,5 with a high alkali content (Na2O-eq. = 1,4 %) was used. The soluble constituents of the greywackes in the alkaline pore solution of the concrete were determined by using a special method of chemical concrete analysis. The concrete samples were storaged in a special fog chamber at 40 °C and 100 % rel. humidity until to 9 month. The following conclusions can be given: 1 The concrete samples which were made with greywacke GWIA show a damage value of about 4 to 5 by means of rifts observed. Analogeous to the damage it can be found that the concentration of the soluble constituents which were release from greywacke begins at zero and increases continual}· until the end of the investigation. A specific discussion of several soluble oxides shows enormous differences between the reactivity of certain constituents investigated. 2 The concrete samples which were manufactured with greywacke GWIC show a damage value of about 1...2 only. But the quantity of the soluble constituents which come from the greywacke is higher. Characteristically here is a shoot up of the soluble constituents after beginning of the cement hydration process. After this the content of the soluble constituents decreases again. This behaviour in chemical reactivity of greywacke investigated can be declared by different structures. The mainly differences between both the GWIA and the GWIC were the size of the greywacke constituents. The chemical reactivity which was determined immediately after the alkali attack of the pore solution of the hardened cement and the macroscopical reactivity observed by means of rifts after 9 month are not the same.
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Xie, Peitao, Zidong Zhang, Zhongyang Wang, Kai Sun, and Runhua Fan. "Targeted Double Negative Properties in Silver/Silica Random Metamaterials by Precise Control of Microstructures." Research 2019 (January 15, 2019): 1–11. http://dx.doi.org/10.34133/2019/1021368.
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The mechanism of negative permittivity/permeability is still unclear in the random metamaterials, where the precise control of microstructure and electromagnetic properties is also a challenge due to its random characteristic. Here silver was introduced into porous SiO2 microsphere matrix by a self-assemble and template method to construct the random metamaterials. The distribution of silver was restricted among the interstices of SiO2 microspheres, which lead to the precise regulation of electrical percolation (from hoping to Drude-type conductivity) with increasing silver content. Negative permittivity came from the plasma-like behavior of silver network, and its value and frequency dispersion were further adjusted by Lorentz-type dielectric response. During this process, the frequency of epsilon-near-zero (ENZ) could be adjusted accordingly. Negative permeability was well explained by the magnetic response of eddy current in silver micronetwork. The calculation results indicated that negative permeability has a linear relation with ω0.5, showing a relaxation-type spectrum, different from the “magnetic plasma” of periodic metamaterials. Electromagnetic simulations demonstrated that negative permittivity materials and ENZ materials, with the advantage of enhanced absorption (40dB) and intelligent frequency selection even in a thin thickness (0.1 mm), could have potentials for electromagnetic attenuation and shielding. This work provides a clear physical image for the theoretical explanation of negative permittivity and negative permeability in random metamaterials, as well as a novel strategy to precisely control the microstructure of random metamaterials.
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Xie, Peitao, Zidong Zhang, Zhongyang Wang, Kai Sun, and Runhua Fan. "Targeted Double Negative Properties in Silver/Silica Random Metamaterials by Precise Control of Microstructures." Research 2019 (January 15, 2019): 1–11. http://dx.doi.org/10.1155/2019/1021368.
Full textAbstract:
The mechanism of negative permittivity/permeability is still unclear in the random metamaterials, where the precise control of microstructure and electromagnetic properties is also a challenge due to its random characteristic. Here silver was introduced into porous SiO2 microsphere matrix by a self-assemble and template method to construct the random metamaterials. The distribution of silver was restricted among the interstices of SiO2 microspheres, which lead to the precise regulation of electrical percolation (from hoping to Drude-type conductivity) with increasing silver content. Negative permittivity came from the plasma-like behavior of silver network, and its value and frequency dispersion were further adjusted by Lorentz-type dielectric response. During this process, the frequency of epsilon-near-zero (ENZ) could be adjusted accordingly. Negative permeability was well explained by the magnetic response of eddy current in silver micronetwork. The calculation results indicated that negative permeability has a linear relation with ω0.5, showing a relaxation-type spectrum, different from the “magnetic plasma” of periodic metamaterials. Electromagnetic simulations demonstrated that negative permittivity materials and ENZ materials, with the advantage of enhanced absorption (40dB) and intelligent frequency selection even in a thin thickness (0.1 mm), could have potentials for electromagnetic attenuation and shielding. This work provides a clear physical image for the theoretical explanation of negative permittivity and negative permeability in random metamaterials, as well as a novel strategy to precisely control the microstructure of random metamaterials.
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Müller, Albert L., Wenyu Gu, Vadim Patsalo, Jörg S. Deutzmann, James R. Williamson, and Alfred M. Spormann. "An alternative resource allocation strategy in the chemolithoautotrophic archaeon Methanococcus maripaludis." Proceedings of the National Academy of Sciences 118, no. 16 (April 16, 2021): e2025854118. http://dx.doi.org/10.1073/pnas.2025854118.
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Most microorganisms in nature spend the majority of time in a state of slow or zero growth and slow metabolism under limited energy or nutrient flux rather than growing at maximum rates. Yet, most of our knowledge has been derived from studies on fast-growing bacteria. Here, we systematically characterized the physiology of the methanogenic archaeon Methanococcus maripaludis during slow growth. M. maripaludis was grown in continuous culture under energy (formate)-limiting conditions at different dilution rates ranging from 0.09 to 0.002 h−1, the latter corresponding to 1% of its maximum growth rate under laboratory conditions (0.23 h−1). While the specific rate of methanogenesis correlated with growth rate as expected, the fraction of cellular energy used for maintenance increased and the maintenance energy per biomass decreased at slower growth. Notably, proteome allocation between catabolic and anabolic pathways was invariant with growth rate. Unexpectedly, cells maintained their maximum methanogenesis capacity over a wide range of growth rates, except for the lowest rates tested. Cell size, cellular DNA, RNA, and protein content as well as ribosome numbers also were largely invariant with growth rate. A reduced protein synthesis rate during slow growth was achieved by a reduction in ribosome activity rather than via the number of cellular ribosomes. Our data revealed a resource allocation strategy of a methanogenic archaeon during energy limitation that is fundamentally different from commonly studied versatile chemoheterotrophic bacteria such as E. coli.
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Schröder, Rasmus R., Dietmar Manstein, Werner Jahn, and James A. Spudich. "Energy filtering and correction for the contrast transfer function (CTF) of frozen hydrated objects as illustrated by a reconstruction of Dictyostelium S1 decorated actin." Proceedings, annual meeting, Electron Microscopy Society of America 51 (August 1, 1993): 118–19. http://dx.doi.org/10.1017/s0424820100146436.
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Ice embedded samples can not be simply described as weak phase objects, but as strong interacting specimens with inelastically dominated multiple scattering. Removal of the inelastically scattered electrons allows closer to focus imaging and improves the structural signal to noise ratio, both leading to a higher structural information content. Recent work demonstrated, that for radial density distributions the CTF correction of energy filtered images was necessary and sufficient to obtain good agreement with X-ray data. Here we present the fully CTF-corrected three dimensional structure of F-actin decorated with Dictyostelium myosin head fragment (MHF). The results show aggreement to the known protein structure after CTF correction. In addition to the radial density profile also amplitudes of Bessel terms in the Fourier Transform are changing.Actin from rabbit muscle was decorated with Dictyostelium myosin head fragment under the usual buffer conditions. Images were taken with a Zeiss EFTEM EM902. Magnification was 50000x, electron energy 80kV, electron energy loss δE=0eV (zero-loss mode), energy width ΔE=20eV, defocus values were in the range of 500-900nm. Vitrified samples were observed at a temperature of 90K. All images were taken at an specimen electron dose of 500 e−/nm2, negative material was Kodak SO163 developed for 12 min in undiluted Kodak D19. For image processing and the helical reconstruction a new set of computer programs was written.
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Elghazouly, Alaa A., Mohamed I. Doma, and Ahmed A. Sedeek. "Estimating satellite and receiver differential code bias using a relative Global Positioning System network." Annales Geophysicae 37, no. 6 (November 18, 2019): 1039–47. http://dx.doi.org/10.5194/angeo-37-1039-2019.
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Abstract. Precise total electron content (TEC) is required to produce accurate spatial and temporal resolution of global ionosphere maps (GIMs). Receivers and satellite differential code biases (DCBs) are one of the main error sources in estimating precise TEC from Global Positioning System (GPS) data. Recently, researchers have been interested in developing models and algorithms to compute DCBs of receivers and satellites close to those computed from the Ionosphere Associated Analysis Centers (IAACs). Here we introduce a MATLAB code called Multi Station DCB Estimation (MSDCBE) to calculate satellite and receiver DCBs from GPS data. MSDCBE based on a spherical harmonic function and a geometry-free combination of GPS carrier-phase, pseudo-range code observations, and weighted least squares was applied to solve observation equations and to improve estimation of DCB values. There are many factors affecting the estimated values of DCBs. The first one is the observation weighting function which depends on the satellite elevation angle. The second factor is concerned with estimating DCBs using a single GPS station using the Zero Difference DCB Estimation (ZDDCBE) code or using the GPS network used by the MSDCBE code. The third factor is the number of GPS receivers in the network. Results from MSDCBE were evaluated and compared with data from IAACs and other codes like M_DCB and ZDDCBE. The results of weighted (MSDCBE) least squares show an improvement for estimated DCBs, where mean differences from the Center for Orbit Determination in Europe (CODE) (University of Bern, Switzerland) are less than 0.746 ns. DCBs estimated from the GPS network show better agreement with IAAC than DCBs estimated from precise point positioning (PPP), where the mean differences are less than 0.1477 and 1.1866 ns, respectively. The mean differences of computed DCBs improved by increasing the number of GPS stations in the network.
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Manjunath, G., and H. Jaeger. "Echo State Property Linked to an Input: Exploring a Fundamental Characteristic of Recurrent Neural Networks." Neural Computation 25, no. 3 (March 2013): 671–96. http://dx.doi.org/10.1162/neco_a_00411.
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The echo state property is a key for the design and training of recurrent neural networks within the paradigm of reservoir computing. In intuitive terms, this is a passivity condition: a network having this property, when driven by an input signal, will become entrained by the input and develop an internal response signal. This excited internal dynamics can be seen as a high-dimensional, nonlinear, unique transform of the input with a rich memory content. This view has implications for understanding neural dynamics beyond the field of reservoir computing. Available definitions and theorems concerning the echo state property, however, are of little practical use because they do not relate the network response to temporal or statistical properties of the driving input. Here we present a new definition of the echo state property that directly connects it to such properties. We derive a fundamental 0-1 law: if the input comes from an ergodic source, the network response has the echo state property with probability one or zero, independent of the given network. Furthermore, we give a sufficient condition for the echo state property that connects statistical characteristics of the input to algebraic properties of the network connection matrix. The mathematical methods that we employ are freshly imported from the young field of nonautonomous dynamical systems theory. Since these methods are not yet well known in neural computation research, we introduce them in some detail. As a side story, we hope to demonstrate the eminent usefulness of these methods.
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Panyadee, Prateep, Prasit Wangpakapattanawong, Angkhana Inta, and Henrik Balslev. "Very High Food Plant Diversity among Ethnic Groups in Northern Thailand." Diversity 15, no. 1 (January 16, 2023): 120. http://dx.doi.org/10.3390/d15010120.
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The combination of the high biodiversity and many ethnicities in Thailand results in extensive ethnobotanical studies, especially in the northern part of the country. Here we have assembled 7620 records from 60 references regarding how plants are used for food among 14 ethnicities in northern Thailand. The uses are based on 1182 different plant species. Vegetables are the most common food category, which contributed more than 60% of all use-reports and involved nearly 900 species. This was followed by the dessert fruit category, which included about 350 species and over 1800 use-reports. The similarity among the different ethnicities was low and the number of uses and species recorded among different ethnicities were significantly related to the number of studies that had been conducted for each group. This implies that additional ethnobotanical studies are still needed in order to conserve and compile the valuable traditional knowledge related to food plants. Many exotic species are now an important part of traditional knowledge, whereas rare endemic species are uncommon among wild food plants. This situation leads to a loss of traditional knowledge about food plants and reduced awareness of their importance. As a key to using this great reservoir of food for local people, traditional knowledge related to local wild food plants can contribute to the zero-hunger goal of the Sustainable Development Goal (SDG). More studies on the nutrient content and health properties of these plants could lead to the development of new crops to meet present consumer demands.
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Kivi, Iman R., Auregan Boyet, Haiqing Wu, Linus Walter, Sara Hanson-Hedgecock, Francesco Parisio, and Victor Vilarrasa. "Global physics-based database of injection-induced seismicity." Earth System Science Data 15, no. 7 (July 26, 2023): 3163–82. http://dx.doi.org/10.5194/essd-15-3163-2023.
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Abstract. Fluid injection into geological formations for energy resource development frequently induces (micro)seismicity. Moderate- to large-magnitude induced earthquakes may cause injuries and/or economic loss, with the consequence of jeopardizing the operation and future development of these geo-energy projects. To achieve an improved understanding of the mechanisms of induced seismicity, develop forecasting tools and manage the associated risks, it is necessary to carefully examine seismic data from reported cases of induced seismicity and the parameters controlling them. However, these data are challenging to gather together and are time-consuming to collate as they come from different disciplines and sources. Here, we present a publicly available, multi-physical database of injection-induced seismicity (Kivi et al., 2022a; https://doi.org/10.20350/digitalCSIC/14813), sourced from an extensive review of published documents. Currently, it contains 158 datasets of induced seismicity caused by various subsurface energy-related applications worldwide. Each dataset covers a wide range of variables, delineating general site information, host rock properties, in situ geologic and tectonic conditions, fault characteristics, conducted field operations, and recorded seismic activities. We publish the database in flat-file formats (i.e., .xls and .csv tables) to facilitate its dissemination and utilization by geoscientists while keeping it directly readable by computer codes for convenient data manipulation. The multi-disciplinary content of this database adds unique value to databases focusing only on seismicity data. In particular, the collected data aim at facilitating the understanding of the spatiotemporal occurrence of induced earthquakes, the diagnosis of potential triggering mechanisms, and the development of scaling relations of maximum possible earthquake magnitudes and operational parameters. The database will boost research in seismic hazard forecasting and mitigation, paving the way for increasing contributions of geo-energy resources to meeting net-zero carbon emissions.
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Grozovsky, Renata, Qiyong Peter Liu, Andrew Hanneman, David J. Ashline, Hailong Zhang, Vernon Reinhold, and Karin M. Hoffmeister. "The Human Platelet Glycome and Its Variations Among Healthy Volunteers and Storage." Blood 122, no. 21 (November 15, 2013): 2300. http://dx.doi.org/10.1182/blood.v122.21.2300.2300.
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Abstract Platelets have the shortest shelf-life of all major blood components and are the most difficult to store complicating platelet transfusion practices. Transfused fresh radiolabeled autologous platelets differ significantly in recovery and survival among healthy subjects, however the cause of the inter-individual differences remains unclear. We demonstrated that the loss of sialic acid from the surfaces of cold-stored and transfused platelets promotes their clearance by Ashwell Morell receptors. The loss of platelet surface sialic acid correlates with increases in surface sialidase activity during platelet storage. Here we investigated whether fresh platelets from individual donors exhibit differences in surface sialidase expression and glycan exposure and sialic acid content changes with storage. Methods Platelets were isolated by standard methods from the venous blood of healthy volunteers or from standard platelet concentrates (PCs) and analyzed by flow cytometry for surface β-galactose using FITC-conjugated E. cristagalli lectin (ECL). Platelet surface sialidase expression was measured by flow cytometry using antibodies to sialidases Neu1 and Neu3. Sialidase activities were assayed using standard methods, Platelet uptake by hepatocytes was measured by using the human hepatoma cell line HepG2. To further elucidate these issues in a structural biology context we performed baseline study of the N- and O-linked glycans and glycosphingolipids (GSLs) in platelets, and any structural changes observed during storage, by employing HPLC, LC-MS/(MS), and sequential mass spectrometry (MSn) approaches. Results We found that terminal galactose on freshly-isolated platelet glycoproteins varies considerably among healthy subjects: Seven of ten individuals had low levels of exposed galactose (15.3 ± 4.1, MFI) and three subjects exhibited significantly higher levels of terminal galactose as detected by flow cytometry using lectins. Reduced sialic acid content correlated with increased surface sialidase activity and expression. Platelets with high terminal galactose were ingested with a higher rate by HepG2 cells, i.e via Ashwell Morell receptors. Importantly, individuals with low sialic acid levels correlate with low platelet counts at steady state. Structural analysis revlealed that fresh platelet N-glycan pools include a significant amount of high-mannose (Man5-Man9) and asialo complex glycans, however, are dominated by a diverse range of complex sialylated structures with two to four antennae, up to four NeuAcs, and include antennary fucosylation, and five or more lactosamine extensions. The O-linked fractions are comprised of core-1 and core-2 glycans having zero, one, or two NeuAc residues. A significant decrease in sialylation during conventional platelet storage at room temperature was confirmed at the level of individual O-glycan structures. Quantitative analysis of the more structurally complex N-glycan pools is ongoing. Conclusion Our results show that fresh platelets from healthy individuals vary in surface sialidase activity and sialic acid content and exhibit a high complexity in glycan structures. Collectively we propose that individual platelet counts may be dependent on surface sialic acid content and that the surface sialic acid could represent a factor that affects the recovery and survival of transfused platelets. Disclosures: No relevant conflicts of interest to declare.
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Oliveira-Hofman, Camila, Vinícius S. Victor, Lance J. Meinke, and Julie A. Peterson. "Molecular Gut-Content Analysis of Adult Ground Beetles (Coleoptera: Carabidae) Provides No Evidence of Predation of Western Corn Rootworm (Coleoptera: Chrysomelidae) in a Nebraska Corn Agroecosystem." Journal of Entomological Science 55, no. 4 (October 26, 2020): 448–61. http://dx.doi.org/10.18474/0749-8004-55.4.448.
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Abstract This study was conducted to characterize the ground beetle (Coleoptera: Carabidae) community in Nebraska continuous cornfields and investigate the potential for predation of the western corn rootworm, Diabrotica virgifera virgifera LeConte, a key root-feeding insect pest that is an annual management challenge in this system. Seven collection dates were conducted at five commercial cornfields in west central Nebraska during the growing season of 2014. In each field, carabids were sampled using five 24-h pitfall traps. Carabid specimens were placed in 95% ethanol in the field and stored at –20°C to preserve DNA. After identification to the species level, DNA was extracted and polymerase chain reaction was conducted for gut-content analysis using D. v. virgifera-specific primers. Data from single-plant emergence cages and yellow sticky cards showed high abundance of D. v. virgifera prey in three of the five fields sampled. Sixteen genera and 36 carabid species were found in pitfall traps. Of the total 235 carabid specimens tested in this study, zero tested positive for D. v. virgifera DNA. The lack of positive results for the presence of D. v. virgifera DNA in the gut-contents of carabids, despite abundant pest populations, indicates that, in this system, ground beetles may not be a strong mortality agent of D. v. virgifera. However, results presented here contribute to our knowledge of carabid diversity in agroecosystems and indicate that future D. v. virgifera biological control efforts in this region should focus on other natural enemies and/or other life stages of carabids, such as larvae.
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Teanby, N. A., P. G. J. Irwin, J. I. Moses, and R. Helled. "Neptune and Uranus: ice or rock giants?" Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 378, no. 2187 (November 9, 2020): 20190489. http://dx.doi.org/10.1098/rsta.2019.0489.
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Existing observations of Uranus and Neptune’s fundamental physical properties can be fitted with a wide range of interior models. A key parameter in these models is the bulk rock:ice ratio and models broadly fall into ice-dominated (ice giant) and rock-dominated (rock giant) categories. Here we consider how observations of Neptune’s atmospheric temperature and composition (H 2 , He, D/H, CO, CH 4 , H 2 O and CS) can provide further constraints. The tropospheric CO profile in particular is highly diagnostic of interior ice content, but is also controversial, with deep values ranging from zero to 0.5 parts per million. Most existing CO profiles imply extreme O/H enrichments of >250 times solar composition, thus favouring an ice giant. However, such high O/H enrichment is not consistent with D/H observations for a fully mixed and equilibrated Neptune. CO and D/H measurements can be reconciled if there is incomplete interior mixing (ice giant) or if tropospheric CO has a solely external source and only exists in the upper troposphere (rock giant). An interior with more rock than ice is also more compatible with likely outer solar system ice sources. We primarily consider Neptune, but similar arguments apply to Uranus, which has comparable C/H and D/H enrichment, but no observed tropospheric CO. While both ice- and rock-dominated models are viable, we suggest a rock giant provides a more consistent match to available atmospheric observations. This article is part of a discussion meeting issue ‘Future exploration of ice giant systems’.
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Klemd, Reiner, Andreas Beinlich, Matti Kern, Malte Junge, Laure Martin, Marcel Regelous, and Robert Schouwstra. "Magmatic PGE Sulphide Mineralization in Clinopyroxenite from the Platreef, Bushveld Complex, South Africa." Minerals 10, no. 6 (June 25, 2020): 570. http://dx.doi.org/10.3390/min10060570.
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The Platreef, at the base of the northern limb of the Bushveld Complex in South Africa, hosts platinum-group element (PGE) mineralization in association with base-metal sulphides (BMS) and platinum-group minerals (PGM). However, whilst a magmatic origin of the stratiform mineralization of the upper Platreef has been widely confirmed, the processes responsible for the PGE and BMS mineralization and metasomatism of the host rocks in the Platreef are still under discussion. In order to contribute to the present discussion, we present an integrated petrographical, mineral-chemical, whole-rock trace- and major-element, sulphur- and neodymium-isotope, study of Platreef footwall clinopyroxenite drill core samples from Overysel, which is located in the northern sector of the northern Bushveld limb. A metasomatic transformation of magmatic pyroxenite units to non-magmatic clinopyroxenite is in accordance with the petrography and whole-rock chemical analysis. The whole-rock data display lower SiO2, FeO, Na2O and Cr (<1700 ppm), and higher CaO, concentrations in the here-studied footwall Platreef clinopyroxenite samples than primary magmatic Platreef pyroxenite and norite. The presence of capped globular sulphides in some samples, which display differentiation into pyrrhotite and pentlandite in the lower, and chalcopyrite in the upper part, is attributed to the fractional crystallization of a sulphide liquid, and a downward transport of the blebs. In situ sulphur (V-CDT) isotope BMS data show isotopic signatures (δ34S = 0.9 to 3.1 ‰; Δ33S = 0.09 to 0.32‰) close to or within the pristine magmatic range. Elevated (non-zero) Δ33S values are common for Bushveld magmas, indicating contamination by older, presumably crustal sulphur in an early stage chamber, whereas magmatic δ34S values suggest the absence of local crustal contamination during emplacement. This is in accordance with the εNd (2.06 Ga) (chondritic uniform reservoir (CHUR)) values, of −6.16 to −6.94, which are similar to those of the magmatic pyroxenite and norite of the Main Zone and the Platreef in the northern sector of the northern Bushveld limb. Base-metal sulphide textures and S–Se-ratios give evidence for a secondary S-loss during late- to post-magmatic hydrothermal alteration. The textural evidence, as well as the bulk S/Se ratios and sulphide S isotopes studies, suggest that the mineralization in both the less and the pervasively hydrothermally altered clinopyroxenite samples of Overysel are of magmatic origin. This is further supported by the PPGE (Rh, Pt, Pd) concentrations in the BMS and mass-balance calculations, in both of which large proportions of the whole-rock Pd and Rh are hosted by pentlandite, whereas Pt and the IPGE (Os, Ir, Ru) were interpreted to mainly occur in discrete PGM. However, the presence of pentlandite with variable PGE concentrations on the thin section scale may be related to variations in the S content, already at S-saturation during magmatic formation, and/or post-solidification mobilization and redistribution.
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SAUDER, C., H. CARDOT, C. DISENHAUS, and Y. LE COZLER. "Non-parametric approaches to the impact of Holstein heifer growth from birth to insemination on their dairy performance at lactation one." Journal of Agricultural Science 151, no. 4 (December 20, 2012): 578–89. http://dx.doi.org/10.1017/s0021859612000974.
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SUMMARYParametric approaches have been used widely to model animal growth and study the impact of growth profile on performance. Individual variation is often not considered in such approaches. However, non-parametric modelling allows this. Such an approach, based on spline functions, was used to study the importance of growth profiles from age 0 to 15 months (i.e. insemination) on milk yield and composition in primiparous cows. A dataset of 447 heifers was used for analysis of growth performance; 296 of them were also used to study impact on lactation. All of them originated from a French experimental herd and were born between 1986 and 2006. Clustering methods were also tested. Comparison of spline methods showed that a cubic spline interpolation method, with no smoothing parameter, was best suited to studying heifer growth. Similarly, partitioning around medoids proved the most accurate clustering method for classifying heifer growth into groups. The results of these analyses agreed with those previously published, supporting the utility of these methods. A final study on the impact of breakdowns in the growth curves was performed. A breakdown was considered only when the derivative of the interpolation function was negative or zero. Of the 447 heifers initially used, 125 (Gr0), 175 (Gr1) and 147 (Gr2) had no, one, or two or more breakpoints during the 0–15 months of age period. Milk yield on a 305 d basis was significantly reduced with an increased number of breakpoints (6548v.6828 and 6905 kg for Gr2, Gr1 and Gr0 animals, respectively). Fat content was also higher in Gr2 than in Gr0 groups, but overall, no difference in total fat or protein-corrected milk production was noted. The intersection between groups for growth and groups for breakdowns confirmed that animals with two or more breakdowns belonged more frequently to the group with the lowest growth performance. These results offer the possibility of analysing large databases, originating from an automatic collecting system (e.g. milking robots) or from different herds, breeds, genetics, etc. These approaches could also be used for studies on body score index, girth development, lactation profiles, etc. and in other species, such as dairy goats or beef cattle. They could find use in the development of new models of prediction, e.g. the probability of heat appearance on an animal basis, which could be included among useful management tools.