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Lin, Dakui, Zhengkun Liu, Kay Dietrich, Andréy Sokolov, Mewael Giday Sertsu, Hongjun Zhou, Tonglin Huo et al. „Soft X-ray varied-line-spacing gratings fabricated by near-field holography using an electron beam lithography-written phase mask“. Journal of Synchrotron Radiation 26, Nr. 5 (16.08.2019): 1782–89. http://dx.doi.org/10.1107/s1600577519008245.
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A fabrication method comprising near-field holography (NFH) with an electron beam lithography (EBL)-written phase mask was developed to fabricate soft X-ray varied-line-spacing gratings (VLSGs). An EBL-written phase mask with an area of 52 mm × 30 mm and a central line density greater than 3000 lines mm−1 was used. The introduction of the EBL-written phase mask substantially simplified the NFH optics for pattern transfer. The characterization of the groove density distribution and diffraction efficiency of the fabricated VLSGs indicates that the EBL–NFH method is feasible and promising for achieving high-accuracy groove density distributions with corresponding image properties. Vertical stray light is suppressed in the soft X-ray spectral range.
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Tlak Gajger, I., O. Vugrek, D. Grilec und Z. Petrinec. „Prevalence and distribution of Nosema ceranae in Croatian honeybee colonies“. Veterinární Medicína 55, No. 9 (07.10.2010): 457–62. http://dx.doi.org/10.17221/2983-vetmed.
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Nosema disease of European honey bees afflicts bees worldwide. Nosema ceranae is a recently described microsporidian parasite of the honey bee (Apis mellifera) and its geographical distribution is not well known. The disease may have many negative effects on bee colonies and cause high losses for apiculture and consequently in agriculture. With this in mind, a total of 204 samples of dead bees from different localities in Croatia were selected and investigated for distribution, prevalence and diversity of N. ceranae infection, using light microscopic examination and multiplex PCR. Our results show that N. ceranae is the only nosema species found to infect honeybees in our geographically varied collection. The nucleotide sequences of amplicons from Nosema-infested honeybee samples were 100% identical with the N. ceranae sequence deposited in the GenBank database. N. ceranae infected bees were found in samples collected from each of 21 districts, and in all three climatic areas, i.e., mediterranean, mountain, and continental parts regions of Croatia.
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Capouchová, I., J. Petr und D. Marešová. „Evaluation of size distribution of starch granules in selected wheat varieties by the Low Angle Laser Light Scattering method“. Plant, Soil and Environment 49, No. 1 (10.12.2011): 12–17. http://dx.doi.org/10.17221/4083-pse.
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The distribution of the size of wheat starch granules using the method LALLS (Low Angle Laser Light Scattering), followed by the evaluation of the effect of variety, experimental site and intensity of cultivation on the vol. % of the starch A (starch granules > 10 μm) was determined. The total starch content and crude protein content in dry matter of flour T530 in selected collection of five winter wheat varieties were determined. Vol. % of the starch A in evaluated collection of wheat varieties varied between 65.31 and 72.34%. The effect of a variety on the vol. % of starch A seemed to be more marked than the effect of site and intensity of cultivation. The highest vol. % of starch A reached evaluated varieties from the quality group C, i.e. varieties unsuitable for baking utilisation (except variety Contra with high total content of starch in dry matter of flour T530, but relatively low vol. % of starch A). A low vol. % of starch A was also found in the variety Hana (very good variety for baking utilisation). Certain variety differences followed from the evaluation of distribution of starch fractions of starch granules, forming starch A. In the case of varieties Hana, Contra and Siria higher representation of fractions up to 30 μm was recorded, while starch A in the varieties Estica andVersailleswas formed in higher degree by size fractions of starch granules over 30 μm and particularly size fraction > 50 μm was greatest in these varieties of all evaluated samples. With increasing total starch content in dry matter of flour T530 the crude protein content decreased; the vol. % of starch A not always increased proportionally with increasing total starch content.
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Cobben, M. M. P., R. van Treuren, N. P. Castañeda-Álvarez, C. K. Khoury, C. Kik und T. J. L. van Hintum. „Robustness and accuracy of Maxent niche modelling for Lactuca species distributions in light of collecting expeditions“. Plant Genetic Resources 13, Nr. 2 (18.09.2014): 153–61. http://dx.doi.org/10.1017/s1479262114000847.
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Niche modelling software can be used to assess the probability of detecting a population of a plant species at a certain location. In this study, we used the distribution of the wild relatives of lettuce (Lactuca spp.) to investigate the applicability of Maxent species distribution models for collecting missions. Geographic origin data of genebank and herbarium specimens and climatic data of the origin locations were used as input. For Lactuca saligna, we varied the input data by omitting the specimens from different parts of the known distribution area to assess the robustness of the predicted distributions. Furthermore, we examined the accuracy of the modelling by comparing the predicted probabilities of population presence against recent expedition data for the endemic Lactuca georgica and the cosmopolitan Lactuca serriola. We found Maxent to be quite robust in its predictions, although its usefulness was higher for endemic taxa than for more widespread species. The exclusion of occurrence data from the perceived range margins of the species can result in important information about local adaptation to distinct climatic conditions. We discuss the potential for enhanced use of Maxent in germplasm collecting planning.
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MARTINEZ, JUANA M., HASSAN ELFARISSI, BEGONA De VELASCO, GINA H. OCHOA, ARIA M. MILLER, YING MEI CLARK, BRIAN MATSUMOTO und LAURA J. ROBLES. „Distribution of tubulin, kinesin, and dynein in light- and dark-adapted octopus retinas“. Visual Neuroscience 17, Nr. 1 (Januar 2000): 127–38. http://dx.doi.org/10.1017/s0952523800171135.
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Cephalopod retinas exhibit several responses to light and dark adaptation, including rhabdom size changes, photopigment movements, and pigment granule migration. Light- and dark-directed rearrangements of microfilament and microtubule cytoskeletal transport pathways could drive these changes. Recently, we localized actin-binding proteins in light-/dark-adapted octopus rhabdoms and suggested that actin cytoskeletal rearrangements bring about the formation and degradation of rhabdomere microvilli subsets. To determine if the microtubule cytoskeleton and associated motor proteins control the other light/dark changes, we used immunoblotting and immunocytochemical procedures to map the distribution of tubulin, kinesin, and dynein in dorsal and ventral halves of light- and dark-adapted octopus retinas. Immunoblots detected α- and β-tubulin, dynein intermediate chain, and kinesin heavy chain in extracts of whole retinas. Epifluorescence and confocal microscopy showed that the tubulin proteins were distributed throughout the retina with more immunoreactivity in retinas exposed to light. Kinesin localization was heavy in the pigment layer of light- and dark-adapted ventral retinas but was less prominent in the dorsal region. Dynein distribution also varied in dorsal and ventral retinas with more immunoreactivity in light- and dark-adapted ventral retinas and confocal microscopy emphasized the granular nature of this labeling. We suggest that light may regulate the distribution of microtubule cytoskeletal proteins in the octopus retina and that position, dorsal versus ventral, also influences the distribution of motor proteins. The microtubule cytoskeleton is most likely involved in pigment granule migration in the light and dark and with the movement of transport vesicles from the photoreceptor inner segments to the rhabdoms.
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Liu, Qiang, Longfei Xie und Fengri Li. „The Spatial Distribution of the Needle Area of Planted Larix olgensis Trees“. Forests 10, Nr. 1 (04.01.2019): 28. http://dx.doi.org/10.3390/f10010028.
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The spatial distribution of leaf area largely governs both the structure and function of a tree crown. Three sample trees were selected from a 16-year-old Larix olgensis plantation in the Maoershan Forest Farm, Heilongjiang Province, based on the average diameter at breast height in each plot. All needles from the branches in the nodal and internodal pseudowhorls within the crown were destructively sampled. The crown was divided into several segments in the vertical and horizontal directions, resulting in different sub-regions. The needle area (NA) in each sub-region was computed based on the needle mass per area (NMA). The vertical and horizontal distributions and their cumulative NA distributions were characterized using the Weibull distribution function and its cumulative form. A two-dimensional NA model was created by combining the two Weibull distribution functions of the vertical and horizontal distributions. The variation in the spatial distribution of the NA among the different crown directions is discussed, and the influence of competition from competitors on the spatial distribution of NA was analyzed. The results showed that the Weibull distribution function and its cumulative form performed well in describing the vertical and horizontal distributions and the cumulative distributions of the NA, which was generally concentrated upward within the crown. This phenomenon was most apparent in dense stands with strong competition. The center of the NA exhibited an inward shift in the horizontal direction within the crown but shifted outwards with an increase in competition. The cumulative vertical and horizontal distributions of the NA obviously varied with different crown directions, which was associated mainly with the light conditions. The two-dimensional NA patterns showed that the center of the NA generally shifted outward with an increase in the relative depth into the crown (RDINC), and that more concentrated and more skewed patterns usually occurred under increased competition. Different crown directions exhibited different two-dimensional NA patterns, but the core driver was the variable light condition caused by the competitors, particularly in closed stands.
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Bretšnajdrová, Edita, Ladislav Svoboda und Jiří Zelenka. „Determination of Particle Shape and Size Distribution of Model Types of Nanomaterials“. Journal of Electrical Engineering 61, Nr. 5 (01.09.2010): 302–4. http://dx.doi.org/10.2478/v10187-011-0046-z.
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Determination of Particle Shape and Size Distribution of Model Types of Nanomaterials At present, great attention is given to study of preparation and properties of various nanomaterials usable in many applications. They are utilized in varied fields of human activity - eg in electronics, medicine, paint industry etc. Besides the detailed chemical structure, such nanoparticle properties as the shape and size distribution are fundamental to the given application. To measure these parameters various methods are used, e.g. transmission electron microscopy (TEM), atomic force microscopy (AFM), acoustic spectrometry, methods based on the light scattering and X-ray disc centrifuge system.
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Zhao, Fei, Lu Song, Zhiyan Peng, Jianqin Yang, Guize Luan, Chen Chu, Jieyu Ding, Siwen Feng, Yuhang Jing und Zhiqiang Xie. „Night-Time Light Remote Sensing Mapping: Construction and Analysis of Ethnic Minority Development Index“. Remote Sensing 13, Nr. 11 (28.05.2021): 2129. http://dx.doi.org/10.3390/rs13112129.
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Using toponym data, population data, and night-time light data, we visualized the development index of the Yi, Wa, Zhuang, Naxi, Hani, and Dai ethnic groups on ArcGIS as well as the distribution of 25 ethnic minorities in the study area. First, we extracted the toponym data of 25 ethnic minorities in the study area, combined with night-time light data and the population proportion data of each ethnic group, then we obtained the development index of each ethnic group in the study area. We compared the development indexes of the Yi, Wa, Zhuang, Naxi, Hani, and Dai ethnic groups with higher development indexes. The results show that the Yi nationality’s development index was the highest, reaching 28.86 (with two decimal places), and the Dai nationality’s development index was the lowest (15.22). The areas with the highest minority development index were concentrated in the core area of the minority development, and the size varied with the minority’s distance. According to the distribution of ethnic minorities, we found that the Yi ethnic group was distributed in almost the entire study area, while other ethnic minorities had obvious geographical distribution characteristics, and there were multiple ethnic minorities living together. This research is of great significance to the cultural protection of ethnic minorities, the development of ethnic minorities, and the remote sensing mapping of lights at night.
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KAŽUKAUSKAS, VAIDOTAS, und MINDAUGAS PRANAITIS. „TRAP DISTRIBUTION NEAR THE ENERGY BAND GAP EDGE IN MDMO-PPV“. Functional Materials Letters 04, Nr. 01 (März 2011): 53–56. http://dx.doi.org/10.1142/s1793604711001567.
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Carrier transport and trapping was investigated in poly[2-methoxy-5-(3′,7′-dimethyloctyloxy)-1,4-phenylenevinylene] (MDMO-PPV) layers by thermally stimulated currents (TSC) depending on the exciting light spectral range. The upper edge of the light spectra was varied from 1.77 eV up to 3.1 eV to assure selective excitation of the defect states. We had shown that material conductivity is affected by several thermally activated processes, i.e., carrier generation from trapping states and thermally stimulated mobility growth. If the below band gap excitation was used, the effective photoconductivity activation energy values of 0.13–0.15 eV were obtained. After the above band gap excitation, the effective photoconductivity activation energy values decreased to 0.05 eV. The energy distribution of the trapping state density was shown to follow the Gaussian distribution function. The deeper states with activation energies of 0.28–0.3 eV and 0.8–0.85 eV were identified too. The results are direct indication by photo-thermo-electrical methods of distributed in energy trapping and transport states with the standard deviation of the density of states of about 0.015 eV.
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Tornés, Elisabet, und Sergi Sabater. „Variable discharge alters habitat suitability for benthic algae and cyanobacteria in a forested Mediterranean stream“. Marine and Freshwater Research 61, Nr. 4 (2010): 441. http://dx.doi.org/10.1071/mf09095.
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Large-scale algal community patterns can be understood by studying organisation within patches. Spatial heterogeneity in light and substratum type may affect the biomass and community composition of benthic algae and cyanobacteria. We compared the effects of these factors at the species level in two reaches differing in canopy cover in a forested Mediterranean stream in winter (high water flow) and late spring (low water flow). Partial redundancy analyses revealed that the major determinants of species distribution were strongly associated with variations in measured environmental variables. Light availability, the Reynolds number and substratum type were the main factors accounting for the algal and cyanobacterial distribution. Factors affecting algal distribution varied between hydrological periods, suggesting that some species had specific requirements whereas others had a wider tolerance to environmental conditions. Our results demonstrated that the hydraulic conditions (low velocity v. high velocity) influence small-scale heterogeneity in streams, and that this affects benthic community distribution.
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Pyo, Jeongsang, Hyun Yeol Ryu und Han-Youl Ryu. „Numerical Investigation of Light Extraction Efficiency of GaN-based Vertical Blue Micron-Scale Light-Emitting Diode Structures“. Journal of Nanoscience and Nanotechnology 21, Nr. 3 (01.03.2021): 1869–74. http://dx.doi.org/10.1166/jnn.2021.18944.
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The light extraction efficiency (LEE) of GaN-based vertical blue micron-scale light-emitting diode (μ-LED) structures was investigated numerically using three-dimensional finite-difference timedomain (FDTD) methods. The entire μ-LED chip was included in the FDTD computational domain to determine the LEE accurately. As the lateral dimensions of μ-LEDs increased from 5 to 30 μm, the LEE decreased gradually because of the increased portion of light trapped inside the LED chip and the increased light absorption in the GaN layers with increasing chip size. The LEE varied strongly with the p-GaN thickness for the μ-LED with a flattop surface, which could be explained by the strong dependence of the spatial distribution of the emission patterns on the p-GaN thickness. This dependence on the p-GaN thickness decreased when the surface of the μ-LED chip was patterned. A high LEE of >80% could be achieved in LEDs with properly chosen parameters. The FDTD simulation results presented in this study are expected to be employed advantageously in designing μ-LED structures with a high LEE.
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Uesaka, Tetsu, und Janne Juntunen. „Time-dependent, stochastic failure of paper and box“. Nordic Pulp & Paper Research Journal 27, Nr. 2 (01.05.2012): 370–74. http://dx.doi.org/10.3183/npprj-2012-27-02-p370-374.
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Abstract Time-dependent, stochastic failure is most common in practical situations where paper and board are used, such as web breaks and box failure. A theoretical treatment has been presented, starting from Coleman’s stochastic failure model to the models with structural hierarchy. Creep failure data of box and board published in the literature were analysed from the light of the proposed theoretical model. The results showed that the distribution of life time (not only mean life time) of corrugated boxes changes very sensitively with loading and environmental conditions. Generally the coefficient of variation varied from 6% to 90%. Another important parameter, the load sensitivity of damage growth also varied from 1.7 to 27. Such enormous variation of the key parameters is not a mere fluctuation of experimental condition, but represents the very nature of timedependent, stochastic failure. The stochastic failure model presented provides a framework for analyzing experimental data as well as for predicting life time distributions under general fluctuating loading conditions other than creep.
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Sánchez-Cano, Ana, und Justiniano Aporta. „Optimization of Lighting Projects Including Photopic and Circadian Criteria: A Simplified Action Protocol“. Applied Sciences 10, Nr. 22 (13.11.2020): 8068. http://dx.doi.org/10.3390/app10228068.
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Lighting projects that consider parameters related to circadian light remain rare. Using controlled lighting on both photopic and melanopic levels, this study aims to simplify the design of circadian lighting projects based on traditional photometric parameters and calculations. A real classroom is used to illustrate the behavior of horizontal (visual stimuli) and vertical (circadian contribution) illuminances under different design parameters, such as the varied reflectance of walls, ceiling, and floor; varied spatial distribution curves, including the number and position of luminaires; and across the spectral power distribution of a variety of LEDs. In this work, we seek to clarify and simplify to the greatest possible extent the meaning and scope of various lighting standards while establishing simple protocols. Our results will enable designers to carry out optimized lighting projects from both the photometric and circadian perspectives.
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Tian, Wei-Min, und Zheng-Hai Hu. „DISTRIBUTION AND ULTRASTRUCTURE OF VEGETATIVE STORAGE PROTEINS IN LEGUMINOSAE“. IAWA Journal 25, Nr. 4 (2004): 459–99. http://dx.doi.org/10.1163/22941932-90000378.
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The distribution and ultrastructure of vegetative storage proteins in 44 species and one variety of 31 genera of Leguminosae were investigated by light- and electron microscopy and SDS-PAGE. Leguminosae are as a whole a vegetative storage protein-rich family, abundant with vacuolar protein inclusions in deciduous trees while much less so in evergreen trees. Several prominent proteins with molecular weights ranging from 15 to 45 kDa were isolated and identified to be vegetative storage proteins on the basis of their association with vacuolar protein inclusions and seasonal fluctuation. Vacuolar protein inclusions were present in protein body-like organelles in temperate species while localized in large central vacuoles in tropical ones during leafless periods. The inclusions varied in forms among species or in the same species, but the different forms were present in different cells, suggesting that vegetative storage proteins may be cell-type specific to some extent.
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Khang, Byung-Geun, Jan J. Koenderink und Astrid M. L. Kappers. „Shape from Shading from Images Rendered with Various Surface Types and Light Fields“. Perception 36, Nr. 8 (August 2007): 1191–213. http://dx.doi.org/10.1068/p5807.
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Shape constancy is referred to as the tendency for the perceived shape of an object to remain unchanged even under changed viewing and illumination conditions. We investigated, in two experiments, whether shape constancy would hold for images of 3-D solid objects defined by shading only, whose renderings differed in terms of surface material type (bi-directional reflectance distribution functions), light field, light direction, shape, and specularity. Observers were presented with the image of a sphere or an ellipsoid and required to set perceived orientation and cross-section profile on designated points of the image. Results showed that shape judgments varied with all the aforementioned variables except specularity. Shape estimates were more precise with specular than asperity scattering surfaces, collimated than hemispherical diffuse lighting conditions, lower than higher elevations, spherical than ellipsoidal shapes, but not different between surfaces having differing specularity. These results suggest that shape judgments are made largely on the basis of the overall intensity distribution of shading, and that the portions of intensity distribution that are due to nonstructural variables such as surface material type or light field are not excluded in the process of shape estimation, as if being due to structural components. It is concluded that little constancy is expected in the perception of shape from shading.
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Moore, Eric M., Dimitrios V. Papavassiliou und Robert L. Shambaugh. „Air Velocity, Air Temperature, Fiber Vibration and Fiber Diameter Measurements on a Practical Melt Blowing Die“. International Nonwovens Journal os-13, Nr. 3 (September 2004): 1558925004os—13. http://dx.doi.org/10.1177/1558925004os-1300309.
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Numerous measurements were taken during the operation of a practical melt blowing slot die. On-line measurements were taken of the mean velocity and temperature of the air jets. Also, on-line measurements of fiber vibration amplitude were done. Off-line measurements were taken to determine fiber diameter distributions in the nonwoven webs. The light absorbance of these non-woven mats was measured and related to fiber diameter distribution and mat basis weight. Process conditions were varied across the operating range of the die to produce a variety of finished mats. It was found that the mean air velocity and temperature decayed in a manner similar to that observed in both laboratory-scale melt blowing dies and (more generally) in rectangular jets. Fiber vibrations were found to be strongly dependent on operating temperature and air flow rate. The fiber light absorbance correlated well with the projected area of the fibers present in the mat.
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Liu, Qi, Frank J. Sterck, Jiao-Lin Zhang, Arne Scheire, Evelien Konings, Min Cao, Li-Qing Sha und Lourens Poorter. „Traits, strategies, and niches of liana species in a tropical seasonal rainforest“. Oecologia 196, Nr. 2 (23.05.2021): 499–514. http://dx.doi.org/10.1007/s00442-021-04937-4.
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AbstractPlant functional traits and strategies hold the promise to explain species distribution, but few studies have linked multiple traits to multiple niche dimensions (i.e., light, water, and nutrients). Here, we analyzed for 29 liana species in a Chinese tropical seasonal rainforest how: (1) trait associations and trade-offs lead to different plant strategies; and (2) how these traits shape species’ niche dimensions. Eighteen functional traits related to light, water, and nutrient use were measured and species niche dimensions were quantified using species distribution in a 20-ha plot combined with data on canopy gaps, topographic water availability, and soil nutrients. We found a tissue toughness spectrum ranging from soft to hard tissues along which species also varied from acquisitive to conservative water use, and a resource acquisition spectrum ranging from low to high light capture and nutrient use. Intriguingly, each spectrum partly reflected the conservative–acquisitive paradigm, but at the same time, the tissue toughness and the resource acquisition spectrum were uncoupled. Resource niche dimensions were better predicted by individual traits than by multivariate plant strategies. This suggests that trait components that underlie multivariate strategy axes, rather than the plant strategies themselves determine species distributions. Different traits were important for different niche dimensions. In conclusion, plant functional traits and strategies can indeed explain species distributions, but not in a simple and straight forward way. Although the identification of global plant strategies has significantly advanced the field, this research shows that global, multivariate generalizations are difficult to translate to local conditions, as different components of these strategies are important under different local conditions.
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Mordas, Genrik, Nina Prokopciuk, Steigvilė Byčenkienė, Jelena Andriejauskienė und Vidmantas Ulevicius. „Optical Properties of the Urban Aerosol Particles Obtained from Ground Based Measurements and Satellite-Based Modelling Studies“. Advances in Meteorology 2015 (2015): 1–12. http://dx.doi.org/10.1155/2015/898376.
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Applications of satellite remote sensing data combined with ground measurements and model simulation were applied to study aerosol optical properties as well as aerosol long-range transport under the impact of large scale circulation in the urban environment in Lithuania (Vilnius). Measurements included the light scattering coefficients at 3 wavelengths (450, 550, and 700 nm) measured with an integrating nephelometer and aerosol particle size distribution (0.5–12 μm) and number concentration (Dpa> 0.5 μm) registered by aerodynamic particle sizer. Particle number concentration and mean light scattering coefficient varied from relatively low values of 6.0 cm−3and 12.8 Mm−1associated with air masses passed over Atlantic Ocean to relatively high value of 119 cm−3and 276 Mm−1associated with South-Western air masses. Analysis shows such increase in the aerosol light scattering coefficient (276 Mm−1) during the 3rd of July 2012 was attributed to a major Sahara dust storm. Aerosol size distribution with pronounced coarse particles dominance was attributed to the presence of dust particles, while resuspended dust within the urban environment was not observed.
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FREEMAN, DANIEL K., WALTER F. HEINE und CHRISTOPHER L. PASSAGLIA. „The maintained discharge of rat retinal ganglion cells“. Visual Neuroscience 25, Nr. 4 (Juli 2008): 535–48. http://dx.doi.org/10.1017/s095252380808067x.
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AbstractAction potentials were recorded from rat retinal ganglion cell fibers in the presence of a uniform field, and the maintained discharge pattern was characterized. Spike trains recorded under ketamine–xylazine anesthesia were generally stationary, while those recorded under urethane anesthesia often showed slow, undriven, quasiperiodic fluctuations in firing rate. In light of these nonstationarities, interspike interval distributions and power spectral densities are reported for data collected primarily under ketamine–xylazine. The majority of cells had multimodal interval distributions, with the first peak in the range of 25.0–38.5 ms and the subsequent peaks occurring at integer multiples of the first peak. Cells with unimodal distributions were fit well by a gamma distribution function. Interval and spike count statistics showed that ON cells tended to fire faster than OFF cells and that cells with higher rates fired in a more regular manner, with the coefficient of variation covering a wide range of values across all cells (0.43–0.97). Both ON and OFF cells show serial correlations between adjacent interspike intervals, while ON cells also showed second-order correlations. Cells with multimodal interval distribution showed a strong peak at high frequencies in the power spectra in the range of 28.9–41.4 Hz. Oscillations were present under both anesthetic conditions and persisted in the dark at a slightly lower frequency, implying that the oscillations are generated independent of any light stimulus but can be modulated by light level. The oscillation frequency varied slightly between cells of the same type and in the same eye, suggesting that multiple oscillatory generating mechanisms exist within the retina. Cells with high-frequency oscillations were described well by an integrate-and-fire model with the input consisting of Gaussian noise plus a sinusoid where the phase was jittered randomly to account for the bandwidth present in the oscillations.
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Lee, I., Y. Ono, N. Kubushiro, T. Ikeda und M. Takagi. „The Nature and Distribution of Large Proteoglycans in Developing Rat Bone.“ Microscopy and Microanalysis 3, S2 (August 1997): 193–94. http://dx.doi.org/10.1017/s1431927600007856.
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The nature and distribution of large hyaluronate-binding proteoglycans (PGs) in early bone formation bf developing rat mandible were biochemically and immunohistochemically investigated with a monoclonal antibody (MAb) 5D5, which is derived from bovine sciera and specifically recognizes the core protein of the large PGs such as versican, neurocan and brevican, but not that of aggrecan.The first sign of mandibular bone formation is evident in the embryonic day 15 (Day 15). At the site of initiation of bone formation, a center of ossification was seen in the close proximity to Meckel’s cartilage. At the light microscopic level, these centers contained fine strips of the intercellular matrix surrounded by osteoblasts (Fig. 1). At the EM level, these matrices contained very fine fibrillar material, numerous, osteoblastic cell processes, and vesicular structures, but did not show any typical mineralization pattern. In Day 16, clusters of needle-like crystals or bone nodules, which varied considerably in size and shape, were seen in the intercellular matrix among osteoblasts (Fig. 2).
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Alfaro, Rene I., und Cheng C. Ying. „LEVELS OF SITKA SPRUCE WEEVIL, PISSODES STROBI (PECK), DAMAGE AMONG SITKA SPRUCE PROVENANCES AND FAMILIES NEAR SAYWARD, BRITISH COLUMBIA“. Canadian Entomologist 122, Nr. 4 (August 1990): 607–15. http://dx.doi.org/10.4039/ent122607-7.
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AbstractVariation in tree height, number of attacks by the Sitka spruce weevil (= white pine weevil) (Pissodes strobi [Peck]), tree form, and stem defect were studied in a 15-year-old Sitka spruce (Picea sitchensis [Bong.] Carr.) provenance test near Sayward, on Vancouver Island, B.C. An aggregated spatial distribution of the attacks was found in the plantation. Average number of attacks, tree form, and total tree height varied significantly among provenances and among families within provenances in both light and severe infestation patches. The number of unattacked trees varied by provenance from 5 to 51%, but in patches of severe infestation it varied from 0 to 64%. The number of attacks per tree had a significant negative effect on tree height. However, at the same level of attack, some provenances grew significantly taller than others. Thirty, 19, and 51% of all trees were classified as having a good, medium, or poor form, respectively. Among provenances located in severe infestation patches, the percentages of trees having good form varied from 4 to 64%. The type of defect that formed after an attack (minor crook, major crook, or fork) varied by provenance. Aggregated weevil attack and genetic differences among provenances may have accounted for this variation.
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RICARD, MICHELLE, GILLES M. DORRIS, NATALIE PAGÉ und DENISE FILION. „Online analysis of macrostickies in a sorted office waste recycling plant making tissue“. April 2014 13, Nr. 4 (01.05.2014): 47–55. http://dx.doi.org/10.32964/tj13.4.47.
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An online macrocontaminant analyzer, the FPAutoSpeck, was used for 8000 measurements of deinked pulp to determine the number and area of heavy stickies, light macrocontaminants, and dirt. The analyzer detected a wide range of macrocontaminant levels, during which the three types of macrocontaminants varied independently of each other. “Stickies storm” levels were detected and visualized by the analyzer, with heavy stickies levels exceeding 17000/kg in the final pulp. Different particle size distribution patterns were noted for the light macrocontaminants when compared to those obtained for heavy stickies and dirt. Mill surveys of the fine screens and flotation cell showed different removal efficiencies for heavy stickies and light macrocontaminants. Fine screening was slightly more efficient in the removal of heavy stickies than of light macrocontaminants. Fine screens were more efficient at removing heavy stickies with particle sizes larger than 400 μm in diameter. On the other hand, flotation could remove heavy stickies with particle sizes of 200-300 μm. Furthermore, flotation was able to remove most of the light macrocontaminants independent of their particle size.
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Sakai, E. H. „Measurement and Visualization of the Contact Pressure Distribution of Rubber Disks and Tires“. Tire Science and Technology 23, Nr. 4 (01.10.1995): 238–55. http://dx.doi.org/10.2346/1.2137506.
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Abstract The contact conditions of a tire with the road surface have a close relationship to various properties of the tire and are among the most important characteristics in evaluating the performance of the tire. In this research, a new measurement device was developed that allows the contact stress distribution to be quantified and visualized. The measuring principle of this device is that the light absorption at the interface between an optical prism and an evenly ground or worn rubber surface is a function of contact pressure. The light absorption can be measured at a number of points on the surface to obtain the pressure distribution. Using this device, the contact pressure distribution of a rubber disk loaded against a plate was measured. It was found that the pressure distribution was not flat but varied greatly depending upon the height and diameter of the rubber disk. The variation can be explained by a “spring” effect, a “liquid” effect, and an “edge” effect of the rubber disk. Next, the measurement and image processing techniques were applied to a loaded tire. A very high definition image was obtained that displayed the true contact area, the shape of the area, and the pressure distribution from which irregular wear was easily detected. Finally, the deformation of the contact area and changes in the pressure distribution in the tread rubber block were measured when a lateral force was applied to the loaded tire.
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Huang, Shu Ping, Xuan Mao Peng, Qi Ling, Yi Hua Dai und Cheng Peng Du. „Genetic Analysis of Concrete Crack in Hydroelectric Station's Plant Based on FEM“. Key Engineering Materials 340-341 (Juni 2007): 1163–68. http://dx.doi.org/10.4028/www.scientific.net/kem.340-341.1163.
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This study is mainly in temperature-control and anti-cracking of plant concrete in hydroelectric station. By means of FEM of three-dimension thermal creep stress and imitating construction progress, an emulator calculation is performed from construction period to operation period and distribution regularity of thermal creep stress is brought to light in the theory. The text described the developing process of concrete’s temperature and thermal stress, and then combined concrete’s time-varied thermotics and mechanics performance to analyze the possibility of yielding crack in different period and position.
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Alves, Eliane Gomes, Peter Harley, José Francisco de C. Gonçalves, Carlos Eduardo da Silva Moura und Kolby Jardine. „Effects of light and temperature on isoprene emission at different leaf developmental stages of eschweilera coriacea in central Amazon“. Acta Amazonica 44, Nr. 1 (2014): 9–18. http://dx.doi.org/10.1590/s0044-59672014000100002.
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Isoprene emission from plants accounts for about one third of annual global volatile organic compound emissions. The largest source of isoprene for the global atmosphere is the Amazon Basin. This study aimed to identify and quantify the isoprene emission and photosynthesis at different levels of light intensity and leaf temperature, in three phenological phases (young mature leaf, old mature leaf and senescent leaf) of Eschweilera coriacea (Matamatá verdadeira), the species with the widest distribution in the central Amazon. In situ photosynthesis and isoprene emission measurements showed that young mature leaf had the highest rates at all light intensities and leaf temperatures. Additionally, it was observed that isoprene emission capacity (Es) changed considerably over different leaf ages. This suggests that aging leads to a reduction of both leaf photosynthetic activity and isoprene production and emission. The algorithm of Guenther et al. (1999) provided good fits to the data when incident light was varied, however differences among E S of all leaf ages influenced on quantic yield predicted by model. When leaf temperature was varied, algorithm prediction was not satisfactory for temperature higher than ~40 °C; this could be because our data did not show isoprene temperature optimum up to 45 °C. Our results are consistent with the hypothesis of the isoprene functional role in protecting plants from high temperatures and highlight the need to include leaf phenology effects in isoprene emission models.
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Barbosa, Hélder M. C., und Marta M. D. Ramos. „Computer Simulation of Hole Distribution in Polymeric Materials“. Materials Science Forum 587-588 (Juni 2008): 711–15. http://dx.doi.org/10.4028/www.scientific.net/msf.587-588.711.
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Polymers have been known for their flexibility and easy processing into coatings and films, which made them suitable to be applied in a variety of areas and in particular the growing area of organic electronics. The electronic properties of semiconducting polymers made them a serious rival in areas where until now inorganic materials were the most used, such as light emitting diodes or solar cells. Typical polymers can be seen as a network of molecular strands of varied lengths and orientations, with a random distribution of physical and chemical defects which makes them an anisotropic material. To further increase their performance, a better understanding of all aspects related to charge transport and space charge distribution in polymeric materials is required. The process associated with charge transport depends on the properties of the polymer molecules as well as connectivity and texture, and so we adopt a mesoscopic approach to build polymer structures. Changing the potential barrier for charge injection we can introduce holes in the polymer network and, by using a generalised Monte-Carlo method, we can simulate the transport of the injected charge through the polymer layer caused by imposing a voltage between two planar electrodes. Our results show that the way that holes distribute within polymer layer and charge localization in these materials is quite different from the inorganic ones.
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Caumo, Sofia, Roy E. Bruns und Pérola C. Vasconcellos. „Variation of the Distribution of Atmospheric n-Alkanes Emitted by Different Fuels’ Combustion“. Atmosphere 11, Nr. 6 (16.06.2020): 643. http://dx.doi.org/10.3390/atmos11060643.
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This study presents the emission profiles of n-alkanes for different vehicular sources in two Brazilian cities. Atmospheric particulate matter was collected in São Paulo (Southeast) and in Salvador (Northeast) to determine n-alkanes. The sites were impacted by bus emissions and heavy and light-duty vehicles. The objective of the present study is to attempt to differentiate the profile of n-alkane emissions for particulate matter (PM) collected at different sites. PM concentrations ranged between 73 and 488 µg m−3, and the highest concentration corresponded to a tunnel for light and heavy duty vehicles. At sites where diesel-fueled vehicles are dominant, the n-alkanes show a unimodal distribution, which is different from the bimodal profile observed in the literature. Carbon preference index values corresponded to anthropogenic sources for most of the sites, as expected, but Cmax varied comparing to literature and a source signature was difficult to observe. The main sources to air pollution were indicated by principal component analysis (PCA). For PCA, a receptor model often used as an exploratory tool to identify the major sources of air pollutant emissions, the principal factors were attributed to mixed sources and to bus emissions. Chromatograms of four specific samples showed distinct profiles of unresolved complex mixtures (UCM), indicating different contributions of contamination from petroleum or fossil fuel residues, which are unable to resolve by gas chromatography. The UCM area seemed higher in samples collected at sites with the abundance of heavy vehicles.
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Ilie, N., und BI Luca. „Efficacy of Modern Light Curing Units in Polymerizing Peripheral Zones in Simulated Large Bulk-fill Resin-composite Fillings“. Operative Dentistry 43, Nr. 4 (01.07.2018): 416–25. http://dx.doi.org/10.2341/17-095-l.
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SUMMARY The variation in micro-hardness (HV) within simulated large cavities (10 × 6 mm) filled in one increment with three bulk-fill resin-based composites (BF-RBC) was assessed by means of a universal hardness device. Modern blue and violet-blue light curing units (LCUs) were applied in three different positions, by rotating the LCU in 120° steps. The exposure distance was 3 mm. One center and two peripheral (4-mm apart from the center) HV line profiles were measured in 0.5-mm steps at 24 hours postpolymerization to calculate the depth of cure (DOC). Incident light, irradiance, and spectral distribution were recorded. A multivariate analysis (general linear model) assessed the effect of the varied parameters as well as their interaction terms on HV and DOC. The effect of LCU rotation was not significant (p=0.109). The DOC varied between 3.46 mm and 5.50 mm and was more strongly influenced by the BF-RBC (p<0.001, ηP2=0.774), followed by the width of specimen (p<0.001, ηP2=0.554), while the influence of the LCU was very low (p<0.06, ηP2=0.070). Whether a BF-RBC filling is cured as well in the periphery as in the center depends more on the material than on the curing unit used.
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Moiseeva, N. A., T. Ya Churilova, T. V. Efimova, V. A. Artemiev und E. Yu Skorokhod. „Spectral bio-optical properties of water of Atlantic sector of Antarctic“. Marine Biological Journal 5, Nr. 4 (30.12.2020): 69–78. http://dx.doi.org/10.21072/mbj.2020.05.4.06.
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Studies of variability of spectral bio-optical properties of water of Atlantic sector of Antarctic were carried out during the 79th cruise of the RV “Akademik Mstislav Keldysh” (11.01.2020–04.02.2020). Chlorophyll a and phaeopigment concentration varied in the layer studied from 0.1 to 1.8 mg·m−3, except for two stations with content reaching 2.2 and 4.4 mg·m−3. The relationship was revealed between light absorption coefficient by phytoplankton and chlorophyll a concentration at a wavelength, corresponding to spectrum maxima: aph(438) = 0.044 × Ca1.2, r2 = 0.84 (n = 117); aph(678) = 0.021 × Ca1.1, r2 = 0.89 (n = 117). Spectral distribution of light absorption coefficient by non-algal particles and colored dissolved organic matter was described by exponential function. Absorption parameterization coefficients were retrieved: (1) light absorption coefficient by non-algal particles (0.001–0.027 m−1) and by colored dissolved organic matter (0.016–0.19 m−1) at a wavelength of 438 nm; (2) spectral slope coefficients of these components (0.005–0.016 and 0.009–0.022 nm−1, respectively).
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Peroni, F. H. G., T. S. Rocha und C. M. L. Franco. „Some Structural and Physicochemical Characteristics of Tuber and Root Starches“. Food Science and Technology International 12, Nr. 6 (Dezember 2006): 505–13. http://dx.doi.org/10.1177/1082013206073045.
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Starches from six different species (cassava, arrowroot, sweet potato, yam, canna and ginger) were isolated and some structural and physicochemical characteristics analysed and correlated. Phosphorous and amylose contents were determined using a colorimetric method and measuring iodine affinity, respectively. Molecular weight distributions of starches were analysed by Sepharose CL 2B. Granular shape and size distribution were performed using an image analyser system attached to a light microscope. Swelling power was determined at 60, 70, 80 and 90°C. Pasting and thermal properties were measured using a rapid viscoanalyser, and a differential scanning calorimeter, respectively. Phosphorous content varied from 0.007 to 0.031% for cassava and canna starches, respectively. Yam, canna and ginger starches displayed higher amylose contents (32.6, 31.7 and 26.5%, respectively) than cassava, arrowroot and sweet potato starches (19.8, 20.8 and 22.6%, respectively). These last three starches displayed amylose molecules of higher molecular weight than those shown for yam, canna and ginger starches. Canna starch showed higher proportions of longer branch chains of amylopectin than others starches. The size and shape of granules were quite variable among all starches and the average size of granules varied from 13.9 to 42.3μ for sweet potato and canna, respectively. Swelling power, pasting, and thermal properties were affected by structural characteristics of the starches.
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Rybakova (Goroslavskaya), E., S. Galkin, M. Bergmann, T. Soltwedel und A. Gebruk. „Density and distribution of megafauna at the Håkon Mosby Mud Volcano (the Barents Sea) based on image analysis“. Biogeosciences Discussions 9, Nr. 12 (10.12.2012): 17475–517. http://dx.doi.org/10.5194/bgd-9-17475-2012.
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Abstract. During a survey of the Håkon Mosby Mud Volcano (HMMV), located on the Bear Island Fan in the southwest Barents Sea at ~ 1250 m water depth, different habitats inside the volcano caldera and outside it were photographed using a towed camera platform, an Ocean Floor Observation System (OFOS). Three transects were performed across the caldera and one outside, in the background area, each transect was ~ 2 km in length. We compared the density, taxa richness and diversity of non-symbiotrophic megafauna in areas inside the volcano caldera with different bacterial mat and pogonophoran tubeworm cover. Significant variations in megafaunal composition, density and distribution were found between considered areas. Total megafaunal density was highest in areas of dense pogonophoran populations (mean 52.9 ind. m−2) followed by areas of plain light-coloured sediment that were devoid of bacterial mats and tubeworms (mean 37.7 ind. m−2). The lowest densities were recorded in areas of dense bacterial mats (mean ≤ 1.4 ind. m−2). Five taxa contributed to most of the observed variation: the ophiuroid Ophiocten gracilis, lysianassid amphipods, the pycnogonid Nymphon macronix, the caprellid Metacaprella horrida and the fish Lycodes squamiventer. In agreement with previous studies, three zones within the HMMV caldera were distinguished, based on different habitats and megafaunal composition: "bacterial mats", "pogonophoran fields" and "plain light-coloured sediments". The zones were arranged almost concentrically around the central part of the caldera that was devoid of visible megafauna. The total number of taxa showed little variation inside (24 spp.) and outside the caldera (26 spp.). The density, diversity and composition of megafauna varied substantially between plain light-coloured sediment areas inside the caldera and the HMMV background. Megafaunal density was lower in the background (mean 25.3 ind. m−2) compared to areas of plain light-coloured sediments inside the caldera.
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Uddin, MJ, MK Hasan, ASM Mohiuddin, SU Ahmed und MM Hassan. „Study of some soils of the Himalayan piedmont plain of Bangladesh“. Journal of the Asiatic Society of Bangladesh, Science 38, Nr. 2 (07.07.2013): 199–206. http://dx.doi.org/10.3329/jasbs.v38i2.15610.
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Results of four representative pedons of the Old Himalayan piedmont, collected horizonwise from Thakurgaon district, revealed that the color of the topsoil was dark grayish brown to dark yellowish brown and that of the subsoils was dark yellowish brown to light olive-brown and light brownish grey when moist. The soils have moderately well drained conditions except Baliadangi soils which are imperfectly drained. Prismatic to subangular blocky structure has been developed in subsurface horizons of all the profiles, whereas massive structure was found in the surface horizons. Sand was by far the dominant fraction in the soils. The texture of the soils varied from clay loam to sandy loam. The irregular vertical distribution patterns of sand/silt ratio in the profiles indicate the heterogeneous nature of the parent materials. The pH of the soils ranged from 5.4 to 6.26. The organic matter contents as well as total nitrogen of these soils were, in general, low. The C/N ratios of the soils varied from 4.3 to 10.3. The cation exchange capacity (CEC) in most of the studied soils were low. Calcium and magnesium were the dominant cations in all the soils. DOI: http://dx.doi.org/10.3329/jasbs.v38i2.15610 J. Asiat. Soc. Bangladesh, Sci. 38(2): 199-206, December 2012
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Soborski, Rafal. „Biopolitics in the Time of Pandemic: Populism and Neoliberalism in the Light of COVID-19“. Perspectives on Global Development and Technology 20, Nr. 1-2 (25.03.2021): 137–50. http://dx.doi.org/10.1163/15691497-12341587.
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Abstract Populism is at the center of many debates about socio-political aspects of the COVID-19 pandemic. However, pondering questions such as, “Is coronavirus bad for populism?” or “How do populist leaders respond to it?” is unlikely to bring significant insights into the distribution and operation of power in the context of COVID-19, or more generally. The populist label is used by elites to describe any politics that they dismiss, whether right- or left-wing, rendering populism an empty and incoherent concept. This point is supported by developments associated with COVID-19 as attitudes of “populist” regimes towards the pandemic varied and some of them followed the same strategies as those pursued by “non-populist” governments. This article reveals the limited explanatory utility of the concept of populism and proposes shifting the focus of attention towards neoliberalism as a key factor shaping individual countries’ responses to the ongoing biopolitical challenge.
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Karshima, Solomon Ngutor, Idris A. Lawal und Oluseyi Oluyinka Okubanjo. „Feeding Patterns and Xenomonitoring of Trypanosomes among Tsetse Flies around the Gashaka-Gumti National Park in Nigeria“. Journal of Parasitology Research 2016 (2016): 1–6. http://dx.doi.org/10.1155/2016/1591037.
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In order to understand the epidemiology of trypanosomoses in Gashaka-Gumti National Park, Nigeria, we determined the density, infection rates, and feeding patterns of tsetse flies using biconical traps, ITS, and mitochondrial cytochrome b PCRs. A total of 631 tsetse flies were captured, of which 531 (84.2%) and 100 (15.8%) were analyzed for trypanosomes and blood meals, respectively. Tsetse distribution varied significantly (p<0.05) across study sites with average trap and daily catches of 4.39 and 26.34, respectively. Overall tsetse infection rate was 5.08% and ranged between 3.03% and 6.84% across study sites. We identified 10T. brucei, 3T. congolense savannah,2T. congolense forest, and 2 mixed infections among the 13 pools made from the 27 flies positive for trypanosomes with light microscopy. The distribution of vertebrate blood meals in tsetse flies varied significantly (p<0.05) and ranged between 6.0% and 45% across hosts. We also observed dual feeding patterns involving at least 2 hosts in 24% and multiple feeding involving at least 3 hosts in 17% of the flies. We observed predominance ofG. palpaliswhich also recorded higher infection rate.T. bruceiwas more prevalent among tsetse flies. Tsetse flies fed predominantly on cattle and less frequently on humans and also showed mixed feeding habits.
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Dawson, H. J., und E. Fouksman. „Labour, laziness and distribution: work imaginaries among the South African unemployed“. Africa 90, Nr. 2 (Februar 2020): 229–51. http://dx.doi.org/10.1017/s0001972019001037.
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AbstractA wealth of new writing has emerged around the future of labour, focusing on thinking beyond employment in imagining the futures of ‘surplus populations’ no longer needed by labour markets. These new imaginaries include radically expanded forms of redistribution, such as unconditional cash transfers or universal basic income. But what are the views of the ‘surplus populations’ themselves? This article uses ethnographic research in an informal settlement in South Africa to understand why the unemployed or precariously employed poor are themselves often reluctant to delink labour and income. In particular, we focus on the discursive use of ‘laziness’ by urban unemployed young men. The varied (and often contradictory) ways in which these men employ the laziness discourse sheds light on the logics linking waged work and money in our informants’ social imaginaries. It illuminates the underlying contradictions and complexities of such logics, including those of gender, relational obligations, expectations of citizenship, and the inevitable tensions between aspirational hopes and economic realities. To begin thinking ‘beyond the proper job’, to use Ferguson and Li's phrase, we must unravel and understand such nuanced logics that continue to bind together hard work, deservingness and cash – even for those left out of labour markets.
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Sawasdee, Komkrich, Ployphailin Choksawad, Sopida Pimcharoen und Kanlaya Prapainop. „Development of size-tunable polymeric nanoparticles for drug delivery applications“. GHMJ (Global Health Management Journal) 1, Nr. 2 (31.10.2017): 31. http://dx.doi.org/10.35898/ghmj-12113.
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Background: Poly(lactide-co-glycolide) (PLGA) nanoparticles (NPs) have been widely used in drug delivery applications because of its excellent properties such as biocompatibility, biodegradability along with its abilities to deliver hydrophobic drugs, increase drug bioavailability, and improve drug absorption to targeted cells in both oral and parenteral administrations. The PLGA NPs can be synthesized using emulsion solvent evaporation method. Each parameter during synthesis play a role in formation of nanoparticles and could affect to form different NP sizes which is an important factor for successful development of drug delivery system. Aims: The aim of this study is to prepare different sizes of PLGA NPs by investigation of four factors (molecular weight (MW) of PLGA, emulsifier concentrations, organic solvent type and power of ultrasonication) that involve in PLGA nanoparticle synthesis.Methods: PLGA nanoparticles were prepared by emulsion solvent evaporation method. Size and size distribution were analyzed by dynamic light scattering and polydispersity index (PdI).Results: The effect of four parameters: PLGA MW, emulsifier concentrations, solvent types, and amplitude of ultrasonication on PLGA NPs preparation were evaluated. Changing one parameter results in different sizes of PLGA NPs varied from 150-300 nm. PdI which is an indicator for determination of size distribution of NPs are also varied with overall value less than 0.2.Conclusion: MW of PLGA polymer, emulsifier concentration, type of organic solvent and power of ultrasonication affect the size and size distribution of PLGA NPs.
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Aubin, Isabelle, Marilou Beaudet und Christian Messier. „Light extinction coefficients specific to the understory vegetation of the southern boreal forest, Quebec“. Canadian Journal of Forest Research 30, Nr. 1 (01.02.2000): 168–77. http://dx.doi.org/10.1139/x99-185.
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This study was conducted in six different forest types in Abitibi, Que., (i) to identify the factors that most influence understory light transmission in the southern boreal forest and (ii) to develop light extinction coefficients (k), which could be used to simulate light transmission in the understory. Light availability and understory vegetation (cover, composition, vertical distribution, and leaf area index) were characterized within three strata (0.05-5 m) in a total of 180 quadrats. Calculated k values were based on measured light availability and leaf area index. These values varied among forest types, strata, understory vegetation types, and cover in the upper stratum. The highest k values were generally associated with a dense stratum of Acer spicatum Lam. We developed five sets of k values based on the factors that most affected light transmission. Measured transmission (Tm) was compared with transmission predicted (Tp) from each set of k values. Light transmission predicted using a single k value (mean k = 0.54) underestimated Tm. More accurate predictions were obtained when we used the other four sets of k values. Our results indicate that, in the southern boreal forest, the understory vegetation can be quite heterogeneous and patterns of light transmission cannot be accurately simulated using a unique k value. However, the various sets of k values developed in this study could be used in prediction models of forest dynamics to obtain relatively good predictions of understory light extinction in forest types similar to the ones studied here.
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Rybakova (Goroslavskaya), E., S. Galkin, M. Bergmann, T. Soltwedel und A. Gebruk. „Density and distribution of megafauna at the Håkon Mosby mud volcano (the Barents Sea) based on image analysis“. Biogeosciences 10, Nr. 5 (21.05.2013): 3359–74. http://dx.doi.org/10.5194/bg-10-3359-2013.
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Abstract. During a survey of the Håkon Mosby mud volcano (HMMV), located on the Bear Island fan in the southwest Barents Sea at ∼1250 m water depth, different habitats inside the volcano caldera and outside it were photographed using a towed camera platform, an Ocean Floor Observation System (OFOS). Three transects were performed across the caldera and one outside, in the background area, each transect was ∼2 km in length. We compared the density, taxa richness and diversity of nonsymbiotrophic megafauna in areas inside the volcano caldera with different bacterial mat and pogonophoran tubeworm cover. Significant variations in megafaunal composition, density and distribution were found between considered areas. Total megafaunal density was highest in areas of dense pogonophoran populations (mean 52.9 ind. m−2) followed by areas of plain light-coloured sediment that were devoid of bacterial mats and tube worms (mean 37.7 ind. m−2). The lowest densities were recorded in areas of dense bacterial mats (mean ≤1.4 ind. m−2). Five taxa contributed to most of the observed variation: the ophiuroid Ophiocten gracilis, lysianassid amphipods, the pycnogonid Nymphon macronix, the caprellid Metacaprella horrida and the fish Lycodes squamiventer. In agreement with previous studies, three zones within the HMMV caldera were distinguished, based on different habitats and megafaunal composition: "bacterial mats", "pogonophoran fields" and "plain light-coloured sediments". The zones were arranged almost concentrically around the central part of the caldera that was devoid of visible megafauna. The total number of taxa showed little variation inside (24 spp.) and outside the caldera (26 spp.). The density, diversity and composition of megafauna varied substantially between plain light-coloured sediment areas inside the caldera and the HMMV background. Megafaunal density was lower in the background (mean 25.3 ind. m−2) compared to areas of plain light-coloured sediments inside the caldera. So the effect of the mud-volcano environment on benthic communities is expressed in increasing of biomass, changing of taxa composition and proportions of most taxonomic groups.
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Zhou, Haoran, Brent R. Helliker, Matthew Huber, Ashley Dicks und Erol Akçay. „C4 photosynthesis and climate through the lens of optimality“. Proceedings of the National Academy of Sciences 115, Nr. 47 (06.11.2018): 12057–62. http://dx.doi.org/10.1073/pnas.1718988115.
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CO2, temperature, water availability, and light intensity were all potential selective pressures that determined the competitive advantage and expansion of the C4 photosynthetic carbon-concentrating mechanism over the last ∼30 My. To tease apart how selective pressures varied along the ecological trajectory of C4 expansion and dominance, we coupled hydraulics to photosynthesis models while optimizing photosynthesis over stomatal resistance and leaf/fine-root allocation. We further examined the importance of nitrogen reallocation from the dark to the light reactions. We show here that the primary selective pressures favoring C4 dominance changed through the course of C4 evolution. The higher stomatal resistance and leaf-to-root ratios enabled by C4 led to an advantage without any initial difference in hydraulic properties. We further predict a reorganization of the hydraulic system leading to higher turgor-loss points and possibly lower hydraulic conductance. Selection on nitrogen reallocation varied with CO2 concentration. Through paleoclimate model simulations, we find that water limitation was the primary driver for a C4 advantage, with atmospheric CO2 as high as 600 ppm, thus confirming molecular-based estimates for C4 evolution in the Oligocene. Under these high-CO2 conditions, nitrogen reallocation was necessary. Low CO2 and high light, but not nitrogen reallocation, were the primary drivers for the mid- to late-Miocene global expansion of C4. We also predicted the timing and spatial distribution for origins of C4 ecological dominance. The predicted origins are broadly consistent with prior estimates, but expand upon them to include a center of origin in northwest Africa and a Miocene-long origin in Australia.
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Lorenc-Plucińska, Gabriela, und Hubert Ziegler. „Inhibition of phloem loading by sulfite affects sugar distribution in pea leaves“. Acta Societatis Botanicorum Poloniae 62, Nr. 3-4 (2014): 175–78. http://dx.doi.org/10.5586/asbp.1993.027.
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Under the influence of sulfite, changes in the rate of <sup>14</sup>CO<sub>2</sub> fixation, <sup>14</sup>C-sucrose uptake and sugar content of the apoplastic and intracellular spaces of pea leaves varied according to the time of treatment and the anion concentration used. The greatest decrease of the rate of <sup>14</sup>CO<sub>2</sub> and <sup>14</sup>C-sucrose uptake in the presence of sulfite at concentrations from 0.1 to 5.0 mM was detected immediately (i.e. 5 min.) after supplying sulfite to the medium. Two hours later, a significant inhibition of photosynthesis and sucrose uptake was observed only with 5.0 and 2.5 and 5.0 mM concentrations of sulfite, respectively. The effect of sulfite (0.1-5.0 mM) on the apoplastic and intracellular sugar content for the first 30 min of treatment was negligible. However, after longer periods under sulfite treatment at concentrations ≥ 1.0 mM, significant increases in the apoplastic sucrose content were observed. An increase in the accumulation of starch was also noted. In light of our observations it suggested that the inhibition of phloem loading by sulfite induces disturbances in sugar distribution.
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Ritter, Thomas, Sven Wiegärtner, Gunter Hagen und Ralf Moos. „Simulation of a thermoelectric gas sensor that determines hydrocarbon concentrations in exhausts and the light-off temperature of catalyst materials“. Journal of Sensors and Sensor Systems 6, Nr. 2 (22.12.2017): 395–405. http://dx.doi.org/10.5194/jsss-6-395-2017.
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Abstract. Catalyst materials can be characterized with a thermoelectric gas sensor. Screen-printed thermopiles measure the temperature difference between an inert part of the planar sensor and a part that is coated with the catalyst material to be analyzed. If the overall sensor temperature is modulated, the catalytic activity of the material can be varied. Exothermic reactions that occur at the catalyst layer cause a temperature increase that can then be measured as a sensor voltage due to the Seebeck coefficient of the thermopiles. This mechanism can also be employed at stationary conditions at constant sensor temperature to measure gas concentrations. Then, the sensor signal changes linearly with the analyte concentration. Many variables influence the sensing performance, for example, the offset voltage due to asymmetric inflow and the resulting inhomogeneous temperature distributions are an issue. For even better understanding of the whole sensing principle, it is simulated in this study by a 3-D finite element model. By coupling all influencing physical effects (fluid flow, gas diffusion, heat transfer, chemical reactions, and electrical properties) a model was set up that is able to mirror the sensor behavior precisely, as the comparison with experimental data shows. A challenging task was to mesh the geometry due to scaling problems regarding the resolution of the thin catalyst layer in the much larger gas tube. Therefore, a coupling of a 3-D and a 1-D geometry is shown. This enables to calculate the overall temperature distribution, fluid flow, and gas concentration distribution in the 3-D model, while a very accurate calculation of the chemical reactions is possible in a 1-D dimension. This work does not only give insight into the results at stationary conditions for varying feed gas concentrations and used substrate materials but shows also how various exhaust gas species behave under transient temperature modulation.
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Khonina, Svetlana N., und Andrey V. Ustinov. „Analyzing the Symmetry Properties of a Distribution in the Focal Plane for a Focusing Element with Periodic Angle Dependence of Phase“. Advances in Optical Technologies 2012 (10.10.2012): 1–7. http://dx.doi.org/10.1155/2012/918298.
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We analyze the symmetry properties of the focal plane distribution when light is focused with an element characterized by a periodic angular dependent phase, sin (mφ) or cos (mφ). The majority of wave aberrations can be described using the said phase function. The focal distribution is analytically shown to be a real function at odd values of m, which provides a simple technique for generating designed wave aberrations by means of binary diffractive optical elements. Such a possibility may prove useful in tight focusing, as the presence of definite wave aberrations allows the focal spot size to be decreased. The analytical computations are illustrated by the numerical simulation, which shows that by varying the radial parameters the focal spot configuration can be varied, whereas the central part symmetry is mainly determined by the parity of m: for even the symmetry order is 2m and for odd is m.
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Miller, Rebecca E., Roslyn M. Gleadow und Ian E. Woodrow. „Cyanogenesis in tropical Prunus turneriana: characterisation, variation and response to low light“. Functional Plant Biology 31, Nr. 5 (2004): 491. http://dx.doi.org/10.1071/fp03218.
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This study characterised three aspects of cyanogenesis in the late successional tropical rainforest species Prunus turneriana (F.M.Bailey) Kalkman. First, all tissues were found to be highly cyanogenic, containing combinations of the cyanogenic glycosides (R)-prunasin, (S)-sambunigrin, and amygdalin. Second, the progeny of a single parent tree varied markedly and continuously in their cyanogenic glycoside content, indicating that this variation is genetically based. Third, we investigated resource allocation to cyanogenic glycosides in light treatments representative of rainforest understorey and gap environments. Contrary to our hypothesis that under low light, photosynthetic gain would be maximised by the reallocation of nitrogen from defence to the photosynthetic system, we found no difference in cyanogenic glycoside concentration, or the proportion of nitrogen allocated to cyanogenic glycoside, between high and low light. However, within the plant, shade affected a significant change in distribution of cyanogenic glycosides between young and old leaves. There was an increased allocation of cyanogenic glycosides to old, expanded and photosynthetically productive leaves, a pattern which appears inconsistent with predictions of optimal defence theories, and the results of other studies. We suggest that such a strategy may be advantageous for seedlings of tree species that can only reach a reproductive stage following the creation of a canopy gap.
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Backman, J., L. V. Rizzo, J. Hakala, T. Nieminen, H. E. Manninen, F. Morais, P. P. Aalto et al. „The variability of urban aerosol size distributions and optical properties in São Paulo – Brazil: new particle formation events occur at the site“. Atmospheric Chemistry and Physics Discussions 11, Nr. 11 (11.11.2011): 30419–55. http://dx.doi.org/10.5194/acpd-11-30419-2011.
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Abstract. The quest to reduce the dependence on fossil fuel has increased the use of bio-ethanol as an additive to gasoline. The metropolitan area of São Paulo (population 20 million) is a unique laboratory to study the ambient aerosol population caused by the use of bio-fuels because 55% of the fuel used is ethanol. The use of ethanol as an additive to fossil fuel is known to increase aldehyde emissions and when photo chemically oxidized, result in smog. In order to characterize this smog problem total particle number concentration, particle number size distribution, light scattering and light absorption measurement equipment were deployed at the University of São Paulo campus area. Here we present the results from three months of measurements from 10 October 2010 to 10 January 2011. The median total particle number concentration for the sub-micron aerosol typically varies between 1×104–3×104 cm−3 frequently exceeding 5×104 cm−3 during the day. Median diurnal values for light absorption and light scattering vary between 12–33 Mm−1 and 21–64 Mm−1, respectively. The hourly median single-scattering albedo varied between 0.63 and 0.85 indicating a net warming effect on a regional scale. A total of ten new particle formation (NPF) events were observed. During these events, growth rates ranged between 9–25 nm h−1. On average, a calculated sulphuric acid vapour abundance of 2.6× 108 cm−3 would have explained the growth with a vapour production rate of 2.8×106 cm−3 s−1 to sustain it. The estimated sulphuric acid concentration, calculated from global irradiance and sulphur dioxide measurements, accounted for only a fraction of the vapour concentration needed to explain the observed growth rates. This indicates that also other condensable vapours participate in the growth process. During the events, the condensation sink was calculated to be 12× 10−3 s−1 on average.
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Stelmakh, Liudmila, und Tatiana Gorbunova. „Effect of phytoplankton adaptation on the distribution of its biomass and chlorophyll a concentration in the surface layer of the Black Sea“. Oceanological and Hydrobiological Studies 48, Nr. 4 (18.12.2019): 404–14. http://dx.doi.org/10.2478/ohs-2019-0035.
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Abstract Using the field data collected in the Black Sea in September 2005–May 2013, the authors studied the spatial variability of the ratio of organic carbon to chlorophyll a (C:Chl a) in the sea surface layer (0–1 m). The C:Chl a ratio is an important parameter that reflects the phytoplankton adaptation to abiotic factors. Its maximum variations occurred in September–October 2005 and October 2010 when the highest spatial variability of average light intensity and nitrogen concentration was observed in the upper mixed layer. As a result, the maps of phytoplankton biomass differed from chlorophyll maps. In August 2011, no effect of light or nitrogen on the spatial variability of the C:Chl a ratio was found. Changes in the contribution of dinoflagellates to the total phytoplankton biomass affected the C:Chl a ratio variability, which was two times lower compared to September–October 2005 and October 2010. Also, the spatial distribution of phytoplankton biomass differed from the distribution of chlorophyll a concentration only in some areas of the sea. In May 2013, environmental factors slightly varied across the study area and the spatial variability of the C:Chl a ratio was insignificant. Therefore, the map of phytoplankton biomass indicated similarities with the chlorophyll map.
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Pollock, Karen E. „The Identification of Vowel Errors Using Traditional Articulation or Phonological Process Test Stimuli“. Language, Speech, and Hearing Services in Schools 22, Nr. 2 (April 1991): 39–50. http://dx.doi.org/10.1044/0161-1461.2202.39.
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The stimulus items from five commonly used assessment tools were examined to determine the number of occurrences of each English vowel and diphthong in a variety of contexts. Results indicated that the overall number of occurrences varied greatly from vowel to vowel and from test to test. In addition, the distribution of vowels across contexts was not balanced in any of the tests examined. The suitability of such stimuli for analyzing vowel errors is discussed in light of these results. Suggestions are provided for supplementing tests with additional stimulus words in order to obtain an adequate sample for vowel analysis. The suggested procedures are illustrated with data from one phonologically disordered client exhibiting vowel errors.
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Silvera, Katia, John B. Skillman und J. W. Dalling. „Seed germination, seedling growth and habitat partitioning in two morphotypes of the tropical pioneer tree Trema micrantha in a seasonal forest in Panama“. Journal of Tropical Ecology 19, Nr. 1 (Januar 2003): 27–34. http://dx.doi.org/10.1017/s0266467403003043.
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We examined the distribution, germination, growth and photosynthetic characteristics of two co-existing morphotypes of the pioneer tree Trema micrantha at the Barro Colorado Nature Monument (BCNM), Panama. Morphotypes differed significantly in distribution and in seed characteristics. A ‘large’-seeded morphotype (endocarp mass=3.83 mg) was associated with treefall gaps in the forest interior, whereas a ‘small’-seeded morphotype (endocarp mass=1.38 mg) was found predominantly on landslides on the margins of Lake Gatun. Seeds of the small-seeded morphotype germinated faster than seeds of the large-seeded morphotype, with seedlings of the small-seeded morphotype showing both a higher Unit Leaf Rate (ULR) and a lower Specific Leaf Area (SLA). Differences in photosynthetic rates reflected differences in SLA; the small-seeded morphotype had a higher rate on a leaf area basis, while the large-seeded morphotype had a higher rate on a leaf mass basis. Although allocation patterns between morphotypes varied in a way consistent with known interspecific differences between ‘sun’ and ‘shade’ plants, relative growth rates (RGR) of the morphotypes were similar across different light conditions suggesting that factors other than light, such as water uptake efficiency, soil nutrient requirements, and perhaps seed dispersal characters may explain the habitat partitioning of morphotypes.
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Thangjam, Uttam, und U. K. Sahoo. „Effect of Seed Mass on Germination and Seedling Vigour of Parkia Timoriana (DC.) Merr.“ Current Agriculture Research Journal 4, Nr. 2 (15.12.2016): 171–78. http://dx.doi.org/10.12944/carj.4.2.06.
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Seeds of Parkia tiamoriana show both intra specific and inter specific variation in seed weight. A research was carried out to study the effect of seed mass on germination and early growth parameters of the species. Mature seeds were collected from Sakawrtuchung provenance of Mizoram (India). They were then bulked and grouped into 3 categories as light (lwt), intermediate (mwt) and heavy (hwt), using a predetermines weight method. The grouped seeds are then sown using 1mm sieved garden soil as a medium in poly bags. After germination and from the two leave stage we start counting the seedling length, collar diameter, dry weight, etc., at every 15 days interval and up to 90th day, by using destructive method. Study on the germination and seedling growth parameters conclude that except in mean germination time (MGT) and germination index (GI), all the other parameters are positively correlated with increasing weight. Relative growth rate (RGR) and average growth rate (AGR) that use seedling dry weight also showed a positive relation with seed weight. Apart from this, the distribution pattern of seed weights as calculated from the frequency distribution of 255 seeds did not show lognormal distribution (K-S test: P<0.05, d = 0.163, n = 255). Seed weight (n=255) varied from 0.39g to 0.81g (mean: 0.61g ± 0.01g). Among the weight class, mid weight (0.5 to 0.69g) seeds made up 56.47% of the total population followed by heavy weight (23.14%) and then by light weight (20.39%).
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Shimokawa, CAK, B. Sullivan, ML Turbino, CJ Soares und RB Price. „Influence of Emission Spectrum and Irradiance on Light Curing of Resin-Based Composites“. Operative Dentistry 42, Nr. 5 (01.09.2017): 537–47. http://dx.doi.org/10.2341/16-349-l.
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SUMMARY Purpose: This study examined the influence of different emission spectra (single-peak and broad-spectrum) light-curing units (LCUs) delivering the same radiant exposures at irradiance values of 1200 or 3600 mW/cm2 on the polymerization and light transmission of four resin-based composites (RBCs). Methods and Materials: Two prototype LCUs that used the same light tip, but were either a single-peak blue or a broad-spectrum LED, were used to deliver the same radiant exposures to the top surfaces of the RBCs using either standard (1200 mW/cm2) or high irradiance (3600 mW/cm2) settings. The emission spectrum and radiant power from the LCUs were measured with a laboratory-grade integrating sphere coupled to a spectrometer, and the light beam was assessed with a beam profiler camera. Four RBCs (Filtek Supreme Ultra A2, Tetric EvoCeram A2, Tetric EvoCeram T, and TPH Spectra High Viscosity A2) were photoactivated using four different light conditions: single-peak blue/standard irradiance, single-peak blue/high irradiance, broad-spectrum/standard irradiance, and broad-spectrum/high irradiance. The degree of conversion (N=5) and microhardness at the top and bottom of 2.3-mm-diameter by 2.5-mm-thick specimens (N=5) were analyzed with analysis of variance and Tukey tests. The real-time light transmission through the RBCs was also measured. Results: For all light conditions, the 2.3-mm-diameter specimens received a homogeneous irradiance and spectral distribution. Although similar radiant exposures were delivered to the top surfaces of the RBCs, the amount of light energy emitted from the bottom surfaces was different among the four RBCs, and was also greater for the single-peak lights. Very little violet light (wavelengths below 420 nm) reached the bottom of the 2.5-mm-thick specimens. The degree of conversion and microhardness results varied according to the RBC (p<0.05). The RBCs that included alternative photoinitiators had greater microhardness values at the top when cured with broad-spectrum lights, while at the bottom, where little violet light was observed, the results were equal or higher when they were photoactivated with single-peak blue lights. With the exception of the microhardness at the top of TPH, equivalent or higher microhardness and degree-of-conversion values were achieved at the bottom surface when the standard (1200 mW/cm2) irradiance levels were used compared to when high irradiance levels were used. Conclusions: Considering the different behaviors of the tested RBCs, the emission spectrum and irradiance level influenced the polymerization of some RBCs. The RBCs that included alternative photoinitiators produced greater values at the top when cured with broad-spectrum lights, while at the bottom, results were equal or higher for the RBCs photoactivated with single-peak blue lights.
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Pike, Daniel G., und Harold E. Welch. „Spatial and Temporal Distribution of Sub-Ice Macrofauna in the Barrow Strait Area, Northwest Territories“. Canadian Journal of Fisheries and Aquatic Sciences 47, Nr. 1 (01.01.1990): 81–91. http://dx.doi.org/10.1139/f90-008.
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The distribution of sub-ice macrofauna was investigated in the Barrow Strait area near Resolute, N.W.T. from April–June, 1985, 1986, and 1987, and in January 1986. Invertebrates were sampled using remotely deployed net and video camera systems. Ten species of amphipods and two species of mysids were found, but over 90% of the biomass was made up of only four species of amphipods: Weyprechtia pinguis, Onisimus litoralis, Gammarus setosus, and Onisimus spp. juveniles. Species composition varied annually, with W. pinguis dominating in spring 1985, O. litoralis in 1986, and G. setosus in 1987. There were also areal differences in species composition over distances of 50–200 km. Underlying water depth was the major environmental correlate of both total biomass and species composition; total biomass decreased with increasing underlying water depth, being near zero over >100 m depth. We hypothesize that spring sub-ice distribution is a reflection of summertime benthic distribution. Total biomass decreased with increasing snow depth early in the spring, probably because the attenuation of incident light by snow reduces the concentration of sub-ice algae. Total biomass was lower within 1 km of the ice edge than in areas further from the ice edge.