170,233 research outputs found
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Mitomycin C in highly myopic eyes - Author reply
No full textOphthalmology. 2005 Feb;112(2):208-18; discussion 219.
Mitomycin C modulation of corneal wound healing after photorefractive keratectomy in highly myopic eyes.
Gambato C, Ghirlando A, Moretto E, Busato F, Midena E.
SourceRefractive Surgery Service and Antimetabolite Therapy Research Unit, Department of Ophthalmology, University of Padova, Padova, Italy.
Abstract
PURPOSE: To evaluate the role of topical mitomycin C in corneal wound healing (CWH) after photorefractive keratectomy (PRK) in highly myopic eyes.
DESIGN: Prospective, double-masked, randomized clinical trial.
PARTICIPANTS: Seventy-two eyes of 36 patients affected by high (>7 diopters) myopia.
METHODS: In each patient, one eye was randomly assigned to PRK with intraoperative topical 0.02% mitomycin C application, and the fellow eye was treated with a placebo. Postoperatively, mitomycin C-treated eyes received artificial tears (3 times daily, tapered in 3 months), whereas the fellow eye was treated with fluorometholone sodium 2% and artificial tears (3 times daily, tapered in 3 months).
MAIN OUTCOME MEASURES: Uncorrected visual acuity (UCVA) and best-corrected visual acuity (BCVA), contrast sensitivity, manifest refraction, and biomicroscopy. Contrast sensitivity was determined using the Pelli-Robson chart. Corneal confocal microscopy documented CWH.
RESULTS: Mean follow-up was 18 months (range, 12-36). No side effects or toxic effects were documented. At 12-month follow-up examination, UCVAs (logarithm of the minimum angle of resolution) were 0.4+/-0.48 and 0.5+/-0.53 (P = .03) in mitomycin C-treated eyes and corticosteroid-treated eyes, respectively. At 1 year, corneal haze developed in 20% of corticosteroid-treated eyes, versus 0% of mitomycin C-treated eyes. At 12, 24, and 36 months, corneal confocal microscopy showed activated keratocytes and extracellular matrix significantly more evident in untreated eyes (Ps = 0.004, 0.024, and 0.046, respectively).
CONCLUSION: Topical intraoperative application of 0.02% mitomycin C can reduce haze formation in highly myopic eyes undergoing PRK.
Comment in
Ophthalmology. 2006 Feb;113(2):357; author reply 357-8
Dispelling the Myths Behind First-author Citation Counts
No full textWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
Combining peak- and chromatogram-based retention time alignment algorithms for multiple chromatography-mass spectrometry datasets
No full textHoffmann N, Keck M, Neuweger H, et al. Combining peak- and chromatogram-based retention time alignment algorithms for multiple chromatography-mass spectrometry datasets. BMC Bioinformatics. 2012;13(1): 21.Background
Modern analytical methods in biology and chemistry use separation techniques coupled to sensitive detectors, such as gas chromatography-mass spectrometry (GC-MS) and liquid chromatography-mass spectrometry (LC-MS). These hyphenated methods provide high-dimensional data. Comparing such data manually to find corresponding signals is a laborious task, as each experiment usually consists of thousands of individual scans, each containing hundreds or even thousands of distinct signals. In order to allow for successful identification of metabolites or proteins within such data, especially in the context of metabolomics and proteomics, an accurate alignment and matching of corresponding features between two or more experiments is required. Such a matching algorithm should capture fluctuations in the chromatographic system which lead to non-linear distortions on the time axis, as well as systematic changes in recorded intensities. Many different algorithms for the retention time alignment of GC-MS and LC-MS data have been proposed and published, but all of them focus either on aligning previously extracted peak features or on aligning and comparing the complete raw data containing all available features.
Results
In this paper we introduce two algorithms for retention time alignment of multiple GC-MS datasets: multiple alignment by bidirectional best hits peak assignment and cluster extension (BIPACE) and center-star multiple alignment by pairwise partitioned dynamic time warping (CEMAPP-DTW). We show how the similarity-based peak group matching method BIPACE may be used for multiple alignment calculation individually and how it can be used as a preprocessing step for the pairwise alignments performed by CEMAPP-DTW. We evaluate the algorithms individually and in combination on a previously published small GC-MS dataset studying the Leishmania parasite and on a larger GC-MS dataset studying grains of wheat (Triticum aestivum).
Conclusions
We have shown that BIPACE achieves very high precision and recall and a very low number of false positive peak assignments on both evaluation datasets. CEMAPP-DTW finds a high number of true positives when executed on its own, but achieves even better results when BIPACE is used to constrain its search space. The source code of both algorithms is included in the OpenSource software framework Maltcms, which is available from http://maltcms.sf.net webcite. The evaluation scripts of the present study are available from the same source
A Multi-Language Comparison of Influences on Author Verification using Character N-Grams
No full textWe create a new multi-language corpus for author verification based on Wikipedia talkpages, and evaluate the influence that differences in topic and time have on character n-gram author profiles. Topic alignment between two texts is found to increase author verification precision, and an authors writing style is found to change over time, but not more significantly after 3 years than after 1 year.Information ArchitectureWISElectrical Engineering, Mathematics and Computer Scienc
A 0.12mm<sup>2</sup> Wien-Bridge Temperature Sensor with 0.1°C (3σ) Inaccuracy from -40°C to 180°C
No full text Resistor-based temperature sensors can achieve much higher resolution and energy efficiency than conventional BJT-based sensors [1], but they typically occupy more area (> 0.25 mm 2 ) and have lower operating temperatures (le 125 {circ} {C}) [2]-[4]. This work describes a 0.12mm 2 resistor-based sensor that uses a Wien-bridge (WB) filter to achieve 0.1 {circ} {C} (3 sigma) inaccuracy from - 40 {circ} {C} to 180 {circ} {C}. Compared to a state-of-the-art WB sensor [4], it occupies 6 × less area and achieves comparable relative accuracy over a 76% wider operating range. Session 10.3 Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Electronic InstrumentationMicroelectronic
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Proceedings of the Fourth International Conference on Guayule Research and Development Conference: Tucson, Arizona, October 16-19, 1985
No full textThe Guayule Rubber Society, The University of Arizona College of Agriculture, United States Department of Agriculture.INVITED REVIEW PAPERS: The Performance of Guayule in Australia / P. L. Milthorpe – The Guayule Program in Argentina / R. Ayerza and D. Bengtson – GUAYULE ACTIVITIES IN THE UNITED STATES, IRAQ AND NEW ZEALAND: New Attempts to Introduce Guayule Into Iraq / S. H. AI-Abbasi, N. A. Muradian, N. A. Jajawi, and A. A. Hassan – Guayule-the New Zealand Experience / J.O. Taylor – Gila Guayule Natural Rubber Industry in 1992: Status, Potential, Financial Requirements / W. Miller, J. Reidl, W. Cole, and S. Prather – TISSUE CULTURE: Establishment of Guayule Tissue in vitro for Somatic Cell Hybridization / J. Ruffin, U. Banerjee, and R. Navasero – Cloning Guayule Plant Selections Via Tissue Culture / D.N. Radin, R.A. Norton, and E. Rodriguez – Control of Morphogenesis in Guayule Tissue Culture / J. E. Peters, C. Salvucci, and J. Levasseur – Rubber Synthesis in Crown Gall and Normal Tissue Cultures of Guayule / R.A. Norton, D. N. Radin, and E. Rodriguez – SEEDS AND SEEDING: Guayule Seed Harvesting Equipment / B. Lorenzen and W. Coates – Improved Quality of Chemically Treated Guayule (Parthenium argentatum Gray) Seeds / G. R. Chandra and D. A. Bucks – Direct Seeding of Guayule Under Dryland Conditions / C. L. Gonzalez and R. J. Rektorik – Direct Seeding of Guayule in West Texas / M. A. Foster, T. D. Carrillo, and J. Moore – Direct Seeding for Economical Guayule Field Establishment / D. A. Bucks, R. L. Roth, D. E. Powers, and G. R. Chandra – SALINITY: Salinity in Relation to Direct Seeding of Guayule / S. Miyamoto – The Effects of Certain Sodium and Calcium Salts on the Germination of a Guayule Cultivar / S. K. Ballal and T. J. Daugherty – Salt Tolerance of Guayule / E. V. Maas, T. J. Donovan, L. E. Francois, and G. E. Hamerstrand – Water Quantity and Quality Requirements of Guayule: Tentative Assessment / S. Miyamoto and D. A. Bucks – BIOREGULATORS: The Cultivar Effect on the Bioinduction of Guayule Rubber / E. Hayman, S. Gold and H. Yokoyama – The Regulation of Isoprenoid Synthesis in Guayule Seed by the Bioregulator 2-(4-Methylphenoxy) Triethylamine (MPTA) / C. R. Benedict, C. L. Rosenfield, M. A. Foster, and H. Yokoyama – Effect of Phytohormones on Germination and Growth of Guayule Parthenium argentatum Gray / E. Flores, J. Meza and M. A. Martinez – GENETICS: Evaluation of Diploid and Tetraploid Guayule for Rubber and Other Characters / S. Kuruvadi – Meiotic Analysis and Fertility of F₁ Hybrids Between Guayule, Parthenium argentatum, and Arborescent Parthenium tomentosum var. stramonium / A. Hashemi, J. G. Waines, and W. W. Wright – Variation in Morphology, Chromosome Number, and Chemistry in Mariola (Parthenium incanum) / J. West, A. Hashemi, J. G. Waines, and W. W. Wright – Selection and Hybridization for Improved Rubber Yield in Guayule / H. H. Naqvi, T. Burch, and J. G. Waines – Rubber Yield Evaluation of New Guayule Selections / A. Estilai and J.G. Waines – Rubber Analysis of Guayule at the TAES-Firestone Research Site / M. A. Foster, T. S. Ward, and J. Moore – Development of Interspecific Hybrids in Parthenium / H. H. Naqvi, J. Davey, and J. G. Waines – A New Industry and a Contribution to Our National Security If? / H. M. Tysdal – SHRUB HARVEST BY CLIPPING: Clipping as an Agronomic Practice in Guayule / D. T. Ray, D. J. Garrot Jr., D. D. Fangmeier, and W. Coates – Effects of Season of Pollarding and Cutting Height on Growth and Survival of Guayule / M. A. Foster, T. S. Ward, T. D. Carrillo, and J. Moore – Development of a Clipper for Guayule Shrub Harvesting / W. Coates – AGRONOMIC PRACTICES: The Effect of Flowering Upon Rubber Production in Guayule / K. L. Willard and D. T. Ray – Guayule Rubber Production When Interseeded with Buffelgrass (Cenchrus ciliaris) Under Dryland Conditions in South Texas / C. L. Gonzalez – The Effect of Honey Bee Pollination on the Seed Quantity and Quality of Cultivated Guayule Parthenium argentatum Gray / A. N. Mahmood, D. T. Ray, and G. D. Waller – Comparative Phosphorus Requirements of GuayuIe Cultivars / J. R. Thomas – Guayule Seed/Rubber Production Cash Flow Analysis Using Commercial Computer Software / N. G. Wright – RUBBER QUALITY: Purification of Rubber Particles from Guayule (Parthenium argentatum Gray) Tissue / R. A. Backhaus and G. R. Chandra – Effects of Storage on the Molecular Weight of Rubber Contained in Guayule / L. T. Black, C. L. Swanson, and G. E. Hamerstrand – Influence of Rubber Gels in Guayule on Field Pre-processing, Final Physical Properties and Rubber Analysis / R. Seeger and D. McIntyre – Reversion Studies of Guayule Rubber / J. M. Sloan, M. J. Magliochetti, and H. D. C. Hart – INVITED REVIEW PAPERS: An Update on the South African Guayule Programme / J.C. Paterson-Jones – Guayule as an Industrial Crop in Semiarid Zones / D. Forgacs, J. Schechter, J. Wisniak, and M. Forti – PLANT CHARACTERISTICS: Leaf Growth as an Indicator of Phase in Guayule / E. E. Bradley and P. L. Healey – Potential Rubber Carrying Capacity (PRCC) in Guayule, A Structural Study / P. L. Healey, I. J. Mehta, and A. V. Charlesworth – Seasonal Effects on Guayule Resin Composition / W. W. Schloman Jr., D. J. Garrot Jr., D. T. Ray, and D. J. Bennett – Gel Permeation Chromatographic Analysis of Isoprene Polymers of the Genus Parthenium / J. West, G. Flores, M. Martinez, and E. Rodriguez – Guayule Collections from Wild Stands with High Rubber yield / A. Lopez-Benitez and S. Kuruvadi – Exploration, Collection, and Evaluation of Native Germplasm of Guayule / S. Kuruvadi – PESTS AND PATHOGENS: Weed Control in Established Guayule Stands / M. A. Foster, T. D. Carrillo, and J. Moore – The Effect of Glomus intraradices on the Growth and Nutrition of Guayule in a Saline Soil / C. M. Pfeiffer and H. E. Bloss – Greenhouse Evaluation of Tolerance of Triploid and Tetraploid Guayule Lines to Verticillium dahlia / T. V. Orum and S. M. Alcorn – Some Phytophagous Arthropods Associated with the Wild Population of Parthenium integrifolium L. and Cultivated Guayule, Parthenium argentatum Gray / R. C. Navasero, J. Ruffin, and U. C. Banerjee – Root Rot of Guayule / D. P. S. Verma – Susceptibility of Guayule Transplants to Plant-Parasitic Nematode Injury / S. H. Thomas and C. J. Goddard – Latex Content and Biomass Increase in Mycorrhizal Guayule Under Field Conditions / H. E. Bloss and C. M. Pfeiffer – The Evaluation of Guayule Resin as a Pesticide / J. D. Bultman, R. H. Beal, W. W. Schloman, and C. A. Bailey – RUBBER EXTRACTION AND UTILIZATION: Development of a Process for Solvent Extraction of Natural Rubber from Guayule / J. P. Wagner, C. R. Engler, D. G. Parma, and E. W. Lusas – The Extraction of Isopentenyl Isomerase from Guayule Plants / S. H. Pan, C. R. Benedict, and C. L. Rosenfield – Techniques for the Determination of the Rubber Content of Guayule Plants / C. L. Rosenfield, M. Foster, R. D. Stipanovic, H. Yokoyama, and C. R. Benedict – A Rapid Soxhlet Technique for the Quantitative Determination of Resin and Rubber in the Guayule Shrub / D. J. Bennett, R. W. Biro, and A. S. Hilton – Conversion of Guayule Residues to Diesel Fuel / J. L. Kuester and T. Wang – INVITED REVIEW PAPERS: Review of Research and Development of Guayule in Mexico / A. Lopez-Benitez and S. Kuruvadi – Guayule Research in India - An Overview / G. S. Srivastava, et al. – WATER RELATIONS: Water Stress and Seasonal Effects on the Photosynthetic and Hydrocarbon Emission Rates in Guayule / F. S. Nakayama, S. G. Allen, and S.T. Mitchell – Water and Stress Effects on Growth and Rubber Accumulation in Guayule as Determined by the Crop Water Stress Index / D. J. Garrot Jr., D. T. Ray, and D. D. Fangmeier – Water Management and Production Relations of Mature Guayule / D. A. Bucks and F. S. Nakayama – Water Stress and Seasonal Effects on Rubber Quality in Irrigated Guayule / D. J. Garrot Jr., W. W. Schloman Jr., and D. T. Ray – Sprinkler Irrigation for Establishing Directly Seeded Guayule / R. H. Zittlosen and D. D. Fangmeier.Page iv in original is an unnumbered blank page
Pfade des C- und N-Umsatzes im Boden unter erhöhter CO2-Konzentration
No full textIn the present thesis the C and N transformations in soil as influenced by indirect effect of elevated atmospheric CO2, soil physical structure and land use change were studied in four laboratory experiments using stable-C and N isotopes, as well as soil microbiological techniques. To test the interrelations between chemical and biological characteristics of soil organic matter (SOM) as affected by land use change and elevated atmospheric CO2 an approach for SOM partitioning based on its thermal stability was chosen. In the first experiment C isotopic composition of soils subjected to C3-C4 vegetation change (grassland to Miscanthus x gigantheus, respectively) was used for the estimation of C turnover in SOM pools. In the 2nd (Free Air CO2 Enrichment ? FACE ? Hohenheim) and 3rd (FACE Braunschweig) experiments CO2 applied for FACE was strongly depleted in 13C and thus provided an opportunity to study C turnover in SOM based on its δ13C value. Simultaneous use of 15N labeled fertilizers allowed N turnover to be studied (in the 2nd experiment). We hypothesized that the biological availability of SOM pools expressed as the mean residence time (MRT) of C or N is inversely proportional to their thermal stability. Soil samples were analysed by thermogravimetry coupled with differential scanning calorimetry (TG-DSC). According to differential weight losses between 20 and 1000 °C (dTG) and energy release or consumption (DSC), SOM pools (4 to 5 depending on experiment) with increasing thermal stability were distinguished. Soil samples were heated up to the respective temperature and the remaining soil was analyzed for δ13C and δ15N by IRMS. For all three experiments the separation of SOM based on its thermal stability was not sufficient to reveal pools with contrasting turnover rates of C and N. A possible explanation for the inability of thermal oxidation for isolating SOM pools of contrasting turnover times is that the fractionation of SOM pools according to their thermal stability is close to chemical separation. In turn, it was found that chemical separations of SOM failed to isolate the SOM pools of different turnover time because different biochemical plant components (cellulose, lignin) are decomposed in a wide temperature range. Individual components of plant residues may be directly incorporated into, or even mixed with the thermal stable SOM pools and will so mask low turnover rates of these pools.
To evaluate the interactions between availability of SOM for decomposition by soil microbial biomass (biological characteristic) under elevated atmospheric CO2 and protection of SOM due to the occlusion within aggregates of different sizes (physical property, responsible for SOM sequestration) we measured the activity of microbial biomass (indicated by enzyme activities) and growth strategies of soil microorganisms (fast- vs. slow growing organisms) in isolated macro- and microaggregates.
The contribution of fast (r-strategists) and slowly growing microorganisms (K-strategists) in microbial communities was estimated by the kinetics of the CO2 emission from bulk soil and aggregates amended with glucose and nutrients (Substrate Induced Growth Respiration method). Although Corg and total Cmic were unaffected by elevated CO2, maximal specific growth rates were significantly higher under elevated than ambient CO2 for bulk soil, small macroaggregates, and microaggregates. Thus, we conclude that elevated atmospheric CO2 stimulated the r-selected microorganisms. Such an increase in r-selected microorganisms could increase C turnover in terrestrial ecosystems in a future elevated atmospheric CO2 environment.
The activities of β-glucosidase, phosphatase and sulphatase were unaffected in bulk soil and in aggregate-size classes by elevated CO2, however, significant changes were observed in potential enzyme production after substrate amendment. After adding glucose, enzyme activities under elevated CO2 were 1.2-1.9-fold higher than under ambient CO2. This indicates an increased activity of microorganisms, which leads to accelerated C turnover in soil under elevated CO2. Significantly higher chitinase activity in bulk soil and in large macroaggregates under elevated CO2 revealed an increased contribution of fungi to turnover processes. At the same time, less chitinase activity in microaggregates underlined microaggregate stability and the difficulties for fungi hyphae penetrating them. We conclude that quantitative and qualitative changes of C input by plants into the soil at elevated CO2 affect microbial community functioning, but not its total content. Future studies should therefore focus more on the changes of functions and activities, but less on the pools.
In conclusion, elevated CO2 concentrations in the atmosphere along with soil physical structure have a pronounced effect on qualitative but not quantitative changes in C and N transformations in soil under agricultural ecosystem. The physical parameters of soil such as aggregation correlate more with biological availability of SOM than the chemical properties of soil organic materials. The increase of soil microbial activity under elevated CO2 detected especially in soil microaggregates, which are supposed to be responsible for SOM preservation, prejudice sequestration of C in agroecosystems affected by elevated atmospheric CO2.In der vorliegenden Dissertation wurde anhand von vier Laborversuchsreihen untersucht, wie C- und N-Transformationen in Böden indirekt durch erhöhte atmosphärische CO2-Konzentrationen, durch die physikalische Bodenstruktur und durch Änderungen der Bodennutzung beeinflusst werden. Dabei kamen die Analyse stabiler C- und N-Isotopen sowie bodenmikrobiologische Techniken zum Einsatz. Um die Relationen chemischer und biologischer Charakteristika von SOM (soil organic matter) unter dem Einfluss von Bodennutzungsänderungen und erhöhten atmosphärischen CO2-Konzentrationen zu erfassen, wurde eine SOM-Fraktionierung anhand ihrer thermischen Stabilität durchgeführt. In der ersten Versuchsreihe wurde der C-Umsatz in SOM-Pools anhand der Zusammensetzung der stabilen C-Isotope in Böden nach einem Wechsel des Bestandes von C3-Arten zu C4-Arten (temperates Grünland zu Miscanthus x gigantheus) analysiert. In der zweiten (FACE ? Free Air CO2 Enrichment ? Hohenheim) und dritten (FACE Braunschweig) Versuchsreihe wurde CO2 zur Konzentrationserhöhung benutzt, das deutlich in der 13C-Signatur abgereichert war und daher als Tracer für den C-Umsatz in den SOM pools genutzt werden konnte. Gleichzeitig wurde (im FACE Hohenheim) der Stickstoffdünger mit 15N markiert und ermöglichte es, den N-Umsatz zu verfolgen. Als Arbeitshypothese sollte getestet werden, ob die biologische Verfügbarkeit von SOM Pools (ausgedrückt als mittlere Verweildauer, mean residence time MRT für C und N) umgekehrt proportional zu ihrer thermischen Stabilität ist. Die Bodenproben wurden mittels Thermogravimetrie, gekoppelt mit differenzieller Scanning Kalorimetrie (TG-DSC), analysiert. Anhand der differenziellen Gewichtsverluste im Temperaturbereich zwischen 20 und 1000 °C und der Energieabgabe bzw. ?Aufnahme wurden je nach Versuchsreihe 4 bzw. 5 SOM Pools mit steigender thermischer Stabilität unterschieden. Die Bodenproben wurden bis zur jeweiligen Temperatur aufgeheizt und der verbleibende Rest jeweils auf 13C- und 15N-Gehalte mittels IRMS untersucht. Die Fraktionierung von SOM anhand ihrer thermischen Stabilität war somit in allen drei Versuchsreihen nicht ausreichend, um Pools mit unterschiedlichen Umsatzraten von C und N zu differenzieren. Eine mögliche Erklärung dafür kann sein, dass die thermische Stabilität von SOM-Pools eng mit ihrer chemischen Struktur verbunden ist. Entsprechend liegen Befunde vor, dass es anhand einer chemischen Fraktionierung von SOM-Pools nicht möglich war, Pools mit unterschiedlichen Turnover-Raten zu separieren, da die verschiedenen Pflanzenbestandteile (Zellulose, Lignin) in einem weiten Temperaturbereich zersetzt werden. Einzelne Inhaltsstoffe der Pflanzenrückstände können direkt in die thermisch stabilen SOM-Pools inkorporiert oder sogar mit ihnen vermischt werden, so dass potenziell geringere Turnover-Raten maskiert werden.
Um die Interaktionen zwischen der Verfügbarkeit von SOM für mikrobielle Zersetzung (biologische Eigenschaften) und dem Schutz von SOM aufgrund des Einschlusses innerhalb von Bodenaggregaten unterschiedlicher Größe (physikalische Eigenschaften, verantwortlich für die SOM-Sequestrierung) unter erhöhtem atmosphärischem CO2 zu untersuchen, wurden die Aktivität der mikrobiellen Biomasse anhand von Enzymaktivitäten und die Wachstumsstrategien der Bodenmikroorganismen (schnellwüchsige vs. langsamwüchsige Organismen in isolierten Makro- und Mikroaggregaten gemessen.
Der Anteil schnellwüchsiger (r-Strategen) und langsamwüchsiger (K-Strategen) Mikroorganismen an der mikrobiellen Gemeinschaft wurde anhand der Kinetik der CO2-Emission aus dem Gesamtboden und den Bodenaggregaten nach Glukose- und Nährstoff-Applikation bestimmt (Substratinduzierte Wachstumsrespirationsmethode, SIGR). Obwohl Corg und Cmic unter erhöhtem CO2 unbeeinflusst blieben, waren die maximale spezifische Wachstumsrate durch den CO2-Anstieg im Gesamtboden, in den kleinen Makroaggregaten und in den Mikroaggregaten signifikant erhöht. Dies deutet auf eine erhöhte Aktivität von Mikroorganismen mit r-Strategie unter erhöhtem CO2.
Die Aktivitäten von β-Glucosidase, Phosphatase und Sulphatase waren unter erhöhtem CO2 sowohl im Gesamtboden als auch in den einzelnen Aggregatklassen unverändert. Es traten aber signifikante Veränderungen in den potenziellen Enzymaktivitäten nach Aktivierung durch Glukose- und Nährstoffaddition auf. Dies deutet auf gesteigerte Aktivität der Mikrorganismen und beschleunigten C-Umsatz in den Böden unter erhöhtem CO2. Die Chitinase-Aktivität war im Gesamtboden und in den großen Makroaggregaten unter CO2-Anstieg signifikant höher und belegt einen gestiegenen Anteil von Pilzen an den Umsetzungsprozessen. Zusammenfassend kann postuliert werden, dass quantitative und qualitative Veränderungen im C-Eintrag durch Pflanzen in den Boden unter erhöhtem CO2 auftreten, welche die Funktion, nicht aber die Gesamtmenge der mikrobiellen Gemeinschaft beeinflussen. Künftige Studien sollten daher vermehrt auf Funktionen und Aktivitäten und weniger auf die Pools fokussiert werden.
Steigende CO2-Konzentrationen in der Atmosphäre haben deutliche Auswirkungen auf qualitative, weniger aber auf quantitative Aspekte der C- und N-Umsätze in Böden von Agrarökosystemen. Physikalische Bodenparameter wie die Aggregation korrelieren stärker mit der biologischen Verfügbarkeit von SOM als die chemischen Eigenschaften des organischen Materials. Die erhöhte mikrobielle Aktivität unter erhöhtem CO2, die vor allem in den für die Konservierung von SOM wichtigen Bodenmikroaggregaten gefunden wurde, beeinträchtigt eine potenzielle C-Sequestrierung in Agrarökosystemen unter steigenden atmosphärischen Kohlendioxidkonzentrationen
A ±25A Versatile Shunt-Based Current Sensor with 10kHz Bandwidth and ±0.25% Gain Error from -40°C to 85°C Using 2-Current Calibration
No full textAccurate current sensing is critical in many industrial applications, such as battery management and motor control. Precise shunt-based current sensors have been reported with gain errors of less than 1% over the industrial temperature range (-40°C to 85°C) [1]–[4]. However, since they are intended for coulomb counting, their bandwidth is limited to a few tens of Hz, making them unsuitable for battery impedance or motor-current sensing. This paper presents a current sensor with a wide (10kHz) bandwidth and a tunable temperature compensation scheme (TCS), which allows it to be flexibly used with different types of shunts while maintaining high accuracy. A low-cost room-temperature calibration scheme is proposed to optimize gain flatness over temperature by exploiting the shunt's self-heating at large currents. Over the industrial temperature range and a ±25A current range, it achieves state-of-the-art gain error (±0.25%) with both low-cost PCB and stable metal-alloy shunts.Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Electronic InstrumentationMicroelectronic
An Article About Albertus C. Van Raalte, Author Unknown, Except for Parts Taken from an Article by Anna C. Post
No full textAn article about Albertus C. Van Raalte, author unknown, except for parts taken from an article by Anna C. Post. The author knew first generation persons in the Holland settlement and therefore, the article has some value.https://digitalcommons.hope.edu/vrp_1890s/1012/thumbnail.jp
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