bluuebunny/crossref_metadata_2025_split huggingface dataset:
Development of a trace gas stable isotope capture system in a mobile laboratory for temporal and spatial sampling of field and laboratory experiments
Authors: McNamara Niall , Benham David , Sleep Darren , Grant Helen , Stott Andrew 
Published: November 2002

AbstractWe describe the development of a novel mobile field laboratory, purposely designed for the automated capture and subsequent stable isotopic analyses of multiple gas samples. The multiple capture system is integrated into a mobile laboratory that is fully capable of measuring the concentration of carbon dioxide, methane and nitrous oxide trace gases in a flow‐through system connected to a gas chromatograph fitted with both electron capture and flame ionisation detectors. The capture of gases is achieved by routing samples through a series of 135 mL gas flasks that are sealed by micro‐solenoid valves triggered by a timing system. Trace gas light stable isotope ratio mass spectrometry can then be carried out on gas samples collected by the system (NERC 15N Stable Isotope Facility). The excitingly unique potential of the system to the ecological research field is that it will allow the collection of cyclical data for three different trace gases both in real‐time and in situ. We present data arising from the validation of this mobile system as well as a preliminary experimental assessment of this technique. This technique was used to measure δ13C in CO2 and CH4 in soil gases released from waterlogged cores and δ13C‐CH4 values were significantly depleted in wet cores compared with dry ones (p < 0.001). Copyright © 2002 John Wiley & Sons, Ltd.
Characterization of soil organic matter fractions from grassland and cultivated soils via C content and δ13C signature
Authors: Accoe Frederik , Boeckx Pascal , Van Cleemput Oswald , Hofman Georges , Hui Xu , Bin Huang , Guanxiong Chen 
Published: November 2002

AbstractVariations in 13C natural abundance and distribution of total C among five size and density fractions of soil organic matter, water soluble organic C (WSOC) and microbial biomass C (MBC) were investigated in the upper layer (0–20 cm) of a continuous grassland soil (CG, C3 vegetation), a C3‐humus soil converted to continuous maize cultivation (CM, C4 vegetation) and a C3‐humus soil converted to a rotation of maize cultivation and grassland (R). The amounts of WSOC and MBC were both significantly larger in the CG than in the CM and the R. In the three soils, WSOC was depleted while MBC was enriched in 13C as compared with whole soil C. The relative contributions to the total C content of C stored in the macro‐organic matter and in the size fraction 50–150 µm decreased with decreasing total C contents in the order CG > R > CM, while the relative contribution of C associated with the clay‐ and silt‐sized fraction <50 µm increased. This reflects a greater stability and physical protection against microbial degradation associated with soil disruption (tillage) of the clay‐ and silt‐associated organic C, in relation to the organic C in larger size fractions. The size and density fractions from the CG soil showed significant differences in 13C enrichment, indicating different degrees of microbial degradation and stability of soil organic C associated with physically different soil organic matter (SOM) fractions. δ13C analysis of the size and density fractions from CM and R soils reflected a decreasing turnover rate of soil organic C with increasing density among the macro‐organic matter fractions and with decreasing particle size. Copyright © 2002 John Wiley & Sons, Ltd.
Invertebrate accessibility and vulnerability in the analysis of brown trout (Salmo trutta L.) summer habitat suitability
Authors: de Billy V. de Crespin , Dumont B. , Lagarrigue T. , Baran P. , Statzner B. 
Published: November 2002

AbstractWater discharge regulation can affect food availability, accessibility and vulnerability and thus, the trophic habitat suitability for lotic salmonids. To analyse brown trout habitat suitability, we therefore combined the relative importance of the food availability (overall abundance of benthic and drifting invertebrates), with the potential food vulnerability (accessibility, conspicuousness and ease of handling), the latter depending on both physical habitat characteristics (flow patterns and structural complexity of habitat) and invertebrate traits (size and other biological traits). We considered the trophic patterns of trout at two spatial scales: the reach scale (unregulated reach versus regulated reach) and the macrohabitat scale (e.g. riffles and pools).Discharge regulation reduced trout abundance, biomass, and temperature‐independent growth rates. In the regulated reach, trout had a lower total prey consumption, a higher consumption of terrestrial invertebrates and a higher diet diversity than in the unregulated reach, indicating that trout were food‐limited. However, the potential availability of food supplies per individual trout was similar for the two reaches. Thus, trout prey consumption in the regulated reach should have been predominantly affected by the decrease in both the availability of large invertebrates in the drift and their vulnerability in the total food supplies.There were no macrohabitat‐specific differences in the total prey consumption and in the potential food availability within each reach. However, brown trout diets differed between the macrohabitats of each reach, in relation to differences in potential invertebrate vulnerability.Therefore, the potential vulnerability of invertebrates to predation was more relevant in the ecological evaluation of salmonid habitat suitability than the total food availability. The analysis at the macrohabitat scale provided a better understanding of the switches in brown trout diet and enabled a finer and more realistic analysis of trout feeding patterns. Copyright © 2002 John Wiley & Sons, Ltd.
Controls on the size and occurrence of pools in coarse‐grained forest rivers
Authors: Buffington John M. , Lisle Thomas E. , Woodsmith Richard D. , Hilton Sue 
Published: November 2002

AbstractControls on pool formation are examined in gravel‐ and cobble‐bed rivers in forest mountain drainage basins of northern California, southern Oregon, and southeastern Alaska. We demonstrate that the majority of pools at our study sites are formed by flow obstructions and that pool geometry and frequency largely depend on obstruction characteristics (size, type, and frequency). However, the effectiveness of obstructions to induce scour also depends on channel characteristics, such as channel gradient, width:depth ratio, relative submergence (ratio of flow depth to grain size), and the calibre and rate of bed material supply. Moreover, different reach‐scale channel types impose different characteristic physical processes and boundary conditions that further control the occurrence of pools within a catchment. Our findings indicate that effective management of pools and associated aquatic habitat requires consideration of a variety of factors, each of which may be more or less important depending on channel type and location within a catchment. Consequently, strategies for managing pools that are based solely on single‐factor, regional target values (e.g. a certain number of wood pieces or pools per stream length) are likely to be ineffective because they do not account for the variety of local and catchment controls on pool scour and, therefore, may be of limited value for proactive management of complex ecosystems. Copyright © 2002 John Wiley & Sons, Ltd.
Effects of stream diversion on riffle macroinvertebrate communities in a Maui, Hawaii, stream
Authors: McIntosh Mollie D. , Benbow M. Eric , Burky Albert J. 
Published: November 2002

AbstractThe continual demand for freshwater by industry (e.g. tourism) and agriculture, a growing population, and increasing development over the past 100 years has resulted in the construction of diversions within many streams of Hawaii. The main objective of this study was to evaluate the impact of stream diversions on riffle macroinvertebrate communities. Benthic macroinvertebrate larval populations were compared above and below a diversion in Iao Stream, Maui, Hawaii, from April to August 2000. During this summer approximately 92–97% of daily stream flow was diverted from Iao Stream. Three taxa, Procanace sp. (Diptera: Canacidae), Atyoida bisulcata (Crustacea: Decapoda), and Amphipoda (Crustacea), were only collected above the diversion. However, the most numerous taxa, Chironomidae (63–64% of the total macroinvertebrate community), Hydroptila arctia (Trichoptera: Hydroptilidae; 15%), and Cheumatopsyche pettiti (Trichoptera: Hydropsychidae; 8%), were found both above and below the diversion. The relative percentage abundance of these dominant taxa remained relatively consistent above and below the diversion over the study period. However, the mean total density of individual dominant taxa was greater above the diversion. The mean total macroinvertebrate density above the diversion was 46% greater than below the diversion (Student t‐test: df = 30, t = −3.22, p > 0.01). No correlation was found between temperature and density. A positive correlation was detected between Froude number and mean total macroinvertebrate density. Overall, the reduction in macroinvertebrate diversity and in individual and total density below the diversion suggest that trophic interactions, and thus energy flow, could be affected by reduced flow in Hawaiian streams. The information gained from this study will contribute to knowledge on Hawaiian stream ecosystems, help to create minimum instream flow standards for stream restoration, and will provide information for future freshwater management issues on the Hawaiian islands. Copyright © 2002 John Wiley & Sons, Ltd.
Application of airborne multispectral digital imagery to quantify riverine habitats at different base flows
Authors: Whited D. , Stanford J. A. , Kimball J. S. 
Published: November 2002

AbstractWe employed an integrated system of airborne remote sensing and ground surveys for regional mapping of instream habitats under variable flows over a 70 km section of the Lower Yakima River in southern Washington, USA. Airborne multispectral digital imagery was obtained in conjunction with field survey measurements and used to quantify the spatial extent, condition and temporal changes of selected river habitat characteristics under two different flows (14 and 28 m3 s−1). Under each flow, geomorphic measures were quantified (e.g. channel complexity, number and size of habitats). Water depth and velocity were also classified for instream habitats, and temperature and turbidity were recorded. Remote sensing classification accuracies for islands, exposed rocks and water surfaces were greater than 99%, while more detailed depth/flow classifications were less accurate (68% and 72%, for the high and low flows, respectively). While high turbidity (>4 Nephelometric Turbidity Units (NTU)), shadows and bidirectional reflectance factor reduced classification accuracies, the overall effect of these factors was minimal. Under the low‐flow situation, off‐channel habitats were less abundant, more isolated and had shallower depths and warmer temperatures. Our analysis suggests that airborne multispectral imagery, coupled with appropriate ground truth data, can be a viable method for regional mapping of diverse riverine habitats under variable flows. We concluded from this analysis that the higher flow situation provided substantially better habitat than currently exists in the Lower Yakima River. Copyright © 2002 John Wiley & Sons, Ltd.
Multiple perspectives for the study of teaching: Knowledge, reason, understanding, and being
Authors: Feldman Allan 
Published: November 2002

AbstractThis study analyzes the participation of secondary school teachers in a U.S. science education curriculum reform effort. All participating teachers agreed to implement the curriculum in their classrooms; however, the level at which it was implemented varied significantly among teachers. This article reviews the available perspectives used to account for the behavior of these teachers—reliance on a knowledge base, practical reasoning and reflective practice, and sociocultural views—and argues they are incomplete. A fourth perspective is developed in which teaching is viewed as a way of being and teachers as meaning makers immersed in educational situations. The remainder of the article is a cross‐case analysis of two teachers' use of the curriculum as seen from each of these perspectives on teaching. © 2002 Wiley Periodicals, Inc. J Res Sci Teach 39: 1032–1055, 2002
Investigation of preservice elementary teachers' thinking about science
Authors: Cobern William W. , Loving Cathleen C. 
Published: November 2002

AbstractIt is not uncommon to find media reports on the failures of science education, nor uncommon to hear prestigious scientists publicly lament the rise of antiscience attitudes. Given the position elementary teachers have in influencing children, antiscience sentiment among them would be a significant concern. Hence, this article reports on an investigation in which preservice elementary teachers responded to the Thinking about Science survey instrument. This newly developed instrument addresses the broadrelationship of science to nine important areas of society and culture and is intended to reveal the extent of views being consistent with or disagreeing with a commonly held worldview of science portrayed in the media and in popular science and science education literature. Results indicate that elementary teachers discriminate with respect to different aspects of culture and science but they are not antiscience. © 2002 Wiley Periodicals, Inc. J Res Sci Teach 39: 1016–1031, 2002
Development and evaluation of the conceptual inventory of natural selection
Authors: Anderson Dianne L. , Fisher Kathleen M. , Norman Gregory J. 
Published: November 2002

AbstractNatural selection as a mechanism of evolution is a central concept in biology; yet, most nonbiology‐majors do not thoroughly understand the theory even after instruction. Many alternative conceptions on this topic have been identified, indicating that the job of the instructor is a difficult one. This article presents a new diagnostic test to assess students' understanding of natural selection. The test items are based on actual scientific studies of natural selection, whereas previous tests have employed hypothetical situations that were often misleading or oversimplified. The Conceptual Inventory of Natural Selection (CINS) is a 20‐item multiple choice test that employs common alternative conceptions as distractors. An original 12‐item version of the test was field‐tested with 170 nonmajors in 6 classes and 43 biology majors in 1 class at 3 community colleges. The test scores of one subset of nonmajors (n = 7) were compared with the students' performances in semistructured interviews. There was a positive correlation between the test scores and the interview scores. The current 20‐item version of the CINS was field‐tested with 206 students in a nonmajors' general biology course. The face validity, internal validity, reliability, and readability of the CINS are discussed. Results indicate that the CINS will be a valuable tool for instructors. © 2002 Wiley Periodicals, Inc. J Res Sci Teach 39: 952–978, 2002
Effect of the challenger experience on elementary children's attitudes to science
Authors: Jarvis Tina , Pell Anthony 
Published: November 2002

AbstractThis research explored how the Challenger experience influenced over 655 elementary boys' and girls' general attitudes to science and space during the 5 months after their visit by examining their responses to four different attitude scales. These were administered to the 10‐ to 11‐year‐olds immediately before and after the Challenger experience as well as 2 and 5 months later. Knowledge tests were also administered before and after the visit. A sample of children completed an existing measure of anxiety. Although there were mainly positive outcomes immediately after the Challenger experience, there were some negative effects. There were also noticeable differences between boys and girls. Some 24% of pupils were inspired to become scientists. There was also less fear of space travel with a greater appreciation of the use of science to protect the planet after the visit. Most girls improved and maintained their attitudes toward science in society. A sizeable number of pupils were relatively unaffected by the experience and there was a significant negative effect on a small group of anxious girls. There are indications that previsit preparation and careful choice of roles during the simulation are important. © 2002 Wiley Periodicals, Inc. J Res Sci Teach 39: 979–1000, 2002
Differential effects on the achievement of males and females of teaching the particulate nature of chemistry
Authors: Bunce Diane M. , Gabel Dorothy 
Published: November 2002

AbstractChemistry concepts in three 2‐week modules were presented to a treatment and control group of high school students from 10 different high schools. The treatment group was taught using three representations of matter (macroscopic, particulate, and symbolic), whereas only two representations (macroscopic and symbolic) were used with the control group. The treatment group scored significantly higher across the combined score of all three modules. When the data were analyzed for gender–group interactions, females who were taught the particulate representation scored as well as males whereas those who were not taught the particulate representation scored significantly lower than males. Teaching males the particulate representation did not significantly affect males' achievement. © 2002 Wiley Periodicals, Inc. J Res Sci Teach 39: 911–927, 2002
Situational knowledge in physics: The case of electrodynamics
Authors: Savelsbergh Elwin R. , de Jong Ton , Ferguson‐Hessler Monica G.M. 
Published: November 2002

AbstractMajor difficulties for a novice physics problem solver are how to interpret new problems and how to combine information given in the problem with information already known. A domain expert, by contrast, has the knowledge to take full advantage of problem features at a glance. It takes a long period of practice to acquire such situational knowledge, and it would be desirable for this to be taught more effectively. As a first step, this requires information on how situational knowledge differs across individuals of different competence levels. Related research on mental models and problem representations does not give a direct view on the knowledge subjects have of situations before being confronted with the problem. To assess situational knowledge more directly, we asked participants to respond to physics formulas (from the field of electrodynamics) by describing relevant problem situations. We compared physics problem descriptions by experts (n = 6) and by proficient (n = 6) and less proficient (n = 6) novices. We analyzed the situations that were described at the levels of words, sentences, and complete descriptions. Results indicate that competence is related to the structure of problem situations rather than the use of particular concepts, and that the differences in the use of multiple representations are more prominent than differences in the use of one specific kind of representation. Results also indicate that the differences between experts and novices are along different dimensions than the differences between more and less proficient novices. Implications for teaching are discussed. © 2002 Wiley Periodicals, Inc. J Res Sci Teach 39: 928–951, 2002
Correction for long‐term instrumental drift
Authors: Rousseau Richard M. 
Published: November 2002

AbstractA method of correcting for instrumental drift must be associated with any calibration procedure in order to validate the stored calibration data (slopes and intercepts) over a long period of time. Indeed, it can usually be observed that the drift is negligible for a 24 h period, but over longer periods corrections to the measured intensities have to be made. These corrections are based on the measurement of special specimens known as drift monitors or simply monitors. Physically, the monitor can comprise one to several specimens, each containing one or several analytes of which the intensity of each analyte is slightly higher than the highest intensity in the analyte concentration range. The other two essential properties of a monitor are its stability over time and reproducibility of its intensity measurements. A drift correction must be applied to the measured intensities of every analyte using one, two or several monitors depending on the spread of the intensity ranges. Some drift correction methods are proposed and it is explained how to combine them with the calibration procedure in order to obtain precise analytical results over long periods of time from the same set of calibration data. Copyright © 2002 John Wiley & Sons, Ltd.
Quantitative characterization of microsamples by x‐ray fluorescence tomography
Authors: Chukalina M. , Simionovici A. , Snigirev A. , Jeffries T. 
Published: November 2002

AbstractA novel semi‐quantitative algebraic reconstruction technique for x‐ray fluorescence tomography data sets is described and its use is demonstrated on laser‐ablated resin samples. The experiments were performed at the ID22 beamline of the European Synchrotron Radiation Facility in Grenoble. The projections were collected using a parallel scheme using 22.5 keV x‐rays at 4 µm resolution. The iterative algebraic reconstruction technique was used to calculate an elemental ‘effective’ concentration distribution. This ‘effective’ concentration is introduced for the first time and allows the attenuation of both the incident x‐ray beam and the fluorescence to be included in the reconstruction procedure. Copyright © 2002 John Wiley & Sons, Ltd.
Vacant states of TiO2 with rutile structure and their reflection in different‐type x‐ray absorption spectra
Authors: Finkelstein L. D. , Zabolotzky E. I. , Korotin M. A. , Shamin S. N. , Butorin S. M. , Kurmaev E. Z. , Nordgren J. 
Published: November 2002

AbstractA tight‐binding linearized muffin‐tin orbital method was applied for the calculation of the densities of states (DOS) for TiO2 with the rutile structure in the wide energy region of the conduction band. The calculated partial DOS of titanium and oxygen were compared with the experimental Ti 2p total electron yield spectrum (TEY), which was measured in the present work, and the Ti 1s x‐ray absorption spectrum, O 1s TEY and bremstrahlung isochromat spectrum taken from the literature. We found that in the energy region higher than ∼6 eV above the bottom of the conduction band the fine structure of experimental absorption spectra follows the distribution of the corresponding partial DOS. In connection with this, one does not need to use any satellite mechanism for an interpretation of these spectra. In the region of vacant Ti 3d states (up to ∼6 eV), correspondence between the experimental and calculated splitting of t2g and eg subbands is observed in all spectra except Ti 2p TEY. As we showed using atomic calculations, this is connected with the Ti 2p53d1 multiplet in the final state of absorption which leads to suppression of the intensity of lower states of the t2g subband in Ti 2p TEY of TiO2. As a result, t2g–eg splitting extracted from Ti 2p3/2 and Ti 2p1/2 TEY is less than in Ti 3d DOS and other experimental spectra (Ti 1s XAS and O 1s TEY) in which an interaction of core level vacancy with photoelectron is absent owing to the delocalized character of valent states. Copyright © 2002 John Wiley & Sons, Ltd.