363 research outputs found

    Water balance complexities in ephemeral catchments with different land uses: Insights from monitoring and distributed hydrologic modeling

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    Although ephemeral catchments are widespread in arid and semiarid climates, the relationship of their water balance with climate, geology, topography, and land cover is poorly known. Here we use 4 years (2011–2014) of rainfall, streamflow, and groundwater level measurements to estimate the water balance components in two adjacent ephemeral catchments in south-eastern Australia, with one catchment planted with young eucalypts and the other dedicated to grazing pasture. To corroborate the interpretation of the observations, the physically based hydrological model CATHY was calibrated and validated against the data in the two catchments. The estimated water balances showed that despite a significant decline in groundwater level and greater evapotranspiration in the eucalypt catchment (104–119% of rainfall) compared with the pasture catchment (95–104% of rainfall), streamflow consistently accounted for 1–4% of rainfall in both catchments for the entire study period. Streamflow in the two catchments was mostly driven by the rainfall regime, particularly rainfall frequency (i.e., the number of rain days per year), while the downslope orientation of the plantation furrows also promoted runoff. With minimum calibration, the model was able to adequately reproduce the periods of flow in both catchments in all years. Although streamflow and groundwater levels were better reproduced in the pasture than in the plantation, model-computed water balance terms confirmed the estimates from the observations in both catchments. Overall, the interplay of climate, topography, and geology seems to overshadow the effect of land use in the study catchments, indicating that the management of ephemeral catchments remains highly challenging

    The striatal dopamine transporter in first-episode, drug-naive schizophrenic patients: evaluation by the new SPECT-ligand[99mTc]TRODAT-1

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    Following the current hypothesis that acute schizophrenic psychotic illness is associated with a triatal ‘hyperdopaminergic state’, presynaptic integrity and dopamine transporter (DAT) density in first-episode, neuroleptic-naive schizophrenic patients was measured by single-photonemission- tomography (SPECT) and compared with that in healthy control subjects. A new SPECT-ligand for assessment of the striatal DAT, the Technetium-99m-labelled tropane TRODAT-1 ([99mTc]TRODAT-1), was used. Ten inpatients suffering from a first acute schizophrenic episode and 10 age- and sex-matched healthy control subjects underwent SPECT with [99mTc]TRODAT-1. On the day of SPECT, psychopathological ratings were performed with the Brief Psychiatric Rating Scale (BPRS), the Positive and Negative Syndrome Scale (PANSS) and Schedule for Assessment of Negative Symptoms (SANS). Patients had not previously received any neuroleptic or antidepressant medication. Mean specific TRODAT-1 binding in the striatum did not differ significantly between the patient and the age- and sex-matched control group (1.25 vs. 1.28). Variance was significantly higher in the patient group. The data obtained with the new ligand in first-episode, drug-naive schizophrenic patients are in line with the PET results from the group of Laakso et al. in a comparable patient sample. [99mTc]TRODAT-1 seems to be a valuable new SPECTligand in the evaluation of the presynaptic site of the striatal dopaminergic synapse in schizophrenia

    Striatal dopamine D2 receptor binding of risperidone in schizophrenic patients as assessed by 123I-iodobenzamide SPECT: a comparative study with olanzapine

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    The aim of this investigation was to compare the degree of striatal dopamine-(D2) receptor blockade by two atypical antipsychotic drugs, risperidone and olanzapine. The percentage of D2 receptor occupancy during treatment was calculated by comparing the results of 123I-iodobenzamide SPECT with those from healthy control subjects. Twenty inpatients suffering from schizophrenia or schizoaffective psychosis according to DSM IV/ICD-10 criteria were treated with clinically recommended doses of risperidone and compared with 13 inpatients treated with up to 20 mg olanzapine. Neuroleptic dose and D2 receptor blockade correlated strongly for both risperidone (Pearson r = –0.86, p = 0.0001) and olanzapine (Pearson r = –0.77, p = 0.002). There was no significant difference between the D2 receptor occupancy of the two substances when given in the clinically recommended dose range (unpaired t-test, t= –0.112, p=0.911)

    An Exploration of Some Pitfalls of Thematic Map Assessment Using the New Map Tools Resource

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    A variety of metrics are commonly employed by map producers and users to assess and compare thematic maps’ quality, but their use and interpretation is inconsistent. This problem is exacerbated by a shortage of tools to allow easy calculation and comparison of metrics from different maps or as a map’s legend is changed. In this paper, we introduce a new website and a collection of R functions to facilitate map assessment. We apply these tools to illustrate some pitfalls of error metrics and point out existing and newly developed solutions to them. Some of these problems have been previously noted, but all of them are under-appreciated and persist in published literature. We show that binary and categorical metrics, including information about true-negative classifications, are inflated for rare categories, and more robust alternatives should be chosen. Most metrics are useful to compare maps only if their legends are identical. We also demonstrate that combining land-cover classes has the often-neglected consequence of apparent improvement, particularly if the combined classes are easily confused (e.g., different forest types). However, we show that the average mutual information (AMI) of a map is relatively robust to combining classes, and reflects the information that is lost in this process; we also introduce a modified AMI metric that credits only correct classifications. Finally, we introduce a method of evaluating statistical differences in the information content of competing maps, and show that this method is an improvement over other methods in more common use. We end with a series of recommendations for the meaningful use of accuracy metrics by map users and producer

    Relations between teachers' goal orientations, their instructional practices and student motivation

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    Relations between teachers’ goal orientations, their instructional practices as expressed in perceived class- room goal structures and students’ goal orientations were analyzed, focusing also on potential moderators. Results of a questionnaire study with 46 Mathematics teachers and their 930 students supported the as-sumption that teachers’ goal orientations affect their instructional practices and students’ goal orientations. These effects were, in part, moderated by teacher beliefs (implicit theories, self-efficacy beliefs). Overall, the results provided strong support for the notion that the mechanisms underlying these effects are based on the functionality of certain instructional practices for the attainment of teachers’ goals

    LACO-Wiki: A land cover validation tool and a new, innovative teaching resource for remote sensing and the geosciences

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    The validation of land cover products is an important step in the workflow of generating a land cover map from remotely-sensed imagery. Many students of remote sensing will be given exercises on classifying a land cover map followed by the validation process. Many algorithms exist for classification, embedded within proprietary image processing software or increasingly as open source tools. However, there is little standardization for land cover validation, nor a set of open tools available for implementing this process. The LACO-Wiki tool was developed as a way of filling this gap, bringing together standardized land cover validation methods and workflows into a single portal. This includes the storage and management of land cover maps and validation data; step-by-step instructions to guide users through the validation process; sound sampling designs; an easy-to-use environment for validation sample interpretation; and the generation of accuracy reports based on the validation process. The tool was developed for a range of users including producers of land cover maps, researchers, teachers and students. The use of such a tool could be embedded within the curriculum of remote sensing courses at a university level but is simple enough for use by students aged 13-18. A beta version of the tool is available for testing at: http://www.lacowiki.net

    Goal orientations of teacher trainees: Longitudinal analysis of magnitude, change and relevance

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    The central focus of this paper is to address the magnitudes of and changes in four central components of teacher goal orientation (learning, performance approach, performance avoidance and work avoidance goal orientation) among prospective teachers. The findings reported here were gathered with a sample of 130 teacher trainees who responded to questionnaires at five measuring points over the course of the two years pre-service training which comprise the second phase of teacher education ("Referendariat"). Differential magnitudes and changes in teacher trainees\u27 goal orientations were analyzed using a hierarchical linear modeling approach. Cluster analyses were able to identify three typical growth trajectory patterns in goal orientation which were differentially associated with achievement levels at the end of the second phase of teacher education, stress experiences, attitudes concerning help seeking, as well as dropout tendencies. (DIPF/Orig.)Im Zentrum des vorliegenden Beitrags stehen die differentiellen Ausprägungen und Veränderungen der vier zentralen Komponenten der Lehrkraftzielorientierung von angehenden Lehrkräften (Lern-, Annäherungsperformanz-, Vermeidungsperformanz- und Arbeitsvermeidungszielorientierung). Berichtet werden die Befunde einer Stichprobe von 130 Lehramtsanwärter(inne)n, die im Laufe der zweijährigen zweiten Phase der Lehramtsausbildung ("Referendariat") zu fünf Messzeitpunkten schriftlich befragt wurden. Individuelle Ausprägungen und Veränderungen der Zielorientierungen der angehenden Lehrer(innen) wurden mit Hilfe einer hierarchisch-linearen Modellierungsstrategie analysiert. Clusteranalytisch wurden drei typische Verlaufsmuster der Zielorientierungen identifiziert, die mit den Leistungen am Ende des Referendariats, dem Belastungserleben, den Einstellungen gegenüber Hilfe sowie der Abbruchtendenz im Zusammenhang standen. (DIPF/Orig.

    LACO-Wiki: A New Online Land Cover Validation Tool Demonstrated Using GlobeLand30 for Kenya

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    Accuracy assessment, also referred to as validation, is a key process in the workflow of developing a land cover map. To make this process open and transparent, we have developed a new online tool called LACO-Wiki, which encapsulates this process into a set of four simple steps including uploading a land cover map, creating a sample from the map, interpreting the sample with very high resolution satellite imagery and generating a report with accuracy measures. The aim of this paper is to present the main features of this new tool followed by an example of how it can be used for accuracy assessment of a land cover map. For the purpose of illustration, we have chosen GlobeLand30 for Kenya. Two different samples were interpreted by three individuals: one sample was provided by the GlobeLand30 team as part of their international efforts in validating GlobeLand30 with GEO (Group on Earth Observation) member states while a second sample was generated using LACO-Wiki. Using satellite imagery from Google Maps, Bing and Google Earth, the results show overall accuracies between 53% to 61%, which is lower than the global accuracy assessment of GlobeLand30 but may be reasonable given the complex landscapes found in Kenya. Statistical models were then fit to the data to determine what factors affect the agreement between the three interpreters such as the land cover class, the presence of very high resolution satellite imagery and the age of the image in relation to the baseline year for GlobeLand30 (2010). The results showed that all factors had a significant effect on the agreement

    Study satisfaction among university students during the COVID-19 pandemic: longitudinal development and personal-contextual predictors

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    The COVID-19 pandemic challenges the well-being and academic success of many students. Yet, little is known about students’ study satisfaction during the COVID-19 pandemic, a multilayered construct which accounts for students’ subjective cognitive well-being and academic success. Besides, previous studies on study satisfaction are mostly cross-sectional and hardly consider the distinct subdimensions of this construct. Therefore, our main goal in this study was to shed light on the understudied development of the subdimensions of study satisfaction (i.e., satisfaction with study content, conditions of studying, and coping with study-related stress) in two semesters amid the COVID-19 pandemic. Additionally, we examined how particular personal (i.e., gender, age, GPA, intrinsic motivation, motivational cost, and academic procrastination) and contextual (i.e., loneliness) factors are related to these subdimensions. We conducted two panel studies with convenience and purposeful samples of university students in Germany (Nstudy1 = 837; Nstudy2 = 719). Participants responded online to questions on each of the subdimensions of study satisfaction at the beginning, middle, and end of each semester but responded to measures of personal and contextual factors only at the beginning of each semester. In both studies, manifest growth curve models indicated a decrease in all subdimensions of study satisfaction as the semester progressed. Generally, gender (male) and intrinsic motivation were positive predictors but age (younger students), motivational cost, and loneliness were negative predictors of different subdimensions of study satisfaction – particularly satisfaction with study content. Overall, motivational costs and loneliness were the most consistent predictors of all subdimensions of study satisfaction across both studies. Our findings provide support for the understanding that study satisfaction could diminish in the face of challenging situations such as in this pandemic. The present study also highlights certain personal and contextual factors that relate to study satisfaction and calls for intensive research into the multidimensional construct of study satisfaction
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