1,720,998 research outputs found
Structural investigations on Xe/Pd(111) with spin-polarized LEED
Full text linkHilgers G, Potthoff M, Müller N, Heinzmann U. Structural investigations on Xe/Pd(111) with spin-polarized LEED. Surface Science. 1993;287-288(1):414-417
Xe-adlayers on Pt(111) and Pd(111): structure investigation by spin-polarized LEED
Full text linkHilgers G, Potthoff M, Wirth S, et al. Xe-adlayers on Pt(111) and Pd(111): structure investigation by spin-polarized LEED. Surface Science. 1991;251-252:612-615
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe 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
Short-term effects of earthworm activity and straw amendment on the microbial C and N turnover in a remoistened arable soil after summer drought
No full textShort-term effects of actively burrowing Octolasion lacteum (ORL.) (Lumbricidae) on the microbial C and N turnover in an arable soil with a high clay content were studied in a microcosm experiment throughout a 16 day incubation. Treatments with or without amendment of winter wheat straw were compared under conditions of a moistening period after summer drought. The use of C-14 labeled straw allowed for analyzing the microbial use of different C components. Microbial biomass C, biomass N and ergosterol were only slightly affected by rewetting and not by O. lacteum in both cases. Increased values of soil microbial biomass were determined in the straw treatments even after 24 h of incubation. This extra biomass corresponded to the initial microbial colonization of the added straw. O. lacteum significantly increased CO2 production from soil organic matter and from the C-14-labeled straw. Higher release rates of C-14-CO2 were recorded shortly after insertion of earthworms. This effect remained until the end of the experiment. O. lacteum enhanced N mineralization. Earthworms significantly increased both mineral N content of soil and N leaching in the treatments without straw addition. Moreover, earthworms slightly reduced N immobilization in the treatments with straw addition. The immediate increase in microbial activity suggests that perturbation of soil is more important than substrate consumption for the effect of earthworms on C and N turnover in moistening periods after drought. (C) 2001 Elsevier Science Ltd. All rights reserved
Greenhouse estimates of CO2 and N2O emissions following surface application of grass mulch: importance of indigenous microflora of mulch
No full textThe effects of surface-applied, fresh grass mulch on CO2 and N2O emissions were determined for 7 weeks in a greenhouse microcosm study under aerated conditions with daily irrigation (1.8 mm day(-1)). Dynamics Of CO2 and N2O emissions were determined by automated, continuous flux measurements. Grass mulch was added (C input: 100 g C m(-2), N input: 9.2 g N m(-2)) to Soil columns (Ap horizon of a cambisol) and quartz sand columns to assess the importance of indigenous microflora of grass residues for mulch decomposition and N2O production. About 76% of the grass mulch carbon was respired within 50 days, regardless of whether the grass mulch was added to soil or quartz sand. Total N2O-N emissions caused by the surface application of grass mulch was equivalent to 0.3% (application on soil) and 0.2% (application on quartz sand) of the N applied in the grass mulch. As much as 89% of the diurnal variability in NO emission and 80% of the diurnal variability in CO2 release from the decomposing grass mulch could be explained by changes in the temperature. The results show that indigenous microflora present on the plant residues determine both the decomposition rate of the surface-applied grass mulch and N-mineralisation and denitrification of mulch N. (C) 2002 Elsevier Science Ltd. All rights reserved
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Carbon and nitrogen mineralization after maize harvest between and within maize rows: a microcosm study using C-13 natural abundance
No full textThe sequestration of carbon in soil is not completely understood, and quantitative information about the rates of soil organic carbon (SOC) turnover could improve understanding. We analyzed the effects of the uneven distribution of crop residues after harvest of silage maize on C and N losses (CO2-C, dissolved organic carbon (DOC) and nitrogen (DON), and NO3-) from a Haplic Phaeozem and on the occurrence of priming effects induced by the decomposition of accumulated maize residues. Soil columns were taken from a continuous maize (since 1961) field after harvest i) between maize stalk rows M-bare) ii) within the maize rows including a standing maize stalk (M-stalk), and iii) from a continuous rye (since 1878) field after tillage (rye stalk and roots were mixed into the Ap horizon). The soil columns were incubated for 230 days at 8 degreesC with an irrigation rate of 2mm 10(-2) M CaCl2 per day. Natural C-13 abundance was used to distinguish between maize-derived C (in SOC and maize residues) and older C originating from former C-3 vegetation
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe 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
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