60 research outputs found
Opening the 'black box' of efficiency measurement: input allocation in multi-output settings.
We develop a new Data Envelopment Analysis (DEA)-based methodology for measuring the efficiency of Decision Making Units (DMUs) characterized by multiple inputs and multiple outputs. The distinguishing feature of our method is that it explicitly includes information about output-specific inputs and joint inputs in the efficiency evaluation. This contributes to opening the „black box‟ of efficiency measurement in two different ways. First, including information on the input allocation substantially increases the discriminatory power of the efficiency measurement. Second, it allows to decompose the efficiency value of a DMU into output-specific efficiency values which facilitates the identification of the outputs the manager should focus on to remedy the observed inefficiency. We demonstrate the usefulness and managerial implications of our methodology by means of a unique dataset collected from the Activity Based Costing (ABC) system of a large service company with 290 DMUs.
Opening the 'black box' of efficiency measurement: input allocation in multi-output settings
We develop a new Data Envelopment Analysis (DEA)-based methodology for measuring the efficiency of Decision Making Units (DMUs) characterized by multiple inputs and multiple outputs. The distinguishing feature of our method is that it explicitly includes information about output-specific inputs and joint inputs in the efficiency evaluation. This contributes to opening the „black box? of efficiency measurement in two different ways. First, including information on the input allocation substantially increases the discriminatory power of the efficiency measurement. Second, it allows to decompose the efficiency value of a DMU into output-specific efficiency values which facilitates the identification of the outputs the manager should focus on to remedy the observed inefficiency. We demonstrate the usefulness and managerial implications of our methodology by means of a unique dataset collected from the Activity Based Costing (ABC) system of a large service company with 290 DMUs.
Thermal niche differentiation in the benthic diatom Cylindrotheca closterium (Bacillariophyceae) complex
Coastal waters are expected to undergo severe warming in the coming decades. Very little is known about how diatoms, the dominant primary producers in these habitats, will cope with these changes. We investigated the thermal niche of Cylindrotheca closterium, a widespread benthic marine diatom, using 24 strains collected over a wide latitudinal gradient. A multi-marker phylogeny in combination with a species delimitation approach shows that C. closterium represents a (pseudo)cryptic species complex, and this is reflected in distinct growth response patterns in terms of optimum growth temperature, maximum growth rate, and thermal niche width. Strains from the same Glade displayed a similar thermal response, suggesting niche conservation between closely related strains. Due to their lower maximum growth rate and smaller thermal niche width, we expect the polar species to be particularly sensitive to warming, and, in the absence of adaptation, to be replaced with species from lower latitudes
Haloperoxidase mediated quorum quenching by Nitzschia cf pellucida: study of the metabolization of N-acyl homoserine lactones by a benthic diatom
Diatoms are known to produce a variety of halogenated compounds, which were recently shown to have a role in allelopathic interactions between competing species. The production of these compounds is linked to haloperoxidase activity. This research, has shown that this system may also be involved in diatom-bacteria interactions via the H2O2 dependent inactivation of a type of quorum sensing (QS) molecule, i.e., N-beta-ketoacylated homoserine lactones (AHLs), by a natural haloperoxidase system from the benthic diatom Nitzschia cf pellucida. The AHL degradation pathway towards corresponding halogenated derivatives was elucidated via HPLC-MS analysis and the synthesis of a broad series of novel halogenated AHL analogues as reference compounds. Furthermore, their biological activity as quorum sensing modulators was directly compared and evaluated against a series of naturally occurring beta-keto-AHLs. It has been demonstrated that the loss of the QS activity results from the final cleavage of the halogenated N-acyl chain of the signal molecules
Microbial biodiversity in polar lake ecosystems: why is it different at the North and South Pole?
Global radiation in a rare biosphere soil diatom
Soil micro-organisms drive the global carbon and nutrient cycles that underlie essential ecosystem functions. Yet, we are only beginning to grasp the drivers of terrestrial microbial diversity and biogeography, which presents a substantial barrier to understanding community dynamics and ecosystem functioning. This is especially true for soil protists, which despite their functional significance have received comparatively less interest than their bacterial counterparts. Here, we investigate the diversification of Pinnularia borealis, a rare biosphere soil diatom species complex, using a global sampling of >800 strains. We document unprecedented high levels of species-diversity, reflecting a global radiation since the Eocene/Oligocene global cooling. Our analyses suggest diversification was largely driven by colonization of novel geographic areas and subsequent evolution in isolation. These results illuminate our understanding of how protist diversity, biogeographical patterns, and members of the rare biosphere are generated, and suggest allopatric speciation to be a powerful mechanism for diversification of micro-organisms
On the identity of Navicula gottlandica (Bacillariophyta), with the description of two new species Navicula eileencoxiana and Navicula bergstromiana from the Australo-Pacific region
During the past two decades, the subantarctic diatom flora has been the subject of several detailed taxonomic revisions, resulting in the description of a large number of new species. During a survey of the freshwater diatom flora of Macquarie Island (southern Pacific Ocean), an unknown Navicula species was observed showing resemblance to Navicula gottlandica. Populations of similar diatoms (previously reported as N. gottlandica) from Tasmania were also investigated. We here present a detailed morphological analysis of these diatoms, and compare it with the type material of N. gottlandica
Reliability and Validity of the Supports Intensity Scale (SIS) Measured in Adults with Physical Disabilities
The objective of this study was to investigate the internal consistency and the construct validity of the Dutch version of the Supports Intensity Scale (SIS-NL1.0; Buntinx 2006) in individuals with physical disabilities (N = 65). To investigate the construct validity, the relationship between SIS subscales and practical skills (Barthel Index; BI) was calculated. Support was provided for the internal consistency. The SIS subscales (except Behavior) had moderate to high intercorrelations and the SIS was able to discriminate between groups with different number of disabilities. However, weak relationships were found between the BI and four out of eight SIS subscales. For people with physical disabilities, future revisions of the SIS should also take into consideration limitations in practical skills in other support domains
Diatom distributions in space and time – a case study from the polar regions
第3回極域科学シンポジウム/第34回極域生物シンポジウム 11月27日(火) 統計数理研究所 3階セミナー
- …