Common Ownership, Competition, and Top Management Incentives

When one firm’s strategy affects other firms’ value, optimal executive incentives depend on whether shareholders have interests in only one or in multiple firms. Performance-sensitive contracts induce managerial effort to reduce costs, and lower costs induce higher output. Hence, greater managerial effort can lead to lower product prices and industry profits. Therefore, steep managerial incentives can be optimal for a single firm and at the same time violate the interests of common owners of several firms in the same industry. Empirically, managerial wealth is more sensitive to performance when a firm’s largest shareholders do not own large stakes in competitors

Shifts in plant and soil C, N and P accumulation and C:N:P stoichiometry associated with flooding intensity in subtropical estuarine wetlands in China

Flooding caused by rising sea levels can influence the biogeochemistry of estuarine wetland ecosystems. We studied the relationships of higher flooding intensity with soil carbon (C), nitrogen (N) and phosphorus (P) concentrations in communities of the native sedge Cyperus malaccensis var. brevifolius Boecklr. in the wetlands of the Minjiang River estuary in China. The aboveground and total biomasses of C. malaccensis were higher in high-flooding habitats than in intermediate- and low-flooding habitats. These differences in plant biomass were accompanied by a lower N:P ratio in the aboveground biomass and a higher N:P ratio in the belowground biomass. Higher intensities of flooding were associated with higher soil N and P concentrations in intermediate and deep soil layers. The higher P concentration under flooding was mainly associated with the higher clay content, whereas the higher N concentration was associated with higher salinity. Flooding intensity did not have a net total effect on soil total C concentration. The positive direct effect of flooding intensity on total soil C concentration was counteracted by its positive effects on CH4 emissions and soil salinity. The results suggest that C. malaccensis wetlands will be able to maintain and even increase the current C, N and P storage capacity of the ecosystem under moderate increases of flooding in the Minjiang River estuary

Mathematical models of cytotoxic effects in endpoint tumor cell line assays: Critical assessment of the application of a single parametric value as a standard criterion to quantify the dose-response effects and new unexplored proposal formats

The development of convenient tools for describing and quantifying the effects of standard and novel therapeutic agents is essential for the research community, to perform more precise evaluations. Although mathematical models and quantification criteria have been exchanged in the last decade between different fields of study, there are relevant methodologies that lack proper mathematical descriptions and standard criteria to quantify their responses. Therefore, part of the relevant information that can be drawn from the experimental results obtained and the quantification of its statistical reliability are lost. Despite its relevance, there is not a standard form for the in vitro endpoint tumor cell lines' assays (TCLA) that enables the evaluation of the cytotoxic dose-response effects of anti-tumor drugs. The analysis of all the specific problems associated with the diverse nature of the available TCLA used is unfeasible. However, since most TCLA share the main objectives and similar operative requirements, we have chosen the sulforhodamine B (SRB) colorimetric assay for cytotoxicity screening of tumor cell lines as an experimental case study. In this work, the common biological and practical non-linear dose-response mathematical models are tested against experimental data and, following several statistical analyses, the model based on the Weibull distribution was confirmed as the convenient approximation to test the cytotoxic effectiveness of anti-tumor compounds. Then, the advantages and disadvantages of all the different parametric criteria derived from the model, which enable the quantification of the dose-response drug-effects, are extensively discussed. Therefore, model and standard criteria for easily performing the comparisons between different compounds are established. The advantages include a simple application, provision of parametric estimations that characterize the response as standard criteria, economization of experimental effort and enabling rigorous comparisons among the effects of different compounds and experimental approaches. In all experimental data fitted, the calculated parameters were always statistically significant, the equations proved to be consistent and the correlation coefficient of determination was, in most of the cases, higher than 0.98.The authors are grateful to the Foundation for Science and Technology (FCT) of Portugal and FEDER for financial support to CIMO (UID/AGR/00690/2013); and to the Xunta de Galicia for financial support for the post-doctoral research of M. A. Prieto.info:eu-repo/semantics/publishedVersio

An Initial Empirical Assessment of an Ontological Model of the Human Genome

Conceptual modeling is used to model application domains for which an information system is needed. One of the most complex domains to which conceptual modeling has been applied is that of the human genome. Due to its complexity, its understanding is often left to domain experts. Conceptual models represent genomics-related concepts, with various purposes, including domain clarification or data structures design for facilitating data integration. However, traditional conceptual models, which might be expressed, for example, with UML, may not be appropriate for properly explaining such a complex domain, thus requiring an additional layer to ground the model on well-accepted ontological foundations. To achieve this result, an “ontological unpacking” method has been proposed that uses OntoUML as a visual formalism. In this research, we carry out an empirical study to compare the two mentioned representations. The study involved a small group of participants, who responded to a set of questions by reading either a UML model or its related OntoUML unpacked version; the results enabled us to assess their understanding of the domain. We aim to initiate a practical evaluation framework to assess the effectiveness, efficiency and user beliefs of models derived by ontologically unpacking traditional conceptual models. The results of the analysis provide the basis for a broader assessment

Midge-stabilized sediment drives the composition of benthic cladoceran communities in Lake Mývatn, Iceland

The importance of environmental disturbances as drivers of ecological communities depends not only on the magnitude of the disturbance, but also on the disturbance-specific sensitivity of the community. Organisms that alter the physical structure of their surroundings can affect the sensitivity of their habitat to environmental disturbance, and may alter the potential for disturbance to shape ecological communities. Such organisms therefore act as ecosystem engineers by indirectly modifying the resources available to other species. The benthos of shallow, eutrophic Lake Mývatn, Iceland, is frequently disturbed by wind events that lead to sediment resuspension. The impact of wind, however, depends on the abundance of midges (Chironomidae) whose larval tubes bind sediment and reduce wind-driven resuspension. Here, we investigate the long-term effect of fluctuations in midge abundance on the benthic cladoceran community using two lake sediment cores representing 30 and 140 years of deposition. In both cores, midge remains show a significant positive correlation with abundance of a large benthic surface-dwelling cladoceran, Eurycercus lamellatus, relative to the abundance of a small within-sediment-dwelling cladoceran, Alona rectangula. To experimentally investigate whether this shift could have been caused by midges acting as ecosystem engineers, we subjected cladoceran communities to sediment resuspension events within mesocosms. We found a significant decrease in abundance of the large epibenthic E. lamellatus relative to the abundance of small infaunal Alona spp. when subjected to disturbance. These findings show that physical alteration of benthic sediment and hence the sensitivity of the sediment to disturbance may explain the community shift in cladocerans observed with fluctuating midge abundance in Lake Mývatn.National Science Foundation Graduate Research Fellowship. Grant Number: DGE-1256259 LTREB. Grant Number: DEB-1052160Peer Reviewe

Influence of inoculum preparation method on in vitro methane production by ruminal microorganisms

The characteristics of the inoculum are recognized as one of the most relevant factors influencing the results of in vitro fermentations in batch cultures of ruminal microorganisms. Four rumen-fistulated sheep fed a 66:34 alfalfa hay:concentrate diet were used as donors to investigate the effect of rumen contents’ processing on in vitro methane (CH4) and volatile fatty acid (VFA) production from 3 substrates of variable composition

Peroxisome proliferator-activated receptor β/δ activation inhibits hypertrophy in neonatal rat cardiomyocytes

Objective: Peroxisome proliferator-activated receptor β/δ (PPARβ/δ) is the predominant PPAR subtype in cardiac cells and plays a prominent role in the regulation of cardiac lipid metabolism. However, the role of PPARβ/δ activators in cardiac hypertrophy is not yet known. Methods and Results: In cultured neonatal rat cardiomyocytes, the selective PPARβ/δ activator L-165041 (10 μmol/L) inhibited phenylephrine (PE)-induced protein synthesis ([3H]leucine uptake), induction of the fetal-type gene atrial natriuretic factor (ANF) and cardiac myocyte size. Induction of cardiac hypertrophy by PE stimulation also led to a reduction in the transcript levels of both muscle-type carnitine palmitoyltransferase (50%, P<0.05) and pyruvatedehydrogenase kinase 4 (30%, P<0.05), and these changes were reversed in the presence of the PPARβ/δ agonist L-165041. Stimulation of neonatal rat cardiomyocytes with PE and embryonic rat heart-derived H9c2 cells with lipopolysaccharide (LPS) enhanced the expression of the nuclear factor (NF)-κB-target gene monocyte chemoattractant protein 1 (MCP-1). The induction of MCP-1 was reduced in the presence of L-165041, suggesting that this compound prevented NF-κB activation. Electrophoretic mobility shift assay (EMSA) revealed that L-165041 significantly decreased LPS-stimulated NF-κB binding activity in H9c2 myotubes. Finally, coimmunoprecipitation studies showed that L-165041 strongly enhanced the physical interaction between PPARβ/δ and the p65 subunit of NF-κB, suggesting that increased association between these two proteins is the mechanism responsible for antagonizing NF-κB activation by PPARβ/δ activators. Conclusion: These results suggest that PPARβ/δ activation inhibits PE-induced cardiac hypertrophy and LPS-induced NF-κB activatio