Strategic or Status quo-Preserving Business Exit: (How) Do CEO Turnover and Succession Matter?

Business exit has implications for a firm’s corporate strategy. Two types of exit events are distinguished: those that involve strategic change and those that are status quo-preserving. This study investigates the impact of CEO turnover and succession on strategic versus status quo-preserving business exits. Based on a sample of CEO turnover and succession events and subsequent business exits of German corporations from different industries, our results suggest that neither voluntary nor involuntary CEO turnover is relevant to business exit. In contrast, outsider succession significantly affects the likelihood of strategic business exit, while a corporation’s performance does not moderate this relationship

Adaptation to enemy shifts: rapid resistance evolution to local Vibrio spp. in invasive Pacific oysters

One hypothesis for the success of invasive species is reduced pathogen burden, resulting from a release from infections or high immunological fitness of invaders. Despite strong selection exerted on the host, the evolutionary response of invaders to newly acquired pathogens has rarely been considered. The two independent and genetically distinct invasions of the Pacific oyster Crassostrea gigas into the North Sea represent an ideal model system to study fast evolutionary responses of invasive populations. By exposing both invasion sources to ubiquitous and phylogenetically diverse pathogens (Vibrio spp.), we demonstrate that within a few generations hosts adapted to newly encountered pathogen communities. However, local adaptation only became apparent in selective environments, i.e. at elevated temperatures reflecting patterns of disease outbreaks in natural populations. Resistance against sympatric and allopatric Vibrio spp. strains was dominantly inherited in crosses between both invasion sources, resulting in an overall higher resistance of admixed individuals than pure lines. Therefore, we suggest that a simple genetic resistance mechanism of the host is matched to a common virulence mechanism shared by local Vibrio strains. This combination might have facilitated a fast evolutionary response that can explain another dimension of why invasive species can be so successful in newly invaded ranges

(how) do CEO turnover and succession matter?

Business exit has implications for a firm’s corporate strategy. Two types of exit events are distinguished: those that involve strategic change and those that are status quo-preserving. This study investigates the impact of CEO turnover and succession on strategic versus status quo-preserving business exits. Based on a sample of CEO turnover and succession events and subsequent business exits of German corporations from different industries, our results suggest that neither voluntary nor involuntary CEO turnover is relevant to business exit. In contrast, outsider succession significantly affects the likelihood of strategic business exit, while a corporation’s performance does not moderate this relationship

Persistence, seasonal dynamics and pathogenic potential of Vibrio communities from pacific oyster hemolymph

Bacteria of the genus Vibrio occur at a continuum from free-living to symbiotic life forms, including opportunists and pathogens, that can contribute to severe diseases, for instance summer mortality events of Pacific oysters Crassostrea gigas. While most studies focused on Vibrio isolated from moribund oysters during mortality outbreaks, investigations of the Vibrio community in healthy oysters are rare. Therefore, we characterized the persistence, diversity, seasonal dynamics, and pathogenicity of the Vibrio community isolated from healthy Pacific oysters. In a reciprocal transplant experiment we repeatedly sampled hemolymph from adult Pacific oysters to differentiate population from site-specific effects during six months of in situ incubation in the field. We characterized virulence phenotypes and genomic diversity based on multilocus sequence typing in a total of 70 Vibrio strains. Based on controlled infection experiments we could show that strains with the ability to colonize healthy adult oysters can also have the potential to induce high mortality rates on larvae. Diversity and abundance of Vibrio varied significantly over time with highest values during and after spawning season. Vibrio communities from transplanted and stationary oysters converged over time, indicating that communities were not population specific, but rather assemble from the surrounding environment forming communities, some of which can persist over longer period

The behaviour of random forest permutation-based variable importance measures under predictor correlation

<p>Abstract</p> <p>Background</p> <p>Random forests (RF) have been increasingly used in applications such as genome-wide association and microarray studies where predictor correlation is frequently observed. Recent works on permutation-based variable importance measures (VIMs) used in RF have come to apparently contradictory conclusions. We present an extended simulation study to synthesize results.</p> <p>Results</p> <p>In the case when both predictor correlation was present and predictors were associated with the outcome (H_A), the unconditional RF VIM attributed a higher share of importance to correlated predictors, while under the null hypothesis that no predictors are associated with the outcome (H₀) the unconditional RF VIM was unbiased. Conditional VIMs showed a decrease in VIM values for correlated predictors versus the unconditional VIMs under H_Aand was unbiased under H₀. Scaled VIMs were clearly biased under H_Aand H₀.</p> <p>Conclusions</p> <p>Unconditional unscaled VIMs are a computationally tractable choice for large datasets and are unbiased under the null hypothesis. Whether the observed increased VIMs for correlated predictors may be considered a "bias" - because they do not directly reflect the coefficients in the generating model - or if it is a beneficial attribute of these VIMs is dependent on the application. For example, in genetic association studies, where correlation between markers may help to localize the functionally relevant variant, the increased importance of correlated predictors may be an advantage. On the other hand, we show examples where this increased importance may result in spurious signals.</p

Effect of AlSi10Mg0.4 long-term reused powder in PBF-LB/M on the mechanical properties

Laser-based powder bed fusion (PBF-LB/M) is a well-established additive manufacturing (AM) process capable of producing high quality parts with excellent mechanical properties. Industrial applications of additively manufactured parts require the usage of fresh powder which makes the process expensive, especially in case of AM machines with enlarged build envelopes. Processing long-term reused powder fits to economic yields with the drawback of increased porosity and incorporated oxides. In this study, a detailed analysis of components made of virgin and long-term reused AlSi10Mg0.4 powder is provided. The experiments reveal that process parameters qualified for the virgin powder are not working offhand for the reused powder, as an increase of porosity from less than 1 % up to 3 % and a decline of tensile strength as well as yield strength of about 15 % are observed. The results indicate that powder degradation, which is based on the formation of hydroxides and oxides, has a significant impact on as-built microstructure as well as mechanical properties of additively manufactured parts. The amount of hydrogen and oxygen is measured for different powder conditions and the powder ageing process of AlSi10Mg0.4 is discussed in detail

The Erythropoietin Promoter Variant rs1617640 Is Not Associated with Severe Retinopathy of Prematurity, Independent of Treatment with Erythropoietin

In this case-control study, the erythropoietin (EPO) promoter variant s1617640, linked to high intravitreal EPO concentrations and increased risk of diabetic retinopathy, was not associated with severe retinopathy of prematurity. This finding was observed both in infants with and without recombinant EPO administration

Technical improvement of the Detia Degesch Phosphine Tolerance Test Kit: Presentation

Phosphine is the most important commonly used fumigant for the control of stored product insects in warehouses and processing facilities globally. However, the improper and extensive use has led to reduced susceptibility to phosphine for several insect species and strains in many parts of the world. To evaluate and quantify this phenomenon, Detia Degesch developed the Detia Degesch Phosphine Tolerance Test Kit (DDPTTK) more than 10 years ago. The use of DDPTTK is based on the exposure of the insects on a high concentration of phosphine (e.g. 3000 ppm) for short exposure periods (e.g. 8-15 min). This kit can be used on site by the fumigation and food industry, and can provide immediate results on the tolerance status of the insect strains that are to be treated. So far, the instructions of DDPTTK refer only to a six insect species. In this work, data for the expansion of knowledge about other species is provided, in order to broaden the spectrum of cases where the kit can be used. Moreover, certain improvements for the use of the kit are introduced, i.e. practical recommendations on the procedure and safety instructions.Phosphine is the most important commonly used fumigant for the control of stored product insects in warehouses and processing facilities globally. However, the improper and extensive use has led to reduced susceptibility to phosphine for several insect species and strains in many parts of the world. To evaluate and quantify this phenomenon, Detia Degesch developed the Detia Degesch Phosphine Tolerance Test Kit (DDPTTK) more than 10 years ago. The use of DDPTTK is based on the exposure of the insects on a high concentration of phosphine (e.g. 3000 ppm) for short exposure periods (e.g. 8-15 min). This kit can be used on site by the fumigation and food industry, and can provide immediate results on the tolerance status of the insect strains that are to be treated. So far, the instructions of DDPTTK refer only to a six insect species. In this work, data for the expansion of knowledge about other species is provided, in order to broaden the spectrum of cases where the kit can be used. Moreover, certain improvements for the use of the kit are introduced, i.e. practical recommendations on the procedure and safety instructions

Introducing a Longitudinal Study of Community Gardeners and Gardens in New York City

For almost a decade, the NYC Department of Parks and Recreation GreenThumb program has collected data about hundreds of New York City community gardens citywide to understand how these gardens function. Building on a data set that includes surveys and interviews conducted periodically with garden representatives since 2003, GreenThumb and USDA Forest Service researchers have conducted a new round of community garden interviews examining membership, programming, partnerships, and motivations for gardening. This comprehensive study of the largest community gardening program in the United States aims to understand the evolving role of community gardens in New York City. The study asks: From 2003-2011, is gardeners’ motivation for creating and participating in community gardens persistent or changing? How do the use and social functions of community gardens evolve or remain the same? What sort of programs and community events are held in gardens? How has garden membership changed over time? Is membership increasing, decreasing, or staying the same? Who participates in gardening in neighborhoods with changing demographics? During the summer of 2011, structured interviews were conducted by phone with representatives from a sample of 102 community gardens for which survey data existed from 2003, 2007, and 2009. These research findings will help assess the ways in which New York City community gardens have evolved and can continue to grow in the future