Intra-seasonal rainfall variability and herbivory affect the interaction outcome of two dryland plant species

Increases in drought frequency in combination with overgrazing may result in degradation of (semi-) arid ecosystems. Facilitative interactions between plants are a key mechanism in preventing degradation, but it is poorly understood how they respond to increased stress by combined drought and herbivory. In this study, we used an ecohydrological model, to simulate the plant growth of two plant species interacting with each other under different rainfall and herbivory pressure scenarios. The functional traits of the two modeled plants were based on a prior field experiment in southeastern Spain, in which an unpalatable “nurse” species protected a palatable protégé’ species from herbivory. Moreover, the nurse species was more drought-resistant; that is, it had a lower wilting point, whereas the protégé species had a higher optimal growth rate. Firstly, we investigated the coexistence of the two plant species growing under a single limiting resource, focusing on the effect of intra-seasonal rainfall variability. We found that longer periods without rainfall within the wet season resulted in stable coexistence, whereas nearly constant rainfall led to competitive exclusion of the protégé by the nurse species. Secondly, we investigated how plant interactions varied along our studied gradients. Using the neighbor effect intensity and importance indices, we found that competitive effects increased with more constant rainfall. Moreover, higher herbivory rates resulted in increased facilitative effects of the nurse on the protégé species, but facilitative effects could only prevail over competitive effects under currently observed or higher intra-seasonal rainfall variability. This study highlights the relevance of intra-seasonal rainfall variability in explaining coexistence of species in dryland ecosystems and shows that increasing intra-seasonal rainfall variability or herbivory pressure can result in more facilitative effects from a nurse species. This information is crucial to obtain a better insight into the long-term coexistence of species, and the resulting stability of dryland ecosystems in response to future climate change

Hole in the Wall: Informed Short Selling ahead of Private Placements

__Abstract__ Companies planning a private placement typically gauge the interest of potential buyers before the offering is publicly announced. Regulators are concerned with this practice, called wall-crossing, as it might invite insider trading, especially when the potential investors are hedge funds. We examine privately placed common stock and convertible offerings and find widespread evidence of pre-announcement short selling. We show that pre-announcement short sellers are able to predict announcement day returns. The effects are especially strong when hedge funds are involved and when the number of buyers is high

Frailty and functional outcomes after open and endovascular procedures for patients with peripheral arterial disease:A systematic review

Background: Frailty has been associated with postoperative complications and mortality across surgical specialties, including vascular surgery. However, the influence of frailty on postoperative functional outcomes is unclear. We sought to determine the influence of frailty on functional outcomes after open or endovascular vascular procedures in patients with peripheral arterial disease. Methods: This systematic review was conducted according to the PRISMA guidelines. Eligible articles were identified through database searches of Pubmed and EMBASE in April 2017. Studies reporting on frailty and functional outcomes after vascular interventions for peripheral artery disease (PAD) were included. Outcomes of interest were dependency in activities of daily living (ADL), dependent mobility, discharge destination, disability-free survival, and quality of life. Individual studies were assessed for quality and risk of bias using the Quality in Prognosis Studies tool. Results: Eight studies met the eligibility criteria and were included. The risk of bias was low in two studies, intermediate in three studies, and high in three studies. Methods for frailty assessment were different for each study. Frailty was a predictor for discharge to a higher level of care, dependent mobility, and dependency in ADL after vascular procedures for PAD. Both frailty models and individual frailty characteristics seem to be associated with these adverse functional outcomes. Conclusions: Despite a limited amount of literature and an overall intermediate quality of the included studies, this systematic review shows an association between frailty and adverse functional outcomes after peripheral arterial procedures for PAD, including discharge to a care facility, dependent mobility, and a decline in ADL functioning

Gendered prices

We provide evidence that culture is a source of pricing bias. In a sample of 1.9 million auction transactions in 49 countries, paintings by female artists sell at an unconditional discount of 42.1%. The gender discount increases with measures of country-level gender inequality—even in artist fixed effects regressions. Our results are robust to accounting for potential gender differences in art characteristics and their liquidity. Evidence from two experiments supports the argument that women's art may sell for less because it is made by women. However, the gender discount reduces over time as gender equality increases

Do state visits affect cross-border mergers and acquisitions

This paper studies the relation between state visits and cross-border merger and acquisition (M&A) activity. Based on 1161 state visits and 11,531 cross-border acquisitions, we find that corporations from visiting countries are more likely to acquire corporations in countries hosting the visit. Domestic acquisitions in the host country or M&As with non-visiting countries are not elevated. Evidence from instrumental variable analysis points towards a causal effect of state visits on M&A activity. Further analysis shows that the elevated M&A activity originating from visiting countries can be attributed to business networking and a reduction in investment uncertainty and cultural barriers

Non-Standard Errors

In statistics, samples are drawn from a population in a data-generating process (DGP). Standard errors measure the uncertainty in estimates of population parameters. In science, evidence is generated to test hypotheses in an evidence-generating process (EGP). We claim that EGP variation across researchers adds uncertainty: Non-standard errors (NSEs). We study NSEs by letting 164 teams test the same hypotheses on the same data. NSEs turn out to be sizable, but smaller for better reproducible or higher rated research. Adding peer-review stages reduces NSEs. We further find that this type of uncertainty is underestimated by participants

Binding the Smart City Human-Digital System with Communicative Processes

This chapter will explore the dynamics of power underpinning ethical issues within smart cities via a new paradigm derived from Systems Theory. The smart city is an expression of technology as a socio-technical system. The vision of the smart city contains a deep fusion of many different technical systems into a single integrated “ambient intelligence”. ETICA Project, 2010, p. 102). Citizens of the smart city will not experience a succession of different technologies, but a single intelligent and responsive environment through which they move. Analysis of such an environment requires a framework which transcends traditional ontologically-based models in order to accommodate this deep fusion. This chapter will outline a framework based on Latour’s Actor-Network Theory and Luhmann’s treatment of society as an autopoetic system. We shall use this framework to map the influence of relevant factors on ethical issues, irrespective of their composition or type. For example, under this treatment, both human praxis and technical design can be viewed as comparable tools of domination. This chapter will provide a framework for the analysis of relations between any elements of the smart city, ranging from top-level urban management processes down to individual device operations. While we will illustrate the use of this schema through examination of ethical issues arising from power dynamics within the smart city, it is intended that this example will demonstrate the wider utility of the model in general

Non-standard errors

In statistics, samples are drawn from a population in a data-generating process (DGP). Standard errors measure the uncertainty in estimates of population parameters. In science, evidence is generated to test hypotheses in an evidence generating process (EGP). We claim that EGP variation across researchers adds uncertainty: Non-standard errors (NSEs). We study NSEs by letting 164 teams test the same hypotheses on the same data. NSEs turn out to be sizable, but smaller for better reproducible or higher rated research. Adding peer-review stages reduces NSEs. We further find that this type of uncertainty is underestimated by participants