117 research outputs found

    Conditional Allocation of Control Rights in Venture Capital Finance

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    When a young entrepreneurial firm matures, it is often necessary to replace the founding entrepreneur by a professional manager. This replacement decision can be affected by the private benefits of control enjoyed by the entrepreneur which gives rise to a conflict of interest between the entrepreneur and the venture capitalist. We show that a combination of convertible securities and contingent control rights can be used to resolve this conflict efficiently. This contractual arrangement is frequently observed in venture capital finance

    Design and Status of the Balloon Experimental Twin Telescope for Infrared Interferometry (BETTII): An Interferometer at the Edge of Space

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    The Balloon Experimental Twin Telescope for Infrared Interferometry (BETTII) is an 8-meter baseline far-infraredinterferometer designed to fly on a high altitude balloon. BETTII uses a double-Fourier Michelson interferometer tosimultaneously obtain spatial and spectral information on science targets; the long baseline permits subarcsecond angular resolution, a capability unmatched by other far-infrared facilities. Here, we present key aspects of the overall design of the mission and provide an overview of the current status of the project. We also discuss briefly the implications of this experiment for future space-based far-infrared interferometers

    Assessing the carcinogenic potential of low-dose exposures to chemical mixtures in the environment: the challenge ahead.

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    Lifestyle factors are responsible for a considerable portion of cancer incidence worldwide, but credible estimates from the World Health Organization and the International Agency for Research on Cancer (IARC) suggest that the fraction of cancers attributable to toxic environmental exposures is between 7% and 19%. To explore the hypothesis that low-dose exposures to mixtures of chemicals in the environment may be combining to contribute to environmental carcinogenesis, we reviewed 11 hallmark phenotypes of cancer, multiple priority target sites for disruption in each area and prototypical chemical disruptors for all targets, this included dose-response characterizations, evidence of low-dose effects and cross-hallmark effects for all targets and chemicals. In total, 85 examples of chemicals were reviewed for actions on key pathways/mechanisms related to carcinogenesis. Only 15% (13/85) were found to have evidence of a dose-response threshold, whereas 59% (50/85) exerted low-dose effects. No dose-response information was found for the remaining 26% (22/85). Our analysis suggests that the cumulative effects of individual (non-carcinogenic) chemicals acting on different pathways, and a variety of related systems, organs, tissues and cells could plausibly conspire to produce carcinogenic synergies. Additional basic research on carcinogenesis and research focused on low-dose effects of chemical mixtures needs to be rigorously pursued before the merits of this hypothesis can be further advanced. However, the structure of the World Health Organization International Programme on Chemical Safety 'Mode of Action' framework should be revisited as it has inherent weaknesses that are not fully aligned with our current understanding of cancer biology

    Campaign 9 of the K2 mission: Observational parameters, scientific drivers, and community involvement for a simultaneous space-and ground-based microlensing survey

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    K2ʼs Campaign 9 (K2C9) will conduct a ∼3.7 deg2 survey toward the Galactic bulge from 2016 April 22 through July 2 that will leverage the spatial separation between K2 and the Earth to facilitate measurement of the microlens parallax πE for ≳170 microlensing events. These will include several that are planetary in nature as well as many short-timescale microlensing events, which are potentially indicative of free-floating planets (FFPs). These satellite parallax measurements will in turn allow for the direct measurement of the masses of and distances to the lensing systems. In this article we provide an overview of the K2C9 space- and ground-based microlensing survey. Specifically, we detail the demographic questions that can be addressed by this program, including the frequency of FFPs and the Galactic distribution of exoplanets, the observational parameters of K2C9, and the array of resources dedicated to concurrent observations. Finally, we outline the avenues through which the larger community can become involved, and generally encourage participation in K2C9, which constitutes an important pathfinding mission and community exercise in anticipation of WFIRST

    TIC 168789840: A Sextuply Eclipsing Sextuple Star System

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    We report the discovery of a sextuply eclipsing sextuple star system from TESS data, TIC 168789840, also known as TYC 7037-89-1, the first known sextuple system consisting of three eclipsing binaries. The target was observed in Sectors 4 and 5 during Cycle 1, with lightcurves extracted from TESS Full Frame Image data. It was also previously observed by the WASP survey and ASAS-SN. The system consists of three gravitationally bound eclipsing binaries in a hierarchical structure of an inner quadruple system with an outer binary subsystem. Follow-up observations from several different observatories were conducted as a means of determining additional parameters. The system was resolved by speckle interferometry with a 0farcs42 separation between the inner quadruple and outer binary, inferring an estimated outer period of ~2 kyr. It was determined that the fainter of the two resolved components is an 8.217 day eclipsing binary, which orbits the inner quadruple that contains two eclipsing binaries with periods of 1.570 days and 1.306 days. Markov Chain Monte Carlo (MCMC) analysis of the stellar parameters has shown that the three binaries of TIC 168789840 are triplets, as each binary is quite similar to the others in terms of mass, radius, and Teff. As a consequence of its rare composition, structure, and orientation, this object can provide important new insight into the formation, dynamics, and evolution of multiple star systems. Future observations could reveal if the intermediate and outer orbital planes are all aligned with the planes of the three inner eclipsing binaries

    Empathy among undergraduate medical students: A multi-centre cross-sectional comparison of students beginning and approaching the end of their course

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    BACKGROUND: Although a core element in patient care the trajectory of empathy during undergraduate medical education remains unclear. Empathy is generally regarded as comprising an affective capacity: the ability to be sensitive to and concerned for, another and a cognitive capacity: the ability to understand and appreciate the other person's perspective. The authors investigated whether final year undergraduate students recorded lower levels of empathy than their first year counterparts, and whether male and female students differed in this respect. METHODS: Between September 2013 and June 2014 an online questionnaire survey was administered to 15 UK, and 2 international medical schools. Participating schools provided both 5-6 year standard courses and 4 year accelerated graduate entry courses. The survey incorporated the Jefferson Scale of Empathy-Student Version (JSE-S) and Davis's Interpersonal Reactivity Index (IRI), both widely used to measure medical student empathy. Participation was voluntary. Chi squared tests were used to test for differences in biographical characteristics of student groups. Multiple linear regression analyses, in which predictor variables were year of course (first/final); sex; type of course and broad socio-economic group were used to compare empathy scores. RESULTS: Five medical schools (4 in the UK, 1 in New Zealand) achieved average response rates of 55 % (n = 652) among students starting their course and 48 % (n = 487) among final year students. These schools formed the High Response Rate Group. The remaining 12 medical schools recorded lower response rates of 24.0 % and 15.2 % among first and final year students respectively. These schools formed the Lower Response Rate Group. For both male and female students in both groups of schools no significant differences in any empathy scores were found between students starting and approaching the end of their course. Gender was found to significantly predict empathy scores, with females scoring higher than males. CONCLUSIONS: Participant male and female medical students approaching the end of their undergraduate education, did not record lower levels of empathy, compared to those at the beginning of their course. Questions remain concerning the trajectory of empathy after qualification and how best to support it through the pressures of starting out in medical practice

    TIC 168789840: A Sextuply-Eclipsing Sextuple Star System

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    We report the discovery of a sextuply-eclipsing sextuple star system from TESS data, TIC 168789840, also known as TYC 7037-89-1, the first known sextuple system consisting of three eclipsing binaries. The target was observed in Sectors 4 and 5 during Cycle 1, with lightcurves extracted from TESS Full Frame Image data. It was also previously observed by the WASP survey and ASAS-SN. The system consists of three gravitationally-bound eclipsing binaries in a hierarchical structure of an inner quadruple system with an outer binary subsystem. Follow-up observations from several different observatories were conducted as a means of determining additional parameters. The system was resolved by speckle interferometry with a 0."42 separation between the inner quadruple and outer binary, inferring an estimated outer period of ~2 kyr. It was determined that the fainter of the two resolved components is an 8.217 day eclipsing binary, which orbits the inner quadruple that contains two eclipsing binaries with periods of 1.570 days and 1.306 days. MCMC analysis of the stellar parameters has shown that the three binaries of TIC 168789840 are "triplets", as each binary is quite similar to the others in terms of mass, radius, and Teff. As a consequence of its rare composition, structure, and orientation, this object can provide important new insight into the formation, dynamics, and evolution of multiple star systems. Future observations could reveal if the intermediate and outer orbital planes are all aligned with the planes of the three inner eclipsing binaries

    Assessing the carcinogenic potential of low-dose exposures to chemical mixtures in the environment: the challenge ahead

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    Summary Low-dose exposures to common environmental chemicals that are deemed safe individually may be combining to instigate carcinogenesis, thereby contributing to the incidence of cancer. This risk may be overlooked by current regulatory practices and needs to be vigorously investigated

    Training future generations to deliver evidence-based conservation and ecosystem management

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    1. To be effective, the next generation of conservation practitioners and managers need to be critical thinkers with a deep understanding of how to make evidence-based decisions and of the value of evidence synthesis. 2. If, as educators, we do not make these priorities a core part of what we teach, we are failing to prepare our students to make an effective contribution to conservation practice. 3. To help overcome this problem we have created open access online teaching materials in multiple languages that are stored in Applied Ecology Resources. So far, 117 educators from 23 countries have acknowledged the importance of this and are already teaching or about to teach skills in appraising or using evidence in conservation decision-making. This includes 145 undergraduate, postgraduate or professional development courses. 4. We call for wider teaching of the tools and skills that facilitate evidence-based conservation and also suggest that providing online teaching materials in multiple languages could be beneficial for improving global understanding of other subject areas.Peer reviewe
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