426 research outputs found
Predicting Success in Equity Crowdfunding
Equity crowdfunding is an increasingly popular means of raising capital for early stage startups. It enables entrepreneurs to finance their companies with smaller contributions from a variety of people. This paper studies the relationship between the characteristics of a given company and its ability to raise funds on an equity crowdfunding platform. A series of statistical and machine learning models are fit to data from a U.S.-based equity crowdfunding website, including a logistic regression, a CART decision tree, a naïve Bayes classifier, and a support vector machine. This study demonstrates that a connection exists between the probability of a company’s crowdfunding success and its previous funding history, Twitter presence, media buzz, size, location, and its founders’ educational backgrounds. As a whole, however, the classification quality of the various models leaves something to be desired. This suggests the need for additional data inputs and more longitudinal research in the field of equity crowdfunding
The Influence of Magnetic Field Geometry on the Evolution of Black Hole Accretion Flows: Similar Disks, Drastically Different Jets
Because the magneto-rotational instability is capable of exponentially
amplifying weak preexisting magnetic fields, it might be hoped that the
character of the magnetic field in accretion disks is independent of the nature
of the seed field. However, the divergence-free nature of magnetic fields in
highly conducting fluids ensures that their large-scale topology is preserved,
no matter how greatly the field intensity is changed. By performing global
two-dimensional and three-dimensional general relativistic magnetohydrodynamic
disk simulations with several different topologies for the initial magnetic
field, we explore the degree to which the character of the flows around black
holes depends on the initial topology. We find that while the qualitative
properties of the accretion flow are nearly independent of field topology,
jet-launching is very sensitive to it: a sense of vertical field consistent for
at least an inner disk inflow time is essential to the support of strong jets.Comment: 42 pages; 17 figures; Accepted for publication in ApJ (some new
discussion and 2 new figures
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