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With Big Data Comes Big Responsibilities for Science Equity Research
Get PDFOur ability to collect and access large quantities of data over the last decade has been revolutionary for many social sciences. Suddenly, it is possible to measure human behavior, performance, and activity on an unprecedented scale, opening the door to fundamental advances in discovery and understanding. Yet such access to data has limitations that, if not sufficiently addressed and explored, can result in significant over-sights. Here we discuss recent research that used data from a large global sample of high school students to demonstrate, paradoxically, that in nations with higher gender equality, fewer women pursued science, technology, engineering, and mathematics (STEM) degrees than would be expected based on aptitude in those subjects. The reasons for observed patterns is central to current debates, with frequent disagreement about the nature and magnitude of problems posed by the lack of female representation in STEM and the best ways to deal with them. In our international efforts to use big data in education research, it is necessary to critically consider its limitations and biases.Publishe
Entrepreneurship for the People: Government Resources for researching, starting, and growing your business
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Severe Long-Lasting Drought Accelerated Carbon Depletion in the Mongolian Plateau
Get PDFPaleoclimate records identified a severe drought lasting approximately a decade on the Mongolian Plateau during the 2000s, the severity of which was only exceeded by a single drought during the last two millennia. Under high-emission scenarios, arid and semiarid areas are projected to continue to experience a drying trend over the coming decades; therefore, understanding how ecosystems respond to long-lasting drought has global implications. Here we used a process-based ecosystem model to examine the interannual and intra-annual variations in net ecosystem productivity in response to climate extremes across the Mongolian Plateau. We find that the recent-decade drought caused Mongolian terrestrial ecosystems to shift from a carbon (C) sink to a C source, canceling 40% of climate-induced C accumulation over the entire twentieth century. Our study details a shortened C sequestering season, increased summer C source, and accelerated C depletion during the 2000s drought. Plain Language Summary Multiple lines of evidence have shown detrimental effects of drought events on ecosystem production and carbon dynamics, but it remains uncertain how arid and semiarid ecosystems respond to long-lasting drought. Here we reveal that a severe drought during the first decade of the 2000s on the Mongolian Plateau considerably weakened C sequestration capacity and accelerated C depletion. This work has broad implications for understanding impacts of persistent droughts on terrestrial C dynamics as a drying trend, in many arid and semiarid areas, is projected to continue over the coming decades.PublishedYe
A Resisting Reader's Guide to George Eliot's Heroines
No full textArticle from the George Eliot Review, digitized and hosted by the George Eliot Review Online.Publishe
Double Rydberg anions with solvated ammonium kernels: Electron binding energies and Dyson orbitals
Get PDFAb initio electron-propagator calculations on the electron detachment energies and associated Dyson orbitals of NnH3n+1- for n = 1-5 confirm the assignment of low-energy peaks in anion photoelectron spectra to double Rydberg anions, species in which a closed-shell cation binds a diffuse pair of electrons. The most stable double Rydberg anions contain NnH3n+1+ cores, wherein the NH4+ kernel forms n - 1 hydrogen bonds with ammonia molecules. Other low-energy peaks for a given n pertain to double Rydberg anions of lower n that are weakly bound to ammonia molecules. High-energy peaks arise from the most stable isomers which consist of hydrides bound to N-H bonds of coordinating ammonia molecules. Dyson orbitals of electron detachment are distributed over the periphery of the bonding regions of the NnH3n+1+ cores. For n = 2-4, negative charge accumulates mostly outside the N-H bonds of the NH4+ kernels that are not engaged in hydrogen bonds. For the tetrahedral cases, where n = 1, 5, Dyson orbitals are diffuse, symmetric functions that are orthogonalized to occupied a(1) orbitals of the cationic core. Shake-up features in spectra have been assigned to doublet states with a single diffuse electron in an s, p, d, or f orbital
Cluster perturbation theory. I. Theoretical foundation for a coupled cluster target state and ground-state energies
Get PDFWe introduce a new class of perturbation models-the cluster perturbation (CP) models-where the major drawbacks of Moller-Plesset perturbation theory and coupled cluster perturbation theory have been eliminated. In CP theory, we consider a target excitation space relative to the Hartree-Fock state and partition the target excitation space into a parent and an auxiliary excitation space. The zeroth-order state is a coupled cluster (CC) state in the parent excitation space, and the target state is either a cluster linear or a CC state in the target excitation space. In CP theory, perturbation series are determined in orders of the CC parent state similarity-transformed fluctuation potential for the energy and for a molecular property, where the zeroth-order term in the series is the energy or a molecular property for the CC parent state and where the series formally converge to the energy or a molecular property for the target state. In CP theory, we use a generalized order concept, where the zeroth-order component of the extended parent-state Jacobian contains a fluctuation potential contribution, and use this new generalized order to treat internal relaxation in the parent excitation space at zeroth order and hence remove it from the perturbation calculation. Even more importantly, using this new generalized order concept, CP series can be determined for molecular properties of ground and excited states and for transition properties between these states, including excitation energies and energies of the excited states. The applicability of CP theory to both the energy and molecular properties and numerical results for the CP energy and molecular property series demonstrate the superiority of CP theory compared to previous perturbation models. Low-order corrections in the CP perturbation series can be expected soon to become state-of-the-art electronic structure models for the determination of energies and molecular properties of target-state quality for single-configuration dominated molecular systems. Published under license by AIP Publishing.Publishe
Lizard embryos prioritize post-hatching energy reserves over increased hatchling body size during development
No full textEmbryonic development in oviparous organisms is fueled by maternally-allocated yolk, with many organisms hatching before that energy store is completely used up; the resultant leftover (residual) yolk is internalized and may support early post-hatching life. We experimentally reduced yolk quantity at oviposition in lizard eggs (Amphibolurus muricatus) to determine if embryos (1) exhaust yolk supply during development (thereby maximizing neonatal size) or (2) reduce neonatal size by retaining yolk reserves at hatching. Our data support the latter scenario. Eggs from the yolk-reduced treatment produced smaller offspring with a similar proportion of residual yolk compared to offspring from unmanipulated eggs, suggesting that the fitness benefits of post-hatching energy stores outweigh those of larger neonatal size.SubmittedYe