2,638 research outputs found
Ideabook: Libraries for Families
The IDEABOOK is a research-based framework to guide and broaden family engagement in libraries.The framework helps libraries move beyond thinking of family engagement as random, individual activities or programs, but rather as a system where library leadership, activities, and resources that are linked to goals. The framework represents a theory of change that begins with a set of elements—leadership, engagement, and support services—that build a pathway for meaningful family engagement beginning in the early childhood years and extending through young adulthood.This IDEABOOK was developed for anyone who works in a library setting—from library directors and children's and youth librarians, to volunteers and support staff—and shares many innovative ways that libraries support and guide families in children's learning and development
GiRaFFE: An Open-Source General Relativistic Force-Free Electrodynamics Code
We present GiRaFFE, the first open-source general relativistic force-free
electrodynamics (GRFFE) code for dynamical, numerical-relativity generated
spacetimes. GiRaFFE adopts the strategy pioneered by McKinney and modified by
Paschalidis and Shapiro to convert a GR magnetohydrodynamic (GRMHD) code into a
GRFFE code. In short, GiRaFFE exists as a modification of IllinoisGRMHD, a
user-friendly, open-source, dynamical-spacetime GRMHD code. Both GiRaFFE and
IllinoisGRMHD leverage the Einstein Toolkit's highly-scalable infrastructure to
make possible large-scale simulations of magnetized plasmas in strong,
dynamical spacetimes on adaptive-mesh refinement (AMR) grids. We demonstrate
that GiRaFFE passes a large suite of both flat and curved-spacetime code tests
passed by a number of other state-of-the-art GRFFE codes, and is thus ready for
production-scale simulations of GRFFE phenomena of key interest to relativistic
astrophysics.Comment: 23 pages, 4 figures. Consistent with published versio
A systematic correlation between two-dimensional flow topology and the abstract statistics of turbulence
Velocity differences in the direct enstrophy cascade of two-dimensional
turbulence are correlated with the underlying flow topology. The statistics of
the transverse and longitudinal velocity differences are found to be governed
by different structures. The wings of the transverse distribution are dominated
by strong vortex centers, whereas, the tails of the longitudinal differences
are dominated by saddles. Viewed in the framework of earlier theoretical work
this result suggests that the transfer of enstrophy to smaller scales is
accomplished in regions of the flow dominated by saddles.Comment: 4 pages, 4 figure
Random Projections For Large-Scale Regression
Fitting linear regression models can be computationally very expensive in
large-scale data analysis tasks if the sample size and the number of variables
are very large. Random projections are extensively used as a dimension
reduction tool in machine learning and statistics. We discuss the applications
of random projections in linear regression problems, developed to decrease
computational costs, and give an overview of the theoretical guarantees of the
generalization error. It can be shown that the combination of random
projections with least squares regression leads to similar recovery as ridge
regression and principal component regression. We also discuss possible
improvements when averaging over multiple random projections, an approach that
lends itself easily to parallel implementation.Comment: 13 pages, 3 Figure
Evolving American Investing Attitudes: The Hybrid Shift In Mutual Fund Distribution
This paper studies the dramatic evolution in the way American investors choose to invest in the mutual fund industry. The industry’s change from direct-to-shareholder model to a third-party distribution model is discussed, as well as the implications for future mutual fund investors. Ever since the first recorded asset and debt managers arose in the 14th and 15th centuries in Europe, investing has grown into a tug-and-pull type of system that the human mind seems drawn to. The way that Americans choose to invest their money is changing as we enter the 21st century and the new methods and procedures are having a greater impact than many of us realize. In the U.S., trillions of dollars each year are invested in mutual funds, but more and more investors are taking a less-involved route by allowing financial analysts to choose where their money is invested. In the following pages, we will take a closer look at the mutual fund market and its basic components, the ways that mutual funds have been viewed and traded in the past, and the revolutionary changes that are happening right under our noses that the average American may not even be aware of. With the help of many credible sources, such as the Investment Company Institute, Reflow Investments LLC, and the Financial Planning Journal, the change from direct-to-shareholder mutual fund distribution to third-party intermediary distribution will be explained and the effects these changes has on the average investor will be explored
Forced Stratified Turbulence: Successive Transitions with Reynolds Number
Numerical simulations are made for forced turbulence at a sequence of
increasing values of Reynolds number, R, keeping fixed a strongly stable,
volume-mean density stratification. At smaller values of R, the turbulent
velocity is mainly horizontal, and the momentum balance is approximately
cyclostrophic and hydrostatic. This is a regime dominated by so-called pancake
vortices, with only a weak excitation of internal gravity waves and large
values of the local Richardson number, Ri, everywhere. At higher values of R
there are successive transitions to (a) overturning motions with local
reversals in the density stratification and small or negative values of Ri; (b)
growth of a horizontally uniform vertical shear flow component; and (c) growth
of a large-scale vertical flow component. Throughout these transitions, pancake
vortices continue to dominate the large-scale part of the turbulence, and the
gravity wave component remains weak except at small scales.Comment: 8 pages, 5 figures (submitted to Phys. Rev. E
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