100 research outputs found
The evolving scholarly record
This report presents a framework to help organize and drive discussions about the evolving scholarly record. The framework provides a high-level view of the categories of material the scholarly record potentially encompasses, as well as the key stakeholder roles associated with the creation, management, and use of the scholarly record.
Key highlights:
A confluence of trends is accelerating changes to the scholarly record\u27s content and stakeholder roles.
Scholarly outcomes are contextualized by materials generated in the process and aftermath of scholarly inquiry.
The research process generates materials covering methods employed, evidence used, and formative discussion.
The research aftermath generates materials covering discussion, revision, and reuse of scholarly outcomes.
The scholarly record is evolving to have greater emphasis on collecting and curating context of scholarly inquiry.
The scholarly record’s stakeholder ecosystem encompasses four key roles: create, fix, collect, and use.
The stakeholder ecosystem supports thinking about how roles are reconfigured as the scholarly record evolves.
The ways and means of scholarly inquiry are experiencing fundamental change, with consequences for scholarly communication and ultimately, the scholarly record. The boundaries of the scholarly record are both expanding and blurring, driven by changes in research practices, as well as changing perceptions of the long-term value of certain forms of scholarly materials. Understanding the nature, scope, and evolutionary trends of the scholarly record is an important concern in many quarters—for libraries, for publishers, for funders, and of course for scholars themselves. Many issues are intrinsic to the scholarly record, such as preservation, citation, replicability, provenance, and data curation.
The conceptualization of the scholarly record and its stakeholder ecosystem provided in the report can serve as a common point of reference in discussions within and across domains, and help cultivate the shared understanding and collaborative relationships needed to identify, collect, and make accessible the wide range of materials the scholarly record is evolving to include
Continuous breakdown of Purcell's scallop theorem with inertia
Purcell's scallop theorem defines the type of motions of a solid body -
reciprocal motions - which cannot propel the body in a viscous fluid with zero
Reynolds number. For example, the flapping of a wing is reciprocal and, as was
recently shown, can lead to directed motion only if its frequency Reynolds
number, Re_f, is above a critical value of order one. Using elementary
examples, we show the existence of oscillatory reciprocal motions which are
effective for all arbitrarily small values of the frequency Reynolds number and
induce net velocities scaling as (Re_f)^\alpha (alpha > 0). This demonstrates a
continuous breakdown of the scallop theorem with inertia.Comment: 6 pages, 1 figur
FAST (Faceted Application of Subject Terminology) Users: Summary and Case Studies
FAST (Faceted Application of Subject Terminology) Users: Summary and Case Studies, written by Research Assistant Jeff Mixter and Consulting Project Manager Eric Childress, includes case studies of sixteen parties (nine adopters, seven non-adopters) in six countries that have expressed interest in FAST, as well as a profile of OCLC's own use of FAST.FAST is an enumerative faceted subject heading schema derived from Library of Congress Subject Headings (LCSH). Development was initiated in 1998 by OCLC Research with the Library of Congress to work together on a research project aimed at developing a faceted controlled vocabulary based on LCSH. Over the period of the project, FAST has been built out into an eight-facet vocabulary with a universe of approximately 1.7 million headings across all facets and has been made available as Linked Open Data and integrated into a number of metadata workflows and discovery systems.Community interest in knowing who is using FAST and how FAST is being used has also grown. To address this interest, OCLC Research conducted a census of FAST users in late 2012 and early 2013 to examine:How FAST is being utilizedWhy those using FAST selected it as their cataloging vocabularyWhat benefits FAST providesWhat can be done to enhance the value of FASTThe interviews in summary form and an analysis of the information gathered from the interviews are published in the report.Key findings:Most cited FAST attributes: ease of use, simple syntax, and suitability for non-cataloger applicationTop three FAST facets used (of eight facets total): Topic, Geographic Names, Form/GenrePublishing FAST as linked data under an open license has favorably advanced its adoptio
Encoding Application Profiles in a Computational Model of the Crosswalk
OCLC’s Crosswalk Web Service (Godby, Smith and Childress, 2008) formalizes the notion of crosswalk, as defined in Gill,et al. (n.d.), by hiding technical details and permitting the Semantic equivalences to emerge as the centerpiece. One outcome is that metadata experts, who are typically not programmers, can enter the translation logic into a spreadsheet that can be automatically converted into executable code. In this paper, we describe the implementation of the Dublin Core Terms application profile in the management of crosswalks involving MARC. A crosswalk that encodes an application profile extends the typical format with two columns: one that annotates the namespace to which an element belongs, and one that annotates a ‘broadernarrower’ relation between a pair of elements, such as Dublin Core coverage and Dublin Core Terms spatial. This information is sufficient to produce scripts written in OCLC’s Semantic Equivalence Expression Language (or Seel), which are called from the Crosswalk Web Service to generate production-grade translations. With its focus on elements that can be mixed, matched, added, and redefined, the application profile (Heery and Patel, 2000) is a natural fit with the translation model of the Crosswalk Web Service, which attempts to achieve interoperability by mapping one pair of elements at a time
Stokesian jellyfish: Viscous locomotion of bilayer vesicles
Motivated by recent advances in vesicle engineering, we consider
theoretically the locomotion of shape-changing bilayer vesicles at low Reynolds
number. By modulating their volume and membrane composition, the vesicles can
be made to change shape quasi-statically in thermal equilibrium. When the
control parameters are tuned appropriately to yield periodic shape changes
which are not time-reversible, the result is a net swimming motion over one
cycle of shape deformation. For two classical vesicle models (spontaneous
curvature and bilayer coupling), we determine numerically the sequence of
vesicle shapes through an enthalpy minimization, as well as the fluid-body
interactions by solving a boundary integral formulation of the Stokes
equations. For both models, net locomotion can be obtained either by
continuously modulating fore-aft asymmetric vesicle shapes, or by crossing a
continuous shape-transition region and alternating between fore-aft asymmetric
and fore-aft symmetric shapes. The obtained hydrodynamic efficiencies are
similar to that of other low Reynolds number biological swimmers, and suggest
that shape-changing vesicles might provide an alternative to flagella-based
synthetic microswimmers
Swimming in circles: Motion of bacteria near solid boundaries
Near a solid boundary, E. coli swims in clockwise circular motion. We provide
a hydrodynamic model for this behavior. We show that circular trajectories are
natural consequences of force-free and torque-free swimming, and the
hydrodynamic interactions with the boundary, which also leads to a hydrodynamic
trapping of the cells close to the surface. We compare the results of the model
with experimental data and obtain reasonable agreement. In particular, we show
that the radius of curvature of the trajectory increases with the length of the
bacterium body.Comment: Also available at http://people.deas.harvard.edu/~lauga
The long-time dynamics of two hydrodynamically-coupled swimming cells
Swimming micro-organisms such as bacteria or spermatozoa are typically found
in dense suspensions, and exhibit collective modes of locomotion qualitatively
different from that displayed by isolated cells. In the dilute limit where
fluid-mediated interactions can be treated rigorously, the long-time
hydrodynamics of a collection of cells result from interactions with many other
cells, and as such typically eludes an analytical approach. Here we consider
the only case where such problem can be treated rigorously analytically, namely
when the cells have spatially confined trajectories, such as the spermatozoa of
some marine invertebrates. We consider two spherical cells swimming, when
isolated, with arbitrary circular trajectories, and derive the long-time
kinematics of their relative locomotion. We show that in the dilute limit where
the cells are much further away than their size, and the size of their circular
motion, a separation of time scale occurs between a fast (intrinsic) swimming
time, and a slow time where hydrodynamic interactions lead to change in the
relative position and orientation of the swimmers. We perform a multiple-scale
analysis and derive the effective dynamical system - of dimension two -
describing the long-time behavior of the pair of cells. We show that the system
displays one type of equilibrium, and two types of rotational equilibrium, all
of which are found to be unstable. A detailed mathematical analysis of the
dynamical systems further allows us to show that only two cell-cell behaviors
are possible in the limit of , either the cells are attracted to
each other (possibly monotonically), or they are repelled (possibly
monotonically as well), which we confirm with numerical computations
The Long-Baseline Neutrino Experiment: Exploring Fundamental Symmetries of the Universe
The preponderance of matter over antimatter in the early Universe, the
dynamics of the supernova bursts that produced the heavy elements necessary for
life and whether protons eventually decay --- these mysteries at the forefront
of particle physics and astrophysics are key to understanding the early
evolution of our Universe, its current state and its eventual fate. The
Long-Baseline Neutrino Experiment (LBNE) represents an extensively developed
plan for a world-class experiment dedicated to addressing these questions. LBNE
is conceived around three central components: (1) a new, high-intensity
neutrino source generated from a megawatt-class proton accelerator at Fermi
National Accelerator Laboratory, (2) a near neutrino detector just downstream
of the source, and (3) a massive liquid argon time-projection chamber deployed
as a far detector deep underground at the Sanford Underground Research
Facility. This facility, located at the site of the former Homestake Mine in
Lead, South Dakota, is approximately 1,300 km from the neutrino source at
Fermilab -- a distance (baseline) that delivers optimal sensitivity to neutrino
charge-parity symmetry violation and mass ordering effects. This ambitious yet
cost-effective design incorporates scalability and flexibility and can
accommodate a variety of upgrades and contributions. With its exceptional
combination of experimental configuration, technical capabilities, and
potential for transformative discoveries, LBNE promises to be a vital facility
for the field of particle physics worldwide, providing physicists from around
the globe with opportunities to collaborate in a twenty to thirty year program
of exciting science. In this document we provide a comprehensive overview of
LBNE's scientific objectives, its place in the landscape of neutrino physics
worldwide, the technologies it will incorporate and the capabilities it will
possess.Comment: Major update of previous version. This is the reference document for
LBNE science program and current status. Chapters 1, 3, and 9 provide a
comprehensive overview of LBNE's scientific objectives, its place in the
landscape of neutrino physics worldwide, the technologies it will incorporate
and the capabilities it will possess. 288 pages, 116 figure
SN 2012fr: Ultraviolet, Optical, and Near-infrared Light Curves of a Type Ia Supernova Observed within a Day of Explosion
We present detailed ultraviolet, optical, and near-infrared light curves of the Type Ia supernova (SN) 2012fr, which exploded in the Fornax cluster member NGC 1365. These precise high-cadence light curves provide a dense coverage of the flux evolution from −12 to +140 days with respect to the epoch of B-band maximum (tBmax). Supplementary imaging at the earliest epochs reveals an initial slow and nearly linear rise in luminosity with a duration of ∼2.5 days, followed by a faster rising phase that is well reproduced by an explosion model with a moderate amount of 56Ni mixing in the ejecta. From our analysis of the light curves, we conclude that: (i) the explosion occurred 1800 Å) luminosity was 16.5 ± 0.6 days, (iii) the supernova suffered little or no host-galaxy dust reddening, (iv) the peak luminosity in both the optical and near-infrared was consistent with the bright end of normal Type Ia diversity, and (v) 0.60 ± 0.15 M⊙ of 56Ni was synthesized in the explosion. Despite its normal luminosity, SN 2012fr displayed unusually prevalent high-velocity Ca II and Si II absorption features, and a nearly constant photospheric velocity of the Si II λ6355 line at ∼12,000 km s-1 that began ∼5 days before tBmax. We also highlight some of the other peculiarities in the early phase photometry and the spectral evolution. SN 2012fr also adds to a growing number of Type Ia supernovae that are hosted by galaxies with direct Cepheid distance measurements.Facultad de Ciencias Astronómicas y GeofísicasInstituto de Astrofísica de La Plat
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