2,793 research outputs found
Digitization of Museum Collections: Using Technology, Creating Access, and Releasing Authority in Managing Content and Resources
Through the use of new technologies and platforms, the Minnesota HistoricalSociety (MNHS) has been able to reach new levels of transparency in working with Dakota communities on the access, management and care of Dakota material culture collections. By digitizing and sharing information about collections and using an online platform for soliciting feedback - which then becomes attached to the permanent record of the object – the MNHS is relinquishing the authority of intellectual control over Dakota material culture which they have historically claimed to have. In doing so, the institution is not only opening pathways to meaningful dialogue, but is benefiting by gaining new insights and knowledge shared with them by cultural insiders.
By expanding upon this shared authority, the MNHS is also being educated inregards to the traditional modes of care for items within their Dakota material culture collections. Over the course of the last few years, through outreach efforts, many Dakota people have also learned about museum best practices in physical preservation. In the past, this type of dialogue has not existed or has been extremely strained. Through sharing information and partnering, personal and professional relationships are guiding emerging professional practices.By promoting online resources that can be accessed via the internet fromanywhere, the MNHS has recently begun fostering meaningful dialogue and partnerships. These resources include the Dakota material culture collections, and to a lesser extent, the photograph collections and genealogical records. In sharing these resources, the MNHS has not only promoted access, but has fostered reciprocal sharing of knowledge, in turn creating a more robust and complete understanding. In familiarizing new audiences with digital surrogates, MNHS has promoted the sharing of information, as well as the decentralization of authority. By completing this work in partnership with Dakota communities – often within their own communities – the MNHS is also reaching underserved audiences
Long-Term Technology Assessment: Mortality, Hospitalization, and Work Loss Due to Peptic Ulcer and Gastritis/Duodenitis in the Federal Republic of Germany
Once the effects of short-term data analysis of new medical technology appear clear, additional or long-term analyses are infrequently performed on subsequent information. This often leads to incomplete understanding of the technology's full medical, social, and economic effects. Available data for the Federal Republic of Germany on mortality, hospitalization, and work loss due to gastric and duodenal ulcer and gastritis/duodenitis allowed long-term analysis of direct and indirect impacts on the population from 1975 through 1984. Mortality rates declined for all ages (ρ ≤ 0.01) except for those age 75 and older, and nearly equally for all study diagnoses. Hospital discharge rates for all diagnoses rose slowly and steadily, while those for persons diagnosed with gastric ulcer, duodenal ulcer or gastritis/duodenitis declined sharply (ρ = 0.04). Declines of hospital discharges were greater for men than for women. The ongoing decline in rates of mortality and hospital discharges increased after 1977. Rates of work loss per 10,000 population-at-risk for study diagnoses were either stable or increasing until 1979, after which there was a marked decline (ρ = 0.03 for gastric ulcer, ρ = 0.02 for duodenal ulcer, ρ = 0.008 for gastritis/duodenitis). Work loss due to study diseases declined as a percentage of work loss for all diseases during the later study years. Only by examining many years' data could the accelerating declines be discerned, not only for mortality and hospitalizations, which have been examined before, but also for work loss, an infrequently analyzed effect of diseas
Commissioning of the electron injector for the AWAKE experiment
The advanced wakefield experiment (AWAKE) at CERN is the first proton beam-driven plasma wakefield acceleration experiment. The main goal of AWAKE RUN 1 was to demonstrate seeded self-modulation (SSM) of the proton beam and electron witness beam acceleration in the plasma wakefield. For the AWAKE experiment, a 10-meter-long Rubidium-vapor cell together with a high-power laser for ionization was used to generate the plasma. The plasma wakefield is driven by a 400 GeV/c proton beam extracted from the super proton synchrotron (SPS), which undergoes a seeded self-modulation process in the plasma. The electron witness beam used to probe the wakefields is generated from an S-band RF photo-cathode gun and then accelerated by a booster structure up to energies between 16 and 20 MeV. The first run of the AWAKE experiment revealed that the maximum energy gain after the plasma cell is 2 GeV, and the SSM mechanism of the proton beam was verified. In this paper, we will present the details of the AWAKE electron injector. A comparison of the measured electron beam parameters, such as beam size, energy, and normalized emittance, with the simulation results was performed
Positron Acceleration in Plasma Wakefields
Plasma acceleration has emerged as a promising technology for future particle
accelerators, particularly linear colliders. Significant progress has been made
in recent decades toward high-efficiency and high-quality acceleration of
electrons in plasmas. However, this progress does not generalize to
acceleration of positrons, as plasmas are inherently charge asymmetric. Here,
we present a comprehensive review of historical and current efforts to
accelerate positrons using plasma wakefields. Proposed schemes that aim to
increase the energy efficiency and beam quality are summarised and
quantitatively compared. A dimensionless metric that scales with the
luminosity-per-beam power is introduced, indicating that positron-acceleration
schemes are currently below the ultimate requirement for colliders. The primary
issue is electron motion; the high mobility of plasma electrons compared to
plasma ions, which leads to non-uniform accelerating and focusing fields that
degrade the beam quality of the positron bunch, particularly for high
efficiency acceleration. Finally, we discuss possible mitigation strategies and
directions for future research.Comment: 24 pages (30 pages with references), 22 figure
Nonlinear Spectroscopy of Controllable Many-Body Quantum Systems
We establish a novel approach to probing spatially resolved multi-time
correlation functions of interacting many-body systems, with scalable
experimental overhead. Specifically, designing nonlinear measurement protocols
for multidimensional spectra in a chain of trapped ions with single-site
addressability enables us, e.g., to distinguish coherent from incoherent
transport processes, to quantify potential anharmonicities, and to identify
decoherence-free subspaces.Comment: 12 pages, 3 figure
Measuring geometric phases with a dynamical quantum Zeno effect in a Bose-Einstein condensate
A closed-trajectory evolution of a quantum state generally imprints a phase
that contains both dynamical and geometrical contributions. While dynamical
phases depend on the reference system, geometric phase factors are uniquely
defined by the properties of the outlined trajectory. Here, we generate and
measure geometric phases in a Bose-Einstein condensate of Rb using a
combination of dynamical quantum Zeno effect and measurement-free evolution. We
show that the dynamical quantum Zeno effect can inhibit the formation of a
geometric phase without altering the dynamical phase. This can be used to
extract the geometric Aharonov-Anandan phase from any closed-trajectory
evolution without requiring knowledge or control of the Hamiltonian.Comment: 4+3 pages, 4+3 figure
Three-dimensional Models of Core-collapse Supernovae From Low-mass Progenitors With Implications for Crab
We present 3D full-sphere supernova simulations of non-rotating low-mass (~9
Msun) progenitors, covering the entire evolution from core collapse through
bounce and shock revival, through shock breakout from the stellar surface,
until fallback is completed several days later. We obtain low-energy explosions
[~(0.5-1.0)x 10^{50} erg] of iron-core progenitors at the low-mass end of the
core-collapse supernova (LMCCSN) domain and compare to a super-AGB (sAGB)
progenitor with an oxygen-neon-magnesium core that collapses and explodes as
electron-capture supernova (ECSN). The onset of the explosion in the LMCCSN
models is modelled self-consistently using the Vertex-Prometheus code, whereas
the ECSN explosion is modelled using parametric neutrino transport in the
Prometheus-HOTB code, choosing different explosion energies in the range of
previous self-consistent models. The sAGB and LMCCSN progenitors that share
structural similarities have almost spherical explosions with little metal
mixing into the hydrogen envelope. A LMCCSN with less 2nd dredge-up results in
a highly asymmetric explosion. It shows efficient mixing and dramatic shock
deceleration in the extended hydrogen envelope. Both properties allow fast
nickel plumes to catch up with the shock, leading to extreme shock deformation
and aspherical shock breakout. Fallback masses of <~5x10^{-3} Msun have no
significant effects on the neutron star (NS) masses and kicks. The anisotropic
fallback carries considerable angular momentum, however, and determines the
spin of the newly-born NS. The LMCCSNe model with less 2nd dredge-up results in
a hydrodynamic and neutrino-induced NS kick of >40 km/s and a NS spin period of
~30 ms, both not largely different from those of the Crab pulsar at birth.Comment: 47 pages, 27 figures, 6 tables; minor revisions, accepted by MNRA
Local Detection of Quantum Correlations with a Single Trapped Ion
As one of the most striking features of quantum mechanics, quantum
correlations are at the heart of quantum information science. Detection of
correlations usually requires access to all the correlated subsystems. However,
in many realistic scenarios this is not feasible since only some of the
subsystems can be controlled and measured. Such cases can be treated as open
quantum systems interacting with an inaccessible environment. Initial
system-environment correlations play a fundamental role for the dynamics of
open quantum systems. Following a recent proposal, we exploit the impact of the
correlations on the open-system dynamics to detect system-environment quantum
correlations without accessing the environment. We use two degrees of freedom
of a trapped ion to model an open system and its environment. The present
method does not require any assumptions about the environment, the interaction
or the initial state and therefore provides a versatile tool for the study of
quantum systems.Comment: 6 Pages, 5 Figures + 6 Pages, 1 Figure of Supplementary Materia
- …