1,571 research outputs found
Self-Energy Correction to the Bound-Electron g Factor of P States
The radiative self-energy correction to the bound-electron g factor of 2P_1/2
and 2P_3/2 states in one-electron ions is evaluated to order alpha (Z alpha)^2.
The contribution of high-energy virtual photons is treated by means of an
effective Dirac equation, and the result is verified by an approach based on
long-wavelength quantum electrodynamics. The contribution of low-energy virtual
photons is calculated both in the velocity and in the length gauge and gauge
invariance is verified explicitly. The results compare favorably to recently
available numerical data for hydrogenlike systems with low nuclear charge
numbers.Comment: 8 pages, RevTe
Instructional Leadership, Teaching Quality, and Student Achievement: Suggestive Evidence from Three Urban School Districts
Does providing instruction-related professional development to school principals set in motion a chain of events that can improve teaching and learning in their schools? This report examines professional development efforts by the University of Pittsburgh's Institute for Learning in elementary schools in Austin, St. Paul, and New York City
Observation of Spin Flips with a Single Trapped Proton
Radio-frequency induced spin transitions of one individual proton are
observed for the first time. The spin quantum jumps are detected via the
continuous Stern-Gerlach effect, which is used in an experiment with a single
proton stored in a cryogenic Penning trap. This is an important milestone
towards a direct high-precision measurement of the magnetic moment of the
proton and a new test of the matter-antimatter symmetry in the baryon sector
3D tomography of cells in micro-channels
We combine confocal imaging, microfluidics and image analysis to record
3D-images of cells in flow. This enables us to recover the full 3D
representation of several hundred living cells per minute. Whereas 3D confocal
imaging has thus far been limited to steady specimen, we overcome this
restriction and present a method to access the 3D shape of moving objects. The
key of our principle is a tilted arrangement of the micro-channel with respect
to the focal plane of the microscope. This forces cells to traverse the focal
plane in an inclined manner. As a consequence, individual layers of passing
cells are recorded which can then be assembled to obtain the volumetric
representation. The full 3D information allows for a detailed comparisons with
theoretical and numerical predictions unfeasible with e.g.\ 2D imaging. Our
technique is exemplified by studying flowing red blood cells in a micro-channel
reflecting the conditions prevailing in the microvasculature. We observe two
very different types of shapes: `croissants' and `slippers'. Additionally, we
perform 3D numerical simulations of our experiment to confirm the observations.
Since 3D confocal imaging of cells in flow has not yet been realized, we see
high potential in the field of flow cytometry where cell classification thus
far mostly relies on 1D scattering and fluorescence signals
Resolution of Single Spin-Flips of a Single Proton
The spin magnetic moment of a single proton in a cryogenic Penning trap was
coupled to the particle's axial motion with a superimposed magnetic bottle.
Jumps in the oscillation frequency indicate spin-flips and were identified
using a Bayesian analysis.Comment: accepted for publication by Phys. Rev. Lett., submitted 6.June.201
SAMplus: adaptive optics at optical wavelengths for SOAR
Adaptive Optics (AO) is an innovative technique that substantially improves
the optical performance of ground-based telescopes. The SOAR Adaptive Module
(SAM) is a laser-assisted AO instrument, designed to compensate ground-layer
atmospheric turbulence in near-IR and visible wavelengths over a large Field of
View. Here we detail our proposal to upgrade SAM, dubbed SAMplus, that is
focused on enhancing its performance in visible wavelengths and increasing the
instrument reliability. As an illustration, for a seeing of 0.62 arcsec at 500
nm and a typical turbulence profile, current SAM improves the PSF FWHM to 0.40
arcsec, and with the upgrade we expect to deliver images with a FWHM of
arcsec -- up to 0.23 arcsec FWHM PSF under good seeing
conditions. Such capabilities will be fully integrated with the latest SAM
instruments, putting SOAR in an unique position as observatory facility.Comment: To appear in Proc. SPIE 10703 (Ground-based and Airborne
Instrumentation for Astronomy VII; SPIEastro18
Artificial neural networks for 3D cell shape recognition from confocal images
We present a dual-stage neural network architecture for analyzing fine shape
details from microscopy recordings in 3D. The system, tested on red blood
cells, uses training data from both healthy donors and patients with a
congenital blood disease. Characteristic shape features are revealed from the
spherical harmonics spectrum of each cell and are automatically processed to
create a reproducible and unbiased shape recognition and classification for
diagnostic and theragnostic use.Comment: 17 pages, 8 figure
Designing Sustainable Urban Futures : Concepts and Practices from Different Countries
Many 21st century cities have the potential to be sustainable and resource-saving living spaces when multifunctional structures, well-integrated transportation infrastructure, and democratic governance processes are present. Sustainable urban futures require a focus on the needs of humans and environmental best practices, as well as on the creative scope for community-driven sustainability innovations. This book is based on contributions from science and practice to the international symposium on “Sustainable Urban Development at Different Scales” organized by the Institute for Technology Assessment and Systems Analysis at the Karlsruhe Institute of Technology, Karlsruhe, Germany, in May 2014. The symposium used the global urbanization and reurbanization trend as an opportunity to examine cities as sustainable living spaces. This book identifi es concepts, analytic approaches, and practical applications for the design of sustainable urban futures among multiple disciplines and cultural backgrounds
Demonstration of the Double Penning Trap Technique with a Single Proton
Spin flips of a single proton were driven in a Penning trap with a
homogeneous magnetic field. For the spin-state analysis the proton was
transported into a second Penning trap with a superimposed magnetic bottle, and
the continuous Stern-Gerlach effect was applied. This first demonstration of
the double Penning trap technique with a single proton suggests that the
antiproton magnetic moment measurement can potentially be improved by three
orders of magnitude or more
Designing Sustainable Urban Futures : Concepts and Practices from Different Countries
This book is based on contributions from science and practice to the international symposium on “Sustainable Urban Development at Different Scales”. The symposium used the global urbanization and reurbanization trend as an opportunity to examine cities as sustainable living spaces. This book identifies concepts, analytic approaches, and practical applications for the design of sustainable urban futures among multiple disciplines and cultural backgrounds
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