9,213 research outputs found
Octave-tunable miniature RF resonators
The development and testing of a miniaturized, high-Q, broadly tunable resonator is described. An exemplary device, with a center frequency that is continuously tunable from 1.2 to 2.6 GHz, was tested in detail. Experimental results demonstrated a resonator Q of up to 380, and typical insertion loss of -1.9 dB for a 25 MHz 3-dB bandwidth. These resonators have been used to stabilize a broadly-tunable oscillator with phase noise of -132 dBc/Hz at 100-kHz offset, with a center frequency tunable from 1.2-2.6 GHz, and a tuning speed of 1 GHz/ms
The Consumption of Reference Resources
Under the operational restriction of the U(1)-superselection rule, states
that contain coherences between eigenstates of particle number constitute a
resource. Such resources can be used to facilitate operations upon systems that
otherwise cannot be performed. However, the process of doing this consumes
reference resources. We show this explicitly for an example of a unitary
operation that is forbidden by the U(1)-superselection rule.Comment: 4 pages 6x9 page format, 2 figure
Recommended from our members
Technical Review of Residential Programmable Communicating Thermostat Implementation for Title 24-2008
Stochastic and Mixed Density Functional Theory within the projector augmented wave formalism for the simulation of warm dense matter
Stochastic and mixed stochastic-deterministic density functional theory (DFT)
are promising new approaches for the calculation of the equation-of-state and
transport properties in materials under extreme conditions. In the intermediate
warm dense matter regime, a state between correlated condensed matter and
kinetic plasma, electrons can range from being highly localized around nuclei
to delocalized over the whole simulation cell. The plane-wave basis
pseudo-potential approach is thus the typical tool of choice for modeling such
systems at the DFT level. Unfortunately, the stochastic DFT methods scale as
the square of the maximum plane-wave energy in this basis. To reduce the effect
of this scaling, and improve the overall description of the electrons within
the pseudo-potential approximation, we present stochastic and mixed DFT
developed and implemented within the projector augmented wave formalism. We
compare results between the different DFT approaches for both single-point and
molecular dynamics trajectories and present calculations of self-diffusion
coefficients of solid density carbon from 1 to 50 eV
3D printing for bio-synthetic biliary stents
Three-dimensional (3D) printing is an additive manufacturing method that holds great potential in a variety of future patient-specific medical technologies. This project validated a novel crosslinked polyvinyl alcohol (XL-PVA) 3D printed stent infused with collagen, human placental mesenchymal stem cells (PMSCs), and cholangiocytes. The biofabrication method in the present study examined 3D printing and collagen injection molding for rapid prototyping of customized living biliary stents with clinical applications in the setting of malignant and benign bile duct obstructions. XL-PVA stents showed hydrophilic swelling and addition of radiocontrast to the stent matrix improved radiographic opacity. Collagen loaded with PMSCs contracted tightly around hydrophilic stents and dense choloangiocyte coatings were verified through histology and fluorescence microscopy. It is anticipated that design elements used in these stents may enable appropriate stent placement, provide protection of the stent-stem cell matrix against bile constituents, and potentially limit biofilm development. Overall, this approach may allow physicians to create personalized bio-integrating stents for use in biliary procedures and lays a foundation for new patient-specific stent fabrication techniques
Magnetic fields in galaxies: I. Radio disks in local late-type galaxies
We develop an analytical model to follow the cosmological evolution of
magnetic fields in disk galaxies. Our assumption is that fields are amplified
from a small seed field via magnetohydrodynamical (MHD) turbulence. We further
assume that this process is fast compared to other relevant timescales, and
occurs principally in the cold disk gas. We follow the turbulent energy density
using the Shabala & Alexander (2009) galaxy formation and evolution model.
Three processes are important to the turbulent energy budget: infall of cool
gas onto the disk and supernova feedback increase the turbulence; while star
formation removes gas and hence turbulent energy from the cold gas. Finally, we
assume that field energy is continuously transferred from the incoherent random
field into an ordered field by differential galactic rotation. Model
predictions are compared with observations of local late type galaxies by Fitt
& Alexander (1993) and Shabala et al. (2008). The model reproduces observed
magnetic field strengths and luminosities in low and intermediate-mass
galaxies. These quantities are overpredicted in the most massive hosts,
suggesting that inclusion of gas ejection by powerful AGNs is necessary in
order to quench gas cooling and reconcile the predicted and observed magnetic
field strengths.Comment: 10 pages, 8 figures; MNRAS in pres
- …