Decorrelation Times of Photospheric Fields and Flows

We use autocorrelation to investigate evolution in flow fields inferred by applying Fourier Local Correlation Tracking (FLCT) to a sequence of high-resolution (0.3 \arcsec), high-cadence ($\simeq 2$ min) line-of-sight magnetograms of NOAA active region (AR) 10930 recorded by the Narrowband Filter Imager (NFI) of the Solar Optical Telescope (SOT) aboard the {\em Hinode} satellite over 12--13 December 2006. To baseline the timescales of flow evolution, we also autocorrelated the magnetograms, at several spatial binnings, to characterize the lifetimes of active region magnetic structures versus spatial scale. Autocorrelation of flow maps can be used to optimize tracking parameters, to understand tracking algorithms' susceptibility to noise, and to estimate flow lifetimes. Tracking parameters varied include: time interval $\Delta t$ between magnetogram pairs tracked, spatial binning applied to the magnetograms, and windowing parameter $\sigma$ used in FLCT. Flow structures vary over a range of spatial and temporal scales (including unresolved scales), so tracked flows represent a local average of the flow over a particular range of space and time. We define flow lifetime to be the flow decorrelation time, $\tau$. For $\Delta t > \tau$, tracking results represent the average velocity over one or more flow lifetimes. We analyze lifetimes of flow components, divergences, and curls as functions of magnetic field strength and spatial scale. We find a significant trend of increasing lifetimes of flow components, divergences, and curls with field strength, consistent with Lorentz forces partially governing flows in the active photosphere, as well as strong trends of increasing flow lifetime and decreasing magnitudes with increases in both spatial scale and $\Delta t$.Comment: 48 pages, 20 figures, submitted to the Astrophysical Journal; full-resolution images in manuscript (8MB) at http://solarmuri.ssl.berkeley.edu/~welsch/public/manuscripts/flow_lifetimes_v2.pd

SOCIOECONOMIC ISSUES IN IRRIGATION DEVELOPMENT AND DISTRIBUTION

Resource /Energy Economics and Policy,

Development of Rebunching Cavities at IAP

A focus of work at IAP has been the development and optimization of spiral loaded cavities since the 1970s [A. Schempp et al, NIM 135, 409 (1976)]. These cavities feature a high efficiency, a compact design and a big variety of possible fields of application. They find use both as bunchers and post accelerators to vary the final energy of the beam. In comparison to other available designs, the advantage of these structures lies in their small size. Furthermore they can easily be tuned to the required resonance frequency by varying the length of the spiral. Due to the small size of the cavities the required budget can also be kept low. Here, two slightly different types of spiral loaded cavities, which were built for the REX-ISOLDE project at CERN and the intensity upgrade program at GSI are being discussed.Comment: 4 pages, 9 figures PRST-AB special LINAC 2000 edition with additional information in comparison to the 3 pages LINAC paper physics/000708

Histological investigations on the thyroid glands of marine mammals (Phoca vitulina, Phocoena phocoena) and the possible implications of marine pollution

In 1988 and 1989, thousands of harbor seals (Phoca vitulina) died in the North Sea from phocine distemper infection. The morphology of thyroid glands from 40 harbor seals found dead on the North Sea coastlines of Schleswig-Holstein, Federal Republic of Germany, during an epizootic of phocine distemper, was compared with the morphology of thyroid glands from five healthy harbor seals collected in Iceland. Thyroid glands from seven harbor porpoises (Phocoena phocoena) found dead in 1990 on the North Sea coastlines also were evaluated. Colloid depletion and fibrosis were found in the thyroid glands of harbor seals which died during the epizootic, but not in animals from Iceland. Thyroid glands of the porpoises showed similar lesions, but to a lesser degree, than those observed in the North Sea seals

Low Power Measurements on a Finger Drift Tube Linac

The efficiency of RFQs decreases at particle energies higher than a few MeV/u and thus typically DTL structures are used in this energy region. However, the rf field in the gap always has a defocusing influence on the beam. In order to compensate this effect, fingers with quadrupole symmetry were added to the drift tubes, the focusing fingers do not need an additional power source or feed through. Beam dynamics have been studied with the code RFQSIM. Detailed analysis of the field distribution was done and the geometry of the finger array has been optimized with respect to beam dynamics. A prototype cavity with finger drift tubes was built and low power measurements were done. In this contribution, the results of the rf simulation with Microwave Studio are compared to bead perturbation measurements and the focusing effect on the beam is discussed

Extension of the Measurement Capabilities of the Quadrupole Resonator

The Quadrupole Resonator, designed to measure the surface resistance of superconducting samples at 400 MHz has been refurbished. The accuracy of its RF-DC compensation measurement technique is tested by an independent method. It is shown that the device enables also measurements at 800 and 1200 MHz and is capable to probe the critical RF magnetic field. The electric and magnetic field configuration of the Quadrupole Resonator are dependent on the excited mode. It is shown how this can be used to distinguish between electric and magnetic losses.Comment: 6 pages, g figure

Magnetic helicity transported by flux emergence and shuffling motions in Solar Active Region NOAA 10930

We present a new methodology which can determine magnetic helicity transport by the passage of helical magnetic field lines from sub-photosphere and the shuffling motions of foot-points of preexisting coronal field lines separately. It is well known that only the velocity component which is perpendicular to the magnetic field ($\upsilon_{\perp B}$) has contribution to the helicity accumulation. Here, we demonstrate that $\upsilon_{\perp B}$ can be deduced from horizontal motion and vector magnetograms, under a simple relation of $\upsilon_t = \mu_t + \frac{\upsilon_n}{B_n} B_t$ as suggested by D$\acute{e}$moulin & Berger (2003). Then after dividing $\upsilon_{\perp B}$ into two components, as one is tangential and the other is normal to the solar surface, we can determine both terms of helicity transport. Active region (AR) NOAA 10930 is analyzed as an example during its solar disk center passage by using data obtained by the Spectro-Polarimeter and the Narrowband Filter Imager of Solar Optical Telescope on board Hinode. We find that in our calculation, the helicity injection by flux emergence and shuffling motions have the same sign. During the period we studied, the main contribution of helicity accumulation comes from the flux emergence effect, while the dynamic transient evolution comes from the shuffling motions effect. Our observational results further indicate that for this AR, the apparent rotational motion in the following sunspot is the real shuffling motions on solar surface

Atomic entanglement near a realistic microsphere

We study a scheme for entangling two-level atoms located close to the surface of a dielectric microsphere. The effect is based on medium-assisted spontaneous decay, rigorously taking into account dispersive and absorptive properties of the microsphere. We show that even in the weak-coupling regime, where the Markov approximation applies, entanglement up to 0.35 ebits between two atoms can be created. However, larger entanglement and violation of Bell's inequality can only be achieved in the strong-coupling regime.Comment: 16 pages, 4 figures, Late

Tomographic reconstruction of quantum states in N spatial dimensions

Most quantum tomographic methods can only be used for one-dimensional problems. We show how to infer the quantum state of a non-relativistic N-dimensional harmonic oscillator system by simple inverse Radon transforms. The procedure is equally applicable to finding the joint quantum state of several distinguishable particles in different harmonic oscillator potentials. A requirement of the procedure is that the angular frequencies of the N harmonic potentials are incommensurable. We discuss what kind of information can be found if the requirement of incommensurability is not fulfilled and also under what conditions the state can be reconstructed from finite time measurements. As a further example of quantum state reconstruction in N dimensions we consider the two related cases of an N-dimensional free particle with periodic boundary conditions and a particle in an N-dimensional box, where we find a similar condition of incommensurability and finite recurrence time for the one-dimensional system.Comment: 8 pages, 1 figur