Proton relaxation times in human red bone marrow by volume selective magnetic resonance spectroscopy

In hematological diseases the composition of red bone marrow shows alterations. The relaxation timesT ₁ andT ₂ of water and lipids in human hemopoietic bone marrow of 14 normal volunteers and 10 patients with acute leukemia and bone marrow carcinosis are determined using a double spin echo spectroscopy sequencein vivo. The volumes of interest (VOI) of (13 mm)³ in the center of vertebral bodies are examined using different measurement parameters. ForT ₁ measurements an inversion-recovery method is used.T ₂ is evaluated from spectra with differentTE. T ₁ (water) is found in a range between 1000 and 1700 ms,T ₁ (lipids) in a range between 260 and 320 ms in healthy volunteers.T ₂ (water) is determined between 32 and 65 ms. In some cases phase distortions of the water signals occur in the spectra. Water flow within the VOI may be a possible reason.T ₂ (lipids) is evaluated between 73 and 91 ms. The patients with acute leukemia exhibit clearly reduced lipid signals in their spectra. Lipid relaxation times could not be determined in these cases.T ₂ (water) is prolonged in acute leukemia to 51–98 ms.T ₁ (water) was not significantly different from values of healthy volunteers in our measurements. Results are discussed in comparison to relaxometric data from imaging and STEAM spectroscopic methods of other authors.     

The REX-ISOLDE project

The Radioactive Beam Experiment REX-ISOLDE [1–3] is a pilot experiment at ISOLDE (CERN) testing the new concept of post acceleration of radioactive ion beams by using charge breeding of the ions in a high charge state ion source and the efficient acceleration of the highly charged ions in a short LINAC using modern ion accelerator structures. In order to prepare the ions for the experiments singly charged radioactive ions from the on-line mass separator ISOLDE will be cooled and bunched in a Penning trap, charge bred in an electron beam ion source (EBIS) and finally accelerated in the LINAC. The LINAC consists of a radiofrequency quadrupole (RFQ) accelerator, which accelerates the ions up to 0.3 MeV/u, an interdigital H-type (IH) structure with a final energy between 1.1 and 1.2 MeV/u and three seven gap resonators, which allow the variation of the final energy. With an energy of the radioactive beams between 0.8 MeV/u and 2.2 MeV/u a wide range of experiments in the field of nuclear spectroscopy, astrophysics and solid state physics will be addressed by REX-ISOLDE. This revised version was published online in July 2006 with corrections to the Cover Date.     

Scattering experiments on the structure of concentrated dispersions

 In this work the Couette cell is compared with a more recently constructed disk shear cell. There are distinct advantages of the disk over the Couette cell, in particular, when it comes to the determination of the intensity along certain Bragg rods. Received: 12 December 2000 Accepted: 31 January 2001     

MAFF — The Munich accelerator for fission fragments

At the new high flux reactor FRM-II in Munich the accelerator MAFF (Munich accelerator for fission fragments) is under design. In the high neutron flux of 10¹⁴ n/cm² s up to 10¹⁴ neutron-rich fission fragments per second are produced in the 1 g U-235 target. Ions with an energy of 30 keV are extracted from the ion source. In the mass separator two isotopes can be selected. One of the beams is used for low energy experiments, the other one is injected into an ECRIS (or EBIS) for charge breeding to a q/A≥0.16. A gas filled RFQ cooler is used for emittance improvement. The subsequent LINAC delivers beams with an energy ranging from 3.7 MeV/u to 5.9 MeV/u. New IH structures are being developed at the Munich tandem laboratory. A small storage ring is planned in a further stage to recycle the fission fragments. A thin target foil can be placed into this ring, e.g., for synthesis of super-heavy elements. The through-going beam tube has been installed in the heavy water tank of the reactor. Tests of the target ion source in a special oven to test long term stability and safety tests were in progress.     

Non-stoichiometry and magneto-optic properties of magnetic bubble thin films of TmIG substituted with bismuth and gallium

Thulium iron garnet thin films substituted with bismuth and gallium were prepared by LPE from a PbO.B₂O₃ flux. Radioactive isotope tracers were added to the melt as the chemical analysis technique. The deviation from the ratio (Pb+Bi+Tm)/(Fe+Ga)=0.6 of the layers was large and a proportion of the thulium ions possibly lie on the octahedral crystallographic sites. The concentration of Bi, Pb, and Ga as a function of the growth temperature was studied. The magneto-optic properties show that the layers are well suited for use in a magneto-optic device. A figure of merit of 2.5 degree per decibel at λ=560 nm was obtained and some magnetic bubble parameters are also presented.     

Localized Larmor frequency-guided fat and water proton MRI of the spine: a method to emphasize pathological findings.

A measurement protocol providing a correct adjustment of the irradiation frequencies for well separated fat and water images of the lumbar spine is presented. To determine accurately the Larmor frequencies of water and fat protons within the vertebral bodies, a volume selective spectrum of a volume element (13 mm)3 located in a lumbar vertebral body was acquired with the 90 degrees-180 degrees-180 degrees double spin-echo method. These Larmor frequencies are used to adjust the frequency-selective pulse of the SENEX chemical-shift imaging sequence. This procedure provides well separated fat and water images for a large field of view even in the inhomogeneous region of the vertebral column. Their clinical importance is demonstrated by localized Larmor frequency-guided (LLFG) SENEX 1H images of the lumbar spine in healthy persons of different age and in a patient with acute myeloid leukemia.     

Upper and lower bounds to critical values of the Hartree operator

Upper and lower bounds for the minimal critical energy E of the Hartree operator for helium are calculated. We show that a Ritz analogous procedure for the calculation of the upper bounds converges to the exact value. The lower bound to E yields that the ground state E_H of the helium atom is strictly lower than 2E.