Achromatic, planar Fresnel-reflector for a single-beam magneto-optical trap.

We present a novel achromatic, planar, periodic mirror structure for single-beam magneto-optical trapping and demonstrate its use in the first- and second-stage cooling and trapping for different isotopes of strontium. We refer to it as a Fresnel magneto-optical trap (MOT) as the structure is inspired by Fresnel lenses. By design, it avoids many of the problems that arise for multi-color cooling using planar structures based on diffraction gratings, which have been the dominant planar structures to be used for single-beam trapping thus far. In addition to a complex design process and cost-intensive fabrication, diffraction gratings suffer from their inherent chromaticity, which causes different axial displacements of trap volumes for different wavelengths and necessitates trade-offs in their diffraction properties and achievable trap depths. In contrast, the Fresnel-reflector structure presented here is a versatile, easy-to-manufacture device that combines achromatic beam steering with the advantages of a planar architecture. It enables miniaturizing trapping systems for alkaline-earth-like atoms with multiple cooling transitions as well as multi-species trapping in the ideal tetrahedral configuration and within the same volume above the structure. Our design presents a novel approach for the miniaturization of cold-atom systems based on single-beam MOTs and enables the widespread adoption of these systems.

A field ionizer for photodetachment studies of negative ions.

In this paper, we present an apparatus for studies into the photodetachment process of atomic negative ions. State-selective detection of the residual atom following the initial photodetachment step is achieved by combining resonant laser excitation of the photo-detached atom with electric field ionization. The resonance ionization technique in combination with a co-linear ion-laser beam geometry gives an experimental apparatus that has both high selectivity and sensitivity. In addition to measurements of a single selected partial photodetachment channel, the apparatus also can be used to study a manifold of photodetachment channels in which the residual atom is left in a high-lying Rydberg state and for investigation of the double electron-detachment process. Ion-optical simulations in SIMION are used to illustrate the operation of the apparatus for studying such processes. Successful performance of the apparatus against the simulation is demonstrated by a high resolution study of the photodetachment of cesium, where the sharp s-wave threshold of the photodetachment processes leaving the residual atom in the excited 6p state was investigated.

An ultralow-noise superconducting radio-frequency ion trap for frequency metrology with highly charged ions.

We present a novel ultrastable superconducting radio-frequency (RF) ion trap realized as a combination of an RF cavity and a linear Paul trap. Its RF quadrupole mode at 34.52 MHz reaches a quality factor of Q ≈ 2.3 × 105 at a temperature of 4.1 K and is used to radially confine ions in an ultralow-noise pseudopotential. This concept is expected to strongly suppress motional heating rates and related frequency shifts that limit the ultimate accuracy achieved in advanced ion traps for frequency metrology. Running with its low-vibration cryogenic cooling system, electron-beam ion trap, and deceleration beamline supplying highly charged ions (HCIs), the superconducting trap offers ideal conditions for optical frequency metrology with ionic species. We report its proof-of-principle operation as a quadrupole-mass filter with HCIs and trapping of Doppler-cooled 9Be+ Coulomb crystals.

Operating a cesium sputter source in a pulsed mode.

A scheme is presented for pulsing of a cesium sputter negative ion source by periodically switching on and off the high voltage driving the sputtering process. We demonstrate how the pulsed ion beam can be used in combination with a pulsed laser (6 ns pulse length) that has a 10 Hz repetition rate to study the photodetachment process, where a negative ion is neutralized due to the absorption of a photon. In such experiments, where the ion beam is used only for a small fraction of the time, we show that the pulsed mode operation can increase the lifetime of a cathode by two orders of magnitude as compared with DC operation. We also investigate how the peak ion current compares with the ion current obtained when the source is run in a DC mode. We find that the peak current in the pulsed mode is strongly dependent on the ion species. In some cases, we observed a strong enhancement, whereas others showed only a moderate enhancement, or even a decrease, in the peak current. We conclude that the pulsed mode operation can be of great value when the negative ion to be investigated requires cathodes that have short lifetimes, expensive materials, or those with relatively small ion beam yields, in the latter case limited to elements with large enhancement factors.

Coherent laser spectroscopy of highly charged ions using quantum logic.

Precision spectroscopy of atomic systems1 is an invaluable tool for the study of fundamental interactions and symmetries2. Recently, highly charged ions have been proposed to enable sensitive tests of physics beyond the standard model2-5 and the realization of high-accuracy atomic clocks3,5, owing to their high sensitivity to fundamental physics and insensitivity to external perturbations, which result from the high binding energies of their outer electrons. However, the implementation of these ideas has been hindered by the low spectroscopic accuracies (of the order of parts per million) achieved so far6-8. Here we cool trapped, highly charged argon ions to the lowest temperature reported so far, and study them using coherent laser spectroscopy, achieving an increase in precision of eight orders of magnitude. We use quantum logic spectroscopy9,10 to probe the forbidden optical transition in 40Ar13+ at a wavelength of 441 nanometres and measure its excited-state lifetime and g-factor. Our work unlocks the potential of highly charged ions as ubiquitous atomic systems for use in quantum information processing, as frequency standards and in highly sensitive tests of fundamental physics, such as searches for dark-matter candidates11 or violations of fundamental symmetries2.

A cryogenic radio-frequency ion trap for quantum logic spectroscopy of highly charged ions.

A cryogenic radio-frequency ion trap system designed for quantum logic spectroscopy of highly charged ions (HCI) is presented. It includes a segmented linear Paul trap, an in-vacuum imaging lens, and a helical resonator. We demonstrate ground state cooling of all three modes of motion of a single 9Be+ ion and determine their heating rates as well as excess axial micromotion. The trap shows one of the lowest levels of electric field noise published to date. We investigate the magnetic-field noise suppression in cryogenic shields made from segmented copper, the resulting magnetic field stability at the ion position and the resulting coherence time. Using this trap in conjunction with an electron beam ion trap and a deceleration beamline, we have been able to trap single highly charged Ar13+ (Ar XIV) ions concurrently with single Be+ ions, a key prerequisite for the first quantum logic spectroscopy of a HCI. This major stepping stone allows us to push highly-charged-ion spectroscopic precision from the gigahertz to the hertz level and below.

Closed-cycle, low-vibration 4 K cryostat for ion traps and other applications.

In vacuo cryogenic environments are ideal for applications requiring both low temperatures and extremely low particle densities. This enables reaching long storage and coherence times, for example, in ion traps, essential requirements for experiments with highly charged ions, quantum computation, and optical clocks. We have developed a novel cryostat continuously refrigerated with a pulse-tube cryocooler and providing the lowest vibration level reported for such a closed-cycle system with 1 W cooling power for a <5 K experiment. A decoupling system suppresses vibrations from the cryocooler by three orders of magnitude down to a level of 10 nm peak amplitudes in the horizontal plane. Heat loads of about 40 W (at 45 K) and 1 W (at 4 K) are transferred from an experimental chamber, mounted on an optical table, to the cryocooler through a vacuum-insulated massive 120 kg inertial copper pendulum. The 1.4 m long pendulum allows installation of the cryocooler in a separate, acoustically isolated machine room. At the experimental chamber, we measured the residual vibrations using an interferometric setup. The positioning of the 4 K elements is reproduced to better than a few micrometer after a full thermal cycle to room temperature. Extreme high vacuum on the 10-15 mbar level is achieved. In collaboration with the Max-Planck-Institut für Kernphysik, such a setup is now in operation at the Physikalisch-Technische Bundesanstalt for a next-generation optical clock experiment using highly charged ions.

Coulomb crystallization of highly charged ions.

Control over the motional degrees of freedom of atoms, ions, and molecules in a field-free environment enables unrivalled measurement accuracies but has yet to be applied to highly charged ions (HCIs), which are of particular interest to future atomic clock designs and searches for physics beyond the Standard Model. Here, we report on the Coulomb crystallization of HCIs (specifically (40)Ar(13+)) produced in an electron beam ion trap and retrapped in a cryogenic linear radiofrequency trap by means of sympathetic motional cooling through Coulomb interaction with a directly laser-cooled ensemble of Be(+) ions. We also demonstrate cooling of a single Ar(13+) ion by a single Be(+) ion-the prerequisite for quantum logic spectroscopy with a potential 10(-19) accuracy level. Achieving a seven-orders-of-magnitude decrease in HCI temperature starting at megakelvin down to the millikelvin range removes the major obstacle for HCI investigation with high-precision laser spectroscopy.

F-ara-A pharmacokinetics during reduced-intensity conditioning therapy with fludarabine and busulfan.

Fludarabine is commonly used in combination with busulfan as part of conditioning regimens before allogeneic stem cell transplantation. So far, no data are available on busulfan-fludarabine drug interactions in transplant recipients. The pharmacokinetic (PK) properties of F-ara-A (9-beta-D-arabinosyl-2-fluoradenine) before and after application of busulfan were prospectively investigated in 16 patients with hematological malignancies. The conditioning regimen consisted of intravenous fludarabine 30 mg/m(2) over 30 min from day -6 to day -3, and oral busulfan given at 1 mg/kg every 6 h from day -5 to day -2. PK parameters of F-ara-A, derived from plasma and urine on day -6, -5, -4 and -3, were determined using high-performance liquid chromatography (HPLC). AUC, C(max), t(1/2), Cl(total) and V(SS) were 21.9 microMh, 3.5 microM, 13.0 h, 4.3 l/h/m(2), 60.0 l/m(2) on day -6 and 22.4 microMh, 3.5 microM, 14.0 h, 4.7 l/h/m(2), 69.0 l/m(2) on day -5 to (-2), respectively. Cl(renal) and the urine-recovery were 4.8 l/h, 43.7% of the fludarabine dose on day -6 and 3.9 l/h, 44.2% of the fludarabine dose on day -5 to (-2), respectively. There were no changes in PK parameters of fludarabine given before and after intake of busulfan. This implies that a clinically relevant busulfan-fludarabine drug interaction is unlikely.

Activity of sirolimus in patients with myelodysplastic syndrome--results of a pilot study.

The pathophysiology of the myelodysplastic syndromes (MDS) involves disturbed regulation of angiogenesis, apoptosis, proliferation and differentiation as well as immune surveillance. Increasing data suggest that sirolimus might affect these pathways positively, thus being of possible therapeutic benefit in patients with this disease. Nineteen patients (n = 19) with a median age of 72 years (range 54-80 years) diagnosed with MDS received sirolimus orally with a target blood concentration of 3-12 ng/ml. Sirolimus was administered for a median of 3.7 months (range 0.3-11 months). Three patients [1 x refractory anaemia with excess blasts (RAEB)-2, 1 x RAEB-1, 1 x refractory cytopenia with multilineage dysplasia] showed either a major (1 x platelet, 1 x neutrophil) or a minor (1 x erythroid, 2 x platelet) haematological response according to International Working Group criteria. Major side-effects were hyperlipidaemia (n = 4), stomatitis (n = 3), thrombocytopenia (n = 2) and urinary tract infection (n = 1). These data suggest that sirolimus has activity in a subset of patients with more advanced MDS.

Liquid chromatographic method for detection and quantitation of STI-571 and its main metabolite N-desmethyl-STI in plasma, urine, cerebrospinal fluid, culture medium and cell preparations.

An isocratic online-enrichment HPLC-assay was developed allowing for the simple and fast separation and quantitation of STI-571 and its main metabolite N-desmethyl-STI (N-DesM-STI) in plasma, urine, cerebrospinal fluid (CSF), culture media and cell preparations in various concentrations using UV-detection at 260 nm. The analytical procedure consists of an online concentration of STI-571 and N-DesM-STI in the HPLC system followed by the elution on a ZirChrom-PBD analytical column. Time of analysis is 40 min including the enrichment time of 5 min. The detection limit is 10 ng/ml in plasma, CSF, culture medium (RPMI) and 25 ng/ml in urine for both STI-571 and N-DesM-STI. The intra-day precision, as expressed by the coefficient of variation (CV), in plasma samples ranges between 1.74 and 8.60% for STI-571 and 1.45 and 8.87% for N-DesM-STI. The corresponding values for urine measurements are 2.17-7.54% (STI-571) and 1.31-9.51% (N-DesM-STI). The inter-day precision analyzed over a 7-month time period was 8.31% (STI-571) or 6.88% (N-DesM-STI) and 16.45% (STI-571) or 14.83% (N-DesM-STI) for a concentration of 1000 ng/ml in plasma and 750 ng/ml in urine, respectively. Moreover, we demonstrate that with an alternative, but more time and labor consuming sample preparation and the implementation of electrochemical detection, a detection limit < 10 ng/ml can be achieved. The method described was used to perform pharmacokinetic measurements of STI-571 and N-desmethyl-STI in patient samples and for kinetic measurements of intracellular STI-571 and N-DesM-STI following in vitro incubation.

[Experiences in diagnosis and therapy of puppy diseases in the fist days of life]. / Erfahrungen in der Diagnostik und Therapie von Welpenerkrankungen in den ersten Lebenstagen.

In a survey covering 145 puppies in 60 litters diseases after parturition and within the first week of life are discussed. Problems in the diagnosis and therapy are correlated with further investigations, i.e. bacteriology, sensitivity tests and in some cases necropsy. Neonatal respiratory distress syndrome and bacterial infections have been found to be the most common diseases in the first days of life in puppies.

Foreign bodies in the hand.

A prospective study was carried out on 164 consecutive cases presenting at the Accident Department with foreign bodies in the hand. The distal segment of the digits was the commonest site. The late, symptomatic presentation of patients, together with the development of symptoms in patients managed conservatively indicate that foreign bodies should be removed. General anaesthesia is rarely required, but an effective "block" with a tourniquet is necessary, as infiltration anaesthesia has a high failure rate, and secondary exploration a high complication rate. Glass fragments are almost always visible on plain x-rays.