Active position stabilization of an atomic cloud in a narrow-line magneto-optical trap using a Raspberry Pi.

We report on a simple method for an active position stabilization of an atomic cloud trapped in a magneto-optical trap operating on the narrow 182 kHz intercombination line of atomic ytterbium. Our method makes use of the significant sensitivity of the position of a narrow-line magneto-optical trap (MOT) on the laser frequency. After in situ detection of the MOT position using a Pi Camera, an error signal is generated by a Raspberry Pi, which is directly fed back onto the laser frequency. Thus, perturbations of the MOT position, e.g., due to drifts of the Zerodur cavity to which the MOT laser is stabilized or the ambient magnetic field, can be compensated directly. Our method allows for long-term stabilization of the MOT position on a 10 µm scale and thus improves loading of a tightly focused optical trap.

Alleviation of chronic venous leg ulcers with a hand-held dielectric barrier discharge plasma generator (PlasmaDerm(®) VU-2010): results of a monocentric, two-armed, open, prospective, randomized and controlled trial (NCT01415622).

BACKGROUND: Cold atmospheric plasma (CAP, i.e. ionized air) is an innovating promising tool in reducing bacteria. OBJECTIVE: We conducted the first clinical trial with the novel PlasmaDerm® VU-2010 device to assess safety and, as secondary endpoints, efficacy and applicability of 45 s/cm(2) cold atmospheric plasma as add-on therapy against chronic venous leg ulcers. METHODS: From April 2011 to April 2012, 14 patients were randomized to receive standardized modern wound care (n = 7) or plasma in addition to standard care (n = 7) 3× per week for 8 weeks. The ulcer size was determined weekly (Visitrak® , photodocumentation). Bacterial load (bacterial swabs, contact agar plates) and pain during and between treatments (visual analogue scales) were assessed. Patients and doctors rated the applicability of plasma (questionnaires). RESULTS: The plasma treatment was safe with 2 SAEs and 77 AEs approximately equally distributed among both groups (P = 0.77 and P = 1.0, Fisher's exact test). Two AEs probably related to plasma. Plasma treatment resulted in a significant reduction in lesional bacterial load (P = 0.04, Wilcoxon signed-rank test). A more than 50% ulcer size reduction was noted in 5/7 and 4/7 patients in the standard and plasma groups, respectively, and a greater size reduction occurred in the plasma group (plasma -5.3 cm(2) , standard: -3.4 cm(2) ) (non-significant, P = 0.42, log-rank test). The only ulcer that closed after 7 weeks received plasma. Patients in the plasma group quoted less pain compared to the control group. The plasma applicability was not rated inferior to standard wound care (P = 0.94, Wilcoxon-Mann-Whitney test). Physicians would recommend (P = 0.06, Wilcoxon-Mann-Whitney test) or repeat (P = 0.08, Wilcoxon-Mann-Whitney test) plasma treatment by trend. CONCLUSION: Cold atmospheric plasma displays favourable antibacterial effects. We demonstrated that plasma treatment with the PlasmaDerm® VU-2010 device is safe and effective in patients with chronic venous leg ulcers. Thus, larger controlled trials and the development of devices with larger application surfaces are warranted.

Determination of the s-wave scattering length of chromium.

We have measured the deca-triplet s-wave scattering length of the bosonic chromium isotopes 52Cr and 50Cr. From the time constants for cross-dimensional thermalization in ultracold atomic samples, we have determined the magnitudes |a(52Cr)|=(170+/-39)a(0) and |a(50Cr)|=(40+/-15)a(0), where a(0)=0.053 nm. By measuring the rethermalization rate of 52Cr over a wide temperature range and comparing the temperature dependence with the effective-range theory and numerical single-channel calculations, we have obtained strong evidence that the sign of a(52Cr) is positive. Rescaling our 52Cr model potential to 50Cr strongly suggests that a(50Cr) is positive also.

Sodium Bose-Einstein condensates in the F = 2 state in a large-volume optical trap.

We have investigated the properties of Bose-Einstein condensates of sodium atoms in the upper hyperfine ground state. Condensates in the high-field seeking [F=2, m(F)=-2> state were created in a large volume optical trap from initially prepared [F=1, m(F)=-1> condensates using a microwave transition at 1.77 GHz. We found condensates in the stretched state [F=2, m(F)=-2> to be stable for several seconds at densities in the range of 10(14) atoms/cm(3). In addition, we studied the clock transition [F=1, m(F)=0> --> [F=2, m(F)=0> in a sodium Bose-Einstein condensate and determined a density-dependent frequency shift of (2.44+/-0.25+/-0.5) x 10(-12) Hz cm(3).

Imprinting vortices in a Bose-Einstein condensate using topological phases.

Vortices were imprinted in a Bose-Einstein condensate using topological phases. Sodium condensates held in a Ioffe-Pritchard magnetic trap were transformed from a nonrotating state to one with quantized circulation by adiabatically inverting the magnetic bias field along the trap axis. Using surface wave spectroscopy, the axial angular momentum per particle of the vortex states was found to be consistent with 2 variant Planck's over 2pi or 4 variant Planck's over 2pi, depending on the hyperfine state of the condensate.

[Indicators of structural quality in palliative care for cancer pain patients in Lower-Saxony]. / Palliativmedizinische Betreuung von Tumorschmerzpatienten in Niedersachsen Indikatoren der Strukturqualität.

INTRODUCTION: Palliative care in Germany fails to reach established standards. To improve this situation the Chamber of Physicians of Lower-Saxony initiated SUPPORT in 1995. Prior to interventions structural quality of care was evaluated, specifically the rate of availability of opioid-prescription-forms and the ability to treat chronic pain (defined as a construct of knowledge, attitudes and skills) were examined. METHODS: The survey was carried out using a standardized questionnaire mailed to a representative stratified sample of 1200 physicians. RESULTS: Out of 865 answering physicians (response rate 72.1%) only 36.9% had their own opioid-prescription-forms. Differentiations regarding to specialty, working place (clinic vs. private practice) and treatment of cancer pain patients during the last three months shows a better result for GPs (84.6%), internists (48.6%), gynecologists (51%) and pain specialists (66.7%). Only 33.1% of respondents claimed knowledge of the WHO-3-step-analgesic-ladder. Again the aforementioned differentiations yield somewhat better results for GPs (49.2%), internists (51.5%), gynecologists (34.7%) and pain specialists (55.6%), however only two thirds of these physicians were able to identify the correct number of steps of the WHO-algorithm. CONCLUSIONS: These results verify an insufficient structural quality in palliative care in Lower-Saxony. In the authors' opinion effective improvements can only be achieved by implementing a parallel strategy:improvement of basic knowledge in pain management with sufficient transfer of this knowledge into practice as well as raising the rate of availability of opioid-prescription-forms,and, on the other hand, establishing local palliative-care-teams with nursing and medical expertise with 24/7 on-demand availability to optimize palliative care.

Two-species mixture of quantum degenerate Bose and Fermi gases.

We have produced a macroscopic quantum system in which a 6Li Fermi sea coexists with a large and stable 23Na Bose-Einstein condensate. This was accomplished using interspecies sympathetic cooling of fermionic 6Li in a thermal bath of bosonic 23Na. The system features rapid thermalization and long lifetimes.

Transport of Bose-Einstein condensates with optical tweezers.

We have transported gaseous Bose-Einstein condensates over distances up to 44 cm. This was accomplished by trapping the condensate in the focus of an infrared laser and translating the location of the laser focus with controlled acceleration. Condensates of order 10(6) atoms were moved into an auxiliary chamber and loaded into a magnetic trap formed by a Z-shaped wire. This transport technique avoids the optical and mechanical access constraints of conventional condensate experiments and creates many new scientific opportunities.

Realization of Bose-Einstein condensates in lower dimensions.

Bose-Einstein condensates of sodium atoms have been prepared in optical and magnetic traps in which the energy-level spacing in one or two dimensions exceeds the interaction energy between atoms, realizing condensates of lower dimensionality. The crossover into two-dimensional and one-dimensional condensates was observed by a change in aspect ratio and by the release energy converging to a nonzero value when the number of trapped atoms was reduced.

Observation of vortex phase singularities in Bose-Einstein condensates.

We have observed phase singularities due to vortex excitation in Bose-Einstein condensates. Vortices were created by moving a laser beam through a condensate. They were observed as dislocations in the interference fringes formed by the stirred condensate and a second unperturbed condensate. The velocity dependence for vortex excitation and the time scale for re-establishing a uniform phase across the condensate were determined.

Amplification of light and atoms in a bose-einstein condensate

A Bose-Einstein condensate illuminated by a single off-resonant laser beam ("dressed condensate") shows a high gain for matter waves and light. We have characterized the optical and atom-optical properties of the dressed condensate by injecting light or atoms, illuminating the key role of long-lived matter wave gratings produced by the condensate at rest and recoiling atoms. The narrow bandwidth for optical gain gave rise to an extremely slow group velocity of an amplified light pulse ( approximately 1 m/s).

Suppression and enhancement of impurity scattering in a Bose-Einstein condensate.

Impurity atoms propagating at variable velocities through a trapped Bose-Einstein condensate were produced using a stimulated Raman transition. The redistribution of momentum by collisions between the impurity atoms and the stationary condensate was observed in a time-of-flight analysis. The collisional cross section was dramatically reduced when the impurity velocity was reduced below the condensate speed of sound, in agreement with the Landau criterion for superfluidity. For large numbers of impurity atoms, we observed an enhancement of atomic collisions due to bosonic stimulation. This enhancement is analogous to optical super-radiance.