Enhanced efficiency of AlGaInP disk laser by in-well pumping.

The performance of a 665-nm GaInP disk laser operated continuous-wave at 15°C both in-well-pumped at 640 nm and barrier pumped at 532 nm is reported. The efficiency with respect to the absorbed power was enhanced by 3.5 times when using a 640-nm pump instead of a 532-nm pump. In-well pumping which is based on the absorption of the pump photons within the quantum-well heterostructures of the gain region instead of short-wavelength absorption in the barrier and spacer regions reduces the quantum defect between pump and laser photon and hence the heat generation. A slope efficiency of 60% with respect to the absorbed pump power was obtained by in-well pumping at 15°C. Continuous-wave laser operation was further demonstrated at heat sink temperatures of up to 55°C. Both the measurement of photoluminescence and COMSOL simulation show that the overall heat load in the in-well pumped laser is smaller than in the barrier-pumped laser. These results demonstrate the potential of optical in-well pumping for the operation of red AlGaInP disk lasers if combined with means for efficient pump-light absorption.

Single-grating-mirror intracavity stretcher design for chirped pulse regenerative amplification.

We report for the first time, to the best of our knowledge, an innovative design concept for intracavity pulse stretching in a regenerative amplifier, employing a single "grating-mirror" based on a leaky-mode grating-waveguide design. The very compact and flexible layout allows for femtosecond pulses to be in principle easily stretched up to nanosecond durations. The design has been tested in a diode-pumped Yb:CALGO regenerative amplifier followed by a standard transmission grating compressor. Sub-200-fs pulses (stretched pulses ≈110 ps) with 205-µJ energy at 20-kHz repetition rate have been demonstrated. In order to prove the robustness and potential for energy scaling of leaky-mode grating-waveguide intracavity stretcher, we generated stretched pulses with energies of up to ≈700 µJ (400-ps long) at a lower repetition rate of 10 kHz. A simple model is proposed for the study of the cavity in presence of induced spatial chirp.

[Mechanical support in cardiogenic shock]. / Mechanische Unterstützung im kardiogenen Schock.

Treatment of patients in cardiogenic shock (CS) presenting with acute myocardial infarction (AMI) is still a challenge and mortality rates remain high, approaching 50 %. Hemodynamic stabilization before and/or after early revascularization remains the primary goal in these patients. In addition to hemodynamic support by inotropes and vasopressors, support with mechanical devices such as intra-aortic balloon pumping (IABP), percutaneous left ventricular assist devices (LVAD) and complete extracorporeal life support (ECLS) with extracorporeal membrane oxygenation (ECMO) may be considered. The use of IABP cannot be recommended anymore on a routine basis. Unfortunately, there are no large randomized data from studies evaluating treatment with mechanical support systems compared to standard treatment with respect to the clinical outcome of patients and no head-to-head comparison of different devices is available. Another important open question to be answered is which subgroups of patients may have a benefit from LVAD therapy. Guidelines discourage the routine use of mechanical support as a first-line treatment in CS patients and emphasize that the application should be restricted to those patients with refractory shock. This article gives an overview of the different devices for percutaneous mechanical support in CS and describes the available evidence and guideline recommendations.

["Fit4You"--A Programme for Prevention and Reduction of Overweight in Apprentices in the Workplace Setting]. / "Fit4U"--ein Präventionsprogramm zur Vermeidung und Verminderung von Übergewicht bei Auszubildenden im Betrieb.

The effect of health promotion at the worksite for overweight adolescents is not known. This 2-year intervention study examined the effect of a multimodal programme including nutrition counselling, sport, and life-skill training on medical and psychological outcomes. The body mass index increased slightly less in the intervention group. Semistructured interviews at the end showed that participants are highly interested in health promotion at the worksite.

Femtosecond Yb:CaGdAlO4 thin-disk oscillator.

A mode-locked thin-disk laser based on Yb:CALGO is demonstrated for the first time. At an average output power of 28 W we obtained pulses with a duration of 300 fs and a pulse energy of 1.3 µJ. 197 fs pulses with 0.9 µJ of energy were achieved at an average output power of 20 W. The shortest pulse duration measured in our experiments was 135 fs with a spectrum centered at 1043 nm. The experiments also revealed a very broad tunability from 1032 to 1046 nm with sub-200 fs pulses.

Propagation of Gaussian-apodized paraxial beams through first-order optical systems via complex coordinate transforms and ray transfer matrices.

We investigate the linear propagation of Gaussian-apodized solutions to the paraxial wave equation in free-space and first-order optical systems. In particular, we present complex coordinate transformations that yield a very general and efficient method to apply a Gaussian apodization (possibly with initial phase curvature) to a solution of the paraxial wave equation. Moreover, we show how this method can be extended from free space to describe propagation behavior through nonimaging first-order optical systems by combining our coordinate transform approach with ray transfer matrix methods. Our framework includes several classes of interesting beams that are important in applications as special cases. Among these are, for example, the Bessel-Gauss and the Airy-Gauss beams, which are of strong interest to researchers and practitioners in various fields.

Case report of a haemovigilance investigation using phylogenetic analysis of HIV-1 in Brazil.

OBJECTIVES: The aim of this work is to provide the first report of a transfusion-acquired HIV-1 infection and to verify transmission from the donor to the recipients using phylogenetic analysis of HIV-1 DNA sequences in a Brazilian blood bank. BACKGROUND: Although haemovigilance procedures based on phylogenetic analysis of HIV have been reported in several countries, this type of study has yet to be conducted in Latin America. MATERIALS AND METHODS: Upon identifying a HIV-1-positive repeat blood donor by enzyme immunoassay (EIA) blood screening, all recipients of the donor's previous donation were identified and tested for HIV-1 by EIA, nucleic acid amplification test and HIV-1 DNA sequencing and phylogenetic analysis. RESULTS: One of the recipients tested positive for HIV-1. The phylogenetic analysis showed a high genetic similarity among the viruses, thus supporting the hypothesis of transmission from the donor to the recipient. CONCLUSIONS: Phylogenetic analysis of HIV-1 DNA sequences has been a decisive tool in verifying suspected transmission of the virus from blood donor to recipient in Brazil.

[Arterial hypertension in patients with coronary artery disease]. / Arterielle Hypertonie bei Patienten mit koronarer Herzerkrankung.

Arterial hypertension is the most important risk factor for coronary artery disease (CAD). There is a high coincidence of both diseases, whereby both impair coronary microcirculatory function synergistically, which can be measured functionally by decreased coronary flow reserve. This dysfunction leads to permanent damage to the left ventricular myocardium. Lifestyle changes play a central role in the primary and secondary prevention of CAD. Additionally, there are well-established options for antihypertensive drug therapy, which should be combined with aspirin and statins. Pharmacological treatment should follow distinctive blood pressure goals in relation to the severity of CAD. Particular attention is paid in this context to the relation between diastolic blood pressure values and cardiovascular endpoints, which displays a j-shaped curve with the lowest risk at levels between 70 and 90 mmHg.

Yb:CaGdAlO4 thin-disk laser.

We present the first demonstration of a Yb:CALGO thin-disk laser. In a slightly multimode configuration, we obtained up to 30 W of average power at a slope efficiency of 40% and an optical-to-optical efficiency of 32%. With a single-mode cavity, an average power of 25 W was achieved. A tuning range from 1018 to 1052 nm could be demonstrated by inserting a prism into the cavity. In the Q-switched regime, we obtained 1 mJ of pulse energy at a repetition rate of 100 Hz.

Randomized clinical trial of the i-gel™ and Magill tracheal tube or single-use ILMA™ and ILMA™ tracheal tube for blind intubation in anaesthetized patients with a predicted difficult airway.

BACKGROUND: The single-use supraglottic airway device i-gel™ has been described in several case reports as a conduit for intubation, but no prospective data about success rates of blind intubation are available. Therefore, we performed this prospective randomized controlled trial to compare the success rate of blind tracheal intubation with a Magill PVC tube through the i-gel™ with intubation using an sILMA™ PVC tube through the single-use intubating laryngeal mask airway (sILMA™). METHODS: With ethics committee approval and written informed consent, 80 patients with predictors of a difficult airway were computer randomized to either supraglottic airway device (SAD). The corresponding tracheal tube (TT) was introduced through the SAD under fibreoptic visualization but without fibreoptic guidance. Primary outcome was blind intubation success rate. Times, airway leak pressure, fibreoptic view, and adverse events were recorded. To control for the influence of the TT, we compared data from 40 patients described in an accompanying study (sILMA™ with Magill TT and i-gel™ with sILMA™ TT). RESULTS: Blind intubation success rate through the sILMA™ (69%) was higher than with the i-gel™ (15%, P<0.001). Data from the other patient group excluded the TT type as the primary cause for the difference in success rate. Removal of SADs was without problems with no difference between the type of SAD. CONCLUSIONS: Blind tracheal intubation using the sILMA™ tube through the sILMA™ is much more successful than blind intubation with a Magill PVC tube through the i-gel™. Because of its low success rate, we would not recommend blind intubation through the i-gel™.