High-performance cavity-dumped Q-switched Alexandrite laser CW diode-pumped in double-pass configuration.

We present a high-performance Alexandrite laser for LIDAR applications with repetition rates up to 20 kHz in cavity-dumped Q-switched operation continuous-wave diode-pumped in the red spectral region. With a double-pass pump configuration, short pulses with 2.8 ns duration at repetition frequencies ranging from 1 kHz to 20 kHz could be demonstrated. At 5 kHz a - to our knowledge - record pulse energy of over 500 µJ could be achieved at 755 nm in TEM00. Furthermore, a stability measurement at an energy of around 350 µJ with 5 kHz showed no degradation over 150 Mega-shots. The influence of the crystal temperature on the laser performance is also investigated, first in continuous-wave and secondly in cavity-dumped Q-switched operation.

Heparin-induced thrombocytopenia: An update for the COVID-19 era.

The increased use of heparin during the current COVID-19 pandemic has highlighted the risk of a rare but potentially serious complication of heparin therapy, viz. heparin-induced thrombocytopenia (HIT). This is a short review on the pharmacology of heparin and its derivatives, and the pathophysiology of HIT. Guidance on laboratory testing for and clinical management of HIT is presented in accordance with international guidelines. There are important similarities and differences between HIT and the new entity of vaccine-induced immune thrombotic thrombocytopenia, also known as thrombosis with thrombocytopenia syndrome, which clinicians need to be aware of.

Recommendations for the diagnosis and management of vaccine-induced immune thrombotic thrombocytopenia.

There have recently been safety concerns regarding an increased risk of vaccine-induced immune thrombotic thrombocytopenia (VITT) following administration of SARS-CoV-2 adenoviral vector vaccines. The Southern African Society of Thrombosis and Haemostasis reviewed the emerging literature on this idiosyncratic complication. A draft document was produced and revised by consensus agreement by a panel of professionals from various specialties. The recommendations were adjudicated by independent international experts to avoid local bias. We present concise, practical guidelines for the clinical management of VITT.

[Migraine with typical aura without headache; first presentation at older age]. / Visuele verschijnselen bij migraine met typisch aura.

Transient visual phenomena in later life due to a visual aura in migraine are not uncommon and can also occur without headache. This migraine with aura is not always recognized as such. Since visual phenomena can also have a variety of other causes, they can present a diagnostic dilemma in both primary and secondary care. Visual aura phenomena have various and often complex manifestations and are usually observed binocularly. In case of transient visual phenomena, the patient's history is of utmost importance to determine whether there is a mono- or binocular cause of the complaints. Timely recognition of visual phenomena in the context of migraine can prevent unnecessary diagnostics and treatments.

Experimental and numerical study of interlock requirements for high-power EYDFAs.

In this work, we studied the interlock requirements in a seed failure scenario for Er3+:Yb3+ doped fiber amplifiers (EYDFAs) pumped with high intensities in the MWcm-2 range at 9XX nm. We fed a time-dependent FEM-tool with the data from backwards directed amplified spontaneous emission (ASE) transients of different commercially available core-pumped single-mode fibers. In the FEM-tool, the Er3+:Yb3+ system is defined as a bi-directional energy transfer process and described by the corresponding rate equations. The power evolution of the pump, seed, and ASE signal is computed by differential equations taking into account the transient population densities of the relevant energy levels. With the model, we computed the temporal evolution of the corresponding energy levels after a seeder failure to take place within tens to hundreds of µs and calculated the associated gain. The fibers under test provide a critical total gain of 30 dB after ∼ 80 µs within the Yb3+ band and after ∼300 µs within the Er3+ band. This time decreases with increasing pump power and doping concentration. The results can be extrapolated to high-power cladding-pumped EYDFAs to meet the challenging requirements of engineering-level systems.

Patient blood management: A solution for South Africa.

For more than 70 years the default therapy for anaemia and blood loss was mostly transfusion. Accumulating evidence demonstrates a significant dose-dependent relationship between transfusion and adverse outcomes. This and other transfusion-related challenges led the way to a new paradigm. Patient blood management (PBM) is the application of evidence-based practices to optimise patient outcomes by managing and preserving the patient's own blood. 'Real-world' studies have shown that PBM improves patient outcomes and saves money. The prevalence of anaemia in adult South Africans is 31% in females and 17% in males. Improving the management of anaemia will firstly improve public health, secondly relieve the pressure on the blood supply, and thirdly improve the productivity of the nation's workforce. While high-income countries are increasingly implementing PBM, many middle- and low-income countries are still trying to upscale their transfusion services. The implementation of PBM will improve South Africa's health status while saving costs.

Gain dynamics in Raman fiber lasers and passive pump-to-Stokes RIN suppression.

We report on theoretical and experimental investigations of gain dynamics in Raman fiber lasers in the frequency range of 1 Hz-1 MHz. An analytical solution of the problem is due to the nonlinear nature of the Raman effect not feasible. Thus, we used a numerical simulation to gain general insights. Experimentally and numerically obtained results for a Raman fiber laser emitting at 1180 nm show good qualitative agreement. We also present a potential physical interpretation of the observed dynamical properties. In addition, we report on an experimental proof-of-principle of a passive pump-to-Stokes RIN suppression scheme for the main Stokes order in cascaded Raman fiber lasers utilizing an additional parasitic Stokes order. Again, results from numerical and experimental studies of a cascaded Raman fiber laser at 1180 nm and 1240 nm show good agreement and confirm the passive pump-to-Stokes RIN suppression at 1180 nm. The dependencies between the resonator design and the parameters of the noise suppression are investigated. In addition, it is shown that the scheme can also be applied to cascaded Raman fiber lasers with more then two Stokes shifts. This opens the possibility to design for example low-noise Raman fiber lasers at 1480 nm to pump low-noise Er(3+) doped fiber amplifiers.

Gain dynamics in Er(3+):Yb(+) co-doped fiber amplifiers.

Understanding the gain dynamics of fiber amplifiers is essential for the implementation and active stabilization of low noise amplifiers or for coherent beam combining schemes. The gain dynamics of purely Er3+ or Yb3+ doped fiber amplifiers are well studied, whereas no analysis for co-doped systems, especially for Er3+:Yb3+ co-doped fiber amplifiers has been performed, so far. Here, we analyze for the first time the gain dynamics of Er3+:Yb3+ co-doped fiber amplifiers theoretically and experimentally. It is shown that due to the energy transfer between the Yb3+ and Er3+ ions a full analytical solution is not possible. Thus, we used numerical simulations to gain further insights. Comparison of experimental and numerical results shows good qualitative agreement. In addition, we were able to determine the Yb3+-Er3+ transfer function of the energy transfer experimentally.

Co-seeded Er3+:Yb3+ single frequency fiber amplifier with 60 W output power and over 90% TEM(00) content.

We report on the design and fabrication of an Er(3+):Yb(3+) triple clad fiber and on the power scaling of a single frequency fiber amplifier at 1.5 µm based on that fiber. In addition, we report on mode content measurements in order to reveal the overlap of the amplifier output with the TEM(00) mode. The triple clad design was used to enable high output power levels, a good slope efficiency and an excellent beam quality. A maximum single frequency output power of 61 W at 1.5 µm could be achieved with the aid of the co-seeding method, which was used to suppress parasitic processes at 1.0 µm. With a scanning ring cavity the mode content of the amplifier output was analyzed with respect to the TEM modes. For all output power levels the TEM(00) content was above 90%.

Venous thromboembolism: prophylactic and therapeutic practice guideline.

BACKGROUND: Pharmacological prophylactic anticoagulation in many countries, including South Africa, is under-prescribed. This has resulted in unacceptable rates of morbidity and mortality. METHOD: The Southern African Society of Thrombosis and Haemostasis held a meeting to update the previous guideline and review new literature including guidelines from other societies. The following specialties were represented on the committees: anaesthetics, cardiology, clinical haematology, critical care, obstetrics and gynaecology, haematopathology, internal medicine, neurology, orthopaedic surgery and pulmonology. A draft document was presented at the meeting, which was then revised by consensus agreement. To avoid local bias, the guideline was adjudicated by recognised international external experts. RESULTS AND CONCLUSION: A concise, practical updated guideline for thromboprophylaxis and treatment in medical and surgical patients has been produced for South African conditions. It is hoped that this guideline will continue to improve anticoagulation practice in this country, which we believe will directly benefit patient outcomes.

Stabilized high-power laser system for the gravitational wave detector advanced LIGO.

An ultra-stable, high-power cw Nd:YAG laser system, developed for the ground-based gravitational wave detector Advanced LIGO (Laser Interferometer Gravitational-Wave Observatory), was comprehensively characterized. Laser power, frequency, beam pointing and beam quality were simultaneously stabilized using different active and passive schemes. The output beam, the performance of the stabilization, and the cross-coupling between different stabilization feedback control loops were characterized and found to fulfill most design requirements. The employed stabilization schemes and the achieved performance are of relevance to many high-precision optical experiments.

Venous thromboembolism--prophylactic and therapeutic practice guideline.

BACKGROUND: Pharmacological prophylactic anticoagulation in many countries, including South Africa, is under-prescribed, which unfortunately results in unacceptable morbidity and mortality in a substantial number of patients. METHOD: The Southern African Society of Thrombosis and Haemostasis reviewed the available literature as well as guidelines from other societies. Specialties represented on the committees included anaesthetics, cardiology, clinical haematology, critical care, gynaecology, haematopathology, internal medicine, neurology, orthopaedic surgery, pulmonology and vascular surgery. A draft document was produced, which was revised by consensus agreement. To avoid local bias, the guidelines were adjudicated by recognised independent international external experts. RESULTS AND CONCLUSION. A concise, practical guideline for thrombo-prophylaxis and treatment in medical and surgical patients has been produced for South African conditions. These guidelines will hopefully lead to improved anticoagulation practice in this country, which we believe will directly benefit patient outcomes.

[Summary of the practice guideline 'Thyroid disorders' (first revision) from the Dutch College of General Practitioners]. / Samenvatting van de standaard 'Schildklieraandoeningen' (eerste herziening) van het Nederlands Huisartsen Genootschap.

--The practice guideline 'Thyroid disorders' developed by the Dutch College of General Practitioners replaces the practice guideline 'Functional thyroid disorders' from 1996. Recommendations for palpable thyroid disorders have been added. --Hypothyroidism can often be treated by the general practitioner. The guideline offers specific recommendations for substitution therapy based on the 'start low, go slow'-principle. --Pharmacological treatment of hyperthyroidism is described as an optional activity for general practitioners. --A conservative approach is taken to the treatment of subclinical thyroid dysfunction. The development of symptoms may justify treatment initiation. --Cooperation has improved harmonisation of this practice guideline with the Netherlands Association for Internal Medicine's practice guideline 'Functional thyroid disorders' and the Dutch Institute for Healthcare Improvement's practice guideline 'Thyroid carcinomas'.

[Cerebral infarction due to polycythaemia as the initial manifestation of renal cell carcinoma]. / Herseninfarct door polycytemie als eerste uiting van een niercelcarcinoom.

A 65-year-old man with known diabetes mellitus and hypertension (cardiovascular risk factors) presented to the Emergency Clinic with a transient language disorder and motor- and cognitive-function disorders that had been present for the past half a year. Brain imaging revealed multiple white-matter lesions and a recent infarction. Routine blood tests revealed polycythaemia. Further tests revealed an elevated erythropoietin level and bilateral renal tumours. The cognitive functions improved after repeated phlebotomies and surgical resection of the renal-cell carcinomas. Before surgery, transcranial ultrasound had shown very low cerebral flow velocities, which became normal after correction of the haematocrit. This case emphasises the importance of routine blood tests in patients with suspected cerebral infarction. To our knowledge, this is the first case of cerebral infarction as the first manifestation ofa renal-cell carcinoma.

Is there a reentrant glass in binary mixtures?

By employing computer simulations for a model binary mixture, we show that a reentrant glass transition upon adding a second component occurs only if the ratio alpha of the short-time mobilities between the glass-forming component and the additive is sufficiently small. For alpha approximately 1, there is no reentrant glass, even if the size asymmetry between the two components is large, in accordance with the two-component mode-coupling theory. For alpha<<1, on the other hand, the reentrant glass is observed and reproduced only by an effective one-component mode-coupling theory.

Structure elucidation of 11-amino-8-hydroxypentacyclo[5.4.0.0(2, 6).0(3, 10).0(5, 9)]undecane-8,11-lactam through selective acetylation and complete 1H and 13C NMR spectral assignment of the mono-, di- and triacetates.

NMR techniques cannot unambiguously distinguish between 11-amino-8-hydroxypentacyclo[5.4.0.0(2, 6).0(3, 10).0(5, 9)]undecane-8,11-lactam and 8-amino-11-hydroxypentacyclo[5.4.0.0(2, 6).0(3, 10).0(5, 9)]undecane-8,11-lactam, both of which are possible products during the reaction of pentacyclo[5.4.0.0(2, 6).0(3, 10).0(5, 9)]undecane-8,11-dione with Strecker reagents. Treatment of 11-amino-8-hydroxy-pentacyclo[5.4.0.0(2, 6).0(3, 10).0(5, 9)]undecane-8,11-lactam with acetic anhydride at room temperature produced a monoacetate. With acetic anhydride containing sodium acetate, a triacetate was obtained at reflux temperature. Treatment with acetyl chloride and N,N-dimethylaniline produced a diacetate. High-field 1H and 13C NMR techniques were used in the structure elucidation and assignment of the different NMR resonances of these three acetylated compounds.

Uterine artery embolization for symptomatic fibroids.

OBJECTIVES: The aim of this study was to introduce uterine artery embolization (UAE) as an effective and safe treatment option in patients with symptomatic fibroids. METHODS: Sixty-one patients underwent UAE with a 3- and 12-month follow-up. RESULTS: The procedure was well tolerated in all patients with the following symptoms improving: heavy bleeding [90% (95% CI 80.21%; 95.4%)]; dysmenorrhea [median -4 (95% CI -5; -4)]; feeling of a mass [74% (95% CI 57.9%; 85.8%)]; abdomino-pelvic discomfort [88% (95% CI 75.5%; 94.9%)]; and deep dyspareunia [90% (95% CI 71.1%; 97.3%)]. Uterine volume decreased by a median difference of 188 cm(3) (95% CI 146.5; 236), which related to a median % reduction of 37.7% (95% CI 32.4%; 45%) at 12-month follow-up. Most (91%) patients were satisfied with the procedure and only minor complications occurred. CONCLUSIONS: Uterine artery embolization can be performed effectively and safely at centers with the necessary expertise and can be used with success in Africa.

Uterine artery embolisation for symptomatic fibroids: the effect of the large uterus on outcome.

OBJECTIVE: The aim of this study was to evaluate the efficacy of uterine artery embolisation (UAE) in myomatous uteri larger than 24 week's gestation (780 cm3). DESIGN: Prospective case control study. SETTING: Universitas Hospital, University of the Free State, Bloemfontein, South Africa. POPULATION: Sixty-one women, who underwent UAE, were included in the study. The study group comprised of 12 women with uteri > or =780 cm3 and the control group 49 women with uteri <780 cm3. METHODS: UAE was performed and the difference in outcome for the two groups was determined at 12 months. MAIN OUTCOME MEASURE: Symptomatic improvement with embolisation of the large uterus. RESULTS: Reduction of dysmenorrhoea, menorrhagia and pressure effects was similar for both groups. The median reduction in uterine volume (pre- to post-embolisation) was 188 cm3 (range 28-2038 cm3) with a 95% CI for the median difference for paired data of 146.5 and 236. Only 66% of the study group had, however, a reduction in volume to <780 cm3. The complication rates were similar for the two groups with regards to post-embolisation syndrome, fibroid slough, haematoma formation, infection, hysterectomy and failure to embolise. Satisfaction was similar between the two groups, with 91% of women satisfied with the procedure. CONCLUSION: The large uterus does not decrease UAE's efficacy. Although 33.3% of the study group still had a uterus of > or =780 cm3, symptom reduction was still similar for both groups. Women may thus still be left with a large uterine volume but without symptoms. This must be taken into consideration when counselling women with an extremely large uterus for UAE.

Novel suppression scheme for Brillouin scattering.

We demonstrate a new scheme for the efficient suppression of Brillouin scattering of a single-frequency laser source in a 72 m-long Neodymium-doped fiber amplifier by simultaneous amplification of two seed lasers separated in wavelength by two times the Brillouin-shift. This scheme can be independently employed in addition to conventional methods of suppressing stimulated Brillouin scattering enabling further power scaling of existing systems.