ABSTRACT
We report on the generation of GW-class peak power, 35-fs pulses at 2-µm wavelength with an average power of 51 W at 300-kHz repetition rate. A compact, krypton-filled Herriott-type cavity employing metallic mirrors is used for spectral broadening. This multi-pass compression stage enables the efficient post compression of the pulses emitted by an ultrafast coherently combined thulium-doped fiber laser system. The presented results demonstrate an excellent preservation of the input beam quality in combination with a power transmission as high as 80%. These results show that multi-pass cell based post-compression is an attractive alternative to nonlinear spectral broadening in fibers, which is commonly employed for thulium-doped and other mid-infrared ultrafast laser systems. Particularly, the average power scalability and the potential to achieve few-cycle pulse durations make this scheme highly attractive.
ABSTRACT
Bright, coherent soft X-ray radiation is essential to a variety of applications in fundamental research and life sciences. To date, a high photon flux in this spectral region can only be delivered by synchrotrons, free-electron lasers or high-order harmonic generation sources, which are driven by kHz-class repetition rate lasers with very high peak powers. Here, we establish a novel route toward powerful and easy-to-use SXR sources by presenting a compact experiment in which nonlinear pulse self-compression to the few-cycle regime is combined with phase-matched high-order harmonic generation in a single, helium-filled antiresonant hollow-core fibre. This enables the first 100 kHz-class repetition rate, table-top soft X-ray source that delivers an application-relevant flux of 2.8 × 106 photon s-1 eV-1 around 300 eV. The fibre integration of temporal pulse self-compression (leading to the formation of the necessary strong-field waveforms) and pressure-controlled phase matching will allow compact, high-repetition-rate laser technology, including commercially available systems, to drive simple and cost-effective, coherent high-flux soft X-ray sources.
ABSTRACT
BACKGROUND: The hands of medical stuff are the most important vectors for the transmission of pathogens in the hospital. Furthermore a "bare below the elbows dress code" has been introduced in Great Britain. OBJECTIVES: Aim of this study was to investigate whether workwear contamination of the medical stuff by pathogens is similar to the contamination of their hands and whether wearing workwear is associated with increased transmission risk. MATERIAL AND METHODS: In total 54 swabs were collected from nursing stuff, medical doctors, patients and hospital work material. RESULTS: Patients had a statistically significant more dense colonization with bacteria (median = 73 colony-forming units (CFU)), than the sleeves of the doctor's coat (median = 36 CFU, p = 0,005), followed by workwear of the nursing stuff at the end of a shift (median = 23 CFU, p < 0,001) and the hospital work material (median = 15 CFU, p < 0,001). Isolated pathogens were coagulase-negative staphylococci, Staphylococcus aureus, Enterobacter cloacae and Acinetobacter species. CONCLUSIONS: Contaminated work wear presents a relevant risk for the transmission of pathogens. A "bare below the elbow dress-code" or the daily change of the doctor's coat appear both to represent reasonable measures to reduce the transmission risk of pathogens in hospitals.
Subject(s)
Bacteria/isolation & purification , Clothing/statistics & numerical data , Cross Infection/prevention & control , Equipment Contamination/prevention & control , Hand/microbiology , Nursing/statistics & numerical data , Germany , Humans , Physicians/statistics & numerical dataABSTRACT
Type 2 diabetes is associated with an increased risk of cardiac complications. Inhibitors of dipeptidylpeptidase 4 (DPP-4) are novel drugs for the treatment of patients with type 2 diabetes. The effect of DPP-4 inhibitors on myocardial metabolism has not been studied in detail. In wild-type C57Bl6-mice, 3weeks of treatment with sitagliptin had no effect on body weight and glucose tolerance nor on phosphorylation of AMP-activated protein kinase (AMPK) and acetyl-CoAcarboxylase (ACC), phosphofructokinase-2 (PFK2) or tuberin-2 (TSC2) in the left ventricular myocardium. However, in 10week old db/db-/- mice, a model of diabetes and obesity, sitagliptin potently reduced plasma glucose rise in peritoneal glucose tolerance tests and reduced weight increase. The myocardium of untreated db/db-/- mice exhibited a marked increase of the phosphorylation of AMPK, ACC, TSC2, expression of p53 and fatty acid translocase (FAT/CD36) membrane expression. These changes were reduced by DPP-4 inhibition. Sitagliptin showed no effect on cardiomyocyte size but prevented myocardial fibrosis in the 10week old db/db-/- mice and reduced expression of TGF-ß1, markers of oxidative stress and the accumulation of advanced glycation end products in cardiomyocytes. Working heart analyses did not show an effect of sitagliptin on parameters of systolic cardiac function. In animals with diabetes and obesity, sitagliptin improved glucose tolerance, reduced weight gain, myocardial fibrosis and oxidative stress. Furthermore the study provides evidence that treatment with sitagliptin decreases elevated myocardial fatty acid uptake and oxidation in the diabetic heart. These observations show beneficial myocardial metabolic effect of DPP-4 inhibition in this mouse model of diabetes and obesity.
