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Broadband, high-power mid-infrared (mid-IR) sources are critical for many applications. Compared to alternatives such as fluorides and chalcogenides, tellurite fibers are more robust and can handle much higher power. Tellurite fibers also have high nonlinearity and a material zero dispersion close to 2 µm, making them ideal for nonlinear processes pumped by Tm-doped silica fiber lasers. In this work, we have demonstrated solid tellurite fibers fabricated by a stack-and-draw process and investigated their potential for broadband mid-IR supercontinuum generation. We have identified that fibers with low dispersion are beneficial and that low residual hydroxyl (OH) is critical for broadband mid-IR supercontinuum generation in tellurite fibers pumped at ~2 µm.

Searches for extrasolar planets using the periodic Doppler shift of stellar spectral lines have recently achieved a precision of 60 cm s(-1) (ref. 1), which is sufficient to find a 5-Earth-mass planet in a Mercury-like orbit around a Sun-like star. To find a 1-Earth-mass planet in an Earth-like orbit, a precision of approximately 5 cm s(-1) is necessary. The combination of a laser frequency comb with a Fabry-Pérot filtering cavity has been suggested as a promising approach to achieve such Doppler shift resolution via improved spectrograph wavelength calibration, with recent encouraging results. Here we report the fabrication of such a filtered laser comb with up to 40-GHz (approximately 1-A) line spacing, generated from a 1-GHz repetition-rate source, without compromising long-term stability, reproducibility or spectral resolution. This wide-line-spacing comb, or 'astro-comb', is well matched to the resolving power of high-resolution astrophysical spectrographs. The astro-comb should allow a precision as high as 1 cm s(-1) in astronomical radial velocity measurements.

Searches for extrasolar planets using the periodic Doppler shift of stellar spectral lines have recently achieved a precision of 60 cm s super(-1), which is sufficient to find a 5-Earth-mass planet in a Mercury-like orbit around a Sun-like star. To find a 1-Earth-mass planet in an Earth-like orbit, a precision of approx5 cm s super(-1) is necessary. The combination of a laser frequency comb with a Fabry-Perot filtering cavity has been suggested as a promising approach to achieve such Doppler shift resolution via improved spectrograph wavelength calibration, with recent encouraging results. Here we report the fabrication of such a filtered laser comb with up to 40-GHz (approx1-Aa) line spacing, generated from a 1-GHz repetition-rate source, without compromising long-term stability, reproducibility or spectral resolution. This wide-line-spacing comb, or 'astro-comb', is well matched to the resolving power of high-resolution astrophysical spectrographs. The astro-comb should allow a precision as high as 1 cm s super(-1) in astronomical radial velocity measurements.

Combing the sky for 'earths' The current count of extrasolar planets (on planetquest.jpl.nasa.gov) stands at 277, none of them Earth-like. Most were detected as a Doppler shift in stellar spectral lines, a method that 'sees' planets down to about five times the mass of the Earth. If Earth-sized planets are to be revealed by this observational approach, better Doppler shift resolution via improved spectrograph wavelength calibration will be required. A newly developed instrument, the 'astro-comb', achieves just that by adapting the laser frequency comb, a device that has revolutionized laboratory spectroscopy, to the needs of astrophysics. This involves reducing the density of comb lines, without compromising spectral resolution. A performance test of the astro-comb is reported in this issue, and in May 2008, the new device joins the search for 'exoearths' in earnest. Searches for extrasolar planets using the periodic Doppler shift of stellar spectral lines have recently achieved a precision of 60 cm s −1 , sufficient to find a 5-Earth-mass planet in a Mercury-like orbit around a Sun-like star. The fabrication of an 'astro-comb' that should allow a precision as high as 1 cm s −1 in astronomical radial velocity measurements is reported Searches for extrasolar planets using the periodic Doppler shift of stellar spectral lines have recently achieved a precision of 60 cm s -1 (ref. 1 ), which is sufficient to find a 5-Earth-mass planet in a Mercury-like orbit around a Sun-like star. To find a 1-Earth-mass planet in an Earth-like orbit, a precision of ∼5 cm s -1 is necessary. The combination of a laser frequency comb with a Fabry–Pérot filtering cavity has been suggested as a promising approach to achieve such Doppler shift resolution via improved spectrograph wavelength calibration 2 , 3 , 4 , with recent encouraging results 5 . Here we report the fabrication of such a filtered laser comb with up to 40-GHz (∼1-Å) line spacing, generated from a 1-GHz repetition-rate source, without compromising long-term stability, reproducibility or spectral resolution. This wide-line-spacing comb, or ‘astro-comb’, is well matched to the resolving power of high-resolution astrophysical spectrographs. The astro-comb should allow a precision as high as 1 cm s -1 in astronomical radial velocity measurements.

Searches for extrasolar planets using the periodic Doppler shift of stellar spectral lines have recently achieved a precision of 60 cm/s (ref 1), which is sufficient to find a 5-Earth-mass planet in a Mercury-like orbit around a Sun-like star. To find a 1-Earth-mass planet in an Earthlike orbit, a precision of 5 cm/s is necessary. The combination of a laser frequency comb with a Fabry-Perot filtering cavity has been suggested as a promising approach to achieve such Doppler shift resolution via improved spectrograph wavelength calibration, with recent encouraging results. Here we report the fabrication of such a filtered laser comb with up to 40- GHz (1-A) line spacing, generated from a 1- GHz repetition-rate source, without compromising long-term stability, reproducibility or spectral resolution. This wide-line-spacing comb, or `astro-comb', is well matched to the resolving power of high-resolution astrophysical spectrographs. The astro-comb should allow a precision as high as 1 cm/s in astronomical radial velocity measurements.

A second degree of freedom-the so-called carrier-envelope-offset frequency (f^sub ceo^), which determines the absolute position of the comb in the frequency space-can be easily measured when the laser spectrum covers one optical octave (such that/and 2/frequency components are present in the spectrum).2 Technical considerations The ideal reference is actually a frequency comb that matches the instrument functions of the spectrograph with a resolving power from about 103 to 105, corresponding to mode spacing from 5 to 400 GHz. Gigahertz astro-comb technology To create the first astro-comb based on a filtered laser-frequency comb, researchers from the Harvard-Smithsonian Center for Astrophysics (CFA; Cambridge, MA) and the Massachusetts Institute of Technology (MIT; Cambidge, MA) used a 1 GHz octave-spanning Tirsapphire laser developed at MIT to demonstrate a 40 GHz astro-comb by external filtering with a Fabry-Perot filter.5,6 The octave-spanning 1 GHz laser has been commercialized by Menlo Systems (Newton, NJ); one of those lasers will be used as a calibration source in Doppler spectral exoplanetary exploration at the Multiple Mirror Technology (MMT) telescope in the Fred Lawrence Whipple Observatory on Mount Hopkins (Amado, AZ).

Background: Second victim phenomena (SVP) are critical to workplace and patient safety, and epidemiological data are limited to investigate the causes and impact on German health care. We investigated SVP in German nurses regarding prevalence, causes, and predisposition compared to a preceding study on German physicians (Second Victims in Deutschland/SeViD-I). Methods: We conducted a nationwide anonymous cross-sectional online study in 2020 using a modified SeViD questionnaire including the BFI-10 (personality traits). Statistical analysis was conducted using chi² tests and binary logistic regression models. Results: Of 332 nurses, 60% reported to experience SVP at least once a working lifetime, with a 12-month prevalence among SVP of 49%. Of the nurses, 24% reported recovery times of more than 1 year. In contrast to physicians from SeViD-I, a main cause for becoming a second victim was aggressive behavior by patients. High neuroticism values, higher age, and medium work life experience, but neither gender nor workplace position, were predisposing for SVP. Like SeViD-I, nurses reported demand for an institutional response in cases of SVP. Conclusions: SVP is common among German nurses and comprises other causes and a different course than in physicians. Further research should concentrate on specific prevention strategies, e.g., profession- and workplace-based educational programs.

Immunization with Plasmodium falciparum (Pf) sporozoites under chemoprophylaxis (PfSPZ-CVac) is the most efficacious approach to malaria vaccination. Implementation is hampered by a complex chemoprophylaxis regimen and missing evidence for efficacy against heterologous infection. We report the results of a double-blinded, randomized, placebo-controlled trial of a simplified, condensed immunization regimen in malaria-naive volunteers (EudraCT-Nr: 2018-004523-36). Participants are immunized by direct venous inoculation of 1.1 × 10 5 aseptic, purified, cryopreserved PfSPZ (PfSPZ Challenge) of the PfNF54 strain or normal saline (placebo) on days 1, 6 and 29, with simultaneous oral administration of 10 mg/kg chloroquine base. Primary endpoints are vaccine efficacy tested by controlled human malaria infection (CHMI) using the highly divergent, heterologous strain Pf7G8 and safety. Twelve weeks following immunization, 10/13 participants in the vaccine group are sterilely protected against heterologous CHMI, while (5/5) participants receiving placebo develop parasitemia (risk difference: 77%, p = 0.004, Boschloo’s test). Immunization is well tolerated with self-limiting grade 1–2 headaches, pyrexia and fatigue that diminish with each vaccination. Immunization induces 18-fold higher anti-Pf circumsporozoite protein (PfCSP) antibody levels in protected than in unprotected vaccinees (p = 0.028). In addition anti-PfMSP2 antibodies are strongly protection-associated by protein microarray assessment. This PfSPZ-CVac regimen is highly efficacious, simple, safe, well tolerated and highly immunogenic. In this placebo-controlled trial, 10/13 malaria naïve subjects immunized with a simplified regimen of chemoattenuated P. falciparum sporozoites, PfSPZ-CVac, show sterile protection from heterologous malaria challenge. Immunization was well tolerated and induced high levels of anti-PfCSP antibodies.

The pandemic caused by SARS-CoV-2 resulted in increasing demands for diagnostic tests, leading to a shortage of recommended testing materials and reagents. This study reports on the performance of self-sampled alternative swabbing material (ordinary Q-tips tested against flocked swab and rayon swab), of reagents for classical RNA extraction (phenol/guanidine-based protocol against a commercial kit), and of intercalating dye-based one-step quantitative reverse transcription real-time PCRs (RT-qPCR) compared against the gold standard hydrolysis probe-based assays for SARS-CoV-2 detection. The study found sampling with Q-tips, RNA extraction with classical protocol and intercalating dye-based RT-qPCR as a reliable and comparably sensitive strategy for detection of SARS-CoV-2—particularly valuable in the current period with a resurgent and dramatic increase in SARS-CoV-2 infections and growing shortage of diagnostic materials especially for regions limited in resources.