Chromaticity in all-reflective telescopes for astrometry

Chromatic effects are usually associated with refractive optics, so reflective telescopes are assumed to be free from them. We show that all-reflective optics still bears significant levels of such perturbations, which is especially critical to modern micro-arcsecond astrometric experiments. We analyze the image formation and measurement process to derive a precise definition of the chromatic variation of the image position, and we evaluate the key aspects of optical design with respect to chromaticity. The fundamental requirement related to chromaticity is the symmetry of the optical design and of the wavefront errors. Finally, we address some optical engineering issues, such as manufacturing and alignment, providing recommendations to minimize the degradation that chromaticity introduces into astrometry.Comment: 10 pages, 8 figure

An Easily Constructed, Tuning Free, Ultra-broadband Probe for NMR

We have developed an easy to construct, non-resonant wideband NMR probe. The probe is of the saddle coil geometry and is designed such that the coil itself forms a transmission line. The probe thus requires no tuning or matching elements. We use the probe with a spectrometer whose duplexer circuitry employs a simple RF switch instead of the more common lambda/4 lines, so the entire probe and spectrometer perform in an essentially frequency-independent manner. Despite being designed with electro- and magnetostatic formulas, the probe performs well at frequencies up to 150 MHz and beyond. We expect that with additional design effort, the probe could be modified for use at significantly higher frequencies. Because our construction method relies on commercial circuit fabrication techniques, identical probes can be easily and accurately produced

Healthcare-associated infections and antibiotic use in long-term care residents from two geographical regions in Switzerland.

The burden of healthcare-associated infections (HAIs) and antimicrobial use in Swiss long-term care facilities (LTCFs) is currently unknown. This study assessed the prevalence of HAIs and antibiotic use among LTCF residents in Switzerland. A point-prevalence study was undertaken in LTCFs in eastern and western Switzerland from August to October 2019 according to the 'Healthcare-associated infections in long-term care facilities' (HALT) protocol. Characteristics of residents (age, sex, wounds, dementia, indwelling catheters) and institutions (specific factors, geographic region) were assessed. LTCF residents were screened for HAIs and current antibiotic treatment. Personal and institutional factors associated with HAIs were assessed. In total, 1185 residents from 16 LTCFs (eight per geographic region) were screened for HAIs and antibiotic treatment. Median age was 87 years (interquartile range 79-91) and 71% were female. The prevalence of HAIs was 4.2% (west 4.3% vs east 4.2%; P=0.93), with mucocutaneous skin infections (36%) and respiratory tract infections (30%) being the most common. Independent risk factors for the presence of HAIs were presence of a chronic wound [odds ratio (OR) 2.4, 95% confidence interval (CI) 1.1-5.0; P=0.02] and being immobile (OR 1.8, 95% CI 1.0-3.3; P=0.04). Antibiotics were given to 2.9% of residents (west 3.9% vs east 1.8%; P=0.05) on the day of the survey. The most commonly prescribed antibiotics were amoxicillin-clavulanic acid and quinolones. The prevalence of HAIs in Swiss LTCFs is similar to that in other European countries, whereas antibiotic consumption is lower. Further point-prevalence surveys on a broader scale are recommended to improve understanding of the burden of HAIs and antibiotic consumption in this setting

Long-term heliomagnetic field variation based on cosmogenic 44Ti in meteorites

Reconstructions of the heliospheric magnetic field (HMF) in the past centuries are mainly based on the analysis of sunspot activity, geomagnetic data or on measurement of cosmogenic radioisotopes stored in terrestrial reservoirs (tree rings and ice cores). There are, however, significant discrepancies among the results obtained by various techniques using different proxies of solar magnetic activity. In this work, new results obtained from a unique approach based on the measurement of the cosmogenic 44Ti activity detected in meteorites are presented and compared with the most recent reconstructions of the near-Earth HMF strength. The very low level of 44Ti activity in several meteorites fallen in the last 250 years was determined by using gamma-ray spectrometers (HPGe+NaI) located in the underground laboratory of Monte dei Cappuccini (INAF-OATo) in Torino, Italy. This approach, specifically designed to overcome the main problems affecting other methods, yields a powerful independent tool to reconstruct the long-term evolution of the HMF through the last two and a half centuries

Adapting response to a measles outbreak in a context of high vaccination and breakthrough cases: an example from Vaud, Switzerland, January to March 2024.

A measles outbreak with 51 cases occurred in the canton of Vaud, Switzerland, between January and March 2024. The outbreak was triggered by an imported case, and 37 (72.5%) subsequent cases were previously vaccinated individuals. Epidemiological investigations showed that vaccinated measles cases were symptomatic and infectious. In a highly vaccinated population, it is important to raise awareness among healthcare professionals to suspect and test for measles virus when an outbreak is declared, irrespective of the vaccination status of the patients