ALBERT

Description: By introducing two types of zenith troposphere delay (ZTD) products in precise point positioning (PPP), we developed the ZTD-corrected PPP and the ZTD-constrained PPP, both of them reduced the PPP convergence time. Both enhanced PPP methods are examined by global empirical ZTD models and regional ZTD corrections. For global ZTD models, we verified that ZTD-corrected PPP will deviate the positioning results, while ZTD-constrained PPP could produce unbiased estimations. Therefore, the latter is utilized to study the performance of global ZTD models (ITG, GPT2w, GZTD and UNB3m). After numerous experiments, we found that the performance of ZTD models was positively related to the real ZTD accuracy, and we proposed a universal tropospheric stochastic model 2SQR(9rms) which denotes double the square of nine times ZTD rms, to constrain ZTD in PPP. The proposed model subsequently was validated by real-time static and kinematic ZTD-constrained PPP on the premise that the ZTD rms on every station was known. Compared with traditional PPP, in static PPP, the number of improved stations is increased by 15.5 per cent (ITG), 14.4 per cent (GPT2w), 11.1 per cent (GZTD) and 8.3 per cent (UNB3m). For kinematic PPP, PPP constrained by ITG model still had the best performance, the number of improved stations is increased by 14.4 per cent, after 30 min of initialization time, 13.4 cm east, 13.4 cm north and 11.7 cm up positioning accuracy was obtained, compared with 15.3 cm east, 15.3 cm north and 14.3 cm up accuracy by traditional PPP. In addition, experiments using regional ZTD corrections to enhance real-time PPP showed that both ZTD-corrected PPP and ZTD-constrained PPP can notably reduce the convergence time on the vertical component (within 15 cm).

Description: Infectious diseases are potential catalysts for exploring ‘engaged citizen’ or socioscientific themes given their interwoven economic, political, scientific and social dimensions. This article describes how an undergraduate course on the history of infectious diseases was modified to explore the impact of two ‘engaged citizen’ themes (poverty and technology), and to consider the ramifications of those themes on past, present and future infectious disease outbreaks. Four outbreaks were used as the foundation for the course: plague (1350s), puerperal fever (1840s), cholera (1850s) and syphilis (1930s). The first part of the article describes the general course structure and the role of university-wide ‘engaged citizen’ themes in its semester-specific construction. The second part of the article demonstrates how poverty and technology ‘threads’ were explored in each of the four historical contexts, and subsequently how they were considered in current and future contexts; appendices with lesson suggestions are provided. The third and final part of the article discusses how this specific model might be more broadly applied to other microbiology instructional contexts.

Description: We study fluctuations in the degree-2 zonal spherical harmonic coefficient of the Earth's gravity potential, C 20 , over the period 2003–2015. This coefficient is related to the Earth's oblateness and studying its temporal variations, C 20 , can be used to monitor large-scale mass movements between high and low latitude regions. We examine C 20 inferred from six different sources, including satellite laser ranging (SLR), GRACE and global geophysical fluids models. We further include estimates that we derive from measured variations in the length-of-day (LOD), from the inversion of global crustal displacements as measured by GPS, as well as from the combination of GRACE and the output of an ocean model as described by Sun et al. We apply a sequence of trend and seasonal moving average filters to the different time-series in order to decompose them into an interannual, a seasonal and an intraseasonal component. We then perform a comparison analysis for each component, and we further estimate the noise level contained in the different series using an extended version of the three-cornered-hat method. For the seasonal component, we generally obtain a very good agreement between the different sources, and except for the LOD-derived series, we find that over 90 per cent of the variance in the seasonal components can be explained by the sum of an annual and semiannual oscillation of constant amplitudes and phases, indicating that the seasonal pattern is stable over the considered time period. High consistency between the different estimates is also observed for the intraseasonal component, except for the solution from GRACE, which is known to be affected by a strong tide-like alias with a period of about 161 d. Estimated interannual components from the different sources are generally in agreement with each other, although estimates from GRACE and LOD present some discrepancies. Slight deviations are further observed for the estimate from the geophysical models, likely to be related to the omission of polar ice and groundwater changes in the model combination we use. On the other hand, these processes do not seem to play an important role at seasonal and shorter timescales, as the sum of modelled atmospheric, oceanic and hydrological effects effectively explains the observed C 20 variations at those scales. We generally obtain very good results for the solution from SLR, and we confirm that this well-established technique accurately tracks changes in C 20 . Good agreement is further observed for the estimate from the GPS inversion, showing that this indirect method is successful in capturing fluctuations in C 20 on scales ranging from intra- to interannual. Obtaining accurate estimates from LOD, however, remains a challenging task and more reliable models of atmospheric wind fields are needed in order to obtain high-quality C 20 , in particular at the seasonal scale. The combination of GRACE data and the output of an ocean model appears to be a promising approach, particularly since corresponding C 20 is not affected by tide-like aliases, and generally gives better results than the solution from GRACE, which still seems to be of rather poor quality.

Description: With the alarming rise of antibiotic resistance, clinical professionals are called upon to manage antibiotic therapies using the most relevant and recent clinical and laboratory data. To this end, antimicrobial stewardship (AMS) programs aim to reduce unnecessary or suboptimal use of antibiotics while maximizing outcomes for the patient. For AMS programs to succeed, the active participation of clinical professionals at all levels of patient care is required. Although programs exist to train established clinicians in AMS, there is a paucity of literature on how and when to integrate AMS concepts and skills in pre-clinical and clinical coursework. Here, we discuss the crucial microbiology concepts and proficiencies that are necessary for building and supporting an AMS program. We provide recommendations for key points to include in clinical curricula in order to develop the necessary microbiology interpretation skills to participate in AMS. The influence of AMS programs on local organism susceptibility patterns is emphasized. The importance of antibiograms, rapid diagnostic testing and the practical interpretations of microbiology laboratory reporting are discussed in regard to prioritization in clinical curricula. We also review the current literature on instructional strategies for introducing AMS into clinical programs, and propose concepts that should be included in didactic coursework in order to provide a foundation for AMS education.