We describe a large SARS-CoV-2 outbreak involving an acute care hospital emergency department during December 2020 and January 2021, in which 27 healthcare personnel worked while infectious, resulting in multiple opportunities for SARS-CoV-2 transmission to patients and other healthcare personnel. We provide recommendations for improving infection prevention and control.

Let $a,b$ and n be positive integers and let $S=\{x_1, \ldots , x_n\}$ be a set of n distinct positive integers. For ${x\in S}$ , define $G_{S}(x)=\{d\in S: d<x, \,d\mid x \ \mathrm {and} \ (d\mid y\mid x, y\in S)\Rightarrow y\in \{d,x\}\}$ . Denote by $[S^a]$ the $n\times n$ matrix having the ath power of the least common multiple of $x_i$ and $x_j$ as its $(i,j)$ -entry. We show that the bth power matrix $[S^b]$ is divisible by the ath power matrix $[S^a]$ if $a\mid b$ and S is gcd closed (that is, $\gcd (x_i, x_j)\in S$ for all integers i and j with $1\le i, j\le n$ ) and $\max _{x\in S} \{|G_S (x)|\}=1$ . This confirms a conjecture of Shaofang Hong [‘Divisibility properties of power GCD matrices and power LCM matrices’, Linear Algebra Appl.428 (2008), 1001–1008].

Under global warming, many glaciers worldwide are receding. However, recent studies have suggested the extension of the Karakoram Anomaly, a region of anomalous glacier mass gain, into the western Kunlun and eastern Pamir mountains. However, the eastern limit of this anomaly in the Kunlun Mountains is unclear. This study, using changes in glacier area and surface elevation, estimates the eastern limit of the Kunlun-Pamir-Karakoram anomaly at ~85°E. Over the past 50 years, glaciers west of 85°E in the Kunlun Mountains decreased in area from 8401 to 7945 km2 at a rate of −0.12 ± 0.07% a−1, showed a reduction in the rate of retreat through time and have recently gained mass, with surface elevation changes of 0.15 ± 0.35 m a−1 over the period of 2000–2013. Glaciers east of 85°E have experienced greater rates of area change (−61 ± 12 km2 and −0.43 ± 0.13% a−1) over the past 50 years, accelerated area loss in recent years and elevation change rate of −0.51 ± 0.18 m a−1 between 2000 and 2013. These patterns of elevation and area change are consistent with regional increases in summer temperature in the eastern Kunlun Mountains and slight cooling in the western Kunlun Mountains.

Violent respiratory events play critical roles in the transmission of respiratory diseases, such as coughing and sneezing, between infectious and susceptible individuals. In this work, large-scale multiphase flow large-eddy simulations have been performed to simulate the coughing jet from a human's mouth carrying pathogenic or virus-laden droplets by using a weakly compressible smoothed particle hydrodynamics method. We explicitly model the cough jet ejected from a human mouth in the form of a mixture of two-phase fluids based on the cough velocity profile of the exhalation flow obtained from experimental data and the statistics of the droplets’ sizes. The coupling and interaction between the two expiratory phases and ambient surrounding air are examined based on the interaction between the gas particles and droplet particles. First, the results reveal that the turbulence of the cough jet determines the dispersion of the virus-laden droplets, i.e. whether they fly up evolving into aerosols or fall down to the ground. Second, the droplet particles have significant effects on the evolution of the cough jet turbulence; for example, they increase the complexity and butterfly effect introduced by the turbulence disturbance. Our results show that the prediction of the spreading distance of droplet particles often goes beyond the social distancing rules recommended by the World Health Organization, which reminds us of the risks of exposure if we do not take any protecting protocol.

HMGR, 3-hydroxy-3-methylglutaryl-CoA reductase, is a major rate-limiting enzyme in mevalonate (MVA) pathway for isoprenoids and subsequent tanshinone biosynthesis in the Chinese traditional bulk herbal medicine Danshen, Salvia miltiorrhiza, mainly for cardiovascular disorders. In this paper, the genomic SmHMGR genes of 38 cultivated populations of S. miltiorrhiza collected in China were for the first time sequenced to reveal the genetic diversity and phylogeny. The SmHMGR gene was shown to be intron-free, 1650~1659 bp in complete CDS with the majority being 1656 bp, and two unique populations (W-FJLY-V-1 and W-SCHY-W-1) being 1659 and 1650 bp respectively. A total of 103 SNP variation sites were detected with a variation rate of 6.22%, most of which occurred in S. miltiorrhiza f. alba population W-SCHY-W-1; a total of 25 amino acid variation sites were found, of which 19 was in W-SCHY-W-1. The same four populations, W-SCHY-W-1, V-HBAG-V-1, V-JLCC-V-1 and S-NM-V-1 could be discriminated from the remaining 34 by both the SNP fingerprints and the deduced amino acid variation sites. Other or composite DNA markers are needed for better identification. The SmHMGR gene of white flower S. miltiorrhiza f. alba population W-SCHY-W-1 is especially rich in variations and worthy of further studies. Phylogenetic trees based on both the gene and the deduced amino acid sequences showed a very similar two-clade topological structure. This research enriched the content and the genetic means for the molecular identification, genetic diversity and phylogenetic studies of the cultivated S. miltiorrhiza populations, and laid a solid foundation for further related and in-depth investigations.

This study evaluated the association between inflammatory diets as measured by the dietary inflammatory index (DII), and inflammation biomarkers, and the development of preeclampsia among the Chinese population. We followed the reporting guidelines of the STROBE statement for observational studies. A total of 466 preeclampsia cases aged over 18 years were recruited between March 2016 and June 2019, and 466 healthy controls were 1:1 ratio matched by age (± 3 years), week of gestation (± 1 week), and gestational diabetes mellitus. The energy-adjusted DII (E-DII) was computed based on dietary intake assessed using a 79-item semiquantitative food frequency questionnaire (FFQ). Inflammatory biomarkers were analyzed by ELISA kits. The mean E-DII scores were -0.65 ± 1.58 for cases and -1.19 ± 1.47 for controls (P value <0.001). E-DII scores positively correlated with IFN-γ (rs = 0.194, P value = 0.001) and IL-4 (rs = 0.135, P value = 0.021). After multivariable adjustment, E-DII scores were positively related to preeclampsia risk (P trend <0.001). The highest tertile of E-DII was 2.18 times the lowest tertiles (95% CI = 1.52, 3.13). The odds of preeclampsia increased by 30% (95% CI= 18%, 43%, P value <0.001) for each E-DII score increase. The preeclampsia risk was positively associated with IL-2 (OR = 1.07, 95% CI = 1.03, 1.11), IL-4 (OR = 1.26, 95% CI = 1.03, 1.54) and TGF-β (OR = 1.17, 95% CI = 1.06, 1.29). Therefore, proinflammatory diets, corresponding to higher IL-2, IL-4 and TGF-β levels, were associated with increased preeclampsia risk.

This paper presents a new approach to force fighting equalisation in a redundant active-active-active rudder actuation system that is used for the primary flight control system of a turboprop regional aircraft. The related coupled problem of force fighting scenario, and the hydraulic architecture of electronic-hydrostatic actuator (EHA) are analysed, the mathematical model of the EHA system is built. The virtual test bench is designed to evaluate the performance of the force fighting equalisation strategy. The proposed methodology is tested on an iron bird test rig. The physical experiment shows that the fighting force is minimised under all flight conditions, meets the low cost requirement and can be a very reliable system. The proposed methodology can be applied to other types of aircraft’ flight actuation systems.

The realizing of variable output constant force has received wide attention. To achieve a force regulation in an economic way, a configuration of the constant force mechanism (CFM) referring to positive and negative stiffness combination method is proposed in this paper. By adjusting preloading displacement applied on positive-stiffness structure of the CFM, the variable constant force output can be realized. The force–displacement expression of the CFM in the non-preloaded condition is deduced by the established analytical models. Furthermore, parametric sensitivity analysis with several architectural parameters are conducted for optimizing physical structures. Finally, the correctness of the proposed principle is verified by experimental studies. The observed experimental results show that the CFM under different preloading displacements can provide required output constant force, which is consistent with proposed hypothesis.

Background: Emergency departments (EDs) are complex, sociotechnical, high-paced, safety-critical work systems that have been disproportionately affected by the COVID-19 pandemic. Despite training, consistent compliance with recommended PPE use during COVID-19 pandemic has been challenging. Healthcare workers (HCWs) have had adapt to overcome these challenges to ensure their own safety and patient safety. We sought to identify barriers in the work system that impede the recommended COVID-19 PPE use in EDs. Methods: We conducted semistructured, in-depth interviews over ZoomTM from August 2020–May 2021 with 45 HCWs from the ED (ie, physicians, nurses, ancillary support staff, etc) affiliated with a large, tertiary-care, academic medical center. These audio-recorded interviews were transcribed and analyzed using a hybrid (inductive and deductive) qualitative coding approach in NVivo software. The deductive portion was guided by the SEIPS work system model, a well-known human-factors conceptual framework. Results: We identified multiple work-system factors in the ED that impede compliance with the recommended COVID-19 PPE use. In addition, ED HCWs have reported making a variety of adaptations or developing strategies to overcome these barriers. Some of these adaptations were made to the PPE physically (eg, trimming portions of PPE), and others were related to the tasks and/or processes associated with PPE, such as filming their own training video demonstrating PPE donning and doffing techniques, and environment services staff checking a patient’s status with nurses prior to entering the patient’s room when there was no COVID-19 signage on the door. Conclusions: Consistent compliance with COVID-19 PPE use in ED clinical practice is challenging and can be negatively affected by a variety of work system factors. Resilience strategies developed by HCWs can provide critical information with regards to HCW needs and potential directions for innovation. Future efforts should focus on not only changing individual HCW behavior through training but also on improving the PPE and ED work system design.

Funding: US CDC

Disclosures: The authors gratefully acknowledge the US CDC for funding this work. This material is based upon work supported by the Naval Sea Systems Command (under contract no. N00024-13-D-6400, task order NH076). Any opinions, findings, and conclusions or recommendations expressed in this material are those of the authors and do not necessarily reflect the views of the Naval Sea Systems Command (NAVSEA) or the US CDC.

Background: In March–April 2021, 23 patients at a 906-bed hospital in Delaware had surgical implantation of a bone graft product contaminated with Mycobacterium tuberculosis; 17 patients were rehospitalized for surgical site infections and 6 developed pulmonary tuberculosis. In May 2021, we investigated this tuberculosis outbreak and conducted a large, multidisciplinary, contact investigation among healthcare personnel (HCP) and patients potentially exposed over an extended period in multiple departments. Methods: Exposed HCP were those identified by their managers as present, without the use of airborne precautions, in operating rooms (ORs) during index spine surgeries or subsequent procedures, the postanesthesia care unit (PACU) when patients had draining wounds, inpatient rooms when wound care was performed, and the sterile processing department (SPD) on the days repeated surgeries were performed. We created and assigned an online education module and symptom screening questionnaire to exposed HCP. Employee health services (EHS) instituted a dedicated phlebotomy station to provide interferon-γ release assay (IGRA) testing for HCP at ≥8 weeks after last known exposure. EHS managed all exposed HCP, including nonemployees (eg, private surgeons) via automated e-mail reminders, which were escalated through supervisory chains as needed until follow-up completion. The infection prevention team notified exposed patients, defined as those who shared semiprivate rooms with case patients with transmissible tuberculosis. The Delaware Division of Public Health performed IGRA testing. Results: There were 506 exposed HCP in ORs (n = 100), the PACU (n = 87), inpatient units (n = 140), the SPD (n = 54), and other locations (n = 122); 83% were employed by the health system. Surgical masks and eye protection were routinely used during patient care. All exposed HCP completed screening by December 17, 2021. Furthermore, 2 HCP had positive IGRAs without symptoms or chest radiograph abnormalities, indicating latent tuberculosis infection, but after further review of records and interviews, we discovered that they had previously tested positive and had been treated for latent tuberculosis infection. In addition, 5 exposed patients tested negative and 2 remain pending. Conclusions: This large investigation demonstrated the need for a systematic process that encompassed all exposed HCP including nonemployees and incorporated administrative controls to ensure complete follow-up. We did not identify any conversions related to this outbreak despite high burden of disease in case patients and multiple exposures to contaminated bone-graft material and infectious bodily fluids without respirator use. Transmission risk was likely reduced by baseline surgical mask use and rapid institution of airborne precautions after outbreak recognition.

Funding: None

Disclosures: None