For multi-scale differential equations (or fast–slow equations), one often encounters problems in which a key system parameter slowly passes through a bifurcation. In this article, we show that a pair of prototypical reaction–diffusion equations in two space dimensions can exhibit delayed Hopf bifurcations. Solutions that approach attracting/stable states before the instantaneous Hopf point stay near these states for long, spatially dependent times after these states have become repelling/unstable. We use the complex Ginzburg–Landau equation and the Brusselator models as prototypes. We show that there exist two-dimensional spatio-temporal buffer surfaces and memory surfaces in the three-dimensional space-time. We derive asymptotic formulas for them for the complex Ginzburg–Landau equation and show numerically that they exist also for the Brusselator model. At each point in the domain, these surfaces determine how long the delay in the loss of stability lasts, that is, to leading order when the spatially dependent onset of the post-Hopf oscillations occurs. Also, the onset of the oscillations in these partial differential equations is a hard onset.

We assessed the validity of serum total anti-nucleoprotein Immunoglobulin (N-antibodies) to identify SARS-CoV-2 (re)infections by estimating the persistence of N-antibody seropositivity and boosting following infection. From a prospective Dutch cohort study (VASCO), we included adult participants with ≥2 consecutive self-collected serum samples, 4–8 months apart, between May 2021–May 2023. Sample pairs were stratified by N-seropositivity of the first sample and by self-reported infection within the sampling interval. We calculated the proportions of participants with N-seroconversion and fold-increase (1.5, 2, 3, 4) of N-antibody concentration over time since infection and explored determinants. We included 67,632 sample pairs. Pairs with a seronegative first sample (70%) showed 89% N-seroconversion after reported infection and 11% when no infection was reported. In pairs with a seropositive first sample (30%), 82%–65% showed a 1.5- to 4-fold increase with a reported reinfection, and 19%–10% without a reported reinfection, respectively. After one year, 83% remained N-seropositive post-first infection and 93%–61% showed a 1.5-fold to 4-fold increase post-reinfection. Odds for seroconversion/fold increase were higher for symptomatic infections and Omicron infections. In the current era with limited antigen or PCR testing, N-serology can be validly used to detect SARS-CoV-2 (re)infections at least up to a year after infection, supporting the monitoring of COVID-19 burden and vaccine effectiveness.

A Bayesian approach for simultaneous optimization of test-based decisions is presented using the example of a selection decision for a treatment followed by a mastery decision. A distinction is made between weak and strong rules where, as opposed to strong rules, weak rules use prior test scores as collateral data. Conditions for monotonicity of optimal weak and strong rules are presented. It is shown that under mild conditions on the test score distributions and utility functions, weak rules are always compensatory by nature.

This article presents the preliminary results of investigations at the site of Qach Rresh on the Erbil Plain of the Kurdistan Region of Iraq, conducted by the Rural Landscapes of Iron Age Imperial Mesopotamia project (RLIIM). The site of Qach Rresh is estimated to have been founded in the mid–eighth century B.C.E., at the height of the Assyrian Empire, and continued to be utilised in varying capacity until the onset of the Hellenistic period (c. 320 B.C.E.). Magnetic gradiometry survey and excavations currently suggest that Qach Rresh served as a rural administrative/storage center during the Assyrian Empire, which fell into disrepair following the empire’s collapse. The following post-Assyrian/Iron Age III period then saw several of its large buildings repurposed as refuse areas containing debris from largely domestic contexts. Qach Rresh is the first rural settlement investigated within the Assyrian imperial heartland. The results from this project seem to indicate a high degree of Assyrian state or elite involvement in the countryside, serving as a critical first foray into assessing the relationship between urban governing centers and their “hinterlands”.

Hybrid yoghurts combining dairy and plant-based derivatives present a novel approach to enhancing consumer acceptance of plant-based products, which is increasingly significant due to dietary trends and lactose intolerance. This study investigates the production of hybrid yoghurt blending cow's milk (CM) with soy (C:S) and oat (C:O) drinks in various ratios (90%, 70%, and 50% cow's milk), assessing their acceptability and quality. Notably, the C:S (70:30) and C:O (70:30) ratios resulted improved viscosity over time, although still less than CM. The hybrid yoghurts exhibited a favourable pH gradient, enhancing the acidic environment critical for flavour. Sensory analysis revealed that C:O (70:30) offered more favourable attributes on the just-about-right scale, scoring overall 6.86/10. Importantly, microbial analysis confirmed the safety of all hybrid products for consumption, with no harmful microorganisms detected.

In recent years, there has been significant momentum in applying deep learning (DL) to machine health monitoring (MHM). It has been widely claimed that DL methodologies are superior to more traditional techniques in this area. This paper aims to investigate this claim by analysing a real-world dataset of helicopter sensor faults provided by Airbus. Specifically, we will address the problem of machine sensor health unsupervised classification. In a 2019 worldwide competition hosted by Airbus, Fujitsu Systems Europe (FSE) won first prize by achieving an F1-score of 93% using a DL model based on generative adversarial networks (GAN). In another comprehensive study, various modified and existing image encoding methods were compared for the convolutional auto-encoder (CAE) model. The best classification result was achieved using the scalogram as the image encoding method, with an F1-score of 91%. In this paper, we use these two studies as benchmarks to compare with basic statistical analysis methods and the one-class supporting vector machine (SVM). Our comparative study demonstrates that while DL-based techniques have great potential, they are not always superior to traditional methods. We therefore recommend that all future published studies of applying DL methods to MHM include appropriately selected traditional reference methods, wherever possible.

Bacterial survival on, and interactions with, human skin may explain the epidemiological success of MRSA strains. We evaluated the bacterial counts for 27 epidemic and 31 sporadic MRSA strains on 3D epidermal models based on N/TERT cells (NEMs) after 1, 2 and 8 days. In addition, the expression of antimicrobial peptides (hBD-2, RNase 7), inflammatory cytokines (IL-1β, IL-6) and chemokine IL-8 by NEMs was assessed using immunoassays and the expression of 43 S. aureus virulence factors was determined by a multiplex competitive Luminex assay. To explore donor variation, bacterial counts for five epidemic and seven sporadic MRSA strains were determined on 3D primary keratinocyte models (LEMs) from three human donors. Bacterial survival was comparable on NEMs between the two groups, but on LEMs, sporadic strains showed significantly lower survival numbers compared to epidemic strains. Both groups triggered the expression of immune factors. Upon interaction with NEMs, only the epidemic MRSA strains expressed pore-forming toxins, including alpha-hemolysin (Hla), gamma-hemolysin (HlgB), Panton-Valentine leucocidin (LukS) and LukED. Together, these data indicate that the outcome of the interaction between MRSA and human skin mimics, depends on the unique combination of bacterial strain and host factors.

Background: Alzheimer’s disease, Parkinson’s disease, and Huntington’s disease are neurodegenerative disorders characterized by progressive structural and functional loss of specific neuronal populations, protein aggregation, insidious adult onset, and chronic progression. Modeling these diseases in animal models is useful for studying the relationship between neuronal dysfunction and abnormal behaviours and for screening therapies. Methods: We conducted a comprehensive descriptive review of the numerous animal models currently available to study these three diseases with a focus on their utilities and limitations. Results: A vast range of genetic and toxin-induced models have been generated. Our review outlines how these models differ with regards to the genetic manipulation or toxin used and the brain regions lesioned, describes the extent to which they mimic the neuropathological and behavioral deficits seen in the human conditions, and discusses the advantages and drawbacks of each model. Conclusions: We recommend the adoption of a conservative approach when extrapolating findings based on a single animal model and the validation of findings using multiple models. Investing in additional preclinical studies before embarking on more expensive human trials will improve our understanding of the neuropathology underlying neuronal demise and enhance the chances of identifying effective therapies.

With an annual growth in travel demand of about 5% globally, managing the environmental impact is a challenge. In 2019, the International Civil Aviation Organisation (ICAO) issued emission reduction targets, including well-to-wake greenhouse gas (GHG) emissions reduced at least 50% from 2005 levels by 2050. This discusses several technologies from an aircraft design perspective that can contribute to achieving these targets. One thing is certain: aircraft will look different in the future. The Transonic Truss-Braced Wing and Flying V configurations are promising significant efficiency improvements over conventional configurations. Electric propulsion, in various architectures, is becoming a feasible option for general aviation and commuter aircraft. It will be a growing field of aviation with zero-emissions flight and opportunities for special missions. Lastly, this paper discusses methods and design processes that include all relevant disciplines to ensure that the aircraft is optimised as a complete system. While empirical methods are essential for initial design, Multidisciplinary Design Optimisation (MDO) incorporates models and simulations integrated in an optimisation environment to capture critical trade-offs. Concurrent design places domain experts in one site to facilitate collaboration, interaction, and joint decision-making, and to ensure all disciplines are equally considered. It is supported by a Collaborative Design Facility (CDF), an information technology facility with connected hardware and software tools for design analysis.

Background: In the Erasmus MC University Medical Center, Rotterdam, the Netherlands, patients considered at risk for carrying highly resistant microorganisms (HRMO) are placed in isolation on admission, until tested negative for HRMO (ie, targeted screening). Patients without risk factors are not routinely screened (ie, nontargeted screening). However, nontargeted screening could identify patients colonized with HRMO missed by targeted screening. To determine the additional value of nontargeted screening, we compared the outcomes of the nontargeted screening approach with all available clinical cultures. Objective: We aim to identify patients colonized with HRMO, but missed by targeted screening, and to determine whether non-targeted screening has additional value. Methods: For the MOVE study, nontargeted admission and discharge cultures (nose and perianal) were obtained from randomly selected patients admitted to specific wards, regardless of HRMO risk factors. This study was part of a research initiative to identify the relation of a contaminated environment with the risk of becoming infected or colonized on a patient level. All bacteriological clinical samples positive for at least 1 HRMO from January 1, 2018, until August 31, 2019, were compared with the nontargeted screening samples. Samples were screened for methicillin-susceptible Staphylococcus aureus (MSSA) and methicillin-resistant Staphylococcus aureus (MRSA) as well as highly resistant Pseudomonas aeruginosa, Acinetobacter baumannii, Enterococcus faecium, and Enterobacteriales. Broth enrichment was used for all cultures. Results: During the study period, 50,653 patients were admitted. 706 patients (1%) had a clinical sample positive for at least 1 HRMO during their hospital stay. 936 (1.8%) patients were included in the nontargeted screening for the MOVE study, and 40 patients were found to have at least 1 culture positive for HRMO (4.3%). Among these 40 patients, 28 were positive at admission and 12 were positive at discharge. Extended-spectrum β-lactamase (ESBL)–producing Enterobacteriales were most prevalent (n = 36, 90.0%) both at admission and discharge (n = 26 and n = 10, respectively). At admission, 1 patient was identified with MRSA and 1 patient was positive for vancomycin-resistant E. faecium (VRE). At discharge, 1 patient was identified with VRE and 1 had Verona Integron-encoded Metallo-β-lactamase (VIM)–positive P. aeruginosa. Conclusions: Our results show that the current targeted screening does not identify all HRMO carriers. Furthermore, patients who acquire an HRMO during admission are missed. The nontargeted screening identified 40 unknown carriers (4.3%). The limitations of the study are the restricted number of sample sites and the fact that we were unable to culture all patients. Therefore, it is likely that our study shows an underestimation of the true number of patients with HRMO.

Funding: None

Disclosures: None

Background: Studies have shown that patients colonized with highly resistant microorganisms (HRMO) contaminate the hospital environment, and that transmission from contaminated environments to patients occurs. In May 2018, the Erasmus MC University Medical Center, Rotterdam, moved from a hospital with mostly multiple-occupancy rooms to a new hospital with 100% single-patient rooms with private bathrooms. This move provided the unique opportunity to determine environmental contamination before the new hospital was open for admissions and thereafter and to compare the environmental contamination to the number of patients colonized with HRMO. Method: Environmental sampling took place twice in the old building and 12 times in the new building, from 2 weeks before to 15 months after relocating patients. At each moment, ~306 samples were taken from 13 locations (eg, nightstands, sinks) in 40 patient rooms. Samples were screened for Staphylococcus aureus (methicillin-susceptible [MSSA] and methicillin resistant [MRSA]) and highly resistant Pseudomonas aeruginosa, Acinetobacter baumannii, Enterococcus faecium, and Enterobacteriales. During the study period, January 1, 2018, until August 31, 2019, all clinical samples positive for HRMO were included. Results: Environmental sampling revealed that 29 of 724 (4.0%) locations were positive for HRMO in the old building, whereas 4 of 3,358 (0.1%) samples in the new building were positive for HRMO (P < .001). In the old building, 14 of 29 locations were positive for extended-spectrum β-lactamase (ESBL)–producing bacteria and 15 were positive for carbapenemase-producing bacteria. In the new building, 3 of 4 positive samples were positive for vancomycin-resistant E. faecium (VRE), 1 was positive for ESBL-producing K. pneumoniae. For both HRMO, no carriers were detected. In the old building, 145 of 12,256 adult patients (1.2%) had clinical samples positive for HRMO, compared to 561 of 38,397 (1.5%) in the new building, a small but significant increase (P = .02). Conclusions: The transition from mainly 2- and 4-person rooms to 100% single-patient rooms resulted in a significant decrease in environmental contamination, even though the number of patients colonized with HRMO slightly increased. No molecular typing to determine transfer from environment to patients and vice versa has yet been performed. Future sampling is needed to determine whether the low environmental contamination is a long-term effect of the transition to single rooms.

Funding: None

Disclosures: None