bluuebunny/crossref_metadata_2025 huggingface dataset:
Combined effect of diameter ratio and spacing ratio on flow around two tandem circular cylinders at a moderate Reynolds number (Re)
Authors: Zhang Di , Qi Yizhen , Liang Dongfang , Liu Yakun , Li Zhuoyue , Ma Jun
Published: August 2024

In order to ascertain the combined effect of diameter ratio (d/D) and spacing ratio (L/D) on the flow around two tandem circular cylinders, a total of 43 research cases are numerically simulated using a large eddy simulation model in this study, including d/D = 0.2 (L/D = 0.80–6.00), d/D = 0.4 (L/D = 0.80–6.00), and d/D = 0.6 (L/D = 0.90–6.00) at Re = 3900. By systematically analyzing the instantaneous/time-averaged spanwise vorticity contours, the three-dimensional time-averaged Q-criterion iso-surfaces, the spanwise periodicity within the gap, and the Strouhal number (St), eight sub-flow regimes can be identified, namely, non-periodic reattachment-(1), small-scale periodic reattachment, large-scale periodic reattachment, non-periodic reattachment-(2), bi-stable flow, intermittent lock-in co-shedding, subharmonic lock-in co-shedding and no lock-in co-shedding. The occurrence of these sub-flow regimes depends on the combination of d/D and L/D. Besides, with regard to the larger downstream cylinder (DC), there are three possible dominant St values for the DC instantaneous drag coefficient (i.e. StCD-D1, StCD-D2, and StCD-D3). It is quite clear that StCD-D1 has almost the same value as StCL-D1, StCD-D2 is roughly equal to 2StCL-D1, and StCD-D3 is approximately the summation of StCL-D1 and StCL-D2, where StCL-D1 and StCL-D2 denote the primary and secondary dominant St values of the DC instantaneous lift coefficient, respectively. Additionally, various flow statistical parameters are obtained and compared for different combinations of d/D and L/D, such as the velocity, vorticity, St value, spanwise periodicity, force coefficient, base pressure coefficient, reattachment angle, and separation angle.
Characterization of corona-induced ionic wind and spark channel formation using high-speed schlieren imaging
Authors: Chen Yanheng , Zhang Yumin , Li Yiheng , Luo Yi , Liu Xiaoming , Pei Xuekai
Published: August 2024

Studying ionic wind is crucial for deepening our comprehension of electrical discharge processes and refining their application in industrial technologies. This research investigates the behavior of needle–needle electrode using high-speed schlieren imaging techniques, focusing on the dynamics of ionic wind and its influence on spark discharge channel formation. Observations indicate that the ionic wind generated during corona discharge provides a structured pathway that significantly guides the development of spark discharge channels, particularly evident in horizontal configurations. Our findings reveal that the velocity and density of the ionic wind increase with decreasing curvature radius of the needle tip, thereby enhancing its guiding effect. Furthermore, the spark discharge channel forms through the convergence of positive and negative streamers, which meet near the cathode, leading to substantial disturbances in the surrounding flow field post-discharge. This research highlights the intricate relationship between corona and spark discharges, demonstrating the critical role of ionic wind in influencing discharge channel morphology and offering insights for future applications in plasma and electrostatic-based technologies.
Environmental temperature influences detectability of a nocturnal marsupial
Authors: Kowalick Gillian N. , Ross Alexandra K. , Crisp Helen A.
Published: August 2024

Mammals have a range of strategies designed to maintain optimal body temperature regardless of environmental temperature. One energy-efficient strategy is to avoid environmental temperature extremes by modifying active periods. Reduced animal activity can result in fewer detections of target species during surveys that require direct observation of individuals. Observations of the greater bilby (Macrotis lagotis) from 8 years of survey data were investigated to determine the impact of environmental temperature and season on bilby detectability. Bilby observations were positively correlated with temperature regardless of season. Wildlife managers should consider minimum environmental temperatures when planning surveys and analysing observational data.
An hetero-modal deep learning framework for medical image synthesis applied to contrast and non-contrast MRI
Authors: Gourdeau Daniel , Duchesne Simon , Archambault Louis
Published: August 2024

Some pathologies such as cancer and dementia require multiple imaging modalities to fully diagnose and assess the extent of the disease. Magnetic resonance imaging offers this kind of polyvalence, but examinations take time and can require contrast agent injection. The flexible synthesis of these imaging sequences based on the available ones for a given patient could help reduce scan times or circumvent the need for contrast agent injection. In this work, we propose a deep learning architecture that can perform the synthesis of all missing imaging sequences from any subset of available images. The network is trained adversarially, with the generator consisting of parallel 3D U-Net encoders and decoders that optimally combines their multi-resolution representations with a fusion operation learned by an attention network trained conjointly with the generator network. We compare our synthesis performance with 3D networks using other types of fusion and a comparable number of trainable parameters, such as the mean/variance fusion. In all synthesis scenarios except one, the synthesis performance of the network using attention-guided fusion was better than the other fusion schemes. We also inspect the encoded representations and the attention network outputs to gain insights into the synthesis process, and uncover desirable behaviors such as prioritization of specific modalities, flexible construction of the representation when important modalities are missing, and modalities being selected in regions where they carry sequence-specific information. This work suggests that a better construction of the latent representation space in hetero-modal networks can be achieved by using an attention network.
Daemonic quantum battery charged by thermalization
Authors: Satriani Matias Araya , Barra Felipe
Published: August 2024

The reduced state of a small system strongly coupled to a charger in thermal equilibrium may be athermal and used as a small battery once disconnected. By harnessing the battery-charger correlations, the battery’s extractable energy can increase above the ergotropy. We introduce a protocol that uses a quantum system as a memory that measures the charger and leaves the battery intact in its charged state. Using the information gained from the measurement, the daemonic ergotropy of the battery is extracted. Then the battery is reconnected to the charger, thermalizing and charging it. However, the memory should return to its initial standard state to close the thermodynamic cycle. Thus, on the one hand, the work cost of the cycle is the sum of the disconnecting and reconnecting battery-charger work plus the measurement and erasure work. On the other hand, the extracted energy is the daemonic ergotropy of the battery plus the ergotropy of the memory. The ratio of these quantities defines the efficiency of the cycle. The protocol is exemplified by a modified transverse spin 1/2 Ising chain, one spin functioning as the battery and the others as the charger. The memory is another auxiliary spin 1/2. We found pairs of measurement schemes from which we extract the same daemonic ergotropy from the battery, they dissipate the same amount of energy, and one leaves the memory in an active state, the other in a passive state. We study the memory’s ergotropy and the daemonic ergotropy of the battery. We find that with measurements, the efficiency can surpass that of the unmeasured protocol, given conditions on temperature, coupling, and choice of the measurement operators.
Future projections of storm surge in Hurricane Katrina and sensitivity to meteorological forcing resolution
Authors: Danso Derrick K , Patricola Christina M
Published: August 2024

In this study, we investigated whether and how the storm surge induced by Hurricane Katrina could change if it occurs in a future warmer climate, and the sensitivity of the changes to atmospheric forcing resolution. Climate model simulations of Hurricane Katrina at 27 km, 4.5 km, and 3 km resolutions were used to drive storm surge simulations in historical and future climates using the ADvanced CIRCulation (ADCIRC) model. We found that peak surge height increased significantly in the future with all forcing resolutions. However, the future projection is 22% greater in the 3 km forcing, typical of regional climate models, compared to the 27 km forcing, typical of state-of-the-art global climate models. Additionally, the spatial extent of the future change is highly sensitive to forcing resolution, extending most broadly under the 27 km forcing. Furthermore, we found that storm surge duration decreases in the future with all forcing resolutions due to increasing TC translation speed and decreasing ocean lifetime. However, the future change in the surge duration is sensitive to the forcing resolution, decreasing by 31% in the 27 km forcing and 6% in the 3 km forcing.
Heater power supply fluctuations in metal oxide gas sensors: impact on gas sensing performance
Authors: Saidi Tarik , Manser Abderrazak , Welearegay Tesfalem
Published: August 2024

This work reports the impact of deviations in heater current caused by an imprecise 5V power source on the parameters utilized in gas sensing modules in MQ series towards 62 ppm of Ethanol vapor. The gas sensing experiments involved three MQ series gas sensors under lab-made chamber for continuous Ethanol vapor measurement. To investigate how heaters’ current irregularities, affect the gas sensing performance parameters, the sensor’s response/recovery time, pattern recognition techniques of principal component analysis (PCA) and hierarchical cluster analysis (HCA) were employed. While minor voltage drops (±100 mV) may not significantly affect sensing resistance (RS) due to real-time input voltage (Vin) adjustment, a constant current source is essential for heating resistance (RH). The study revealed that a slight increase (±3 mA) in heater supply, particularly from 154 mA (94 °C) to 157 mA (96 °C), can significantly accelerate the recovery time (Trec) of the MQ-7 sensor from 484 s to 316 s, resulting in a difference of over 150 s. This improvement can be attributed to the desorption of gas molecules at higher temperatures, aiding in sensor cleaning. However, this small change does not significantly affect the response time (Tres), which remains between 245 and 295 s at worst. Our gas sensor exhibits enhanced sensitivity and operational stability thanks to a calibrated circuit and stable 5V power supply. Strong correlations between normalized response and sensing films’ temperatures, with a correlation coefficient of 0.985, provide insights into the relationship between heater currents, temperature effects, and gas sensitivity. These findings offer insights for optimizing sensing performance under gas exposure conditions.
Expected decrease for derivative-free algorithms using random subspaces
Authors: Hare Warren , Roberts Lindon , Royer Clément
Published: August 2024

Derivative-free algorithms seek the minimum of a given function based only on function values queried at appropriate points. Although these methods are widely used in practice, their performance is known to worsen as the problem dimension increases. Recent advances in developing randomized derivative-free techniques have tackled this issue by working in low-dimensional subspaces that are drawn at random in an iterative fashion. The connection between the dimension of these random subspaces and the algorithmic guarantees has yet to be fully understood.

In this paper, we develop an analysis for derivative-free algorithms (both direct-search and model-based approaches) employing random subspaces. Our results leverage linear local approximations of smooth functions to obtain understanding of the expected decrease achieved per function evaluation. Although the quantities of interest involve multidimensional integrals with no closed-form expression, a relative comparison for different subspace dimensions suggest that low dimension is preferable. Numerical computation of the quantities of interest confirm the benefit of operating in low-dimensional subspaces.
Distinguishing C*-algebras by their unitary groups
Authors: Fogang Takoutsing Lionel , Robert Leonel
Published: August 2024

We obtain partial affirmative answers to the question of whether the isomorphism of the unitary groups of two C*-algebras, either as topological groups or as discrete groups, implies the isomorphism of the C*-algebras as real C*-algebras.
Catullus in Twentieth-Century Music
Authors: Oade Stephanie
Published: August 2024

Catullus in Twentieth-Century Music works within the overlap of music and poetry in order to explore the particular lyric voice of Catullus in the context of his twentieth-century musical reception. It considers some of the difficulties inherent in ideas of lyric and lyricism, both specifically in relation to Catullus and more broadly in generic terms. It then uses works of musical reception—settings of Catullus’s poetry from the twentieth century—to clearly identify the essence of Catullan lyricism. Moreover, by considering the very process of reception, it takes a broader view of lyric, identifying traits and characteristics that are common to both music and poetry, thus transcending the boundaries of individual art forms in order to consider the genre in larger, interdisciplinary terms.
Instability in Catullus 3 and Rawsthorne’s Lament for a Sparrow
Authors: Oade Stephanie
Published: August 2024

This chapter continues the study of Catullan reception in song. Through close structural analysis of Catullus poem 3 and Alan Rawsthorne’s song Lament for a Sparrow, developed through a study of voice and tone, the chapter considers both the potential for maintaining lyric traits (such as communality and subjectivity) during the process of reception and the opportunities for appropriation, (re-)interpretation, mediation, dialogism, and generic complication brought about by musical voicing and performance. The chapter also develops the concept of das Gleitende by considering the incremental changes that occur within Catullus’s original text, as well as the ways in which Rawsthorne heightens the effect of these changes in his music.
MetDecode: methylation-based deconvolution of cell-free DNA for noninvasive multi-cancer typing
Authors: Passemiers Antoine , Tuveri Stefania , Sudhakaran Dhanya , Jatsenko Tatjana , Laga Tina , Punie Kevin , Hatse Sigrid , Tejpar Sabine , Coosemans An , Van Nieuwenhuysen Els , Timmerman Dirk , Floris Giuseppe , Van Rompuy Anne-Sophie , Sagaert Xavier , Testa Antonia , Ficherova Daniela , Raimondi Daniele , Amant Frederic , Lenaerts Liesbeth , Moreau Yves , Vermeesch Joris R
Published: August 2024

Motivation

Circulating-cell free DNA (cfDNA) is widely explored as a noninvasive biomarker for cancer screening and diagnosis. The ability to decode the cells of origin in cfDNA would provide biological insights into pathophysiological mechanisms, aiding in cancer characterization and directing clinical management and follow-up.

Results

We developed a DNA methylation signature-based deconvolution algorithm, MetDecode, for cancer tissue origin identification. We built a reference atlas exploiting de novo and published whole-genome methylation sequencing data for colorectal, breast, ovarian, and cervical cancer, and blood-cell-derived entities. MetDecode models the contributors absent in the atlas with methylation patterns learnt on-the-fly from the input cfDNA methylation profiles. In addition, our model accounts for the coverage of each marker region to alleviate potential sources of noise. In-silico experiments showed a limit of detection down to 2.88% of tumor tissue contribution in cfDNA. MetDecode produced Pearson correlation coefficients above 0.95 and outperformed other methods in simulations (P < 0.001; T-test; one-sided). In plasma cfDNA profiles from cancer patients, MetDecode assigned the correct tissue-of-origin in 84.2% of cases. In conclusion, MetDecode can unravel alterations in the cfDNA pool components by accurately estimating the contribution of multiple tissues, while supplied with an imperfect reference atlas.

Availability and implementation

MetDecode is available at https://github.com/JorisVermeeschLab/MetDecode.
Global synthesis indicates widespread occurrence of shifting baseline syndrome
Authors: Soga Masashi , Gaston Kevin J
Published: August 2024

As environmental degradation continues at local, regional, and global levels, people's accepted norms for natural environmental conditions are likely to decline. This phenomenon, known as shifting baseline syndrome (SBS), is increasingly recognized as a likely major obstacle to addressing global environmental challenges. However, the prevalence of SBS remains uncertain. We conducted an extensive systematic review, synthesizing existing research on people's perceived environmental baselines. Our analysis, based on 73 case studies, suggests that SBS is a widespread global phenomenon, occurring across diverse socioeconomic, environmental, and cultural settings. We observed that younger individuals tend to hold lower environmental baselines across various environmental contexts, including climate change, natural resource depletion, biodiversity loss, and pollution. An upward shift in perceived environmental baselines among younger generations was rarely observed. These results underscore the challenge that SBS poses when policy and management responses to environmental degradation are influenced by perceived natural environmental norms.
Outcome analysis of the surgical team in open surgical repair of intact abdominal aortic aneurysm surgery
Authors: Piffaretti Gabriele , Zammito Alessandro , Guzzetti Luca , Selmo Gabriele , Binda Simone , D’Onofrio Dunia , Tozzi Matteo , Franchin Marco
Published: August 2024

OBJECTIVES

To analyze how the experience of the surgical team went to impact the outcomes after open surgical repair (OSR) of intact abdominal aortic aneurysms (AAAs).

METHODS

This is a single-center, observational cohort study with retrospective analysis of all OR for intact AAA performed between 1 January 2010 and 31 December 2022. The primary outcome was survival at 30 days and in follow-up, and a composite outcome of mortality and major complication. The secondary outcome was freedom from aorta-related reintervention. All outcomes were stratified according to the experience of the operating team (surgeons and anesthesiology).

RESULTS

We analyzed 103 (7.2%) patients: 97 (94.2%) males and 6 (5.8%) females. The mean age was 76 ± 8 years (range, 55–93). The best possible team composition was present in 52 (50.5%) interventions. The follow-up index was 0.82 ± 0.18 (range, 0.6–1.0). Mean follow-up duration was 59 ± 43 months (range, 0–158). We observed no differences between teams in major complications (best, 17.3% vs mixed, 21.6%; OR: 0.4, P = 0.622), 30 days mortality (best, 0% vs mixed, 5.9%; OR: 7.6, P = 0.118) and composite outcome (best, 11.5% vs mixed, 17.6%; OR: 0.8, P = 0.416). Cox regression analysis identified the best possible team as a protective factor against the need for reintervention (hazard ratio: 0.2; 95% confidence interval: 0.06–0.88, P = 0.032).

CONCLUSIONS

In our experience, OR of AAA yielded satisfactory results in terms of safety and efficacy independently of the team’s experience. A more experienced team may protect against aorta-related reintervention.
Spectral variation and pigmentary basis of ornamental and mimetic wing colour patches of swallowtail butterflies
Authors: Dharmaraaj Bhavya , Venkatesan Radhika , Kunte Krushnamegh
Published: August 2024

Colours and colour patterns are diverse traits that are often used as visual signals. To test ecological and evolutionary drivers of these visual signals, a clear understanding of their nature and variation is necessary. Here we characterize variation in wing coloration of mormon swallowtail butterflies (Papilio, subgenus Menelaides). These species exhibit two kinds of colour patches on black wings: creamy white/yellow/green patches that are presumably used as sexual ornaments, and pure white patches that are presumably used as mimetic signals. Using reflectance spectrophotometry we quantified spectral properties of black wing background and colour patches between sexes, wing surfaces, and mimicry status. We found that brightness and saturation of the black background were less variable across sexes, wing surfaces, and mimetic/nonmimetic status. However, colour contrast and saturation were higher on dorsal surfaces than on ventral surfaces, and colour contrast between the black background and colour patches was higher in males than in females. Colour patches in nonmimetic butterflies were brighter and more saturated across the whole colour spectrum compared to mimetic butterflies. Thus, our study characterizes colour variation in an extraordinary signal radiation on the wings of swallowtail butterflies, a model clade in ecology, evolution, and genetics. Our results generate numerous hypotheses about the ecological and sexual functions of these colour patches, which may guide further behavioural experiments. Finally, using liquid chromatography-mass spectrometry we identified the pigment papiliochrome-II to be the chemical basis of the presumed sexual ornaments in mormon swallowtails.
Dissecting negative effects of two root-associated bacteria on the growth of an invasive weed
Authors: Liu Xiangyu , Fernandes Hocelayne Paulino , Ossowicki Adam , Vrieling Klaas , Lommen Suzanne T E , Bezemer Thiemo Martijn
Published: August 2024

Plant-associated microorganisms can negatively influence plant growth, which makes them potential biocontrol agents for weeds. Two Gammaproteobacteria, Serratia plymuthica and Pseudomonas brassicacearum, isolated from roots of Jacobaea vulgaris, an invasive weed, negatively affect its root growth. We examined whether the effects of S. plymuthica and P. brassicacearum on J. vulgaris through root inoculation are concentration-dependent and investigated if these effects were mediated by metabolites in bacterial suspensions. We also tested whether the two bacteria negatively affected seed germination and seedling growth through volatile emissions. Lastly, we investigated the host specificity of these two bacteria on nine other plant species. Both bacteria significantly reduced J. vulgaris root growth after root inoculation, with S. plymuthica showing a concentration-dependent pattern in vitro. The cell-free supernatants of both bacteria did not affect J. vulgaris root growth. Both bacteria inhibited J. vulgaris seed germination and seedling growth via volatiles, displaying distinct volatile profiles. However, these negative effects were not specific to J. vulgaris. Both bacteria negatively affect J. vulgaris through root inoculation via the activity of bacterial cells, while also producing volatiles that hinder J. vulgaris germination and seedling growth. However, their negative effects extend to other plant species, limiting their potential for weed control.
Factors Associated With Intended Utilization of Home-Based Long-Term Care Among Older Adults in China: The Moderating Effect of Community Support
Authors: Che Run-Ping , Cheung Mei-Chun
Published: August 2024

Objectives

Guided by Andersen’s behavioral model, the objectives of this study were to (a) examine the associations between individual factors and the intended utilization of home-based long-term care (LTC) services among older adults in China and (b) explore the influence of community support, if any, on these associations.

Methods

Using a multistage random sampling approach, we recruited 1,064 older adults in Chengdu, China. Hierarchical regression was employed to investigate the direct effects of individual predictors and community support on the intended use of home-based LTC services. The moderating effect of community support was examined using the Hayes Process.

Results

Two predisposing (i.e., being old and unmarried), 4 enabling (i.e., living alone, having fewer children, and receiving less family and peer support), and 6 need factors (i.e., having more chronic illnesses; decreased performance in instrumental activities of daily living; higher levels of depression, anxiety, loneliness; and a lower self-image of aging), and low community support were significantly associated with increased intended utilization of home-based LTC. In addition, community support moderated the effects of family support (B = −0.20, p < .001), peer support (B = −0.20, p < .001), self-image of aging (B = −0.39, p < .001), depression (B = −0.34, p < .001), and loneliness (B = −0.48, p < .001) on the intended utilization of home-based LTC services.

Discussion

Policy-makers and practitioners should consider delivering tailored services for older adults and involve the community in the context of enhancing home-based LTC services.
The Spatiotemporal properties of afterslip following the 2016 Kaikoura earthquake in New Zealand from GPS observations: Its complementary and inherited patterns with coseismic slip
Authors: Zhang Lupeng , Meng Guojie , She Yawen
Published: August 2024

The Mw 7.8 Kaikoura earthquake, which occurred on November 13, 2016, ruptured a complex system of strike-slip and reverse faults in northeastern South Island, New Zealand. However, the postseismic afterslip behavior and its relationship to the coseismic slip remain incompletely understood. This study investigates the spatiotemporal characteristics of afterslip following the mainshock by using four years of position data from 58 continuous GPS (cGPS) stations, considering the viscoelastic relaxation. Meanwhile, this study considers the contributions of crustal and the interface faults when exploring the combined effect of afterslip and viscoelastic relaxation. Results reveal substantial coseismic deformation northeastern of the epicenter, and postseismic displacements exhibit a continuation of the northeastward evolution. The primary coseismic slip occurred along the Kekerengu and Jordan Thrust faults, while secondary slip was accommodated by the Humps fault and the shallow subduction interface. Two primary afterslip zones are identified: one extending downdip from the secondary coseismic slip areas, and the other adjacent to shallow primary coseismic slip areas near the seismogenic Needles and Hope faults. The afterslip distribution exhibits a spatially complementary pattern to the coseismic slip areas, suggesting that velocity-strengthening zones may have hindered coseismic rupture propagation. The total seismic moment released by afterslip is estimated at ∼2.51×1020 N·m (Mw ∼7.53), approximately 30% of the coseismic moment. Meanwhile, about 80% of the postseismic seismic moment is ascribed to the slip along the southern subduction interface, suggesting the subduction fault plays an important role during postseismic slip. Temporal evolution modeling highlights that roughly 55% of the total afterslip moment was released within the initial three months. Postseismic afterslip dominated during the first month following the earthquake, with a slip rate of ∼10 mm/day. This rate subsequently decreased to ∼5 mm/day over the following two to three months, indicating that the majority of postseismic afterslip occurred shortly after the mainshock. In contrast to the earlier afterslip stages, the latter stages show continued movement along the Needles fault and the subduction interface. Cumulative peak slips have reached 2 cm since mid-2018, with fault slip rates decreasing to approximately 0.6-1.0 mm/day. This indicates ongoing afterslip at shallow faults and the subduction interface, with a steady slip rate over time. Importantly, the cumulative Coulomb stress changes induced by both coseismic slip and afterslip have increased the earthquake hazards potential near the Wellington fault, a densely populated region warranting further investigation.
Plesio-geostrophy for Earth’s core – II: thermal equations and onset of convection
Authors: Maffei Stefano , Jackson Andrew , Livermore Philip W
Published: August 2024

The columnar-flow approximation allows the development of computationally efficient numerical models tailored to the study of the rapidly rotating dynamics of Earth’s fluid outer core. In this paper, we extend a novel columnar-flow formulation, called Plesio-Geostrophy (PG) by including thermal effects and viscous boundary conditions. The effect of both no-slip and stress-free boundaries, the latter being a novelty for columnar-flow models, are included. We obtain a set of fully 2-D evolution equations for fluid flows and temperature where no assumption is made regarding the geometry of the latter, except in the derivation of an approximate thermal diffusion operator. To test the new PG implementation, we calculated the critical parameters for onset of thermal convection in a spherical domain. We found that the PG model prediction is in better agreement with unapproximated, 3-D calculations in rapidly rotating regimes, compared to another state-of-the-art columnar-flow model.
C-C Motif Ligand 7 and C-C Motif Chemokine Receptor 3 Dysregulation in Patients With Scrub Typhus and Association With Mortality
Authors: Ueland Thor , Astrup Elisabeth , Otterdal Kari , Lekva Tove , Janardhanan Jeshina , Michelsen Annika E , Aukrust Pål , Varghese George M , Damås Jan K
Published: August 2024

Background

Scrub typhus, caused by Orientia tsutsugamushi, involves infiltration of a mixture of perivascular lymphocytes and macrophages into affected organs. We investigated if this is characterized by chemokine dysregulation.

Methods

mRNA expression of chemokines and receptors was screened in whole blood by cDNA microarray in a subgroup of patients and controls. Regulated transcripts were analyzed in plasma by enzyme immunoassays (chemokines) and in whole blood by quantitative polymerase chain reaction (receptors) from patients with scrub typhus (n = 129), patients with similar febrile illness without O tsutsugamushi infection (n = 31), and healthy controls (n = 31).

Results

cDNA microarray identified dysregulation of the chemokines CCL18 and CCL23 and the receptor CCR3 in severe scrub typhus. Plasma CCL7 (a ligand for CCR3), CCL18, and CCL23 were higher in patients with scrub typhus, with a decline during follow-up. Conversely, mRNA levels of CCR3 and CCR8 (the receptor for CCL18) were decreased in whole blood at hospital admission, followed by an increase during follow-up. CCL7 was independently associated with disease severity. Admission CCL7 levels were associated with short-time mortality.

Conclusions

Our findings suggest that CCL7 could represent a hitherto unknown pathogenic mediator in O tsutsugamushi infection, contributing to local and systemic inflammation.
Respiratory Viral Infections From 2015 to 2022 in the HIVE Cohort of American Households: Incidence, Illness Characteristics, and Seasonality
Authors: Monto Arnold S , Foster-Tucker Joshua E , Callear Amy P , Leis Aleda M , Godonou Elie-Tino , Smith Matthew , Truscon Rachel , Johnson Emileigh , Thomas Lara J , Thompson Mark S , Fry Alicia M , Flannery Brendan , Malosh Ryan E , Petrie Joshua G , Lauring Adam S , Martin Emily T
Published: August 2024

Background

Viral respiratory illnesses are the most common acute illnesses experienced and generally follow a predicted pattern over time. The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic interrupted that pattern.

Methods

The HIVE (Household Influenza Vaccine Evaluation) study was established in 2010 to follow a cohort of Southeast Michigan households over time. Initially focused on influenza, surveillance was expanded to include other major respiratory pathogens, and, starting in 2015, the population was followed year round. Symptoms of acute illness were reported, and respiratory specimens were collected and tested to identify viral infections. Based on the known population being followed, virus-specific incidence was calculated.

Results

From 2015 to 2022, 1755 participants were followed in HIVE for 7785 person-years with 7833 illnesses documented. Before the pandemic, rhinovirus (RV) and common cold human coronaviruses (HCoVs) were the viruses most frequently identified, and incidence decreased with increasing age. Type A influenza was next but with comparable incidence by age. Parainfluenza and respiratory syncytial viruses were less frequent overall, followed by human metapneumoviruses. Incidence was highest in young children, but infections were frequently documented in all age groups. Seasonality followed patterns established decades ago. The SARS-CoV-2 pandemic disrupted these patterns, except for RV and, to a lesser extent, HCoVs. In the first 2 years of the pandemic, RV incidence far exceeded that of SARS-CoV-2.

Conclusions

Longitudinal cohort studies are important in comparing the incidence, seasonality, and characteristics of different respiratory viral infections. Studies documented the differential effect of the pandemic on the incidence of respiratory viruses in addition to SARS-CoV-2.
Efficacy and Safety of Artemether-Lumefantrine Against Uncomplicated Falciparum Malaria Infection in Tanzania, 2022: A Single-Arm Clinical Trial
Authors: Laury Jessica E , Mugittu Kefas , Kajeguka Debora C , Kamugisha Erasmus , Ishengoma Deus S , Mandara Celine I , Ngasala Billy , Chiduo Mercy G , Mahende Muhidin K , Kitau Jovin , Ahmed Maimuna M , Mkumbaye Sixbert I , Francis Filbert , Chacky Frank , Warsame Marian , Serbantez Naomi , Kitojo Chonge , Reaves Erik J , Bishanga Dunstan R , Bajic Marko , Kabula Bilali I , Muro Florida , Kavishe Reginald A
Published: August 2024

Background

Artemether-lumefantrine (AL) is the first-line antimalarial drug for the treatment of uncomplicated malaria in Tanzania. The World Health Organization (WHO) recommends regular efficacy monitoring of antimalarial drugs to inform case management policy decisions. This study assessed the safety and efficacy of AL for treating uncomplicated Plasmodium falciparum malaria in Tanzania in 2022.

Methods

Children aged 6 months to 10 years with uncomplicated P falciparum malaria were recruited from 4 sentinel sites and treated with the standard 6-dose, 3-day regimen for AL. Clinical and parasitological responses were monitored for 28 days using the WHO standard protocol. Genotyping based on msp1, msp2, and glurp was used to distinguish recrudescence from reinfection. Sanger sequencing was used to detect K13 mutations.

Results

Three hundred fifty-two participants, 88 per site, were enrolled. Four withdrew and 55 experienced parasite recurrence. The polymerase chain reaction (PCR)–corrected Kaplan-Meier efficacies were 89.9% in Pwani, 95.0% in Kigoma, 94.4% in Tanga, and 98.9% in Morogoro. No K13 mutations were found.

Conclusions

Artemether-lumefantrine remains highly efficacious in 3 regions of Tanzania, but the PCR-corrected efficacy in Pwani fell below the WHO-defined 90% threshold at which policy change is recommended. Implementing strategies to diversify artemisinin-based combination therapies to ensure effective case management in Tanzania is critical.
Adaptation strategies of giant viruses to low-temperature marine ecosystems
Authors: Buscaglia Marianne , Iriarte José Luis , Schulz Frederik , Díez Beatriz
Published: August 2024

Microbes in marine ecosystems have evolved their gene content to thrive successfully in the cold. Although this process has been reasonably well studied in bacteria and selected eukaryotes, less is known about the impact of cold environments on the genomes of viruses that infect eukaryotes. Here, we analyzed cold adaptations in giant viruses (Nucleocytoviricota and Mirusviricota) from austral marine environments and compared them with their Arctic and temperate counterparts. We recovered giant virus metagenome-assembled genomes (98 Nucleocytoviricota and 12 Mirusviricota MAGs) from 61 newly sequenced metagenomes and metaviromes from sub-Antarctic Patagonian fjords and Antarctic seawater samples. When analyzing our data set alongside Antarctic and Arctic giant viruses MAGs already deposited in the Global Ocean Eukaryotic Viral database, we found that Antarctic and Arctic giant viruses predominantly inhabit sub-10°C environments, featuring a high proportion of unique phylotypes in each ecosystem. In contrast, giant viruses in Patagonian fjords were subject to broader temperature ranges and showed a lower degree of endemicity. However, despite differences in their distribution, giant viruses inhabiting low-temperature marine ecosystems evolved genomic cold-adaptation strategies that led to changes in genetic functions and amino acid frequencies that ultimately affect both gene content and protein structure. Such changes seem to be absent in their mesophilic counterparts. The uniqueness of these cold-adapted marine giant viruses may now be threatened by climate change, leading to a potential reduction in their biodiversity.
O02 Beyond borders: a global risk analysis of XDR Salmonella Typhi and typhoid outbreaks in Pakistan
Authors: Ahmad Saeed , Idrees Fahmeeda
Published: August 2024

Background

Pakistan has experienced a surge in typhoid outbreaks caused by an emergent strain of XDR Salmonella Typhi since 2016. This strain, resistant to multiple antibiotics including third generation cephalosporins, poses a significant public health threat not only within Pakistan but also globally due to international travel. Understanding the mechanisms of transmission and identifying high-risk regions for importation and onward transmission of XDR S. Typhi are crucial for effective outbreak management and containment efforts.

Objectives

This study investigates the global risk posed by XDR S. Typhi outbreaks, with a focus on understanding the dynamics of transmission and identifying regions at heightened vulnerability. The research aims to assess the association between air travel patterns from Pakistan and the spread of XDR S. Typhi globally, providing insights for targeted public health interventions.

Methods

Using data from the District Health Information System (DHIS-2) for reporting priority infectious diseases in Pakistan, this study employs a combination of epidemiological analysis and phylogeographic modelling. Air travel volume data from Pakistan are analysed to discern patterns of XDR S. Typhi transmission to other countries. Phylogeographic models are fitted to identify associations between air travel volume and the movement of the H58 haplotype of S. Typhi. Flight itinerary data are cross-referenced with model-based estimates of typhoid fever incidence to identify countries at highest risk of importation and sustained transmission of XDR S. Typhi.

Results

The analysis reveals a significant association between air travel volume from Pakistan and the rate of between-country movement of XDR S. Typhi, particularly the H58 haplotype. Countries with strong travel links to Pakistan and efficient local S. Typhi transmission are identified as being at highest risk of importation and sustained onward transmission of XDR S. Typhi. These findings underscore the importance of targeted public health interventions in high-risk countries to mitigate the spread of XDR S. Typhi.

Conclusions

This study highlights the global threat posed by XDR S. Typhi outbreaks originating in Pakistan. The identification of high-risk countries based on air travel patterns and transmission dynamics provides valuable insights for prioritizing public health activities to track and mitigate the spread of XDR S. Typhi. Efforts to strengthen surveillance, enhance antimicrobial stewardship and improve sanitation infrastructure are critical for preventing and controlling future outbreaks of XDR typhoid on a global scale.
P15 The main aetiological factors of lung damage in severe pneumonia and sepsis in military servicemen: retrospective analysis for 2023
Authors: Viltsaniuk Oksana , Syvak Viktor , Lysak Tatiana , Sokolovska Nataliia , Viktoria Martyniuk , Viltsaniuk Oleksandr
Published: August 2024

Background

Today, the problem of pulmonary pathology is very relevant in Ukraine, as it is not always possible to provide timely and high-quality medical care owing to the Russian invasion of Ukraine.

Objectives

To analyse the types of the main aetiological factors of lung pathology and their susceptibility to different groups of antimicrobial agents used at different stages of treatment of these patients.

Materials and methods

Microbiological studies of 36 case histories of severe patients who were inpatients in the pulmonology department of the Military Medical Centre were analysed.

Results

The main diseases that caused lung pathology were community-acquired pneumonia (44%), septic pneumonia (29%) and nosocomial pneumonia (27%). When studying the extent of lung involvement, the most common was involvement of four and five lobes of the lungs, which accounted for 61% of all cases, and the most common complication was exudative pleurisy (57%). In the course of studying the microbiological characteristics of pathogens, a monoculture was isolated in 80% of cases, in 12% of cases there was a combination of Staphylococcus aureus and Klebsiella pneumoniae, and in 8% of cases S. aureus, K. pneumoniae and Enterobacter were identified. S. aureus and K. pneumoniae were most often isolated from sputum and pleural fluid. Susceptibility testing showed that in the vast majority of cases S. aureus was susceptible to meropenem, linezolid, cefepime, cefoperazone, ciprofloxacin and amikacin. K. pneumoniae was susceptible to cefepime and ciprofloxacin in only 2% of cases, while it was resistant to other antibiotic groups. Pathogens isolated from blood were mostly S. aureus and Staphylococcus haemolyticus, which were susceptible to meropenem and vancomycin, while resistance to ceftazidime, moxifloxacin, cefazolin and amikacin was noted.

Conclusions

The isolated pathogens are resistant to the main groups of antimicrobial drugs recommended for use according to the AWaRe antibiotic classification in the initial stages of empirical antimicrobial therapy. This is of concern because there is an active use of reserve drugs, which in turn also contributes to the progression of resistance to such drugs. In addition, active migration of people between countries may lead to the spread of this trend beyond Ukraine.
P17 Characteristics of pathogens and their susceptibility to the main groups of antibiotics in purulent-inflammatory diseases of soft tissues and post-operative purulent complications
Authors: Viltsaniuk Oleksandr , Belyaev Pavlo
Published: August 2024

Background

The problem of purulent-inflammatory diseases of soft tissues and post-operative purulent complications remains one of the most pressing problems of modern medicine. Despite the advances in the improvement of methods for fighting infectious complications, mortality in patients with suppurative and inflammatory processes remains high, which is primarily due to inadequate antimicrobial therapy and high antibiotic resistance of microorganisms. Therefore, the study of the nature of the microflora and its susceptibility to antimicrobial drugs remains an urgent problem.

Objectives

To investigate the nature of pathogens and their susceptibility to the main groups of antibiotics in the patients of a general surgical hospital with purulent inflammatory diseases of soft tissues and post-operative purulent complications.

Materials and methods

A retrospective review of the pathogens of purulent inflammatory processes of soft tissues and post-operative purulent complications, their susceptibility to the main groups of antibiotics in 704 patients who were treated in the surgical department for abscesses, phlegmon, post-operative wound suppuration and other purulent inflammatory processes were performed.

Results

The analysis revealed that aerobic microflora was isolated in 560 patients (79.5%) and anaerobic microflora in 144 (20.5%). Among the isolated microflora, Staphylococcus aureus prevailed, which was isolated in 286 (40.6%) cases, Staphylococcus epidermidis in 115 (16.3%), Escherichia coli in 69 (9.8%) was in third place in terms of frequency of isolation, Klebsiella pneumoniae was isolated in 16 cases (2.3%), Enterococcus faecalis and P. aeruginosa in 26 (3.7%), and P. vulgaris in 6 (0.9%). Candida spp. were isolated in 15 (2.1%) patients and did not significantly affect the structure of pathogens of purulent inflammatory processes. Susceptibility testing of S. aureus, as the main causative agent of purulent inflammatory processes, showed its resistance to penicillin, aminoglycosides and macrolides. Third and fourth generation cephalosporins (63.1%), fluoroquinolones (76.3%) and lincosamides (70.8%) showed the highest activity against the isolated Staphylococcus strains.

Conclusions

The main causes of purulent inflammatory diseases of soft tissues and post-operative purulent complications were S. aureus in 40.6% of cases, S. epidermidis in 16.3%, and intestinal bacteria. Third and fourth generation cephalosporins showed highest activity against the isolated S. aureus strains (63.1% of susceptible strains), followed by fluoroquinolones (76.3% of susceptible strains) and lincosamides (70.8%). Empirical therapy for purulent inflammation should take into account the microbial landscape of pathogens and their susceptibility to antibiotics in a particular general surgical hospital.
P33 Improving compliance with early IV-to-oral switch of antibiotics using quality improvement methodology
Authors: Khan Muhammad Sami , May Sarah
Published: August 2024

Background

Antimicrobial stewardship (AMS) refers to a coherent set of interventions which promote responsible use of antimicrobials.1 Timely IV-to-oral switch (IVOS) of antibiotics is one of the interventions which has several clinical benefits,2 but unfortunately frequent non-compliance has been observed in clinical practice. To address this, we aim to improve IVOS of antibiotics in the respiratory department of our hospital using quality improvement (QI) methodology.

Methods

A QI project was conducted at the respiratory department of Calderdale Royal Hospital, West Yorkshire. A total of 82 adult inpatients (42 retrospective, 40 prospective), aged 18 years and over, with active prescriptions of IV antibiotics at the time of project, were elected. We excluded patients with known deep-seated infections, in the ICU or high dependency unit and those treated with IV antifungals or antivirals. UKHSA National IVOS criteria for adults3 was utilized as standard of care. Baseline data were collected retrospectively in November–December 2023 which was compared with post-intervention prospective re-audit in February–March 2024. Interventions included: e-mail correspondence and IVOS decision aid poster exhibition in wards; education sessions in weekly departmental teaching and board rounds; distributing lanyard cards with ACED tool, consistent with National IVOS criteria3, among doctors; and twice weekly pharmacist IVOS rounds. Outcome measures consisted of antibiotic(s) review within 24 h of prescription; eligible patients switched when met criteria; time to switch; and duration of IV therapy.

Results

Post-intervention phase revealed substantial improvement in outcome measures compared with baseline: antibiotic(s) review within 24 h of prescription (from 10% to 94%); eligible patients switched when met criteria (from 33.3% to 90%); median time to switch (from 22 h 34 min to 06 h 22 min); and median duration of IV therapy (from 96 h to 48 h). We found unawareness of existence of national criteria as significant factor contributing to local non-compliance at baseline which improved with QI interventions.

Conclusions

QI methodology helped significantly in promoting local antimicrobial stewardship by bridging the knowledge gaps regarding IVOS standards among doctors and empowering them for prompt IVOS decisions, where appropriate. This small AMS intervention, when implemented appropriately, has a big impact in reducing antimicrobial resistance and healthcare costs with better clinical outcomes. We recommend encouragement of such QI projects to implement standards and optimize the antimicrobial prescribing practice.