bluuebunny/crossref_metadata_2025_split huggingface dataset:
Nothing is ever lost or forgotten: Searching for the traces of Mo Dickyi Sangmo
Authors: Gill Harmandeep Kaur 
Published: October 2024

AbstractThis ethnographic article provides glimpses into the everyday life of an elderly Tibetan woman, Mo Dickyi Sangmo, who used to live in the Tibetan exile capital of McLeod Ganj in northwest India. Old age for her was a falling apart of her life world, giving rise to a series of absences in her daily life. I always sensed in her a longing for that which was missing, gathered through her somber moods and constant complaints. While others emphasized Dickyi's annoyed and closed‐off persona, I sensed that there was more to her; something was hidden in the gaps between her words and the silences that rested in between us. This article grew from my attempt at lending Mo Dickyi a compassionate ear, in an effort to understand what had become of her. By combining words and images, it became an experiment in a type of seeing and listening that is like a tender and soothing touch. By sensing Mo Dickyi through my words and in my images of her, this contribution is also a call out to the reader's imagination to uncover the gaps, and to possibly connect with the loneliness of Mo Dickyi's heart.
Reconstructing host plant repertoire and timing of evolution of phyline plant bugs (Hemiptera, Miridae)
Authors: Bush Tatiana , Weirauch Christiane 
Published: October 2024

AbstractThe diversity of phytophagous insects is often attributed to the success of land plants in the framework of ecological speciation. Several hypotheses have been proposed to explain host plant driven insect diversification in a phylogenetic context and have mostly been explored using Lepidoptera. We posit that Miridae are a great system to examine these hypotheses because they are one of the largest primarily phytophagous insect families and include many species with narrow host repertoire. Focusing on the species‐rich Phylinae (>2700 spp.), we generate the most taxon‐rich phylogeny published to date and for the first time estimate divergence times and trace the evolution of host plant associations across the group. Focusing on two clades of oak‐associated phylines, we further examine if diversification in these insects and their hosts coincided or if the insects tracked their hosts. We find that Phylinae diverged from their orthotyline sister group before the end of the Cretaceous, tribal‐level taxa diversified throughout the Paleogene, and diversification within genera mostly occurred in the Neogene. Host plant repertoire reconstructions at the family level show transitions from stenophagy to polyphagy are more common than the reverse. We reconstructed the ancestral phyline host as ambiguous, followed by Asterales throughout most of the deep splits. Species‐level divergences in the two oak‐associated clades coincide with those in oaks, a pattern is that is consistent with the hypothesis that these plant bugs may have cospeciated with their hosts. Our study shows that Phylinae are a suitable system to further test hypotheses on ecological speciation of plants and insects but will require more robust phylogenetic hypotheses of the group.
Conformally invariant random fields, Liouville quantum gravity measures, and random Paneitz operators on Riemannian manifolds of even dimension
Authors: Schiavo Lorenzo Dello , Herry Ronan , Kopfer Eva , Sturm Karl‐Theodor 
Published: October 2024

AbstractFor large classes ofeven‐dimensionalRiemannian manifolds , we construct and analyze conformally invariant random fields. These centered Gaussian fields , calledco‐polyharmonic Gaussian fields, are characterized by their covariance kernelskwhich exhibit a precise logarithmic divergence: . They share a fundamental quasi‐invariance property under conformal transformations. In terms of the co‐polyharmonic Gaussian field , we define theLiouville Quantum Gravity measure, a random measure on , heuristically given asand rigorously obtained as almost sure weak limit of the right‐hand side with replaced by suitable regular approximations . In terms on the Liouville Quantum Gravity measure, we define theLiouville Brownian motionon and therandom GJMS operators. Finally, we present an approach to a conformal field theory in arbitrary even dimension with an ansatz based on Branson's ‐curvature: we give a rigorous meaning to thePolyakov–Liouville measureand we derive the correspondingconformal anomaly. The set ofadmissiblemanifolds is conformally invariant. It includes all compact 2‐dimensional Riemannian manifolds, all compact non‐negatively curved Einstein manifolds of even dimension, and large classes of compact hyperbolic manifolds of even dimension. However, not every compact even‐dimensional Riemannian manifold is admissible. Our results concerning the logarithmic divergence of the kernel rely on new sharp estimates for heat kernels and higher order Green kernels on arbitrary closed manifolds.
Transient Analysis of Flow Unsteadiness and Machine Instabilities in a Centrifugal Compressor at Surge and Second Quadrant Operation
Authors: Serena Alberto , Bakken Lars E. 
Published: October 2024

Abstract
Instabilities in turbomachinery operation originate from intrinsic flow unsteadiness, sudden variations of operating conditions, and interactions with the surrounding system, affecting both system stability and machine reliability. The flow unsteadiness, presenting a characteristic behavior, requires a deep understanding of the underlying flow fundamentals, a careful analysis using advanced experimental methods and a clear distinction on how the system might lead to instabilities. The identified approach addresses deep surge and second quadrant characterization. The analysis presented here benefits from the responsiveness and flexibility of the experimental test rig, fine tuning of the system layout, the instrumentation installation, and the transient tests procedure. The main focus area is the time-frequency analysis of flow and pressure signals at transients, thus providing a proper reconstruction of flow mechanisms and instability evolution. Valuable techniques include: short-time fast Fourier transform, wavelet analysis, and Wigner-Ville distribution; coherence between flow and pressure, to trace waves propagation, is considered too. These, presented outlining their strengths and weaknesses, are evaluated considering real-time field applicability with regards to computational resources too. The experimental campaigns and data processing are presented, with a test matrix covering a wide range of parameters, including system layout and surge volume size, rotational speeds, flow rates ranging from nominal point to full second quadrant operation. These data are vital for system modeling validation for a full compressor-system digital twin. Results indicate the importance of ensuring reliable data acquisition and analysis, with adequate instrumentation range, accuracy, synchronization, responsiveness and positioning.
Response of n-Heptane and Dodecane Swirl-Stabilized Spray Flames to Transverse Forcing Characterized by Flame Describing Functions Based on Downstream Acoustic Pressure or Velocity Signals
Authors: Patat Clément , Blaisot Jean-Bernard , Domingues Éric , Baillot Françoise 
Published: October 2024

Abstract
Predicting thermoacoustic instabilities in annular combustors requires knowledge of the impact of acoustic oscillations on heat release rate (HRR) oscillations. Flame describing functions (FDF) measured at the burner exit using acoustic forcing are key elements of thermoacoustic instability analyses. FDFs based on acoustic pressure measurements, FP′, or on axial velocity measurements, FU′, are compared here. This study is done on the TACC-Spray bench, an original linear array of spray flames stabilized by a strong swirling flow, representing an unfolded sector of a self-unstable annular combustor. Acoustic forcing of a standing transverse chamber mode is applied downstream of the injectors. Experiments are conducted with liquid n-heptane or dodecane, with the flames placed at a pressure or an intensity antinode (IAN) of the transverse mode. FP′ does not depend on the measurement location for acoustically compact flames provided that this location remains in the flame vicinity. FU′ can lead to significant discrepancies, as swirling flows present strong velocity gradients, which can be minimized by carefully choosing the measurement location. The injector admittance linking the two FDFs is shown to be quasi-independent of the forcing amplitude here. Consequently, both FDFs show a similar dependence on the forcing amplitude. FP′ indicates constructive combustion-acoustics interference whatever the flame location in the acoustic field and the fuel, consistent with self-sustained instabilities observed in the annular combustor. An analysis using the Rayleigh criterion corroborates the results derived from the FDFs. So, FP′ appears as a powerful and practical tool for characterizing combustion dynamics.
Analysis of the Flow-Field Distortions Induced by Pneumatic Pressure Probes in Test Bench Experiments on Centrifugal Compressors: Are We Testing Right?
Authors: Baroni Alberto , Romani Luca , Balduzzi Francesco , Toni Lorenzo , Grimaldi Angelo , Belardini Elisabetta , Biliotti Davide , Bianchini Alessandro , Ferrara Giovanni 
Published: October 2024

Abstract
Experimental testing at the test rig still plays a key role in the development of new centrifugal compressor designs for industrial applications. Although a wide set of different probes is used as per common practice, the overall impact of the probes' dimensions on the stage performance and rangeability is often assumed to be negligible. In this study, we aimed at quantifying the intrusiveness effects of pneumatic pressure probes on the flow-field inside a vaned diffuser using a model stage of an industrial centrifugal compressor, for which different experimental setups were tested at the University of Florence test rig. Performance and rangeability were initially assessed using a conventional set of pneumatic probes inserted in the flow path. Then, comparative analyses were realized through dedicated tests by either removing all probes at the diffuser inlet or introducing only a single pressure probe in the upstream section and varying its angular position in the measuring section. Experiments revealed an impact of upstream probes much higher than expected, with a decrease in efficiency and a substantial reduction of stall margin. Moving from this experimental evidence, accurate three-dimensional computational fluid dynamics (CFD) simulations of the entire stage were carried out including the actual geometry of the probes for two probes configurations and three operating points (OPs). Simulations highlighted the effect probes' wakes on downstream vanes and the induced blockage effect, which both appear in line with experimental evidence. As a handout, a recommendation on the optimal probe positioning is suggested.
Investigation of Onboard Power Generation Method Using Waste Energy at Altitude Conditions
Authors: Kang Sang-Guk , Pope Aaron J. , Schroen Erik S. , Mattson Jonathan M. , Kim Kenneth S. , Hepp Kyle D. , Kruger Kurt M. , Kweon Chol-Bum M. , Gibson Joseph A. , Meininger Rik D. , Musser Marshall R. 
Published: October 2024

Abstract
Demand for increased onboard power generation on small aircraft is ever growing due to increased electrical power demand. The objective of this study is to investigate onboard power generation using waste energy at various altitude and ambient conditions. Experiments were performed on a 2-liter, turbocharged direct-injection intermittent combustion engine fueled with jet fuel (F-24). The turbocharger has an integrated motor-generator system that is designed to generate electricity using the enthalpy in the engine exhaust, or to use as a motor to rotate the turbocharger using the energy stored in onboard energy storage device. An electrically actuated wastegate was used to control useful exhaust flowrate that is used to generate electricity. An external power supply system was used to emulate the energy storage. The engine was installed in the U.S. DEVCOM Army Research Laboratory's altitude chamber in which absolute outside air pressure was controlled up to 37.6 kPa to simulate the altitude conditions up to 7,620 m (25,000 ft). Three different ambient conditions were selected to represent International Standard Atmosphere (ISA), polar, and tropical conditions. Based on the experimental results, a response surface model was developed to predict the power generation of the motor-generator integrated turbocharger using waste energy as a function of altitude, engine power, and the wastegate position. The result from this study provides an insight into onboard power generation method using waste energy at altitude conditions.
Emissions and Flame Stability Assessment of Hydrogen Addition and Air Dilution in a Microgas Turbine Combustor Using Zero-Dimensional/One-Dimensional Modeling by Chemical Reactor Network
Authors: Farrokhi Farshid Yousefzad , Piscopo Alessandro , Pappa Alessio , Parente Alessandro , De Paepe Ward 
Published: October 2024

Abstract
Hydrogen emerges as a promising fuel for clean and sustainable electricity production when utilized in microgas turbines (mGTs). However, some challenges linked to hydrogen usage must be overcome as its high reactivity can lead to increased NOx emissions and flame instabilities. Literature suggests that combustion air humidification and/or exhaust gas recirculation (EGR) may be methods to reduce this reactivity. However, these measures are limited due to the small operating range of the mGT combustor. In this context, a 20 kWth mGT combustor is investigated under various inlet conditions to assess the effect of EGR toward increased flame stability and emission control when operating under hydrogen-enriched methane firing, using a chemical reactor network (CRN) model. The CRN modeling is a fast and low computational complexity tool to model combustion performance and emissions by representing complex reactive flow fields through idealized reactor models, leading to reduced computational costs. This study examines partial load conditions, fuel compositions, and the effect of combustion air dilution through EGR. The CRN model of the combustion process is designed based on combustion zones extracted from the main flow fields with similar thermochemical states from computational fluid dynamics (CFD) analysis, while emission predictions are experimentally validated for different operating points. Predicted NOx and CO emissions by the proposed CRN model show an acceptable agreement with the experimental data at high power loads. However, its accuracy diminishes for loads below 70% due to the variability in model tuning parameters across different loads, whereas the current model is optimized for 90% load conditions. At full load with the activation of EGR, these emissions are reduced by approximately 20%. CRN results predict that NOx emissions do not increase excessively by hydrogen addition due to the constant power operation of the mGT. Indeed, the higher reactivity of hydrogen leads to a lower fuel flow rate and, thus, leaner operating conditions. On the other hand, CO emissions decrease by 15% to 40% when adding hydrogen from 5% to 50% of the volume fraction to natural gas (NG). Finally, air dilution by EGR positively affects flame temperature and NOx emissions. Tuning CRN models that are not dependent on specific load parameters to get a better agreement with experimental data, as well as EGR/humidified air dilution effects on partial loads and hydrogen-added fuels, are subjects to future work.
On the Relationship Between Swirl and Unsteadiness Within Turbine Rim Seals
Authors: Vella Simon , Tang Hui , Carnevale Mauro , Scobie James A. , Lock Gary D. , Salvatori Francesco , Sangan Carl M. 
Published: October 2024

Abstract
Unraveling the flow physics pertaining to hot gas ingress in turbines is crucial in enabling designers to realize global decarbonization targets in aerospace. A turbine rim seal is fitted at the periphery of the rotor–stator cavity to minimize the ingress of annulus gas, which detrimentally affects cycle's efficiency. The inherent unsteadiness in rim seal flows, arising from shear gradients between contiguous flow paths, introduces a consequential, yet presently unestablished, influence on sealing characteristics. A single-stage axial turbine facility in conjunction with an aeroengine architecture is employed to assess the steady and unsteady sealing characteristics of a range of industrially relevant rim seals. Time-averaged measurements of gas concentration and swirl, acquired over a range of flow coefficients (CF), exhibited an inverse relationship between sealing performance and the purge-mainstream swirl difference (Δβ). Spectral analysis of unsteady pressure signals revealed an associated unsteadiness, induced by the strength of the annulus-cavity interaction. Across all CF, a low-frequency harmonic range consistently displayed proportionality between spectral activity and Δβ. Thus, a relationship between steady and unsteady characteristics was established. Examining a series of rim seal configurations with varying radial clearances signified that sealing performance was predominantly influenced by the radially outermost clearance. The configurations exhibiting superior performance presented heightened spectral activity, ascribed to an increased radial purge mass flux and establishing a definite relationship with concurrent steady measurements.
Diversity of
Campylobacter
spp. circulating in a rhesus macaque (
Macaca mulatta
) breeding colony using culture and molecular methods
Authors: Bacon Rebecca L. , Hodo Carolyn L. , Wu Jing , Welch Shannara , Nickodem Colette , Vinasco Javier , Threadgill Deborah , Gray Stanton B. , Norman Keri N. , Lawhon Sara D. 
Published: October 2024

ABSTRACT

Campylobacter jejuni
and
Campylobacter coli
represent the leading causes of bacterial gastroenteritis in humans, and infections can produce post-infectious irritable bowel syndrome (PI-IBS). Rhesus macaques (
Macaca mulatta
) (RM) are similarly susceptible to acute campylobacteriosis and represent a potential model of PI-IBS. We characterized the
Campylobacter
species circulating in an RM breeding colony using culture, qPCR, and whole genome sequencing (WGS). We also compared the
C. jejuni
and
C. coli
prevalence in RM as detected with qPCR versus culture and identified risk factors for bacteria presence and intestinal disease. Culture of 275 samples yielded
C. coli
(103) and
C. jejuni
(8), of which 21.6% were resistant to quinolones and 3.6% were resistant to macrolides. Multidrug-resistant isolates were obtained exclusively from animals exhibiting diarrhea or with histologically confirmed chronic enterocolitis. WGS revealed a non-clonal population of
Campylobacter
spp. Genotypic predictions of resistance were excellent except for aminoglycosides. All sequenced isolates contained genes for all subunits of cytolethal distending toxin. qPCR detected a prevalence of 45.9% for
C. coli
and 29.6% for
C. jejuni
. The quantity of either bacteria was significantly higher (
P
< 0.05) in animals with intestinal disease compared to healthy animals, though only young age was significantly associated with the presence of
Campylobacter
sp. or intestinal disease. Significantly more
C. jejuni
positive animals were detected with qPCR than with culture. These results provide a comprehensive characterization of
Campylobacter
spp. circulating in a breeding colony of RM in the United States and suggest that qPCR is superior for the detection of
C. jejuni
in RM.

IMPORTANCE

Gastrointestinal disease is one of the most common reasons for hospitalization in non-human primate colonies and accounts for over one-third of non-research related euthanasia. In rhesus macaques, this manifests as both acute diarrhea and chronic enterocolitis (CE), a syndrome of chronic diarrhea resulting in poor weight gain or weight loss which is minimally responsive to treatment.
Campylobacter
spp. are major causes of acute enterocolitis in rhesus macaques and may predispose individuals to the development of CE, similar to post-infectious irritable bowel syndrome in humans. Despite these concerns, there are few studies characterizing
Campylobacter
in rhesus macaque colonies, in particular utilizing whole genome sequencing and assessing findings with respect to the health status of the host. Our findings provide insight into
Campylobacter
strains circulating in rhesus macaque colonies, which can improve clinical monitoring, assist in treatment decisions, and provide new avenues of investigation into campylobacteriosis as a catalyst for CE.
Marsh topography reveals the signature of storm-surge-driven sedimentation
Authors: Tognin Davide , D’Alpaos Andrea , Ghinassi Massimiliano , Carniello Luca 
Published: October 2024

Abstract
Salt marshes are valuable tidal landforms threatened by drowning due to increasing sea levels. Marsh accretion supported by sediment settling during repeated flooding potentially offsets the relative elevation loss. Although tidal flooding is commonly depicted as the main mechanism delivering the sediment to marshes, storm surges and waves may deeply affect tidal flow conditions and sediment reworking in shallow tidal systems, thus raising questions on the relative contribution of these processes to salt-marsh accretion. Here we show that storm surges substantially sustain the marsh sediment budget, locally contributing up to 90% of sedimentation, and critically influence depositional patterns by analyzing a 3-yr-long measurement record of sedimentation on the marshes in the Venice Lagoon (Italy). Surge-enhanced water levels promote wind-wave-driven sediment fluxes directly across the tidal flat-marsh transition, altering tidal sedimentation patterns and, thus, affecting marsh topographic elevation and morphology. By comparing sedimentation patterns and topographic profiles, we show that the signature of storm-surge sedimentation can be found in marsh topography, which we suggest therefore as an easily detectable indicator of the relative contribution of the different physical processes driving marsh vertical evolution. The comparison with other marshes worldwide, characterized by different tidal ranges and wave exposure, consistently supports the link between the salt-marsh topographic profile and the physical processes controlling marsh evolution.