bluuebunny/crossref_metadata_2025 huggingface dataset:
Speech Amplification Device Usage for the Management of Hypophonia: A Survey of Speech-Language Pathologists
Authors: Gates Kelly , Knowles Thea , Mach Helen , Higginbotham Jeff , Holder Thea
Published: April 2024

Purpose:

The purpose of this study was to survey speech-language pathologists (SLPs) who assess and treat people with Parkinson's disease (PD) to gather insights into their decision making regarding their use or potential use of speech amplification technology for the management of hypophonia.

Method:

A total of 111 SLPs who were currently practicing in the United States or Canada and had experience working with clients with PD for at least 2 years completed an anonymous Qualtrics survey. Questions were designed to probe the following areas: (a) degree of familiarity with amplification devices as a form of treatment for PD, (b) attitudes and perceptions of the implementation of these devices for PD, and (c) factors that influence the clinical decision to prescribe such devices.

Results:

Most participants (75; 71%) reported they had considered prescribing a device to at least one client with PD. When asked at which stages of speech or voice impairment they would consider the use of an amplification device for clients with PD, the most common response was for clients with moderate or severe hypophonia who were not stimulable for louder speech. However, 36 (32%) respondents indicated they would also consider an amplification device for clients who were stimulable for louder speech with severe hypophonia. When asked to rank the most important factors they would weigh when considering the prescription of an amplification device, they ranked the client's preference and comfort level as the most important consideration.

Conclusion:

This study provides valuable clinical insights regarding how SLPs can approach utilizing speech amplification devices in the therapy environment.
Used to Be a Dime, Now It's a Dollar: Revised Speech Perception in Noise Key Word Predictability Revisited 40 Years On
Authors: Whitley Alexina , Naylor Graham , Hadley Lauren V.
Published: April 2024

Purpose:

Almost 40 years after its development, in this article, we reexamine the relevance and validity of the ubiquitously used Revised Speech Perception in Noise (R-SPiN) sentence corpus. The R-SPiN corpus includes “high-context” and “low-context” sentences and has been widely used in the field of hearing research to examine the benefit derived from semantic context across English-speaking listeners, but research investigating age differences has yielded somewhat inconsistent findings. We assess the appropriateness of the corpus for use today in different English-language cultures (i.e., British and American) as well as for older and younger adults.

Method:

Two hundred forty participants, including older (60–80 years) and younger (19–31 years) adult groups in the the United Kingdom and United States, completed a cloze task consisting of R-SPiN sentences with the final word removed. Cloze, as a measure of predictability, and entropy, as a measure of response uncertainty, were compared between culture and age groups.

Results:

Most critically, of the 200 “high-context” stimuli, only around half were assessed as highly predictable for older adults (United Kingdom: 109; United States: 107); and fewer still, for younger adults (United Kingdom: 75; United States: 81). We also found dominant responses to these “high-context” stimuli varied between cultures, with U.S. responses being more likely to match the original R-SPiN target.

Conclusions:

Our findings highlight the issue of incomplete transferability of corpus items across English-language cultures as well as diminished equivalency for older and younger adults. By identifying relevant items for each population, this work could facilitate the interpretation of inconsistent findings in the literature, particularly relating to age effects.
Pediatric Feeding Disorder and the School-Based Speech-Language Pathologist: An Evidence-Based Update for Clinical Practice
Authors: Homer Emily M.
Published: April 2024

Purpose:

This prologue introduces the forum “Pediatric Feeding Disorder and the School-Based SLP: An Evidence-Based Update for Clinical Practice” and informs the reader of the scope of articles presented.

Method:

The guest prologue author provides a brief history of pediatric feeding and swallowing services in the public-school setting, including previous forums on swallowing and feeding services in the schools (Logemann & O'Toole, 2000; McNeilly & Sheppard, 2008). The concepts that have been learned since the 2008 forum are shared. The contributing authors in the forum are introduced, and a summary is provided for each of the articles.

Conclusions:

The articles provide evidence-based information on topics that are uniquely of interest to school-based speech-language pathologists managing pediatric feeding and swallowing in their districts. The topics shared in this forum range from relevant information on anatomy, physiology, developmental milestones, and differential diagnosis to therapeutic practice when identifying and treating pediatric feeding and swallowing in the school setting. The forum also includes focused articles on the necessity of collaboration with families during the treatment process, current information on legal parameters dealing with school-based pediatric feeding disorder services, and a framework for assessment and treating pediatric feeding disorder in the school setting.
Very long baseline interferometry detection of nearby (<100 pc) young stars
Authors: Dzib Sergio A. , Loinard Laurent , Launhardt Ralf , Ordóñez-Toro Jazmín
Published: April 2024

To increase the number of sources with very long baseline interferometry (VLBI) astrometry available for comparison with the Gaia results, we have observed 31 young stars with recently reported radio emission. These stars are all in the Gaia DR3 catalog and were suggested, on the basis of conventional interferometry observations, to be nonthermal radio emitters and are therefore good candidates for VLBI detections. The observations were carried out with the Very Long Baseline Array (VLBA) at two epochs separated by a few days and yielded ten detections (a roughly 30% detection rate). Using the astrometric Gaia results, we extrapolated the target positions to the epochs of our radio observations and compared them with the position of the radio sources. For seven objects, the optical and radio positions are coincident within five times their combined position errors. Three targets, however, have position discrepancies above eight times the position errors, indicating different emitting sources at optical and radio wavelengths. In one case, the VLBA emission is very likely associated with a known companion of the primary target. In the two other cases, we associated the VLBA emission with previously unknown companions, but further observations will be needed to confirm this.
Models of quasi-discontinuous solar-wind streams
Authors: Westrich Lukas , Shergelashvili Bidzina M. , Fichtner Horst
Published: April 2024

Context. The modeling of the solar-wind outflow patterns is addressed in terms of local transient distortions of the flow, temperature, and density profiles due to the presence of local energy sources. A recently introduced related new class of analytically derived quasi-discontinuous solar-wind solutions is numerically approached.

Aims. The analytical discontinuous solutions can asymptotically obtained from steady-state and time-dependent models in the limit of very localized external heating. The aim of the current study is to develop a numerical confirmation for the presence of quasi-discontinuous distortions of the wind profiles by mimicking the local energy sources with additional source terms in the governing equations of the numerical models.

Methods. Corresponding systems of ordinary and partial differential equations, respectively, are formulated employing prescribed heating functions. After a comparison of sequences of numerically obtained steady-state solutions with the analytical one, the stability of the former is tested with a time-dependent simulation.

Results. The analytical discontinuous solutions are asymptotically reproduced with the quasi-discontinuous steady-state and time-dependent numerical solutions in the limit of vanishingly small width (compared to the other characteristic length scales of the system) of the heating function.

Conclusions. The interpretation that such solutions result from strongly localized heating has been confirmed both qualitatively and quantitatively. The applied numerical approach enables the building of more complex, multidimensional counterpart models and local profiles of typical local energy sources that are presumably responsible for the dynamical properties of the solar-wind patterns found.
Titanium abundances in late-type stars
Authors: Mallinson J. W. E. , Lind K. , Amarsi A. M. , Youakim K.
Published: April 2024

Context. Rapidly growing datasets from stellar spectroscopic surveys are providing unprecedented opportunities to analyse the chemical evolution history of our Galaxy. However, spectral analysis requires accurate modelling of synthetic stellar spectra for late-type stars, for which the assumption of local thermodynamic equilibrium (LTE) has been shown to be insufficient in many cases. Errors associated with LTE can be particularly large for Ti I, which is susceptible to over-ionisation, particularly in metal-poor stars.

Aims. The aims of this work are to study and quantify the 1D non-LTE effects on titanium abundances across the Hertzsprung-Russell diagram for a large sample of stars.

Methods. A large grid of departure coefficients, βν, were computed on standard MARCS model atmospheres. The grid extends from 3000 K to 8000 K in Teff, −0.5 dex to +5.5 dex in log g, and −5.0 to +1.0 in [Fe/H], with non-LTE effects in this grid reaching up to 0.4 dex. This was used to compute abundance corrections that were subsequently applied to the LTE abundances of over 70 000 stars selected from the GALAH survey in addition to a smaller sample of literature Keck data for metal-poor dwarfs.

Results. The non-LTE effects grow towards lower [Fe/H], lower log g, and higher Teff, with a minimum and maximum ΔA(Ti)Ti I of 0.02 and 0.19 in the GALAH sample. For metal-poor giants, the non-LTE modelling reduces the average ionisation imbalance (ΔI−II) from −0.11 dex to −0.01 dex at [Fe/H] = −1.7, and the enhancement in titanium abundances from Ti I lines results in a [Ti/Fe] versus [Fe/H] trend that more closely resembles the behaviour of Ti II at low metallicities. At higher metallicities, the results are limited by the precision of the GALAH DR3 LTE abundances and the effects are within the errors. For the most metal-poor dwarfs from the Keck sample, the average ionisation imbalance increases from −0.1 dex to +0.2 dex, a shortcoming that is consistent with previous 1D non-LTE studies and which we speculate could be related to 3D effects.

Conclusions. Non-LTE effects on titanium abundances are significant. Neglecting them may alter our understanding of Galactic chemical evolution. We have made our grid of departure coefficients publicly available, with the caveat that the Ti abundances of metal-poor dwarfs need further study in 3D non-LTE.
Anatomy of the Class I protostar L1489 IRS with NOEMA
Authors: Tanious M. , Le Gal R. , Neri R. , Faure A. , Gupta A. , Law C. J. , Huang J. , Cuello N. , Williams J. P. , Ménard F.
Published: April 2024

Context. Over the past few years, chemical studies have revealed multiple structures in the vicinity of young stellar objects (YSOs). It has become evident that specific physical conditions are associated with the emission of particular molecular lines, allowing us to use molecular probes of the YSO physics. Consequently, chemical surveys are now necessary to fully constrain the origin of the observed structures. Several surveys have been conducted to explore the chemistry of YSOs, focusing on Class 0 and Class II objects. However, our knowledge of intermediate objects, that are Class I objects, remains limited.

Aims. To bridge the gap and establish the relationship between observed structures and molecular line emission at the Class I evolutionary stage, we investigate the spatial distribution of key molecular gas species in the low-mass Class I protostar L1489 IRS (IRAS 04016+2610), a source part of the ChemYSO survey.

Methods. We performed a 3 mm line survey at high spatial and high spectral resolution using the NOEMA interferometer and the IRAM-30 m telescope. For the data analysis, we applied and compared two methods: a streamline model and the new python package TIPSY.

Results. We present here the ten brightest lines of our survey, in which we identified a new ~3000 au long streamer in HC3N, C2H, and c–C3H2 emission, likely associated with more localized accretion shocks probed in SO. In addition, two ~10 000 au bubbles are seen with the dense molecular tracers HCO+, CS, and HCN around the YSO. We retrieve previously identified structures, like an outflow in HCO+ and another streamer in C2H. Additionally, potential indicators of a second outflow appear in CS and HCN emission, but its nature remains to be confirmed.

Conclusions. The late infall identified at large scales may originate from the nearby prestellar core L1489 and is likely responsible for the formation of an external warped disk in this system. The detection of a potential second outflow could be the direct evidence of a binary system. Finally, we hypothesize that the bubbles may result from the magnetic pressure as observed in numerical simulations.
Asteroseismology of the young open cluster NGC 2516
Authors: Li Gang , Aerts Conny , Bedding Timothy R. , Fritzewski Dario J. , Murphy Simon J. , Van Reeth Timothy , Montet Benjamin T. , Jian Mingjie , Mombarg Joey S. G. , Gossage Seth , Sreenivas Kalarickal R.
Published: April 2024

Context.Asteroseismic modelling of isolated stars presents significant challenges due to the difficulty in accurately determining stellar parameters, particularly the stellar age. These challenges can be overcome by observing stars in open clusters whose coeval members share an initial chemical composition. The light curves from the all-sky survey by the Transiting Exoplanet Survey Satellite (TESS) allow us to investigate and analyse stellar variations in clusters with an unprecedented level of detail for the first time.

Aims.We aim to detect gravity-mode oscillations in the early-type main-sequence members of the young open cluster NGC 2516 to deduce their internal rotation rates.

Methods.We selected the 301 member stars with no more than mild contamination as our sample. We analysed the full-frame image light curves, which provide nearly continuous observations in the first and third years of TESS monitoring. We also collected high-resolution spectra using the Fiber-fed Extended Range Optical Spectrograph for theg-mode pulsators, with the aim of assessing theGaiaeffective temperatures and gravities and preparing for future seismic modelling.

Results.By fitting the theoretical isochrones to the colour-magnitude diagram of a cluster, we determined an age of 102 ± 15 Myr and inferred that the extinction at 550 nm (A0) is 0.53 ± 0.04 mag. We identified 147 stars with surface-brightness modulations: 24 with gravity (g-)mode pulsations (γDoradus or slowly pulsating B-type stars) and 35 with pressure (p-)mode pulsations (δSct stars). When sorted by colour index, the amplitude spectra of theδSct stars show a distinct ordering and reveal a discernible frequency-temperature relationship. The near-core rotation rates, measured from period spacing patterns in two slowly pulsating B-type (SPB) stars and nineγDor stars, reach up to 3 d−1. This is at the high end of the values found fromKeplerdata of field stars of similar variability type. TheγDor stars of NGC 2516 have internal rotation rates as high as 50% of their critical value, whereas the SPB stars exhibit rotation rates close to their critical rate. Although the B-type stars are rotating rapidly, we did not find long-term brightness and colour variations in the mid-infrared, which suggests that there are no disc or shell formation events in our sample. We also discussed the results of our spectroscopic observations for theg-mode pulsators.
Pulsating hydrogen-deficient white dwarfs and pre-white dwarfs observed with TESS
Authors: Calcaferro Leila M. , Sowicka Paulina , Uzundag Murat , Córsico Alejandro H. , Kepler Souza O. , Bell Keaton J. , Althaus Leandro G. , Handler Gerald , Kawaler Steven D. , Werner Klaus
Published: April 2024

Context.Significant advances have been achieved through the latest improvements in the photometric observations accomplished by the recent space missions, which substantially boost the study of pulsating stars via asteroseismology. The TESS mission has already proven to be of particular relevance for pulsating white dwarf and pre-white dwarf stars.

Aims.We report a detailed asteroseismic analysis of the pulsating PG 1159 star NGC 246 (TIC 3905338), which is the central star of the planetary nebula NGC 246, based on high-precision photometric data gathered by the TESS space mission.

Methods.We reduced TESS observations of NGC 246 and performed a detailed asteroseismic analysis using fully evolutionary PG 1159 models computed accounting for the complete prior evolution of their progenitors. We constrained the mass of this star by comparing the measured mean period spacing with the average of the computed period spacings of the models, and we also employed the observed individual periods to search for a seismic stellar model.

Results.We extracted a total of 17 periodicities from the TESS light curves from the two sectors where NGC 246 was observed. All the oscillation frequencies are associated withg-mode pulsations, with periods spanning from ∼1460 to ∼1823 s. We found a constant period spacing of ΔΠ = 12.9 s, which allowed us to deduce that the stellar mass is higher than ∼0.87 M⊙if the period spacing is assumed to be associated withℓ = 1 modes, and that the stellar mass is ∼0.568 M⊙if it is associated withℓ = 2 modes. The less massive models are more consistent with the distance constraint fromGaiaparallax. Although we were not able to find a unique asteroseismic model for this star, the period-to-period fit analyses suggest a high stellar mass (≳0.74M⊙) when the observed periods are associated with modes withℓ = 1 only, and both a high and an intermediate stellar mass (≳0.74 M⊙and ∼0.57 M⊙, respectively) when the observed periods are associated with modes with a mixture ofℓ = 1, 2.
Bias versus variance when fitting multi-species molecular lines with a non-LTE radiative transfer model
Authors: Roueff Antoine , Pety Jérôme , Gerin Maryvonne , Ségal Léontine E. , Goicoechea Javier R. , Liszt Harvey S. , Gratier Pierre , Beslic Ivana , Einig Lucas , Gaudel Mathilde , Orkisz Jan H. , Palud Pierre , Santa-Maria Miriam G. , de Souza Magalhaes Victor , Zakardjian Antoine , Bardeau Sébastien , Bron Emeric , Chainais Pierre , Coudé Simon , Demyk Karine , Guzman Viviana V. , Hughes Annie , Languignon David , Levrier François , Lis Dariusz C. , Le Bourlot Jacques , Le Petit Franck , Peretto Nicolas , Roueff Evelyne , Sievers Albrecht , Thouvenin Pierre-Antoine
Published: April 2024

Context. Robust radiative transfer techniques are requisite for efficiently extracting the physical and chemical information from molecular rotational lines.

Aims. We study several hypotheses that enable robust estimations of the column densities and physical conditions when fitting one or two transitions per molecular species. We study the extent to which simplifying assumptions aimed at reducing the complexity of the problem introduce estimation biases and how to detect them.

Methods. We focus on the CO and HCO+ isotopologues and analyze maps of a 50 square arcminutes field. We used the RADEX escape probability model to solve the statistical equilibrium equations and compute the emerging line profiles, assuming that all species coexist. Depending on the considered set of species, we also fixed the abundance ratio between some species and explored different values. We proposed a maximum likelihood estimator to infer the physical conditions and considered the effect of both the thermal noise and calibration uncertainty. We analyzed any potential biases induced by model misspecifications by comparing the results on the actual data for several sets of species and confirmed with Monte Carlo simulations. The variance of the estimations and the efficiency of the estimator were studied based on the Cramér-Rao lower bound.

Results. Column densities can be estimated with 30% accuracy, while the best estimations of the volume density are found to be within a factor of two. Under the chosen model framework, the peak 12CO (1 – 0) is useful for constraining the kinetic temperature. The thermal pressure is better and more robustly estimated than the volume density and kinetic temperature separately. Analyzing CO and HCO+ isotopologues and fitting the full line profile are recommended practices with respect to detecting possible biases.

Conclusions. Combining a non-local thermodynamic equilibrium model with a rigorous analysis of the accuracy allows us to obtain an efficient estimator and identify where the model is misspecified. We note that other combinations of molecular lines could be studied in the future.
Connecting low-redshift LISA massive black hole mergers to the nHz stochastic gravitational wave background
Authors: Izquierdo-Villalba David , Sesana Alberto , Colpi Monica , Spinoso Daniele , Bonetti Matteo , Bonoli Silvia , Valiante Rosa
Published: April 2024

Pulsar Timing Array (PTA) experiments worldwide recently reported evidence of a nHz stochastic gravitational wave background (sGWB) compatible with the existence of slowly inspiralling massive black hole (MBH) binaries (MBHBs). The shape of the signal contains valuable information about the evolution of z < 1 MBHs above 108 M⊙, suggesting a faster dynamical evolution of MBHBs towards the gravitational-wave-driven inspiral or a larger MBH growth than usually assumed. In this work, we investigate if the nHz sGWB could also provide constraints on the population of merging lower-mass MBHBs (< 107 M⊙) detectable by LISA. To this end, we use the L-Galaxies semi-analytical model applied to the Millennium suite of simulations. We generate a population of MBHs compatible simultaneously with current electromagnetic and nHz sGWB constraints by including the possibility that, in favourable environments, MBHs can accrete gas beyond the Eddington limit. The predictions of this new model for the sGWB show that the global (integrated up to high-z) LISA detection rate is not significantly affected when compared to a fiducial model whose nHz sGWB signal is ∼2 times smaller. In both cases, the global rate yields ∼12 yr−1 and is dominated by systems of 105 − 6 M⊙. The main differences are limited to low-z (z < 3), high-mass (> 106 M⊙) LISA MBHBs. The model compatible with the latest PTA results predicts up to ∼1.6 times more detections, with a rate of ∼1 yr−1. We find that these LISA MBHB systems have 50% probability of shining with bolometric luminosities > 1043 erg s−1. Hence, in case PTA results are confirmed and given the current MBH modelling, our findings suggest there will be higher chances to perform multimessenger studies with LISA MBHB than previously expected.
Discovery of the magnetic cataclysmic variable XMM J152737.4–205305.9 with a deep eclipse-like feature
Authors: Ok Samet , Schwope Axel , Buckley David A. H. , Brink Jaco
Published: April 2024

We report the identification and subsequent examination of a polar-type cataclysmic variable named XMM J152737.4−205305.9 newly discovered with the X-ray Multi-Mirror Mission (XMM-Newton). This discovery was made by matching the XMM-Newton data archive with the cataclysmic variable candidate catalog provided by Gaia Data Release 3 (DR3). The use of X-ray photometry led to the identification of two distinct dips that exhibit a recurring pattern with a precise period of 112.4 (1) min in two XMM-Newton observations made one year apart. The data obtained from photometry provided by the Zwicky Transient Facility (ZTF) and the Asteroid Terrestrial-impact Last Alert System (ATLAS) survey consistently indicate the presence of mass-accretion states that differ by up to 2 mag. Following the optical data, the Spectrum Roentgen Gamma(SRG)/eROSITA All Sky Survey observed the system at two different X-ray levels, which may imply different accretion states. Following these observations, the low-resolution spectrum obtained using SALT spectroscopy exposes the prominent hydrogen Balmer and helium emission lines, strongly supporting the categorization of this system as a polar-type magnetic cataclysmic variable. The XMM-Newton observations conducted at various X-ray levels reveal a consistent pattern of a deep dip-like feature with a width of ≈9.1 min. This feature implies the presence of an eclipse in both observations. According to Gaia data, the object is located at a distance of 1156−339+720 pc, and its X-ray luminosity lies within the LX = (3 − 6)×1031 erg s−1 range.
High-precision astrometry with VVV
Authors: Griggio M. , Libralato M. , Bellini A. , Bedin L. R. , Anderson J. , Smith L. C. , Minniti D.
Published: April 2024

Aims. We use near-infrared, ground-based data from the VISTA Variables in the Via Lactea (VVV) survey to indirectly extend the astrometry provided by the Gaia catalog to objects in heavily extinct regions toward the Galactic bulge and plane that are beyond Gaia’s reach.

Methods. We made use of state-of-the-art techniques developed for high-precision astrometry and photometry with the Hubble Space Telescope to process the VVV data. We employed empirical, spatially variable, effective point spread functions and local transformations to mitigate the effects of systematic errors, like residual geometric distortion and image motion, and to improve measurements in crowded fields and for faint stars. We also anchored our astrometry to the absolute reference frame of Gaia Data Release 3.

Results. We measure between 20 and 60 times more sources than Gaia in the region surrounding the Galactic center, obtaining a single-exposure precision of about 12 mas and a proper-motion precision of better than 1 mas yr−1 for bright, unsaturated sources. Our astrometry provides an extension of Gaia into the Galactic center. We publicly release the astro-photometric catalogs of the two VVV fields considered in this work, which contain a total of ~3.5 million sources. Our catalogs cover ~3 sq. deg, about 0.5% of the entire VVV survey area.
Computed tomography-based prediction of pancreatitis following biliary metal stent placement with the convolutional neural network
Authors: Hamada Tsuyoshi , Yasaka Koichiro , Nakai Yousuke , Fukuda Rintaro , Hakuta Ryunosuke , Ishigaki Kazunaga , Kanai Sachiko , Noguchi Kensaku , Oyama Hiroki , Saito Tomotaka , Sato Tatsuya , Suzuki Tatsunori , Takahara Naminatsu , Isayama Hiroyuki , Abe Osamu , Fujishiro Mitsuhiro
Published: April 2024

Background and study aims Pancreatitis is a potentially lethal
adverse event of endoscopic transpapillary placement of a self-expandable metal stent (SEMS)
for malignant biliary obstruction (MBO). Deep learning-based image recognition has not been
investigated in predicting pancreatitis in this setting.

Patients and methods We included 70 patients who underwent
endoscopic placement of a SEMS for nonresectable distal MBO. We constructed a convolutional
neural network (CNN) model for pancreatitis prediction using a series of pre-procedure
computed tomography images covering the whole pancreas (≥ 120,960 augmented images in total).
We examined the additional effects of the CNN-based probabilities on the following machine
learning models based on clinical parameters: logistic regression, support vector machine with
a linear or RBF kernel, random forest classifier, and gradient boosting classifier. Model
performance was assessed based on the area under the curve (AUC) in the receiver operating
characteristic analysis, positive predictive value (PPV), accuracy, and specificity.

Results The CNN model was associated with moderate levels of
performance metrics: AUC, 0.67; PPV, 0.45; accuracy, 0.66; and specificity, 0.63. When added
to the machine learning models, the CNN-based probabilities increased the performance metrics.
The logistic regression model with the CNN-based probabilities had an AUC of 0.74, PPV of
0.85, accuracy of 0.83, and specificity of 0.96, compared with 0.72, 0.78, 0.77, and 0.96,
respectively, without the probabilities.

Conclusions The CNN-based model may increase predictability for
pancreatitis following endoscopic placement of a biliary SEMS. Our findings support the
potential of deep learning technology to improve prognostic models in pancreatobiliary
therapeutic endoscopy.
Stereoselective Synthesis of Unsymmetrical 1,1-Diborylalkenes
Authors: Lyu Hairong , Lou Xiangyu , Lin Jiaxin
Published: April 2024

1,1-Diborylalkene, a class of important diboryl species, serves as the synthetic precursor of multisubstituted olefin, which is a prevalent building block in natural products, functional materials, and pharmaceuticals. Current methods mainly afford symmetrical 1,1-diborylalkenes, and late-stage differentiation of the two identical boryl groups is required to achieve selective difunctionalization. In comparison, stereoselective synthesis of unsymmetrical 1,1-diborylalkenes (UDBA) are less-explored. This Synpacts article provides a brief summary of the achievements in the synthesis of UDBAs. In particularly, we highlight our recent work on the unsymmetrical 1,1-diborylation of alkynes using a neutral sp2–sp3 diboron reagent to access UDBAs and their controllable stepwise derivatization.

1 Introduction

2 Background: Unsymmetrical 1,1-Diborylalkene Synthesis

3 Stereoselective Unsymmetrical 1,1-Diborylation of Alkynes with a Neutral sp2–sp3 Diboron Reagent

4 Summary and Outlook
Endothelial-Derived Microparticles Associate with Hospital Major Adverse Cardiovascular Events but not with Long-Term Adverse Events in Acute Myocardial Infarction
Authors: Hartopo Anggoro B. , Mayasari Dyah S. , Puspitawati Ira , Putri Astrid K. , Setianto Budi Y.
Published: April 2024

Endothelial-derived microparticles (EDMP) are markers of vascular function and convey roles in coagulation, inflammation, vasoactivity, angiogenesis, and cellular apoptosis, which implicate acute myocardial infarction (AMI). This study aimed to investigate whether, among AMI, on-admission EDMP counts affect hospital major adverse cardiovascular events (MACE) and whether the change of EDMP in 30-day posthospital discharge affects long-term follow-up MACE. The research design was a prospective cohort study. The subjects were 119 patients diagnosed and hospitalized with AMI, who were enrolled consecutively. The EDMP was measured on hospital admission and repeated 30-day posthospital discharge. The outcomes were in the hospital MACE comprised of cardiac mortality, heart failure, cardiogenic shock, reinfarction, and resuscitated ventricular arrhythmia. Furthermore, long-term follow-up were performed on 30-day, 90-day, and 1-year posthospital AMI discharge. The on-admission EDMP counts were significantly higher in subjects with hospital MACE compared with those without (median [interquartile range]: 27,421.0 [6,956.5–53,184.0] vs. 11,617.5 [4,599.0–23,336.7] counts/µL, p = 0.028). The EDMP counts cutoff value of >26,810.0 counts/µL (52.4% sensitivity, 81.6% specificity) had significantly increased hospital MACE occurrence (adjusted odd ratio: 4.45, 95% confidence interval: 1.47–13.53, p = 0.008). The EDMP counts were significantly increased after 30-day posthospital discharge. Both on-admission and 30-day EDMP counts and the changes in EDMP counts did not impact MACE on the long-term follow-up. In conclusion, higher on-admission EDMP counts were independently associated with hospital MACE among AMI. However, on-admission and 30-day postdischarge EDMP and their changes did not impact long-term follow-up MACE.
Design and simulation of a wire quadrupole ion trap for ion trapping and cooling
Authors: Li Ze-Kai , Zhou Yijie , Dong Changwu , Hou Gao-Lei
Published: April 2024

Serving as the core device of an ion trapping system, radiofrequency ion traps are widely employed in chemical reaction dynamics, atomic and molecular physics, precise measurement, and ion spectroscopy. They can store, enrich, and cool ions down to very low temperatures in combination with a cryogenic cooler, thus greatly facilitating the following experiments, such as, high-resolution spectroscopy. In this work, we describe in detail the structural design of a radiofrequency wire quadrupole trap (w4PT) that utilizes six wire electrodes to act as one cylindrical electrode of the conventional quadrupole ion trap to simulate the hyperboloids. We simulated the electric fields and ion motion trajectories within the trap to investigate the performance of the designed w4PT, and showed that it is capable of reaching a tight confinement of ions in a small volume. We also conducted the heat transfer simulations based on the designed supporting platform for the trap, and the chosen materials for the electrodes, trap cavity, and printed circuit boards for installing the electrodes. The simulated temperature distributions showed that the current trap could cool ions to a low temperature below 5 K using a helium cryogenic cooler. This work shall be helpful for the development of ion trap technology to be employed in high-precision spectroscopy.
Development of high-resolution photoelectron imaging with dual-reflection time of flight mass analyzer
Authors: Fei Zejie , Han Changcai , Wang Yongtian , Xu Hui , Hong Jing , Jiang Yihuang , Zhou Yuan , Ju Hechen , Dong Changwu , Liu Hongtao
Published: April 2024

A velocity map imaging photoelectron spectroscopy, coupled with an electrospray ionization source and a dual-reflection time of flight (TOF) mass analyzer has been developed for the investigation of anions in the gas phase. Anions formed in the electrospray source are guided by a radio-frequency quadrupole ion guide into a quadrupole ion trap, where the ions are accumulated. A unique feature of this apparatus involves the coupling of a dual-reflection mass analyzer to the original Wiley-McLaren design. This can effectively improve the mass spectrum resolution, so as to accurately select the target ion. The mass resolution (M/ΔM) above 2000 can be achieved. The velocity map imaging spectrometer resolution is about 5.8 meV full width at half maximum for the photoelectrons with the kinetic energy of 0.59 eV, leading to a relative resolution of ~0.98%. The detailed design, construction, and operation of the new apparatus are presented.
Review and perspective of single-molecule spectroscopy for
chemistry
Authors: Xie Mingyi , Tian Yuxi
Published: April 2024

Single-molecule spectroscopy (SMS) has emerged as a powerful technique more than three decades after its initial optical detection in solid matrices. Over this period, numerous technological advancements have been made, leading to successful implementation of these methods across various scientific disciplines, such as biology, chemistry, physics, and materials. While SMS has found extensive utility in the field of biology, particularly in super-resolution imaging, its application in chemistry remains relatively limited. This review presents a comprehensive overview of the diverse applications of SMS in several areas, highlighting its potential applications in chemistry. Furthermore, we provide a brief perspective on the future development of SMS, emphasizing its promising prospects for advancing chemical research.
Effects of reagent rotational excitation on OH+HCI→CI+H2O reaction
Authors: Xu Xin , Chen Jun , Liu Shu , Zhang Dong H.
Published: April 2024

Potential-averaged fivedimensional (PA5D) time-dependent wave packet calculations have been carried out to obtain the initial state-specific reaction probabilities and rate constants for a series of reactant rotationally excited states of the title reaction on one of our recently developed potential energy surface (F12a PES). It is found that individual excitation of the reactant HC1 to j1=2 or OH to j2=1 yields the largest total reaction probability except for low collision energies. In the low energy region, the resonance enhancement of reaction probability decreases rapidly with the increase of OH rotational excitation, resulting in a rapid decline in the rate constant below 250 K. The rate constant of the simultaneous HC1 and OH rotational excitation is not a simple superposition of the results of the separate excitation. Finally, we obtain the thermal rate constants of the reaction by Boltzmann averaging the rate constants for initial rotational states up to (5, 5), which are in reasonable agreement with the experimental results.
A hermetic on-cryostat helium source for low temperature experiments
Authors: Castoria K. E. , Byeon H. , Theis J. , Beysengulov N. R. , Glen E. O. , Koolstra G. , Sammon M. , Lyon S. A. , Pollanen J. , Rees D. G.
Published: April 2024

We describe a helium source cell for use in cryogenic experiments that is hermetically sealed in situ on the cold plate of a cryostat. The source cell is filled with helium gas at room temperature and, subsequently, sealed using a cold weld crimping tool before the cryostat is closed and cooled down. At low temperatures, the helium condenses and collects in a connected experimental volume, as monitored via the frequency response of a planar superconducting resonator device sensitive to small amounts of liquid helium. This on-cryostat helium source negates the use of a filling tube between the cryogenic volumes and room temperature, thereby preventing unwanted effects such as temperature instabilities that arise from the thermomechanical motion of helium within the system. This helium source can be used in experiments investigating the properties of quantum fluids or to better thermalize quantum devices.
Design of a novel gamma camera with large field of view for 16N diagnosis in the primary loop of nuclear reactor
Authors: Zhang Tao , Tang Lingzhi , Yan Yihong , Bai Xuejie , Wang Dongming , Sun Weiqiang , Jing Futing , Lv Huanwen , Hu Guang , Yan Mingfei , Hu Huasi
Published: April 2024

The assessment of the concentration and distribution of l6N, derived from 16O in the cooling water exposed to neutron irradiation, is essential for ensuring radiation safety during nuclear reactor operation. The imaging method allows for the visualization of the intensity distribution of these l6N by capturing gamma-rays emitted during their decay process. However, the existing gamma camera is exclusively compatible with gamma-rays below 2 MeV. In this paper, a novel gamma camera featuring a thick double-conical penumbra aperture, a pixelated Lu1.8Y0.2SiO5:Ce scintillator array, and a position-sensitive photomultiplier tube is proposed to address this limitation. This innovative design offers a large field of view (FOV) and is suitable for high energy extended gamma source imaging. The optimization of key parameters of the camera was conducted, and a FOV of 60° and an angular resolution of up to 4.57° were achieved. Imaging simulations, including a simplified model of the primary loop of the pressurized-water reactor by GEANT4 code and image reconstruction using the expectation maximum algorithm, demonstrated that the proposed gamma camera could obtain a satisfactory spatial resolution for diagnosing the distribution of 16N in the primary loop of a nuclear reactor.
A linearly implicit energy-stable scheme for critical dissipative surface quasi-geostrophic flows
Authors: Zhao Lei , Zhang Zhiyue
Published: April 2024

In this paper, we propose an effective linearly implicit unconditional energy-stable scheme for surface quasi-geostrophic flows based on the scalar auxiliary variable approach and the Fourier spectral Galerkin method. Compared with traditional numerical methods, our scheme has constant coefficient matrices at each time step, and the numerical solutions are consistent with the dissipation laws for modified energy. By treating linear terms implicitly and nonlinear terms explicitly, we derive the dissipation laws for discrete modified surface kinetic energy and Hamiltonian. To reduce the aliasing error induced by the Fourier spectral Galerkin method, we implement a 2/3 de-aliasing technique for the nonlinear terms. Furthermore, the integration concerning energy in our numerical scheme is exact due to the Fourier spectral Galerkin method. Numerical experiments are presented to verify the stability and efficiency of the proposed scheme.
Estimating the carbon footprint of computational fluid dynamics
Authors: Horwitz J. A. K.
Published: April 2024

Computational resources have grown exponentially in the past few decades. These machines make possible research and design in fields as diverse as medicine, astronomy, and engineering. Despite ever-increasing computational capabilities, direct simulation of complex systems has remained challenging owing to the degrees of freedom involved. At the cusp of exascale computing, high-resolution simulation of practical problems with minimal model assumptions may soon experience a renaissance. However, growing reliance on modern computers comes at the cost of a growing carbon footprint. To illustrate this, we examine historic computations in fluid dynamics where larger computers have afforded the opportunity to simulate flows at increasingly relevant Reynolds numbers. Under a variety of flow configurations, the carbon footprint of such simulations is found to scale roughly with the fourth power of Reynolds number. This is primarily explained by the computation cost in core-hours, which is also described by similar scaling, though regional differences in renewable energy use also play a role. Using the established correlation, we examine a large database of simulations to develop estimates for the carbon footprint of computational fluid dynamics in a given year. Collectively, the analysis provides an additional benchmark for new computations where, in addition to balancing considerations of model fidelity, carbon footprint should also be considered.
Neutrality in the average-atom model
Authors: Faussurier Gérald
Published: April 2024

We consider the neutrality in the framework of the average-atom model. It is shown that it is difficult to ensure the local neutrality inside the Wigner–Seitz sphere and the global neutrality inside all space. If we keep the neutrality of the Wigner–Seitz sphere, there is a small excess or deficit of charge in all space. Numerical examples are given for aluminum, iron, molybdenum, and gold for various compressions as a function of temperature. The small excess or deficit of charge in all space is noticeable in the warm dense matter regime. At high temperature, the neutrality inside the Wigner–Seitz sphere and in all space is restored.
Predicting lift and drag coefficients during hypersonic Mars reentry using hyStrath
Authors: Maigler Maximilian , Pessina Valentina , Schein Jochen
Published: April 2024

During hypersonic reentry, a spacecraft experiences several different fluid flow regimes, which usually require the application of different software frameworks to simulate the respective regimes. This study aims to evaluate the hyStrath library for predicting aerodynamic lift and drag coefficients of complex three-dimensional (3D) geometries during hypersonic Mars reentry, using flight data of the Viking 1 mission as reference. A range of altitudes (h=30−140 km) and Mach numbers (M=13−24) where flight data is available is considered, covering the rarefied, transitional, and continuum fluid flow regimes. The hyStrath library contains a set of modified solvers and state-of-the-art thermophysical and chemistry models within the framework of OpenFOAM, dedicated to modeling high-enthalpy hypersonic flow problems. Depending on the flow regime, the computational fluid dynamics solver hy2Foam or direct-simulation Monte Carlo solver dsmcFoam+ are employed in the study. Because hyStrath is based on OpenFOAM, it allows the use of an unstructured adaptive mesh refinement approach for arbitrary geometries. We obtain excellent results throughout all investigated flow regimes and Mach numbers with an average deviation of 1.5% and 2% from the measured lift and drag coefficients, respectively. The applicability of the framework for accurately modeling both rarefied and continuum Mars reentry problems of complex 3D geometries such as the Viking capsule is demonstrated.
Condensation shock topologies in carbon dioxide and a non-condensable gas mixture in supersonic nozzles
Authors: Restrepo Julián C. , Bolaños-Acosta Andrés F. , Simões-Moreira José R.
Published: April 2024

Condensation shock waves may occur in many flow expansion devices such as turbomachinery, gas ejectors, micro thrust-nozzles, and supersonic gas flow separators. However, their experimental analysis has been barely addressed as condensation shocks comprise complex phenomena such as compressible flow behavior, a shock-like phase transition, and a two-phase flow expansion. This work characterizes experimentally some condensation shock topologies of a mixture of carbon dioxide and dry air at several compositions in a Laval nozzle. Experiments were carried out in a test-rig instrumented with high-response pressure transducers installed along the Laval nozzle wall along with a Schlieren setup equipped with a high-speed video camera imaging the flow behavior within the nozzle. The nozzle wall profile was built by using the method of characteristics developed from a real equation-of-state suited for the testing mixture. Results revealed the influence of the nozzle wall profile on the condensation shock location and topology. Moreover, there types of flow behavior were captured and named as conventional, transition, and Mach wave condensation shocks. The transition from one topology to another occurred due to the interaction between cancelation waves originated from the nozzle wall and the phase-change phenomenon, giving rise to two distinct regions characterized by certain observable droplet population density. The current investigation presents an in-depth phenomenological discussion of the three types of condensation shock topologies as such assessment has not been previously developed.
Transcriptional elongation control of hypoxic response
Authors: Soliman Shimaa Hassan AbdelAziz , Iwanaszko Marta , Zheng Bin , Gold Sarah , Howard Benjamin Charles , Das Madhurima , Chakrabarty Ram Prosad , Chandel Navdeep S. , Shilatifard Ali
Published: April 2024

The release of paused RNA polymerase II (RNAPII) from promoter-proximal regions is tightly controlled to ensure proper regulation of gene expression. The elongation factor PTEF-b is known to release paused RNAPII via phosphorylation of the RNAPII C-terminal domain by its cyclin-dependent kinase component, CDK9. However, the signal and stress-specific roles of the various RNAPII-associated macromolecular complexes containing PTEF-b/CDK9 are not yet clear. Here, we identify and characterize the CDK9 complex required for transcriptional response to hypoxia. Contrary to previous reports, our data indicate that a CDK9 complex containing BRD4 but not AFF1/4 is essential for this hypoxic stress response. We demonstrate that BRD4 bromodomains (BET) are dispensable for the release of paused RNAPII at hypoxia-activated genes and that BET inhibition by JQ1 is insufficient to impair hypoxic gene response. Mechanistically, we demonstrate that the C-terminal region of BRD4 is required for Polymerase-Associated Factor-1 Complex (PAF1C) recruitment to establish an elongation-competent RNAPII complex at hypoxia-responsive genes. PAF1C disruption using a small-molecule inhibitor (iPAF1C) impairs hypoxia-induced, BRD4-mediated RNAPII release. Together, our results provide insight into potentially targetable mechanisms that control the hypoxia-responsive transcriptional elongation.