bluuebunny/crossref_metadata_2025_split huggingface dataset:
Spatially resolving polycyclic aromatic hydrocarbons in Herbig Ae disks with VISIR-NEAR at the VLT
Authors: Yoffe G. , van Boekel R. , Li A. , Waters L. B. F. M. , Maaskant K. , Siebenmorgen R. , van den Ancker M. , dit de la Roche D. J. M. Petit , Lopez B. , Matter A. , Varga J. , Hogerheijde M. R. , Weigelt G. , Oudmaijer R. D. , Pantin E. , Meyer M. R. , Augereau J.-C. , Henning Th. 
Published: March 2023

Context. The emission from polycyclic aromatic hydrocarbons (PAHs) arises from the uppermost layers of protoplanetary disks, higher than the optical/near-infrared scattered light and similar to the emission from the highly thick 12CO millimeter lines. The PAH intensity profiles trace the gas distribution and can constrain the penetration depth of UV radiation.
Aims. We aim to constrain the spatial intensity profiles of the four strongest PAH emission features in the telluric N-band spectral region. Thereby, we seek to constrain the dependence of PAH properties on the (radial) location in the disk, such as charge state, the interrelation with the presence and dynamics of small silicate grains, and the correlation of PAH emission with gas or dust.
Methods. We used the long-slit spectroscopy mode of the VISIR-NEAR experiment to perform diffraction-limited observations of eight nearby Herbig Ae protoplanetary disks. We extracted spectra for various locations along the slit with a spectral resolution of R ≈ 300 and performed a compositional fit at each spatial location using spectral templates of silicates and the four PAH bands. This yields the intensity versus location profiles of each species.
Results. We obtained spatially resolved intensity profiles of the PAH emission features in the N band for five objects (AB Aurigae, HD 97048, HD 100546, HD 163296, and HD 169142). We observe two kinds of PAH emission geometry in our sample: centrally peaked (HD 97048) and ring-like (AB Aurigae, HD 100546, HD 163296, and potentially HD 169142). Comparing the spatial PAH emission profiles with near-infrared scattered light images, we find a strong correlation in the disk substructure but a difference in radial intensity decay rate. The PAH emission shows a less steep decline with distance from the star. Finally, we find a correlation between the presence of (sub)micron-sized silicate grains and the depletion of PAH emission within the inner regions of the disks.
Conclusions. In this work we find the following: (1) PAH emission traces the extent of Herbig Ae disks to a considerable radial distance. (2) The correlation between the presence of silicate emission within the inner regions of disks and the depletion of PAH emission can result from dust-mixing and PAH coagulation mechanisms and competition over UV photons. (3) For all objects in our sample, PAHs undergo stochastic heating across the entire spatial extent of the disk and are not saturated. (4) The difference in radial intensity decay rates between the PAHs and scattered-light profiles may be attributed to shadowing and dust-settling effects, which impact the scattering grains more so than the PAHs.
Possible origin of the non-detection of metastable He I in the upper atmosphere of the hot Jupiter WASP-80b
Authors: Fossati L. , Pillitteri I. , Shaikhislamov I. F. , Bonfanti A. , Borsa F. , Carleo I. , Guilluy G. , Rumenskikh M. S. 
Published: March 2023

Aims. We aim to constrain the origin of the non-detection of the metastable He I triplet at ≈10 830 Å obtained for the hot Jupiter WASP-80b.
Methods. We measure the X-ray flux of WASP-80 from archival observations and use it as input to scaling relations accounting for the coronal [Fe/O] abundance ratio in order to infer the extreme-ultraviolet (EUV) flux in the 200–504 Å range, which controls the formation of metastable He I. We run three-dimensional (magneto) hydrodynamic simulations of the expanding planetary upper atmosphere interacting with the stellar wind to study the impact on the He I absorption of the stellar high-energy emission, the He/H abundance ratio, the stellar wind, and the possible presence of a planetary magnetic field up to 1 G.
Results. For low-stellar-EUV emission, which is favoured by the measured log R′HK value, the He I non-detection can be explained by a solar He/H abundance ratio in combination with a strong stellar wind, by a subsolar He/H abundance ratio, or by a combination of the two. For a high stellar EUV emission, the non-detection implies a subsolar He/H abundance ratio. A planetary magnetic field is unlikely to be the cause of the non-detection.
Conclusions. The low-EUV stellar flux driven by the low [Fe/O] coronal abundance is the likely primary cause of the He I non-detection. High-quality EUV spectra of nearby stars are urgently needed to improve the accuracy of high-energy emission estimates, which would then enable the employment of observations to constrain the planetary He/H abundance ratio and the stellar wind strength. This would greatly enhance the information that can be extracted from He I atmospheric characterisation observations.
Nature of continuum emission in the source of the water maser super-flare G25.65+1.04
Authors: Bayandina O. S. , Burns R. A. , Kurtz S. E. , Moscadelli L. , Sobolev A. M. , Stecklum B. , Val’tts I. E. 
Published: March 2023

Context. The G25.65+1.04 source is one of the few known ‘super-flare’ water masers in the Milky Way, but in contrast to other super-flare sources, it remains the least studied. In fact, even the nature of the source driving the water maser is still unclear.
Aims. With this project, we aim to clarify the composition and properties of the G25.65+1.04 region by means of examining the parameters of the continuum sources and establishing their association with masers of different types.
Methods. Our previous VLA (Karl G. Jansky Very Large Array) observation detected four continuum peaks (VLA 1-4), three of which (VLA 1-3) were closely spaced and presented a linear orientation. However, the observation, which used the VLA B configuration, lacked the spatial resolution to resolve individual sources. A higher-resolution (A configuration) VLA observation of the continuum and spectral lines was conducted in 2019 using the L, S, C, and Ku bands.
Results. For the first time, the continuum source VLA 1 – associated with the flaring water maser – is resolved into two components: VLA 1A and 1B. The component VLA 1A and the water maser are found to spatially coincide and are thought to be powered by the same source, a protostar at an early stage of evolution showing active ejection. We argue that VLA 2 pinpoints an actively ejecting high-mass protostar, as it is associated with a 6.7 GHz methanol maser and a magnetised jet traced by a 22 GHz H2O maser. Highly polarised OH maser emission is detected in the vicinity of VLA 1-2, with the brightest OH maser found in VLA 2. The magnetic field, identified from the OH maser emission, ranges from ∼ + 0.4 mG in VLA 1A to ∼ − 8 mG in VLA 2.
Conclusions. The G25.65+1.04 region is found to consist of at least two young stellar objects: VLA 1A and VLA 2. Both sources are found to be at an active accretion and ejection stage of evolution.
Modeling contact binaries
Authors: Fabry M. , Marchant P. , Langer N. , Sana H. 
Published: March 2023

Context. It is common for massive stars to engage in binary interactions. In close binaries, the components can enter a contact phase, when both stars simultaneously overflow their respective Roche lobes. While observational constraints on the stellar properties of such systems exist, the most detailed stellar evolution models that feature a contact phase are not fully reconcilable with those measurements.
Aims. We aim to consistently model the contact phases of binary stars in a 1D stellar evolution code. To this end, we have developed a methodology to account for energy transfer in the common contact layers.
Methods. We implemented an approximative model for energy transfer between the components of a contact binary based on the von Zeipel theorem in the stellar evolution code MESA. We compared structure and evolution models both with and without this transfer. We then analyzed the implications for the observable properties of the contact phase.
Results. Implementing energy transfer helps in eliminating baroclinicity in the common envelope between the components of a contact binary, which (if present) would drive strong thermal flows. We find that accounting for energy transfer in massive contact binaries significantly alters the mass ratio evolution and can extend the lifetime of an unequal mass ratio contact system.
Wie kann die biologische Dosimetrie in Fällen unklarer Strahlenbelastung helfen?
Authors: Bucher Martin , Oestreicher Ursula 
Published: March 2023

ZusammenfassungBei einer unklaren, übermäßigen Exposition durch ionisierende Strahlung am Menschen bietet
die biologische Dosimetrie die Möglichkeit, diese retrospektiv nachzuweisen und gegebenenfalls
zu quantifizieren. Besonders hilfreich ist dies in Fällen, in denen keine physikalische
Dosisrekonstruktion möglich ist oder widersprüchliche Ergebnisse vorliegen.Grundlage für die biologische Dosimetrie sind zelluläre Reaktionen, DNA-Schäden und Fehlreparaturen nach einer Exposition gegenüber ionisierender Strahlung. Die in der biologischen Dosimetrie eingesetzten Methoden weisen diese Veränderungen nach und setzen sie anhand von Dosis-Effekt-Kurven ins Verhältnis zur Expositionsdosis. Die Analyse von dizentrischen Chromosomen hat sich als zuverlässigste und empfindlichste Methode für den Nachweis einer Exposition mit ionisierender Strahlung erwiesen, weil sie eine niedrige spontane Häufigkeit aufweist und für ionisierende Strahlung charakteristisch ist. Die Nachweisgrenze für eine homogene Ganzkörperbestrahlung liegt bei 0,1 Gy bei der Auswertung von 500–1000 Zellen für locker ionisierende γ-Strahlung. Die Analyse erfolgt im Speziallabor nach international standardisierten Verfahren.Die biologische Dosimetrie kommt als unabhängige Methode oder zur Ergänzung der physikalischen Dosimetrie zum Einsatz. Da bei der biologischen Dosimetrie die Wirkung der Dosis im Blut erfasst wird, können wertvolle Erkenntnisse zur Strahlenexposition geliefert werden und die medizinische Versorgung von Betroffenen unterstützt werden.
Transition-Metal-Catalyzed Directed C8–H Carbon–Carbon Bond Formation in Quinolines and 1,2,3,4-Tetrahydroquinolines
Authors: Punniyamurthy Tharmalingam , Basak Shubhajit , Paul Tripti , Mandal Santu , Karjee Pallab , Nanjegowda Maniya Vadakanamala 
Published: March 2023

AbstractC8-Substituted quinoline (QN) and 1,2,3,4-tetrahydroquinoline (THQ) scaffolds are featured in numerous bioactive compounds and natural products. Appreciable efforts have been made towards the development of elegant techniques to functionalize the C8–H bond of QNs and THQs. The transition-metal-catalyzed chelation-assisted C–H activation strategy has emerged as an effective synthetic tool among existing methods. This review focuses on recent advances in transition-metal-catalyzed directed carbon–carbon bond forming reactions for the C8–H functionalization of QNs and THQs (till February 2023). The discussion has been categorized based on the type of reaction.1	Introduction2	Acylation3	Alkylation4	Alkenylation5	Alkynylation6	Allylation7	Annulation8	Arylation9	Conclusion and Outlook
Oxa-di-π-methane Rearrangement of a Substrate Embodying the Platencin Core Provides the Decahydro-1H-cyclopenta[c]indene Framework Associated with Various Diterpenes and Certain Lycopodium Alkaloids
Authors: Banwell Martin G. , Ye Sebastian Young , Khan Faiyaz , Gardiner Michael G. , Lan Ping 
Published: March 2023

AbstractA chemoenzymatic approach to the title framework is reported. The reaction sequence starts with the whole-cell biotransformation of iodobenzene and the conversion of the resulting homochiral metabolite into a triene that engages in an intramolecular Diels–Alder reaction and so affording an adduct embodying the platencin core. Application of an oxa-di-π-methane rearrangement to a derivative of this core affords a cyclopropannulated form of the target framework; the latter is then obtained through a TMSI-mediated cleavage of the three-membered ring. A strategy for the assembly of the enantiomeric framework is also described.
Martin Silicates as Versatile Radical Precursors in Photoredox/ Nickel Dual Catalysis
Authors: Wiethoff Maxim-Aleksa , Abdellaoui Mehdi , Lemière Gilles , Ollivier Cyril , Fensterbank Louis , Deis Thomas , Corcé Vincent 
Published: March 2023

AbstractA cross-coupling methodology is described based on the nickel-catalyzed connection of an aryl moiety to an alkyl radical generated by photoinduced single-electron oxidation of a silicate formed from a Martin spirosilane. Complementary to the other anionic radical precursors in photoredox catalysis, Martin silicates permit access to highly reactive alkyl radicals directly engageable in smooth C(sp2)–C(sp3) bond-formation reactions.
The Medial Sural Artery Perforator Flap versus Other Free Flaps in Head and Neck Reconstruction: A Systematic Review
Authors: Al Omran Yasser , Evans Ellie , Jordan Chloe , Borg Tiffanie-Marie , AlOmran Samar , Sepehripour Sarvnaz , Akhavani Mohammed Ali 
Published: March 2023

AbstractThe medial sural artery perforator (MSAP) flap is a versatile fasciocutaneous flap, and yet is less commonly utilized than other free flaps in microvascular reconstructions of the head and neck. The aim is to conduct a high-quality Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA)– and Assessment of Multiple Systematic Reviews 2 (AMSTAR 2)–compliant systematic review comparing the use of the MSAP flap to other microvascular free flaps in the head and neck. Medline, Embase, and Web of Science databases were searched to identify all original comparative studies comparing patients undergoing head and neck reconstruction with an MSAP flap to the radial forearm free flap (RFFF) or anterolateral thigh (ALT) flap from inception to February 2021. Outcome studied were the recipient-site and donor-site morbidities as well as speech and swallow function. A total of 473 articles were identified from title and abstract review. Four studies met the inclusion criteria. Compared with the RFFF and the ALT flaps, the MSAP flap had more recipient-site complications (6.0 vs 10.4%) but less donor-site complications (20.2 vs 7.8%). The MSAP flap demonstrated better overall donor-site appearance and function than the RFFF and ALT flaps (p = 0.0006) but no statistical difference in speech and swallowing function following reconstruction (p = 0.28). Although higher quality studies reviewing the use of the MSAP flap to other free flaps are needed, the MSAP flap provides a viable and effective reconstructive option and should be strongly considered for reconstruction of head and neck defects.
Residual Venous Obstruction as an Indicator of Clinical Outcomes following Deep Vein Thrombosis: A Management Study
Authors: Iding Aaron F. J. , Kremers Bram M. M. , Pallares Robles Alejandro , ten Cate Hugo , ten Cate-Hoek Arina J. 
Published: March 2023

Background Residual venous obstruction (RVO) is considered a risk factor of recurrence and possibly other clinical outcomes following deep vein thrombosis (DVT). Current guidelines do not support an RVO-tailored duration of anticoagulant therapy; contemporary data of such management strategies are scarce. We aimed to evaluate an RVO-based management strategy and to assess associations of RVO with recurrence, post-thrombotic syndrome (PTS), arterial events and cancer. To gain further insight, D-dimer levels were measured 1 month after stopping anticoagulant therapy.
Methods Consecutive patients with symptomatic, proximal DVT were treated in a 2-year clinical care pathway (CCP) at Maastricht University Medical Center and were followed up to 5 years. RVO was assessed at the end of regular duration of anticoagulant therapy, which was extended once if RVO was detected. The study was approved by the medical ethics committee.
Result From a total of 825 patients, 804 patients (97.5%) completed the CCP and 755 (93.9%) were available for extended follow-up. Most patients (76.5%) stopped anticoagulant therapy. Incidence rates of recurrence, PTS, arterial events, and cancer were 4.4, 11.9, 1.7, and 1.8 per 100 patient-years, respectively. RVO was independently associated with PTS (hazard ratio [HR]: 1.66 [1.19–2.32]) and arterial events (HR: 2.07 [1.18–3.65]), but not with recurrence or cancer. High D-dimer was associated with recurrence (HR: 3.51 [2.24–5.48]).
Conclusion Our RVO-based management strategy might have attenuated the association of RVO with recurrence. In addition, RVO identified patients at increased risk of PTS and arterial events, which might be used to identify patients in need of alternative treatment strategies.
Adventures in the Chemistry of 1,1-Diacylcyclopropanes
Authors: Langer Peter 
Published: March 2023

AbstractThe present personalized account aims to highlight 1,1-diacylcyclopropanes as synthetic building blocks or target molecules. The chemistry presented includes cyclization reactions of 1,1-diacylcyclopropanes with free and masked dianions to give spirocyclopropanes as products or reactive intermediates that readily undergo ring-cleavage reactions. In addition, the synthesis of cyclopropylated 1,3,5-tricarbonyl compounds, containing two 1,1-diacylcyclopropane moieties, is discussed. Based on this work also other syntheses of cyclopropanes were developed.1 Introduction2 Reactions of Masked Dianions3 Reactions of Free Dianions4 Cyclopropylated 1,3,5-Tricarbonyl Compounds5 Miscellaneous6 Conclusions
Identification of a de novo Mutation in TMEM106B in a Saudi Child Causes Hypomyelination Leukodystrophy
Authors: Alotaibi Lena , Alqasmi Amal 
Published: March 2023

AbstractHypomyelinating leukodystrophies are one of the white matter disorders caused by a lack of myelin deposition in the central nervous system (CNS). Here, we report the first case of hypomyelinating leukodystrophy in the Middle East and Saudi Arabia. This condition is caused by a mutation in the TMEM106B gene (HLD16; MIM 617964). Hypotonia, congenital nystagmus, delayed motor development, and delayed speech are the main clinical manifestations. The affected patient has mild pyramidal syndrome, a mild intellectual disability, ataxic gait, hyperreflexia, intention tremor, dysmetria, and other motor difficulties. Findings from neuroimaging reveal severe, ongoing, and diffuse hypomyelination identified via the whole exome sequencing, a harmful missense mutation in the TMEM106B gene that is heterozygous. The patient is the offspring of two unrelated persons. The protein's cytoplasmic domain contains a variation that is located in highly conserved residues. In an oligodendroglial cell line, the mutant protein significantly lowered the mRNA production of important myelin genes, decreased branching, and increased cell mortality. TMEM106B is abundantly expressed in neurons and oligodendrocytes in the CNS and is localized in the late endosome and lysosome compartments. TMEM106B levels can be controlled at the transcriptional level through chromatin modification, at the mRNA level through miRNAs, and at the protein level through lysosomal functions. Our findings reveal a novel role of zinc homeostasis in oligodendrocyte development and myelin production and show that variations in TMEM163 induce hypomyelination leukodystrophy.
Does Chemical Shift Magnetic Resonance Imaging Improve Visualization of Pars Interarticularis Defect?
Authors: Smith Emily , Nischal Neha , Murphy Jennifer , Azzopardi Christine , Iyengar Karthikeyan P. , Haleem Shahnawaz , Botchu Rajesh 
Published: March 2023

Abstract
Introduction A unilateral or bilateral pars interarticularis defect (spondylolysis) is a leading cause of axial back pain in adolescent athletes. Currently, a spectrum of imaging modalities is used for assessment of pars interarticularis defects.
Objectives The aim of this study is to compare the accuracy of chemical shift sequence (magnetic resonance imaging [MRI]) technique to conventional MRI sequences in the detection of pars defects.
Patients and Methods Conventional T1, T2, and short tau inversion recovery sagittal and axial, as well as “in-” and “out-” phase chemical shift sagittal MRI sequences of 70 consecutive patients referred for low back pain were reviewed. Demographic details, clinical indication, and presence/diagnosis of pars defects using a 5-point Likert scale on both conventional and chemical shift MRI sequences. Spearman's correlation was used for statistical analysis. Intraclass correlation coefficient analysis was evaluated to assess the intraclass reliability between observers. Data were analyzed using DATAtab web-based statistics software (2022).
Results A total of 70 patients with an average age of 54.34 years with a female predominance were included. There were 11 pars defects in the cohort. Both in and out phases of chemical shift imaging were able to identify pars defect and intact pars. However, out phase was relatively better in delineating pars defects, while the in phase was superior in identifying an intact pars, though this was not statistically significant. There was good intra- and interobserver reliabilities.
Conclusion Chemical shift MRI sequence is a quicker, complementary technique to assess and analyze pars interarticularis confidently than conventionally utilized MRI sequences in patients being evaluated for axial back pain.
Value-added-tax rate increases: A comparative study using difference-in-difference with an ARIMA modeling approach
Authors: Mgammal Mahfoudh Hussein , Al-Matari Ebrahim Mohammed , Alruwaili Talal Fawzi 
Published: March 2023

AbstractCollecting and managing taxes is a critical keystone to protecting a country’s financial intensity and developing a country’s tax system, where value-added tax (VAT) has proven to be a nurturing and steady foundation of income for governments. VAT is a primary source of financial gain in developing nations, which differs from economic income in developed nations, where economic income is primarily derived from tax income. This study examines the influence of the new VAT on non-financial Saudi-listed companies. We compared and examined the impact of the newly introduced 15% VAT in various non-financial sectors. Using charts, tables, appropriate variance analysis, and ARIMA model in the Difference in Difference approach. Regarding data, we targeted 2019 before the new VAT, the discovery of COVID-19, and 2020 after the new VAT and during the COVID-19 pandemic. Results show that a sharp increase in VAT (with other unmeasured variables in this study) has a significant positive/negative impact on inter-industry volatility in corporate financial reporting metrics and was even more dramatic with the COVID-19 disaster. The proposed 10% VAT increase has caused significant fluctuations in companies’ metrics, for example, a decrease in average profits—2.16%, an escalation in more inactive companies, and a higher probability of bankruptcy among companies. Such an outcome would undoubtedly affect unemployment and possibly lead to a reduction in tax revenues in the long run. The consequences of an unexpected VAT increase raise the question of whether they accurately reflect the natural tax system in Saudi Arabia. Therefore, the Saudi government may consider the practical implications of outcomes before taking the next step in interventions in non-financial sectors.