bluuebunny/crossref_metadata_2025 huggingface dataset:
Identification and engineering efflux transporters for improved L-homoserine production in Escherichia coli
Authors: Ding Chao , Zhang Jiwei , Qiao Jinfang , Ma Zhenping , Liu Pi , Liu Jun , Liu Qingdai , Xu Ning
Published: April 2023

Aims

This study aimed to functionally identify the potential L-homoserine transporters in Escherichia coli, and to generate the promising beneficial mutants by targeted directed evolution for improving the robustness and efficiency of microbial cell factories.

Methods and results

By constructing a series of gene deletion and overexpression strains, L-homoserine tolerance assays revealed that RhtA was an efficient and major L-homoserine exporter in E. coli, whereas RhtB and RhtC exhibited relatively weak transport activities for L-homoserine. Real-time RT-PCR analysis suggested that the expression levels of these three target mRNAs were generally variably enhanced when cells were subjected to L-homoserine stress. Based on in vivo continuous directed evolution and growth-couple selections, three beneficial mutations of RhtA exporter (A22V, P119L, and T235I) with clearly increased tolerance against L-homoserine stress were quickly obtained after two rounds of mutagenesis-selection cycles. L-homoserine export assay revealed that the RhtA mutants exhibited different degrees of improvement in L-homoserine export capacity. Further studies suggested that a combination of these beneficial sites led to synergistic effects on conferring L-homoserine-resistance phenotypes. Moreover, the introduction of RhtA beneficial mutants into the L-homoserine-producing strains could facilitate increased amounts of L-homoserine in the shake-flask fermentation.

Conclusions

In this study, we provided further evidence that RhtA serves as a major L-homoserine exporter in E. coli, and obtained several RhtA beneficial mutants, including A22V, P119L, and T235I that contributed to improving the L-homoserine resistance phenotypes and the production efficiency in microbial chassis.
Sheep with ovarian androgen excess have fibrosis and follicular arrest with increased mRNA abundance for steroidogenic enzymes and gonadotropin receptors
Authors: Abedal-Majed Mohamed A , Abuajamieh Mohannad , Al-Qaisi Mohmmad , Sargent Kevin M , Titi Hosam H , Alnimer Mufeed A , Abdelqader Anas , Shamoun Ahmad I , Cupp Andrea S
Published: April 2023

An androgen excess ovarian micro-environment may limit follicle progression in sheep. Two populations of ewes with divergent follicular fluid androstenedione (A4) were identified in a flock in Jordan: High A4; (A4) ≥ 30 ng/mL, (N = 12) or Control A4 (Control); A4 ≤ 15 ng/mL; (N = 12). We hypothesized High A4 ewes would have increased steroidogenic enzyme mRNA abundance, inflammation, and follicular arrest. Messenger RNA abundance for steroidogenic enzymes StAR, CYP17A1, CYP11A1, and HSD3B1 were increased in theca cells while CYP17A1, CYP19A1, and HSD3B1 were increased in granulosa cells in High A4 ewes compared to Control. Gonadotropin receptor mRNA expression for LHCGR was increased in theca and FSHR in granulosa in High A4 ewes. Messenger RNA expression of FOS when reduced, increases expression of CYP17A1 which was observed in High A4 granulosa cells compared to Control. Furthermore, High A4 ewes had greater numbers of primordial follicles (P < 0.001) and fewer developing follicles compared to Control before, and after 7 d of culture, indicating follicular arrest was not alleviated by cortex culture. Increased fibrosis in the ovarian cortex was detected in High A4 ewes relative to Control (P < 0.001) suggesting increased inflammation and altered extracellular matrix deposition. Thus, this High A4 ewes population has similar characteristics to High A4 cows and women with polycystic ovary syndrome suggesting that naturally occurring androgen excess occurs in multiple species and may be a causative factor in follicular arrest and subsequent female sub- or infertility.
Implementing the National Dense Breast Reporting Standard, Expanding Supplemental Screening Using Current Guidelines, and the Proposed Find It Early Act
Authors: Berg Wendie A , Seitzman Robin L , Pushkin JoAnn
Published: April 2023

Thirty-eight states and the District of Columbia (DC) have dense breast notification laws that mandate varying levels of patient notification about breast density after a mammogram, and these cover over 90% of American women. On March 10, 2023, the Food and Drug Administration issued a final rule amending regulations under the Mammography Quality Standards Act for a national dense breast reporting standard for both patient results letters and mammogram reports. Effective September 10, 2024, letters will be required to tell a woman her breasts are “dense” or “not dense,” that dense tissue makes it harder to find cancers on a mammogram, and that it increases the risk of developing cancer. Women with dense breasts will also be told that other imaging tests in addition to a mammogram may help find cancers. The specific density category can be added (eg, if mandated by a state “inform” law). Reports to providers must include the Breast Imaging Reporting and Data System density category. Implementing appropriate supplemental screening should be based on patient risk for missed breast cancer on mammography; such assessment should include consideration of breast density and other risk factors. This article discusses strategies for implementation. Currently 21 states and DC have varying insurance laws for supplemental breast imaging; in addition, Oklahoma requires coverage for diagnostic breast imaging. A federal insurance bill, the Find It Early Act, has been introduced that would ensure no-cost screening and diagnostic imaging for women with dense breasts or at increased risk and close loopholes in state laws.
The applications of hybrid approach combining exact method and evolutionary algorithm in combinatorial optimization
Authors: Duan Suling , Jiang Shanlin , Dai Huan , Wang Luping , He Zhenan
Published: April 2023

Combinatorial optimization problems have very important applications in information technology, transportation, economics, management, network communication, and other fields. Since the problem size in real-scenario application is in large-scale, the demand for real-time and efficient solving approaches increases rapidly. The traditional exact methods guarantee the optimality of the final solution, but these methods can hardly solve the problem in acceptable time due to extremely high computational costs. Heuristic approaches can find feasible solutions in a limited time, while these approaches cannot meet the demand of solution quality. In recent years, hybrid algorithms based on exact methods and heuristic algorithms show outstanding performance in solving large-scale combinatorial optimization problems. The hybridization not only overcomes the shortcomings from single algorithm but also fully utilizes the search ability for population-based approaches as well as the interpretability in exact methods, which promotes the application of combinatorial optimization in real-world problems. This paper reviews existing studies on hybrid algorithms combining exact method and evolutionary computation, summarizes the characteristics of the existing algorithms, and directs the future research.
Experimental study on the receiving piezoelectric vibrator of azimuthal acoustic logging
Authors: Lu Junqiang , Men Baiyong , Che Xiaohua
Published: April 2023

The performance of the azimuthal receiving piezoelectric vibrator has a major impact on the azimuthal acoustic logging tool. The evaluation of the performance and selective preference of piezoelectric vibrators through experimental methods will help improve the measurement accuracy of the tool. A heating tester was developed to test the static capacitance, resonant frequency, admittance and receiving amplitude of the vibrator at different temperatures. Far-field underwater acoustic tests were used to analyse the peak-to-peak amplitude, sensitivity and −3 dB angle of the vibrator and to determine the amplitude correction coefficients of each vibrator. The horizontal directivity of the azimuthally receiving phased subarray was also tested. Compared with the values at room temperature, the resonant frequency of the piezoelectric vibrator decreases by 9.20%, the static capacitance increases by 21.33% and the amplitude increases by 5.29% at a high temperature of 155°C. The underwater acoustic test showed that the main lobe of the receiving directional characteristic of the vibrator is symmetrical along the 0° main maximum direction, the −3 dB angle of the main lobe is 115°–142° and the average sensitivity level is −209.38 dB. The −3 dB angle of the receiving subarray is 66° and 60° without and with phase delay, respectively, and the energy of the received waveform is significantly increased. The piezoelectric vibrator can function stably at high temperatures, and its performance can be recovered after heating. It has good azimuthal resolution and high sensitivity, but the amplitude response has some discretion which needs to be corrected.
Efficacy of regional anesthesia in hip preservation surgeries: a systematic review
Authors: Banks Evan M , Ayisi Jake A , Feroe Aliya G , Alrayashi Walid , Yen Yi-Meng , Novais Eduardo N , Hassan Mahad M
Published: April 2023

The purpose of this study was to review the current literature on perioperative pain management in hip arthroscopy, periacetabular osteotomy and surgical hip dislocation. A systematic review of the literature published from January 2000 to December 2022 was performed. Selection criteria included published randomized controlled trials, prospective reviews and retrospective reviews of all human subjects undergoing hip preservation surgery. Exclusion criteria included case reports, animal studies and studies not reporting perioperative pain control protocols. Thirty-four studies included hip arthroscopy in which peripheral nerve blocks were associated with a significant reduction in pain score (P = 0.037) compared with general anesthesia alone. However, no pain control modality was associated with a significant difference in postanesthesia care unit opioid use (P = 0.127) or length of stay (P = 0.251) compared with general anesthesia alone. Falls were the most common complication reported, accounting for 37% of all complications. Five studies included periacetabular osteotomy and surgical hip dislocation in which peripheral nerve blocks were associated with an 18% reduction in pain on postoperative Day 2, a 48% reduction in cumulative opioid use on postoperative Day 2 and a 40% reduction in hospital stay. Due to the low sample size of the periacetabular osteotomy and surgical hip dislocation studies, we were unable to determine the significant difference between the means. Due to significant between-study heterogeneity, additional studies with congruent outcome measures need to be conducted to determine the efficacy of regional anesthesia in hip arthroscopy, periacetabular osteotomy and surgical hip dislocation.
Versatile microbial communities rapidly assimilate ammonium hydroxide-treated plastic waste
Authors: Schaerer Laura G , Wood Emily , Aloba Sulihat , Byrne Emily , Bashir M Aamir , Baruah Kaushik , Schumann Elizabeth , Umlor Libby , Wu Ruochen , Lee Hyeonseok , Orme Christopher J , Wilson Aaron D , Lacey Jeffrey A , Ong Rebecca G , Techtmann Stephen M
Published: April 2023

Waste plastic presently accumulates in landfills or the environment. While natural microbial metabolisms can degrade plastic polymers, biodegradation of plastic is very slow. This study demonstrates that chemical deconstruction of polyethylene terephthalate (PET) with ammonium hydroxide can replace the rate limiting step (depolymerization) and by producing plastic-derived terephthalic acid and terephthalic acid monoamide. The deconstructed PET (DCPET) is neutralized with phosphoric acid prior to bioprocessing, resulting in a product containing biologically accessible nitrogen and phosphorus from the process reactants. Three microbial consortia obtained from compost and sediment degraded DCPET in ultrapure water and scavenged river water without addition of nutrients. No statistically significant difference was observed in growth rate compared to communities grown on DCPET in minimal culture medium. The consortia were dominated by Rhodococcus spp., Hydrogenophaga spp., and many lower abundance genera. All taxa were related to species known to degrade aromatic compounds. Microbial consortia are known to confer flexibility in processing diverse substrates. To highlight this, we also demonstrate that two microbial consortia can grow on similarly deconstructed polyesters, polyamides, and polyurethanes in water instead of medium. Our findings suggest that microbial communities may enable flexible bioprocessing of mixed plastic wastes when coupled with chemical deconstruction.
Embryo Loss and Moral Status
Authors: Delaney James
Published: April 2023

There is a significant debate over the moral status of human embryos. This debate has important implications for practices like abortion and IVF. Some argue that embryos have the same moral status as infants, children, and adults. However, critics claim that the frequency of pregnancy loss/miscarriage/spontaneous abortion shows a moral inconsistency in this view. One line of criticism is that those who know the facts about pregnancy loss and nevertheless attempt to conceive children are willing to sacrifice embryos lost for the healthy children they ultimately have. I respond to this criticism and argue that on the most plausible accounts of well-being, these embryos are not made worse off and thus not “sacrifices.” I then make some more general remarks about what people’s typical views about pregnancy loss show about their views toward the moral status of embryos.
When Words Fail: “Miscarriage,” Referential Ambiguity, and Psychological Harm
Authors: Bohn Jessalyn A
Published: April 2023

Despite significant efforts to support those bereaved by intrauterine death, they remain susceptible to avoidable psychological harm such as disenfranchised grief, misplaced guilt, and emotional shock. This is in part because the words available to describe intrauterine death—“miscarriage,” “spontaneous abortion,” and “pregnancy loss”—are referentially ambiguous. Despite appearing to refer to one event, they can refer to two distinct events: the baby’s death and his preterm delivery. Disenfranchised grief increases when people understand “miscarriage” as the physical process of preterm delivery alone, for this obscures the baby’s death and excludes non-gestational parents, such as the father. Additionally, focusing on the delivery reinforces the mistaken idea that a gestational mother bears responsibility for her baby’s death, increasing misplaced guilt. When these terms instead shift the focus to the baby’s intrauterine death rather than the preterm delivery, they can obscure the physically difficult and often traumatic experience women have when they deliver their dead children, leaving women shocked by preterm delivery’s physical reality. Given their outsized role in framing the bereaved’s experiences, and their duty to avoid harming their patients, healthcare practitioners in particular should take special care to discuss intrauterine death and preterm delivery appropriately with patients and their families. Changing language to describe intrauterine death and preterm delivery clearly and precisely helps mitigate disenfranchised grief, misplaced guilt, and shock, while also helping to reframe the social response to intrauterine death, making it more obvious why certain steps, such as allowing bereavement leave following an intrauterine death, promote healing.
The Mereotopology of Pregnancy
Authors: Finn Suki
Published: April 2023

Consider the following two metaphysical questions about pregnancy: (1) When does a new organism of a certain kind start to exist? (2) What is the mereological and topological relationship between the pregnant organism and with what it is pregnant? Despite assumptions made in the literature, I take these questions to be independent of each other, such that an answer to one does not provide an answer to the other. I argue that the way to connect them is via a maximality principle that prevents one organism being a proper part of another organism of the same kind. That being said, such a maximality principle need not be held, and may not apply in the case of pregnancy. The aims of this paper are thus to distinguish and connect these metaphysical questions, in order to outline a taxonomy of rival mereotopological models of pregnancy that result from the various combinations of their answers.
Semantic Incorporation in English Singular Indefinites
Authors: Srinivas Sadhwi , Rawlins Kyle
Published: April 2023

In this paper, we introduce a class of exceptionally narrow-scoping singular indefinites in English (e.g., “Sam drove a car for several years before switching to a truck”), which pattern more closely with what have been termed “weak definites” in the literature (e.g., Poesio, 1994; Carlson et al., 2006) than with regular indefinites. While the existence of such exceptional “weak” indefinites has been previously anticipated by Klein et al. (2013), the category is difficult to distinguish from simple narrow-scoped singular indefinites in most contexts. Here, we argue that there is one environment where weak singular indefinites can be distinctively identified: namely, when they appear with for-adverbials. We sketch a concrete implementation of a semantic incorporation-based account for such nominals, bringing them analytically in line with incorporation analyses of weak definites, building closely on the ideas in Dayal (2011). We further briefly discuss how the proposed analysis adjudicates between two competing analyses for for-adverbials, one which assumes that for encodes a universal quantifier (e.g., Deo & Piñango, 2011) and another which takes for to be non-quantificational (e.g., Champollion, 2013), in favor of the latter view. We close by considering some remaining issues surrounding semantically incorporated DPs in English: specifically, how weak (in) definites relate to other nominals that receive covarying interpretations across contexts—such as bare plurals on the one hand (which we do not take to be semantically incorporated) and bare singulars on the other.
Application of Health Belief Model: demographic factors affecting body mass index (BMI) and perceptions of weight management among Malaysians
Authors: Raman Sivasankari , Ong Siew Chin , See Ooi Guat
Published: April 2023

Objectives

The previous studies underlined the need for specified educational intervention programs to prevent overweight and obesity problems among Malaysians. Therefore, in this context, this study aimed to explore the demographic factors that are associated with BMI and perceptions of body weight management among Malaysians by utilizing the Health Belief Model (HBM). The findings of the study will help in developing effective interventions and provide more specific recommendations on weight management in health education programs to ensure the well-being of the people.

Methods

A questionnaire-based cross-sectional study was conducted to study the demographical factors and perception of body weight management by the self-administered Health Belief Model Questionnaire (HBMQ). The data were collected using the HBMQ via Google Form link which was promoted on social media platforms to reach out to the public from all over the 13 states in Malaysia.

Key findings

Out of 440 respondents, 44 (10.0%) were obese, 92 (20.90%) were overweight, 60 (13.60%) were underweight and 244 (55.50%) had normal weight. Significant associations were observed between body mass index (BMI) and demographic characteristics such as age range, gender, education level, marital status, employment status, intention to reduce weight, and health issues (P < 0.05). A statistically significant difference was observed between HBM subscales and different demographic characteristics. The regression model explained ~8.3% of the variance in BMI (P < 0.001) and revealed that perceived severity and behavioural intention were the significant variables to predict a person’s BMI.

Conclusion

The findings in this study conclude that Malaysians with different demographic characteristics have different perceptions on obesity and weight reduction behaviours.
Parental willingness to COVID-19 vaccination among 5- to 11-year-old children in Jordan
Authors: Mayyas Fadia
Published: April 2023

Objectives

Although an emergency approval for Coronavirus Disease 2019 (COVID-19) vaccine was given for 5- to 15-year-old children, there is a public hesitancy to give it for children. This study aimed to investigate parental willingness to COVID-19 vaccine among 5- to 11-year-old children.

Methods

A cross-sectional study using a self-administered questionnaire was distributed to parents from Jordan through social media and at the paediatric clinics.

Key findings

Six hundred and sixty-two parents participated. The mean age was 42.3 ± 2.9 years old and 67% of them were mothers. Around 60% of parents had 5- to 11-year-old children, 56% had children under 5 years, and 49.5% had 12- to 18-year-old children. About 89% of parents and 20% of their 12–18 years children had received COVID-19 vaccine. Only 37% of parents thought that COVID-19 vaccines are safe in children. Only 36/399 parents accepted the vaccine for their 5–11 years children and 232/339 rejected it. The acceptance number increased to 171 if the vaccine was a condition for school admission. Potential long-term unknown side effect was the most reported concern. Independent factors correlated with parental willingness to 5–11 years children vaccination were having a high income, having had children vaccinated to influenza vaccine, and trusting information from the government. Whereas concern of side effects was associated with vaccine rejection.

Conclusion

Vaccine acceptance for 5- to 11-year-old children is a major issue among parents. The current study could assist the policymakers in Jordan to undertake strategies to encourage children vaccination to confine the spread of the pandemic.
Trends in estimated total retail dispensed prescriptions of purported COVID-19 treatments and preventions in Canada
Authors: Alkabbani Wajd , Gamble John-Michael
Published: April 2023

Objectives

Several medications were proposed for the treatment and prophylaxis of COVID-19 but with limited supporting evidence. Herein, we assessed trends in the volume of projected total retail dispensed prescriptions for 12 agents proposed for treatment and prevention of COVID-19 before and after March 2020 in Canada.

Methods

We conducted a cross-sectional study using monthly prescription volumes obtained from IQVIA’s CompuScript database. We used joinpoint regression to identify significant inflection points and calculate the monthly percent change (MPC).

Key findings

Dispensations peaked after March 2020 for several medications, including hydroxychloroquine, fluvoxamine, ivermectin, colchicine, tocilizumab, sarilumab and famotidine. Although most peaks were short lived, large increases were observed for ivermectin (MPC from September 2020 to January 2021 = 28%) and famotidine (MPC from June 2021 to October 2021 = 14%).

Conclusions

Overall, Canadian prescribing patterns were mostly consistent with recommendations from guidelines and health regulatory bodies. Nonetheless, active monitoring of trends should continue.
Physiological function of hydrophobin Vmh3 in lignin degradation by white-rot fungus Pleurotus ostreatus
Authors: Han Junxian , Kawauchi Moriyuki , Terauchi Yuki , Yoshimi Akira , Tanaka Chihiro , Nakazawa Takehito , Honda Yoichi
Published: April 2023

Hydrophobins are small-secreted proteins comprising both hydrophobic and hydrophilic parts, that can self-assemble into an amphiphilic film at the air-liquid interface. More than 20 hydrophobin genes have been estimated in the white-rot fungus Pleurotus ostreatus. In our previous studies, three hydrophobin genes were shown to be predominantly expressed under ligninolytic conditions, and only vmh3 was downregulated in both the delignification-deficient mutant Δgat1 and Δhir1 strains. Here, we focused on the function of the hydrophobin Vmh3 to clarify its physiological role in lignin degradation. When the hyphae were observed by transmission electron microscopy, deletion of vmh3 resulted in the disappearance of black aggregates at the interface between the cell wall and outer environment. Deletion of vmh3 resulted in reduced hydrophobicity when 0.2% sodium dodecyl sulfate was dropped onto the mycelial surface. These results suggest that Vmh3 functions on the cell surface and plays a major role in mycelial hydrophobization. Furthermore, the Δvmh3 strain showed a marked delay in lignin degradation on beech wood sawdust medium, while the production of lignin-modifying enzymes was not reduced. This study demonstrated, for the first time, the possible effect of hydrophobin on lignin degradation by a white-rot fungus.
The high diversity of Scedosporium and Lomentospora species and their prevalence in human-disturbed areas in Taiwan
Authors: Huang Yin-Tse , Hung Tsu-Chun , Fan Yun-Chen , Chen Chi-Yu , Sun Pei-Lun
Published: April 2023

Scedosporium and Lomentospora are important opportunistic pathogens causing localized or disseminated infection in humans. Understanding their environmental distribution is critical for public hygiene and clinical management. We carried out the first environmental survey in urbanized and natural regions in Taiwan. Overall, Scedosporium and Lomentospora species were recovered in 132 out of 273 soil samples (48.4%) across Taiwan. We morphologically and molecularly identified six Scedosporium and one Lomentospora species. All four major clinical relevant species were isolated with high frequency, i.e., Scedosporium apiospermum (42.4%), S. boydii (21.8%), Lomentosporaprolificans (14.5%), S. aurantiacum (8.5%); two clinically minor species, Pseudallescheria angusta (6.7%) and S. dehoogii (5.6%), and a saprobic species, S. haikouense (0.6%), had moderate to rare incidence. These fungal species had high incidence in urban (48.6%) and hospital (67.4%) soil samples, and had limited distribution in samples from natural regions (5%). Multivariate analysis of the fungal composition revealed strong evidence of the preferential distribution of these fungi in urban and hospital regions compared with natural sites. In addition, strong evidence suggested that the distribution and abundance of these fungal species were highly heterogeneous in the environment; samples in vicinity often yielded varied fungal communities. We concluded that these fungal species were prevalent in soil in Taiwan and their occurrences were associated with human activities. Although, hygiene sensitive sites such as hospitals were not harboring heavier fungal burdens than other urban facilities in our survey, still, aware should be taken for the high frequency of these clinical relevant species around hospital regions.
Two-dimensional simulations of internal gravity waves in a 5 M⊙ zero-age-main-sequence model
Authors: Le Saux A , Baraffe I , Guillet T , Vlaykov D G , Morison A , Pratt J , Constantino T , Goffrey T
Published: April 2023

Main-sequence intermediate-mass stars present a radiative envelope that supports internal gravity waves (IGWs). Excited at the boundary with the convective core, IGWs propagate towards the stellar surface and are suspected to impact physical processes such as rotation and chemical mixing. Using the fully compressible time-implicit code MUSIC, we study IGWs in two-dimensional simulations of a zero-age-main-sequence 5 solar mass star model up to 91  per cent of the stellar radius with different luminosity and radiative diffusivity enhancements. Our results show that low-frequency waves excited by core convection are strongly impacted by radiative effects as they propagate. This impact depends on the radial profile of radiative diffusivity which increases by almost 5 orders of magnitude between the centre of the star and the top of the simulation domain. In the upper layers of the simulation domain, we observe an increase of the temperature. Our study suggests that this is due to heat added in these layers by IGWs damped by radiative diffusion. We show that non-linear effects linked to large amplitude IGWs may be relevant just above the convective core. Both these effects are intensified by the artificial enhancement of the luminosity and radiative diffusivity, with enhancement factors up to 104 times the realistic values. Our results also highlight that direct comparison between numerical simulations with enhanced luminosity and observations must be made with caution. Finally, our work suggests that thermal effects linked to the damping of IGWs could have a non-negligible impact on stellar structure.
A MUSE view of the multiple interacting system HCG 31
Authors: Gómez-Espinoza Diego A , Torres-Flores S , Firpo V , Amram Philippe , Epinat Benoit , Contini Thierry , Mendes de Oliveira Claudia
Published: April 2023

We present, for the first time, spatially resolved spectroscopy for the entire Hickson Compact Group 31 obtained with the MUSE instrument at the VLT and an in-depth analysis of this compact group. To obtain a complete understanding of the system, we derived radial velocity and dispersion velocity maps, maps of the ionization mechanism of the system, chemical abundances and their distribution over the whole system, star formation rates and ages of the different star-forming regions, and the spatial distribution of the Wolf–Rayet stellar population. We also reconstructed the star formation history of the galaxies HCG 31 A, C, B, and F, measured the emission-line fluxes, and performed a stellar population synthesis. Our main findings are: (i) that there is clearly disturbed kinematics due to the merger event that the system is experiencing; (ii) that the ionization is produced exclusively via star formation except for the nucleus of the galaxy HCG 31 A, where there is a small contribution of shocks; (iii) that there is low oxygen abundance distributed homogeneously through the system; (iv) that there is a prominent population of carbon Wolf–Rayet stars in the central zone of the group; and (v) that there are clear evidences of the tidal origin of the galaxies HCG 31 E, HCG 31 H, and HCG 31 F because they show quite high oxygen abundances for their stellar mass. All these findings are clear evidence that HCG 31 is currently in an early merging phase and manifesting a starburst in its central region.
Spatially resolved chemodynamics of the starburst dwarf galaxy CGCG 007-025: evidence for recent accretion of metal-poor gas
Authors: del Valle-Espinosa Macarena G , Sánchez-Janssen Rubén , Amorín Ricardo , Fernández Vital , Sánchez Almeida Jorge , García Lorenzo Begoña , Papaderos Polychronis
Published: April 2023

Nearby metal-poor starburst dwarf galaxies present a unique opportunity to probe the physics of high-density star formation with a detail and sensitivity unmatched by any observation of the high-z Universe. Here, we present the first results from a chemodynamical study of the nearby, gas-rich starburst dwarf CGCG 007-025. We use VLT/MUSE integral field spectroscopy to characterize the properties of the star-forming (SF) gas, from its metal content to its kinematics. The star formation rate (SFR) surface density presents a clumpy distribution, with the brightest knot hosting a 5 Myr young, Wolf–Rayet (WR) population (revealed by the presence of the characteristic 5808 Å WR bump). The ionized gas kinematics are dominated by disordered motions. A superposition of a narrow (σ ≈ 30km s−1), intermediate (150 km s−1), and broad (1000 km s−1) kinematic components are needed to model the emission-line profiles in the brightest SF region, suggesting the presence of energetic outflows from massive stars. The gas-phase metallicity of the galaxy spans 0.6 dex and displays a strong anticorrelation with SFR surface density, dropping to 12 + log(O/H) = 7.7 in the central SF knot. The spatially resolved BPTs indicate the gas is being ionized purely by SF processes. Finally, the anticorrelation between the SFR and the gas metallicity points out to accretion of metal-poor gas as the origin of the recent off-centre starburst, in which the infalling material ignites the SF episode.
The role of mass and environment in the build-up of the quenched galaxy population since cosmic noon
Authors: Taylor Elizabeth , Almaini Omar , Merrifield Michael , Maltby David , Wild Vivienne , Hartley William G , Rowlands Kate
Published: April 2023

We conduct the first study of how the relative quenching probability of galaxies depends on environment over the redshift range 0.5 < z < 3, using data from the UKIDSS Ultra Deep Survey. By constructing the stellar mass functions for quiescent and post-starburst (PSB) galaxies in high-, medium-, and low-density environments to z = 3, we find an excess of quenched galaxies in dense environments out to at least z ∼ 2. Using the growth rate in the number of quenched galaxies, combined with the star-forming galaxy mass function, we calculate the probability that a given star-forming galaxy is quenched per unit time. We find a significantly higher quenching rate in dense environments (at a given stellar mass) at all redshifts. Massive galaxies (M* > 1010.7 M⊙) are on average 1.7 ± 0.2 times more likely to quench per Gyr in the densest third of environments compared to the sparsest third. Finally, we compare the quiescent galaxy growth rate to the rate at which galaxies pass through a PSB phase. Assuming a visibility time-scale of 500 Myr, we find that the PSB route can explain ∼50 per cent of the growth in the quiescent population at high stellar mass (M* > 1010.7 M⊙) in the redshift range 0.5 < z < 3, and potentially all of the growth at lower stellar masses.
Evidence for scattering of curvature radiation in radio pulsar profiles
Authors: Dyks J
Published: April 2023

Radio pulsars exhibit several unexplained phenomena, in particular the average pulse profiles with the apparent core-cone structure and interesting frequency evolution. I show that they can be interpreted through essential geometric properties of the inverse Compton scattering. If the scattering occurs in a dipolar magnetosphere and the mean free path is long, a nested cone structure is expected with the cone size ratio of two-thirds, which is consistent with observations. Being a discontinuous process, the scattering is consistent with the discrete altitude structure of emission rings, as derived from aberration–retardation effects. Assuming that the upscattered signal is the curvature radiation (CR), one can interpret the observed bifurcated components (BCs) as a magnified microbeam of CR: the BCs are wide low-frequency CR microbeams that have been upshifted in frequency with their width preserved by beam-copying scattering in divergent magnetic field. The large flux of BCs is partly caused by compression of the full emitted spectrum into the narrow observed bandwidth, which explains why the frequency-resolved BCs have the frequency-integrated shape. The wide low-frequency microbeams can encompass large magnetospheric volumes, which considerably abates the requirements of the energy needed for coherency. The properties of BCs thus suggest that the observed modulated radio flux is strongly affected by the scattering-driven blueshift and spectral compression. The relativistic beaming formula (1/γ) is not always applicable, in the sense that it may not be directly applied to some blueshifted profile features.
SILCC – VII. Gas kinematics and multiphase outflows of the simulated ISM at high gas surface densities
Authors: Rathjen Tim-Eric , Naab Thorsten , Walch Stefanie , Seifried Daniel , Girichidis Philipp , Wünsch Richard
Published: April 2023

We present magnetohydrodynamic (MHD) simulations of the star-forming multiphase interstellar medium (ISM) in stratified galactic patches with gas surface densities Σgas = 10, 30, 50, and 100 $\mathrm{M_\odot \, pc^{-2}}$. The silcc project simulation framework accounts for non-equilibrium thermal and chemical processes in the warm and cold ISM. The sink-based star formation and feedback model includes stellar winds, hydrogen-ionizing UV radiation, core-collapse supernovae, and cosmic ray (CR) injection and diffusion. The simulations follow the observed relation between Σgas and the star formation rate surface density ΣSFR. CRs qualitatively change the outflow phase structure. Without CRs, the outflows transition from a two-phase (warm and hot at 1 kpc) to a single-phase (hot at 2 kpc) structure. With CRs, the outflow always has three phases (cold, warm, and hot), dominated in mass by the warm phase. The impact of CRs on mass loading decreases for higher Σgas and the mass loading factors of the CR-supported outflows are of order unity independent of ΣSFR. Similar to observations, vertical velocity dispersions of the warm ionized medium (WIM) and the cold neutral medium (CNM) correlate with the star formation rate as $\sigma _\mathrm{z} \propto \Sigma _\mathrm{SFR}^a$, with a ∼ 0.20. In the absence of stellar feedback, we find no correlation. The velocity dispersion of the WIM is a factor ∼2.2 higher than that of the CNM, in agreement with local observations. For $\Sigma _\mathrm{SFR} \gtrsim 1.5 \times 10^{-2}\, \mathrm{M}_\odot \, \mathrm{yr}^{-1}\, \mathrm{kpc}^{-2}$ the WIM motions become supersonic.
A broad survey of spectro-temporal properties from FRB 20121102A
Authors: Chamma Mohammed A , Rajabi Fereshteh , Kumar Aishwarya , Houde Martin
Published: April 2023

We survey the spectro-temporal properties of fast radio bursts from FRB 20121102A observed by earlier studies across a wide range of frequencies. We investigate 167 bursts from FRB 20121102A spanning frequencies 1–7.5 GHz, durations of less than 1 to ∼10 ms, with low and high energies, and with different wait-times. We find from this sample of bursts a strong agreement with the inverse relationship between sub-burst slope and duration and with other predictions made by the triggered relativistic dynamical model. Earlier results found agreement with those predictions across three different repeating FRB sources. For this sample of bursts, we find that the sub-burst slope as well as the ‘sad trombone’ drift rate are consistent with being in a quadratic relationship with frequency and that both these quantities are inversely proportional to the duration. We also find that the duration decreases with increasing frequency as well as a statistically significant correlation between the sub-burst duration and bandwidth (proportional to t−1/2) that is unexpected. No distinct group of bursts in this sample deviated from these relationships, however significant scatter can be seen in measurements. This study demonstrates the consistent existence of relationships between the spectro-temporal properties of bursts from a repeating FRB source. A simple explanation for the inverse relation between the sub-burst slope and duration is an inherently narrowband emission process. We make all measurements available as well as a graphical user interface called Frbgui developed and used to perform measurements of burst waterfalls.
Constraints on the inner regions of lensing galaxies from central images using a recent AGN offset distribution
Authors: Perera D , Williams L L R , Scarlata C
Published: April 2023

In gravitational lensing, central images in quads can serve as a powerful probe of the inner regions of lens galaxies. The presence of an offset central supermassive black hole (SMBH) has the potential to distort the time-delay surface in a way such that three central images form: a strongly demagnified image near the SMBH, and two less demagnified (and potentially observable) images at a central maximum and saddle point. Using a quad-lens macro-model, we simulate the constraints that could be placed on various lens galaxy parameters based on their central images’ probability of detection or non-detection. Informed by a recent low-redshift distribution of off-nucleus active galactic nucleus, we utilize Bayesian inference to constrain the mean SMBH off-nucleus distance and galactic core radius for a sample of six quads. In general, we find that a detection of the central image in any quad would favour larger SMBH off-nucleus distances and galaxy core sizes. Assuming a linear relationship between core radii and velocity dispersion rc = bσ, these results similarly imply strong constraints on b, where the likely case of a central image non-detection in each quad constrains b to $3.11^{+2.72}_{-2.26} \times 10^{-4}$ kpc km−1 s. Our results show that tight constraints on lens galaxy parameters can be made regardless of a detection or non-detection of a central image. Therefore, we recommend observational searches for the central image, possibly using our suggested novel detection technique in ultraviolet filters, to formalize stronger constraints on lens galaxy parameters.
New eruptive variable(s) in the RAFGL 7009S H ii region
Authors: Nikoghosyan E H , Azatyan N M , Andreasyan D H , Kaper L , Samsonyan A L , Yeghikyan A G , Baghdasaryan D S , Harutyunyan N A
Published: April 2023

Eruptions of young stellar objects (YSOs) are rare events, therefore a new outburst is always noteworthy. We present two new high-amplitude variable YSOs, J183421.85−055951.0 (#1) and J183421.39−055937.7 (#2), in the RAFGL 7009S star-forming region. We find them in the United Kingdom Infrared Telescope Infrared Deep Sky Survey Galactic Plane Survey data base, and supplement these data with archived infrared and millimetre photometric and spectral images and data from the Spitzer Infrared Array Camera, the K-band Multi-Object Spectrograph, and the Atacama Large Millimeter/submillimeter Array data bases. The outburst in #1 occurred in the period 2007–2011, during which the brightness increased by ∼2.7 mag in the K band and by ∼2.5 mag in the 3.6 μm band. The colour indices indicate a YSO in Class I/II evolutionary stage. After outburst, the K-band spectrum shows the CO band, Brγ, Mg i in absorption and H2 in emission – characteristics associated with a FU Orionis (FUors)-type eruptive variable. Object #1 is associated with an outflow detected in the near-infrared and millimetre ranges, mainly in the H2, SiO, HCO+, and HCN lines. Object #2 only shows high-amplitude variability in the K band (ΔK  =  2.0 mag) while its colour indices before outburst indicate a YSO at an early evolutionary stage. There is no obvious outflow activity associated with this object. We classify #1 as a FUor-type eruptive variable based on the obtained data. The limited information on #2 makes it difficult to draw definite conclusions about the nature of its variability.
Studying the multifrequency angular power spectrum of the cosmic dawn 21-cm signal
Authors: Shaw Abinash Kumar , Ghara Raghunath , Zaroubi Saleem , Mondal Rajesh , Mellema Garrelt , Mertens Florent , Koopmans Léon V E , Semelin Benoît
Published: April 2023

The light-cone (LC) anisotropy arises due to cosmic evolution of the cosmic dawn (CD) 21-cm signal along the line-of-sight (LoS) axis of the observation volume. The LC effect makes the signal statistically non-ergodic along the LoS axis. The multifrequency angular power spectrum (MAPS) provides an unbiased alternative to the popular three-dimensional (3D) power spectrum as it does not assume statistical ergodicity along every direction in the signal volume. Unlike the 3D power spectrum which mixes the cosmic evolution of the 21-cm signal along the LoS k modes, MAPS keeps the evolution information disentangled. Here, we first study the impact of different underlying physical processes during CD on the behaviour of the 21-cm MAPS using simulations of various different scenarios and models. We also make error predictions in 21-cm MAPS measurements considering only the system noise and cosmic variance for mock observations of Hydrogen Epoch of Reionization Array (HERA), NenuFAR, and SKA-Low. We find that 100 h of HERA observations will be able to measure 21-cm MAPS at ≥3σ for ℓ ≲ 1000 with $0.1\, {\rm MHz}$ channel-width. The better sensitivity of SKA-Low allows reaching this sensitivity up to ℓ ≲ 3000. Note that due to the difference in the frequency coverage of the various experiments, the CD–epoch of reionization model considered for NenuFAR is different than those used for the HERA and SKA-Low predictions. Considering NenuFAR with the new model, measurements ≥2σ are possible only for ℓ ≲ 600 with $0.2\, {\rm MHz}$ channel-width and for a 10 times longer observation time of tobs = 1000 h. However, for the range 300 ≲ ℓ ≲ 600 and tobs = 1000 h more than 3σ measurements are still possible for NenuFAR when combining consecutive frequency channels within a 5 MHz band.
3D hydrodynamics simulations of internal gravity waves in red giant branch stars
Authors: Blouin Simon , Mao Huaqing , Herwig Falk , Denissenkov Pavel , Woodward Paul R , Thompson William R
Published: April 2023

We present the first 3D hydrodynamics simulations of the excitation and propagation of internal gravity waves (IGWs) in the radiative interiors of low-mass stars on the red giant branch (RGB). We use the ppmstar explicit gas dynamics code to simulate a portion of the convective envelope and all the radiative zone down to the hydrogen-burning shell of a $1.2\, {\rm M}_{\odot }$ upper RGB star. We perform simulations for different grid resolutions (7683, 15363, and 28803), a range of driving luminosities, and two different stratifications (corresponding to the bump luminosity and the tip of the RGB). Our RGB tip simulations can be directly performed at the nominal luminosity, circumventing the need for extrapolations to lower luminosities. A rich, continuous spectrum of IGWs is observed, with a significant amount of total power contained at high wavenumbers. By following the time evolution of a passive dye in the stable layers, we find that IGW mixing in our simulations is weaker than predicted by a simple analytical prescription based on shear mixing and not efficient enough to explain the missing RGB extra mixing. However, we may be underestimating the efficiency of IGW mixing given that our simulations include a limited portion of the convective envelope. Quadrupling its radial extent compared to our fiducial set-up increases convective velocities by up to a factor 2 and IGW velocities by up to a factor 4. We also report the formation of a $\sim 0.2\, H_P$ penetration zone and evidence that IGWs are excited by plumes that overshoot into the stable layers.
Velocity relationships of isolated galaxy pairs in support of MOND-type theories
Authors: Penner A Raymond
Published: April 2023

The MOND-type theories of AQUADratic Lagrangian (AQUAL) and GRavitational Anti-Screening (GRAS) are applied to isolated galaxy pairs. Theoretical relationships between their intervelocities, line-of-sight velocities, and their baryonic masses will be derived. These relationships will be compared with observations taken of a set of 3970 highly isolated pairs. The theoretical velocity relationships and distributions provided by AQUAL and GRAS are found to be in very good agreement with these observations. This agreement indirectly implies that there is no fall-off in the rotational curves of galaxies, which remain flat out to large distances.