bluuebunny/crossref_metadata_2025 huggingface dataset:
Mitofusin 2 mutation drives cell proliferation in Charcot-Marie-Tooth 2A fibroblasts
Authors: Zanfardino Paola , Longo Giovanna , Amati Alessandro , Morani Federica , Picardi Ernesto , Girolamo Francesco , Pafundi Mariella , Cox Sharon N , Manzari Caterina , Tullo Apollonia , Doccini Stefano , Santorelli Filippo M , Petruzzella Vittoria
Published: August 2022

Dominant mutations in ubiquitously expressed mitofusin 2 gene (MFN2) cause Charcot-Marie-Tooth type 2A (CMT2A; OMIM 609260), an inherited sensory-motor neuropathy that affects peripheral nerve axons. Mitofusin 2 protein has been found to take part in mitochondrial fusion, mitochondria–endoplasmic reticulum tethering, mitochondrial trafficking along axons, mitochondrial quality control and various types of cancer, in which MFN2 has been indicated as a tumor suppressor gene. Discordant data on the mitochondrial altered phenotypes in patient-derived fibroblasts harboring MFN2 mutations and in animal models have been reported. We addressed some of these issues by focusing on mitochondria behavior during autophagy and mitophagy in fibroblasts derived from a CMT2AMFN2 patient with an MFN2650G > T/C217F mutation in the GTPase domain. This study investigated mitochondrial dynamics, respiratory capacity and autophagy/mitophagy, to tackle the multifaceted MFN2 contribution to CMT2A pathogenesis. We found that MFN2 mutated fibroblasts showed impairment of mitochondrial morphology, bioenergetics capacity, and impairment of the early stages of autophagy, but not mitophagy. Unexpectedly, transcriptomic analysis of mutated fibroblasts highlighted marked differentially expressed pathways related to cell population proliferation and extracellular matrix organization. We consistently found the activation of mTORC2/AKT signaling and accelerated proliferation in the CMT2AMFN2 fibroblasts. In conclusion, our evidence indicates that MFN2 mutation can positively drive cell proliferation in CMT2AMFN2 fibroblasts.
Non-coding RNAs in Alzheimer’s disease: perspectives from omics studies
Authors: Wang Erming , Lemos Duarte Mariana , Rothman Lauren E , Cai Dongming , Zhang Bin
Published: August 2022

Neurodegenerative diseases such as Alzheimer’s disease (AD) are characterized by the progressive loss of neurons in the brain and the spinal cord. The pathophysiology of AD is multifactorial with heterogeneous molecular manifestations. The lack of efficacious therapies for AD reinforces the importance of exploring in depth multifaceted disease mechanisms. Recent progresses on AD have generated a large amount of RNA-sequencing data at both bulk and single cell levels and revealed thousands of genes with expression changes in AD. However, the upstream regulators of such gene expression changes are largely unknown. Non-coding RNAs (ncRNAs) represent the majority of the human transcriptome, and regulatory ncRNAs have been found to play an important role in regulating gene expression. A single miRNA usually targets a number of mRNAs and thus such ncRNAs are particular important for understanding disease mechanisms and developing novel therapeutics. This review aims to summarize the recent findings on the roles of ncRNAs in AD from ncRNA-omics studies with a focus on ncRNA signatures, interactions between ncRNAs and mRNAs, and ncRNA-regulated pathways in AD. We also review the potential of specific ncRNAs to serve as biomarkers and therapeutic targets for AD. In the end, we point out future directions for studying ncRNAs in AD.
Advancing Children’s Rights in Peace Processes: The Role of the Committee on the Rights of the Child
Authors: Molloy Sean
Published: August 2022

The cessation of violent conflict offers crucial opportunities to increase the likelihood that children’s rights are respected, protected and realized in the post-conflict state. Peace processes—which include peace negotiations, peace agreement(s) and the implementation of peace agreement provisions—can be central to the realization of this objective. This article examines the concluding observations of the Committee on the Rights of the Child through the lens of process-based performance. The objective is to demonstrate contributions that the Committee can make to advancing children’s rights at different stages of a peace process, often in combination with other actors and mechanisms seeking to do the same. After identifying some of the challenges associated with translating this potential into practice, suggestions are made to help bridge the chasm between potential and practice.
Transcriptional Behavior of Regulatory T Cells Predicts IBD Patient Responses to Vedolizumab Therapy
Authors: Abreu Maria T , Davies Julie M , Quintero Maria A , Delmas Amber , Diaz Sophia , Martinez Catherine D , Venables Thomas , Reich Adrian , Crynen Gogce , Deshpande Amar R , Kerman David H , Damas Oriana M , Fernandez Irina , Santander Ana M , Pignac-Kobinger Judith , Burgueno Juan F , Sundrud Mark S
Published: August 2022

Background

Inflammatory bowel disease (IBD) involves chronic T cell–mediated inflammatory responses. Vedolizumab (VDZ), a monoclonal antibody against α4β7 integrin, inhibits lymphocyte extravasation into intestinal mucosae and is effective in ulcerative colitis (UC) and Crohn’s disease (CD).

Aim

We sought to identify immune cell phenotypic and gene expression signatures that related to response to VDZ.

Methods

Peripheral blood (PBMC) and lamina propria mononuclear cells (LPMCs) were analyzed by flow cytometry and Cytofkit. Sorted CD4 + memory (Tmem) or regulatory T (Treg) cells from PBMC and LPMC were analyzed by RNA sequencing (RNA-seq). Clinical response (≥2-point drop in partial Mayo scores [UC] or Harvey-Bradshaw index [CD]) was assessed 14 to 22 weeks after VDZ initiation. Machine-learning models were used to infer combinatorial traits that predicted response to VDZ.

Results

Seventy-one patients were enrolled: 37 received VDZ and 21 patients remained on VDZ >2 years. Fourteen of 37 patients (38%; 8 UC, 6 CD) responded to VDZ. Immune cell phenotypes and CD4 + Tmem and Treg transcriptional behaviors were most divergent between the ileum and colon, irrespective of IBD subtype or inflammation status. Vedolizumab treatment had the greatest impact on Treg metabolic pathways, and response was associated with increased expression of genes involved in oxidative phosphorylation. The strongest clinical predictor of VDZ efficacy was concurrent use of thiopurines. Mucosal tissues offered the greatest number of response-predictive biomarkers, whereas PBMC Treg-expressed genes were the best predictors in combinatorial models of response.

Conclusions

Mucosal and peripheral blood immune cell phenotypes and transcriptional profiles can inform VDZ efficacy and inform new opportunities for combination therapies.
Does surgical fixation improve pain and quality of life in patients with non-flail rib fractures? A best evidence topic review
Authors: Raza Samad , Eckhaus Jazmin
Published: August 2022

A best evidence topic in thoracic surgery was written according to a structured protocol. The question addressed was ‘does surgical stabilization of rib fractures improve pain and quality of life in patients with non-flail rib fractures?’. Altogether >300 papers were found using the reported search, of which 6 represented the best evidence to answer the clinical question. The authors, journal, date and country of publication, patient group studied, study type, relevant outcomes and results of these papers were tabulated. Whilst several non-randomized cohort studies demonstrate superior pain and quality of life outcomes with surgical fixation as compared to conservative management, this is not replicated by the findings of a recent randomized trial which found worse pain, but early return to work in those treated with surgical stabilization of rib fractures. Given this, clinicians will need to carefully consider the indications for treating painful non-flail rib fractures as surgical fixation represents a reasonable treatment option in only appropriately selected candidates.
Preoperative P-wave parameters and risk of atrial fibrillation after cardiac surgery: a meta-analysis of 20 201 patients
Authors: Kawczynski Michal J , Van De Walle Sophie , Maesen Bart , Isaacs Aaron , Zeemering Stef , Hermans Ben , Vernooy Kevin , Maessen Jos G , Schotten Ulrich , Bidar Elham
Published: August 2022

OBJECTIVES

To evaluate the role of P-wave parameters, as defined on preprocedural electrocardiography (ECG), in predicting atrial fibrillation after cardiac surgery [postoperative atrial fibrillation (POAF)].

METHODS

PubMed, Cochrane library and Embase were searched for studies reporting on P-wave parameters and risk of POAF. Meta-analysis of P-wave parameters reported by at least 5 different publications was performed. In case of receiver operator characteristics (ROC-curve) analysis in the original publications, an ROC meta-analysis was performed to summarize the sensitivity and specificity.

RESULTS

Thirty-two publications, with a total of 20 201 patients, contributed to the meta-analysis. Increased P-wave duration, measured on conventional 12-lead ECG (22 studies, Cohen’s d = 0.4, 95% confidence interval: 0.3–0.5, P < 0.0001) and signal-averaged ECG (12 studies, Cohen’s d = 0.8, 95% confidence interval: 0.5–1.2, P < 0.0001), was a predictor of POAF independently from left atrial size. ROC meta-analysis for signal-averaged ECG P-wave duration showed an overall sensitivity of 72% (95% confidence interval: 65–78%) and specificity of 68% (95% confidence interval: 58–77%). Summary ROC curve had a moderate discriminative power with an area under the curve of 0.76. There was substantial heterogeneity in the meta-analyses for P-wave dispersion and PR-interval.

CONCLUSIONS

This meta-analysis shows that increased P-wave duration, measured on conventional 12-lead ECG and signal-averaged ECG, predicted POAF in patients undergoing cardiac surgery.
Optimal timing for lung metastasectomy in patients with colorectal cancer
Authors: Ichinose Junji , Hashimoto Kohei , Matsuura Yosuke , Nakao Masayuki , Akiyoshi Takashi , Fukunaga Yosuke , Okumura Sakae , Mun Mingyon
Published: August 2022

OBJECTIVES

The possibility of occult metastasis remains a concern when deciding on lung metastasectomy. This study aimed to evaluate the utility of our two-step determination, which required confirmation that no new metastases had occurred over 3 months before surgery.

METHODS

Patients who were referred for colorectal lung metastases between 2007 and 2015 were reviewed. Immediate wedge resection was performed for cases with a single peripheral metastasis, whereas surgical indications for others were determined by the two-step determination. Early increase was defined as the emergence of new metastases within 4 months after the diagnosis of lung metastases.

RESULTS

Among 369 patients included, 92 were unresectable upon initial diagnosis, and 74 with single peripheral metastasis underwent immediate wedge resection. Surgical indications for the remaining 203 patients were ascertained based on the two-step determination. Surgery was not indicated in 48 patients (24%) due to new metastases or a favourable response to chemotherapy, with a median waiting duration of 4.8 months. Those who did not receive surgery had a worse prognosis than those who did (5-year overall survival: 21% vs 69%, P < 0.001) and were comparable to the initially unresectable group (5-year overall survival: 23%). Thirty-eight patients with early increase had lower surgical resection rates and worse prognoses than those without. Multivariable analysis identified early increase as an independent prognostic factor (hazard ratio: 4.49, P < 0.001).

CONCLUSIONS

Patients with colorectal lung metastasis who developed new metastasis during the waiting period exhibited poor prognosis, suggesting the utility of the two-step determination of surgical indications.
A scoping study of the medication therapy related pharmacist services in the Western Pacific Region
Authors: Jackson John , Mishra Pradeep , Caliph Suzanne
Published: August 2022

Objectives

To identify the preferred terminologies, nature of services, perceived benefits and barriers to medication therapy-related pharmacist services in the Western Pacific region to facilitate the development of a framework for medication therapy management.

Method

A survey was completed by hospital and community pharmacists purposively selected by the national pharmacist associations.

Key findings

Pharmaceutical care was the preferred term with services predominantly related to medication safety and public health. The perceived barriers included lack of appropriate facility, time and funding.

Conclusion

A broader pharmaceutical care framework is a preferred approach to delivery of Good Pharmacy Practice in the region.
Understanding Early Pandemic Severe Acute Respiratory Syndrome Coronavirus 2 Transmission in a Medical Center by Incorporating Public Sequencing Databases to Mitigate Bias
Authors: Turcinovic Jacquelyn , Schaeffer Beau , Taylor Bradford P , Bouton Tara C , Odom-Mabey Aubrey R , Weber Sarah E , Lodi Sara , Ragan Elizabeth J , Connor John H , Jacobson Karen R , Hanage William P
Published: August 2022

Background

Throughout the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic, healthcare workers (HCWs) have faced risk of infection from within the workplace via patients and staff as well as from the outside community, complicating our ability to resolve transmission chains in order to inform hospital infection control policy. Here we show how the incorporation of sequences from public genomic databases aided genomic surveillance early in the pandemic when circulating viral diversity was limited.

Methods

We sequenced a subset of discarded, diagnostic SARS-CoV-2 isolates between March and May 2020 from Boston Medical Center HCWs and combined this data set with publicly available sequences from the surrounding community deposited in GISAID with the goal of inferring specific transmission routes.

Results

Contextualizing our data with publicly available sequences reveals that 73% (95% confidence interval, 63%–84%) of coronavirus disease 2019 cases in HCWs are likely novel introductions rather than nosocomial spread.

Conclusions

We argue that introductions of SARS-CoV-2 into the hospital environment are frequent and that expanding public genomic surveillance can better aid infection control when determining routes of transmission.
Genotypic and Phenotypic Study of Antiviral Resistance Mutations in Refractory Cytomegalovirus Infection
Authors: Santos Bravo Marta , Plault Nicolas , Sánchez-Palomino Sonsoles , Rodríguez Cristina , Navarro Gabriel Mireia , Mosquera María Mar , Fernández Avilés Francesc , Suarez-Lledó María , Rovira Montserrat , Bodro Marta , Moreno Asunción , Linares Laura , Cofan Frederic , Berengua Carla , Esteva Cristina , Cordero Elisa , Martin-Davila Pilar , Aranzamendi Maitane , Pérez Jiménez Ana Belén , Vidal Elisa , Fernández Sabé Nuria , Len Oscar , Hantz Sebastien , Alain Sophie , Marcos María Ángeles ,   the Spanish Network for Research in Infectious Diseases (REIPI) and the Group for the Study of Infection in Transplantation (GESITRA), López-Medrano Francisco , Agüado Jose María , Martin-Gandul Cecilia , Carratalá Jordi , Niubó Jordí , Cervera Carlos , Muñoz Patricia , Fariñas María Carmen , Antón Andrés , Montejo Miguel , Pérez-Romero Pilar , Torres-Cisneros Julián
Published: August 2022

Background

This study describes the genotypic and phenotypic characterization of novel human cytomegalovirus (HCMV) genetic variants of a cohort of 94 clinically resistant HCMV patients.

Methods and results

Antiviral-resistant mutations were detected in the UL97, UL54, and UL56 target genes of 25 of 94 (26.6%) patients. The genotype-phenotype correlation study resolved the status of 5 uncharacterized UL54 deoxyribonucleic acid polymerase (G441S, A543V, F460S, R512C, A928T) and 2 UL56 terminase (F345L, P800L) mutations found in clinical isolates. A928T conferred high, triple resistance to ganciclovir, foscarnet, and cidofovir, and A543V had 10-fold reduced susceptibility to cidofovir. Viral growth assays showed G441S, A543V, F345L, and P800L impaired viral growth capacities compared with wild-type AD169 HCMV. Three-dimensional modeling predicted A543V and A928T phenotypes but not R512C, reinforcing the need for individual characterization of mutations by recombinant phenotyping.

Conclusions

Extending mutation databases is crucial to optimize treatments and to improve the assessment of patients with resistant/refractory HCMV infection.
The Influence of Sex, Body Mass Index, and Age on Cellular and Humoral Immune Responses Against Measles After a Third Dose of Measles-Mumps-Rubella Vaccine
Authors: Quach Huy Quang , Chen Jun , Monroe Jonathon M , Ratishvili Tamar , Warner Nathaniel D , Grill Diane E , Haralambieva Iana H , Ovsyannikova Inna G , Poland Gregory A , Kennedy Richard B
Published: August 2022

Background

A third dose of measles-mumps-rubella vaccine (MMR3) is recommended in mumps outbreak scenarios, but the immune response and the need for widespread use of MMR3 remain uncertain. Herein, we characterized measles-specific immune responses to MMR3 in a cohort of 232 healthy subjects.

Methods

Serum and peripheral blood mononuclear cells (PBMCs) were sampled at day 0 and day 28 after MMR3. Measles-specific binding and neutralizing antibodies were quantified in sera by enzyme-linked immunosorbent assay and a microneutralization assay, respectively. PBMCs were stimulated with inactivated measles virus, and the release of cytokines/chemokines was assessed by a multiplex assay. Demographic variables of subjects were examined for potential correlations with immune outcomes.

Results

Of the study participants, 95.69% and 100% were seropositive at day 0 and day 28, respectively. Antibody avidity significantly increased from 38.08% at day 0 to 42.8% at day 28 (P = .00026). Neutralizing antibodies were significantly enhanced, from 928.7 at day 0 to 1289.64 mIU/mL at day 28 (P = .0001). Meanwhile, cytokine/chemokine responses remained largely unchanged. Body mass index was significantly correlated with the levels of inflammatory cytokines/chemokines.

Conclusions

Measles-specific humoral immune responses, but not cellular responses, were enhanced after MMR3 receipt, extending current understanding of immune responses to MMR3 and supporting MMR3 administration to seronegative or high-risk individuals.
Oxazolidinones: mechanisms of resistance and mobile genetic elements involved
Authors: Brenciani Andrea , Morroni Gianluca , Schwarz Stefan , Giovanetti Eleonora
Published: August 2022

The oxazolidinones (linezolid and tedizolid) are last-resort antimicrobial agents used for the treatment of severe infections in humans caused by MDR Gram-positive bacteria. They bind to the peptidyl transferase centre of the bacterial ribosome inhibiting protein synthesis. Even if the majority of Gram-positive bacteria remain susceptible to oxazolidinones, resistant isolates have been reported worldwide. Apart from mutations, affecting mostly the 23S rDNA genes and selected ribosomal proteins, acquisition of resistance genes (cfr and cfr-like, optrA and poxtA), often associated with mobile genetic elements [such as non-conjugative and conjugative plasmids, transposons, integrative and conjugative elements (ICEs), prophages and translocatable units], plays a critical role in oxazolidinone resistance. In this review, we briefly summarize the current knowledge on oxazolidinone resistance mechanisms and provide an overview on the diversity of the mobile genetic elements carrying oxazolidinone resistance genes in Gram-positive and Gram-negative bacteria.
Transfer learning enables prediction of myocardial injury from continuous single-lead electrocardiography
Authors: Jin Boyang Tom , Palleti Raj , Shi Siyu , Ng Andrew Y , Quinn James V , Rajpurkar Pranav , Kim David
Published: August 2022

Objective

Chest pain is common, and current risk-stratification methods, requiring 12-lead electrocardiograms (ECGs) and serial biomarker assays, are static and restricted to highly resourced settings. Our objective was to predict myocardial injury using continuous single-lead ECG waveforms similar to those obtained from wearable devices and to evaluate the potential of transfer learning from labeled 12-lead ECGs to improve these predictions.

Methods

We studied 10 874 Emergency Department (ED) patients who received continuous ECG monitoring and troponin testing from 2020 to 2021. We defined myocardial injury as newly elevated troponin in patients with chest pain or shortness of breath. We developed deep learning models of myocardial injury using continuous lead II ECG from bedside monitors as well as conventional 12-lead ECGs from triage. We pretrained single-lead models on a pre-existing corpus of labeled 12-lead ECGs. We compared model predictions to those of ED physicians.

Results

A transfer learning strategy, whereby models for continuous single-lead ECGs were first pretrained on 12-lead ECGs from a separate cohort, predicted myocardial injury as accurately as models using patients’ own 12-lead ECGs: area under the receiver operating characteristic curve 0.760 (95% confidence interval [CI], 0.721–0.799) and area under the precision–recall curve 0.321 (95% CI, 0.251–0.397). Models demonstrated a high negative predictive value for myocardial injury among patients with chest pain or shortness of breath, exceeding the predictive performance of ED physicians, while attending to known stigmata of myocardial injury.

Conclusions

Deep learning models pretrained on labeled 12-lead ECGs can predict myocardial injury from noisy, continuous monitor data early in a patient’s presentation. The utility of continuous single-lead ECG in the risk stratification of chest pain has implications for wearable devices and preclinical settings, where external validation of the approach is needed.
Facilitators and Barriers to Implementation of Lung Cancer Screening: A Framework-Driven Systematic Review
Authors: Sedani Ami E , Davis Olivia C , Clifton Shari C , Campbell Janis E , Chou Ann F
Published: August 2022

Background

The purpose of this study is to undertake a comprehensive systematic review to describe multilevel factors (barriers and facilitators) that may influence the implementation of low-dose chest computed tomography for lung cancer screening in the United States.

Methods

Systematic literature searches were performed using 6 online databases and citation indexes for peer-reviewed studies, for articles published from 2013 to 2021. Studies were classified into 3 perspectives, based on the study’s unit of analysis: system, health-care provider, and patient. Barriers and facilitators identified for each study included in our final review were then coded and categorized using the Consolidate Framework for Implementation Research domains.

Results

At the system level, the 2 most common constructs were external policy and incentives and executing the implementation process. At the provider level, the most common constructs were evidence strength and quality of the intervention characteristics, patient needs and resources, implementation climate, and an individual’s knowledge and beliefs about the intervention. At the patient level, the most common constructs were patient needs and resources, individual’s knowledge and beliefs about the intervention, and engaging in the implementation process. These constructs can act as facilitators or barriers to lung cancer screening implementation.

Conclusions

Applying the Consolidate Framework for Implementation Research domains and constructs to understand and specify factors facilitating uptake of lung cancer screening as well as cataloging the lessons learned from previous efforts helps inform the development and implementation processes of lung cancer screening programs in the community setting.

Registration

PROSPERO, CRD42021247677.
Strangulated transomental hernia in virgin abdomen: laparoscopic surgery with a small laparotomy may be useful to assess the indeterminate viability of the bowel
Authors: Sawano Toyoaki , Kurokawa Tomohiro , Ozaki Akihiko , Bhandari Divya , Furuya Mioko , Kanemoto Yoshiaki , Tsubokura Masaharu , Ejiri Tomozo , Kanzaki Norio
Published: August 2022

A 66-year-old female without prior history of abdominal surgery visited the emergency department with a complain of sudden intensive lower abdominal pain. Closed loop bowel obstruction was discovered on contrast-enhanced computed tomography, leading to a laparoscopic examination of 5 h after the onset. During laparoscopy, 100 cm of distal jejunum with borderline viability was found incarcerated in a gap of the greater omentum. A 3-cm small incision was made at the umbilical trocar site to observe the bowel after it was released laparoscopically. When viewed under the shadowless lamp, the affected bowel appeared reddish, with peristalsis and a palpated mesentery artery. The surgical team determined no need for resection. The postoperative recovery went smoothly without any complications. Laparoscopic surgery for transomental hernias can be performed safely even in patients with borderline bowel viability, and observing bowel extra-peritoneally with a small incision could be helpful for laparoscopic surgery for internal hernias with borderline viability.
Spleen metastasis of recurrent malignant thymoma
Authors: Wu Chung-Wei , Yang Tsen-Long
Published: August 2022

Thymoma is a rare tumour that often occurs in the anterior mediastinum. Thymomas are usually diagnosed in middle-aged patients, and nearly half of cases are associated with myasthenia gravis. Thymomas typically progress through direct invasion of the thoracic cavity with extra-thoracic distant metastasis being uncommon. Here we report the case of a male patient who underwent an extensive thymectomy and radiotherapy 10 years before presentation, and in whom we detected a spleen tumour during regular out-patient follow-up. The patient underwent a splenectomy, and a final diagnosis of type B3 malignant thymoma was established.
A Genealogy of Reasonableness
Authors: Lawlor Krista
Published: August 2022

We all know that being reasonable is important in daily life. Beyond daily life, major political and ethical theorists give central place to reasonableness in their accounts of just and moral behaviour. In the law, at least in the Anglo-American setting, reasonableness is the standard for a wide range of behaviour, from administrative decisions to torts. But what is it to be reasonable? In answer, I provide a genealogical account of reasonableness. The functional perspective afforded by a genealogical account has numerous payoffs, explaining important features of reasonableness, and enabling us to respond to worries about vagueness or subjectivity in the meaning of ‘reasonable’.
Lucky imaging method based on wavelet analysis
Authors: Fan Wending , Li Binhua , Li Junwu , Zhang Xiliang
Published: August 2022

Lucky imaging is able to reconstruct high-resolution images effectively from astronomical images affected by atmospheric turbulence. Its image reconstruction process can be carried out in the spatial domain or in the Fourier domain. This paper extend the lucky imaging technique to the wavelet domain, and proposes a lucky imaging method based on wavelet analysis. First, the short-exposure astronomical images are decomposed into four subbands by using the bior3.7 wavelet basis. Then, for the low-frequency subbands, the components with higher wavelet coefficients are extracted in a given selection ratio for fusion. For the high-frequency subbands in the horizontal, vertical, and diagonal directions, taking the whole subband as a unit, the subbands with smaller sums of wavelet coefficients are extracted for stacking in a given selection ratio. Finally, an inverse wavelet transform is performed on the four fused subbands to reconstruct the resultant image. Experimental results show that the proposed algorithm can better extract the details hidden in the original short-exposure astronomical images and obtain a higher-resolution image, and that it has a good image restoration effect.
RJ-plots: An improved method to classify structures objectively
Authors: Clarke S D , Jaffa S E , Whitworth A P
Published: August 2022

The interstellar medium is highly structured, presenting a range of morphologies across spatial scales. The large data sets resulting from observational surveys and state-of-the-art simulations studying these hierarchical structures means that identification and classification must be done in an automated fashion to be efficient. Here we present RJ-plots, an improved version of the automated morphological classification technique J-plots developed by Jaffa et al. This method allows clear distinctions between quasi-circular/elongated structures and centrally over/underdense structures. We use the recent morphological SEDIGISM catalogue of Neralwar et al. to show the improvement in classification resulting from RJ-plots, especially for ring-like and concentrated cloud types. We also find a strong correlation between the central concentration of a structure and its star formation efficiency and dense gas fraction, as well as a lack of correlation with elongation. Furthermore, we use the accreting filament simulations of Clarke, Williams & Walch to highlight a multiscale application of RJ-plots, finding that while spherical structures become more common at smaller scales they are never the dominant structure down to r ∼ 0.03 pc.
Evidence of hard power-law spectral cutoff and disc reflection features from the X-ray transient XTE J1739–285
Authors: Mondal Aditya S , Raychaudhuri B , Dewangan G C , Beri Aru
Published: August 2022

We report on the nearly simultaneous NICER and NuSTAR observations of the known X-ray transient XTE J1739–285. These observations provide the first sensitive hard X-ray spectrum of this neutron star X-ray transient. The source was observed on 2020 February 19 in the hard spectral state with a luminosity of 0.007 of the Eddington limit. The broadband 1−70 keV NICER and NuSTAR observation clearly detects a cutoff of the hard spectral component around 34−40 keV when the continuum is fitted by a soft thermal component and a hard power-law component. This feature has been detected for the first time in this source. Moreover, the spectrum shows evidence for disc reflection – a relativistically broadened Fe K α line around 5−8 keV and a Compton hump in the 10−20 keV energy band. The accretion disc reflection features have not been identified before from this source. Through accretion disc reflection modelling, we constrain the radius of the inner disc to be $R_{\rm in}=3.1_{-0.5}^{+1.8}R_{\rm ISCO}$ for the first time. In addition, we find a low inclination, i ∼ 33°. Assuming the magnetosphere is responsible for such truncation of the inner accretion disc above the stellar surface, we establish an upper limit of 6.2 × 108 G on the magnetic field at the poles.
η Geminorum: an eclipsing semiregular variable star orbited by a companion surrounded by an extended disc
Authors: Torres Guillermo , Sakano Kristy
Published: August 2022

We report 11 yr of spectroscopic monitoring of the M-type asymptotic giant branch star η Gem, a semiregular variable and a known spectroscopic binary with a period of 8.2 yr. We combine our radial velocities with others from the literature to provide an improved spectroscopic orbital solution, giving a period of 2979 d, which we then use to predict past times of eclipse. We examine archival photometry from amateur variable star observers, and other sources, and find many instances of dimmings that occurred at the right time. This confirms previous indications that the system is eclipsing, and it now ranks among those with the longest known periods. No secondary eclipses are seen. The ∼0.4 mag eclipses that last about 5 months are much too deep to be produced by a stellar companion. We propose instead that the companion is surrounded by a large disc that is at least 1.5 au in diameter but is likely larger. We predict the centre of the next eclipse will occur on New Year’s Day, 2029.
The effects of plasma on the magnification and time delay of strongly lensed fast radio bursts
Authors: Er Xinzhong , Mao Shude
Published: August 2022

The number of identified fast radio bursts (FRBs) will continue to increase rapidly with current and planned future facilities. Strongly lensed FRBs are also expected to be found, which can provide precise time delays and thus have rich applications in cosmology and fundamental physics. However, the radio signal of lensed FRBs will be deflected by the plasma in lens galaxies in addition to the deflection by gravity. Such deflections by both gravity and plasma will cause frequency-dependent time delays, which are different from the dispersion delay and the geometric delay caused by gravitational lensing. Depending on the lensing and plasma models, the frequency–time-delay relationship of the lensed images can show distinguishing behaviours either between the multiple images or from the dispersion relation. Such phenomena cannot be neglected in future studies, especially at low radio frequencies, as plasma exists in lens galaxies in general. More importantly, such information provides not only a potential way to search for lensed FRBs but also constraints on the mass and plasma distributions in lens galaxies. In particular, plasma may make the missing central images observable at low radio frequencies.
Spin-down induced quark-hadron phase transition in cold isolated neutron stars
Authors: Prasad R , Mallick Ritam
Published: August 2022

We have studied the spin-down induced phase transition (PT) in cold, isolated neutron stars in this work. After birth, as the star slows down, its central density rises and crosses the critical density of PT, and a quark core is seeded inside the star. Intermediate-mass stars are more likely to have a quark seeding in their lifetime at birth. Smaller neutron stars do not have a quark core and remain neutron stars throughout their life, whereas in massive stars, a quark core exists at their centre from birth. In intermediate and massive stars, the quark core grows further as the star slows down. The appearance of a quark core leads to a sudden change in the moment of inertia of the star in its evolutionary history, and is also reflected in a sudden discontinuity in the braking index of the star (at the frequency where the quark core first seeds). The energy released during the PT process as the quark core is seeded can excite the f-mode oscillation in the star and is emitted in the form of the gravitational wave, which is in the range of detection with present operating detectors; however, future detectors will enable a more clean extraction of this signals. Also, neutrinos and bursts of gamma-rays can originate from PT events. The spin-down induced PT could be gradual or in the form of subsequent leaps producing persistent or multiple transient emissions.
Primordial magnetic fields in Population III star formation: a magnetized resolution study
Authors: Prole Lewis R , Clark Paul C , Klessen Ralf S , Glover Simon C O , Pakmor Rüdiger
Published: August 2022

Population III (Pop III) stars form in groups due to the fragmentation of primordial gas. While uniform magnetic fields have been shown to support against fragmentation in present-day star formation, it is unclear whether realistic k3/2 primordial fields can have the same effect. We bypass the issues associated with simulating the turbulent dynamo by introducing a saturated magnetic field at equipartition with the velocity field when the central densities reach 10−13 g cm−3. We test a range of sink particle creation densities from 10−10 to 10−8 g cm−3. Within the range tested, the fields did not suppress fragmentation of the gas and hence could not prevent the degree of fragmentation from increasing with increased resolution. The number of sink particles formed and total mass in sink particles was unaffected by the magnetic field across all seed fields and resolutions. The magnetic pressure remained sub-dominant to the gas pressure except in the highest density regions of the simulation box, where it became equal to but never exceeded gas pressure. Our results suggest that the inclusion of magnetic fields in numerical simulations of Pop III star formation is largely unimportant.
The role of rotation on the formation of second generation stars in globular clusters
Authors: Lacchin E , Calura F , Vesperini E , Mastrobuono-Battisti A
Published: August 2022

By means of 3D hydrodynamic simulations, we explore the effects of rotation in the formation of second-generation (SG) stars in globular clusters (GC). Our simulations follow the SG formation in a first-generation (FG) internally rotating GC; SG stars form out of FG asymptotic giant branch (AGB) ejecta and external pristine gas accreted by the system. We have explored two different initial rotational velocity profiles for the FG cluster and two different inclinations of the rotational axis with respect to the direction of motion of the external infalling gas, whose density has also been varied. For a low (10−24 g cm−3) external gas density, a disc of SG helium-enhanced stars is formed. The SG is characterized by distinct chemo-dynamical phase space patterns: it shows a more rapid rotation than the FG with the helium-enhanced SG subsystem rotating more rapidly than the moderate helium-enhanced one. In models with high external gas density ($10^{-23}\, {\rm g\ cm^{-3}}$), the inner SG disc is disrupted by the early arrival of external gas and only a small fraction of highly enhanced helium stars preserves the rotation acquired at birth. Variations in the inclination angle between the rotation axis and the direction of the infalling gas and the velocity profile can slightly alter the extent of the stellar disc and the rotational amplitude. The results of our simulations illustrate the complex link between dynamical and chemical properties of multiple populations and provide new elements for the interpretation of observational studies and future investigations of the dynamics of multiple-population GCs.
Improving black hole accretion treatment in hydrodynamical simulations
Authors: Tartėnas Matas , Zubovas Kastytis
Published: August 2022

The large-Galactic scales are connected to the many orders of magnitude smaller supermassive black hole (SMBH) scales by an episodic cycle of feeding and feedback. Active Galactic nuclei (AGN) are powered by accretion on to SMBH and the majority of AGN energy in near-Eddington regime is produced in thin subpc accretion discs. Currently, it is very difficult to model processes that occur on vastly different scales, ranging from the circumnuclear gas reservoirs at tens to hundreds of parsecs down to the accretion disc scales at <0.01 pc. While subgrid prescriptions used in large-scale or cosmological simulations are able to reproduce large-scale feedback, we propose using a more realistic model in parsec-scale simulations, where it is important to get accurate time-scales to understand how feedback affects gas dynamics and star formation in the vicinity of the AGN. To test our approach we use a subresolution thin accretion disc model coupled to the SMBH in a set of hydrodynamical simulations of a retrograde collision between a gas ring and a molecular cloud in an environment similar to the Galactic Centre using the SPH code Gadget-3. The disc-mediated feeding of the SMBH is relatively smooth and delayed compared to an instantaneous feeding prescription. While the reduction of accretion due to feedback is present in both accretion disc and instantaneous feeding simulations, a clear central cavity appears only in accretion disc runs – hinting that a less volatile accretion phase could have a greater impact on the surrounding gas.
Ionized filaments and ongoing physical processes in massive-star-forming sites around l = 345.°5
Authors: Dewangan L K , Pirogov L E , Bhadari N K , Maity A K
Published: August 2022

Numerous research studies on dust and molecular filaments in star-forming sites have been conducted, but only a limited number have focused on ionized filaments. To observationally study this aspect, we present an analysis of multiwavelength data from an area of ∼74.6 arcmin × 55 arcmin around l = 345${_{.}^{\circ}}$5. Using the 843-MHz continuum map, two distinct ionized filaments, namely IF-A (extent ∼8.5 arcmin) and IF-B (extent ∼22.65 arcmin), hosting ionized clumps powered by massive OB stars are identified. Using the 13CO(2–1) and C18O(2–1) line data, the parent molecular clouds of IF-A and IF-B are studied in the velocity range [−21, −10] km s−1, and found to have filamentary appearances. At least two cloud components around −18 and −15 km s−1 towards the parent clouds of IF-A and IF-B are investigated and are found to be connected in velocity space. These filamentary clouds also overlap spatially along the major axis, supporting the filamentary twisting/coupling nature. Noticeable Class I protostars and massive stars appear to be observed towards the common zones of the cloud components. These findings support the collision of two filamentary clouds about 1.2 Myr ago. The existence of the ionized filaments seems to be explained by the combined feedback of massive stars. The molecular filaments associated with IF-A and IF-B favour the outcomes of the most recent model concerning the escape and the trapping of the ionizing radiation from an O star formed in a filament.
The proper motion of stars in dwarf galaxies: distinguishing central density cusps from cores
Authors: de Martino Ivan , Diaferio Antonaldo , Ostorero Luisa
Published: August 2022

We show that measuring the proper motion of ∼2000 stars within a dwarf galaxy, with an uncertainty of 1 km s−1 at most, can establish whether the dark matter (DM) density profile of the dwarf has a central core or cusp. We derive these limits by building mock star catalogues similar to those expected from future astrometric Theia-like missions and including celestial coordinates, radial velocity and proper motion of the stars. The density field of the DM halo of the dwarf is sampled from an extended Navarro–Frank–White (eNFW ) spherical model, whereas the number density distribution of the stars is a Plummer sphere. The velocity field of the stars is set according to the Jeans equations. A Monte Carlo Markov chain algorithm applied to a sample of N ≳ 2000 stars returns unbiased estimates of the eNFW DM parameters within $10{{\ \rm per\, cent}}$ of the true values and with 1σ relative uncertainties ≲ 20 per cent. The proper motions of the stars lift the degeneracy among the eNFW parameters which appears when the line-of-sight velocities alone are available. Our analysis demonstrates that, by estimating the log-slope of the mass density profile estimated at the half-light radius, a sample of N = 2000 stars can distinguish between a core and a cusp at more than 8σ. Proper motions also return unbiased estimates of the dwarf mass profile with 1σ uncertainties that decrease, on average, from 2.65 dex to 0.15 dex when the size of the star sample increases from N = 100 to N = 6000 stars. The measure of the proper motions can thus strongly constrain the distribution of DM in nearby dwarfs and provides fundamental contribution to understanding the nature and the properties of DM.
Propagation time delay and frame dragging effects of lightlike geodesics in the timing of a pulsar orbiting SgrA*
Authors: Ben-Salem Bilel , Hackmann Eva
Published: August 2022

Timing a pulsar in a close orbit around the supermassive black hole SgrA* at the centre of the Milky Way would open the window for an accurate determination of the black hole parameters and for new tests of general relativity and alternative modified gravity theories. An important relativistic effect which has to be taken into account in the timing model is the propagation delay of the pulses in the gravitational field of the black hole. Due to the extreme mass ratio of the pulsar and the supermassive back hole we use the test particle limit to derive an exact analytical formula for the propagation delay of lightlike geodesics in a Kerr space–time, and deduce a relativistic formula for the corresponding frame dragging effect on the arrival time. As an illustration, we treat an edge-on orbit in which the frame dragging effect on the emitted lightlike geodesics is expected to be maximal. We compare our formula for the propagation time delay with Post-Newtonian approaches, and in particular with the frame dragging terms derived in previous works by Wex & Kopeikin and Rafikov & Lai. Our approach correctly identifies the asymmetry of the frame dragging delay with respect to superior conjunction, avoids singularities in the time delay, and indicates that in the Post-Newtonian approach frame dragging effects on the lightlike pulses are generally slightly overestimated.
Environmental dependence of the molecular cloud lifecycle in 54 main-sequence galaxies
Authors: Kim Jaeyeon , Chevance Mélanie , Kruijssen J M Diederik , Leroy Adam K , Schruba Andreas , Barnes Ashley T , Bigiel Frank , Blanc Guillermo A , Cao Yixian , Congiu Enrico , Dale Daniel A , Faesi Christopher M , Glover Simon C O , Grasha Kathryn , Groves Brent , Hughes Annie , Klessen Ralf S , Kreckel Kathryn , McElroy Rebecca , Pan Hsi-An , Pety Jérôme , Querejeta Miguel , Razza Alessandro , Rosolowsky Erik , Saito Toshiki , Schinnerer Eva , Sun Jiayi , Tomičić Neven , Usero Antonio , Williams Thomas G
Published: August 2022

The processes of star formation and feedback, regulating the cycle of matter between gas and stars on the scales of giant molecular clouds (GMCs; ∼100 pc), play a major role in governing galaxy evolution. Measuring the time-scales of GMC evolution is important to identify and characterize the specific physical mechanisms that drive this transition. By applying a robust statistical method to high-resolution CO and narrow-band H α imaging from the PHANGS survey, we systematically measure the evolutionary timeline from molecular clouds to exposed young stellar regions on GMC scales, across the discs of an unprecedented sample of 54 star-forming main-sequence galaxies (excluding their unresolved centres). We find that clouds live for about 1−3 GMC turbulence crossing times (5−30 Myr) and are efficiently dispersed by stellar feedback within 1−5 Myr once the star-forming region becomes partially exposed, resulting in integrated star formation efficiencies of 1−8 per cent. These ranges reflect physical galaxy-to-galaxy variation. In order to evaluate whether galactic environment influences GMC evolution, we correlate our measurements with average properties of the GMCs and their local galactic environment. We find several strong correlations that can be physically understood, revealing a quantitative link between galactic-scale environmental properties and the small-scale GMC evolution. Notably, the measured CO-visible cloud lifetimes become shorter with decreasing galaxy mass, mostly due to the increasing presence of CO-dark molecular gas in such environment. Our results represent a first step towards a comprehensive picture of cloud assembly and dispersal, which requires further extension and refinement with tracers of the atomic gas, dust, and deeply embedded stars.