bluuebunny/crossref_metadata_2025 huggingface dataset:
Moderating effects of trustworthiness between pharmacists and physicians: using partial least squares
Authors: Murshid Mohsen Ali , Mohaidin Zurina , Zayed Mohammad , Al Doghan Mohammed A
Published: September 2021

Objectives

Trustworthiness (TRS) is an essential factor that drives pharmacist–physician collaboration (PPC), which, in turn, improves prescribing behaviour. This study examines the moderating effect of TRS on the relationship between pharmacist expertise, PPC and prescribing decisions of physicians (PPD).

Methods

A total of 393 usable data were collected from selected physicians using a structured questionnaire form. Partial least squares structural equation modelling was adopted for data analysis.

Key findings

The result shows that TRS does not moderate the relationship between pharmacist expertise power and PPD, although the relationship is stronger with higher TRS (β = 0.054, t = 0.483, P > 0.05). As expected, the relationship between PPC and PPD is stronger at high TRS (β = 0.137, t = 1.653, P < 0.05).

Conclusions

TRS plays a ‘dynamic’ role in strengthening the positive impact of high pharmacist collaboration on prescribing rather than a ‘supportive’ role in increasing physicians’ readiness to gather information and recommendations from the pharmacist.
Transfusion-Transmitted Malaria: Two Pediatric Cases From the United States and Their Relevance in an Increasingly Globalized World
Authors: Stubbs Leigh A , Price Michael , Noland Daniel , Fuchs Jennifer , Filkins Laura , McElvania Erin , Luu Hung S , Sebert Michael , Waters Ami , Hsiang Michelle S
Published: September 2021

In non-endemic settings, transfusion-transmitted malaria (TTM) is rare but potentially fatal and becoming more common with globalization. We present two pediatric cases that demonstrate donor screening using questionnaires is subject to error and that TTM should be considered with fever following numerous transfusions in children, particularly sickle cell patients.
Acute Respiratory Failure With Hemoptysis in a Teenager Due to Cystic Echinococcosis
Authors: Blatz Allison M , Laycock Katherine M , Kaur Ishminder , Swami Sanjeev K
Published: September 2021

A previously healthy 14-year-old male presented with abrupt onset respiratory failure with hemoptysis and anaphylaxis. Imaging demonstrated a large, cystic lesion with bronchopleural fistula that was consistent with cystic echinococcosis. He underwent thoracotomy for cyst removal and bronchopleural fistula repair, then completed 3 months of albendazole therapy. He developed recurrence of a bronchopleural fistula 4 months after surgery which improved over time with conservative management. This case highlights pathognomonic imaging and pathology findings for cystic echinococcosis.
3D Printing: an appealing technology for the manufacturing of solid oral dosage forms
Authors: Pitzanti Giulia , Mathew Essyrose , Andrews Gavin P , Jones David S , Lamprou Dimitrios A
Published: September 2021

Objectives

The traditional manufacturing methods of solid oral dosage forms (SODFs) are reported to be time-consuming, highly expensive and not tailored to the patient’s needs. Three-dimensional printing (3DP) is an innovative emerging technology that can help to overcome these issues. The aim of this review is to describe the most employed 3DP technologies, materials and the state of the art on 3DP SODFs. Characterization techniques of 3DP SODFs, challenges and regulatory issues are also discussed.

Key findings

The interest in the investigation of the suitability of 3DP as an alternative strategy for the fabrication of SODFs is growing. Different 3DP technologies and starting materials have been investigated for the development of SODFs. Numerous SODFs with complex geometries and composition, and with different release patterns, have been successfully manufactured via 3DP. Despite that, just one 3DP SODF has reached the market.

3DP can be a promising alternative to the classical SODFs manufacturing methods. However, numerous technically and regulatory challenges still need to be addressed in order 3DP to be extensively used in the pharmaceutical sector.
Performance and paroxetine stability in tablets manufactured by fused deposition modelling-based 3D printing
Authors: Figueiredo Sara , Fernandes Ana I , Carvalho Fátima G , Pinto João F
Published: September 2021

Objectives

The objective of this study was to develop a method for the preparation and characterization of paroxetine (PRX) tablets, obtained by coupling hot-melt extrusion and fused deposition modelling (FDM)-based three-dimensional printing (3DP) technology. The impact of the printing process parameters on the drug stability and on the tablets performance was assessed.

Methods

Tablets were obtained by FDM of hot-melt extruded PRX-loaded filaments. Physicochemical, thermal, spectroscopic, diffractometric analysis and in-vitro dissolution tests of the intermediate products and the finished dosage forms were performed.

Key findings

The characterization of printed tablets evidenced mass and dimensions uniformity, and consistency of drug content and dissolution profile. The formation of amorphous solid dispersions and interaction of formulation components throughout the manufacturing process were demonstrated. Layer thickness, printing temperature, printing and travelling speeds, and infill were the most impacting process parameters on both the physicochemical properties and the in-vitro performance of the 3D-printed tablets.

Conclusions

PRX tablets, meeting compendial limits, were manufactured by 3DP, envisaging their clinical use as individually designed dosage forms. The assessment of the impact of processing parameters on the printed tablets provided insights, which will ultimately allow streamlining of the 3D process set-up for quicker and easier production of patient-centric medicines.
The traditional uses, phytochemistry, pharmacology and toxicology of Dictamnus dasycarpus: a review
Authors: Qin Yu , Quan Hong-Feng , Zhou Xi-Rong , Chen Shu-Juan , Xia Wen-Xin , Li Hang , Huang Huan-Ling , Fu Xue-Yan , Dong Lin
Published: September 2021

Objectives

Dictamnus dasycarpus is a plant of the Rutaceae family, and its root bark is the main part used as a medicine, named ‘Bai-Xian-Pi’. It is used to clear away heat, remove dampness, and dispel wind and also used for detoxification. The purpose of this review is to provide a systematic review about the botany, traditional uses, phytochemistry, pharmacology and toxicology of this plant.

Key findings

More than 200 compounds have been isolated and identified from the plant, including alkaloids and their glycosides, terpenoids and their derivatives and phenylpropanoids. Extensive pharmacological activities of the extracts or compounds of D. dasycarpus in vivo and in vitro were mainly confirmed, including anti-inflammatory activity, protecting cardiovascular activity, improving liver injury and anti-cancer activity.

In this paper, the botany, traditional uses, phytochemistry and pharmacology of D. dasycarpus were reviewed. In the future, D. dasycarpus needs further study, such as paying more attention to quality control and the utilization on agriculture. In addition, discussing the medicinal components of decoction as well as the toxicity will also contribute to the progress of clinical trial studies.
Ganoderma lucidum polysaccharides protect against sepsis-induced cardiac dysfunction by activating SIRT1
Authors: Xu Zhong-Heng , Su Xiao , Yang Geng , Qin Tao , Liu Yu
Published: September 2021

Objective

To investigate whether the silent information regulator 1 (SIRT1) was involved in the protective effects of Ganoderma lucidum polysaccharides (GLP) against sepsis-induced cardiac dysfunction.

Methods

Lipopolysaccharide (LPS)-induced sepsis model was constructed in C57/BL6J mice. Mice were randomly divided into LPS + GLP + EX-527, LPS + EX-527, LPS + GLP, LPS or control group). The levels of serum inflammatory factor markers were examined by ELISA. H&E staining was performed to assess the inflammation. TUNEL staining and bromodeoxyuridine staining were used to observe cell apoptosis and proliferation, respectively. Expression of apoptosis and proliferation-related proteins was detected by western blot.

Key findings

GLP treatment could significantly increase the expression of SIRT1, reduce levels of serum inflammatory factors (TNF-α, IL-1α and IL-6) and inflammatory cells in mice heart tissue of sepsis models (all Ps < 0.01). Compared with LPS group, GLP treatment inhibited apoptosis and promoted proliferation of myocardial tissues (all Ps < 0.01). Besides, EX-527 (SIRT1 inhibitor) treatment could partially reverse the protective effects of GLP against sepsis-induced cardiac dysfunction (all Ps < 0.01).

Conclusions

GLP might play a protective role in sepsis-induced cardiac dysfunction through regulating inflammatory response, apoptosis and proliferation via activating SIRT1. Therefore, GLP is expected to be a probable novel strategy for treatment of sepsis.
Evaluation approach for whole dose distribution in clinical cases using spherical projection and spherical harmonics expansion: spherical coefficient tensor and score method
Authors: Anetai Yusuke , Koike Yuhei , Takegawa Hideki , Nakamura Satoaki , Tanigawa Noboru
Published: September 2021

Whole dose distribution results from well-conceived treatment plans including patient-specific (location, size and shape of tumor, etc.) and facility-specific (clinical policy and goal, equipment, etc.) information. To evaluate the whole dose distribution efficiently and effectively, we propose a method to apply spherical projection and real spherical harmonics (SH) expansion, thus leading to the expanded coefficients as a rank-2 tensor, SH coefficient tensor, for every patient-specific dose distribution. To verify the feature of this tensor, we introduce Isomap from the manifold learning method and multi-dimensional scaling (MDS). Subsequently, we obtained the MDS distance representing similarity, η, and the SH score, ζ, which is a Frobenius norm of the SH coefficient tensor. These were then validated in the intensity-modulated radiation therapy (IMRT) data sets of: (i) 375 mixing treated regions, (ii) 135 head and neck (HN), and (iii) 132 prostate cases, respectively. The MDS map indicated that the SH coefficient tensor enabled a quantitative feature extraction of whole dose distributions. In particular, the SH score systematically detected irregular cases as the deviation higher than +1.5 standard deviations (SD) from the average case, which matched up with clinically irregular case that required very complicated dose distributions. In summary, the proposed SH coefficient tensor is a useful representation of the whole dose distribution. The SH score from the SH coefficient tensor is a convenient and simple criterion used to characterize the entire dose distributions, which is not dependent on the data set.
A word of caution: bilateral axillofemoral bypass could not provide sufficient blood flow in a patient who underwent aortic resection for aortoesophageal fistula: a case report
Authors: Okubo Ryo , Shirasaka Tomonori , Shibagaki Keisuke , Kamiya Hiroyuki
Published: September 2021

An 81-year-old man was transferred to our hospital for a ruptured infected descending aortic aneurysm. An emergency thoracic endovascular aortic repair was performed, but a computed tomography scan 7 days later revealed an aortoesophageal fistula. The establishment of extracorporeal circulation using the femoral artery and utilization of the omentum was considered difficult. We performed bilateral axillofemoral bypass followed by descending aortic resection and esophagectomy. However, the patient’s circulatory insufficiency worsened, and he died on the 18th postoperative day.

In the treatment of aortoesophageal fistula, bilateral axillofemoral bypass is not recommended as an alternative to descending aortic replacement.
Large mediastinal germ cell tumor with disease progression during systemic therapy
Authors: Hsu Diana S , Wilde Sawley A , Banks Kian C , Velotta Jeffrey B
Published: September 2021

A 29-year-old male developed acute onset severe shortness of breath and fevers and was found to have a 17 cm anterior mediastinal mass with immature teratoma and possible mixed germ cell tumor on biopsy. He remained hospitalized during neoadjuvant cisplatin-based chemotherapy due to compressive symptoms from his mass and neutropenic fevers. Despite 3 cycles of therapy, his tumor mildly increased in size. After multidisciplinary discussion, he underwent urgent en bloc resection with a right hemi-clamshell incision. His postoperative course was uncomplicated and he was discharged to home within a week. His final pathology demonstrated mixed germ cell tumor.
Automatic implantable cardioverter defibrillator (AICD) within the abdomen as a cause of adhesive small bowel obstruction (ASBO): a case report
Authors: Shean Christopher J W , Butt Amir
Published: September 2021

Adhesive small bowel obstruction (ASBO) is commonly caused by intra-abdominal adhesions, usually from prior surgery. Conservative management is the mainstay of treatment, with adhesiolysis required for non-resolving obstruction. An unusual patient presentation of ASBO is presented here, where the cause is proposed as an automatic implantable cardioverter defibrillator (AICD) within the abdomen. Although the patient had several presentations of ASBO successfully treated with conservative management, a non-resolving obstruction required surgical management. At laparotomy, the AICD was found to be in close association with extensive matted adhesions to adjacent small bowel. Adhesiolysis was performed, with the AICD implanted in a subrectus pocket. The patient had an uncomplicated recovery, and at review 6 weeks following the operation was found to have a normal bowel habit with nil further episodes concerning for obstruction. This case highlights the importance of non-classical risk factors being a possible cause of ASBO.
Application of the Konno procedure for infective endocarditis in native bicuspid aortic valve with annular abscess extending into the interventricular septum
Authors: Doi Toshio , Nagao Kanetsugu , Obi Hayato , Higashida Akihiko , Aoki Masaya , Yokoyama Shigeki , Nagura Saori , Yamashita Shigeyuki , Yamashita Akio , Fukahara Kazuaki , Yoshimura Naoki
Published: September 2021

Annular abscess is a serious complication of infective endocarditis, which often requires complex surgery and has a very high post-operative mortality rate. The Konno procedure involves valve annuloplasty for a narrow aortic annulus or left ventricular outflow tract stenosis in children; it is also performed for various cardiac conditions in adults. Here, we report a case of the Konno procedure performed in a patient with aortic valve infective endocarditis, with an annular abscess extending into the interventricular septum (IVS). A 58-year-old man who presented to our hospital with fever was diagnosed with aortic valve infective endocarditis caused by Streptococcus saccharolyticus. On echocardiography, an annular abscess in the direction of the IVS was detected, and surgery was planned. The Konno procedure was performed to secure an adequate surgical field and to debride and reconstruct the cavity created by the interventricular septal abscess. The patient was discharged uneventfully 29 days after surgery.
Cadmium interference with iron sensing reveals transcriptional programs sensitive and insensitive to reactive oxygen species
Authors: McInturf Samuel A , Khan Mather A , Gokul Arun , Castro-Guerrero Norma A , Höhner Ricarda , Li Jiamei , Marjault Henri-Baptiste , Fichman Yosef , Kunz Hans-Henning , Goggin Fiona L , Keyster Marshall , Nechushtai Rachel , Mittler Ron , Mendoza-Cózatl David G
Published: September 2021

Iron (Fe) is an essential micronutrient whose uptake is tightly regulated to prevent either deficiency or toxicity. Cadmium (Cd) is a non-essential element that induces both Fe deficiency and toxicity; however, the mechanisms behind these Fe/Cd-induced responses are still elusive. Here we explored Cd- and Fe-associated responses in wild-type Arabidopsis and in a mutant that overaccumulates Fe (opt3-2). Gene expression profiling revealed a large overlap between transcripts induced by Fe deficiency and Cd exposure. Interestingly, the use of opt3-2 allowed us to identify additional gene clusters originally induced by Cd in the wild type but repressed in the opt3-2 background. Based on the high levels of H2O2 found in opt3-2, we propose a model where reactive oxygen species prevent the induction of genes that are induced in the wild type by either Fe deficiency or Cd. Interestingly, a defined cluster of Fe-responsive genes was found to be insensitive to this negative feedback, suggesting that their induction by Cd is more likely to be the result of an impaired Fe sensing. Overall, our data suggest that Fe deficiency responses are governed by multiple inputs and that a hierarchical regulation of Fe homeostasis prevents the induction of specific networks when Fe and H2O2 levels are elevated.
Protocols to Dissolve Amorphous Urate Crystals in Urine
Authors: Behan Kristina Jackson , Johnston Michael A
Published: September 2021

Objective

Amorphous urate crystals can obscure significant findings during a routine urinalysis. There is no standardized protocol to minimize their effect.

Materials and Methods

We tested 210 urine specimens. Three specimens had high red blood cell (RBC) or white blood cell (WBC) counts. Fifty-six specimens formed amorphous urates. Sediment from these specimens was treated with 50 mM sodium hydroxide (NaOH) at a 1:2 and/or 1:4 dilution. We warmed 22 specimens with crystals at various temperatures.

Results

Amorphous urate crystals formed in concentrated urine with an acidic pH. Adding 50 mM NaOH dissolved amorphous urates, revealing the presence of underlying bacteria and yeast, but WBC and RBC counts were grossly decreased. Prewarming unspun specimens to 60°C for 90 seconds dissolved most amorphous urates.

Conclusion

The protocol to eliminate amorphous urate crystals is to prewarm the specimen before testing. Adding 50 mM NaOH to sediment dissolves amorphous urates to enhance the visibility of bacteria and yeast but has a deleterious effect on WBC and RBC.
Densely computable structures
Authors: Calvert Wesley , Cenzer Douglas , Harizanov Valentina
Published: September 2021

In recent years, computability theorists have extensively studied generically and coarsely computable sets. This study of approximate computability was originally motivated by asymptotic density problems in combinatorial group theory. We generalize the notions of generic and coarse computability of sets, introduced by Jockusch and Schupp, to arbitrary structures by defining generically and coarsely computable and computably enumerable structures. There are two directions in which these notions could potentially trivialize: either all structures could have a densely computable copy or only those having a computable (or computably enumerable) copy. We show that some particular classes of structures realize each of these extremal conditions, while other classes realize neither of them. To further explore these concepts, we introduce a graded family of elementarity conditions for substructures, in which we require that the dense sets under consideration be ‘strong’ substructures of the original structure. Here, again, for a given class, the notion could trivialize in the same two directions and we show that both are possible. For each class that we investigate, there is some natural number $n$ such that requiring $\varSigma _{n}$ elementarity of substructures is enough to trivialize the class of generically or densely computable structures, witnessing the essentially structural character of these notions.
An ASP-based solver for parametrized-difference revision
Authors: Aravanis Theofanis
Published: September 2021

In the present article, a solver for the well-behaved concrete revision operators, named parametrized-difference (PD) revision operators, is described. The solver is developed by means of the powerful framework of answer set programming, which constitutes a contemporary modelling tool, oriented towards difficult search problems. Several useful functionalities are supported by the system, namely, dynamic PD revision, query-answering capabilities, integrity-constraints handling and revision under the closed-world assumption. The solver exhibits high performance in a plethora of revision instances, including hard ones of the SATLIB library; the fact that PD revision respects an intuitive relevance-sensitive principle, identified herein, contributes to this high performance. A graphical user interface provides easy interaction with the implemented system, making it a high-end standalone revision-tool for potential artificial intelligence applications.
Modal Logics and Group Polarization
Authors: Young Pedersen Mina , Smets Sonja , Ågotnes Thomas
Published: September 2021

This paper proposes different ways of modally defining properties related to the concept of balance in signed social networks where relations can be either positive or negative. The motivation is to be able to formally reason about the social phenomenon of group polarization based on balance theory. The starting point is a recently developed basic modal logic that axiomatizes the class of social networks that are balanced up to a certain degree. This property is not modally definable but can be captured using a deduction rule. In this work, we examine different possibilities for extending this basic language to define frame properties such as balance and related properties such as non-overlapping positive and negative relations and collective connectedness as axioms. Furthermore, we define the property of full balance rather than balanced-up-to-a-degree. We look into the complexity of the model checking problem and show a non-compactness result of the extended language. Along the way, we provide axioms for weak balance. We also look at a full hybrid extension and reason about network changes with dynamic modalities. Then, to explore the measures of how far a network is from polarization, we consider variations of measures in relation to balance.
Continual arrival and the longue durée: Emplacement as activism among migrant workers in Hong Kong
Authors: Constable Nicole
Published: September 2021

Most studies of ‘emplacement’ focus on immigrants or refugees who seek permanent settlement. In contrast, this article examines the significance of emplacement for ‘temporary migrants’ who live under conditions of ongoing arrival, contingency, and temporariness and have no expectation of remaining permanently. For temporary migrant workers in Hong Kong, specifically domestic workers, I argue that emplacement has become a form of collective and ongoing activism. It does not rely on any one person’s or one group’s permanence but persists across the longue durée. This activism builds social ties and produces sociability to claim a collective presence that offers nurturance and is a form of rights-claiming. Both economically and socially marginal, foreign domestic workers in Hong Kong claim their central place, socially and geographically, and they collectively demand recognition and visibility. Within the context of temporary migrant workers’ ongoing arrival at the margins, this article examines ethnographic materials from three temporal strata (between 1990 and 2020) to illustrate how emplacement is produced and reproduced through conscious efforts and the production of sociality and sociability across time. More broadly, this article contributes to critical analyses of conceptual binaries of margin and center, permanent and temporary, migrant and citizen, and highlights the coevalness of temporary migrants and nonmigrants.
Opportunistic yeast pathogenCandidaspp.: Secreted and membrane-bound virulence factors
Authors: Lim Si Jie , Mohamad Ali Mohd Shukuri , Sabri Suriana , Muhd Noor Noor Dina , Salleh Abu Bakar , Oslan Siti Nurbaya
Published: September 2021

Candidiasis is a fungal infection caused by Candida spp. especially Candida albicans, C. glabrata, C. parapsilosis and C. tropicalis. Although the medicinal therapeutic strategies have rapidly improved, the mortality rate as candidiasis has continuously increased. The secreted and membrane-bound virulence factors (VFs) are responsible for fungal invasion, damage and translocation through the host enterocytes besides the evasion from host immune system. VFs such as agglutinin-like sequences (Als), heat shock protein 70, phospholipases, secreted aspartyl proteinases (Sap), lipases, enolases and phytases are mostly hydrolases which degrade or interact with the enterocyte membrane components. Candidalysin, however, acts as a peptide toxin to induce necrotic cell lysis. To date, structural studies of the VFs remain underexplored, hindering their functional analyses. Among the VFs, only Sap and Als have their structures deposited in Protein Data Bank (PDB). Therefore, this review scrutinizes the mechanisms of these VFs by discussing the VF-deficient studies of several Candida spp. and their abilities to produce these VFs. Nonetheless, their latest reported sequential and structural analyses are discussed to impart a wider perception of the host-pathogen interactions and potential vaccine or antifungal drug targets. This review signifies that more VFs structural investigations and mining in the emerging Candida spp. are required to decipher their pathogenicity and virulence mechanisms compared to the prominent C. albicans.

Lay summary

Candida virulence factors (VFs) including mainly enzymes and proteins play vital roles in breaching the human intestinal barrier and causing deadly invasive candidiasis. Limited VFs’ structural studies hinder deeper comprehension of their mechanisms and thus the design of vaccines and antifungal drugs against fungal infections.
NGTS clusters survey – III. A low-mass eclipsing binary in the Blanco 1 open cluster spanning the fully convective boundary
Authors: Smith Gareth D , Gillen Edward , Queloz Didier , Hillenbrand Lynne A , Acton Jack S , Alves Douglas R , Anderson David R , Bayliss Daniel , Briegal Joshua T , Burleigh Matthew R , Casewell Sarah L , Delrez Laetitia , Dransfield Georgina , Ducrot Elsa , Gill Samuel , Gillon Michaël , Goad Michael R , Günther Maximilian N , Henderson Beth A , Jenkins James S , Jehin Emmanuël , Moyano Maximiliano , Murray Catriona A , Pedersen Peter P , Sebastian Daniel , Thompson Samantha , Tilbrook Rosanna H , Triaud Amaury H M J , Vines Jose I , Wheatley Peter J
Published: September 2021

We present the discovery and characterization of an eclipsing binary identified by the Next Generation Transit Survey in the ∼115-Myr-old Blanco 1 open cluster. NGTS J0002−29 comprises three M dwarfs: a short-period binary and a companion in a wider orbit. This system is the first well-characterized, low-mass eclipsing binary in Blanco 1. With a low mass ratio, a tertiary companion, and binary components that straddle the fully convective boundary, it is an important benchmark system, and one of only two well-characterized, low-mass eclipsing binaries at this age. We simultaneously model light curves from NGTS, TESS, SPECULOOS, and SAAO, radial velocities from VLT/UVES and Keck/HIRES, and the system’s spectral energy distribution. We find that the binary components travel on circular orbits around their common centre of mass in Porb = 1.098 005 24 ± 0.000 000 38 d, and have masses Mpri = 0.3978 ± 0.0033 M⊙ and Msec = 0.2245 ± 0.0018 M⊙, radii Rpri = 0.4037 ± 0.0048 R⊙ and Rsec = 0.2759 ± 0.0055 R⊙, and effective temperatures $T_{\rm pri}=\mbox{$3372\, ^{+44}_{-37}$}$ K and $T_{\rm sec}=\mbox{$3231\, ^{+38}_{-31}$}$ K. We compare these properties to the predictions of seven stellar evolution models, which typically imply an inflated primary. The system joins a list of 19 well-characterized, low-mass, sub-Gyr, stellar-mass eclipsing binaries, which constitute some of the strongest observational tests of stellar evolution theory at low masses and young ages.
Gamma-rays and neutrinos from RX J1713–3946 in a lepto–hadronic scenario
Authors: Cristofari P , Niro V , Gabici S
Published: September 2021

The gamma-ray emission of RX J1713–3946, despite being extensively studied in the GeV and TeV domains, remains poorly understood. This is mostly because, in this range, two competing mechanisms can efficiently produce gamma-rays: the inverse Compton scattering of accelerated electrons, and interactions of accelerated protons with the nuclei of the interstellar medium (ISM). In addition to the acceleration of particles from the thermal pool, the re-acceleration of pre-existing cosmic rays is often overlooked, and has in fact also been taken into account. Especially, because of the distance to the SNR (∼1 kpc), and the low density in which the shock is currently expanding (∼10−2 cm−3), the re-acceleration of cosmic-ray electrons pre-existing in the ISM can account for a significant fraction of the observed gamma-ray emission, and contribute to the shaping of the spectrum in the GeV–TeV range. Remarkably, this emission of leptonic origin is found to be close to the level of the gamma-ray signal in the TeV range, provided that the spectrum of pre-exisiting cosmic-ray electrons is similar to that observed in the local ISM. The overall gamma-ray spectrum of RX J1713–3946 is naturally produced as the sum of leptonic emission from re-accelerated cosmic-ray electrons, and a subdominant hadronic emission from accelerated protons. We also argue that neutrino observations with next-generation detectors might lead to a detection even in the case of a lepto–hadronic origin of the gamma-ray emission.
Canis Major OB1 stellar group contents revealed by Gaia
Authors: Santos-Silva T , Perottoni H D , Almeida-Fernandes F , Gregorio-Hetem J , Jatenco-Pereira V , Mendes de Oliveira C , Montmerle T , Bica E , Bonatto C , Monteiro H , Dias W S , Barbosa C E , Fernandes B , Galli P A B , Borges Fernandes M , Kanaan A , Ribeiro T , Schoenell W
Published: September 2021

Canis Major OB1 (CMa OB1) is a Galactic stellar association with a very intriguing star-formation scenario. There are more than two dozen known star clusters in its line of sight, but it is not clear which ones are physically associated with CMa OB1. We use a clustering code that employs five-dimensional data from the Gaia DR2 catalogue to identify physical groups and obtain their astrometric parameters and, in addition, we use two different isochrone-fitting methods to estimate the ages of these groups. We find 15 stellar groups with distances between 570 and 1650 pc, including 10 previously known and five new open cluster candidates. Four groups, precisely the youngest ones (< 20 Myr), CMa05, CMa06, CMa07, and CMa08, are confirmed to be part of CMa OB1. We find that CMa08, a new cluster candidate, may be the progenitor cluster of runaway stars. CMa06 coincides with the well-studied CMa R1 star-forming region. While CMa06 is still forming stars, due to the remaining material of the molecular cloud associated with the Sh 2-262 nebula, CMa05, CMa07, and CMa08 seem to be in more evolved stages of evolution, with no recent star-forming activity. The properties of these CMa OB1 physical groups fit well in a monolithic scenario of star formation, with a common formation mechanism, and having suffered multiple episodes of star formation. This suggests that the hierarchical model alone, which explains the populations of other parts of the same association, is not sufficient to explain its whole formation history.
Low-radio frequency observations of seven nearby galaxies with GMRT
Authors: Roy Subhashis , Manna Souvik
Published: September 2021

We have observed seven nearby large-angular-sized galaxies at 0.33 GHz using Giant Metrewave Radio Telescope with an angular resolution of ∼10 arcsec and sub-mJy sensitivity. Using archival higher frequency data at 1.4 or ∼6 GHz, we have then determined their spatially resolved non-thermal spectrum. As a general trend, we find that the spectral indices are comparatively flat at the galaxy centres and gradually steepen with increasing galactocentric distances. Using archival far-infrared (FIR) MIPS 70-${\mu }\mathrm{m}$ data, we estimate the exponent of radio–FIR correlation. One of the galaxies (NGC 4826) was found to have an exponent of the correlation of ∼1.4. Average exponent from 0.33-GHz data for the rest of the galaxies was 0.63 ± 0.06 and is significantly flatter than the exponent 0.78 ± 0.04 obtained using 1.4-GHz data. This indicates cosmic-ray electron (CRe) propagation to have reduced the correlation between FIR and 0.33-GHz radio. Assuming a model of simple isotropic diffusion of CRe, we find that the scenario can explain the frequency-dependent CRe propagation length-scales for only two galaxies. Invoking streaming instability could, however, explain the results for the majority of the remaining ones.
On the narrow spectral feature at ∼3 TeV in the MAGIC spectrum of Mrk 501
Authors: Hu Wen , Yan Dahai
Published: September 2021

Using a time-dependent one-zone leptonic model that incorporates both shock acceleration and stochastic acceleration processes, we investigate the formation of the narrow spectral feature at ∼3 TeV of Mrk 501 which was observed during the X-ray and TeV flaring activity in 2014 July. It is found that the broad-band spectral energy distribution (SED) can be well interpreted as the synchrotron and synchrotron-self-Compton emission from the electron energy distribution (EED) that is composed by a power-law (PL) branch and a pileup branch. The PL branch produces synchrotron photons which are scattered by the electrons of the pileup branch via inverse-Compton scattering and form the narrow spectral feature observed at the TeV energies. The EED is produced by two injection episodes, and the pileup branch in EED is caused by shock acceleration rather than stochastic acceleration.
Discovery of galaxy clusters and a head–tail radio galaxy in the direction of globular cluster NGC 6752
Authors: Cheng Zhongqun , Sun Xiaohui , Wang Wei , Li Zhiyuan
Published: September 2021

We report on the discovery of CXOU J191100–595621 and CXOU J191012–595619, two galaxy clusters serendipitously detected in the direction of globular cluster NGC 6752, based on archival Chandra observations with a total exposure time of ∼344 ks. The deep Chandra X-ray data enabled us to measure the properties of both systems. We found a redshift of z = 0.239 ± 0.013 and z = 0.375 ± 0.016, a temperature of $kT=3.32^{+0.57}_{-0.46}$ keV and $kT=3.71^{+1.18}_{-0.86}$ keV, an iron abundance of $Z_{\rm Fe}=0.64^{+0.34}_{-0.29}Z_{\rm Fe\odot }$ and $Z_{\rm Fe}=1.29^{+0.97}_{-0.65}Z_{\rm Fe\odot }$ and a rest-frame full band (0.5–7 keV) luminosity of $L_{\rm X}=9.2^{+1.2}_{-1.1}\times 10^{43} {\rm \, erg\, s^{-1}}$ and $L_{\rm X}=9.9^{+2.7}_{-2.2}\times 10^{43} {\rm \, erg\, s^{-1}}$ for CXOU J191100–595621 and CXOU J191012–595619, respectively. The temperature profile of CXOU J191100–595621 is found to decrease with decreasing radius, indicating a cool core in this cluster. The hydrostatic equilibrium estimation suggests that the clusters are moderately weighted, with $M_{500}=(1.3\pm 0.4)\times 10^{14}\, \mathrm{M}_{\odot }$ and $M_{500}=(2.0\pm 1.5)\times 10^{14}\, \mathrm{M}_{\odot }$, respectively. We search for optical and radio counterparts of X-ray point sources in the clusters. Three active galactic nuclei are found, among which one is identified with a narrow-angle-tail radio galaxy, and one is found to be associated with the brightest central galaxy of CXOU J191100–595621.
Hidden in the haystack: low-luminosity globular clusters towards the Milky Way bulge
Authors: Gran F , Zoccali M , Saviane I , Valenti E , Rojas-Arriagada A , Contreras Ramos R , Hartke J , Carballo-Bello J A , Navarrete C , Rejkuba M , Olivares Carvajal J
Published: September 2021

Recent wide-area surveys have enabled us to study the Milky Way with unprecedented detail. Its inner regions, hidden behind dust and gas, have been partially unveiled with the arrival of near-infrared (IR) photometric and spectroscopic data sets. Among recent discoveries, there is a population of low-mass globular clusters, known to be missing, especially towards the Galactic bulge. In this work, five new low-luminosity globular clusters located towards the bulge area are presented. They were discovered by searching for groups in the multidimensional space of coordinates, colours, and proper motions from the Gaia EDR3 catalogue and later confirmed with deeper VVV survey near-IR photometry. The clusters show well-defined red giant branches and, in some cases, horizontal branches with their members forming a dynamically coherent structure in proper motion space. Four of them were confirmed by spectroscopic follow-up with the MUSE instrument on the ESO VLT. Photometric parameters were derived, and when available, metallicities, radial velocities, and orbits were determined. The new clusters Gran 1 and 5 are bulge globular clusters, while Gran 2, 3 and 4 present halo-like properties. Preliminary orbits indicate that Gran 1 might be related to the Main Progenitor, or the so-called ‘low-energy’ group, while Gran 2, 3 and 5 appears to follow the Gaia-Enceladus/Sausage structure. This study demonstrates that the Gaia proper motions, combined with the spectroscopic follow-up and colour–magnitude diagrams, are required to confirm the nature of cluster candidates towards the inner Galaxy. High stellar crowding and differential extinction may hide other low-luminosity clusters.
The abacus cosmological N-body code
Authors: Garrison Lehman H , Eisenstein Daniel J , Ferrer Douglas , Maksimova Nina A , Pinto Philip A
Published: September 2021

We present abacus, a fast and accurate cosmological N-body code based on a new method for calculating the gravitational potential from a static multipole mesh. The method analytically separates the near- and far-field forces, reducing the former to direct 1/r2 summation and the latter to a discrete convolution over multipoles. The method achieves 70 million particle updates per second per node of the Summit supercomputer, while maintaining a median fractional force error of 10−5. We express the simulation time-step as an event-driven ‘pipeline’, incorporating asynchronous events such as completion of co-processor work, input/output, and network communication. abacus has been used to produce the largest suite of N-body simulations to date, the abacussummit suite of 60 trillion particles, incorporating on-the-fly halo finding. abacus enables the production of mock catalogues of the volume and resolution required by the coming generation of cosmological surveys.
Broad-band study of BL Lac during flare of 2020: spectral evolution and emergence of HBL component
Authors: Prince Raj
Published: September 2021

BL Lacertae (BL Lac) is categorized as TeV blazar and considered as a possible source of astrophysical neutrinos. In 2020, the brightest X-ray flare ever detected from it. A detailed study can answer many puzzling questions related to multiband emissions and fast-flux variability often seen in this kind of source. We have performed the temporal and spectral analysis of the brightest flare. The variability is characterized by the fractional variability amplitude and the variability time. We found that the source has crossed all its previous limits of flux and reached to a maximum ever seen from it in optical and X-rays. It is highly variable in X-rays with fractional variability above 100 per cent (1.8397 ± 0.0181) and the fastest variability time of 11.28 h within a day. The broad-band light-curves correlation with X-ray suggest a time lag of one day. A broad-band SED modelling is pursued to understand the possible physical mechanisms responsible for broad-band emission. Modelling requires two emission regions located at two different sites to explain the low and high flux states. A significant spectral change is observed in the optical-UV and X-ray spectrum during the high state, which eventually leads to shifts in the location of the synchrotron peak towards higher energy, suggesting an emergence of a new HBL component.
A broad-band radio study of PSR J0250+5854: the slowest spinning radio pulsar known
Authors: Agar C H , Weltevrede P , Bondonneau L , Grießmeier J-M , Hessels J W T , Huang W J , Karastergiou A , Keith M J , Kondratiev V I , Künsemöller J , Li D , Peng B , Sobey C , Stappers B W , Tan C M , Theureau G , Wang H G , Zhang C M , Cecconi B , Girard J N , Loh A , Zarka P
Published: September 2021

We present radio observations of the most slowly rotating known radio pulsar PSR J0250+5854. With a 23.5-s period, it is close, or even beyond, the P-$\dot{P}$ diagram region thought to be occupied by active pulsars. The simultaneous observations with the Five-hundred-metre Aperture Spherical radio Telescope (FAST), the Chilbolton and Effelsberg Low Frequency Array (LOFAR) international stations, and New Extension in Nançay Upgrading loFAR (NenuFAR) represent a five-fold increase in the spectral coverage of this object, with the detections at 1250 (FAST) and 57 MHz (NenuFAR) being the highest and lowest frequency published, respectively, to date. We measure a flux density of 4 ± 2 $\mu$Jy at 1250 MHz and an exceptionally steep spectral index of $-3.5^{+0.2}_{-1.5}$, with a turnover below ∼95 MHz. In conjunction with observations of this pulsar with the Green Bank Telescope and the LOFAR Core, we show that the intrinsic profile width increases drastically towards higher frequencies, contrary to the predictions of conventional radius-to-frequency mapping. We examine polarimetric data from FAST and the LOFAR Core and conclude that its polar cap radio emission is produced at an absolute height of several hundreds of kilometres around 1.5 GHz, similar to other rotation-powered pulsars across the population. Its beam is significantly underfilled at lower frequencies, or it narrows because of the disappearance of conal outriders. Finally, the results for PSR J0250+5854 and other slowly spinning rotation-powered pulsars are contrasted with the radio-detected magnetars. We conclude that magnetars have intrinsically wider radio beams than the slow rotation-powered pulsars, and that consequently the latter’s lower beaming fraction is what makes objects such as PSR J0250+5854 so scarce.
Searching for Fermi GRB optical counterparts with the prototype Gravitational-wave Optical Transient Observer (GOTO)
Authors: Mong Y-L , Ackley K , Galloway D K , Dyer M , Cutter R , Brown M J I , Lyman J , Ulaczyk K , Steeghs D , Dhillon V , O’Brien P , Ramsay G , Noysena K , Kotak R , Breton R , Nuttall L , Pallé E , Pollacco D , Thrane E , Awiphan S , Burhanudin U , Chote P , Chrimes A , Daw E , Duffy C , Eyles-Ferris R , Gompertz B , Heikkilä T , Irawati P , Kennedy M , Killestein T , Levan A , Littlefair S , Makrygianni L , Marsh T , Mata-Sanchez D , Mattila S , Maund J , McCormac J , Mkrtichian D , Mullaney J , Rol E , Sawangwit U , Stanway E , Starling R , Strøm P , Tooke S , Wiersema K
Published: September 2021

The typical detection rate of ∼1 gamma-ray burst (GRB) per day by the Fermi Gamma-ray Burst Monitor (GBM) provides a valuable opportunity to further our understanding of GRB physics. However, the large uncertainty of the Fermi localization typically prevents rapid identification of multiwavelength counterparts. We report the follow-up of 93 Fermi GRBs with the Gravitational-wave Optical Transient Observer (GOTO) prototype on La Palma. We selected 53 events (based on favourable observing conditions) for detailed analysis, and to demonstrate our strategy of searching for optical counterparts. We apply a filtering process consisting of both automated and manual steps to 60 085 candidates initially, rejecting all but 29, arising from 15 events. With ≈3 GRB afterglows expected to be detectable with GOTO from our sample, most of the candidates are unlikely to be related to the GRBs. Since we did not have multiple observations for those candidates, we cannot confidently confirm the association between the transients and the GRBs. Our results show that GOTO can effectively search for GRB optical counterparts thanks to its large field of view of ≈40 deg2 and its depth of ≈20 mag. We also detail several methods to improve our overall performance for future follow-up programmes of Fermi GRBs.
Strong scatterings of cold Jupiters and their influence on inner low-mass planet systems: theory and simulations
Authors: Pu Bonan , Lai Dong
Published: September 2021

Recent observations have indicated a strong connection between compact (a ≲ 0.5 au) super-Earth and mini-Neptune systems and their outer (a ≳ a few au) giant planet companions. We study the dynamical evolution of such inner systems subject to the gravitational effect of an unstable system of outer giant planets, focusing on systems whose end configurations feature only a single remaining outer giant. In contrast to similar studies which used on N-body simulations with specific (and limited) parameters or scenarios, we implement a novel hybrid algorithm which combines N-body simulations with secular dynamics with aims of obtaining analytical understanding and scaling relations. We find that the dynamical evolution of the inner planet system depends crucially on Nej, the number of mutual close encounters between the outer planets prior to eventual ejection/merger. When Nej is small, the eventual evolution of the inner planets can be well described by secular dynamics. For larger values of Nej, the inner planets gain orbital inclination and eccentricity in a stochastic fashion analogous to Brownian motion. We develop a theoretical model, and compute scaling laws for the final orbital parameters of the inner system. We show that our model can account for the observed eccentric super-Earths/mini-Neptunes with inclined cold Jupiter companions, such as HAT-P-11, Gliese 777, and π Men.
Radiative MHD simulations of photon bubbles in radiation-supported magnetized atmospheres of neutron stars with isotropic Thomson scattering
Authors: (张力中) Lizhong Zhang , Blaes Omer , (姜燕飞) Yan-Fei Jiang
Published: September 2021

A major uncertainty in the structure and dynamics of magnetized, radiation pressure dominated neutron star accretion columns in X-ray pulsars and pulsating ultraluminous X-ray sources is that they are thought to be subject to the photon bubble instability. We present the results of two-dimensional radiation relativistic magnetohydrodynamic simulations of a non-accreting, static atmosphere to study the development of this instability assuming isotropic Thomson scattering in the slow diffusion regime that is relevant to neutron star accretion columns. Photon bubbles generally grow faster towards shorter wavelengths, until a maximum growth rate is achieved at the radiation viscosity length-scale, which is generally quite small and requires high numerical resolution to simulate. We confirm the consistency between our simulation results and linear theory in detail, and show that the non-linear evolution inevitably leads to collapse of the atmosphere with the higher resolution simulation collapsing faster due to the presence of shorter length-scale non-linear structures. At least in static atmospheres with horizontally periodic boundary conditions, this resolution dependence may make simulations of the non-linear dynamics of photon bubble instability in neutron star accretion columns challenging. It remains to be seen whether these difficulties will persist upon inclusion of an accretion flow through the top and magnetically confined horizontal boundaries through which photons can escape. Our results here provide a foundation for such future work.