bluuebunny/crossref_metadata_2025 huggingface dataset:
Left-sided accessory pathways successfully ablated from the aortomitral continuity region: distinctive atrial activation patterns and anatomic concerns
Authors: Li Meng-Meng , Long De-Yong , Sang Cai-Hua , Jiang Chen-Xi , Guo Xue-Yuan , Zhao Xin , Li Song-Nan , Wang Wei , Tang Ri-Bo , Li Jing-Ye , Dai Wen-Li , Kong Xiang-Yi , Zuo Song , Ning Man , Li Xu , Wu Jia-Hui , Dong Jian-Zeng , Du Xin , Ma Chang-Sheng
Published: May 2020

Aims

Accessory pathways (APs) successfully ablated at the aortomitral continuity (AMC) were sporadically reported but relevant data are very limited. We aimed to describe the electrophysiological characteristics of AMC-AP and the related anatomy.

Methods and results

This study involved eight (male/female = 3/5, mean age 42.6 ± 10.5 years) patients with left-sided AP successfully ablated in the AMC region. The retrograde atrial activation sequence was analysed and compared via recordings at the His-bundle (HB), coronary sinus (CS), and roving catheter during tachycardia, and the peak of QRS from the same cardiac circle used as time reference. Of the eight patients, two received prior ablations. During tachycardia, the activation time at the proximal CS (CSp), lateral CS (CSl), and HB region averaged 120 ± 26 ms, 124 ± 29 ms, and 117 ± 21 ms following the reference, respectively (P = 0.86). The latest atrial activation was recorded in the posterior CS which averaged 135 ± 25 ms following the reference. Placing the ablation catheter to AMC via retrograde approach was attempted in all cases but stable positioning achieved in none. Via transseptal approach, the ablation catheter could be easily placed at the AMC and recorded the earliest retrograde atrial activations with 60 ± 27 ms earlier than the relatively ‘earliest’ CS/HB recordings, and ablation at this site successfully eliminated AP conduction. No patients had recovered AP conduction after at least 12-month follow-up.

Conclusion

AMC-AP is featured by recording comparable retrograde atrial activation times at CSp, CSl, and HB with the latest recordings at the posterior CS. Stable placement and successful ablation in the AMC via retrograde aortic approach was difficult but can be achieved via transseptal approach.
Timing and evolution of advanced conduction disturbances in patients with right bundle branch block undergoing transcatheter aortic valve replacement
Authors: Muntané-Carol Guillem , del Val David , Junquera Lucía , Faroux Laurent , Delarochellière Robert , Paradis Jean-Michel , Mohammadi Siamak , Kalavrouziotis Dimitri , Dumont Eric , Philippon François , Rodés-Cabau Josep
Published: May 2020

Aims

This study sought to determine the timing and evolution over time of advanced conduction disturbances (CDs) in patients with baseline right bundle branch block (RBBB) undergoing transcatheter aortic valve replacement (TAVR).

Methods and results

One hundred and ten consecutive patients with pre-existing RBBB were included (out of 1341, 8.2%). All arrhythmias during the hospitalization period were recorded. Follow-up was performed at 30 days, 1 year, and yearly thereafter. Conduction recovery and ventricular pacing percentage (VPP) was evaluated at 30 days in those patients with permanent pacemaker implantation (PPMI). Sixty-one (55.5%) patients suffered advanced CDs [97% complete or high-degree atrioventricular block (CHB/HAVB)], and the vast majority (98%) occurred within the first 3 days post-procedure (intraprocedural: 85%). Fifty-two (47.3%) patients had PPMI (vs. 11.0% in non-RBBB patients, P < 0.001). Ventricular pacing percentage at 1 month was higher in patients with persistent-intraprocedural CHB/HAVB compared to those with transient-intraprocedural or post-procedural CHB/HAVB [99 (interquartile range, IQR 97–100)% vs. 72 (IQR 30–99)%, P = 0.02]. Complete recovery (VPP < 1%) was observed in only one patient (2%) with CHB/HAVB. After hospital discharge, no symptomatic bradyarrhythmias or sudden death occurred within 30 days. Patients with pre-existing RBBB exhibited a higher risk of PPMI at 4-year follow-up (26% vs. 8% in non-RBBB patients, P < 0.001).

Conclusion

In patients with pre-existing RBBB, the vast majority of advanced CDs occurred within the 3 days following TAVR, and most did not recover at 1-month, particularly those with intra-procedural persistent CHB/HAVB. These results should help to determine the hospitalization length and timing of PPMI in RBBB patients undergoing TAVR.
Got Selenium?
Authors: Oremland Ronald S
Published: May 2020

‘There's antimony, arsenic, aluminum, selenium, and hydrogen, and oxygen, and nitrogen and rhenium’—so begins ‘The Elements’ song (https://www.youtube.com/watch?v=AcS3NOQnsQM), whereby Tom Lehrer (Fig. 1) assiduously deconstructed the many painstaking decades of research effort by scores of scientists in assembling the Periodic Table as primarily based upon the atomic numbers of the elements. Lehrer instead opted for his imaginative rhyme, with its musical meter purloined from the patter song of Major General Stanley ("I am the Very Model of a Modern Major General’) as in the Gilbert and Sullivan's operetta ‘The Pirates of Penzance’. By some coincidence, however, three of the four named in the first stanza are Group 15 and 16 elements with which I have considerable microbiological research experience. Only one is missing (tellurium). Hence, by futzing with Lehrer's ‘libretto’ to suit my own needs for this issue of FEMS, I would pose the following introductory re-rearrangement: ‘There's antimony, arsenic, selenium, tellurium, and cadmium, and chromium, and calcium and curium’. While this may (or may not) sit well with Mr Lehrer, who at the time of this writing is still living, I hope it does not cause further discomfiture to the collective eternal peace of Professor Dimitri Mendeleev, Sir William Schwenk Gilbert and Sir Arthur Sullivan. Nonetheless, I will use this preface to take departure for the primary subject of this manuscript, namely our efforts on selenium, which is where it all got started.
The development of allometric systems of equations for compatible area-based LiDAR-assisted estimation
Authors: Yang Ting-Ru , Kershaw John A , Ducey Mark J
Published: May 2020

Light detection and ranging (LiDAR) is used to estimate tree, stand and forest characteristics across large geographic areas. In most analyses, several independent LiDAR-based allometric equations are built to predict various forest attributes. When each forest attribute is estimated independently, there is potential for predictions of forest attributes that are not mathematically or biologically consistent. Combined allometric equations can be considered a system of equations describing the stand structure. Mathematically compatible and biologically meaningful estimates can be derived by estimating key structural variables and solving for other components, rather than estimating each forest attribute separately and independently. In this study, we propose the development of a system of allometric equations describing the relationship between volume per unit area, Lorey’s average height, basal area, quadratic mean diameter (QMD) and density. The system of allometric equations is derived from extensive field data. Key structural attributes are predicted using LiDAR metrics, and the remaining structural variables are solved for using the system of allometric equations. Predictions of structural attributes from the system of allometric equations are compared with predictions from independent LiDAR-derived prediction equations. Results showed that applying the systems approach can provide reasonable and compatible estimates with lower required sample sizes, especially when multiple attributes need to be considered simultaneously. Testing the portability of the systems approach in more complex stand structures and across different LiDAR acquisitions will be required in the future.
ThewclYgene ofEscherichia coliserotype O117 encodes an α1,4-glucosyltransferase with strict acceptor specificity but broad donor specificity
Authors: Kocev Alexander , Melamed Jacob , Torgov Vladimir , Danilov Leonid , Veselovsky Vladimir , Brockhausen Inka
Published: May 2020

The O antigen of enterotoxigenic Escherichia coli serotype O117 consists of repeating units with the structure [-D-GalNAcβ1-3-L-Rhaα1-4-D-Glcα1-4-D-Galβ1-3-D-GalNAcα1-4]n. A related structure is found in E. coli O107 where Glc is replaced by a GlcNAc residue. The O117 and O107 antigen biosynthesis gene clusters are homologous and reveal the presence of four putative glycosyltransferase (GT) genes, wclW, wclX, wclY and wclZ, but the enzymes have not yet been biochemically characterized. We show here that the His6-tagged WclY protein expressed in E. coli Lemo21(DE3) cells is an α1,4-Glc-transferase that transfers Glc to the Gal moiety of Galβ1-3GalNAcα-OPO3-PO3-phenoxyundecyl as a specific acceptor and that the diphosphate moiety of this acceptor is required. WclY utilized UDP-Glc, TDP-Glc, ADP-Glc, as well as UDP-GlcNAc, UDP-Gal or UDP-GalNAc as donor substrates, suggesting an unusual broad donor specificity. Activity using GDP-Man suggested the presence of a novel Man-transferase in Lemo21(DE3) cells. Mutations of WclY revealed that both Glu residues of the Ex7E motif within the predicted GT domain are essential for activity. High GlcNAc-transferase (GlcNAc-T) activities of WclY were created by mutating Arg194 to Cys. A triple mutant identical to WclY in E. coli O107 was identified as an α1,4 GlcNAc-T. The characterization of WclY opens the door for the development of antibacterial approaches.
The Centre-Quotient Property and Weak Centrality forC*-Algebras
Authors: Archbold Robert J , Gogić Ilja
Published: May 2020

We give a number of equivalent conditions (including weak centrality) for a general $C^*$-algebra to have the centre-quotient property. We show that every $C^*$-algebra $A$ has a largest weakly central ideal $J_{wc}(A)$. For an ideal $I$ of a unital $C^*$-algebra $A$, we find a necessary and sufficient condition for a central element of $A/I$ to lift to a central element of $A$. This leads to a characterisation of the set $V_A$ of elements of an arbitrary $C^*$-algebra $A$, which prevent $A$ from having the centre-quotient property. The complement $\textrm{CQ}(A):= A \setminus V_A$ always contains $Z(A)+J_{wc}(A)$ (where $Z(A)$ is the centre of $A$), with equality if and only if $A/J_{wc}(A)$ is abelian. Otherwise, $\textrm{CQ}(A)$ fails spectacularly to be a $C^*$-subalgebra of $A$.
Associations of types of primary care facilities with adult vaccination and cancer screening in Japan
Authors: Aoki Takuya , Fukuhara Shunichi
Published: May 2020

Objective

To examine the association between primary care facility types and the quality of preventive care, especially adult vaccination and cancer screening, with a focus on the differences between community clinics and hospitals.

Design

Multicenter cross-sectional study.

Setting

A primary care practice-based research network in Japan (25 primary care facilities).

Participants

Adult outpatients for whom the participating facility serves as their usual source of care.

Intervention

None.

Main Outcome Measures

Influenza and pneumococcal vaccination delivery and performance of colorectal, breast and cervical cancer screening.

Results

Data collected from 1725 primary care outpatients were analyzed. After adjustment of possible confounders and clustering within facilities, hospital-based practices were significantly associated with poorer uptake of influenza [adjusted odds ratio (aOR) = 0.64, 95% confidence interval (CI) 0.42–0.96] and pneumococcal vaccines (aOR = 0.55, 95% CI 0.40–0.75) and colorectal cancer screening (aOR = 0.59, 95% CI 0.39–0.88) compared with clinic-based practices. In contrast, the associations of types of primary care facilities with uptake of breast and cervical cancer screening were not statistically significant.

Conclusions

Differences in the performance of adult vaccination and cancer screening raised concerns about the provision of preventive care at hospital-based compared with clinic-based primary care practices. Efforts to improve preventive care at hospital-based primary care practices should help to promote equalization of the quality of primary care. Further study is needed on the comparisons of other quality indicators among different structures of primary care facilities.
Non-electrophilic TRPA1 agonists, menthol, carvacrol and clotrimazole, open epithelial tight junctions via TRPA1 activation
Authors: Mukaiyama Minagi , Usui Takeo , Nagumo Yoko
Published: May 2020

Activation of the transient receptor potential A1 channel (TRPA1) by electrophilic agonists was reported to induce the opening of tight junctions (TJs). Because compounds that increase TJ permeability can be paracellular permeability enhancers, we investigated the effect of non-electrophilic TRPA1 activators, including food ingredients (menthol and carvacrol) and medication (clotrimazole), on epithelial permeability. We show that all three compounds induced increase of the permeability of fluorescein isothiocyanate-conjugated dextran (4 kDa) and decrease of transepithelial electrical resistance, accompanied by Ca2+ influx and cofilin activation in epithelial MDCK II monolayers. These phenotypes were attenuated by pretreatment of a TRPA1 antagonist, suggesting TRPA1-mediated opening of TJs. These results suggest that non-electrophilic TRPA1 activators with established safety can be utilized to regulate epithelial barriers.
Unusual presentation of rare complication following endoscopic gastroplasty: case report
Authors: Alqahtani Awadh , Aljohani Emad
Published: May 2020

A 35-years-old female post-endoscopic gastroplasty presented to the emergency department complaining of epigastric abdominal pain. The abdominal examination showed epigastric and tenderness. On abdomen computerized axial tomography (CAT) scan she had small bowel obstruction with twisting of mesenteric vessel. The patient taken to the operating room for diagnostic laparoscopy and proceed, laparoscopic examination showed proximal dilatation of small intestine with collapse of distal part of jejunum, the obstruction identified, as fibrous band originating from the stomach to the proximal part of jejunum, this band caused by suture penetrating the stomach wall, which is going with the previous history of the endoscopic gastroplasty, reduction of the internal hernia done by releasing of the fibrous band, the herniated segment was healthy. Internal hernia can present with variety of complications. To the best of our knowledge from the literature review, this is the first case to be reported as internal abdominal hernia secondary to endoscopic gastroplasty.
Spontaneous intra-adrenal massive hematoma: possible extreme evolution of a non-secreting untreated adrenal adenoma
Authors: Mancini Mariangela , Leone Nicolò , Iafrate Massimo , Fassina Ambrogio , Zattoni Filiberto ,   in collaboration with European Reference Network for Rare Urogenital Diseases and Complex Conditions (ERN eUROGEN)
Published: May 2020

The spontaneous adrenal hematoma is a rare event. An 83-year-old male patient presented a 26-cm asymptomatic retroperitoneal mass of doubtful renal–adrenal origin. He had been evaluated 10 years before for an adrenal incidentaloma of 2.3 cm and had refused surgery when it had reached 7 cm. Later, the mass enlarged to 26 cm and was surgically removed through an open anterior approach. The histopathology showed a solid 4 kg mass of fibrinoid–hemorrhagic material, partially necrotic, mixed with adrenal tissue, with a well-vascularized capsule. No relapse is present at 6-month follow-up. This is the largest case described of spontaneous intra-adrenal hematoma in a case with previous non-secreting adrenal adenoma. The hematoma (a 4 kg mass) developed 10 years after the first diagnosis and exposed the patient to potential damage of the surrounding organs and to high-risk abdominal surgery. Long-term follow-up of non-secreting adrenal adenomas should be recommended.
Streamlining Definitive Care for Occult Scaphoid Fractures: A Retrospective Review of the Workup of Scaphoid Nonunions and Applying Lessons Learned
Authors: Liu Peterson Shian , Scott Donoughe John , O’Neal Derrick , Mombell Kyle , GomezLeonardelli Dominic
Published: May 2020

Introduction

The process for working up scaphoid fractures from frontline providers to the specialty care clinic is variable. Initial imaging can often be negative and the management algorithm is not clearly defined. Delays in diagnosis are a contributing factor to scaphoid nonunion. Fractures may not be identified by frontline providers on initial presentation because of radiographically occult injuries. If not treated promptly, scaphoid fractures may be complicated by nonunion, avascular necrosis, and osteoarthritis.

Materials and Methods

Retrospective review of scaphoid nonunions from 2017 to 2018 in a single tertiary care institution after internal review board approval was obtained (NMCSD.QI.2019.0003). Cases were identified using an ICD 10 search for “scaphoid (navicular) fracture non-union” and subtypes. Charts were examined for time between injury and presentation, injury and diagnosis, initial radiologic workup, and limited duty (LIMDU). Nonparametric statistical analysis for linear and categorical data was conducted using SPSS. A subgroup of patients who had a delay in diagnosis of greater than 30 days upon entering the medical system was further analyzed and identified as the “delayed diagnosis” cohort.

Results

In total, 30 patients with scaphoid nonunion were identified. Overall, 35% of patients had negative initial X-rays and averaged 42.1 days until diagnosis. In total, 100% of patients required at least one LIMDU period, averaging 1.4 periods, for a total of 6,404 days and 16% went on to a physical evaluation board (PEB). In 9 (30%) of these patients, injury was initially not identified upon entering the medical system resulting in average of 139.7 days until diagnosis; this became known as the delayed diagnosis subgroup. Further analysis of the delayed diagnosis subgroup demonstrated significantly more initial negative X-rays (P < .005) at a rate of 77% (7/9). A delay in diagnosis was significantly associated with PEB (R = 0.4, P = .031) with 33% of these patients going on to a PEB.

Conclusions

Delayed diagnosis of a scaphoid fracture is a contributing factor for excessive light duty, high rates of LIMDU utilization, and ultimately medical separation of service members. Overall, in all patients who had scaphoid nonunions, the average time to diagnosis was 42.1 days with 35% of patients presenting with negative initial imaging. A delayed diagnosis subgroup was identified and notable for a higher rate of initial negative X-rays, an average of 139.7 days until diagnosis, and a 33% PEB rate. In total, 77% of patients with a delay in diagnosis of more than 30 days had an initial negative X-ray. An evidence-based algorithm for diagnosing occult scaphoid fractures may prevent delays in diagnosis, thus increasing the readiness of active duty service members.
Trapped orbits and solar-neighbourhood kinematics
Authors: Binney James
Published: May 2020

Torus mapping yields constants of motion for stars trapped at a resonance. Each such constant of motion yields a system of contours in velocity space at the Sun and neighbouring points. If Jeans’ theorem applied to resonantly trapped orbits, the density of stars in velocity space would be equal at all intersections of any two contours. A quantitative measure of the violation of this principle is defined and used to assess various pattern speeds for a model of the bar recently fitted to observations of interstellar gas. Trapping at corotation of a bar with pattern speed near $36\, \mathrm{Gyr}^{-1}$ is favoured and trapping at the outer Lindblad resonance is disfavoured. As one moves around the Sun the structure of velocity space varies quite rapidly, both as regards the observed star density and the zones of trapped orbits. The data seem consistent with trapping at corotation.
Using realistic host galaxy metallicities to improve the GRB X-ray equivalent total hydrogen column density and constrain the intergalactic medium density
Authors: Dalton Tony , Morris Simon L
Published: May 2020

It is known that the GRB equivalent hydrogen column density (NHX) changes with redshift and that, typically, NHX is greater than the GRB host neutral hydrogen column density. We have compiled a large sample of data for GRB NHX and metallicity [X/H]. The main aims of this paper are to generate improved NHX for our sample by using actual metallicities, dust corrected where available for detections, and for the remaining GRB, a more realistic average intrinsic metallicity using a standard adjustment from solar. Then, by approximating the GRB host intrinsic hydrogen column density using the measured neutral column (NHI, IC) adjusted for the ionization fraction, we isolate a more accurate estimate for the intergalactic medium (IGM) contribution. The GRB sample mean metallicity is = −1.17 ± 0.09 rms (or 0.07 ± 0.05 Z/Zsol) from a sample of 36 GRB with a redshift 1.76 ≤ z ≤ 5.91, substantially lower than the assumption of solar metallicity used as standard for many fitted NHX. Lower GRB host mean metallicity results in increased estimated NHX with the correction scaling with redshift as Δlog (NHX cm−2) = (0.59 ± 0.04)log(1 + z) + 0.18 ± 0.02. Of the 128 GRB with data for both NHX and NHI, IC in our sample, only six have NHI, IC > NHX when revised for realistic metallicity, compared to 32 when solar metallicity is assumed. The lower envelope of the revised NHX – NHI, IC, plotted against redshift can be fit by log(NHX – NHI, IC cm−2) = 20.3 + 2.4 log(1 + z). This is taken to be an estimate for the maximum IGM hydrogen column density as a function of redshift. Using this approach, we estimate an upper limit to the hydrogen density at redshift zero (n0) to be consistent with n0 = 0.17 × 10−7cm−3.
Long-term evolution of a magnetic massive merger product
Authors: Schneider F R N , Ohlmann S T , Podsiadlowski Ph , Röpke F K , Balbus S A , Pakmor R
Published: May 2020

About 10 per cent of stars more massive than ${\approx}1.5\, {\mathrm{M}}_{\odot }$ have strong, large-scale surface magnetic fields and are being discussed as progenitors of highly magnetic white dwarfs and magnetars. The origin of these fields remains uncertain. Recent three-dimensional (3D) magnetohydrodynamical simulations have shown that strong magnetic fields can be generated in the merger of two massive stars. Here, we follow the long-term evolution of such a 3D merger product in a 1D stellar evolution code. During a thermal relaxation phase after the coalescence, the merger product reaches critical surface rotation, sheds mass and then spins down primarily because of internal mass readjustments. The spin of the merger product after thermal relaxation is mainly set by the co-evolution of the star–torus structure left after coalescence. This evolution is still uncertain, so we also consider magnetic braking and other angular momentum-gain and -loss mechanisms that may influence the final spin of the merged star. Because of core compression and mixing of carbon and nitrogen in the merger, enhanced nuclear burning drives a transient convective core that greatly contributes to the rejuvenation of the star. Once the merger product relaxed back to the main sequence, it continues its evolution similar to that of a genuine single star of comparable mass. It is a slow rotator that matches the magnetic blue straggler τ Sco. Our results show that merging is a promising mechanism to explain some magnetic massive stars and it may also be key to understand the origin of the strong magnetic fields of highly magnetic white dwarfs and magnetars.
The SAMI Galaxy Survey: decomposed stellar kinematics of galaxy bulges and disks
Authors: Oh Sree , Colless Matthew , Barsanti Stefania , Casura Sarah , Cortese Luca , van de Sande Jesse , Owers Matt S , Scott Nicholas , D’Eugenio Francesco , Bland-Hawthorn Joss , Brough Sarah , Bryant Julia J , Croom Scott M , Foster Caroline , Groves Brent , Lawrence Jon S , Richards Samuel N , Sweet Sarah M
Published: May 2020

We investigate the stellar kinematics of the bulge and disk components in 826 galaxies with a wide range of morphology from the Sydney-AAO Multi-object Integral-field spectroscopy Galaxy Survey. The spatially resolved rotation velocity (V) and velocity dispersion (σ) of bulge and disk components have been simultaneously estimated using the penalized pixel fitting (ppxf) method with photometrically defined weights for the two components. We introduce a new subroutine of ppxf for dealing with degeneracy in the solutions. We show that the V and σ distributions in each galaxy can be reconstructed using the kinematics and weights of the bulge and disk components. The combination of two distinct components provides a consistent description of the major kinematic features of galaxies over a wide range of morphological types. We present Tully–Fisher and Faber–Jackson relations showing that the galaxy stellar mass scales with both V and σ for both components of all galaxy types. We find a tight Faber–Jackson relation even for the disk component. We show that the bulge and disk components are kinematically distinct: (1) the two components show scaling relations with similar slopes, but different intercepts; (2) the spin parameter λR indicates bulges are pressure-dominated systems and disks are supported by rotation; and (3) the bulge and disk components have, respectively, low and high values in intrinsic ellipticity. Our findings suggest that the relative contributions of the two components explain, at least to first order, the complex kinematic behaviour of galaxies.
On the origin of the bimodal rotational velocity distribution in stellar clusters: rotation on the pre-main sequence
Authors: Bastian Nate , Kamann Sebastian , Amard Louis , Charbonnel Corinne , Haemmerlé Lionel , Matt Sean P
Published: May 2020

We address the origin of the observed bimodal rotational distribution of stars in massive young and intermediate age stellar clusters. This bimodality is seen as split main sequences at young ages and also has been recently directly observed in the Vsini distribution of stars within massive young and intermediate age clusters. Previous models have invoked binary interactions as the origin of this bimodality, although these models are unable to reproduce all of the observational constraints on the problem. Here, we suggest that such a bimodal rotational distribution is set-up early within a cluster’s life, i.e. within the first few Myr. Observations show that the period distribution of low-mass ($\lesssim\! 2 \, \mathrm{M}_\odot$) pre-main-sequence (PMS) stars is bimodal in many young open clusters, and we present a series of models to show that if such a bimodality exists for stars on the PMS that it is expected to manifest as a bimodal rotational velocity (at fixed mass/luminosity) on the main sequence for stars with masses in excess of ∼1.5 M⊙. Such a bimodal period distribution of PMS stars may be caused by whether stars have lost (rapid rotators) or been able to retain (slow rotators) their circumstellar discs throughout their PMS lifetimes. We conclude with a series of predictions for observables based on our model.
The optical polarization of the blazar PKS 2155–304 during an optical flare in 2010
Authors: Peceur N W , Taylor A R , Kraan-Korteweg R C
Published: May 2020

An analysis is presented of the optical polarimetric and multicolour photometric (BVRJ) behaviour of the blazar PKS 2155–304 during an outburst in 2010. This flare develops over roughly 117 d, with a flux doubling time τ ∼ 11 d, which increases from blue to red wavelengths. The polarization angle is initially aligned with the jet axis but rotates by roughly 90° as the flare grows. Two distinct states are evident at low and high fluxes. Below 18 mJy, the polarization angle takes on a wide range of values, without any clear relation to the flux. In contrast, there is a positive correlation between the polarization angle and flux above 18 mJy. The polarization degree does not display a clear correlation with the flux. We find that the photopolarimetric behaviour for the high flux state can be attributed to a variable component with a steady power-law spectral energy distribution and high optical polarization degree (13.3 per cent). These properties are interpreted within the shock-in-jet model, which shows that the observed variability can be explained by a shock that is seen nearly edge-on. Some parameters derived for the relativistic jet within the shock-in-jet model are: B = 0.06 G for the magnetic field, δ = 22.3 for the Doppler factor, and Φ = 2.6° for the viewing angle.
Non-ideal magnetohydrodynamics versus turbulence II: Which is the dominant process in stellar core formation?
Authors: Wurster James , Lewis Benjamin T
Published: May 2020

Non-ideal magnetohydrodynamics (MHD) is the dominant process. We investigate the effect of magnetic fields (ideal and non-ideal) and turbulence (sub- and transsonic) on the formation of protostars by following the gravitational collapse of 1 M⊙ gas clouds through the first hydrostatic core to stellar densities. The clouds are imposed with both rotational and turbulent velocities, and are threaded with a magnetic field that is parallel/antiparallel or perpendicular to the rotation axis; we investigate two rotation rates and four Mach numbers. The initial radius and mass of the stellar core are only weakly dependent on the initial parameters. In the models that include ideal MHD, the magnetic field strength implanted in the protostar at birth is much higher than observed, independent of the initial level of turbulence; only non-ideal MHD can reduce this strength to near or below the observed levels. This suggests that not only is ideal MHD an incomplete picture of star formation, but that the magnetic fields in low mass stars are implanted later in life by a dynamo process. Non-ideal MHD suppresses magnetically launched stellar core outflows, but turbulence permits thermally launched outflows to form a few years after stellar core formation.
Large-scale changes of the cloud coverage in the ϵ Indi Ba and Bb system
Authors: Hitchcock J A , Helling Ch , Scholz A , Hodosan G , Dominik M , Hundertmark M , Jørgensen U G , Longa-Peña P , Sajadian S , Skottfelt J , Snodgrass C , Bozza V , Burgdorf M J , Campbell-White J , Figuera Jaimes Roberto , Fujii Y I , Haikala L K , Henning T , Hinse T C , Lowry S , Mancini L , Rahvar S , Rabus M , Southworth J , von Essen C ,   (The MiNDSTEp Collaboration)
Published: May 2020

We present the results of 14 nights of I-band photometric monitoring of the nearby brown dwarf binary, ϵ Indi Ba and Bb. Observations were acquired over 2 months, with a total of close to 42 h of coverage at a typically high cadence of 1.4 min. At a separation of just 0.7 arcsec, we do not resolve the individual components, and so effectively treat the binary as if it were a single object. However, ϵ Indi Ba (spectral type T1) is the brightest known T-type brown dwarf, and is expected to dominate the photometric signal. We typically find no strong variability associated with the target during each individual night of observing, but see significant changes in mean brightness – by as much as 0.10 mag – over the 2 months of the campaign. This strong variation is apparent on a time-scale of at least 2 d. We detect no clear periodic signature, which suggests that we may be observing the T1 brown dwarf almost pole-on, and the days-long variability in mean brightness is caused by changes in the large-scale structure of the cloud coverage. Dynamic clouds will very likely produce lightning, and complementary high-cadence V-band and H α images were acquired to search for the emission signatures associated with stochastic ‘strikes’. We report no positive detections for the target in either of these passbands.
Carbon stars as standard candles: I. The luminosity function of carbon stars in the Magellanic Clouds
Authors: Ripoche Paul , Heyl Jeremy , Parada Javiera , Richer Harvey
Published: May 2020

Our goal in this paper is to derive a carbon-star luminosity function that will eventually be used to determine distances to galaxies at 50–60 Mpc and hence yield a value of the Hubble constant. Cool N-type carbon stars exhibit redder near-infrared colours than oxygen-rich stars. Using Two Micron All Sky Survey near-infrared photometry and the Gaia Data Release 2, we identify carbon stars in the Magellanic Clouds (MC) and the Milky Way (MW). Carbon stars in the MC appear as a distinct horizontal feature in the near-infrared ((J − Ks)0, MJ) colour–magnitude diagram. We build a colour selection (1.4 < (J − Ks)0 < 2) and derive the luminosity function of the colour-selected carbon stars. We find the median absolute magnitude and the dispersion, in the J band, for the Large and the Small Magellanic Clouds (LMC/SMC) to be, respectively, ($\bar{M_J} = -6.284~\pm ~0.004$ and σ = 0.352  ±  0.005) and ($\bar{M_J} = -6.160~\pm ~0.015$ and σ = 0.365  ±  0.014). The difference between the MC may be explained by the lower metallicity of the SMC, but in any case it provides limits on the type of galaxy whose distance can be determined with this technique. To account for metallicity effects, we developed a composite magnitude, named C, for which the error-weighted mean C magnitude of the MC are equal. Thanks to the next generation of telescopes (JWST, ELT, and TMT), carbon stars could be detected in MC-type galaxies at distances out to 50–60 Mpc. The final goal is to eventually try and improve the measurement of the Hubble constant while exploring the current tensions related to its value.
Stability of Jovian Trojans and their collisional families
Authors: Holt Timothy R , Nesvorný David , Horner Jonathan , King Rachel , Marschall Raphael , Kamrowski Melissa , Carter Brad , Brookshaw Leigh , Tylor Christopher
Published: May 2020

The Jovian Trojans are two swarms of objects located around the L4 and L5 Lagrange points. The population is thought to have been captured by Jupiter during the Solar system’s youth. Within the swarms, six collisional families have been identified in previous work, with four in the L4 swarm, and two in the L5. Our aim is to investigate the stability of the two Trojan swarms, with a particular focus on these collisional families. We find that the members of Trojan swarms escape the population at a linear rate, with the primordial L4 (23.35 per cent escape) and L5 (24.89 per cent escape) population sizes likely 1.31 and 1.35 times larger than today. Given that the escape rates were approximately equal between the two Trojan swarms, our results do not explain the observed asymmetry between the two groups, suggesting that the numerical differences are primordial in nature, supporting previous studies. Upon leaving the Trojan population, the escaped objects move on to orbits that resemble those of the Centaur and short-period comet populations. Within the Trojan collisional families, the 1996 RJ and 2001 UV209 families are found to be dynamically stable over the lifetime of the Solar system, whilst the Hektor, Arkesilos and Ennomos families exhibit various degrees of instability. The larger Eurybates family shows 18.81 per cent of simulated members escaping the Trojan population. Unlike the L4 swarm, the escape rate from the Eurybates family is found to increase as a function of time, allowing an age estimation of approximately 1.045 ± 0.364 × 109 yr.
Chaotically magnetized atmosphere with dust
Authors: Silant’ev N A , Alekseeva G A , Ananjevskaja Yu K
Published: May 2020

We consider the influence of absorbing dust particles on the intensity and polarization of radiation in chaotically magnetized atmospheres. The Milne problem is considered. It is known that the existence of absorbing dust particles leads to more elongated intensity distribution along the normal to the atmosphere and increasing of polarization degree near the direction perpendicular to the normal. The chaotic Faraday rotations practically do not change the intensity distribution, but they decrease the polarization degree. How looks the picture when the atmosphere is chaotically magnetized and contains the absorbing dust particles? Usually one assumes that such atmospheres exist in active galactic nuclei in Seyfert galaxies, both in accretion discs and gas–dusty toruses. In particular, we establish when both mechanisms cancel one another and the resulting polarization is near to ordinary atmosphere without the magnetic field fluctuations and absorbing particles. Of course, the angular distribution mostly corresponds to the level of existing dust particles, because it is practically independent of polarization.
From birth associations to field stars: mapping the small-scale orbit distribution in the Galactic disc
Authors: Coronado Johanna , Rix Hans-Walter , Trick Wilma H , El-Badry Kareem , Rybizki Jan , Xiang Maosheng
Published: May 2020

Stars born at the same time in the same place should have formed from gas of the same element composition. But most stars subsequently disperse from their birth siblings, in orbit and orbital phase, becoming ‘field stars’. Here, we explore and provide direct observational evidence for this process in the Milky Way disc, by quantifying the probability that orbit-similarity among stars implies indistinguishable metallicity. We define the orbit similarity among stars through their distance in action-angle space, Δ(J, θ), and their abundance similarity simply by Δ[Fe/H]. Analysing a sample of main-sequence stars from Gaia DR2 and LAMOST, we find an excess of pairs with the same metallicity (Δ[Fe/H] < 0.1) that extends to remarkably large separations in Δ(J, θ) that correspond to nearly 1 kpc distances. We assess the significance of this effect through a mock sample, drawn from a smooth and phase-mixed orbit distribution. Through grouping such star pairs into associations with a friend-of-friends algorithm linked by Δ(J,θ), we find 100s of mono-abundance groups with ≥3 (to ≳20) members; these groups – some clusters, some spread across the sky – are over an order-of-magnitude more abundant than expected for a smooth phase-space distribution, suggesting that we are witnessing the ‘dissolution’ of stellar birth associations into the field.
Full stomachs at empty tides: tidal cycle affects feeding activity and diet of the sandy beach gastropod Olivella minuta
Authors: Checon Helio H , Silva Mariana O , Corte Guilherme N , Yokoyama Leonardo Q , Teodósio M Alexandra , Turra Alexander
Published: May 2020

Olivella minuta is an abundant neogastropod on sandy beaches from Texas (USA) to southern Brazil. This study aimed to characterize and compare the feeding activity and diet of a Brazilian population of O. minuta in different tidal zones (intertidal and subtidal), and different tidal levels (high and low tides), with three combinations of tidal zone and level being studied (intertidal during low tide, intertidal during high tide and subtidal). The results showed that diet composition was generally similar among tidal conditions, with O. minuta being a generalist, feeding on 45 different food items. Feeding activity, however, was higher in the intertidal during low tide, whereas the richness and diversity of food items were higher in the intertidal during high tide. The higher feeding activity of O. minuta during low tide may be linked to a lower risk of predation; at low tide organisms may be able to feed for a longer time, and this may be particularly true on beaches with fine sand, where water retention is higher than that on beaches with coarse sand. The higher diversity of food items consumed in the intertidal during high tide is likely related to the increased prevalence of planktonic food during high tide. Our results indicate that tidal zone and level may strongly influence the feeding activity of coastal soft-bottom species and that species may show higher feeding activity during low tide. Given the current loss of intertidal habitats due to anthropogenic activity and climate-change associated factors, our study has important implications, highlighting the importance of intertidal areas for the ecology and conservation of sandy beach species.
Distortions in Production Networks*
Authors: Bigio Saki , La’O Jennifer
Published: May 2020

How does an economy’s production structure determine its macroeconomic response to sectoral distortions? We study a static, multisector framework in which production is organized in an input-output network and production decisions are distorted. Sectoral distortions manifest at the aggregate level via two channels: total factor productivity (TFP) and the labor wedge. We show that near efficiency, distortions have zero first-order effects on TFP and nonzero first-order effects on the labor wedge, and that a sufficient statistic for the latter are the Domar weights. We thereby provide a Hulten-like theorem for the aggregate effects of sectoral distortions. A quantitative application of the model to the 2008–09 financial crisis suggests that the U.S. input-output structure amplified financial distortions by roughly a factor of two during the crisis.
Functional Pathway Identification With CRISPR/Cas9 Genome-wide Gene Disruption in Human Dopaminergic Neuronal Cells Following Chronic Treatment With Dieldrin
Authors: Russo Max , Sobh Amin , Zhang Ping , Loguinov Alex , Tagmount Abderrahmane , Vulpe Chris D , Liu Bin
Published: May 2020

Organochlorine pesticides, once widely used, are extremely persistent and bio-accumulative in the environment. Epidemiological studies have implicated that environmental exposure to organochlorine pesticides including dieldrin is a risk factor for the development of Parkinson’s disease. However, the pertinent mechanisms of action remain poorly understood. In this study, we carried out a genome-wide (Brunello library, 19 114 genes, 76 411 sgRNAs) CRISPR/Cas9 screen in human dopaminergic SH-SY5Y neuronal cells exposed to a chronic treatment (30 days) with dieldrin to identify cellular pathways that are functionally related to the chronic cellular toxicity. Our results indicate that dieldrin toxicity was enhanced by gene disruption of specific components of the ubiquitin proteasome system as well as, surprisingly, the protein degradation pathways previously implicated in inherited forms of Parkinson’s disease, centered on Parkin. In addition, disruption of regulatory components of the mTOR pathway which integrates cellular responses to both intra- and extracellular signals and is a central regulator for cell metabolism, growth, proliferation, and survival, led to increased sensitivity to dieldrin-induced cellular toxicity. This study is one of the first to apply a genome-wide CRISPR/Cas9-based functional gene disruption screening approach in an adherent neuronal cell line to globally decipher cellular mechanisms that contribute to environmental toxicant-induced neurotoxicity and provides novel insight into the dopaminergic neurotoxicity associated with chronic exposure to dieldrin.
Structure parameter optimization and bearing limit analysis of the expansion unit of three-roller tube expander
Authors: Bi Gang , Qu Zhan , Wang Zhenquan , Dou Liangbin , Li Mengmeng
Published: May 2020

The critical technical issues for the structure design of three-roller tube expander were first studied and analysed in this paper. Then, the major design parameters of the expansion unit structure and the bearing limit of 12¼″ three-roller tube expander were optimized and investigated by finite-element numerical simulation method. Results from study show that the required expansion force increases when the taper angle of the roller outer surface gets larger, taking the axial expansion force as the quantitative indicators. It is suggested that the roller tape angle of the expansion unit should be in the range of 9–12° considering the proper length of the roller and the non-self-locking tube expansion process. The required expansion force of the bellows first decreases and then increases when the gauge length of the expansion unit becomes longer. The optimal value of the gauge length is 50 mm considering the proper length of the roller. And according to the numerical simulation results, the designed three-roller tube expander meets the strength requirements. The results of this study are of great significance to the expend bellows drilling technology.
After the bite: bacterial transmission from grey seals (
Halichoerus grypus
) to harbour porpoises (
Phocoena phocoena
)
Authors: Gilbert Maarten J. , IJsseldijk Lonneke L. , Rubio-García Ana , Gröne Andrea , Duim Birgitta , Rossen John , Zomer Aldert L. , Wagenaar Jaap A.
Published: May 2020

Recent population growth of the harbour porpoise (
Phocoena phocoena
), grey seal (
Halichoerus grypus
) and common seal (
Phoca vitulina
) in the North Sea has increased potential interaction between these species. Grey seals are known to attack harbour porpoises. Some harbour porpoises survive initially, but succumb eventually, often showing severely infected skin lesions. Bacteria transferred from the grey seal oral cavity may be involved in these infections and eventual death of the animal. In humans, seal bites are known to cause severe infections. In this study, a 16S rRNA-based microbiome sequencing approach is used to identify the oral bacterial diversity in harbour porpoises, grey seals and common seals; detect the potential transfer of bacteria from grey seals to harbour porpoises by biting and provide insights in the bacteria with zoonotic potential present in the seal oral cavity. β-diversity analysis showed that 12.9% (4/31) of the harbour porpoise skin lesion microbiomes resembled seal oral microbiomes, while most of the other skin lesion microbiomes also showed seal-associated bacterial species, including potential pathogens. In conclusion, this study shows that bacterial transmission from grey seals to harbour porpoises by biting is highly likely and that seal oral cavities harbour many bacterial pathogens with zoonotic potential.
Study on mechanical characteristics of conductors with three-dimensional finite-element models
Authors: Liu Jiaqiong , Yan Bo , Huang Guizao , Mou Zheyue , Lv Xin , Zhang Haibing
Published: May 2020

Refined three-dimensional (3D) finite-element (FE) models of typical aluminium conductor steel reinforced (ACSR) and formed aluminium conductor steel reinforced (FACSR) with structural details to simulate their static and dynamic characteristics are proposed. Taking into account the elastoplastic behaviour of the aluminium wires, the tensile mechanical properties and coupling between tension and torsion of the two types of conductors under tensile loading are numerically investigated. Furthermore, dynamic responses of two transmission lines, in which the refined 3D segment models and equivalent beam models of the two types of conductors are used, after ice-shedding are numerically simulated and the dynamic characteristics of the conductors are analysed. Finally, based on the numerical simulation results, the fatigue lives of the aluminium wires are estimated and the wear between the wires is discussed. It is revealed that taking into account the structural details of the conductors in the strength design of transmission lines is necessary, and the mechanical characteristics of FACSR are better than those of the ACSR in both static and dynamic situations.