bluuebunny/crossref_metadata_2025 huggingface dataset:
Multicentre validation of a EUCAST method for the antifungal susceptibility testing of microconidia-forming dermatophytes
Authors: Arendrup Maiken Cavling , Jørgensen Karin Meinike , Guinea Jesus , Lagrou Katrien , Chryssanthou Erja , Hayette Marie-Pierre , Barchiesi Francesco , Lass-Flörl Cornelia , Hamal Petr , Dannaoui Eric , Chowdhary Anuradha , Meletiadis Joseph
Published: March 2020

Objectives

Terbinafine resistance is increasingly reported in Trichophyton, rendering susceptibility testing particularly important in non-responding cases. We performed a multicentre evaluation of six EUCAST-based methods.

Methods

Ten laboratories susceptibility tested terbinafine, itraconazole, voriconazole and amorolfine against a blinded panel of 38 terbinafine WT and target gene mutant isolates. E.Def 9.3.1 modifications included: medium with/without addition of chloramphenicol and cycloheximide (CC), incubation at 25°C to 28°C for 5–7 days and three MIC endpoints [visually and spectrophotometrically (90%/50% inhibition)], generating 7829 MICs. Quality control (QC) strains were Aspergillus flavus ATCC 204304 and CNM-CM1813. Eyeball, ECOFFinder (where ECOFF stands for epidemiological cut-off) and derivatization WT upper limits (WT-ULs), very major errors (VMEs; mutants with MICs ≤WT-ULs) and major errors (MEs; WT isolates with MICs >WT-ULs) were determined.

Results

MICs fell within the QC ranges for ATCC 204304/CNM-CM1813 for 100%/96% (voriconazole) and 84%/84% (itraconazole), respectively. Terbinafine MICs fell within 0.25–1 mg/L for 96%/92%, suggesting high reproducibility. Across the six methods, the number of terbinafine MEs varied from 2 to 4 (2.6%–5.2%) for Trichophyton rubrum and from 0 to 2 (0%–2.0%) for Trichophyton interdigitale. Modes for WT and mutant populations were at least seven 2-fold dilutions apart in all cases. Excluding one I121M/V237I T. rubrum mutant and two mixed WT/mutant T. interdigitale specimens, the numbers of VMEs were as follows: T. rubrum: CC visual, 1/67 (1.5%); CC spectrophotometric 90% inhibition, 3/59 (5.1%); and CC spectrophotometric 50% inhibition, 1/67 (1.5%); and T. interdigitale: none. Voriconazole and amorolfine MICs were quite uniform, but trailing growth complicated determination of itraconazole visual and spectrophotometric 90% inhibition MIC.

Conclusions

Although none of the laboratories was experienced in dermatophyte testing, error rates were low. We recommend the CC spectrophotometric 50% inhibition method and provide QC ranges and WT-ULs for WT/non-WT classification.
Effectiveness of dolutegravir-based antiretroviral treatment for HIV-2 infection: retrospective observational study from Western India
Authors: Pujari Sanjay , Patel Atul , Gaikwad Sunil , Patel Ketan , Dabhade Digamber , Chitalikar Abhishek , Joshi Kedar , Bele Vivek
Published: March 2020

Background

Data on the use of dolutegravir for treatment of HIV-2 infection are limited.

Objectives

To assess the effectiveness of dolutegravir in people living with HIV-2 (PLHIV-2).

Methods

A retrospective chart review was performed in two clinics in Western India. PLHIV-2 initiated on dolutegravir-based regimens were included. Response to treatment in both treatment-naive (TN) and treatment-experienced (TE; substitution and not in the context of failure) was assessed by CD4 counts and HIV-2 viral load (VL) in a proportion of individuals. The primary objective was to assess immunological effectiveness (absence of a drop in absolute CD4 counts by more than 30% of baseline). Change in absolute CD4 counts was assessed by fitting a mixed-effects model.

Results

Sixty-two PLHIV-2 treated with dolutegravir were included. The immunological effectiveness rates (95% CI) were 91.9% (82.4%–96.5%), 92% (81.1%–96.8%) and 91.6% (64.6%–98.5%) amongst all, TE and TN individuals, respectively. Median change in absolute CD4 counts at 6, 12 and 18 months were +29 cells/mm3, +101 cells/mm3 and +72 cells/mm3, respectively. The virological effectiveness rates (HIV-2 VL <100 copies/mL) (95% CI) for all, TE and TN individuals were 88.8% (74.6%–95%), 89.6% (73.6%–96.4%) and 85.7% (48.6%–97.4%), respectively. Three clinical events were documented: spinal tuberculosis, relapsed non-Hodgkin’s lymphoma and herpes simplex virus retinitis. One individual reported self-limiting somnolence.

Conclusions

Dolutegravir was well tolerated and associated with immunological, virological and clinical effectiveness in both TN and TE PLHIV-2 in a large cohort from Western India. Dolutegravir-based ART is an excellent option for treatment of individuals with HIV-2 infection.
Antimicrobial susceptibility of Clostridioides difficile isolated from diarrhoeal stool specimens of Canadian patients: summary of results from the Canadian Clostridioides difficile (CAN-DIFF) surveillance study from 2013 to 2017
Authors: Karlowsky James A , Adam Heather J , Baxter Melanie R , Dutka Christopher W , Nichol Kim A , Laing Nancy M , Golding George R , Zhanel George G
Published: March 2020

Objectives

To summarize data generated by the Canadian Clostridioides difficile (CAN-DIFF) surveillance study from 2013 to 2017.

Methods

Isolates of C. difficile (n = 2158) were cultured from toxin-positive diarrhoeal stool specimens submitted by eight hospital laboratories to a coordinating laboratory. Antimicrobial susceptibility testing was performed according to the CLSI agar dilution method (M11, 2018). Isolate ribotypes were determined using an international, standardized, high-resolution capillary gel-based electrophoresis protocol.

Results

Of the 2158 isolates of C. difficile, 2133 (98.8%) had vancomycin MICs ≤2 mg/L [i.e. were vancomycin susceptible (EUCAST breakpoint tables, v 9.0, 2019) or WT (CLSI M100, 29th edition, 2019)]. Fidaxomicin MICs were lower than those of all other agents tested (MIC90, 0.5 mg/L); however, one isolate with a fidaxomicin MIC of >8 mg/L was identified. Metronidazole MICs ranged from 0.12 to 4 mg/L; all isolates were metronidazole susceptible by the CLSI breakpoint (≤8 mg/L) compared with 96.8% susceptible by the EUCAST breakpoint (≤2 mg/L). In total, 182 different ribotypes were identified from 2013 to 2017. The most common ribotypes identified were 027 (19.3% of isolates) and 106 (8.2%). Ribotype 027 isolates were frequently moxifloxacin resistant (87.3% of isolates) and MDR (48.6%), associated with vancomycin (10/25, 40.0%) and metronidazole (58/69, 84.1%) resistance and from patients aged ≥80 years. The prevalence of ribotype 027 decreased significantly (P < 0.0001) from 2013 (27.5%) to 2017 (9.0%) and was replaced by increases in ribotype 106 (P = 0.0003) and multiple less common ribotypes.

Conclusions

Periodic surveillance is required to monitor clinical isolates of C. difficile for changes to in vitro susceptibility testing profiles and ribotype evolution.
Quantitative Nuclear Magnetic Resonance Spectroscopic Analysis of Two Commonly Used Gastrointestinal Tract Drugs
Authors: Elbagary Ramzia I , Fouad Marwa A , Ezzeldin Menna I
Published: March 2020

Background

Two fast and precise quantitative nuclear magnetic resonance spectroscopic methods (qNMR) were established and evaluated for the determination of ondansetron (OND) and omeprazole (OMP) in bulk drugs and their pharmaceutical dosage forms. NMR spectra were established using dimethylsulfoxide (DMSO-d6) as a solvent and phloroglucinol as the internal standard. Proton NMR signals at 3.743, 3.811, and 5.670 ppm were used for quantitative monitoring purposes corresponding to OND, OMP, and phloroglucinol, respectively. In this study, the methods linearity, accuracy, limit of quantification, limit of detection, stability, and precision were validated as per International Conference on Harmonization (ICH) guidelines. Linearity ranges were 0.3–10 mg for OND and 1–10 mg for OMP. The student t-test and F-test were used for statistical evaluation. Herein, the proposed methods are useful and can be a successful practical appliance for OND and OMP determination in drug substances and their dosage forms.
Safety, Pharmacodynamics, and Efficacy of High- Versus Low-Dose Ascorbic Acid in Severely Burned Adults
Authors: Nagel Sarah Sophie , Radu Christian Andreas , Kremer Thomas , Meess David , Horter Johannes , Ziegler Benjamin , Hirche Christoph , Schmidt Volker Juergen , Kneser Ulrich , Hundeshagen Gabriel
Published: March 2020

In sepsis and burns, ascorbic acid (AA) is hypothesized advantageous during volume resuscitation. There is uncertainty regarding its safety and dosing. This study evaluated high dose AA (HDAA: 66 mg/kg/h for 24 hours) versus low dose AA (LDAA: 3.5 g/days) administration during the first 24 hours in severely burned adults. We conducted a retrospective study comparing fluid administration before and after switching from low dose to HDAA in severely burned adults. A total of 38 adults with burns >20% TBSA, who received either HDAA or LDAA were included in this retrospective study. AA serum concentrations were quantified at 0, 24, and 72 hours postburn. HDAA impact on hemodynamics, acid–base homeostasis, acute kidney injury, vasopressor use, resuscitation fluid requirement, urinary output, and the incidence of adverse effects was evaluated; secondary clinical outcomes were analyzed. AA plasma levels were 10-fold elevated in the LDAA and 150-fold elevated in the HDAA group at 24 hours and decreased in both groups afterwards. HDAA was not associated with a significantly increased risk of any complications. A significant reduction in colloid fluid requirements was noted (LDAA: 947 ± 1722 ml/24 hours vs HDAA: 278 ± 667 ml/24 hours, P = 0.029). Other hemodynamic and resuscitation measures, as well as secondary clinical outcomes were comparable between groups. HDAA was associated with higher AA levels and lower volumes of colloids in adults with severe burns. The rate of adverse events was not significantly higher in patients treated with HDAA. Future studies should consider prolonged administration of AA.
Food as Fuel: Performance Goals Increase the Consumption of High-Calorie Foods at the Expense of Good Nutrition
Authors: Cornil Yann , Gomez Pierrick , Vasiljevic Dimitri
Published: March 2020

At work, at school, at the gym club, or even at home, consumers often face challenging situations in which they are motivated to perform their best. This research demonstrates that activating performance goals, whether in cognitive or physical domains, leads to an increase in the consumption of high-calorie foods at the expense of good nutrition. This effect derives from beliefs that the function of food is to provide energy for the body (food as fuel) coupled with poor nutrition literacy, leading consumers to overgeneralize the instrumental role of calories for performance. Indeed, nutrition experts choose very different foods (lower in calorie, higher in nutritional value) than lay consumers in response to performance goals. Also, performance goals no longer increase calorie intake when emphasizing the hedonic function of food (food for pleasure). Hence, while consumer research often interprets the overconsumption of pleasurable and unhealthy high-calorie foods as a consequence of hedonic goals and self-control failures, our research suggests that this overconsumption may also be explained by a maladaptive motivation to manage energy intake.
Differentiated Integration and Disintegration in the EU: Brexit, the Eurozone Crisis, and Other Troubles
Authors: Markakis Menelaos
Published: March 2020

This article looks at theories of differentiated integration and disintegration in the wake of the Eurozone crisis and the Brexit referendum. It advances four distinct, albeit interrelated, arguments with respect to these proposals. First, it could be contested whether certain policy areas should be pushed to the ‘outer core’ of European integration. Second, it would be very difficult to disentangle those areas to be pushed to the ‘outer core’ from those areas remaining in the ‘inner core’. Third, the legal and institutional arrangements for organizing differentiated integration are equally important. Fourth, even if the problems adumbrated above could be addressed satisfactorily, the emerging arrangements for differentiated integration would differ little from the degree of flexibility or variation that already exists within some of those areas. Brexit may be viewed as an opportunity for reform to ‘fix’ those issues that are regarded as problematic in the design or functioning of the EU. Should it appear desirable to pursue differentiated integration, the better course of action would be to build on those opportunities for differentiated integration that are offered by the EU Treaties. Any forthcoming Treaty revision to take stock of Brexit could be used to give added impetus to differentiated integration.
Cn algebras with Moisil possibility operators
Authors: Figallo Aldo V , Pelaitay Gustavo , Sarmiento Jonathan
Published: March 2020

In this paper, we continue the study of the Łukasiewicz residuation algebras of order $n$ with Moisil possibility operators (or $MC_n$-algebras) initiated by Figallo (1989, PhD Thesis, Universidad Nacional del Sur). More precisely, among other things, a method to determine the number of elements of the $MC_n$-algebra with a finite set of free generators is described. Applying this method, we find again the results obtained by Iturrioz and Monteiro (1966, Rev. Union Mat. Argent., 22, 146) and by Figallo (1990, Rep. Math. Logic, 24, 3–16) for the case of Tarski algebras and $I\varDelta _{3}$-algebras, respectively.
Novel Characteristics of Immune Responsive Protein IRP30 in the Bumble Bee Bombus lantschouensis (Hymenoptera: Apidae)
Authors: Dong Jie , Wu Jie , Han Lei , Huang Jiaxing , Wang Deqian
Published: March 2020

Immune responsive protein 30 (IRP30) is a Hymenoptera-specific protein first identified from honey bee hemolymph in response to bacterial infection. However, its function remains elusive. Here, we cloned the full-length IRP30 gene and clarified its expression pattern in the bumble bee Bombus lantschouensis (Vogt). The full-length IRP30 gene measures 1443 bp and contains two exons and one intron. The length of the cDNA is 1082 bp, including a 36-bp 5′-UTR and a 218-bp 3′-UTR, and it encodes a putative protein of 275 amino acids. As expected, the sequence of the B. lantschouensis IRP30 protein was clustered with the bumble bee group, which appeared as a single clade next to honey bees. The family shared similar conserved protein domains. Moreover, bumble bee IRP30 belongs to a recently diverged clade that has four leucine-rich repeat (LRR) conserved domains. IRP30 is highly expressed in the worker caste, during pupal developmental stages, and in the head and thorax tissues. Interestingly, its expression increases 20- to 90-fold when female bumble bees (B. lantschouensis) and honey bees (Apis mellifera L.) begin laying eggs. Overall, based on the expression of IRP30 during development and egg laying in female bumble bees, this protein not only responds to immune challenge but also may play an important role in metamorphosis and reproduction.
Snowshoe hare feeding behavior responds to coyote and moose cues at diverse vegetation densities
Authors: Lankist Zachary K , Maher Christine R
Published: March 2020

Heterospecific competitors can use chemical cues left by dominant species to avoid aggressive interactions. Similarly, prey avoid chemical cues from predators at feeding sites, presumably because risk of death outweighs the benefit of food. This study addressed the lack of information regarding mammals’ avoidance of direct cues from competitors and also examined how indirect cues, i.e., vegetative cover, affect foraging behavior. To test if chemical cues and vegetative cover alter the number of visits by prey species and time spent at feeding plots, we observed snowshoe hares (Lepus americanus) in plots containing coyote (Canis latrans; predator) and moose (Alces alces; competitor) urine across a spectrum of vegetation densities. Snowshoe hares significantly reduced number of visits to plots that contained coyote or moose urine. In plots treated with coyote urine, number of visits decreased significantly as plots became more densely vegetated. Neither chemical cues nor vegetation density affected time spent in plots. These results suggest that competition between snowshoe hares and moose has selected for an avoidance response. This study also reinforces the idea that an increase in vegetation density could prove disadvantageous to prey, perhaps because some predators use dense vegetation to their advantage.
Characteristic Features of FUS Inclusions in Spinal Motor Neurons of Sporadic Amyotrophic Lateral Sclerosis
Authors: Ikenaka Kensuke , Ishigaki Shinsuke , Iguchi Yohei , Kawai Kaori , Fujioka Yusuke , Yokoi Satoshi , Abdelhamid Rehab F , Nagano Seiichi , Mochizuki Hideki , Katsuno Masahisa , Sobue Gen
Published: March 2020

Alterations of RNA metabolism caused by mutations in RNA-binding protein genes, such as transactivating DNA-binding protein-43 (TDP-43) and fused in sarcoma (FUS), have been implicated in the pathogenesis of amyotrophic lateral sclerosis (ALS). Unlike the accumulation of TDP43, which is accepted as a pathological hall mark of sporadic ALS (sALS), FUS pathology in sALS is still under debate. Although immunoreactive inclusions of FUS have been detected in sALS patients previously, the technical limitation of signal detection, including the necessity of specific antigen retrieval, restricts our understanding of FUS-associated ALS pathology. In this study, we applied a novel detection method using a conventional antigen retrieval technique with Sudan Black B treatment to identify FUS-positive inclusions in sALS patients. We classified pathological motor neurons into 5 different categories according to the different aggregation characteristics of FUS and TDP-43. Although the granular type was more dominant for inclusions with TDP-43, the skein-like type was more often observed in FUS-positive inclusions, suggesting that these 2 proteins undergo independent aggregation processes. Moreover, neurons harboring FUS-positive inclusions demonstrated substantially reduced expression levels of dynactin-1, a retrograde motor protein, indicating that perturbation of nucleocytoplasmic transport is associated with the formation of cytoplasmic inclusions of FUS in sALS.
Efficacy of radiation boost after breast-conserving surgery for breast cancer with focally positive, tumor-exposed margins
Authors: Suzuki Ryoko , Yoshida Masahiro , Oguchi Masahiko , Yoshioka Yasuo , Tokumasu Kenji , Osako Tomo , Ono Shinji , Ueno Takayuki , Miyagi Yumi
Published: March 2020

Many patients with positive margins following breast-conserving surgery (BCS) undergo re-excisions that aim to remove residual disease from the breast, which brings a tremendous emotional burden in addition to financial consequences. We sought to determine whether re-excisions could be safely avoided without compromising local control and survival by using whole-breast radiation therapy (WBRT) with a tumor bed boost in patients with early-stage breast cancer with focally positive, tumor-exposed margins after BCS. All patients with ductal carcinoma in situ (DCIS) and/or invasive breast cancer (IBC) who had pathologically tumor-exposed margins following BCS, without re-excision and treated with WBRT with tumor bed boost between March 2005 and December 2011, were included. The radiotherapy consisted of WBRT at a dose of 50 Gy in 25 fractions, followed by a tumor bed boost with an additional dose of 16 Gy in eight fractions. A total of 125 patients fulfilled the eligibility criteria; of the 125 patients, 1 had bilateral breast cancer, resulting in 126 cases. Invasive disease was found in 102 (81%) cases and purely ductal carcinoma in situ (DCIS) disease in 24 (19%) cases. The 10-year ipsilateral breast tumor recurrence (IBTR) -free survival, progression-free survival (PFS), and 10-year overall survival (OS) rates were 95%, 92.5% and 96%, respectively. Patients with early-stage breast cancer who receive BCS and have focally positive, tumor-exposed margins can avoid re-excision by undergoing WBRT followed by a sufficient dose of tumor bed boost, without negatively impacting local control and survival.
Hydrated electrons induce the formation of interstrand cross-links in DNA modified by cisplatin adducts
Authors: Behmand B , Noronha A M , Wilds C J , Marignier J-L , Mostafavi M , Wagner J R , Hunting D J , Sanche L
Published: March 2020

Double-stranded oligonucleotides containing cisplatin adducts, with and without a mismatched region, were exposed to hydrated electrons generated by gamma-rays. Gel electrophoresis analysis demonstrates the formation of cisplatin-interstrand crosslinks from the cisplatin-intrastrand species. The rate constant per base for the reaction between hydrated electrons and the double-stranded oligonucleotides with and without cisplatin containing a mismatched region was determined by pulse radiolysis to be 7 × 109 and 2 × 109 M−1 s−1, respectively. These results provide a better understanding of the radiosensitizing effect of cisplatin adducts in hypoxic tumors and of the formation of interstrand crosslinks, which are difficult for cells to repair.
Silent burn: the hidden danger and effects of bright light from fibre-optic cables in arthroscopic knee surgery
Authors: Chitnavis Jai
Published: March 2020

Following an uneventful arthroscopic menisectomy of the right knee, a white circular skin lesion, 1 cm in diameter, was noted on the anterior left thigh of a 23-year-old patient. The overlying paper surgical drape had not ignited nor produced smoke. Close inspection revealed a minute perforation in the drape with slight discolouration. No electro-cautery, radio-ablation or irritant skin preparation had been used during surgery. Tests failed to identify fault with the light source, fibre-optic cable or arthroscope.

The lesion was diagnosed as a full-thickness thermal burn resulting from heat transmitted from a 300-W Xenon lamp via a detached fibre-optic cable. The effects of contact between an illuminated fibre-optic light cable and living human skin are described, with changes in appearances followed over 2 years. Patients may be burnt and permanently scarred without the knowledge of staff in operating theatres if detached light cables rest against surgical drapes.
Seasonal nitrogen remobilization and the role of auxin transport in poplar trees
Authors: Li Gen , Lin Rongshoung , Egekwu Chioma , Blakeslee Joshua , Lin Jinshan , Pettengill Emily , Murphy Angus S , Peer Wendy A , Islam Nazrul , Babst Benjamin A , Gao Fei , Komarov Sergey , Tai Yuan-Chuan , Coleman Gary D
Published: March 2020

Seasonal nitrogen (N) cycling in Populus, involves bark storage proteins (BSPs) that accumulate in bark phloem parenchyma in the autumn and decline when shoot growth resumes in the spring. Little is known about the contribution of BSPs to growth or the signals regulating N remobilization from BSPs. Knockdown of BSP accumulation via RNAi and N sink manipulations were used to understand how BSP storage influences shoot growth. Reduced accumulation of BSPs delayed bud break and reduced shoot growth following dormancy. Further, 13N tracer studies also showed that BSP accumulation is an important factor in N partitioning from senescing leaves to bark. Thus, BSP accumulation has a role in N remobilization during N partitioning both from senescing leaves to bark and from bark to expanding shoots once growth commences following dormancy. The bark transcriptome during BSP catabolism and N remobilization was enriched in genes associated with auxin transport and signaling, and manipulation of the source of auxin or auxin transport revealed a role for auxin in regulating BSP catabolism and N remobilization. Therefore, N remobilization appears to be regulated by auxin produced in expanding buds and shoots that is transported to bark where it regulates protease gene expression and BSP catabolism.
Can we detect the stellar differential rotation of WASP-7 through the Rossiter–McLaughlin observations?
Authors: Serrano L M , Oshagh M , Cegla H M , Barros S C C , Santos N C , Faria J P , Akinsanmi B
Published: March 2020

The Rossiter–McLaughlin (RM) effect is the radial velocity signal generated when an object transits a rotating star. Stars rotate differentially and this affects the shape and amplitude of this signal, on a level that can no longer be ignored with precise spectrographs. Highly misaligned planets provide a unique opportunity to probe stellar differential rotation via the RM effect, as they cross several stellar latitudes. In this sense, WASP-7, and its hot Jupiter with a projected misalignment of ∼90°, is one of the most promising targets. The aim of this work is to understand if the stellar differential rotation is measurable through the RM signal for systems with a geometry similar to WASP-7. In this sense, we use a modified version of soap3.0 to explore the main hurdles that prevented the precise determination of the differential rotation of WASP-7. We also investigate whether the adoption of the next generation spectrographs, like ESPRESSO, would solve these issues. Additionally, we assess how instrumental and stellar noise influence this effect and the derived geometry of the system. We found that, for WASP-7, the white noise represents an important hurdle in the detection of the stellar differential rotation, and that a precision of at least 2 m s−1 or better is essential.
HST/WFC3 grism observations of z ∼ 1 clusters: evidence for evolution in the mass–size relation of quiescent galaxies from post-starburst galaxies
Authors: Matharu J , Muzzin A , Brammer G B , van der Burg R F J , Auger M W , Hewett P C , Chan J C C , Demarco R , van Dokkum P , Marchesini D , Nelson E J , Noble A G , Wilson G
Published: March 2020

Minor mergers have been proposed as the driving mechanism for the size growth of quiescent galaxies with decreasing redshift. The process whereby large star-forming galaxies quench and join the quiescent population at the large size end has also been suggested as an explanation for this size growth. Given the clear association of quenching with clusters, we explore this mechanism by studying the structural properties of 23 spectroscopically identified recently quenched (or ‘post-starburst’ (PSB)) cluster galaxies at z ∼ 1. Despite clear PSB spectral signatures implying rapid and violent quenching, 87 per cent of these galaxies have symmetric, undisturbed morphologies in the stellar continuum. Remarkably, they follow a mass–size relation lying midway between the star-forming and quiescent field relations, with sizes 0.1 dex smaller than z ∼ 1 star-forming galaxies at log(M*/M⊙) = 10.5. This implies a rapid change in the light profile without directly effecting the stellar distribution, suggesting changes in the mass-to-light ratio gradients across the galaxy are responsible. We develop fading toy models to explore how star-forming galaxies move across the mass–size plane as their stellar populations fade to match those of the PSBs. ‘Outside-in’ fading has the potential to reproduce the contraction in size and increase in bulge-dominance observed between star-forming and PSB cluster galaxies. Since cluster PSBs lie on the large size end of the quiescent mass–size relation, and our previous work shows cluster galaxies are smaller than field galaxies, the sizes of quiescent galaxies must grow both from the quenching of star-forming galaxies and dry minor mergers.
Parameters of dust jets in comet Encke’s coma
Authors: Chernetenko Yu , Medvedev Yu
Published: March 2020

Using 4412 positional observations, we compute eight single apparition orbits in the period 1993–2017. The analysis of the residuals of the orbit’s fit shows their systematic deviations around perihelia. We assume that these deviations in positional observations are a result of the dust emissions from a restricted area of the nucleus, and that the ejected dust particles contain a certain amount of ice. Additional sublimation of ice from particles causes a gas-rich effect when the comet is approaching the Sun. Another effect of the jet motion of particles is a shift of the centre of brightness in the direction of ejection. Taking these effects into account, we estimate the size of the dust particles (2–10 cm) containing $80{{\ \rm per\ cent}}$ ice, dust velocities (1.8–2.6 m s−1), and the positions of active regions on the comet’s nucleus (cometocentric latitude from 55° to 74°). These estimates are based on the data for the residuals in the positional observations before the perihelia of the 1993, 2003, 2013 and 2017 apparitions.
Energy optimization in extrasolar planetary systems: the transition from peas-in-a-pod to runaway growth
Authors: Adams Fred C , Batygin Konstantin , Bloch Anthony M , Laughlin Gregory
Published: March 2020

Motivated by the trends found in the observed sample of extrasolar planets, this paper determines tidal equilibrium states for forming planetary systems – subject to conservation of angular momentum, constant total mass, and fixed orbital spacing. In the low mass limit, valid for super-Earth-class planets with masses of order mp ∼ 10 M⊕, previous work showed that energy optimization leads to nearly equal mass planets, with circular orbits confined to a plane. The present treatment generalizes previous results by including the self-gravity of the planetary bodies. For systems with a sufficiently large total mass $m_{\scriptstyle \rm T}$ in planets, the optimized energy state switches over from the case of nearly equal mass planets to a configuration where one planet contains most of the material. This transition occurs for a critical mass threshold of approximately $m_{\scriptstyle \rm T}\gtrsim m_{\scriptstyle \rm C}\sim 40\,{\rm M_\oplus}$ (where the value depends on the semimajor axes of the planetary orbits, the stellar mass, and other system properties). These considerations of energy optimization apply over a wide range of mass scales, from binary stars to planetary systems to the collection of moons orbiting the giant planets in our Solar system.
Two-temperature magnetohydrodynamic simulations for sub-relativistic active galactic nucleus jets: dependence on the fraction of the electron heating
Authors: Ohmura Takumi , Machida Mami , Nakamura Kenji , Kudoh Yuki , Matsumoto Ryoji
Published: March 2020

We present the results of two-temperature magnetohydrodynamic simulations of the propagation of sub-relativistic jets of active galactic nuclei. The dependence of the electron and ion temperature distributions on the fraction of electron heating, fe, at the shock front is studied for fe = 0, 0.05, and 0.2. Numerical results indicate that in sub-relativistic, rarefied jets, the jet plasma crossing the terminal shock forms a hot, two-temperature plasma in which the ion temperature is higher than the electron temperature. The two-temperature plasma expands and forms a backflow referred to as a cocoon, in which the ion temperature remains higher than the electron temperature for longer than 100 Myr. Electrons in the cocoon are continuously heated by ions through Coulomb collisions, and the electron temperature thus remains at Te > 109 K in the cocoon. X-ray emissions from the cocoon are weak because the electron number density is low. Meanwhile, X-rays are emitted from the shocked intracluster medium (ICM) surrounding the cocoon. Mixing of the jet plasma and the shocked ICM through the Kelvin–Helmholtz instability at the interface enhances X-ray emissions around the contact discontinuity between the cocoon and shocked ICM.
Chemical evolution of galaxies: emerging dust and the different gas phases in a new multiphase code
Authors: Millán-Irigoyen I , Mollá M , Ascasibar Y
Published: March 2020

Dust plays an important role in the evolution of a galaxy, as it is one of the main ingredients for efficient star formation. Dust grains are also a sink/source of metals when they are created/destroyed, and, therefore, a self-consistent treatment is key in order to correctly model chemical evolution. In this work, we discuss the implementation of dust physics in our current multiphase model, which also follows the evolution of atomic, ionized and molecular gas. Our goal is to model the conversion rates among the different phases of the interstellar medium, including the creation, growth and destruction of dust, based, as far as possible, on physical principles rather than on phenomenological recipes. We first present the updated set of differential equations and then discuss the results. We calibrate our model against observations of the Milky Way Galaxy and compare its predictions with extant data. Our results are broadly consistent with the observed data for intermediate and high metallicities, but the models tend to produce more dust than is observed in the low-metallicity regime.
Physical conditions in two high-redshift H2-bearing GRB-DLAs, 120815A and 121024A
Authors: Shaw Gargi , Ferland G J
Published: March 2020

The gamma-ray burst (GRB) afterglows provide a unique opportunity to study the interstellar medium (ISM) of star-forming galaxies at high-redshift. The GRB-DLAs (damped Lyman-α absorbers) contain a large neutral hydrogen column density, N(H i), and are observed against the GRB afterglow. A large fraction of GRB-DLAs show presence of molecular hydrogen (H2) which is an indicator of star-formation. Hence it is important to study those GRB-DLAs which have H2 lines to decipher and understand their physical conditions. The GRB-DLAs 121024A and 120815A, situated at redshift 2.30 and 2.36, respectively, are two such important H2-bearing GRB-DLAs. Besides H2, these two GRB-DLAs also show many metal lines. In this work we have carried out a detail numerical study on the H2 lines, as well as on those metal lines, in GRB-DLAs 121024A and 120815A self-consistently. We use the spectral synthesis code cloudy for this study. This modelling helps us to determine the underlying physical conditions which give rise to such lines and hence to understand these two GRB-DLAs in much more detail than any other previous investigation. We find that the hydrogen densities for these two H2-bearing DLAs are ≥60 cm−3. Moreover our study infers that the linear sizes are ≤17.7 pc for these two GRB-DLAs, and the mean gas temperatures averaged over the cloud thickness, are ≤140 K. Overall, we find that these two H2-bearing GRB-DLAs are denser, cooler, and smaller compared to those without H2.
Forecast for FAST: from galaxies survey to intensity mapping
Authors: Hu Wenkai , Wang Xin , Wu Fengquan , Wang Yougang , Zhang Pengjie , Chen Xuelei
Published: March 2020

The Five-Hundred-Meter Aperture Spherical Radio Telescope (FAST) is the largest single-dish radio telescope in the world. In this paper, we make forecast on the FAST H i large-scale structure survey by mock observations. We consider a drift scan survey with the L-band 19 beam receiver, which may be commensal with the pulsar search and Galactic H i survey. We also consider surveys at lower frequency, using either the current single feed wide-band receiver or a future multibeam phased array feed (PAF) in the UHF band. We estimate the number density of detected H i galaxies and the measurement error in positions and the precision of the surveys are evaluated using both Fisher matrix and simulated observations. The measurement error in the H i galaxy power spectrum is estimated, and we find that the error is relatively large even at moderate redshifts, as the number of positively detected galaxies drops drastically with increasing redshift. However, good cosmological measurement could be obtained with the intensity mapping technique where the large scale H i distribution is measured without resolving individual galaxies. The figure of merit for the dark energy equation of state with different observation times is estimated, and we find that with the existing L-band multibeam receiver, a good measurement of low redshift large-scale structure can be obtained, which complements the existing optical surveys. With a PAF in the UHF band, the constraint can be much stronger, reaching the level of a dark energy task force stage IV experiment.
Non-local thermodynamic equilibrium line formation for Si i–ii–iii in A–B stars and the origin of Si ii emission lines in ι Her
Authors: Mashonkina Lyudmila
Published: March 2020

A comprehensive model atom was developed for Si i–ii–iii using the most up-to-date atomic data available so far. Based on non-local thermodynamic equilibrium (NLTE) line formation for Si i, Si ii and Si iii and high-resolution observed spectra, we determined the NLTE abundances for a sample of nine unevolved A9–B3 type stars with well-determined atmospheric parameters. For each star, NLTE reduces the line-to-line scatter for Si ii substantially compared with the LTE case and leads to consistent mean abundances from lines of different ionization stages. In the hottest star of our sample, ι Her, Si ii is subject to overionization that drives emission in the lines arising from the high-excitation doublet levels. Our NLTE calculations reproduced 10 emission lines of Si ii observed in ι Her. The same overionization effect leads to greatly weakened Si ii lines, which are observed in absorption in ι Her. Large positive NLTE abundance corrections (up to 0.98 dex for 5055 Å) were useful for achieving consistent mean abundances from lines of the two ionization stages, Si ii and Si iii. It was found that NLTE effects are overestimated for the Si ii 6347, 6371 Å doublet in ι Her, while the new model atom works well for cooler stars. At this stage, we failed to understand this problem. We computed a grid of the NLTE abundance corrections for lines of Si i, Si ii and Si iii in model atmospheres with effective temperatures and surface gravities characteristic of unevolved A–B type stars.
A compact X-ray emitting binary in likely association with 4FGL J0935.3+0901
Authors: Wang Zhongxiang , Xing Yi , Zhang Jujia , Boutsia Konstantina , Wang Gege , V Jithesh , Burdge Kevin B , Coughlin Michael W , Duev Dmitry A , Kulkarni S R , Riddle Reed , Serabyn Eugene
Published: March 2020

4FGL J0935.3+0901 is a γ-ray source detected by the Large Area Telescope (LAT) onboard the Fermi Gamma-Ray Space Telescope. We have conducted detailed analysis of the LAT data for this source and multiwavelength studies of the source field. Its γ-ray emission can be described with a power law (Γ = 2.0 ± 0.2) with an exponential cut-off (Ec = 2.9 ± 1.6 GeV), while the flux shows significant long-term variations. From analysis of archival Neil Gehrels Swift Observatory X-Ray Telescope data, we find only one X-ray source in the LAT’s 2σ error region. Within a $3.7\,{\rm arcsec}$ radius error circle of the X-ray source, there is only one optical object down to r′ ∼ 23 mag. Time-resolved photometry of the optical object indicates a likely 2.5 h periodic modulation, while its spectrum shows double-peaked hydrogen and helium emission lines (similar to those seen in accretion discs in low-mass X-ray binaries). Combining these results, we conclude that we have discovered a compact X-ray emitting binary in likely association with 4FGL J0935.3+0901, i.e. a millisecond pulsar (MSP) binary. We discuss the implication of the optical spectral features: this binary could be a transitional MSP system at a subluminous disc state, although the other possibility, the binary in a rotation-powered state showing the optical emission lines due to intrabinary interaction processes, cannot be excluded. Further observational studies will help to determine detailed properties of this candidate MSP binary and thus clarify its current state.
How do bound star clusters form?
Authors: Krumholz Mark R , McKee Christopher F
Published: March 2020

Gravitationally bound clusters that survive gas removal represent an unusual mode of star formation in the Milky Way and similar spiral galaxies. While forming, they can be distinguished observationally from unbound star formation by their high densities, virialized velocity structures, and star formation histories that accelerate towards the present, but extend multiple free-fall times into the past. In this paper, we examine several proposed scenarios for how such structures might form and evolve, and carry out a Bayesian analysis to test these models against observed distributions of protostellar age, counts of young stellar objects relative to gas, and the overall star formation rate of the Milky Way. We show that models in which the acceleration of star formation is due either to a large-scale collapse or a time-dependent increase in star formation efficiency are unable to satisfy the combined set of observational constraints. In contrast, models in which clusters form in a ‘conveyor belt’ mode where gas accretion and star formation occur simultaneously, but the star formation rate per free-fall time is low, can match the observations.
TESS observations of pulsating subdwarf B stars: extraordinarily short-period gravity modes in CD−28° 1974
Authors: Reed M D , Shoaf K A , Németh P , Vos J , Uzundag M , Baran A S , Sahoo S K , Jeffery C S , Telting J H , Østensen R H
Published: March 2020

Transiting Exoplanet Survey Satellite (TESS) observations show CD−28° 1974 to be a gravity(g)-mode-dominated hybrid pulsating subdwarf B (sdBV) star. It shows 13 secure periods that form an ℓ = 1 asymptotic sequence near the typical period spacing. Extraordinarily, these periods lie between 1500 and 3300 s, whereas typical $\ell = 1\, g$ modes in sdBV stars occur between 3300 and 10 000 s. This indicates a structure somewhat different from typical sdBV stars. CD−28° 1974 has a visually close F/G main-sequence companion 1.33 arcsec away, which may be a physical companion. Gaia proper motions indicate a comoving pair with the same distance. A reanalysis of Ultraviolet and Visual Echelle Spectrograph (UVES) spectra failed to detect any orbital motion and the light curve shows no reflection effect or ellipsoidal variability, making an unseen close companion unlikely. The implication is that CD−28° 1974 has become a hot subdwarf via single star or post-merger evolution.
The radio pulsar population of the Small Magellanic Cloud
Authors: Titus N , Toonen S , McBride V A , Stappers B W , Buckley D A H , Levin L
Published: March 2020

We model the present-day, observable, normal radio pulsar population of the Small Magellanic Cloud (SMC). The pulsars are generated with SeBa, a binary population synthesis code that evolves binaries and the constituent stellar objects up to remnant formation and beyond. We define radio pulsars by selecting neutron stars (NSs) that satisfy a selection of criteria defined by Galactic pulsars, and apply the detection thresholds of previous and future SMC pulsar surveys. The number of synthesized and recovered pulsars is exceptionally sensitive to the assumed star formation history and applied radio luminosity model, but is not affected extensively by the assumed common-envelope model, metallicity, and NS kick velocity distribution. We estimate that the SMC formed (1.6 ± 0.3) ×104 normal pulsars during the last 100 Myr. We study which pulsars could have been observed by the Parkes multibeam survey of the SMC, by applying the survey’s specific selection effects, and recover 4.0 ± 0.8 synthetic pulsars. This is in agreement with their five observed pulsars. We also apply a proposed MeerKAT configuration for the upcoming SMC survey, and predict that the MeerKAT survey will detect 17.2 ± 2.5 pulsars.
On the spatial and temporal non-locality of dynamo mean-field effects in supersonic interstellar turbulence
Authors: Gressel Oliver , Elstner Detlef
Published: March 2020

The interstellar medium (ISM) of the Milky Way and nearby disc galaxies harbour large-scale coherent magnetic fields of microgauss strength, that can be explained via the action of a mean-field dynamo. As in our previous work, we aim to quantify dynamo effects that are self-consistently emerging in realistic direct magnetohydrodynamic simulations, but we generalize our approach to the case of a non-local (non-instantaneous) closure relation, described by a convolution integral in space (time). To this end, we leverage our comprehensive simulation framework for the supernova-regulated turbulent multiphase ISM. By introducing spatially (temporally) modulated mean fields, we extend the previously used test-field method to the spectral realm – providing the Fourier representation of the convolution kernels. The resulting spectra of the dynamo mean-field coefficients that we obtain broadly match expectations and allow to rigorously constrain the degree of scale separation in the Galactic dynamo. A surprising result is found for the diamagnetic pumping term, which increases in amplitude when going to smaller scales. Our results amount to the most comprehensive description of dynamo mean-field effects in the Galactic context to date. Surveying the relevant parameter space and quenching behaviour, this will ultimately enable the development of assumption-free subgrid prescriptions for otherwise unresolved global galaxy simulations.
Pulsation among TESS A and B stars and the Maia variables
Authors: Balona L A , Ozuyar D
Published: March 2020

Classification of over 50 000 TESS stars in sectors 1–18 has resulted in the detection of 766 pulsating main-sequence B stars as well as over 5000 δ Scuti, 2300 γ Doradus, and 114 roAp candidates. Whereas it has been assumed that high-frequency pulsations among B-type main-sequence stars are confined to the early B-type β Cephei stars, the observations indicate that high frequencies are to be found over the whole B-star range, eventually merging with δ Scuti stars. The cool B stars pulsating in high frequencies are called Maia variables. It is shown that Maia variables are not rapidly rotating and thus cannot be β Cephei pulsators that appear to have lower temperatures due to gravity darkening. In the region where β Cephei variables are found, the proportion of pulsating stars is larger and amplitudes are higher and a considerable fraction pulsate in a single mode and low rotation rate. There is no distinct region of slowly pulsating B stars (SPB stars). Stars pulsating solely in low frequencies are found among all B stars. At most, only one-third of B stars appear to pulsate. These results, as well as the fact that a large fraction of A and B stars show rotational modulation, indicate a need for a revision of current ideas regarding stars with radiative envelopes.
A transient α-helix in the N-terminal RNA recognition motif of polypyrimidine tract binding protein senses RNA secondary structure
Authors: Maris Christophe , Jayne Sandrine , Damberger Fred F , Beusch Irene , Dorn Georg , Ravindranathan Sapna , Allain Frédéric H-T
Published: March 2020

The polypyrimidine tract binding protein (PTB) is a multi-domain protein involved in alternative splicing, mRNA localization, stabilization, polyadenylation and translation initiation from internal ribosome entry sites (IRES). In this latter process, PTB promotes viral translation by interacting extensively with complex structured regions in the 5′-untranslated regions of viral RNAs at pyrimidine-rich targets located in single strand and hairpin regions. To better understand how PTB recognizes structured elements in RNA targets, we solved the solution structure of the N-terminal RNA recognition motif (RRM) in complex with an RNA hairpin embedding the loop sequence UCUUU, which is frequently found in IRESs of the picornovirus family. Surprisingly, a new three-turn α3 helix C-terminal to the RRM, folds upon binding the RNA hairpin. Although α3 does not mediate any contacts to the RNA, it acts as a sensor of RNA secondary structure, suggesting a role for RRM1 in detecting pyrimidine tracts in the context of structured RNA. Moreover, the degree of helix formation depends on the RNA loop sequence. Finally, we show that the α3 helix region, which is highly conserved in vertebrates, is crucial for PTB function in enhancing Encephalomyocarditis virus IRES activity.