bluuebunny/crossref_metadata_2025 huggingface dataset:
Experimental study and numerical estimation of moisture effect on charge transport in polymer nanocomposites
Authors: Qiang Dayuan , Wang Xinyu , Wang Yan , Andritsch Thomas , Chen George
Published: April 2020

Polymer nanocomposites as dielectrics have attracted a wide range of research interests due to their improved performance. One of the observed characteristics of polymer nanocomposites is the suppression on space charge injection and accumulation and the charge transport mechanism behind is also investigated based on thermally activated hopping (TAH) and quantum mechanical tunnelling (QMT) mechanisms. However, there still lacks research on the effect of moisture on charge transport characteristics and its relationship with experimental results. We herein proposed a method to re-virtualize the distribution of nanoparticles/their aggregates based on the multidimensional scaling method in the first step, and a simple numerical method is further following to estimate the contribution of TAH and QMT conductivities to the experimental ones. The results, firstly, indicate the presence of moisture could lead to significant charge injections, and for different relative humidity conditions, due to their diverse water shell thickness, the separation distances of nanoparticles where deep/shallow traps locate show an obvious reduction and consequently vary the contribution of TAH and QMT conductivities in the measured ones. Second, the TAH mechanism plays the main role in charge transport/conduction, especially under lower RH conditions, while the obvious increment of QMT conduction is attributed to the reduced trap distances caused by thicker conductive water shells and support the existence of deep traps. Besides, the proposed model could be potentially extended to other research topics on electrical properties of polymer nanocomposites, such as particle size, dispersion/distribution status and filler loading concentrations which can be reflected and explained via the variation of nanoparticle surface/trap site distances.
Neutron scattering study of the orientational disorder and phase transitions in barium carbonate
Authors: Cai Guanqun , Phillips Anthony E , Tucker Matthew G , Dove Martin T
Published: April 2020

Orientational disorder of the molecular

C
O

3

2
−

anions in BaCO3, which occurs naturally as the mineral witherite, has been studied using a combination of neutron total scattering analysed by the reverse Monte Carlo method and molecular dynamics simulations. The primary focus is on the phase transition to the cubic phase, which assumes a rocksalt structure (Strukturbericht type B1) with highly disordered orientations consistent with the mismatch between the site (

m

3

¯

m

) and molecular (3/m) symmetries. Both experiment and simulation show a high degree of disorder, with the C–O bond orientation distribution never exceeding 25% variation from that of a completely uniform distribution, although there are differences between the two methods regarding the nature of these variations. Molecular dynamics simulations are also reported for the analogous phase transitions in the very important mineral calcite, CaCO3. The combination of the simulations and comparison with BaCO3 shows that the properties of calcite at all temperatures within its stability field are affected mostly by the onset of orientational disorder associated with the high-temperature cubic phase, even though this lies outside the stability field of calcite. This is a new understanding of calcite, which previously had been interpreted purely in terms of the phase transition to an intermediate partially-disordered phase. Finally, we also found that witherite itself appears to support the development of orientational disorder on heating, with the simulations showing a sequence of phase transitions that explain the much larger thermal expansion of one axis.
Non-contact capacitive sensing for ECG recording in small animals
Authors: Wang Ting-Wei , Lin Shien-Fong
Published: April 2020

Rat electrocardiography (ECG) is frequently used in biomedical research as a model for exploring heart function in a wide variety of experimental conditions. Subcutaneous ECG is a common approach to record rat heart rhythm using implanted needle electrodes to sense the rat ECG signals with the animal under deep anesthesia. However, such an invasive measurement could cause inconvenience due to cumbersome animal preparation, and the anesthetics are likely to interfere with the autonomic regulation of cardiac rhythm. Most studies used the galvanic contact between animal limb and electrode sensing surface to record cardiac signals from small animals. However, the non-contact approach of capacitive ECG sensing for small laboratory animals has not been extensively investigated. This study aims to develop a non-contact ECG system to promote the ECG measurement of laboratory animals for biomedical research. The method utilizes the capacitive coupling technique to detect cardiac signals in awake rats (R-wave amplitude of only 0.2 mV) through a non-conductive layer. The proposed system generates non-contact ECG signals with distinguishable R-peaks at a limb-electrode capacitance above 8.5 pF and maximum through-thickness of the non-conductive layer of 0.4 mm for heart rate assessment. In conclusion, this study provides non-contact ECG monitoring based on capacitive electrodes to improve the throughput of ECG measurement procedures for biomedical research and establish a lower bound of coupling capacitance for non-contact application to heart rate. The new method is ideally suited for the rapid evaluation of autonomic regulation of heart rhythm in awake laboratory small animals.
A novel procedure for determining the optimal MLC configuration parameters in treatment planning systems based on measurements with a Farmer chamber
Authors: Saez Jordi , Hernandez Victor , Goossens Jo , De Kerf Geert , Verellen Dirk
Published: April 2020

Modelling of the multi-leaf collimator (MLC) in treatment planning systems (TPS) is crucial for the dose calculation accuracy of intensity-modulated radiation therapy plans. However, no standardised methodology for their configuration exists to date. In this study we present a method that separates the effect of each dosimetric characteristic of the MLC, offering comprehensive equations for the determination of the configuration parameters used in the TPS model. The main advantage of the method is that it only requires prior knowledge of the nominal leaf width and is based on doses measured with a Farmer chamber, which is a very well established and robust methodology. Another significant advantage is the required time, since measuring the tests takes only about 30 minutes per energy. Firstly, we provide a theoretical general formalism in terms of the primary fluence constructed from the transmission map obtained from an MLC model for synchronous and asynchronous sweeping beams. Secondly, we apply the formalism to the RayStation TPS as a proof of concept and we derive analytical expressions that allow the determination of the configuration parameters (leaf tip width, tongue-and-groove width, x-position offset and MLC transmission) and describe how they intertwine. Finally, we apply the method to Varian’s Millennium120 and HD120 MLCs in a TrueBeam linear accelerator for different energies and determine the optimal configuration parameters. The proposed procedure is much faster and streamlined than the typical trial-and-error methods and increases the accuracy of dose calculation in clinical plans. Additionally, the procedure can be useful for standardising the MLC configuration process and it exposes the limitations of the implemented MLC model, providing guidance for further improvement of these models in TPSs.
The Use of Variable Frequency Drives of Centrifugal Pumps atthe Pumping Station
Authors: Zyubin I , Pankratov S , Petrov A , Babikova D
Published: April 2020

The article presents the experience of operating real pumping stations in urban water supply. The basic principles of practical modeling of the operation of a group of pumps for a common load are considered. The main errors in the modernization of pumping equipment of water supply units are analyzed.
Study of Cavitation Characteristics of a Cryogenic Pump by Computational Fluid Dynamic Methods
Authors: Babikova D , Petrov A
Published: April 2020

This article is devoted to the study of cavitation characteristics of a centrifugal cryogenic pump. Hydrodynamic simulation of the fluid flow in the wet part of the pump was carried out in order to determine the output parameters of the pump. A critical increase in the temperature of liquid helium, corresponding to the beginning of cavitation in the pump, was determined. A cavitation performance of the pump was built under given operating conditions and a critical NPSH was determined.
Methodology for the comprehensive optimization of a centrifugal pump with a magnetic coupling
Authors: Zaytseva A , Protopopov A
Published: April 2020

The article considers the design of a leakproof pump with a magnetic coupling operating on a chemical fluid. In this work the optimization of the pump assembly was carried out, including hydrostatic bearings and a magnetic coupling, using the STARCCM + simulation package. The throttle diameters optimal for this design are calculated. The author minimized the overflows in the auxiliary cooling paths of the coupling and the axial force on the pump rotor.
Predicted resource of the most loaded bearing of a horizontal centrifugal pump
Authors: Shablovskiy A , Menagarishvili N , Makhlaeva A , Emshina E
Published: April 2020

The paper gives a derivation of the formula for calculating the predicted resource of the most loaded bearing of a horizontal centrifugal pump. A model of a horizontal centrifugal pump, as well as the action of axial forces and radial reactions, are considered.
The presence of the “locking effect” when the fluid flows through the cylindrical throttle channels
Authors: Kuznetsov V , Yarots V
Published: April 2020

A study was made for the continuous flow of the working fluid through a cylindrical throttle channel (so-called “locking effect”). The flow of the fluid into the atmosphere and the change in absolute pressure at the inlet to the throttle channel ranging between 0.221 MPa and 0.24 MPa are studied. It was found that the pressure in the compressed section inside the throttle channel remains almost constant and equal to 4 kPa. A comparison is made of the experimental values of the flow rate determined for the same absolute pressure difference Δp in the separated and unseparated flow regimes. Knowing that the value of the flow coefficient μ in the zone of the existence of the “locking effect” can be determined from known data for the process of fluid outflow from holes with a sharp edge in a thin wall. Also, similar phenomena occur when fluid flows through small holes and slots in the guide, control and regulatory equipment of various hydraulic systems.
Technological heredity effect on fatigue strength of hydropower plant parts after combined processing
Authors: Yakovleva A , Dubov A , Sobranin A , Karpovich E , Marchenkov A
Published: April 2020

The paper investigates the effect of combined processing on fatigue strength. We developed a plant for combined processing, processed 40X steel samples with various modes. Furthermore, we experimentally studied the fatigue strength of the samples by the metal magnetic memory method, and found the relationship between stress concentration zones and combined processing modes under the heredity factor effect. Finally, we gave recommendations on the use of combined processing for hardening parts of hydropower plants.
Calculation of the hydro-pneumatic suspension damper
Authors: Britsin S , Ryabinin M , Sarach E
Published: April 2020

Annotation

The paper considers general approaches to the design and calculation of the characteristics of hydropneumatic dampers that can be used in the suspensions of mobile cars. It is paid particular attention to the determination of the main hydraulic characteristics of the flow part of the damper, including a direct-acting belt valve, based on numerical simulation.
Investigation of the flow part of a high-speed vane pump of a hydraulic unit using numerical hydrodynamic modeling
Authors: Derevianko M , Ryabinin M
Published: April 2020

Annotation

On this paper was studied the flow part of a high-speed vane pump of a hydraulic unit for pumping fuel of a passenger transport aircraft. To solve the task was used a numerical method for hydrodynamic modeling. It is described the used mathematical model. The obtained pressure and torque graphs on the shaft are given, depending on the feed of the centrifugal pump. The obtained data can be used for further design of the hydraulic unit.
Complex optimization of vaned stators of high-speed centrifugal pumps for thermal stabilization systems
Authors: Kochetov A , Petrov A , Kuleshova M
Published: April 2020

The scope of the pumps for thermal stabilization systems, the main elements of such pumps, their configurations and basic requirements for pumps of this type are considered. In order to increase efficiency, an optimization of the pump vaned stator is carried out. Such simulation results as efficiency and pressure values for each variant are obtained. The data received is analyzed and appropriate conclusion on the efficiency of optimization approach is made.
Tough and conductive polymer hydrogel based on double network for photo-curing 3D printing
Authors: Ding Xueyuan , Jia Runping , Gan Zuzhong , Du Yong , Wang Dayang , Xu Xiaowei
Published: April 2020

Conductive hydrogels (CHs) have attracted significant attention in wearable equipment and soft sensors due to their high flexibility and conductivity. However, CHs with high-strength and free-structure still need to be further explored. Herein, 3D printing high-strength conductive polymer hydrogels (CPHs) based on a double network was prepared. Firstly, PHEA-PSS hydrogels were prepared by copolymerizing 2-Hydroxyethyl acrylate (HEA) with 4-Vinylbenzenesulfonic acid (SSS) using a photo-curing 3D printer. Then 3, 4-Ethylenedioxythiophene (EDOT) was in situ polymerized in the network of PHEA-PSS to obtain the PHEA-PSS/PEDOT hydrogels. It can not only satisfy the printing of complex spatial structures, but also has high mechanical and electrical properties. When the content of EDOT is 12 wt%, the tensile strength of the PHEA-PSS/PEDOT hydrogels is close to 8 MPa, the electrical conductivity reach to 1.2 S cm−1 and the elasticity remain unchanged. Due to the presence of hydrogen and coordination bonds, CPHs have certain self-heal ability. In addition, the resistance of the hydrogel is sensitive to the changes of external pressure. The results show that CPHs can be used as a 3D printing material for flexible sensors.
Electron localisation descriptors in ONETEP: a tool for interpreting localisation and bonding in large-scale DFT calculations
Authors: Clements R J , Womack J C , Skylaris C-K
Published: April 2020

Electron localisation descriptors, such as the electron localisation function (ELF) and localised orbital locator (LOL) provide a visual tool for interpreting the results of electronic structure calculations. The descriptors produce a quantum valence shell electron pair repulsion (VSEPR) representation, indicating the localisation of electron pairs into bonding pairs and lone pairs in single molecules, coordination compounds and crystalline solids. We have implemented the ELF and LOL within ONETEP, a DFT code designed to perform calculations on systems containing thousands of atoms with plane-wave accuracy. This is possible using a linear-scaling formulation of DFT in which the Kohn–Sham orbitals are expressed in terms of a set of strictly localised non-orthogonal generalised Wannier functions (NGWFs), themselves expanded in a psinc basis set. In this paper, we describe our implementation and explore the chemical insights offered by electron localisation descriptors in ONETEP in a range of bonding and nonbonded situations.
Sedation Modulates Frontotemporal Predictive Coding Circuits and the Double Surprise Acceleration Effect
Authors: Witon Adrien , Shirazibehehsti Amirali , Cooke Jennifer , Aviles Alberto , Adapa Ram , Menon David K , Chennu Srivas , Bekinschtein Tristan , Lopez Jose David , Litvak Vladimir , Li Ling , Friston Karl , Bowman Howard
Published: April 2020

Two important theories in cognitive neuroscience are predictive coding (PC) and the global workspace (GW) theory. A key research task is to understand how these two theories relate to one another, and particularly, how the brain transitions from a predictive early state to the eventual engagement of a brain-scale state (the GW). To address this question, we present a source-localization of EEG responses evoked by the local-global task—an experimental paradigm that engages a predictive hierarchy, which encompasses the GW. The results of our source reconstruction suggest three phases of processing. The first phase involves the sensory (here auditory) regions of the superior temporal lobe and predicts sensory regularities over a short timeframe (as per the local effect). The third phase is brain-scale, involving inferior frontal, as well as inferior and superior parietal regions, consistent with a global neuronal workspace (GNW; as per the global effect). Crucially, our analysis suggests that there is an intermediate (second) phase, involving modulatory interactions between inferior frontal and superior temporal regions. Furthermore, sedation with propofol reduces modulatory interactions in the second phase. This selective effect is consistent with a PC explanation of sedation, with propofol acting on descending predictions of the precision of prediction errors; thereby constraining access to the GNW.
An Epidemic Recovery Framework to Jump-start Analysis, Planning, and Action on a Neglected Aspect of Global Health Security
Authors: Schoch-Spana Monica
Published: April 2020

Epidemic readiness and response command the disproportionate attention of health security decision makers, planners, and practitioners, overshadowing recovery. How patients and their families, health organizations, community sectors, and entire societies recuperate from major outbreaks requires more systematic study and better translation into policy and guidance. To help remedy this neglected aspect of health emergency management, we offer a working definition for epidemic recovery and a preliminary model of postepidemic recovery. Guiding this framework’s development are insights gleaned from the more mature study of postdisaster reconstruction and rehabilitation as well as recognition that postoutbreak recovery—which involves infectious disease, a biological hazard—presents challenges and opportunities distinct from events involving geological or meteorological hazards. Future work includes developing a consensus around characteristics of successful epidemic recovery, applying these metrics to support preincident planning for postepidemic recovery, and using such a scheme to track and inform actual recovery from an epidemic.
Contact Tracing for COVID-19: An Opportunity to Reduce Health Disparities and End the Human Immunodeficiency Virus/AIDS Epidemic in the United States
Authors: Nosyk Bohdan , Armstrong Wendy S , del Rio Carlos
Published: April 2020

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) testing and contact tracing have been proposed as critical components of a safe and effective coronavirus disease 2019 (COVID-19) public health strategy. We argue that COVID-19 contact tracing may provide a unique opportunity to also conduct widespread HIV testing, among other health-promotion activities.
Left atrial appendage thrombus on full-dose dabigatran treatment: a case report
Authors: Candelaresi Paolo , Iannuzzi Angela , Servillo Giovanna , Gottilla Rossella
Published: April 2020

Background

Dabigatran is a direct competitive thrombin inhibitor approved for stroke prevention in non-valvular atrial fibrillation. At full-dose, dabigatran showed similar rates of bleedings and higher efficacy compared to warfarin.

Case summary

We report a case of acute ischaemic stroke in a patient treated with dabigatran 150 mg b.i.d. for atrial fibrillation. After an off-label treatment with idarucizumab, a humanized monoclonal antibody approved for dabigatran reversal, we performed a successful intravenous thrombolysis (IVT). Transoesophageal echocardiography showed a left atrial appendage (LAA) thrombus, despite full-dose dabigatran and an adequate therapy adherence.

Discussion

There are few cases of LAA thrombus during dabigatran treatment reported in literature till date. We analyse the possible pathogenetic mechanisms involved in dabigatran failure, including drug interactions and unexpected genetic variations interfering with dabigatran serum levels suggesting periodical assessment of direct Oral Anticoagulant levels. Furthermore, we confirm initial reports of safety and efficacy of intravenous thrombolysis after idarucizumab, in case of dabigatran failure.
‘Minimalist approach’ for transcatheter mitral valve replacement using intracardiac echocardiography and conscious sedation: a case series
Authors: Cubeddu Robert J , Sarkar Abdullah , Navas Viviana , Navia Jose L
Published: April 2020

Background

Transcatheter aortic valve implantation operators have adapted to a less invasive technique by foregoing the use of general anaesthesia and transoesophageal echocardiography. This is known as a ‘minimalist approach’. This approach has yet to be explored in transcatheter mitral valve replacement (TMVR). Two patients with high perioperative risk underwent TMVR using only monitored conscious sedation (CS) and intracardiac echocardiography (ICE).

Case summary

The patients were symptomatic and required treatment of severe mitral regurgitation and severe mitral stenosis in a mitral valve ring and prosthetic mitral valve, respectively. With the use of an antegrade transseptal approach, the procedure was conducted under CS using ICE only. After placement of the prosthetic mitral valve, the valve was assessed by advancing the ICE catheter through the interatrial septal defect and no significant paravalvular leak occurred. In one case, ad hoc treatment of right to left shunting was successfully pursued. Valve function was excellent immediately and at 24 h after implantation and resulted in significant haemodynamic improvement.

Conclusion

With more TMVR cases being conducted, the ‘minimalist approach’ with CS and ICE may be considered in selected cases.
Mitral valve bio-prosthesis and annuloplasty thrombosis during extracorporeal membrane oxygenation: case series
Authors: Challa Abhinay , Latona Jilani , Fraser John , Spanevello Michelle , Scalia Gregory , Burstow Darryl , Platts David
Published: April 2020

Background

Veno-arterial extracorporeal membrane oxygenation (VA-ECMO) is a well-recognized form of haemodynamic support for patients with refractory cardiogenic shock, who are unable to be weaned off cardiopulmonary bypass. Thrombosis or bleeding from cannula sites or surgical wounds are the leading cause of morbidity and mortality in these patients, and presents a delicate balance of anticoagulation during management of patients undergoing circulatory support.

Case summary

In this case series, we discuss three cases of patients undergoing mitral valve replacements or repair with thrombosis of their new bio-prosthesis in the immediate post-operative setting. All three patients were supported with VA-ECMO post-operatively, and thrombosis occurred despite anticoagulation.

Discussion

During extracorporeal membrane oxygenation, the reduced flow throughout the heart increases the risk of intra-cardiac thrombosis. This is of particular importance in the context of mitral valve replacements and repairs, where the bio-prosthesis is an additional risk factor for thrombosis. Our cases demonstrate the morbidity and mortality of such complications, with the likely aetiology being low transvalvular flow in a newly inserted valve combined with the pro-thrombotic state created by the VA-ECMO circuit.
Delineating anatomy and function with multimodality imaging: a case report of giant right coronary artery aneurysms
Authors: Kassab Kameel , Iskander Mina , Malhotra Saurabh , Pyslar Nataliya
Published: April 2020

Background

Giant coronary artery aneurysms (CAAs) are rare and have been reported in patients with connective tissue diseases, arteritides, and atherosclerosis. Given the rarity of the condition, multimodality imaging is essential for comprehensive evaluation of coronary aneurysms and determination of their haemodynamic significance.

Case summary

A 58-year-old Filipino female was evaluated for dyspnoea on exertion of one month. Chest computed tomography (CT) showed right coronary artery (RCA) aneurysms. Invasive coronary angiogram (ICA) confirmed two giant aneurysms of the RCA. Distal RCA could not be opacified due to contrast stagnation in the proximal aneurysms. Coronary CT angiography (CCTA) depicted an additional giant distal RCA aneurysm not visualized on ICA with intraluminal thrombosis. Contrast-enhanced cardiac magnetic resonance imaging (CMR) revealed delayed time to peak perfusion in the mid to apical inferior walls, on first-pass imaging, without myocardial scarring. Late gadolinium images revealed aneurysmal wall inflammation.

Discussion

This case highlights the anatomical findings of giant CAA and the application of multimodality imaging for their accurate characterization. While ICA confirmed the presence of the aneurysms, CCTA enabled the assessment of their full extent and depict intraluminal thrombosis. Contrast-enhanced CMR delineated aneurysm wall characteristics, with first-pass images demonstrating reduced inferior wall perfusion at rest, which was likely the cause of patient’s exertional symptoms. Management of giant coronary aneurysms involves surgical resection with bypass grafting.
Long-term clinical outcomes of losartan in patients with Marfan syndrome: follow-up of the multicentre randomized controlled COMPARE trial
Authors: van Andel Mitzi M , Indrakusuma Reza , Jalalzadeh Hamid , Balm Ron , Timmermans Janneke , Scholte Arthur J , van den Berg Maarten P , Zwinderman Aeilko H , Mulder Barbara J M , de Waard Vivian , Groenink Maarten
Published: April 2020

Aims

The COMPARE trial showed a small but significant beneficial effect of 3-year losartan treatment on aortic root dilatation rate in adults with Marfan syndrome (MFS). However, no significant effect was found on clinical endpoints, possibly due to a short follow-up period. The aim of the current study was therefore to investigate the long-term clinical outcomes after losartan treatment.

Methods and results

In the original COMPARE study (inclusion 2008–2009), adult patients with MFS (n = 233) were randomly allocated to either the angiotensin-II receptor blocker losartan® on top of regular treatment (β-blockers in 71% of the patients) or no additional medication. After the COMPARE trial period of 3 years, study subjects chose to continue their losartan medication or not. In a median follow-up period of 8 years, 75 patients continued losartan medication, whereas 78 patients, originally allocated to the control group, never used losartan after inclusion. No differences existed between baseline characteristics of the two groups except for age at inclusion [losartan 34 (interquartile range, IQR 26–43) years, control 41 (IQR 30–52) years; P = 0.031], and β-blocker use (losartan 81%, control 64%; P = 0.022). A pathological FBN1 mutation was present in 76% of patients and 58% of the patients were male. Clinical endpoints, defined as all-cause mortality, aortic dissection/rupture, elective aortic root replacement, reoperation, and vascular graft implantation beyond the aortic root, were compared between the two groups. A per-patient composite endpoint was also analysed. Five deaths, 14 aortic dissections, 23 aortic root replacements, 3 reoperations, and 3 vascular graft implantations beyond the aortic root occurred during follow-up. Except for aortic root replacement, all endpoints occurred in patients with an operated aortic root. Patients who used losartan during the entire follow-up period showed a reduced number of events compared to the control group (death: 0 vs. 5, P = 0.014; aortic dissection: 3 vs. 11, P = 0.013; elective aortic root replacement: 10 vs. 13, P = 0.264; reoperation: 1 vs. 2, P = 0.463; vascular graft implantations beyond the aortic root 0 vs. 3, P = 0.071; and composite endpoint: 14 vs. 26, P = 0.019). These results remained similar when corrected for age and β-blocker use in a multivariate analysis.

Conclusion

These results suggest a clinical benefit of combined losartan and β-blocker treatment in patients with MFS.
Retrieval of amplitude and attenuation from ambient seismic noise: synthetic data and practical considerations
Authors: Zhou Lianqing , Song Xiaodong , Weaver Richard L
Published: April 2020

Ambient noise correlation has been used extensively to retrieve traveltimes of surface waves. However, studies of retrieving amplitude information and attenuation from ambient noise are limited. In this study, we develop methods and strategies to extract Rayleigh wave amplitude and attenuation from ambient noise correlation, based on theoretical derivation, numerical simulation, and practical considerations of real seismic data. The synthetic data included a numerical simulation of a highly anisotropic noise source and Earth-like temporally varying strength. Results from synthetic data validate that amplitudes and attenuations can indeed be extracted from noise correlations for a linear array. A temporal flattening procedure is effective in speeding up convergence while preserving relative amplitudes. The traditional one-bit normalization and other types of temporal normalization that are applied to each individual station separately are problematic in recovering attenuation and should be avoided. In this study, we propose an ‘asynchronous’ temporal flattening procedure for real data that does not require all stations to have data at the same time. Furthermore, we present the detailed procedure for amplitude retrieval from ambient noise. Tests on real data suggest attenuations extracted from our noise-based methods are comparable with those from earthquakes. Our study shows an exciting promise of retrieving amplitude and attenuation information from ambient noise correlations and suggests practical considerations for applications to real data.
Characteristics of REPRIEVE Trial Participants Identifying Across the Transgender Spectrum
Authors: Smeaton Laura M , Kileel Emma M , Grinsztejn Beatriz , Gardner Edward M , Starr Kate , Murry Melissa L , Desvigne-Nickens Patrice , Alston-Smith Beverly , Waclawiw Myron A , Cooper-Arnold Katharine , Madruga José V , Sangle Shashi , Fitch Kathleen V , Zanni Markella V , Douglas Pamela S , Ribaudo Heather J , Grinspoon Steven K , Klingman Karin L
Published: April 2020

Because persons who identify across the transgender spectrum (PATS) are a key population in human immunodeficiency virus (HIV) yet are underreported in HIV and cardiovascular research, we aimed to characterize this population within the REPRIEVE global clinical trial (n = 7770). Acceptance of gathering gender identity was high (96%). Participation by PATS was 1.7% overall, 2.4% among natal males, 0.3% among natal females, and varied across geographic regions (from 0% in sub-Saharan Africa to 2.3% in High Income Region). Thirty percent of natal male PATS identified other than transgender. Some characteristics differed by gender. Most notably, 38% of natal male PATS receiving gender-affirming treatment had waist circumference >102 cm (compared with ≤25% in other groups). Given that PATS is a key population, HIV research should routinely report trial participation and outcomes by gender in addition to natal sex, to provide the results needed to optimize medical care to PATS.
Modeling-Based Response-Guided Glecaprevir-Pibrentasvir Therapy for Chronic Hepatitis C to Identify Patients for Ultrashort Treatment Duration
Authors: Dasgupta Swikriti , Imamura Michio , Gorstein Evan , Nakahara Takashi , Tsuge Masataka , Churkin Alexander , Yardeni David , Etzion Ohad , Uprichard Susan L , Barash Danny , Cotler Scott J , Dahari Harel , Chayama Kazuaki
Published: April 2020

We recently showed in a proof-of-concept study that real-time modeling-based response-guided therapy can shorten hepatitis C virus treatment duration with sofosbuvir-velpatasvir, elbasvir-grazoprevir, and sofosbuvir-ledipasvir without compromising efficacy, confirming our retrospective modeling reports in >200 patients. However, retrospective modeling of pibrentasvir-glecaprevir (P/G) treatment has yet to be evaluated. In the current study, modeling hepatitis C virus kinetics in 44 cirrhotic and noncirrhotic patients predicts that P/G treatment might have been reduced to 4, 6, and 7 weeks in 16%, 34%, and 14% of patients, respectively. These results support the further evaluation of a modeling-based response-guided therapy approach using P/G.
Diabetes-Related Complications and Pancreatic Cancer Incidence in the Multiethnic Cohort
Authors: Farias Albert J , Wu Anna H , Porcel Jacqueline , Marchand Loïc Le , Wilkens Lynne R , Monroe Kristine R , Maskarinec Gertraud , Pandol Stephen J , Setiawan Veronica Wendy
Published: April 2020

Background

People with diabetes are at an increased risk of developing pancreatic cancer. However, it is unclear whether diabetes-related complications are associated with risk of pancreatic cancer.

Methods

A nested matched case-control analysis was conducted among the fee-for-service Medicare participants of the prospective Multiethnic Cohort (n = ∼123 000). Between 2001 and 2014, 433 incident cases of pancreatic ductal adenocarcinoma were matched to 1728 controls by birth year, sex, race and ethnicity, and age at cohort entry. Participants were linked to data from the California and Hawaii cancer registries and Medicare claims. We used the diabetes complications severity index (DCSI) for the presence of 7 complications within 2 years prior to the diagnosis date of the index case. Multivariable conditional logistic regression was used to examine the association of DCSI with pancreatic cancer incidence.

Results

Diabetes was present among 45.4% of cases and 34.1% of controls. Cases had higher DCSI score compared with controls (score ≥4: 32.8% in cases; 21.2% in controls). The most prevalent diabetes-related complications for cases were cardiovascular disease (61.2%), nephropathy (31.2%), and cerebrovascular disease (21.7%). Individuals with diabetes (odds ratio [OR] = 1.48, 95% confidence interval [CI] = 1.14 to 1.91), nephropathy (OR = 1.75, 95% CI = 1.32 to 2.33), cardiovascular disease (OR = 1.88, 95% CI = 1.45 to 2.44), and metabolic complications (OR = 6.61, 95% CI = 2.49 to 17.50) were at increased risk of pancreatic cancer. For every 1-unit increase in DCSI score, participants had 18% greater risk of pancreatic cancer (OR = 1.18, 95% CI = 1.11 to 1.25).

Conclusions

Participants with diabetes-related complications have an elevated risk of pancreatic cancer. Identifying diabetes-related complications may help identify high-risk groups who can be studied for development of early markers for this fatal cancer.
Infections Within the First Month After Pediatric Lung Transplantation: Epidemiology and Impact on Outcomes
Authors: Onyearugbulem Chinyere , Coss-Bu Jorge , Gazzaneo Maria C , Melicoff Ernestina , Das Shailendra , Lam Fong , Mallory George B , Munoz Flor M
Published: April 2020

Background

Despite successes in lung transplantation, with infection as the leading cause of death in the first year following lung transplantation, there remains a lag in survival compared with other solid organ transplants. Infections that occur early after transplantation may impact short- and long-term outcomes in pediatric lung transplant recipients (LTRs).

Methods

We performed a retrospective review of pediatric LTRs at a large quaternary-care hospital from January 2009 to March 2016 to evaluate both epidemiologic features of infection in the first 30 days post-transplantation and mortality outcomes. The 30 days were divided into early (0–7 days) and late (8–30 days) periods.

Results

Among the 98 LTRs, there were 51 episodes of infections. Cystic fibrosis (CF) was associated with early bacterial infections (P = .004) while non-CF was associated with late viral (P = .02) infections. Infection after transplantation was associated with worse survival by Kaplan-Meier analysis (P value log rank test = .007). Viral infection in the late period was significantly associated with 3-year mortality after multivariable analysis (P = .02).

Conclusions

Infections in pediatric LTRs were frequent in the first 30 days after transplant, despite perioperative antimicrobial coverage. The association of 3-year mortality with late viral infections suggests a possible important role in post-transplant lung physiology and graft function. Understanding the epidemiology of early post-lung transplant infections can help guide post-operative management and interventions to reduce their incidence and the early- and long-term impact in this population.
Root phenotypes of young wheat plants grown in controlled environments show inconsistent correlation with mature root traits in the field
Authors: Rich Sarah M , Christopher Jack , Richards Richard , Watt Michelle
Published: April 2020

Using a field to lab approach, mature deep-rooting traits in wheat were correlated to root phenotypes measured on young plants from controlled conditions. Mature deep-rooting root traits of 20 wheat genotypes at maturity were established via coring in three field trials across 2 years. Field traits were correlated to phenotypes expressed by the 20 genotypes after growth in four commonly used lab screens: (i) soil tubes for root emergence, elongation, length, and branching at four ages to 34 days after sowing (DAS); (ii) paper pouches 7 DAS and (iii) agar chambers for primary root (PR) number and angles at 8 DAS; and (iv) soil baskets for PR and nodal root (NR) number and angle at 42 DAS. Correlations between lab and field root traits (r2=0.45–0.73) were highly inconsistent, with many traits uncorrelated and no one lab phenotype correlating similarly across three field experiments. Phenotypes most positively associated with deep field roots were: longest PR and NR axiles from the soil tube screen at 20 DAS; and narrow PR angle and wide NR angle from soil baskets at 42 DAS. Paper and agar PR angles were positively and significantly correlated to each other, but only wide outer PRs in the paper screen correlated positively to shallower field root traits. NR phenotypes in soil baskets were not predicted by PR phenotypes in any screen, suggesting independent developmental controls and value in measuring both root types in lab screens. Strong temporal and edaphic effects on mature root traits, and a lack of understanding of root trait changes during plant development, are major challenges in creating controlled-environment root screens for mature root traits in the field.
ProSpect: generating spectral energy distributions with complex star formation and metallicity histories
Authors: Robotham A S G , Bellstedt S , Lagos C del P , Thorne J E , Davies L J , Driver S P , Bravo M
Published: April 2020

We introduce ProSpect, a generative galaxy spectral energy distribution (SED) package that encapsulates the best practices for SED methodologies in a number of astrophysical domains. ProSpect comes with two popular families of stellar population libraries (BC03 and EMILES), and a large variety of methods to construct star formation and metallicity histories. It models dust through the use of a Charlot & Fall attenuation model, with re-emission using Dale far-infrared templates. It also has the ability to model active galactic nucleus (AGN) through the inclusion of a simple AGN and hot torus model. Finally, it makes use of MAPPINGS-III photoionization tables to produce line emission features. We test the generative and inversion utility of ProSpect through application to the Shark galaxy formation semi-analytic code, and informed by these results produce fits to the final ultraviolet to far-infrared photometric catalogues produces by the Galaxy and Mass Assembly Survey. As part of the testing of ProSpect, we also produce a range of simple photometric stellar mass approximations covering a range of filters for both observed frame and rest-frame photometry.
Galaxy mergers in eagle do not induce a significant amount of black hole growth yet do increase the rate of luminous AGN
Authors: McAlpine Stuart , Harrison Chris M , Rosario David J , Alexander David M , Ellison Sara L , Johansson Peter H , Patton David R
Published: April 2020

We investigate the connection between galaxy–galaxy mergers and enhanced black hole (BH) growth using the cosmological hydrodynamical eagle simulation. We do this via three methods of analysis, investigating: the merger fraction of AGN, the AGN fraction of merging systems, and the AGN fraction of galaxies with close companions. In each case, we find an increased abundance of AGN within merging systems relative to control samples of inactive or isolated galaxies (by up to a factor of ≈3 depending on the analysis method used), confirming that mergers are enhancing BH accretion rates for at least a subset of the galaxy population. The greatest excess of AGN triggered via a merger are found in lower mass (M* ∼ 1010 M⊙) gas rich (fgas > 0.2) central galaxies with lower mass BHs (MBH ∼ 107 M⊙) at lower redshifts (z < 1). We find no enhancement of AGN triggered via mergers in more massive galaxies (M* ≳ 1011 M⊙). The enhancement of AGN is not uniform throughout the phases of a merger, and instead peaks within the early remnants of merging systems (typically lagging ≈300 Myr post-coalescence of the two galaxies at z = 0.5). We argue that neither major ($M_{\mathrm{*,1}} / M_{\mathrm{*,2}} \ge \frac{1}{4}$) nor minor mergers ($\frac{1}{10} \lt M_{\mathrm{*,1}} / M_{\mathrm{*,2}} \lt \frac{1}{4}$) are statistically relevant for enhancing BH masses globally. Whilst at all redshifts the galaxies experiencing a merger have accretion rates that are on average 2–3 times that of isolated galaxies, the majority of mass that is accreted on to BHs occurs outside the periods of a merger. We compute that on average no more than 15 per cent of a BHs final day mass comes from the enhanced accretion rates triggered via a merger.
Ionic emissions in comet C/2016 R2 (Pan-STARRS)
Authors: Venkataramani Kumar , Ganesh Shashikiran , Baliyan Kiran S
Published: April 2020

We have carried out observations of a peculiar comet, C/2016 R2 (Pan-STARRS), using a low-resolution spectrograph mounted on the 1.2-m telescope at Mount Abu Infrared Observatory, India. The comet was observed on two dates in 2018 January, when it was at a heliocentric distance of 2.8 au. A study based on our observations has revealed that the optical spectrum of this comet is quite unusual compared with general cometary spectra. Most major cometary emissions, such as C2, C3 and CN, were absent in comet C/2016 R2. However, the comet’s spectrum showed very strong emission bands from ionic species such as CO+ and N$_{2}^{+}$. A mean N2/CO ratio of 0.09 ± 0.02 was derived from the spectra and an extremely low depletion factor of 1.6 ± 0.4 has been estimated for this ratio compared with the solar nebula. We have also detected minor emission features beyond 5400 Å, albeit marginally. The column densities of CO+ and N$_{2}^{+}$ were calculated from their emission bands. The optical spectrum suggests that the cometary ice is dominated by CO. The low depletion factor of the N2/CO ratio in this comet, compared with the solar nebula, and the unusual spectrum of the comet are consequences of distinctive processing at the location of its formation in the early solar nebula.
Evidence that emission and absorption outflows in quasars are related
Authors: Xu Xinfeng , Zakamska Nadia L , Arav Nahum , Miller Timothy , Benn Chris
Published: April 2020

We analyse VLT/X-shooter data for seven quasars, where we study the relationships between their broad absorption line (BAL) and emission line outflows. We find (1) the luminosity of the [O iii] λ5007 emission profile decreases with increasing electron number density ($n_\mathrm{e}$) derived from the BAL outflow in the same quasar, (2) the measured velocity widths from the [O iii] emission features and C iv absorption troughs in the same object are similar, and (3) the mean radial velocity derived from the BAL outflow is moderately larger than the one from the [O iii] emission outflow. These findings are consistent with [O iii] and BAL outflows being different manifestations of the same wind, and the observed relationships are likely a reflection of the outflow density distribution. When we have outflows with smaller distances to the central source, their $n_\mathrm{e}$ is higher. Therefore, the [O iii] emission is collisionally de-excited and the [O iii] luminosity is then suppressed. Comparisons to previous studies show that the objects in our sample exhibit broad [O iii] emission features similar to the ones in extremely red quasars (ERQs). This might imply that BAL quasars and ERQs have the same geometry of outflows or are at a similar evolutionary stage. We find that the physical parameters derived from the BAL outflows can explain the amount of observed [O iii] luminosity, which strengthens our claim that both BAL and [O iii] outflows are from the same wind. These estimates can be tested with upcoming James Webb Space Telescope, which will be able to spatially resolve some of the ionized gas outflows.
Stellar property statistics of massive haloes from cosmological hydrodynamics simulations: common kernel shapes
Authors: Anbajagane Dhayaa , Evrard August E , Farahi Arya , Barnes David J , Dolag Klaus , McCarthy Ian G , Nelson Dylan , Pillepich Annalisa
Published: April 2020

We study stellar property statistics, including satellite galaxy occupation, of haloes in three cosmological hydrodynamics simulations: BAHAMAS + MACSIS, IllustrisTNG, and Magneticum Pathfinder. Applying localized linear regression, we extract halo mass-conditioned normalizations, slopes, and intrinsic covariance for (i) Nsat, the number of stellar mass-thresholded satellite galaxies within radius R200c of the halo; (ii) $M_{\star , \rm tot}$, the total stellar mass within that radius, and (iii) $M_{\star ,\rm BCG}$, the gravitationally bound stellar mass of the central galaxy within a $100 \, \rm kpc$ radius. The parameters show differences across the simulations, in part from numerical resolution, but there is qualitative agreement for the $N_{\rm sat}\!-\! M_{\star ,\rm BCG}$ correlation. Marginalizing over Mhalo, we find the Nsat kernel, $p(\ln N_{\rm sat}\, |\, M_{\rm halo}, z)$ to be consistently skewed left in all three simulations, with skewness parameter γ = −0.91 ± 0.02, while the $M_{\star , \rm tot}$ kernel shape is closer to lognormal. The highest resolution simulations find γ ≃ −0.8 for the z = 0 shape of the $M_{\star ,\rm BCG}$ kernel. We provide a Gaussian mixture fit to the low-redshift Nsat kernel as well as local linear regression parameters tabulated for $M_{\rm halo}\gt 10^{13.5} \, {\rm M}_\odot$ in all simulations.