bluuebunny/crossref_metadata_2025 huggingface dataset:
Dispersion of surface-modified, aggregated, fumed silica in polymer nanocomposites
Authors: Rishi Kabir , Pallerla Lahari , Beaucage Gregory , Tang Anh
Published: May 2020

Surface modification of model silica to enhance compatibility in nanocomposites has been widely studied. In addition to model spherical silica, several authors have investigated the impact of surface conditions on compatibility in commercial aggregated carbon black and silica. In this paper, dispersion is investigated for a series of nanocomposites produced from commercially modified fumed silica mixed with styrene butadiene rubber, polystyrene, and polydimethylsiloxane. Surface modification includes variation in surface hydroxyl content, siloxane, and silane treatment. Qualitatively, hydroxyl groups on the silica surface are considered incompatible with non-polar polymers, while methyl groups are compatible with oleophilic polymers. X-ray scattering was used to analyze the filler aggregate structure before and after dispersion, and the second virial coefficient was used to quantify nanodispersion. The content of surface moieties was determined from Fourier-transform infrared spectroscopy. It is observed that modified silica can display mean field or specific interactions as reflected by the presence of a correlation peak in x-ray scattering. For systems with specific interactions, a critical ordering concentration is observed related to the free energy change for structuring. A van der Waals model was used to model the second virial coefficient as a function of accumulated strain, yielding the excluded volume and an energetic term. The excluded volume could be predicted from the structural information, and the bound polymer layer was directly related to the surface methyl content, whereas the energetic term was found to synergistically depend on both the methyl and hydroxyl surface content.
Perpendicular magnetofluid theory for magnetically confined plasmas in the collisionless limit
Authors: Zheng Linjin
Published: May 2020

Note that the magnetically confined plasmas in thermonuclear fusion turn to be collisionless. Some particles are trapped by the inhomogeneous equilibrium field or by the waves, while some others keep circulating. One cannot expect the charged particles to be collectively localized in space by collisions along the magnetic field lines. Consequently, the fluid parameters relating to the parallel motion, such as parallel fluid velocity, become inadequate. In this paper, the perpendicular magnetofluid theory for magnetically confined plasmas in the collisionless limit is developed. It revises Braginskii's transport theory by releasing the collisional dominance assumption. In the perpendicular direction, the particle spatial localization is solo resulted from the strong magnetic field, while the finite Larmor radius (FLR) effects are taken into account in the next order. In the parallel direction, the particle mobility feature is fully retained by constructing only the perpendicular moments. Therefore, besides the FLR effects till order O(k⊥2ρi2), the Landau damping, the trapped particle effects, and other parallel kinetic effects are all kept in the current formalism. Here, k⊥ is the perpendicular wave number and ρi is the ion Larmor radius. The theory can be used for both the analytical and numerical studies of magnetically confined plasmas.
Understanding the thermal stability of Ohmic contacts
Authors: Lim Alane
Published: May 2020

Using X-ray photoelectron spectroscopy, researchers uncover one way that electronics can degrade.
Modifying ablator composition can reduce hot electron generation in laser-plasma interactions
Authors: Bandari Anashe
Published: May 2020

Hot electrons are a dangerous byproduct of laser-plasma interactions, and it is important to mitigate their production to achieve direct-drive inertial confinement fusion.
Refractive index of azobenzene holds key to tunable optical microresonators
Authors: Bandari Anashe
Published: May 2020

Optical excitation of azobenzene to change its structural properties leads to small modifications in its refractive index that are amplified within a resonator.
Analytical nuclear gradients for electron-attached and electron-detached states for the second-order algebraic diagrammatic construction scheme combined with frozen-density embedding
Authors: Liu Jing , Hättig Christof , Höfener Sebastian
Published: May 2020

In the present work, we report the derivation and implementation of vertical ionization potentials (IPs) and electron affinities (EAs) for embedded wavefunction methods as well as the corresponding analytical nuclear gradients. Vertical transitions have been implemented for CIS(D∞), the second-order algebraic diagrammatic construction [ADC(2)] scheme, and the second-order approximate coupled-cluster singles and doubles method. For all methods, density fitting is applied to facilitate reduced memory and disk storage requirements. Analytical nuclear gradients have been derived and implemented for CIS(D∞) and ADC(2) both with and without frozen-density embedding (FDE). The objective of the reported method is to study the properties of organic semiconductors in which charge is transported along molecular stacks in molecular crystals. The accuracy of the implemented methods is, therefore, assessed using stacked dimers of small model systems. Albeit second-order methods can yield noticeable errors with respect to reference methods in terms of absolute IP and EA values, they show a significantly improved accuracy for the shift of the IP and EA values at different intermolecular distances relative to the monomers. Besides reducing the computational costs, the FDE ansatz introduces furthermore a significant conceptual difference as it enables control over which subsystem is ionized, allowing for the calculation of transfer integrals for the interacting (embedded) systems. The new implementation is finally applied to tetraazaperopyrenes, used as organic semiconductors, to study charge-localization and long-range polarization in particular.
A scanning nonlinear dielectric microscopic investigation of potential-induced degradation in monocrystalline silicon solar cells
Authors: Cho Yasuo , Jonai Sachiko , Masuda Atsushi
Published: May 2020

Carrier distributions in monocrystalline silicon solar cells affected by potential-induced degradation (PID) were investigated using scanning nonlinear dielectric microscopy (SNDM), employing three samples with different PID levels. These observations clearly demonstrated that reductions in the carrier density were correlated with the extent of PID. Depth profile measurements showed that the solar cells were affected by PID to a significant depth of approximately 90 μm, equal to almost half the cell thickness. This result suggests that the Na+ migration is readily induced by the application of a high voltage. Super-higher-order-SNDM was also employed to obtain a more precise analysis of the depletion layer distributions in monocrystalline silicon solar cells with and without the application of a high voltage. The data showed that the depletion layer of a sample without PID was thinner than that of a sample exhibiting PID, indicating that the carrier concentration in the former sample was higher. This finding was in good agreement with the results produced by direct quantitative dopant measurements using SNDM.
Improvements in the orbitalwise scaling down of Perdew–Zunger self-interaction correction in many-electron regions
Authors: Yamamoto Yoh , Romero Selim , Baruah Tunna , Zope Rajendra R.
Published: May 2020

The Perdew–Zunger (PZ) method provides a way to remove the self-interaction (SI) error from density functional approximations on an orbital by orbital basis. The PZ method provides significant improvements for the properties such as barrier heights or dissociation energies but results in over-correcting the properties well described by SI-uncorrected semi-local functional. One cure to rectify the over-correcting tendency is to scale down the magnitude of SI-correction of each orbital in the many-electron region. We have implemented the orbitalwise scaled down SI-correction (OSIC) scheme of Vydrov et al. [J. Chem. Phys. 124, 094108 (2006)] using the Fermi–Löwdin SI-correction method. After validating the OSIC implementation with previously reported OSIC-LSDA results, we examine its performance with the most successful non-empirical SCAN meta-GGA functional. Using different forms of scaling factors to identify one-electron regions, we assess the performance of OSIC-SCAN for a wide range of properties: total energies, ionization potentials and electron affinities for atoms, atomization energies, dissociation and reaction energies, and reaction barrier heights of molecules. Our results show that OSIC-SCAN provides superior results than the previously reported OSIC-LSDA, -PBE, and -TPSS results. Furthermore, we propose selective scaling of OSIC (SOSIC) to remove its major shortcoming that destroys the −1/r asymptotic behavior of the potentials. The SOSIC method gives the highest occupied orbital eigenvalues practically identical to those in PZSIC and unlike OSIC provides bound atomic anions even with larger powers of scaling factors. SOSIC compared to PZSIC or OSIC provides a more balanced description of total energies and barrier heights.
Understanding tunable photoresponsivity of two-dimensional multilayer phototransistors: Interplay between thickness and carrier mobility
Authors: Moon Young-Sun , Shon Ji Hoon , Kim Doyoon , Lee Kookjin , Joo Min-Kyu , Kim Gyu-Tae
Published: May 2020

Thickness-dependent bandgap and carrier mobility of two-dimensional (2D) van der Waals (vdW) layered materials make them a promising material as a phototransistor that detects light signals and converts them to electrical signals. Thus far, to achieve a high photoresponsivity of 2D materials, enormous efforts have been made via material and dielectric engineering, as well as modifying device structure. Nevertheless, understanding the effect of interplay between the thickness and the carrier mobility to photoresponsivity is little known. Here, we demonstrate the tunable photoresponsivity (R) of 2D multilayer rhenium disulfide (ReS2), which is an attractive candidate for photodetection among 2D vdW materials owing to its layer-independent direct bandgap and decoupled vdW interaction. The gate bias (VG)-dependent photocurrent generation mechanism and R are presented for the channel thickness range of 1.7–27.5 nm. The high similarity between VG-dependent photocurrent and transconductance features in the ReS2 phototransistors clearly implies the importance of the channel thickness and the operating VG bias condition. Finally, the maximum R was found to be 4.1 × 105 A/W at 14.3 nm with the highest carrier mobility of ∼15.7 cm2⋅V−1⋅s−1 among the fabricated devices after excluding the contact resistance effect. This work sheds light on the strategy of how to obtain the highest R in 2D vdW-based phototransistors.
Step flow growth of β-Ga2O3 thin films on vicinal (100) β-Ga2O3 substrates grown by MOVPE
Authors: Bin Anooz S. , Grüneberg R. , Wouters C. , Schewski R. , Albrecht M. , Fiedler A. , Irmscher K. , Galazka Z. , Miller W. , Wagner G. , Schwarzkopf J. , Popp A.
Published: May 2020

Homoepitaxial (100) β-Ga2O3 films were grown on substrates with miscut angles of 2°, 4°, and 6° toward [001¯] by metal organic vapor phase epitaxy. Step-flow growth mode, resulting in smooth film surfaces and high crystalline quality, could only be achieved if the diffusion length on the film surface corresponds approximately to the width of the terraces. Otherwise, 2D islands or step-bunching is obtained, which results in a deteriorated crystalline quality and reduced Hall mobility of the electrons. By varying the growth parameters such as the O2/Ga ratio, Ar push gas flow, and chamber pressure, the diffusion length could be adjusted so that step-flow growth mode could be achieved at all miscut angles. Furthermore, the growth rate could remarkably be increased from 1.6 nm/min to 4.3 nm/min. For homoepitaxial β-Ga2O3 films grown in step-flow growth mode, TEM measurements revealed a high crystalline quality, which is correlated with a high Hall mobility of 131 cm2/V s at a carrier concentration of 1.6 × 1017cm−3, which is comparable with β-Ga2O3 single crystal bulk values. This study clearly points out the high potential of β-Ga2O3 films for high performance MOSFETs if the influence of the deposition parameters on the structural and electrical properties is well understood.
Low-latency power-dividing clocking scheme for adiabatic quantum-flux-parametron logic
Authors: He Yuxing , Takeuchi Naoki , Yoshikawa Nobuyuki
Published: May 2020

Adiabatic quantum-flux-parametron (AQFP) logic is a highly energy-efficient superconductor logic family. Traditionally, AQFP circuits have relied on the four-phase clocking scheme, which uses a pair of ac current sources with a 90° phase difference. The operation of each logic gate thus takes a quarter clock cycle, leading to a relatively long latency for some applications. In this Letter, we propose a low-latency clocking scheme for AQFP logic based on microwave power dividers (PDs). The whole circuit is powered by a single excitation current, which is equally split for each logic stage by a serial-type PD. As a result, the latency between adjacent logic stages is determined by the transmission line length (propagation delay) inside the PD, which can be much shorter than a quarter clock cycle. Note that the low-latency performance is independent of the horizontal length of the AQFP circuit, and thus, the proposed clocking scheme is applicable to large-scale designs where a large number of gates are horizontally placed in a single stage. For validation, several numerical simulations are conducted and a six-stage AQFP test circuit is demonstrated using the proposed power-dividing clocking scheme (with a designed latency of 20 ps per gate) at a temperature of 4.2 K.
Infrared photodissociation spectroscopy and anharmonic vibrational study of the HO4+ molecular ion
Authors: Franke Peter R. , Duncan Michael A. , Douberly Gary E.
Published: May 2020

Molecular cations of HO4+ and DO4+ are produced in a supersonic expansion. They are mass-selected, and infrared photodissociation spectra of these species are measured with the aid of argon-tagging. Although previous theoretical studies have modeled these systems as proton-bound dimers of molecular oxygen, infrared spectra have free OH stretching bands, suggesting other isomeric structures. As a consequence, we undertook extensive computational studies. Our conformer search used a composite method based on an economical combination of single- and multi-reference theories. Several conformers were located on the quintet, triplet, and singlet surfaces, spanning in energy of only a few thousand wavenumbers. Most of the singlet and triplet conformers have pronounced multiconfigurational character. Previously unidentified covalent-like structures (H—O—O—O—O) on the singlet and triplet surfaces likely represent the global minima. In our experiments, HO4+ is formed in a relatively hot environment, and similar experiments have been shown capable of producing multiple conformers in low-lying electronic states. None of the predicted HO4+ isomers can be ruled out a priori based on energetic arguments. We interpret our argon-tagged spectra with Second-Order Vibrational Perturbation Theory with Resonances (VPT2+K). The presence of one or more covalent-like isomers is the only reasonable explanation for the spectral features observed.
Dynamical phase diagram of an auto-regulating gene in fast switching conditions
Authors: Jia Chen , Grima Ramon
Published: May 2020

While the steady-state behavior of stochastic gene expression with auto-regulation has been extensively studied, its time-dependent behavior has received much less attention. Here, under the assumption of fast promoter switching, we derive and solve a reduced chemical master equation for an auto-regulatory gene circuit with translational bursting and cooperative protein-gene interactions. The analytical expression for the time-dependent probability distribution of protein numbers enables a fast exploration of large swaths of the parameter space. For a unimodal initial distribution, we identify three distinct types of stochastic dynamics: (i) the protein distribution remains unimodal at all times; (ii) the protein distribution becomes bimodal at intermediate times and then reverts back to being unimodal at long times (transient bimodality); and (iii) the protein distribution switches to being bimodal at long times. For each of these, the deterministic model predicts either monostable or bistable behavior, and hence, there exist six dynamical phases in total. We investigate the relationship of the six phases to the transcription rates, the protein binding and unbinding rates, the mean protein burst size, the degree of cooperativity, the relaxation time to the steady state, the protein mean, and the type of feedback loop (positive or negative). We show that transient bimodality is a noise-induced phenomenon that occurs when the protein expression is sufficiently bursty, and we use a theory to estimate the observation time window when it is manifested.
Mulling over the mulla mullas: revisiting phosphorus hyperaccumulation in the Australian plant genus Ptilotus (Amaranthaceae)
Authors: Hammer Timothy A. , Ye Daihua , Pang Jiayin , Foster Kevin , Lambers Hans , Ryan Megan H.
Published: May 2020

Species in the Australian genus Ptilotus (Amaranthaceae) grow well in soils with both very low and very high phosphorus (P) availability; in the latter they hyperaccumulate P. However, it is not known whether this trait is common within Ptilotus, whether it is shared with other genera in the family, or whether it correlates with the wide array of morphologies and ecologies within Ptilotus. We therefore assessed P hyperaccumulation across the morphological, ecological and phylogenetic diversity of Ptilotus. Experiment 1 tested the response of 11 species to added P (0, 50 and 100 mg kg–1), including six species of Ptilotus and the Australian amaranth Gomphrena canescens R.Br. Experiment 2 tested the response of five species – three Ptilotus spp., G. canescens and Kennedia prostrata R.Br. – to added P (5 and 150 mg kg–1) and two pre-harvest P-pulse treatments (5 and 50 mg kg–1). Ptilotus species hyperaccumulated P when grown in high-P soil, but curtailed uptake from a pulse. All Ptilotus species preferentially allocated P to leaves (reaching 73 mg g–1) without development of P toxicity symptoms. Gomphrena canescens and K. prostrata preferentially allocated P to stems and roots, respectively, and suffered P toxicity. The lack of tolerance to high [P] in G. canescens suggests that the likely widespread, or universal, mechanisms for tolerance of high P by Ptilotus are not shared by amaranths. Further research will determine the mechanisms underlying the unusual P physiology of Ptilotus.
Light response of photosynthesis and stomatal conductance of rose leaves in the canopy profile: the effect of lighting on the adaxial and the abaxial sides
Authors: Paradiso Roberta , de Visser Pieter H. B. , Arena Carmen , Marcelis Leo F. M.
Published: May 2020

We investigated the light response of leaf photosynthesis, stomatal conductance and optical properties in rose plants grown in a glasshouse with bending technique. Leaves were lighted from the adaxial or the abaxial side during measurements, performed in four positions in the upright and bent shoots: top leaves, middle leaves, bottom leaves, and bent shoot leaves. Moreover, the effect of the irradiation on the adaxial or abaxial leaf side on whole canopy photosynthesis was estimated through model simulation. No significant differences were found in light transmission, reflection and absorption of leaves and in photosynthesis light response curves among the four positions. In all the leaf positions, light absorption, stomatal conductance and photosynthesis were higher when leaves were lighted from the adaxial compared with the abaxial side. The model showed that a substantial part of the light absorbed by the crop originated from light reflected from the greenhouse floor, and thus the abaxial leaf properties have impact on whole crop light absorbance and photosynthesis. Simulations were performed for crops with leaf area index (LAI) 1, 2 and 3. Simulation at LAI 1 showed the highest reduction of simulated crop photosynthesis considering abaxial properties; however, to a lesser extent photosynthesis was also reduced at LAI 2 and 3. The overall results showed that the model may be helpful in designing crop systems for improved light utilisation by changing lamp position or level of leaf bending and pruning.
Sensitive magnetometry reveals inhomogeneities in charge storage and weak transient internal currents in Li-ion cells
Authors: Hu Yinan , Iwata Geoffrey Z. , Mohammadi Mohaddese , Silletta Emilia V. , Wickenbrock Arne , Blanchard John W. , Budker Dmitry , Jerschow Alexej
Published: May 2020

The ever-increasing demand for high-capacity rechargeable batteries highlights the need for sensitive and accurate diagnostic technology for determining the state of a cell, for identifying and localizing defects, and for sensing capacity loss mechanisms. Here, we leverage atomic magnetometry to map the weak induced magnetic fields around Li-ion battery cells in a magnetically shielded environment. The ability to rapidly measure cells nondestructively allows testing even commercial cells in their actual operating conditions, as a function of state of charge. These measurements provide maps of the magnetic susceptibility of the cell, which follow trends characteristic for the battery materials under study upon discharge. In particular, hot spots of charge storage are identified. In addition, the measurements reveal the capability to measure transient internal current effects, at a level of μA, which are shown to be dependent upon the state of charge. These effects highlight noncontact battery characterization opportunities. The diagnostic power of this technique could be used for the assessment of cells in research, quality control, or during operation, and could help uncover details of charge storage and failure processes in cells.
Cell entry mechanisms of SARS-CoV-2
Authors: Shang Jian , Wan Yushun , Luo Chuming , Ye Gang , Geng Qibin , Auerbach Ashley , Li Fang
Published: May 2020

Significance

A key to curbing SARS-CoV-2 is to understand how it enters cells. SARS-CoV-2 and SARS-CoV both use human ACE2 as entry receptor and human proteases as entry activators. Using biochemical and pseudovirus entry assays and SARS-CoV as a comparison, we have identified key cell entry mechanisms of SARS-CoV-2 that potentially contribute to the immune evasion, cell infectivity, and wide spread of the virus. This study also clarifies conflicting reports from recent studies on cell entry of SARS-CoV-2. Finally, by highlighting the potency and the evasiveness of SARS-CoV-2, the study provides insight into intervention strategies that target its cell entry mechanisms.
Marked themes in spoken Chinese: a discourse semantics perspective
Authors: Gao Yanmei , Lyu Guoyan
Published: May 2020

This paper focuses on Marked Theme in spoken Chinese. Previous studies have explored the functions of Marked Themes within clauses, but not many researchers have observed this phenomenon from a discourse semantics perspective. Combining the framework of discourse semantics with the use of corpus study, this paper first explores the occurrence of such structures in conversations and then examines their discourse functions. Data from the corpus show that, in line with findings from corpus studies of written texts, the occurrence of Marked Themes is quite low. The inspection of their discourse functions leads to the following preliminary findings: (1) in sequences of activities, Marked Themes often function as lexical cohesive devices to build up taxonomical relations across utterances; (2) from the view point of identification, Marked Themes function as anaphoric devices to help keep track of the Participants in question; (3) from the viewpoint of periodicity, while most Marked Themes convey given information, especially contrastive information, a considerable amount of Marked Themes function as HyperTheme to start new phases of discourse.
A numerical model to introduce students to AC loss calculation in superconductors
Authors: Grilli Francesco , Rizzo Enrico
Published: May 2020

A numerical model implemented in the open-source finite-element method FreeFEM program is presented, with the aim of introducing students to the calculation of AC losses in superconductors. With this simple approach, students can learn about the critical state model used to describe the macroscopic electromagnetic behavior of superconductors and the importance of different factors influencing the AC losses of superconductors.
Contribution of nano-SiC/epoxy coating with nonlinear conduction characteristics to surface charge accumulation under DC voltage
Authors: Pan Zijun , Tang Ju , Pan Cheng , Luo Yi , Liu Qinyi , He Huasuan
Published: May 2020

In order to suppress surface charge accumulation, a nano-SiC/epoxy composite with nonlinear conduction characteristic was employed to coat a pure epoxy substrate in this paper. Surface potential distributions on the insulator were measured after being charged by a pair of finger-shaped electrodes (one was powered at −10 kV, and the other was grounded). For the insulators with and without coating, there were mainly positive potentials on the whole surface, and the area with higher potential located near the high voltage electrode. As the charging time increased, the high potential area began to shrink, indicating a possible charge migration. When the charging time exceeded 60 min, the potential distribution was almost kept unchanged. Compared with the pure epoxy substrate, the amount of surface charges had a slight increment after being coated with 3 wt% nano-particles. The accumulated surface charges were progressively reduced when the content of fillers became higher. Especially for the samples with 7 wt% and 10 wt% ingredients, there was a sharp decrease of accumulated surface charges in the distributed area and magnitude from 40 to 60 min. In terms of surface trapping characteristics and nonlinear conduction of the composite, the effect of coating on the surface charge accumulation was discussed.
Planar microwave retroreflector based on transmissive gradient index metasurface
Authors: Liu Yong-Qiang , Li Sheng , Guo Jie , Li Liangsheng , Yin Hongcheng
Published: May 2020

In this paper, a novel planar microwave retroreflector based on a transmissive gradient metasurface combined with a curved metal mirror is proposed and demonstrated. The transmissive metasurface can efficiently converge a wide-angle incident wave to a pre-designed curved metal mirror behind it with a proper distance, which acts as an effective reflective surface that can greatly enhance the backscattering of the incident wave with a wide-angle view. According to the full-wave simulations, the proposed metasurface retroreflector can perform an excellent retroreflective effect for incident microwaves of angle view between −30° and 30° range. A prototype was fabricated and the experimental results verify that the metasurface retroreflector can realize the monostatic radar cross section (RCS) enhancement with a continuous wide incident angle view from −30° to 30° at 10 GHz within a stable 3 dB RCS level. It is further demonstrated that the excellent wide-angle backscattering performance (absolute RCS enhancement value, operational bandwidth and/or incident angle view) of the proposed microwave metasurface retroreflector is competitive against the traditional trihedral corner reflector with comparable dimensions, thus opening up new possibilities to substitute the traditional bulky radar retroreflector by using a planar compact metasurface structure for microwave engineering. The presented microwave metasurface retroreflector is promising to develop into a low-profile, light weight and planar radar retroreflector which possesses tremendous RCS backscattering enhancement and wide-angle view operation range.
Environmental monitoring and disease detection of plants in smart greenhouse using internet of things
Authors: Khan Fazeel Ahmed , Ibrahim Adamu Abubakar , M Zeki Akram
Published: May 2020

This research implements the idea of automation using Internet of Things (IoT) in a greenhouse environment. The development is focuses on deployment of agicultural greenhouses into small-scale level transforming it into a smart greenhouse. They are to help in monitoring the greenhouse environment conditions, water irrigation management, image collection using installed cameras as well as predicting diseases in the plants on collected leaf datasets. This research focus on development for the purpose of validating a proposed system design and architecture for a suitable IoT based monitoring for environment conditions, managing water irrigation system and a effective method for detecting leaf diseases on the plants inside a greenhouse environment.
Forces between kinks in ϕ8 theory
Authors: d’Ornellas Peru
Published: May 2020

We investigate the dynamics of the kinks that emerge in a one-dimensional scalar field theory with an octic potential containing a quartic minimum and two quadratic minima. We show analytically that kink-antikink and kink-kink pairs interact with a force that scales with the fourth power of the inter-kink distance, and calculate its strength. This is done using two different techniques. The first employs a collective coordinate method to approximately solve the equation of motion for the profile of an accelerating kink. The second is based on modifying the potential to one that is able to support static solutions containing multiple kinks. We show that the two methods give consistent results. All calculations are supported by numerical work that confirms the validity of our results.
Implementation of a pharmacist-led transitional care clinic
Authors: Layman Sara N , Elliott Whitney V , Regen Sloan M , Keough Leigh Anne
Published: May 2020

Purpose

To describe a pharmacist-led transitional care clinic (TCC) for high-risk patients who were recently hospitalized or seen in the emergency department (ED).

The Memphis Veterans Affairs Medical Center (VAMC) established a pharmacist-led face-to-face and telephone follow-up TCC to improve posthospitalization follow-up care through medication optimization and disease state management, particularly for veterans with high-risk disease states such as chronic obstructive pulmonary disease (COPD) and heart failure (HF). The clinic’s clinical pharmacy specialists (CPSs) ordered diagnostic and laboratory tests, performed physical assessments, and consulted other providers and specialty services in addition to performing medication reconciliation, compliance assessment, and evaluation of adverse drug events. TCC patients were typically seen within 2 weeks of discharge and subsequently referred back to their primary care provider or a specialty care provider for continued management. A retrospective review of 2016 TCC data found that 7.8% of patients seen in the TCC were readmitted within 30 days of discharge; readmission rates for COPD and HF were reduced to 13% and 10%, respectively, compared to hospital-wide readmission rates of 17% and 24%. A separate observational analysis found that 30-day readmissions for COPD and HF were reduced in TCC patients, with pharmacists documenting an average of 6.2 interventions and 3.3 medication-related problems per patient. To reduce clinic appointment no-shows, the CPSs worked with inpatient providers and schedulers to emphasize to patients the importance of clinic attendance; also, TCC services were expanded to include telehealth appointments to increase access for rural and/or homebound patients.

Conclusion

A pharmacist-led TCC effectively reduced readmissions and prevented medication-related problems for high-risk patients who were hospitalized or seen in the ED.
V-Mango: a functional–structural model of mango tree growth, development and fruit production
Authors: Boudon Frédéric , Persello Séverine , Jestin Alexandra , Briand Anne-Sarah , Grechi Isabelle , Fernique Pierre , Guédon Yann , Léchaudel Mathieu , Lauri Pierre-Éric , Normand Frédéric
Published: May 2020

Background and Aims

Mango (Mangifera indica L.) is the fifth most widely produced fruit in the world. Its cultivation, mainly in tropical and sub-tropical regions, raises a number of issues such as the irregular fruit production across years, phenological asynchronisms that lead to long periods of pest and disease susceptibility, and the heterogeneity of fruit quality and maturity at harvest. To address these issues, we developed an integrative functional–structural plant model that synthesizes knowledge about the vegetative and reproductive development of the mango tree and opens up the possible simulation of cultivation practices.

Methods

We designed a model of architectural development in order to precisely characterize the intricate developmental processes of the mango tree. The appearance of botanical entities was decomposed into elementary stochastic events describing occurrence, intensity and timing of development. These events were determined by structural (position and fate of botanical entities) and temporal (appearance dates) factors. Daily growth and development of growth units and inflorescences were modelled using empirical distributions and thermal time. Fruit growth was determined using an ecophysiological model that simulated carbon- and water-related processes at the fruiting branch scale.

Key Results

The model simulates the dynamics of the population of growth units, inflorescences and fruits at the tree scale during a growing cycle. Modelling the effects of structural and temporal factors makes it possible to simulate satisfactorily the complex interplays between vegetative and reproductive development. The model allowed the characterization of the susceptibility of mango tree to pests and the investigatation of the influence of tree architecture on fruit growth.

Conclusions

This integrative functional–structural model simulates mango tree vegetative and reproductive development over successive growing cycles, allowing a precise characterization of tree phenology and fruit growth and production. The next step is to integrate the effects of cultivation practices, such as pruning, into the model.
A willow drawing from 1786: the earliest depiction of intraspecific trait variation in plants?
Authors: Stegmann Ulrich E
Published: May 2020

Background and Aims

The study of intraspecific trait variation (ITV) in plants has a long history, dating back to the fourth century BC. Its existence was widely acknowledged by the end of the 18th century, although systematic and experimental studies commenced only a century later. However, the historiography of ITV has many gaps, especially with regard to early observations and visual documents. This note identifies an early depiction of plant ITV.

Methods

The botanical works of Johann Wolfgang von Goethe (1749–1832), a German writer and naturalist, were subjected to close reading. This included all publications and unpublished sources related to botany between 1785 and 1832 (e.g. notes, drafts, diaries, letters, drawings). This material is accessible in the multi-volume historical-critical edition of Goethe’s studies in natural science (Leopoldina-Ausgabe).

Key Results

A diary entry from 9 September 1786 described changes in leaf morphology along an elevation gradient in the Bavarian Alps. The leaves of an unidentified species of willow (Spix sp.) and gentian (Gentiana sp.) were said to become narrower with increasing elevation; leaves also stood further apart on twigs, and the latter became thinner. A crude drawing of two willow twigs illustrated the differences. Goethe conjectured that the differences were due to environmental conditions.

Conclusions

Goethe’s notes were anecdotal, and it is unclear whether the observed plant individuals actually belonged to the same species. Nevertheless, the notes represent an early and clear articulation of the hypothesis that changes in environmental conditions can cause ITV in a natural plant population. The drawing may be the earliest visual record of environmentally caused plant ITV in the wild.
The locality dilemma of Sankoff-like RNA alignments
Authors: Müller Teresa , Miladi Milad , Hutter Frank , Hofacker Ivo , Will Sebastian , Backofen Rolf
Published: May 2020

Motivation

Elucidating the functions of non-coding RNAs by homology has been strongly limited due to fundamental computational and modeling issues. While existing simultaneous alignment and folding (SA&F) algorithms successfully align homologous RNAs with precisely known boundaries (global SA&F), the more pressing problem of identifying new classes of homologous RNAs in the genome (local SA&F) is intrinsically more difficult and much less understood. Typically, the length of local alignments is strongly overestimated and alignment boundaries are dramatically mispredicted. We hypothesize that local SA&F approaches are compromised this way due to a score bias, which is caused by the contribution of RNA structure similarity to their overall alignment score.

Results

In the light of this hypothesis, we study pairwise local SA&F for the first time systematically—based on a novel local RNA alignment benchmark set and quality measure. First, we vary the relative influence of structure similarity compared to sequence similarity. Putting more emphasis on the structure component leads to overestimating the length of local alignments. This clearly shows the bias of current scores and strongly hints at the structure component as its origin. Second, we study the interplay of several important scoring parameters by learning parameters for local and global SA&F. The divergence of these optimized parameter sets underlines the fundamental obstacles for local SA&F. Third, by introducing a position-wise correction term in local SA&F, we constructively solve its principal issues.

Availability and implementation

The benchmark data, detailed results and scripts are available at https://github.com/BackofenLab/local_alignment. The RNA alignment tool LocARNA, including the modifications proposed in this work, is available at https://github.com/s-will/LocARNA/releases/tag/v2.0.0RC6.

Supplementary information

Supplementary data are available at Bioinformatics online.
Karyotype evolution and flexible (conventional versus inverted) meiosis in insects with holocentric chromosomes: a case study based onPolyommatusbutterflies
Authors: Lukhtanov Vladimir A , Dantchenko Alexander V , Khakimov Fayzali R , Sharafutdinov Damir , Pazhenkova Elena A
Published: May 2020

The Polyommatus butterflies have holocentric chromosomes, which are characterized by kinetic activity distributed along the entire chromosome length, and the highest range of haploid chromosome numbers (n) known within a single eukaryotic genus (from n = 10 to n = 226). Previous analyses have shown that these numbers most likely evolved gradually from an ancestral karyotype, in accordance with the Brownian motion model of chromosome change accumulation. Here we studied chromosome sets within a monophyletic group of previously non-karyotyped Polyommatus species. We demonstrate that these species have a limited interspecific chromosome number variation from n = 16 to n = 25, which is consistent with the Brownian motion model prediction. We also found intra- and interpopulation variation in the chromosome numbers. These findings support the model of karyotype evolution through the gradual accumulation of neutral or weakly underdominant rearrangements that can persist in the heterozygous state within a population. For Polyommatus poseidonides we report the phenomenon of flexible meiosis in which the chromosome multivalents are able to undergo either conventional or inverted meiosis within the same individual. We hypothesise that the ability to invert the order of the meiotic events may be adaptive and can facilitate proper chromosome segregation in chromosomal heterozygotes, thus promoting rapid karyotype evolution.
Reduced Thalamus Volume and Enhanced Thalamus and Fronto-Parietal Network Integration in the Chess Experts
Authors: Wang Yanpei , Zuo Chenyi , Wang Daoyang , Tao Sha , Hao Lei
Published: May 2020

The ability of chess experts depends to a large extent on spatial visual processing, attention, and working memory, all of which are thought to be mediated by the thalamus. This study explored whether continued practice and rehearsal over a long period of time results in structural changes in the thalamic region. We found smaller gray matter volume regions in the thalami of expert Chinese chess players in comparison with novice players. We then used these regions as seeds for resting-state functional connectivity analysis and observed significantly strengthened integration between the thalamus and fronto-parietal network in expert Chinese chess players. This strengthened integration that includes a group of brain regions showing an increase in activation to external stimulation, particularly during tasks relying on working memory and attention. Our findings demonstrate structural changes in the thalamus caused by a wide range of engagement in chess problem solving, and that this strengthened functional integration with widely distributed circuitry better supports high-level cognitive control of behavior.
Loss of SIRT1 in diabetes accelerates DNA damage-induced vascular calcification
Authors: Bartoli-Leonard Francesca , Wilkinson Fiona L , Schiro Andrew , Serracino Inglott Ferdinand , Alexander M Yvonne , Weston Ria
Published: May 2020

Aims

Vascular calcification is a recognized predictor of cardiovascular risk in the diabetic patient, with DNA damage and accelerated senescence linked to oxidative stress-associated pathological calcification. Having previously shown that systemic SIRT1 is reduced in diabetes, the aim was to establish whether SIRT1 is protective against a DNA damage-induced senescent and calcified phenotype in diabetic vascular smooth muscle cells (vSMCs).

Methods and results

Immunohistochemistry revealed decreased SIRT1 and increased DNA damage marker expression in diabetic calcified arteries compared to non-diabetic and non-calcified controls, strengthened by findings that vSMCs isolated from diabetic patients show elevated DNA damage and senescence, assessed by the Comet assay and telomere length. Hyperglycaemic conditions were used and induced DNA damage and enhanced senescence in vSMCs in vitro. Using H2O2 as a model of oxidative stress-induced DNA damage, pharmacological activation of SIRT1 reduced H2O2 DNA damage-induced calcification, prevented not only DNA damage, as shown by reduced comet tail length, but also decreased yH2AX foci formation, and attenuated calcification. While Ataxia Telanglectasia Mutated (ATM) expression was reduced following DNA damage, in contrast, SIRT1 activation significantly increased ATM expression, phosphorylating both MRE11 and NBS1, thus allowing formation of the MRN complex and increasing activation of the DNA repair pathway.

Conclusion

DNA damage-induced calcification is accelerated within a diabetic environment and can be attenuated in vitro by SIRT1 activation. This occurs through enhancement of the MRN repair complex within vSMCs and has therapeutic potential within the diabetic patient.
EAPCI Position Statement on Invasive Management of Acute Coronary Syndromes during the COVID-19 pandemic
Authors: Chieffo Alaide , Stefanini Giulio G , Price Susanna , Barbato Emanuele , Tarantini Giuseppe , Karam Nicole , Moreno Raul , Buchanan Gill Louise , Gilard Martine , Halvorsen Sigrun , Huber Kurt , James Stefan , Neumann Franz-Josef , Möllmann Helge , Roffi Marco , Tavazzi Guido , Mauri Ferré Josepa , Windecker Stephan , Dudek Dariusz , Baumbach Andreas
Published: May 2020

The coronavirus disease 2019 (COVID-19) pandemic poses an unprecedented challenge to healthcare worldwide. The infection can be life threatening and require intensive care treatment. The transmission of the disease poses a risk to both patients and healthcare workers. The number of patients requiring hospital admission and intensive care may overwhelm health systems and negatively affect standard care for patients presenting with conditions needing emergency interventions. This position statements aims to assist cardiologists in the invasive management of acute coronary syndrome (ACS) patients in the context of the COVID-19 pandemic. To that end, we assembled a panel of interventional cardiologists and acute cardiac care specialists appointed by the European Association of Percutaneous Cardiovascular Interventions (EAPCI) and from the Acute Cardiovascular Care Association (ACVC) and included the experience from the first and worst affected areas in Europe. Modified diagnostic and treatment algorithms are proposed to adapt evidence-based protocols for this unprecedented challenge. Various clinical scenarios, as well as management algorithms for patients with a diagnosed or suspected COVID-19 infection, presenting with ST- and non-ST-segment elevation ACS are described. In addition, we address the need for re-organization of ACS networks, with redistribution of hub and spoke hospitals, as well as for in-hospital reorganization of emergency rooms and cardiac units, with examples coming from multiple European countries. Furthermore, we provide a guidance to reorganization of catheterization laboratories and, importantly, measures for protection of healthcare providers involved with invasive procedures.
Characteristics and outcomes of patients hospitalized for COVID-19 and cardiac disease in Northern Italy
Authors: Inciardi Riccardo M , Adamo Marianna , Lupi Laura , Cani Dario S , Di Pasquale Mattia , Tomasoni Daniela , Italia Leonardo , Zaccone Gregorio , Tedino Chiara , Fabbricatore Davide , Curnis Antonio , Faggiano Pompilio , Gorga Elio , Lombardi Carlo M , Milesi Giuseppe , Vizzardi Enrico , Volpini Marco , Nodari Savina , Specchia Claudia , Maroldi Roberto , Bezzi Michela , Metra Marco
Published: May 2020

Aims

To compare demographic characteristics, clinical presentation, and outcomes of patients with and without concomitant cardiac disease, hospitalized for COVID-19 in Brescia, Lombardy, Italy.

Methods and results

The study population includes 99 consecutive patients with COVID-19 pneumonia admitted to our hospital between 4 March and 25 March 2020. Fifty-three patients with a history of cardiac disease were compared with 46 without cardiac disease. Among cardiac patients, 40% had a history of heart failure, 36% had atrial fibrillation, and 30% had coronary artery disease. Mean age was 67 ± 12 years, and 80 (81%) patients were males. No differences were found between cardiac and non-cardiac patients except for higher values of serum creatinine, N-terminal probrain natriuretic peptide, and high sensitivity troponin T in cardiac patients. During hospitalization, 26% patients died, 15% developed thrombo-embolic events, 19% had acute respiratory distress syndrome, and 6% had septic shock. Mortality was higher in patients with cardiac disease compared with the others (36% vs. 15%, log-rank P = 0.019; relative risk 2.35; 95% confidence interval 1.08–5.09). The rate of thrombo-embolic events and septic shock during the hospitalization was also higher in cardiac patients (23% vs. 6% and 11% vs. 0%, respectively).

Conclusions

Hospitalized patients with concomitant cardiac disease and COVID-19 have an extremely poor prognosis compared with subjects without a history of cardiac disease, with higher mortality, thrombo-embolic events, and septic shock rates.