bluuebunny/crossref_metadata_2025 huggingface dataset:
Development of a New Burner Device Based on Injection-Radiation Method for Gas Fuel Combustion
Authors: Sinitsyn A. A. , Nikiforov O. Y. , Akhmetov Timur , Karpov D. F.
Published: July 2020

This paper presents the results of designing a promising burner device that combines injection and radiation methods for gaseous fuel combustion. Infrared radiation from the heated surface of nozzle of radiation burner provides intensive heat transfer in furnaces and boilers, specifies their high efficiency at low flue gas temperatures, and very low NOx emissions. Effective gas combustion is facilitated by additional heating of the initial fuel mixture during filtration through the hot walls of porous nozzle. The new design of radiation burner has high performance characteristics, provides effective combustion of gaseous fuel up to 99% and meets high environmental standards and requirements.
Analysis of influence of external atmospheric factors on the accuracy of fault location on overhead power lines
Authors: Ahmedova Olga , Soshinov Anatoliy , Shevchenko Natalia
Published: July 2020

Devices of fault location are widespread in electrical grids. In overhead power lines of voltages of 10 kV and higher, such devices are based on measurements of parameters in emergency mode. These devices can be divided into two main groups: designed to determine fault location of short circuits and of ground short circuit. In both cases, when detecting fault location, analyzed are not only the current and voltage parameters at the accident time, but also the parameters of overhead power line. When analyzing equivalent circuits of power lines, approximate tabular values of direct and quadrature parameters are used. It was revealed, that the line parameters are significantly affected by external atmospheric factors: ambient temperature, soil moisture, wind strength and direction, ice formation, etc. To accurately determine the fault location, it is necessary to evaluate the influence of these factors on the linear parameters of the overhead line. The paper presents analysis of the influence of changes in atmospheric factors on parameters of overhead power line. A methodology for calculating the operation setpoints of the device for fault location in power line is given.
Analysis of the global energy resource market
Authors: Volotkovskaya Yulia , Volotkovskaya Natalya , Semenov Alexander , Semkova Anastasia , Fedorov Oleg , Vladimirov Oleg
Published: July 2020

The paper analyses the global demand for various energy resources in recent years. Nowadays, qualitative and quantitative changes in structure of distribution and consumption of energy resources take place. The paper has reviewed a number of papers predicting two-fold increase in the global energy production market by 2040. A number of other papers also predict the shift of energy demand from the USA and EU countries to the Asian market. The paper presents percentage distribution of world’s energy requirements satisfied by the six types of resources among which oil, gas, and coil are still predominant. Some papers have stated that the demand for natural gas will continue to grow faster than the demand for oil or coil in the future. To confirm or deny this theory the authors have designed the mathematical model showing trends in demand for gas compared to the total demand for oil and coal; as a result, two different polynomial functions have been obtained with almost the same probability confirming this prediction. Trends in energy production and change of global energy demand across regions over the past twenty years have been studied. The studies show that, in general, energy production has been increased for the last decade. However, due to economic crises fluctuations, energy production in EU countries has abruptly decreased; it results in displacement of the EU countries from the market by the countries of the Middle East and the Near East. The paper also notes such important factors as decrease in solid fuel production in Great Britain; steady increasing importance of renewable energy sources for the last few years; reducing of the rate of nuclear energy development by some key countries; general lack of energy recourses in EU countries, etc.
Modeling Operation of Liquid Metal Fuses When Breaking Overcurrents
Authors: Kuznetsov A V , Aleksandrov D S , Yurenkov Y P
Published: July 2020

This paper shows that successful switching of extremely high short-circuit currents I> 50 kA can be achieved by joint operation of a liquid-metal self-resetting current limiter and a circuit breaker connected in series. The type NFU-225 device from Mitsubishi was taken as an example. The time-current characteristic of joint operation of a liquid-metal self-resetting current-limiting device and a circuit breaker was compiled. However, further in the article physical processes occurring in a liquid-metal self-resetting current limiter with a complete transformation of fusible unit are considered. The result of work is modelling of operation of liquid-metal fuses when overcurrents are switched off based on the pilot studies obtained by the Japanese scientists. It is proposed to simulate the break process not at every time moment, but at specific time moments (reference points). At other time moments, current and voltage should be considered as approximately linearly changing characteristics. The work of current limiter can be represented by three stages: the pre-arc, the main arc and the final arc. If the current density is less than 1000 A/mm2, then the pre-arc operation stage of the current limiter includes the following sections for heating the fusible unit: primary heating to the melting temperature; melting and its transition to liquid state; secondary heating to evaporation temperature; evaporation of fusible unit.
Steam reheater with helical tube bundle for wet steam turbine
Authors: Egorov Mikle , Ivanov Alexander , Kovalenko Ivan , Krectunova Irina , Litvinova Nadezhda , Popova Elena
Published: July 2020

Since steam heat exchangers, used at steam cycle of Russian nuclear power stations, were designed while the knowledge about the separation and the heat exchange processes was limited, deviations between its empirical and theoretical characteristics occur. This limitation also determined application of heating pipes with simple straight shape rather than curved. This study explores a steam heat exchanger with helical heating pipes. It was shown that the model may work stably within the range of parameters, simulating work conditions of the moisture separator and steam reheater at Leningrad nuclear power plant. The experiment included processing of pure water steam as well as mixture of steam and nitrogen. It was obtained a relationship between empirical the heat transfer coefficient and the steam mass flow rate. It was noted that presence of incondensable gas does not affect significantly the heat transfer from the coils, processing high pressure steam.
Increasing the productivity of a plant for moisture evaporation from oil sludge by application of efficient method for technological parameters calculation
Authors: Surikova Alisa , Sytsyanko Elena , Solov’eva Ekaterina , Mukhametova Liliya
Published: July 2020

The paper presents the method of heat calculation of recovery stages for the plant of moisture evaporation from oil sludge. It enables to increase the plant power and reduce fuel consumption per one unit of evaporated moisture in heating boiler.
Optimization of transversal flow stress and strain and weld seam microstructure analysis in butt-HDPE friction stir welded plates
Authors: Hamrouni Khaled , Rezgui Mohamed-Ali , Trabelsi Ali , Kiss Zoltan , Nasri Rachid
Published: July 2020

The paper aims to optimize the characteristic performances of friction stir welding of high-density polyethylene in order to predict failure modes in weld nugget and interfacial zones. Three replicates of a face central composite design are employed to estimate the effects of parameters process, on the transversal flow stress and strain of the seam and to understand root causes, which may lead to structural defects such as the onset of cracks and the seam-base metal rupture. The study findings disclose that maximum responses are obtained when the tool rotation speed is set middle and both the feed rate and the plunged surface are set high. The transversal flow stress of the welded seam is found highly sensitive to the plunged surfaces and at a lesser degree to the rotation speed, whereas, the transversal flow strain of the welded seam is mostly sensitive to the rotation speed and at a lesser degree to the plunged surfaces. For the microscopic analysis, it is shown that at low rotation speed, there exist four structural layers in the transition zone between the seam and the base material giving rise to the formation of a continuous line of cracks that can initiate structure failure.
Hypertriglyzeridämie
Authors: Merkel Martin
Published: July 2020

Eine Erhöhung der Triglyzeride ist ein häufiger Befund. Die klinische Bedeutung einer leichten bzw. moderaten Hypertriglyzeridämie besteht in einer Erhöhung des kardiovaskulären Risikos. Neben Diät, Lebensstilmaßnahmen und der Behandlung ursächlicher Krankheiten wie Diabetes mellitus oder Hypothyreose ist die wichtigste therapeutische Maßnahme eine kardiovaskuläre Risikoreduktion. Dies erfolgt durch zielwertgerechte Senkung des LDL-Cholesterins bzw. des Non-HDL-Cholesterins unter Einsatz von Statinen, Ezetimib und gegebenenfalls PCSK9-Senkern. Fibrate und Omega-3-Fettsäuren spielen keine signifikante Rolle. Das klinische Risiko einer schweren Hypertriglyzeridämie über 880 mg/dl bzw. 10 mmol/l und des familiären Chylomikronämiesyndroms besteht wiederum in einer akuten Pankreatitis. Zusätzlich zu Diät und Lebensstilmaßnahmen kommen insbesondere beim familiären Chylomikronämiesyndrom der Fettersatz durch MCT-Fette und ggf. eine Medikation mit dem Antisense-Oligonukleotid
Volanesorsen zur Anwendung.
The Flipped Classroom: An Innovative Approach to Medical Education in Ophthalmology
Authors: Alabiad Chris R. , Moore Kevin J. , Green David P. , Kofoed Matthew , Mechaber Alex J. , Karp Carol L.
Published: July 2020

Objective The aim of the study is to report the creation of a flipped ophthalmology course and preclinical medical student perceptions and knowledge gains before and after a flipped ophthalmology course.

Design  The form of the study discussed is an observational study.

Subjects The subjects involved in the study are second-year (U.S.) United States medical students at the University of Miami, Miller School of Medicine (n = 401).

Methods Second-year medical students participated in a 1-week “flipped classroom” ophthalmology course geared toward primary care providers at the University of Miami, Miller School of Medicine. Eleven hours of traditional classroom lectures were condensed into 4.5 hours of short videos with self-assessment quizzes, small group discussions, and a large group case-based discussion. Fifty-seven short videos (<9 minutes) focused on major ophthalmology topics and common conditions were viewed by the students at their leisure. Students completed a pre- and post-course evaluation on their perceptions and opinions of the flipped classroom approach. Final exam scores in the flipped classroom cohort were compared with the final exam scores in the traditional didactic format used in years prior.

Main Outcome Measures The main outcome measures include: student final exam performance; student satisfaction, opinions, and perceptions.

Results Over the course of 2 years, 401 second-year U.S. medical students participated in the flipped classroom ophthalmology course. The majority of students enjoyed the flipped classroom experience (75.3%) and expressed interest in using the approach for future lessons (74.6%). The flipped classroom videos were preferred to live lectures (61.2%). Over 90% of students stated the self-assessment quizzes were useful, 79% reported that the small group discussions were an effective way to apply knowledge, and 76% cited the large group case-based discussion as useful. Pre-course knowledge assessment scores averaged 48%. Final examination scores in the flipped group (average ± standard deviation [SD] = 92.1% ± 6.1) were comparable to that of the traditional group when evaluating identical questions (average ± SD = 91.7% ± 5.54), p = 0.34.

Conclusion The flipped classroom approach proved to be a well-received and successful approach to preclinical medical education for ophthalmology. This was achieved using 35% less course time than our traditional course. This innovative approach has potential for expansion to other medical schools, medical education abroad, and for other medical school modules.
Hippocrates transformed: crafting a Hippocratic discourse of medical semiotics in English, 1850–1930
Authors: Karimullah Kamran I.
Published: July 2020

This study presents a methodology for adapting corpus linguistics to the genealogical analysis of translation’s role in the evolution of medical concepts. This methodology is exhibited by means of a case study that draws on a number of corpora to explore how two English translators—Francis Adams, a Scottish physician, and Williams H.S. Jones, a Cambridge philologist, classicist and ancient historian—translated a set of terms in Hippocratic medical texts that refer to how the body reveals illness. Drawing on the Genealogies of Knowledge subcorpora of ancient Greek and modern English, it examines some of the ways in which translation contributes to the creation of a Hippocratic semiotic discourse in English whose lexical features differ from those attested to in the subcorpus of Greek Hippocratic texts. A comparative analysis of keyword frequency and collocations of Greek semiotic terms such assēmeion, and English terms such assignandsymptomreveals the different translation strategies Jones and Adams used to translate the text. The result of this process is a Hippocratic semiotic discourse in English whose lexical features do not reflect those in the Hippocratic texts in a straightforward way.
Too bored to bother? Boredom as a potential threat to the efficacy of pandemic containment measures
Authors: Martarelli Corinna S. , Wolff Wanja
Published: July 2020

Coronavirus disease 2019 (COVID-19) caused by coronavirus (SARS-nCoV2) is currently spreading across the world. In response, different sets of pandemic containment measures have been employed by several countries. The effectiveness of non-pharmacological measures such as home confinement hinges on adherence by the population. While adherence to these social distancing measures appears to be high in general, adherence might be more challenging for some individuals and complying with these measures might become more difficult the longer they last. Here, we suggest that boredom and self-control are two important psychological concepts for understanding the challenges the COVID-19 pandemic containment measures pose to individuals. To maximize adherence to these measures, we propose to consider the specific and combined effects of boredom and self-control demands elicited by this situation on subsequent behavior.
A machine learning model to predict molecular dipole moments
Authors: Kim Meeri
Published: July 2020

The model achieves highly accurate results compared to the current state of the art for predicting dipole moments at a fraction of the computational cost.
Cascaded pyroelectric conversion: Optimizing the ferroelectric phase transition and electrical losses
Authors: Smith A. N. , Hanrahan B. M.
Published: July 2020

The dramatic increase in the pyroelectric coefficient around the ferroelectric–paraelectric phase transition suggests high potential energy conversion efficiencies, but the reality is more complicated when thermal and electrical losses are considered. The performance of prototype mono-domain lead titanate thin films is simulated around phase transition using a phenomenological modeling approach. Thermodynamic properties are calculated using a modified Landau–Devonshire potential that is a function of temperature, applied electric field, and uniaxial tensile stress for bulk films. Significant performance enhancement near the ferroelectric–paraelectric phase transition is observed. However, increases in both the specific heat and the dielectric constant reduced the anticipated improvement. Critically, electrical losses during charging and discharging processes within the energy conversion cycle are included and calculated using the dielectric dissipation factor. Cascaded pyroelectric conversion cycles are considered where heat for each subsequent stage is provided by the previous stage, allowing for the segmentation of large temperature changes into multiple cycles. The implementation of a multi-stage or cascade approach could greatly increase the cycle efficiency over a large temperature range while utilizing lower, more realistic, electric field strengths. We show how each stage could be optimized through a secondary multi-caloric effect where the ferroelectric–paraelectric transition temperature is shifted using an applied biaxial stress. Loss tangents as low as 5% are shown to negate the benefits of cascading for high number of stages (n > 10). Using a stress-tuned optimum phase transition temperature for cascade stages provides roughly a 100% increase in thermal efficiency vs the unoptimized material for low electric field cycles.
Collisionless ion modeling in Hall thrusters: Analytical axial velocity distribution function and heat flux closures
Authors: Boccelli S. , Charoy T. , Alvarez Laguna A. , Chabert P. , Bourdon A. , Magin T. E.
Published: July 2020

The genesis of the ion axial velocity distribution function (VDF) is analyzed for collisionless Hall thruster discharges. An analytical form for the VDF is obtained from the Vlasov equation, by applying the Tonks–Langmuir theory in the thruster channel, under the simplifying assumptions of monoenergetic creation of ions and steady state. The equivalent set of 1D unsteady anisotropic moment equations is derived from the Vlasov equation, and simple phenomenological closures are formulated, assuming a polynomial shape for the ion VDF. The analytical results and the anisotropic moment equations are compared to collisionless particle-in-cell simulations, employing either a zero heat flux (Euler-like equations) or the polynomial-VDF closure for the heat flux. The analytical ion VDF and its moments are then compared to experimental measurements.
Exact semi-classical light–matter interaction operator applied to two-photon processes with strong relativistic effects
Authors: Delcey Mickaël G. , Couto Rafael Carvalho , Sørensen Lasse Kragh , Fdez. Galván Ignacio , Guo Meiyuan , Lindh Roland , Lundberg Marcus
Published: July 2020

X-ray processes involve interactions with high-energy photons. For these short wavelengths, the perturbing field cannot be treated as constant, and there is a need to go beyond the electric-dipole approximation. The exact semi-classical light–matter interaction operator offers several advantages compared to the multipole expansion such as improved stability and ease of implementation. Here, the exact operator is used to model x-ray scattering in metal K pre-edges. This is a relativistic two-photon process where absorption is dominated by electric-dipole forbidden transitions. With the restricted active space state-interaction approach, spectra can be calculated even for the multiconfigurational wavefunctions including second-order perturbation. However, as the operator itself depends on the transition energy, the cost for evaluating integrals for hundreds of thousands unique transitions becomes a bottleneck. Here, this is solved by calculating the integrals in a molecular-orbital basis that only runs over the active space, combined with a grouping scheme where the operator is the same for close-lying transitions. This speeds up the calculations of single-photon processes and is critical for the modeling of two-photon scattering processes. The new scheme is used to model Kα resonant inelastic x-ray scattering of iron–porphyrin complexes with relevance to studies of heme enzymes, for which the total computational time is reduced by several orders of magnitude with an effect on transition intensities of 0.1% or less.
Systematic errors in diffusion coefficients from long-time molecular dynamics simulations at constant pressure
Authors: von Bülow Sören , Bullerjahn Jakob Tómas , Hummer Gerhard
Published: July 2020

In molecular dynamics simulations under periodic boundary conditions, particle positions are typically wrapped into a reference box. For diffusion coefficient calculations using the Einstein relation, the particle positions need to be unwrapped. Here, we show that a widely used heuristic unwrapping scheme is not suitable for long simulations at constant pressure. Improper accounting for box-volume fluctuations creates, at long times, unphysical trajectories and, in turn, grossly exaggerated diffusion coefficients. We propose an alternative unwrapping scheme that resolves this issue. At each time step, we add the minimal displacement vector according to periodic boundary conditions for the instantaneous box geometry. Here and in another paper [J. T. Bullerjahn, S. von Bülow, and G. Hummer, J. Chem. Phys. 153, 024116 (2020)], we apply the new unwrapping scheme to extensive molecular dynamics and Brownian dynamics simulation data. We provide practitioners with a formula to assess if and by how much earlier results might have been affected by the widely used heuristic unwrapping scheme.
Widegap CH3NH3PbBr3 solar cells for optical wireless power transmission application
Authors: Ishikawa Ryousuke , Kato Takuya , Anzo Ryotaro , Nagatake Momoko , Nishimura Tatsuya , Tsuboi Nozomu , Miyajima Shinsuke
Published: July 2020

The optoelectrical properties of bromide-based perovskite thin films were evaluated to develop an optical wireless power transmission system. CH3NH3PbBr3 (MAPbBr3) films were deposited by the anti-solvent method after substrate preheating. The low-temperature exciton emission and discontinuous peak shift from phase transitions in the emission spectra indicate the high optical quality of MAPbBr3 films on TiO2. The Urbach energy and diffusion length of the MAPbBr3 thin films on TiO2 were 22.7 meV and 1.14 μm, respectively. The films exhibited good solar cell performance under monochromatic light with an efficiency over 20%.
Composition dependence of spin−orbit torque in Pt1−xMnx/CoFeB heterostructures
Authors: Vihanga De Zoysa K. , DuttaGupta Samik , Itoh Ryuichi , Takeuchi Yutaro , Ohno Hideo , Fukami Shunsuke
Published: July 2020

We investigate spin–orbit torques (SOTs) in heterostructures with Pt1−xMnx alloy and CoFeB as a function of Mn composition (x) by using an extended harmonic Hall measurement. Slonczewski-like and field-like SOT efficiencies (ξSL and ξFL) show non-monotonic variation and a different trend with respect to x, and considerably large ξSL up to 0.21 is obtained at x = 0.20. Compared to the x dependence of longitudinal resistivity, the Slonczewski-like SOT in the low x region is mainly attributed to an intrinsic spin-Hall mechanism, whereas a non-monotonic variation in the higher x region suggests the presence of additional factors. The present findings deliver useful clues to understand the physics behind SOT generation in antiferromagnetic heterostructures and offer a route to realize efficient devices.
High-temperature nitrogen annealing induced bonding states and photoluminescence changes in inductively coupled plasma torch synthesized silicon nanostructures
Authors: Freddi Sonia , Fabbri Filippo , Cannizzaro Annalisa , Agati Marta , Dolbec Richard , Drera Giovanni , Pagliara Stefania , Sangaletti Luigi , El Khakani My Ali , Boninelli Simona , Castrucci Paola
Published: July 2020

In this work, we investigate the optical properties of self-standing Si nanostructures (SiNS) as-grown, by an inductively coupled plasma torch process, and after their annealing under N2 flux at 1200 °C. We show that as-grown SiNS are embedded in a silicon oxide shell while part of the annealed SiNS transforms into silicon nitrides or oxynitrides. The analysis of the photoluminescence spectra and maps of both as-grown and annealed SiNS enabled us to confirm the occurrence of quantum confinement effects in the ultra-small SiNS and to highlight the role played by the silicon oxide, silicon nitrides, and silicon oxynitrides nanophases in the photoluminescence emission.
Beamforming with transformation acoustics in anisotropic media
Authors: Craig Steven R. , Lee Jeong Hun , Shi Chengzhi
Published: July 2020

Transformation acoustics correlates complex material properties in physical space with distorted wave manipulations in virtual space, such that wave propagation patterns can be determined by mathematical coordinate transformations. These transformations allow for accurate modeling of acoustic propagation in complex materials. Such models are relevant for both biomedical ultrasound therapies and integrated on-chip systems, where muscle fibers and piezoelectric substrates act as effective anisotropic media, respectively. Without considering the anisotropic density of these sophisticated media, attempts to beamform acoustic patterns by phase engineering result in a heavily distorted signal. This distortion is detrimental to the performance of high intensity focused ultrasound acoustic tweezers for noninvasive surgeries, cell trapping, and cell sorting. Here, we demonstrate that the distortion effects can be corrected by transformation acoustics in which the phased array profile is adjusted to account for the corresponding anisotropy. We perform experiments to verify this transformation acoustic correction for arbitrary focused and self-bending beams with two-dimensional anisotropic spoof surface acoustic waves. The benefit of transformation acoustics in suppressing undesired anisotropic effects on beamformed waves improves the precision and efficacy of medical treatments that facilitate noninvasive ultrasound therapies and integrated on-chip applications.
Numerical investigation of engulfment flow at low Reynolds numbers in a T-shaped microchannel
Authors: Madana Venkata Sai Teja , Ashraf Ali Basheer
Published: July 2020

Microreactors play a major role in the intensification of industrial processes. The performance of microfluidic devices depends on the flow behavior and flow regimes present in such systems. In this work, single-phase flow behavior and associated flow regimes in a T-shaped microchannel are numerically analyzed using computational fluid dynamics (CFD). To predict the single-phase flow regimes, three dimensional transient CFD simulations are performed. The critical Reynolds number (Re) at which flow regime transition and onset of engulfment occur is identified (Recritical = 300). To achieve engulfment flow at lower Re, the inlet geometry of the microchannel is modified as a convergent (C)–divergent (D) section and its effect on engulfment flow is analyzed. When the C/D ratio is 9:1, the predicted pressure drop (Δp) is found to be minimum (Recritical = 75, Δp = 5.4 kPa). The understanding of the engulfment flow regime is exploited through residence time distribution (RTD). The predicted RTD profiles indicate strong recirculation among vortices. The mixing index is calculated to quantify RTD, and it is found to be minimum when the C/D ratio is 9:1. The mixing performance is further verified by introducing buoyant particles in Lagrangian manner using discrete phase modeling. The predicted dynamics are qualitatively and quantitatively analyzed through Poincaré maps and Shannon’s entropy for various convergent–divergent inlets to characterize mixing. Once again, the C/D ratio of 9:1 supports in enhancing mixing in the microchannel. Hence, the proposed micromixer based on geometric modifications at the inlet helps achieve the engulfment flow regime at low Re.
Evolutionary origins for ecological patterns in space
Authors: Urban Mark C. , Strauss Sharon Y. , Pelletier Fanie , Palkovacs Eric P. , Leibold Mathew A. , Hendry Andrew P. , De Meester Luc , Carlson Stephanie M. , Angert Amy L. , Giery Sean T.
Published: July 2020

Historically, many biologists assumed that evolution and ecology acted independently because evolution occurred over distances too great to influence most ecological patterns. Today, evidence indicates that evolution can operate over a range of spatial scales, including fine spatial scales. Thus, evolutionary divergence across space might frequently interact with the mechanisms that also determine spatial ecological patterns. Here, we synthesize insights from 500 eco-evolutionary studies and develop a predictive framework that seeks to understand whether and when evolution amplifies, dampens, or creates ecological patterns. We demonstrate that local adaptation can alter everything from spatial variation in population abundances to ecosystem properties. We uncover 14 mechanisms that can mediate the outcome of evolution on spatial ecological patterns. Sometimes, evolution amplifies environmental variation, especially when selection enhances resource uptake or patch selection. The local evolution of foundation or keystone species can create ecological patterns where none existed originally. However, most often, we find that evolution dampens existing environmental gradients, because local adaptation evens out fitness across environments and thus counteracts the variation in associated ecological patterns. Consequently, evolution generally smooths out the underlying heterogeneity in nature, making the world appear less ragged than it would be in the absence of evolution. We end by highlighting the future research needed to inform a fully integrated and predictive biology that accounts for eco-evolutionary interactions in both space and time.
Kpi, a chaperone-usher pili system associated with the worldwide-disseminated high-risk clone
Klebsiella pneumoniae
ST-15
Authors: Gato Eva , Vázquez-Ucha Juan Carlos , Rumbo-Feal Soraya , Álvarez-Fraga Laura , Vallejo Juan A. , Martínez-Guitián Marta , Beceiro Alejandro , Ramos Vivas Jose , Sola Campoy Pedro J. , Pérez-Vázquez María , Oteo Iglesias Jesus , Rodiño-Janeiro Bruno Kotska , Romero Antonio , Poza Margarita , Bou Germán , Pérez Astrid
Published: July 2020

Significance

Emergence of the pathogen
Klebsiella pneumoniae
(particularly of carbapenem-resistant strains) is considered a dire threat to public health. Resistance and virulence determinants may favor the emergence of untreatable infections. Understanding the mechanisms involved in the pathogenesis and epidemicity of
K. pneumoniae
is essential for managing outbreaks and developing treatments. Here we identify a CUP system (Kpi) and infer the epidemiology of Kpi
+
K. pneumoniae
in Europe. We demonstrate a direct link between Kpi presence and
K
.
pneumoniae
persistence in the hospital environment. Adherence of the bacterium to different cell types enables host colonization, favoring nosocomial outbreaks and spread of infection. Kpi appears to play a key role in the host–pathogen interaction and is associated with the worldwide-disseminated ST-15 clone.
L-type Ca
2+
channel blockers promote vascular remodeling through activation of STIM proteins
Authors: Johnson Martin T. , Gudlur Aparna , Zhang Xuexin , Xin Ping , Emrich Scott M. , Yoast Ryan E. , Courjaret Raphael , Nwokonko Robert M. , Li Wei , Hempel Nadine , Machaca Khaled , Gill Donald L. , Hogan Patrick G. , Trebak Mohamed
Published: July 2020

Voltage-gated L-type Ca
2+
channel (Ca
v
1.2) blockers (LCCBs) are major drugs for treating hypertension, the preeminent risk factor for heart failure. Vascular smooth muscle cell (VSMC) remodeling is a pathological hallmark of chronic hypertension. VSMC remodeling is characterized by molecular rewiring of the cellular Ca
2+
signaling machinery, including down-regulation of Ca
v
1.2 channels and up-regulation of the endoplasmic reticulum (ER) stromal-interacting molecule (STIM) Ca
2+
sensor proteins and the plasma membrane ORAI Ca
2+
channels. STIM/ORAI proteins mediate store-operated Ca
2+
entry (SOCE) and drive fibro-proliferative gene programs during cardiovascular remodeling. SOCE is activated by agonists that induce depletion of ER Ca
2+
, causing STIM to activate ORAI. Here, we show that the three major classes of LCCBs activate STIM/ORAI-mediated Ca
2+
entry in VSMCs. LCCBs act on the STIM N terminus to cause STIM relocalization to junctions and subsequent ORAI activation in a Ca
v
1.2-independent and store depletion-independent manner. LCCB-induced promotion of VSMC remodeling requires STIM1, which is up-regulated in VSMCs from hypertensive rats. Epidemiology showed that LCCBs are more associated with heart failure than other antihypertensive drugs in patients. Our findings unravel a mechanism of LCCBs action on Ca
2+
signaling and demonstrate that LCCBs promote vascular remodeling through STIM-mediated activation of ORAI. Our data indicate caution against the use of LCCBs in elderly patients or patients with advanced hypertension and/or onset of cardiovascular remodeling, where levels of STIM and ORAI are elevated.
Atomic structure of the
Campylobacter jejuni
flagellar filament reveals how ε Proteobacteria escaped Toll-like receptor 5 surveillance
Authors: Kreutzberger Mark A. B. , Ewing Cheryl , Poly Frederic , Wang Fengbin , Egelman Edward H.
Published: July 2020

Significance

Flagella are used by many pathogenic bacteria not only for motility but also for adhesion to host cells and to other bacteria in biofilm formation. Since thousands of copies of flagellin, the protein that forms the flagellar filament, are exposed on the surface of bacteria, they are a target for immune surveillance by hosts. Some bacteria important to human health, such as
Campylobacter jejuni
and
Helicobacter pylori
, have managed to evade the innate immune recognition of their flagellin. We show, with an atomic structure of the
Campylobacter jejuni
flagellar filament, how mutations that destabilize the filament in one region recognized by vertebrates have been compensated for by new contacts not seen in other flagellar filaments that would stabilize these filaments.
Cancer cells educate natural killer cells to a metastasis-promoting cell state
Authors: Chan Isaac S. , Knútsdóttir Hildur , Ramakrishnan Gayathri , Padmanaban Veena , Warrier Manisha , Ramirez Juan Carlos , Dunworth Matthew , Zhang Hao , Jaffee Elizabeth M. , Bader Joel S. , Ewald Andrew Josef
Published: July 2020

Natural killer (NK) cells have potent antitumor and antimetastatic activity. It is incompletely understood how cancer cells escape NK cell surveillance. Using ex vivo and in vivo models of metastasis, we establish that keratin-14+ breast cancer cells are vulnerable to NK cells. We then discovered that exposure to cancer cells causes NK cells to lose their cytotoxic ability and promote metastatic outgrowth. Gene expression comparisons revealed that healthy NK cells have an active NK cell molecular phenotype, whereas tumor-exposed (teNK) cells resemble resting NK cells. Receptor–ligand analysis between teNK cells and tumor cells revealed multiple potential targets. We next showed that treatment with antibodies targeting TIGIT, antibodies targeting KLRG1, or small-molecule inhibitors of DNA methyltransferases (DMNT) each reduced colony formation. Combinations of DNMT inhibitors with anti-TIGIT or anti-KLRG1 antibodies further reduced metastatic potential. We propose that NK-directed therapies targeting these pathways would be effective in the adjuvant setting to prevent metastatic recurrence.
The complex choreography of agricultural biotechnology in Africa
Authors: Rock Joeva , Schurman Rachel
Published: July 2020

In spite of impressive efforts from public and private organizations over the last 25 years, agricultural biotechnology has gained relatively little ground in Africa. Using ethnographic research and case studies from across the continent, we argue that a complex choreography of socio-political, regulatory, and business conditions is required for agricultural biotechnology projects to ‘succeed’ in Africa. While this choreography is rarely achieved, efforts to bring agricultural biotechnology to the continent have resulted in significant reconfigurations of political, legal, and media landscapes in many African countries. These shifts cry out for more scholarly attention, which we attempt to give here.
Breadwinners and Losers: Does the Mental Health of Mothers, Fathers, and Children Vary by Household Employment Arrangements? Evidence From 7 Waves of Data From the Longitudinal Study of Australian Children
Authors: King Tania L , Shields Marissa , Byars Sean , Kavanagh Anne M , Craig Lyn , Milner Allison
Published: July 2020

In Australia, as in many industrialized countries, the past 50 years have been marked by increasing female labor-force participation. It is popularly speculated that this might impose a mental-health burden on women and their children. This analysis aimed to examine the associations between household labor-force participation (household employment configuration) and the mental health of parents and children. Seven waves of data from the Longitudinal Study of Australian Children were used, comprising 2004–2016, with children aged 4–17 years). Mental health outcome measures were the Strengths and Difficulties Questionnaire (children/adolescents) and 6-item Kessler Psychological Distress Scale (parents). A 5-category measure of household employment configuration was derived from parental reports: both parents full-time, male-breadwinner, female-breadwinner, shared-part-time employment (both part-time) and father full-time/mother part-time (1.5-earner). Fixed-effects regression models were used to compare within-person effects, controlling for time-varying confounders. For men, the male-breadwinner configuration was associated with poorer mental health compared with the 1.5-earner configuration (β = 0.21, 95% confidence interval: 0.05, 0.36). No evidence of association was observed for either women or children. This counters prevailing social attitudes, suggesting that neither children nor women are adversely affected by household employment configuration, nor are they disadvantaged by the extent of this labor-force participation. Men’s mental health appears to be poorer when they are the sole household breadwinner.
Safe Glabellar Wrinkle Correction With Soft Tissue Filler Using Doppler Ultrasound
Authors: Lee Won , Moon Hyoung-Jin , Kim Ji-Soo , Yang Eun-Jung
Published: July 2020

Background

Glabellar wrinkle corrections are usually performed by injecting botulinum toxin and hyaluronic acid fillers. The glabella is one of the most dangerous locations for filler injection because of possible visual complications.

Objectives

The aim of this study was to use Doppler ultrasound to determine the anatomic relation between glabellar wrinkles and the supratrochlear artery pathway, perform safe hyaluronic acid filler injection to correct glabellar wrinkles, and determine the efficacy of the procedure.

Methods

From January 2019 to July 2019, 42 patients (74 glabellar wrinkle lines; 32 bilateral and 10 unilateral wrinkles) were evaluated. Glabellar wrinkle lines were corrected with hyaluronic acid filler. Doppler ultrasound was used to avoid the supratrochlear artery.

Results

Among the 74 wrinkle lines, the supratrochlear arteries were located either at the glabellar wrinkle lines (30/74, 41%) or lateral to the glabellar wrinkle lines (44/74, 59%). In the latter 44 wrinkles, fillers were injected into the subdermal layer of the glabellar wrinkle lines. In the 30 wrinkles where supratrochlear artery was located at the glabellar wrinkle lines, the artery was located at the deep subcutaneous layer in 24 and at the subdermal layer in 6; thus, filler injection was not performed.

Conclusions

The supratrochlear artery may be located either at or lateral to the glabellar wrinkle lines. When performing glabellar wrinkle correction, Doppler ultrasound can be used to confirm the location of the supratrochlear artery before filler injection, which helps in avoiding vascular complications.

Level of Evidence: 4
Factors Related to Organisational Commitment amongst Social Workers in the Occupied Palestinian Territories
Authors: Safadi Najwa S , Easton Scott D , Hasson Robert G
Published: July 2020

This study examined the contribution of social–demographic characteristics, employee attitudes and environmental factors in explaining levels of organisational commitment amongst public sector social workers in the Occupied Palestinian Territories. Using a cross-sectional design, data were collected in the summer of 2016 from employees at twelve local directorates of the Ministry of Social Development (N = 237) in the West Bank. Palestinian social workers reported extremely high levels of overall organisational commitment. Results of multiple regressions revealed predictors of this outcome, including job stress, job satisfaction and service orientation. As hypothesised, job satisfaction and service orientation were positively related to the dependent variable. Surprisingly, higher levels of job stress were related to higher levels of organisational commitment. Implications for organisational policies and future research are discussed.
Graded, multidimensional intra- and intergroup variations in primary progressive aphasia and post-stroke aphasia
Authors: Ingram Ruth U , Halai Ajay D , Pobric Gorana , Sajjadi Seyed , Patterson Karalyn , Lambon Ralph Matthew A
Published: July 2020

Language impairments caused by stroke (post-stroke aphasia, PSA) and neurodegeneration (primary progressive aphasia, PPA) have overlapping symptomatology, nomenclature and are classically divided into categorical subtypes. Surprisingly, PPA and PSA have rarely been directly compared in detail. Rather, previous studies have compared certain subtypes (e.g. semantic variants) or have focused on a specific cognitive/linguistic task (e.g. reading). This study assessed a large range of linguistic and cognitive tasks across the full spectra of PSA and PPA. We applied varimax-rotated principal component analysis to explore the underlying structure of the variance in the assessment scores. Similar phonological, semantic and fluency-related components were found for PSA and PPA. A combined principal component analysis across the two aetiologies revealed graded intra- and intergroup variations on all four extracted components. Classification analysis was used to test, formally, whether there were any categorical boundaries for any subtypes of PPA or PSA. Semantic dementia formed a true diagnostic category (i.e. within group homogeneity and distinct between-group differences), whereas there was considerable overlap and graded variations within and between other subtypes of PPA and PSA. These results suggest that (i) a multidimensional rather than categorical classification system may be a better conceptualization of aphasia from both causes; and (ii) despite the very different types of pathology, these broad classes of aphasia have considerable features in common.
Dextran sulphate-induced tau assemblies cause endogenous tau aggregation and propagation in wild-type mice
Authors: Masuda-Suzukake Masami , Suzuki Genjiro , Hosokawa Masato , Nonaka Takashi , Goedert Michel , Hasegawa Masato
Published: July 2020

Accumulation of assembled tau protein in the central nervous system is characteristic of Alzheimer’s disease and several other neurodegenerative diseases, called tauopathies. Recent studies have revealed that propagation of assembled tau is key to understanding the pathological mechanisms of these diseases. Mouse models of tau propagation are established by injecting human-derived tau seeds intracerebrally; nevertheless, these have a limitation in terms of regulation of availability. To date, no study has shown that synthetic assembled tau induce tau propagation in non-transgenic mice. Here we confirm that dextran sulphate, a sulphated glycosaminoglycan, induces the assembly of recombinant tau protein into filaments in vitro. As compared to tau filaments induced by heparin, those induced by dextran sulphate showed higher thioflavin T fluorescence and lower resistance to guanidine hydrochloride, which suggests that the two types of filaments have distinct conformational features. Unlike other synthetic filament seeds, intracerebral injection of dextran sulphate-induced assemblies of recombinant tau caused aggregation of endogenous murine tau in wild-type mice. AT8-positive tau was present at the injection site 1 month after injection, from where it spread to anatomically connected regions. Induced tau assemblies were also stained by anti-tau antibodies AT100, AT180, 12E8, PHF1, anti-pS396 and anti-pS422. They were thioflavin- and Gallyas-Braak silver-positive, indicative of amyloid. In biochemical analyses, accumulated sarkosyl-insoluble and hyperphosphorylated tau was observed in the injected mice. In conclusion, we revealed that intracerebral injection of synthetic full-length wild-type tau seeds prepared in the presence of dextran sulphate caused tau propagation in non-transgenic mice. These findings establish that propagation of tau assemblies does not require tau to be either mutant and/or overexpressed.
Neural correlates of polygenic risk score for autism spectrum disorders in general population
Authors: Khundrakpam Budhachandra , Vainik Uku , Gong Jinnan , Al-Sharif Noor , Bhutani Neha , Kiar Gregory , Zeighami Yashar , Kirschner Matthias , Luo Cheng , Dagher Alain , Evans Alan
Published: July 2020

Autism spectrum disorder is a highly prevalent and highly heritable neurodevelopmental condition, but studies have mostly taken traditional categorical diagnosis approach (yes/no for autism spectrum disorder). In contrast, an emerging notion suggests a continuum model of autism spectrum disorder with a normal distribution of autistic tendencies in the general population, where a full diagnosis is at the severe tail of the distribution. We set out to investigate such a viewpoint by investigating the interaction of polygenic risk scores for autism spectrum disorder and Age2 on neuroimaging measures (cortical thickness and white matter connectivity) in a general population (n = 391, with age ranging from 3 to 21 years from the Pediatric Imaging, Neurocognition and Genetics study). We observed that children with higher polygenic risk for autism spectrum disorder exhibited greater cortical thickness for a large age span starting from 3 years up to ∼14 years in several cortical regions localized in bilateral precentral gyri and the left hemispheric postcentral gyrus and precuneus. In an independent case–control dataset from the Autism Brain Imaging Data Exchange (n = 560), we observed a similar pattern: children with autism spectrum disorder exhibited greater cortical thickness starting from 6 years onwards till ∼14 years in wide-spread cortical regions including (the ones identified using the general population). We also observed statistically significant regional overlap between the two maps, suggesting that some of the cortical abnormalities associated with autism spectrum disorder overlapped with brain changes associated with genetic vulnerability for autism spectrum disorder in healthy individuals. Lastly, we observed that white matter connectivity between the frontal and parietal regions showed significant association with polygenic risk for autism spectrum disorder, indicating that not only the brain structure, but the white matter connectivity might also show a predisposition for the risk of autism spectrum disorder. Our findings showed that the fronto-parietal thickness and connectivity are dimensionally related to genetic risk for autism spectrum disorder in general population and are also part of the cortical abnormalities associated with autism spectrum disorder. This highlights the necessity of considering continuum models in studying the aetiology of autism spectrum disorder using polygenic risk scores and multimodal neuroimaging.