bluuebunny/crossref_metadata_2025 huggingface dataset:
Analytic solutions for Asay foil trajectories with implications for ejecta source models and mass measurements
Authors: Tregillis I. L. , Koskelo Aaron , Harrison Alan K.
Published: September 2021

We consider the trajectory of an Asay foil ejecta diagnostic for scenarios where ejecta are produced at a singly shocked planar surface and fly ballistically through a perfect vacuum to the sensor. We do so by building upon a previously established mathematical framework derived for the analytic study of stationary sensors. First, we derive the momentum conservation equation for the problem, in a form amenable to accelerating sensors, in terms of a generic ejecta source model. The result is an integrodifferential equation of motion for the foil trajectory. This equation yields an easily calculable closed-form implicit solution for the foil trajectory in instant-production scenarios. From there, we derive a boundary condition that particle velocity distributions must satisfy if their associated foil trajectories are to exhibit a smooth initial acceleration, as occurs in some experiments. This condition is identical to one derived previously from a consideration of piezoelectric voltage data obtained in similar experiments. We also compare techniques for inferring accumulated ejecta masses from foil trajectories, first by deriving the exact solution, and then by quantifying the error imposed by a frequently used approximate solution (both subject to the assumption of instantaneous ejecta production). Finally, we examine the common practice of presenting inferred cumulative ejecta masses as a function of implied ejecta velocity, establishing the conditions under which this methodology is most meaningful.
Nuclear singlet relaxation by chemical exchange
Authors: Bengs Christian , Dagys Laurynas , Moustafa Gamal A. I. , Whipham James W. , Sabba Mohamed , Kiryutin Alexey S. , Ivanov Konstantin L. , Levitt Malcolm H.
Published: September 2021

The population imbalance between nuclear singlet states and triplet states of strongly coupled spin-1/2 pairs, also known as nuclear singlet order, is well protected against several common relaxation mechanisms. We study the nuclear singlet relaxation of 13C pairs in aqueous solutions of 1,2-13C2 squarate over a range of pH values. The 13C singlet order is accessed by introducing 18O nuclei in order to break the chemical equivalence. The squarate dianion is in chemical equilibrium with hydrogen-squarate (SqH−) and squaric acid (SqH2) characterized by the dissociation constants pK1 = 1.5 and pK2 = 3.4. Surprisingly, we observe a striking increase in the singlet decay time constants TS when the pH of the solution exceeds ∼10, which is far above the acid–base equilibrium points. We derive general rate expressions for chemical-exchange-induced nuclear singlet relaxation and provide a qualitative explanation of the TS behavior of the squarate dianion. We identify a kinetic contribution to the singlet relaxation rate constant, which explicitly depends on kinetic rate constants. Qualitative agreement is achieved between the theory and the experimental data. This study shows that infrequent chemical events may have a strong effect on the relaxation of nuclear singlet order.
Trapping of H2− in aluminum hydride, Al4H14−
Authors: Kiran Boggavarapu , Bowen Kit H. , Kandalam Anil K.
Published: September 2021

Ever since our first experimental and computational identification of Al4H6 as a boron analog [X. Li et al., Science 315, 356 (2007)], studies on aluminum hydrides unveiled a richer pattern of structural motifs. These include aluminum-rich hydrides, which follow shell closing electron counting models; stoichiometric clusters (called baby crystals), which structurally correspond to the bulk alane; and more. In this regard, a mass spectral identification of unusually high intense peak of Al4H14−, which has two hydrogen atoms beyond stoichiometry, has remained mostly unresolved [X. Li et al., J. Chem. Phys. 132, 241103 (2010)]. In this Communication, with the help of global minima methods and density functional theory-based calculations, we identify the lowest energy bound structure with a unique Al–H–H–Al bonding. Our electronic structural analysis reveals that two Al2H6 units trap a transient, metastable H2−. In other words, three stable molecules, two Al2H6 and an H2, are held together by a single electron. Our studies provide a pathway to stabilize transient species by making them part of a more extensive system.
COVID-19 challenges faced by general practitioners in Australia: a survey study conducted in March 2021
Authors: Copp Tessa , Isautier Jennifer M. J. , Nickel Brooke , Pickles Kristen , Tracy Marguerite , Doust Jenny , Bonner Carissa , Dodd Rachael H. , Ayre Julie , Cvejic Erin , Trevena Lyndal , Manocha Ramesh , McCaffery Kirsten J.
Published: September 2021

Limited studies at the beginning of the COVID-19 pandemic found GPs have been negatively affected by increased workload, reduced income and major concerns about staff and patient safety. This study aimed to investigate the challenges of COVID-19 in general practice 1 year since it was declared a pandemic. A national cross-sectional online survey was conducted in March 2021 of a convenience sample of 295 Australian GPs attending an online educational webcast. Twenty-five multipart and free-text questions collected information regarding GPs’ main COVID-19-related issues and concerns, including COVID-19 vaccines, useful sources of information, information needs and their perceived role as GPs in COVID-19 management. Descriptive statistics were calculated for all quantitative variables. Content analysis was used to analyse text data from open-ended questions. Of the 596 eligible attendees of the online educational webcast, 295 completed the survey (49.5% response rate). One year since COVID-19 was declared a pandemic, GPs still have concerns regarding patients ignoring prescreening and presenting with flu-like symptoms, the safety of their colleagues and family and catching COVID-19 themselves, as well as concerns about the effect of the pandemic on their patients and patients delaying essential care for non-COVID-19 conditions. More education and resources about vaccines was identified as the top information need, which will assist with what GPs’ perceived to be their key roles in managing the COVID-19 pandemic, namely educating the public, correcting misunderstandings and providing the COVID-19 vaccine. These findings highlight gaps in communication and information, particularly regarding COVID-19 vaccines. GPs need high-quality information and resources to support them in undertaking complex risk communication with their patients.
Metabolism modulates network synchrony in the aging brain
Authors: Weistuch Corey , Mujica-Parodi Lilianne R. , Razban Rostam M. , Antal Botond , van Nieuwenhuizen Helena , Amgalan Anar , Dill Ken A.
Published: September 2021

Significance

How do brains adapt to changing resource constraints? This is particularly relevant in the aging brain, for which the ability of neurons to utilize their primary energy source, glucose, is diminished. Through experiments and modeling, we find that changes to brain activity patterns with age can be understood in terms of decreasing metabolic activity. Specifically, we find that older brains approach a critical point in our model, enabling small changes in metabolic activity to give rise to an abrupt reconfiguration of functional brain networks.
Activity waves and freestanding vortices in populations of subcritical Quincke rollers
Authors: Liu Zeng Tao , Shi Yan , Zhao Yongfeng , Chaté Hugues , Shi Xia-qing , Zhang Tian Hui
Published: September 2021

Significance

Active matter is made of units that move or displace others by using energy stored internally or gathered from their environment. In most systems and models considered so far, these self-propelled units are constantly moving. Here we study active matter made of units that do not move when isolated, but can be set into motion by close neighbors. Our subcritical active matter consists of Quincke rollers, that is, colloidal spheres at the bottom of a cell filled with conducting fluid submitted to a vertical electric field. We find spectacular collective self-organized phenomena: activity waves propagating in a quiescent population, and arbitrarily large, steadily rotating vortices forming without confinement or particle chirality.
Matrix stiffness drives stromal autophagy and promotes formation of a protumorigenic niche
Authors: Hupfer Anna , Brichkina Anna , Koeniger Anke , Keber Corinna , Denkert Carsten , Pfefferle Petra , Helmprobst Frederik , Pagenstecher Axel , Visekruna Alexander , Lauth Matthias
Published: September 2021

Significance

Increased tissue stiffness is a hallmark of several diseases such as organ fibrosis or cancer, and tissue fibroblasts play central roles in these pathologies. In tumors, stromal cells support the growth of cancer cells by supplying signaling molecules and nutrients, the latter also being provided by stromal autophagy. The mechanisms inducing these processes are, however, not well understood. Here, we demonstrate that an increased physical rigidity of a fibroblast’s environment is sufficient to evoke stromal autophagy. Mechanistically, matrix stiffness is transmitted via Integrin αV receptors and focal adhesion kinase, resulting in stabilization of AMPK at focal adhesion structures. Stiffness-mediated stromal autophagy supports the growth of neighboring tumor cells in vitro and in vivo, opening possibilities for anti-cancer therapies.
Natural Fe-bearing aluminous bridgmanite in the Katol L6 chondrite
Authors: Ghosh Sujoy , Tiwari Kishan , Miyahara Masaaki , Rohrbach Arno , Vollmer Christian , Stagno Vincenzo , Ohtani Eiji , Ray Dwijesh
Published: September 2021

Significance

Bridgmanite is the most volumetrically abundant mineral of the Earth’s interior, and it is important to understand its formation mechanism to better comprehend the origin and evolution of planetary interiors. Natural bridgmanites have been reported in only a few shocked meteorites; however, the composition of these specimens differs from plausible compositions of terrestrial bridgmanite. This study reports a natural occurrence of bridgmanite, observed in an ordinary chondrite, with a composition closest to the bridgmanite present in the Earth’s lower mantle. The bridgmanite in the Katol chondrite has high Fe
3+
/ΣFe ratio and agrees with experimental predictions. The Katol chondrite may serve as a unique analogue for crystallization of bridgmanite during the final stages of magma ocean crystallization of the Earth.
A genetic model of methionine restriction extends
Drosophila
health- and lifespan
Authors: Parkhitko Andrey A. , Wang Lin , Filine Elizabeth , Jouandin Patrick , Leshchiner Dmitry , Binari Richard , Asara John M. , Rabinowitz Joshua D. , Perrimon Norbert
Published: September 2021

Significance

Methionine metabolism is dramatically affected by age and restricting methionine consumption extends the lifespan across different species. However, we have limited information on the activity of different branches of methionine metabolism during aging. Furthermore, how tissue-specific perturbation of methionine metabolism affects aging is not known. Here, by feeding
13
C5-methionine to
Drosophila
and tracing its fate in different branches of the methionine metabolism, we were able to identify impairments of methionine flux associated with aging. In addition, to deplete methionine in a tissue-specific manner, we created transgenic flies that express
Methioninase
. Strikingly,
Methioninase
expression even in a single tissue can dramatically extend the health- and lifespan.
Mechanistic insights into central spindle assembly mediated by the centralspindlin complex
Authors: Pan Han , Guan Ruifang , Zhao Ruixue , Ou Guangshuo , Chen Zhucheng
Published: September 2021

Significance

Centralspindlin bundles microtubules to assemble the central spindle, being essential for cytokinesis of the cell. It is a heterotetramer formed by ZEN-4 and CYK-4 in a 2:2 manner. We determined the crystal structures of centralspindlin, which revealed the detailed mechanism of complex formation. We found that centralspindlin clustered to undergo liquid–liquid phase separation (LLPS), which depended on the complementary charged residues located at ZEN-4 and CYK-4, respectively, explaining the synergy of the two subunits for the function. The LLPS of centralspindlin is critical for the microtubule bundling activity in vitro and the assembly of the central spindle in vivo. Together, our study provides angstrom-to-micron mechanistic insights into central spindle assembly mediated by the centralspindlin complex.
Interpreting in Tanzania from the perspective of Tanzanian interpreters
Authors: Getta Elizaveta
Published: September 2021

The study overviews the role of interpreting services in Tanzania, presenting mainly the experience of practicing freelance interpreters. The two official languages of Tanzania – English and Swahili – have separate roles in the country. Although most Tanzanians accept English as a necessary medium of intercultural communication, Swahili is perceived as an important part of Tanzanian national identity. It is the country’s lingua franca. On the one hand, Tanzania aims to preserve communication in Swahili; on the other hand, there is an inevitable need for intercultural communication with the rest of the world that grows especially in the context of globalization. The paper focuses on the role, status, education, working languages, conditions of Tanzanian interpreters, and the requirements of local and international clients. The study also creates a broader context that mentions crucial historical moments that have influenced the country’s current character of intercultural communication.
Britain as a protector, a mediator or an onlooker?
Authors: Wang Guofeng
Published: September 2021

Since Hong Kong’s handover to China, British newspapers still play an active role in constructing Britain’s connections with its former colony. This study elaborates a schema for protests to help better understand protests in general. Based on this schema, the study examined representations of the 2019–20 protests in British newspapers using the approach of corpus-assisted critical discourse studies. The analysis shows that they mainly used the predicational strategy, and emphasized the Chinese government’s control of Hong Kong – including the inabilities of the Hong Kong government and police violence – in contrast with the protestors’ demands for universal suffrage. They suggested that Britain act as a mediator to shoulder a moral responsibility over Hong Kong. Their attitudes are interpreted with regard to Britain’s foreign policies and the dominant ideology cultivated in its historical, socio-political contexts and suggest that the UK journalistic practice regarding Hong Kong issues is political-driven to a great extent.
A National Survey of Barriers and Facilitators to Medications for Opioid use Disorder among Legal-Involved Veterans in the Veterans Health Administration
Authors: Taylor Emmeline N. , Timko Christine , Binswanger Ingrid A. , Harris Alex H. S. , Stimmel Matthew , Smelson David , Finlay Andrea K.
Published: September 2021

Background: Medications for opioid use disorder (MOUD) are clinically effective at treating OUD among legal-involved populations. However, research shows that legal-involved veterans who receive care through the VHA have lower rates of MOUD use compared to non-legal-involved veterans. Education may be a key factor in intervention strategies to improve MOUD access. This study was a national survey of VHA staff to identify barriers to and facilitators of MOUD, as well as MOUD-related education needs for VHA staff, community partners, criminal justice partners, and legal-involved veterans. Method: A 98-item online survey was conducted to examine VHA staff perspectives ( N = 218) around needed education, barriers to, and facilitators of MOUD for legal-involved veterans. Descriptive statistics were conducted and linear regression analyses were used to evaluate differences in perceptions by respondents’ current position at the VHA and their VHA facility's rate of provision of MOUD among legal-involved veterans. Results: Respondents endorsed a need for education in all areas of MOUD (e.g., existing medications for the treatment of OUD) for VHA staff and providers, community partners, criminal justice partners, and legal-involved veterans. VHA staff perceived barriers to MOUD for legal-involved veterans to include stigma and complicated guidelines around MOUD and OUD treatment. Facilities with low rates of MOUD use highlighted barriers including MOUD conflicting with the philosophy of the local VHA facility and provider stigma toward patients with OUD. Perceptions of efficacy of MOUD differed by respondents’ current position at the VHA such that substance use disorder treatment providers perceived buprenorphine and methadone as more effective compared to Veterans Justice Specialists. Conclusion: The results of this study suggest a need for an educational intervention emphasizing the evidence supporting use of MOUD as a lack of knowledge about these medications was considered a barrier to access, whereas gaining education about MOUD was a facilitator to access. Education strategies specifically tailored to address VHA facility-level differences may help address barriers to MOUD experienced by legal-involved veterans.
Social Relationships, Homelessness, and Substance use among Emergency Department Patients
Authors: Jurewicz Amanda , Padgett Deborah K. , Ran Ziwei , Castelblanco Donna G. , McCormack Ryan P. , Gelberg Lillian , Shelley Donna , Doran Kelly M.
Published: September 2021

Background: Emergency department (ED) patients commonly experience both substance use and homelessness, and social relationships impact each in varied ways not fully captured by existing quantitative research. This qualitative study examines how social relationships can precipitate or ameliorate homelessness and the connection (if any) between substance use and social relationships among ED patients experiencing homelessness. Methods: As part of a broader study to develop ED-based homelessness prevention interventions, we conducted in-depth interviews with 25 ED patients who used alcohol or drugs and had recently become homeless. We asked patients about the relationship between their substance use and homelessness. Interviews were recorded, transcribed, and coded line-by-line by investigators. Final codes formed the basis for thematic analysis through consensus discussions. Results: Social relationships emerged as focal points for understanding the four major themes related to the intersection of homelessness and substance use: (1) Substance use can create strain in relationships; (2) Help is there until it's not; (3) Social relationships can create challenges contributing to substance use; and (4) Reciprocal relationship of substance use and isolation. Sub-themes were also identified and described. Conclusions: The association between substance use and homelessness is multifaceted and social relationships are a complex factor linking the two. Social relationships are often critical for homelessness prevention, but they are impacted by and reciprocally affect substance use. ED-based substance use interventions should consider the high prevalence of homelessness and the impact of social relationships on the interaction between homelessness and substance use.
The modified mitochondrial outer membrane carrier MTCH2 links mitochondrial fusion to lipogenesis
Authors: Labbé Katherine , Mookerjee Shona , Le Vasseur Maxence , Gibbs Eddy , Lerner Chad , Nunnari Jodi
Published: September 2021

Mitochondrial function is integrated with cellular status through the regulation of opposing mitochondrial fusion and division events. Here we uncover a link between mitochondrial dynamics and lipid metabolism by examining the cellular role of mitochondrial carrier homologue 2 (MTCH2). MTCH2 is a modified outer mitochondrial membrane carrier protein implicated in intrinsic cell death and in the in vivo regulation of fatty acid metabolism. Our data indicate that MTCH2 is a selective effector of starvation-induced mitochondrial hyperfusion, a cytoprotective response to nutrient deprivation. We find that MTCH2 stimulates mitochondrial fusion in a manner dependent on the bioactive lipogenesis intermediate lysophosphatidic acid. We propose that MTCH2 monitors flux through the lipogenesis pathway and transmits this information to the mitochondrial fusion machinery to promote mitochondrial elongation, enhanced energy production, and cellular survival under homeostatic and starvation conditions. These findings will help resolve the roles of MTCH2 and mitochondria in tissue-specific lipid metabolism in animals.
MicroRNA-directed pathway discovery elucidates an miR-221/222–mediated regulatory circuit in class switch recombination
Authors: Wigton Eric J. , Mikami Yohei , McMonigle Ryan J. , Castellanos Carlos A. , Wade-Vallance Adam K. , Zhou Simon K. , Kageyama Robin , Litterman Adam , Roy Suparna , Kitamura Daisuke , Dykhuizen Emily C. , Allen Christopher D.C. , Hu Hui , O’Shea John J. , Ansel K. Mark
Published: September 2021

MicroRNAs (miRNAs, miRs) regulate cell fate decisions by post-transcriptionally tuning networks of mRNA targets. We used miRNA-directed pathway discovery to reveal a regulatory circuit that influences Ig class switch recombination (CSR). We developed a system to deplete mature, activated B cells of miRNAs, and performed a rescue screen that identified the miR-221/222 family as a positive regulator of CSR. Endogenous miR-221/222 regulated B cell CSR to IgE and IgG1 in vitro, and miR-221/222–deficient mice exhibited defective IgE production in allergic airway challenge and polyclonal B cell activation models in vivo. We combined comparative Ago2-HITS-CLIP and gene expression analyses to identify mRNAs bound and regulated by miR-221/222 in primary B cells. Interrogation of these putative direct targets uncovered functionally relevant downstream genes. Genetic depletion or pharmacological inhibition of Foxp1 and Arid1a confirmed their roles as key modulators of CSR to IgE and IgG1.
Surface and underground seismic characterization at Terziet in Limburg—the Euregio Meuse–Rhine candidate site for Einstein Telescope
Authors: Koley Soumen , Bader Maria , van den Brand Jo , Campman Xander , Bulten Henk Jan , Linde Frank , Vink Bjorn
Published: September 2021

We present a detailed characterization of surface and underground seismic noise measured at Limburg in the south of the Netherlands. This location is the Euregio Meuse–Rhine candidate for hosting Einstein Telescope, a future observatory for gravitational waves. Seismic noise measurements were performed with an array of seismometers installed on the surface. Passive seismic methods like beamforming were used to extract the propagation wave types of ambient seismic noise and the Rayleigh-wave dispersion in the region. Subsurface shear-wave models sensitive to depths of 300 m were derived by using the Rayleigh-wave dispersion and ellipticity. Subsurface P-wave velocities to depths of 200 m were obtained from an active seismic survey. Wavepath Eikonal tomography was used on the source-receiver refracted-wave travel-times to obtain a subsurface P-wave velocity model. Both the passive and the active seismic data analysis point to the presence of a layered geology with a soft-soil to hard-rock transition occurring at a shallow depth of about 25 to 40 m. The surface arrays are complemented by two permanent tri-axial seismometers installed on the surface and in a borehole at 250 m depth. Their data are used to interpret the surface-wave and body-wave contributions to the observed seismic noise. We use a cross-correlation analysis and compute the theoretical surface-wave eigenfunctions to understand the contributions of the different wave types at different frequencies. We observe that below 4 Hz in the horizontal component and 9 Hz in the vertical component, the seismic noise at depth is dominantly due to surface waves. Above these frequencies a significant contribution can be attributed to both nearby and far-away body-wave sources. At a depth of 250 m we find that the surface noise power has been damped by up to a factor 104 above about 2 Hz. The Limburg geology with soft-soil on top of hard-rock efficiently damps the anthropogenic noise produced at the surface. This implies that Einstein Telescope’s test masses are shielded from anthropogenic seismic noise and construction at greater depth will not bring significant further improvements in this regard. A body-wave background has been identified that contributes about half of the total underground seismic noise at 250 m depth for frequencies above 4 Hz. It remains to be studied if subtraction schemes for Newtonian noise originating from this body-wave background will be necessary. Finally, we estimate an interferometer downtime of about 3% due to regional and teleseismic earthquakes. We believe this is acceptable as it is comparable to current experience at the LIGO and Virgo interferometer sites.
Adaptive polygon rendering for interactive visualization in the Schwarzschild spacetime
Authors: Müller Thomas , Schulz Christoph , Weiskopf Daniel
Published: September 2021

Interactive visualization is a valuable tool for introductory or advanced courses in general relativity as well as for public outreach to provide a deeper understanding of the visual implications due to curved spacetime. In particular, the extreme case of a black hole where the curvature becomes so strong that even light cannot escape, benefits from an interactive visualization where students can investigate the distortion effects by moving objects around. However, the most commonly used technique of four-dimensional general-relativistic ray tracing is still too slow for interactive frame rates. Therefore, we propose an efficient and adaptive polygon rendering method that takes light deflection and light travel time into account. An additional advantage of this method is that it provides a natural demonstration of how multiple images occur and how light travel time affects them. Finally, we present our method using three example scenes: a triangle passing behind a black hole, a sphere orbiting a black hole and an accretion disk with different inclination angles.
Intercalated water mediated electromechanical response of graphene oxide films on flexible substrates
Authors: Devendar Lavudya , Shijeesh M R , Sakorikar Tushar , Ganapathi K Lakshmi , Jaiswal Manu
Published: September 2021

The confinement of water between sub-nanometer bounding walls of layered two-dimensional materials has generated tremendous interest. Here, we examined the influence of confined water on the mechanical and electromechanical response of graphene oxide films, prepared with variable oxidative states, casted on polydimethylsiloxane substrates. These films were subjected to uniaxial strain under controlled humid environments (5 to 90% RH), while dc transport studies were performed in tandem. Straining resulted in the formation of quasi-periodic linear crack arrays. The extent of water intercalation determined the density of cracks formed in the system thereby, governing the electrical conductance of the films under strain. The crack density at 5% strain, varied from 0 to 3.5 cracks mm−1 for hydrated films and 8 to 22 cracks mm−1 for dry films, across films with different high oxidative states. Correspondingly, the overall change in the electrical conductance at 5% strain was observed to be ∼5 to 20 folds for hydrated films and ∼20 to 35 folds for the dry films. The results were modeled with a decrease in the in-plane elastic modulus of the film upon water intercalation, which was attributed to the variation in the nature of hydrogen bonding network in graphene oxide lamellae.
vdW-DF-ahcx: a range-separated van der Waals density functional hybrid
Authors: Shukla Vivekanand , Jiao Yang , Frostenson Carl M , Hyldgaard Per
Published: September 2021

Hybrid density functionals replace a fraction of an underlying generalized-gradient approximation (GGA) exchange description with a Fock-exchange component. Range-separated hybrids (RSHs) also effectively screen the Fock-exchange component and thus open the door for characterizations of metals and adsorption at metal surfaces. The RSHs are traditionally based on a robust GGA, such as PBE (Perdew J P et al 1996 Phys. Rev. Lett.
77 3865), for example, as implemented in the HSE design (Heyd J et al 2003 J. Chem. Phys.
118 8207). Here we define an analytical-hole (Henderson T M et al 2008 J. Chem. Phys.
128 194105) consistent-exchange RSH extension to the van der Waals density functional (vdW-DF) method (Berland K et al 2015 Rep. Prog. Phys.
78 066501), launching vdW-DF-ahcx. We characterize the GGA-type exchange in the vdW-DF-cx version (Berland K and Hyldgaard P 2014 Phys. Rev. B
89 035412), isolate the short-ranged exchange component, and define the new vdW-DF hybrid. We find that the performance vdW-DF-ahcx compares favorably to (dispersion-corrected) HSE for descriptions of bulk (broad molecular) properties. We also find that it provides accurate descriptions of noble-metal surface properties, including CO adsorption.
Protected quantum coherence by gain and loss in a noisy quantum kicked rotor
Authors: Wang Wen-Yuan , Zhao Wen-Lei
Published: September 2021

We study the effects of non-Hermiticity on quantum coherence via a noisy quantum kicked rotor (NQKR). The random noise comes from the fluctuations in kick amplitude at each time. The non-Hermitian driving indicates the imaginary kicking potential, representing the environment-induced atom gain and loss. In the absence of gain and loss, the random noise destroys quantum coherence manifesting dynamical localization, which leads to classical diffusion. Interestingly, in the presence of non-Hermitian kicking potential, the occurrence of dynamical localization is highly sensitive to the gain and loss, manifesting the restoration of quantum coherence. Using the inverse participation ratio arguments, we numerically obtain a phase diagram of the classical diffusion and dynamical localization on the parameter plane of noise amplitude and non-Hermitian driving strength. With the help of analysis on the corresponding quasieigenstates, we achieve insight into dynamical localization, and uncover that the origin of the localization is interference between multiple quasi-eigenstates of the quantum kicked rotor. We further propose an experimental scheme to realize the NQKR in a dissipative cold atomic gas, which paves the way for future experimental investigation of an NQKR and its anomalous non-Hermitian properties.
Micromagnetic modeling of magnon coherent states in a nonuniform magnetic field
Authors: Belanovsky A D , Vetoshko P M , Bunkov Yu M
Published: September 2021

Quantum magnonics is an emerging research field, with great potential for applications in a magnon based quantum technologies, including quantum computing, processing and encoding information. Magnon correlation and quantum entanglement are the main concepts in many quantum technologies under development. Of particular interest is the magnon Bose condensation. The emerging current question is the applicability of quasi-classical Landau–Lifshitz–Gilbert equations to describe the coherent state of magnons. We performed micromagnetic modeling of the magnetization dynamics at a high angle of deviation in an inhomogeneous magnetic field. We have obtained solutions that are well coincided with the properties of experimentally observed magnon BEC states. This result will be needed for the calculation the properties of magnetic devices on the basis of quantum magnonics.
A fault diagnosis method for rolling bearings based on inter-class repulsive force discriminant transfer learning
Authors: Wang Teng , Li Tongyi , Jiang Peixuan , Cheng Yangyang , Tang Tuojiang
Published: September 2021

For fault diagnosis of rolling bearings, it is generally difficult or even impossible to obtain class labels of new working condition samples under actual variable working conditions, which leads to a low fault diagnosis accuracy. On account of this, we propose a novel unsupervised transfer learning method called inter-class repulsive force discriminant transfer learning (IRFDTL) in this paper. In the proposed IRFDTL, to reduce the classification error in source domain and improve the generalization ability of IRFDTL, a nonnegative extended slack matrix is creatively constructed to transform the strict binary label matrix into an extended slack label matrix. Moreover, the joint distribution discrepancy is introduced to reduce the difference between source and target domains, and the inter-class repulsive force term is innovatively designed to promote the discriminative learning effect by increasing the inter-class distance. Finally, the whole framework of IRFDTL is optimized by the alternating direction multiplier method. By using the labeled samples under historical working conditions, the IRFDTL can perform high-precision class discrimination on the testing samples under new working conditions when there are no class labels of testing samples. The proposed IRFDTL-based fault diagnosis method can achieve precise fault diagnosis of the testing samples under new working conditions, and fault diagnosis instances of rolling bearings verify the effectiveness of the proposed method.
Design of Menger sponge fractal structural NiTi as bone implants
Authors: Zhang Xudong , Yang Fan , Liu Baosheng , Deng Junkai
Published: September 2021

Finite element simulations were performed to investigate potential applications of Menger sponge fractal NiTi structures as bone implants. The tunable correlations between porosity and fractal parameters in Menger sponge fractal structures were explored to match the characteristics of the natural bones, including porosity, hierarchical porous structures, and fractal dimensions. The computational results demonstrate that the broad range of elastic modulus and yield stress in our designed fractal NiTi structures can satisfy the mechanical requirements of natural bones. In addition, the hierarchical-stepwise phase transformation in fractal NiTi structures exhibits a statistical power-law behavior, which is compatible with the multiscale failure process during deformation in natural bones. These results indicate that Menger sponge fractal NiTi structures may have great potentials for bone implants. The present design concept of fractal structures may open new avenues in biomechanical capabilities that conventional metal structures cannot achieve.
Designing hexagonal close packed high entropy alloys using machine learning
Authors: Akhil Bejjipurapu , Bajpai Anurag , Gurao Nilesh P , Biswas Krishanu
Published: September 2021

High entropy alloys (HEAs) have drawn significant interest in the materials research community owing to their remarkable physical and mechanical properties. These improved physicochemical properties manifest due to the formation of simple solid solution phases with unique microstructures. Though several pathbreaking HEAs have been reported, the field of alloy design, which has the potential to guide alloy screening, is still an open topic hindering the development of new HEA compositions, particularly ones with hexagonal close packed (hcp) crystal structure. In this work, an attempt has been made to develop an intelligent extra tree (ET) classification model based on the key thermodynamic and structural properties, to predict the phase evolution in HEAs. The results of correlation analysis suggest that all the selected thermodynamic and structural features are viable candidates for the descriptor dataset. Testing accuracy of above 90% along with excellent performance matrices for the ET classifier reveal the robustness of the model. The model can be employed to design novel hcp HEAs and as a valuable tool in the alloy design of HEAs in the future.
Model for current drive induced crash cycles in W7-X
Authors: Aleynikova K. , Hudson S.R. , Helander P. , Kumar A. , Geiger J. , Hirsch M. , Loizu J. , Nührenberg C. , Rahbarnia K. , Qu Z. , Gao Y. , Thomsen H. , Turkin Y. , Zanini M. , W7-X Team the
Published: September 2021

In the Wendelstein 7-X (W7-X) stellarator, the vacuum rotational transform, ι, has a flat radial profile and does not cross any major rational resonance. Nevertheless, during plasma operation the ι‐profile can be strongly modified by electron cyclotron current drive in such a way that the resulting ι-profile passes through low-order rational values, and this can trigger magnetohydrodynamic (MHD) events. Indeed, W7-X plasmas are sometimes subject to repetitive collapses of core confinement, which can be observed regardless of the direction in which the EC current is driven. Even though the origin of these MHD instabilities is under investigation, the crashes may be connected to the formation of magnetic islands and magnetic reconnection. In the present work, we try to shed light on the dynamics of different events happening during the course of sawtooth cycles in W7-X by proposing a model that combines a slow current diffusion with a recipe for fast relaxation that conserves the corresponding helical flux (Kadomtsev 1975 Fiz. Plazmy
1 710–15). We also propose a simple model based on Taylor relaxation (Taylor 1974 Phys. Rev. Lett.
33 1139), (Taylor 1986 Rev. Mod. Phys.
58 741) to predict the nonlinear redistribution of plasma current caused by the largest of the observed events.
Plasma radiation behavior approaching high-radiation scenarios in W7-X
Authors: Zhang D. , Burhenn R. , Feng Y. , König R. , Buttenschön B. , Beidler C.D. , Hacker P. , Reimold F. , Thomsen H. , Laube R. , Klinger T. , Giannone L. , Penzel F. , Pavone A. , Krychowiak M. , Beurskens M. , Bozhenkov S. , Brunner J.K. , Effenberg F. , Fuchert G. , Gao Y. , Geiger J. , Hirsch M. , Höfel U. , Jakubowski M. , Knauer J. , Kwak S. , Laqua H.P. , Niemann H. , Otte M. , Pedersen T. Sunn , Pasch E. , Pablant N. , Rahbarnia K. , Svensson J. , Blackwell B. , Drews P. , Endler M. , Rudischhauser L. , Wang E. , Weir G. , Winters V. , the W7-X Team
Published: September 2021

The W7-X stellarator has so far performed experiments under both limiter and divertor conditions. The plasma is mostly generated by ECR-heating with powers up to 6.5 MW, and the plasma density is usually limited by the radiation losses from low-Z impurities (such as carbon and oxygen) released mainly from the graphite targets. The present work first summarizes the radiation loss fractions f
rad achieved in quasi-stationary hydrogen plasmas in both operational phases, and then shows how impurity radiation behaves differently with the two different boundary conditions as the plasma density increases. The divertor operation is emphasized and some beneficial effects (with respect to impurity radiation) are highlighted: (1) intensive radiation is located at the edge (r/a > 0.8) even at high radiation loss fractions, (2) the plasma remains stable up to f
rad approaching unity, (3) the reduction in the stored energy is about 10% for high f
rad scenarios. Moreover, effects of wall boronisation on impurity radiation profiles are also presented.
Screening for P- and K-solubilizing, and siderophore producing capacity of rhizobacteria from Khao Dawk Mali 105 Aromatic Rice
Authors: Chinachanta K , Shutsrirung A
Published: September 2021

Low nutrient status and high salinity have been identified as significant constraints for KDML105 aromatic rice production in the TKR region, Northeastern, Thailand. The use of PGPR can provides green alternatives to synthetic fertilizer in this region. In this study, therefore, rhizobacteria were isolated from KDML105 rice and evaluated for their potential in P and K solubilization, and siderophore production. The results indicated that 52.0, 21.5, 17.9, and 21.1% of 629 tested isolates, were able to solubilize P, K-mica, K-feldspar, and produce siderophore, respectively. At 0% NaCl the highest amount of solubilized P (35.6 mg L-1), K (49.5 mg L-1), and hydroxamate-type siderophore (618.3 μg L-1), were obtained from isolates ORF4-13, ORF15-23, and CRF16-3, respectively. Under salt stress, the amount of solubilized P of almost all the isolates increased with salt concentration up to 0.5% NaCl and declined thereafter, as compared to the control. In contrast, the amount of solubilized K progressively decreased with NaCl concentration. On the average, ORF15-23 exhibited promising ability in P and K solubilization under salt stress. The promising isolates obtained in this study should be evaluated for their effects on rice nutrients uptake and growth before developing them as biofertilizer.
Characterization and identification of lactic acid bacteria from Mexican stingless bees (Apidae: Meliponini)
Authors: Torres-Moreno R , Hemández-Sánchez Humberto S , Méndez-Tenorio A , Palmeros-Sánchez B , Melgar-Lalanne G
Published: September 2021

Stingless bees (family Apidae; tribe Meliponini), native from Mexico, are essential in tropical ecosystems. They are responsible for the pollination of many crops, native flora, and honey production. Lactic Acid Bacteria (LAB) are a regular host of the bee microbiota. LAB provide beneficial effects such as decreasing bacterial and parasitic pathogens infections and enhancing beehive honey production. Four different stingless bee species were sampled in the southeast of Mexico (Veracruz State) and identified as Melipona beecheii, Scaptotrigona pectoralis, Plebeia llorentei and Plebeia jatiformis. Twelve LAB strains were isolated from the bee gastrointestinal tract and characterised by microbiologic features, carbohydrates fermentation profile, antibiogram and phylogenetic reconstructions through distance and Bayesian inference methods, selecting two genes with hypervariable regions (16S rRNA and pheS). The species were characterised as gram-positive and catalase-negative as rods and cocci. Moreover, most of the species identified were able to use diverse polysaccharides as the only carbon source. Lactobacillaceae resulted in resistance to ciprofloxacin and Leuconstaceae to cotrimoxazole. Finally, ten strains could be identified by both phylogenetic reconstructions as Lactiplantibacillus plantarum (2), Weissella paramesenteroides (3), Leuconostoc citreum (2), and Apilactobacillus spp. (3). This is the first report of LAB isolated from Mexican stingless bees to the best of our knowledge.
Correlation functions as a tool to study collective behaviour phenomena in biological systems
Authors: Grigera Tomás S
Published: September 2021

Much of interesting complex biological behaviour arises from collective properties. Important information about collective behaviour lies in the time and space structure of fluctuations around average properties, and two-point correlation functions are a fundamental tool to study these fluctuations. We give a self-contained presentation of definitions and techniques for computation of correlation functions aimed at providing students and researchers outside the field of statistical physics a practical guide to calculating correlation functions from experimental and simulation data. We discuss some properties of correlations in critical systems, and the effect of finite system size, which is particularly relevant for most biological experimental systems. Finally we apply these to the case of the dynamical transition in a simple neuronal model.
Mirković–Vilonen basis in type 𝐴₁
Authors: Baumann Pierre , Demarais Arnaud
Published: September 2021

Let

G
G

be a connected reductive algebraic group over

C

\mathbb C

. Through the geometric Satake equivalence, the fundamental classes of the Mirković–Vilonen cycles define a basis in each tensor product

V
(

λ
1

)
⊗
⋯
⊗
V
(

λ
r

)

V(\lambda _1)\otimes \cdots \otimes V(\lambda _r)

of irreducible representations of

G
G

. We compute this basis in the case

G
=

S
L

2

(

C

)

G=\mathrm {SL}_2(\mathbb C)

and conclude that in this case it coincides with the dual canonical basis at

q
=
1

q=1

.
Clones and Clusters of Antimicrobial-ResistantKlebsiellaFrom Southwestern Nigeria
Authors: Afolayan Ayorinde O , Oaikhena Anderson O , Aboderin Aaron O , Olabisi Olatunde F , Amupitan Adewale A , Abiri Oyekola V , Ogunleye Veronica O , Odih Erkison Ewomazino , Adeyemo Abolaji T , Adeyemo Adeyemi T , Obadare Temitope O , Abrudan Monica , Argimón Silvia , David Sophia , Kekre Mihir , Underwood Anthony , Egwuenu Abiodun , Ihekweazu Chikwe , Aanensen David M , Okeke Iruka N ,   NIHR Global Health Research Unit on Genomic Surveillance of Antimicrobial Resistance, Abudahab Khalil , Harste Harry , Muddyman Dawn , Taylor Ben , Wheeler Nicole , Donado-Godoy Pilar , Fabian Bernal Johan , Arevalo Alejandra , Fernanda Valencia Maria , Osma Castro Erik C D , Ravikumar K L , Nagaraj Geetha , Shamanna Varun , Govindan Vandana , Prabhu Akshata , Sravani D , Shincy M R , Rose Steffimole , Ravishankar K N , Ajiboye Jolaade J , Carlos Celia , Lagrada Marietta L , Macaranas Polle Krystle V , Olorosa Agnettah M , Gayeta June M , Herrera Elmer M , Molloy Ali , Stelling John , Vegvari Carolin
Published: September 2021

Background

Klebsiella pneumoniae is a World Health Organization high-priority antibiotic-resistant pathogen. However, little is known about Klebsiella lineages circulating in Nigeria.

Methods

We performed whole-genome sequencing (WGS) of 141 Klebsiella isolated between 2016 and 2018 from clinical specimens at 3 antimicrobial-resistance (AMR) sentinel surveillance tertiary hospitals in southwestern Nigeria. We conducted in silico multilocus sequence typing; AMR gene, virulence gene, plasmid, and K and O loci profiling; as well as phylogenetic analyses, using publicly available tools and Nextflow pipelines.

Results

Phylogenetic analysis revealed that the majority of the 134 K. pneumoniae and 5 K. quasipneumoniae isolates from Nigeria characterized are closely related to globally disseminated multidrug-resistant clones. Of the 39 K. pneumoniae sequence types (STs) identified, the most common were ST307 (15%), ST5241 (12%), ST15 (~9%), and ST25 (~6%). ST5241, 1 of 10 novel STs detected, is a single locus variant of ST636 carrying dfrA14, tetD, qnrS, and oqxAB resistance genes. The extended-spectrum β-lactamase (ESBL) gene blaCTX_M-15 was seen in 72% of K. pneumoniae genomes, while 8% encoded a carbapenemase. No isolate carried a combination of carbapenemase-producing genes. Four likely outbreak clusters from 1 facility, within STs 17, 25, 307, and 5241, were ESBL but not carbapenemase-bearing clones.

Conclusions

This study uncovered known and novel K. pneumoniae lineages circulating in 3 hospitals in Southwest Nigeria that include multidrug-resistant ESBL producers. Carbapenemase-producing isolates remain uncommon. WGS retrospectively identified outbreak clusters, pointing to the value of genomic approaches in AMR surveillance for improving infection prevention and control in Nigerian hospitals.
Minimally Invasive Tissue Sampling Surveillance Alliance—Facilitating the Expansion of Pathology-Based Mortality Surveillance
Authors: Goco Norman J , McClure Elizabeth M , Rakislova Natalia , Bassat Quique
Published: September 2021

The Minimally Invasive Tissue Sampling (MITS) Surveillance Alliance was created with funding from the Bill & Melinda Gates Foundation to expand pathology-based mortality surveillance and to support the generation of improved cause-of-death (CoD) data. MITS, also known as minimally invasive autopsy, has evolved to become an important tool to improve CoD ascertainment. Here, we describe the 18 articles included in this supplement that present advanced methods for improving MITS and related areas of research, summarize the expansion of the use of MITS, report on findings from a variety of research projects, and address the importance of postmortem approaches taken during the novel coronavirus disease 2019 pandemic. Support by the scientific and global health community for enhancements and innovation is needed for the broader adoption of MITS-informed CoD as a critical tool to better understand mortality in low- and middle-income countries and identify interventions for the prevention of premature death.