bluuebunny/crossref_metadata_2025 huggingface dataset:
Mechanical properties of stabilized nanocrystalline FCC metals
Authors: Spearot Douglas E. , Tucker Garritt J. , Gupta Ankit , Thompson Gregory B.
Published: September 2019

In this perspective, recent advances and current research challenges concerning the mechanical properties of stabilized nanocrystalline face-centered cubic (FCC) metals are discussed. First, a brief review of key experiments and modeling efforts over the last two decades is provided, with a focus on elucidating the mechanisms associated with plastic yield, hardening, and microstructure stabilization in nanocrystalline metals. This prior work has provided an understanding of the transition between dislocation-based and grain boundary-mediated mechanisms in plasticity and has identified several strategies to mitigate temperature or stress driven grain growth. Yet, the consequence of various stabilization methods on mechanical properties is not well understood. Future research challenges are presented in order to address this scientific gap, most critically the need to include grain boundary chemistry or grain boundary phases resulting from stabilization methods in new mechanistic theories for mechanical properties of nanocrystalline FCC metals.
Basic physical properties of cubic boron arsenide
Authors: Kang Joon Sang , Li Man , Wu Huan , Nguyen Huuduy , Hu Yongjie
Published: September 2019

Cubic boron arsenide (BAs) is an emerging semiconductor material with a record-high thermal conductivity subject to intensive research interest for its applications in electronics thermal management. However, many fundamental properties of BAs remain unexplored experimentally since high-quality BAs single crystals have only been obtained very recently. Here, we report the systematic experimental measurements of important physical properties of BAs, including the bandgap, optical refractive index, elastic modulus, shear modulus, Poisson's ratio, thermal expansion coefficient, and heat capacity. In particular, light absorption and Fabry–Pérot interference were used to measure an optical bandgap of 1.82 eV and a refractive index of 3.29 (657 nm) at room temperature. A picoultrasonic method, based on ultrafast optical pump probe spectroscopy, was used to measure a high elastic modulus of 326 GPa, which is twice that of silicon. Furthermore, temperature-dependent X-ray diffraction was used to measure a linear thermal expansion coefficient of 3.85 × 10−6 K−1; this value is very close to prototype semiconductors such as GaN, which underscores the promise of BAs for cooling high power and high frequency electronics. We also performed ab initio theory calculations and observed good agreement between the experimental and theoretical results. Importantly, this work aims to build a database (Table I) for the basic physical properties of BAs with the expectation that this semiconductor will inspire broad research and applications in electronics, photonics, and mechanics.
Electronic structure of interstitial hydrogen in In-Ga-Zn-O semiconductor simulated by muon
Authors: Kojima K. M. , Hiraishi M. , Okabe H. , Koda A. , Kadono R. , Ide K. , Matsuishi S. , Kumomi H. , Kamiya T. , Hosono H.
Published: September 2019

We report on the local electronic structure of an interstitial muon (Mu) as pseudohydrogen in In-Ga-Zn oxide (IGZO) semiconductors studied by muon spin rotation/relaxation (μSR) experiment. In polycrystalline (c-) IGZO, it is inferred that Mu is in a diamagnetic state, where the μSR time spectra under zero external field are perfectly described by the Gaussian Kubo-Toyabe relaxation function with the linewidth Δ serving as a sensitive measure for the random local fields from In/Ga nuclear magnetic moments. The magnitude of Δ combined with the density functional theory calculations for H (to mimic Mu) suggests that Mu occupies Zn-O bond-center site (MuBC) similar to the case in crystalline ZnO. This implies that the diamagnetic state in c-IGZO corresponds to MuBC+, thus serving as an electron donor. In amorphous (a-) IGZO, the local Mu structure in the as-deposited films is nearly identical to that in c-IGZO, suggesting MuBC+ for the electronic state. In contrast, the diamagnetic signal in heavily hydrogenated a-IGZO films exhibits the Lorentzian Kubo-Toyabe relaxation, implying that Mu accompanies more inhomogeneous distribution of the neighboring nuclear spins that may involve a Mu− H−-complex state in an oxygen vacancy.
Discovering mean residence time and escape probability from data of stochastic dynamical systems
Authors: Wu Dengfeng , Fu Miaomiao , Duan Jinqiao
Published: September 2019

We present a method to learn mean residence time and escape probability from data modeled by stochastic differential equations. This method is a combination of machine learning from data (to extract stochastic differential equations as models) and stochastic dynamics (to quantify dynamical behaviors with deterministic tools). The goal is to learn and understand stochastic dynamics based on data. This method is applicable to sample path data collected from complex systems, as long as these systems can be modeled as stochastic differential equations.
Water wettability of graphene and graphite, optimization of solid-liquid interaction force fields, and insights from mean-field modeling
Authors: Ramos-Alvarado Bladimir
Published: September 2019

A simple mean-field model of carbon-water interactions was developed to predict the binding energy in classical simulations for graphene and graphite surfaces. Using this model, analytical expressions were derived to link microscopic parameters (such as the binding energy) with macroscopic wetting behavior (work of adhesion). Adding these expressions to an optimized mean-field model of wettability, the empirical relationship between the binding energy and the work of adhesion in classical simulations was formally explained. An orientation dependent mean-field model and the insight gained from mean field modeling of the binding energy were used to develop a method to optimize comprehensive carbon-water interaction potentials, where molecular orientation is taken into account using data from state-of-the-art high-resolution multibody electronic structure methods. This method eliminates the ambiguity of finding a set of four parameters by informing on the bounds for the parameter-search process using physics-informed constraints.
Interevent time distribution, burst, and hybrid percolation transition
Authors: Park Jinha , Yi Sudo , Choi K. , Lee Deokjae , Kahng B.
Published: September 2019

Understanding of a hybrid percolation transitions (HPTs) induced by cluster coalescence, exhibiting a jump in the giant cluster size and a critical behavior of finite clusters, is fundamental and intriguing. Here, we uncover the underlying mechanism using the so-called restricted-random network model, in which clusters are ranked by size and partitioned into small- and large-cluster sets. As clusters are merged and their rankings are updated, they may move back and forth across the set boundary. The intervals of these crossings exhibit a self-organized critical (SOC) behavior with two power-law exponents. During this process, a bump is formed and eliminated in the cluster size distribution, characterizing the criticality of the HPT. This SOC behavior is in contrast to the critical branching process, which governs the avalanche dynamics of the HPT in the pruning process. Finally, we find that a burst of such crossing events occurs and signals the upcoming abrupt transition.
Inorganic vacancy-ordered perovskite Cs2SnCl6:Bi/GaN heterojunction photodiode for narrowband, visible-blind UV detection
Authors: Shao Dali , Zhu Weiguang , Xin Guoqing , Lian Jie , Sawyer Shayla
Published: September 2019

A heterojunction photodiode was fabricated from Bi doped Cs2SnCl6 nanoparticles (Cs2SnCl6:Bi NPs) spin-coated on an epitaxially grown GaN substrate. With the back illumination configuration, the heterojunction photodiode demonstrated excellent narrow-band UV sensing capability with a full wavelength of half maximum of 18 nm and a maximum detectivity of 1.2 × 1012 jones, which is promising for biomedical applications. In addition to the excellent narrow band UV sensitivity, the device also demonstrated a large linear dynamic range of 71 decibels (dB) and a fast photoresponse speed (a rise time of 0.75 μs and a fall time of 0.91 μs). The excellent performance is attributed to excellent carrier separation efficiency at the heterojunction interface and improved carrier collection efficiency through the multi-walled carbon nanotube (MWCNT) network. All the above advantages are of great importance for commercial deployment of perovskite-based photodetectors.
Pollen biology of the serpentine-endemic Orobanche nowackiana (Orobanchaceae) from Albania
Authors: Pavlova Dolja , Bani Aida
Published: September 2019

The holoparasite flowering plant Orobanche nowackiana Markgr. is a rare endemic plant that parasitises the Ni hyperaccumulator species Alyssum murale Waldst. and Kit. in Komjan Mt. (Albania). The purpose of this study was to establish baseline data concerning aspects of its pollen biology. To achieve this goal three objectives were addressed: (1) describe pollen morphology; (2) study pollen production and fertility/sterility; (3) study the localisation of metals in anthers and pollen. Pollen morphology was investigated with light microscope and scanning electron microscope (SEM) observations. The pollen grains are 3-colpate, most often oblate-spheroidal, with long colpi reaching the poles. The ornamentation is microreticulate. The anther and pollen grains were micromorphologically analysed by SEM coupled with an energy-dispersive X-ray probe (SEM-EDX). Low concentration of Ni was recorded for anthers (0.38%) and pollen (0.1–5.6%). Variation in pollen production was found for the flowers of the same individual. The mean pollen production per flower and stamen was 59365 and 14938 pollen grains respectively. The sterile pollen was above the limit considered as a normal abortion and was between 10.1 and 38.0%. From a palynological point of view our results are important for taxonomy and support keeping the species in the genus Phelipanche.
The Microbiologists’ Warning: a Warning from All Microbiologists’ to Humanity
Authors: Cavicchioli Rick
Published: September 2019

The Microbiologists’ Warning is a Consensus Statement proclaiming that microorganisms are so critical to achieving an environmentally sustainable future that ignoring them risks the fate of Humanity. It aims to raise awareness of the microbial world and make a call to action for microbiologists to become increasingly engaged in, and microbial research to become increasingly infused into, the frameworks for addressing climate change. We must learn not just how microorganisms affect climate change (including production and consumption of greenhouse gases), but also how they will be affected by climate change and other human activities.
Maternal viral infection causes global alterations in porcine fetal microglia
Authors: Antonson Adrienne M. , Lawson Marcus A. , Caputo Megan P. , Matt Stephanie M. , Leyshon Brian J. , Johnson Rodney W.
Published: September 2019

Significance

Mental health disorders account for approximately 14% of the worldwide burden of disease and affect people of all age groups and socioeconomic statuses. Prenatal exposure to maternal infection increases the risk of developing certain mental health disorders, most notably schizophrenia and autism. Maternally derived cytokines, up-regulated during infection, may lead to an aberrant proinflammatory and phagocytic shift in fetal microglia, the resident immune cells of the brain. As these cells perform essential processes that aid in the highly orchestrated progression of brain development, modifications in their prenatal phenotype could be detrimental. Using swine, a highly translatable animal model, we show that fetal microglia activity is globally altered by maternal infection, a finding that could have far-reaching implications for neuropsychiatric disorders.
High-resolution limited-angle phase tomography of dense layered objects using deep neural networks
Authors: Goy Alexandre , Rughoobur Girish , Li Shuai , Arthur Kwabena , Akinwande Akintunde I. , Barbastathis George
Published: September 2019

Significance

We demonstrate that it is possible to use deep neural networks to produce tomographic reconstructions of dense layered objects with small illumination angle as low as 10 °. It is also shown that a DNN trained on synthetic data can generalize well to and produce reconstructions from experimental measurements. This work has application in the field of X-ray tomography for the inspection of integrated circuits and other materials studies.
Toward electrochemical synthesis of cement—An electrolyzer-based process for decarbonating CaCO
3
while producing useful gas streams
Authors: Ellis Leah D. , Badel Andres F. , Chiang Miki L. , Park Richard J.-Y. , Chiang Yet-Ming
Published: September 2019

Cement production is currently the largest single industrial emitter of CO
2
, accounting for ∼8% (2.8 Gtons/y) of global CO
2
emissions. Deep decarbonization of cement manufacturing will require remediation of both the CO
2
emissions due to the decomposition of CaCO
3
to CaO and that due to combustion of fossil fuels (primarily coal) in calcining (∼900 °C) and sintering (∼1,450 °C). Here, we demonstrate an electrochemical process that uses neutral water electrolysis to produce a pH gradient in which CaCO
3
is decarbonated at low pH and Ca(OH)
2
is precipitated at high pH, concurrently producing a high-purity O
2
/CO
2
gas mixture (1:2 molar ratio at stoichiometric operation) at the anode and H
2
at the cathode. We show that the solid Ca(OH)
2
product readily decomposes and reacts with SiO
2
to form alite, the majority cementitious phase in Portland cement. Electrochemical calcination produces concentrated gas streams from which CO
2
may be readily separated and sequestered, H
2
and/or O
2
may be used to generate electric power via fuel cells or combustors, O
2
may be used as a component of oxyfuel in the cement kiln to improve efficiency and lower CO
2
emissions, or the output gases may be used for other value-added processes such as liquid fuel production. Analysis shows that if the hydrogen produced by the reactor were combusted to heat the high-temperature kiln, the electrochemical cement process could be powered solely by renewable electricity.
Genomic analysis of siderophore β-hydroxylases reveals divergent stereocontrol and expands the condensation domain family
Authors: Reitz Zachary L. , Hardy Clifford D. , Suk Jaewon , Bouvet Jean , Butler Alison
Published: September 2019

Significance

Bacteria produce siderophores to sequester iron(III). Genome mining of nonribosomal peptide synthetases predicts partial structures of peptidic siderophores; however, current tools cannot reliably predict which aspartate and histidine residues will be hydroxylated to form bidentate chelating groups, nor the resulting stereochemistry. We identified 2 functional subtypes of nonheme Fe(II)/α-ketoglutarate–dependent aspartyl β-hydroxylases in siderophore biosynthetic gene clusters and one type of histidyl β-hydroxylase. Stand-alone genes encode one class of aspartyl β-hydroxylases and the histidyl β-hydroxylases, while the second class of aspartyl β-hydroxylases is encoded within a domain of a nonribosomal peptide synthetase (NRPS) gene. Each aspartyl β-hydroxylase subtype effects distinct diastereoselectivity. Mapping the β-OHAsp diastereomers in siderophores to the phylogenetic tree of β-hydroxylases enables prediction of β-OHAsp stereochemistry in silico.
Conformational equilibrium defines the variable induction of the multidrug-binding transcriptional repressor QacR
Authors: Takeuchi Koh , Imai Misaki , Shimada Ichio
Published: September 2019

Significance

Multidrug resistance (MDR) constitutes a major obstacle in the treatment of infectious diseases, as well as human cancers, even in developed countries. This study deciphers the structural mechanism that dictates the promiscuous multidrug binding to the variable transcriptional regulation of QacR, the major multidrug-binding transcriptional repressor in pathogenic bacteria
Staphylococcus aureus
. The transcriptional level of the downstream transporter gene,
qacA
, is dynamically regulated by QacR via the relative populations of inducive versus repressive conformations in the molecule. The conformational equilibrium also defines the basal activity of the MDR system, as well as the elevated transcription levels with the constitutively active mutants. Our structural definition provides an important advance in understanding and potentially targeting the MDR system.
Selection of endurance capabilities and the trade-off between pressure and volume in the evolution of the human heart
Authors: Shave Robert E. , Lieberman Daniel E. , Drane Aimee L. , Brown Marcel G. , Batterham Alan M. , Worthington Steven , Atencia Rebeca , Feltrer Yedra , Neary Jennifer , Weiner Rory B. , Wasfy Meagan M. , Baggish Aaron L.
Published: September 2019

Significance

Unlike other great apes, humans evolved multisystem capabilities for moderate-intensity EPA, but it is unknown if selection acted similarly on the heart. We present data from a sample of humans, chimpanzees, and gorillas showing that the human (LV) evolved numerous features that help to augment stroke volume (SV), enabling moderate-intensity EPA. We also show that phenotypic plasticity of the human LV trades off pressure adaptations for volume capabilities, becoming more similar to a chimpanzee-like heart in response to physical inactivity or chronic pressure loading. Consequently, the derived human heart appears partly dependent upon moderate EPA and its absence, in combination with a highly processed diet, likely contributes to the modern epidemic of hypertensive heart disease.
T cell activation and immune synapse organization respond to the microscale mechanics of structured surfaces
Authors: Jin Weiyang , Tamzalit Fella , Chaudhuri Parthiv Kant , Black Charles T. , Huse Morgan , Kam Lance C.
Published: September 2019

Cells have the remarkable ability to sense the mechanical stiffness of their surroundings. This has been studied extensively in the context of cells interacting with planar surfaces, a conceptually elegant model that also has application in biomaterial design. However, physiological interfaces are spatially complex, exhibiting topographical features that are described over multiple scales. This report explores mechanosensing of microstructured elastomer surfaces by CD4
+
T cells, key mediators of the adaptive immune response. We show that T cells form complex interactions with elastomer micropillar arrays, extending processes into spaces between structures and forming local areas of contraction and expansion dictated by the layout of microtubules within this interface. Conversely, cytoskeletal reorganization and intracellular signaling are sensitive to the pillar dimensions and flexibility. Unexpectedly, these measures show different responses to substrate rigidity, suggesting competing processes in overall T cell mechanosensing. The results of this study demonstrate that T cells sense the local rigidity of their environment, leading to strategies for biomaterial design.
Organization of fast and slow chromatin revealed by single-nucleosome dynamics
Authors: Ashwin S. S. , Nozaki Tadasu , Maeshima Kazuhiro , Sasai Masaki
Published: September 2019

Significance

Recent live cell imaging has revealed that chromatin is not a static, rigid structure but is dynamically fluctuating in cells. We study chromatin motion by using single-nucleosome tracking data in living human cells. The distribution of single-nucleosome movement shows a distinct 2-peak feature: fast and slow fractions. Nucleosome movement is investigated using statistical analyses and a polymer model to elucidate the mechanism of dynamic organization of fast and slow chromatin.
Arabidopsis
H
+
-ATPase AHA1 controls slow wave potential duration and wound-response jasmonate pathway activation
Authors: Kumari Archana , Chételat Aurore , Nguyen Chi Tam , Farmer Edward E.
Published: September 2019

Significance

Phosphorylation (P)-type ATPases act to maintain and modulate charge distribution across membranes and these proteins have been coopted for electrical signaling in animals. When wounded, membranes in the leaves of
Arabidopsis thaliana
depolarize rapidly. This is followed by a slower repolarization phase. We found that the proton pump AHA1 acted to control membrane potential when these plants were wounded. Specifically, the repolarization phase in
aha1
mutants is prolonged relative to that in wild-type plants. In parallel, the jasmonate defense pathway is activated strongly and the mutant plants are better defended against herbivores than the wild type. We reveal that plants, like animals, use P-type ATPases in electrical signaling and show that AHA1 couples membrane potential to anti-herbivore defense.
Immunization against poly-
N
-acetylglucosamine reduces neutrophil activation and GVHD while sparing microbial diversity
Authors: Hülsdünker Jan , Thomas Oliver S. , Haring Eileen , Unger Susanne , Gonzalo Núñez Nicolás , Tugues Sonia , Gao Zhan , Duquesne Sandra , Cywes-Bentley Colette , Oyardi Ozlem , Kirschnek Susanne , Schmitt-Graeff Annette , Pabst Oliver , Koenecke Christian , Duyster Justus , Apostolova Petya , Blaser Martin J. , Becher Burkhard , Pier Gerald B. , Häcker Georg , Zeiser Robert
Published: September 2019

Significance

Our previous work has shown that bacterial-induced activation of neutrophil granulocytes after allogeneic hematopoietic cell transplantation promotes acute graft-versus-host disease (GVHD). In patients, depleting neutrophils is not possible because they mediate protection from invading bacteria and antibiotic treatment needed to reduce bacteria-induced neutrophil activation affects protective intestinal microbiota. Here, we describe that active and passive immunization against the conserved microbial surface polysaccharide poly-
N
-acetylglucosamine leads to killing of invading bacteria, which reduces the uncontrolled neutrophil activation, and thereby opens a new avenue to interfere with acute GVHD without affecting commensal intestinal microbial diversity.
The gut microbiome regulates host glucose homeostasis via peripheral serotonin
Authors: Martin Alyce M. , Yabut Julian M. , Choo Jocelyn M. , Page Amanda J. , Sun Emily W. , Jessup Claire F. , Wesselingh Steve L. , Khan Waliul I. , Rogers Geraint B. , Steinberg Gregory R. , Keating Damien J.
Published: September 2019

The gut microbiome is an established regulator of aspects of host metabolism, such as glucose handling. Despite the known impacts of the gut microbiota on host glucose homeostasis, the underlying mechanisms are unknown. The gut microbiome is also a potent mediator of gut-derived serotonin synthesis, and this peripheral source of serotonin is itself a regulator of glucose homeostasis. Here, we determined whether the gut microbiome influences glucose homeostasis through effects on gut-derived serotonin. Using both pharmacological inhibition and genetic deletion of gut-derived serotonin synthesis, we find that the improvements in host glucose handling caused by antibiotic-induced changes in microbiota composition are dependent on the synthesis of peripheral serotonin.
Tubulin lattice in cilia is in a stressed form regulated by microtubule inner proteins
Authors: Ichikawa Muneyoshi , Khalifa Ahmad Abdelzaher Zaki , Kubo Shintaroh , Dai Daniel , Basu Kaustuv , Maghrebi Mohammad Amin Faghfor , Vargas Javier , Bui Khanh Huy
Published: September 2019

Cilia, the hair-like protrusions that beat at high frequencies to propel a cell or move fluid around are composed of radially bundled doublet microtubules. In this study, we present a near-atomic resolution map of the
Tetrahymena
doublet microtubule by cryoelectron microscopy. The map demonstrates that the network of microtubule inner proteins weaves into the tubulin lattice and forms an inner sheath. From mass spectrometry data and de novo modeling, we identified Rib43a proteins as the filamentous microtubule inner proteins in the protofilament ribbon region. The Rib43a–tubulin interaction leads to an elongated tubulin dimer distance every 2 dimers. In addition, the tubulin lattice structure with missing microtubule inner proteins (MIPs) by sarkosyl treatment shows significant longitudinal compaction and lateral angle change between protofilaments. These results are evidence that the MIPs directly affect and stabilize the tubulin lattice. It suggests that the doublet microtubule is an intrinsically stressed filament and that this stress could be manipulated in the regulation of ciliary waveforms.
Force-induced recruitment of cten along keratin network in epithelial cells
Authors: Cheah Joleen S. , Jacobs Kyle A. , Heinrich Volkmar , Lo Su Hao , Yamada Soichiro
Published: September 2019

The cytoskeleton provides structural integrity to cells and serves as a key component in mechanotransduction. Tensins are thought to provide a force-bearing linkage between integrins and the actin cytoskeleton; yet, direct evidence of tensin’s role in mechanotransduction is lacking. We here report that local force application to epithelial cells using a micrometer-sized needle leads to rapid accumulation of cten (tensin 4), but not tensin 1, along a fibrous intracellular network. Surprisingly, cten-positive fibers are not actin fibers; instead, these fibers are keratin intermediate filaments. The dissociation of cten from tension-free keratin fibers depends on the duration of cell stretch, demonstrating that the external force favors maturation of cten−keratin network interactions over time and that keratin fibers retain remarkable structural memory of a cell’s force-bearing state. These results establish the keratin network as an integral part of force-sensing elements recruiting distinct proteins like cten and suggest the existence of a mechanotransduction pathway via keratin network.
Genetic ablation of acid ceramidase in Krabbe disease confirms the psychosine hypothesis and identifies a new therapeutic target
Authors: Li Yedda , Xu Yue , Benitez Bruno A. , Nagree Murtaza S. , Dearborn Joshua T. , Jiang Xuntian , Guzman Miguel A. , Woloszynek Josh C. , Giaramita Alex , Yip Bryan K. , Elsbernd Joseph , Babcock Michael C. , Lo Melanie , Fowler Stephen C. , Wozniak David F. , Vogler Carole A. , Medin Jeffrey A. , Crawford Brett E. , Sands Mark S.
Published: September 2019

Significance

This study identifies the source of the toxic glycolipid, galactosylsphingosine (psychosine), which accumulates in the inherited demyelinating disorder, Krabbe disease. It was suggested that psychosine was produced anabolically by the addition of galactose to sphingosine. We show here instead that psychosine is derived from the catabolic deacylation of galactosylceramide by the lysososomal enzyme acid ceramidase. These findings allow us to test and confirm the ∼45-y-old “psychosine hypothesis,” which states that psychosine causes the pathological and clinical signs of Krabbe disease. Finally, these data suggest that acid ceramidase could be a substrate reduction target for treating Krabbe disease. We show that pharmacological inhibition of acid ceramidase significantly increases the life span of the twitcher mouse, an authentic murine model of Krabbe disease.
Rebound effects in persuasion: considering potential ironic effects of suppression and correction / Efectos rebote en la persuasión: una consideración de los posibles efectos irónicos de la supresión y la corrección
Authors: Silva Pedro P. , Garcia-Marques Teresa , Wegener Duane T.
Published: September 2019

Previous theory and research in persuasion has failed to examine possible ironic effects of attempting to suppress or to correct for influences of a potentially biasing source. Yet, because people often encounter sets of persuasive communications in order (e.g., in advertising), such rebound effects seem possible. Data on such possibilities are scarce, however. Here we present a relevant study. It followed the typical single-shot persuasive message with a second message on an unrelated topic but employed a similar type of (potentially biasing — attractive or unattractive) source. Attitudes following the second communication showed increased source impact for participants asked to suppress source-related thoughts during the first message (especially when the second message was encountered under load). Instructions to correct for potential source effects during the first message did not show ironic effects following the second message. This relatively small study is not enough to make definitive claims, but it suggests that rebound effects of thought suppression are possible in (repeated) persuasion settings. Future research and open questions regarding ironic effects are discussed.
Pre‐exercise hypohydration prevalence in soccer players: A quantitative systematic review.
Authors: Chapelle L. , Tassignon B. , Rommers N. , Mertens E. , Mullie P. , Clarys P.
Published: September 2019

Pre‐exercise hypohydration can impair soccer performance and has been extensively studied in different soccer populations. Therefore, the aim of this systematic review was to report hypohydration prevalence, measured by blood or urine samples, in different soccer populations based on sex (males and females), performance level (professional and recreational players) and context (training sessions and games). The Pubmed, Web of Science and SPORTDiscus databases were systematically searched until November 2018. Data were pooled to compare hypohydration prevalence between the different subgroups. Following the systematic search selection process, 24 studies were included. The results indicated that overall pre‐exercise hypohydration prevalence was 63.3%, 37.4% and 58.8% for urine specific gravity (USG), urine osmolality (U Osm) and urine colour, respectively. Furthermore, no study implemented blood samples to examine hypohydration prevalence in soccer players. The subgroup analyses using USG data indicated that pre‐exercise hypohydration prevalence was significantly higher amongst males (66.0%; p = 0.001), professional soccer players (66.2%; p = 0.020) and before a training session (79.6%; p < 0.001). Pre‐exercise hypohydration prevalence was 46.8% among female soccer players, 55.6% in recreational soccer players and 41,3% before a game. The subgroup analyses using U Osm data indicated that hypohydration prevalence was significantly higher before a training session (52.6%; p = 0.023). Based on these results, it can be concluded that hypohydration prevalence in soccer players is of major concern. Future research should explore how pre‐exercise hydration status can be improved in a sustainable way.
Muscle and cerebral oxygenation during exercise in athletes with exercise‐induced hypoxemia: A comparison between sea level and acute moderate hypoxia
Authors: Raberin Antoine , Meric Henri , Mucci Patrick , Lopez Ayerbe Jorge , Durand Fabienne
Published: September 2019

The objective of the present study was to evaluate the influence of exercise‐induced hypoxemia (EIH) on muscle and cerebral oxygenation responses during maximal exercise in normoxia and in acute moderate hypoxia (fraction of inspired oxygen: 15.3%, 2400 m). EIH was defined as a drop in hemoglobin saturation of at least 4% for at least three consecutive minutes during maximal exercise at sea level. Twenty‐five athletes performed incremental treadmill tests to assess maximal oxygen consumption (VO2max) in normoxia and in hypoxia. Oxygenation of the vastus lateralis muscle and the left prefrontal cortex of the brain was monitored using near‐infrared spectroscopy. During the normoxic test, 15 athletes exhibited EIH; they displayed a larger change in muscle levels of oxyhemoglobin (ΔO2Hb) (p = 0.04) and a greater change in cerebral levels of deoxyhemoglobin (ΔHHb) (p = 0.02) than athletes without EIH (NEIH group). During the hypoxic test, muscle ΔO2Hb was lower in the EIH group than in the NEIH group (p = 0.03). At VO2max, hypoxia was associated with a smaller cerebral ΔO2Hb in both groups, and a greater cerebral ΔHHb compared to normoxia in the NEIH group only (p = 0.02). No intergroup differences in changes in muscle oxygenation were observed. The severity of O2 arterial desaturation was negatively correlated with changes in total muscle hemoglobin in normoxia (r = −0.48, p = 0.01), and positively correlated with the cerebral ΔHHb in normoxia (r = 0.45, p = 0.02). The occurrence of EIH at sea level was associated with specific muscle and cerebral oxygenation responses to exercise under both normoxia and moderate hypoxia.
The environment of C- and S-shaped radio galaxies
Authors: Liu Yu-Xing , Xu Hai-Guang , Zheng Dong-Chao , Li Wei-Tian , Zhu Zheng-Hao , Ma Zhi-Xian , Lian Xiao-Li
Published: September 2019

We study the environment of radio galaxies with different morphological types using the Proctor sample, which was built from the Faint Images of the Radio Sky at Twenty-Centimeters (FIRST) survey archive. Among the 15 radio galaxy types classified by Proctor, 199 C-shaped (i.e., wide- or narrow-angle tail) and 203 S-shaped (i.e., S- or Z-shaped) sources are selected in this work, which are located in the redshift range of 0.02 < z < 1, because these two subsamples are relatively larger than the other subsamples in the Proctor sample. By cross-matching these radio galaxies with the optical sources drawn from the Sloan Digital Sky Survey (SDSS) database and counting the SDSS sources with an r-band absolute magnitude brighter than −19 located within a 0.5 Mpc distance around each source (i.e., the richness), we find that the fraction of C-shaped sources with a richness above 10 is larger than that of S-shaped sources. We have also correlated the radio galaxies in our sample with the brightest cluster galaxies (BCGs) defined in the NASA/IPAC Extragalactic Database (NED), and infer that the C-shaped sources are more likely to be BCGs than the S-shaped sources. These results support the idea that C-shaped radio galaxies often reside in a richer environment than radio galaxies with other morphological types.
Non-locality and quasiclassical reality in Kent’s formulation of relativistic quantum theory
Authors: Butterfield J , Marsh B
Published: September 2019

We report Adrian Kent’s proposed framework for a realist, one-world, Lorentz-invariant formulation of quantum theory. The idea is to postulate a final boundary condition: in effect, a late-time distribution of mass-energy recording how photons scattered off macroscopic objects. Nature selects this final boundary condition with the orthodox late-time Born probability; and this defines the probability space of events, to give a realist quantum theory. We emphasize two topics. First, we consider this formulation’s verdicts about traditional locality conditions, such as Outcome Independence and Parameter Independence. Second, we discuss a possible amendment to Kent’s proposal that, roughly speaking, allows for the emergence of a quasiclassical history even when mass-energy is shielded or delayed from appearing in the final boundary condition.
A new rule for quantization that resolves all problems
Authors: Klauder John R
Published: September 2019

While canonical quantization solves many problems there are some problems where it fails. A close examination of the classical/quantum connection leads to a new connection that permits quantum and classical realms to coexist, as is the case in the real world. For those problems for which conventional quantization works well, the new procedures yield identical results. However, we offer an example that fails when quantized conventionally but succeeds when quantized with the new procedures.
Necessary and sufficient conditions for macrorealism using two- and three-time Leggett-Garg inequalities
Authors: Halliwell J J
Published: September 2019

The Leggett-Garg (LG) inequalities were introduced, as a temporal parallel of the Bell inequalities, to test macroscopic realism – the view that a macroscopic system evolving in time possesses definite properties which can be determined without disturbing the future or past state. The original LG inequalities are only a necessary condition for macrorealism, and are therefore not a decisive test. We argue, for the case of measurements of a single dichotomic variable Q, that when the original four three-time LG inequalities are augmented with a set of twelve two-time inequalities also of the LG form, Fine’s theorem applies and these augmented conditions are then both necessary and sufficient. A comparison is carried out with the alternative necessary and sufficient conditions for macrorealism based on no-signaling in time conditions which ensure that all probabilities for Q at one and two times are independent of whether earlier or intermediate measurements are made. We argue that the two tests differ in their implementation of the key requirement of non-invasive measurability so are testing different notions of macrorealism, and these notions are elucidated.
Combinatorial Quantum Gravity: Emergence of Geometric Space from Random Graphs
Authors: Kelly C , Trugenberger C A
Published: September 2019

We review and extend the recently proposed model of combinatorial quantum gravity. Contrary to previous discrete approaches, this model is defined on (regular) random graphs and is driven by a purely combinatorial version of Ricci curvature, the Ollivier curvature, defined on generic metric spaces equipped with a Markov chain. It dispenses thus of notions such as simplicial complexes and Regge calculus and is ideally suited to extend quantum gravity to combinatorial structures which have a priori nothing to do with geometry. Indeed, our results show that geometry and general relativity emerge from random structures in a second-order phase transition due to the condensation of cycles on random graphs, a critical point that defines quantum gravity non-perturbatively according to asymptotic safety. In combinatorial quantum gravity the entropy area law emerges naturally as a consequence of infinite-dimensional critical behaviour on networks rather than on lattices. We propose thus that the entropy area law is a signature of the random graph nature of space-(time) on the smallest scales.
On the hurricane collective molecular dynamics
Authors: Meyer Gabriel , Vitiello Giuseppe
Published: September 2019

We study the molecular dynamics underlying the formation and the evolution of hurricanes. The giant global structure of hurricanes cannot be solely the results of random molecular kinematics. We show that the non-stationary, topologically non-trivial hurricane behavior is the manifestation of the collective dynamics at the molecular level. This is described in terms of spontaneous breakdown of the rotational symmetry of the water molecule electrical dipoles. The long range molecular correlations generated as a consequence of the spontaneous breakdown of symmetry are responsible of the large scale collective motion resulting in the hurricane structure. The critical non-stationary dynamics is analyzed in terms of the non-stationary time dependent Ginzburg-Landau equation leading to the vortex equation. Phase transition, criticality, temperature dependence, energy exchanges and entropy are studied. Energy storage and dissipation processes in the coherent state dynamics are analyzed. Finally the self-similar fractal structure of the hurricane is shown to be the manifestation of the coherence of the collective molecular dynamics.
Violation of the Bell’s type inequalities as a local expression of incompatibility
Authors: Khrennikov Andrei
Published: September 2019

By filtering out the philosophic component we can be said that the EPR-paper was directed against the straightforward interpretation of the Heisenberg’s uncertainty principle or more generally the Bohr’s complementarity principle. The latter expresses contextuality of quantum measurements: dependence of measurement’s output on the complete experimental arrangement. However, Bell restructured the EPR-argument against complementarity to justify nonlocal theories with hidden variables of the Bohmian mechanics’ type. Then this Bell’s kind of nonlocality - subquantum nonlocality - was lifted to the level of quantum theory - up to the terminology “quantum nonlocality”. The aim of this short note is to explain that Bell’s test is simply a special test of local incompatibility of quantum observables, similar to interference experiments, e.g., the two-slit experiment.
Reinforcement Learning Based Control of Coherent Transport by Adiabatic Passage of Spin Qubits
Authors: Porotti Riccardo , Tamascelli Dario , Restelli Marcello , Prati Enrico
Published: September 2019

Several tasks involving the determination of the time evolution of a system of solid state qubits require stochastic methods in order to identify the best sequence of gates and the time of interaction among the qubits. The major success of deep learning in several scientific disciplines has suggested its application to quantum information as well. Thanks to its capability to identify best strategy in those problems involving a competition between the short term and the long term rewards, reinforcement learning (RL) method has been successfully applied, for instance, to discover sequences of quantum gate operations minimizing the information loss. In order to extend the application of RL to the transfer of quantum information, we focus on Coherent Transport by Adiabatic Passage (CTAP) on a chain of three semiconductor quantum dots (QD). This task is usually performed by the so called counter-intuitive sequence of gate pulses. Such sequence is capable of coherently transfer an electronic population from the first to the last site of an odd chain of QDs, by leaving the central QD unpopulated. We apply a technique to find nearly optimal gate pulse sequence without explicitly give any prior knowledge of the underlying physical system to the RL agent. Using the advantage actor-critic algorithm, with a small neural net as function approximator, we trained a RL agent to choose the best action at every time step of the physical evolution to achieve the same results previously found only by ansatz solutions.
Consciousness as the collective excitation of a brainwide web – understanding consciousness from below quantum fields to above neuronal networks
Authors: Lidström Suzy , Allen Roland E
Published: September 2019

In the spirit of previous ideas in the neuroscience community, but with a more physics-oriented perspective, we propose that consciousness can be described as the collective excitation of a brainwide web of neurones. This picture is inspired by the fact that, in all major areas of physics, a collective excitation has just as much physical reality as a particle or other localized object. The brainwide web extends into those regions (neuronal networks) where processed information is received from the senses, memories, etc. (emerging out of unconscious processes in prior networks). It unifies those regions (plus motor control regions) via the vast complexity of the neuronal interactions that it spans. A crude analogy is the worldwide web, which extends into servers which have been prepared by external agents. Other crude analogies are the many collective excitations in physics. True understanding of consciousness must rely mostly on experiment, but since probes of living brains have limited precision, there is an important role for large-scale simulations in revealing details and complementing experiment. Petascale computational facilities should make it possible to perform simulations with realistic complexity.
Some remarks on analytical solutions for a damped quantum parametric oscillator
Authors: Schuch Dieter
Published: September 2019

The time-dependent Schrödinger equation for quadratic Hamiltonians has Gaussian wave packets as exact solutions. For the parametric oscillator with frequency ω(t), the width of these wave packets must be time-dependent. This time-dependence can be determined by solving a complex nonlinear Riccati equation or an equivalent real nonlinear Ermakov equation. All quantum dynamical properties of the system can easily be constructed from these solutions, e.g., uncertainties of position and momentum, their correlations, ground state energies, etc. In addition, the link to the corresponding classical dynamics is supplied by linearizing the Riccati equation to a complex Newtonian equation, actually representing two equations of the same kind: one for the real and one for the imaginary part. If the solution of one part is known, the missing (linear independent) solution of the other can be obtained via a conservation law for the motion in the complex plane. Knowing these two solutions, the solution of the Ermakov equation can be determined immediately plus the explicit expressions for all the quantum dynamical properties mentioned above. The effect of a dissipative, linear velocity dependent friction force on these systems is discussed.
Linearized metric solutions in ghost-free nonlocal gravity
Authors: Buoninfante Luca
Published: September 2019

In this manuscript we review some aspects of linearized metric solutions in ghost-free nonlocal gravity, in which the action is made up of non-polynomial differential operators containing covariant derivatives of infinite order. By working with the simplest model of such a wide class of infinite derivative theories of gravity, we will first compute the spacetime metric generated by a static point-like source and show that all curvature invariants are nonsingular at the origin. Secondly, a similar computation is performed for an electrically charged source and also in this case the regularizing feature of nonlocality plays a crucial role. As a third case, we consider the spacetime metric generated by a Dirac delta distribution on a ring and show that, at least in the linear regime, Kerr-like singularities can be avoided in ghost-free non-local gravity.
Quantum thermodynamic instabilities in compact stars
Authors: Lavagno A , Pigato D , Gervino G
Published: September 2019

We study the existence of thermodynamic instabilities in the nuclear equation of state relative to the high density regime reached in the central core of compact stars. In the framework of a relativistic mean-field theory, we analyze the asymmetric nuclear properties in beta-equilibrium, including hyperons and Delta-isobar degrees of freedom. We investigate a finite density phase transition characterized by pure hadronic matter with the presence of mechanical instability (relative to the fluctuation of baryon number) and of chemical-diffusive instability (relative to the fluctuation of electric charge concentration). We find that, in the presence of thermodynamic instabilities, two hadronic phases with different values of electric charge content may coexist, with several phenomenological consequences in the physics of compact stars.
Simulation of Quantum Universe
Authors: Kim Sang Pyo
Published: September 2019

Quantum simulation provides quantum systems under study with analogous controllable quantum systems and has wide applications from condensed-matter physics to high energy physics and to cosmology. The quantum system of a homogeneous and isotropic field in the Friedmann-Robertson-Walker universe can be simulated by a charge in an electrically modulated ion trap. The quantum states of these time-dependent oscillators are constructed by quantum invariants. Further, we propose simulation of quantum Friedmann-Robertson-Walker universe with a minimal massive scalar field by a charged scalar field in a homogeneous, time-dependent, magnetic field in quantum electrodynamics and investigate the Cauchy problem of how the wave functions evolve.