bluuebunny/crossref_metadata_2025 huggingface dataset:
Effects of deposition environment and temperature on photoluminescence, particle morphology, and crystal structure of pulsed laser deposited Ga2O3 thin films
Authors: Ogugua Simon N. , Swart Hendrik C. , Ntwaeaborwa Odireleng M.
Published: June 2020

Gallium oxide (Ga2O3) thin films were laser ablation deposited on Si(100) substrates in vacuum, argon, and oxygen (O2) at different substrate temperatures by using the pulsed laser deposition technique. X-ray diffraction patterns showed that the films were crystallized in a mixed phase of β-Ga2O3 and Ga(OH)3. Data from scanning electron microscopy and atomic force microscopy showed that the major influence in the deposition conditions on the photoluminescence (PL) intensity was through changes in the particle morphology and surface topography of the films. The surface morphology studied using a field emission scanning electron microscope showed that the films were made of nanoparticles of spherical and cubic shapes at lower and higher temperatures, respectively. The energy-dispersive x-ray spectroscopy spectra confirmed the presence of the major elements Ga and O, with C coming from atmospheric hydrocarbons and Si from Si impurity in Ga2O3 and the substrate. The Si peak intensity was found to increase with the deposition temperature. X-ray photoelectron spectroscopy further confirmed the presence of Ga, O, C, Si, and N on the surface of the films. The PL spectrum excited using a 325 nm He-Cd laser showed nanoparticle shape driven tunable broadband emissions in the wavelength range between 350 and 750 nm. The comparison of the PL intensities of the films deposited in different atmospheres shows that the film deposited in O2 has the highest PL intensity.
Genomic surveillance reveals multiple introductions of SARS-CoV-2 into Northern California
Authors: Deng Xianding , Gu Wei , Federman Scot , du Plessis Louis , Pybus Oliver G. , Faria Nuno R. , Wang Candace , Yu Guixia , Bushnell Brian , Pan Chao-Yang , Guevara Hugo , Sotomayor-Gonzalez Alicia , Zorn Kelsey , Gopez Allan , Servellita Venice , Hsu Elaine , Miller Steve , Bedford Trevor , Greninger Alexander L. , Roychoudhury Pavitra , Starita Lea M. , Famulare Michael , Chu Helen Y. , Shendure Jay , Jerome Keith R. , Anderson Catie , Gangavarapu Karthik , Zeller Mark , Spencer Emily , Andersen Kristian G. , MacCannell Duncan , Paden Clinton R. , Li Yan , Zhang Jing , Tong Suxiang , Armstrong Gregory , Morrow Scott , Willis Matthew , Matyas Bela T. , Mase Sundari , Kasirye Olivia , Park Maggie , Masinde Godfred , Chan Curtis , Yu Alexander T. , Chai Shua J. , Villarino Elsa , Bonin Brandon , Wadford Debra A. , Chiu Charles Y.
Published: June 2020

Epidemic in Northern California

Genome sequencing of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) outbreaks is valuable for tracing the sources and perhaps for drawing lessons about preventing future outbreaks. Genomic analysis by Deng
et al.
revealed that Northern California experienced a complex series of introductions of the virus, deriving not only from state-to-state transmission but also from international travel by air and ship. The study highlights the importance of being able to rapidly test and trace contacts of positive cases to enable swift control.

Science
, this issue p.
582
Screening and Evaluation of New Hydroxymethylfurfural Oxidases for Furandicarboxylic Acid Production
Authors: Viñambres Mario , Espada Marta , Martínez Angel T. , Serrano Ana
Published: June 2020

HMFO is the only enzyme described to date that can catalyze by itself the three consecutive oxidation steps to produce FDCA from HMF. Unfortunately, only one HMFO enzyme is currently available for biotechnological application. This availability is enlarged here by the identification, heterologous production, purification, and characterization of two new HMFOs, one from
Pseudomonas nitroreducens
and one from an unidentified
Pseudomonas
species. Compared to the previously known
Methylovorus
HMFO, the new enzyme from
P. nitroreducens
exhibits better performance for FDCA production in wider pH and temperature ranges, with higher tolerance for the hydrogen peroxide formed, longer half-life during oxidation, and higher yield and total turnover numbers in long-term conversions under optimized conditions. All these features are relevant properties for the industrial production of FDCA. In summary, gene screening and heterologous expression can facilitate the selection and improvement of HMFO enzymes as biocatalysts for the enzymatic synthesis of renewable building blocks in the production of bioplastics.
Differential Impacts on Host Transcription by ROP and GRA Effectors from the Intracellular Parasite Toxoplasma gondii
Authors: Rastogi Suchita , Xue Yuan , Quake Stephen R. , Boothroyd John C.
Published: June 2020

This work performs transcriptomic analysis of U-I cells, captures the earliest stage of a host cell’s interaction with
Toxoplasma gondii
, and dissects the effects of individual classes of parasite effectors on host cell biology.
The Nucleoid-Associated Protein GapR Uses Conserved Structural Elements To Oligomerize and Bind DNA
Authors: Lourenço Rogério F. , Saurabh Saumya , Herrmann Jonathan , Wakatsuki Soichi , Shapiro Lucy
Published: June 2020

Bacteria organize their genetic material in a structure called the nucleoid, which needs to be compact to fit inside the cell and, at the same time, dynamic to allow high rates of replication and transcription. Nucleoid-associated proteins (NAPs) play a pivotal role in this process, so their detailed characterization is crucial for our understanding of DNA organization into bacterial cells. Even though NAPs affect DNA-related processes differently, all of them have to oligomerize and bind DNA for their function. The significance of this study is the identification of structural elements involved in the oligomerization and DNA binding of a newly discovered NAP in
C. crescentus
and the demonstration that structural elements are conserved in evolutionarily distant and functionally distinct NAPs.
Pan-GWAS of Streptococcus agalactiae Highlights Lineage-Specific Genes Associated with Virulence and Niche Adaptation
Authors: Gori Andrea , Harrison Odile B. , Mlia Ethwako , Nishihara Yo , Chan Jia Mun , Msefula Jacquline , Mallewa Macpherson , Dube Queen , Swarthout Todd D. , Nobbs Angela H. , Maiden Martin C. J. , French Neil , Heyderman Robert S.
Published: June 2020

GBS is a leading cause of mortality in newborn babies in high- and low-income countries worldwide. Different strains of GBS are characterized by different degrees of virulence, where some are harmlessly carried by humans or animals and others are much more likely to cause disease.
The genome sequences of almost 2,000 GBS samples isolated from both animals and humans in high- and low- income countries were analyzed using a pan-genome-wide association study approach. This allowed us to identify 279 genes which are associated with different lineages of GBS, characterized by a different virulence and preferred host. Additionally, we propose that the GBS now carried in humans may have first evolved in animals before expanding clonally once adapted to the human host.
These findings are essential to help understand what is causing GBS disease and how the bacteria have evolved and are transmitted.
The Novel J-Domain Protein Mrj1 Is Required for Mitochondrial Respiration and Virulence in Cryptococcus neoformans
Authors: Horianopoulos Linda C. , Hu Guanggan , Caza Mélissa , Schmitt Kerstin , Overby Peter , Johnson James D. , Valerius Oliver , Braus Gerhard H. , Kronstad James W.
Published: June 2020

Cryptococcus neoformans
is the causative agent of cryptococcal meningitis, a disease responsible for ∼15% of all HIV-related deaths. Unfortunately, development of antifungal drugs is challenging because potential targets are conserved between humans and
C. neoformans
. In this context, we characterized a unique J-domain protein, Mrj1, which lacks orthologs in humans. We showed that Mrj1 was required for normal mitochondrial respiration and that mutants lacking Mrj1 were deficient in growth, capsule elaboration, and virulence. Furthermore, we were able to phenocopy the defects in growth and capsule elaboration by inhibiting respiration. This result suggests that the role of Mrj1 in mitochondrial function was responsible for the observed virulence defects and reinforces the importance of mitochondria to fungal pathogenesis. Mitochondria are difficult to target, as their function is also key to human cells; however, Mrj1 presents an opportunity to target a unique fungal protein required for mitochondrial function and virulence in
C. neoformans
.
Nitrogen Source Governs Community Carbon Metabolism in a Model Hypersaline Benthic Phototrophic Biofilm
Authors: Anderton Christopher R. , Mobberley Jennifer M. , Cole Jessica K. , Nunez Jamie R. , Starke Robert , Boaro Amy A. , Yesiltepe Yasemin , Morton Beau R. , Cory Alexandra B. , Cardamone Hayley C. , Hofmockel Kirsten S. , Lipton Mary S. , Moran James J. , Renslow Ryan S. , Fredrickson James K. , Lindemann Stephen R.
Published: June 2020

Anthropogenic inputs of nitrogen into aquatic ecosystems, and especially those of agricultural origin, involve a mix of chemical species. Although it is well-known in general that nitrogen eutrophication markedly influences the metabolism of aquatic phototrophic communities, relatively little is known regarding whether the specific chemical form of nitrogen inputs matter. Our data suggest that the nitrogen form alters the rate of nitrogen uptake significantly, whereas corresponding alterations in carbon uptake were minor. However, differences imposed by uptake of divergent nitrogen forms may result in alterations among phototroph-heterotroph interactions that rewire community metabolism. Furthermore, our data hint that availability of other nutrients (i.e., iron) might mediate the linkage between carbon and nitrogen cycling in these communities. Taken together, our data suggest that different nitrogen forms should be examined for divergent impacts on phototrophic communities in fluvial systems and that these anthropogenic nitrogen inputs may significantly differ in their ultimate biogeochemical impacts.
Incipient evolution of the Eastern California shear zone through the transpressional zone of the San Bernardino Mountains and San Gorgonio Pass, California
Authors: Cochran William J. , Spotila James A. , Prince Philip S.
Published: June 2020

The nature of the connection between the Eastern California shear zone (ECSZ) and the San Andreas fault (SAF) in southern California (western United States) is not well understood. Northwest of San Gorgonio Pass, strands of the ECSZ may be migrating south and west into the convergent zone of the San Bernardino Mountains (SBM) as it is advected to the southeast via the SAF. Using high-resolution topography and field mapping, this study aims to test whether diffuse faults within the SBM represent a nascent connection between the ECSZ and the SAF. Topographic resolution of ≤1 m was achieved using both lidar and unmanned aerial vehicle surveys along two Quaternary strike-slip faults. The Lone Valley fault enters the SBM from the north and may form an along-strike continuation of the Helendale fault. We find that its geomorphic expression is obscured where it crosses Quaternary alluvium, however, suggesting that it may have a low rate of yet-undetermined activity. The Lake Peak fault is located farther south and cuts through the high topography of the San Gorgonio massif and may merge with strands of the SAF system. We find that this fault clearly cuts Quaternary glacial deposits, although the magnitude of offset is difficult to assess. Based on our interpretation of geomorphic features, we propose that the Lake Peak fault has predominantly dextral or oblique-dextral motion, possibly with a slip rate that is comparable to the low rates observed along other strands of the ECSZ (i.e., ≤1 mm/yr). Comparing the geomorphic expressions of these faults is difficult, however, given that the erosive nature of the mountainous landscape in the SBM may obscure evidence of active faulting. Based on these observations, as well as the occurrence of other diffuse faults in the region, we suggest that dextral strain is overprinting the actively convergent zone of the SBM, thereby creating a throughgoing connection between the ECSZ and the SAF west of San Gorgonio Pass.
Three-dimensional shape and structure of the Susitna basin, south-central Alaska, from geophysical data
Authors: Shah Anjana K. , Phillips Jeffrey D. , Lewis Kristen A. , Stanley Richard G. , Haeussler Peter J. , Potter Christopher J.
Published: June 2020

We use gravity, magnetic, seismic reflection, well, and outcrop data to determine the three-dimensional shape and structural features of south-central Alaska’s Susitna basin. This basin is located within the Aleutian-Alaskan convergent margin region and is expected to show effects of regional subduction zone processes. Aeromagnetic data, when filtered to highlight anomalies associated with sources within the upper few kilometers, show numerous linear northeast-trending highs and some linear north-trending highs. Comparisons to seismic reflection and well data show that these highs correspond to areas where late Paleocene to early Eocene volcanic layers have been locally uplifted due to folding and/or faulting. The combined magnetic and seismic reflection data suggest that the linear highs represent northeast-trending folds and north-striking faults. Several lines of evidence suggest that the northeast-trending folds formed during the middle Eocene to early Miocene and may have continued to be active in the Pliocene. The north-striking faults, which in some areas appear to cut the northeast-trending folds, show evidence of Neogene and probable modern movement. Gravity data facilitate estimates of the shape and depth of the basin. This was accomplished by separating the observed gravity anomaly into two components—one representing low-density sedimentary fill within the basin and one representing density heterogeneities within the underlying crystalline basement. We then used the basin anomaly, seismic reflection data, and well data to estimate the depth of the basin. Together, the magnetic, gravity, and reflection seismic analyses reveal an asymmetric basin comprising sedimentary rock over 4 km thick with steep, fault-bounded sides to the southwest, west, and north and a mostly gentle rise toward the east. Relations to the broader tectonic regime are suggested by fold axis orientations within the Susitna basin and neighboring Cook Inlet basin, which are roughly parallel to the easternmost part of the Alaska-Aleutian trench and associated Wadati-Benioff zone as it trends from northeast to north-northeast to northeast. An alignment between forearc basin folds and the subduction zone trench has been observed at other convergent margins, attributed to strain partitioning generated by regional rheologic variations that are associated with the subducting plate and arc magmatism. The asymmetric shape of the basin, especially its gentle rise to the east, may reflect uplift associated with flat-slab subduction of the Yakutat microplate, consistent with previous work that suggested Yakutat influence on the nearby Talkeetna Mountains and western Alaska Range. Yakutat subduction may also have contributed to Neogene and later reverse slip along north-striking faults within the Susitna basin.
Disseminated septic arthritis caused byStreptococcus equiinfection
Authors: Mobeen Khudaim Mohammed , Carter Janine , Ahmed Zaheer , Minton Jane
Published: June 2020

We describe a rare case of bloodstream infection and disseminated septic arthritis in a relatively fit and well 73-year-old retired farmer and gamekeeper, due to the zoonotic organismStreptococcus equi. The presence of the organism in multiple joints led to slow clinical response to treatment and was complicated by relapse of infection and lengthy disability. Source control was achieved with multiple joint washouts and spinal cord decompression. Following this, a 6-week course of intravenous antibiotics was required for complete clearance of infection. After a long period of rehabilitation, the patient made a good recovery. This case demonstrates thatS. equican cause life threatening and difficult to treat sepsis in humans and requires a high index of suspicion in people who have regular contact with equine species, cattle and unpasteurised milk.
Autosomal dominant hypocalcaemia: identification of two novel variants ofCASRgene
Authors: Gomes Vânia , Silvestre Catarina , Ferreira Florbela , Bugalho Maria João Guerreiro Martins
Published: June 2020

Autosomal dominant hypocalcaemia is a rare aetiology of hypocalcaemia, caused by gain-of-function mutations of the calcium-sensing receptor (CASR) gene. We present two cases of two asymptomatic women (50-year-old—case 1 and 25-year-old—case 2), referred to our endocrinology department for investigation of hypocalcaemia, hyperphosphatemia and inappropriately low parathormone. Both patients had relatives with the same laboratorial findings. At diagnosis, both patients presented basal ganglia calcifications. Genetic analysis was performed, identifying two novel heterozygousCASRvariants: c.2269G>A (p.Glu757Lys) and c.2086C>G (p.Leu696Val), respectively, for case 1 and case 2. Affected individuals started oral calcium and vitamin D analogues, aiming to a low–normal calcium level. They remain under observation and are asymptomatic.
Euglycaemic diabetic ketoacidosis in a 43-year-old woman with type 2 diabetes mellitus on SGLT-2 inhibitor (empagliflozin)
Authors: Latif Azka , Gastelum Aheli Arce , Sood Akshat , Reddy Joseph Thilumala
Published: June 2020

We report a case of euglycaemic diabetic ketoacidosis (EDKA) in a 43-year-old woman with type 2 diabetes mellitus who presented to the emergency department with problems of vomiting, cough, shortness of breath and generalised weakness after following a ketogenic diet for 2 weeks. Therapy with sodium glucose transport protein-2 empagliflozin had been started 2 months prior. Initial evaluation revealed high anion gap metabolic acidosis with blood glucose level of 169 mg/dL. Treatment for EDKA with fluid resuscitation, intravenous insulin and dextrose resolved her acidosis and symptoms in less than 24 hours. Empaglifozin was discontinued on discharge. This entity represents a diagnostic challenge since the differential diagnosis is broad with a potentially misleading clinical presentation that can result in delayed diagnosis and adverse outcomes including acute kidney injury, multiple electrolyte abnormalities, cerebral oedema, acute respiratory distress syndrome, shock and death.
Detection of microsatellite instability in a panel of solid tumours with the Idylla MSI Test using extracted DNA
Authors: Pécriaux Adrien , Favre Loetitia , Calderaro Julien , Charpy Cécile , Derman Jonathan , Pujals Anaïs
Published: June 2020

Aim

During the last few years, determination of microstatellite instability (MSI) status has become a routine part of clinical practice, essentially to detect Lynch syndrome. Recently, MSI testing has increased with the development of immunotherapy and has expanded to a large panel of solid tumours. The aim of our work was to evaluate a fully automated system developed by Biocartis, the Idylla MSI Test, which performs an MSI analysis within 150 min.

Methods

A comparison between pentaplex PCR, immunohistochemistry and Idylla MSI Test was performed in 53 colorectal carcinoma samples, 7 small intestine adenocarcinomas, 15 duodenal and pancreatic adenocarcinomas, 16 gastric tumours, 15 endometrial adenocarcinomas, 5 ovarian carcinomas and 4 cases of urinary tract tumours using extracted DNA. Limit-of-detection (LOD) experiment was also done using a commercial DNA known to harbour MSI phenotype.

Results

The overall sensitivity was 94% and the overall specificity was 100%. Two invalid and three false-negative results were observed. Our experiments showed that the amount of DNA loaded into the cartridge was decisive and should be superior to 25 ng. LOD comprised between 4% and 8%.

Conclusion

Overall, we have demonstrated that the Idylla MSI Test is a rapid and valid option to detect MSI phenotype which can be used in a large panel of solid tumours.
Bumble bee (Bombus spp.) diversity differs between forested wetlands and clearcuts in the Acadian forest
Authors: Brooks Delaney R. , Nocera Joseph J.
Published: June 2020

Bumble bees (species of Bombus Latreille, 1802) are important pollinators that are generally in population decline, but species presence and relative abundance are unknown in forested wetlands of the Acadian forest. To address this knowledge gap, we sampled bumble bees in forested wetlands and harvested sites (clearcuts) using vane and pan traps. We collected 617 specimens representing 11 species. We also included observations from iNaturalist (n = 70) in disturbed sites. We found that species-specific abundance in Acadian forested wetlands differed significantly from that in harvested sites. Wet coniferous forests with moderate to high herbaceous cover had greater overall bumble bee abundance than harvest sites. Species interactions may also influence community structure: sites with higher abundance of Bombus borealis Kirby, 1837 and B. ternarius Say, 1837 had fewer B. fervidus (Fabricius, 1798); B. flavidus Eversmann, 1852; and B. terricola Kirby, 1837. Differences in presence and abundance of bumble bee species may be explained by forested wetlands having a greater variety of flowering plants than forest harvest sites.
Seventy-year history of management using low-intensity harvesting methods: weak impact on biodiversity of hemiboreal Scots pine forests
Authors: Tullus Tea , Lutter Reimo , Randlane Tiina , Saag Andres , Tullus Arvo , Roosaluste Elle , Kõresaar Priit , Pärtel Meelis , Tullus Hardi
Published: June 2020

Less intensive harvesting methods (e.g., selection cutting, shelterwood cuttings) are recommended as alternatives to clearcutting for maintaining mature forest biodiversity in the process of forest regeneration. However, the long-term impact of low-intensity harvesting methods has rarely been studied. Our aim was to clarify the long-term effects of repeated selective cutting, thinning, and shelterwood cutting on the richness, abundance, and species composition of vascular plants, bryophytes, and lichens in Scots pine forests (Pinus sylvestris L.). Data were collected from 25 mature stands located in dry Podzols in southwestern Estonia with a known management history for the last 70 years. Altogether, 35 vascular plant, 41 bryophyte, and 78 lichen species were recorded, including five species with conservational value. Generally, the management history was not related to species richness, except a negative correlation with the species number of epiphytic lichens on conifer trees. In addition, the abundance of two lichen species from the genus Chaenotheca was lower in more frequently managed stands. Species richness and composition were most strongly affected by soil pH and light conditions. We conclude that long-term, low-intensity harvesting of Scots pine forests on nutrient-poor Podzols maintains suitable habitats for vascular plants, bryophytes, and lichens, confirming its suitability for sustainable forest regeneration.
The confining color field in SU(3) gauge theory
Authors: Baker M. , Cea P. , Chelnokov V. , Cosmai L. , Cuteri F. , Papa A.
Published: June 2020

We extend a previous numerical study of SU(3) Yang–Mills theory in which we measured the spatial distribution of all components of the color fields surrounding a static quark–antiquark pair and provided evidence that the simulated gauge invariant chromoelectric field can be separated into a Coulomb-like ‘perturbative’ field and a ‘non-perturbative’ confining field. In this paper we hypothesize that the fluctuating color fields not measured in our simulations do not contribute to the string tension. Under this assumption the string tension is determined by the color fields we measure, which form a field strength tensor pointing in a single direction in color space. We call this the ‘Maxwell picture of confinement’. We provide an additional procedure to isolate the confining field. We then extract the string tension from a stress energy-momentum tensor having the Maxwell form, constructed from the simulated non-perturbative part of the field strength tensor. To test our hypothesis we calculate the string tension for values of the quark–antiquark separation ranging from 0.37 fm to 1.2 fm. We also calculate the spatial distributions of the energy-momentum tensor surrounding static quarks for this range of separations, and we compare with the distributions obtained from direct simulations of the energy-momentum tensor.
Exact vacuum solutions to modified Einstein field equations in f(R) gravity
Authors: Al-Ali Usamah S. , Bokhari Ashfaque H.
Published: June 2020

Considering the plane symmetric non-static spacetimes in the context of [Formula: see text] gravity, we obtain exact solutions of the vacuum field equations by assuming constant scalar curvature. By suitable transformations, it is shown that the obtained solutions can be transformed to Bianchi type [Formula: see text], a type of Taub’s and the De Sitter solutions. Of particular interest is a solution that represents a model that has initial singularity and under an appropriate transformation can be converted to a Bianchi-type V model. This solution, like the Bianchi type V model, leads to predictions about evolution in the sense of an expanding universe starting from an initial singularity. In this context, we show that the expansion of the universe in [Formula: see text] gravity can be explained without invoking the cosmological constant [Formula: see text].
Complex network routing strategy based on segmented transportation distance limit
Authors: Li Yuanhao , Zhuo Xinjian , Li Hui-Jia
Published: June 2020

In transmission problem of many complex networks, there are some restrictions on the routing path between a pair of sources and destinations, especially for the transmission process that has a segment distance limit, which has a wide range of applications in real transportation, information transmission, etc. on large real networks. In this work, we constructed a complex network transmission model, defined the transmission distance limit to [Formula: see text] and randomly selected a part of the nodes in the scale-free network as the station. Based on the shortest path algorithm and a weighted routing algorithm, we observed the results under the transmission distance limit. The results show that the setting of [Formula: see text] is important, which can be used to guide and control the fuel carrying capacity of vehicles on the transportation network. Finally, we selected two real road network for simulation and the results demonstrate the effectiveness of the algorithm in scale-free networks and real networks.
Influence of He+-ion beam induced effect on ultrafast quantum spin-state switching dynamics in exchange bias Co–Mn FM/AFM systems
Authors: Farberovich Oleg V. , Mazuritskiy Mikhail
Published: June 2020

A study of magnetic or spin logic appears as an appealing alternative due to its nonvolatile character, which can boost up switching on/off. The influences of Dzyaloshinskii–Moriya (DM) interaction on non-classical correlations play an important role in foundations of quantum technologies such as quantum information and quantum computation. We have considered the anisotropic general spin Hamiltonian (GSH) model in presence of DM interaction in addition to the Landau–Lifshitz–Gilbert (LLG)-model in a pulse magnetic field. For study of ultrafast spin dynamics in exchange bias Co–Mn FM/AFM systems, we present some quantum circuits for a deterministic quantum computing in Co–Mn FM/AFM systems.
Period-Bubbling Transition to Chaos in Thermo-Viscoelastic Fluid Systems
Authors: Layek G. C. , Pati N. C.
Published: June 2020

We report a 6D nonlinear dynamical system for thermo-viscoelastic fluid by selecting higher modes of infinite Fourier series of flow quantities. This nonlinear system demonstrates overstable convective motion and some organized structures such as period-bubbling and Arnold tongue-like structures. Studies reveal that the stability of the conduction state does not alter for the new 6D system in comparison with the lowest order 4D system of Khayat [1995] . However, the stabilities of the convective state have some differences. The onset of unsteady convection in the 6D system is delayed for weak elasticity of the fluid. There exists a critical range of fluid elasticity where the 4D system exhibits subcritical Hopf bifurcation while the 6D system shows supercritical Hopf bifurcation, which ensures the increase of the domain of stability. In this range, catastrophic route to chaos occurs in the 4D system, whereas the 6D system exhibits intermittent onset of chaos. Comparing the two-parameter dependent dynamics for the two systems, the chaotic zones enclosed by periodic regions are suppressed in the 6D system, so the flow behaviors become more predictable. Owing to interacting thermal buoyancy and fluid elasticity, both the models exhibit period-bubbling transition to chaos, but the period-bubbling cascade in the 6D model occurs at lower Rayleigh number than the 4D model. The convergence rate of the period-bubbling process slows down compared to usual period-doubling and approaches the square root of the Feigenbaum constant asymptotically.
Bifurcation Sequences and Multistability in a Two-Dimensional Piecewise Linear Map
Authors: Tikjha Wirot , Gardini Laura
Published: June 2020

Bifurcation mechanisms in piecewise linear or piecewise smooth maps are quite different with respect to those occurring in smooth maps, due to the role played by the borders. In this work, we describe bifurcation mechanisms associated with the appearance/disappearance of cycles, which may be related to several cases: (A) fold border collision bifurcations, (B) degenerate flip bifurcations, supercritical and subcritical, (C) degenerate transcritical bifurcations and (D) supercritical center bifurcations. Each of these is characterized by a particular dynamic behavior, and may be related to attracting or repelling cycles. We consider different bifurcation routes, showing the interplay between all these kinds of bifurcations, and their role in the phase plane in determining attracting sets and basins of attraction.
Detection and Classification of Solutions for Systems Interacting by Soft Impacts with Sample-Based Method
Authors: Lazarek M. , Brzeski P. , Solecki W. , Perlikowski P.
Published: June 2020

In this paper, we analyze the dynamics of two externally forced Duffing oscillators interacting via soft impacts using the extended basin stability method. The investigated system is multistable with different types of coexisting solutions (periodic with and without impacts and chaotic). The extended basin stability method lets us estimate the occurrence probability of solution or given type of behavior for assumed parameters and initial condition ranges. We present the general study of system behavior focusing on the existence of nonimpacting periodic solutions. We show how selected controlling parameters and initial conditions affect the response of the system. The proposed method is robust and can be utilized for a variety of engineering applications where the parameters are varying.
Dynamical Analysis of Planetary Gear Transmission System Under Support Stiffness Effects
Authors: Xiang Ling , Deng Zeqi , Hu Aijun
Published: June 2020

The transverse-torsional nonlinear model of multistage gear transmission system which is comprised of a planetary gear set and two parallel gear stages is proposed with time-varying meshing stiffness, comprehensive gear errors and gear backlash. The nonlinear dynamic responses are analyzed by applying excitation frequency and support stiffness as the bifurcation parameters. The motions of the system are identified through global bifurcation diagram, largest Lyapunov exponent (LLE) and Poincaré map. The numerical results demonstrate that the support stiffness affects the system, especially on planetary gear set. The motions of the system with the changes of the support stiffness are diverse including some different multiperiodic motions. Also, the state of the system undergoes 2T-periodic motion, chaos, quasi-periodic behavior and multiperiodic motion. For the support stiffness or other nonlinear factors of the gear system, the suitable range of working frequencies could make the system stable. Correspondingly, parameters of the system should be designed properly and controlled for the better operation and enhancing the life of the system.
Dynamics of Convective Thermal Explosion in Porous Media
Authors: Allali Karam , Joundy Youssef , Taik Ahmed , Volpert Vitaly
Published: June 2020

In this paper, we study complex dynamics of the interaction between natural convection and thermal explosion in porous media. This process is modeled with the nonlinear heat equation coupled with the nonstationary Darcy equation under the Boussinesq approximation for a fluid-saturated porous medium in a rectangular domain. Numerical simulations with the Radial Basis Functions Method (RBFM) reveal complex dynamics of solutions and transitions to chaos after a sequence of period doubling bifurcations. Several periodic windows alternate with chaotic regimes due to intermittence or crisis. After the last chaotic regime, a final periodic solution precedes transition to thermal explosion.
Rich Bifurcation Structure of Prey–Predator Model Induced by the Allee Effect in the Growth of Generalist Predator
Authors: Sen Deeptajyoti , Petrovskii Sergei , Ghorai S. , Banerjee Malay
Published: June 2020

Prey–predator models are building blocks for many food-chain and food-web models in theoretical population biology. These models can be divided into two groups depending on the nature of predators, namely, specialist predator and generalist predator. Generalist predators can survive in the absence of prey but specialist predators go to extinction. Prey–predator models with specialist predator and Allee effect in prey growth have been investigated by several researchers and various types of interesting dynamics have been reported. In this paper, we consider a prey–predator model with generalist predator subject to Allee effect in predator’s growth rate. In general, a prey–predator system with saturating functional response can be destabilized due to the increase of the carrying capacity of prey which is known as paradox of enrichment. In our model with Allee effect in predator growth, we have shown that increase in carrying capacity of prey helps the populations to survive in a coexistence steady state. The considered model is capable of producing bistable dynamics for a reasonable range of parameter values. The complete dynamics of the system are quite rich and all possible local and global bifurcations are studied to understand the dynamics of the model. Analytical results are verified with numerical examples and successive bifurcations are identified with the help of bifurcation diagrams.
On the Bifurcation Structure of a Leslie–Tanner Model with a Generalist Predator
Authors: Valenzuela Luis Miguel , Blé Gamaliel , Falconi Manuel
Published: June 2020

In this work, the dynamical properties of a Leslie–Tanner predator–prey model are analyzed. A method is provided to find the regions in the parameter space where Bautin, Hopf and simultaneous supercritical Hopf bifurcations exist. A remarkable feature of the dynamics of the model is the existence of tristability. In fact, the system simultaneously presents three stable limit cycles. These results generalize some previous knowledge on the subject since both prey defense and a generalist predator are incorporated in our analysis.
A Chaotic Image Encryption Scheme Based on Hénon–Chebyshev Modulation Map and Genetic Operations
Authors: Liu Yu , Qin Zheng , Liao Xiaofeng , Wu Jiahui
Published: June 2020

Thanks to the complex characteristics of ergodicity, pseudo-randomness and sensitivity in initial conditions, chaotic systems have been widely applied in the field of cryptography. By cascading the Hénon map and the Chebyshev map, a new two-dimensional Hénon–Chebyshev modulation map (2D-HCMM) is proposed in this paper. Several methods of objective assessment, including phase diagrams, bifurcation diagrams, Lyapunov exponents and information entropy, are utilized to analyze the dynamics of the 2D-HCMM. The results show that the 2D-HCMM possesses better ergodicity and unpredictability, with larger chaotic ranges, compared with the original chaotic maps. By using the proposed map and the essential principles of genetic recombination and genetic mutation, a new image encryption scheme is proposed. In this scheme, the bit planes of image are substituted by genetic recombination operation, and the pixel values are scrambled randomly by genetic mutation operation. The simulation results and security analysis demonstrate that the proposed scheme not only can resist various conventional attacks, but also possesses a fast speed, achieving a good trade-off between security and efficiency.
Spiral Tip Recognition via Deterministic Learning
Authors: Song Chen , Dong Xunde , Wang Cong
Published: June 2020

The spiral tip is vital to the understanding of the spiral wave behaviors. Most studies of spiral tip dynamics focused on the prevention, control, and elimination of spiral wave, while few studies focused on the recognition of spiral wave. In real systems with the spiral wave, the recognition of the spiral wave should be before control or elimination. In the paper, we study the recognition of the spiral tip via deterministic learning. It mainly consists of two phases: the identification phase and the recognition phase. In the identification phase, the dynamics of spiral tips of the training set is accurately identified by using deterministic learning. In the recognition phase, a set of errors is obtained for a test spiral tip by employing an estimator model. Finally, the recognition of test spiral tip is achieved according to the smallest error principle. Numerical simulations based on the spiral tip generated by the Barkley model are performed to demonstrate the effectiveness and feasibility of the proposed method.
On the initial value problems for the Caputo–Fabrizio impulsive fractional differential equations
Authors: Abbas Mohamed I.
Published: June 2020

This paper is devoted to initial value problems for impulsive fractional differential equations of Caputo–Fabrizio type fractional derivative. By means of Banach’s fixed point theorem and Schaefer’s fixed point theorem, the existence and uniqueness results are obtained. Finally, an example is given to illustrate one of the main results.
Edge geodetic self-decomposition in graphs
Authors: John J. , Stalin D.
Published: June 2020

Let [Formula: see text] be a simple connected graph of order [Formula: see text] and size [Formula: see text]. A decomposition of a graph [Formula: see text] is a collection of edge-disjoint subgraphs [Formula: see text] of [Formula: see text] such that every edge of [Formula: see text] belongs to exactly one [Formula: see text]. The decomposition [Formula: see text] of a connected graph [Formula: see text] is said to be an edge geodetic self-decomposition if [Formula: see text] for all [Formula: see text]. Some general properties satisfied by this concept are studied.
4E Analysis and Design of a Combined Cycle with a Geothermal Condensing System in Iranian Moghan Diesel Power Plant
Authors: Norouzi Nima
Published: June 2020

Considering the new issues human society faces now, environmental issues, and climate change is one of the primary and most essential phenomena which have been caused by the unsustainable lifestyle of men over the last two centuries. Power and energy are some of the leading role players of today’s human lifestyle and one of the most effective in which the environment is affected. This article represents the results of research over the possibility of recovering waste heat and determination of design parameters of a waste heat steam generator for medium speed set of diesel generators, with the rated 42[Formula: see text]MW capacity and are used for power generation. The main goals of this study are to manage the waste heat of the engines and to help the severe water leakage of the power plant. In this paper, for managing the waste heat, a combined steam cycle is being designed for this process. This system added 19[Formula: see text]MW the overall electricity generation, and the exergy and energy efficiencies of the system are being increased by 29.2% and 32.8%. Moreover, finally, a geothermal condensing system (GCS) is designed to control the water shortages of the steam power unit condensing system. The GCS condensing system developed in this paper helps to reduce the water evaporation losses in the cooling water by more than 79% compared to the wet cooling towers.
Machine Learning Assisted PUF Calibration for Trustworthy Proof of Sensor Data in IoT
Authors: Chatterjee Urbi , Chatterjee Soumi , Mukhopadhyay Debdeep , Chakraborty Rajat Subhra
Published: June 2020

Remote integrity verification plays a paramount role in resource-constraint devices owing to emerging applications such as Internet-of-Things (IoT), smart homes, e-health, and so on. The concept of Virtual Proof of Reality (VPoR) proposed by Rührmair et al. in 2015 has come up with a
Sense-Prove-Validate
framework for integrity checking of abundant data generated from billions of connected sensors. It leverages the unreliability factor of Physically Unclonable Functions (PUFs) with respect to ambient parameter variations such as temperature, supply voltages, and so on, and claims to prove the authenticity of the sensor data without using any explicit keys. The state-of-the-art authenticated sensing protocols majorly lack in limited authentications and huge storage overhead. These protocols also assume that the behaviour of the PUF instances varies unpredictably for different levels of ambient factors, which in turn makes them hard to go beyond the theoretical concept. We address these issues in this work
1
and propose a Machine Learning (ML) assisted PUF calibration scheme to predict the Challenge-Response Pair (CRP) behaviour of a PUF instance in a specific environment, given the CRP behaviour in a pivot environment. Here, we present a new class of authenticated sensing protocols where we leverage the beneficence of ML techniques to validate the authenticity and integrity of sensor data over ambient factor variations. The scheme also reduces the storage complexity of the verifier from
O
(
p
*
K
*
l
* (
c
+
r
)) to
O
(
p
*
l
*(
c
+
r
)), where
p
is the number of PUF instances deployed in the framework,
l
is the number of challenge-response pairs used for authentication,
c
is the bit lengths of the challenge,
r
is the response bits of the PUF, and
K
is the number of levels of ambient factor variations. The scheme alleviates the issue of
limited authentication
as well, whereby every CRP is used only once for authentication and then deleted from the database. To validate the proposed protocol through actual experiments on FPGA, we propose 5-4 Double Arbiter PUF, which is an extension of
Double Arbiter PUFs
(DAPUFs) as this design is more suited for FPGA, and implement it on Xilinx Artix-7 FPGAs. We characterise the proposed PUF instance from −20°
C
to 80°
C
and use
Random Forest
--based ML technique to generate a soft model of the PUF instance. This model is further used by the verifier to authenticate the actual PUF circuit. According to the FPGA-based validation, the proposed protocol with DAPUF can be effectively used to authenticate sensor devices across wide variations of temperature values.
Strong Logic Obfuscation with Low Overhead against IC Reverse Engineering Attacks
Authors: Alasad Qutaiba , Yuan Jiann-Shuin , Subramanyan Pramod
Published: June 2020

Untrusted foundries pose threats of integrated circuit (IC) piracy and counterfeiting, and this has motivated research into logic locking. Strong logic locking approaches potentially prevent piracy and counterfeiting by preventing unauthorized replication and use of ICs. Unfortunately, recent work has shown that most state-of-the-art logic locking techniques are vulnerable to attacks that utilize Boolean Satisfiability (SAT) solvers.

In this article, we extend our prior work on using silicon nanowire (SiNW) field-effect transistors (FETs) to produce obfuscated ICs that are resistant to reverse engineering attacks, such as the sensitization attack, SAT and approximate SAT attacks, as well as tracked signal attacks. Our method is based on exchanging some logic gates in the original design with a set of polymorphic gates (PLGs), designed using SiNW FETs, and augmenting the circuit with a small block, whose output is untraceable, namely, URSAT. The URSAT may not offer very strong resilience against the combined AppSAT-removal attack. Strong URSAT is achieved using only CMOS-logic gates, namely, S-URSAT. The proposed technique, S-URSAT + PLG-based traditional encryption, designed using SiNW FETs, increases the security level of the design to robustly thwart all existing attacks, including combined AppSAT-removal attack, with small penalties. Then, we evaluate the effectiveness of our proposed methods and subject it to a thorough security analysis. We also evaluate the performance penalty of the technique and find that it results in very small overheads in comparison to other works. The average area, power, and delay overheads of implementing 64 baseline key-bits of S-URSAT for small benchmarks are 5.03%, 2.60%, and −2.26%, respectively, while for large benchmarks they are 2.37%, 1.18%, and −1.93%.
Modeling the Impact of Crop Diseases on Global Food Security
Authors: Savary Serge , Willocquet Laetitia
Published: June 2020

Plant pathology must contribute to improving food security in a safe operating space, which is shrinking as a result of declining natural resources, climate change, and the growing world population. This review analyzes the position of plant pathology in a nexus of relationships, which is mapped and where the coupled dynamics of crop growth, disease, and yield losses are modeled. We derive a hierarchy of pathogens, whereby pathogens reducing radiation interception (RI), radiation use efficiency (RUE), and harvest index increasingly impact crop yields in the approximate proportions: 1:4.5:4,700. Since the dawn of agriculture, plant breeding has targeted the harvest index as a main objective for domesticated plants. Surprisingly, the literature suggests that pathogens that reduce yields by directly damaging harvestable plant tissues have received much less attention than those that reduce RI or RUE. Ecological disease management needs to target diverse production situations and therefore must consider variation in attainable yields; this can be achieved through the reengineering of agrosystems to incorporate built-in dynamic diversity of genes, plants, and crop stands.
Porphyrins-as Active Materials in the Design of Sensors. An Overview
Authors: Negut Catalina Cioates , Stefan - van Staden Raluca-Ioana , van Staden Jacobus Frederick
Published: June 2020

This overview described the utilization of porphyrins as active compound in the design of different types of sensors. The modified electrodes with porphyrins showed a new approach in sensing of different compounds such as biogenic amines, vitamins, toxic and polyphenolic compounds, biomarkers. The porphyrins had many applications due to their large surface area, redox mediators, regular porosity and tunable structures, making them suitable for detecting small molecules. Different electrochemical and optical sensors were designed and applied successfully for clinical, food, and environmental analysis.