Carbon dioxide has attracted considerable attention owing to its physics and abundant polymorphs. Despite decades of extensive experiments and theoretical simulations, the structure and properties of carbon dioxide under extreme pressures and temperatures are yet to be properly understood. Particularly, the intermediate phase IV of solid carbon dioxide, which separates the molecular phases at low pressures from the non-molecular phases at high pressures, has not been fully investigated, and its structure remains controversial. Here, based on the second-order Møller−Plesset perturbation (MP2) theory and the embedded fragment method, we study the crystal structure, equation of state, and Raman spectra of solid carbon dioxide phase IV at high pressures and temperatures. We demonstrate that the solid carbon dioxide phase IV is a molecular structure that remains in a molecular state rather than the bent state shown in other literatures, which is consistent with the experimental work by Datchi et al. and denies the observed results by Park et al. The proposed work is of great significance in determining the structure of the high-pressure phases of carbon dioxide and further exploring the new phase of molecular crystals.

Quantum chemical calculations are applied to study the complexes between X2TO (X=H, F, Cl, Br, CH3; T=C, Si, Ge, Sn) and CO2. The carbon atom of CO2 as a Lewis acid participates in the O•••C carbon bond, whereas its oxygen atom as a base engages in the O•••T tetrel bond with X2TO. Most of complexes are stabilized by a combination of both O•••C and O•••T interactions. The interaction energies are dependent on the nature of T and X atoms/groups. Both the electron-withdrawing halogen group and the electron-donating methyl group increase the interaction energy, up to 51 kJ/mol in F2SiO•••CO2. One F2SiO molecule can bind with different number of CO2 molecules from one to four; as the number of CO2 increases, the average interaction energy for each CO2 is decreased but it can contribute at least 27 kJ/mol stabilization energy. Therefore, silicon-containing molecules are good absorbents for CO2.

In this paper fluidization transition from Geldart B to A induced by change in temperature was visualized by high-temperature electrical capacitance tomography (ECT) recently developed. Silica particles with a Sauter mean diameter of 222 μm and density of 2650 kg/m3, which are typically Geldart B particles at ambient condition, were fluidized in a fluidized bed of 5 cm from 20 to 600 °C. With the increase in temperature, ECT images showed the decrease in superficial gas velocity corresponding to the onset of bubbles, i.e. the minimum bubbling velocity (Umb) and homogeneous fluidization regime. The pressure drop versus superficial gas velocity curves confirmed the existence of homogeneous fluidization between the minimum fluidization velocity (Umf) and Umb at elevated temperature. Our detailed analysis confirms that the cohesive inter-particle forces, which manifest a linear increment with temperature, are responsible for the fluidization transition.

g-C3N4 nanosheets with tunable CO2 adsorption properties and nanostructures were synthesized and incorporated into polyether block amide (Pebax) membrane for CO2 separation. The g-C3N4 nanosheets with variable adsorption properties were produced from two monomers, dicyandiamide and melamine, and the variation of nanostructures was controlled by thermal oxidation etching process. The effects of CO2-philic and molecular sieving properties of g-C3N4 nanosheets on solubility and diffusivity of gas molecules in the as-prepared membranes were systematically investigated. The results demonstrated that the g-C3N4 nanosheets produced from dicyandiamide and undergoing 4 h thermal etching (DCN-4 nanosheets) showed the optimal CO2 sorption and sieving property. The membrane with 0.25 wt% DCN-4 nanosheets exhibited simultaneous enhancement in CO2 permeance and CO2/N2 selectivity compared with pure Pebax membrane. Moreover, the membrane maintained its separation performance during long-term operation test, showing great potential for CO2 capture.

Single-nucleotide polymorphisms (SNPs) have numerous advantages over microsatellites, including greater power to infer population structure and history and to detect loci undergoing selection. Here, we conduct the first continental-level SNP study of polar bears (Ursus maritimus) using genotypes from an array of 5441 SNP loci genotyped in 16–30 polar bears sampled in each of 16 geographic regions in Canada and West Greenland. Our study aimed to assess population history and genetic structure and to identify evidence of adaptive loci. Using these data, we confirmed the existence of four broad-scale genetic clusters in North America (FCT = 0.035) and identified nine fine-scale subclusters using more powerful spatial methods. An assessment of historical patterns of migration suggests that polar bears migrated into North America from the Beaufort Sea after the last glacial maximum. Using a conservative approach, we identified 17 loci that may represent adaptive variation, including one SNP in the 3’ untranslated region of PDLIM5 (PDZ And LIM Domain 5), a gene involved in cardiovascular function, which has undergone substantial selection in polar bears since their divergence from brown bears. Outlier loci differentiated the Norwegian Bay genetic cluster more strongly from remaining clusters than did our complete dataset, suggesting possible adaptive differences in the High Arctic. Through careful consideration of SNP loci, sample inclusion, and analytical approaches, we provide a comprehensive picture of polar bear population structure at a continental level. This study provides a model for the analysis of wide-ranging species that can contribute to their conservation and management.

How to choose the optimization criterion of the objective function is an important issue for uncertain optimal control. The Hurwicz criterion is a flexible optimization criterion attempting to find the intermediate area between the extremes posed by the optimistic and pessimistic criteria. Based on uncertainty theory, in this paper, we establish a new uncertain optimal control model with jump by making use of Hurwicz criterion to optimize an uncertain objective function. By applying Bellman's principle of optimality, the principle of optimality for the proposed model is presented and then the equation of optimality is derived. Finally, an example is given to show the the effectiveness of the results obtained.

In this paper, we study the asymptotic behavior of the discrete Kuramoto model on graphs. The main research method is: by using the theory of graph limits, we rigorously justify that the solutions of the initial value problems (IVPs) for the discrete Kuramoto model with external drive convergence to the solution of the initial value problem for its continuum limit on deterministic graphs, W-random graphs and SW graphs.

The paper deals with mixed boundary value problems in a cubic elastic half-plane. The formulation of the problem depends on an asymptotic model derived for anisotropic materials. It is demonstrated that defining the displacements in terms of a pair of plane harmonic functions reduces the problem to a classical isotropic form, which can be formulated within the framework of the asymptotic hyperbolic-elliptic model developed for isotropic materials. As an example, a semi-infinite rigid stamp moving at a constant speed along the surface is considered

Being able to think, express, learn and communicate with other humans brings interconnections that define our culture and society. Technology has shaped history, brought forward by generations of craftsmen, engineers, mathematicians. It is hard to see how humans could evolve without cooperation, trust and a common cognitive capacity, enabled through the language of science.Technology is often part of the equation of understanding complex questions. Injecting ideas into a thinking machine let us automatically interpret patterns in sensory data that otherwise is invisible for the human brain, or solve problems that otherwise would take immense labor and time. We often call these concepts learning and problem-solving.  As technology has evolved, we have emerged from war-time mechanical machines to supercomputers enabled by developments in silicon material. The field of artificial intelligence investigates the possibility for the computer to learn, reason and think.The question of whether a machine can think is not new.  Alan Turing, a mathematician from Cambridge University, made a philosophical standpoint by presenting the popular theoretical test, the "Imitation Game" in his 1950 paper "Computing machinery and intelligence" \cite{TURING_1950}.  Whether the opponent is a computer or not, is decided by a human interrogator who makes a decision when the game ends. As Stevan Harnad points out\cite{cogprints1584}, a thinking machine that is indistinguishable to any judge has capacities of infinity possible interactions with the real world, and therefore cannot win the game. Although some claim to have successfully passed a limited version of the test\cite{human}, Harnad interprets the test about how machines can generate cognitive capacity similar to humans.  For our concerns over technology gone wrong, we would not expect machine intelligence to conquer humans physically, but thinking machines might indeed influence and shape our decisions about economy, politics and personal relations through the way we communicate in a modern world. Algorithms edit the world we perceive, leading to allegations of mistrust, lost opportunities, skewed elections, and echo chambers of thoughts, best demonstrated by the 2018 Cambridge Analytica scandal\cite{widens}. Our daily stream of information input may well consist of elements where the Turing test has been passed without our awareness.

In this paper we are interested in two-dimensions fragmentation process that describes the evolution of an object having a rectangular shape. We focus on the non-homogenous fragmentation process where we break a rectangle according to a distribution that depends on its dimensions. Via Integral equations tools, we compute the mean and the variance of the distribution of the total number of the sub-rectangles obtained at the end of the process.

In this paper we investigate the global existence of small data solutions for the following structurally damped σ-evolution model with nonlinear memory term % \[u_{tt}+(-\Delta)^\sigma u+\mu(-\Delta)^{\frac{\sigma}{2}}u_t=\int_0^t (1+\tau)^{-\gamma}|u_t(\tau,\cdot)|^p\,d\tau,\] % with σ>0. In particular, for $\gamma\in ((n-\sigma)/n,1)$ we find the sharp critical exponent, under the assumption of small data in~$L^1$. Dropping the~$L^1$ smallness assumption of initial data, we show how the critical exponent is consequently modified for the problem. In particular, we obtain a new interplay between the fractional order of integration~$1-\gamma$ in the nonlinear memory term, and the assumption that initial data are small in~$L^m$, for some~$m>1$.

INTRODUCTION The article considers a system of two second order nonlinear differential equations with discontinuous functions on the right sides. The aim of the work is to obtain sufficient conditions for the existence, local uniqueness, and asymptotic stability of a stationary solution of a parabolic system with a large gradient in the vicinity of the discontinuity points of the right-hand sides. The area where the function undergoes large gradient is called the internal transition layer. The authors arrived at this formulation of the problem during the development of the autowave model for the development of megacities . This model is based on the activator-inhibitor system of two equations where the urban area acts as the activator, and the inhibitor is determined by environmental or economic factors due to urban planning policies of a country. The presence of barriers that prevent the propagation of the front of the activator, for example, large bodies of water, is taken into account in the model as a jump in the functions on the right-hand sides. Obviously, the numerical solution of such a problem should be preceded by an analytical study of the existence of the mentioned solution, which was done in the present work. The proof of the existence and asymptotic stability of the stationary solution of the initial-boundary-value problem here is carried out using the asymptotic method of differential inequalities , based on the method of super- and subsolutions.The latter was extended to problems with a single discontinuity point of the first kind on the right-hand sides of the equations based on a modified proof of the corresponding theorem from , where it was carried out for the case of C² continuous right-hand sides.

Maintenance of a portfolio of adaptive alleles may provide resilience of populations to natural environmental variability. We used Pacific ocean perch (POP; Sebastes alutus) to test for the maintenance of adaptive variation across overlapping generations. POP are a long-lived species characterized by widespread larval dispersal in their first year and a longevity of over 100 years. In order to understand how early marine dispersal affects POP survival and population structure, we used Restriction Site Associated DNA sequencing (RADseq) to obtain 11,146 single-nucleotide polymorphisms (SNPs) from 401 young-of-the-year (YOY) POP collected during surveys conducted in 2014 (19 stations) and 2015 (4 stations) in the eastern Gulf of Alaska. Population clustering analysis showed that the POP samples represented four distinct ancestral populations mixed throughout the sampling area. Based on prior work on larval dispersal of POP, these larvae are most likely from distinct parturition locations that are mixing during their pelagic dispersal life stage. Latent factor mixed models revealed that POP larvae face significant selection during their first year at sea, which were specific to the year of their birth. Thus each adult cohort’s genetic composition is heavily influenced by the environmental conditions experienced during their first year at sea. Long-lived species relying on broadcast spawning strategies may therefore be uniquely resilient to environmental variability by maintaining a portfolio of cohort-specific adaptive genotypes, and age truncation due to overfishing of older cohorts may have detrimental effect on the population viability.

Animals rely on an array of environmental triggers or cues to make their behavioural and life-history decisions. In the case of brood parasites, it is adaptive to use a suitable host to guarantee maximum fitness. Despite the fact that the Eurasian reed warbler (Acrocephalus scirpaceus) is the most frequent host of the common cuckoo (Cuculus canorus), we video recorded that cuckoo young often fall out of the nests of this host before fledging time and drown. To establish whether these events are influenced by the size of the nest, we replaced original Eurasian reed warbler nests for much bigger great reed warbler (Acrocephalus arundinaceus) nests and transferred cuckoo chicks into them. Subsequently, we video-recorded the fate of these cuckoo chicks. In these bigger nests, we recorded a significantly lower falling-out rate (4 of 29) compared with those remained in the real reed warbler nests (12 of 32). This result suggests that host nest size plays an important role in the suitability of reed warbler host species and that Eurasian reed warbler nests have a high mortality risk to the relatively big cuckoo chicks. Moreover, we found that cuckoo chicks that fell out of the nests were significantly less fed by foster parents during the three hours before falling-out event than chicks that stayed in the nests. This suggests that also insufficient parental care in terms of lower feeding intensity may facilitate falling-out of cuckoo chicks, probably because hungry chicks are more restless in host nests. The relatively high falling-out rate represents a substantial and underestimated cost of brood parasites. Moreover, without video surveillance it can be incorrectly confused with predation. Therefore, we strongly recommend using video-recording for estimating predation costs in birds.

Although research has focused on density-dependent responses to single parasite infections, much less in known about how parasite density affects the more common scenario in nature, co-infections. We investigate how parasite density alters co-infection dynamics by simultaneously exposing Cuban treefrogs (Osteopilus septentrionalis), in all pairwise combinations and at a range of doses, to: the nematode Aplectana hamatospicula, the chytrid fungus (Batrachochytrium dendrobatidis), and Ranavirus. The latter two parasites are implicated in widespread amphibian declines. We found that all pairwise co-infections were density dependent, but some were positively and others negatively density dependent, and these effects drove host pathology. Also, all co-infections were highly asymmetric – strong in one direction and weak in the other – consistent with weak and asymmetric interactions dominating food webs and mutualistic networks. These findings suggest that the null expectation for co-infections should be that they are density-dependent, asymmetric, and important to host health.

In this work, we define Rad-oplus-supplemented and strongly Rad-oplus-supplemented lattices and give some properties of these lattices. We generalize some properties of Rad-oplus-supplemented modules to lattices.

In this paper, we prove a local equivariant index theorem for sub-signature operators which generalizes Weiping Zhang's index theorem for sub-signature operators.

In this article, we study the zero-Hopf bifurcation of a quartic system in the three-dimensional space which can be obtained from a scalar the third-order ordinary differential equation.

In this work, we first propose the concept of stepanov-like almost automorphic functions on time scales, and present some properties, including the translation invariance and completeness. Moreover, we also prove the connection between stepanov-like almost automorphic functions on time scales and on $\mathbb{R}$. Then we establish some existence and uniqueness result of almost automorphic solutions for some linear dynamic equation on time scales. As an application of the above results, we study the existence and global exponential stability of almost automorphic solutions for a class of cellular neural networks with time-varying delays on time scales.

A Novel beam switch antenna based on a CRLH Butler matrix is presented in this manuscript. The CRLH transmission line is proposed to increase the number of beams switch. The proposed CRLH TL has more than 100- degree phase deference with different bias voltages. By different bias voltages between 0 to 8 Volt, different combinations of phase shifts are achieved. The CRLH transmission line is added to the conventional butler matrix to increase the number of phase incremental combination and consequently the beam pattern. A 5-degree beam resolution is achieved. The measurement results follow well with the simulation result.

Many scientific researches have shown an obvious fact that the quality control charts with variable sampling schemes are more effective than the classical ones in improving statistical measures. The average number of false alarms (ANF), the average number of samples (ANS), the average number of inspected items (ANI), and the adjusted average time to signal (AATS) are the most important statistical measures that have always been attending in the evaluation of control charts. In this paper, a comprehensive analytical review on the U control chart by the statistical measures have been explained. For this purpose, different levels of the possible factors are determined and presented the results of calculating the statistical measures with the obtained parameters on the sampling schemes of the U control chart. It is shown that the variable U control charts are able to improve the effectiveness statistical, especially for detecting shifts and number of false alarms.

While most people know the rich flavors, pleasant tastes, and numerous health benefits of teas, various contaminations with chemicals for controling weeds, insects, microbial pathogens and other tea garden managements, become increasingly concerned on tea products. Meanwhile most of tea secondary metabolites concentrated in tea leaves, such as catechins, affeine, volatiles, saponins, and theanine, are synthesized primarily for defenses against both biotic and abiotic stresses. However, few use of these plant natural products for weed, pest and disease control by tea producers disabled the sustainable and safty production of teas. This is partly because the lacking of detailed information about biosynthesis, regulation, defense mechanism of these tea specialized metabolites due to chemical diversity and metabolic complexicity. An in-depth understanding of the biosynthesis, regulation, and defensive mechanisms of these specialized metabolites would greatly facilitate the employment of the innate immunity of tea plants to minimaize the use of other health-harmful chemicals. The review highlights relevant contexts of metabolic genomics of tea plants, so as to guaide future research on genetic improvement of tea plants for both safety and nutritional quality of teas.

1. Numerous evidence agree that global changes have altered plant phenology, abiotic factors and functional traits are center drivers linking phenology. However, few studies have considered the joint effects of these factors on flowering phenology under nitrogen (N) inputs and biodiversity loss. 2. A common garden experiment with two N addition and six plant diversity levels was established in Beijing. We assessed the effects of N addition and plant diversity loss on three flowering phenology events of Medicago sativa via functional traits and abiotic factors. 3. The first flowering day (FFD) delayed, the last flowering day (LFD) advanced, and flowering duration (FD) shortened after N addition. While FFD advanced, LFD delayed, and FD extended an average of 0.31, 0.64, and 0.95 days per species lost, respectively. Importantly, three analysis methods had been used to prove that the contributions of functional traits for the variance in flowering phenology changes was significantly larger than abiotic factors under biodiversity loss and N addition. 4. Our findings illustrate the non-negligible effects of functional traits on flowering phenology, and highlight the importance of including functional traits in phenology models to improve predictions of the response of plant phenology to N inputs and biodiversity loss.

The hydrosilylation is one of the largest scale applications for homogeneous catalysis and is widely used to commercialize silicon products. However, the development of highly versatile heterogeneous catalytic systems to efficiently catalyze the hydrosilylation of alkenes remains a significant challenge. This work used a heat-assisted impregnation method followed by a mild reduction with sodium borohydride to will support a catalyst of platinum (Pt/IDA-MIL-101) supported on amine and carboxyl functionalized Metal-Organic Frameworks (MOFs) allowing for alkenes hydrosilylation reaction. IDA plays a key role in forming platinum nanoparticles that are uniform and well dispersed. More interestingly, IDA changes the pore size of the MIL-101 during the experiment. The Hydrosilylation experiments of olefins show that the reaction can effectively catalyze alkenes without solvents. Also, the synthetic heterogeneous catalyst Pt/IDA-MIL-101 achieves reasonable utilization of Pt in terms of cycle number and atomic utilization, demonstrating the potential for achieving a green hydrosilation industry.