In this paper, we deal with the wave equation with acoustic boundary conditions. The exponential stabilization is obtained by Lyapunov approach and Riemannian geometry method. We then apply our main theorem to the wave equations with memory type acoustic boundary conditions, which is not available in the literature and give an example in the end.

The Dirichlet, Neumann and mixed boundary value problems for the linear second-order scalar elliptic differential equation with variable coefficient in a bounded three-dimensional domain are considered. The PDE right-hand side belongs to $H^{-1}(\Omega)$ or $\widetilde{H}^{-1}(\Omega),$ when neither classical nor canonical co-normal derivatives are well defined. Using the two-operator approach and appropriate parametrix (Levi function) each problem is reduced to different systems of boundary domain integral equations (BDIEs). Equivalence of the BDIEs to the original BVP, BDIE solvability, solution uniqueness/non-uniqueness, and as well as invertibility of the BDIE operators are analysed in appropriate Sobolev (Bessel potential) spaces. It is shown that the BDIE operators for the Neumann BVP are not invertible, and appropriate finite-dimensional perturbations are constructed leading to invertibility of the perturbed operators.

We consider a linear RLC network, modeled by differential-algebraic equations, containing distributed semiconductor devices, modeled by multi-dimensional parabolic-elliptic equations. With appropriate coupling conditions, we obtain a system of multidimensional partial differential-algebraic equations. For the resulting system, we prove an existence and uniqueness result, and study the asymptotic behavior of the solutions.

A linear manifold ${\mathcal K}_2$ of evolutionary equations for a pseudovector field on ${\Bbb R}^3$ is described. An infinitisimal shift of each equation is determined by a second-order differential operator of divergent type. All operators are invariant with respect to space translations in ${\Bbb R}^3$, relative to time translations, and they are transformed by covariant way relative to rotations of ${\Bbb R}^3$. It is proved that the linear space ${\mathcal M}_2 \subset {\mathcal K}_2$ of differential operators preserving solenoidal property and unimodularity of the field is one-dimensional and an explicit form of such operators is found.

Particle-laden flows in a vertical channel were simulated using an Eulerian–Eulerian, Anisotropic-Gaussian (EE-AG) model. Two sets of cases varying the overall mass loading were done using particle sizes corresponding to either a large or small Stokes number. Primary and turbulent statistics were extracted from these results and compared with counterparts collected from Eulerian–Lagrangian (EL) simulations. The statistics collected from the small Stokes number particle cases correspond well between the two models, with the EE-AG model replicating the transition observed using the EL model from shear-induced turbulence to relaminarization to cluster-induced turbulence as the mass loading increased. The EE-AG model was able to capture the behavior of the EL simulations only at the largest particle concentrations using the large Stokes particles. This is due to the limitations involved with employing a particle-phase Eulerian model (as opposed to a Lagrangian representation) for a spatially intermittent system that has a low particle number concentration.

The stock-specific distribution of maturing and adult salmon in the Northeast (NE) Pacific has been a persistent information gap that has prevented us from determining the ocean conditions experienced by individual stocks. This continues to impede understanding of the role of ocean conditions in stock-specific population dynamics. We assessed scale archives for 17 sockeye salmon (Oncorhynchus nerka) stocks covering the entire North Pacific, from the Columbia River to Kamchatka Peninsula, to define salmon locations during their last growing season before returning to their spawning grounds. We used the relationship between δ13C in salmon scales and sea water temperature to estimate salmon distribution based on correlation strength. Significant correlations were found for 13 of the stocks allowing us to define feeding grounds with confidence. Complementary information from δ15N, historical tagging studies, and connectivity analysis were used to further refine distribution estimates. Based on the estimated distributions of the NE Pacific stocks, we suggest a sequence of steps that could result in salmon marine distributions. This study is a first step toward determining stock-specific distributions of salmon in the NE Pacific, and provides a basis for the application of the approach to other salmon scale archives. This information will improve our ability to relate stock dynamics to ocean conditions, ultimately enabling improved stock management. For example, our estimated distributions of Bristol Bay and NE Pacific stocks demonstrated that they occupy different areas with a number of the former being distributed in the high productivity shelf waters of the Aleutian Islands and Bering Sea. This may explain while these stocks seem to have responded differently to changes in ocean conditions, and the long term trend of increased productivity of Bristol Bay sockeye.

We investigated the flow characteristics in a tank of H/T=1.5 stirred by a novel multi-blade combined agitator (MBC) by using time-resolved PIV and LES approach. The predictions were assessed by Y+ values and power spectrum analysis, as well as experimental validation of velocity distributions. Results demonstrate that the MBC agitator can load the energy into the system effectively with a power number of 12.5 in a turbulent regime, resulting in improved axial and radial mass exchange. The upper and lower short blades produce an axial down-flow in the top half and an axial up-flow in the bottom half, respectively. Part of axial flows change to radial flows by the radial pumping of the long blades, meanwhile, the impingement of two axial flows improves the axial mass exchange. These flow characteristics leads to an obvious improvement in the turbulent kinetic energy distribution uniformity.

Multiple breakdown phenomena may take place when operating dielectric elastomers. Thermal breakdown, which occurs due to Joule heating, becomes of special importance when using multilayered stacks of dielectric elastomers, due to the large volume-to-surface-area-ratio. In this article, a 2D axisymmetric finite-element model of a multilayered stack of dielectric elastomers is set up in \comsol. Both the electro-thermal and electro-mechanical couplings are considered, allowing for determination of the onset of thermal breakdown. Simulation results show that an entrapped particle in the dielectric elastomer drastically reduces the possible number of layers in the stack. Furthermore, the possible number of layers is greatly affected by the ambient temperature and the applied voltage. The performance of three hyperelastic material models for modelling the elastomer deformation are compared, and it is established that the Gent model yields the most restrictive prediction of breakdown point, while the Ogden model yields the least restrictive estimation.

The flow characteristics of the blade unit of a tridimensional rotational flow sieve tray was investigated experimentally in this study. First, the flow patterns are defined under different liquid arrangement methods. They are bilateral film flow, continuous perforated flow, and dispersion-mixing flow in overflow distribution and film and jet flow and jet and mixed flow in spray distribution. Second, the time and frequency domain analysis of the differential pressure pulsation signal in the blade unit is carried out. The influence of perforation and mixing intensity on the flow pattern transition is clarified. Third, the rotational flow ratio of the gas-liquid phase is measured. The influence of the operating conditions on the distribution of the rotational and perforated flow for the gas-liquid phase is investigated. Finally, a prediction model for the rotational flow ratio is proposed. The prediction results agree well with the experimental data.

Background and Objective Clinical Practice Guidelines (CPGs) provide evidence-based recommendations to healthcare professionals, policy makers, patients and other stakeholders. Mexico is the biggest producer of CPGs in Latin America and Caribbean countries. The National Healthcare Technology Excellence Center (acronym in Spanish: CENETEC) is responsible for the CPG development, adaptation and update. The aim of this study was to assess the Mexican CPG quality and adherence to the GRADE framework. Study design We conducted a descriptive cross-sectional study of 86 CPGs representing all the CPGs produced by CENETEC between 2015 and 2017 and published in an online database called “Catalogo Maestro”. We performed quality assessment with the online AGREE II tool and assessed the reporting on the GRADE framework. Results Of the 86 CPGs, 34 were published in 2015, 21 in 2016 and 31 in 2017. The overall quality by AGREE II proved a median of 16.6% (Min 16.6%, Max 50%). Of the 86 CPGs, 25 (29%) used the GRADE framework; adherence to GRADE standards was, however, inconsistent and generally poor. Conclusion CPGs produced by CENETEC during this period had a low score by AGREE II standards and low adherence to the GRADE framework. A concerted initiative could rapidly improve CENETEC guidelines.

The European eel (Anguilla anguilla) is critically endangered throughout its distribution range. Knowledge about age distribution of future spawners (silver eels) is essential to monitor the status and contribute to the recovery of this species. Determination of age in anguillid eels is challenging, especially in eels from the northern part of the distribution area where growth is slow and age at maturation can be up to 30 years or more. Eels from the river Imsa in Norway have been monitored since 1975 and this reference time-series has been used to assess the stock at the European level. Population dynamics in this catchment were analyzed during the late 1980s by estimating ages on whole cleared otoliths. However, techniques for revealing annual increments on otoliths have evolved over the years sometimes yielding significant differences in age estimates. In this study, the historical otolith data were reanalyzed using a grinding and polishing method rather than reading the whole otolith. The new age estimates were considerably higher than the previous ones, sometimes by up to 29 years. Since the 1980s, mean age of silver eels only slightly increased (from 19 to 21 years in the 2010s). This was mainly due to the disappearance of younger silver eels (less than 15 years) in the 2010s. The new age estimates agreed with the steep decline in recruitment which occurred in the late 1980s in the Imsa catchment. Growth (30 mm y-1) has not changed since the 1980s, although density in the catchment has decreased. Revealing and reading age of slow growing eels remain a challenge but adding a measure of otolith reading uncertainty may improve age data collection and contribute to recovery measures for this species.

Turtles have been prominent subjects of analyses of sexual size dimorphism (SSD) owing to their mating system and habitat diversity. In prior studies, marine turtles were grouped with non-marine aquatic turtles (NMAT). This is odd because it is well-established that the marine environment imposes a distinct selective milieu on body form of vagile vertebrates, driven by convergent adaptations for energy-efficient propulsion and drag reduction. We generated a comprehensive database of adult marine turtle body size (38,569 observations across all species), which we then used to evaluate both the magnitude of SSD in marine turtles and how it compares to SSD in NMAT. We find that marine turtles are not sexually size dimorphic, whereas NMAT typically exhibit female-biased SSD. We argue that the reason for this difference is the sustained long-distance swimming that characterises marine turtle ecology, which entails significant energetic costs incurred by both sexes. Hence, the ability of either sex to allocate proportionately more to growth than the other is likely constrained, meaning that sexual differences in growth and resultant body size are not possible. Consequently, lumping marine turtles with NMAT dilutes the statistical signature of different kinds of selection on SSD and should be avoided in future studies.

Introduction of a heterocyclic ring and an amino-ethyl-amino group to D-A type photosensitive dyes can modulate the lifetime of the charge separation generated in the D-A dyes as well as their electronic and UV-Vis absorption properties. Here we performed DFT and TDDFT calculations to study eleven derivatives of a triphenylamine-pyrimidine, MTPA-Pyc, in order to improve the performance of MTPA-Pyc as solar cell sensitizers. Five heterocyclic rings and an amino-ethyl-amino group were introduced on the styryl moiety of MTPA-Pyc. The results show that introduction of heterocyclic rings generally causes an absorption red-shift, but absorption intensity is reduced due to the increase of dihedral angle between the donor and acceptor. Further introduction of an amino-ethyl-amino group to these dyes with a heterocyclic ring modification disrupts the conjugation between donor and acceptor, which does not benefit the absorption but may have potential to increase the lifetime of charge separation of the dyes. This work identified two out of eleven dyes that have the best potential for solar cell applications.

Sickness behaviour is a taxonomically-widespread coordinated set of behavioural changes that in- creases shelter-seeking while reducing levels of general activity, as well as food (anorexia) and water (adipsia) consumption, when fighting infection by pathogens and disease. The leading hypothesis ex- plaining such sickness-related shifts in behaviour is the energy conservation hypothesis. This hypothe- sis argues that sick (i.e. immune-challenged) animals reduce energetic expenditure in order have more energy to fuel an immune response, which in some vertebrates, also includes producing an energetically- expensive physiological fever. We experimentally tested the hypothesis that an immune-challenge with lipopolysaccharide (LPS) will cause Gryllus firmus field crickets to reduce their activity, increase shelter- use and avoid foods that interfere with an immune response (i.e. fat) while preferring a diet thats fuel an immune response (i.e. protein). We found little evidence of sickness behaviour in Gryllus firmus as immune-challenged individuals did not reduce their activity or increase their shelter-seeking. Neither did we observe changes in feeding or drinking behaviour nor a preference for protein or avoidance of lipids. Males tended to use shelters less than females but no other behaviours differed between the sexes. The lack of sickness behaviour in our study might reflect the fact that invertebrates do not possess energetically-expensive physiological fever as part of their immune response. Therefore, there is little reason to conserve energy via reduced activity or increased shelter use when immune-challenged.

We present a new family of fast and robust methods for the calculation of the vapor-liquid equilibrium at isobaric-isothermal (PT-flash), isochoric-isothermal (VT-flash), isenthalpic-isobaric (HP-flash), and isoenergetic-isochoric (UV-flash) conditions. The framework is provided by formulating phase-equilibrium conditions for multi-component mixtures in an effectively reduced space based on the molar specific value of the recently introduced volume function derived from the Helmholtz free energy. The proposed algorithmic implementation can fully exploit the optimum quadratic convergence of a Newton method with the analytical Jacobian matrix. This paper provides all required exact analytic expressions for the general cubic equation of state. Computational results demonstrate the effectivity and efficiency of the new methods. Compared to conventional methods, the proposed reduced-space iteration leads to a considerable speed-up as well as to improved robustness and better convergence behavior near the spinodal and coexistence curves of multi-component mixtures, where the preconditioning by the reduction method is most effective.

Reproductive character displacement is a pattern whereby sympatric lineages diverge more in reproductive character morphology than allopatric lineages. This pattern has been observed in many plant species, but comparably few have sought to disentangle underlying mechanisms. Here, in a hyperdiverse lineage of Neotropical plants (Ruellia; Acanthaceae), we present evidence of reproductive character displacement in a macroevolutionary framework (i.e., among species) and document mechanistic underpinnings. In a series of inter-specific hand pollinations in a controlled glasshouse environment, we found that crosses between species that differed more in overall flower size, particularly in style length, were significantly less likely to produce viable seeds. Further, species pairs that failed to set seed were more likely to have sympatric distributions in nature. While these findings could result from competition for pollinators or differential fusion of sympatric populations based on variable crossability, our results instead lend support for a role of reinforcement whereby selection has acted to increase reproductive barriers between sympatric species, especially given divergence in floral traits less likely to be under selection by pollinators (i.e., style length). Our results add to growing evidence that character displacement contributes to exceptional floral diversity of angiosperms.

Water transit time and young water fraction are important metrics for characterizing catchment hydrologic function and understanding solute transport. Hydrological and biogeochemical processes in karst environments are strongly controlled by heterogenous fracture-conduit networks. Quantifying the spatio-temporal variability of water transit time and young water fractions in such heterogeneous hydrogeological systems is fundamental linking discharge and water quality dynamics in the karst critical zone. We used a tracer-aided hydrological model to track the fluxes of water parcels that entered a karst catchment as rainfall, time-stamping each hour of rain input individually. Using this approach, the variability of transit times and water age distributions were estimated in the main landscape units in the karst catchment of Chenqi in Guizhou Province, Southwest China. The estimated mean young water (i.e <~2 months old) fractions were 0.39, 0.31 and 0.10 for output fluxes from the hillslope unit, catchment outlet and slow flow reservoirs (matrix and small fractures), respectively. Marked seasonal variability in sources of runoff generation and associated hydrological connectivity between different conceptual stores were the main drivers of young water fraction dynamics in each landscape unit. The water age and travel time distributions were strongly influenced by the water storage dynamics reflecting catchment wetness conditions. Even though the contribution of young water to runoff was greater, the older water turnover was generally accelerated at moderately high flows during wet season.

Time-dependent density functional theory approach implemented at hybrid-B3LYP, GGA-PBE and DFTB levels of theory was used to model photoinjection in organic-dye/TiO2 quantum-dot to explore the prospects of improvement of DSSC. The photosensitizer used in this study consisted of six carbazole based organic dyes having acceptor as cyanoacrilic acid group and oligothiophene π-bridge spacer. The modifications were made in the dyes by increasing length of the spacer by adding thiophene and oxadiazole rings at different positions of the donor-acceptor bridge. The structural variations appeared to alter the electronic and optical properties of dyes studied via energy levels and excitation spectra. The UV-Vis spectra calculated for all the dyes in solvents exhibited a red shift in spectral peaks with increase in polarity of the solvents. The findings of the study pointed towards photoinjection of indirect nature studied in dye-(TiO2)96 complex for six different dyes. The substitution of oxadiazole ring in center and addition of a thiophene ring at the edge of the spacer produced two dyes which exhibited lowest injection energies of 0.11eV and 0.17 eV along with the regeneration energies of 1.18 eV and 1.12 eV respectively. The dyes reported herein may have promising applications in photoanode for enhancing the performance of DSSC.