bluuebunny/crossref_metadata_2025 huggingface dataset:
Neuronal adaptation and optimal coding in economic decisions
Authors: Rustichini Aldo , Conen Katherine E , Cai Xinying , Padoa-Schioppa Camillo
Published: June 2017

During economic decisions, neurons in orbitofrontal cortex (OFC) encode the values of offered goods. Importantly, their responses adapt to the range of values available in any given context. Prima facie, range adaptation seems to provide an efficient representation. However, uncorrected adaptation in the encoding of offer values would induce arbitrary choice biases. Thus a fundamental and open question is whether range adaptation is behaviorally advantageous. Here we present a theory of optimal coding for economic decisions. In a nutshell, the representation of offer values is optimal if it ensures maximal expected payoff. In this framework, we examine the activity ofoffer valuecells in non-human primates. We show that their firing rates are quasi-linear functions of the offered values, even when optimal tuning functions would be highly non-linear. Most importantly, we demonstrate that for linear tuning functions range adaptation maximizes the expected payoff, even if the effects of adaptation are corrected to avoid choice biases. Thus value coding in OFC is functionally rigid (linear tuning) but parametrically plastic (range adaptation with optimal gain). Importantly, the benefit of range adaptation outweighs the cost of functional rigidity. While generally suboptimal, linear tuning may facilitate transitive choices.
Glucose limitation inLactococcusshapes a single-peaked fitness landscape exposing membrane occupancy as a constraint
Authors: Price Claire E. , dos Santos Filipe Branco , Hesseling Anne , Uusitalo Jaakko J. , Bachmann Herwig , Benavente Vera , Goel Anisha , Berkhout Jan , Bruggeman Frank J. , Marrink Siewert-Jan , Montalban-Lopez Manolo , Jong Anne de , Kok Jan , Molenaar Douwe , Poolman Bert , Teusink Bas , Kuipers Oscar P.
Published: June 2017

A central theme in biology is to understand the molecular basis of fitness: which strategies succeed under which conditions; how are they mechanistically implemented; and which constraints shape trade-offs between alternative strategies. We approached these questions with parallel bacterial evolution experiments in chemostats. Chemostats provide a constant environment with a defined resource limitation (glucose), in which the growth rate can be controlled. UsingLactococcus lactis, we found a single mutation in a global regulator of carbon metabolism, CcpA, to confer predictable fitness improvements across multiple growth rates.In silicoprotein structural analysis complemented with biochemical and phenotypic assays, show that the mutation reprograms the CcpA regulon, specifically targeting transporters. This supports that membrane occupancy, rather than biosynthetic capacity, is the dominant constraint for the observed fitness enhancement. It also demonstrates that cells can modulate a pleiotropic regulator to work around limiting constraints.
More than Drylands but Less of Dry Forests
Authors: Cruz Marcelino de la , Quintana-Ascencio Pedro F. , Cayuela Luis , Espinosa Carlos I. , Escudero Adrián
Published: June 2017

The recent Global Drylands Assessment of forests is based on both an incomplete delimitation of dry forests distribution and on an old and incorrect delimitation of drylands. Its sampling design includes a large proportion of plots located in humid ecosystems and ignores critical areas for the conservation of dry forests. Therefore its results and conclusions are unreliable.
Centriole triplet microtubules are required for stable centriole formation and inheritance in human cells
Authors: Wang Jennifer T. , Kong Dong , Hoerner Christian R. , Loncarek Jadranka , Stearns Tim
Published: June 2017

Centrioles are composed of long-lived microtubules arranged in nine triplets. In unicellular eukaryotes, loss of the noncanonical tubulins, delta-tubulin and epsilon tubulin, result in loss of the triplet microtubule structure. However, the contribution of triplet microtubules to mammalian centriole formation and stability is unknown. Here, we report the first characterization of delta-tubulin and epsilon-tubulinnullhuman cells. Centrioles in cells lacking either delta-tubulin or epsilon-tubulin lack triplet microtubules and fail to undergo centriole maturation. These aberrant centrioles are formedde novoeach cell cycle, but are unstable and do not persist to the next cell cycle, leading to a futile cycle of centriole formation and disintegration. Disintegration can be suppressed by paclitaxel treatment. Delta-tubulin and epsilon-tubulin physically interact, indicating that these tubulins act together to maintain triplet microtubules and that these are necessary for inheritance of centrioles from one cell cycle to the next.
DDX54 regulates transcriptome dynamics during DNA damage response
Authors: Milek Miha , Imami Koshi , Mukherjee Neelanjan , Bortoli Francesca De , Zinnall Ulrike , Hazapis Orsalia , Trahan Christian , Oeffinger Marlene , Heyd Florian , Ohler Uwe , Selbach Matthias , Landthaler Markus
Published: June 2017

The cellular response to genotoxic stress is mediated by a well-characterized network of DNA surveillance pathways. The contribution of post-transcriptional gene regulatory networks to the DNA damage response (DDR) has not been extensively studied. Here, we systematically identified RNA-binding proteins differentially interacting with polyadenylated transcripts upon exposure of human breast carcinoma cells to ionizing radiation (IR). Interestingly, more than 260 proteins, including many nucleolar proteins, showed increased binding to poly(A)+RNA in IR-exposed cells. The functional analysis of DDX54, a candidate genotoxic stress responsive RNA helicase, revealed that this protein is an immediate-to-early DDR regulator required for the splicing efficacy of its target IR-induced pre-mRNAs. Upon IR exposure, DDX54 acts by increased interaction with a well-defined class of pre-mRNAs that harbor introns with weak acceptor splice sites, as well as by protein–protein contacts within components of U2 snRNP and spliceosomal B complex, resulting in lower intron retention and higher processing rates of its target transcripts. Because DDX54 promotes survival after exposure to IR, its expression and/or mutation rate may impact DDR-related pathologies. Our work indicates the relevance of many uncharacterized RBPs potentially involved in the DDR.
A two-dimensional copper(II) coordination polymer based on 2,4′-oxybis(benzoate) and 4,4′-bipyridine
Authors: Tang Long , Zhang Juan , Liu Xiao-Xia , Wang Ji-Jiang , Fu Feng
Published: June 2017

The reaction of Cu(NO3)2·3H2O with 2,4′-oxybis(benzoic acid) and 4,4′-bipyridine under hydrothermal conditions produced a new mixed-ligand two-dimensional copper(II) coordination polymer, namely poly[[(μ-4,4′-bipyridine-κ2
N,N′)[μ-2,4′-oxybis(benzoato)-κ4
O
2,O
2′:O
4,O
4′]copper(II)] monohydrate], {[Cu(C14H8O5)(C10H8N2)]·H2O}
n
, which was characterized by elemental analysis, IR spectroscopy, thermogravimetric analysis and single-crystal X-ray diffraction. The X-ray diffraction crystal structure analysis reveals that the CuII ions are connected to form a two-dimensional wave-like network through 4,4′-bipyridine and 2,4′-oxybis(benzoate) ligands. The two-dimensional layers are expanded into a three-dimensional supramolecular structure through intermolecular O—H...O and C—H...O hydrogen bonds. Furthermore, magnetic susceptibility measurements indicate that the complex shows weak antiferromagnetic interactions between adjacent CuII ions.
Thermoelectric transport properties in magnetically ordered crystals
Authors: Grimmer Hans
Published: June 2017

The forms of the tensors describing thermoelectric transport properties in magnetically ordered crystals are given for frequently used orientations of the 122 space-time point groups up to second order in an applied magnetic field. It is shown which forms are interchanged for the point groups of the hexagonal crystal family by two different conventions for the connection between the Hermann–Mauguin symbol and the orientation of the Cartesian coordinate system. The forms are given in Nye notation, which conspicuously shows how the forms for different point groups are related. It is shown that the measurable effects in magnetically ordered crystals can be decomposed into an effect occurring in all crystals and one coming from the magnetic ordering. Errors in the literature are pointed out.
An on-line Kriging metamodel assisted robust optimization approach under interval uncertainty
Authors: Zhou Qi , Jiang Ping , Shao Xinyu , Zhou Hui , Hu Jiexiang
Published: June 2017

Purpose

Uncertainty is inevitable in real-world engineering optimization. With an outer-inner optimization structure, most previous robust optimization (RO) approaches under interval uncertainty can become computationally intractable because the inner level must perform robust evaluation for each design alternative delivered from the outer level. This paper aims to propose an on-line Kriging metamodel-assisted variable adjustment robust optimization (OLK-VARO) to ease the computational burden of previous VARO approach.

Design/methodology/approach

In OLK-VARO, Kriging metamodels are constructed for replacing robust evaluations of the design alternative delivered from the outer level, reducing the nested optimization structure of previous VARO approach into a single loop optimization structure. An on-line updating mechanism is introduced in OLK-VARO to exploit the obtained data from previous iterations.

Findings

One nonlinear numerical example and two engineering cases have been used to demonstrate the applicability and efficiency of the proposed OLK-VARO approach. Results illustrate that OLK-VARO is able to obtain comparable robust optimums as to that obtained by previous VARO, while at the same time significantly reducing computational cost.

Practical implications

The proposed approach exhibits great capability for practical engineering design optimization problems under interval uncertainty.

Originality/value

The main contribution of this paper lies in the following: an OLK-VARO approach under interval uncertainty is proposed, which can significantly ease the computational burden of previous VARO approach.
On deterministic procedures for low-cost multi-objective design optimization of miniaturized impedance matching transformers
Authors: Koziel Slawomir , Bekasiewicz Adrian
Published: June 2017

Purpose

This paper aims to investigate deterministic strategies for low-cost multi-objective design optimization of compact microwave structures, specifically, impedance matching transformers. The considered methods involve surrogate modeling techniques and variable-fidelity electromagnetic (EM) simulations. In contrary to majority of conventional approaches, they do not rely on population-based metaheuristics, which permit lowering the design cost and improve reliability.

Design/methodology/approach

There are two algorithmic frameworks presented, both fully deterministic. The first algorithm involves creating a path covering the Pareto front and arranged as a sequence of patches relocated in the course of optimization. Response correction techniques are used to find the Pareto front representation at the high-fidelity EM simulation level. The second algorithm exploits Pareto front exploration where subsequent Pareto-optimal designs are obtained by moving along the front by means of solving appropriately defined local constrained optimization problems. Numerical case studies are provided demonstrating feasibility of solving real-world problems involving expensive EM-simulation models of impedance transformer structures.

Findings

It is possible, by means of combining surrogate modeling techniques and constrained local optimization, to identify the set of alternative designs representing Pareto-optimal solutions, in a realistic time frame corresponding to a few dozen of high-fidelity EM simulations of the respective structures. Multi-objective optimization for the considered class of structures can be realized using deterministic approaches without defaulting to evolutionary methods.

Research limitations/implications

The present study can be considered a step toward further studies on expedited optimization of computationally expensive simulation models for miniaturized microwave components.

Originality/value

The proposed algorithmic solutions proved useful for expedited multi-objective design optimization of miniaturized microwave structures. The problem is extremely challenging when using conventional methods, in particular evolutionary algorithms. To the authors’ knowledge, this is one of the first attempts to investigate deterministic surrogate-assisted multi-objective optimization of compact components at the EM-simulation level.
Computational method for determining the mechanical tension in a self-anchored suspension bridge during construction and its engineering application
Authors: Lu Pengzhen , Shao Hua , Cheng Jian Ting
Published: June 2017

Purpose

The purpose of this paper is to develop a simplified optimization calculation method to assess cable force of self-anchored suspension bridge based on optimization theories.

Design/methodology/approach

A simplified analysis method construction using Matlab is developed, which is then compared with the optimization method that considers the main cable’s geometric nonlinearity with software ANSYS in an actual bridge calculation.

Findings

This contrast proves the weak coherence and the adjacently interaction theory unreasonable and its limitation.

Originality/value

This paper analyzes the calculation method to assess cable force of a self-anchored suspension bridge and its application effect.
Model assessment in scientific computing
Authors: Prabhu Saurabh , Atamturktur Sez , Cogan Scott
Published: June 2017

Purpose

This paper aims to focus on the assessment of the ability of computer models with imperfect functional forms and uncertain input parameters to represent reality.

Design/methodology/approach

In this assessment, both the agreement between a model’s predictions and available experiments and the robustness of this agreement to uncertainty have been evaluated. The concept of satisfying boundaries to represent input parameter sets that yield model predictions with acceptable fidelity to observed experiments has been introduced.

Findings

Satisfying boundaries provide several useful indicators for model assessment, and when calculated for varying fidelity thresholds and input parameter uncertainties, reveal the trade-off between the robustness to uncertainty in model parameters, the threshold for satisfactory fidelity and the probability of satisfying the given fidelity threshold. Using a controlled case-study example, important modeling decisions such as acceptable level of uncertainty, fidelity requirements and resource allocation for additional experiments are shown.

Originality/value

Traditional methods of model assessment are solely based on fidelity to experiments, leading to a single parameter set that is considered fidelity-optimal, which essentially represents the values which yield the optimal compensation between various sources of errors and uncertainties. Rather than maximizing fidelity, this study advocates for basing model assessment on the model’s ability to satisfy a required fidelity (or error tolerance). Evaluating the trade-off between error tolerance, parameter uncertainty and probability of satisfying this predefined error threshold provides us with a powerful tool for model assessment and resource allocation.
Performance evaluation of local surrogate models in differential evolution-based optimum design of truss structures
Authors: Krempser Eduardo , Bernardino Heder S. , Barbosa Helio J.C. , Lemonge Afonso C.C.
Published: June 2017

Purpose

The purpose of this paper is to propose and analyze the use of local surrogate models to improve differential evolution’s (DE) overall performance in computationally expensive problems.

Design/methodology/approach

DE is a popular metaheuristic to solve optimization problems with several variants available in the literature. Here, the offspring are generated by means of different variants, and only the best one, according to the surrogate model, is evaluated by the simulator. The problem of weight minimization of truss structures is used to assess DE’s performance when different metamodels are used. The surrogate-assisted DE techniques proposed here are also compared to common DE variants. Six different structural optimization problems are studied involving continuous as well as discrete sizing design variables.

Findings

The use of a local, similarity-based, surrogate model improves the relative performance of DE for most test-problems, specially when using r-nearest neighbors withr= 0.001 and a DE parameterF= 0.7.

Research limitations/implications

The proposed methods have no limitations and can be applied to solve constrained optimization problems in general, and structural ones in particular.

Practical/implications

The proposed techniques can be used to solve real-world problems in engineering. Also, the performance of the proposals is examined using structural engineering problems.

Originality/value

The main contributions of this work are to introduce and to evaluate additional local surrogate models; to evaluate the effect of the value of DE’s parameter F (which scales the differences between components of candidate solutions) upon each surrogate model; and to perform a more complete set of experiments covering continuous as well as discrete design variables.
Wave sensitivity analysis for periodic and arbitrarily complex composite structures
Authors: Chronopoulos Dimitrios , Collet Manuel , Ichchou Mohamed
Published: June 2017

Purpose

This paper aims to present the development of a numerical continuum-discrete approach for computing the sensitivity of the waves propagating in periodic composite structures. The work can be directly used for evaluating the sensitivity of the structural dynamic performance with respect to geometric and layering structural modifications.

Design/methodology/approach

A structure of arbitrary layering and geometric complexity is modelled using solid finite element (FE). A generic expression for computing the variation of the mass and the stiffness matrices of the structure with respect to the material and geometric characteristics is hereby given. The sensitivity of the structural wave properties can thus be numerically determined by computing the variability of the corresponding eigenvalues for the resulting eigenproblem. The exhibited approach is validated against the finite difference method as well as analytical results.

Findings

An intense wavenumber dependence is observed for the sensitivity results of a sandwich structure. This exhibits the importance and potential of the presented tool with regard to the optimization of layered structures for specific applications. The model can also be used for computing the effect of the inclusion of smart layers such as auxetics and piezoelectrics.

Originality/value

The paper presents the first continuum-discrete approach specifically developed for accurately and efficiently computing the sensitivity of the wave propagation data for periodic composite structures irrespective of their size. The considered structure can be of arbitrary layering and material characteristics as FE modelling is used.
Applications of reduced order models in the aeroelastic analysis of long-span bridges
Authors: Ebrahimnejad L. , Janoyan K.D. , Valentine D.T. , Marzocca P.
Published: June 2017

Purpose

The application of reduced order models (ROMs) in the aerodynamic/aeroelastic analysis of long-span bridges, unlike the aeronautical structures, has not been extensively studied. ROMs are computationally efficient techniques, which have been widely used for predicting unsteady aerodynamic response of airfoils and wings. This paper aims to discuss the application of a reduced order computational fluid dynamics (CFD) model based on the eigensystem realization algorithm (ERA) in the aeroelastic analysis of the Great Belt Bridge (GBB).

Design/methodology/approach

The aerodynamic impulse response of the GBB section is used to construct the aerodynamic ROM, and then the aerodynamic ROM is coupled with the reduced DOF model of the system to construct the aeroelastic ROM. Aerodynamic coefficients and flutter derivatives are evaluated and compared to those of the advanced discrete vortex method-based CFD code.

Findings

Results demonstrate reasonable prediction power and high computational efficiency of the technique that can serve for preliminary aeroelastic analysis and design of long-span bridges, optimization and control purposes.

Originality/value

The application of a system identification tool like ERA into the aeroelastic analysis of long-span bridges is performed for the first time in this work. Authors have developed their earlier work on the aerodynamic analysis of long-span bridges, published in the Journal of Bridge Engineering, by coupling the aerodynamic forces with reduced DOF of structural system. The high computational efficiency of the technique enables bridge designers to perform preliminary aeroelastic analysis of long-span bridges in less than a minute.
Solving the coupled Sylvester-like matrix equations via a new finite iterative algorithm
Authors: Hajarian Masoud
Published: June 2017

Purpose

The purpose of this paper is to obtain an iterative algorithm to find the solution of the coupled Sylvester-like matrix equations.

Design/methodology/approach

In this work, the matrix form of the conjugate direction (CD) algorithm to find the solution X of the coupled Sylvester-like matrix equations:

{A1XB1+M1f1(X)N1=F1,A2XB2+M2f2(X)N2=F2,with fi(X) = X, fi(X) = X¯, fi(X) = XT and fi(X) = XH for i = 1; 2 has been established.

Findings

It is proven that the algorithm converges to the solution within a finite number of iterations in the absence of round-off errors. Finally, four numerical examples were used to test the proficiency and convergence of the established algorithm.

Originality/value

The numerical examples have led the author to believe that the generalized CD (GCD) algorithm is efficient and it converges more rapidly in comparison with the CGNR and CGNE algorithms.
MHD mixed convection stagnation point flow of a viscous fluid over a lubricated vertical surface
Authors: Mahmood Khalid , Sajid Muhammad , Ali Nasir , Javed Tariq
Published: June 2017

Purpose

An attempt is made to study magnetohydrodynamic viscous fluid impinging orthogonally toward a stagnation point on a vertical surface lubricated with power law fluid. It has been assumed that the surface temperature varies linearly with the distance from the stagnation point. The problem is governed by system of partial differential equations for both the base fluid and the lubricant. The continuity of velocity and shear stress is assumed at the interface layer between the base fluid and the lubricant. Dimensionless variables are introduced to transform original problem into ordinary differential equations. An implicit finite-difference scheme known as the Keller-Box method is implemented to obtain the numerical solutions. The influence of various important parameters is presented in the form of graphs and tables. The limiting cases for full and no-slip conditions are deduced from the present solutions. A comparison of the present results with the existing results in the special case validates the obtained numerical solutions. The purpose of this study is to see the behaviour of flow characteristics in the presence of lubrication.

Design/methodology/approach

The authors’ problem is governed by system of partial differential equations for both the base fluid and the lubricant. Dimensionless variables are introduced to transform original problem into ordinary differential equations. The obtained ordinary differential equation along with boundary conditions are highly nonlinear and coupled. An implicit finite-difference scheme known as the Keller-Box method is implemented to obtain the numerical solutions.

Findings

Some findings of this study are that the lubricant increases the velocity of the base fluid inside the boundary layer. In the case of full slip, the effects of viscosity are suppressed by the lubricant. The temperature of the base fluid decreases by increase in lubrication on the surface. By increasing the slip on the surface, the skin friction decreases and local Nusselt number increases, but the rate of increase or decrease is less in magnitude for the case of opposing flow. The similarity solutions only exist forn= 1/2. A non-similar solution is obtained for the other values of the power-law indexn.

Originality/value

The study of flow phenomenon over a lubricated surface has important applications in machinery components such as fluid bearings and mechanical seals. Coating is another major application of lubrication including the preparation of thin films, printing, painting, etc. The authors hope that the current study will provide the roadmap for the future studies in this direction.
Design and vibration analysis of a self-adaptive piston in a novel nanoimprint system
Authors: Liu Chaoran , Su Yufeng , Yue Jinzhao , Wang Junjie , Xia Weiwei , Li Dongxue , Wang Wen , Wang Pan , Duan Zhiyong
Published: June 2017

Purpose

A self-adaptive piston is designed for the compressional gas cushion press nanoimprint lithography system. It avoids the lube pollution and high wear of traditional piston.

Design/methodology/approach

The self-adaptive piston device consists of symmetrical piston bodies, piston rings and other parts. The two piston bodies are linked by a ball-screw. The locking nut adjusts the distance between two piston bodies to avoid the piston rings from being stuck. The piston rings are placed between two piston bodies.

Findings

The simulation results based on COMSOL indicate that cylinder vibration caused by self-adaptive piston is 15.9 times smaller than the one caused by a traditional piston.

Originality/value

The self-adaptive piston is superior to the traditional piston in decreasing cylinder vibration.
Theoretical research on sector oil-pads’ mechanical property in hydrostatic thrust bearing based on constant flow
Authors: Li Xibing , Cheng Tian , Li Ming , Li Mingjian , Wu Ruren , Wan Yingsi
Published: June 2017

Purpose

The purpose of this study with the rapid development of the heavy/large mechanical equipment, the heavy computer numerical control (CNC) vertical lathe has become the ideal processing equipment for the parts of those mechanical equipments. The main factor which affects the machining quality and efficiency of heavy CNC vertical lathe is the mechanical properties of the hydrostatic thrust bearing.

Design/methodology/approach

This paper did the research based on the large size sector oil pad’s lubrication performance of the hydrostatic thrust bearing in the heavy/large equipments, establishing the lubrication performance distribution mathematical model of the velocity field, flow field, pressure field and so on, analyzing the bearing behavior of the large size sector oil pad.

Findings

The results show that the oil flow generated by the plate relative motion will be greater than that generated by the pressure difference in area B, with the rotational speed’s increasing of the hydrostatic thrust bearing, and the direction is opposite. The oil flow generated by the centrifugal force will be greater than that generated by the pressure difference in area C, with the rotational speed’s increasing of the hydrostatic thrust bearing, and the direction is opposite. When the rotational speed of the hydrostatic thrust bearing is too high, the friction heat will be not easy to be sent out. The bearing rotating speed should be lower than the comparatively smaller one of ω1 and ω2, which can help avoid the rise of too high temperature.

Originality/value

The research provides powerful theoretical foundation for practical application of the large size sector oil pad hydrostatic thrust bearing, its structure design and operating reliability, realizing the lubrication performance prediction of the large size hydrostatic thrust bearing.
Wear characteristics of AlCrN coating on AISI 410 steel by the ball-cratering test method
Authors: Prabakaran Vijayasarathi , S. Ilaiyavel , P. SureshPrabhu , Thambu Sornakumar Samuel
Published: June 2017

Purpose

In this study the microstructure and wear characteristics of Multilayer AlCrN coated AISI 410 stainless steel with the physical vapor deposition technique.

Design/methodology/approach

The friction and wear performance of the ML-AlCrN-coated AISI410 steel and uncoated AISI410 steel sliding against with high carbon steel were investigated by the ball cratering test at room temperature. The tribological characteristic of coated AISI410 steel was determined by applying constant sliding velocity of 0.3927 ms−1 and total sliding distance of 353.43 m over various normal loads of 2, 3 and 4 N.

Findings

The AlCrN-coated AISI410 steel showed excellent wear performance up to 4 N load. The uncoated AISI410 steel showed good to acceptable wear resistance up to 2 N load. The wear tracks and worn surface were examined by scanning electron microscopy with energy-dispersive X-ray spectroscopy (EDS) attachment for explaining the differences in wear mechanism.

Originality/value

The ability of coating to delay substrate oxidation, with an excellent wear resistance, was identified under different parameters on worn areas.
Experimental investigations of rheological behaviour and thermal conductivity of nanogrease
Authors: Mohamed Alaa , Hamdy Mohamed , Bayoumi Mohamed , Osman Tarek
Published: June 2017

Purpose

This work describes the fabrication of composite nanogrease based on carbon nanotubes (CNTs) as an additive at different volume concentrations 0, 0.5, 1, 2 and 3 Wt.% and investigates the correlation between CNTs and grease rheological behaviour. In addition, study the influence of shear thinning rate at various temperatures and investigates the thermal conductivity of nanogrease. The results demonstrated that grease behaves like a Newtonian viscoelastic material with a narrow linear domain. The thermal conductivity of nanogrease was enhanced by about 31.58 per cent, and the thermal and mechanical stabilities improved. Moreover, the apparent viscosity and dropping point increased by about 93 and 27 per cent, respectively.

Design/methodology/approach

Grease was dissolved in chloroform (10 Wt.%), at 25°C for 1 h. In parallel, functionalized CNTs with different volume concentrations (0.5, 1, 2 and 3 Wt.%) were dispersed in N,N-dimethylformamide; the dispersion was stirred for 15 min, and then sonicated (40 kHz, 150 W) for 30 min. Grease solution was then added to the CNTs. The nanofluid was magnetically stirred for 15 min and then sonicated for 2 h. This ensured uniform dispersion of nanoparticles in the base fluid.

Findings

Inexpensive and simple fabrication of nanogrease. Thermal conductivity of nanogrease was typically enhanced compared to other reported studies. Apparent viscosity and dropping point increases with the increase the volume concentration.

Originality/value

This work describes the inexpensive and simple fabrication of nanogrease for improving properties of lubricants, which improve power efficiency and extend lifetimes of mechanical equipment.
A response‐surface examination of competition and facilitation between native and invasive juvenile fishes
Authors: Nelson Kirsten A. , Collins Scott F. , Sass Greg G. , Wahl David H.
Published: June 2017

Ecological theory has long recognised the importance of positive and negative species interactions as drivers of food web structure, yet many studies have only focused on competition. Because competitive and facilitative mechanisms operate simultaneously, but through different food web pathways, the balance of their combined effects can produce complex and variable responses.

We used a response‐surface experimental design to assess the roles of negative (e.g. intra‐, interspecific competition) and positive (e.g. facilitation) interactions between native and invasive juvenile fishes. We tested whether these interactions alter the densities of planktonic and benthic invertebrates to evaluate the magnitude and mechanism(s) influencing the acceptance or resistance of biological invaders. Interactions between bighead carp (Hypophthalmichthys nobilis) and bluegill (Lepomis macrochirus) or common carp (Cyprinus carpio) were evaluated in mesocosms.

Intraspecific interactions were 1.5–2.4 times stronger than interspecific interactions between carp species. The only instance of interspecific competition resulted in bighead carp reducing the daily growth of bluegill, whereas the reciprocal interaction resulted in facilitation. Facilitation occurred when bluegill increased the daily growth of low density bighead carp treatments, despite increased numbers of fishes. Bighead carp also increased densities of benthic Chironomidae larvae, which were subsequently consumed by bluegill, but did not result in enhanced bluegill growth. These suites of interactions were not observed between common and bighead carp.

Our response‐surface design proved useful for comparing the relative magnitude of intra‐ vs. interspecific competition, identifying facilitation among species, and tracing attendant effects on invertebrate communities. By accounting for the directionality of interactions within our experimental framework and tracking responses of prey at lower trophic levels, we provide a clearer understanding of how competitive effects and stressed consumers alter prey communities and influence facilitation.

A plain language summary
is available for this article.
Tree species vary widely in their tolerance for liana infestation: A case study of differential host response to generalist parasites
Authors: Visser Marco D. , Schnitzer Stefan A. , Muller‐Landau Helene C. , Jongejans Eelke , de Kroon Hans , Comita Liza S. , Hubbell Stephen P. , Wright S. Joseph
Published: June 2017

Lianas are structural parasites of trees and reduce individual host tree growth, survival and fecundity. Thus, liana infestation is expected to affect tree population growth rates, with potentially different effects in different species depending on the frequency of liana infestation and the impact of liana infestation on population growth rates. Previous studies have documented the myriad negative effects of lianas on trees and variation in liana infestation among tree species; however, no study has quantified the impact of liana infestation on individual tree species population growth rates. Lianas are increasing in abundance in multiple Neotropical sites, which may have profound consequences for tree species composition if lianas differentially affect host tree species population growth.

Here, we use long‐term data to evaluate the effects of liana infestation on the reproduction, growth, survival and ultimately population growth rates of dozens of tree species from Barro Colorado Island, Panama. We then test whether liana infestation affects tree species differentially with respect to two axes of life‐history variation: adult stature and position along the fast–slow axis, a measure of shade tolerance.

Liana infestation decreased tree growth, survival and reproduction, with the strongest effects on survival in fast‐growing, light‐demanding species and on reproduction in large‐statured species. In combination, these effects reduced tree population growth rates such that liana‐infested populations declined by an average of 1.4% annually relative to conspecific liana‐free populations. The reduction in population growth rates was greatest among fast‐growing species and smaller in slow‐growing species.

Synthesis. Our results demonstrate that liana infestation has strong negative effects on tree population growth rates, which vary systematically among tree species with tree life history. The finding that liana infestation is more harmful to fast‐growing tree species appears to be at odds with the general expectations in the literature. We propose that this is likely due to survivorship bias, as infestation greatly decreases survival in fast‐growing species such that the observable sample is biased towards those that survived and liana‐free. In combination with data on how tree species vary in liana infestation rates, these results provide a basis for predicting the impacts of changes in liana abundance on tree species composition.
Neighbourhood effects on plant reproduction: An experimental–analytical framework and its application to the invasive Senecio inaequidens
Authors: Lachmuth Susanne , Henrichmann Colette , Horn Juliane , Pagel Jörn , Schurr Frank M.
Published: June 2017

Density dependence is of fundamental importance for population and range dynamics. Density‐dependent reproduction of plants arises from competitive and facilitative plant–plant interactions that can be pollination independent or pollination mediated. In small and sparse populations, conspecific density dependence often turns from negative to positive and causes Allee effects. Reproduction may also increase with heterospecific density (community‐level Allee effect), but the underlying mechanisms are poorly understood and the consequences for community dynamics can be complex. Allee effects have crucial consequences for the conservation of declining species, but also the dynamics of range edge populations. In invasive species, Allee effects may slow or stop range expansion.

Observational studies in natural plant communities cannot distinguish whether reproduction is limited by pollination‐mediated interactions among plants or by other neighbourhood effects (e.g. competition for abiotic resources). Even experimental pollen supply cannot distinguish whether variation in reproduction is caused by direct density effects or by plant traits correlated with density. Finally, it is unknown over which spatial scales pollination‐mediated interactions occur.

To circumvent these problems, we introduce a comprehensive experimental and analytical framework which simultaneously (1) manipulates pollen availability and quality by hand pollination and pollinator exclusion, (2) manipulates neighbourhoods by transplanting target plants, and (3) analyses the effects of con‐ and heterospecific neighbourhoods on reproduction with spatially explicit trait‐based neighbourhood models.

Applying this framework to Senecio inaequidens, one of Europe's fastest plant invaders, we found that the seed set was strongly pollen limited. Reproduction had increased by pollinator‐mediated facilitation by both con‐ and heterospecific neighbours which may lead to (community‐level) Allee effects. Pollination‐independent interactions, such as amelioration of abiotic conditions through neighbours, contributed to additional positive neighbour effects. However, these pollination‐independent interactions were weaker than the pollination‐mediated interactions and they occurred over smaller spatial scales. Finally, the strength and direction of neighbourhood effects depended on neighbour traits and thus changed with the trait composition of the neighbourhood.

Synthesis. By manipulating both pollen availability and target plant locations within neighbourhoods, we can comprehensively analyse spatially explicit density dependence of plant reproduction. This experimental approach enhances our ability to understand the dynamics of sparse populations and of species geographical ranges.
The impact of drought and water scarcity on irrigator farm exit intentions in the Murray–Darling Basin
Authors: Wheeler Sarah Ann , Zuo Alec
Published: June 2017

Drought and future water scarcity in the Murray–Darling Basin (MDB) will continue to restructure the irrigation industry in the coming decades. There has been little work conducted in Australia that has modelled farm exit or exit intention. ABARES farm survey data were used to model irrigators’ farm exit intentions across the southern MDB from 2006 to 2013. In particular, we examined the hypotheses that drought and water scarcity positively impacted on farm exit intentions and that it is the poorest performing farms that intend to exit in times of drought. Results revealed that water scarcity impacts varied considerably. There was only weak evidence to suggest that irrigators’ exit intentions were higher in times of drought, but there was stronger evidence to support the influence of a lagged water scarcity impact on farm exit intentions during periods of nondrought (e.g. intending to exit at times when the property market was less depressed). There was also strong evidence that poorer performing farms (measured by rates of return and higher debt over a certain level) were more likely to have exit intentions in drought periods, but not necessarily so in nondrought periods. Older age is the most consistent predictor of farm exit intentions across all industries, though it was most significant in drought periods.
Ageing and memory medication: social rationales and consumption practices
Authors: Lopes Noémia , Pegado Elsa , Zózimo Joana R.
Published: June 2017

This article focuses on the social rationales underlying the consumption or rejection of medication for memory by the elderly. Our analysis is set within the wider frame of the current use of psychopharmaceuticals for the enhancement of everyday performance, discussing its relationship to new cultures of ageing. Our results, from a recently concluded study, point to different patterns of investment in memory in old age. On the one hand, we found a willingness to consume medication for memory – a heterogeneous disposition split between the imaginary of disease and that of performance enhancement. On the other hand, we found a cultural resistance and scepticism towards the use of psychopharmaceuticals for performance purposes. This suggests that a new frame of psychopharmaceuticalization of old age – represented by memory medication – is prompting different rationales, ranging from consumption to resistance.
Domestic Predation of an Elder: A Fatal Dog Attack Case
Authors: Le Garff Erwan , Mesli Vadim , Delannoy Yann , Pollard Jocelyn , Becart Anne , Hedouin Valéry
Published: June 2017

We present the case of a 91‐year‐old woman lived alone at her home with two domestic dogs, that is,, a Labrador Retriever and a Staffordshire Bull Terrier and found dead. The investigation of the scene revealed that the Bull Terrier's jawbone and chest were covered with blood. The autopsy revealed multiple, histologically confirmed, life‐threatening skin and bone lacerations without scavenging marks. The punctures and tearing of each of the wounds on the skin were compatible with bites. A left humeral fracture and multiple fractures of the right facial bones were observed. The death was attributed to external hemorrhages due to several dog bites. A veterinary physical and behavioral examination indicated that the Bull Terrier was involved in the attack. A domestic predation hypothesis was deemed here most likely due to the presence of food supplies at the scene, the dog's previous history of attack, and the breed of the dog.
“Undoing” (or Symbolic Reversal) at Homicide Crime Scenes
Authors: Russell Maria , Schlesinger Louis B. , Leon Maria , Holdren Samantha
Published: June 2017

A closed case file review of a nonrandom national sample of 975 homicides disclosed 11 cases (1.13%) of undoing, wherein offenders engaged in crime scene behavior that has been considered an attempt to symbolically reverse the murder. The frequency of the various methods of undoing involved the use of blankets to cover the victim's body (55%), positioning the body (55%), use of a bed or couch (42%), washing the body (36%), using pillows (36%), as well as removing clothing and adding other types of adornments (27%). Ten of the 11 offenders were male, and one was female; all 12 victims were female. Ten of the 12 victims were family members or relationship intimates. These findings are consistent with prior reports which concluded that the motivation for undoing behavior is an attempt to compensate for guilt or remorse for having committed the homicide.
Renal effects of an emergency department chloride‐restrictive intravenous fluid strategy in patients admitted to hospital for more than 48 hours
Authors: Yunos Nor'azim Mohd , Bellomo Rinaldo , Taylor David McD , Judkins Simon , Kerr Fergus , Sutcliffe Harvey , Hegarty Colin , Bailey Michael
Published: June 2017

Objective

Patients commonly receive i.v. fluids in the ED. It is still unclear whether the choice of i.v. fluids in this setting influences renal or patient outcomes. We aimed to assess the effects of restricting i.v. chloride administration in the ED on the incidence of acute kidney injury (AKI).

Methods

We conducted a before‐and‐after trial with 5008 consecutive ED‐treated hospital admissions in the control period and 5146 consecutive admissions in the intervention period. During the control period (18 February 2008 to 17 August 2008), patients received standard i.v. fluids. During the intervention period (18 February 2009 to 17 August 2009), we restricted all chloride‐rich fluids. We used the Kidney Disease: Improving Global Outcomes (KDIGO) staging to define AKI.

Results

Stage 3 of KDIGO‐defined AKI decreased from 54 (1.1%; 95% confidence interval [CI] 0.8–1.4) to 30 (0.6%; 95% CI 0.4–0.8) (P = 0.006). The rate of renal replacement therapy did not change, from 13 (0.3%; 95% CI 0.2–0.4) to 8 (0.2%; 95% CI 0.1–0.3) (P = 0.25). After adjustment for relevant covariates, liberal chloride therapy remained associated with a greater risk of KDIGO stage 3 (hazard ratio 1.82; 95% CI 1.13–2.95; P = 0.01). On sensitivity assessment after removing repeat admissions, KDIGO stage 3 remained significantly lower in the intervention period compared with the control period (P = 0.01).

Conclusion

In a before‐and‐after trial, a chloride‐restrictive strategy in an ED was associated with a significant decrease in the incidence of stage 3 of KDIGO‐defined AKI.
Microencapsulation of Corn Wastewater (Nejayote) Phytochemicals by Spray Drying and Their Release Under Simulated Gastrointestinal Digestion
Authors: Villela‐Castrejón Javier , Acosta‐Estrada Beatriz A. , Gutiérrez‐Uribe Janet A.
Published: June 2017

Corn lime cooking generates a large amount of wastewater known as nejayote that is composed of suspended solids and solubilized phytochemicals. Spray drying can be an alternative to recover bioactive molecules, such as ferulic acid, from nejayote. Besides the yield, the physicochemical properties (solubility, water activity, pH, moisture, hygroscopicity, total phenolic content, and distribution of free and bound hydroxycinnamic acids) of spray‐dried nejayote powders were analyzed. The powders were obtained at 200 °C/100 °C or 150 °C/75 °C (inlet/outlet) air temperatures with the addition of maltodextrin (MD) or 2‐hydroxypropyl‐beta‐cyclodextrin (HBCD) as encapsulating agents. Even when no carrier agent was used, a spray‐dried nejayote powder was produced. The use of MD or HBCD as carrier increased the yield from 60.26% to 68.09% or 71.83%, respectively. As expected, a high inlet temperature (200 °C) allowed a satisfactory yield (>70%) and a low powder moisture (2.5%) desired by the industry. Water activity was reduced from 0.586 to 0.307 when HBCD was used in combination with a drying inlet temperature of 150 °C; and from 0.488 to 0.280 when the inlet temperature was set at 200 °C. Around 100% bioaccessibility of the compounds was observed after in vitro digestion. The addition of HBCD increased the release time (P < 0.05). Under simulated physiological conditions, there was no reduction of total phenolics, suggesting a good stability. This paper showed the feasibility to engage the spray drying technology to the corn industry to minimize their residues and reuse their by‐products.