bluuebunny/crossref_metadata_2025 huggingface dataset:
Influence of bamboo pile clusters in the pile mattress bamboo construction systems as reinforcement of soft subgrade that support embankment load
Authors: Widodo B , Pratikso  , Rochim A , Irsyam M , Widoanindyawati V
Published: May 2019

One of the problems that arise in building land transport infrastructure located on soft soil is the making of the road construction. The completion of the road construction issue is carried out by the engineering that the road is safe and stable. The main long-term goal of this research is to provide a method of handling embankment construction that is above soft soil, complementing the existing methods, by using the main bamboo material. This study discussed the influence of bamboo pile clusters on a bamboo matrass construction system to support the embankment load on soft soil. The method of this research is to make a bamboo cluster containing 3 bamboo sticks, 4 bamboo sticks, and 7 bamboo sticks. The cluster is inserted into the soft soil. Bamboo pile clusters are gradually loaded until the soil collapses. Data that is investigated in the area of the cluster and the force given to suppress the cluster. The results of the study show the relationship of bamboo pile clusters with Pult. The value of the P

ult
depends on the area of the cluster with the formula: P

ult
= 840 L

n
(X) - 3044 with X = is the cluster area.
Reversible moisture damage in asphalt mixture
Authors: Arfat M , Yaacob H , Hassan N A , Warid M N M , Idham M K , Ismail C R , Nor H M , Hainin M R , Mohamed A , Mashros N , Yunus N Z M , Hassan S A , Jaya R P , Ayob M F
Published: May 2019

A moisture damage has been one of the major concerns for HMA pavement by loss of adhesion between bitumen and aggregate surface or loss of the cohesion within asphalt binder due to action of water. Water is the one of major contributor towards the damage of asphalt pavement. The aim of this research is to evaluate the effects of Moisture Damage (MD) towards the performance of asphalt mixture under different conditions (dry, wet and dry back). For this research laboratory fabricated specimens were conditioned in accordance to ASTM D4867 to achieve desire saturation level up to 80% and then immersed in water for different soaking period to simulate flooding scenario. Indirect Tensile strength (ITS) and Resilient Modulus (RM) tests were performed on moisture conditioned specimens at regular interval (1,3 and 5 days). After 5 days testing specimens were stored at room temperature for another 5 days to dry and were tested again to determine the recoverability of moisture damage. The results from this study indicated that tensile strength and modulus gradually decreased with the increasing of conditioning period, and upon drying at certain period specimens recovered 82% and 76% of initial ITS and RM respectively. The results suggested that moisture damage in asphalt mixture tested is reversible.
Improvement of CBR value in soil subgrade using garnet waste
Authors: Sani W. N. H. M. , Mohamed A. , Khalid N. H. A. , Nor H. M. , Hainin M. R. , Giwangkara G. G. , Hassan N. A. , Kamarudin N. A. S. , Mashros N.
Published: May 2019

This paper presents the findings on the improvement of California Bearing Ratio (CBR) value of soil subgrade using garnet waste. Soil subgrade are very important in construction of roadways and need more attention in strength. Many researchers found that soil subgrade in Malaysia need an improvement technique for the road constructions. One of the techniques is using garnet waste which is an industrial waste that is getting bulkier, and thus create opportunity to reduce and reuse the waste. The research aims to determine the properties of soil subgrade and garnet waste, to determine the CBR value of soil subgrade and to determine CBR value of soil subgrade mixed with garnet waste. Material properties testing for soil subgrade are sieve analysis and Atterberg limit; and garnet waste used sieve analysis and chemical composition. Compaction test in the mixed proportion are used to obtain the Optimum Moisture Content (OMC) and Maximum Dry Density (MDD) and CBR test was done using CBR-Marshall Tester. In this study, the result obtained from garnet waste have been used to observed their effect on CBR value of soil subgrade by varying the amount of garnet waste contain 20%, 40%, 60%, 80% and 100%. 100% garnet waste content showed the best result for the highest 43% CBR value. The CBR value of the soil showed judicious improvement after mixing with above 40% garnet waste in the soil subgrade. As a conclusion, the improvement of CBR value in soil subgrade using garnet waste is applicable.
Aberrant behaviour plausibility in road traffic violations, errors and lapses
Authors: Faiz R.U. , Mashros N. , Abbas H. Z. U. , Hassan S. A.
Published: May 2019

Road traffic crashes have been formidable concern for road safety engineer and different techniques have been applied to address such problems. Driving Behaviour is one of the pivotal issue that arises as in every country, state and region; though such issues play significant role in socio-economic development of country. The aim to conduct this study was to estimate driver traits and correlation between violation, errors, and lapses. Questionnaires are used to measure aberrant behaviour and its plausibility to be involved in road traffic crashes. A questionnaire was developed based on the Manchester Driving Behaviour Questionnaire to estimate the correlation. Data was collected from the capital city (Islamabad) of Pakistan. Statistical analysis was carried out to set up the correlation using the Pearson Correlation. It was estimated from the model results that violations are positively associated and correlated with lapses and errors. Lapses are positively associated and correlated to violations and errors. Errors are positively associated and correlated to lapses and violations.
Design concept of horse arena in Malaysia – A case study
Authors: Fadilah Darmansah Nur , Diana Tamjehi Sitti , Wafi Razali Abdul , Zaini Nadia , Syed Sahimi Sharifah Nur Farhana
Published: May 2019

One of the most important facilities required for any equine centre is horse arena. Horse arena is a place where horse doing the execrsice. Its a dedicated riding space is useful for training purposes. Equine Center may include an outdoor arena, indoor arena, or both. This paper presents the findings from a case study on the arena design concept throughout Malaysia. A total of fourtytwo (42) Equine Centre throughout the country were selected and visited in the study. The items studied include the types of arena, size of arena, material used for surface and fencing. The results indicated that about 79% of the arena used outdoor design, 31% of the arena had arena size of 20m x 60m, 56% used Polyvinyl Chloride (PVC) as the main material of fencing, and almost 74% used sand as types of surface in arena. Then for the indoor arena, the design concept of the roof structure was 79% used gable type of design with 81% used zinc as the roofing material. Generally, it can be said that the design concept of the horse arena in Malaysia depends on the owner needs, activities of the equine centre whether it is use for training or game.
Level-set modelling of Laser Beam Melting process applied onto ceramic materials – Comparison with experimental results
Authors: Chen Q. , Moniz Da Silva Sancho L. , Guillemot G. , Gandin Ch.-A. , Bellet M. , Bartout J.-D. , Berger M.-H. , Colin C.
Published: May 2019

Laser Beam Melting (LBM) processes benefit from significant progress in recent years. Currently, manufacturing of ceramic parts for applications at high temperature in aeronautical industries can be planned. However, understanding of defect formation is required in order to optimize manufacturing strategy. In this work, level-set modelling is proposed to simulate tracks development during LBM processes. Thermo-mechanical solution is performed in both powder and dense domains. Fluid flow is computed considering the surface tension and Marangoni forces. In addition mechanical resolution is achieved to investigate stress evolution in the rear part of the track. Applications are developed on alumina material. The influence of laser power, scanning velocity and physical properties are investigated and discussed. Validations of the heat source model are proposed by comparisons of melt pool dimensions and shapes with experimental measurements. A coherent evolution of the track morphology is shown when varying process parameters or material properties.
Thermo-mechanical simulation of track development in the Laser Beam Melting process - Effect of laser-metal interaction
Authors: Queva Alexis , Mayi Yaasin , Bellet Michel , Guillemot Gildas , Peyre Patrice , Dal Morgan , Moriconi Clara , Metton Charlotte
Published: May 2019

Interest has recently emerged for the manufacture of aeronautical parts by Laser Beam Melting (LBM) additive process. This energy efficient process can for instance be used to build complex geometries, which cannot be made with traditional processes. However, complex phenomena occur during powder melting and track development : vaporisation phenomena influence laser-matter interaction by creating metal vapours that are responsible for the reduction of absorbed energy. The recoil pressure generated by the vaporisation counteracts the surface tension between the melt pool and the inert gas, also inducing liquid instabilities. The study of laser-matter interaction and induced phenomena can help understand the origin of defects such as porosities or cracks. In this approach, a level-set modelling of the LBM process at a mesoscopic scale is proposed to follow melt pool evolution and track development during build. A volume heat source model is used for laser/powder interaction considering the material absorption coefficient. A surface heat source is used to take into account the high laser energy absorption by dense metal alloys. An energy solver is coupled with thermodynamic database and pre-determined solidification path. Shrinkage during consolidation from powder to liquid and compact medium is modelled by a compressible Newtonian constitutive law. An automatic remeshing adaptation is also used to save time and avoid high computational cost. In the future, the computation of multiple beads or the build of a wall in a context of lattice structures will have to be considered.
Solidification of niobium-silicide-based alloys during laser additive manufacturing process
Authors: Allen A. , Douglas A. C. , Feitosa L. M. , Qian H. , Li J. , Dong H. B. , Lin X. , Li Y.
Published: May 2019

Niobium silicide-based composites, in the application of gas turbine blades, promise significant efficiency improvements compared to current Ni-based alloys. The higher temperature capability would allow the engine to run at a higher temperature than that of current alloys, increasing engine efficiency. Nb-Si based composites possess a lower density, due to the presence of ceramic phases such as Nb5Si3 and/or Nb3Si. This would reduce the weight of the rotating blades. However, improvements in certain properties, such as room temperature toughness and oxidation resistance are needed.

This study focuses on the manufacturability aspect of the powder feeding laser additive manufacturing (LAM) process to engineering Nb-Si based alloy samples. LAM has the advantage of forming near-net shapes without the use of expensive cores and moulds for the reactive Nb-Si melt. Fine microstructure and even chemical composition distribution with reduced macro-segregation are obtained. With the use of power feeding system, new Nb-Si based alloys are LAMed with varying atomic composition. Microstructures of the LAMed alloys will be presented, and the relationship between the microstructure and the alloy chemistry will be reported.
Solidification cracking during welding of steel: In situ X-ray observation
Authors: Aucott L. , Li J. , Rack A. , Dong H. B.
Published: May 2019

Solidification cracking is an important issue during welding, casting and some of the additive manufacturing process. In order to illuminate the failure mechanisms, solidification cracking during arc welding of steel are investigated in situ with high-speed, high energy, synchrotron X-ray radiography approach. Analysis of the in situ radiography sequence revealed the solidification cracking initiates in the weld sub-surface trailing the welding electrode at relatively low true strain of about 3.1% in the form of micro-cavities. Although both material type and bending speed influence solidification cracking, cracks propagate from the core of the weld towards the free surface along the solidifying grain boundaries was found at a speed of between 1.7 - 2.6 × 10−3 m s−1 for three different steels. In addition, a three-stage mechanistic model for solidification cracking during welding of steel is proposed.
A 3D discrete-element model for simulating liquid feeding during dendritic solidification of steel
Authors: Feng Yi , Založnik Miha , Thomas Brian , Phillion André
Published: May 2019

A 3D meso-scale discrete-element model has been developed to simulate fluid flow during dendritic solidification of steel. The model domain is a representative volume element consisting of a set of equiaxed dendritic grain envelopes along with extra-dendritic liquid channels, where the final grain shape is given by a Voronoi tessellation. Solidification of each grain is simulated via a volume average approach. The output of the solidification simulation at a given solid fraction is used as the input mesh for the fluid flow simulation. A single domain Darcy-Brinkman model is used to calculate the pressure field within the liquid channels, with Poiseuille flow assumed to occur in the extra-dendritic region, and Darcy flow assumed to occur within the dendrite envelope. Mass conservation over each element is then used to derive a flow equation that is solved via the finite element method. The results of this new model are first compared with a previously-developed granular model [1] where fluid flow only occurs between the grains, and then compared with different forms of the Carman-Kozeny equation. It is shown that the intra-dendritic liquid fluid flow plays a major role in the semi-solid pressure field, and thus needs to be included when investigating hot tearing susceptibility in engineering alloys undergoing dendritic solidification.
Effect of the Coriolis force on the macrosegregation of aluminum in the centrifugal casting of Ti-Al alloys
Authors: Cisternas Fernández M. , Založnik M. , Combeau H. , Huang C. , Zollinger J. , Hecht U.
Published: May 2019

Within the framework of the ESA GRADECET project, experiments of directional solidification of cylindrical Ti-Al samples were conducted in hypergravity. The experiments were performed in a centrifuge with the apparent gravity (sum of centrifugal and terrestrial gravity) aligned along the cylinder centerline. 3D numerical simulations of aluminum macrosegregation in these samples are presented. A volume-averaging solidification model is used that accounts for centrifugal and Coriolis accelerations in a non-inertial rotating reference system. We compare the melt flow pattern and the macrosegregation formation under terrestrial gravity and under

20

g
→

centrifugation. The results show that the Coriolis acceleration, although very weak, breaks the symmetry of the thermosolutal convection, having an important impact on the final macrosegregation pattern. The macrosegregation is entirely modified in comparison with a sample solidified under terrestrial gravity conditions. Besides the aluminum segregation intensity increases with the centrifugation level.
Prediction of solidification structures in a 9.8 t steel ingot
Authors: Gerin Benjamin , Combeau Hervé , Založnik Miha , Poitrault Isabelle , Cherif Maya
Published: May 2019

The control of the carbon macrosegregation level in steel ingots is important for the structural integrity of the final component. During solidification, the fragmentation of the columnar dendrites is an important source of equiaxed grains, and has a large influence on the macrosegregation and the grain structure. The goal of this study is to show that a numerical model that takes into account fragmentation can describe the formation of the structures and the macrosegregation during solidification of a large steel ingot. The present article describes the multiphase numerical model used in the simulations. The simulation results are compared to experimental data from a 9.8 t ingot cast in A5/6 steel by ArcelorMittal Industeel. The model can then be used to explain the formation of the observed structures. For example, we show that the structural transitions, first from columnar to equiaxed globular and then to equiaxed dendritic at the bottom of the ingot are a consequence of the concurrent transport and growth of the dendrite fragments from the columnar zone. Furthermore, we show that most of the structures are formed very early on during solidification, whereas macrosegregation develops much more gradually.
Optimization of ultrasonic cavitation processing in the liquid melt flow
Authors: Subroto T , Eskin D G , Tzanakis I , Lebon G S B. , Miranda A , Pericleous K.
Published: May 2019

Ultrasonic processing (USP) during direct-chill (DC) casting of light metal alloys is typically applied in the sump of a billet. This approach, though successful for structure refinement and modification, has two main drawbacks: (a) mixture of mechanisms that rely heavily on dendrite fragmentation and (b) a limited volume that can be processed by a single ultrasonic source. We suggest moving the location of USP from the sump to the launder and applying it to the melt flow for continuous treatment. The apparent benefits include: (a) degassing of the melt volume, (b) grain refinement through activation of non-metallic inclusions, fragmentation of primary crystals, and deagglomeration of grain refining substrates, and (c) a possibility to use a single ultrasonic source for processing large melt volumes. To optimize this process with regard to the acoustic intensity and melt residence time in the active cavitation zone, flow modification with baffles as well as informed location of the ultrasonic source are required. In this paper, we demonstrate the results of experimental trials where the degassing degree and grain refinement have been the indicators of the USP efficiency for two aluminium alloys, i.e. LM25 and AA7050. The results are supported by acoustic measurements and computer simulations.
Characterization of heat transfer and its effect on solidification in water cooled LPDC of wheels
Authors: Saadah AU , Reilly C , Maijer DM , Cockcroft SL
Published: May 2019

Computational process modelling has become an important engineering tool in the casting industry to predict the solidification sequence in complex castings. Used properly, this tool can help reduce manufacturing costs. One of the challenging issues in developing casting simulations of the low pressure die casting (LPDC) process for automotive wheels is to quantify the heat transfer coefficients (HTC) within the cooling channels in a die. When water is used as the cooling media, the HTCs exhibit a complex, non-linear behaviour due to the boiling phenomena that occur making it possible to extract a significant amount of heat from the die in a short period of time and influence the solidification of a wheel. Primarily, constant heat transfer coefficients have been used to describe this heat transfer in casting models up until now, but an opportunity exists to improve the transient description of heat transfer in channels cooled with water. In this paper, HTC’s in a lab-scale physical analogue model of die cooling will be characterized as a function of initial die temperatures.
Interfaces at internal chills in solidifying steel sections
Authors: Monroe Charles , Foley Robin , Griffin John , Gibbons Sean , Saville Alec
Published: May 2019

Chills are used in the production of metal castings as a thermal aid to promote directional solidification in casted sections. This study will review microstructure and thermal circumstances of the internal chill interface where the chill is intended to be incorporated into the structure of the cast section. The conditions for interface coherency of cast steel sections from 25 to 50mm will be shown. Solidification proceeds away from the interface chill growing to a maximum thickness and then melting back to the original chill geometry. Furthermore, it is shown that promoting section solidification prior to the complete melting of the internal chill can lead to the formation of interfaces will be coherent across the chill and cast sections for compatible steel alloys. A computer model of the heat transfer and interface evolution show the possibility of using the coherent interface of internal chills in the design of other cast components.
Effect of cooling rate on the porosity defect in the thick aluminum casting by 3D computed tomography analysis
Authors: Cho I S , Kwak S Y , Kim Y H , Lee H K , Yoo S M
Published: May 2019

In the present study, effect of cooling rate on the formation of the porosity in the thick aluminum sand casting was investigated. Nowadays large scale thick aluminum casting replaces steel frame for vacuum chamber for semiconductor production, with the consideration of weight and cost reduction. Several thick aluminum castings were manufactured using chill with temperature measurements. The castings were inspected by using 3D computed tomography in order to quantify the porosity defect density in the castings. Effect of the thickness of the chill on the porosity defect density were discussed.
A Novel Powder Metallurgy Technique for Introducing Synthetic Inclusions into Liquid Steel
Authors: Smith A , Tran T , Ji F , Tiekink W , Abbel G , Verdier S
Published: May 2019

Previous studies have shown that it is extremely problematic to add synthetic inclusions successfully into liquid steel for clean steel experiments. Small micro-particles encapsulated in a metallic parcel are difficult to pass through the melt-gas interface and inclusions tend to agglomerate then float up to the liquid surface. In this study, powder metallurgy is used to distribute cerium oxide particles of a known size from 1µm to 14µm within a small-scale steel ingot. Carbonyl iron powder has been mixed with 0.1 wt.% cerium oxide (CeO2) then sintered in an electrical furnace to produce sintered ingots of 500 grams. A series of induction furnace melting trials using a total of 400 grams of electrolytic iron and cerium oxide sintered ingot have been undertaken. The work has included extensive FE-SEM analysis using the INCA Feature® to characterise synthetic cerium oxide inclusions from both the sintered ingots and trial ingots. The INCA Feature® results showed that the size distribution and number of cerium oxide inclusions agreed well between the sintered ingot and trial ingot. The synthetic cerium oxide inclusions are homogeneously dispersed through the bottom, centre and top of the trial ingot with approximately 16 number counts/mm2. Analysis suggests that more than 95% of the cerium oxide from the sintered ingot has been distributed throughout the trial ingot. The work has also been upscaled from 400 grams up to 1.5 kg and has been successful. The method developed will be useful for further studies into steel cleanness of high value alloyed steels.
Study of elasto-plastic deformation in a cast AlCu7 alloy
Authors: Schöbel M , Fernández R , Degischer HP
Published: May 2019

The need for efficient and clean solutions, due to the increasing current environmental regulations puts extra pressure on new combustion engine development, to compete in a market with alternative driving concepts. Downsizing and weight reduction can reduce the engine emission and efficiency, but require light alloys with superior thermo-mechanical properties for high temperature exposure to maintain the same engine performance. Cast Al-Cu could be alternative to standard Al-Si alloys for new engine generations due to their higher temperature strength, creep-resistance and long term stability of engine components. In Al-Si and Al-Cu cast alloys with heterogeneous microstructures a composite-like deformation behavior is responsible for superior high temperature properties. Stiff Si or Al2Cu particles, respectively reinforce a ductile α-Al matrix to a composite with improved thermo-mechanical strength. However, different Young’s moduli and coefficients of thermal expansion are responsible for micro stress gradients and unpredictable micro crack formation under operation. These micro-mechanical deformation mechanisms in Al-Si and Al-Cu systems, responsible for crack initiation and growth, have been scarcely investigated so far.

This manuscript describes an example of elasto-plastic deformation mechanisms in an AlCu7 alloy. Tensile testing shows anomalous macroscopic deformation behavior indicating unknown internal micro-mechanical processes. External loading until yield strength and beyond are applied under laboratory conditions and during in-situ neutron diffraction. The results of macroscopic deformation and micro strain evolution are compared and correlated with the heterogeneous micro structure. High resolution synchrotron computed tomography reveals conclusions on the micro-mechanic deformation mechanisms and their effects on the macroscopic damage initiation and material’s service performance.
On the use of heterogeneous thermomechanical and thermophysical material properties in finite element analyses of cast components
Authors: Jansson Johan , Olofsson Jakob , Salomonsson Kent
Published: May 2019

Cast components generally show a heterogeneous distribution of material properties, caused by variations in the microstructure that forms during solidification. Variations caused by the casting process are not commonly considered in structural analyses, which might result in manufacturing of sub-optimised components with unexpected in-use behaviour. In this paper, we present a methodology which can be used to consider both thermomechanical and thermophysical variations using finite element analyses in cast components. The methodology is based on process simulations including microstructure modelling and correlations between microstructural features and material properties. Local material data are generated from the process simulation results, which are integrated into subsequent structural analyses. In order to demonstrate the methodology, it is applied to a cast iron cylinder head. The heterogeneous distribution of material properties in this component is investigated using experimental methods, demonstrating local variations in both mechanical and physical behaviour. In addition, the strength-differential effect on tensile and compressive behaviour of cast iron is considered in the modelling. The integrated simulation methodology presented in this work is relevant to both design engineers, production engineers as well as material scientists, in order to study and better understand how local variations in microstructure might influence the performance and behaviour of cast components under in-use conditions.
An investigation of the chill-casting interface dynamics in production of sand-cast A319 engine blocks
Authors: Farhang Mehr Farzaneh , Cockcroft Steve , Maijer Daan
Published: May 2019

In recent years, the automotive industry has been increasing the production of small, high-power gas engines as part of several strategies to achieve the new “Corporate Average Fuel Economy” (CAFE) standards. This trend requires an improvement in the thermal and mechanical fatigue durability of the aluminium alloys used in the production of the cylinder blocks in these engines. Conventionally, solid chills are employed in areas of these castings subject to high cyclic loading to enhance the mechanical performance of the cast material – i.e. in the main bearing bulkhead. A potential means of improving the efficacy of these chills is to incorporate water cooling. To assess the effectiveness of this method, a water-cooled chill was designed and installed in a bonded-sand engine block mould package (1/4 section). The moulds were instrumented with thermocouples, to measure the evolution of temperature at key locations in the casting, and “Linear Variable Displacement Transducers” (LVDTs), to measure the gap formation at the interface between the chill and the casting. This paper summarizes, at a high level, some of the findings of this work.
Nanofiber scaffolds attenuate collagen synthesis of human dermal fibroblasts through TGF-β1/TSG-6 pathway*
Authors: Xie Bei , Zhu Wanzong , Ding Pinghui , Chen Mengting , Li Ji , Lei Lei , Zhang Can , Nie Hemin
Published: May 2019

Nanofiber scaffolds are promising patches for skin tissue regeneration as they provide favorable environment for the adhesion, infiltration and proliferation of skin dermal fibroblasts. However, the effects of nanofiber scaffolds on scar formation remain to be elucidated. The aim of this study was to find out the relationship between nanofiber scaffolds and scar formation, along with the underlying mechanism. We found that polycaprolactone (PCL)/gelatin nanofiber scaffolds attenuated the mRNA expression of fibrosis-associated genes in fibroblasts, including collagen I (collagen type I alpha 1), collagen III (collagen type III alpha 1) and fibronectin. Specifically thicker scaffolds displayed stronger fibrosis inhibitory effect than thin scaffolds. The mechanism relied on TGF-β1/TSG-6 pathway, and overexpression of TSG-6 impaired the anti-fibrosis effect of nanofiber scaffolds, which decreased TGF-β1 expression with thickness-dependency. Moreover, in vivo study demonstrated that nanofiber scaffolds remarkably accelerated the wound healing process by reducing the ratios of collagen I/collagen III and TGF-β1, eventually decreased the deposition of collagens. Taken together, our results suggested that the attenuation of fibrosis by PCL/gelatin nanofiber scaffolds was TGF-β1-dependent and through TGF-β1/TSG-6 pathway. Nanofiber scaffold of appropriate thickness would accelerate skin wound healing, stimulate re-epithelialization and form cutaneous skin appendages in skin trauma. Thus, PCL/gelatin nanofiber scaffolds could be adopted for scar-free skin wound healing and skin cosmetics applications.
Discrete resonance problems subject to periodic forcing
Authors: Robinson Stephen , Schmitt Klaus
Published: May 2019

In this paper, we consider the following discrete nonlinear problem which is subject to a periodic nonlinear forcing term:

A
u
=
λ
u
+
p
(
u
)
+
h
,

\begin{equation*} A u = \lambda u +p(u) + h, \end{equation*}

where

A
A

is an

n
×
n

n\times n

matrix with real components,

p
:

R

n

→

R

n

p: \mathbb {R}^n\to \mathbb {R}^n

is a periodic forcing term, and

⟨
h
,

ϕ
¯

⟩
=
0

\langle h,\overline {\phi } \rangle =0

, where

ϕ
¯

\overline {\phi }

is an eigenvector of

A
T

,

A^T,

the transpose of

A
A

, corresponding to a simple real eigenvalue

λ
\lambda

. Conditions on these terms will be provided such that this problem will have infinitely many distinct solutions. The results here are motivated by some recent results for discrete systems and by results obtained for analogous boundary value problems for semilinear elliptic problems at resonance.
Positively curved Killing foliations via deformations
Authors: Caramello Francisco , Töben Dirk
Published: May 2019

We show that a compact manifold that admits a Killing foliation with positive transverse curvature fibers over finite quotients of spheres or weighted complex projective spaces provided that the singular foliation defined by the closures of the leaves has maximal dimension. This result is obtained by deforming the foliation into a closed one while maintaining transverse geometric properties, which allows us to apply results from the Riemannian geometry of orbifolds to the space of leaves. We also show that the basic Euler characteristic is preserved by such deformations. Using this fact, we prove that a Riemannian foliation of a compact manifold with finite fundamental group and nonvanishing Euler characteristic is closed. As another application, we obtain that, for a positively curved Killing foliation of a compact manifold, if the structural algebra has sufficiently large dimension, then the basic Euler characteristic is positive.
Tau tubulin kinase is required for spermatogenesis and development of motile cilia in planarian flatworms
Authors: Magley Robert Alan , Rouhana Labib
Published: May 2019

Cilia are microtubule-based structures that protrude from the apical surface of cells to mediate motility, transport, intracellular signaling, and environmental sensing. Tau tubulin kinases (TTBKs) destabilize microtubules by phosphorylating microtubule-associated proteins (MAPs) of the MAP2/Tau family, but also contribute to the assembly of primary cilia during embryogenesis. Expression of TTBKs is enriched in testicular tissue, but their relevance to reproductive processes is unknown. We identified six TTBK homologues in the genome of the planarian Schmidtea mediterranea ( Smed-TTBK-a, -b, -c, -d, -e, and -f), all of which are preferentially expressed in testes. Inhibition of TTBK paralogues by RNA interference (RNAi) revealed a specific requirement for Smed-TTBK-d in postmeiotic regulation of spermatogenesis. Disrupting expression of Smed-TTBK-d results in loss of spermatozoa, but not spermatids. In the soma, Smed-TTBK-d RNAi impaired the function of multiciliated epidermal cells in propelling planarian movement, as well as the osmoregulatory function of protonephridia. Decreased density and structural defects of motile cilia were observed in the epidermis of Smed-TTBK-d(RNAi) by phase contrast, immunofluorescence, and transmission electron microscopy. Altogether, these results demonstrate that members of the TTBK family of proteins are postmeiotic regulators of sperm development and also contribute to the formation of motile cilia in the soma.
Ancient complement and lineage-specific evolution of the Sec7 ARF GEF proteins in eukaryotes
Authors: Pipaliya Shweta V. , Schlacht Alexander , Klinger Christen M. , Kahn Richard A. , Dacks Joel
Published: May 2019

Guanine nucleotide exchange factors (GEFs) are the initiators of signaling by every regulatory GTPase, which in turn act to regulate a wide array of essential cellular processes. To date, each family of GTPases is activated by distinct families of GEFs. Bidirectional membrane trafficking is regulated by ADP-ribosylation factor (ARF) GTPases and the development throughout eukaryotic evolution of increasingly complex systems of such traffic required the acquisition of a functionally diverse cohort of ARF GEFs to control it. We performed phylogenetic analyses of ARF GEFs in eukaryotes, defined by the presence of the Sec7 domain, and found three subfamilies (BIG, GBF1, and cytohesins) to have been present in the ancestor of all eukaryotes. The four other subfamilies (EFA6/PSD, IQSEC7/BRAG, FBX8, and TBS) are opisthokont, holozoan, metazoan, and alveolate/haptophyte specific, respectively, and each is derived from cytohesins. We also identified a cytohesin-derived subfamily, termed ankyrin repeat-containing cytohesin, that independently evolved in amoebozoans and members of the SAR and haptophyte clades. Building on evolutionary data for the ARF family GTPases and their GTPase-­activating proteins allowed the generation of hypotheses about ARF GEF protein function(s) as well as a better understanding of the origins and evolution of cellular complexity in eukaryotes.
Absolute requirement for polyamines for growth of Escherichia coli mutants (mnmE/G) defective in modification of the wobble anticodon of transfer-RNA
Authors: Keller Christopher , Chattopadhyay Manas , Tabor Herbert
Published: May 2019

The genes mnmE and mnmG are responsible for the modification of uridine 34, ‘the wobble position’ of many aminoacyl-tRNAs. Deletion of these genes affects the strength of the codon-anticodon interactions of the aminoacyl-tRNAs with the mRNAs and the ribosomes. However, deletion of these genes does not usually have a significant effect on the growth rate of the standard Escherichia coli strains. In contrast, we have found that if the host E. coli strain is deficient in the synthesis of polyamines, deletion of the mnmE or mnmG gene results in complete inhibition of growth unless the medium contains polyamines. The finding of an absolute requirement for polyamines in our current work will be significant in studies on polyamine function, in studies on the function of the mnmE/G genes, and in studies on the role of aminoacyl-tRNAs in protein biosynthesis.
Leaf anatomical adaptations have central roles in photosynthetic acclimation to humidity
Authors: Du Qingjie , Liu Tao , Jiao Xiaocong , Song Xiaoming , Zhang Jiayu , Li Jianming
Published: May 2019

Examination of long-term photosynthetic acclimation of two tomato cultivars (Jinpeng and Zhongza) to leaf-to-air vapour pressure difference reveals that independent changes in epidermal and mesophyll cell size maintain photosynthetic homeostasis in Jinpeng.
Reduced stomatal density in bread wheat leads to increased water-use efficiency
Authors: Dunn Jessica , Hunt Lee , Afsharinafar Mana , Meselmani Moaed Al , Mitchell Alice , Howells Rhian , Wallington Emma , Fleming Andrew J , Gray Julie E
Published: May 2019

Crops that require less water but produce the same yield would aid agriculture. We show that engineering lower stomatal density in wheat leaves can improve water-use efficiency, yet maintain yield.
Dissecting the genome-wide genetic variants of milling and appearance quality traits in rice
Authors: Misra Gopal , Anacleto Roslen , Badoni Saurabh , Butardo Vito , Molina Lilia , Graner Andreas , Demont Matty , Morell Matthew K , Sreenivasulu Nese
Published: May 2019

Genetic regions in the rice genome are identified that affect the proportion of grains that remain intact after milling (the head rice yield) and the degree of chalkiness in the grain.
The quest for osmosensors in plants
Authors: Nongpiur Ramsong Chantre , Singla-Pareek Sneh Lata , Pareek Ashwani
Published: May 2019

Osmotic stress has severe effects on crop productivity. Since climate change is predicted to exacerbate this problem, the development of new crops that are tolerant to osmotic stresses, especially drought and salinity stress, is required. However, only limited success has been achieved to date, primarily because of the lack of a clear understanding of the mechanisms that facilitate osmosensing. Here, we discuss the potential mechanisms of osmosensing in plants. We highlight the roles of proteins such as receptor-like kinases, which sense stress-induced cell wall damage, mechanosensitive calcium channels, which initiate a calcium-induced stress response, and phospholipase C, a membrane-bound enzyme that is integral to osmotic stress perception. We also discuss the roles of aquaporins and membrane-bound histidine kinases, which could potentially detect changes in extracellular osmolarity in plants, as they do in prokaryotes and lower eukaryotes. These putative osmosensors have the potential to serve as master regulators of the osmotic stress response in plants and could prove to be useful targets for the selection of osmotic stress-tolerant crops.
Evolution and functional differentiation of recently diverged phytochelatin synthase genes from Arundo donax L.
Authors: Li Mingai , Stragliati Luca , Bellini Erika , Ricci Ada , Saba Alessandro , Sanità di Toppi Luigi , Varotto Claudio
Published: May 2019

Plant phytochelatin synthases undergo evolutionarily rapid functional differentiation after duplication, allowing fast and precise adjustment of metal detoxification capacity by modulation of both transcription and enzymatic activity.
Improving the Work Environment, Step by Step
Authors: Kennedy Maureen Shawn
Published: May 2019

Greater awareness of the issues will hopefully lead to more change.
U.S. Women's Health Falls Behind That of Other High-Income Countries
Authors: Zolot Joan
Published: May 2019

Breast cancer care and access to specialists are bright spots.
Study of Reported Sexual Misconduct by Nurses Finds Gaps in Disciplinary Action
Authors: Kritz Fran
Published: May 2019

Resources for nurses and managers are available via the NCSBN.
The Number of Uninsured Americans Is on the Rise Again
Authors: Sofer Dalia
Published: May 2019

Most affected are women, young adults, and those with low incomes.
America's Problem with Opioid Abuse Takes Its Toll on Nursing, Too
Authors: Sofer Dalia
Published: May 2019

Clinicians contend with a crisis of addiction as solutions remain elusive.
Sustaining Nursing Grand Rounds Through Interdisciplinary Teamwork and Interorganizational Partnership
Authors: Salinas Dagoberto , Johnson Stephen Christopher , Conrardy Julie Anne , Adams Tuesday Lynn , Brown James Denning
Published: May 2019

In 2017, Navy Nurse Corps executives launched a new nursing professional practice model that promotes operational readiness, professional development, and transformational leadership. This directive prompted nursing leadership at Naval Hospital Jacksonville (NH JAX) to conduct a needs assessment survey to determine what kind of educational initiative nursing staff members would most welcome in support of the goals of the new practice model. Survey respondents favored case studies presented in a nursing grand rounds format. Our change implementation team designed and executed the grand rounds program, offering lunchtime presentations every other month. Topics included a wide range of “high-risk/low-volume” procedures—those infrequently performed at participants’ clinical sites. Ten months after the initiation of grand rounds, surveys were distributed to NH JAX participants to assess their perceptions of the value of the sessions in terms of professional development, interdisciplinary teamwork, and strengthened institutional partnerships.

Of the 161 nursing grand rounds participants, 41 (25%) responded to the postimplementation survey. Responses indicated that participants valued nursing grand rounds in enhancing clinical knowledge (83% agreed), discussing research and evidence-based practices (71% agreed), supporting professional development (88% agreed), improving interdisciplinary teamwork (83% agreed), and solidifying interorganizational partnerships (73% agreed). This article presents the implementation of the NH JAX grand rounds program and demonstrates how nursing grand rounds can serve as an excellent forum in which to develop knowledge, showcase research and evidence-based practices, support professional growth, improve collaboration, and strengthen partnerships.
Radical Prostatectomy has Substantial Benefit for Otherwise Healthy Men
Authors: Rosenberg Karen
Published: May 2019

According to this study:

For otherwise healthy men with clinically detected, localized prostate cancer, radical prostatectomy reduces mortality and the risk of metastasis compared with watchful waiting.
Data-driven mathematical model of East-Asian facial attractiveness: the relative contributions of shape and reflectance to attractiveness judgements
Authors: Nakamura Koyo , Watanabe Katsumi
Published: May 2019

Facial attractiveness is judged through a combination of multiple cues including morphology (facial shape) and skin properties (facial reflectance). While several studies have examined the way in which people in Western cultures judge facial attractiveness, there have been fewer investigations into non-Western attitudes. This is because stimuli that quantitatively vary the attractiveness of non-Western faces are rare. In the present study, we built a model of the attractiveness of East-Asian faces, judged by East-Asian observers. Therefore, 400 computer-generated East-Asian faces were created and attractiveness rating scores were collected from Japanese observers. Data-driven mathematical calculations were used to identify quantitative links between facial attractiveness and shape and reflectance properties, with no prior hypothesis. Results indicate that faces with larger eyes, smaller noses and brighter skin are judged as more attractive, regardless of the sex of the faces, possibly reflecting a general preference for femininity. Shape is shown to be a strong determinant of attractiveness for both male and female faces, while reflectance properties are less important in judging male facial attractiveness. Our model provides a tool to effectively produce East-Asian face stimuli that quantitatively varies attractiveness and can be used to elucidate visual processes related to attractiveness judgements.
Postbuckling analyses of frame mesostructures consisting of straight ribbons for mechanically guided three-dimensional assembly
Authors: Liu Yuan , Xu Zheng , Hwang Keh-Chi , Huang Yonggang , Zhang Yihui
Published: May 2019

Mechanically guided assembly through buckling-induced two-dimensional (2D)-to- three-dimensional (3D) transformation represents a versatile approach to the formation of 3D mesostructures, thanks to the demonstrated applicability to a wide range of length scales (from tens of nanometres to centimetres) and material types (from semiconductors, metals to polymers and ceramics). In many demonstrated examples of device applications, the 2D precursor structures are composed of ribbon-type components, and some of them exhibit frame geometries consisting of multiple straight ribbons. The coupling of bending/twisting deformations among various ribbon components of the frame mesostructures makes the analyses more complicated than the case with a single component, which requires the development of a relevant theory to serve as the basis of design optimization in practical applications. Here, an analytic model of compressive buckling in such frame mesostructures is presented in the framework of energetic approach, taking into account the contributions of spatial bending deformations and twisting deformations. Three different frame geometries are studied, including ‘+’, ‘T' and ‘H' shaped designs. As validated by the experiments and finite-element analyses (FEA), the developed model can predict accurately the assembled 3D configurations during the postbuckling of different precursor shapes. Furthermore, the theoretical analyses provide approximate analytic solutions to some key physical quantities (e.g. the maximum out-of-plane displacements and maximum strains), which can be used as design references in practical applications.
Population spatial synchrony enhanced by periodicity and low detuning with environmental forcing
Authors: Haynes Kyle J. , Walter Jonathan A. , Liebhold Andrew M.
Published: May 2019

Explaining why fluctuations in abundances of spatially disjunct populations often are correlated through time is a major goal of population ecologists. We address two hypotheses receiving little to no testing in wild populations: (i) that population cycling facilitates synchronization given weak coupling among populations, and (ii) that the ability of periodic external forces to synchronize oscillating populations is a function of the mismatch in timescales (detuning) between the force and the population. Here, we apply new analytical methods to field survey data on gypsy moth outbreaks. We report that at timescales associated with gypsy moth outbreaks, spatial synchrony increased with population periodicity via phase locking. The extent to which synchrony in temperature and precipitation influenced population synchrony was associated with the degree of mismatch in dominant timescales of oscillation. Our study provides new empirical methods and rare empirical evidence that population cycling and low detuning can promote population spatial synchrony.