bluuebunny/crossref_metadata_2025 huggingface dataset:
Strain development during the phase transition of La(Fe,Mn,Si)13Hz
Authors: Neves Bez Henrique , Nielsen Kaspar K. , Smith Anders , Norby Poul , Ståhl Kenny , Bahl Christian R. H.
Published: August 2016

We use powder X-ray diffraction to evaluate the temperature dependence of the crystalline properties during the magnetic phase transition of La(Fe,Mn,Si)13Hz as a function of the Fe/Mn/Si ratio. Both the paramagnetic and ferromagnetic phases were observed as peak overlaps in the patterns around the Curie temperature (TC) occurring continuously in a temperature range of about 5 K around TC. Using the Williamson-Hall method, we evaluate the strain developing in the crystallites during the transition and find that it is associated with the growth of the paramagnetic phase as the transition occurs. Based on our measurements and microstructure analyses, we propose that cracking during the phase transition is due to or aggravated by the small content of a La-rich phase.
Electrostatic ion acceleration across a diverging magnetic field
Authors: Ichihara D. , Uchigashima A. , Iwakawa A. , Sasoh A.
Published: August 2016

Electrostatic ion acceleration across a diverging magnetic field, which is generated by a solenoid coil, permanent magnets, and a yoke between an upstream ring anode and a downstream off-axis hollow cathode, is investigated. The cathode is set in an almost magnetic-field-free region surrounded by a cusp. Inside the ring anode, an insulating wall is set to form an annular slit through which the working gas is injected along the anode inner surface, so the ionization of the working gas is enhanced there. By supplying 1.0 Aeq of argon as working gas with a discharge voltage of 225 V, the ion beam energy reached about 60% of a discharge voltage. In spite of this unique combination of electrodes and magnetic field, a large electrical potential drop is formed almost in the axial direction, located slightly upstream of the magnetic-field-free region. The ion beam current almost equals the equivalent working gas flow rate. These ion acceleration characteristics are useful for electric propulsion in space.
A case of homing after translocation of chuditch, Dasyurus geoffroii (Marsupialia : Dasyuridae)
Authors: Cannella Edward G. , Henry Jan
Published: August 2016

Fauna translocations are often used for conservation purposes. This has been especially prevalent in the translocation of threatened species in south-west Western Australia. Translocations can fail for several reasons such as stress, disease and predation and, less frequently, homing behaviours of translocated individuals. We report on one of eight chuditch, Dasyurus geoffroii, that was recaptured near the original point of capture 12 days after release at the designated translocation site in George State Forest Block, 14 km to the south. During that period she had lost 12.5% of her body weight, but was otherwise in good condition. It is possible that this event was unique to this individual and the other seven chuditch remained within the translocation site of George Block. However, this species is known to travel long distances and have large home ranges. It is important to determine the propensity of this species to attempt homing after translocation in an effort to determine whether a minimum release distance is necessary.
Truncation of grain filling in wheat (Triticum aestivum) triggered by brief heat stress during early grain filling: association with senescence responses and reductions in stem reserves
Authors: Shirdelmoghanloo Hamid , Cozzolino Daniel , Lohraseb Iman , Collins Nicholas C.
Published: August 2016

Short heat waves during grain filling can reduce grain size and consequently yield in wheat (Triticum aestivum L.). Grain weight responses to heat represent the net outcome of reduced photosynthesis, increased mobilisation of stem reserves (water-soluble carbohydrates, WSC) and accelerated senescence in the grain. To compare their relative roles in grain weight responses under heat, these characteristics were monitored in nine wheat genotypes subjected to a brief heat stress at early grain filling (37°C maximum for 3 days at 10 days after anthesis). Compared with the five tolerant varieties, the four susceptible varieties showed greater heat-triggered reductions in final grain weight, grain filling duration, flag leaf chla and chlb content, stem WSC and PSII functionality (Fv/Fm). Despite the potential for reductions in sugar supply to the developing grains, there was little effect of heat on grain filling rate, suggesting that grain size effects of heat may have instead been driven by premature senescence in the grain. Extreme senescence responses potentially masked stem WSC contributions to grain weight stability. Based on these findings, limiting heat-triggered senescence in the grain may provide an appropriate focus for improving heat tolerance in wheat.
Protection by light against heat stress in leaves of tropical crassulacean acid metabolism plants containing high acid levels
Authors: Krause G. Heinrich , Winter Klaus , Krause Barbara , Virgo Aurelio
Published: August 2016

Heat tolerance of plants exhibiting crassulacean acid metabolism (CAM) was determined by exposing leaf sections to a range of temperatures both in the dark and the light, followed by measuring chlorophyll a fluorescence (Fv/Fm and F0) and assessing visible tissue damage. Three CAM species, Clusia rosea Jacq., Clusia pratensis Seem. and Agave angustifolia Haw., were studied. In acidified tissues sampled at the end of the night and exposed to elevated temperatures in the dark, the temperature that caused a 50% decline of Fv/Fm (T50), was remarkably low (40−43°C in leaves of C. rosea). Conversion of chlorophyll to pheophytin indicated irreversible tissue damage caused by malic acid released from the vacuoles. By contrast, when acidified leaves were illuminated during heat treatments, T50 was up to 50−51°C. In de-acidified samples taken at the end of the light period, T50 reached ∼54°C, irrespective of whether temperature treatments were done in the dark or light. Acclimation of A. angustifolia to elevated daytime temperatures resulted in a rise of T50 from ∼54° to ∼57°C. In the field, high tissue temperatures always occur during sun exposure. Measurements of the heat tolerance of CAM plants that use heat treatments of acidified tissue in the dark do not provide relevant information on heat tolerance in an ecological context. However, in the physiological context, such studies may provide important clues on vacuolar properties during the CAM cycle (i.e. on the temperature relationships of malic acid storage and malic acid release).
BLOC-1 and BLOC-3 regulate VAMP7 cycling to and from melanosomes via distinct tubular transport carriers
Authors: Dennis Megan K. , Delevoye Cédric , Acosta-Ruiz Amanda , Hurbain Ilse , Romao Maryse , Hesketh Geoffrey G. , Goff Philip S. , Sviderskaya Elena V. , Bennett Dorothy C. , Luzio J. Paul , Galli Thierry , Owen David J. , Raposo Graça , Marks Michael S.
Published: August 2016

Endomembrane organelle maturation requires cargo delivery via fusion with membrane transport intermediates and recycling of fusion factors to their sites of origin. Melanosomes and other lysosome-related organelles obtain cargoes from early endosomes, but the fusion machinery involved and its recycling pathway are unknown. Here, we show that the v-SNARE VAMP7 mediates fusion of melanosomes with tubular transport carriers that also carry the cargo protein TYRP1 and that require BLOC-1 for their formation. Using live-cell imaging, we identify a pathway for VAMP7 recycling from melanosomes that employs distinct tubular carriers. The recycling carriers also harbor the VAMP7-binding scaffold protein VARP and the tissue-restricted Rab GTPase RAB38. Recycling carrier formation is dependent on the RAB38 exchange factor BLOC-3. Our data suggest that VAMP7 mediates fusion of BLOC-1–dependent transport carriers with melanosomes, illuminate SNARE recycling from melanosomes as a critical BLOC-3–dependent step, and likely explain the distinct hypopigmentation phenotypes associated with BLOC-1 and BLOC-3 deficiency in Hermansky–Pudlak syndrome variants.
Midbody remnant licenses primary cilia formation in epithelial cells
Authors: Ott Carolyn M.
Published: August 2016

Tethered midbody remnants dancing across apical microvilli, encountering the centrosome, and beckoning forth a cilium—who would have guessed this is how polarized epithelial cells coordinate the end of mitosis and the beginning of ciliogenesis? New evidence from Bernabé-Rubio et al. (2016. J. Cell Biol. http://dx.doi.org/10.1083/jcb.201601020) supports this emerging model.
A miR-155–Peli1–c-Rel pathway controls the generation and function of T follicular helper cells
Authors: Liu Wen-Hsien , Kang Seung Goo , Huang Zhe , Wu Cheng-Jang , Jin Hyun Yong , Maine Christian J. , Liu Yi , Shepherd Jovan , Sabouri-Ghomi Mohsen , Gonzalez-Martin Alicia , Xu Shunbin , Hoffmann Alexander , Zheng Ye , Lu Li-Fan , Xiao Nengming , Fu Guo , Xiao Changchun
Published: August 2016

MicroRNA (miRNA) deficiency impairs the generation of T follicular helper (Tfh) cells, but the contribution of individual miRNAs to this phenotype remains poorly understood. In this study, we performed deep sequencing analysis of miRNAs expressed in Tfh cells and identified a five-miRNA signature. Analyses of mutant mice deficient of these miRNAs revealed that miR-22 and miR-183/96/182 are dispensable, but miR-155 is essential for the generation and function of Tfh cells. miR-155 deficiency led to decreased proliferation specifically at the late stage of Tfh cell differentiation and reduced CD40 ligand (CD40L) expression on antigen-specific CD4+ T cells. Mechanistically, miR-155 repressed the expression of Peli1, a ubiquitin ligase that promotes the degradation of the NF-κB family transcription factor c-Rel, which controls cellular proliferation and CD40L expression. Therefore, our study identifies a novel miR-155–Peli1–c-Rel pathway that specifically regulates Tfh cell generation and function.
Insights into the structure and function of HV1 from a meta-analysis of mutation studies
Authors: DeCoursey Thomas E. , Morgan Deri , Musset Boris , Cherny Vladimir V.
Published: August 2016

The voltage-gated proton channel (HV1) is a widely distributed, proton-specific ion channel with unique properties. Since 2006, when genes for HV1 were identified, a vast array of mutations have been generated and characterized. Accessing this potentially useful resource is hindered, however, by the sheer number of mutations and interspecies differences in amino acid numbering. This review organizes all existing information in a logical manner to allow swift identification of studies that have characterized any particular mutation. Although much can be gained from this meta-analysis, important questions about the inner workings of HV1 await future revelation.
MethFlowVM: a virtual machine for the integral analysis of bisulfite sequencing data
Authors: Lebrón Ricardo , Barturen Guillermo , Gómez-Martín Cristina , Oliver José L. , Hackenberg Michael
Published: August 2016

The analysis of whole genome DNA methylation patterns is an important first step towards the understanding on how DNA methylation is involved in the regulation of gene expression and genome stability.

Previously, we published MethylExtract, a program for DNA methylation profiling and genotyping from the same sample. Over the last years we developed it further into a methylation analysis pipeline that allows to take full advantage of novel genome assembly models. The result is a new pipeline termed MethFlow which permits both, profiling of methylation levels and differential methylation analysis.

Frequently DNA methylation research is carried out in the biomedical field, where privacy issues play an important role. Therefore we implemented the pipeline into a virtual machine termed MethFlowVMwhich shares with a web-server its user-friendliness however, the decisive advantage is that the sequencing data does not leave the user desktop or server and therefore no privacy issues do exist.

The virtual machine is available at:http://bioinfo2.uqr.es:8080/MethFlow/
Inhibition of cell proliferation does not slow down echinoderm neural regeneration
Authors: Mashanov Vladimir S. , Zueva Olga R. , García-Arrarás José E.
Published: August 2016

Background

Regeneration of the damaged central nervous system is one of the most interesting post-embryonic developmental phenomena. Two distinct cellular events have been implicated in supplying regenerative neurogenesis with cellular material – generation of new cells through cell proliferation and recruitment of already existing cells through cell migration. The relative contribution and importance of these two mechanisms is often unknown.

Methods

Here, we use the regenerating radial nerve cord (RNC) of the echinodermHolothuria glaberrimaas a model of extensive post-traumatic neurogenesis in the deuterostome central nervous system. To uncouple the effects of cell proliferation from those of cell migration, we treated regenerating animals with aphidicolin, a specific inhibitor of S-phase DNA replication. Cell migration was tracked with vital staining with the lipophilic dye DiI.

Results

Aphidicolin treatment resulted in a significant 2.1-fold decrease in cell proliferation. In spite of this, the regenerating RNC in the treated animals did not differ in histological architecture, size and cell number from its counterpart in the control vehicle-treated animals. DiI labeling showed extensive cell migration in the RNC. Some cells migrated from as far as 2 mm away from the injury plane to contribute to the neural outgrowth.

Conclusions

We suggest that inhibition of cell division in the regenerating RNC of H.glaberrima, is compensated for by recruitment of cells, which migrate into the RNC outgrowth from deeper regions of the neuroepithelium. Neural regeneration in echinoderms is thus a highly regulative developmental phenomenon, in which the size of the cell pool can be controlled either by cell proliferation or cell migration, and the latter can neutralize perturbations in the former.
Training and spontaneous reinforcement of neuronal assemblies by spike timing plasticity
Authors: Ocker Gabriel Koch , Doiron Brent
Published: August 2016

The synaptic connectivity of cortex is plastic, with experience shaping the ongoing interactions between neurons. Theoretical studies of spike timing–dependent plasticity (STDP) have focused on either just pairs of neurons or large-scale simulations. A simple analytic account for how fast spike time correlations affect both micro- and macroscopic network structure is lacking. We develop a low-dimensional mean field theory for STDP in recurrent networks and show the emergence of assemblies of strongly reciprocally coupled neurons with shared stimulus preferences. After training this connectivity is actively reinforced by spike train correlations during the spontaneous dynamics. Furthermore, the stimulus coding by cell assemblies is actively maintained by these internally generated spiking correlations, suggesting a new role for noise correlations in neural coding. Assembly formation has been often associated with firing rate-based plasticity schemes; our theory provides an alternative and complementary framework, where fine temporal correlations and STDP form and actively maintain learned structure in cortical networks.
Using Digital Polymerase Chain Reaction to Detect Single-Nucleotide Substitutions Induced by Genome Editing
Authors: Miyaoka Yuichiro , Chan Amanda H. , Conklin Bruce R.
Published: August 2016

This protocol is designed to detect single-nucleotide substitutions generated by genome editing in a highly sensitive and quantitative manner. It uses a combination of allele-specific hydrolysis probes and a new digital polymerase chain reaction (dPCR) technology called droplet digital PCR (ddPCR). ddPCR partitions a reaction into more than 10,000 nanoliter-scale water-in-oil droplets. As a result, each droplet contains only a few copies of the genome so that ddPCR is able to detect rare genome-editing events without missing them.
Single-Channel Recording of Glycine Receptors in Human Embryonic Kidney (HEK) Cells
Authors: Plested Andrew J.R. , Baranovic Jelena
Published: August 2016

This protocol describes how to record the single-channel activity of recombinant homomeric glycine receptors expressed in human embryonic kidney (HEK) cells. Cell-attached recordings readily reveal the large conductance (90 pS) and distinctive clusters of activations at high glycine concentration. This method for obtaining equilibrium recordings can be adapted to any ion channel receptor. The necessary extensions to outside-out patch for nonequilibrium recordings are also described, as are basic analyses of channel properties and activity.
Selecting Female Mice in Estrus and Checking Plugs
Authors: Behringer Richard , Gertsenstein Marina , Nagy Kristina Vintersten , Nagy Andras
Published: August 2016

The female mouse estrous cycle is divided into four phases: proestrus (development of ovarian follicles), estrus (ovulation), metestrus (formation of corpora lutea), and diestrus (beginning of follicle development for next ovulation and elimination of previous oocytes). The appearance of the epithelium of the external genitalia is used to identify the stage of the estrous cycle of a female mouse. This is usually easier to see in strains with either no or only light skin pigmentation. By examining the color, moistness, and degree of swelling of the vagina, females in estrus can readily be identified. To set up the matings, females are examined in the afternoon, and those in estrus are placed into the cages with males (one or two females in each cage with one male). Usually, 50% or more of the selected females will mate. The presence of a vaginal copulation plug next morning indicates that mating has occurred, but it does not mean that a pregnancy will result even if proven breeder fertile males were used. It is important to check vaginal plugs early in the morning because they fall out or are no longer detectable ~12 h after mating or sometimes earlier.
Data Formats in Bioinformatics
Authors: Hung Jui-Hung , Weng Zhiping
Published: August 2016

Here we introduce several interchangeable data formats that are commonly used in bioinformatics.
Structure and topology of three-dimensional hydrocarbon polymers
Authors: Kondrin Mikhail V. , Lebed Yulia B. , Brazhkin Vadim V.
Published: August 2016

A new family of three-dimensional hydrocarbon polymers which are more energetically favorable than benzene is proposed. Although structurally these polymers are closely related to well known diamond and lonsdaleite carbon structures, using topological arguments we demonstrate that they have no known structural analogs. Topological considerations also give some indication of possible methods of synthesis. Taking into account their exceptional optical, structural and mechanical properties these polymers might have interesting applications.
Growth, morphology, structure and characterization ofL-histidinium dihydrogen arsenate orthoarsenic acid single crystal
Authors: Tyagi Nidhi , Sinha Nidhi , Yadav Harsh , Kumar Binay
Published: August 2016

L-Histidinium dihydrogen arsenate orthoarsenic acid (LHAS) crystals were grown by the slow evaporation method. Single-crystal X-ray diffraction confirms monoclinic structure. The growth rates of various planes of LHAS crystals were estimated by morphological study. Hirshfeld surface and fingerprint plots were analyzed to investigate the intermolecular interactions at 0.002 a.u. present in the crystal structure. The functional groups and phase behavior of the compound are studied by FTIR spectroscopy and differential scanning calorimetry (DSC). A ferroelectric to paraelectric phase transition at 307 K was observed in dielectric studies. The piezoelectric charge coefficients of the grown crystal were found to be 2 pC/N. The values of coercive field (Ec), remnant polarization (Pr) and spontaneous polarization (Ps) in the hysteresis loop are found to be 5.236 kV cm−1, 0.654 µC cm−2and 2.841 µC cm−2, respectively. Piezoelectricity and ferroelectricity are reported for the first time in LHAS crystals. The mechanical strength was confirmed from microhardness study and void volume. Due to the low value of the dielectric constant, and good piezoelectric and ferroelectric properties, LHAS crystals can be used in microelectronics, sensors and advanced electronic devices.
Exploring polymorphism of benzene and naphthalene with free energy based enhanced molecular dynamics
Authors: Schneider Elia , Vogt Leslie , Tuckerman Mark E.
Published: August 2016

Prediction and exploration of possible polymorphism in organic crystal compounds are of great importance for industries ranging from organic electronics to pharmaceuticals to high-energy materials. Here we apply our crystal structure prediction procedure and the enhanced molecular dynamics based sampling approach called the Crystal-Adiabatic Free Energy Dynamics (Crystal-AFED) method to benzene and naphthalene. Crystal-AFED allows the free energy landscape of structures to be explored efficiently at any desired temperature and pressure. For each system, we successfully predict the most stable crystal structures at atmospheric pressure and explore the relative Gibbs free energies of predicted polymorphs at high pressures. Using Crystal-AFED sampling, we find that mixed structures, which typically cannot be discovered by standard crystal structure prediction methods, are prevalent in the solid forms of these compounds at high pressure.
Effect of packing motifs on the energy ranking and electronic properties of putative crystal structures of tricyano-1,4-dithiino[c]-isothiazole
Authors: Curtis Farren , Wang Xiaopeng , Marom Noa
Published: August 2016

We present an analysis of putative structures of tricyano-1,4-dithiino[c]-isothiazole (TCS3), generated within the sixth crystal structure prediction blind test. Typical packing motifs are identified and characterized in terms of distinct patterns of close contacts and regions of electrostatic and dispersion interactions. We find that different dispersion-inclusive density functional theory (DFT) methods systematically favor specific packing motifs, which may affect the outcome of crystal structure prediction efforts. The effect of crystal packing on the electronic and optical properties of TCS3 is investigated using many-body perturbation theory within theGWapproximation and the Bethe–Salpeter equation (BSE). We find that a structure withPna21symmetry and a bilayer packing motif exhibits intermolecular bonding patterns reminiscent of π–π stacking and has markedly different electronic and optical properties than the experimentally observedP21/nstructure with a cyclic dimer motif, including a narrower band gap, enhanced band dispersion and broader optical absorption. ThePna21bilayer structure is close in energy to the observed structure and may be feasible to grow.
Board and audit committee effectiveness, ethnic diversification and earnings management: a study of the Malaysian manufacturing sector
Authors: Wan Mohammad Wan Masliza , Wasiuzzaman Shaista , Nik Salleh Nik Mohamad Zaki
Published: August 2016

Purpose

This purpose of this paper is to examine the implications of the Revised Malaysian Code on Corporate Governance (2007) toward the effectiveness of the board and audit committees in Malaysian manufacturing companies. Since the manufacturing firms are dominantly held by Chinese firms, this paper is extended to incorporate the implication of ethnicity on board and audit committees’ effectiveness.

Design/methodology/approach

Using a sample of 201 firms from fiscal year 2004-2009, the data set consists of a total of 1,206 firm-year observations. Analysis is carried out using correlation analysis, multiple and logistic regression analyses.

Findings

The findings reveal that board and audit committees’ effectiveness is positively associated with earnings management pre- and post-Revised Malaysian Code on Corporate Governance (2007). A higher number of ethnic members in the board are also positively associated with earnings management.

Research limitations/implications

This study is limited to some industries in the manufacturing sector due to the special characteristics of this sector and covers mostly large firms. The results may not therefore be applicable to small firms. Finally, the study does not consider possible interaction between the board and audit characteristics which may be significant in influencing earnings management.

Practical implications

The findings show that the corporate governance mechanism in Malaysian firms is currently inadequate in preventing earnings management and extra effort is needed to improve board governance.

Originality/value

This paper contributes to the current literature on the issues of corporate governance effectiveness and board ethnicity in the current economic and political structure in Malaysia.
Effect of rotating cylinder on heat transfer in a differentially heated rectangular enclosure filled with power law non-Newtonian fluid
Authors: Sojoudi Atta , Khezerloo Marzieh , Saha Suvash C , Gu Yuantong
Published: August 2016

Purpose

– The purpose of this paper is to numerically investigate two dimensional steady state convective heat transfer in a differentially heated square cavity with constant temperatures and an inner rotating cylinder. The gap between the cylinder and the enclosure walls is filled with power law non-Newtonian fluid.

Design/methodology/approach

– Finite volume-based CFD software, Fluent (Ansys 15.0) is used to solve the governing equations. Attribution of the various flow parameters of fluid flow and heat transfer are investigated including Rayleigh number, Prandtl number, power law index, the cylinder radius and the angular rotational speed.

Findings

– Outcomes are reported in terms of isotherms, streamlines and average Nusselt number (Nu) of the heated wall for various considered here.

Research limitations/implications

– A detailed investigates is needed in the context of 3D flow. This will be a part of the future work.

Practical implications

– The effect of a rotating cylinder on heat transfer and fluid flow in a differentially heated rectangular enclosure filled with power law non-Newtonian fluid has practical importance in the process industry.

Originality/value

– The results of this study may be of some interest to the researchers of the field of chemical or process engineers.
A two-dimensional simulation of solidification processes in materials with thermo-dependent properties using XFEM
Authors: Stapór Pawel
Published: August 2016

Purpose

– The purpose of this paper is to carry out a finite element simulation of a physically non-linear phase change problem in a two-dimensional space without adaptive remeshing or moving-mesh algorithms. The extended finite element method (XFEM) and the level set method (LSM) were used to capture the transient solution and motion of phase boundaries. It was crucial to consider the effects of unequal densities of the solid and liquid phases and the flow in the liquid region.

Design/methodology/approach

– The XFEM and the LSM are applied to solve non-linear transient problems with a phase change in a two-dimensional space. The model assumes thermo-dependent properties of the material and unequal densities of the phases; it also allows for convection in the liquid phase. A non-linear system of equations is derived and a numerical solution is proposed. The Newton-Raphson method is used to solve the problem and the LSM is applied to track the interface.

Findings

– The robustness and utility of the method are demonstrated on several two-dimensional benchmark problems.

Originality/value

– The novel procedure based on the XFEM and the LSM was developed to solve physically non-linear phase change problems with unequal densities of phases in a two-dimensional space.
Effects of gap size for parallel 45 degree angled rib turbulators
Authors: Park Jongmyung , Park Samgyu , Ligrani Phillip M
Published: August 2016

Purpose

– Turbulent air flows within a channel with 45° angled rib turbulators on the top and bottom walls are numerically predicted using the numerical code. For the predictions, a v2-f turbulence model (velocity variance scale and elliptic relaxation factor model) is utilized. The paper aims to discuss these issues.

Design/methodology/approach

– Three different rib arrangements with or without gap are investigated to present information on the effects of gap size on flow structure and heat transfer characteristics. Three-dimensional turbulent transport, and detailed flow structural characteristics are considered to provide new insight into the mechanisms which result in surface heat transfer augmentations.

Findings

– Compared to the baseline rib arrangement, the numerically predicted results show that the parallel ribs with gap (where the width of the gap is two times of rib height) shows the highest local Nusselt number ratios. This is a result of locally increased vorticity distributions, as well as augmented local magnitudes of mixing, secondary flows, and turbulent transport. Local transport changes are less pronounced when the gap width of gap is 0.5 times of rib height. As a result, associated local and spatially averaged Nusselt number ratios are also lower for this arrangement.

Practical implications

– Results will give improved heat transfer augmentation technologies.

Originality/value

– The present investigation provides new information and insight into flow structural characteristics in a channel with rib turbulators, both with and without gaps, especially the mechanisms which result in surface heat transfer augmentations, which are not available in any other existing numerical or experimental investigation.
Development of a stream function-upper bound analysis applicable to the process of plate rolling
Authors: Asgharzadeh Amir , Serajzadeh Siamak
Published: August 2016

Purpose

– The purpose of this paper is to develop a mathematical solution to estimate the deformation pattern and required power in cold plate rolling using coupled stream function method and upper bound theorem.

Design/methodology/approach

– In the first place, an admissible velocity field and the geometry of deformation zone are derived from a new stream function. Then, the optimum velocity field is obtained by minimizing the corresponding power function. Also, to calculate the adiabatic heating during high speed rolling operations, a two-dimensional conduction-convection problem is sequentially coupled with the mechanical model. To verify the predictions, rolling experiments on aluminum plates are conducted and also, a finite element analysis is performed by Abaqus/Explicit. The predicted deformation zone is then compared with the experimentally measured region as well as with the results of the finite element analysis.

Findings

– The results show that the predicted deformation zone and the temperature distribution fit reasonably with the experimental data while much lower computational cost needs comparing to the fully finite element analysis.

Originality/value

– A new stream function is proposed to properly describe the velocity field and deformation pattern during plate rolling considering the neutral point. Furthermore, the employed algorithm can be simply coupled with the thermal finite element analysis.
Effects of thermal and diffusion phase-lags in a plate with axisymmetric heat supply
Authors: Kumar Rajneesh , Sharma Nidhi , Lata Parveen
Published: August 2016

Purpose

– The purpose of this paper is to depict the effect of time and thermal and diffusion phase-lags due to axisymmetric heat supply in a ring. The problem is discussed within the context of dual-phase-lag heat transfer and dual-phase-lag diffusion models. The upper and lower surfaces of the ring are traction free and subjected to an axisymmetric heat supply.

Design/methodology/approach

– The solution is found by using Laplace and Hankel transform technique and a direct approach without the use of potential functions. The analytical expressions of displacements, stresses and chemical potential, temperature and mass concentration are computed in transformed domain. Numerical inversion technique has been applied to obtain the results in the physical domain. Numerically simulated results are depicted graphically. The effect of time and diffusion and thermal phase-lags are shown on the various components. Some particular cases of result are also deduced from the present investigation.

Findings

– It is observed that change in time changes the behaviour of deformations of the various components of stresses, displacements, chemical potential function, temperature change and mass concentration. The authors find that for t=0.2, trends are oscillatory in all the cases whereas for t=0.1, trends are quite different. A sound impact of diffusion and thermal phase-lags on the various quantities is observed. A lot of difference in the trends of single phase lag and dual phase lag is observed. The use of diffusion phase-lags in the equation of mass diffusion gives a more realistic model of thermoelastic diffusion media as it allows a delayed response between the relative mass flux vector and the potential gradient.

Originality/value

– This problem is totally new because dual phase lag is applied in heat conduction and diffusion equation while considering the problem of plate in axisymmetric heat supply.
Two-temperature generalized magneto-thermoelastic medium for dual-phase-lag model under the effect of gravity field and hydrostatic initial stress
Authors: Said Samia M
Published: August 2016

Purpose

– The dual-phase-lag (DPL) model and Lord-Shulman theory with one relaxation time are applied to study the effect of the gravity field, the magnetic field, and the hydrostatic initial stress on the wave propagation in a two-temperature generalized thermoelastic problem for a medium with an internal heat source that is moving with a constant speed. The paper aims to discuss this issue.

Design/methodology/approach

– The exact expressions of the considered variables are obtained by using normal mode analysis.

Findings

– Numerical results for the field quantities are given in the physical domain and illustrated graphically in the absence and presence of the gravity field as well as the magnetic field. Comparisons are made between the results of the two different models with and without temperature dependent properties and for two different values of the hydrostatic initial stress. A comparison is also made between the results of the two different models for two different values of the time.

Originality/value

– In the present work, the author shall formulate a two-temperature generalized magneto-thermoelastic problem for a medium with temperature dependent properties and with an internal heat source that is moving with a constant speed under the influence of a gravity field and a hydrostatic initial stress. Normal mode analysis is used to obtain the exact expressions for the displacement components, thermodynamic temperature, conductive temperature, and stress components. A comparison is carried out between the considered variables as calculated from the generalized thermoelasticity based on the DPL model and the L-S theory in the absence and presence of a magnetic field as well as a gravity field. Comparisons are also made between the results of the two theories with and without temperature dependent properties and for two different values of hydrostatic initial stress. A comparison is also made between the results of the two different models for two different values of the time.
Exergy Optimization of a Double-Exposure Solar Cooker by Response Surface Method
Authors: Zamani Hossein , Mahian Omid , Rashidi Iman , Lorenzini Giulio , Wongwises Somchai
Published: August 2016

The purpose of this study was to optimize the performance of a double-exposure solar cooker based on exergy efficiency. Two similar solar cookers with variable parabolic mirror position were used for this experimental research. The system's exergy depends on many variables, which were kept fixed with the exception of the mirror position and operation time. The mathematical model of exergy efficiency was obtained based on the experimental variables, which could be used to optimize the mirror positions at any time. As a result, a new system with a variable mirror on a parabolic curve was developed, which can yield up to 30% increased mean exergy efficiency. Validation of the results was carried out by both the variance analysis test and comparing with the experimental data. The experiments were carried out in Mashhad, Iran, at 37 latitude, 54 longitude, and a height of 985 m above sea level.
Heat Transfer and Pressure Loss Measurements in Additively Manufactured Wavy Microchannels
Authors: Kirsch Kathryn L. , Thole Karen A.
Published: August 2016

The role of additive manufacturing for the hot section components of gas turbine engines grows ever larger as progress in the industry continues. The opportunity for the heat transfer community is to exploit the use of additive manufacturing in developing nontraditional cooling schemes to be built directly into components. This study investigates the heat transfer and pressure loss performance of additively manufactured wavy channels. Three coupons, each containing channels of a specified wavelength (length of one wave period), were manufactured via direct metal laser sintering (DMLS) and tested at a range of Reynolds numbers. Results show that short wavelength channels yield high pressure losses, without corresponding increases in heat transfer, due to the flow structure promoted by the waves. Longer wavelength channels offer less of a penalty in pressure drop with good heat transfer performance.
Material Model for Creep-Assisted Microcracking Applied to S2 Sea Ice
Authors: Santaoja Kari , Reddy J. N.
Published: August 2016

A material model is presented that includes the following deformation mechanisms: the instantaneous response of ice due to distortion of crystal lattices, creep, the formation of microcrack nuclei due to creep, the formation of microcracks, and deformation due to microcracks. The new material model has a strict foundation on deformation mechanisms. This constitutive equation was applied to sea ice for engineering applications through implementation in the Abaqus explicit code by writing a VUMAT subroutine. The computed results show that the model correctly predicts the uniaxial tensile and the uniaxial compressive strengths of ice. The computed compressive strength versus strain-rate relation takes an almost linear relation when expressed in the log–log coordinates, which fits well with the data obtained from the literature. The material model shows the Hall–Petch type of strength dependency on the grain size.
Reliability-Based Design Optimization Concerning Objective Variation Under Mixed Probabilistic and Interval Uncertainties
Authors: Zhou Jianhua , Xu Min , Li Mian
Published: August 2016

Uncertainties, inevitable in nature, can be classified as probability based and interval based uncertainties in terms of its representations. Corresponding optimization strategies have been proposed to deal with these two types of uncertainties. It is more likely that both types of uncertainty can occur in one single problem, and thus, it is trivial to treat all uncertainties the same. A novel formulation for reliability-based design optimization (RBDO) under mixed probability and interval uncertainties is proposed in this paper, in which the objective variation is concerned. Furthermore, it is proposed to efficiently solve the worst-case parameter resulted from the interval uncertainty by utilizing the Utopian solution presented in a single-looped robust optimization (RO) approach where the inner optimization can be solved by matrix operations. The remaining problem can be solved utilizing any existing RBDO method. This work applies the performance measure approach to search for the most probable failure point (MPFP) and sequential quadratic programing (SQP) to solve the entire problem. One engineering example is given to demonstrate the applicability of the proposed approach and to illustrate the necessity to consider the objective robustness under certain circumstances.
Shifts in frequency-modulated pulses recorded during an encounter with Blainville's beaked whales (Mesoplodon densirostris)
Authors: Keating Jennifer L. , Barlow Jay , Rankin Shannon
Published: August 2016

Echolocation signals produced by beaked whales (family: Ziphiidae) include frequency-modulated (FM) pulses that appear to have species-specific characteristics. To date there has been no established evidence that a single species of beaked whale might produce more than one type of FM pulse. In 2014 a group of Blainville's beaked whales (Mesoplodon densirostris) were sighted off of Southern California; recordings included FM pulses with significant increases in peak frequency, center frequency, and −10 dB bandwidth relative to FM pulses previously attributed to this species. This research suggests there may be greater variation in received beaked whale FM pulses than previously understood.
Abdominal vascular trauma
Authors: Kobayashi Leslie M , Costantini Todd W , Hamel Michelle G , Dierksheide Julie E , Coimbra Raul
Published: August 2016

Abdominal vascular trauma, primarily due to penetrating mechanisms, is uncommon. However, when it does occur, it can be quite lethal, with mortality ranging from 20% to 60%. Increased early mortality has been associated with shock, acidosis, hypothermia, coagulopathy, free intraperitoneal bleeding and advanced American Association for the Surgery of Trauma Organ Injury Scale grade. These patients often arrive at medical centers in extremis and require rapid surgical control of bleeding and aggressive resuscitation including massive transfusion protocols. The most important factor in survival is surgical control of hemorrhage and restoration of appropriate perfusion to the abdominal contents and lower extremities. These surgical approaches and the techniques of definitive vascular repair can be quite challenging, particularly to the inexperienced surgeon. This review hopes to describe the most common abdominal vascular injuries, their presentation, outcomes, and surgical techniques to control and repair such injuries.
Generalized framework to predict undrained uplift capacity of buried offshore pipelines
Authors: Maitra Shubhrajit , Chatterjee Santiram , Choudhury Deepankar
Published: August 2016

Estimation of undrained uplift capacity is essential for the determination of optimal burial depth of buried offshore pipelines. However, a generalized prediction model that incorporates various factors influencing this capacity is scarce in the literature. In this paper, results from a series of small-strain finite element analyses are presented that explore the effects of pipe embedment, pipe–soil interface roughness, interface tensile capacity, soil shear strength, and unit weight on pipe uplift response. From the study, a simple method to predict the undrained upheaval resistance of buried pipelines for any practical range of pipeline and soil parameters is proposed. Factors associated with transition in failure mechanism with embedment are also examined. The numerical model is validated by comparing the results with available analytical and experimental data. Large-deformation finite element analyses have also been performed independently for a few cases to justify the applicability of small-strain methods in modelling pipe upheaval. Accuracy of the model for generalized shear strength profile is then examined by considering practical values of parameters over broad ranges. The proposed methodology gives results with maximum error less than 8% for all ranges of parameters and hence can be adopted in design practices.
A Discontinuous Finite Volume Element Method Based on Bilinear Trial Functions
Authors: Zhang Tie , Tang Lixin
Published: August 2016

We propose a discontinuous finite volume element (DFVE) method for second order elliptic and parabolic problems. Discontinuous bilinear functions are used as the trial functions. We give the stability analysis of this DFVE method and derive the optimal error estimates in the broken [Formula: see text]-norm. Specifically, the optimal [Formula: see text]-error is obtained for the first time for the bilinear DFVE methods solving elliptic and parabolic problems.
Extension and Calibration of a Hawkes-Based Optimal Execution Model
Authors: Alfonsi Aurélien , Blanc Pierre
Published: August 2016

We provide some theoretical extensions and a calibration protocol for our former dynamic optimal execution model. The Hawkes parameters and the propagator are estimated independently on financial data from stocks of the CAC40. Interestingly, the propagator exhibits a smoothly decaying form with one or two dominant time scales, but only so after a few seconds that the market needs to adjust after a large trade. Motivated by our estimation results, we derive the optimal execution strategy for a multi-exponential Hawkes kernel and backtest it on the data for round trips. We find that the strategy is profitable on average when trading at the midprice, which is in accordance with violated martingale conditions. However, in most cases, these profits vanish when we take bid–ask costs into account.
A Survey on the Current Status and Future Challenges Towards Objective Skills Assessment in Endovascular Surgery
Authors: Mazomenos Evangelos B. , Chang Ping-Lin , Rolls Alexander , Hawkes David J. , Bicknell Colin D. , Poorten Emmanuel Vander , Riga Celia V. , Desjardins Adrien , Stoyanov Danail
Published: August 2016

Minimally invasive endovascular interventions have evolved rapidly over the past decade, facilitated by breakthroughs in medical imaging and sensing, instrumentation and most recently robotics. Catheter-based operations are potentially safer and applicable to a wider patient population due to the reduced comorbidity. As a result endovascular surgery has become the preferred treatment option for conditions previously treated with open surgery and as such the number of patients undergoing endovascular interventions is increasing every year. This fact coupled with a proclivity for reduced working hours results in a requirement for efficient training and assessment of new surgeons, that deviates from the “see one, do one, teach one” model introduced by William Halsted, so that trainees obtain operational expertise in a shorter period. Developing more objective assessment tools based on quantitative metrics is now a recognized need in interventional training and this manuscript reports the current literature for endovascular skills assessment and the associated emerging technologies. A systematic search was performed on PubMed (MEDLINE), Google Scholar, IEEXplore and known journals using the keywords, “endovascular surgery”, “surgical skills”, “endovascular skills”, “surgical training endovascular” and “catheter skills”. Focusing explicitly on endovascular surgical skills, we group related works into three categories based on the metrics used; structured scales and checklists, simulation-based and motion-based metrics. This review highlights the key findings in each category and also provides suggestions for new research opportunities towards fully objective and automated surgical assessment solutions.