bluuebunny/crossref_metadata_2025 huggingface dataset:
A unified model for simulating liquid and gas phase, intermolecular energy transfer: N2 + C6F6 collisions
Authors: Paul Amit K. , Kohale Swapnil C. , Pratihar Subha , Sun Rui , North Simon W. , Hase William L.
Published: May 2014

Molecular dynamics simulations were used to study relaxation of a vibrationally excited C6F6* molecule in a N2 bath. Ab initio calculations were performed to develop N2-N2 and N2-C6F6 intermolecular potentials for the simulations. Energy transfer from “hot” C6F6 is studied versus the bath density (pressure) and number of bath molecules. For the large bath limit, there is no heating of the bath. As C6F6* is relaxed, the average energy of C6F6* is determined versus time, i.e., ⟨E(t)⟩, and for each bath density ⟨E(t)⟩ is energy dependent and cannot be fit by a single exponential. In the long-time limit C6F6 is fully equilibrated with the bath. For a large bath and low pressures, the simulations are in the fixed temperature, independent collision regime and the simulation results may be compared with gas phase experiments of collisional energy transfer. The derivative d[⟨E(t)⟩]/dt divided by the collision frequency ω of the N2 bath gives the average energy transferred from C6F6* per collision ⟨ΔEc⟩, which is in excellent agreement with experiment. For the ∼100–300 ps simulations reported here, energy transfer from C6F6* is to N2 rotation and translation in accord with the equipartition model, with no energy transfer to N2 vibration. The energy transfer dynamics from C6F6* is not statistically sensitive to fine details of the N2-C6F6 intermolecular potential. Tests, with simulation ensembles of different sizes, show that a relatively modest ensemble of only 24 trajectories gives statistically meaningful results.
Determination of the thermodynamic correction factor of fluids confined in nano-metric slit pores from molecular simulation
Authors: Collell Julien , Galliero Guillaume
Published: May 2014

The multi-component diffusive mass transport is generally quantified by means of the Maxwell-Stefan diffusion coefficients when using molecular simulations. These coefficients can be related to the Fick diffusion coefficients using the thermodynamic correction factor matrix, which requires to run several simulations to estimate all the elements of the matrix. In a recent work, Schnell et al. [“Thermodynamics of small systems embedded in a reservoir: A detailed analysis of finite size effects,” Mol. Phys. 110, 1069–1079 (2012)] developed an approach to determine the full matrix of thermodynamic factors from a single simulation in bulk. This approach relies on finite size effects of small systems on the density fluctuations. We present here an extension of their work for inhomogeneous Lennard Jones fluids confined in slit pores. We first verified this extension by cross validating the results obtained from this approach with the results obtained from the simulated adsorption isotherms, which allows to determine the thermodynamic factor in porous medium. We then studied the effects of the pore width (from 1 to 15 molecular sizes), of the solid-fluid interaction potential (Lennard Jones 9-3, hard wall potential) and of the reduced fluid density (from 0.1 to 0.7 at a reduced temperature T* = 2) on the thermodynamic factor. The deviation of the thermodynamic factor compared to its equivalent bulk value decreases when increasing the pore width and becomes insignificant for reduced pore width above 15. We also found that the thermodynamic factor is sensitive to the magnitude of the fluid-fluid and solid-fluid interactions, which softens or exacerbates the density fluctuations.
On the elastically coupled magnetic and ferroelectric domains: A phase-field model
Authors: Yang T. N. , Hu Jia-Mian , Nan C. W. , Chen L. Q.
Published: May 2014

A phase-field model is developed to study local elastic coupling between magnetic and ferroelectric domains that show one-to-one pattern match. A multiferroic layered heterostructure of Co0.4Fe0.6/BaTiO3 is considered as an example. Dynamics of the local elastic coupling is investigated by simulating a time-dependent electric-field driven changes in local magnetization/polarization/strain distributions and by comparing the associated velocities of the magnetic and ferroelectric domain walls. It is found that the electric-field-driven dynamic magnetic domain evolution manifests itself as an alternating occurrence of local magnetization rotation and coupled motion of magnetic and ferroelectric domain walls with almost identical velocities.
A macroscopic model for slightly compressible gas slip-flow in homogeneous porous media
Authors: Lasseux D. , Parada F. J. Valdes , Tapia J. A. Ochoa , Goyeau B.
Published: May 2014

The study of gas slip-flow in porous media is relevant in many applications ranging from nanotechnology to enhanced oil recovery and in any situation involving low-pressure gas-transport through structures having sufficiently small pores. In this paper, we use the method of volume averaging for deriving effective-medium equations in the framework of a slightly compressible gas flow. The result of the upscaling process is an effective-medium model subjected to time- and length-scale constraints, which are clearly identified in our derivation. At the first order in the Knudsen number, the macroscopic momentum transport equation corresponds to a Darcy-like model involving the classical intrinsic permeability tensor and a slip-flow correction tensor that is also intrinsic. It generalizes the Darcy-Klinkenberg equation for ideal gas flow, and exhibits a more complex form for dense gas. The component values of the two intrinsic tensors were computed by solving the associated closure problems on two- and three-dimensional periodic unit cells. Furthermore, the dependence of the slip-flow correction with the porosity was also verified to agree with approximate analytical results. Our predictions show a power-law relationship between the permeability and the slip-flow correction that is consistent with other works. Nevertheless, the generalization of such a relationship to any configuration requires more analysis.
Mixing in a liquid metal electrode
Authors: Kelley Douglas H. , Sadoway Donald R.
Published: May 2014

Fluid mixing has first-order importance for many engineering problems in mass transport, including design and optimization of liquid-phase energy storage devices. Liquid metal batteries are currently being commercialized as a promising and economically viable technology for large-scale energy storage on worldwide electrical grids. But because these batteries are entirely liquid, fluid flow and instabilities may affect battery robustness and performance. Here we present estimates of flow magnitude and ultrasound measurements of the flow in a realistic liquid metal electrode. We find that flow does substantially affect mass transport by altering the electrode mixing time. Above a critical electrical current density, the convective flow organizes and gains speed, which promotes transport and would yield improved battery efficiency.
Light trapping and electrical transport in thin-film solar cells with randomly rough textures
Authors: Kowalczewski Piotr , Bozzola Angelo , Liscidini Marco , Claudio Andreani Lucio
Published: May 2014

Using rigorous electro-optical calculations, we predict a significant efficiency enhancement in thin-film crystalline silicon (c-Si) solar cells with rough interfaces. We show that an optimized rough texture allows one to reach the Lambertian limit of absorption in a wide absorber thickness range from 1 to 100 μm. The improvement of efficiency due to the roughness is particularly substantial for thin cells, for which light trapping is crucial. We consider Auger, Shockley-Read-Hall (SRH), and surface recombination, quantifying the importance of specific loss mechanisms. When the cell performance is limited by intrinsic Auger recombination, the efficiency of 24.4% corresponding to the wafer-based PERL cell can be achieved even if the absorber thickness is reduced from 260 to 10 μm. For cells with material imperfections, defect-based SRH recombination contributes to the opposite trends of short-circuit current and open-circuit voltage as a function of the absorber thickness. By investigating a wide range of SRH parameters, we determine an optimal absorber thickness as a function of material quality. Finally, we show that the efficiency enhancement in textured cells persists also in the presence of surface recombination. Indeed, in our design the efficiency is limited by recombination at the rear (silicon absorber/back reflector) interface, and therefore it is possible to engineer the front surface to a large extent without compromising on efficiency.
Vertically aligned crystalline silicon nanowires with controlled diameters for energy conversion applications: Experimental and theoretical insights
Authors: Razek Sara Abdel , Swillam Mohamed A. , Allam Nageh K.
Published: May 2014

Vertically orientated single crystalline silicon nanowire (SiNW) arrays with controlled diameters are fabricated via a metal-assisted chemical etching method. The diameter of the fabricated nanowires is controlled by simply varying the etching time in HF/H2O2 electrolytes. The fabricated SiNWs have diameters ranging from 117 to 650 nm and lengths from 8 to 18 μm. The optical measurements showed a significant difference in the reflectance/absorption of the SiNWs with different diameters, where the reflectance increases with increasing the diameter of the SiNWs. The SiNWs showed significant photoluminescence (PL) emission spectra with peaks lying between 380 and 670 nm. The PL intensity increases as the diameter increases and shows red shift for peaks at ∼670 nm. The increase or decrease of reflectivity is coincident with PL intensity at wavelength ∼660 nm. The x-ray diffraction patterns confirm the high crystallinity of the fabricated SiNWs. In addition, the Raman spectra showed a shift in the first order transverse band toward lower frequencies compared to that usually seen for c-Si. Finite difference time domain simulations have been performed to confirm the effect of change of diameter on the optical properties of the nanowires. The simulation results showed good agreement with the experimental results for the SiNWs of different diameters.
Acoustic scattering by elastic cylinders of elliptical cross-section and splitting up of resonances
Authors: Ancey S. , Bazzali E. , Gabrielli P. , Mercier M.
Published: May 2014

The scattering of a plane acoustic wave by an infinite elastic cylinder of elliptical cross section is studied from a modal formalism by emphasizing the role of the symmetries. More precisely, as the symmetry is broken in the transition from the infinite circular cylinder to the elliptical one, the splitting up of resonances is observed both theoretically and experimentally. This phenomenon can be interpreted using group theory. The main difficulty stands in the application of this theory within the framework of the vectorial formalism in elastodynamics. This method significantly simplifies the numerical treatment of the problem, provides a full classification of the resonances, and gives a physical interpretation of the splitting up in terms of symmetry breaking. An experimental part based on ultrasonic spectroscopy complements the theoretical study. A series of tank experiments is carried out in the case of aluminium elliptical cylinders immersed in water, in the frequency range 0 ≤ kr ≤ 50, where kr is the reduced wave number in the fluid. The symmetry is broken by selecting various cylinders of increasing eccentricity. More precisely, the greater the eccentricity, the higher the splitting up of resonances is accentuated. The experimental results provide a very good agreement with the theoretical ones, the splitting up is observed on experimental form functions, and the split resonant modes are identified on angular diagrams.
Electric-field–temperature phase diagram of the ferroelectric relaxor system (1 − x)Bi1/2Na1/2TiO3 − xBaTiO3 doped with manganese
Authors: Sapper Eva , Novak Nikola , Jo Wook , Granzow Torsten , Rödel Jürgen
Published: May 2014

The electric-field–temperature phase diagram for the lead-free relaxor material (1 − x)(Bi1/2Na1/2)TiO3 − xBaTiO3 (x = 0.03, 0.06, and 0.09) doped with 0.5 mol% Mn (BNT-100xBT:Mn) was established. Transition lines between ergodic or nonergodic relaxor states and the field-induced ferroelectric state were determined at constant temperatures with electric-field-dependent measurements of the polarization as well as of the piezoelectric coefficient and permittivity. Near the depolarization temperature Td, the switching between two ferroelectric poling directions occurs in two steps via an intermediate relaxor state. This effect is closely related to the pinching of the ferroelectric hysteresis loop.
Valley and spin thermoelectric transport in ferromagnetic silicene junctions
Authors: Ping Niu Zhi , Dong Shihao
Published: May 2014

We have investigated the valley and spin resolved thermoelectric transport in a normal/ferromagnetic/normal silicene junction. Due to the coupling between the valley and spin degrees of freedom, thermally induced pure valley and spin currents can be demonstrated. The magnitude and sign of these currents can be manipulated by adjusting the ferromagnetic exchange field and local external electric field, thus the currents are controllable. We also find fully valley and/or spin polarized currents. Similar to the currents, owing to the band structure symmetry, tunable pure spin and/or valley thermopowers with zero charge counterpart are generated. The results obtained here suggest a feasible way of generating a pure valley (spin) current and thermopower in silicene.
Experimental observation of heat transparency
Authors: Zeng Lunwu , Song Runxia
Published: May 2014

In this Letter, we experimentally observed heat diffusion transparency with the heat diffusion device we fabricated, which can measure time-dependent temperature. Utilizing the effective medium theory, we fabricated an isotropic spherical shell with an isotropic spherical core, as well as a multilayer isotropic spherical shell with an isotropic spherical core as neutral inclusions. We measured the temperatures and temperature gradients outside the neutral inclusions with the self-made heat diffusion device and analyzed the heat transparent conditions. The experimental results show that the temperature gradients are parallel and equal outside the neutral inclusion, and the iso-temperature lines are also parallel outside the neutral inclusion.
Foliar herbicide control of sticky florestina (Florestina tripteris DC.)
Authors: McKenzie John , Brazier Dannielle , Campbell Shane , Vitelli Joseph , Anderson Angela , Mayer Robert
Published: May 2014

Sticky florestina (Florestina tripteris DC.) is an annual exotic weed that has become naturalised near the townships of Tambo and Barcaldine in central western Queensland, Australia. Three experiments conducted near Barcaldine identified foliar herbicides effective in killing sticky florestina plants and in providing residual activity to reduce recruitment from the soil seed bank. An initial chemical screening experiment evaluated the efficacy of 28 herbicide treatments. The most promising herbicides were then further evaluated in two response-rate experiments. Overall, 2,4-D/picloram, aminopyralid/fluroxypyr, clopyralid, metsulfuron-methyl and triclopyr/picloram proved to be the most effective selective herbicides. Two of these, metsulfuron-methyl at 18 g active ingredient (a.i) ha–1 and 2,4-D + picloram at 900 g a.i. ha–1 + 225 g a.i. ha–1 have now been included in a minor use permit (PER11920) with the Australian Pesticides and Veterinary Medicines Authority (APVMA) for the control of sticky florestina in pasture, stock route, roadside and non-crop situations using both spot and boom-spray applications (APVMA 2010). The permit also allows the use of 2,4-D amine for the control of seedlings only.
Optimal lamellar arrangement in fish gills
Authors: Park Keunhwan , Kim Wonjung , Kim Ho-Young
Published: May 2014

Significance

It is generally assumed that shapes encountered in nature have evolved in a way as to maximize the robustness of a species. Nevertheless, given nature’s notoriously complex designs, it is often unclear what is being optimized. The lamellar pattern of fish gills is one of the few cases in which optimization in nature can be well defined. We demonstrate that the lamellar pattern of fish gills has been optimized, such that fish display interlamellar spaces of similar dimension regardless of body mass or species, thereby revealing the primary evolutionary pressure on fish gills. This natural optimization strategy demonstrates how control of the channel arrangement in microfluidic devices enhances heat and mass transfer.
Publisher, be damned! From price gouging to the open road
Authors: Harvie David , Lightfoot Geoff , Lilley Simon , Weir Kenneth
Published: May 2014

All four authors are members of the Leicester school of critical management and have previously written together on academic publishing. David Harvie lectures in finance and is interested in ethical issues related to this and other matters. He is a member of The Free Association writing collective. Geoff Lightfoot lectures in entrepreneurship and has particular interests in the ideology of markets and critical accounting. Simon Lilley works on information aspects of organisation and is currently head of the School of Management at Leicester University. Kenneth Weir is interested in accounting practices, especially critical and social accounting.
Purification and characterization of β-Mannanase from Reinekea sp. KIT-YO10 with transglycosylation activity
Authors: Hakamada Yoshihiro , Ohkubo Yoshitaka , Ohashi Shinichi
Published: May 2014

Marine bacterium Reinekea sp. KIT-YO10 was isolated from the seashore of Kanazawa Port in Japan as a seaweed-degrading bacterium. Homology between KIT-YO10 16S rDNA and the 16S rDNA of Reinekea blandensis and Reinekea marinisedimentorum was 96.4 and 95.4%, respectively. Endo-1,4-β-D-mannanase (β-mannanase, EC 3.2.1.78) from Reinekea sp. KIT-YO10 was purified 29.4-fold to a 21% yield using anion exchange chromatography. The purified enzyme had a molecular mass of 44.3 kDa, as estimated by SDS-PAGE. Furthermore, the purified enzyme displayed high specificity for konjac glucomannan, with no secondary agarase and arginase activity detected. Hydrolysis of konjac glucomannan and locust bean gum yielded oligosaccharides, compatible with an endo mode of substrate depolymerization. The purified enzyme possessed transglycosylation activity when mannooligosaccharides (mannotriose or mannotetraose) were used as substrates. Optimal pH and temperature were determined to be 8.0 and 70 °C, respectively. It showed thermostability at temperatures from 20 to 50 °C and alkaline stability up to pH 10.0. The current enzyme was thermostable and thermophile compared to the β-mannanase of other marine bacteria.
Vancomycin-Resistant Enterococcus (VRE) Transmission and Risk Factors in Contacts of VRE Carriers
Authors: Kaki Reham , Yu Yang , O’Neill Cindy , Lee Christine , Mertz Dominik ,   Hamilton Health Sciences Infection Prevention and Control Team
Published: May 2014

During a 2-year period, the vancomycin-resistant enterococcus (VRE) acquisition rate was 10.9% (40/368) in patients who had shared a room with a newly detected VRE carrier. Exposure to vancomycin and to anti-anaerobic antibiotics were identified as independent risk factors for VRE acquisition. Sensitivity of the first rectal VRE screening was less than 50%.

Infect Control Hosp Epidemiol 2014;35(7):876–879
Vector fields whose linearisation is Hurwitz almost everywhere
Authors: Pires Benito , Rabanal Roland
Published: May 2014

A real matrix is Hurwitz if its eigenvalues have negative real parts. The following generalisation of the Bidimensional Global Asymptotic Stability Problem (BGAS) is provided. Let

X
:

R

2

→

R

2

X:\mathbb {R}^2\to \mathbb {R}^2

be a

C
1

C^1

vector field whose Jacobian matrix

D
X
(
p
)

DX(p)

is Hurwitz for Lebesgue almost all

p
∈

R

2

p\in \mathbb {R}^2

. Then the singularity set of

X
X

is either an empty set, a one–point set or a non-discrete set. Moreover, if

X
X

has a hyperbolic singularity, then

X
X

is topologically equivalent to the radial vector field

(
x
,
y
)
↦
(
−
x
,
−
y
)

(x,y)\mapsto (-x,-y)

. This generalises BGAS to the case in which the vector field is not necessarily a local diffeomorphism.
Algebras in which every subalgebra is noetherian
Authors: Rogalski D. , Sierra S. , Stafford J.
Published: May 2014

We show that the twisted homogeneous coordinate rings of elliptic curves by infinite order automorphisms have the curious property that every subalgebra is both finitely generated and noetherian. As a consequence, we show that a localisation of a generic Skylanin algebra has the same property.
SparkSeq: fast, scalable and cloud-ready tool for the interactive genomic data analysis with nucleotide precision
Authors: Wiewiórka Marek S. , Messina Antonio , Pacholewska Alicja , Maffioletti Sergio , Gawrysiak Piotr , Okoniewski Michał J.
Published: May 2014

Summary: Many time-consuming analyses of next - generation sequencing data can be addressed with modern cloud computing. The Apache Hadoop-based solutions have become popular in genomics because of their scalability in a cloud infrastructure. So far, most of these tools have been used for batch data processing rather than interactive data querying.

The SparkSeq software has been created to take advantage of a new MapReduce framework, Apache Spark, for next-generation sequencing data. SparkSeq is a general-purpose, flexible and easily extendable library for genomic cloud computing. It can be used to build genomic analysis pipelines in Scala and run them in an interactive way. SparkSeq opens up the possibility of customized ad hoc secondary analyses and iterative machine learning algorithms. This article demonstrates its scalability and overall fast performance by running the analyses of sequencing datasets. Tests of SparkSeq also prove that the use of cache and HDFS block size can be tuned for the optimal performance on multiple worker nodes.

Availability and implementation: Available under open source Apache 2.0 license: https://bitbucket.org/mwiewiorka/sparkseq/ .

Contact:  marek.wiewiorka@gmail.com

Supplementary information:  Supplementary data are available at Bioinformatics online.
Documentation of Dual Sensory Impairment in Electronic Medical Records
Authors: Dullard Brittney , Saunders Gabrielle H.
Published: May 2014

Purpose of the Study:

To examine the documentation of sensory impairment in the electronic medical records (EMRs) of Veterans with both hearing and vision losses (dual sensory impairment [DSI]).

Design and Methods:

A retrospective chart review of the EMRs of 20 patients with DSI was conducted. Providers’ documentation of the presence of sensory impairment, the use of assistive technology during clinical appointments, and the content of notes mentioning communication issues were extracted from each chart note in the EMR for the prior 6 years.

Results:

Primary care providers documented DSI in 50% of EMRs, vision loss alone in 40%, and hearing loss alone in 10% of EMRs. Audiologists documented vision loss in 50% of cases, whereas ophthalmologists/optometrists documented hearing loss in 15% of cases. Examination of two selected cases illustrates that care can be compromised when providers do not take note of sensory impairments during planning and provision of clinical care.

Implications:

Sensory impairment is poorly documented by most providers in EMRs. This is alarming because vision and hearing affect patient–physician communication and the use of medical interventions. The results of this study raise awareness about the need to document the presence of sensory impairments and use the information when planning treatment for individuals with DSI.
Concepts of Sustainability, Motivations for Pest Management Approaches, and Implications for Communicating Change
Authors: Sherman Jennifer , Gent David H.
Published: May 2014

Impact and relevance are valued by both plant pathologists and the supporters of research and extension. Impact has been characterized as the “So what?” of research results, and in applied research in agriculture typically involves some change in human behavior. This might involve, for instance, avoidance of broad spectrum pesticides, use of economic thresholds, or adoption of a new cultural practice in disease management. Changes in human behavior often are slow and difficult, even when the potential benefits of change seem clear. Research and extension personnel working with farmers have discussed for decades the apparent slow pace of adoption of integrated pest management (IPM) and other less-pesticide-intensive management practices. The reasons why change is slow are numerous, but one aspect that warrants consideration is how changes in farm practices are communicated to farmers. Effectively communicating changes in pest management practices at the farm level requires a system of research and extension management that differs from that to which most biological scientists are accustomed. What is the motivation for farmers to deviate from historical practices? How persuasive are concepts of environmental sustainability, integrated pest management, risk management, and economic gain in communicating the needs for change? In addressing these questions, it is useful to understand some of the basic determinants of farmers' decision processes and motivations to adopt practices. This article discusses these issues.
First Report of the Root-Knot Nematode Meloidogyne hapla Parasitizing Roses in Ethiopia
Authors: Meressa Beira H. , Heuer H. , Dehne H.-W. , Hallmann J.
Published: May 2014

Meloidogyne hapla is one of the most damaging plant-parasitic nematodes in temperate regions. This nematode has a wide host range with more than 500 plant taxa including roses. In Ethiopia, rose production has developed over the past 10 years to the second most important export market after coffee. Considering the high damage potential of M. hapla, infestation of roses in Ethiopia with this nematode could result in major economic losses. Therefore, awareness of this nematode species is extremely important. During two surveys conducted in August 2011 and April 2012, M. hapla was detected in soil samples from six out of nine rose producing farms located in the districts of Ziway, Holleta, Sebeta, and Menagesha. At infested farms, rose plants appeared stunted and less productive and often showed symptoms of chlorosis and wilting. Identification was based on morphological and morphometrical characters of females, males, and second-stage juveniles, which were all within the range of variability known for this species (4). Shape of juvenile stylet knobs, shape of male head, and perennial pattern of the females with characteristic punctuations between the anus and tail terminus were also typical for M. hapla. The morphological identification was confirmed by sequence analysis of the D2-D3 expansion segment of the 28S rDNA gene following amplification with the primers D2A (5′-ACAAGTACCGTGAGGGAAAGTT-3′) and D3B (5′-TCGGAAGGAACCAGCTACTA-3′) (1). PCR products were purified and sequenced at the Macrogene sequencing facility service (Amsterdam, The Netherlands). Sequences were deposited in GenBank (KJ645427 to 33). The sequences were compared with previously published sequences in NCBI database and showed 96 to 100% sequence similarity with M. hapla accession nos. GQ130139, DQ328685, KF430798, and DQ145641. Unfortunately, comparison of sequences did not provide further information about the origin of this Ethiopian population, if it is native to Ethiopia or was imported with infected plant material. To the best of our knowledge, this is the first record of M. hapla occurring in Ethiopia. M. hapla is known as a serious pest of roses in colder climate regions. In Africa, it was previously reported from Tanzania (3) and South Africa (2). Thus, it appears that this species has now become also established in Ethiopia at higher altitudes (1,400 to 2,100 m above sea level) within the urban hinterland of Addis Ababa.

References: (1) Baldwin et al. Mol. Phy. Evol. 8:248, 1887. (2) J. H. O'Bannon. Institute Agri. Res. 29, 1975. (3) E. Onkendi and L. N. Moleleki. Eur. J. Pl. Pathol. 136:1, 2013. (4) A. G. Whitehead. Trans. Zool. Soc. Lon.31:263, 1968.
Plain faces are more expressive: comparative study of facial colour, mobility and musculature in primates
Authors: Santana Sharlene E. , Dobson Seth D. , Diogo Rui
Published: May 2014

Facial colour patterns and facial expressions are among the most important phenotypic traits that primates use during social interactions. While colour patterns provide information about the sender's identity, expressions can communicate its behavioural intentions. Extrinsic factors, including social group size, have shaped the evolution of facial coloration and mobility, but intrinsic relationships and trade-offs likely operate in their evolution as well. We hypothesize that complex facial colour patterning could reduce how salient facial expressions appear to a receiver, and thus species with highly expressive faces would have evolved uniformly coloured faces. We test this hypothesis through a phylogenetic comparative study, and explore the underlying morphological factors of facial mobility. Supporting our hypothesis, we find that species with highly expressive faces have plain facial colour patterns. The number of facial muscles does not predict facial mobility; instead, species that are larger and have a larger facial nucleus have more expressive faces. This highlights a potential trade-off between facial mobility and colour patterning in primates and reveals complex relationships between facial features during primate evolution.
A stochastic model for early placental development
Authors: Cotter Simon L. , Klika Václav , Kimpton Laura , Collins Sally , Heazell Alexander E. P.
Published: May 2014

In the human, placental structure is closely related to placental function and consequent pregnancy outcome. Studies have noted abnormal placental shape in small-for-gestational-age infants which extends to increased lifetime risk of cardiovascular disease. The origins and determinants of placental shape are incompletely understood and are difficult to studyin vivo. In this paper, we model the early development of the human placenta, based on the hypothesis that this is driven by a chemoattractant effect emanating from proximal spiral arteries in the decidua. We derive and explore a two-dimensional stochastic model, and investigate the effects of loss of spiral arteries in regions near to the cord insertion on the shape of the placenta. This model demonstrates that disruption of spiral arteries can exert profound effects on placental shape, particularly if this is close to the cord insertion. Thus, placental shape reflects the underlying maternal vascular bed. Abnormal placental shape may reflect an abnormal uterine environment, predisposing to pregnancy complications. Through statistical analysis of model placentas, we are able to characterize the probability that a given placenta grew in a disrupted environment, and even able to distinguish between different disruptions.
A brief history of Lord Rutherford's radium
Authors: Todd Neil
Published: May 2014

In this paper I give a brief summary of what is known about the acquisition, use and fate of the radium sources that were in the possession of Lord Rutherford during his lifetime. The account is written in two parts, corresponding to the periods from the discovery of radium in 1898 until his death in 1937 and then from 1937 until recent times. The history of Rutherford's radium closely shadows the history of radioactivity, the evolution of nuclear physics, the race for the bomb, and the development of the nuclear industry.
An extended finite-element model coupled with level set method for analysis of growth of corrosion pits in metallic structures
Authors: Vagbharathi A. S. , Gopalakrishnan S.
Published: May 2014

Mass balance between metal and electrolytic solution, separated by a moving interface, in stable pit growth results in a set of governing equations which are solved for concentration field and interface position (pit boundary evolution). The interface experiences a jump discontinuity in metal concentration. The extended finite-element model (XFEM) handles this jump discontinuity by using discontinuous-derivative enrichment formulation, eliminating the requirement of using front conforming mesh and re-meshing after each time step as in the conventional finite-element method. However, prior interface location is required so as to solve the governing equations for concentration field for which a numerical technique, the level set method, is used for tracking the interface explicitly and updating it over time. The level set method is chosen as it is independent of shape and location of the interface. Thus, a combined XFEM and level set method is developed in this paper. Numerical analysis for pitting corrosion of stainless steel 304 is presented. The above proposed model is validated by comparing the numerical results with experimental results, exact solutions and some other approximate solutions. An empirical model for pitting potential is also derived based on the finite-element results. Studies show that pitting profile depends on factors such as ion concentration, solution pH and temperature to a large extent. Studying the individual and combined effects of these factors on pitting potential is worth knowing, as pitting potential directly influences corrosion rate.
The chemical cue tetrabromopyrrole from a biofilm bacterium induces settlement of multiple Caribbean corals
Authors: Sneed Jennifer M. , Sharp Koty H. , Ritchie Kimberly B. , Paul Valerie J.
Published: May 2014

Microbial biofilms induce larval settlement for some invertebrates, including corals; however, the chemical cues involved have rarely been identified. Here, we demonstrate the role of microbial biofilms in inducing larval settlement with the Caribbean coral
Porites astreoides
and report the first instance of a chemical cue isolated from a marine biofilm bacterium that induces complete settlement (attachment and metamorphosis) of Caribbean coral larvae. Larvae settled in response to natural biofilms, and the response was eliminated when biofilms were treated with antibiotics. A similar settlement response was elicited by monospecific biofilms of a single bacterial strain,
Pseudoalteromonas
sp. PS5, isolated from the surface biofilm of a crustose coralline alga. The activity of
Pseudoalteromonas
sp. PS5 was attributed to the production of a single compound, tetrabromopyrrole (TBP), which has been shown previously to induce metamorphosis without attachment in Pacific acroporid corals. In addition to inducing settlement of brooded larvae (
P. astreoides
), TBP also induced larval settlement for two broadcast-spawning species,
Orbicella
(formerly
Montastraea
)
franksi
and
Acropora palmata
, indicating that this compound may have widespread importance among Caribbean coral species.
Genetic recombination variation in wild Robertsonian mice: on the role of chromosomal fusions andPrdm9allelic background
Authors: Capilla Laia , Medarde Nuria , Alemany-Schmidt Alexandra , Oliver-Bonet Maria , Ventura Jacint , Ruiz-Herrera Aurora
Published: May 2014

Despite the existence of formal models to explain how chromosomal rearrangements can be fixed in a population in the presence of gene flow, few empirical data are available regarding the mechanisms by which genome shuffling contributes to speciation, especially in mammals. In order to shed light on this intriguing evolutionary process, here we present a detailed empirical study that shows how Robertsonian (Rb) fusions alter the chromosomal distribution of recombination events during the formation of the germline in a Rb system of the western house mouse (Mus musculus domesticus). Our results indicate that both the total number of meiotic crossovers and the chromosomal distribution of recombination events are reduced in mice with Rb fusions and that this can be related to alterations in epigenetic signatures for heterochromatinization. Furthermore, we detected novel house mousePrdm9allelic variants in the Rb system. Remarkably, mean recombination rates were positively correlated with a decrease in the number of ZnF domains in thePrdm9gene. The suggestion that recombination can be modulated by both chromosomal reorganizations and genetic determinants that control the formation of double-stranded breaks during meiosis opens new avenues for understanding the role of recombination in chromosomal speciation.
A restatement of the natural science evidence base concerning neonicotinoid insecticides and insect pollinators
Authors: Godfray H. Charles J. , Blacquière Tjeerd , Field Linda M. , Hails Rosemary S. , Petrokofsky Gillian , Potts Simon G. , Raine Nigel E. , Vanbergen Adam J. , McLean Angela R.
Published: May 2014

There is evidence that in Europe and North America many species of pollinators are in decline, both in abundance and distribution. Although there is a long list of potential causes of this decline, there is concern that neonicotinoid insecticides, in particular through their use as seed treatments are, at least in part, responsible. This paper describes a project that set out to summarize the natural science evidence base relevant to neonicotinoid insecticides and insect pollinators in as policy-neutral terms as possible. A series of evidence statements are listed and categorized according to the nature of the underlying information. The evidence summary forms the appendix to this paper and an annotated bibliography is provided in the electronic supplementary material.
Hypoxia-inducible factor-1 mediates adaptive developmental plasticity of hypoxia tolerance in zebrafish,Danio rerio
Authors: Robertson Cayleih E. , Wright Patricia A. , Köblitz Louise , Bernier Nicholas J.
Published: May 2014

In recent years, natural and anthropogenic factors have increased aquatic hypoxia the world over. In most organisms, the cellular response to hypoxia is mediated by the master regulator hypoxia-inducible factor-1 (HIF-1). HIF-1 also plays a critical role in the normal development of the cardiovascular system of vertebrates. We tested the hypothesis that hypoxia exposures which resulted in HIF-1 induction during embryogenesis would be associated with enhanced hypoxia tolerance in subsequent developmental stages. We exposed zebrafish (Danio rerio) embryos to just 4 h of severe hypoxia or total anoxia at 18, 24 and 36 h post-fertilization (hpf). Of these, exposure to hypoxia at 24 and 36 hpf as well as anoxia at 36 hpf activated the HIF-1 cellular pathway. Zebrafish embryos that acutely upregulated the HIF-1 pathway had an increased hypoxia tolerance as larvae. The critical window for hypoxia sensitivity and HIF-1 signalling was 24 hpf. Adult male fish had a lower critical oxygen tension (Pcrit) compared with females. Early induction of HIF-1 correlated directly with an increased proportion of males in the population. We conclude that mounting a HIF-1 response during embryogenesis is associated with long-term impacts on the phenotype of later stages which could influence both individual hypoxia tolerance and population dynamics.
The repeated evolution of large seeds on islands
Authors: Kavanagh Patrick H. , Burns Kevin C.
Published: May 2014

Several plant traits are known to evolve in predictable ways on islands. For example, herbaceous species often evolve to become woody and species frequently evolve larger leaves, regardless of growth form. However, our understanding of how seed sizes might evolve on islands lags far behind other plant traits. Here, we conduct the first test for macroevolutionary patterns of seed size on islands. We tested for differences in seed size between 40 island–mainland taxonomic pairings from four island groups surrounding New Zealand. Seed size data were collected in the field and then augmented by published seed descriptions to produce a more comprehensive dataset. Seed sizes of insular plants were consistently larger than mainland relatives, even after accounting for differences in growth form, dispersal mode and evolutionary history. Selection may favour seed size increases on islands to reduce dispersibility, as long-distance dispersal may result in propagule mortality at sea. Alternatively, larger seeds tend to generate larger seedlings, which are more likely to establish and outcompete neighbours. Our results indicate there is a general tendency for the evolution of large seeds on islands, but the mechanisms responsible for this evolutionary pathway have yet to be fully resolved.
Analyses of evolutionary dynamics in viruses are hindered by a time-dependent bias in rate estimates
Authors: Duchêne Sebastián , Holmes Edward C. , Ho Simon Y. W.
Published: May 2014

Time-scales of viral evolution and emergence have been studied widely, but are often poorly understood. Molecular analyses of viral evolutionary time-scales generally rely on estimates of rates of nucleotide substitution, which vary by several orders of magnitude depending on the timeframe of measurement. We analysed data from all major groups of viruses and found a strong negative relationship between estimates of nucleotide substitution rate and evolutionary timescale. Strikingly, this relationship was upheld both within and among diverse groups of viruses. A detailed case study of primate lentiviruses revealed that the combined effects of sequence saturation and purifying selection can explain this time-dependent pattern of rate variation. Therefore, our analyses show that studies of evolutionary time-scales in viruses require a reconsideration of substitution rates as a dynamic, rather than as a static, feature of molecular evolution. Improved modelling of viral evolutionary rates has the potential to change our understanding of virus origins.
Microfinance through non-governmental organizations and its effects on formal and informal credit
Authors: Xiang Cheng , Jia Xiangping , Huang Jikun
Published: May 2014

Purpose

– Internationally, microfinance run by non-governmental organizations (NGOs) is often considered an important approach to meeting the credit demand of rural households, particularly among the poor. However, the perceived competitions with formal financial institutions and concerns about financial risks in the rural economy have impeded the development of microfinance by NGOs in China. Despite these concerns about NGO microfinance, little empirical evidence has been brought to prove them. The purpose of this paper is to provide empirical evidence of the relationship between NGO microfinance and farmers’ demand for formal and informal credit in rural China.

Design/methodology/approach

– The study is based on a household longitudinal data set consisting of 749 households from 40 microfinance villages in rural China. This study draws evidence from China's largest NGO microfinance. Out of the five county branches where China Foundation for Poverty Alleviation has launched institutionalized microfinance since 2006, the authors selected two of them. A random sampling approach was applied in surveying villages and households. In an effort to create impact assessments, the authors surveyed the detailed information on household characteristics and credit access during the period 2006-2009. A panel data is thus structured for the analysis.

Findings

– The authors found that the demand for credit in rural China is immense and rising, as formal financial institutions have gradually moved away from less developed regions in rural areas. In its place, informal lending has become a primary source of credit for the poor. However, where NGO microfinance has become available, both formal and informal credit has slowed down. The development and expansion of NGO microfinance did stand up as a substitution for institutional lenders and informal financial networks.

Research limitations/implications

– The findings have profound policy implications. First, since the development of NGO microfinance fill the demand for credit in rural China and poses low financial risk, the intellectual bias against NGO microfinance is unwarranted. In particular, the regulations that hamper the development of NGO microfinance should be corrected. Second, informal networks do not appear to be costless. Where NGO microfinance can substitute for them, it can mitigate the financial stresses related to the informal credit market.
Mismatch
Authors: Che Yi
Published: May 2014

Purpose

– The purpose of this paper is to evaluate the relative impacts of full-scale land reallocation (FLR) and partial-scale land reallocation (PLR) on household land rental behavior in rural China.

Design/methodology/approach

– Probit model, Tobit model and Semi-parametric model are used to provide empirical evidences.

Findings

– Drawing upon an unique farm survey in 2003, the authors find that in rural China, FLR is more likely to follow egalitarian rule and PLR takes productivity of households into consideration. Econometric analysis provides two main findings. First, FLR has positive effect on household land rental behavior, possibly because egalitarian FLR creates a mismatch between household agricultural ability and land size and after FLR households have to participate in land rental market to adjust the mismatch. Second, PLR has negative effect on household land rental behavior which supports that land reallocation and land rental market are substitutes (Brandt et al., 2004).

Originality/value

– The main contribution of this study is to show that FLR and PLR in rural China are motivated by two different rationales (i.e. FLR by egalitarian concerns and PLR by efficiency concerns).
Multi-level design of an isolation transformer using collaborative optimization
Authors: C. Berbecea Alexandru , Gillon Frédéric , Brochet Pascal
Published: May 2014

Purpose

– The purpose of this paper is to present an application of a multidisciplinary multi-level design optimization methodology for the optimal design of a complex device from the field of electrical engineering throughout discipline-based decomposition. The considered benchmark is a single-phase low voltage safety isolation transformer.

Design/methodology/approach

– The multidisciplinary optimization of a safety isolation transformer is addressed within this paper. The bi-level collaborative optimization (CO) strategy is employed to coordinate the optimization of the different disciplinary analytical models of the transformer (no-load and full-load electromagnetic models and thermal model). The results represent the joint decision of the three distinct disciplinary optimizers involved in the design process, under the coordination of the CO's master optimizer. In order to validate the proposed approach, the results are compared to those obtained using a classical single-level optimization method – sequential quadratic programming – carried out using a multidisciplinary feasible formulation for handling the evaluation of the coupling model of the transformer.

Findings

– Results show a good convergence of the CO process with the analytical modeling of the transformer, with a reduced number of coordination iterations. However, a relatively important number of disciplinary models evaluations were required by the local optimizers.

Originality/value

– The CO multi-level methodology represents a new approach in the field of electrical engineering. The advantage of this approach consists in that it integrates decisions from different teams of specialists within the optimal design process of complex systems and all exchanges are managed within a unique coordination process.