bluuebunny/crossref_metadata_2025 huggingface dataset:
CPW balun for printed balanced antennas
Authors: Sánchez A.M. , Ribó M. , Pradell L. , Anguera J. , Andújar A.
Published: May 2014

In coplanar waveguide (CPW) circuits, printed balanced antennas must be excited through baluns. These baluns often feature coplanar‐to‐slotline transitions that must be tuned and matched by electromagnetic optimisation, and may interfere with the antenna backward radiation. A new CPW balun for printed balanced antennas is presented and modelled. As its multimodal circuit model makes clear, it integrates an impedance‐matching network within its structure that can be analytically designed. The balun has been experimentally tested, exhibiting good agreement with its circuit model and a weak electromagnetic interaction with the antenna radiation.
Computational technique for probing terminal control mechanisms inside three‐dimensional nano‐scale MOSFET
Authors: Mir R.N. , Frensley W.R. , Shichijo S. , Blakey P.A.
Published: May 2014

A novel computational technique is presented to study the terminal influence inside the three‐dimensional (3D) nano‐scale metal‐oxide semiconductor field effect transistor (MOSFET) using TCAD simulations. Within the MOSFET the derivative of the electrostatic potential with respect to voltages at each terminal is taken, and when these derivatives are summed together they always sum to unity. It is found that these functions can be used to quantify the relative influence or control of the terminals anywhere inside the MOSFET, including the channel. The motivation for moving from planar MOSFETs to 3D‐MOSFETs is to increase the gate control over the channel. The terminal influence functions quantify the notion of control. To gain insight into the working of a semiconductor device, different quantities like potential, charge or current density etc. may be visualised. These quantities are available in the standard TCAD tool‐kit. However, these do not directly address the mechanism of terminal control. The terminal response or control functions can be used to do this very clearly.
Low‐cost fixed‐width squarer by using probability‐compensated circuit
Authors: Chen Yuan‐Ho
Published: May 2014

A simple and uniform compensated bias for a fixed‐width squarer is proposed. By employing the expected value of truncation parts, truncation errors can be efficiently alleviated. The proposed squarer derives a simple compensated bias and achieves a small area. The results show that the proposed squarer achieves low‐cost, high‐accuracy performance and yields higher values than previous designs do, particularly regarding the value of accuracy divided by the area–delay product.
Additively manufactured heterogeneous substrates for three‐dimensional control of local permittivity
Authors: Tribe J. , Whittow W.G. , Kay R.W. , Vardaxoglou J.C.
Published: May 2014

The concept of using additive manufacturing as a method to construct heterogeneous substrates from a single building material via stereolithography is introduced. The dynamic variation of air cavities within the bulk material is used to control the effective permittivity of the host medium. The digitally driven layer process enables full three‐dimensional variation of the local permittivity. The high resolution of stereolithography enables sub‐millimetre control of air inclusion features. Measurements of the effective permittivity with different air fractions have been compared to analytical results.
Transmission of data with orthogonal frequency division multiplexing technique for communication networks using GHz frequency band soliton carrier
Authors: Amiri I.S. , Ebrahimi M. , Yazdavar A.H. , Ghorbani S. , Alavi S.E. , Idrus S.M. , Ali J.
Published: May 2014

Microring resonators (MRRs) can be used to generate optical millimetre‐wave solitons with a broadband frequency of 40–60 GHz. Non‐linear light behaviours within MRRs, such as chaotic signals, can be used to generate logic codes (digital codes). The soliton signals can be multiplexed and modulated with the logic codes using an orthogonal frequency division multiplexing (OFDM) technique to transmit the data via a network system. OFDM uses overlapping subcarriers without causing inter‐carrier interference. It provides both a high data rate and symbol duration using frequency division multiplexing over multiple subcarriers within one channel. The results show that MRRs support both single‐carrier and multi‐carrier optical soliton pulses, which can be used in an OFDM based on whether fast Fourier transform or discrete wavelet transform transmission/receiver system. Localised ultra‐short soliton pulses within frequencies of 50 and 52 GHz can be seen at the throughput port of the panda system with respect to full‐width at half‐maximum (FWHM) and free spectrum range of 5 MHz and 2 GHz, respectively. The soliton pulses with FWHMs of 10 MHz could be generated at the drop port. Therefore, transmission of data information can be performed via a communication network using soliton pulse carriers and an OFDM technique.
Physical layer security by robust masked beamforming and protected zone optimisation
Authors: Romero‐Zurita Nabil , McLernon Desmond , Ghogho Mounir
Published: May 2014

The authors address the physical layer security in multiple‐input‐single‐output communication systems. This study introduces a robust strategy to cope with the channel state information errors in the main link to convey confidential information towards a legitimate receiver while artificial noise is broadcast to confuse an unknown eavesdropper. The authors study how an eavesdropper physically located in the vicinity of the transmitter can put at risk the network's security, and hence, as a countermeasure, a ‘protected zone’ was deployed to prevent the close‐quarters eavesdropping attacks. The authors determine the size of the protected zone and transmission covariance matrices of the steering information and the artificial noise to maximise the worst‐case secrecy rate in a resource‐constrained system and to minimise the use of resources to ensure an average secrecy rate. The proposed robust masked beamforming scheme offers a secure performance even with erroneous estimates of the main channel showing that a protected zone not only enhances the transmission security but it allows us to make an efficient use of energy by prioritising the available resources.
Concatenated coding and hybrid automatic repeat request for wiretap channels
Authors: Kim Sunghwan , Nguyen Giang Kien , Hoang Tiep Minh , Shin Hyundong
Published: May 2014

In this study, the authors propose an equivocation scheme for wiretap channels, which is composed of bit‐extension mapping, coset coding and hybrid automatic repeat request (HARQ). The inner bit‐extension code and outer coset code are used for equivocation of a wiretapper channel, whereas the HARQ scheme is to mitigate noisy errors in a main legitimate channel. These concatenated codes and HARQ are effective and practical for various channel conditions. The average equivocation and the probability of causing imperfect secrecy are analysed for finite codeword lengths. As a function of channel conditions, they investigate the block error rate at the legitimate receiver and the information leakage to the wiretapper. From simulation results, they further determine the minimum requirements of code design for some target values of the ‘residual’ block error rate and information leakage at maximum retransmission.
U‐shaped bow‐tie magneto‐electric dipole antenna with a modified horned reflector for ultra‐wideband applications
Authors: Feng Botao , Li Shufang , An Wenxing , Yin Sixing , Li Jingchun , Qiu Tianshuang
Published: May 2014

A novel U‐shaped bow‐tie magneto‐electric dipole unidirectional antenna with a dual‐layer horned reflector for ultra‐wideband (UWB) applications is proposed. To broaden impedance bandwidth, a U‐shaped bow‐tie electric dipole structure with two notch slots is presented. In addition, to reduce the size of the antenna and improve impedance matching, a new feeding structure designed with perforation and tapered line is introduced. Finally, a double‐layer horned reflector, instead of a ground plane, is employed to improve radiation patterns and gains for high‐rate data transmission. The prototype antenna can achieve a stable gain of 10 ± 1.2 dBi and an impedance bandwidth of 118% for standing wave ratio ≤ 2 from 2.81 to 10.92 GHz. To the best of the authors knowledge, it is the first U‐shaped bow‐tie magneto‐electric dipole unidirectional antenna for UWB applications. The proposed antenna, which possesses the advantages of UWB antenna and magneto‐electric dipole antenna simultaneously, can be easily fabricated with low cost. With these features, it is a practicable candidate for UWB communications.
Benzo‐cyclo‐butene bonding process with ‘stamp’ printing for wafer level package
Authors: Xia Wen , Li Lei , Deng Kangfa , Li Song , Su Weiguo , Zhang Wei
Published: May 2014

Presented is a novel process of benzo‐cyclo‐butene (BCB) bonding for a wafer level package with ‘stamp’ printing, in which the BCB structure is transferred and patterned by pressing the cap wafer towards another wafer with a liquid BCB layer. Compared with the conventional BCB bonding process, this new method not only avoids the residual polymer inside the cavity to extend the application of BCB bonding in the complex three‐dimensional structures but also raises the bonding strength because of the non‐treatment before bonding. The key process parameters, such as the auxiliary wafer material, pre‐curing time and bonding pressure were optimised after a series of contrast experiments. The bonding quality was evaluated qualitatively by manual separation and quantitatively by a tensile bonding test. This new method has a minimum bonding strength of 5.9 MPa, which is more than ten times the conventional one. Besides, the bonding yield reaches 80% in five groups of 4‐inch wafers. Finally, this process was successfully utilised in an acceleration microswitch.
Magneto-optical Kerr effect in L1 FePdPt ternary alloys: Experiments and first-principles calculations
Authors: Ma L. , Hu J. , Costa M. , Shi Z. , Li J. , Xu X. G. , Jiang Y. , Guo G. Y. , Wu R. Q. , Zhou S. M.
Published: May 2014

We have studied the magneto-optical Kerr effect (MOKE) of L10 Fe0.5(Pd1−xPtx)0.5 alloy films with both experiments and first-principles calculations. In the visible region, negative Kerr rotation and ellipticity peaks are, respectively, observed in the regions of 1.5–2.0 eV and 1.7–2.6 eV. These peaks are shifted towards higher energies, and their magnitudes are enhanced for larger x. The MOKE evolution is mainly ascribed to the anomalous Hall conductivity contributed by the spin-down d↓,x2−y2 bands from Pd and Pt. We established a close correlation among the MOKE spectra, the spin orbit coupling strength, and the band feature for this prototypical system.
The effects of temperature and vacancies on dynamics of crack in graphene sheet
Authors: Lohrasebi A. , Amini M. , Neek-Amal M.
Published: May 2014

Crack propagation in a defected graphene sheet is investigated at finite temperature using molecular dynamics simulation. The effects of several initial cracks, temperature and different percentage of vacancies are considered. It is found that i) the critical load, which is a criteria for crack propagation, is larger when the load is applied on the zigzag direction, ii) the critical load decreases with increasing temperature, iii) a hole in the center of the sheet and the presence of randomly distributed vacancies reduce the critical load giving different crack propagation trajectory. Our new results would help to understand the crack propagation phenomena in defected graphene at finite temperature.
Introducing thermally stable inter-tube defects to assist off-axial phonon transport in carbon nanotube films
Authors: Wang Jing , Chen Di , Wallace Joseph , Gigax Jonathan , Wang Xuemei , Shao Lin
Published: May 2014

Through integrated molecular dynamics (MD) simulations and experimental studies, we demonstrated the feasibility of an ion-irradiation-and-annealing based phonon engineering technique to enhance thermal conductivity of carbon nanotube (CNT) films. Upon ion irradiation of CNT films, both inter-tube defects and intra-tube defects are introduced. Our MD simulations show that inter-tube defects created between neighboring tubes are much more stable than intra-tube defects created on tube graphitic planes. Upon thermal annealing, intra-tube defects are preferentially removed but inter-tube defects stay. Consequently, axial phonon transport increases due to reduced phonon scattering and off-axial phonon transport is sustained due to the high stability of inter-tube defects, leading to a conductivity enhancement upon annealing. The modeling predictions agree with experimental observations that thermal conductivities of CNT films were enhanced after 2 MeV hydrogen ion irradiations and conductivities were further enhanced upon post irradiation annealing.
A second-generation constrained reaction volume shock tube
Authors: Campbell M. F. , Tulgestke A. M. , Davidson D. F. , Hanson R. K.
Published: May 2014

We have developed a shock tube that features a sliding gate valve in order to mechanically constrain the reactive test gas mixture to an area close to the shock tube endwall, separating it from a specially formulated non-reactive buffer gas mixture. This second-generation Constrained Reaction Volume (CRV) strategy enables near-constant-pressure shock tube test conditions for reactive experiments behind reflected shocks, thereby enabling improved modeling of the reactive flow field. Here we provide details of the design and operation of the new shock tube. In addition, we detail special buffer gas tailoring procedures, analyze the buffer/test gas interactions that occur on gate valve opening, and outline the size range of fuels that can be studied using the CRV technique in this facility. Finally, we present example low-temperature ignition delay time data to illustrate the CRV shock tube's performance.
Thermodynamics and structure of a two-dimensional electrolyte by integral equation theory
Authors: Aupic Jana , Urbic Tomaz
Published: May 2014

Monte Carlo simulations and integral equation theory were used to predict the thermodynamics and structure of a two-dimensional Coulomb fluid. We checked the possibility that integral equations reproduce Kosterlitz-Thouless and vapor-liquid phase transitions of the electrolyte and critical points. Integral equation theory results were compared to Monte Carlo data and the correctness of selected closure relations was assessed. Among selected closures hypernetted-chain approximation results matched computer simulation data best, but these equations unfortunately break down at temperatures well above the Kosterlitz-Thouless transition. The Kovalenko-Hirata closure produces results even at very low temperatures and densities, but no sign of phase transition was detected.
On the high Mach number shock structure singularity caused by overreach of Maxwellian molecules
Authors: Myong R. S.
Published: May 2014

The high Mach number shock structure singularity arising in moment equations of the Boltzmann equation was investigated. The source of the singularity is shown to be the unbalanced treatment between two high order kinematic and dissipation terms caused by the overreach of Maxwellian molecule assumption. In compressive gaseous flow, the high order stress-strain coupling term of quadratic nature will grow far faster than the strain term, resulting in an imbalance with the linear dissipation term and eventually a blow-up singularity in high thermal nonequilibrium. On the other hand, the singularity arising from unbalanced treatment does not occur in the case of velocity shear and expansion flows, since the high order effects are cancelled under the constraint of the free-molecular asymptotic behavior. As an alternative method to achieve the balanced treatment, Eu's generalized hydrodynamics, consistent with the second law of thermodynamics, was revisited. After introducing the canonical distribution function in exponential form and applying the cumulant expansion to the explicit calculation of the dissipation term, a natural platform suitable for the balanced treatment was derived. The resulting constitutive equation with the nonlinear factor was then shown to be well-posed for all regimes, effectively removing the high Mach number shock structure singularity.
Molecular modeling of vapor-deposited polymer glasses
Authors: Lin Po-Han , Lyubimov Ivan , Yu Lian , Ediger M. D. , de Pablo Juan J.
Published: May 2014

We have investigated the properties of vapor-deposited glasses prepared from short polymer chains using molecular dynamics simulations. Vapor-deposited polymer glasses are found to have higher density and higher kinetic stability than ordinary glasses prepared by gradual cooling of the corresponding equilibrium liquid. In contrast to results for binary Lennard-Jones glasses, the deposition rate is found to play an important role in the stability of polymer vapor-deposited glasses. Glasses deposited at the slowest deposition rate and at the optimal substrate temperature are found to correspond to the ordinary glasses that one could hypothetically prepare by cooling the liquid at rates that are 4–5 orders of magnitude slower than those accessible in the current simulations. For intermediate-length polymer chains, the resulting vapor-deposited glasses are found to be highly anisotropic. For short chains, however, the glasses are isotropic, showing that structural anisotropy is not a necessary condition for formation of stable glasses by physical vapor deposition.
Improved performance of HgCdTe infrared detector focal plane arrays by modulating light field based on photonic crystal structure
Authors: Liang Jian , Hu Weida , Ye Zhenhua , Liao Lei , Li Zhifeng , Chen Xiaoshuang , Lu Wei
Published: May 2014

An HgCdTe long-wavelength infrared focal plane array photodetector is proposed by modulating light distributions based on the photonic crystal. It is shown that a promising prospect of improving performance is better light harvest and dark current limitation. To optimize the photon field distributions of the HgCdTe-based photonic crystal structure, a numerical method is built by combining the finite-element modeling and the finite-difference time-domain simulation. The optical and electrical characteristics of designed HgCdTe mid-wavelength and long-wavelength photon-trapping infrared detector focal plane arrays are obtained numerically. The results indicate that the photon crystal structure, which is entirely compatible with the large infrared focal plane arrays, can significantly reduce the dark current without degrading the quantum efficiency compared to the regular mesa or planar structure.
Excitons in a mirror: Formation of “optical bilayers” using MoS2 monolayers on gold substrates
Authors: Mertens Jan , Shi Yumeng , Molina-Sánchez Alejandro , Wirtz Ludger , Yang Hui Ying , Baumberg Jeremy J.
Published: May 2014

We report coupling of excitons in monolayers of molybdenum disulphide to their mirror image in an underlying gold substrate. Excitons at the direct band gap are little affected by the substrate whereas strongly bound C-excitons associated with a van-Hove singularity change drastically. On quartz substrates only one C-exciton is visible (in the blue) but on gold substrates a strong red-shifted extra resonance in the green is seen. Exciton coupling to its image leads to formation of a “mirror biexciton” with enhanced binding energy. Estimates of this energy shift in an emitter-gold system match experiments well. The absorption spectrum of MoS2 on gold thus resembles a bilayer of MoS2 which has been created by optical coupling. Additional top-mirrors produce an “optical bulk.”
Domain switching of fatigued ferroelectric thin films
Authors: Tak Lim Yun , Yeog Son Jong , Shin Young-Han
Published: May 2014

We investigate the domain wall speed of a ferroelectric PbZr0.48Ti0.52O3 (PZT) thin film using an atomic force microscope incorporated with a mercury-probe system to control the degree of electrical fatigue. The depolarization field in the PZT thin film decreases with increasing the degree of electrical fatigue. We find that the wide-range activation field previously reported in ferroelectric domains result from the change of the depolarization field caused by the electrical fatigue. Domain wall speed exhibits universal behavior to the effective electric field (defined by an applied electric field minus the depolarization field), regardless of the degree of the electrical fatigue.
Ion motion in the wake driven by long particle bunches in plasmas
Authors: Vieira J. , Fonseca R. A. , Mori W. B. , Silva L. O.
Published: May 2014

We explore the role of the background plasma ion motion in self-modulated plasma wakefield accelerators. We employ Dawson's plasma sheet model to derive expressions for the transverse plasma electric field and ponderomotive force in the narrow bunch limit. We use these results to determine the on-set of the ion dynamics and demonstrate that the ion motion could occur in self-modulated plasma wakefield accelerators. Simulations show the motion of the plasma ions can lead to the early suppression of the self-modulation instability and of the accelerating fields. The background plasma ion motion can nevertheless be fully mitigated by using plasmas with heavier plasmas.
Theoretical study of head-on collision of dust acoustic solitary waves in a strongly coupled complex plasma
Authors: Jaiswal S. , Bandyopadhyay P. , Sen A.
Published: May 2014

We investigate the propagation characteristics of two counter propagating dust acoustic solitary waves (DASWs) undergoing a head-on collision, in the presence of strong coupling between micron sized charged dust particles in a complex plasma. A coupled set of nonlinear dynamical equations describing the evolution of the two DASWs using the extended Poincaré-Lighthill-Kuo perturbation technique is derived. The nature and extent of post collision phase-shifts of these solitary waves are studied over a wide range of dusty plasma parameters in a strongly and a weakly coupled medium. We find a significant change in the nature and amount of phase delay in the strongly coupled regime as compared to a weakly coupled regime. The phase shift is seen to change its sign beyond a threshold value of compressibility of the medium for a given set of dusty plasma parameters.
Indium arsenide nanowire field-effect transistors for pH and biological sensing
Authors: Upadhyay S. , Frederiksen R. , Lloret N. , De Vico L. , Krogstrup P. , Jensen J. H. , Martinez K. L. , Nygård J.
Published: May 2014

Indium Arsenide is a high mobility semiconductor with a surface electron accumulation layer that allows ohmic electrical contact to metals. Here, we present nanowire devices based on this material as a platform for chemical and biological sensing. The sensing principle involves the binding of a charged species at the sensor surface transduced via field effect into a change in current flowing through the sensor. We show the sensitivity of the platform to the H+ ion concentration in solution as proof of principle and demonstrate the sensitivity to larger charged protein species. The sensors are highly reproducible and reach a detection limit of 10 pM for Avidin.
Radiation effects on bifurcation and dual solutions in transient natural convection in a horizontal annulus
Authors: Luo Kang , Yi Hong-Liang , Tan He-Ping
Published: May 2014

Transitions and bifurcations of transient natural convection in a horizontal annulus with radiatively participating medium are numerically investigated using the coupled lattice Boltzmann and direct collocation meshless (LB-DCM) method. As a hybrid approach based on a common multi-scale Boltzmann-type model, the LB-DCM scheme is easy to implement and has an excellent flexibility in dealing with the irregular geometries. Separate particle distribution functions in the LBM are used to calculate the density field, the velocity field and the thermal field. In the radiatively participating medium, the contribution of thermal radiation to natural convection must be taken into account, and it is considered as a radiative term in the energy equation that is solved by the meshless method with moving least-squares (MLS) approximation. The occurrence of various instabilities and bifurcative phenomena is analyzed for different Rayleigh number Ra and Prandtl number Pr with and without radiation. Then, bifurcation diagrams and dual solutions are presented for relevant radiative parameters, such as convection-radiation parameter Rc and optical thickness τ. Numerical results show that the presence of volumetric radiation changes the static temperature gradient of the fluid, and generally results in an increase in the flow critical value. Besides, the existence and development of dual solutions of transient convection in the presence of radiation are greatly affected by radiative parameters. Finally, the advantage of LB-DCM combination is discussed, and the potential benefits of applying the LB-DCM method to multi-field coupling problems are demonstrated.
A system for trapping barium ions in a microfabricated surface trap
Authors: Graham R. D. , Chen S.-P. , Sakrejda T. , Wright J. , Zhou Z. , Blinov B. B.
Published: May 2014

We have developed a vacuum chamber and control system for rapid testing of microfabricated surface ion traps. Our system is modular in design and is based on an in-vacuum printed circuit board with integrated filters. We have used this system to successfully trap and cool barium ions and have achieved ion ‘dark' lifetimes of 31.6 s ± 3.4 s with controlled shuttling of ions. We provide a detailed description of the ion trap system including the in-vacuum materials used, control electronics and neutral atom source. We discuss the challenges presented in achieving a system which can work reliably over two years of operations in which the trap under test was changed at least 10 times.
Use of Ethyl (Benzothiazol-2-ylsulfonyl)acetate for Malonic Ester-type Syntheses of Carboxylic Acids and Esters
Authors: Hussein Waleed M. , McGeary Ross P.
Published: May 2014

A new methodology for the synthesis of substituted carboxylic acids is described. Alkylation of either ethyl (benzothiazol-2-ylsulfonyl)acetate or ethyl 2-(benzothiazol-2-ylsulfonyl)propionate was achieved with alkyl halides and 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) in dichloromethane solution. These products were then desulfinated and hydrolysed in one-pot under mild conditions to give substituted acetic acids in good-to-excellent yields.
The Preparation of Macrocyclic Calpain Inhibitors by Ring Closing Metathesis and Cross Metathesis
Authors: Jones Seth A. , Duncan Joanna , Aitken Steven G. , Coxon James M. , Abell Andrew D.
Published: May 2014

Ring closing metathesis and cross metathesis approaches to a new macrocyclic peptidomimetic aldehyde 2 have been developed, with the former route being the most convenient. Aldehyde 2 is a potent inhibitor of calpain II (IC50 of 45 nM) with comparable activity to the benchmark acyclic inhibitor SJA6017 4. Both compounds contain an N-terminal 4-fluorophenylsulfonyl group. The P2 Ile analogue of 2 (16) is significantly less active (IC50 of 2000 nM) which reflects an unusually subtle importance of the P2 residue for active site binding.
Common beans, biodiversity, and multiple stresses: challenges of drought resistance in tropical soils
Authors: Beebe Stephen E. , Rao Idupulapati M. , Devi Mura Jyostna , Polania José
Published: May 2014

Common bean (Phaseolus vulgaris L.) is the grain legume with the highest volume of direct human consumption in the world, and is the most important legume throughout Eastern and Southern Africa, cultivated over an area of ~4 million ha. In Sub-Saharan Africa (SSA) drought is the most important production risk, potentially affecting as much as one-third of the production area. Both terminal and intermittent drought prevail in different production regions. The Pan-African Bean Research Alliance (PABRA), coordinated by the International Center for Tropical Agriculture (CIAT by its Spanish acronym), has participated in projects for both strategic and applied research to address drought limitations, with research sites in six SSA countries. Bean originated in the mid-altitude neo-tropics, and by its nature is not well adapted to warm, dry climates. Efforts at genetic improvement of drought resistance have a long history, exploiting variability among races of common bean, as well as through interspecific crosses. Useful traits are found both in roots and in shoots. Many authors have stressed the importance of harvest index and related parameters to sustain yield of common bean under drought stress, and our field studies substantiate this. Additionally, in tropical environments, soil-related constraints can seriously limit the potential expression of drought resistance, and it is especially important to address multiple stress factors to confront drought effectively in farmers’ fields. Poor soil fertility is widespread in the tropics and constrains root and shoot growth, thus limiting access to soil moisture. Phosphorus and nitrogen deficiencies are especially common, but are not the only limiting soil factors. Soil acidity and accompanying aluminium toxicity limit root development and inhibit access to moisture in lower soil strata. Soil physical structure can also limit root development in some soils, as can poor soil management that leads to compaction. We review efforts to address each of these constraints through genetic means in combination with drought resistance per se.
Selenium biofortification in bread-making wheat under Mediterranean conditions: influence on grain yield and quality parameters
Authors: Poblaciones Maria J. , Santamaría Oscar , García-White Teodoro , Rodrigo Sara M.
Published: May 2014

The diet of millions of people around the world is deficient in selenium (Se). Bread-making wheat has been successfully used in Se biofortification programs under temperate climate to remedy Se deficiency. However, its suitability under Mediterranean conditions and its effect on the grain yield and quality parameters are not well known. In a wheat field in south-western Spain, two foliar Se fertilisers (sodium selenate and sodium selenite) were applied at four application rates (0, 10, 20, 40 g ha–1) in 2010–11 and 2011–12. Results showed a strong and linear relationship between total Se in grain and Se dose for both fertilisers, although selenate was much more efficient. A dose of 10 g sodium selenate ha–1 was able to increase significantly the Se in grain to close to the recommended values, although Se loss of 28% during the milling process might be expected. Grain yield was not negatively affected by fertilisation, but grain protein and dry gluten were slightly negatively affected, but only in the dry year. Alveograph parameters were either not affected or slightly favoured by Se fertilisation in any studied year. Bread-making wheat is a good candidate to be included in biofortification programs under semi-arid Mediterranean conditions.
Use of proximal sensors to evaluate at the sub-paddock scale a pasture growth-rate model based on light-use efficiency
Authors: Rahman M. M. , Lamb D. W. , Stanley J. N. , Trotter M. G.
Published: May 2014

Monitoring pasture growth rate is an important component of managing grazing livestock production systems. In this study, we demonstrate that a pasture growth rate (PGR) model, initially designed for NOAA AVHRR normalised difference vegetation index (NDVI) and since adapted to MODIS NDVI, can provide PGR at spatial resolution of ~2 m with an accuracy of ~2 kg DM/ha.day when incorporating in-situ sensor data. A PGR model based on light-use efficiency (LUE) was combined with in-situ measurements from proximal weather (temperature), plant (fraction of absorbed photosynthetically active radiation, fAPAR) and soil (relative moisture) sensors to calculate the growth rate of a tall fescue pasture. Based on an initial estimate of LUEmax for the candidate pasture, followed by a process of iterating LUEmax to reduce prediction errors, the model was capable of estimating PGR with a root mean square error of 1.68 kg/ha.day (R2 = 0.96, P-value ≈ 0). The iterative process proved to be a convenient means of estimating LUE of this pasture (1.59 g DM/MJ APAR) under local conditions. The application of the LUE-PGR approach to developing an in-situ pasture growth rate monitoring system is discussed.
The herpetofauna of Kioloa, New South Wales: baseline observational data collected 30 years ago and inspired by R. E. Barwick
Authors: Henle Klaus , Osborne Will , Lemckert Frank
Published: May 2014

There is increasing concern about the global decline of amphibians and reptiles. One problem with documenting declines and identifying underlying causes is the absence of historical data to compare to current data. Here we provide historic data for Kioloa on the south-eastern coast of New South Wales. In this region considerable clearing of natural forest and woodland and creation of farmland ponds took place during the second half of the 20th century. The Australian National University has a field station at Kioloa and R.E. Barwick introduced us to the field station and what was known of the herpetofauna in the mid-1980s. We undertook detailed observational surveys of the herpetofauna at this time and we revisited the area at other times, focusing on the coastal habitats. We found 13 species of frogs and 11 species of reptiles. Three further frog species and one reptile species known to occur in the area in the 1980s were not detected by us. More recently, one further frog species and six reptile species were added to the list, raising the total to 17 frog and 18 reptile species. The number and composition was similar to other locations of coastal New South Wales, except for some of the rarely encountered species. No strictly forest-dependent species were observed in the partially cleared survey area and such species presumably had already disappeared from these areas already before we commenced our observations. The frog Pseudophryne bibronii was still common in tall open-forest but was uncommon in partially cleared areas. Six species of frogs and one species of reptile presumably benefited from the anthropogenic habitat modifications. No declines of common species of reptiles occurred between the mid-1980s and 1993 but all species of frogs were very rare in 1993 due to very dry conditions. Litoria aurea, a threatened species of frog that was widespread in the mid-1980s, survives (2012) only at one site in the area.
Interactions between chromosomal and nonchromosomal elements reveal missing heritability
Authors: Edwards Matthew D. , Symbor-Nagrabska Anna , Dollard Lindsey , Gifford David K. , Fink Gerald R.
Published: May 2014

Significance

We show that the phenotype of an organism can be affected both by chromosomal and nonchromosomal information. The influence of the cytoplasmic, nonchromosomal information can have a profound effect on the phenotype and can be great enough to mask the effect of a chromosomal mutation. Our ability to quantify the contribution of this cytoplasmic component shows that it could comprise a significant portion of the “missing heritability.” In addition, our findings highlight the possibility of mitochondrial/nuclear incompatibility, which could be an important consideration in evaluating the feasibility of mitochondrial replacement therapy in humans.
Derhoticisation in Scottish English
Authors: Stuart-Smith Jane , Lawson Eleanor , Scobbie James M.
Published: May 2014

This paper presents the rewards of a sociophonetic journey by focusing on fine-grained variation in Scottish English coda /r/. We synthesize the results of some 15 years of research and provide a sociophonological account of variation and change in this feature. We summarize observations on coda /r/ in Scottish English across the twentieth century, which reveal a socially-constrained, long-term process of derhoticisation in working-class speech, alongside strengthening of /r/ in middle-class speakers. We then consider the linguistic and social factors involved, information from studies based on listener responses, the acoustics of derhoticisation, and insights gained from a socio-articulatory ultrasound corpus collected. These different views of coda /r/ force us to consider carefully the complex relationships between auditory, acoustic, and articulatory descriptions of (socially structured) speech. We conclude by discussing the implications of our results for mental representations of speech and social information for speaker-hearers in this community.
New parameters for the sociophonetic indexes
Authors: Marotta Giovanna
Published: May 2014

A sociophonetic analysis of the main phonological processes occurring in Tuscan Italian is presented within a global proposal of a new, original set of parameters of variation. After a general discussion on the sociophonetic indexes and the illustration of phonological processes occurring in the local pronunciation of Italian, the parameters of the new model are metaphorically identified as properties of solids, i.e. shape, size, thickness and weight. In the last section of the paper, the sociophonetic parameters proposed are compared with the socially-marked variables proposed by Labov (2001), showing analogies and differences. The advantages derivable from the model proposed are finally discussed, with the explicit acknowledgement of the need for the inspection of the phonological system in sociophonetic analysis.
An estimate for the Green’s function
Authors: Solynin Alexander
Published: May 2014

Let

K
K

be a continuum on

C

{\mathbb {C}}

and let

g

Ω
(
K
)

(
z
,
∞
)

g_{\Omega (K)}(z,\infty )

be the Green’s function of

Ω
(
K
)
=

C

¯

∖
K

\Omega (K)=\overline {{\mathbb {C}}}\setminus K

. In a recent paper, V. Totik proved that

g

Ω
(
K
)

(

z
0

,
∞
)

g_{\Omega (K)}(z_0,\infty )

≤
C

d
i
s
t
(

z
0

,
∞

)

1

/

2

\le C\,dist(z_0,\infty )^{1/2}

with some non-sharp constant

C
C

depending only on the diameter of

K
K

. He also used this inequality to prove new results on polynomial approximation in

C

\mathbb {C}

. In this note we prove a sharp version of Totik’s inequality and discuss a conjectural sharp lower bound for

g

Ω
(
K
)

(

z
0

,
∞
)

g_{\Omega (K)}(z_0,\infty )

.
SNPsea: an algorithm to identify cell types, tissues and pathways affected by risk loci
Authors: Slowikowski Kamil , Hu Xinli , Raychaudhuri Soumya
Published: May 2014

Summary: We created a fast, robust and general C++ implementation of a single-nucleotide polymorphism (SNP) set enrichment algorithm to identify cell types, tissues and pathways affected by risk loci. It tests trait-associated genomic loci for enrichment of specificity to conditions (cell types, tissues and pathways). We use a non-parametric statistical approach to compute empirical P-values by comparison with null SNP sets. As a proof of concept, we present novel applications of our method to four sets of genome-wide significant SNPs associated with red blood cell count, multiple sclerosis, celiac disease and HDL cholesterol.

Availability and implementation:  http://broadinstitute.org/mpg/snpsea

Contact:  soumya@broadinstitute.org

Supplementary information:  Supplementary Data are available at Bioinformatics online.
Exploring protein domain organization by recognition of secondary structure packing interfaces
Authors: Deng Lizong , Wu Aiping , Dai Wentao , Song Tingrui , Cui Ya , Jiang Taijiao
Published: May 2014

Motivation: Protein domains are fundamental units of protein structure, function and evolution; thus, it is critical to gain a deep understanding of protein domain organization. Previous works have attempted to identify key residues involved in organization of domain architecture. Because one of the most important characteristics of domain architecture is the arrangement of secondary structure elements (SSEs), here we present a picture of domain organization through an integrated consideration of SSE arrangements and residue contact networks.

Results: In this work, by representing SSEs as main-chain scaffolds and side-chain interfaces and through construction of residue contact networks, we have identified the SSE interfaces well packed within protein domains as SSE packing clusters. In total, 17 334 SSE packing clusters were recognized from 9015 Structural Classification of Proteins domains of <40% sequence identity. The similar SSE packing clusters were observed not only among domains of the same folds, but also among domains of different folds, indicating their roles as common scaffolds for organization of protein domains. Further analysis of 14 small single-domain proteins reveals a high correlation between the SSE packing clusters and the folding nuclei. Consistent with their important roles in domain organization, SSE packing clusters were found to be more conserved than other regions within the same proteins.

Contact:  taijiao@moon.ibp.ac.cn

Supplementary information:  Supplementary Data are available at Bioinformatics online.
PyCorrFit—generic data evaluation for fluorescence correlation spectroscopy
Authors: Müller Paul , Schwille Petra , Weidemann Thomas
Published: May 2014

Summary: We present a graphical user interface (PyCorrFit) for the fitting of theoretical model functions to experimental data obtained by fluorescence correlation spectroscopy (FCS). The program supports many data file formats and features a set of tools specialized in FCS data evaluation.

Availability and implementation: The Python source code is freely available for download from the PyCorrFit web page at http://pycorrfit.craban.de. We offer binaries for Ubuntu Linux, Mac OS X and Microsoft Windows.

Contact:  paul.mueller@biotec.tu-dresden.de and weidemann@biochem.mpg.de
Universal dynamical properties preclude standard clustering in a large class of biochemical data
Authors: Gomez Florian , Stoop Ralph L. , Stoop Ruedi
Published: May 2014

Motivation: Clustering of chemical and biochemical data based on observed features is a central cognitive step in the analysis of chemical substances, in particular in combinatorial chemistry, or of complex biochemical reaction networks. Often, for reasons unknown to the researcher, this step produces disappointing results. Once the sources of the problem are known, improved clustering methods might revitalize the statistical approach of compound and reaction search and analysis. Here, we present a generic mechanism that may be at the origin of many clustering difficulties.

Results: The variety of dynamical behaviors that can be exhibited by complex biochemical reactions on variation of the system parameters are fundamental system fingerprints. In parameter space, shrimp-like or swallow-tail structures separate parameter sets that lead to stable periodic dynamical behavior from those leading to irregular behavior. We work out the genericity of this phenomenon and demonstrate novel examples for their occurrence in realistic models of biophysics. Although we elucidate the phenomenon by considering the emergence of periodicity in dependence on system parameters in a low-dimensional parameter space, the conclusions from our simple setting are shown to continue to be valid for features in a higher-dimensional feature space, as long as the feature-generating mechanism is not too extreme and the dimension of this space is not too high compared with the amount of available data.

Availability and implementation: For online versions of super-paramagnetic clustering see http://stoop.ini.uzh.ch/research/clustering.

Contact:  ruedi@ini.phys.ethz.ch

Supplementary information:  Supplementary Data are available at Bioinformatics online.
Adaptation Strategies of Multinational Corporations, State-Owned Enterprises, and Domestic Business Groups to Economic and Political Transitions: A Network Analysis of the Chilean Telecommunications Sector, 1958–2005
Authors: Bucheli Marcelo , Salvaj Erica
Published: May 2014

This paper compares the corporate network strategies between multinational corporations of two different origins (United States and Spain), business groups, and state-owned enterprises in the public utility sector of a developing country going through economic and political transitions. The transitions we consider are from an import substitution industrialization model to an open market economy and from a democratic regime to a dictatorial one and back to democracy. We analyze the Chilean telecommunications sector between 1958 and 2005 and find that during a democratic regime all firms sought to build more networks with each other, while incentives decrease under an authoritarian regime. In the protectionist era, US investors built links with Chile’s corporate elite, while in times of an open economy, Spanish investors built these links with the government. State-owned corporations did not attempt to build links with other actors at any time, and business groups sought to build most networks among members of the group. Our findings challenge two commonly held assumptions: first, that open economies decrease incentives for domestic actors to build links with each other and, second, that close political regimes increase incentives to build networks among economic actors.
Active vs. Passive Decisions and Crowd-Out in Retirement Savings Accounts: Evidence from Denmark
*
Authors: Chetty Raj , Friedman John N. , Leth-Petersen Søren , Nielsen Torben Heien , Olsen Tore
Published: May 2014

Using 41 million observations on savings for the population of Denmark, we show that the effects of retirement savings policies on wealth accumulation depend on whether they change savings rates by active or passive choice. Subsidies for retirement accounts, which rely on individuals to take an action to raise savings, primarily induce individuals to shift assets from taxable accounts to retirement accounts. We estimate that each $1 of government expenditure on subsidies increases total saving by only 1 cent. In contrast, policies that raise retirement contributions if individuals take no action—such as automatic employer contributions to retirement accounts—increase wealth accumulation substantially. We estimate that approximately 15% of individuals are “active savers” who respond to tax subsidies primarily by shifting assets across accounts; 85% of individuals are “passive savers” who are unresponsive to subsidies but are instead heavily influenced by automatic contributions made on their behalf. Active savers tend to be wealthier and more financially sophisticated. We conclude that automatic contributions are more effective at increasing savings rates than subsidies for three reasons: (i) subsidies induce relatively few individuals to respond, (ii) they generate substantial crowd-out conditional on response, and (iii) they do not increase the savings of passive individuals, who are least prepared for retirement.
The Life Cycle of Plants in India and Mexico *
Authors: Hsieh Chang-Tai , Klenow Peter J.
Published: May 2014

In the United States, the average 40-year-old plant employs more than seven times as many workers as the typical plant 5 years or younger. In contrast, surviving plants in India and Mexico exhibit much slower growth, roughly doubling in size over the same age range. The divergence in plant dynamics suggests lower investments by Indian and Mexican plants in process efficiency, quality, and in accessing markets at home and abroad. In simple general equilibrium models, we find that the difference in life cycle dynamics could lower aggregate manufacturing productivity on the order of 25 percent in India and Mexico relative to the United States.