bluuebunny/crossref_metadata_2025 huggingface dataset:
White matter integrity in alcohol-naive youth with a family history of alcohol use disorders
Authors: Squeglia L. M. , Jacobus J. , Brumback T. , Meloy M. J. , Tapert S. F.
Published: March 2014

Background

Understanding pre-existing neural vulnerabilities found in youth who are family history positive (FHP) for alcohol use disorders could help inform preventative interventions created to delay initiation age and escalation of heavy drinking. The goal of this study was to compare indices of white matter integrity using diffusion tensor imaging (DTI) between FHP and family history negative (FHN) youth using a sample of 94 alcohol-naive adolescents and to examine if differences were associated with global and domain-specific cognitive functioning.

Method

Participants were 48 FHP and 46 FHN demographically matched, healthy, substance-naive 12- to 14-year-olds (54% female) recruited from local middle schools. Participants completed a neuropsychological test battery and magnetic resonance imaging session, including DTI.

Results

FHP youth had higher fractional anisotropy and axial diffusivity, and lower radial and mean diffusivity, than FHN youth in 19 clusters spanning projection, association and interhemispheric white matter tracts. Findings were replicated after controlling for age, gender, socio-economic status, grade and pubertal development. Groups did not differ significantly on global or domain-specific neuropsychological test scores.

Conclusions

FHP teens showed higher white matter integrity, but similar cognitive functioning, to FHN youth. More mature neural features could be related to more precocious behaviors, such as substance use initiation, in FHP youth. Future research exploring white matter maturation before and after substance use initiation will help elucidate the neurodevelopmental trajectories in youth at risk for substance use disorders, to inform preventive efforts and better understand the sequelae of adolescent alcohol and drug use.
Long-term mortality of persons with severe mental illness and diabetes: a population-based cohort study in Denmark
Authors: Ribe A. R. , Laursen T. M. , Sandbaek A. , Charles M. , Nordentoft M. , Vestergaard M.
Published: March 2014

Background

Persons with severe mental illness (SMI) have excess mortality, which may partly be explained by their high prevalence of diabetes.

Method

We compared the overall and cause-specific mortality in persons with SMI and diabetes with that of the general Danish population between 1997 and 2009 by linking data from Danish national registries.

Results

The cohort counted 4 734 703 persons, and during follow-up 651 080 persons died of whom 1083 persons had SMI and diabetes. Compared with the background population, the overall mortality rate ratios (MRRs) for persons with SMI and diabetes were 4.14 [95% confidence interval (CI) 3.81–4.51] for men and 3.13 (95% CI 2.88–3.40) for women. The cause-specific MRRs for persons with SMI and diabetes were lowest for malignant neoplasms (women: MRR = 1.98, 95% CI 1.64–2.39; men: MRR = 2.08, 95% CI 1.69–2.56) and highest for unnatural causes of death (women: MRR = 12.31, 95% CI 6.80–22.28; men: MRR = 7.89, 95% CI 5.51–11.29). The cumulative risks of death within 7 years of diabetes diagnosis for persons with SMI and diabetes were 15.0% (95% CI 12.4–17.6%) for those younger than 50 years, 30.7% (95% CI 27.8–33.4%) for those aged 50–69 years, and 63.8% (95% CI 58.9–68.2%) for those aged 70 years or older. Among persons suffering from both diseases, 33.4% of natural deaths were attributed to diabetes and 14% of natural deaths were attributed to the interaction between diabetes and SMI.

Conclusions

Long-term mortality is high for persons with SMI and diabetes. This calls for effective intervention from a coordinated and collaborating healthcare system.
Migrant Labor and Global Commons: Transnational Subjects, Visions, and Methods
Authors: Peck Gunther
Published: March 2014

Despite the prominence of both migrant workers and “global commons” as protagonists in recent meetings of the World Social Forum, few activists or scholars have successfully linked their historical agency or significance. In the following essay, I locate conceptual starting points for linking migrant workers and global commons by analyzing the work of the transnational and the commons in political conversation at the WSF and in the historiographies of immigration and the environment in North America. I argue that the transnational and global commons are best understood as analytical vantages rather than as utopian visions of nation-state transcendence. Using research into the history of human trafficking, I explore the analytical advantages of linking migrant workers to global commons. As inevitable trespassers of both national sovereignty and property claims, migrant workers' journeys help reveal a global commons that is, like them, migratory, fleeting, and often illegible to the state authorities. Such commons are not pristine wildernesses, but polyglots of weedy hybrids. Migrant workers' transnational vantages illuminate the limits of enclosure and the enduring adaptability of nonhuman nature across national boundaries.
Trafficking Nature and Labor Across Borders: The Transnational Return of US Environmental History
Authors: Sackman Douglas
Published: March 2014

Nogales is the shared name of two towns in North America that have grown up in the Sonoran desert; they are separated and united by the international border between the United States and Mexico. Until the early twentieth century, people who frequented Brickwood's Saloon in Nogales, Arizona would literally be standing on the border if they moved close to its south wall (it had to be knocked out to make room for a border marker put up in 1894). A lot of alcohol flowed north over the borderline at Nogales during prohibition. Much illicit traffic in people and goods continues to flow through Ambos Nogales (as the two towns are collectively known). Yet there is also a tremendous amount of licit traffic that goes through America's Port of Entry at Nogales—$2.5 billion worth of fresh produce—tomatoes, cucumbers, melons, peppers, eggplant, mangoes and more, much of it organically grown. These goods came over the border in Mexican trucks in 2011, supplying a healthy dose of fruits and vegetables to American consumers in the winter months. Meanwhile, Mexican workers from places like Oaxaca make a perilous passage through the desert to enter the United States, heading to fields and groves in California or Georgia or Washington or countless other places to harvest fruits and vegetables for Americans or perform other work vital to the so-called American way of life. Over 6,000 migrants, lost or left behind by coyotes, have perished of dehydration in the crossing in the last decade trying to make it to America's fields and other opportunities for work, as other less environmentally punishing border zones in California and Texas have been hardened with walls and intensive surveillance regimes.
A study of teacher confidence in teaching music within the context of the introduction of the Foundation Phase (3–7 years) statutory Education Programme in Wales
Authors: Baldwin Lara , Beauchamp Gary
Published: March 2014

This paper examines teacher confidence in teaching music within the context of the introduction of a Foundation Phase ‘curriculum’ in Wales for pupils aged 3–7 years. This involved a move away from music as a single subject to being part of creative development. The findings are based on a small-scale study of 12 teachers from four primary schools in south Wales. The findings illustrate that teacher confidence has improved since the Foundation Phase was introduced. The language used in the new documentation was a contributory factor as teachers found it more straightforward to understand what they were expected to do, and being able to combine music with other topics made it easier and more enjoyable to teach music. As a result, music (both indoors and outdoors) is a more regular occurrence and has become liberated from its perceived single subject status with the associated confidence issues.
A NOTE ON VARIABLE CAPITAL UTILIZATION IN GROWTH AND BUSINESS CYCLE THEORY
Authors: Strulik Holger , Trimborn Timo
Published: March 2014

It was always considered to be a major achievement of modern business cycle economics that it was solidly grounded in neoclassical growth theory. Preserving this joint foundation, however, imposes a discipline on the specification of models with variable capital utilization. In this note we show that conventional specifications of the depreciation cost of capital utilization and the labor supply elasticity, introduced into business cycle theory to generate a satisfactory amplification of shocks, entail counterfactual growth dynamics: the positive association between capital stock and GDP along the growth path turns negative. Across economies with access to the same technology, the economy with the lowest capital stock per capita is predicted to produce the highest output per capita. We compute lower and upper bounds for the involved elasticities between which these counterfactual dynamics are avoided.
High quality InP nanopyramidal frusta on Si
Authors: Metaferia Wondwosen , Dev Apurba , Kataria Himanshu , Junesand Carl , Sun Yan-Ting , Anand Srinivasan , Tommila Juha , Pozina Galia , Hultman Lars , Guina Mircea , Niemi Tapio , Lourdudoss Sebastian
Published: March 2014

Octagonal nanopyramidal InP frusta grown selectively on silicon.
Solvothermal synthesis of orthorhombic Sb2WO6 hierarchical structures and their visible-light-driven photocatalytic activity
Authors: Hu Sheng-Peng , Xu Cheng-Yan , Ma Fei-Xiang , Cao Lei , Zhen Liang
Published: March 2014

Doughnut-like, concave hierarchical structures of orthorhombic Sb2WO6 were firstly prepared and were found to exhibit excellent visible-light-driven photocatalytic performance.
Pressure-induced hydrogen transfer and polymerization in crystalline furoxan
Authors: Wu Qiong , Zhu Weihua , Xiao Heming
Published: March 2014

Under compression, furoxan (S1) transforms to S2, then forms S3 with chair conformation, and finally becomes S4 with a trans-conformation.
Biodiesel production, characterization, engine performance, and emission characteristics of Malaysian Alexandrian laurel oil
Authors: Rizwanul Fattah I. M. , Kalam M. A. , Masjuki H. H. , Wakil M. A.
Published: March 2014

This article studies the production and characterization of Malaysian Alexandrian laurel oil and the effect of common blends on engine performance and emissions.
Tröger's base quasiracemates and crystal packing tendencies
Authors: Cross Jacob T. , Rossi Nicholas A. , Serafin Mateusz , Wheeler Kraig A.
Published: March 2014

A family of 7 Tröger's base (TB) compounds that vary in configuration (quasiracemates, racemates, and enantiomers) and chemical substitutions (Me, Cl, and Br) has been investigated.
A facile exfoliation-crystal growth route to multicomponent Ag2CO3/Ag-Ti5NbO14 nanohybrids with improved visible light photocatalytic activity
Authors: Park Suhye , Lee Jang Mee , Jo Yun Kyung , Kim In Young , Hwang Seong-Ju
Published: March 2014

A novel visible light active photocatalyst is developed via a direct crystal growth of silver oxosalts on exfoliated titanoniobate nanosheets.
Bionanocomposites based on layered silicates and cationic starch as eco-friendly adsorbents for hexavalent chromium removal
Authors: Koriche Yamina , Darder Margarita , Aranda Pilar , Semsari Saida , Ruiz-Hitzky Eduardo
Published: March 2014

Functional bionanocomposites with the ability to adsorb Cr(vi) oxyanions were prepared by intercalation of cationic starch bearing quaternary ammonium groups in two layered silicates, commercial Cloisite®Na and an Algerian bentonite.
A study on the synthesis of Ni50Co50 alloy nanostructures with tuned morphology through metal–organic chemical routes
Authors: Mourdikoudis Stefanos , Collière Vincent , Fau Pierre , Kahn Myrtil L.
Published: March 2014

Isotropic and anisotropic NiCo alloy nanoparticles, as well as elongated nanostructures (nanorods, nanowires) with a tuned size, shape as well as stoichiometric overall composition are synthesized by employing a H2-assisted metal–organic chemical approach.
Air quality concerns of unconventional oil and natural gas production
Authors: Field R. A. , Soltis J. , Murphy S.
Published: March 2014

Air quality impacts from unconventional oil and gas development range from local to global scales impacting human health and climate.
Immobilization and molecular rearrangement of ionic liquids on the surface of carbon nanotubes
Authors: Zhao Cuifang , Ren Baozeng , Song Yuting , Zhang Junling , Wei Lingchao , Chen Shimou , Zhang Suojiang
Published: March 2014

Two kinds of imidazolium ionic liquids with different weight ratios were absorbed on the outer surface of MWCNTs. The orientational order and properties of ILs immobilized on the MWCNTs' surfaces were analyzed.
Fracture damage of nanowire lithium-ion battery electrode affected by diffusion-induced stress and bending during lithiation
Authors: Chen Bingbing , Zhou Jianqiu , Pang Xuming , Wei Pengfei , Wu Yunbo , Deng Kunjun
Published: March 2014

Lithium-ion battery electrode materials generally experience significant volume changes during lithium diffusion during charging and discharging.
Mark Ylvisaker's Influence on Interprofessional Learning for Speech-Language Pathology Graduate Students
Authors: Coulter Emma , Palasik Scott , Grand James A.
Published: March 2014

Mark Ylvisaker has left an undeniable mark on the field of speech-language pathology, particularly in the assessment and treatment of persons with traumatic brain injuries. Ylvisaker's work continues to hold relevance in the training of new and future clinicians and is now influencing a second generation of speech-language pathologists (SLPs). In this article, some of Ylvisaker's major intervention philosophies are discussed, which include the use of contextualized interventions, antecedent-based behavior management, the use of metaphors in intervention and research, and case-based decision making or patient specific hypothesis testing. Ylvisaker was also heavily influenced by his experience with other professional fields. In the spirit of Ylvisaker's emphasis on case-based research and value of interprofessional perspectives, data from an interprofessional education (IPE) experience performed at The University of Akron in conjunction with the Austen BioInnovation was presented. The data collected from the IPE explores the preparedness of students entering the healthcare profession in serving on inter-disciplinary teams, including those studying speech-language pathology. Results show the need for greater training and exposure to similar interprofessional experiences for graduate students studying speech-language pathology.
300 GHz InP HBT amplifier with 10 mW output power
Authors: Yu H.G. , Choi S.H. , Jeon S. , Kim M.
Published: March 2014

A high‐power terahertz solid‐state amplifier fabricated using 0.25 μm InP heterojunction bipolar transistor (HBT) technology is reported. This amplifier utilies a novel defective‐ground four‐way balun to combine differential amplifier chains for a total output device periphery of 40 μm. A significant amount of power of ∼10 mW is obtained at 305 GHz with better than 20 dB small‐signal gain.
Scene recognition with omnidirectional images in low‐textured environments
Authors: Ryu Hyejeong , Chung Wan Kyun
Published: March 2014

A combined method involving global and local descriptors was developed to recognise scenes for loop closure detection in low‐textured environments. An omnidirectional image is divided into background regions and salient regions according to the colour distribution. To represent a scene with features that are appropriate to its characteristics, global features for background regions are calculated and scale invariant feature transform features for salient regions are extracted. The proposed method can compute a more distinct scene similarity, and this was verified by an experiment involving loop closure detection.
Window increasing technique to discriminate mathematical and physical resonant poles extracted from antenna response
Authors: Sarrazin F. , Pouliguen P. , Sharaiha A. , Potier P. , Chauveau J.
Published: March 2014

A new approach called the window increasing technique (WIT) is presented to discriminate mathematical and physical poles extracted from a noisy antenna response. The principle of the WIT is to apply a pole extraction method on several windows of the response and then to observe the stability of the extracted poles. To compare the WIT with the classical window moving technique (WMT), these two techniques are applied on the electric far‐field backscattered by a dipole antenna. It is shown that, in the presence of noise, the WIT allows finding more physical poles with a good accuracy than does the WMT.
Reflection imaging with terahertz quantum‐cascade laser and quantum‐well photodetector
Authors: Tan Z.Y. , Zhou Tao , Fu Z.L. , Cao J.C.
Published: March 2014

A reflection imaging system based on the terahertz quantum‐well photodetector is presented. Reflected terahertz imaging of a logo on a universal serial bus (USB) flash disk is demonstrated. A spatial resolution better than 0.4 mm is achieved. This experiment demonstrates that the quantum‐well photodetector is potentially useful for reflection imaging applications.
Inductor array for minimising transfer efficiency decrease of wireless power transmission components at misalignment
Authors: Ahn H.R. , Kim M.S. , Kim Y.J.
Published: March 2014

A secondary coil design is reported for the stable transmission of wireless power in a misalignment situation. A coil array is applied to a secondary coil instead of typical single coil. When a misalignment occurs, the misalignment distance between an individual coil in the array and the primary coil is decreased relatively. Therefore, the sudden reduction in the inductive wireless power transmission (WPT) efficiency is mitigated. When the fabricated coil array transmits power, the maximum WPT efficiency improves by 56.45% compared with the typical single coil. The frequency band of the proposed array is wider, and this system can stably transmit power.
Channel width selection scheme for better utilisation of WLAN bandwidth
Authors: Stelter A.
Published: March 2014

The channel access method, defined in the IEEE 802.11ac draft, forces stations (STAs) to transmit data over the widest currently available channel supported by the basic service set (BSS). Unfortunately, the transmission in a wide channel is very inefficient if data frames are short. A channel width selection scheme (CWSS) is proposed which reduces the bandwidth used by the STA, if the transmitted data frame is not sufficiently long. Simulation results show that the CWSS allows a better bandwidth utilisation in an environment of overlapping 802.11ac BSSs. The CWSS is compatible with the channel access procedure defined in the IEEE 802.11ac.
Penalised and doubly‐penalised parallel/successive interference cancellation multi‐user detectors for asynchronous upstream optical code division multiple access passive optical network
Authors: Seleem Hussein , Bentrcia Abdelouahab , Fathallah Habib
Published: March 2014

Optical code division multiple access (OCDMA) is one of the emerging technologies for next generation passive optical networks that can offer customers a Gb/s‐class experience in the upstream. However, OCDMA suffers from multiple access interference (MAI) that significantly reduces the capacity of the system. To mitigate MAI, three novel interference cancellation (IC) techniques have been proposed for incoherent direct sequence OCDMA systems that make use of some prior information to enhance their performance. Some of the IC structures exploit the non‐negativity of the solution, while others exploit in addition to the non‐negativity information the noise variance information. The proposed IC detectors outperform the conventional correlation receiver, the decorrelator detector, the linear parallel/successive interference cancellation detectors and even the linear minimum mean square error detector.
Decode and forward relaying for energy‐efficient multiuser cooperative cognitive radio network with outage constraints
Authors: Naeem Muhammad , Illanko Kandasamy , Karmokar Ashok , Anpalagan Alagan , Jaseemuddin Muhammad
Published: March 2014

We investigate the optimal allocation of power in the downlink cooperative cognitive radio network using decode and forward (DF) relaying technique. The power allocation in DF relaying for green cooperative cognitive radio with an objective of maximising energy‐efficiency is a constraint non‐linear non‐convex fractional programming problem. The optimisation needs to satisfy the primary users interference constraints and secondary users outage constraints. The authors present the optimal power allocation in DF relaying by transforming the constraint non‐linear non‐convex fractional power allocation problem into a concave fractional programme by using Charnes–Cooper transformation. The authors also present an iterative algorithm that uses parametric transformation and guarantees ε‐optimal convergence. The convergence of the iterative algorithm is proved and numerical results obtained for cooperative cognitive radio network are presented with different network parameter settings.
Null‐space cognitive precoding for heterogeneous networks
Authors: Castanheira Daniel , Silva Adão , Gameiro Atílio
Published: March 2014

Small‐cells are considered as an effective solution to increase capacity and offload traffic from, the current macro‐cell cellular system. Owing to the difficulty and costs involved in acquiring new spectrum licenses, small‐cells are expected to coexist with their respective macro‐cells, in the same spectrum. This leads to considerable interference between the two systems. Optimum performance, at the macro‐cell, is achieved when the small‐cell terminals transmit their information over the null‐space of the macro‐cell link. However, availability, at the small‐cell terminals, of the macro‐cell channel null‐space information requires full‐cooperation and thus a high overhead of information exchange. In this study, the cognitive precoding schemes are designed under a limited inter‐system information exchange and the constraint that the performance of the macro‐cell link is kept close to the case where no small‐cell network does exist. Two techniques are considered: a two‐bit quantisation precoded and a dual space‐frequency coding precoded approach. It is demonstrated that the first achieves a performance close to the full cooperation approach recently proposed, but with very low information exchange requirements. For the second, it is show that both the systems are able to coexist without any inter‐system cooperation and with a performance close to the non‐coexistence scenario.
Approximate maximum a posteriori detection for multiple‐input–multiple‐output systems with bit‐level lattice reduction‐aided detectors and successive interference cancellation
Authors: Bai Lin , Li Qiaoyu , Bai Wei , Choi Jinho
Published: March 2014

For iterative detection and decoding (IDD) in multiple‐input–multiple‐output (MIMO) systems, although the maximum a posteriori (MAP) detector can achieve an optimal performance, because of its prohibitively high computational complexity, various low‐complexity approximate MAP detectors are studied. Among the existing MIMO detectors for the non‐IDD receivers, lattice reduction (LR)‐aided detectors can provide a near maximum‐likelihood (ML) detector's performance with reasonably low complexity, and they could be modified to be used in the IDD receivers. In this study, the authors propose a bit‐level LR‐aided MIMO detector whose performance can approach that of the MAP detector, where a priori information is taken into account for soft‐decisions. Furthermore, the proposed method can be extended to large dimensional MIMO systems by channel matrix decomposition and successive interference cancellation, by which a significant complexity reduction can be achieved. Through simulations and complexity analysis, it is shown that a near‐optimal performance is obtained by the authors proposed low‐complexity bit‐level LR‐aided detector for the IDD in the MIMO systems.
Research on global positioning system M‐code acquisition method and the acquisition performance
Authors: Li Hong , Lu Mingquan
Published: March 2014

In global positioning system modernisation, to further enhance the anti‐jamming capability of authorised signals, the new designed M‐code signal utilises a few revolutionary techniques. While enduing the signal with excellent performance, the techniques make the acquisition methods for conventional pseudo‐noise codes, such as C/A‐code and P(Y)‐code, inapplicable. Furthermore, compared with time‐domain correlation, frequency‐domain correlation is favourable for saving computation requirements and suppressing interferences. Thus, it is quite desirable to develop frequency‐domain‐based ones. To this end, a frequency‐domain‐based acquisition method is developed, and based on the method the acquisition performance of M‐code signal is evaluated and the factors associated with the performance are investigated. It is shown that M‐code provides flexible tradeoffs between performance and implementation complexity through the sidebands and chips of the signal. Numerical and simulation results demonstrate the results.
Determination of optimal nanotube radius for single‐strand deoxyribonucleic acid encapsulation
Authors: Alshehri Mansoor H. , Cox Barry J. , Hill James M.
Published: March 2014

The molecular interactions between a single‐strand deoxyribonucleic acid (ssDNA) molecule and a carbon nanotube (CNT) are modelled to determine the suction force experienced by the DNA which is assumed to be located on the axis near the open end of a single‐walled CNT (SWCNT). They determine the optimal nanotube radius for encapsulation, that is, the radius of the nanotube with the lowest interaction energy. The expression for the molecular interaction energy is derived from the 6–12 Lennard‐Jones potential together with the continuum approach, which assumes that a discrete atomic structure can be replaced by a line or a surface with constant average atomic density. It was found that an ssDNA can be encapsulated inside a SWCNT with a radius larger than 8.2 Å, and it is shown that the optimal SWCNT needed to fully enclose the DNA molecule has a radius of 8.8 Å, which approximately corresponds to the chiral vector numbers (13, 13). This means that if it is wished to encapsulate the ssDNA into a CNT, an ideal SWCNT to do this is (13, 13) which has the required radius of 8.8 Å.
Assembly and copper ions detection of highly sensible and stable hydroxyapatite nanocomposite fluorescence probe
Authors: Lu Yi , Jiang Hao , Zhang Nai‐Qian , Zhang Min , Liu Jin‐Ku
Published: March 2014

A novel hydroxyapatite (HAP)–fluorescein (FL) nanocomposite has been designed and assembled successfully as an efficient fluorescent probe for Cu2+ ions. Compared with a plain FL probe, the HAP–FL probe exhibits higher stability and sensitivity. The fluorescence intensity of the probe has shown a linear response to Cu2+ in the concentration range of 1 × 10−3 –1 × 10−6 mol·l−1 in an aqueous solution. These results indicate that the method based on the fluorescence quenching mechanism has enormous potential for the development of a highly efficient fluorescence probe for the detection of the heavy metal ions.
Fabrication of size controllable SU‐8 nanochannels using nanoimprint lithography and low‐pressure thermal bonding methods
Authors: Li Xiaojun , You Hui , Jiang Hai , Lin Ronghui , Kong Deyi , Jiang Rui , Zhu Likai , Gao Jun , Tang Min , Wang Xudi , Fu Shaojun
Published: March 2014

A new and simple method is demonstrated to achieve size controllable nanochannels by using nanoimprint lithography and low‐pressure thermal bonding methods. The flexible free‐standing SU‐8 allows the bonding of the nanochannels' pattern features at such a low pressure primarily because of ‘sequential’ bonding made possible by the bonding layer flexibility and the conformal contact made between the bonding layer and the structure layer in a large area. The simple geometrical argument shows that the height of the enclosed nanochannel can be determined by the depth of the cross‐linked SU‐8 trenches as well as by the initial thickness of the thin unexposed SU‐8 layer. The height of the nanochannels can also be controlled by adjusting the ratio of the ridge width to the trench width on the SU‐8 trenches. These simple relationships can serve as a guideline in choosing the parameters for SU‐8 nanochannel fabrication.
Experimental study of linear and nonlinear regimes of density-driven instabilities induced by CO2 dissolution in water
Authors: Outeda R. , El Hasi C. , D'Onofrio A. , Zalts A.
Published: March 2014

Density driven instabilities produced by CO2 (gas) dissolution in water containing a color indicator were studied in a Hele Shaw cell. The images were analyzed and instability patterns were characterized by mixing zone temporal evolution, dispersion curves, and the growth rate for different CO2 pressures and different color indicator concentrations. The results obtained from an exhaustive analysis of experimental data show that this system has a different behaviour in the linear regime of the instabilities (when the growth rate has a linear dependence with time), from the nonlinear regime at longer times. At short times using a color indicator to see the evolution of the pattern, the images show that the effects of both the color indicator and CO2 pressure are of the same order of magnitude: The growth rates are similar and the wave numbers are in the same range (0–30 cm−1) when the system is unstable. Although in the linear regime the dynamics is affected similarly by the presence of the indicator and CO2 pressure, in the nonlinear regime, the influence of the latter is clearly more pronounced than the effects of the color indicator.
RNA pseudo-knots simulated with a one-bead coarse-grained model
Authors: Taxilaga-Zetina Oscar , Pliego-Pastrana Patricia , Carbajal-Tinoco Mauricio D.
Published: March 2014

We present a revised version of a Monte Carlo simulation model for RNA molecules that was introduced in a previous communication [O. Taxilaga-Zetina, P. Pliego-Pastrana, and M. D. Carbajal-Tinoco, Phys. Rev. E 81, 041914 (2010)]. The basic model consists of a series of knowledge-based pair potentials that were obtained from the statistical analysis of large RNAs belonging to the Protein Data Bank. These effective interactions are then used to dress a polymeric chain that reproduces relatively simple secondary structures (e.g., small hairpins). In order to describe more complicated three-dimensional structures such as pseudo-knots, here we include orientational information for the interaction between nucleotides forming hydrogen bonds, as in the case of the Watson-Crick base pairs. As a result, the simulated molecules obtained through the modified model are now consistent with their corresponding experimental configurations.
Observations on the non-mixed length and unsteady shock motion in a two dimensional supersonic ejector
Authors: Rao Srisha M. V. , Jagadeesh Gopalan
Published: March 2014

Key features that drive the operation of a supersonic ejector are the complex gasdynamic interactions of the primary and secondary flows within a variable area duct and the phenomenon of compressible turbulent mixing between them, which have to be understood at a fundamental level. An experimental study has been carried out on the mixing characteristics of a two dimensional supersonic ejector with a supersonic primary flow (air) of Mach number 2.48 and the secondary flow (subsonic) which is induced from the ambient. The non-mixed length, which is the length within the ejector for which the primary and secondary flow remain visually distinct is used to characterize the mixing in the ejector. The operating pressures, flow rates and wall static pressures along the ejector have been measured. Two flow visualization tools have been implemented—time resolved schlieren and laser scattering flow visualization. An important contribution has been the development of in-house image processing algorithms on the MATLAB platform to detect the non-mixed length from the schlieren and laser scattering images. The ratio of mass flow rates of the secondary flow to primary flow (entrainment ratio) has been varied in a range of 0.15–0.69 for two locations of the primary nozzle in the ejector duct. Representative cases have been computed using commercial CFD tool (Fluent) to supplement the experiments. Significant outcomes of the study are—the non-mixed length quantified from the flow visualization images is observed to lie within 4.5 to 5.2 times the height of the mixing duct which is confirmed by the wall static pressure profiles. The flow through the supersonic ejector in the mixed regime is explained using corroborative evidences from different diagnostic tools. A reduction of the non-mixed length by 46.7% is observed at operating conditions when the nozzle is sufficiently overexpanded. The disturbance caused to the mixing layer due to unsteady shock-boundary layer interactions within the nozzle at such conditions enhances mixing. The analysis of time resolved schlieren images have provided interesting observations on repetitive back and forth motion of the shock cells in the primary flow with a co-flowing secondary flow in the confines of the supersonic ejector. The oscillations have significant amplitudes (order of the nozzle height) at the centerline. The details of these experiments followed by the analysis of data and the inferences drawn from the results are discussed in this article.
Closure measures for coarse-graining of the tent map
Authors: Pfante Oliver , Olbrich Eckehard , Bertschinger Nils , Ay Nihat , Jost Jürgen
Published: March 2014

We quantify the relationship between the dynamics of a time-discrete dynamical system, the tent map T and its iterations Tm, and the induced dynamics at a symbolical level in information theoretical terms. The symbol dynamics, given by a binary string s of length m, is obtained by choosing a partition point α∈[0,1] and lumping together the points x∈[0,1] s.t. Ti(x) concurs with the i − 1th digit of s—i.e., we apply a so called threshold crossing technique. Interpreting the original dynamics and the symbolic one as different levels, this allows us to quantitatively evaluate and compare various closure measures that have been proposed for identifying emergent macro-levels of a dynamical system. In particular, we can see how these measures depend on the choice of the partition point α. As main benefit of this new information theoretical approach, we get all Markov partitions with full support of the time-discrete dynamical system induced by the tent map. Furthermore, we could derive an example of a Markovian symbol dynamics whose underlying partition is not Markovian at all, and even a whole hierarchy of Markovian symbol dynamics.
Effects of Mo addition on thermal stability and magnetic properties of a ferromagnetic Fe75P10C10B5 metallic glass
Authors: Zhang Wei , Jia Xingjie , Li Yanhui , Fang Canfeng
Published: March 2014

The effects of Mo content on the thermal stability, glass-forming ability (GFA), magnetic and mechanical properties of Fe75−xMoxP10C10B5 (x = 0–10) metallic glasses were investigated. The stabilization of supercooled liquid and GFA were significantly enhanced by addition of Mo. Although the saturation magnetization (Is) of the alloys reduced with increasing Mo content, the coercive force (Hc) decreased. The metallic glasses with x = 2.5–7.5 exhibit low glass transition temperature of 733–749 K, large supercooled liquid region of 61–96 K, and high GFA with critical fully glassy sample diameters of 1.5–3.0 mm. They also possess rather high Is of 0.81–1.11 T, low Hc of 2.07–4.87 A/m, high Vicker's hardness of 860–992, high compressive yield strength of over 3000 MPa with a distinct plastic strain.
Pulsing frequency induced change in optical constants and dispersion energy parameters of WO3 films grown by pulsed direct current magnetron sputtering
Authors: Punitha K. , Sivakumar R. , Sanjeeviraja C.
Published: March 2014

In this work, we present the pulsing frequency induced change in the structural, optical, vibrational, and luminescence properties of tungsten oxide (WO3) thin films deposited on microscopic glass and fluorine doped tin oxide (SnO2:F) coated glass substrates by pulsed dc magnetron sputtering technique. The WO3 films deposited on SnO2:F substrate belongs to monoclinic phase. The pulsing frequency has a significant influence on the preferred orientation and crystallinity of WO3 film. The maximum optical transmittance of 85% was observed for the film and the slight shift in transmission threshold towards higher wavelength region with increasing pulsing frequency revealed the systematic reduction in optical energy band gap (3.78 to 3.13 eV) of the films. The refractive index (n) of films are found to decrease (1.832 to 1.333 at 550 nm) with increasing pulsing frequency and the average value of extinction coefficient (k) is in the order of 10−3. It was observed that the dispersion data obeyed the single oscillator of the Wemple-Didomenico model, from which the dispersion energy (Ed) parameters, dielectric constants, plasma frequency, oscillator strength, and oscillator energy (Eo) of WO3 films were calculated and reported for the first time due to variation in pulsing frequency during deposition by pulsed dc magnetron sputtering. The Eo is change between 6.30 and 3.88 eV, while the Ed varies from 25.81 to 7.88 eV, with pulsing frequency. The Raman peak observed at 1095 cm−1 attributes the presence of W-O symmetric stretching vibration. The slight shift in photoluminescence band is attributed to the difference in excitons transition. We have made an attempt to discuss and correlate these results with the light of possible mechanisms underlying the phenomena.
Derivation of the cell dielectric properties based on Clausius-Mossotti factor
Authors: Lo Y. J. , Lei U. , Chen K. Y. , Lin Y. Y. , Huang C. C. , Wu M. S. , Yang P. C.
Published: March 2014

The dielectric properties of membrane and cytoplasm of cells were commonly derived using the experimental electrorotation spectra, which are proportional to the spectra of the imaginary part of the Clausius-Mossotti factor (Ki). However, it was found in this study that the cell properties thus derived do not agree with those derived using the experimental spectra of the real part of the Clausius-Mossotti factor (Kr). Both the Kr and Ki spectra are required simultaneously for deriving appropriate cell dielectric properties. Also the membrane and cytoplasm conductivities decrease, while the membrane and cytoplasm permittivities remain relatively unchanged, as the medium conductivity decreases.
The role of band alignment in p-type conductivity of Na-doped ZnMgO: Polar versus non-polar
Authors: Zhang H. H. , Pan X. H. , Li Y. , Ye Z. Z. , Lu B. , Chen W. , Huang J. Y. , Ding P. , Chen S. S. , He H. P. , Lu J. G. , Chen L. X. , Ye C. L.
Published: March 2014

We investigate the electrical properties of polar and non-polar ZnMgO:Na films that have been fabricated on c-plane and r-plane sapphire substrates using intervened ZnO layers (10–30 nm thick) by pulsed laser deposition. Hall-effect measurements indicate that the a-plane ZnMgO:Na film exhibits p-type conductivity with a carrier concentration of about 3.5 × 1016 cm−3, while the polar film shows a compensatory conductivity. Meanwhile, the dependence of the band alignment on the orientation of the ZnMgO/ZnO heterojunctions has been investigated using photoelectron spectroscopy. The heterojunctions form in the type-I straddling alignment with valence band offsets of 0.07 (0.02) eV for the (non-)polar heterojunction. The difference in valence band offsets is primarily attributed to the spontaneous polarization effect. We propose that the smaller valence band offsets and larger conduction band offsets would reduce the NaZn acceptor level and enhance the relative intrinsic donor levels. Such effects consequently lead to p-type conductivity in non-polar ZnMgO:Na films. The band alignment of non-polar ZnMgO/ZnO can be used to facilitate p-type doping with a shallower acceptor state in the ZnO-like alloy.
Wildland firefighter safety zones: a review of past science and summary of future needs
Authors: Butler B. W.
Published: March 2014

Current wildland firefighter safety zone guidelines are based on studies that assume flat terrain, radiant heating, finite flame width, constant flame temperature and high flame emissivity. Firefighter entrapments and injuries occur across a broad range of vegetation, terrain and atmospheric conditions generally when they are within two flame heights of the fire. Injury is not confined to radiant heating or flat terrain; consequently, convective heating should be considered as a potential heating mode. Current understanding of energy transport in wildland fires is briefly summarised, followed by an analysis of burn injury mechanisms within the context of wildland fire safety zones. Safety zone theoretical and experimental studies are reviewed and a selection of wildland fire entrapments are examined within the context of safe separation distances from fires. Recommendations are made for future studies needed to more fully understand and define wildland firefighter safety zones.
Teachers' and learners' perspectives on autonomy
Authors: Benson Phil
Published: March 2014

In the literature on language teaching and learning, there are many variations upon the basic idea of autonomy. The problem is to explain how these different ways of representing autonomy and putting it into practice may be linked to broader political, ideological or philosophical outlooks. In previous work, for example, I have suggested that we might speak of ‘technical’, ‘psychological’ and ‘political’ versions of autonomy linked to ‘positivistic’, ‘constructivist’ and ‘critical’ outlooks (Benson, 1997). In this chapter, I want to explore this issue from a somewhat different point of view, by asking how the idea of autonomy may appear differently when viewed from a teacher’s or learner’s perspective and how this basic difference of perspective may be related to the three versions of autonomy mentioned above. The basic idea that I want to develop here is that of ‘perspective’, a term I use to refer to a way of viewing a phenomenon that is conditioned both by an individual’s position in a power-inflected role relationship (in this case the teacher-student relationship) and by the experience that the individual acquires within this relationship. The underlying assumption is that teachers and students view the processes in which they are mutually engaged from very different perspectives and that this is likely to influence the ways in which they make sense of a notion such as autonomy. My argument is that, from the teachers’ perspective, autonomy is primarily concerned with institutional and classroom learning arrangements within established curricula. In other words, from the teachers’ perspective, autonomy tends to imply the learner taking control of arrangements whose underlying legitimacy is unquestioned. From the learners’ perspective (which I view as tangential to, rather than opposed to, the teachers’ perspective) autonomy is primarily concerned with learning, in a much broader sense, and its relationship to their lives beyond the classroom. I will illustrate this argument with a theoretical model and empirical data. In conclusion, I will also discuss its relevance to important issues in our field, such as learner resistance to autonomy and the concept of teacher autonomy.
Freedom - a prerequisite for learner autonomy? Classroom innovation and language teacher education
Authors: Trebbi Turid
Published: March 2014

Freedom is frequently referred to as an inherent aspect of learner autonomy and is seemingly accepted as a matter of course, presumably because there is semantic overlap between the word autonomy and the concept of freedom. However, this may turn out to be a simplistic view of both freedom and learner autonomy. The aim of this article is to examine the relationship between the two. After having considered the definition of learner autonomy, the first part poses the issue of learner autonomy and freedom in an institutional context. It then goes on to relate findings from two research projects and concludes by presenting the need for an alternative definition of freedom as related to the concept of learner autonomy.
The subjective theories of student teachers: Implications for teacher education and research on learner autonomy
Authors: Martinez Hélène
Published: March 2014

This article aims to explore to what extent the analysis of subjective theories of student teachers about learner autonomy and their experience as learners and student teachers can help us to re-examine professional scientific theories of learner autonomy and approaches to teacher education. Emphasis is placed on empirical data collected from semi-structured interviews conducted with two groups of student teachers, with special attention to the analysis and interpretation of the verbal data. The study is based on the assumption that the validity of learner autonomy depends on our ability to ground it in empirical research. Thus, qualitative and interpretative research can contribute to protect the concept from narrow interpretations deprived of validity and relevance to language education. Subjective theories are discussed as a means of conceptualising how student teachers view learner autonomy and how these subjective views can be integrated into pre-service teacher training programs. This article suggests that more qualitative and interpretative research should be done in order to foster learner autonomy in the language classroom.
Autonomous teachers, autonomous cognition: Developing personal theories through reflection in language teacher education
Authors: Hacker Penny , Barkhuizen Gary
Published: March 2014

In order for language teachers to meet the challenges of autonomy, we claim it is essential that they know what they believe about teaching and learning. Language teacher education programmes, therefore, should create opportunities for participants to examine and develop their personal theories of teaching. This conclusion was reached through conducting a study in which an inductive qualitative approach, based on a constructionist perspective of knowledge and learning, was used to investigate the personal theories of 20 language teachers. We wanted to discover how their experience over one course in their programme of education may have influenced their cognition. To do this we examined their own analyses of a series of personal reflective journal entries each of them had written during the course. Through inductive analysis we were able to identify a number of salient categories; that is, individual articulations yet one collective articulation of the teachers’ experiences. The articulations revealed that over the course the vast majority of teachers gained further understanding of their personal theories, that the reflective process was central to their experience and that engaging in reflection itself generated confidence for many teachers toward their personal cognition. Furthermore, their articulations support our belief that reflection continues to play a valuable role in teacher education, particularly as it pertains to teachers’ developing personal theories. The teachers’ analyses also reveal that confidence in their own theories may be gained directly from engaging in reflection. We conclude that the mental space afforded teachers in courses of education promotes such reflection and thus prepares them to be effective autonomous teachers.