bluuebunny/crossref_metadata_2025 huggingface dataset:
Experimental results for the flexible joint cable-suspended manipulator of ICaSbot
Authors: Korayem M. H. , Bamdad M. , Tourajizadeh H. , Korayem A. H. , Zehtab R. M. , Shafiee H. , Arvani A.
Published: March 2013

In this paper, design, dynamic, and control of the motors of a spatial cable robot are presented considering flexibility of the joints. End-effector control in order to control all six spatial degrees of freedom (DOFs) of the system and motor control in order to control the joints flexibility are proposed here. Corresponding programing of its operation is done by formulating the kinematics and dynamics and also control of the robot. Considering the existence of gearboxes, flexibility of the joints is modeled in the feed-forward term of its controller to achieve better accuracy. A two sequential closed-loop strategy consisting of proportional derivative (PD) for linear actuators in joint space and computed torque method for nonlinear end-effector in Cartesian space is presented for further accuracy. Flexibility is estimated using modeling and simulation by MATLAB and SimDesigner. A prototype has been built and experimental tests have been done to verify the efficiency of the proposed modeling and controller as well as the effect of flexibility of the joints. The ICaSbot (IUST Cable-Suspended robot) is an under-constrained six-DOF parallel robot actuated by the aid of six suspended cables. An experimental test is conducted for the manufactured flexible joint cable robot of ICaSbot and the outputs of sensors are compared with simulation. The efficiency of the proposed schemes is demonstrated.
Orientations to English in post-apartheid schooling
Authors: McKinney Carolyn
Published: February 2013

As Voloshinov has famously argued, ‘the word is the most sensitive index of social changes, and what is more, of changes still in the process of growth’ (Voloshinov, 1986: 19). Scrutiny of young people's discourses on language together with their language practices offers us a window into a society in transition, such as present-day South Africa. This article examines the language ideologies and language practices of Black youth attending previously White, now desegregated, suburban schools in South African cities, important spaces for the production of an expanding Black middle class (Soudien, 2004). Due to their resourcing during apartheid (both financial and human) previously White schools are aligned with quality education and perceived as strategic sites for the acquisition and maintenance of a prestige variety of South African English. This article looks at how mainly African girls (15–16 years) position themselves in relation to English, drawing on data collected using ethnographic approaches in four desegregated schools in South African cities: three in Johannesburg, Gauteng and one in Cape Town, Western Cape. The discussion focuses on two significant themes: English and the [re]production of race; and the place of English in young people's linguistic repertoires. My aim is to show how African youth in desegregated schools orient themselves to English and what their language ideologies and language practices might tell us about macro social processes, including the (re)constitution of race in South Africa. Schooling, as Bourdieu points out, is one of the most important sites for social reproduction and is thus also one of the key sites, ‘which imposes the legitimate forms of discourse and the idea that discourse should be recognised if and only if it conforms to the legitimate norms’ (Bourdieu, 1977: 650). However, co-present with processes of reproduction are practices that work to subvert and unsettle dominant discourses. Suburban desegregated schools are thus productive sites for the re-making of cultural practices (including language) and identities.
Colonization of forest clearings and tree-fall gaps in lowland rain forests of Colombia by hemiepiphytic aroids: experimental and transect studies
Authors: Benavides Ana María , Wolf Jan H. D. , Duivenvoorden Joost F.
Published: February 2013

The contribution of vegetative recruitment by non-tree species to the regeneration of tropical forests in man-made clearings or tree-fall gaps tends to be ignored. In a series of field studies near Amacayacu, Colombian Amazonia, we tested if hemiepiphytic aroids quickly colonize such open habitats through seed dispersal, sprouting plant fragments, or lateral invasion of flagellar aroids from the closed forest nearby. A seed germination experiment applying two soil substrates and three shade levels showed that abundant light reduced the germination success of three Philodendron species. A total of 400 cuttings from five Philodendron species were placed in forest clearings and almost 12% of these sprouted within 14 wk. Monitoring more than 2000 aroid plants over 14 mo in different habitats showed that recruitment was low (0.3 plants per 10 m2) compared with initial densities (3.1 plants per 10 m2). Flagellar aroids grew about 2.5 times faster than non-flagellar aroids. In forest edges they reached a mean apical growth of 98 cm in 14 mo. However, non-flagellar aroids were five to six times more abundant than flagellar individuals everywhere. It was concluded that hemiepiphytic aroids colonize open habitats mostly through a post-disturbance survival of plants or plant fragments.
Managing biodiversity rich hay meadows in the EU: a comparison of Swedish and Romanian grasslands
Authors: DAHLSTRÖM ANNA , IUGA ANA-MARIA , LENNARTSSON TOMMY
Published: March 2013

Semi-natural hay meadows are among the most biodiversity-rich terrestrial ecosystems, and are managed for conservation purposes in most of Europe, including Sweden. Romania has some of Europe's largest areas of grasslands still managed with traditional methods. Through interviews and field studies, current management practices were investigated in two Romanian villages, and compared with CAP-generated grassland management in Swedish hay meadows and historical Swedish management of grasslands. The study evaluated the effect of the eligibility criteria within both countries’ National Rural Development Programmes (NRDPs) on different ecologically important components of hay meadow management. The success of Swedish management was measured by assessing population trends for 25 grassland plant species. Current management proved to be considerably more diverse in Romania than in Sweden, but historical Swedish management was similar to management in Romania. Both countries’ NRDPs provide support for some management components, but create barriers against other components. The Romanian NRDP contained more barriers than the Swedish NRDP, yet Swedish management showed little success in preserving grassland plants. NRDPs should nourish the use of local and traditional knowledge in order to preserve biodiversity in semi-natural grasslands. There are major limitations in both countries’ NRDPs.
Genetic and epigenetic associations of MAOA and NR3C1 with depression and childhood adversities
Authors: Melas Philippe A. , Wei Yabin , Wong Chloe C. Y. , Sjöholm Louise K. , Åberg Elin , Mill Jonathan , Schalling Martin , Forsell Yvonne , Lavebratt Catharina
Published: March 2013

Monoamine oxidase A (MAOA) harbours a polymorphic upstream variable-number tandem repeat (u-VNTR). The MAOA-L allele of the u-VNTR leads to decreased gene expression levels in vitro and has been found to increase the risk of conduct disorder in males with childhood adversities. Early-life adversities have been associated with hypermethylation of the glucocorticoid receptor (NR3C1). In this study, we first performed a genetic association analysis of the MAOA u-VNTR using individuals with depression (n = 392) and controls (n = 1276). Next, DNA methylation analyses of MAOA and NR3C1 were performed using saliva samples of depressed and control subgroups. Adult MAOA-L females with childhood adversities were found to have a higher risk of developing depression (p = 0.006) and overall MAOA methylation levels were decreased in depressed females compared to controls (mean depressed, 42% vs. mean controls, 44%; p = 0.04). One specific childhood adversity [early parental death (EPD)] was associated with hypermethylation of NR3C1 close to an NGFI-A binding site (mean EPD, 19% vs. mean non-EPD, 14%; p = 0.005). Regression analysis indicated that this association may be mediated by the MAOA-L allele (adjusted R2 = 0.24, ANOVA: F = 23.48, p < 0.001). Conclusively: (1) depression in females may result from a gene × childhood-adversity interaction and/or a dysregulated epigenetic programming of MAOA; (2) childhood-adversity subtypes may differentially impact DNA methylation at NR3C1; (3) baseline MAOA-genotypic variations may affect the extent of NR3C1 methylation.
Motive and Opportunity: British Christian Parties 1997–2011
Authors: Bruce Steve
Published: February 2013

The absence from Britain of anything like the United States New Christian Right of the 1980s could be explained by differences in the popularity of religion or in features of the respective party and political structures. Devolution and electoral reform have encouraged British Christians to form political parties and contest elections. Examination of their performance, agendas, and candidate profiles, coupled with survey data on British attitudes to mixing religion and politics, suggests that the major difference between the United States and Britain lies in the degree of secularization rather than in political opportunity structures.
Faith-Based Interventions for At-Risk Latino Youths: A Study of Outcomes
Authors: Monsma Stephen V. , Smidt Corwin E.
Published: February 2013

This is a study of the comparative outcome success experienced by 2748 participants in government-funded faith-based and community-based intervention programs for at-risk and adjudicated Latino youths run by 28 providers in five western cities. The Latino Coalition, an intermediary faith-based organization, subcontracted with 28 sub-grantees that provided the services from 2005–2008. The study found similar outcomes were experienced by youths in the faith-based versus the community-based programs, but it did find significantly different outcomes by the comprehensive versus non-comprehensive nature of the programs. The study places its findings in the context of faith-based and community initiatives and draws conclusions concerning the public policy implications of the government partnering with faith-based and community-based organizations to provide public services to needy, and especially minority, populations.
A Geometric Morphometric Assessment of Hand Shape and Comparison to the 2D:4D Digit Ratio as a Marker of Sexual Dimorphism
Authors: Sanfilippo Paul G. , Hewitt Alex W. , Mountain Jenny A. , Mackey David A.
Published: February 2013

Twin studies are extremely useful for investigating hypotheses of genetic influence on a range of behavioral and physical traits in humans. Studies of physical traits, however, are usually limited to size-related biological characteristics because it is inherently difficult to quantify the morphological counterpart – shape. In recent years, the development of geometry-preserving analytical techniques built upon multivariate statistical methodologies has produced a new discipline in biological shape analysis known as geometric morphometrics. In this study of hand shape analysis, we introduce the reader already familiar with the field of twin research to the potential utility of geometric morphometrics and demonstrate the cross-discipline applicability of methods. We also investigate and compare the efficacy of the 2D:4D ratio, a commonly used marker of sexual dimorphism, to the fully multivariate approach of shape analysis in discriminating between male and female sex. Studies of biological shape variation utilizing geometric morphometric techniques may be completed with software freely available on the Internet and time invested to master the small learning curve in concepts and theory.
Cerebral Blood Flow Changes after Brain Injury in Human Amyloid-Beta Knock-in Mice
Authors: Abrahamson Eric E , Foley Lesley M , DeKosky Steven T , Hitchens T Kevin , Ho Chien , Kochanek Patrick M , Ikonomovic Milos D
Published: February 2013

Traumatic brain injury (TBI) is an environmental risk factor for Alzheimer's disease (AD). Increased brain concentrations of amyloid-β (Aβ) peptides and impaired cerebral blood flow (CBF) are shared pathologic features of TBI and AD and promising therapeutic targets. We used arterial spin-labeling magnetic resonance imaging to examine if CBF changes after TBI are influenced by human Aβ and amenable to simvastatin therapy. CBF was measured 3 days and 3 weeks after controlled cortical impact (CCI) injury in transgenic human Aβ-expressing APPNLh/NLh mice compared to murine Aβ-expressing C57Bl/6J wild types. Compared to uninjured littermates, CBF was reduced in the cortex of the injured hemisphere in both Aβ transgenics and wild types; deficits were more pronounced in the transgenic group, which exhibited injury-induced increased concentrations of human Aβ. In the hemisphere contralateral to CCI, CBF levels were stable in Aβ transgenic mice but increased in wild-type mice, both relative to uninjured littermates. Post-injury treatment of Aβ transgenic mice with simvastatin lowered brain Aβ concentrations, attenuated deficits in CBF ipsilateral to injury, restored hyperemia contralateral to injury, and reduced brain tissue loss. Future studies examining long-term effects of simvastatin therapy on CBF and chronic neurodegenerative changes after TBI are warranted.
Modeling and Simulation as a Tool to Bridge Efficacy and Safety Data in Special Populations
Authors: Harnisch L , Shepard T , Pons G , Della Pasqua O
Published: February 2013

The registration and approval of novel medicines have traditionally been based on evidence arising from large prospective trials. Such an approach is often not possible or unsuitable to evaluate the benefit‐risk balance in special populations (e.g., children, ethnic groups, rare diseases). Inferences by modeling and simulation can play a major role in evidence synthesis. A framework is proposed that promotes its acceptability and the basis for decision making during development, registration, and therapeutic use of drugs.

CPT: Pharmacometrics & Systems Pharmacology (2013) 2, e28; doi:10.1038/psp.2013.6; advance online publication 27 February 2013
PdZn based catalysts: connecting electronic and geometric structure with catalytic performance
Authors: Föttinger Karin
Published: February 2013

In the recent years, the potential of PdZn intermetallic compounds and related compositions for improving and consequently replacing conventionally used catalysts has been explored for a range of diverse processes, such as selective hydrogenation reactions, methanol synthesis and steam reforming. PdZn has similar electronic properties and reactivity as Cu, a widely used metal catalyst, e.g. Cu is industrially applied in the low temperature water gas shift reaction and methanol synthesis. The higher stability of PdZn makes it an attractive alternative for certain applications. This review will give an overview over selected important potential applications and the correlation of the catalytic performance with properties, such as the electronic structure. A broad range of materials from oxide supported nanoparticles to single crystal based model systems is covered.
Design of artificial landmarks for underwater simultaneous localisation and mapping
Authors: Pailhas Yan , Capus Chris , Brown Keith , Petillot Yvan
Published: March 2013

The use of autonomous underwater vehicles for a variety of purposes is set to increase in the future. A key issue is accurate navigation, especially for survey applications large cumulative error are introduced by the various position sensors: accelerometer; Doppler velocity log; compass; inertial navigation sensors. Algorithms such as simultaneous localisation and mapping rely on accurate landmark recognition in order to correct the vehicle position. This study proposes a solution based on broadband sonar and passive artificial coded landmarks to improve the navigation. Through resolution of the wave equation for acoustic propagation in a multilayer concentric sphere, it is shown that there is a great diversity in the echo spectrum with only small changes in internal structure. This enables the design of a set of passive landmarks, which can be identified unambiguously, since each has a characteristic signature or spectral code when insonified with a broadband sonar.
Correlated Doppler‐assisted target tracking in clutter
Authors: Mušicki Darko , Lyul Song Taek , Lee Hae Ho , Nešić Dragan
Published: March 2013

In a surveillance situation, the origin of each measurement is uncertain. Each measurement may be a clutter measurement or a target detection. In addition to the position [range and angle(s)], measurements often include Doppler velocity. The Doppler velocity measurements are often (e.g. with the linearly modulated frequency transmitted signal) correlated with the range measurements. This study deals with data association (via measurement likelihoods) and estimation in this situation, with a special consideration of the Gaussian mixture approaches. A simulation study shows the benefit of this approach.
‘If I go in like a Cranky Sea Lion, I Come out like a Smiling Dolphin’: Marathon Swimming and the Unexpected Pleasures of Being a Body in Water
Authors: Throsby Karen
Published: March 2013

Drawing on (auto)ethnographic research—on the process of becoming a marathon swimmer, this paper argues that conventional characterisations of marathon swimming as being ‘80 per cent mental and 20 per cent physical’ reprise a mind–body split that at worst excludes women and at best holds them to a masculine standard. This in turn draws the focus towards sensory deprivation, bodily suffering and overcoming, to the exclusion of the pleasures of swimming, beyond the expected ones such as the challenge of swim completion. By exploring instead the ‘shifted sensorium’ of marathon swimming, and examples of the autotelic pleasures of swimming, this paper argues that training changes the way swimming body feels, and that it is these changes that enable a swimmer to feel ‘at home’ in an environment to which it does not naturally belong. This focus on the sensory aspects of swimming, and its unexpected pleasures, both highlights the ways in which those pleasures do not flow unproblematically to women, and brings to light alternative and politically provocative ways of experiencing the gendered sporting body. This highlights the contingency, however constrained, of even the most entrenched ways of thinking about bodies, both within and outside sport.
A comprehensive experimental and theoretical study of H2−CO spectra
Authors: Jankowski Piotr , Surin L. A. , Potapov A. , Schlemmer S. , McKellar A. R. W. , Szalewicz Krzysztof
Published: February 2013

A detailed description of a new ab initio interaction potential energy surfaces for the H2−CO complex computed on a six-dimensional grid (i.e., including the dependence on the H−H and C−O separations) is presented. The interaction energies were first calculated using the coupled-cluster method with single, double, and noniterative triple excitations and large basis sets, followed by an extrapolation procedure. Next, a contribution from iterative triple and noniterative quadruple excitations was added from calculations in smaller basis sets. The resulting interaction energies were then averaged over the ground-state and both ground- and first-excited-states vibrational wave functions of H2 and CO, respectively. The two resulting four-dimensional potential energy surfaces were fitted by analytic expressions. Theoretical infrared spectra calculated from these surfaces have already been shown [P. Jankowski, A. R. W. McKellar, and K. Szalewicz, Science 336, 1147 (2012)] to agree extremely well, to within a few hundredth of wavenumber, with the experimental spectra of the para and orthoH2−CO complex. In the latter case, this agreement enabled an assignment of the experimental spectrum, ten years after it had been measured. In the present paper, we provide details concerning the development of the surfaces and the process of spectral line assignment. Furthermore, we assign some transitions for paraH2−CO that have not been assigned earlier. A completely new element of the present work are experimental investigations of the orthoH2−CO complex using microwave spectroscopy. Vast parts of the measured spectrum have been interpreted by comparisons with the infrared experiments, including new low-temperature ones, and theoretical spectrum. Better understanding of the spectra of both para and orthoH2−CO complexes provides a solid foundation for a new search of the bound H2−CO complex in space.
On the statistical equivalence of restrained-ensemble simulations with the maximum entropy method
Authors: Roux Benoît , Weare Jonathan
Published: February 2013

An issue of general interest in computer simulations is to incorporate information from experiments into a structural model. An important caveat in pursuing this goal is to avoid corrupting the resulting model with spurious and arbitrary biases. While the problem of biasing thermodynamic ensembles can be formulated rigorously using the maximum entropy method introduced by Jaynes, the approach can be cumbersome in practical applications with the need to determine multiple unknown coefficients iteratively. A popular alternative strategy to incorporate the information from experiments is to rely on restrained-ensemble molecular dynamics simulations. However, the fundamental validity of this computational strategy remains in question. Here, it is demonstrated that the statistical distribution produced by restrained-ensemble simulations is formally consistent with the maximum entropy method of Jaynes. This clarifies the underlying conditions under which restrained-ensemble simulations will yield results that are consistent with the maximum entropy method.
Determination of phase equilibria in confined systems by open pore cell Monte Carlo method
Authors: Miyahara Minoru T. , Tanaka Hideki
Published: March 2013

We present a modification of the molecular dynamics simulation method with a unit pore cell with imaginary gas phase [M. Miyahara, T. Yoshioka, and M. Okazaki, J. Chem. Phys. 106, 8124 (1997)] designed for determination of phase equilibria in nanopores. This new method is based on a Monte Carlo technique and it combines the pore cell, opened to the imaginary gas phase (open pore cell), with a gas cell to measure the equilibrium chemical potential of the confined system. The most striking feature of our new method is that the confined system is steadily led to a thermodynamically stable state by forming concave menisci in the open pore cell. This feature of the open pore cell makes it possible to obtain the equilibrium chemical potential with only a single simulation run, unlike existing simulation methods, which need a number of additional runs. We apply the method to evaluate the equilibrium chemical potentials of confined nitrogen in carbon slit pores and silica cylindrical pores at 77 K, and show that the results are in good agreement with those obtained by two conventional thermodynamic integration methods. Moreover, we also show that the proposed method can be particularly useful for determining vapor-liquid and vapor-solid coexistence curves and the triple point of the confined system.
Minimum energy pathways via quantum Monte Carlo
Authors: Saccani S. , Filippi C. , Moroni S.
Published: March 2013

We perform quantum Monte Carlo (QMC) calculations to determine minimum energy pathways of simple chemical reactions, and compare the computed geometries and reaction barriers with those obtained with density functional theory (DFT) and quantum chemistry methods. We find that QMC performs in general significantly better than DFT, being also able to treat cases in which DFT is inaccurate or even unable to locate the transition state. Since the wave function form employed here is particularly simple and can be transferred to larger systems, we suggest that a QMC approach is both viable and useful for reactions difficult to address by DFT and system sizes too large for high level quantum chemistry methods.
Atomic force microscope infrared spectroscopy on 15 nm scale polymer nanostructures
Authors: Felts Jonathan R. , Cho Hanna , Yu Min-Feng , Bergman Lawrence A. , Vakakis Alexander F. , King William P.
Published: February 2013

We measure the infrared spectra of polyethylene nanostructures of height 15 nm using atomic force microscope infrared spectroscopy (AFM-IR), which is about an order of magnitude improvement over state of the art. In AFM-IR, infrared light incident upon a sample induces photothermal expansion, which is measured by an AFM tip. The thermomechanical response of the sample-tip-cantilever system results in cantilever vibrations that vary in time and frequency. A time-frequency domain analysis of the cantilever vibration signal reveals how sample thermomechanical response and cantilever dynamics affect the AFM-IR signal. By appropriately filtering the cantilever vibration signal in both the time domain and the frequency domain, it is possible to measure infrared absorption spectra on polyethylene nanostructures as small as 15 nm.
Molecular dynamics simulation of inertial trapping-induced atomic scale mass transport inside single walled carbon nanotubes
Authors: Hu Z. L. , Mårtensson Gustaf , Murugesan Murali , Guo Xingming , Liu Johan
Published: March 2013

The forced transverse vibration of a single-walled carbon nanotube (SWNT) embedded with atomic-size particles was investigated using molecular dynamic simulations. The particles inside the cylindrical cantilever can be trapped near the antinodes or at the vicinity of the SWNT tip. The trapping phenomenon is highly sensitive to the external driving frequencies such that even very small changes in driving frequency can have a strong influence on the probability of the location of the particle inside the SWNT. The trapping effect could potentially be employed to realize the atomic scale control of particle position inside an SWNT via the finite adjustment of the external driving frequency. It may also be suggested that the trapping phenomenon could be utilized to develop high-sensitive mass detectors based on a SWNT resonator.
Magnetic and electronic properties of Fe3O4/graphene heterostructures: First principles perspective
Authors: Mi Wenbo , Yang Hua , Cheng Yingchun , Chen Guifeng , Bai Haili
Published: February 2013

Magnetic and electronic properties of Fe3O4(111)/graphene heterostructures are investigated by first principles calculations. Different structural models have been considered, which differ in the interface termination of Fe3O4(111) surface with respect to the same monolayer graphene. In three models, the magnetic moment of Fe(A) has a major change due to less O atoms surrounding Fe(A) atoms than Fe(B). Magnetic moment is enhanced by 8.5%, 18.5%, and 8.7% for models (a), (b), and (c), respectively. Furthermore, the spin polarization of models (a) and (c) is lowered due to the simultaneous occurrence of density of states of spin-up Fe(A) and spin-down Fe(B) at Fermi lever. The spin polarization of model (b) remains the same as that of bulk Fe3O4. Our results suggest that different interface terminations and Fe(A) play an important role in determining the magnetism strength and spin polarization.
Effect of buffer layer and external stress on magnetic properties of flexible FeGa films
Authors: Zhang Xiaoshan , Zhan Qingfeng , Dai Guohong , Liu Yiwei , Zuo Zhenghu , Yang Huali , Chen Bin , Li Run-Wei
Published: February 2013

We systematically investigated the effect of a Ta buffer layer and external stress on the magnetic properties of magnetostrictive Fe81Ga19 films deposited on flexible polyethylene terephthalate (PET) substrates. The Ta buffer layers could effectively smoothen the rough surface of PET. As a result, the FeGa films grown on Ta buffer layers exhibit a weaker uniaxial magnetic anisotropy and lower coercivity, as compared to those films directly grown on PET substrates. By inward and outward bending the FeGa/Ta/PET samples, external in-plane compressive and tensile stresses were applied to the magnetic films. Due to the inverse magnetostrictive effect of FeGa, both the coercivity and squareness of hysteresis loops for FeGa/Ta films could be well tuned under various strains.
Magnetic structure of GdNiSn
Authors: Lee-Hone N. R. , Lemoine P. , Ryan D. H. , Vernière A. , Malaman B.
Published: February 2013

The magnetic structure of the TiNiSi-type GdNiSn compound has been studied by both 155Gd Mössbauer spectrocopy and neutron powder diffraction. The results suggest a square-wave modulated magnetic structure characterized by the propagation vector k = [0.426, 0.351, 0] and Gd magnetic moments of 6.52(15)μB (at 3.6 K) oriented along the c-axis. The results are compared with those of the isotypic RNiSn compounds and with the possible magnetic structures of GdNiSn proposed from earlier 155Gd Mössbauer work.
Transparency controllable silver-based electrode for flexible optoelectronics
Authors: Kim Kisoo , Hong Kihyon , Koo Bonhyeong , Lee Illhwan , Lee Jong-Lam
Published: March 2013

The transmittance of Ag-based electrode increased through suppressing surface plasmons (SPs) coupling. When 10-nm-thick Ag was deposited on small-dielectric-constant (ε) film (LiF, SiO), SPs coupling was induced, resulting in low transmittance (<40%) in visible region. At the Ag/large-ε oxide interface (WO3 and MoO3), SPs were suppressed, and the film showed increased transmittance (∼80%). Organic light emitting diodes using Ag/WO3 (ε: 35) as a transparent electrode showed 1.26 times greater luminance and 32.6% greater power efficiency than using Ag/LiF (ε: 5). These results provide us with an important guideline for enhancing the transmittance of Ag/dielectric film by controlling SPs coupling.
Bandgap opening in Janus-type mosaic graphene
Authors: Yang Mingmei , Zhao Ruiqi , Wang Jinying , Zhang Liming , Xie Qin , Liu Zhongfan , Liu Zhirong
Published: March 2013

We demonstrate a novel Janus-type mosaic graphene (J-MOG) for achieving a ubiquitous bandgap opening by asymmetrical modification with covalently bonded H, F, Cl, and Br on opposing sides of graphene sheet. The theoretical capacity of J-MOG is shown to break the pattern restrictions, giving a robust non-zero gap. Our approach provides an effective pathway for the bandgap engineering of graphene for various electronic applications.
Determination of operating parameters for a GaAs-based polariton laser
Authors: Schmutzler J. , Veit F. , Aßmann M. , Tempel J.-S. , Höfling S. , Kamp M. , Forchel A. , Bayer M.
Published: March 2013

We report on a systematic study of the phase transitions to polariton condensation (PC) and further to cavity lasing in a GaAs-based microcavity with respect to exciton-cavity detuning and lattice temperature. Using far field and time-resolved spectroscopy, we determined the parameter space in which PC can be achieved and the corresponding variation of PC threshold power. We found a lower bound of −12 meV for the exciton-cavity detuning and an upper bound of 90 K for the lattice temperature.
Optical absorption in epitaxial La1−xSrxFeO3 thin films
Authors: Scafetta M D. , Xie Y. J. , Torres M. , Spanier J. E. , May S. J.
Published: March 2013

We report the dependence of optical absorption on Sr concentration in La1−xSrxFeO3 (LSFO) (x≤0.4) perovskite thin films. Strained epitaxial films were deposited on SrTiO3 substrates using oxide molecular beam epitaxy. We find systematic changes in the optical absorption spectra with increasing x including a red-shift of transition energies and the increasing presence of a lower energy transition within the fundamental gap of pure LaFeO3. These results serve as a demonstration of the complex manner in which absorption spectra can be altered in complex oxides via heterovalent A-site substitution.
Heat conduction model for nanowire applications
Authors: Tohmyoh Hironori
Published: March 2013

A heat conduction model for determining the temperature of a nanowire through which a current is passed is proposed. In the model, the total Joule heating arising in the nanowire due to the current is considered until the system reaches a steady state. It is important to determine the positions of the “cold points” in the system, where the temperature is left unchanged by the current. The current required to cut a nanowire is predicted from the model. The mechanism for Joule heat welding is classified depending on the positions of the cold points in the metallic nanowire system.
Quantum confinement of Bi2S3 in glass with magnetic behavior
Authors: Panmand Rajendra P. , Kulkarni Milind V. , Valant Matjaz , Gosavi Suresh W. , Kale Bharat B.
Published: March 2013

The novel Bi2S3 quantum dots (QDs) glass nanosystems with unique magnetic properties have been investigated. The monodispersed QDs of size in the range of 3 to 15 nm were grown in the glass matrix. The optical study of these nanosystems clearly demonstrated the size quantization effect resulting in a pronounced band gap variation with QD size. The magnetic properties of the pristine glass and the Bi2S3 QD glass nanosystems were investigated by VSM and SQUID magnetometer. The pristine glass did not show any ferromagnetism while the Bi2S3 glass nanosystems showed significant and reproducible ferromagnetism. We also investigated the effect of the size of Bi2S3 QDs on the magnetic properties. The saturation magnetization for the 15 nm QD glass-nanosystem (124 memu/g) was observed to be higher as compared to the 3nm QD glass nanosystem (58.2 memu/g). The SQUID measurement gave the excellent hysteresis up to 300K. Surprisingly, the bulk Bi2S3 powder is diamagnetic in nature but Bi2S3 quantum dots glass nanosystem showed the ferromagnetic behavior for the first time. The investigated novel QD glass-nanosystem may have a potential application in spintronic devices and most importantly, this nanosystem can be fabricated in any usable shape as per the device requirement.
Simplified estimation of unsaturated soil hydraulic conductivity using bulk electrical conductivity and particle size distribution
Authors: Neyshabouri Mohammad Reza , Rahmati Mehdi , Doussan Claude , Behroozinezhad Boshra
Published: March 2013

Unsaturated soil hydraulic conductivity K is a fundamental transfer property of soil but its measurement is costly, difficult, and time-consuming due to its large variations with water content (θ) or matric potential (h). Recently, C. Doussan and S. Ruy proposed a method/model using measurements of the electrical conductivity of soil core samples to predict K(h). This method requires the measurement or the setting of a range of matric potentials h in the core samples—a possible lengthy process requiring specialised devices. To avoid h estimation, we propose to simplify that method by introducing the particle-size distribution (PSD) of the soil as a proxy for soil pore diameters and matric potentials, with the Arya and Paris (AP) model. Tests of this simplified model (SM) with laboratory data on a broad range of soils and using the AP model with available, previously defined parameters showed that the accuracy was lower for the SM than for the original model (DR) in predicting K (RMSE of logK = 1.10 for SM v. 0.30 for DR; K in m s–1). However, accuracy was increased for SM when considering coarse- and medium-textured soils only (RMSE of logK = 0.61 for SM v. 0.26 for DR). Further tests with 51 soils from the UNSODA database and our own measurements, with estimated electrical properties, confirmed good agreement of the SM for coarse–medium-textured soils (<35–40% clay). For these textures, the SM also performed well compared with the van Genuchten–Mualem model. Error analysis of SM results and fitting of the AP parameter showed that most of the error for fine-textured soils came from poorer adequacy of the AP model’s previously defined parameters for defining the water retention curve, whereas this was much less so for coarse-textured soils. The SM, using readily accessible soil data, could be a relatively straightforward way to estimate, in situ or in the laboratory, K(h) for coarse–medium-textured soils. This requires, however, a prior check of the predictive efficacy of the AP model for the specific soil investigated, in particular for fine-textured/structured soils and when using previously defined AP parameters.
Task-related “cortical” bursting depends critically on basal ganglia input and is linked to vocal plasticity
Authors: Kojima Satoshi , Kao Mimi H. , Doupe Allison J.
Published: March 2013

Basal ganglia-thalamocortical circuits are critical for motor control and motor learning. Classically, basal ganglia nuclei are thought to regulate motor behavior by increasing or decreasing cortical firing rates, and basal ganglia diseases are assumed to reflect abnormal overall activity levels. More recent studies suggest instead that motor disorders derive from abnormal firing patterns, and have led to the hypothesis that surgical treatments, such as pallidotomy, act primarily by eliminating pathological firing patterns. Surprisingly little is known, however, about how the basal ganglia normally influence task-related cortical activity to regulate motor behavior, and how lesions of the basal ganglia influence cortical firing properties. Here, we investigated these questions in a songbird circuit that has striking homologies to mammalian basal ganglia-thalamocortical circuits but is specialized for singing. The “cortical” outflow nucleus of this circuit is required for song plasticity and normally exhibits increased firing during singing and song-locked burst firing. We found that lesions of the striato-pallidal nucleus in this circuit prevented hearing-dependent song changes. These basal ganglia lesions also stripped the cortical outflow neurons of their patterned burst firing during singing, without changing their spontaneous or singing-related firing rates. Taken together, these results suggest that the basal ganglia are essential not for normal cortical firing rates but for driving task-specific cortical firing patterns, including bursts. Moreover, such patterned bursting appears critical for motor plasticity. Our findings thus provide support for therapies that aim to treat basal ganglia movement disorders by normalizing firing patterns.
STUDIES OF NGC 6720 WITH CALIBRATED HST/WFC3 EMISSION-LINE FILTER IMAGES. I. STRUCTURE AND EVOLUTION*
,†
Authors: O'Dell C. R. , Ferland G. J. , Henney W. J. , Peimbert M.
Published: March 2013

We have performed a detailed analysis of the Ring Nebula (NGC 6720) using Hubble Space Telescope WFC3 images and derived a new three-dimensional model. Existing high spectral resolution spectra played an important supplementary role in our modeling. It is shown that the Main Ring of the nebula is an ionization-bounded irregular non-symmetric disk with a central cavity and perpendicular extended lobes pointed almost toward the observer. The faint outer halos are determined to be fossil radiation, i.e., radiation from gas ionized in an earlier stage of the nebula when it was not ionization bounded. The narrowband WFC3 filters that isolate some of the emission lines are affected by broadening on their short wavelength side and all the filters were calibrated using ground-based spectra. The filter calibration results are presented in an appendix.
Optimal digestion theory does not predict the effect of pathogens on intestinal plasticity
Authors: Venesky Matthew D. , Hanlon Shane M. , Lynch Kyle , Parris Matthew J. , Rohr Jason R.
Published: February 2013

One prediction of optimal digestion theory is that organisms will increase the relative length of their digestive tracts when food resources become limited. We used theory of optimal digestion to test whether tadpoles can adjust the relative length of their intestines when challenged with the fungal pathogen
Batrachochytrium dendrobatidis
(
Bd
). The degree of tadpole mouthpart damage, a symptom of
Bd
infections that reduces food consumption, was associated positively with the length of tadpole intestines relative to their body size, consistent with optimal digestion theory. After controlling for mouthpart damage, tadpoles exposed to
Bd
had shorter intestines relative to their body size, opposite to the predictions of optimal digestion theory. One explanation of why tadpoles with higher
Bd
loads have shorter relative intestinal lengths is that they divert energy from maintaining intestinal and overall growth towards anti-parasite defences.
In vitro
and
in vivo
investigations on the effects of low-density lipoprotein concentration polarization and haemodynamics on atherosclerotic localization in rabbit and zebrafish
Authors: Xie Xiang , Tan Ju , Wei Dangheng , Lei Daoxi , Yin Tieying , Huang Junli , Zhang Xiaojuan , Qiu Juhui , Tang Chaojun , Wang Guixue
Published: March 2013

Atherosclerosis (AS) commonly occurs in the regions of the arterial tree with haemodynamic peculiarities, including local flow field disturbances, and formation of swirling flow and vortices. The aim of our study was to confirm low-density lipoprotein (LDL) concentration polarization in the vascular system
in vitro
and
in vivo
, and investigate the effects of LDL concentration polarization and flow field alterations on atherosclerotic localization. Red fluorescent LDL was injected into optically transparent Flk1: GFP zebrafish embryos, and the LDL distribution in the vascular lumen was investigated
in vivo
using laser scanning confocal microscopy. LDL concentration at the vascular luminal surface was found to be higher than that in the bulk. The flow field conditions in blood vessel segments were simulated and measured, and obvious flow field disturbances were found in the regions of vascular geometry change. The LDL concentration at the luminal surface of bifurcation was significantly higher than that in the straight segment, possibly owing to the atherogenic effect of disturbed flow. Additionally, a stenosis model of rabbit carotid arteries was generated. Atherosclerotic plaques were found to have occurred in the stenosis group and were more severe in the stenosis group on a high-fat diet. Our findings provide the first ever definite proof that LDL concentration polarization occurs in the vascular system
in vivo
. Both lipoprotein concentration polarization and flow field changes are involved in the infiltration/accumulation of atherogenic lipids within the location of arterial luminal surface and promote the development of AS.
Design of geometric phase gates and controlling the dynamic phase for a two-qubit Ising model in magnetic fields
Authors: Amniat-Talab M. , Jahromi H. Rangani
Published: March 2013

We investigate how to obtain a non-trivial geometric phase gate for a two-qubit spin chain, with Ising interaction in different magnetic fields. Indeed, one of the spins is driven by a time-varying rotating magnetic field, and the other is coupled with a static magnetic field in the direction of the rotation axis. This is an interesting problem both for the purpose of measuring the geometric phases and in quantum computing applications. It is shown that the static magnetic field does not change the adiabatic states of the system, and it does not affect the geometric phases, whereas it may be used to control the dynamic phases. In addition, by considering the exact two-spin adiabatic geometric phases, we find that a non-trivial two-spin unitary transformation, purely based on Berry phases, can be obtained by using two consecutive cycles with opposite directions of the magnetic fields, opposite signs of the interaction constant and the phase shift of the rotating magnetic field. In addition, in the non-adiabatic case, starting with a certain initial state, a cycle can be achieved and thus the Aharonov–Anandan phase is calculated.
Phenotypic engineering of sperm-production rate confirms evolutionary predictions of sperm competition theory
Authors: Sekii Kiyono , Vizoso Dita B. , Kuales Georg , De Mulder Katrien , Ladurner Peter , Schärer Lukas
Published: February 2013

Sperm production is a key male reproductive trait and an important parameter in sperm competition theory. Under sperm competition, paternity success is predicted to depend strongly on male allocation to sperm production. Furthermore, because sperm production is inherently costly, individuals should economize in sperm expenditure, and conditional adjustment of the copulation frequency according to their sperm availability may be expected. However, experimental studies showing effects of sperm production on mating behaviour and paternity success have so far been scarce, mainly because sperm production is difficult to manipulate directly in animals. Here, we used phenotypic engineering to manipulate sperm-production rate, by employing dose-dependent RNA interference (RNAi) of a spermatogenesis-specific gene,macbol1, in the free-living flatwormMacrostomum lignano. We demonstrate (i) that our novel dose-dependent RNAi approach allows us to induce high variability in sperm-production rate; (ii) that a reduced sperm-production rate is associated with a decreased copulation frequency, suggesting conditional adjustment of mating behaviour; and (iii) that both sperm production and copulation frequency are important determinants of paternity success in a competitive situation, as predicted by sperm competition theory. Our study clearly documents the potential of phenotypic engineering via dose-dependent RNAi to test quantitative predictions of evolutionary theory.
Rapid preflexes in smooth adhesive pads of insects prevent sudden detachment
Authors: Endlein Thomas , Federle Walter
Published: February 2013

Many insects possess adhesive organs that can produce extreme attachment forces of more than 100 times body weight but they can rapidly release adhesion to allow locomotion. During walking, weaver ants (Oecophylla smaragdina) use only a fraction of their maximally available contact area, even upside-down on a smooth surface. To test whether the reduced contact area makes the ants more susceptible to sudden and unexpected detachment forces, for example, by rain or wind gusts, we investigated the reaction of untethered ants to rapid horizontal displacements of the substrate. High-speed video recordings revealed that the pad's contact area could more than double within the first millisecond after the perturbation. This contact area expansion is much faster than any neuromuscular reflex and therefore represents a passive ‘preflex’, resulting from the mechanical properties and geometrical arrangement of the (pre-)tarsus. This preflex reaction protects ants effectively against unexpected detachment, and allows them to use less contact area during locomotion. Contact area expanded most strongly when the substrate displacement generated a pull along the axis of the tarsus, showing that the ants' preflex is direction-dependent. The preflex may be based on the ability of Hymenopteran adhesive pads to unfold when pulled towards the body. We tested Indian stick insects (Carausius morosus), which have smooth pads that lack this motility. Similar to the ants, they showed a rapid and direction-dependent expansion of the contact area mainly in the lateral direction. We propose that the preflex reaction in stick insects is based on the reorientation of internal cuticle fibrils in a constant-volume system, whereas the ants' pad cuticle is probably not a hydrostat, and pad extension is achieved by the arcus, an endoscelerite of the arolium.