bluuebunny/crossref_metadata_2025 huggingface dataset:
Modeling population growth and site specific control of the invasive Lantana camara L. (Verbenaceae) under differing fire regimes
Authors: Osunkoya Olusegun O. , Perrett Christine , Fernando Chandima , Clark Cameron , Raghu Sathyamurthy
Published: March 2013

It is at the population level that an invasion either fails or succeeds. Lantana camara L. (Verbenaceae) is a weed of great significance in Queensland Australia and globally but its whole life‐history ecology is poorly known. Here we used 3 years of field data across four land use types (farm, hoop pine plantation and two open eucalyptus forests, including one with a triennial fire regime) to parameterise the weed's vital rates and develop size‐structured matrix models. Lantanacamara in its re‐colonization phase, as observed in the recently cleared hoop pine plantation, was projected to increase more rapidly (annual growth rate, λ = 3.80) than at the other three sites (λ 1.88–2.71). Elasticity analyses indicated that growth contributed more (64.6 %) to λ than fecundity (18.5 %) or survival (15.5 %), while across size groups, the contribution was of the order: juvenile (19–27 %) ≥ seed (17–28 %) ≥ seedling (16–25 %) > small adult (4–26 %) ≥ medium adult (7–20 %) > large adult (0–20 %). From a control perspective it is difficult to determine a single weak point in the life cycle of lantana that might be exploited to reduce growth below a sustaining rate. The triennial fire regime applied did not alter the population elasticity structure nor resulted in local control of the weed. However, simulations showed that, except for the farm population, periodic burning could work within 4–10 years for control of the weed, but fire frequency should increase to at least once every 2 years. For the farm, site‐specific control may be achieved by 15 years if the biennial fire frequency is tempered with increased burning intensity.
The Ultrasonic Investigation of Phase Transition in Olive Oil up to 0.7 GPa
Authors: Rostocki A. J. , Tarakowski R. , Kiełczyński P. , Szalewski M. , Balcerzak A. , Ptasznik S.
Published: March 2013

This paper presents measurements of sound velocity and attenuation in olive oil, with known chemical composition, as a function of pressure, within the range of pressure up to 0.7 GPa. Dependencies of sound velocity, relative ultrasonic wave attenuation, volume, and adiabatic compressibility on pressure show discontinuities. This proves the existence of the first order phase transition in olive oil (liquid to solid‐like phase transition). Rapid and large changes in relative attenuation testify to the existence of a phase transition in olive oil. Moreover, the kinetics of phase transition was also investigated. Measurement of acoustic wave velocity and relative attenuation in olive oil during the phase transition and in the high‐pressure phase is a novelty. The results obtained can be useful in the development of new methods in food (edible oils) control, processing, and preservation.
Multifractal formalism for Benedicks–Carleson quadratic maps
Authors: CHUNG YONG MOO , TAKAHASI HIROKI
Published: March 2013

For a positive measure set of non-uniformly expanding quadratic maps on the interval we effect a multifractal formalism, i.e., decompose the phase space into level sets of time averages of a given continuous function and consider the associated Birkhoff spectrum which encodes this decomposition. We derive a formula which relates the Hausdorff dimension of level sets to entropies and Lyapunov exponents of invariant probability measures, and then use this formula to show that the spectrum is continuous. In order to estimate the Hausdorff dimension from above, one has to ‘see’ sufficiently many points. To this end, we construct a family of towers. Using these towers we establish a large deviation principle of empirical distributions, with Lebesgue as a reference measure.
Oppegård kirke, Oppegård, Norway: fixing the location where Roald Amundsen revealed his ‘minor diversion’
Authors: Capelotti P.J. , Barr Susan
Published: March 2013

After learning in the first week of September 1909 that the North Pole had been claimed, the career and prospects of the Norwegian explorer Roald Amundsen hung in the balance. Scheduled to lead an exploration of the north polar basin, Amundsen suddenly found himself without adequate funding or a clear objective. His self-described ‘coup’ to turn southwards and reach for the South Pole was perhaps the most dramatic and best-kept secret in the history of polar exploration. Amundsen shared his decision only with a very select few, including his brother and manager, Leon Amundsen, a scene dramatised in the 1985 television mini-series The last place on earth. The location used in the film is identified at the unusual grave markers of the Ingier family outside Oppegård kirke in Oppegård, Norway, about five km from the site of Amundsen's home on Bunnefjorden, a branch of Oslofjord.
A NOTE ON CREDIT MARKET DEVELOPMENT AND HUMAN CAPITAL ACCUMULATION
Authors: Ho Wai-Hong
Published: March 2013

This paper explores the interplay between credit market development and human capital accumulation in a two-period overlapping-generations economy with asymmetric information under the assumption that young lenders channel credits to young borrowers and acquire education. We find that, at the self-selection equilibrium, lenders will allocate more time to acquire education if the cost of screening borrowers falls. Furthermore, a longer duration of lenders' schooling time suppresses borrowers' incentive to cheat thereby enabling lenders to screen less frequently. Our preliminary cross-country empirical analysis appears to support these findings.
Pioneers in Optics: Étienne-Jules Marey and Paul Gottlieb Nipkow
Authors: Davidson Michael W.
Published: March 2013

Étienne-Jules Marey was born in Beaune, France, on March 5, 1830, to a wine merchant and a teacher. To satisfy his father's wishes, he decided to study medicine, attending the Faculty of Medicine in Paris. Marey's fascination with both animals and mechanics inspired him to concentrate on physiology, and it was during his investigations of this field that he became involved in optics.
The Ascent of 3D X-ray Microscopy in the Laboratory
Authors: Merkle Arno P. , Gelb Jeff
Published: March 2013

X rays are universally valued for their ability to penetrate opaque objects. It is only within the past few decades that their short wavelengths have also been exploited to provide 3D imaging of the objects' interiors with resolution well beyond that of light microscopy (LM) in a wide variety of applications. This article explores X-ray imaging as a quantitative sub-micron nanoscale microscopy technique, and specifically its emergent role within the context of the central microscopy laboratory.
Long-Travel Piezomotors for Microscopy Applications
Authors: Jordan Scott , Vorndran Stefan
Published: March 2013

Recent advances in imaging techniques capable of light microscopy resolutions below the Abbe diffraction limit have challenged microscopy equipment designers to pursue conflicting goals for components such as sample positioning and scanning stages and focusing mechanisms. For the super-resolution light microscopy, the positions of these components must be controlled in more degrees of freedom with higher dynamic and static accuracy, yet emerging applications demand higher speeds, finer resolutions, tighter synchronization, nanoscale stabilities, and longer travels to meet scientific and optical requirements. Meanwhile the practicality of today's tight budgetary situations cannot be overlooked, both in terms of purchase price and process throughput. Furthermore, of course, compactness is prized to facilitate close working distances and dense optical configurations.
Using biodiversity to link agricultural productivity with environmental quality: Results from three field experiments in Iowa
Authors: Liebman Matt , Helmers Matthew J. , Schulte Lisa A. , Chase Craig A.
Published: March 2013

Agriculture in the US Corn Belt is under increasing pressure to produce greater quantities of food, feed and fuel, while better protecting environmental quality. Key environmental problems in this region include water contamination by nutrients and herbicides emitted from cropland, a lack of non-agricultural habitat to support diverse communities of native plants and animals, and a high level of dependence on petrochemical energy in the dominant cropping systems. In addition, projected changes in climate for this region, which include increases in the proportion of precipitation coming from extreme events could make soil and water conservation in existing cropping systems more difficult. To address these challenges we have conducted three cropping systems projects in central Iowa: the Marsden Farm Cropping Systems experiment, the Science-based Trials of Row-crops Integrated with Prairies (STRIPs) experiment, and the Comparison of Biofuel Systems (COBS) experiment. Results from these experiments indicate that (1) diversification of the dominant corn–soybean rotation with small grains and forage legumes can permit substantial reductions in agrichemical and fossil hydrocarbon use without compromising yields or profitability; (2) conversion of small amounts of cropland to prairie buffer strips can provide disproportionately large improvements in soil and water conservation, nutrient retention, and densities of native plants and birds; and (3) native perennial species can generate large amounts of biofuel feedstocks and offer environmental benefits relative to corn- and soybean-based systems, including greater carbon inputs to soil and large reductions in nitrogen emissions to drainage water. Increasing biodiversity through the strategic integration of perennial plant species can be a viable strategy for reducing reliance on purchased inputs and for increasing agroecosystem health and resilience in the US Corn Belt.
Diversification and ecosystem services for conservation agriculture: Outcomes from pastures and integrated crop–livestock systems
Authors: Sanderson Matt A. , Archer David , Hendrickson John , Kronberg Scott , Liebig Mark , Nichols Kris , Schmer Marty , Tanaka Don , Aguilar Jonathan
Published: March 2013

Conservation agricultural systems rely on three principles to enhance ecosystem services: (1) minimizing soil disturbance, (2) maximizing soil surface cover and (3) stimulating biological activity. In this paper, we explore the concept of diversity and its role in maximizing ecosystem services from managed grasslands and integrated agricultural systems (i.e., integrated crop–livestock–forage systems) at the field and farm level. We also examine trade-offs that may be involved in realizing greater ecosystem services. Previous research on livestock production systems, particularly in pastureland, has shown improvements in herbage productivity and reduced weed invasion with increased forage diversity but little response in terms of animal production. Managing forage diversity in pastureland requires new tools to guide the selection and placement of plant mixtures across a farm according to site suitability and the goals of the producer. Integrated agricultural systems embrace the concept of dynamic cropping systems, which incorporates a long-term strategy of annual crop sequencing that optimizes crop and soil use options to attain production, economic and resource conservation goals by using sound ecological management principles. Integrating dynamic cropping systems with livestock production increases the complexity of management, but also creates synergies among system components that may improve resilience and sustainability while fulfilling multiple ecosystem functions. Diversified conservation agricultural systems can sustain crop and livestock production and provide additional ecosystem services such as soil C storage, efficient nutrient cycling and conservation of biodiversity.
Coherent tunnelling across a quantum point contact in the quantum Hall regime
Authors: Martins F. , Faniel S. , Rosenow B. , Sellier H. , Huant S. , Pala M. G. , Desplanque L. , Wallart X. , Bayot V. , Hackens B.
Published: March 2013

The unique properties of quantum hall devices arise from the ideal one-dimensional edge states that form in a two-dimensional electron system at high magnetic field. Tunnelling between edge states across a quantum point contact (QPC) has already revealed rich physics, like fractionally charged excitations, or chiral Luttinger liquid. Thanks to scanning gate microscopy, we show that a single QPC can turn into an interferometer for specific potential landscapes. Spectroscopy, magnetic field and temperature dependences of electron transport reveal a quantitatively consistent interferometric behavior of the studied QPC. To explain this unexpected behavior, we put forward a new model which relies on the presence of a quantum Hall island at the centre of the constriction as well as on different tunnelling paths surrounding the island, thereby creating a new type of interferometer. This work sets the ground for new device concepts based on coherent tunnelling.
Random pinning glass transition: Hallmarks, mean-field theory and renormalization group analysis
Authors: Cammarota Chiara , Biroli Giulio
Published: March 2013

We present a detailed analysis of glass transitions induced by pinning particles at random from an equilibrium configuration. We first develop a mean-field analysis based on the study of p-spin spherical disordered models and then obtain the three-dimensional critical behavior by the Migdal-Kadanoff real space renormalization group method. We unveil the important physical differences with the case in which particles are pinned from a random (or very high temperature) configuration. We contrast the pinning particles approach to the ones based on biasing dynamical trajectories with respect to their activity and on coupling to equilibrium configurations. Finally, we discuss numerical and experimental tests.
Shock-induced phase transitions of α-Ce3Al
Authors: Fang Yuankan , Meng Chuanmin , Zhu Wenjun , He Duanwei , Du Gaohui , Jiang Jianzhong
Published: March 2013

A series of shock compression experiments on hexagonal α-Ce3Al have been carried out using a two-stage light gas gun. No phase transition was observed in the recovered sample shock compressed at 23.5 GPa. However, as the shock pressure was increased to 27.3 GPa, a face-centered cubic Ce3Al phase was detected in the samples recovered at ambient conditions. Furthermore, a Ce2Al phase was found in the 37.1 GPa shocked sample with a space group Fd-3m and lattice parameter a = 8.26(1) Å. These Ce-based alloys may have potential industrial applications due to the heavy-fermion related properties.
Characterization of the supersonic flowing microwave discharge using two dimensional plasma tomography
Authors: Nikolić M. , Samolov A. , Čučkov F. , Popović S. , Vušković L. , Godunov A.
Published: March 2013

A tomographic numerical method based on the two-dimensional Radon formula for a cylindrical cavity has been employed for obtaining spatial distributions of the argon excited levels. The spectroscopy measurements were taken at different positions and directions to observe populations of excited species in the plasmoid region and the corresponding excitation temperatures. Excited argon states are concentrated near the tube walls, thus, confirming the assumption that the post discharge plasma is dominantly sustained by travelling surface wave. An automated optical measurement system has been developed for reconstruction of local plasma parameters of the plasmoid structure formed in an argon supersonic flowing microwave discharge. The system carries out angle and distance measurements using a rotating, flat mirror, as well as two high precision stepper motors operated by a microcontroller-based system and several sensors for precise feedback control.
Airy beam induced optical routing
Authors: Rose Patrick , Diebel Falko , Boguslawski Martin , Denz Cornelia
Published: March 2013

We present an all-optical routing scheme based simultaneously on optically induced photonic structures and the Airy beam family. The presented work utilizes these accelerating beams for the demonstration of an all-optical router with individually addressable output channels. In addition, we are able to activate multiple channels at the same time providing us with an optically induced splitter with configurable outputs. The experimental results are corroborated by corresponding numerical simulations.
Extreme doping sensitivity of the ordering direction in GdCo12−xFexB6
Authors: Lee-Hone N. R. , Ryan D. H. , Isnard O. , Diop L. V. B. , Cadogan J. M.
Published: March 2013

155Gd Mössbauer spectroscopy has been used to investigate the magnetic ordering direction of GdCo12−xFexB6 (0≤x≤3) at 5 K. The moment orientation was found to be extremely sensitive to doping with as little as ∼4% Fe doping (0.5 Fe/f.u.) causing the moment orientation to change from the c-axis to the basal plane. Including results from earlier 57Fe-doping work suggests that the axial–basal boundary may lie below 0.5% Fe doping (∼0.06 Fe/f.u.). As the ordering directions for the other R Co12B6 compounds have all been derived from 57Fe-doped samples, a re-evaluation of these compounds may be necessary.
Magnetic permeability of Si-rich (FeCoNi)-based nanocrystalline alloy: Thermal stability in a wide temperature range
Authors: Wang Jia , Wang Zhi , Jia Yun-yun , Shi Rui-min , Wen Zhuan-ping , Kang Hui-juan
Published: March 2013

Structure and magnetic properties of as-quenched and annealed Ni5(Fe0.5Co0.5)68.5Si17.5Nb3B5Cu1 alloys were investigated by differential scanning calorimetry, x-ray diffraction, transmission electron microscopy, and the temperature dependence of initial permeability (μi-T curves) from room temperature up to 680 °C. The as-quenched sample exhibits a higher secondary crystallization temperature (Tx2) and a larger crystallized interval temperature (ΔTx = Tx2−Tx1) for precipitating the single soft magnetic crystal phase. Annealing temperature (Ta) exerts a significant effect on room- and high-temperature μi for samples heating-cooling cycled at 510–680 °C. When Ta is at 640 °C, an excellent high temperature magnetic softness was observed in a wider temperature range, and the μi above 1000 at 10 KHz can keep up to 600 °C. The origin of this improved high-temperature magnetic softness was also analyzed.
Anisotropy of crystal growth mechanisms, dielectricity, and magnetism of multiferroic Bi2FeMnO6 thin films
Authors: Liu P. , Cheng Z. X. , Du Y. , Feng L. Y. , Fang H. , Wang X. L. , Dou S. X.
Published: March 2013

Epitaxial Bi2FeMnO6 (BFMO) thin films deposited on various Nb:SrTiO3 substrates show that the lattice parameters are very sensitive to epitaxial strains. Compressive and tensile strains are induced to the in-plane lattice constants of the (100) and (111) oriented films, respectively, while that of the (110) oriented thin film stay unstrained. The thin films also exhibit a strongly anisotropic growth habit depending on the substrate. Spiral growth, such as in the (100) BFMO film, is unique in samples prepared by pulsed laser deposition. Extrinsic dielectric constants at low frequencies are attributed to oxygen vacancies via the Maxwell-Wagner effect. All the samples show saturated hysteresis loops with very small coercive fields at 200 K, indicating the presence of weak ferromagnetism.
Compound synchronization of four memristor chaotic oscillator systems and secure communication
Authors: Sun Junwei , Shen Yi , Yin Quan , Xu Chengjie
Published: March 2013

In this paper, a novel kind of compound synchronization among four chaotic systems is investigated, where the drive systems have been conceptually divided into two categories: scaling drive systems and base drive systems. Firstly, a sufficient condition is obtained to ensure compound synchronization among four memristor chaotic oscillator systems based on the adaptive technique. Secondly, a secure communication scheme via adaptive compound synchronization of four memristor chaotic oscillator systems is presented. The corresponding theoretical proofs and numerical simulations are given to demonstrate the validity and feasibility of the proposed control technique. The unpredictability of scaling drive systems can additionally enhance the security of communication. The transmitted signals can be split into several parts loaded in the drive systems to improve the reliability of communication.
Hole doped Dirac states in silicene by biaxial tensile strain
Authors: Kaloni T. P. , Cheng Y. C. , Schwingenschlögl U.
Published: March 2013

The effects of biaxial tensile strain on the structure, electronic states, and mechanical properties of silicene are studied by ab-initio calculations. Our results show that up to 5% strain the Dirac cone remains essentially at the Fermi level, while higher strain induces hole doped Dirac states because of weakened Si–Si bonds. We demonstrate that the silicene lattice is stable up to 17% strain. It is noted that the buckling first decreases with the strain (up to 10%) and then increases again, which is accompanied by a band gap variation. We also calculate the Grüneisen parameter and demonstrate a strain dependence similar to that of graphene.
Contribution of radial dopant concentration to the thermoelectric properties of core-shell nanowires
Authors: Martinez Julio A. , Cho Jeong-Hyun , Liu Xiaohua , Luk Ting S. , Huang Jianyu , Picraux S. T. , Sullivan John P. , Swartzentruber B. S.
Published: March 2013

We report the thermoelectric characteristics of core-shell p-type germanium nanowires (GeNWs) (lightly doped core, heavily doped shell). Overall, the thermoelectric characteristics are dominated by the heavily doped shell. Experimental data indicate that surface states produce dopant deactivation when the heavily doped shell is removed. Under this situation, the thermoelectric figure of merit is degraded. Etching the heavily doped shell resulted in a rough germanium nanowire with a thermal conductivity close to 1.1 W/m-K at 300 K, which is one of the smallest k measured for nanowires and comparable to the thermal conductivity of bulk SiO2.
Thin-film transistors fabricated by low-temperature process based on Ga- and Zn-free amorphous oxide semiconductor
Authors: Aikawa Shinya , Darmawan Peter , Yanagisawa Keiichi , Nabatame Toshihide , Abe Yoshiyuki , Tsukagoshi Kazuhito
Published: March 2013

We propose the use of indium tungsten oxide (IWO) as a channel material for thin-film transistors (TFTs). In the present study, an IWO film was deposited at room temperature by means of DC magnetron sputtering and then annealed at 100 °C in N2 prior to formation of Au source and drain electrodes. Analysis using X-ray diffraction and transmission electron microscopy revealed that the film remained amorphous even after the post-deposition annealing treatment. TFTs fabricated using a Si substrate as a back-gate electrode showed good performance, with a saturation field-effect mobility of 19.3 cm2 · V−1 · s−1, an on/off current ratio of 8.9 × 109.
Ferromagnetism and electronic transport in epitaxial Ge1−xFexTe thin film grown by pulsed laser deposition
Authors: Liu J. D. , Miao X. S. , Tong F. , Luo W. , Xia Z. C.
Published: March 2013

The magnetic and transport behaviors of epitaxial Ge1−xFexTe thin film with low Fe concentration (x = 0.02) deposited by pulsed laser deposition have been investigated. Temperature-dependent magnetization and anomalous Hall effect result in a Curie temperature of ∼160 K. A high hole density resulting from crystalline defects induces a long-range ferromagnetism. Competition between spontaneous magnetization and thermal effects leads to a change of magnetoresistance ratio from positive to negative with increasing temperature. The minimum carrier concentration is achieved at 160 K, which may correspond to ferromagnetic-paramagnetic phase transition, implying that ferromagnetism is closely related to transport behaviors.
High magnetocrystalline anisotropy in oxides with near cubic local environments
Authors: Chen Xin , Parker David , Ong Khuong P. , Du Mao-Hua , Singh David J.
Published: March 2013

We investigate magnetic coercivity in double perovskite related oxides, based on first principles calculations of the magnetic properties and magnetocrystalline anisotropy. The Re-based materials studied have large magnetic moments on Re (nearly 1 μB in Sr2CrReO6) and relatively large magnetocrystalline anisotropy energies. This is unexpected considering the octahedral coordination. Based on this, we studied an intergrowth of double perovskite Sr2CrReO6-like and SrTiO3-like blocks. We obtain a very high predicted coercive field in excess of 90 T. This shows that it is possible to have large coercive fields arising from magnetocrystalline anisotropy associated with transition elements in nearly cubic local environments.
City of felt and concrete: Negotiating cultural hybridity in Mongolia's capital of Ulaanbaatar
Authors: Diener Alexander C. , Hagen Joshua
Published: March 2013

Capital cities play an integral role in the construction of national identity. This is particularly true when the capital is the country's only major urban center. Over the course of its history, Mongolia's capital of Ulaanbaatar has been periodically reshaped to reflect competing trajectories of national culture. This article examines the evolving symbolism of architecture, urban design, and public space in Ulaanbaatar as a means of exploring Mongolia's complex negotiation between its traditional culture (mobile pastoralism and Shamanism/Buddhism), its socialist legacy, and globalization. Amidst the rampant social change of the last two decades, rather ambiguous national narratives have emerged in Mongolia. Like the capital's cityscape, these narratives reflect aspects of both recent and distant pasts, as well as contemporary economic, political, and social realities. This article reveals how increasingly palpable global economic and cultural practices are fomenting material change in the current phase of Ulaanbaatar's evolution. A combination of secondary source research and observations drawn from several months of fieldwork provide the basis for a discussion of the city's role as a forum for cultural contestation and national reform.
Between fragmenting and multiplying: Scale-shift processes in Serbian and Croatian antiwar activisms
Authors: Bilić Bojan
Published: March 2013

This paper follows the almost contemporaneous emergence of the two primary antiwar initiatives in Belgrade and Zagreb to explore how they acted as hotbeds from which permanent human rights organizations appeared in the newly created nation-states. Drawing mostly upon in-depth interviews with antiwar activists from Serbia and Croatia, I argue that the dominant patterns of protest expansion were different in the two countries. While cooperation and tensions existed within both antiwar groups, the Antiwar Campaign of Croatia acted as a broker, leading toward the multiplication of civic initiatives; on the other hand, the Belgrade Center for Antiwar Action was characterized by ideological, professional, and personal divisions, which caused a rapid fragmentation of antiwar undertakings. This paper outlines the main reasons for such expansion patterns (scale-shift processes) and discusses them in the light of recent theoretical advances in political contention studies.
MgSO4·11H2O and MgCrO4·11H2O based on time-of-flight neutron single-crystal Laue data
Authors: Fortes A. Dominic , Wood Ian G. , Gutmann Matthias J.
Published: March 2013

Hexaaquamagnesium(II) sulfate pentahydrate, [Mg(H2O)6]SO4·5H2O, and hexaaquamagnesium(II) chromate(II) pentahydrate, [Mg(H2O)6][CrO4]·5H2O, are isomorphous, being composed of hexaaquamagnesium(II) octahedra, [Mg(H2O)6]2+, and sulfate (chromate) tetrahedral oxyanions, SO42−(CrO42−), linked by hydrogen bonds. There are two symmetry-inequivalent centrosymmetric octahedra:M1 at (0, 0, 0) donates hydrogen bonds directly to the tetrahedral oxyanion,T1, at (0.405, 0.320, 0.201), whereas theM2 octahedron at (0, 0, {1 \over 2}) is linked to the oxyanionviafive interstitial water molecules. Substitution of CrVIfor SVIleads to a substantial expansion ofT1, since the Cr—O bond is approximately 12% longer than the S—O bond. This expansion is propagated through the hydrogen-bonded framework to produce a 3.3% increase in unit-cell volume; the greatest part of this chemically induced strain is manifested along theb* direction. The hydrogen bonds in the chromate compound mitigate ∼20% of the expected strain due to the larger oxyanion, becoming shorter (i.e.stronger) and more linear than in the sulfate analogue. The bifurcated hydrogen bond donated by one of the interstitial water molecules is significantly more symmetrical in the chromate analogue.
Three isomorphous two-dimensional coordination polymers generated from a benzimidazole bridging ligand and ZnX2(X= Cl, Br and I)
Authors: Zhang Yue-Feng , Ma Jian-Ping , Liu Qi-Kui , Dong Yu-Bin
Published: March 2013

A novel bridging asymmetric benzimidazole ligand, 4-{2-[3-(pyridin-4-yl)phenyl]-1H-benzimidazol-1-ylmethyl}benzoic acid, was used to construct three isomorphous two-dimensional coordination polymers, namelycatena-poly[chlorido(μ3-4-{2-[3-(pyridin-4-yl)phenyl]-1H-benzimidazol-1-ylmethyl}benzoato)zinc(II)], [Zn(C26H18N3O2)Cl]n, (I), and the bromide, (II), and iodide, (III), analogues. Neighbouring two-dimensional networks are stacked into three-dimensional frameworksviainterlayer π–π interactions. The luminescent properties of (I)–(III) were investigated and they display an obvious red-shift in the solid state at room temperature.
GaSb-based infrared detectors utilizing InAsPSb absorbers
Authors: Klem John F. , Hawkins Samuel D. , Kim Jin K. , Leonhardt Darin , Shaner Eric A. , Fortune Torben R. , Keeler Gordon A.
Published: March 2013

InPSb and InAsPSb have been investigated for use as absorber materials in GaSb-based n-type/barrier/n-type (nBn) detectors with cutoff wavelengths shorter than 4.2 μm. The growth temperature window for high-quality InPSb lattice-matched to GaSb by molecular beam epitaxy is approximately 440–460 °C. InPSb films with thicknesses greater than approximately 1 μm or films grown outside this temperature window have high densities of large defects, with films grown at lower temperatures exhibiting evidence of significant phase separation. In contrast, InAsPSb films can be grown with excellent surface morphologies and no apparent phase separation over a wide temperature range. InAsPSb samples with low-temperature photoluminescence between 3.0 and 3.4 μm and lattice mismatch of less than 1 × 10−3 have been grown, although both photoluminescence and x-ray diffraction data exhibit peak splitting indicative of compositional nonuniformity. AlAsSb-barrier nBn detectors with InPSb and InAsPSb absorbers have been fabricated. At 160 K, InPSb-absorber devices have a photocurrent responsivity edge at approximately 2.8 μm and a dark current of approximately 1.4 × 10−7 A/cm2, and InAsPSb devices with responsivity edges of 3.1–3.2 μm have a dark current of 2.3 × 10−8 A/cm2. Both InPSb and InAsPSb devices require significant reverse bias for full photocurrent collection at low temperature, suggesting the existence of an undesirable valence band energy discontinuity. The temperature dependence of dark current indicates that it is dominated by a mechanism other than generation in the undepleted absorber region.
Removing Coins from a Dice Tower: No Magic — Just Physics
Authors: Vollmer Michael , Möllmann Klaus-Peter
Published: March 2013

There are phenomena that seem impossible—at first glance. But some knowledge of physics can often allow us to plan and also perform the seemingly impossible without any magic. Here is a very simple experiment that can be done with a whole group of students. I learned about it from an activity in a science center, where it was posed as a magical puzzle.
High school physics teachers' assessment of student preparation
Authors: White Susan
Published: March 2013

Student preparation can be quite nuanced. Not only have students been exposed to a variety of preparatory classes and outside influences, but students also vary in their commitment and approach to their current classes. We asked teachers to offer their opinions on their students' preparation for physics in a number of areas. The overall picture of teacher perception of student preparation in various domains is shown at right. In each of the areas, more than half of the teachers felt that their students were at least adequately prepared. Almost two-fifths of the responding teachers reported that their students were inadequately prepared to think and pose questions scientifically, and less than 10% of the teachers felts that their students were adequately prepared in this area.
The Rocker (An Easy Anharmonic Oscillator for Classroom Demonstration)
Authors: Lieberherr Martin
Published: March 2013

Every instructor should know some easy examples of anharmonic oscillations. The rocking of an empty wine bottle or a slender beer glass is one of those: The angle is not a sinusoidal function of time and the period is not independent of the amplitude, not even for small amplitudes. But care has to be taken that the glass does not slip or rotate around a vertical axis. LEGO rockers (see Fig. 1) are much more reliable and versatile.
Teaching Electron—Positron—Photon Interactions with Hands-on Feynman Diagrams
Authors: Kontokostas George , Kalkanis George
Published: March 2013

Feynman diagrams are introduced in many physics textbooks, such as those by Alonso and Finn 1 and Serway,2 and their use in physics education has been discussed by various authors.3–5 They have an appealing simplicity and can give insight into events in the microworld. Yet students often do not understand their significance and often cannot combine the basic units of interaction—points where the world lines of two fermions and one boson meet—to construct diagrams for observed processes.
Hydrogen Cyanide Production During Reduction of Nitric Oxide over Platinum Catalysts
Authors: Voorhoeve R. J. H. , Patel C. K. N. , Trimble L. E. , Kerl R. J.
Published: March 2013

The catalytic reduction of nitric oxide with carbon monoxide and hydrogen was studied with a bench-scale flow reactor at 400° to 800°C over platinum to determine the yield of hydrogen cyanide. An opto-acoustic infrared absorption technique was applied to the analysis of hydrogen cyanide. In mixtures of nitric oxide, carbon monoxide, hydrogen, and water vapor, with all concentrations in the range of 0.1 to 5 percent, up to 80 parts per million (ppm) of hydrogen cyanide is formed over platinum at 600° to 800°C. In the absence of water vapor, the hydrogen cyanide concentration rises to 700 ppm. With 6 to 60 ppm of sulfur dioxide in the gas mixture, hydrogen cyanide production is suppressed to less than 5 ppm. No significant differences were found between a platinum sponge and platinum supported on cordierite. The implications of our results for the catalytic treatment of automotive exhaust are examined.
Middle Stone Age Man-Animal Relationships in Southern Africa: Evidence from Die Kelders and Klasies River Mouth
Authors: Klein Richard G.
Published: March 2013

The Middle Stone Age (earlier upper Pleistocene) sites of Die Kelders Cave I and Klasies River Mouth Cave I, southern Cape Province, South Africa, have provided faunal assemblages which imply that Middle Stone Age peoples were exploiting local resources less effectively than Later Stone Age (later upper Pleistocene-Holocene) peoples in the same area. The age structure of the Pelorovis (giant buffalo) herd in the Klasies site suggests that Middle Stone Age hunters may have been responsible for initiating a decline in the species' abundance that culminated in its final disappearance 10,000 to 12,000 years ago.
Precision Measurement of Particulates by Light Scattering at Optical Resonance
Authors: Marshall Thomas R. , Parmenter Charles S. , Seaver Mark
Published: March 2013

The efficiency of light scattering from individual aerosol spheres is markedly enhanced for certain combinations of the particle size and refractive index with the incident wavelength. Differential scattering patterns observed at these "optical resonances" are so sensitive to particle characteristics that relative optical diameters of an approximately 3-micrometer sphere can be determined to within about 2 angstroms (0.007 percent). Such resonances for 1- to 30-micrometer spheres, cylinders, and regular nonspherical particles should be generally accessible with tunable lasers.
Planetary Brightness Changes: Evidence for Solar Variability
Authors: Lockwood G. W.
Published: March 2013

Brightness changes of Uranus and Neptune at 440 nanometers were highly correlated from 1956 to 1966. Recent observations of Saturn's satellite Titan and of Uranus and Neptune show a steady brightening at 551 and 472 nanometers since 1972. Either the solar constant is slightly variable or solar activity causes correlated changes in the albedos of planetary bodies.
Formation of Negative Ions Under Inverted Field Ionization Conditions
Authors: Anbar Michael , St. John Gilbert A.
Published: March 2013

Negative organic ions including those of thymine, perylene, and trinitrotoluene have been produced by subjecting the parent substances on a metal surface to the influence of a high positive electrostatic field. The field produced at highly curved metallic surfaces (below the threshold of field emission) may allow electron uptake by substances that have a sufficient electron affinity. The scope and implications of this novel mass spectrometric technique are discussed.
Cadmium in Plankton: Elevated Concentrations off Baja California
Authors: Martin J. H. , Broenkow W. W.
Published: March 2013

One hundred thirty-five plankton samples were collected in the northeast Pacific Ocean and analyzed for their cadmium content. Concentrations were generally low (2 to 5 micrograms of cadmium per gram, dry weight) in all samples, except for the plankton collected off Baja California, where high values (10 to 20 parts per million) were consistently found on two cruises.
What is the evidence for chronic concussion-related changes in retired athletes: behavioural, pathological and clinical outcomes?
Authors: McCrory Paul , Meeuwisse Willem H , Kutcher Jeffrey S , Jordan Barry D , Gardner Andrew
Published: March 2013

Objective

The purpose of this paper was to review the current state of evidence for chronic traumatic encephalopathy (CTE) in retired athletes and to consider the potential differential diagnoses that require consideration when retired athletes present with cognitive and psychiatric problems.

Data sources

MEDLINE, CINAHL, EMBASE, Mosby's Index, PsycEXTRA, PsycINFO and Scopus. Key words included CTE, dementia pugilistica, punch drunk syndrome, traumatic encephalopathy, CTE, repetitive head injury, sports concussion, multiple concussions, chronic concussions, subconcussive blow and sports-related traumatic brain injury.

Results

At present, there are no published epidemiological, cross-sectional or prospective studies relating to modern CTE. Owing to the nature of the published studies, being case reports or pathological case series, it is not possible to determine the causality or risk factors with any certainty. As such, the speculation that repeated concussion or subconcussive impacts cause CTE remains unproven. The extent to which age-related changes, psychiatric or mental health illness, alcohol/drug use or coexisting dementing illnesses contribute to this process is largely unaccounted for in the published literature.

Conclusions

At present, the interpretation of causation in the modern CTE case studies should proceed cautiously. The causal assumptions require further prospective or longitudinal studies on the topic.
The depth of edge influence among insectivorous bats at forest–field interfaces
Authors: Jantzen M.K. , Fenton M.B.
Published: March 2013

Species-specific variations in wing morphology and echolocation call characteristics often define which of three structural habitat types (open, cluttered, and edge) different bat species most frequently and efficiently use for foraging. Although edges are recognized as important habitats for commuting and foraging bats, no study to date has examined the depth of edge influence (DEI), the extent of quantitative changes in activity with distance from an edge, for any bat species. We focused our study on five species: northern long-eared bat, Myotis septentrionalis (Trouessart, 1897); hoary bat, Lasiurus cinereus (Beauvois, 1796); little brown bat, Myotis lucifugus (LeConte, 1831); silver-haired bat, Lasionycteris noctivagans (LeConte, 1831); big brown bat, Eptesicus fuscus (Beauvois, 1796). We predicted DEI would vary with species-specific differences in wing morphology and echolocation call characteristics. From June to August in 2010 and 2011, we passively recorded echolocation calls three to four times per month at eight sites in eastern Ontario, Canada. We found that species’ activity was highest at the edge, regardless of wing morphology and echolocation call characteristics. The DEI for all species was approximately 40 m into both forests and fields. Understanding the effects of DEI on bats will enable more effective acoustic monitoring in future studies and may provide crucial information for management decisions.
FINITE GROUPS ALL OF WHOSE SECOND MAXIMAL SUBGROUPS ARE ${\mathcal{H^*}}$-GROUPS
Authors: ZHONG XIANGGUI
Published: March 2013

Let G be a finite group. A subgroup H of G is called weakly normal in G if Hg ≤ NG(H) implies g ∈ NG(H) for all g ∈ G. A finite group G is called an [Formula: see text]-group if all cyclic subgroups of G of order prime or 4 are weakly normal in G. In this paper, the structure of finite groups all of whose second maximal subgroups satisfy [Formula: see text]-property has been characterized.
EMBEDDED FINGERPRINT MATCHING ON SMART CARD
Authors: BENHAMMADI FARID , BEY KADDA BEGHDAD
Published: March 2013

This paper describes an embedded minutia-based matching algorithm using the reference point neighborhoods minutiae. The proposed matching algorithm is implemented in restricted environments such as smart card devices requiring careful monitoring of both memory and processing time usage. The proposed algorithm uses a circular tessellation to encode fingerprint features in neighborhood minutia localization binary codes. The objective of the present study is the development of a new matching approach which reduces both computing time and required space memory for fingerprint matching on Java Card. The main advantage of our approach is avoiding the implicit alignment of fingerprint images during the matching process while improving the fingerprint verification accuracy. Tests carried out on the public fingerprint databases DB1-a and DB2-a of FVC2002 have shown the effectiveness of our approach.
A BACKGROUND MODELING-BASED FAITHFUL APPROACH TO THE DISOCCLUSION PROBLEM IN DEPTH IMAGE-BASED RENDERING
Authors: SCHMEING MICHAEL , JIANG XIAOYI
Published: March 2013

In this paper, we address the disocclusion problem that occurs during view synthesis in depth image-based rendering (DIBR). We propose a method that can recover faithful texture information for disoccluded areas. In contrast to common disocclusion filling methods, which usually work frame-by-frame, our algorithm can take information from temporally neighboring frames into account. This way, we are able to reconstruct a faithful filling for the disocclusion regions and not just an approximate or plausible one. Our method avoids artifacts that occur with common approaches and can additionally reduce compression artifacts at object boundaries.
AVERAGE INTERFERENCE MINIMIZATION UNDER THE PROTOCOL MODEL IN WIRELESS SENSOR NETWORKS
Authors: TAN HAISHENG , LOU TIANCHENG , WANG AMY YUEXUAN , WANG YONGCAI , LAU FRANCIS C. M.
Published: March 2013

Reducing interference is one of the main challenges in wireless communication. How to minimize interference through network topology control in wireless sensor networks is a well-known open algorithmic problem. In this paper, we answer the question of how to minimize the average interference when a node is receiving a message. We adopt the protocol interference model, which defines the interference range of a node to be a constant times larger than its transmission range. We study the problem for nodes arbitrarily deployed in one-dimensional (1D) and two-dimensional (2D) regions respectively. For 1D networks, we propose a fast polynomial-time exact algorithm that can compute the minimum average interference. For 2D networks, we give a proof that the maximum interference can be bounded while minimizing the average interference. The bound is only related to the distances between nodes but not the network size. Based on the bound, we propose the first exact algorithm to compute the minimum average interference in 2D networks. Optimal topologies with the minimum average interference can be constructed through traceback in both 1D and 2D networks.
RANDOM ATTRACTORS OF STOCHASTIC NON-NEWTONIAN FLUIDS ON UNBOUNDED DOMAIN
Authors: GUO CHUNXIAO , GUO BOLING , GUO YANFENG
Published: March 2013

We consider the stochastic non-Newtonian fluids defined on a two-dimensional Poincaré unbounded domain, and prove that it generates an asymptotically compact random dynamical system. Then, we establish the existence of random attractor for the corresponding random dynamical system. Random attractor is invariant and attracts every pullback tempered random set.
COORDINATION ON EGALITARIAN NETWORKS FROM ASYMMETRIC RELATIONS IN A SOCIAL GAME OF CHICKEN
Authors: TSVETKOVA MILENA , BUSKENS VINCENT
Published: March 2013

We present a model of social interaction in which actors choose their partners and play the Chicken Game with them. In contrast to most previous models of the coevolution of games and networks, we assume that the actors can employ different actions against different partners. This allows us to derive two different solutions to the coordination and asymmetry problems in the game: egalitarian stationary conventions (based on indirect reciprocity at the network level) and alternating conventions (based on direct reciprocity in dyads). We derive predictions on the occurrence of the possible convention structures and test our theoretical findings in a computerized experiment. The experimental results indicate that the egalitarian conventions indeed emerge and persist and that the alternating conventions are much more likely than the stationary ones. However, although egalitarian in terms of payoffs, the convention structures tend to have hierarchical action distributions.
CURRENT ALGEBRAS AND QP-MANIFOLDS
Authors: IKEDA NORIAKI , KOIZUMI KOZO
Published: March 2013

Generalized current algebras introduced by Alekseev and Strobl in two dimensions are reconstructed by a graded manifold and a graded Poisson brackets. We generalize their current algebras to higher dimensions. QP-manifolds provide the unified structures of current algebras in any dimension. Current algebras give rise to structures of Leibniz/Loday algebroids, which are characterized by QP-structures. Especially, in three dimensions, a current algebra has a structure of a Lie algebroid up to homotopy introduced by Uchino and one of the authors, which has a bracket of a generalization of the Courant–Dorfman bracket. Anomaly cancellation conditions are reinterpreted as generalizations of the Dirac structure.