bluuebunny/crossref_metadata_2025 huggingface dataset:
Fabrication of nanofibres via polyvinylpyrrolidone by sol–gel method and electro‐spinning technique
Authors: Cai Zhaobing , Jin Guo , Cui Xuifang , Zheng Wei , Liu Erbao , Wang Yang , Tan Na
Published: March 2015

ZrO2 fibres have been used in aspects of aeronautics and astronautics because of their properties such as high strength, good toughness and thermal shock resistance. In this reported work, polyvinylpyrrolidone (PVP)/Y(NO3)3·6H2O/ZrOCl2·8H2O (PVP‐precursor) nanofibres were prepared by the sol–gel method and an electro‐spinning technique. Then, the ZrO2 fibres by Y‐doping were obtained by calcination of the above precursor fibres at 550°C for 0.5 h. These fibres were characterised by X‐ray diffraction, scanning electron microscopy, energy‐dispersive X‐ray spectroscopy, Fourier transform infrared spectroscopy, differential scanning calorimetry and thermogravimetry to study the physical and chemical properties. The formation mechanism of ZrO2 fibres is also illustrated. The results show that: (i) the diameter of the nanofibres is in the range of 500–3000 nm; (ii) PVP‐precursor fibres should reach the level of obvious dehydration, oxidation decomposition and phase transition to synthesise ZrO2 nanofibres; (iii) through thermal poly‐condensation reaction, PVP turns into a network structure of graphitised carbon.
Design of a four-degree-of-freedom nano positioner utilizing electromagnetic actuators and flexure mechanisms
Authors: Ahn Dahoon , Choi Young-Man , Jeong Jaehwa
Published: March 2015

Positioning devices are widely used in industrial applications. High precision is a key performance of the positioner and recently high precision positioners for advanced applications are required to satisfy other performances such as larger motion range, nanometer level precision, and multiple degree-of-freedom (DOF) motion within compact size. We propose a new 4-DOF high-precision positioner employing voice coil motors and flexure guides. Millimeter motion range and nano level resolution were achieved simultaneously, utilizing the frictionless characteristic of the voice coil motors and the flexures. The mathematical model describing static and dynamic behaviors of the positioner was developed and the design parameters were optimized to achieve the best performances. The proposed positioner was manufactured with the size of 180 × 180 × 30.7 mm3 which was very compact. The experiment of feedback control showed the motion range more than 1.80 × 1.80 mm2 in-plane and 0.3 mm vertically and the minimum resolution of 10 nm in-plane and 14 nm vertically.
A reduced-scaling density matrix-based method for the computation of the vibrational Hessian matrix at the self-consistent field level
Authors: Kussmann Jörg , Luenser Arne , Beer Matthias , Ochsenfeld Christian
Published: March 2015

An analytical method to calculate the molecular vibrational Hessian matrix at the self-consistent field level is presented. By analysis of the multipole expansions of the relevant derivatives of Coulomb-type two-electron integral contractions, we show that the effect of the perturbation on the electronic structure due to the displacement of nuclei decays at least as r−2 instead of r−1. The perturbation is asymptotically local, and the computation of the Hessian matrix can, in principle, be performed with ON complexity. Our implementation exhibits linear scaling in all time-determining steps, with some rapid but quadratic-complexity steps remaining. Sample calculations illustrate linear or near-linear scaling in the construction of the complete nuclear Hessian matrix for sparse systems. For more demanding systems, scaling is still considerably sub-quadratic to quadratic, depending on the density of the underlying electronic structure.
Theoretical investigations on the layer-anion interaction in Mg–Al layered double hydroxides: Influence of the anion nature and layer composition
Authors: Cuautli Cristina , Ireta Joel
Published: March 2015

The influence of the anion nature and layer composition on the anion-layer interaction in Mg–Al layered double hydroxides (LDHs) is investigated using density functional theory. Changes in the strength of the anion-layer interaction are assessed calculating the potential energy surface (PES) associated to the interlayer anion (OH−/Cl−) in Mg–Al–OH and Mg–Al–Cl LDHs. The layer composition is varied changing the divalent to trivalent cation proportion (R). Mg–Al–OH is thus investigated with R = 2, 3, 3.5 and Mg–Al–Cl with R = 3. It is found that the PES for OH− in Mg–Al–OH/R = 3 presents wider energy basins and lower energy barriers than any other of the investigated compositions. It is shown that the latter is connected to the number of hydrogen bonds formed by the anions. These results have interesting implications for understanding the enhancement of the physicochemical properties of LDHs upon changing composition.
Theory of correlation effects in dusty plasmas
Authors: Avinash K.
Published: March 2015

A theory of correlation effects in dusty plasmas based on a suitably augmented Debye Huckel approximation is proposed. A model which takes into account the confinement of the dust within the plasma (by external fields) is considered. The dispersion relation of compressional modes with correlation effects is obtained. Results show that strong coupling effects may be subdominant even when Г ≫ 1. Thus, in the limit Γ→0 and/or κ → ∞, one obtains the weakly coupled dust thermal mode. In the range of values of Г ≫ 1, the strong coupling effects scale with κ instead of Г; increasing Г increases the dust acoustic waves phase velocity CDAW in this regime. In the limit Γ≫1,κ≪1, one obtains the weakly coupled dust acoustic wave. Only in the limit Γ≫1,κ≥1, one obtains strong coupling effects, e.g., the dust lattice waves (κ=a/λd, a is the mean particle distance and λd is the Debye length). Observations from a number of experiments are explained.
Response of a fluid-immersed microcantilever close to a deformable body
Authors: Clarke R. J. , Bachtiar V. , Lee T. C. , Cater J. E. , Minton J.
Published: March 2015

The importance of hydrodynamics upon the response of a microcantilever immersed in a viscous fluid has been well established [J. E. Sader, J. Appl. Phys. 84, 64 (1998); C. A. Eysden and J. E. Sader, J. Appl. Phys. 101, 044908 (2007)]. It has previously been shown that the presence of a nearby rigid planar surface can significantly alter a microcantilever's non-contact response, through microcantilever–surface hydrodynamic interactions [C. P. Green and J. E. Sader, Phys. Fluids 17, 073102 (2005); C. P. Green and J. E. Sader, J. Appl. Phys. 98, 114913 (2005); R. J. Clarke et al., J. Fluid Mech. 545, 397426 (2005); R. J. Clarke et al., Phys. Rev. Lett. 96, 050801 (2006).]. In cases where the nearby surface is a finite-sized deformable body, such as in noncontact microrheology measurements, we expect to see further changes in the microcantilever's response. Hence, we here compute the thermal spectra of several microcantilevers in the presence of different compliant samples that have the characteristics of soft biological fibres. Our findings demonstrate that the elastohydrodynamic regime can substantially dictate the extent to which the compliance of a given body is evident in the microcantilever's thermal spectra, and suggest that certain nondimensional quantities should lie within particular, ranges for this to be the case. We expect these findings to be of interest in areas such as Atomic Force Microscopy, microsensing, and non-contact microrheology.
Building blocks for correlated superconductors and magnets
Authors: Sarrao J. L. , Ronning F. , Bauer E. D. , Batista C. D. , Zhu J.-X. , Thompson J. D.
Published: March 2015

Recent efforts at Los Alamos to discover strongly correlated superconductors and hard ferromagnets are reviewed. While serendipity remains a principal engine of materials discovery, design principles and structural building blocks are beginning to emerge that hold potential for predictive discovery. Successes over the last decade with the so-called “115” strongly correlated superconductors are summarized, and more recent efforts to translate these insights and principles to novel hard magnets are discussed. While true “materials by design” remains a distant aspiration, progress is being made in coupling empirical design principles to electronic structure simulation to accelerate and guide materials design and synthesis.
Numerical simulation of cathode plasma dynamics in magnetically insulated vacuum transmission lines
Authors: Thoma C. , Genoni T. C. , Welch D. R. , Rose D. V. , Clark R. E. , Miller C. L. , Stygar W. A. , Kiefer M. L.
Published: March 2015

A novel algorithm for the simulation of cathode plasmas in particle-in-cell codes is described and applied to investigate cathode plasma evolution in magnetically insulated transmission lines (MITLs). The MITL electron sheath is modeled by a fully kinetic electron species. Electron and ion macroparticles, both modeled as fluid species, form a dense plasma which is initially localized at the cathode surface. Energetic plasma electron particles can be converted to kinetic electrons to resupply the electron flux at the plasma edge (the “effective” cathode). Using this model, we compare results for the time evolution of the cathode plasma and MITL electron flow with a simplified (isothermal) diffusion model. Simulations in 1D show a slow diffusive expansion of the plasma from the cathode surface. But in multiple dimensions, the plasma can expand much more rapidly due to anomalous diffusion caused by an instability due to the strong coupling of a transverse magnetic mode in the electron sheath with the expanding resistive plasma layer.
Self-similar and diffusive expansion of nonextensive plasmas
Authors: Akbari-Moghanjoughi M.
Published: March 2015

Exact analytical self-similar solution is presented for free collisionless expansion of a two-component plasma of inertial ions and nonextensive electrons into vacuum, using the generalized nonextensive velocity distribution for electrons. Furthermore, a hydrodynamic model of plasma expansion in the presence of the ambipolar diffusion caused by collisions among the plasma species, such as electrons and ions, is developed and a Fokker-Planck-like generalized diffusion equation for steady-state expansion of a nonextensive electron-ion plasma is derived. For the case of generalized statistics and in the absence of particle diffusion, the density, velocity, electric potential, and field of expansion profiles are exactly obtained and studied in terms of the self-similar parameter. It is found that superthermal electrons lead to an accelerated expansion of plasma compared to that of Maxwellian electrons. It is also revealed that the nonextensivity parameter plays a fundamental role on the density, velocity, electric potential, and field configuration of the expansion. Therefore, one is able to distinguish three different regimes q < 1, q = 1, and q > 1 for expansion corresponding to sub-nonextensive, extensive, and super-nonextensive statistical profiles for electrons, respectively. Current research can provide useful information and suggests techniques for investigation of the involved statistical mechanism on the role of the energetic electron fluid in the expansion of plasma in strong pulsed laser-matter interaction experiments. It is also shown that the particle diffusion expansion mechanism becomes more dominant for relatively large values of the nonextensivity parameter, q.
Enhanced thermoelectric power and electronic correlations in RuSe2
Authors: Wang Kefeng , Wang Aifeng , Tomic A. , Wang Limin , Abeykoon A. M. Milinda , Dooryhee E. , Billinge S. J. L. , Petrovic C.
Published: March 2015

We report the electronic structure, electric and thermal transport properties of Ru1−xIrxSe2 (x ≤ 0.2). RuSe2 is a semiconductor that crystallizes in a cubic pyrite unit cell. The Seebeck coefficient of RuSe2 exceeds −200 μV/K around 730 K. Ir substitution results in the suppression of the resistivity and the Seebeck coefficient, suggesting the removal of the peaks in density of states near the Fermi level. Ru0.8Ir0.2Se2 shows a semiconductor-metal crossover at about 30 K. The magnetic field restores the semiconducting behavior. Our results indicate the importance of the electronic correlations in enhanced thermoelectricity of RuSb2.
β phase instability in poly(vinylidene fluoride/trifluoroethylene) thin films near β relaxation temperature
Authors: Tian B. B. , Bai X. F. , Liu Y. , Gemeiner P. , Zhao X. L. , Liu B. L. , Zou Y. H. , Wang X. D. , Huang H. , Wang J. L. , Sun Sh. , Sun J. L. , Dkhil B. , Meng X. J. , Chu J. H.
Published: March 2015

The β phase stability in poly(vinylidene fluoride/trifluoroethylene) [P(VDF-TrFE)] thin films was studied below 300 K using X-ray diffraction and polarization-electric-field (P-E) hysteresis loops measurements. On as-grown samples, an irreversible partial order-disorder transformation at Tβ ∼ 250 K, namely, the β relaxation temperature, was evidenced by the appearance of an additional X-Ray diffraction peak above Tβ as well as changes on the P-E loops on heating after the first cooling. This order-disorder-like transformation which is attributed to an all-trans order to helical disorder transition is suggested to take place in defect-rich regions like crystal-amorphous interphases and/or crystalline areas with randomly distributed TrFE defect-like units.
Phase characteristics of 0.92Bi0.5Na0.5TiO3-0.08BiAlO3 ceramics
Authors: Peng Wei , Mao Chaoliang , Liu Zhen , Dong Xianlin , Cao Fei , Wang Genshui
Published: March 2015

The phase characteristics of 0.92Bi0.5Na0.5TiO3-0.08BiAlO3 lead-free ceramics were investigated systematically. The loss tangent of poled sample shows a broad peak when heating to about 80 °C, i.e., depolarization temperature Td. The polarization-electric field hysteresis loops at different temperature exhibit the feature of ferroelectric (FE)- antiferroelectric (AFE) phase transition and the co-existence of FE and AFE phase. The pyroelectric coefficients curve confirms its diffusion behaviors. The initial hysteresis loop and switching current curves under Td indicate the co-existence of FE and AFE phase. The domain morphology of transmission electron microscopy supports the co-existence of FE and AFE phase. Our work not only exhibit that the FE and AFE phase characteristics of 0.92Bi0.5Na0.5TiO3-0.08BiAlO3 ceramics but also they may be helpful for further investigation on lead-free ceramics.
Active control of membrane-type acoustic metamaterial by electric field
Authors: Xiao Songwen , Ma Guancong , Li Yong , Yang Zhiyu , Sheng Ping
Published: March 2015

By employing a metal-coated central platelet and a rigid mesh electrode which is transparent to acoustic wave, we show that the membrane-type acoustic metamaterials (MAMs) can be easily tuned by applying an external voltage. With static voltage, the MAM's eigenfrequencies and therefore the phase of the transmitted wave are tunable up to 70 Hz. The MAM's vibration can be significantly suppressed or enhanced by using phase-matched AC voltage. Functionalities such as phase modulation and acoustic switch with on/off ratio up to 21.3 dB are demonstrated.
Negative capacitance switching via VO2 band gap engineering driven by electric field
Authors: He Xinfeng , Xu Jing , Xu Xiaofeng , Gu Congcong , Chen Fei , Wu Binhe , Wang Chunrui , Xing Huaizhong , Chen Xiaoshuang , Chu Junhao
Published: March 2015

We report the negative capacitance behavior of an energy band gap modulation quantum well with a sandwich VO2 layer structure. The phase transition is probed by measuring its capacitance. With the help of theoretical calculations, it shows that the negative capacitance changes of the quantum well device come from VO2 band gap by continuously tuning the temperature or voltage. Experiments reveal that as the current remains small enough, joule heating can be ignored, and the insulator-metal transition of VO2 can be induced by the electric field. Our results open up possibilities for functional devices with phase transitions induced by external electric fields other than the heating or electricity-heat transition.
Strategic variables of commercialization of renewable energy technologies
Authors: Aslani Alireza
Published: March 2015

Utilization of renewable energy sources, as domestic and local natural resources, has important role among the energy policies of the governments. However, diffusion of renewable energy technologies have faced with challenges that slow the development plans and affect security of energy supply. As commercialization is an important contributor to successful diffusion and adaptation of a technology, this research studies the role of commercialization of renewable energy technologies and identifies the key factors of commercialization. A decision matrix is also presented to show the best government strategies for successful commercialization of renewable energy products and services. The contributions help researchers and policy makers to focus more on the strategic variables of commercialization of renewable energy technologies.
Cultural Diversity and Entrepreneurship in England and Wales
Authors: Rodríguez-Pose Andrés , Hardy Daniel
Published: March 2015

British regions are becoming increasingly culturally diverse, with migration as the main driver. Does this diversity benefit local economies? This research examines the impact of cultural diversity on the entrepreneurial performance of UK regions. We focus on two largely overlooked factors: the measurement of diversity and the skills composition of diverse populations. First, more than demonstrating the importance of cultural diversity for entrepreneurship, we show that the type of cultural diversity measured is a decisive factor. Second, the skill composition of diverse populations is also key. Diversity amongst highly skilled workers exerts the strongest impact upon start-up intensities. The empirical investigation employs spatial regression techniques and carries out several robustness checks, including instrumental variables specifications, to corroborate our findings.
Grassroots Innovation for Urban Sustainability: Comparing the Diffusion Pathways of Three Ecovillage Projects
Authors: Boyer Robert H W
Published: March 2015

Grassroots innovation literature proposes that ‘intermediately’ situated community-based projects—those which are neither too radical, nor too embedded in the mainstream—play an important cross-contextual bridging role in processes of innovation for sustainable development. This paper explores this intermediacy claim by comparing how three established ecovillage projects engage outsiders and diffuse their lessons learned. Employing comparative case-study methodology, I find that while all three projects successfully replicate alternative practices outside their boundaries—for example through education, outreach, and on-site activities—one project has partnered with municipal planners to translate ‘ecovillage concepts’ into a new zoning category that will facilitate similar development by mainstream actors. The argument is made that the landscape for grassroots innovation is uneven, and that niche-to-regime translation occurs through projects that position themselves as part of two action domains at once.
Perception of Animacy from the Motion of a Single Sound Object
Authors: Nielsen Rasmus Høll , Vuust Peter , Wallentin Mikkel
Published: March 2015

Research in the visual modality has shown that the presence of certain dynamics in the motion of an object has a strong effect on whether or not the entity is perceived as animate. Cues for animacy are, among others, self-propelled motion and direction changes that are seemingly not caused by entities external to, or in direct contact with, the moving object. The present study aimed to extend this research into the auditory domain by determining if similar dynamics could influence the perceived animacy of a sound source. In two experiments, participants were presented with single, synthetically generated ‘mosquito’ sounds moving along trajectories in space, and asked to rate how certain they were that each sound-emitting entity was alive. At a random point on a linear motion trajectory, the sound source would deviate from its initial path and speed. Results confirm findings from the visual domain that a change in the velocity of motion is positively correlated with perceived animacy, and changes in direction were found to influence animacy judgment as well. This suggests that an ability to facilitate and sustain self-movement is perceived as a living quality not only in the visual domain, but in the auditory domain as well.
A New Demonstration of the Illusory Letters Phenomenon: Graphemic Restoration in Arabic Word Perception
Authors: Jordan Timothy R , Sheen Mercedes , AlJassmi Maryam A , Paterson Kevin B
Published: March 2015

The illusory letters phenomenon (ILP) is a unique demonstration that words can be perceived as complete even when letters are physically absent. However, the ILP has only ever been reported for a Latinate language (English), and it is unknown whether the illusion occurs for alphabetic languages with fundamentally different visual properties. Here we report a demonstration of the ILP for Arabic in which stimuli containing only the exterior letters of three-letter Arabic words and a nonsense pattern in the interior position were presented to fluent Arabic readers. Despite being incomplete, participants perceived these stimuli as complete Arabic words with all letters visible in their appropriate positions, and were unable to distinguish between illusory and normal displays. This finding provides an important extension of the original ILP and suggests that alphabetic languages may be widely susceptible to the phenomenon and reading generally may occur as a process augmented by illusory percepts.
Depicting Visual Motion in Still Images: Forward Leaning and a Left to Right Bias for Lateral Movement
Authors: Walker Peter
Published: March 2015

What artistic conventions are used to convey the motion of animate and inanimate items in still images, such as drawings and photographs? One graphic convention involves depicting items leaning forward into their movement, with greater leaning conveying greater speed. Though this convention could derive from the natural leaning forward of people and animals as they run, it is also applied to depictions of inanimate objects (eg cars and trains). It is proposed that it is this convention that allows the italicization of text to convey notions of motion and speed. Evidence for this is obtained from three sources: the use of italicization on book covers (in book titles); judgments of typeface connotations; and performance measures during the semantic classification of words appearing in italicized and non-italicized fonts. Inspection of the availability of italic fonts in Hebrew indicates an additional artistic convention for conveying motion, based on a fundamental bias, yet to be confirmed, for people to expect to see, or prefer to see, lateral movement (real or implied) in a left to right direction, rather than a right to left direction. Evidence for such a bias is found in photographs of a range of animate and inanimate items archived on Google Images. Whereas a rightward bias is found for photographs of animate and inanimate items in motion (the more so, the faster the motion being conveyed), either no bias or a leftward bias is found for the same items in static pose. Possible origins of a fundamental left to right bias for visual motion, and future lines of research able to evaluate them, are identified.
Effect of cropping practices on soil organic carbon: evidence from long-term field experiments in Victoria, Australia
Authors: Robertson Fiona , Armstrong Roger , Partington Debra , Perris Roger , Oliver Ivanah , Aumann Colin , Crawford Doug , Rees David
Published: March 2015

Despite considerable research, predicting how soil organic carbon (SOC) in grain production systems will respond to conservation management practices, such as reduced tillage, residue retention and alternative rotations, remains difficult because of the slowness of change and apparent site specificity of the effects. We compared SOC stocks (equivalent soil mass to ~0–0.3 m depth) under various tillage, residue management and rotation treatments in three long-term (12-, 28- and 94-year-old) field experiments in two contrasting environments (Mallee and Wimmera regions). Our hypotheses were that SOC stocks are increased by: (1) minimum tillage rather than traditional tillage; (2) continuous cropping, rather than crop–fallow rotations; and (3) phases of crop or pasture legumes in rotations, relative to continuous cropping with cereals. We found that zero tillage and stubble retention increased SOC in some circumstances (by up to 1.5 Mg C ha–1, or 8%) but not in others. Inclusion of bare fallow in rotations reduced SOC (by 1.4–2.4 Mg C ha–1, or 8–12%) compared with continuous cropping. Including a pulse crop (field pea, where the grain was harvested) in rotations also increased SOC in some instances (by ~6–8 Mg C ha–1, or 29–35%) but not in others. Similarly, leguminous pasture (medic or lucerne) phases in rotations either increased SOC (by 3.5 Mg C ha–1, or 21%) or had no significant effect compared with continuous wheat. Inclusion of a vetch green manure or unfertilised oat pasture in the rotation did not significantly increase SOC compared with continuous wheat. The responses in SOC to these management treatments were likely to be due, in part, to differences in nitrogen and water availability (and their effects on carbon inputs and decomposition) and, in part, to other, unidentified, interactions. We conclude that the management practices examined in the present study may not reliably increase SOC on their own, but that significant increases in SOC are possible under some circumstances through the long-term use of multiple practices, such as stubble retention + zero tillage + legume N input + elimination of fallow. The circumstances under which increases in SOC can be achieved require further investigation.
Structure of superhard tungsten tetraboride: A missing link between MB
2
and MB
12
higher borides
Authors: Lech Andrew T. , Turner Christopher L. , Mohammadi Reza , Tolbert Sarah H. , Kaner Richard B.
Published: March 2015

Significance

Superhard materials are those with hardness competitive with diamond. This study investigates tungsten tetraboride, a superhard metallic compound, and a promising candidate to revolutionize cutting tools and to succeed the “hard metals,” such as tungsten carbide, that are commonly used. Unfortunately, the structure of this material has been contested for over half a century. Previous attempts at its solution have lacked comprehensiveness, as they have not used techniques, such as neutron diffraction, which are capable of differentiating between light and heavy elements (boron and tungsten, respectively). Utilizing both X-ray and neutron diffraction, this study reveals that tungsten tetraboride is actually an interesting ‘new’ structural hybrid between lower and higher borides, a missing link that further confirms the structural regularity among borides.
Dramatically reduced spliceosome in
Cyanidioschyzon merolae
Authors: Stark Martha R. , Dunn Elizabeth A. , Dunn William S. C. , Grisdale Cameron J. , Daniele Anthony R. , Halstead Matthew R. G. , Fast Naomi M. , Rader Stephen D.
Published: March 2015

Significance

The spliceosome—the molecular particle responsible for removing interrupting sequences from eukaryotic messenger RNA—is one of the most complex cellular machines. Consisting of five snRNAs and over 200 proteins in humans, its numerous changes in composition and shape during splicing have made it difficult to study. We have characterized an algal spliceosome that is much smaller, with only 43 identifiable core proteins, the majority of which are essential for viability in other organisms. We propose that this highly reduced spliceosome has retained only the most critical splicing factors.
Cyanidioschyzon merolae
therefore provides a powerful system to examine the spliceosome’s catalytic core, enabling future advances in understanding the splicing mechanism and spliceosomal organization that are challenging in more complex systems.
Prepregnancy body mass and weight gain during pregnancy in India and sub-Saharan Africa
Authors: Coffey Diane
Published: March 2015

Significance

Because India—home to one fifth of all births—has no monitoring system for maternal health, basic facts about maternal nutrition are unknown. Using statistically adjusted nationally representative survey data, this paper presents, to my knowledge, the first estimates of prepregnancy body mass and weight gain during pregnancy in India and compares them with sub-Saharan Africa: 42.2% of Indian women are underweight when they begin pregnancy compared with 16.5% of African women. In both regions, women gain little weight during pregnancy, but because of prepregnancy deficits, Indian women end pregnancy weighing less than African women do at the beginning. Deficits in maternal nutrition could help explain the Asian enigma, the puzzle of why Indian children are much smaller than their relative wealth predicts.
Sequential de novo centromere formation and inactivation on a chromosomal fragment in maize
Authors: Liu Yalin , Su Handong , Pang Junling , Gao Zhi , Wang Xiu-Jie , Birchler James A. , Han Fangpu
Published: March 2015

Significance

The centromere is the part of the chromosome that is involved with movement in mitosis and meiosis. The activity of the centromere is epigenetic in that the underlying DNA sequences do not necessarily determine function. In the present study, a chromosomal fragment was followed in which a sequential de novo formation and inactivation occurred for the position of the active centromere. The results suggest that de novo centromere formation occurs regularly. However, when coupled with previous findings that larger centromeres can inactivate smaller ones when present together, it is hypothesized that such frequent de novo centromere formations are cleared from normal chromosomes by inactivation, but can persist on structurally acentric fragments and be inherited.
BRUCE regulates DNA double-strand break response by promoting USP8 deubiquitination of BRIT1
Authors: Ge Chunmin , Che Lixiao , Ren Jinyu , Pandita Raj K. , Lu Jing , Li Kaiyi , Pandita Tej K. , Du Chunying
Published: March 2015

Significance

DNA damage response is essential to preserve genomic stability. Here we report a previously unknown function for the baculovirus inhibitor of apoptosis protein repeat (BIR)-containing ubiquitin-conjugating enzyme (BRUCE) and ubiquitin-specific peptidase 8 (USP8) as activators of DNA damage response. They drive recruitment of the breast cancer susceptibility gene C terminus-repeat inhibitor of human telomerase reverse transcriptase expression (BRIT1) to DNA breaks by promoting BRIT1 deubiquitination. In contrast to the established regulation of repair foci formation by ubiquitination, our data demonstrate deubiquitination as a previously unrecognized critical step in promoting foci formation. Furthermore, we define a pathway by which BRUCE and USP8 activate BRIT1–switch/sucrose nonfermentable (SWI-SNF)–mediated chromatin relaxation to maximize cell responsiveness to DNA damage. Thus, BRUCE represents a novel component in safeguarding genomic stability and a promising therapeutic target in diseases of genomic instability such as cancer.
Transcription factor Hes1 modulates osteoarthritis development in cooperation with calcium/calmodulin-dependent protein kinase 2
Authors: Sugita Shurei , Hosaka Yoko , Okada Keita , Mori Daisuke , Yano Fumiko , Kobayashi Hiroshi , Taniguchi Yuki , Mori Yoshifumi , Okuma Tomotake , Chang Song Ho , Kawata Manabu , Taketomi Shuji , Chikuda Hirotaka , Akiyama Haruhiko , Kageyama Ryoichiro , Chung Ung-il , Tanaka Sakae , Kawaguchi Hiroshi , Ohba Shinsuke , Saito Taku
Published: March 2015

Significance

Here we demonstrate that Hes1, an important target of Notch signaling, modulated pathogenesis of osteoarthritis by usingCol2a1-CreERT;Hes1fl/flmice.Adamts5andMmp13, catabolic enzymes that break down cartilage matrix, were induced by Hes1. Additionally, microarray analysis and ChIP-seq revealed novel Hes1 target genes, includingIl6andIl1rl1, coding a receptor for IL-33. CaMK2δ was activated during osteoarthritis development. CaMK2δ formed a protein complex with Hes1, and switched it from a transcriptional repressor to a transcriptional activator to induce cartilage catabolic factors.
Alpha-carboxy nucleoside phosphonates as universal nucleoside triphosphate mimics
Authors: Balzarini Jan , Das Kalyan , Bernatchez Jean A. , Martinez Sergio E. , Ngure Marianne , Keane Sarah , Ford Alan , Maguire Nuala , Mullins Niki , John Jubi , Kim Youngju , Dehaen Wim , Vande Voorde Johan , Liekens Sandra , Naesens Lieve , Götte Matthias , Maguire Anita R. , Arnold Eddy
Published: March 2015

Significance

The polymerization of nucleotides by DNA polymerases occurs through a common mechanism based on similar highly conserved amino acid motifs and the universal role of the coordination of Mg
2+
by three dNTP phosphate oxygens. Based on these universal principles, we aimed at designing a dNTP mimic that could interact with a broad variety of DNA polymerases and should consist of three major indispensable entities: a nucleobase for Watson–Crick base-pairing, an enzymatically and chemically stable triphosphate replacement that can efficiently coordinate the Mg
2+
cation, and a variable linker moiety between the nucleobase and the modified phosphate. The resulting α-carboxy nucleoside phosphonates (α-CNPs) were structurally, kinetically, and biochemically investigated, and the novel dNTP mimics were successfully validated in several DNA polymerase models.
Effects of large-scale deforestation on precipitation in the monsoon regions: Remote versus local effects
Authors: Devaraju N. , Bala Govindasamy , Modak Angshuman
Published: March 2015

Significance

Biogeophysical effects such as albedo and evapotranspiration changes due to deforestation were shown by several studies in the past to exert strong influence on local surface temperatures. In this study, we assess the remote versus local effects of large-scale deforestation on precipitation in the monsoon regions of the world. In contrast to the dominant role of local effects on temperature changes, we find that the remote effects have a larger influence than local effects on shifting the location of the Intertropical Convergence Zone and hence precipitation in all the monsoon regions. This result has important implications for assessing the net benefits of climate change mitigation strategies such as afforestation/reforestation and for understanding changes in monsoon rainfall in past climates.
Horizontal gene transfer and gene dosage drives adaptation to wood colonization in a tree pathogen
Authors: Dhillon Braham , Feau Nicolas , Aerts Andrea L. , Beauseigle Stéphanie , Bernier Louis , Copeland Alex , Foster Adam , Gill Navdeep , Henrissat Bernard , Herath Padmini , LaButti Kurt M. , Levasseur Anthony , Lindquist Erika A. , Majoor Eline , Ohm Robin A. , Pangilinan Jasmyn L. , Pribowo Amadeus , Saddler John N. , Sakalidis Monique L. , de Vries Ronald P. , Grigoriev Igor V. , Goodwin Stephen B. , Tanguay Philippe , Hamelin Richard C.
Published: March 2015

Significance

Some of the most damaging tree diseases are caused by pathogens that induce cankers, a stem deformation often lethal. To investigate the cause of this adaptation, we sequenced the genomes of poplar pathogens that do and do not cause cankers. We found a unique cluster of genes that produce secondary metabolites and are co-activated when the canker pathogen is grown on poplar wood and leaves. The gene genealogy is discordant with the species phylogeny, showing a signature of horizontal transfer from fungi associated with wood decay. Furthermore, genes encoding hemicellulose-degrading enzymes are up-regulated on poplar wood chips, with some having been acquired horizontally. We propose that adaptation to colonize poplar woody stems is the result of acquisition of these genes.
Nanomechanics and intermolecular forces of amyloid revealed by four-dimensional electron microscopy
Authors: Fitzpatrick Anthony W. P. , Vanacore Giovanni M. , Zewail Ahmed H.
Published: March 2015

Significance

The biomechanics of amyloid underlies its function in living organisms. We use four-dimensional electron microscopy to systematically dissect the nanoscale origins of amyloid elasticity by measuring the bond stiffnesses of the intermolecular forces stabilizing each of its three characteristic packing interfaces. We find amyloid to have a pronounced mechanical anisotropy with longitudinal, hydrogen bonding 20 times stiffer than transverse, amphiphilic, and electrostatic interactions. Such strongly anisotropic elastic properties are likely to give rise to length-dependent mechanical behavior with short fibrils possessing significantly different material properties than longer fibrils. This is of great importance in understanding fibril–membrane interactions and fragmentation mechanisms, both of which are thought to play a crucial role in the spread of amyloid diseases.
Regulatory link between DNA methylation and active demethylation in
Arabidopsis
Authors: Lei Mingguang , Zhang Huiming , Julian Russell , Tang Kai , Xie Shaojun , Zhu Jian-Kang
Published: March 2015

Significance

DNA methylation is critical for transposon silencing and gene regulation. DNA methylation levels are determined by the combined activities of DNA methyltransferases and demethylases. This study found a 39-bp DNA methylation monitoring sequence (MEMS) in the promoter of the DNA demethylase REPRESSOR OF SILENCING 1 (
ROS1
) gene of
Arabidopsis
plants. DNA methylation of MEMS is responsive to both RNA-directed DNA methylation and ROS1-dependent active demethylation. Thus, MEMS can sense DNA methylation and demethylation activities, and it regulates genomic DNA methylation by adjusting
ROS1
expression levels. Our results suggest that the
ROS1
promoter, with the MEMS and an adjacent helitron transposon element, functions as a “methylstat” that senses and regulates genomic DNA methylation levels.
Failed CTL/NK cell killing and cytokine hypersecretion are directly linked through prolonged synapse time
Authors: Jenkins Misty R. , Rudd-Schmidt Jesse A. , Lopez Jamie A. , Ramsbottom Kelly M. , Mannering Stuart I. , Andrews Daniel M. , Voskoboinik Ilia , Trapani Joseph A.
Published: March 2015

Failure of cytotoxic T lymphocytes (CTLs) or natural killer (NK) cells to kill target cells by perforin (Prf)/granzyme (Gzm)-induced apoptosis causes severe immune dysregulation. In familial hemophagocytic lymphohistiocytosis, Prf-deficient infants suffer a fatal “cytokine storm” resulting from macrophage overactivation, but the link to failed target cell death is not understood. We show that prolonged target cell survival greatly amplifies the quanta of inflammatory cytokines secreted by CTLs/NK cells and that interferon-γ (IFN-γ) directly invokes the activation and secondary overproduction of proinflammatory IL-6 from naive macrophages. Furthermore, using live cell microscopy to visualize hundreds of synapses formed between wild-type, Prf-null, or GzmA/B-null CTLs/NK cells and their targets in real time, we show that hypersecretion of IL-2, TNF, IFN-γ, and various chemokines is linked to failed disengagement of Prf- or Gzm-deficient lymphocytes from their targets, with mean synapse time increased fivefold, from ∼8 to >40 min. Surprisingly, the signal for detachment arose from the dying target cell and was caspase dependent, as delaying target cell death with various forms of caspase blockade also prevented their disengagement from fully competent CTLs/NK cells and caused cytokine hypersecretion. Our findings provide the cellular mechanism through which failed killing by lymphocytes causes systemic inflammation involving recruitment and activation of myeloid cells.
The KRAB zinc finger protein ZFP809 is required to initiate epigenetic silencing of endogenous retroviruses
Authors: Wolf Gernot , Yang Peng , Füchtbauer Annette C. , Füchtbauer Ernst-Martin , Silva Andreia M. , Park Chungoo , Wu Warren , Nielsen Anders L. , Pedersen Finn S. , Macfarlan Todd S.
Published: March 2015

Retroviruses have been invading mammalian germlines for millions of years, accumulating in the form of endogenous retroviruses (ERVs) that account for nearly one-tenth of the mouse and human genomes. ERVs are epigenetically silenced during development, yet the cellular factors recognizing ERVs in a sequence-specific manner remain elusive. Here we demonstrate that ZFP809, a member of the Krüppel-associated box zinc finger protein (KRAB-ZFP) family, initiates the silencing of ERVs in a sequence-specific manner via recruitment of heterochromatin-inducing complexes. ZFP809 knockout mice display highly elevated levels of ZFP809-targeted ERVs in somatic tissues. ERV reactivation is accompanied by an epigenetic shift from repressive to active histone modifications but only slight destabilization of DNA methylation. Importantly, using conditional alleles and rescue experiments, we demonstrate that ZFP809 is required to initiate ERV silencing during embryonic development but becomes largely dispensable in somatic tissues. Finally, we show that the DNA-binding specificity of ZFP809 is evolutionarily conserved in the Muroidea superfamily of rodents and predates the endogenization of retroviruses presently targeted by ZFP809 in Mus musculus. In sum, these data provide compelling evidence that ZFP809 evolved to recognize foreign DNA and establish histone modification-based epigenetic silencing of ERVs.
A genome-scale in vivo loss-of-function screen identifies Phf6 as a lineage-specific regulator of leukemia cell growth
Authors: Meacham Corbin E. , Lawton Lee N. , Soto-Feliciano Yadira M. , Pritchard Justin R. , Joughin Brian A. , Ehrenberger Tobias , Fenouille Nina , Zuber Johannes , Williams Richard T. , Young Richard A. , Hemann Michael T.
Published: March 2015

We performed a genome-scale shRNA screen for modulators of B-cell leukemia progression in vivo. Results from this work revealed dramatic distinctions between the relative effects of shRNAs on the growth of tumor cells in culture versus in their native microenvironment. Specifically, we identified many “context-specific” regulators of leukemia development. These included the gene encoding the zinc finger protein Phf6. While inactivating mutations in PHF6 are commonly observed in human myeloid and T-cell malignancies, we found that Phf6 suppression in B-cell malignancies impairs tumor progression. Thus, Phf6 is a “lineage-specific” cancer gene that plays opposing roles in developmentally distinct hematopoietic malignancies.
The DREAM complex promotes gene body H2A.Z for target repression
Authors: Latorre Isabel , Chesney Michael A. , Garrigues Jacob M. , Stempor Przemyslaw , Appert Alex , Francesconi Mirko , Strome Susan , Ahringer Julie
Published: March 2015

The DREAM (DP, Retinoblastoma [Rb]-like, E2F, and MuvB) complex controls cellular quiescence by repressing cell cycle genes, but its mechanism of action is poorly understood. Here we show that Caenorhabditis elegans DREAM targets have an unusual pattern of high gene body HTZ-1/H2A.Z. In mutants of lin-35, the sole p130/Rb-like gene in C. elegans, DREAM targets have reduced gene body HTZ-1/H2A.Z and increased expression. Consistent with a repressive role for gene body H2A.Z, many DREAM targets are up-regulated in htz-1/H2A.Z mutants. Our results indicate that the DREAM complex facilitates high gene body HTZ-1/H2A.Z, which plays a role in target gene repression.
The changing dynamics in the worldwide mobile phone market: creating excellence through innovation management and collaborative relationships
Authors: Medhi Pankaj Kumar , Mondal Sandeep
Published: March 2015

Subject area

Supply chain management (SCM).

Study level/applicability

Graduate students.

Case overview

In recent times, the world market of mobile phone is in a flux due to many phenomena of importance like strong emergence of smartphones, Nokia losing market share in all segments of market and fast technological and supply chain innovation by players like Apple and Google. Elements of SCM and the way technology is acquired have assumed a place of importance to compete in the global market. A new standard of innovation and SCM is emerging together as the rules of market dominance are re-written all-over again.

Expected learning outcomes

After completion of the case study, the students will understand: role of technological innovation in high-tech industry and global supply chains in changing the consumer behavior world over; the classic battle for market dominance with a new way of innovation management in technology and processes to create most efficient global supply chains; importance of SCM practices of collaboration like tighter partner integration, use of power asymmetry and contract by dominant players to create efficient supply chains; and how visionaries like late Steve Job are shaping the new era of technology.

Supplementary materials

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Stability of jets in a shallow water layer
Authors: Wan Zhanhong , Huang Saihua , Sun Zhilin , You Zhenjiang
Published: March 2015

Purpose

– The present work is devoted to the numerical study of the stability of shallow jet. The effects of important parameters on the stability behavior for large scale shallow jets are considered and investigated. Connections between the stability theory and observed features reported in the literature are emphasized. The paper aims to discuss these issues.

Design/methodology/approach

– A linear stability analysis of shallow jet incorporating the effects of bottom topography, bed friction and viscosity has been carried out by using the shallow water stability equation derived from the depth averaged shallow water equations in conjunction with both Chézy and Manning resistance formulae. Effects of the following main factors on the stability of shallow water jets are examined: Rossby number, bottom friction number, Reynolds number, topographic parameters, base velocity profile and resistance model. Special attention has been paid to the Coriolis effects on the jet stability by limiting the rotation number in the range of Ro∈[0, 1.0].

Findings

– It is found that the Rossby number may either amplify or attenuate the growth of the flow instability depending on the values of the topographic parameters. There is a regime where the near cancellation of Coriolis effects due to other relevant parameters influences is responsible for enhancement of stability. The instability can be suppressed by the bottom friction when the bottom friction number is large enough. The amplification rate may become sensitive to the relatively small Reynolds number. The stability region using the Manning formula is larger than that using the Chézy formula. The combination of these effects may stabilize or destabilize the shallow jet flow. These results of the stability analysis are compared with those from the literature.

Originality/value

– Results of linear stability analysis on shallow jets along roughness bottom bed are presented. Different from the previous studies, this paper includes the effects of bottom topography, Rossby number, Reynolds number, resistance formula and bed friction. It is found that the influence of Reynolds number on the stability of the jet is notable for relative small value. Therefore, it is important to experimental investigators that the viscosity should be considered with comparison to the results from inviscid assumption. In contrast with the classical analysis, the use of multi-parameters of the base velocity and topographic profile gives an extension to the jet stability analysis. To characterize the large scale motion, besides the bottom friction as proposed in the related literature, the Reynolds number Re, Rossby number Ro, the topographic parameters and parameters controlling base velocity profile may also be important to the stability analysis of shallow jet flows.