bluuebunny/crossref_metadata_2025 huggingface dataset:
Search for time lag in intra-day variability of Sgr A*
Authors: Miyazaki A. , Lee S. S. , Sohn B. W. , Jung T. , Tsuboi M. , Tsutsumi T.
Published: May 2014

We searched the time lag between the intra-day variables (IDVs) of Sagittarius A* at 22, 43, and 86 GHz bands using the Korean VLBI Network (KVN). The time lags between the IDV flare peaks at 22 and 43 GHz are reported, and they suggest that the flare emissions come from adiabatically expanding plasma blobs, ejected close to the Galactic center black hole. We searched the time lags between light curves at 90 and 102 GHz using the Nobeyama Millimeter Array, but could not find significant time lags. In order to detect the diversity of the time lags of Sgr A* flares, we performed observations of Sgr A* in the 22, 43, and 86 GHz bands using the KVN in the winter of 2013. Because the receiver system of KVN can observe Sgr A* in these three bands simultaneously, the KVN is very useful to detect the time lags of Sgr A* flares.
Monitoring observations of the interaction between Sgr A* and G2 with the Karl G. Jansky Very Large Array
Authors: Sjouwerman Loránt O. , Chandler Claire J.
Published: May 2014

We report on an ongoing community service observing program to follow the expected encounter of the G2 cloud with the black hole Sgr A* in 2013. The NRAO Karl G. Jansky Very Large Array (VLA) has been observing the Sgr A region since 2012 October on roughly a bi-monthly interval, each for two hours, cycling through eight observing bands at their default continuum frequencies, using 2 GHz of bandwidth. The data from the monitoring program are publicly available through the NRAO data archive immediately after observing has completed, and the flux densities are published by NRAO staff as soon as the data are reduced. The cumulative results of the monitoring effort are posted on the service observing web page https://science.nrao.edu/science/service-observing and so far do not indicate a significant brightening of the emission from the direction of Sgr A* over the period 2012 October to 2013 September, within the calibration uncertainties.
Discovery of a recombination dominant plasma: a relic of a giant flare of Sgr A*?
Authors: Nakashima S. , Nobukawa M. , Uchida H. , Tanaka T. , Tsuru T. G. , Koyama K. , Uchiyama H. , Murakami H.
Published: May 2014

We present the discovery of out-flow like plasma emissions with the Suzaku and ASCA data. Those plasmas have a size of ∼150 pc. Remarkably, the southern plasma is in a recombination dominant phase, which is not predicted by standard shock heating. A plausible scenario is either photoionization due to strong jet-like X-rays from Sgr A* or rapid cooling due to adiabatic expansion of a blowout plasma from the Galactic center about 105 years ago.
A new perspective on the radio active zone at the Galactic center – feedback from nuclear activities
Authors: Zhao J.-H. , Morris M. R. , Goss W. M.
Published: May 2014

Based on our deep image of Sgr A using broadband data observed with the VLA† at 6 cm, we present a new perspective of the radio bright zone at the Galactic center. We further show the radio detection of the X-ray Cannonball, a candidate neutron star associated with the Galactic center SNR Sgr A East. The radio image is compared with the Chandra X-ray image to show the detailed structure of the radio counterparts of the bipolar X-ray lobes. The bipolar lobes are likely produced by the winds from the activities within Sgr A West, which could be collimated by the inertia of gas in the CND, or by the momentum driving of Sgr A*; and the poloidal magnetic fields likely play an important role in the collimation. The less-collimated SE lobe, in comparison to the NW one, is perhaps due to the fact that the Sgr A East SN might have locally reconfigured the magnetic field toward negative galactic latitudes. In agreement with the X-ray observations, the time-scale of ∼1 × 104 yr estimated for the outermost radio ring appears to be comparable to the inferred age of the Sgr A East SNR.
The 3 Ms Chandra campaign on Sgr A*: a census of X-ray flaring activity from the Galactic center
Authors: Neilsen J. , Nowak M. A. , Gammie C. , Dexter J. , Markoff S. , Haggard D. , Nayakshin S. , Wang Q. D. , Grosso N. , Porquet D. , Tomsick J. A. , Degenaar N. , Fragile P. C. , Houck J. C. , Wijnands R. , Miller J. M. , Baganoff F. K.
Published: May 2014

Over the last decade, X-ray observations of Sgr A* have revealed a black hole in a deep sleep, punctuated roughly once per day by brief flares. The extreme X-ray faintness of this supermassive black hole has been a long-standing puzzle in black hole accretion. To study the accretion processes in the Galactic center, Chandra (in concert with numerous ground- and space-based observatories) undertook a 3 Ms campaign on Sgr A* in 2012. With its excellent observing cadence, sensitivity, and spectral resolution, this Chandra X-ray Visionary Project (XVP) provides an unprecedented opportunity to study the behavior of the closest supermassive black hole. We present a progress report from our ongoing study of X-ray flares, including the brightest flare ever seen from Sgr A*. Focusing on the statistics of the flares and the quiescent emission, we discuss the physical implications of X-ray variability in the Galactic center.
Time lags between starburst and AGN activity in galaxy mergers
Authors: Blank M. , Duschl W. J.
Published: May 2014

We show that the observed time lag between starburst and AGN activity can be explained by a viscous time lag the gas needs to flow through the AGN's accretion disk before reaching the central black hole. Our calculations reproduce the observed time lag and are in agreement with the observed correlation between black hole mass and stellar velocity dispersion.
Dark matter in the Galactic center
Authors: Linden Tim
Published: May 2014

In addition to boasting the highest density of baryonic matter in our galaxy, the center of the Milky Way is also believed to contain an extremely high density of dark matter particles. While dark matter is expected to be gravitationally subdominant to baryons near the Galactic center, many models allow for the annihilation of dark matter into standard model particles, a phenomenon which could be a significant source of high energy radiation in the Galactic center region. In fact, standard models of the dark matter density distribution and annihilation spectrum predict that dark matter at the Galactic center would (1) produce the brightest flux from dark matter annihilation of any region in the sky, and (2) contribute a significant portion of the total γ-ray luminosity observed within several degrees of the Galactic center by the Fermi/LAT. This makes the effort to understand and differentiate the morphologies and spectral features of dark matter and astrophysical γ-ray emission at the Galactic center potentially rewarding. Here, I will summarize the recent developments in indirect searches for dark matter annihilation at the Galactic center, and discuss several of the difficulties in producing accurate models of the high energy astrophysical emission. Finally, I will comment on current efforts to produce multi-wavelength models which better constrain or indicate a dark matter signal at the Galactic center.
Diffusion of cosmic-ray electrons in the Galactic centre molecular cloud G0.13–0.13
Authors: Lehmann Andrew , Wardle Mark
Published: May 2014

The Galactic center (GC) molecular cloud G0.13–0.13 exhibits a shell morphology in CS J = (1 − 0), with ∼ 105 solar masses and expansion speed ∼ 20 km s−1, yielding a total kinetic energy ∼ 1051 erg. Its morphology is also suggestive of an interaction with the nonthermal filaments of the GC arc. 74 MHz emission indicates the presence of a substantial population of low energy electrons permeating the cloud, which could either be produced by the interaction with the arc or accelerated in the shock waves responsible for the cloud's expansion. These scenarios are explored using time dependent diffusion models.

With these diffusion models, we determine the penetration of low-energy cosmic-ray electrons accelerated into G0.13–0.13 and calculate the spatial distribution of the cosmic-ray ionization and heating rates. We show that the 6.4 keV Fe Kα line emission associated with the electron population provides an observational diagnostic to distinguish these two acceleration scenarios.

We discuss the implications of our results for understanding the distinct character of clouds in the central molecular zone compared to clouds in the Galactic disk, and how GC nonthermal filaments interact with molecular clouds.
A new era for low frequency Galactic center transient monitoring
Authors: Kassim N. E. , Hyman S. D. , Intema H. , Lazio T. J. W.
Published: May 2014

An upgrade of the low frequency observing system of the VLA developed by NRL and NRAO, called low band (LB), will open a new era of Galactic center (GC) transient monitoring. Our previous searches using the VLA and GMRT have revealed a modest number of radio-selected transients, but have been severely sensitivity and observing time limited. The new LB system, currently accessing the 236--492 MHz frequency range, promises ≥5 × improved sensitivity over the legacy VLA system. The new system is emerging from commissioning in time to catch any enhanced sub-GHz emission from the G2 cloud event, and we review existing limits based on recent observations. We also describe a proposed 24/7 commensal system, called the LOw Band Observatory (LOBO). LOBO offers over 100 VLA GC monitoring hours per year, possibly revealing new transients and helping validate ASTRO2010's anticipation of a new era of transient radio astronomy. A funded LOBO pathfinder called the VLA Low Frequency Ionosphere and Transient Experiment (VLITE) is under development. Finally, we consider the impact of LB and LOBO on our GC monitoring program.
History as a laboratory to better understand the formation of institutions
Authors: VAN BAVEL BAS
Published: May 2014

A main instrument for better understanding the formation of institutions, and explaining the differences in their long-run development between periods and societies, would be to use history as a laboratory, allowing us to test the hypotheses developed in the social sciences. This paper discusses the study by Douglas Allen,The Institutional Revolution, in that context, in order to identify some of the pitfalls in the current attempts by economists to use historical analysis. Next, the paper places his English case into a comparative perspective, helped by the recent insights gained by economic and social history, to see how these pitfalls can be avoided. Based on this, I argue for comparisons at the regional, national and global levels, and for a multidimensional view which includes social contextualization, combined with an open eye for discontinuity in long-run patterns, in order to avoid one-dimensional and teleological approaches to institutional change.
More Than Theory
Authors: Neubauer (These authors contributed equally to this project Andreas B. , Drapaniotis (These authors contributed equally to this proje Philipp M. , Wahl Hans-Werner
Published: May 2014

A randomly drawn sample of 535 empirical articles representing 50% of the papers published between 1990 and 1994 and between 2000 and 2004 in Psychology and Aging and the Journal of Gerontology: Psychological Sciences were analyzed based on a newly developed coding scheme. This instrument allowed us to systematically evaluate types and contents of geropsychological theoretical entities used. We found that theoretical entity use significantly increased from 66.3% to 82.0%, which is much higher than only coding the material according to the explicit use of “theory,” as we have found in previous work (30% versus 44%, respectively; Drapaniotis, Neubauer, & Wahl, 2013 ). We also observed that even the most extensively cited entities, i.e., the mental-slowing hypothesis, the inhibitory-deficit hypothesis, and socioemotional selectivity theory, were cited in only a rather limited number of articles. We conclude that the field of geropsychology relies on a wide and quite heterogeneous array of theoretical entities.
P53-regulated long non-coding RNA TUG1 affects cell proliferation in human non-small cell lung cancer, partly through epigenetically regulating HOXB7 expression
Authors: Zhang E-b , Yin D-d , Sun M , Kong R , Liu X-h , You L-h , Han L , Xia R , Wang K-m , Yang J-s , De W , Shu Y-q , Wang Z-x
Published: May 2014

Recently, a novel class of transcripts, long non-coding RNAs (lncRNAs), is being identified at a rapid pace. These RNAs have critical roles in diverse biological processes, including tumorigenesis. Here we report that taurine-upregulated gene 1 (TUG1), a 7.1-kb lncRNA, recruiting and binding to polycomb repressive complex 2 (PRC2), is generally downregulated in non-small cell lung carcinoma (NSCLC) tissues. In a cohort of 192 NSCLC patients, the lower expression of TUG1 was associated with a higher TNM stage and tumor size, as well as poorer overall survival (P<0.001). Univariate and multivariate analyses revealed that TUG1 expression serves as an independent predictor for overall survival (P<0.001). Further experiments revealed that TUG1 expression was induced by p53, and luciferase and chromatin immunoprecipitation (ChIP) assays confirmed that TUG1 was a direct transcriptional target of p53. TUG1 knockdown significantly promoted the proliferation in vitro and in vivo. Moreover, the lncRNA-mediated regulation of the expression of HOX genes in tumorigenesis and development has been recently receiving increased attention. Interestingly, inhibition of TUG1 could upregulate homeobox B7 (HOXB7) expression; ChIP assays demonstrated that the promoter of HOXB7 locus was bound by EZH2 (enhancer of zeste homolog 2), a key component of PRC2, and was H3K27 trimethylated. This TUG1-mediated growth regulation is in part due to specific modulation of HOXB7, thus participating in AKT and MAPK pathways. Together, these results suggest that p53-regulated TUG1 is a growth regulator, which acts in part through control of HOXB7. The p53/TUG1/PRC2/HOXB7 interaction might serve as targets for NSCLC diagnosis and therapy.
Erratum: Phylogenetic distribution of three pathways for propionate production within the human gut microbiota
Authors: Reichardt Nicole , Duncan Sylvia H , Young Pauline , Belenguer Alvaro , McWilliam Leitch Carol , Scott Karen P , Flint Harry J , Louis Petra
Published: May 2014

Correction to: The ISME Journal (2014) 8, 1323–1335; doi:10.1038/ismej.2014.14; published online 20 February 2014 Since the publication of this article, the authors have identified two omissions within their paper, the main one being that the author affiliations were incomplete. The correct list is shown here.
Solvent-free aerobic oxidation of alcohols using supported gold palladium nanoalloys prepared by a modified impregnation method
Authors: Morad Moataz , Sankar Meenakshisundaram , Cao Enhong , Nowicka Ewa , Davies Thomas E. , Miedziak Peter J. , Morgan David J. , Knight David W. , Bethell Donald , Gavriilidis Asterios , Hutchings Graham J.
Published: May 2014

The synthesis of stable, supported, bimetallic nanoalloys with controlled size, morphology and composition for selective alcohol oxidation.
Ion exchange and intercalation properties of layered double hydroxides towards halide anions
Authors: Costantino Umberto , Vivani Riccardo , Bastianini Maria , Costantino Ferdinando , Nocchetti Morena
Published: May 2014

The selectivity towards halides and the mechanism of ion exchange of ZnAl-LDH in the chloride form (X− = F−, Br−, I−) were investigated using ion exchange isotherms of Cl−/X−.
Synthesis of TiO2 nanotubes with ZnO nanoparticles to achieve antibacterial properties and stem cell compatibility
Authors: Liu Wenwen , Su Penglei , Chen Su , Wang Na , Ma Yuanping , Liu Yiran , Wang Jinshu , Zhang Zhenting , Li Hongyi , Webster Thomas J.
Published: May 2014

ZnO incorporated Ti samples inhibited the expression of Streptococcus mutans bacterial adhesion genes and also inhibited P. gingivalis proliferation. (a) S. mutans and (b) P. gingivalis on the sample of TNT–Zn0.075.
Gold nanoparticle-packed microdisks for multiplex Raman labelling of cells
Authors: Zhang Peipei , Xia Junfei , Wang Zhibin , Guan Jingjiao
Published: May 2014

This paper reports development of disk-shaped particulate microdevices (termed microdisks) containing densely packed gold nanoparticles for multiplex labeling of cells based on surface enhanced Raman scattering.
Design, synthesis, conformational analysis and application of indolizidin-2-one dipeptide mimics
Authors: Khashper Arkady , Lubell William D.
Published: May 2014

Growth in the field of peptide mimicry over the past few decades has resulted in the synthesis of many new compounds and the investigation of novel pharmacological agents.
Transcriptome-wide identification and characterization of Ornithogalum saundersiae phenylalanine ammonia lyase gene family
Authors: Wang Zhi-Biao , Chen Xi , Wang Wei , Cheng Ke-Di , Kong Jian-Qiang
Published: May 2014

Transcriptome-wide identification and characterization ofOrnithogalum saundersiaephenylalanine ammonia lyase gene family.
New strategies for cartilage regeneration exploiting selected glycosaminoglycans to enhance cell fate determination
Authors: Ayerst Bethanie I. , Day Anthony J. , Nurcombe Victor , Cool Simon M. , Merry Catherine L.R.
Published: May 2014

Most research strategies for cartilage tissue engineering use extended culture with complex media loaded with costly GFs (growth factors) to drive tissue assembly and yet they result in the production of cartilage with inferior mechanical and structural properties compared with the natural tissue. Recent evidence suggests that GAGs (glycosaminoglycans) incorporated into tissue engineering scaffolds can sequester and/or activate GFs and thereby more effectively mimic the natural ECM (extracellular matrix). Such approaches may have potential for the improvement of cartilage engineering. However, natural GAGs are structurally complex and heterogeneous, making structure–function relationships hard to determine and clinical translation difficult. Importantly, subfractions of GAGs with specific chain lengths and sulfation patterns have been shown to activate key signalling processes during stem cell differentiation. In addition, recently, GAGs have been bound to synthetic biomaterials, such as electrospun scaffolds and hydrogels, in biologically active conformations, and methods to purify and select affinity-matched GAGs for specific GFs have also been developed. The identification and use of specific GAG moieties to promote chondrogenesis is therefore an exciting new avenue of research. Combining these with synthetic biomaterials may allow a more effective mimicry of the natural ECM, reduction in the need for expensive GFs, and perhaps the deposition of an articular cartilage-like matrix in a clinically relevant manner.
Lineage potential, plasticity and environmental reprogramming of epithelial stem/progenitor cells
Authors: Amici Alessandro W. , Onikoyi Fatai O. , Bonfanti Paola
Published: May 2014

Recent evidence supports and reinforces the concept that environmental cues may reprogramme somatic cells and change their natural fate. In the present review, we concentrate on environmental reprogramming and fate potency of different epithelial cells. These include stratified epithelia, such as the epidermis, hair follicle, cornea and oesophagus, as well as the thymic epithelium, which stands alone among simple and stratified epithelia, and has been shown recently to contain stem cells. In addition, we briefly discuss the pancreas as an example of plasticity of intrinsic progenitors and even differentiated cells. Of relevance, examples of plasticity and fate change characterize pathologies such as oesophageal metaplasia, whose possible cell origin is still debated, but has important implications as a pre-neoplastic event. Although much work remains to be done in order to unravel the full potential and plasticity of epithelial cells, exploitation of this phenomenon has already entered the clinical arena, and might provide new avenues for future cell therapy of these tissues.
What a Difference a Day Makes: Change in Memory for Newly Learned Word Forms Over 24 Hours
Authors: McGregor Karla K.
Published: May 2014

Purpose

This study explored the role of time and retrieval experience in the consolidation of word forms.

Method

Participants were 106 adults trained on 16 novel word-referent pairs, then tested immediately and 24 hr later for recognition and recall of word forms. In the interim, tests were repeated 2 hr or 12 hr after training, or not at all, thus varying the amount and timing of retrieval experience.

Results

Recognition accuracy was stable and speed improved over the 24-hr period. But these manifestations of consolidation did not depend on interim retrieval experience; in fact, the 2-hr interim test interfered with improvements in speed. In contrast, the number of word forms recalled increased only with interim retrieval experiences, and the 12-hr interim test was more advantageous to recall than the 2-hr test.

Conclusions

After a word form is encoded, it can become stronger with time. Retrieval experience can also strengthen the trace, but, if retrieval occurs when the memory is still labile, it can be disruptive. This complex interplay between retrieval experience and time holds implications for measuring learning outcomes and for scheduling practice in classrooms and clinics.
Management of Carotid Artery Trauma
Authors: Lee Thomas S. , Ducic Yadranko , Gordin Eli , Stroman David
Published: May 2014

With increased awareness and liberal screening of trauma patients with identified risk factors, recent case series demonstrate improved early diagnosis of carotid artery trauma before they become problematio. There remains a need for unified screening criteria for both intracranial and extracranial carotid trauma. In the absence of contraindications, antithrombotic agents should be considered in blunt carotid artery injuries, as there is a significant risk of progression of vessel injury with observation alone. Despite CTA being used as a common screening modality, it appears to lack sufficient sensitivity. DSA remains to be the gold standard in screening. Endovascular techniques are becoming more widely accepted as the primary surgical modality in the treatment of blunt extracranial carotid injuries and penetrating/blunt intracranial carotid lessions. Nonetheless, open surgical approaches are still needed for the treatment of penetrating extracranial carotid injuries and in patients with unfavorable lesions for endovascular intervention.
Note: Artificial neural networks for the automated analysis of force map data in atomic force microscopy
Authors: Braunsmann Christoph , Schäffer Tilman E.
Published: May 2014

Force curves recorded with the atomic force microscope on structured samples often show an irregular force versus indentation behavior. An analysis of such curves using standard contact models (e.g., the Sneddon model) would generate inaccurate Young's moduli. A critical inspection of the force curve shape is therefore necessary for estimating the reliability of the generated Young's modulus. We used a trained artificial neural network to automatically recognize curves of “good” and of “bad” quality. This is especially useful for improving the analysis of force maps that consist of a large number of force curves.
Laser-driven, magnetized quasi-perpendicular collisionless shocks on the Large Plasma Device
Authors: Schaeffer D. B. , Everson E. T. , Bondarenko A. S. , Clark S. E. , Constantin C. G. , Vincena S. , Van Compernolle B. , Tripathi S. K. P. , Winske D. , Gekelman W. , Niemann C.
Published: May 2014

The interaction of a laser-driven super-Alfvénic magnetic piston with a large, preformed magnetized ambient plasma has been studied by utilizing a unique experimental platform that couples the Raptor kJ-class laser system [Niemann et al., J. Instrum. 7, P03010 (2012)] to the Large Plasma Device [Gekelman et al., Rev. Sci. Instrum. 62, 2875 (1991)] at the University of California, Los Angeles. This platform provides experimental conditions of relevance to space and astrophysical magnetic collisionless shocks and, in particular, allows a detailed study of the microphysics of shock formation, including piston-ambient ion collisionless coupling. An overview of the platform and its capabilities is given, and recent experimental results on the coupling of energy between piston and ambient ions and the formation of collisionless shocks are presented and compared to theoretical and computational work. In particular, a magnetosonic pulse consistent with a low-Mach number collisionless shock is observed in a quasi-perpendicular geometry in both experiments and simulations.
On the non-stiffness of edge transport in L-mode tokamak plasmas
Authors: Sauter O. , Brunner S. , Kim D. , Merlo G. , Behn R. , Camenen Y. , Coda S. , Duval B. P. , Federspiel L. , Goodman T. P. , Karpushov A. , Merle A. , Team TCV
Published: May 2014

Transport analyses using first-principle turbulence codes and 112-D transport codes usually study radial transport properties between the tokamak plasma magnetic axis and a normalized minor radius around 0.8. In this region, heat transport shows significantly stiff properties resulting in temperature scalelength values (R∕LT) that are relatively independent of the level of the radial heat flux. We have studied experimentally in the tokamak à configuration variable [F. Hofmann et al., Plasma Phys. Controlled Fusion 36, B277 (1994)] the radial electron transport properties of the edge region, close to the last closed flux surface, namely, between ρV=V/Vedge=0.8 to 1. It is shown that electron transport is not stiff in this region and high R∕LTe values (∼20–40) can be attained even for L-mode confinement. We can define a “pedestal” location, already in L-mode regimes, where the transport characteristics change from constant logarithmic gradient, inside ρV = 0.8, to constant gradient between 0.8 and 1.0. In particular, we demonstrate, with well resolved Te and ne profiles, that the confinement improvement with plasma current Ip, with or without auxiliary heating, is due to this non-stiff edge region. This new result is used to explain the significant confinement improvement observed with negative triangularity, which could not be explained by theory to date. Preliminary local gyrokinetic simulations are now consistent with an edge, less stiff, region that is more sensitive to triangularity than further inside. We also show that increasing the electron cyclotron heating power increases the edge temperature inverse scalelength, in contrast to the value in the main plasma region. The dependence of confinement on density in ohmic plasmas is also studied and brings new insight in the understanding of the transition between linear and saturated confinement regimes, as well as of the density limit and appearance of a 2/1 tearing mode. The results presented in this paper provide an important new perspective with regards to radial transport in tokamak plasmas which goes beyond L-mode plasmas and explains some previous puzzling results. It is proposed that understanding the transport properties in this edge non-stiff region will also help in understanding the improved and high confinement edge properties.
Magnetohydrodynamically stable plasma with supercritical current density at the axis
Authors: Burdakov A. V. , Postupaev V. V. , Sudnikov A. V.
Published: May 2014

In this work, an analysis of magnetic perturbations in the GOL-3 experiment is given. In GOL-3, plasma is collectively heated in a multiple-mirror trap by a high-power electron beam. During the beam injection, the beam-plasma interaction maintains a high-level microturbulence. This provides an unusual radial profile of the net current (that consists of the beam current, current of the preliminary discharge, and the return current). The plasma core carries supercritical current density with the safety factor well below unity, but as a whole, the plasma is stable with q(a) ≈ 4. The net plasma current is counter-directed to the beam current; helicities of the magnetic field in the core and at the edge are of different signs. This forms a system with a strong magnetic shear that stabilizes the plasma core in good confinement regimes. We have found that the most pronounced magnetic perturbation is the well-known n = 1, m = 1 mode for both stable and disruptive regimes.
Role of open boundary conditions on the hysteretic behaviour of one-dimensional spin crossover nanoparticles
Authors: Chiruta Daniel , Linares Jorge , Miyashita Seiji , Boukheddaden Kamel
Published: May 2014

In order to explain clearly the role of the open boundary conditions (OBCs) on phase transition in one dimensional system, we consider an Ising model with both short-range (J) and long-range (G) interactions, which has allowed us to study the cooperative nature of spin-crossover (SCO) materials at the nanometer scale. At this end, we developed a transfer-matrix method for one-dimensional (1D) SCO system with free boundary conditions, and we give numerical evidences for how the thermal spin transition curves vary as a function of the physical parameters (J, G) or an applied pressure. Moreover for OBCs case, we have derived the bulk, surface and finite-size contributions to the free energy and we have investigated the variation of these energies as function of J and system size. We have found that the surface free energy behaves like J⟨σ⟩2, where ⟨σ⟩ is the average magnetization per site. Since the properties of the nanometric scale are dramatically influenced by the system's size (N), our analytical outcomes for the size dependence represent a step to achieve new characteristic of the future devices and also a way to find various novel properties which are absent in the bulk materials.
Effect of the fissile bead's and thermocouple wires’ sizes on the response time of a fission couple
Authors: Liang Wenfeng , Lu Yi , Li Meng , Fan Xiaoqiang , Lu Wei
Published: May 2014

The fission couple is proposed as a fast response miniature neutron detector in the measurement of time dependent energy depositions within the fissile material based on theoretical analysis, but the response time of a fission couple is relatively slow in practice. The time lag originated from heat transfer process was demonstrated to be the dominating factor by theoretical simulations and experimental verification in this paper. The response of a fission couple as a function of the bead size and the thermocouple wires’ sizes are simulated using ANSYS workbench. The decrease of wires’ diameter results in the decrease of response time, and the increase of bead's diameter leads to a slight increase of response time. During a pulse heating transient in the fuel of Chinese Fast Burst Reactor II with a FWHM of 181μs, the time lag originated from heat transfer process is about tens of microseconds for the peaks of the change rate of temperature, and is of the order of milliseconds to achieve 85% of the temperature rise for a typical fission couple with a Φ 1 mm fissile bead and two Φ 0.05 mm thermocouple wires. The results obtained provide foundation for the optimization of fission couples.
Design and feasibility study of a microgeneration system to obtain renewable energy from tidal currents
Authors: Álvarez Álvarez Eduardo , Navarro-Manso Antonio , Gutiérrez-Trashorras Antonio J. , Fernández-Francos Joaquín , Rico-Secades Manuel
Published: May 2014

Tidal energy to obtain electrical energy is yet an unexploited renewable energy. Existing generator designs and prototypes are not feasible due to the high investment conditioned by their high rated powers and off-shore locations. In addition, these prototypes are not readily available. This investigation presents a design of a microgeneration system with vertical axis microturbines. The design of the microturbines utilizes off-the-shelf electronic components, thus reducing the initial investment. The nominal data for selection of power electronic components and the total energy that can be obtained in a year are calculated. The investigation also studies the feasibility of an 80 kW microgeneration system to be applied in Spain, taking advantage of the actual electricity prices. The feasibility study quantifies the influence of the parameters: initial investment, tidal current speed, operation hours, turbine efficiency, price of electricity, and number of microturbines obtaining the limiting values of the suitable scenarios.
Effects of boron-nitride substrates on Stone-Wales defect formation in graphene: An ab initio molecular dynamics study
Authors: Jin K. , Xiao H. Y. , Zhang Y. , Weber W. J.
Published: May 2014

Ab initio molecular dynamics simulations are performed to investigate the effects of a boron nitride (BN) substrate on Stone-Wales (SW) defect formation and recovery in graphene. It is found that SW defects can be created by an off-plane recoil atom that interacts with the BN substrate. A mechanism with complete bond breakage for formation of SW defects in suspended graphene is also revealed for recoils at large displacement angles. In addition, further irradiation can result in recovery of the SW defects through a bond rotation mechanism in both graphene and graphene/BN, and the substrate has little effect on the recovery process. This study indicates that the BN substrate enhances the irradiation resistance of graphene.
Electro-optic signatures of turbulent electroconvection in dielectric liquids
Authors: Zhang X.
Published: May 2014

Signatures of turbulent electroconvection in transformer oil stressed by dc and ac voltages are identified from Kerr electro-optic measurement data. When the applied dc voltage is high enough, compared with the results with no applied voltage, the optical scintillation index and image entropy exhibit substantial enhancement and reduction, respectively, which are interpreted as temporal and spatial signatures of turbulence. Under low-frequency ac high voltages, spectral and correlational analyses indicate that there exist interacting flow and charge processes in the gap. This work also clarifies the meaning of dc steady state and the requirement on ac modulation frequency in Kerr measurements.
Effect of the compressive stress on both polarization rotation and phase transitions in PMN-30%PT single crystal
Authors: Zhang Hui
Published: May 2014

In this paper, we have investigated the dependence of both the electromechanical effect and the electrostriction on the compressive stress in PMN-30%PT single crystal on the basis of single domain polarization rotation model. In the model, the electroelastic energy induced by the compressive stress is taken into account. The results have demonstrated that the compressive stress can lead to a significant change in the initial polarization state in the crystal. The reason lies in the stress induced anisotropy which is the coupling between the compressive stress and the electrostrictive coefficients. Thus, the initial polarization state in single crystal is determined by the combination of both electrocrystalline anisotropy and the stress induced anisotropy. The compressive stress along the [100] axis can make the polarization in the crystal be perpendicular to the stress direction, and make it difficult to be polarized to the saturation. This model is useful for better understanding both the polarization rotation and electromechanical effect in ferroelectric crystals with the compressive stress present.
Spatially resolved energy dispersive x-ray spectroscopic method for in-situ evaluation of mechanical properties during the growth of a C - Pt composite nanowire
Authors: Banerjee Amit , Banerjee S. S.
Published: May 2014

A core-shell type C-Pt composite nanowire is fabricated using focused ion and electron beam induced chemical vapor deposition techniques. Using information from spatially resolved energy dispersive x-ray spectra, we detect the resonance vibration in the C-Pt composite nanowire. We use this method to measure the Young's moduli of the constituents (C, Pt) of the composite nanowire and also estimate the density of the FEB CVD grown Pt shell surrounding the C core. By measuring the resonance characteristics of the composite nanowire we estimate a Pt shell growth rate of ∼0.9 nms−1. The study is analyzed to suggest that the Pt shell growth mechanism is primarily governed by the sticking coefficient of the organometallic vapor on the C nanowire core.
Effect of soybean roasting and monensin on microbial protein synthesis, ruminal parameters and plasma metabolites of lactating dairy cows
Authors: Abdi E. , Fatahnia F. , Banadaki M. Dehghan , Azarfar A. , Mosavi S. G.
Published: May 2014

This study was conducted to evaluate the effects of inclusion of roasted whole soybean seed and monensin (MO) in the diets of lactating dairy cows on plasma metabolites, ruminal parameters, and microbial protein synthesised in the rumen. Four multiparous Holstein lactating dairy cows (third parity; 656 ± 55 kg of liveweight; 83 ± 10 days in milk; 35 ± 4 kg/day milk yield) were assigned to a balanced 4 × 4 Latin square design. Each experimental period lasted 21 days with 14 days of treatment adaptation and 7 days of data collection. The control diet (C) was a total mixed ration consisting of 40% forage and 60% concentrate mixture on a dry matter (DM) basis. These cows were randomly assigned to one of the four dietary treatments. The first treatment was the C diet of unprocessed whole soybean seed, second was the C diet supplemented with 24 mg of MO/kg of DM (M), the third was roasted whole soybean seed (R) and the fourth treatment was R diet supplemented with 24 mg of MO/kg of DM (RM). Urinary excretion of creatinine and purine derivatives, microbial protein synthesised in the rumen, rumen pH and rumen concentrations of volatile fatty acids and ammonia were similar among the dietary treatments (P > 0.05). Orthogonal contrasts showed that the rumen concentration of acetate was lower in MO-supplemented cows than non-supplemented cows (P < 0.05). Dietary treatments had no effects on plasma concentrations of glucose, total cholesterol, triglycerides and total protein (P > 0.05). Plasma concentration of urea was significantly lower in cows fed with the RM diet compared with cows fed the C and M diets (P < 0.05). In conclusion, dietary treatments had no effect on microbial protein synthesised in the rumen, plasma metabolites (except for plasma concentration of urea) and ruminal parameters of dairy cows.
Re-used progesterone devices efficiently synchronise oestrus and ovulation after autoclaving process in Toggenburg goats during the breeding season
Authors: Souza-Fabjan J. M. G. , Torres C. A. A. , Maia A. L. R. S. , Brandão F. Z. , Oba E. , Bertoldo M. J. , Fonseca J. F.
Published: May 2014

This study compared new and previously used (and autoclaved) progesterone devices for synchronisation of oestrus during the breeding season in Toggenburg goats. Nulliparous (n = 17) or lactating (n = 50) received new intravaginal devices containing 0.3 g progesterone (CONTROL), or similar devices previously used for either 6 (USED6) or 12 (USED12) days and subsequently autoclaved. All goats received 5 mg dinoprost at device insertion and 200 IU equine chorionic gonadotropin 5 days later and all devices were removed after 6 days. After device removal, females were mated by fertile bucks. Ovarian ultrasonography was performed every 12 h after device removal until ovulation detection. Blood samples were collected for determination of plasma progesterone concentration in different moments and intervals (from 7 days before device insertion to 3 days after its removal). There was no difference (P > 0.05) among groups CONTROL, USED6 or USED12 for: oestrus response [75% (18/24), 77% (17/22) or 71% (15/21), respectively]; duration of oestrus (30.7 ± 3.4, 31.8 ± 1.7 or 32.8 ± 3.4 h), percentage of ovulating goats [67% (6/9), 78% (7/9) or 56% (5/9)], ovulation rate (1.3 ± 0.2, 1.4 ± 0.2 or 1.8 ± 0.4 units of corpora lutea), average follicle diameter (6.2 ± 0.1, 6.7 ± 0.1 or 6.8 ± 0.3 mm) and pregnancy rate [54% (13/24), 50% (11/22) or 48% (10/21)]. Plasma progesterone concentrations were not different (P > 0.05) for does among treatments and between nulliparous and lactating females. In conclusion, autoclaved, previously used intravaginal progesterone devices are effective in synchronising oestrus and ovulation in cyclic goats during the breeding season.
A Highly Selective and Sensitive Chemosensor for Colorimetric and Fluorescent Detection of Al3+ and Living Cell Imaging
Authors: Li Xiao-Bo , Chen Jia-Yi , Wang En-Ju
Published: May 2014

A colorimetric and fluorescent dual chemosensor for detecting Al3+, (E)-N′-((2-hydroxynaphthalen-1-yl)methylene)nicotinohydrazide (HNN), was developed by combining 2-hydroxy-1-naphthaldehyde with nicotinohydrazide. Addition of Al3+ to EtOH–H2O solution of HNN gives rise to a visible colour change from colourless to light blue and a significantly enhanced fluorescence. Other metal ions including Na+, K+, Ca2+, Mg2+, Mn2+, Co2+, Ni2+, Cu2+, Cr3+, Ag+, Pb2+, Zn2+, Cd2+, Hg2+, Fe2+, and Fe3+ have no or little effect on the specific response of HNN to Al3+. The binding mode of HNN–Al3+ complex was further clarified by electrospray ionisation mass spectrometry and 1H NMR titration experiments.
Overcoming the challenges of measuring the abundance of a cryptic macropod: is a qualitative approach good enough?
Authors: Bain Karlene , Wayne Adrian , Bencini Roberta
Published: May 2014

Context
An understanding of population size and status is necessary for the implementation of appropriate conservation measures to recover threatened taxa. Mark–recapture studies at large spatial scales are impractical and expensive and a rapid survey technique is an attractive option to provide a measure of relative abundance for cryptic species, using indicators of activity.

Aims
The aim of our study was to use conventional methods for population estimation to calibrate a rapid survey technique for the quokka (Setonix brachyurus) in the southern forests of Western Australia, with a view to providing quantitative outcomes from this widely adopted monitoring approach.

Methods
We evaluated the accuracy of relative abundances obtained from the rapid survey technique by comparing them with abundance estimates obtained through established methods for the estimation of populations, including web-based mark–recapture and transect-based counts of activity indicators and sightings.

Key results
The rapid survey technique was effective at determining presence of quokkas but resulted in an over-estimation of population size because of inaccurate assumptions about occupancy and relative abundance of animals. An alternative survey method based on counts of fresh faecal-pellet groups was found to provide a more reliable and practical estimation of population abundance (R2 = 0.97).

Conclusions
Activity indices can be used to quantify population abundance, but only for indicators of activity that can be detected readily and for which freshness of activity can be determined.

Implications
Our findings suggest that a rapid survey based on activity indices can be used to evaluate quantitatively the population size of a species that is rare and potentially mobile at a landscape scale. The attraction of these techniques is that they provide a rapid and inexpensive survey option that is potentially applicable to any cryptic and/or threatened species and is practical for resource-constrained land managers.
Combining linkage and association mapping identifiesRECEPTOR-LIKE PROTEIN KINASE1as an essentialArabidopsisshoot regeneration gene
Authors: Motte Hans , Vercauteren Annelies , Depuydt Stephen , Landschoot Sofie , Geelen Danny , Werbrouck Stefaan , Goormachtig Sofie , Vuylsteke Marnik , Vereecke Danny
Published: May 2014

Significance

The regeneration of entire plants from explants is an important step in plant production and plant transformation protocols. Despite recent advances in the knowledge on the molecular basis of regeneration, many aspects of the process and the causes of regeneration recalcitrance are still poorly understood. We combined linkage with association mapping to find genes underlying the natural variation of shoot regeneration inArabidopsis. With this approach, we identified and confirmed the involvement ofRECEPTOR-LIKE PROTEIN KINASE1as a previously unknown determinant of shoot regeneration. Because this gene is implicated in abscisic acid signaling, it seems that this hormone might be an important player in this developmental process.
Generation of bright isolated attosecond soft X-ray pulses driven by multicycle midinfrared lasers
Authors: Chen Ming-Chang , Mancuso Christopher , Hernández-García Carlos , Dollar Franklin , Galloway Ben , Popmintchev Dimitar , Huang Pei-Chi , Walker Barry , Plaja Luis , Jaroń-Becker Agnieszka A. , Becker Andreas , Murnane Margaret M. , Kapteyn Henry C. , Popmintchev Tenio
Published: May 2014

Significance

Attosecond pulses driven by femtosecond lasers make it possible to capture the fastest electron dynamics in molecules and materials. To date, attosecond pulses driven by widely available 800-nm lasers were limited to the extreme UV region of the spectrum, which restricted the range of materials, liquid, and molecular systems that could be explored because of the limited penetrating power. Our recent work showed that longer-wavelength midinfrared driving lasers at wavelengths from 1 to 4 µm are optimal for generating shorter-wavelength, bright, soft X-ray beams. Here we show that longer-pulse-duration midinfrared lasers are also optimal for generating shorter-pulse-duration, attosecond, soft X-rays. This is an unexpected and beautiful convergence of physics: bright, soft X-ray high harmonics naturally emerge as isolated attosecond bursts.
Quantifying the future value of cacheable food using fox squirrels (sciurus niger)
Authors: van der Merwe Marius , Brown Joel S. , Kotler Burt P.
Published: May 2014

Food caching allows foraging decisions to include both present and future food value. We developed and tested a conceptual framework for measuring animals’ perceptions of future vs. present food value. Fox squirrels (Sciurus niger) are well-known caching animals in North America. We measured giving-up densities (GUDs) of fox squirrels to test the following hypotheses: (1) all else equal, animals should prefer cacheable to non-cacheable foods, and (2) the option value of a cacheable food should change seasonally and be highest preceding lean periods. We presented squirrels with experimental food patches containing either shelled hazelnuts, hazelnuts with their shells intact (to affect cacheability) or both kinds. Our data support both hypotheses. Squirrels exploited food patches with cacheable nuts more thoroughly and left them at lower GUDs. The squirrels’ perception of the future value of hazelnuts with their shells intact was found to be 32% higher than their present value. GUDs also varied by season, fall > spring >winter > summer, likely corresponding to food availability. Season and food cacheability interacted to further determine GUDs. The difference in GUDs between cacheable and non-cacheable nuts varied similarly: fall > spring > winter > summer, likely corresponding to changing food availability, reproductive opportunities and pending energetic shortfalls.
Illusory line motion is not caused by object-differentiating mechanisms or endogenous attention
Authors: Christie John
Published: May 2014

Christie and Klein [2005. Does attention cause illusory line motion? Perception & Psychophysics, 67(6), 1032–1043] published line motion ratings consistent with illusory line motion (ILM) after peripheral endogenous cues but not central arrow cues. When attention was directed endogenously on the basis of the shape of one of two peripherally presented objects, participants reported small, but significant motion away from the attended object, and this was attributed to participant bias, or to a peripherally directed object-based attention system endogenously recruited to differentiate the peripheral shapes. By using a unique cueing method with identical peripheral markers, but still allowing them to act as cues, the findings of Christie and Klein Experiment 4 were replicated. This reduces the likelihood that object discrimination or object attention mechanisms are responsible for the reported ILM-like effects.