bluuebunny/crossref_metadata_2025 huggingface dataset:
Polyphenol-Enriched Fractions of Cyclopia intermedia Selectively Affect Lipogenesis and Lipolysis in 3T3-L1 Adipocytes
Authors: Jack Babalwa , Malherbe Christiaan , Willenburg Elize , de Beer Dalene , Huisamen Barbara , Joubert Elizabeth , Muller Christo , Louw Johan , Pheiffer Carmen
Published: September 2017

Cyclopia species are increasingly investigated as sources of phenolic compounds with potential as therapeutic agents. Recently, we demonstrated that a crude polyphenol-enriched organic fraction (CPEF) of Cyclopia intermedia, currently forming the bulk of commercial production, decreased lipid content in 3T3-L1 adipocytes and inhibited body weight gain in obese db/db mice. The aim of the present study was to determine whether a more effective product and/or one with higher specificity could be obtained by fractionation of the CPEF by purposely increasing xanthone and benzophenone levels. Fractionation of the CPEF using high performance counter-current chromatography (HPCCC) resulted in four fractions (F1–F4), predominantly containing iriflophenone-3-C-β-D-glucoside-4-O-β-D-glucoside (benzophenone: F1), hesperidin (flavanone: F2), mangiferin (xanthone: F3), and neoponcirin (flavone: F4), as quantified by high-performance liquid chromatography with diode array detection (HPLC-DAD), and confirmed by LC-DAD with mass spectrometric (MS) and tandem MS (MSE) detection. All fractions inhibited lipid accumulation in 3T3-L1 pre-adipocytes and decreased lipid content in mature 3T3-L1 adipocytes, although their effects were concentration-dependent. F1–F3 stimulated lipolysis in mature adipocytes. Treatment of mature adipocytes with F1 and F2 increased the messenger RNA expression of hormone sensitive lipase, while treatment with F1 and F4 increased uncoupling protein 3 expression. In conclusion, HPCCC resulted in fractions with different phenolic compounds and varying anti-obesity effects. The activities of fractions were lower than the CPEF; thus, fractionation did not enhance activity within a single fraction worthwhile for exploitation as a nutraceutical product, which illustrates the importance of considering synergistic effects in plant extracts.
Investigation of optical transitions in a SiGeSn/GeSn/SiGeSn single quantum well structure
Authors: Du Wei , Ghetmiri Seyed Amir , Margetis Joe , Al-Kabi Sattar , Zhou Yiyin , Liu Jifeng , Sun Greg , Soref Richard A. , Tolle John , Li Baohua , Mortazavi Mansour , Yu Shui-Qing
Published: September 2017

A SiGeSn/GeSn/SiGeSn single quantum well structure featuring type-I band alignment was comprehensively characterized. Three pump lasers with different penetration depths and photon energies were used to pinpoint the optical transition characteristics of the sample. The carrier generation, redistribution, and recombination under each pumping condition were analyzed in detail. By comparing the temperature-dependent photoluminescence spectra of the GeSn quantum well with that of SiGeSn and GeSn thin film samples possessing similar Si and Sn compositions, the optical transition mechanism was clearly identified.
Parametric modeling of wideband piezoelectric polymer sensors: Design for optoacoustic applications
Authors: Fernández Vidal A. , Ciocci Brazzano L. , Matteo C. L. , Sorichetti P. A. , González M. G.
Published: September 2017

In this work, we present a three-dimensional model for the design of wideband piezoelectric polymer sensors which includes the geometry and the properties of the transducer materials. The model uses FFT and numerical integration techniques in an explicit, semi-analytical approach. To validate the model, we made electrical and mechanical measurements on homemade sensors for optoacoustic applications. Each device was implemented using a polyvinylidene fluoride thin film piezoelectric polymer with a thickness of 25 μm. The sensors had detection areas in the range between 0.5 mm2 and 35 mm2 and were excited by acoustic pressure pulses of 5 ns (FWHM) from a source with a diameter around 10 μm. The experimental data obtained from the measurements agree well with the model results. We discuss the relative importance of the sensor design parameters for optoacoustic applications and we provide guidelines for the optimization of devices.
Representation rings of small quantum groups U¯q(sl2)
Authors: Su Dong , Yang Shilin
Published: September 2017

In this paper, we characterize the representation ring of small quantum group U¯q(sl2) by generators and relations, where q is a primitive 2p-th root of unity (p≥2). It turns out that the representation ring of U¯q(sl2) is generated by infinitely many generators subject to a family of generating relations.
Spin wave excitation in sub-micrometer thick Y3Fe5O12 films fabricated by pulsed laser deposition on garnet and silicon substrates: A comparative study
Authors: Balinskiy Michael , Ojha Shuchi , Chiang Howard , Ranjbar Mojtaba , Ross Caroline A. , Khitun Alexander
Published: September 2017

The development of yttrium iron garnet nanostructures on a silicon substrate is critically important for the integration of magnonic components with conventional electronic circuits. In this work, we present experimental data on spin wave excitation and propagation in 700 nm thick planar Y3Fe5O12 (YIG) films fabricated on gadolinium gallium garnet Gd3Ga5O12 (GGG) and silicon substrates by pulsed laser deposition. The spin wave spectroscopy measurements were accomplished using a set of micro-antennas placed directly on the film surface. The data were collected in a frequency range of 0.5–7 GHz and a bias magnetic field from 0 to 2000 Oe. We compare and analyze the spectra obtained for YIG/GGG and YIG/Si. Fitting to the Kittel formula yields the effective magnetization of the samples which is compared with the results obtained by magnetometry. Application of spin wave spectroscopy for magnetic film characterization allows us to extract valuable information on the magnetic texture. Understanding the mechanisms leading to the spin wave damping modification is the key to low-loss spin wave devices compatible with conventional silicon-based technology.
Optimal design of implants for magnetically mediated hyperthermia: A wireless power transfer approach
Authors: Lang Hans-Dieter , Sarris Costas D.
Published: September 2017

In magnetically mediated hyperthermia (MMH), an externally applied alternating magnetic field interacts with a mediator (such as a magnetic nanoparticle or an implant) inside the body to heat up the tissue in its proximity. Producing heat via induced currents in this manner is strikingly similar to wireless power transfer (WPT) for implants, where power is transferred from a transmitter outside of the body to an implanted receiver, in most cases via magnetic fields as well. Leveraging this analogy, a systematic method to design MMH implants for optimal heating efficiency is introduced, akin to the design of WPT systems for optimal power transfer efficiency. This paper provides analytical formulas for the achievable heating efficiency bounds as well as the optimal operating frequency and the implant material. Multiphysics simulations validate the approach and further demonstrate that optimization with respect to maximum heating efficiency is accompanied by minimizing heat delivery to healthy tissue. This is a property that is highly desirable when considering MMH as a key component or complementary method of cancer treatment and other applications.
Composition-driven magnetic and structural phase transitions in Bi1−xPrxFe1−xMnxO3 multiferroics
Authors: Khomchenko V. A. , Ivanov M. S. , Karpinsky D. V. , Paixão J. A.
Published: September 2017

Magnetic ferroelectrics continue to attract much attention as promising multifunctional materials. Among them, BiFeO3 is distinguished by exceptionally high transition temperatures and, thus, is considered as a prototype room-temperature multiferroic. Since its properties are known to be strongly affected by chemical substitution, recognition of the doping-related factors determining the multiferroic behavior of the material would pave the way towards designing the structures with enhanced magnetoelectric functionality. In this paper, we report on the crystal structure and magnetic and local ferroelectric properties of the Bi1−xPrxFe1−xMnxO3 (x ≤ 0.3) compounds prepared by a solid state reaction method. The polar R3c structure specific to the parent BiFeO3 has been found to be unstable with respect to doping for x ≳ 0.1. Depending on the Pr/Mn concentration, either the antipolar PbZrO3-like or nonpolar PrMnO3-type structure can be observed. It has been shown that the non-ferroelectric compounds are weak ferromagnetic with the remanent/spontaneous magnetization linearly decreasing with an increase in x. The samples containing the polar R3c phase exhibit a mixed antiferromagnetic/weak ferromagnetic behavior. The origin of the magnetic phase separation taking place in the ferroelectric phase is discussed as related to the local, doping-introduced structural heterogeneity contributing to the suppression of the cycloidal antiferromagnetic ordering characteristic of the pure BiFeO3.
Generation of banded chorus by a two-component energetic electron distribution in an inhomogeneous magnetic field
Authors: Huang H. , Wang Z. B. , Tao X. , Wang X. G.
Published: September 2017

The generation of banded chorus by a two-component energetic electron distribution in a mirror-like inhomogeneous magnetic field is investigated in this work by a 1D hybrid code DAWN. A previous study by Liu et al. [Geophys. Res. Lett. 38, L14108 (2011)] suggested that banded chorus waves can be independently generated by two energetic electron populations. In this work, we first conduct a series of simulations to confirm that the starting frequency of chorus elements is close to the frequency of maximum linear growth rate. With carefully chosen simulation parameters, we then successfully generate banded chorus with a gap near half the electron gyrofrequency. By expanding the parameter range, however, we demonstrate that the gap can be located at frequencies other than the half electron gyrofrequency. We conclude that though the previous mechanism proposed by Liu et al. [Geophys. Res. Lett. 38, L14108 (2011)] can explain the relative independence of upper band and lower band chorus, further work is needed to explain why the linear properties of energetic electrons in the magnetosphere should produce a gap at 0.5Ωe0.
Internal triaxial strain imaging of visibly opaque black rubbers with terahertz polarization spectroscopy
Authors: Moriwaki Atsuto , Okano Makoto , Watanabe Shinichi
Published: September 2017

We demonstrate the nondestructive imaging of internal triaxial strain in visibly opaque black rubbers by employing the polarization-sensitive terahertz time-domain spectroscopy (PS THz-TDS) technique. From the sample thickness and the differences in amplitude and phase between orthogonal components of the terahertz wave that passed through the sample, the degree of birefringence and the angle of the slow optic axis were determined. We were able to convert the birefringence data into the amount and orientation of the internal strain through a Monte Carlo simulation that correlates the birefringent properties of the rubber with deformation. By comparing the strain map obtained from the PS THz-TDS measurements with that obtained by conventional digital image correlation, we found that both experimental and spatial distributions of the strain are in overall good agreement, except around the clamped sample regions. The deviations result from the intrinsic difference in the obtained strain information between two experiments and it is confirmed that our method based on PS THz-TDS is suited for evaluating the spatial distribution of the internal strain in black rubbers.
Reduced clot debris size using standing waves formed via high intensity focused ultrasound
Authors: Guo Shifang , Du Xuan , Wang Xin , Lu Shukuan , Shi Aiwei , Xu Shanshan , Bouakaz Ayache , Wan Mingxi
Published: September 2017

The feasibility of utilizing high intensity focused ultrasound (HIFU) to induce thrombolysis has been demonstrated previously. However, clinical concerns still remain related to the clot debris produced via fragmentation of the original clot potentially being too large and hence occluding downstream vessels, causing hazardous emboli. This study investigates the use of standing wave fields formed via HIFU to disintegrate the thrombus while achieving a reduced clot debris size in vitro. The results showed that the average diameter of the clot debris calculated by volume percentage was smaller in the standing wave mode than in the travelling wave mode at identical ultrasound thrombolysis settings. Furthermore, the inertial cavitation dose was shown to be lower in the standing wave mode, while the estimated cavitation bubble size distribution was similar in both modes. These results show that a reduction of the clot debris size with standing waves may be attributed to the particle trapping of the acoustic potential well which contributed to particle fragmentation.
Numerical study of core formation of asymmetrically driven cone-guided targets
Authors: Sawada Hiroshi , Sakagami Hitoshi
Published: September 2017

Compression of a directly driven fast ignition cone-sphere target with a finite number of laser beams is numerically studied using a three-dimensional hydrodynamics code IMPACT-3D. The formation of a dense plasma core is simulated for 12-, 9-, 6-, and 4-beam configurations of the GEKKO XII laser. The complex 3D shapes of the cores are analyzed by elucidating synthetic 2D x-ray radiographic images in two orthogonal directions. The simulated x-ray images show significant differences in the core shape between the two viewing directions and rotation of the stagnating core axis in the top view for the axisymmetric 9- and 6-beam configurations.
Spoof surface plasmonic waveguide devices with compact length and low-loss
Authors: Han Chao , Chu Yangyang , Wang Zhaohong , Zhao Xiaodan
Published: September 2017

A spoof surface plasmon polaritons (SSPPs) waveguide structure with periodic T-grooves is proposed and investigated in this paper. Compared to the conventional plasmonic waveguide with periodic rectangular-grooves, the proposed waveguide support the guided SSPPs wave with enhanced propagation confinement. Moreover, the waveguide with T-grooves can achieve 39.4% decrease in length compared with the rectangular-grooves waveguide. The propagation properties of the SSPPs with enhanced confinement are able to improve by adjusting the shape dimensions of T-grooves. The effects of bend radius of 90° T-grooves waveguide on propagation performance are analyzed, and the good transmission characteristics of waveguides with small bend radius are verified. The experimental verifications of the T-grooves plasmonic waveguide filter and 3 dB power divider in microwave region are realized, S21-parameter of waveguide filter is very close to 0 dB from 0 GHz to 5.6 GHz. And 3 dB power divider achieves very good power equipartition from 0 GHz to 5.5 GHz.
A competitive binding between O2 and epoxy with carbon nanotubes
Authors: Tsai Hsin-Jung , Su Yu-Ying , Tseng Chao-Chi , Hsu Wen-Kuang
Published: September 2017

Simulation and observation reveal a competitive binding between O2 and epoxy with carbon nanotubes. Air absorption limits tube-polymer interacting coverage and weakens the van der Waals forces. As O2 is removed the tube-polymer strongly couples and coupling is conformed in a parallel fashion. Electron microscopy verifies tubes to be weakly bonded with polymer and band-shifts of raman arise from air pressure acting on C-C bonds.
Refractory titanium nitride two-dimensional structures with extremely narrow surface lattice resonances at telecommunication wavelengths
Authors: Zakomirnyi Vadim I. , Rasskazov Ilia L. , Gerasimov Valeriy S. , Ershov Alexander E. , Polyutov Sergey P. , Karpov Sergei V.
Published: September 2017

Regular arrays of plasmonic nanoparticles have brought significant attention over the last decade due to their ability to support localized surface plasmons (LSPs) and exhibit diffractive grating behavior simultaneously. For a specific set of parameters (i.e., period, particle shape, size, and material), it is possible to generate super-narrow surface lattice resonances (SLRs) that are caused by interference of the LSP and the grating Rayleigh anomaly. In this letter, we propose plasmonic structures based on regular 2D arrays of TiN nanodisks to generate high-Q SLRs in an important telecommunication range, which is quite difficult to achieve with conventional plasmonic materials. The position of the SLR peak can be tailored within the whole telecommunication bandwidth (from ≈ 1.26 μm to ≈ 1.62 μm) by varying the lattice period, while the Q-factor is controlled by changing nanodisk sizes. We show that the Q-factor of SLRs can reach a value of 2 × 103, which is the highest reported Q-factor for SLRs at telecommunication wavelengths so far. Tunability of optical properties, refractory behavior, and low-cost fabrication of TiN nanoparticles paves the way for manufacturing cheap nanostructures with extremely stable and adjustable electromagnetic response at telecommunication wavelengths for a large number of applications.
Stability of synchrony against local intermittent fluctuations in tree-like power grids
Authors: Auer Sabine , Hellmann Frank , Krause Marie , Kurths Jürgen
Published: September 2017

90% of all Renewable Energy Power in Germany is installed in tree-like distribution grids. Intermittent power fluctuations from such sources introduce new dynamics into the lower grid layers. At the same time, distributed resources will have to contribute to stabilize the grid against these fluctuations in the future. In this paper, we model a system of distributed resources as oscillators on a tree-like, lossy power grid and its ability to withstand desynchronization from localized intermittent renewable infeed. We find a remarkable interplay of the network structure and the position of the node at which the fluctuations are fed in. An important precondition for our findings is the presence of losses in distribution grids. Then, the most network central node splits the network into branches with different influence on network stability. Troublemakers, i.e., nodes at which fluctuations are especially exciting the grid, tend to be downstream branches with high net power outflow. For low coupling strength, we also find branches of nodes vulnerable to fluctuations anywhere in the network. These network regions can be predicted at high confidence using an eigenvector based network measure taking the turbulent nature of perturbations into account. While we focus here on tree-like networks, the observed effects also appear, albeit less pronounced, for weakly meshed grids. On the other hand, the observed effects disappear for lossless power grids often studied in the complex system literature.
Detection of guided-wave plasmon polariton modes in a high-index dielectric MIM structure
Authors: Owen Rachel C. , Murphy Kodiak S. , Hoke Kyle G. , Morgan Trevor J. , Johnson Brad L. , Leger Janelle M.
Published: September 2017

Surface plasmon polaritons (SPPs) are surface charge density oscillations localized to a metal-dielectric interface. In addition to being considered as promising candidates for a variety of applications, structures that support SPPs, including metal-insulator-metal (MIM) multilayers, are of fundamental interest because of the variety of collective plasmonic modes they support. Previously, a particular class of “forbidden” plasmon polariton modes (PPMs) was proposed that includes plasmon polariton modes confined to a region of dispersion space not typically accessible to surface-constructed collective excitations. Specifically, for these modes, known as Guided Wave PPMs (GW-PPMs), due to the dielectric asymmetry of the central layer, the solution to the wave equation in the center insulator layer is oscillatory while remaining surface bound both to the supporting substrate and the exposed surface. These modes are supported by a simple physical structure that results from a minor symmetry modification of the traditional MIM structure, specifically the use of a central insulator layer with a higher refractive index than the supporting substrate. However, they display fundamental properties that are distinctly different from those of standard SPPs and from recently reported hybrid plasmonic modes. While GW-PPMs have been explored theoretically, they have not yet been realized experimentally. In this article, we present the first experimental demonstration of GW-PPMs. Specifically, we excite and detect GW-PPMs at visible frequencies and match model predictions to experimental results with remarkable accuracy using minimal parameter fitting. In addition to the experimental detection, we calculate and report on other interesting and relevant features of the detected modes, including the associated electric field profiles, confinement values, and propagation lengths, and discuss in terms of the applications-relevance of GW-PPMs.
Microscopic description of irreversibility in quantum Lorentz gas by complex spectral analysis of the Liouvillian outside the Hilbert space
Authors: Petrosky T. , Hashimoto K. , Kanki K. , Tanaka S.
Published: September 2017

Irreversible process of a weakly coupled one-dimensional quantum perfect Lorentz gas is studied on the basis of the fundamental laws of physics in terms of the complex spectral analysis associated with the resonance state of the Liouvillian. Without any phenomenological operations, such as a coarse-graining of space-time or a truncation of the higher order correlation, we obtained irreversible processes on a purely dynamical basis in all space and time scale including the microscopic atomic interaction range that is much smaller than the mean-free-length. The list of development of the complex spectral analysis of the Hamiltonian (instead of the Liouvillian) in quantum optical systems and in quantum nano-devices is also presented.
Electromagnetic diagnostic system for the Keda Torus eXperiment
Authors: Tu Cui , Liu Adi , Li Zichao , Tan Mingsheng , Luo Bing , You Wei , Li Chenguang , Bai Wei , Fu Chenshuo , Huang Fangcheng , Xiao Bingjia , Shen Biao , Shi Tonghui , Chen Dalong , Mao Wenzhe , Li Hong , Xie Jinglin , Lan Tao , Ding Weixing , Xiao Chijin , Liu Wandong
Published: September 2017

A system for electromagnetic measurements was designed and installed on the Keda Torus eXperiment (KTX) reversed field pinch device last year. Although the unique double-C structure of the KTX, which allows the machine to be opened easily without disassembling the poloidal field windings, makes the convenient replacement and modification of the internal inductive coils possible, it can present difficulties in the design of flux coils and magnetic probes at the two vertical gaps. Moreover, the KTX has a composite shell consisting of a 6 mm stainless steel vacuum chamber and a 1.5 mm copper shell, which results in limited space for the installation of saddle sensors. Therefore, the double-C structure and composite shell should be considered, especially during the design and installation of the electromagnetic diagnostic system (EDS). The inner surface of the vacuum vessel includes two types of probes. One type is for the measurement of the global plasma parameters, and the other type is for studying the local behavior of the plasma and operating the new saddle coils. In addition, the probes on the outer surface of the composite shell are used for measurements of eddy currents. Finally, saddle sensors for radial field measurements for feedback control were installed between the conducting shell and the vacuum vessel. The entire system includes approximately 1100 magnetic probes, 14 flux coils, 4×26×2 saddle sensors, and 16 Rogowski coils. Considering the large number of probes and limited space available in the vacuum vessel, the miniaturization of the probes and optimization of the probe distribution are necessary. In addition, accurate calibration and careful mounting of the probes are also required. The frequency response of the designed magnetic probes is up to 200 kHz, and the resolution is 1 G. The EDS, being spherical and of high precision, is one of the most basic and effective diagnostic tools of the KTX and meets the demands imposed by requirements on basic machine operating information and future studies.
A distributed parameter model of transmission line transformer for high voltage nanosecond pulse generation
Authors: Li Jiangtao , Zhao Zheng , Li Longjie , He Jiaxin , Li Chenjie , Wang Yifeng , Su Can
Published: September 2017

A transmission line transformer has potential advantages for nanosecond pulse generation including excellent frequency response and no leakage inductance. The wave propagation process in a secondary mode line is indispensable due to an obvious inside transient electromagnetic transition in this scenario. The equivalent model of the transmission line transformer is crucial for predicting the output waveform and evaluating the effects of magnetic cores on output performance. However, traditional lumped parameter models are not sufficient for nanosecond pulse generation due to the natural neglect of wave propagations in secondary mode lines based on a lumped parameter assumption. In this paper, a distributed parameter model of transmission line transformer was established to investigate wave propagation in the secondary mode line and its influential factors through theoretical analysis and experimental verification. The wave propagation discontinuity in the secondary mode line induced by magnetic cores is emphasized. Characteristics of the magnetic core under a nanosecond pulse were obtained by experiments. Distribution and formation of the secondary mode current were determined for revealing essential wave propagation processes in secondary mode lines. The output waveform and efficiency were found to be affected dramatically by wave propagation discontinuity in secondary mode lines induced by magnetic cores. The proposed distributed parameter model was proved more suitable for nanosecond pulse generation in aspects of secondary mode current, output efficiency, and output waveform. In depth, comprehension of underlying mechanisms and a broader view of the working principle of the transmission line transformer for nanosecond pulse generation can be obtained through this research.
A high-power synthesized ultrawideband radiation source
Authors: Efremov A. M. , Koshelev V. I. , Plisko V. V. , Sevostyanov E. A.
Published: September 2017

A high-power ultrawideband radiation source has been developed which is capable of synthesizing electromagnetic pulses with different frequency bands in free space. To this end, a new circuit design comprising a four-channel former of bipolar pulses of durations 2 and 3 ns has been elaborated and conditions for the stable operation of gas gaps of independent channels without external control pulses have been determined. Each element of the 2 × 2 array of combined antennas is driven from an individual channel of the pulse former. Antennas excited by pulses of the same duration are arranged diagonally. Two radiation synthesis modes have been examined: one aimed to attain ultimate field strength and the other aimed to attain an ultimate width of the radiation spectrum. The modes were changed by changing the time delay between the 2-ns and 3-ns pulses. For the first mode, radiation pulses with a frequency band of 0.2–0.8 GHz and an effective potential of 500 kV have been obtained. The synthesized radiation pulses produced in the second mode had an extended frequency band (0.1–1 GHz) and an effective potential of 220 kV. The pulse repetition frequency was 100 Hz.
Dropping the hammer: Examining impact ignition and combustion using pre-stressed aluminum powder
Authors: Hill Kevin J. , Warzywoda Juliusz , Pantoya Michelle L. , Levitas Valery I.
Published: September 2017

Pre-stressing aluminum (Al) particles by annealing and quenching Al powder alters particle mechanical properties and has also been linked to an increase in particle reactivity. Specifically, energy propagation in composites consisting of aluminum mixed with copper oxide (Al + CuO) exhibits a 24% increase in flame speed when using pre-stressed aluminum (PS Al) compared to Al of the same particle size. However, no data exist for the reactivity of PS Al powders under impact loading. In this study, a drop weight impact tester with pressure cell was designed and built to examine impact ignition sensitivity and combustion of PS Al when mixed with CuO. Both micron and nanometer scale powders (i.e., μAl and nAl, respectively) were pre-stressed, then combined with CuO and analyzed. Three types of ignition and combustion events were identified: ignition with complete combustion, ignition with incomplete combustion, and no ignition or combustion. The PS nAl + CuO demonstrated a lower impact ignition energy threshold for complete combustion, differing from nAl + CuO samples by more than 3.5 J/mg. The PS nAl + CuO also demonstrated significantly more complete combustion as evidenced by pressure history data during ignition and combustion. Additional material characterization provides insight on hot spot formation in the incomplete combustion samples. The most probable reasons for higher impact-induced reactivity of pre-stressed particles include (a) delayed but more intense fracture of the pre-stressed alumina shell due to release of energy of internal stresses during fracture and (b) detachment of the shell from the core during impact due to high tensile stresses in the Al core leading to much more pronounced fracture of unsupported shells and easy access of oxygen to the Al core. The μAl + CuO composites did not ignite, even under pre-stressed conditions.
Flexible constrained de Finetti reductions and applications
Authors: Lancien Cécilia , Winter Andreas
Published: September 2017

De Finetti theorems show how sufficiently exchangeable states are well-approximated by convex combinations of independent identically distributed states. Recently, it was shown that in many quantum information applications, a more relaxed de Finetti reduction (i.e., only a matrix inequality between the symmetric state and one of the de Finetti forms) is enough and that it leads to more concise and elegant arguments. Here we show several uses and general flexible applicability of a constrained de Finetti reduction in quantum information theory, which was recently discovered by Duan, Severini, and Winter. In particular, we show that the technique can accommodate other symmetries commuting with the permutation action and permutation-invariant linear constraints. We then demonstrate that, in some cases, it is also fruitful with convex constraints, in particular separability in a bipartite setting. This is a constraint particularly interesting in the context of the complexity class QMA(2) of interactive quantum Merlin-Arthur games with unentangled provers, and our results relate to the soundness gap amplification of QMA(2) protocols by parallel repetition. It is also relevant for the regularization of certain entropic channel parameters. As an aside, we present an alternative way of attacking this problem, relying on an entanglement measure theory rather than the de Finetti approach. Finally, we explore an extension to infinite-dimensional systems, which usually pose inherent problems to de Finetti techniques in the quantum case.
Probing structure–function relationships in early events in photosynthesis using a chimeric photocomplex
Authors: Nagashima Kenji V. P. , Sasaki Mai , Hashimoto Kanako , Takaichi Shinichi , Nagashima Sakiko , Yu Long-Jiang , Abe Yuto , Gotou Kenta , Kawakami Tomoaki , Takenouchi Mizuki , Shibuya Yuuta , Yamaguchi Akira , Ohno Takashi , Shen Jian-Ren , Inoue Kazuhito , Madigan Michael T. , Kimura Yukihiro , Wang-Otomo Zheng-Yu
Published: September 2017

Significance

Phototrophic bacteria have provided fundamental insight into the biological mechanism of solar energy conversion. Early events in photosynthesis are carried out by the antenna apparatus for light-harvesting (LH) and the reaction center (RC) for charge separation. Here we describe a system for expressing a chimeric LH1-RC complex from two phylogenetically distant phototrophic purple bacteria: the LH1 from
Thermochromatium tepidum
and the RC from
Rhodobacter sphaeroides
. This system is exploited to definitively localize Ca
2+
within the
Tch. tepidum
LH1 complex. The hybrid photocomplexes also provide powerful new tools for probing photosynthetic energy transfer, identifying intrinsic LH1–RC interactions, monitoring altered behavior of carotenoids in a nonnative environment, and linking specific amino acid residues to the specific spectroscopic properties of different phototrophic organisms.
Consciousness and Object
Authors: Manzotti Riccardo
Published: September 2017

What is the conscious mind? What is experience? In 1968, David Armstrong asked “What is a man?” and replied that a man is “a certain sort of material object”. This book starts from his question but proceeds along a different path. The traditional mind-brain identity theory is set aside, and a mind-object identity theory is proposed in its place: to be conscious of an object is simply to be made of that object. Consciousness is physical but not neural.

This groundbreaking hypothesis is supported by recent empirical findings in both perception and neuroscience, and is herein tested against a series of objections of both conceptual and empirical nature: the traditional mind-brain identity arguments from illusion, hallucinations, dreams, and mental imagery. The theory is then compared with existing externalist approaches including disjunctivism, realism, embodied cognition, enactivism, and the extended mind. Can experience and objects be one and the same?
Phase field simulation of microstructures of Mg and Al alloys
Authors: Liu H. , Nie J. F.
Published: September 2017

The phase field method has recently emerged as a powerful and versatile tool for mesoscale simulation of microstructure evolution in Mg and Al alloys. It permits the study of the evolution of arbitrary and complex microstructures without any presumption. This article provides a review of applications of the phase-field method in Mg and Al alloys. It covers the evolution of dendrites, the equilibrium shape of some key strengthening precipitates, the effect of pre-existing precipitates and dislocations on the distribution of precipitates, and strengthening effects caused by plate-shaped precipitates that are often encountered in Mg and Al alloys. To further improve the accuracy of the phase field simulation results and to further expand the phase field method to predict mechanical properties, the phase field method needs to be integrated with other methods to establish a multi-scale approach. This integration and its application on Mg and Al alloys are also reviewed.

This paper is part of a thematic issue on Light Alloys.
Amino acid residues critical for DNA binding and inducer recognition in CbnR, a LysR-type transcriptional regulator from Cupriavidus necator NH9
Authors: Moriuchi Ryota , Takada Kaori , Takabayashi Masae , Yamamoto Yuko , Shimodaira Jun , Kuroda Naoko , Akiyama Emiko , Udagawa Mayumi , Minai Ryoichi , Fukuda Masao , Senda Toshiya , Ogawa Naoto
Published: September 2017

CbnR, a LysR-type transcriptional regulator from Cupriavidus necator NH9, activates the transcription of chlorocatechol-degradative enzymes. To activate the transcription, CbnR needs to bind not only to the cbnA promoter but also to the inducer. In this study, the transcriptional activity and DNA-binding activity of twenty-five mutants of CbnR were analyzed. Of the 17 mutants of the DNA-binding domain, 11 mutants lost their ability to activate transcription. While most mutants without transcriptional activation did not show DNA-binding activity, Asn17Ala, Gln29Ala, and Pro30Ala retained DNA-binding activity, suggesting that transcriptional activation by CbnR requires more than its binding to promoter DNA. Of the 8 mutants of the regulatory domain, 6 mutants changed their responses to the inducer, when compared with wild-type CbnR. Interestingly, Arg199Ala and Val246Ala induced constitutive expression of the cbnA promoter without the inducer, suggesting that these mutations brought about a conformational change mimicking that induced by the inducer molecule.
Inhibition of phosphatidylinositide 3-kinase impairs the benzyl isothiocyanate-induced accumulation of autophagic molecules and Nrf2 in human colon cancer cells
Authors: Liu Xiaoyang , Abe-Kanoh Naomi , Liu Yujia , Zhu Beiwei , Munemasa Shintaro , Nakamura Toshiyuki , Murata Yoshiyuki , Nakamura Yoshimasa
Published: September 2017

The regulating role of phosphatidylinositide 3-kinase (PI3K) in benzyl isothiocyanate (BITC)-induced Nrf2 activation, contributing to the inducible expression of cytoprotective genes, was investigated. BITC significantly enhanced the accumulation of Nrf2 as well as autophagic molecules in human colorectal cancer HCT-116 cells. Experiments using a PI3K-specific inhibitor suggested that PI3K plays the key role in the non-canonical Nrf2 activation by BITC.
Is it possible to diagnose benign positional paroxysmal vertigo from primary care referrals to ENT clinic?
Authors: Yuen Jason , Rashid Mamun , Webber Caitlin , Prior Matthew
Published: September 2017

Background:

Ear, nose and throat (ENT) departments commonly receive referrals of dizzy patients from primary care. It is important to distinguish complex cases of dizziness without straightforward diagnoses from simple benign positional paroxysmal vertigo (BPPV) when triaging patients such that appropriate resources are diverted to the patients who need them.

Objective:

To assess efficiency in identifying BPPV among dizzy patients from GP referral letters.

Methods:

Four doctors with different ENT experience and one senior nurse participated to identify BPPV cases from primary care referral letters before the patients’ clinic appointments. The diagnoses subsequently made in clinic were used to compare against the predictions made.

Results:

Forty-nine patients were included, of which 22% were diagnosed BPPV in clinic. The overall predictions were poor among the participants. The positive predictive values (PPV) varied between 0.23 and 0.35. Negative predictive values (NPV) varied between 0.78 and 0.86. The commonly described clinical features of BPPV also had low PPV of less than 0.3.

Conclusions:

The accuracy to identify BPPV from referral letters alone is poor among doctors of different experience. We believe this is due to insufficient details in the current letters. The introduction of referral proformas would likely aid diagnosis.
The duration of mitosis and daughter cell size are modulated by nutrients in budding yeast
Authors: Leitao Ricardo M. , Kellogg Douglas R.
Published: September 2017

The size of nearly all cells is modulated by nutrients. Thus, cells growing in poor nutrients can be nearly half the size of cells in rich nutrients. In budding yeast, cell size is thought to be controlled almost entirely by a mechanism that delays cell cycle entry until sufficient growth has occurred in G1 phase. Here, we show that most growth of a new daughter cell occurs in mitosis. When the rate of growth is slowed by poor nutrients, the duration of mitosis is increased, which suggests that cells compensate for slow growth in mitosis by increasing the duration of growth. The amount of growth required to complete mitosis is reduced in poor nutrients, leading to a large reduction in cell size. Together, these observations suggest that mechanisms that control the extent of growth in mitosis play a major role in cell size control in budding yeast.
Sequence-dependent cargo recognition by SNX-BARs mediates retromer-independent transport of CI-MPR
Authors: Simonetti Boris , Danson Chris M. , Heesom Kate J. , Cullen Peter J.
Published: September 2017

Endosomal recycling of transmembrane proteins requires sequence-dependent recognition of motifs present within their intracellular cytosolic domains. In this study, we have reexamined the role of retromer in the sequence-dependent endosome-to–trans-Golgi network (TGN) transport of the cation-independent mannose 6-phosphate receptor (CI-MPR). Although the knockdown or knockout of retromer does not perturb CI-MPR transport, the targeting of the retromer-linked sorting nexin (SNX)–Bin, Amphiphysin, and Rvs (BAR) proteins leads to a pronounced defect in CI-MPR endosome-to-TGN transport. The retromer-linked SNX-BAR proteins comprise heterodimeric combinations of SNX1 or SNX2 with SNX5 or SNX6 and serve to regulate the biogenesis of tubular endosomal sorting profiles. We establish that SNX5 and SNX6 associate with the CI-MPR through recognition of a specific WLM endosome-to-TGN sorting motif. From validating the CI-MPR dependency of SNX1/2–SNX5/6 tubular profile formation, we provide a mechanism for coupling sequence-dependent cargo recognition with the biogenesis of tubular profiles required for endosome-to-TGN transport. Therefore, the data presented in this study reappraise retromer’s role in CI-MPR transport.
Quality of biological images, reconstructed using localization microscopy data
Authors: Ruszczycki Błażej , Bernas Tytus
Published: September 2017

Motivation

Fluorescence localization microscopy is extensively used to study the details of spatial architecture of subcellular compartments. This modality relies on determination of spatial positions of fluorophores, labeling an extended biological structure, with precision exceeding the diffraction limit. Several established models describe influence of pixel size, signal-to-noise ratio and optical resolution on the localization precision. The labeling density has been also recognized as important factor affecting reconstruction fidelity of the imaged biological structure. However, quantitative data on combined influence of sampling and localization errors on the fidelity of reconstruction are scarce. It should be noted that processing localization microscopy data is similar to reconstruction of a continuous (extended) non-periodic signal from a non-uniform, noisy point samples. In two dimensions the problem may be formulated within the framework of matrix completion. However, no systematic approach has been adopted in microscopy, where images are typically rendered by representing localized molecules with Gaussian distributions (widths determined by localization precision).

Results

We analyze the process of two-dimensional reconstruction of extended biological structures as a function of the density of registered emitters, localization precision and the area occupied by the rendered localized molecule. We quantify overall reconstruction fidelity with different established image similarity measures. Furthermore, we analyze the recovered similarity measure in the frequency space for different reconstruction protocols. We compare the cut-off frequency to the limiting sampling frequency, as determined by labeling density.

Availability and implementation

The source code used in the simulations along with test images is available at https://github.com/blazi13/qbioimages.

Supplementary information

Supplementary data are available at Bioinformatics online.
Compound image segmentation of published biomedical figures
Authors: Li Pengyuan , Jiang Xiangying , Kambhamettu Chandra , Shatkay Hagit
Published: September 2017

Motivation

Images convey essential information in biomedical publications. As such, there is a growing interest within the bio-curation and the bio-databases communities, to store images within publications as evidence for biomedical processes and for experimental results. However, many of the images in biomedical publications are compound images consisting of multiple panels, where each individual panel potentially conveys a different type of information. Segmenting such images into constituent panels is an essential first step toward utilizing images.

Results

In this article, we develop a new compound image segmentation system, FigSplit, which is based on Connected Component Analysis. To overcome shortcomings typically manifested by existing methods, we develop a quality assessment step for evaluating and modifying segmentations. Two methods are proposed to re-segment the images if the initial segmentation is inaccurate. Experimental results show the effectiveness of our method compared with other methods.

Availability and implementation

The system is publicly available for use at: https://www.eecis.udel.edu/~compbio/FigSplit. The code is available upon request.

Supplementary information

Supplementary data are available online at Bioinformatics.
Genome-wide pre-miRNA discovery from few labeled examples
Authors: Yones C , Stegmayer G , Milone D H
Published: September 2017

Motivation

Although many machine learning techniques have been proposed for distinguishing miRNA hairpins from other stem-loop sequences, most of the current methods use supervised learning, which requires a very good set of positive and negative examples. Those methods have important practical limitations when they have to be applied to a real prediction task. First, there is the challenge of dealing with a scarce number of positive (well-known) pre-miRNA examples. Secondly, it is very difficult to build a good set of negative examples for representing the full spectrum of non-miRNA sequences. Thirdly, in any genome, there is a huge class imbalance (1: 10 000) that is well-known for particularly affecting supervised classifiers.

Results

To enable efficient and speedy genome-wide predictions of novel miRNAs, we present miRNAss, which is a novel method based on semi-supervised learning. It takes advantage of the information provided by the unlabeled stem-loops, thereby improving the prediction rates, even when the number of labeled examples is low and not representative of the classes. An automatic method for searching negative examples to initialize the algorithm is also proposed so as to spare the user this difficult task. MiRNAss obtained better prediction rates and shorter execution times than state-of-the-art supervised methods. It was validated with genome-wide data from three model species, with more than one million of hairpin sequences each, thereby demonstrating its applicability to a real prediction task.

Availability and implementation

An R package can be downloaded from https://cran.r-project.org/package=miRNAss. In addition, a web-demo for testing the algorithm is available at http://fich.unl.edu.ar/sinc/web-demo/mirnass. All the datasets that were used in this study and the sets of predicted pre-miRNA are available on http://sourceforge.net/projects/sourcesinc/files/mirnass.

Supplementary information

Supplementary data are available at Bioinformatics online.
Rational Growth and Almost Convexity of Higher-Dimensional Torus Bundles
Authors: Bregman Corey
Published: September 2017

Given a matrix $A\in SL(N,\mathbb{Z})$, form the semidirect product $G=\mathbb{Z}^N\rtimes_A \mathbb{Z}$ where the $\mathbb{Z}$-factor acts on $\mathbb{Z}^N$ by $A$. Such a $G$ arises naturally as the fundamental group of an $N$-dimensional torus bundle which fibers over the circle. In this article, we prove that if $A$ has distinct eigenvalues not lying on the unit circle, then there exists a finite index subgroup $H\leq G$ possessing rational growth series for some generating set. In contrast, we show that if $A$ has at least one eigenvalue not lying on the unit circle, then $G$ is not almost convex for any generating set.
Kac Polynomials for Canonical Algebras
Authors: Plamondon Pierre-Guy , Schiffmann Olivier
Published: September 2017

We prove that the number of geometrically indecomposable representations of fixed dimension vector $\mathbf{d}$ of a canonical algebra $C$ defined over a finite field $\mathbb{F}_q$ is given by a polynomial in $q$ (depending on $C$ and $\mathbf{d}$). We prove a similar result for squid algebras. Finally, we express the volume of the moduli stacks of representations of these algebras of a fixed dimension vector in terms of the corresponding Kac polynomials.