bluuebunny/crossref_metadata_2025 huggingface dataset:
DC‐link voltage control strategy for reducing capacitance and total harmonic distortion in single‐phase grid‐connected photovoltaic inverters
Authors: Hu Yihua , Du Yang , Xiao Weidong , Finney Stephen , Cao Wenping
Published: April 2015

High‐volume capacitance is required to buffer the power difference between the input and output ports in single‐phase grid‐connected photovoltaic inverters, which become an obstacle to high system efficiency and long device lifetime. Furthermore, total harmonic distortion becomes serious when the system runs into low power level. In this study, a comprehensive analysis is introduced for two‐stage topology with the consideration of active power, DC‐link (DCL) voltage, ripple and capacitance. This study proposed a comprehensive DCL voltage control strategy to minimise the DCL capacitance while maintaining a normal system operation. Furthermore, the proposed control strategy is flexible to be integrated with the pulse‐skipping control that significantly improves the power quality at light power conditions. Since the proposed control strategy needs to vary DCL voltage, an active protection scheme is also introduced to prevent any voltage violation across the DCL. The proposed control strategy is evaluated by both simulation and experiments, whose results confirm the system effectiveness.
A novel method for voltage support control under unbalanced grid faults and grid harmonic voltage disturbances
Authors: Dai Zhiyong , Lin Hui , Yin Hang , Qiu Yanan
Published: April 2015

As an important ancillary service for smart grid, voltage support has the capability to improve the grid condition when grid voltage unbalanced fault occurs. Several solutions, taking into account not only the root mean square voltage, but also the shape of the voltage fault, have been proposed. In particular, the control scheme proposed in this study introduces two contributions: a novel reference generator for voltage support and a new current tracking controller. Taking into account of the shape of the grid voltage, this reference generator has the capacity to increase the positive sequence fundamental voltage magnitude and decrease the negative sequence fundamental voltage magnitude, which improves the grid condition when unbalanced fault and voltage sags occur. Compared with other works, phase locked loop is eliminated in this generator which simplifies the structure of the controller. On the basis of output regulation theory, a simple‐structure current tracking controller is proposed, which has a zero steady error under arbitrary order (or their combination) grid voltage harmonic disturbance. Simulations and experiments have verified the proposed control scheme.
Resonantly loaded apertures for high‐resolution near‐field surface imaging
Authors: Malyuskin Oleksandr , Fusco Vincent
Published: April 2015

A novel type of microwave probes based on the loaded aperture geometry has been proposed and experimentally evaluated for dielectrics characterisation and high‐resolution near‐field imaging. Experimental results demonstrate the possibility of very accurate microwave spectroscopic characterisation of thin lossy dielectric samples and biological materials containing water. High‐resolution images of the subwavelength lossy dielectric strips and wet and dry leaves have been obtained with amplitude contrast around 10–20 dB and spatial resolution better than one‐tenth of a wavelength in the near‐field zone. A microwave imaging scenario for the early‐stage skin cancer identification based on the artificial dielectric model has also been explored. This model study shows that the typical resolution of an artificial malignant tumour with a characteristic size of one‐tenth of a wavelength can be discriminated with at least 6 dB amplitude and 50° phase contrast from the artificial healthy skin and with more than 3 dB contrast from a benign lesion of the same size. It has also been demonstrated that the proposed device can efficiently deliver microwave energy to very small, subwavelength, focal areas which is highly sought in the microwave hyperthermia applications.
Estimation of critical electric field of soil ionisation based on tangential electric field method
Authors: Liu Kun , Qie Xiushu , He Jianxin , Lu Gaopeng , Xia Qing
Published: April 2015

The critical electric field of soil ionisation is very important for the performance of grounding system and spatial distribution of electromagnetic field in the soil when lightning directly strikes the lightning protection system. To estimate the critical electric field in the soil, a tangential electric field method is proposed based on the electromagnetic field analysis presented in this study. With this method, the instant moment when the soil ionisation occurs is obtained by examining the tangential component of horizontal electric field. According to the maximum electric field in soil without soil ionisation for every moment, the soil critical electric field could be estimated. In addition, the critical electric fields for four different types of soil reported in the literature are estimated with the tangential electric field method, yielding satisfactory agreement.
Real-time and imaginary-time quantum hierarchal Fokker-Planck equations
Authors: Tanimura Yoshitaka
Published: April 2015

We consider a quantum mechanical system represented in phase space (referred to hereafter as “Wigner space”), coupled to a harmonic oscillator bath. We derive quantum hierarchal Fokker-Planck (QHFP) equations not only in real time but also in imaginary time, which represents an inverse temperature. This is an extension of a previous work, in which we studied a spin-boson system, to a Brownian system. It is shown that the QHFP in real time obtained from a correlated thermal equilibrium state of the total system possesses the same form as those obtained from a factorized initial state. A modified terminator for the hierarchal equations of motion is introduced to treat the non-Markovian case more efficiently. Using the imaginary-time QHFP, numerous thermodynamic quantities, including the free energy, entropy, internal energy, heat capacity, and susceptibility, can be evaluated for any potential. These equations allow us to treat non-Markovian, non-perturbative system-bath interactions at finite temperature. Through numerical integration of the real-time QHFP for a harmonic system, we obtain the equilibrium distributions, the auto-correlation function, and the first- and second-order response functions. These results are compared with analytically exact results for the same quantities. This provides a critical test of the formalism for a non-factorized thermal state and elucidates the roles of fluctuation, dissipation, non-Markovian effects, and system-bath coherence. Employing numerical solutions of the imaginary-time QHFP, we demonstrate the capability of this method to obtain thermodynamic quantities for any potential surface. It is shown that both types of QHFP equations can produce numerical results of any desired accuracy. The FORTRAN source codes that we developed, which allow for the treatment of Wigner space dynamics with any potential form (TanimuranFP15 and ImTanimuranFP15), are provided as the supplementary material.
Optical and magneto-optical studies of martensitic transformation in Ni-Mn-Ga magnetic shape memory alloys
Authors: Beran L. , Cejpek P. , Kulda M. , Antos R. , Holy V. , Veis M. , Straka L. , Heczko O.
Published: April 2015

Optical and magneto-optical properties of single crystal of Ni50.1Mn28.4Ga21.5 magnetic shape memory alloy during its transformation from martensite to austenite phase were systematically studied. Crystal orientation was approximately along {100} planes of parent cubic austenite. X-ray reciprocal mapping confirmed modulated 10 M martensite phase. Temperature depended measurements of saturation magnetization revealed the martensitic transformation at 335 K during heating. Magneto-optical spectroscopy and spectroscopic ellipsometry were measured in the sample temperature range from 297 to 373 K and photon energy range from 1.2 to 6.5 eV. Magneto-optical spectra of polar Kerr rotation as well as the spectra of ellipsometric parameter Ψ exhibited significant changes when crossing the transformation temperature. These changes were assigned to different optical properties of Ni-Mn-Ga in martensite and austenite phases due to modification of electronic structure near the Fermi energy during martensitic transformation.
Interaction transfer of silicon atoms forming Co silicide for Co/3×3R30°-Ag/Si(111) and related magnetic properties
Authors: Chang Cheng-Hsun-Tony , Fu Tsu-Yi , Tsay Jyh-Shen
Published: April 2015

Combined scanning tunneling microscopy, Auger electron spectroscopy, and surface magneto-optic Kerr effect studies were employed to study the microscopic structures and magnetic properties for ultrathin Co/3×3R30°-Ag/Si(111). As the annealing temperature increases, the upward diffusion of Si atoms and formation of Co silicides occurs at temperature above 400 K. Below 600 K, the 3×3R30°-Ag/Si(111) surface structure persists. We propose an interaction transferring mechanism of Si atoms across the 3×3R30°-Ag layer. The upward transferred Si atoms react with Co atoms to form Co silicide. The step height across the edge of the island, a separation of 0.75 nm from the analysis of the 2 × 2 structure, and the calculations of the normalized Auger signal serve as strong evidences for the formation of CoSi2 at the interface. The interaction transferring mechanism for Si atoms enhances the possibility of interactions between Co and Si atoms. The smoothness of the surface is advantage for that the easy axis of magnetization for Co/3×3R30°-Ag/Si(111) is in the surface plane. This provides a possible way of growing flat magnetic layers on silicon substrate with controllable silicide formation and shows potential applications in spintronics devices.
Biexciton formation and exciton coherent coupling in layered GaSe
Authors: Dey P. , Paul J. , Moody G. , Stevens C. E. , Glikin N. , Kovalyuk Z. D. , Kudrynskyi Z. R. , Romero A. H. , Cantarero A. , Hilton D. J. , Karaiskaj D.
Published: April 2015

Nonlinear two-dimensional Fourier transform (2DFT) and linear absorption spectroscopy are used to study the electronic structure and optical properties of excitons in the layered semiconductor GaSe. At the 1s exciton resonance, two peaks are identified in the absorption spectra, which are assigned to splitting of the exciton ground state into the triplet and singlet states. 2DFT spectra acquired for co-linear polarization of the excitation pulses feature an additional peak originating from coherent energy transfer between the singlet and triplet. At cross-linear polarization of the excitation pulses, the 2DFT spectra expose a new peak likely originating from bound biexcitons. The polarization dependent 2DFT spectra are well reproduced by simulations using the optical Bloch equations for a four level system, where many-body effects are included phenomenologically. Although biexciton effects are thought to be strong in this material, only moderate contributions from bound biexciton creation can be observed. The biexciton binding energy of ∼2 meV was estimated from the separation of the peaks in the 2DFT spectra. Temperature dependent absorption and 2DFT measurements, combined with “ab initio” theoretical calculations of the phonon spectra, indicate strong interaction with the A1′ phonon mode. Excitation density dependent 2DFT measurements reveal excitation induced dephasing and provide a lower limit for the homogeneous linewidth of the excitons in the present GaSe crystal.
Photon-counting 1.0 GHz-phase-modulation fluorometer
Authors: Mizuno T. , Nakao S. , Mizutani Y. , Iwata T.
Published: April 2015

We have constructed an improved version of a photon-counting phase-modulation fluorometer (PC-PMF) with a maximum modulation frequency of 1.0 GHz, where a phase domain measurement is conducted with a time-correlated single-photon-counting electronics. While the basic concept of the PC-PMF has been reported previously by one of the authors, little attention has been paid to its significance, other than its weak fluorescence measurement capability. Recently, we have recognized the importance of the PC-PMF and its potential for fluorescence lifetime measurements. One important aspect of the PC-PMF is that it enables us to perform high-speed measurements that exceed the frequency bandwidths of the photomultiplier tubes that are commonly used as fluorescence detectors. We describe the advantages of the PC-PMF and demonstrate its usefulness based on fundamental performance tests. In our new version of the PC-PMF, we have used a laser diode (LD) as an excitation light source rather than the light-emitting diode that was used in the primary version. We have also designed a simple and stable LD driver to modulate the device. Additionally, we have obtained a sinusoidal histogram waveform that has multiple cycles within a time span to be measured, which is indispensable for precise phase measurements. With focus on the fluorescence intensity and the resolution time, we have compared the performance of the PC-PMF with that of a conventional PMF using the analogue light detection method.
Defocusing of an ion beam propagating in background plasma due to two-stream instability
Authors: Tokluoglu Erinc , Kaganovich Igor D.
Published: April 2015

The current and charge neutralization of charged particle beams by background plasma enable ballistic beam propagation and have a wide range of applications in inertial fusion and high energy density physics. However, the beam-plasma interaction can result in the development of collective instabilities that may have deleterious effects on ballistic propagation of an ion beam. In the case of fast, light-ion beams, non-linear fields created by instabilities can lead to significant defocusing of the beam. We study an ion beam pulse propagating in a background plasma, which is subjected to two-stream instability between the beam ions and plasma electrons, using PIC code LSP. The defocusing effects of the instability on the beam can be much more pronounced in small radius beams. We show through simulations that a beamlet produced from an ion beam passed through an aperture can be used as a diagnostic tool to identify the presence of the two-stream instability and quantify its defocusing effects. The effect can be observed on the Neutralized Drift Compression Experiment-II facility by measuring the spot size of the extracted beamlet propagating through several meters of plasma.
Electron-impact vibrational excitation of cyclopropane
Authors: Čurík R. , Čársky P. , Allan M.
Published: April 2015

We report a very detailed test of the ab initio discrete momentum representation (DMR) method of calculating vibrational excitation of polyatomic molecules by electron impact, by comparison of its results with an extensive set of experimental data, covering the entire range of scattering angles from 10∘ to 180∘ and electron energies from 0.4 to 20 eV. The DMR calculations were carried out by solving the two-channel Lippmann-Schwinger equation in the momentum space, and the interaction between the scattered electron and the target molecule was described by exact static-exchange potential corrected by a density functional theory (DFT) correlation-polarization interaction that models target’s response to the field of incoming electron. The theory is found to quantitatively reproduce the measured spectra for all normal modes, even at the difficult conditions of extreme angles and at low energies, and thus provides full understanding of the excitation mechanism. It is shown that the overlap of individual vibrational bands caused by limited experimental resolution and rotational excitation must be properly taken into account for correct comparison of experiment and theory. By doing so, an apparent discrepancy between published experimental data could be reconciled. A substantial cross section is found for excitation of the non-symmetric HCH twisting mode ν4 of A1″ symmetry by the 5.5 eV A2′ resonance, surprisingly because the currently accepted selection rules predict this process to be forbidden. The DMR theory shows that the excitation is caused by an incoming electron in an f-wave of A2′ symmetry which causes excitation of the non-symmetric HCH twisting mode ν4 of the A1″ symmetry and departs in p- and f-waves of A2″ symmetry.
Self-induced gaseous plasma as high power microwave opening switch medium
Authors: Lin S. , Beeson S. , Liu C. , Dickens J. , Neuber A.
Published: April 2015

Self-induced gaseous plasma is evaluated as active opening switch medium for pulsed high power microwave radiation. The self-induced plasma switch is investigated for N2 and Ar environments under pressure conditions ranging from 25 to 700 Torr. A multi-pass TE111 resonator is used to significantly reduce the delay time inherently associated with plasma generation. The plasma forms under the pulsed excitation of a 4 MW magnetron inside the central dielectric tube of the resonator, which isolates the inner atmospheric gas from the outer vacuum environment. The path from the power source to the load is designed such that the pulse passes through the plasma twice with a 35 ns delay between these two passes. In the first pass, initial plasma density is generated, while the second affects the transition to a highly reflective state with as much as 30 dB attenuation. Experimental data revealed that virtually zero delay time may be achieved for N2 at 25 Torr. A two-dimensional fluid model was developed to study the plasma formation times for comparison with experimental data. The delay time predicted from this model agrees well with the experimental values in the lower pressure regime (error < 25%), however, due to filamentary plasma formation at higher pressures, simulated delay times may be underestimated by as much as 50%.
Effect of metamagnetism on multiferroic property in double perovskite Sm2CoMnO6
Authors: Wang Liaoyu , Zhou Weiping , Wang Dunhui , Cao Qingqi , Xu Qingyu , Du Youwei
Published: April 2015

The magnetic and multiferroic properties of a B-site ordered double perovskite Sm2CoMnO6 are investigated. The electric polarization is observed below the ferromagnetic Curie temperature of 135 K. This electric polarization of Sm2CoMnO6 can be influenced by applying a magnetic field, showing an interesting magnetoelectric effect. The origins of multiferroic properties and magnetoelectric effect are discussed.
Hybrid simulation of toroidal Alfvén eigenmode on the National Spherical Torus Experiment
Authors: Liu D. , Fu G. Y. , Crocker N. A. , Podestà M. , Breslau J. A. , Fredrickson E. D. , Kubota S.
Published: April 2015

Energetic particle modes and Alfvén eigenmodes driven by super-Alfvénic fast ions are routinely observed in neutral beam heated plasmas on the National Spherical Torus eXperiment (NSTX). These modes can significantly impact fast ion transport and thus cause fast ion redistribution or loss. Self-consistent linear simulations of Toroidal Alfvén Eigenmodes (TAEs) in NSTX plasmas have been carried out with the kinetic/magnetohydrodynamic hybrid code M3D-K using experimental plasma parameters and profiles including plasma toroidal rotation. The simulations show that unstable TAEs with n=3,4, or 5 can be excited by the fast ions from neutral beam injection. The simulated mode frequency, mode radial structure, and phase shift are consistent with measurements from a multi-channel microwave reflectometer diagnostic. A sensitivity study on plasma toroidal rotation, safety factor q profile, and initial fast ion distribution is performed. The simulations show that rotation can have a significant destabilizing effect when the rotation is comparable or larger than the experimental level. The mode growth rate is sensitive to q profile and fast ion distribution. Although mode structure and peak position depend somewhat on q profile and plasma rotation, the variation of synthetic reflectometer response is within experimental uncertainty and it is not sensitive enough to see the difference clearly.
Magnetic domain wall induced ferroelectricity in double perovskites
Authors: Zhou Hai Yang , Zhao Hong Jian , Zhang Wen Qing , Chen Xiang Ming
Published: April 2015

Recently, a magnetically induced ferroelectricity occurring at magnetic domain wall of double perovskite Lu2CoMnO6 has been reported experimentally. However, there exists a conflict whether the electric polarization is along b or c direction. Here, by first-principles calculations, we show that the magnetic domain wall (with ↑↑↓↓ spin configuration) can lead to the ferroelectric displacements of R3+, Ni2+, Mn4+, and O2− ions in double perovskites R2NiMnO6 (R = rare earth ion) via exchange striction. The resulted electric polarization is along b direction with the P21 symmetry. We further reveal the origin of the ferroelectric displacements as that: (1) on a structural point of view, such displacements make the two out-of-plane Ni-O-Mn bond angles as well as Ni-Mn distance unequal, and (2) on an energy point of view, such displacements weaken the out-of-plane Ni-Mn super-exchange interaction obviously. Finally, our calculations show that such a kind of ferroelectric order is general in ferromagnetic double perovskites.
Route to n-type doping in SnS
Authors: Xiao Zewen , Ran Fan-Yong , Hosono Hideo , Kamiya Toshio
Published: April 2015

SnS is intrinsically a p-type semiconductor, and much effort has been made to attain n-type conduction. In this letter, we performed density functional theory calculations to seek an effective doping route for n-type SnS. It was found that aliovalent doping of SnS by Sb or Bi is not effective due to their high formation enthalpies; while the isovalent Pb-substitution of the Sn sites largely reduces formation enthalpies of Sn and Pb interstitials, which explain the recently demonstrated n-type conduction in the Sn1−xPbxS films fabricated under low H2S pressures.
Revised calibration of the Sm:SrB4O7 pressure sensor using the Sm-doped yttrium-aluminum garnet primary pressure scale
Authors: Rashchenko Sergey V. , Kurnosov Alexander , Dubrovinsky Leonid , Litasov Konstantin D.
Published: April 2015

The pressure-induced shift of Sm:SrB4O7 fluorescence was calibrated in a quasi-hydrostatic helium medium up to 60 GPa using the recent Sm-doped yttrium-aluminum garnet primary pressure scale as a reference. The resulting calibration can be written as P = −2836/14.3 [(1 + Δλ/685.51)−14.3 − 1]. Previous calibrations based on the internally inconsistent primary scales are revised, and, after appropriate correction, found to agree with the proposed one. The calibration extended to 120 GPa was also performed using corrected previous data and can be written as P = 4.20 Δλ (1 + 0.020 Δλ)/(1 + 0.036 Δλ).
The role of shear in the transition from continuous shear thickening to discontinuous shear thickening
Authors: Jiang Weifeng , Xuan Shouhu , Gong Xinglong
Published: April 2015

Dense non-Brownian suspension has rich rheology and is hard to understand, especially for distinguishing continuous shear thickening (CST) from discontinuous shear thickening (DST). By studying the shear stress dependent rheology of a well-known DST suspension of cornstarch in water, we find that the transition from CST to DST could occur not only by increasing the volume fraction ϕ but also by increasing the shear stress σ. For the recovery process of jammed suspension, we observe that the shear activates the time-dependent nature of particle rearrangement. DST can then be interpreted as the consequence of shear-induced jamming. Based on the test data, we plot the schematic phase diagram in the ϕ-σ plane and find out that ϕ and σ perform almost the same effect on flow-state transition.
Modulatable magnetically mediated thermoacoustic imaging with magnetic nanoparticles
Authors: Feng Xiaohua , Gao Fei , Zheng Yuanjin
Published: April 2015

Modulatable magnetically mediated thermoacoustic imaging with magnetic nanoparticles is reported here. Under a pulsed radio frequency magnetic field, magnetic nanoparticles absorb energy strongly from the field and then emanate ultrasound signal thermoelastically. The energy absorption and, consequently, generated thermoacoustic signal strength depend sensitively on the magnetization state of magnetic nanoparticles, which can therefore be modulated effectively by a “bias” magnetic field. The magnetic modulation is demonstrated with a static magnet and modulated phantom imaging results are presented. This method offers an alternative modality for mapping magnetic nanoparticles and its unique modulation capability is demonstrated to be useful for contrast enhancement.
The political economy of mortgage securitization and the neoliberalization of housing policy in Canada
Authors: Walks Alan , Clifford Brian
Published: April 2015

The Canadian case represents a distinct variety of financialization under capitalism, one conditioned by the structure of its mortgage markets and the dominant role played by the state in the process of mortgage securitization. Securitization has been a key component of the neoliberalization of housing policy, with new state roles in the insuring, directing and funding of residential mortgage-backed securities both undergirding and justifying the federal shift from the provision of social rental housing toward supporting a rental market increasingly characterized by private sector individualunit landlord-investors. It was primarily the state's control over, and utilization of, the securitization process that maintained the solvency of the financial system in the face of the global financial crisis. However the resulting rapid uptake of liabilities on behalf of both the state and households brought forth new contradictions, necessitating new policy experimentation and reregulation, to which securitization was once again directed and which now articulate the political economy of housing in the country.
Measure for measure? Commensuration, commodification, and metrology in emissions markets and beyond
Authors: Cooper Mark H
Published: April 2015

The proliferation of markets and market-based policy instruments in environmental governance is premised on the establishment of metrological regimes and the practices of measurement, commensuration, and commodification that underlie these regimes. This paper develops the concept of metrology and examines its role in the function and dysfunction of emissions trading markets. The concept invites us to question the social, political, and scientific conditions under which agreements about measurement and commensuration do or do not occur, and the consequences or effects of particular metrological systems. The paper provides three examples of how measurement, commensuration, and commodification have framed the design and function of emissions markets in order to illustrate the effects of particular metrologies on market rule. Contrary to claims that measurement serves as a means to ‘cool’ political disputes, this paper argues that because markets inevitably have distributional effects, the metrological systems which frame market design are frequently a site of focused political contestation. Seeing measurement and commensuration as inherently political can also provide insight into ongoing disagreements about the appropriate metrics and responsibilities for mitigating climate change and the form and function of markets more generally.
An assessment of the utility of LiDAR data in extracting base-year floorspace and a comparison with the census-based approach
Authors: Shiravi Sajad , Zhong Ming , Beykaei Seyed Ahad , Hunt John Douglas , Abraham John E
Published: April 2015

A literature review indicates that most integrated land-use transport models (ILUTMs) estimate base-year floorspace data according to limited population and employment data provided by the census and, in general, the accuracy is unknown. This paper assesses the utility of airborne Light Detection And Ranging (LiDAR) technology as a valuable tool for extracting base-year floorspace using the following three datasets: a geographic vector building footprint layer, a LiDAR dataset, and field survey data for the south side of the City of Fredericton, Canada. It is found through a statistical comparison with the results from the field survey that LiDAR data can be used to extract buildings and estimate floorspace with a good degree of accuracy. Further, two base-year floorspace estimation methods, one based on the LiDAR data and the other on census data, are compared. In general, our results show that the traditional census-based approach may not be reliable for estimating base-year floorspace. Using the extracted floorspace from the LiDAR data as the basis, for residential floorspace estimation the average absolute percentage errors (APE) of the census-based approach is 16% and the 95th percentile APE is 34%. On the other hand, for employment floorspace estimation, the accuracy of the census-based approach is even lower, with average errors of 50% or higher and the 95th percentile APEs as high as 163% up to 400% for several land-use categories. All the above statistics indicate that the traditional census-based approach is unreliable and inaccurate for modelers and planners to prepare their base-year floorspace, and therefore suggest a better way be explored. Study results clearly show the utility of LiDAR data and imply that it can be used as a powerful add-on for ILUTMs in general.
Development, implementation and evaluation of an interprofessional graduate program for nursing–paramedicine double-degree graduates
Authors: Considine Julie , Walker Tony , Berry Debra
Published: April 2015

Over the past decade, several Australian universities have offered a double degree in nursing and paramedicine. Mainstream employment models that facilitate integrated graduate practice in both nursing and paramedicine are currently lacking. The aim of the present study was to detail the development of the Interprofessional Graduate Program (IPG), the industrial and professional issues that required solutions, outcomes from the first pilot IPG group and future directions. The IPG was an 18-month program during which participants rotated between graduate nursing experience in emergency nursing at Northern Health, Melbourne, Australia and graduate paramedic experience with Ambulance Victoria. The first IPG with 10 participants ran from January 2011 to August 2012. A survey completed by nine of the 10 participants in March 2014 showed that all nine participants nominated Ambulance Victoria as their main employer and five participants were working casual shifts in nursing. Alternative graduate programs that span two health disciplines are feasible but hampered by rigid industrial relations structures and professional ideologies. Despite a ‘purpose built’ graduate program that spanned two disciplines, traditional organisational structures still hamper double-degree graduates using all of skills to full capacity, and force the selection of one dominant profession.

What is known about the topic?
There are no employment models that facilitate integrated graduate practice in both nursing and paramedicine. The lack of innovative employment models for double-degree graduates means that current graduate program structures force double-degree graduates to practice in one discipline, negating the intent of a double degree.

What does this paper add?
This is the first time that a graduate program specifically designed for double-degree graduates with qualifications as Registered Nurses and Paramedics has been developed, delivered and evaluated. This paper confirms that graduate programs spanning two health disciplines are feasible.

What are the implications for practitioners?
Even with a graduate program specifically designed to span nursing and paramedicine, traditional organisational structures still hamper double-degree graduates using all their skills to full capacity, and force the selection of one dominant profession.
Hypoxia limits mouse follicle growth in vitro
Authors: Connolly J. M. , Kane M. T. , Quinlan L. R. , Dockery P. , Hynes A. C.
Published: April 2015

Ovarian follicle culture is useful for elucidation of factors involved in the regulation of follicular function. We examined the effects of gas phase oxygen concentration, an oil overlay, serum type and medium supplementation with FSH, insulin–transferrin–selenium (ITS) and l-ascorbic acid on cultured preantral mouse follicle growth in a spherical, non-attached follicle culture system. Follicle growth in 5% oxygen was significantly (P < 0.01) inferior to growth in 20% oxygen in terms of follicle diameter. This was likely due to hypoxia, as evidenced by significantly (P < 0.05) increased follicle secretion of vascular endothelial growth factor (VEGF), a marker of cell hypoxia. Follicular growth was not (P > 0.05) affected by an oil overlay, ITS supplementation or serum type. Culture in medium with 5% mouse serum, 1 IU mL–1 FSH, 25 μg mL–1 l-ascorbic acid and 20% oxygen without an oil overlay supported the growth of follicles to a maximum diameter of 380 μm in 6 days. Compared with mature preovulatory mouse follicles in vivo that often have diameters >500 μm within the same time frame, in vitro-grown follicles clearly exhibit limited growth. Thus, adequate oxygenation is an essential factor in the process of optimising follicle growth.
Building Rothermel fire behaviour fuel models by genetic algorithm optimisation
Authors: Ascoli Davide , Vacchiano Giorgio , Motta Renzo , Bovio Giovanni
Published: April 2015

A method to build and calibrate custom fuel models was developed by linking genetic algorithms (GA) to the Rothermel fire spread model. GA randomly generates solutions of fuel model parameters to form an initial population. Solutions are validated against observations of fire rate of spread via a goodness-of-fit metric. The population is selected for its best members, crossed over and mutated within a range of model parameter values, until a satisfactory fitness is reached. We showed that GA improved the performance of the Rothermel model in three published custom fuel models for litter, grass and shrub fuels (root mean square error decreased by 39, 19 and 26%). We applied GA to calibrate a mixed grass–shrub fuel model, using fuel and fire behaviour data from fire experiments in dry heathlands of Southern Europe. The new model had significantly lower prediction error against a validation dataset than either standard or custom fuel models built using average values of inventoried fuels, and predictions of the Fuel Characteristics Classification System. GA proved a useful tool to calibrate fuel models and improve Rothermel model predictions. GA allows exploration of a continuous space of fuel parameters, making fuel model calibration computational effective and easily reproducible, and does not require fuel sampling. We suggest GA as a viable method to calibrate custom fuel models in fire modelling systems based on the Rothermel model.
Activation of cyclic electron flow by hydrogen peroxide in vivo
Authors: Strand Deserah D. , Livingston Aaron K. , Satoh-Cruz Mio , Froehlich John E. , Maurino Veronica G. , Kramer David M.
Published: April 2015

Significance

Cyclic electron flow around photosystem I (CEF) is critical for balancing the energy budget of photosynthesis, but its regulation is not well understood. Our results provide evidence that hydrogen peroxide, which is produced as a result of imbalances in chloroplast redox state, acts as a signaling agent to activate CEF in higher plants in vivo.
Ab initio study of hot electrons in GaAs
Authors: Bernardi Marco , Vigil-Fowler Derek , Ong Chin Shen , Neaton Jeffrey B. , Louie Steven G.
Published: April 2015

Significance

How does an excited electron lose its energy? This problem is central in fields ranging from condensed matter physics to electrical engineering and chemistry. The cooling of hot electrons in gallium arsenide (GaAs) is the critical process underlying the operation of exciting electronic and optoelectronic devices, but the nature of this cooling is controversial. Here, we present calculations showing that hot electrons in GaAs lose energy chiefly by emitting lattice vibrations. We find a dominant role of acoustic vibrations, challenging the common notion that optical vibrations dominate excited electron energy loss. Our computational approach shines light on microscopic processes that are hard to capture with both experiments and semi-empirical calculations and opens new avenues to compute excited electron dynamics.
Stat1 stimulates cap-independent mRNA translation to inhibit cell proliferation and promote survival in response to antitumor drugs
Authors: Wang Shuo , Patsis Christos , Koromilas Antonis E.
Published: April 2015

Significance

Stat1 functions as a tumor suppressor by inhibiting cell proliferation and mediating antitumor immune responses. Thus, Stat1 is thought to be a suitable target for the implementation of effective antitumor therapies. However, recent findings have shown that Stat1 can mediate resistance to antitumor drugs through mechanisms that are not well understood. Herein, we demonstrate the ability of Stat1 to induce phosphoinositide 3-kinase γ (PI3Kγ) signaling and inhibit general protein synthesis, which results in the translation of select mRNAs encoding for proteins that inhibit cell proliferation or render cells increasingly resistant to antitumor drugs. Our work may result in the design of therapies that disarm the prosurvival function of Stat1 in tumors without compromising its ability to mount an effective antitumor immune response.
Maternal transmission, sex ratio distortion, and mitochondria
Authors: Perlman Steve J. , Hodson Christina N. , Hamilton Phineas T. , Opit George P. , Gowen Brent E.
Published: April 2015

In virtually all multicellular eukaryotes, mitochondria are transmitted exclusively through one parent, usually the mother. In this short review, we discuss some of the major consequences of uniparental transmission of mitochondria, including deleterious effects in males and selection for increased transmission through females. Many of these consequences, particularly sex ratio distortion, have well-studied parallels in other maternally transmitted genetic elements, such as bacterial endosymbionts of arthropods. We also discuss the consequences of linkage between mitochondria and other maternally transmitted genetic elements, including the role of cytonuclear incompatibilities in maintaining polymorphism. Finally, as a case study, we discuss a recently discovered maternally transmitted sex ratio distortion in an insect that is associated with extraordinarily divergent mitochondria.
Inhibition of TLR2 signaling by small molecule inhibitors targeting a pocket within the TLR2 TIR domain
Authors: Mistry Pragnesh , Laird Michelle H. W. , Schwarz Ryan S. , Greene Shannon , Dyson Tristan , Snyder Greg A. , Xiao Tsan Sam , Chauhan Jay , Fletcher Steven , Toshchakov Vladimir Y. , MacKerell Alexander D. , Vogel Stefanie N.
Published: April 2015

Significance

Excess Toll-like receptor 2 (TLR2) signaling has been implicated in numerous inflammatory diseases, yet there is no TLR2 inhibitor licensed for human use. Using computer-aided drug design (CADD), we identified a compound, C16H15NO4(C29), and a derivative,ortho-vanillin, that inhibit TLR2 signaling in vitro and in vivo. Our findings also revealed unexpected differences between TLR2/1 and TLR2/6 signaling in mice vs. humans. Importantly, our data provide proof of principle that the CADD-targeted BB loop pocket residues are critical for TLR2 signaling and may be targeted therapeutically.
Nanoparticle self-assembly at the interface of liquid crystal droplets
Authors: Rahimi Mohammad , Roberts Tyler F. , Armas-Pérez Julio C. , Wang Xiaoguang , Bukusoglu Emre , Abbott Nicholas L. , de Pablo Juan J.
Published: April 2015

Significance

Controlled assembly of nanoparticles at liquid crystal interfaces could lead to easily manufacturable building blocks for assembly of materials with tunable mechanical, optical, and electronic properties. Past work has examined nanoparticle assembly at planar liquid crystal interfaces. In this work, we show that nanoparticle assembly on curved interfaces is drastically different and arises for conditions under which assembly is too weak to occur on planar interfaces. We also demonstrate that liquid crystal-mediated nanoparticle interactions are strong, are remarkably sensitive to surface anchoring, and lead to hexagonal arrangements that do not arise in bulk systems. All of these elements form the basis for a highly tunable, predictable, and versatile platform for hierarchical materials assembly.
Revealing the climate of snowball Earth from Δ
17
O systematics of hydrothermal rocks
Authors: Herwartz Daniel , Pack Andreas , Krylov Dmitri , Xiao Yilin , Muehlenbachs Karlis , Sengupta Sukanya , Di Rocco Tommaso
Published: April 2015

Significance

The snowball Earth hypothesis predicts that the entire Earth was covered with ice. Snowball Earth events were suggested to have occurred several times during the Precambrian. Classic paleo-thermometers (e.g.,
18
O/
16
O in marine carbonates) are not available from snowball Earth episodes, and only a few reconstructions of
18
O/
16
O in ancient meteoric water exist. Here we present a novel approach to reconstruct the
18
O/
16
O composition of ancient meteoric waters using the triple oxygen isotopic composition (
17
O/
16
O and
18
O/
16
O) of hydrothermally altered rocks. The inferred
18
O/
16
O for waters that precipitated at (sub)tropical paleo-latitudes on a Paleoproterozoic (∼2.4 gigayears ago) snowball Earth are extremely low. Today, similar compositions are observed only in central Antarctica.
Cryo-EM structure of the tetracycline resistance protein TetM in complex with a translating ribosome at 3.9-Å resolution
Authors: Arenz Stefan , Nguyen Fabian , Beckmann Roland , Wilson Daniel N.
Published: April 2015

Significance

The ribosome, the protein-synthesizing machine in the cell, is a major target for antibiotics, such as tetracyclines. The widespread usage of tetracyclines has led to an increase in tetracycline resistance amongst medically relevant pathogenic bacteria, limiting their utility. Many bacteria obtain tetracycline resistance via ribosome protection proteins, such as TetM and TetO, that bind to the ribosome and chase tetracycline from its binding site. We have determined a structure of TetM bound to a translating ribosome at 3.9 Å, providing molecular insight into how TetM interacts with the ribosome to dislodge the drug from its binding site.
Digital diffraction analysis enables low-cost molecular diagnostics on a smartphone
Authors: Im Hyungsoon , Castro Cesar M. , Shao Huilin , Liong Monty , Song Jun , Pathania Divya , Fexon Lioubov , Min Changwook , Avila-Wallace Maria , Zurkiya Omar , Rho Junsung , Magaoay Brady , Tambouret Rosemary H. , Pivovarov Misha , Weissleder Ralph , Lee Hakho
Published: April 2015

Significance

Smartphones and wearable electronics have advanced tremendously over the last several years but fall short of allowing their use for molecular diagnostics. We herein report a generic approach to enable molecular diagnostics on smartphones. The method utilizes molecular-specific microbeads to generate unique diffraction patterns of “blurry beads” which can be recorded and deconvoluted by digital processing. We applied the system to resolve individual precancerous and cancerous cells as well as to detect cancer-associated DNA targets. Because the system is compact, easy to operate, and readily integrated with the standard, portable smartphone, this approach could enable medical diagnostics in geographically and/or socioeconomically limited settings with pathology bottlenecks.
Neuronal medium that supports basic synaptic functions and activity of human neurons in vitro
Authors: Bardy Cedric , van den Hurk Mark , Eames Tameji , Marchand Cynthia , Hernandez Ruben V. , Kellogg Mariko , Gorris Mark , Galet Ben , Palomares Vanessa , Brown Joshua , Bang Anne G. , Mertens Jerome , Böhnke Lena , Boyer Leah , Simon Suzanne , Gage Fred H.
Published: April 2015

Significance

Neuronal cultures are very valuable to learn about basic principles of the nervous system. In vivo, neural electrical activity is the essence of nervous system function, controlling emotion, memory, sensory modalities, and behavior. In this study, we discovered that many crucial neurophysiological properties were strongly altered in classic culture media that are widely used by the research community. To overcome this problem, we designed and tested a new tissue culture neuromedium that adequately supports in vitro neuronal activity. The improvements made in this medium reduce the gap between in vivo brain physiological conditions and neuronal models in vitro. Improving physiological conditions in vitro may lead to more successful translation from bench to clinics.
Mitofusin 2 ablation increases endoplasmic reticulum–mitochondria coupling
Authors: Filadi Riccardo , Greotti Elisa , Turacchio Gabriele , Luini Alberto , Pozzan Tullio , Pizzo Paola
Published: April 2015

Significance

The privileged interrelationship between mitochondria and the endoplasmic reticulum (ER) plays a key role in a variety of physiological functions, from lipid metabolism to Ca
2+
signalling, and its modulation influences apoptotic susceptibility, mitophagy, and cellular bioenergetics. Among the several proteins known to influence ER–mitochondria interactions, mitofusin 2 (Mfn2) has been proposed to form a physical tether. In this study, we demonstrate that Mfn2 instead works as an ER–mitochondria tethering antagonist preventing an excessive, potentially toxic, proximity between the two organelles. Cells in which Mfn2 is ablated or reduced have an increased number of ER–mitochondria close contacts, potentiated Ca
2+
transfer between the two organelles, and greater sensitivity to cell-death stimuli that implies mitochondria Ca
2+
overload toxicity.
Increased size and cellularity of advanced atherosclerotic lesions in mice with endothelial overexpression of the human TRPC3 channel
Authors: Smedlund Kathryn B. , Birnbaumer Lutz , Vazquez Guillermo
Published: April 2015

Significance

Atherosclerosis is a chronic disease of the arterial wall with a dominant inflammatory component. Endothelial cell inflammation and recruitment of circulating monocytes are critical processes during atherosclerotic lesion progression. In this manuscript, we generated a mouse model of atherosclerosis with endothelial-specific overexpression of TRPC3, a calcium permeable channel, and provide evidence indicating that augmented expression/function of TRPC3 supports, in vivo, endothelial inflammation and increased macrophage infiltration, resulting in atherosclerotic lesions of bigger size and complexity. These findings support the notion that endothelial TRPC3 channels may represent attractive targets for development of novel therapeutic strategies in the treatment of atherosclerosis.
Multifunctional bioscaffolds for 3D culture of melanoma cells reveal increased MMP activity and migration with BRAF kinase inhibition
Authors: Leight Jennifer L. , Tokuda Emi Y. , Jones Caitlin E. , Lin Austin J. , Anseth Kristi S.
Published: April 2015

Significance

Matrix metalloproteinases (MMPs) are a family of enzymes that enable cell-mediated remodeling of the local environment. Because of their ability to degrade the extracellular matrix, MMPs are an important component of the metastatic cascade. However, the effect of cancer drug treatment on MMP activity is not well-established. This study reveals that treatment with a clinically relevant BRAF protein kinase inhibitor (PLX4032) correlates with increases in melanoma MMP activity in 3D culture, which consequently leads to increased cell migration. Although PLX4032 initially causes significant tumor shrinkage, patients typically relapse due to metastatic lesions. This work may contribute to our understanding of how initially promising therapeutics ultimately lead to poor patient outcome through drug-induced effects on MMP activity and cell motility.