bluuebunny/crossref_metadata_2025 huggingface dataset:
The Five-hundred-meter Aperture Spherical radio Telescope project and its early science opportunities
Authors: Li Di , Nan Rendong , Pan Zhichen
Published: March 2013

The National Astronomical Observatories, Chinese Academy of Science (NAOC), has started building the largest antenna in the world. Known as FAST, the Five-hundred-meter Aperture Spherical radio Telescope is a Chinese mega-science project funded by the National Development and Reform Commission (NDRC). FAST also represents part of Chinese contribution to the international efforts to build the square kilometer array (SKA). Upon its finishing around September of 2016, FAST will be the most sensitive single-dish radio telescope in the low frequency radio bands between 70 MHz and 3 GHz. The design specifications of FAST, its expected capabilities, and its main scientific aspirations were described in an overview paper by Nan et al. (2011). In this paper, we briefly review the design and the key science goals of FAST, speculate the likely limitations at the initial stages of FAST operation, and discuss the opportunities for astronomical discoveries in the so-called early science phase.
NuSTAR observations of rotation-powered pulsars and magnetars
Authors: Kaspi V. M. , An H. , Bachetti M. , Bellm E. , Beloborodov A. M. , Boggs S. , Chakrabarty D. , Christensen F. , Craig B. , Dufour F. , Harrison F. , Gotthelf E. V. , Kitaguchi T. , Kouveliotou C. , Mori K. , Pivovaroff M. , Stern D. , Vogel J. K. , Zhang W. ,   The NuSTAR Team
Published: March 2013

NASA's NuSTAR observatory is the first focusing hard X-ray telescope. Launched in June 2012, NuSTAR is sensitive in the 3–79 keV range with unprecedented ~17″ FWHM angular resolution above 12 keV, a result of its multilayer-coated optics and 10-m focal length. With its large effective area (900 cm2 at 10 keV), NuSTAR has point-source sensitivity ~100 times better than previous hard X-ray telescopes. Here we describe NuSTAR and its planned work on rotation-powered pulsars and magnetars during its nominal 2-yr baseline mission that has just commenced.
The Square Kilometre Array
Authors: Taylor A. R.
Published: March 2013

The Square Kilometre Array (SKA) is a global project to design and construct the next-generation international radio telescope operating at metre to cm wavelengths. The SKA will be an interferometric array with a collecting area of up to one million square metres and maximum baseline of at least 3000 km, and is designed to address fundamental questions in cosmology, physics and astronomy. The key science goals range from the epoch of re-ionization, dark energy, the formation and evolution of galaxies and large-scale structure, the origin and evolution of cosmic magnetism, strong-field tests of gravity and detection of gravity waves.

The SKA project is now entering a final design for an SKA Observatory to begin to be built in the latter half of this decade that will include facilities in South Africa and Western Australia. The SKA design relies on advances in several technologies that will be prototyped over the next few years, and demonstrated for astronomical observations on SKA precursor telescopes. Scientific operations of the first 10% scale phase of the SKA is targeted for 2020.
R-Process nucleosynthesis in high entropy environment in explosion of supernova type II and neutron star formation
Authors: Baruah Rulee , Duorah Kalpana , Duorah H. L.
Published: March 2013

It is generally acknowledged that Type II supernovae result from the collapse of iron core of a massive star which, at least in some cases, produces a neutron star. At this stage, the neutrinos are produced by neutronization which speeds up as collapse continues. During collapse an outward bound shock wave forms in the matter falling onto the nearly stationary core. The conditions behind the shock at 100 to 200 km are suitable for neutrino heating. This neutrino heating blows a hot bubble above the protoneutron star and is the most important source of energy for Supernova explosion. At this stage, we try to attain the r-process (rapid neutron capture process) path responsible for the production of heavy elements beyond iron, which are otherwise not possible to be formed by fusion reactions. The most interesting evolution occurs as temperature falls from 1010 K to 109 K. At these high temperature conditions, the critical fluids after fusion reactions are forbidden and transform into the respective atoms by r-process path which on beta decaying produce the ultimate elements of the periodic chart.

Another astrophysical parameter needed for our analysis is neutron number density which we take to be greater than 1020 cm−3. With these, at different entropy environments, we assign the neutron binding energy that represents the r-process path in the chart of nuclides. Along the path, the experimental data of observed elements matches our calculated one. We find that an entropy of ~300 with Ye ≃ 0.45 can lead to a successful r-process. It produced heavy neutron-rich nuclei with A ≃ 80 – 240. Later ejecta are neutron-rich (Ye ≤ 0.5) and leaves behind a compact neutron star.
The surface and inner temperatures of magnetars
Authors: Gao Z. F. , Wang N. , Peng Q. H.
Published: March 2013

Assuming that the timescale of the magnetic field decay is approximately equal to that of the stellar cooling via neutrino emission, we obtain a one-to-one relationship between the effective surface thermal temperature and the inner temperature. The ratio of the effective neutrino luminosity to the effective X-ray luminosity decreases with decaying magnetic field.
Chandra observations of black widow pulsars
Authors: Gentile P. , McLaughlin M. , Roberts M. , Camilo F. , Hessels J. , Kerr M. , Ransom S. , Ray P. , Stairs I.
Published: March 2013

We describe the first X-ray observations of binary millisecond pulsars PSR J0023+0923, J1810+1744, J2215+5135, and J2256−1024. All are Fermi gamma-ray sources and three are ‘black-widow’ pulsars, with companions of mass < 0.1 M⊙. Data were taken using the Chandra X-Ray Observatory and covered a full binary orbit for each pulsar. PSRs J2215+5135 and J2256−1024, show significant orbital variability and X-ray flux minima coinciding with eclipses seen at radio wavelengths. This is consistent with intrabinary shock emission characteristic of black-widow pulsars. The other two pulsars, PSRs J0023+0923 and J1810+1744, do not demonstrate significant variability, but are fainter than the other two sources. Spectral fits yield power-law indices that range from 1.4 to 2.3 and blackbody temperatures in the hundreds of eV. The spectrum for PSR J2215+5135 shows a significant hard X-ray component (41% of counts are above 2 keV), which is additional evidence for the presence of intrabinary shock emission.
Constraints of the compactness of the isolated neutron stars via X-ray phase-resolved spectroscopy
Authors: Hambaryan V. , Suleimanov V. , Neuhäuser R. , Werner K.
Published: March 2013

A model with a condensed iron surface and partially ionized hydrogen-thin atmosphere allows us to fit simultaneously the observed general spectral shape and the broad absorption feature (observed at 0.3 keV) in different spin phases of the isolated neutron star RBS 1223. We constrain some physical properties of the X-ray emitting areas, i.e. the temperatures (Tpole1 ~ 105 eV, Tpole2 ~ 99 eV), magnetic field strengths (Bpole1 ≈ Bpole2 ~ 8.6 × 1013 G) at the poles, and their distribution parameters (a1 ~ 0.61, a2 ~ 0.29, indicating an absence of strong toroidal magnetic field component). In addition, we are able to place some constraints on the geometry of the emerging X-ray emission and the gravitational redshift (z ~ 0.160.03−0.01) of the isolated neutron star RBS 1223.
Tracking dispersion measure variations of timing array pulsars with the GMRT
Authors: Kumar Ujjwal , Gupta Yashwant , van Straten Willem , Osłowski Stefan , Roy Jayanta , Bhat N. D. R. , Bailes Matthew , Keith Michael J.
Published: March 2013

We present the results from nearly three years of monitoring of the variations in dispersion measure (DM) along the line-of-sight to 11 millisecond pulsars using the Giant Metrewave Radio Telescope (GMRT). These results demonstrate accuracies of single epoch DM estimates of the order of 5 × 10−4 cm−3 pc. A preliminary comparison with the Parkes Pulsar Timing Array (PPTA) data shows that the measured DM fluctuations are comparable. We show effects of DM variations due to the solar wind and solar corona and compare with the existing models.
The missing compact star of SN1987A: a solid quark star?
Authors: Liu X. W. , Liang J. D. , Xu R. X. , Han J. L. , Qiao G. J.
Published: March 2013

To investigate the missing compact star of Supernova 1987A, we analyzed the cooling and heating processes of a possible compact star based on the upper limit of observational X-ray luminosity. From the cooling process, we found that a solid quark-cluster star (SQS), having a stiffer equation of state than that of a conventional liquid quark star, has a heat capacity much smaller than a neutron star. The SQS can cool down quickly, naturally explaining the non-detection of a point source in X-ray wavelengths. On the other hand, we considered the heating processes due to magnetospheric activity and possible accretion and obtained some constraints on the parameters of a possible pulsar. Therefore, we concluded that a SQS can explain the observational limit in a confident parameter space. As a possible central compact object, the pulsar parameter constraints can be tested for SN1987A with advanced, future facilities.
Searches for continuous gravitational waves with the LIGO and Virgo detector
Authors: Riles Keith
Published: March 2013

The LIGO Scientific Collaboration and Virgo Collaboration have carried out joint searches in LIGO and Virgo data for periodic continuous gravitational waves. These analyses range from targeted searches for gravitational-wave signals from known pulsars, for which precise ephemerides from radio or X-ray observations are used in matched filters, to all-sky searches for unknown neutron stars, including stars in binary systems. Between these extremes lie directed searches for known stars of unknown spin frequency or for new unknown sources at specific locations, such as near the galactic center or in globular clusters. Recent and ongoing searches of each type will be summarized, along with prospects for future searches using data from the Advanced LIGO and Virgo detectors.
A high-energy catalogue of Galactic supernova remnants and pulsar wind nebulae
Authors: Safi-Harb Samar , Ferrand Gilles , Matheson Heather
Published: March 2013

Motivated by the wealth of past, existing, and upcoming X-ray and gamma-ray missions, we have developed the first public database of high-energy observations of all known Galactic Supernova Remnants (SNRs): http://www.physics.umanitoba.ca/snr/SNRcat. The catalogue links to, and complements, other existing related catalogues, including Dave Green's radio SNRs catalogue. We here highlight the features of the high-energy catalogue, including allowing users to filter or sort data for various purposes. The catalogue is currently targeted to Galactic SNR observations with X-ray and gamma-ray missions, and is timely with the upcoming launch of X-ray missions (including Astro-H in 2014). We are currently developing the existing database to include an up-to-date Pulsar Wind Nebulae (PWNe)-dedicated webpage, with the goal to provide a global view of PWNe and their associated neutron stars/pulsars. This extensive database will be useful to both theorists to apply their models or design numerical simulations, and to observers to plan future observations or design new instruments. We welcome input and feedback from the SNR/PWN/neutron stars community.
Observations of transients and pulsars with LOFAR international stations and the ARTEMIS backend
Authors: Serylak Maciej , Karastergiou Aris , Williams Chris , Armour Wesley , Giles Michael ,   the LOFAR Pulsar Working Group
Published: March 2013

The LOw Frequency ARray – LOFAR – is a new radio interferometer designed with emphasis on flexible digital hardware instead of mechanical solutions. The array elements, so-called stations, are located in the Netherlands and in neighbouring countries. The design of LOFAR allows independent use of its international stations, which, coupled with a dedicated backend, makes them very powerful telescopes in their own right. This backend is called the Advanced Radio Transient Event Monitor and Identification System (ARTEMIS). It is a combined software/hardware solution for both targeted observations and real-time searches for millisecond radio transients which uses Graphical Processing Unit (GPU) technology to remove interstellar dispersion and detect millisecond radio bursts from astronomical sources in real-time.
New Constraints on Preferred Frame Effects from Binary Pulsars
Authors: Shao Lijing , Wex Norbert , Kramer Michael
Published: March 2013

Preferred frame effects (PFEs) are predicted by a number of alternative gravity theories which include vector or additional tensor fields, besides the canonical metric tensor. In the framework of parametrized post-Newtonian (PPN) formalism, we investigate PFEs in the orbital dynamics of binary pulsars, characterized by the two strong-field PPN parameters, and . In the limit of a small orbital eccentricity, and contributions decouple. By utilizing recent radio timing results and optical observations of PSRs J1012+5307 and J1738+0333, we obtained the best limits of and in the strong-field regime. The constraint on also surpasses its counterpart in the weak-field regime.
Detection of Giant pulses from pulsar PSR B0950+08
Authors: Smirnova T. V.
Published: March 2013

We investigated pulse intensities of PSR B0950+08 at 112 MHz at various longitudes (phases) and detected very strong pulses exceeding the amplitude of the mean profile by more than one hundred times. The maximum peak flux density of a recorded pulse is 15240 Jy, and the energy of this pulse exceeds the mean pulse energy by a factor of 153. The analysis shows that the cumulative distribution function (CDF) of pulse intensities at the longitudes of the main pulse is described by a piece-wise power law, with a slope changing from n=−1.25 ± 0.04 to n=−1.84 ± 0.07 at I≥600 Jy. The CDF for pulses at the longitudes of the precursor has a power law with n=−1.5 ± 0.1. Detected giant pulses from this pulsar have the same signature as giant pulses of other pulsars.
Near IR Astrometry of Magnetars
Authors: Tendulkar Shriharsh P.
Published: March 2013

We report on the progress of our five-year program for astrometric monitoring of magnetars using high-resolution NIR observations using the laser guide star adaptive optics (LGS-AO) supported NIRC2 camera on the 10-meter Keck telescope. We have measured the proper motion of two of the youngest magnetars, SGR 1806–20 and SGR 1900+14, which have counterparts with K ~21 mag, and have placed a preliminary upper limit on the motion of the young AXP 1E 1841–045. The precision of the proper motion measurement is at the milliarcsecond per year level. Our proper motion measurements now provide evidence to link SGR 1806–20 and SGR 1900+14 with neighboring young star clusters. At the distances of these magnetars, their proper motion corresponds to transverse space velocities of 350 ± 100 km s−1and 130 ± 30 km s−1respectively. The upper limit on the proper motion of AXP 1E 1841–045 is 160 km s−1. With the sample of proper motions available, we conclude that the kinematics of the magnetar family are not distinct from that of pulsars.
Restrictions to neutron star models based on twin-peak quasi-periodic oscillations
Authors: Török Gabriel , Urbanec Martin , Goluchová Kateřina , Bakala Pavel , Šrámková Eva , Stuchlík Zdeněk
Published: March 2013

In a series of works - Török et al. (2010, 2012a) and Urbanec et al. (2010a) - we explored restrictions to neutron star properties that are implied by various models of twin-peak quasi-periodic oscillations. Here we sketch an attempt to confront the obtained mass–angular-momentum relations and limits on neutron star compactness with the parameters estimated by assuming various equations of state and the spin frequency of the atoll source 4U 1636-53.
Modeling pulsar time noise with long term decay modulated by short term oscillations of the magnetic fields of neutron stars
Authors: Xie Yi , Zhang Shuangnan
Published: March 2013

We model the evolution of the magnetic fields of neutron stars as consisting of a long term power-law decay modulated by short term small amplitude oscillations. Our model predictions on the timing noise of neutron stars agree well with the observed statistical properties and correlations of normal radio pulsars. For individual pulsars our model can effectively reduce their timing residuals, thus offering the potential of more sensitive detections of gravitational waves with pulsar timing arrays. Finally our model can also re-produce their observed correlation and oscillations of second derivative of frenquency, as well as the “slow glitch” phenomenon.
Changes in Polarization Position Angle across the Eclipse in the Double Pulsar System
Authors: Yuen R. , Manchester R. N. , Burgay M. , Camilo F. , Kramer M. , Melrose D. B. , Stairs I. H.
Published: March 2013

We investigate the changes in polarization position angle in radiation from pulsar A around the eclipse in the Double Pulsar system PSR J0737-3039A/B at the 20 cm and 50 cm wavelengths using the Parkes 64-m radio telescope. The changes are ~ 2σ during and shortly after the eclipse at 20 cm but less significant at 50 cm. We show that the changes in position angle during the eclipse can be modelled by differential synchrotron absorption in the eclipse regions. Position angle changes after the eclipse are interpreted as Faraday rotation in the magnetotail of pulsar B. Implied charge densities are consistent with the Goldreich-Julian density, suggesting that the particle energies in the magnetotail are mildly relativistic.
Questions on accreting mass and minimum magnetic field of millisecond pulsars
Authors: Zhang C. M.
Published: March 2013

About 0.2 solar mass is absorbed by the millisecond pulsar (MSP) at the binary accretion phase, while the polar magnetic field of MSP is diluted to a magnitude of order 108.5 Gauss, which is proportionally related to the mass accretion rate. It is found that the minimum magnetic field of MSP can be as low as 107 Gauss if the accretion rate of the binary system reaches its the minimum value of 1015 g/s. This bottom field has nothing to do with the MSP initial field. Some questions on MPSs are proposed and answered.
The Ability of the Palestinian Legal System to Secure Adequate Standards of Living: Reform or the Failure of State Duty
Authors: QAFISHEH Mutaz M.
Published: March 2013

In parallel with its efforts to become a full member of the United Nations (UN) and its specialized agencies, Palestine needs to take the implications of joining such organizations in earnest. Admission to the UN, in addition to encompassing rights for states, simultaneously entails duties on the part of the state. One duty is to respect, protect, and fulfil human rights for those living under Palestine's jurisdiction. This paper assesses the ability of the applicable legislation in Palestine to secure adequate standards of living by focusing on three rights: food, housing, and health. Many of the laws relating to these rights date back to the Turkish, British, Jordanian, and Egyptian eras. With a few exceptions, Palestine has so far enacted executive orders to activate these rights based on older laws. Nothing prevents Palestine from modernizing its nutrition, habitation, and medical care systems and joining the community of welfare states.
Rasch-Analyse des Freiburger Fragebogens zur Achtsamkeit
Authors: Sauer Sebastian , Strobl Carolin , Walach Harald , Kohls Niko
Published: March 2013

Ziel der vorliegenden Arbeit ist die psychometrische Überprüfung der 14-Item Version des Freiburger Fragebogens zur Achtsamkeit auf der Grundlage der Rasch-Analyse. Da sowohl eine ein- (Achtsamkeit als Generalfaktor) als auch zweifaktorielle Lösung (Achtsamkeit zusammengesetzt aus Präsenz und Akzeptanz) für den FFA-14 vorgeschlagen wurde, werden in dieser Studie die psychometrischen Kennwerte für beide Lösungen auf der Grundlage des Ratingskalenmodell (RSM) verglichen. Die psychometrische Analyse belegte mit Ausnahme eines Items die psychometrische Qualität des Instruments und zeigte die Überlegenheit der zweifaktoriellen Lösung auf. Jedoch waren auch Boden- und Deckeneffekte nachzuweisen, die die Messung bei Probanden mit sehr hohen bzw. niedrigen Achtsamkeitsausprägungen eventuell verzerren könnten.
Drug and Disease Model Resources: A Consortium to Create Standards and Tools to Enhance Model‐Based Drug Development
Authors: Harnisch L , Matthews I , Chard J , Karlsson MO
Published: March 2013

Model‐based drug development (MBDD) is accepted as a vital approach in understanding patients’ drug‐related benefit and risk by integrating quantitative information integration from diverse sources collected throughout drug development.1 This perspective introduces the activities of the Drug and Disease Model Resources (DDMoRe) consortium, founded in 2011 through the Innovative Medicines Initiative Joint Undertaking (IMI‐JU)2 as a European public–private partnership to address a lack of common tools, languages, and standards for modeling and simulation (M&S) to improve model‐based knowledge integration.

CPT: Pharmacometrics & Systems Pharmacology (2013) 2, e34; doi:10.1038/psp.2013.10; advance online publication 20 March 2013
A crossflow filtration system for constant permeate flux membrane fouling characterization
Authors: Miller Daniel J. , Paul Donald R. , Freeman Benny D.
Published: March 2013

Membrane fouling is often characterized using a crossflow filtration apparatus. Typically, the transmembrane pressure (TMP) difference is fixed, and the flux is allowed to decline as the membrane fouls and the resistance to mass transfer increases. However, as flux varies, so too does the rate at which foulants are brought to the membrane surface, so the observed fouling behavior is not solely the result of membrane/foulant interactions. Constant flux experiments, where the permeate flux is fixed and the TMP difference varies, minimize such variations in the hydrodynamic conditions at the membrane surface, but constant TMP difference experiments dominate the fouling literature because they are more straightforward to execute than constant flux experiments. Additionally, most industrial water purification membrane installations operate at constant flux rather than at constant TMP. Here, we describe the construction and operation of a constant flux crossflow fouling apparatus. System measurement accuracy was validated by comparison of pure water permeance measurements to values specified by the membrane manufacturer, reported elsewhere, and measured by another technique. Fouling experiments were performed with two membrane/foulant systems: polysulfone ultrafiltration membranes with a soybean oil emulsion foulant and PVDF microfiltration membranes with a polystyrene latex bead suspension foulant. Automatic permeate flux control facilitated flux stepping experiments, which are commonly used to determine the threshold flux or critical flux of a membrane/foulant pair. Comparison of a flux stepping experiment with a literature report yielded good agreement.
Reflection of an internal gravity wave beam off a horizontal free-slip surface
Authors: Zhou Qi , Diamessis Peter J.
Published: March 2013

The reflection of a planar finite-amplitude internal gravity wave beam off a free-slip flat horizontal surface is investigated numerically in a uniformly stratified Boussinesq fluid. Nonlinear effects such as mean currents and harmonics are observed in the wave reflection zone. Mean currents form a stationary, vertically oscillatory, layered structure under the free-slip reflecting surface. The vertical wavelength of the mean-flow layers equals half of the vertical wavelength of the reflecting wave. An empirical predictive model for the steady-state mean flow strength, based on the degree of wave nonlinearity and hydrostaticity, is proposed and subsequently compared to the weakly nonlinear theory by Tabaei et al. [J. Fluid Mech. 526, 217–243 (2005)10.1017/S0022112004002769]. Very strong agreement between simulation results and theory is observed for all waves considered, suggesting although weakly nonlinear in its formulation, the Tabaei et al. theory is valid for the full range of finite amplitudes for which a wave remains stable. Both propagating and evanescent superharmonics are observed, and for waves with steepnesses of O(5%), parametric subharmonic instabilities can occur in the later stages of the reflection process. When a subsurface mixed layer is incorporated into the simulations, the mean currents at the middle of the underlying pycnocline are similar in structure and magnitude to their uniformly-stratified counterparts.
Switching of morphotropic phase boundary and large strain response in lead-free ternary (Bi0.5Na0.5)TiO3–(K0.5Bi0.5)TiO3–(K0.5Na0.5)NbO3 system
Authors: Hao Jigong , Shen Bo , Zhai Jiwei , Liu Chunze , Li Xiaolong , Gao Xingyu
Published: March 2013

In this work, we report the phase diagram of lead-free ternary (1 − y)[(1 − x)(Bi0.5Na0.5)TiO3–x(Bi0.5K0.5)TiO3]–y(K0.5Na0.5)NbO3 (BNT–BKT–KNN) system and study the switching characteristics of the morphotropic phase boundary (MPB). The addition of KNN intrinsically changes the structural nature of the system with the shift of MPB from MPB(I) between ferroelectric rhombohedral and ferroelectric tetragonal phases to MPB(II) between ferroelectric rhombohedral and relaxor pseudocubic phases. As the MPB(I) switches to MPB(II), large piezoelectric response with d33 ∼ 150pC/N that obtained for BNT–0.20BKT near MPB(I) almost disappears. Instead, a significant jump of electric-filed-induced strain S up to 0.32%–0.46% (Smax/Emax = 400–575 pm/V) is achieved near MPB(II) due to the shift of the ferroelectric-relaxor transition temperature TF-R down to room temperature. In this study, giant strain ∼0.46% occurs in a very narrow region in the BNT-BKT-KNN system with x = 0.20, y = 0.01, which lies on an underlying tricritical triple point of a rhombohedral (R), tetragonal (T), and pseudocubic (Pc) phases. In-situ high-energy X-ray scattering experiments with external electric field reveal an initial electric-field-induced distortion from the Pc structure for the MPB(II) compositions, while those with single R phase shows no such distortion, which suggests that the large strain achieved near the MPB(II) is likely to be induced by the electric-field-induced structure distortion due to its relative instability structure. We believe that the discovery of a compositional line in the pseudo-ternary system, where the strain response is consistently derivable, should be useful for designing high-performance piezoelectric materials in other BNT-based systems by searching MPBs.
Effect of oscillator strength and intermediate resonance on the performance of resonant phonon-based terahertz quantum cascade lasers
Authors: Fathololoumi S. , Dupont E. , Wasilewski Z. R. , Chan C. W. I. , Razavipour S. G. , Laframboise S. R. , Huang Shengxi , Hu Q. , Ban D. , Liu H. C.
Published: March 2013

We experimentally investigated the effect of oscillator strength (radiative transition diagonality) on the performance of resonant phonon-based terahertz quantum cascade lasers that have been optimized using a simplified density matrix formalism. Our results show that the maximum lasing temperature (Tmax) is roughly independent of laser transition diagonality within the lasing frequency range of the devices under test (3.2–3.7 THz) when cavity loss is kept low. Furthermore, the threshold current can be lowered by employing more diagonal transition designs, which can effectively suppress parasitic leakage caused by intermediate resonance between the injection and the downstream extraction levels. Nevertheless, the current carrying capacity through the designed lasing channel in more diagonal designs may sacrifice even more, leading to electrical instability and, potentially, complete inhibition of the device's lasing operation. We propose a hypothesis based on electric-field domain formation and competition/switching of different current-carrying channels to explain observed electrical instability in devices with lower oscillator strengths. The study indicates that not only should designers maximize Tmax during device optimization but also they should always consider the risk of electrical instability in device operation.
Semi-physical parameter identification for an iron-loss formula allowing loss-separation
Authors: Steentjes S. , Leßmann M. , Hameyer K.
Published: March 2013

This paper presents a semi-physical parameter identification for a recently proposed enhanced iron-loss formula, the IEM-Formula. Measurements are performed on a standardized Epstein frame by the conventional field-metric method under sinusoidal magnetic flux densities up to high magnitudes and frequencies. Quasi-static losses are identified on the one hand by point-by-point dc-measurements using a flux-meter and on the other hand by extrapolating higher frequency measurements to dc magnetization using the statistical loss-separation theory (Jacobs et al., “Magnetic material optimization for hybrid vehicle PMSM drives,” in Inductica Conference, CD-Rom, Chicago/USA, 2009). Utilizing this material information, possibilities to identify the parameter of the IEM-Formula are analyzed. Along with this, the importance of excess losses in present-day non-grain oriented Fe-Si laminations is investigated. In conclusion, the calculated losses are compared to the measured losses.
Fourier-transform infrared spectroscopy of hopping oscillations of electrons in vanadium oxide nanotubes
Authors: Ha Oh Min , Jung Kim Hyo , Won Lee Kyu , Eui Lee Cheol
Published: March 2013

We have employed Fourier-transform infrared spectroscopy in order to study the phase transitions and charge dynamics in vanadium oxide nanotubes with alternating organic and inorganic layers. The structural phase transitions accompanied by conformational changes in the organic layer were identified. Besides, a phase transition around 343 K from an insulator phase to a metal-like one that arises from electron delocalization was observed in the inorganic layers, manifesting an electron hopping oscillation between the V4+ and V5+ sites.
Optically pumped GaInN/GaN multiple quantum wells for the realization of efficient green light-emitting devices
Authors: Schiavon Dario , Binder Michael , Loeffler Andreas , Peter Matthias
Published: March 2013

We report on a green light-emitting device, in which the light of an efficient blue 1 mm2 GaInN/GaN light-emitting diode (LED) is converted into green light by an optically pumped GaInN/GaN multiple quantum well structure. This solution reached an efficacy of 127 lm/W, i.e., higher than that of state-of-the-art 1 mm2 GaInN/GaN LEDs emitting directly at the target wavelength, at 350 mA current and 535 nm peak wavelength. Optically pumped converters overcome the design limitations of typical multiple quantum well LEDs, where carrier transport issues limit the maximum number of functioning wells and might help to solve the problem of the green gap.
Thermal conduction inhomogeneity of nanocrystalline diamond films by dual-side thermoreflectance
Authors: Bozorg-Grayeli Elah , Sood Aditya , Asheghi Mehdi , Gambin Vincent , Sandhu Rajinder , Feygelson Tatyana I. , Pate Bradford B. , Hobart Karl , Goodson Kenneth E.
Published: March 2013

Thin diamond films of thickness near 1 μm can have highly nonuniform thermal conductivities owing to spatially varying disorder associated with nucleation and grain coalescence. Here, we examine the nonuniformity for nanocrystalline chemical vapor deposited diamond films of thickness 0.5, 1.0, and 5.6 μm using picosecond thermoreflectance from both the top and bottom diamond surfaces, enabled by etching a window in the silicon substrate. The extracted local thermal conductivities vary from less than 100 W m−1 K−1 to more than 1300 W m−1 K−1 and suggest that the most defective material is confined to within 1 μm of the growth surface.
Communication: Solvation and dielectric response in ionic liquids—Conductivity extension of the continuum model
Authors: Zhang X.-X. , Schröder C. , Ernsting N. P.
Published: March 2013

The solvation response of a polarity probe in a conducting liquid is analyzed based on simple continuum theory. A multi-exponential description of the dynamics is inverted to give an effective dc conductivity and a generalized permittivity spectrum in terms of Debye modes. For Coumarin 153 in ionic liquids the conductivity is found to be reduced systematically from the bulk value, whereas the permittivity from GHz-THz bulk absorption measurements is well reproduced by the solvation experiment. Thus, by using a dye as molecular antenna, the dielectric dispersion of the microscopic environment can be obtained.
Green luminescence from Cu-doped ZnO nanorods: Role of Zn vacancies and negative thermal quenching
Authors: Huang X. H. , Zhang C. , Tay C. B. , Venkatesan T. , Chua S. J.
Published: March 2013

Bright and stable structured green luminescence (GL) is achieved from solution-grown Cu-doped ZnO nanorods. Dependence of photoluminescence on the annealing parameters reveals that GL is correlated with creation of Zn vacancies (VZn) and then formation of Cu dopants at Zn sites (CuZn). High internal quantum efficiency (43%) of the GL can be sustained up to 240 K due to negative thermal quenching. In contrast to the poor stability of defects-related visible emission, the structured GL shows good stability with respect to sample heating. Cu-doped ZnO nanorods with strong and stable GL have potential applications in visible light display and lighting.
Multiple oxide content media for columnar grain growth in L1 FePt thin films
Authors: Ho Hoan , Yang En , Laughlin David E. , Zhu Jian-Gang
Published: March 2013

An approach to enhance the height-to-diameter ratio of FePt grains in heat-assisted magnetic recording media is proposed. The FePt-SiOx thin films are deposited with a decrease of the SiOx percentage along the film growth direction. When bi-layer and tri-layer media are sputtered at 410 °C, we observe discontinuities in the FePt grains at interfaces between layers, which lead to poor epitaxial growth. Due to increased atomic diffusion, the bi-layer media sputtered at 450 °C is shown to (1) grow into continuous columnar grains with similar size as single-layer media but much higher aspect ratio, (2) have better L10 ordering and larger coercivity.
Effect of etching stop layer on characteristics of amorphous IGZO thin film transistor fabricated at low temperature
Authors: Li Xifeng , Xin Enlong , Chen Longlong , Shi Jifeng , Zhang Jianhua
Published: March 2013

Transparent bottom-gate amorphous Indium-Gallium-Zinc Oxide (a-IGZO) thin-film transistors (TFTs) had been successfully fabricated at relative low temperature. The influence of reaction gas ratio of N2O and SiH4 during the growth of etching stop layer (SiOx) on the characteristics of a-IGZO TFTs was investigated. The transfer characteristics of the TFTs were changed markedly because active layer of a-IGZO films was modified by plasma in the growth process of SiOx. By optimizing the deposition parameters of etching stop layer process, a-IGZO TFTs were manufactured and exhibited good performance with a field-effect mobility of 8.5 cm2V-1s-1, a threshold voltage of 1.3 V, and good stability under gate bias stress of 20 V for 10000 s.
Planning toward Equal Accessibility to Services: A Quadratic Programming Approach
Authors: Wang Fahui , Tang Quan
Published: March 2013

In the literature various accessibility indices have been developed to assess the relative ease by which the locations of services (supply) can be reached from a residential (demand) location. In this paper we address the planning problem: how the resources can be redistributed to achieve the highest equality of accessibility to the service providers. In particular, a quadratic programming approach is used to minimize the variance of accessibility scores across demand locations by readjusting the amounts of service supplies. Two case studies—job access in Columbus, OH and primary healthcare access in Chicago, IL—are used to illustrate the method. The result suggests that in order to achieve better equality of accessibility, peripheral areas, in general, need additional supplies to compensate for their less-central locations, and some central city areas also need to add supplies to accommodate high demands by the high population density there.
Development of a Combined Energy-Demands Calculator for Urban Building Communities in Korea
Authors: Chung Mo , Lee Suk Gyu , Park Chuhwan , Park Hwa-Choon , Im Yong-Hoon
Published: March 2013

A decision-support tool based on relational database technology is developed to aid the planning of energy supply systems for urban communities. The building-load models derived from the data measured or surveyed in Korea over the last two decades are computerized using Microsoft Access® as an application platform. The tool calculates energy demands for arbitrary combinations of buildings in an urban community without requiring detailed technological information. Nonexpert urban planners can use the package by providing simple input parameters such as floor area, building type, and city where the site is located. The program calculates the time series based on the demands for electricity, heating, cooling, and hot water loads for the 8760 hours of a year. It also produces indicative characteristics of each load type such as the annual maximums, trends of the daily maximums and minimums, and the annual sums of energy. Urban planners can use these characteristics of the load profiles in their decision processes at the early stages of planning. The detailed time series can be further exploited for subsequent analysis, such as device operational simulation or cost estimation if more sophisticated analysis is necessary. A case study for an actual project is presented for demonstrational purposes.
A Household Time-Use and Energy-Consumption Model with Multiple Behavioral Interactions and Zero Consumption
Authors: Yu Biying , Zhang Junyi , Fujiwara Akimasa
Published: March 2013

This study develops a new household resource allocation model, which incorporates multiple interactions (including the interaction between time use and energy consumption, the interactivity interaction, the inter-end-use interaction, and the intrahousehold interaction) based on multilinear utility functions and endogenously represents zero consumption for both time and energy within the group decision-making modeling framework. This may be the first model in literature to jointly accommodate all these behavioral mechanisms in a unified and consistent modeling framework, especially in the context of time use and energy consumption. The model is estimated using data collected in a household survey in Beijing in 2010. Estimation results reveal that: (1) synergic effects are observed with respect to in-home time use and energy consumption, out-of-home time use across varied activities, and in-home energy consumption from different end uses; (2) competitive relationships are detected between in-home time use and out-of-home energy consumption, out-of-home time use and in-home energy consumption, in-home and out-of-home energy consumption, and time use. These not only support the joint representation for time use and energy consumption behavior but also for the energy consumption behavior of in-home end uses and out-of-home vehicles. Additionally, it is found that the intrahousehold interaction does exist.
Improving the experiences and health of people with multimorbidity: exploratory research with policymakers and information providers on comorbid arthritis
Authors: Ryan Rebecca E. , Hill Sophie J.
Published: March 2013

Multimorbidity has emerged as a complex health issue with the burden falling predominantly on patients, families and the primary health care sector. Evidence-informed communication and participation, activities informed by evidence and people’s views and experiences, has the potential to improve health outcomes for people with multimorbidity. In recognition of their role in shaping future actions, we conducted focus groups with policymakers and information providers. The aim of this article is to report on the range and impacts of communication problems in multimorbidity, and identify points of intervention. To facilitate and focus dialogue, comorbid arthritis was selected as the case example. Two focus groups were held: one with policymakers and the other with health information providers. Participants were asked to discuss communication problems and possibilities relevant to multimorbidity, using examples from comorbid arthritis where relevant. Participants highlighted three main areas on which to focus future efforts to improve the health outcomes and experiences of people with multimorbidity: (1) make explicit the problems of multimorbidity and communication; (2) recognise that both multimorbidity and communication issues are compounding factors; and (3) consider actions at policy, service, community and individual levels. Examining multimorbidity through the lens of communication issues identified the significant burden across different domains of the health system. The focus on communication may facilitate a cross-disease perspective to emerge and assist with policy development.
Predictive value of bovine follicular components as markers of oocyte developmental potential
Authors: Matoba Satoko , Bender Katrin , Fahey Alan G. , Mamo Solomon , Brennan Lorraine , Lonergan Patrick , Fair Trudee
Published: March 2013

The follicle is a unique micro-environment within which the oocyte can develop and mature to a fertilisable gamete. The aim of this study was to investigate the ability of a panel of follicular parameters, including intrafollicular steroid and metabolomic profiles and theca, granulosa and cumulus cell candidate gene mRNA abundance, to predict the potential of bovine oocytes to develop to the blastocyst stage in vitro. Individual follicles were dissected from abattoir ovaries, carefully ruptured under a stereomicroscope and the oocyte was recovered and individually processed through in vitro maturation, fertilisation and culture. The mean (± s.e.m.) follicular concentrations of testosterone (62.8 ± 4.8 ng mL–1), progesterone (616.8 ± 31.9 ng mL–1) and oestradiol (14.4 ± 2.4 ng mL–1) were not different (P > 0.05) between oocytes that formed (competent) or failed to form (incompetent) blastocysts. Principal-component analysis of the quantified aqueous metabolites in follicular fluid showed differences between oocytes that formed blastocysts and oocytes that degenerated; l-alanine, glycine and l-glutamate were positively correlated and urea was negatively correlated with blastocyst formation. Follicular fluid associated with competent oocytes was significantly lower in palmitic acid (P = 0.023) and total fatty acids (P = 0.031) and significantly higher in linolenic acid (P = 0.036) than follicular fluid from incompetent oocytes. Significantly higher (P < 0.05) transcript abundance of LHCGR in granulosa cells, ESR1 and VCAN in thecal cells and TNFAIP6 in cumulus cells was associated with competent compared with incompetent oocytes.
A single intact ATPase site of the ABC transporter BtuCD drives 5% transport activity yet supports full in vivo vitamin B
12
utilization
Authors: Tal Nir , Ovcharenko Elena , Lewinson Oded
Published: March 2013

In all kingdoms of life, ATP binding cassette (ABC) transporters are essential to many cellular functions. In this large superfamily of proteins, two catalytic sites hydrolyze ATP to power uphill substrate translocation. A central question in the field concerns the relationship between the two ATPase catalytic sites: Are the sites independent of one another? Are both needed for function? Do they function cooperatively? These issues have been resolved for type I ABC transporters but never for a type II ABC transporter. The many mechanistic differences between type I and type II ABC transporters raise the question whether in respect to ATP hydrolysis the two subtypes are similar or different. We have addressed this question by studying the
Escherichia coli
vitamin B
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type II ABC transporter BtuCD. We have constructed and purified a series of BtuCD variants where both, one, or none of the ATPase sites were rendered inactive by mutation. We find that, in a membrane environment, the ATPase sites of BtuCD are highly cooperative with a Hill coefficient of 2. We also find that, when one of the ATPase sites is inactive, ATP hydrolysis and vitamin B
12
transport by BtuCD is reduced by 95%. These exact features are also shared by the archetypical type I maltose ABC transporter. Remarkably, mutants that have lost 95% of their ATPase and transport capabilities still retain the ability to fully use vitamin B
12
in vivo. The results demonstrate that, despite the many differences between type I and type II ABC transporters, the fundamental mechanism of ATP hydrolysis remains conserved.
Two molybdate/tungstate ABC transporters that interact very differently with their substrate binding proteins
Authors: Vigonsky Elena , Ovcharenko Elena , Lewinson Oded
Published: March 2013

In all kingdoms of life, ATP Binding Cassette (ABC) transporters participate in many physiological and pathological processes. Despite the diversity of their functions, they have been considered to operate by a largely conserved mechanism. One deviant is the vitamin B
12
transporter BtuCD that has been shown to operate by a distinct mechanism. However, it is unknown if this deviation is an exotic example, perhaps arising from the nature of the transported moiety. Here we compared two ABC importers of identical substrate specificity (molybdate/tungstate), and find that their interactions with their substrate binding proteins are utterly different. One system forms a high-affinity, slow-dissociating complex that is destabilized by nucleotide and substrate binding. The other forms a low-affinity, transient complex that is stabilized by ligands. The results highlight significant mechanistic divergence among ABC transporters, even when they share the same substrate specificity. We propose that these differences are correlated with the different folds of the transmembrane domains of ABC transporters.
Natural enemy interactions constrain pest control in complex agricultural landscapes
Authors: Martin Emily A. , Reineking Björn , Seo Bumsuk , Steffan-Dewenter Ingolf
Published: March 2013

Biological control of pests by natural enemies is a major ecosystem service delivered to agriculture worldwide. Quantifying and predicting its effectiveness at large spatial scales is critical for increased sustainability of agricultural production. Landscape complexity is known to benefit natural enemies, but its effects on interactions between natural enemies and the consequences for crop damage and yield are unclear. Here, we show that pest control at the landscape scale is driven by differences in natural enemy interactions across landscapes, rather than by the effectiveness of individual natural enemy guilds. In a field exclusion experiment, pest control by flying insect enemies increased with landscape complexity. However, so did antagonistic interactions between flying insects and birds, which were neutral in simple landscapes and increasingly negative in complex landscapes. Negative natural enemy interactions thus constrained pest control in complex landscapes. These results show that, by altering natural enemy interactions, landscape complexity can provide ecosystem services as well as disservices. Careful handling of the tradeoffs among multiple ecosystem services, biodiversity, and societal concerns is thus crucial and depends on our ability to predict the functional consequences of landscape-scale changes in trophic interactions.