bluuebunny/crossref_metadata_2025 huggingface dataset:
Interband magneto-spectroscopy in InSb square and parabolic quantum wells
Authors: Kasturiarachchi T. , Saha D. , Pan X. , Sanders G. D. , Edirisooriya M. , Mishima T. D. , Doezema R. E. , Stanton C. J. , Santos M. B.
Published: June 2015

We measure the magneto-optical absorption due to intersubband optical transitions between conduction and valence subband Landau levels in InSb square and parabolic quantum wells. InSb has the narrowest band gap (0.24 eV at low temperature) of the III–V semiconductors leading to a small effective mass (0.014 m0) and a large g–factor (−51). As a result, the Landau level spacing is large at relatively small magnetic fields (<8 T), and one can observe spin-splitting of the Landau levels. We examine two structures: (i) a multiple-square-well structure and (ii) a structure containing multiple parabolic wells. The energies and intensities of the strongest features are well explained by a modified Pidgeon-Brown model based on an 8-band k•p model that explicitly incorporates pseudomorphic strain. The strain is essential for obtaining agreement between theory and experiment. While modeling the square well is relatively straight-forward, the parabolic well consists of 43 different layers of various thickness to approximate a parabolic potential. Agreement between theory and experiment for the parabolic well validates the applicability of the model to complicated structures, which demonstrates the robustness of our model and confirms its relevance for developing electronic and spintronic devices that seek to exploit the properties of the InSb band structure.
Spin-glass-like behavior and negative thermal expansion in antiperovskite Mn3Ni1−xCuxN compounds
Authors: Ding Lei , Wang Cong , Sun Ying , Colin Claire V. , Chu Lihua
Published: June 2015

The Cu-doping effect on the lattice and magnetic properties in Mn3Ni1−xCuxN (x = 0, 0.3, 0.5, 0.7, 1.0) was extensively investigated. We observed that the Cu-doping at the Ni site complicated the magnetic ground states, which induced the competition of antiferromagnetic and ferromagnetic interactions. Spin-glass-like behavior, arising from possible site-randomness and competing interactions of magnetism, was observed in compounds with x = 0.3, 0.5, and 0.7, and typically discussed by means of the measurement of ac magnetic susceptibility for x = 0.7. The negative thermal expansion (NTE) behavior, due to the magnetic ordering transition, was observed in Mn3Ni1−xCuxN compounds using variable temperature x-ray diffraction. It reveals that the introduction of Cu effectively broadens the temperature range displaying negative thermal expansion. The relationship between the local lattice distortion and the competing magnetic ground states might play an important role in broadening the NTE temperature range in this antiperovskite compound.
Fast pulsed operation of a small non-radioactive electron source with continuous emission current control
Authors: Cochems P. , Kirk A. T. , Bunert E. , Runge M. , Goncalves P. , Zimmermann S.
Published: June 2015

Non-radioactive electron sources are of great interest in any application requiring the emission of electrons at atmospheric pressure, as they offer better control over emission parameters than radioactive electron sources and are not subject to legal restrictions. Recently, we published a simple electron source consisting only of a vacuum housing, a filament, and a single control grid. In this paper, we present improved control electronics that utilize this control grid in order to focus and defocus the electron beam, thus pulsing the electron emission at atmospheric pressure. This allows short emission pulses and excellent stability of the emitted electron current due to continuous control, both during pulsed and continuous operations. As an application example, this electron source is coupled to an ion mobility spectrometer. Here, the pulsed electron source allows experiments on gas phase ion chemistry (e.g., ion generation and recombination kinetics) and can even remove the need for a traditional ion shutter.
Non-thermal effects on femtosecond laser ablation of polymers extracted from the oscillation of time-resolved reflectivity
Authors: Kumada Takayuki , Akagi Hiroshi , Itakura Ryuji , Otobe Tomohito , Nishikino Masaharu , Yokoyama Atsushi
Published: June 2015

The dynamics of femtosecond laser ablation of transparent polymers were examined using time-resolved reflectivity. When these polymers were irradiated by a pump pulse with fluence above the ablation threshold of 0.8–2.0 J/cm2, we observed the oscillation of the reflectivity caused by the interference between the reflected probe pulses from the sample surface and the thin layer due to the non-thermal photomechanical effects of spallation. As the fluence of the pump pulse increased, the separation velocity of the thin layer increased from 6 km/s to the asymptotic value of 11 km/s. It is suggested that the velocities are determined by shock-wave velocities of the photo-excited layer.
Single-pulse picking at kHz repetition rates using a Ge plasma switch at the free-electron laser FELBE
Authors: Schmidt J. , Winnerl S. , Seidel W. , Bauer C. , Gensch M. , Schneider H. , Helm M.
Published: June 2015

We demonstrate a system for picking of mid-infrared and terahertz (THz) radiation pulses from the free-electron laser (FEL) FELBE operating at a repetition rate of 13 MHz. Single pulses are reflected by a dense electron-hole plasma in a Ge slab that is photoexcited by amplified near-infrared (NIR) laser systems operating at repetition rates of 1 kHz and 100 kHz, respectively. The peak intensity of picked pulses is up to 400 times larger than the peak intensity of residual pulses. The required NIR fluence for picking pulses at wavelengths in the range from 5 μm to 30 μm is discussed. In addition, we show that the reflectivity of the plasma decays on a time scale from 100 ps to 1 ns dependent on the wavelengths of the FEL and the NIR laser. The plasma switch enables experiments with the FEL that require high peak power but lower average power. Furthermore, the system is well suited to investigate processes with decay times in the μs to ms regime, i.e., much longer than the 77 ns long pulse repetition period of FELBE.
A comparison of weighted ensemble and Markov state model methodologies
Authors: Feng Haoyun , Costaouec Ronan , Darve Eric , Izaguirre Jesús A.
Published: June 2015

Computation of reaction rates and elucidation of reaction mechanisms are two of the main goals of molecular dynamics (MD) and related simulation methods. Since it is time consuming to study reaction mechanisms over long time scales using brute force MD simulations, two ensemble methods, Markov State Models (MSMs) and Weighted Ensemble (WE), have been proposed to accelerate the procedure. Both approaches require clustering of microscopic configurations into networks of “macro-states” for different purposes. MSMs model a discretization of the original dynamics on the macro-states. Accuracy of the model significantly relies on the boundaries of macro-states. On the other hand, WE uses macro-states to formulate a resampling procedure that kills and splits MD simulations for achieving better efficiency of sampling. Comparing to MSMs, accuracy of WE rate predictions is less sensitive to the definition of macro-states. Rigorous numerical experiments using alanine dipeptide and penta-alanine support our analyses. It is shown that MSMs introduce significant biases in the computation of reaction rates, which depend on the boundaries of macro-states, and Accelerated Weighted Ensemble (AWE), a formulation of weighted ensemble that uses the notion of colors to compute fluxes, has reliable flux estimation on varying definitions of macro-states. Our results suggest that whereas MSMs provide a good idea of the metastable sets and visualization of overall dynamics, AWE provides reliable rate estimations requiring less efforts on defining macro-states on the high dimensional conformational space.
Sr2IrO4: Gateway to cuprate superconductivity?
Authors: Mitchell J. F.
Published: June 2015

High temperature superconductivity in cuprates remains a defining challenge in condensed matter physics. Recently, a new set of related compounds based on Ir rather than Cu has been discovered that may be on the verge of superconductivity themselves or be able to shed new light on the underlying interactions responsible for superconductivity in the cuprates.
Backbone NxH compounds at high pressures
Authors: Goncharov Alexander F. , Holtgrewe Nicholas , Qian Guangrui , Hu Chaohao , Oganov Artem R. , Somayazulu Maddury , Stavrou Elissaios , Pickard Chris J. , Berlie Adam , Yen Fei , Mahmood Mahmood , Lobanov Sergey S. , Konôpková Zuzana , Prakapenka Vitali B.
Published: June 2015

Optical and synchrotron x-ray diffraction diamond anvil cell experiments have been combined with first-principles theoretical structure predictions to investigate mixtures of N2 and H2 up to 55 GPa. Our experiments show the formation of structurally complex van der Waals compounds [see also D. K. Spaulding et al., Nat. Commun. 5, 5739 (2014)] above 10 GPa. However, we found that these NxH (0.5 < x < 1.5) compounds transform abruptly to new oligomeric materials through barochemistry above 47 GPa and photochemistry at pressures as low as 10 GPa. These oligomeric compounds can be recovered to ambient pressure at T < 130 K, whereas at room temperature, they can be metastable on pressure release down to 3.5 GPa. Extensive theoretical calculations show that such oligomeric materials become thermodynamically more stable in comparison to mixtures of N2, H2, and NH3 above approximately 40 GPa. Our results suggest new pathways for synthesis of environmentally benign high energy-density materials. These materials could also exist as alternative planetary ices.
Investigation of shock-shock interaction and Mach reflection in laterally colliding laser-blow-off plasmas
Authors: Kumar Bhupesh , Singh R. K. , Sengupta Sudip , Kaw P. K. , Kumar Ajai
Published: June 2015

Interactions of two Li plasma plumes and shock waves are investigated at various pressures (∼10−5 to 3 mbar) in the argon gas ambient. Fast imaging and optical emission spectroscopy are used to study the plume dynamics and characteristic emission of plasmas. The plasma plumes are created in laser-blow-off geometry. The expansion of plasma plumes in the ambient gas leads to the formation of an interaction zone. The formation of interaction zone is dependent on the ambient pressure and below a certain pressure, no significant change is observed in the shape and size of the interaction plasma. In the higher pressure, formation of interaction zone and its shape are dependent on ambient pressure. Dynamics of seed plasmas and interaction zone are also affected by the shock-shock interactions. The shock-shock interaction depends on the angle of incidence (α) between two shock waves at the initial time of interaction but as the plumes expand, the shock-shock interaction does not follow α dependence.
Low-frequency characteristics in the wake of a circular disk
Authors: Yang Jianzhi , Liu Minghou , Wu Guang , Liu Quan , Zhang Xintai
Published: June 2015

Numerical simulations of flow over a circular disk have been performed in this study at Re = 250, 300, 3000, and 104. The Fourier spectra analysis of the velocity at different positions suggests that together with the natural vortex-shedding frequency and the shear-layer Kelvin-Helmholtz instability frequency, several much lower frequencies are also detected when the Reynolds number (Re) increases to 300: one is fp ≈ 0.03, another one is fr ≈ 0.02, and its second harmonic is at about 0.04 and a low frequency of about 0.05. Considering the limited time length of the data, time-frequency analysis based on wavelet transform is then performed. It is found that the local frequencies of the amplitude peaks for the large-scale vortex shedding and shear-layer Kelvin-Helmholtz instability vary irregularly with time, indicating that the traditional Fourier analysis of the numerical signals would not be representative. Nevertheless, the low frequencies fp ≈ 0.03 and fr ≈ 0.02 are clearly confirmed. The frequencies of about 0.04 and 0.05 are observed to occur in some time periods but with much weaker magnitude. It is found that the low-frequency signals keep nearly invariant as Reynolds number increases. The physical origins of the low frequencies fp ≈ 0.03 and fr ≈ 0.02 are then investigated. The physical origin of fp ≈ 0.03 is due to a low-frequency pumping motion of the recirculation bubble, and the fr ≈ 0.02 signal is due to a low-frequency modulation in the rotation of the azimuthal location of large-scale vortex shedding (i.e., the changing of the rotation direction). To characterize the low-frequency unsteadiness of the recirculation bubble, the temporal evolution of the low-pass filtered flow field is investigated. It is observed that the pumping motion of the recirculation bubble is associated with the growing and shedding of the large toroidal vortices formed in the bubble, which is closely related to the behavior of the separated shear layer. The separated shear layer rolls up later in the state with longer recirculation bubble, whereas it rolls up earlier in the state with shorter bubble.
Quantum mechanical calculations of state-to-state cross sections and rate constants for the F + DCl → Cl + DF reaction
Authors: Bulut Niyazi , Kłos Jacek , Roncero Octavio
Published: June 2015

We present accurate state-to-state quantum wave packet calculations of integral cross sections and rate constants for the title reaction. Calculations are carried out on the best available ground 12A′ global adiabatic potential energy surface of Deskevich et al. [J. Chem. Phys. 124, 224303 (2006)]. Converged state-to-state reaction cross sections have been calculated for collision energies up to 0.5 eV and different initial rotational and vibrational excitations, DCl(v = 0, j = 0 − 1; v = 1, j = 0). Also, initial-state resolved rate constants of the title reaction have been calculated in a temperature range of 100-400 K. It is found that the initial rotational excitation of the DCl molecule does not enhance reactivity, in contract to the reaction with the isotopologue HCl in which initial rotational excitation produces an important enhancement. These differences between the isotopologue reactions are analyzed in detail and attributed to the presence of resonances for HCl(v = 0, j), absent in the case of DCl(v = 0, j). For vibrational excited DCl(v = 1, j), however, the reaction cross section increases noticeably, what is also explained by another resonance.
Assessment of TD-DFT and LF-DFT for study of d − d transitions in first row transition metal hexaaqua complexes
Authors: Vlahović Filip , Perić Marko , Gruden-Pavlović Maja , Zlatar Matija
Published: June 2015

Herein, we present the systematic, comparative computational study of the d − d transitions in a series of first row transition metal hexaaqua complexes, [M(H2O)6]n+ (M2+/3+ = V 2+/3+, Cr2+/3+, Mn2+/3+, Fe2+/3+, Co2+/3+, Ni2+) by the means of Time-dependent Density Functional Theory (TD-DFT) and Ligand Field Density Functional Theory (LF-DFT). Influence of various exchange-correlation (XC) approximations have been studied, and results have been compared to the experimental transition energies, as well as, to the previous high-level ab initio calculations. TD-DFT gives satisfactory results in the cases of d2, d4, and low-spin d6 complexes, but fails in the cases when transitions depend only on the ligand field splitting, and for states with strong character of double excitation. LF-DFT, as a non-empirical approach to the ligand field theory, takes into account in a balanced way both dynamic and non-dynamic correlation effects and hence accurately describes the multiplets of transition metal complexes, even in difficult cases such as sextet-quartet splitting in d5 complexes. Use of the XC functionals designed for the accurate description of the spin-state splitting, e.g., OPBE, OPBE0, or SSB-D, is found to be crucial for proper prediction of the spin-forbidden excitations by LF-DFT. It is shown that LF-DFT is a valuable alternative to both TD-DFT and ab initio methods.
Low-loss dielectric-loaded graphene surface plasmon polariton waveguide based biochemical sensor
Authors: Wijesinghe Thamani M. , Premaratne Malin , Agrawal Govind P.
Published: June 2015

We have modeled and numerically simulated the performance of a dielectric-loaded graphene surface-plasmon-polariton (DL-GSPP) waveguide as a biochemical sensing device. In our device, the conventionally used gold layer is replaced with a graphene microribbon for the detection of biochemical molecules. The graphene layer is incorporated to minimize ohmic losses and to enhance the adsorption of biomolecules so that the sensor sensitivity is increased significantly. The sensor performance is quantified through numerical simulations carried out by varying device parameters such as waveguide length, effective mode index, dimension of the dielectric ridge, and the length and the number of graphene layers. One of the prominent features of our DL-GSPP waveguide sensor is that its length is in the millimeter range, an essential requirement for realistic plasmonic waveguide sensors. The average sensitivity of DL-GSPP structure is found to be in the range of 3–6 μRIU (refractive index units), which is comparable to the values obtained using surface-plasmon resonance (1–10 μRIU) and long-range waveguide sensors (0.1–5 μRIU).
Comment on “Effective thermal conductivity of metal and non-metal particulate composites with interfacial thermal resistance at high volume fraction of nano to macro-sized spheres” [J. Appl. Phys. 117, 055104 (2015)]
Authors: Pal Rajinder
Published: June 2015

In a recent article, Faroughi and Huber [J. Appl. Phys. 117, 055104 (2015)] propose two theoretical models to compute the effective thermal conductivity of metal and dielectric spherical particle reinforced composites with interfacial thermal resistance. The models are based on the differential effective medium (DEM) theory. The authors have failed to cite and discuss the paper of Pal [Mater. Sci. Eng., A 498, 135–141 (2008)] where similar models have been derived using the same approach (DEM theory). Furthermore, the models proposed by Faroughi and Huber are seriously flawed in that the “excluded volume effect” is taken into account two times, instead of once, in their derivations. Last but not least, there are typos in their models.
Nodal surfaces and interdimensional degeneracies
Authors: Loos Pierre-François , Bressanini Dario
Published: June 2015

The aim of this paper is to shed light on the topology and properties of the nodes (i.e., the zeros of the wave function) in electronic systems. Using the “electrons on a sphere” model, we study the nodes of two-, three-, and four-electron systems in various ferromagnetic configurations (sp, p2, sd, pd, p3, sp2, and sp3). In some particular cases (sp, p2, sd, pd, and p3), we rigorously prove that the non-interacting wave function has the same nodes as the exact (yet unknown) wave function. The number of atomic and molecular systems for which the exact nodes are known analytically is very limited and we show here that this peculiar feature can be attributed to interdimensional degeneracies. Although we have not been able to prove it rigorously, we conjecture that the nodes of the non-interacting wave function for the sp3 configuration are exact.
Anisotropy of tensile strength and fracture mode of perfect face-centered-cubic crystals
Authors: Wang R. F. , Xu J. , Qu R. T. , Liu Z. Q. , Zhang Z. F.
Published: June 2015

This study presents an effective method to calculate the ideal tensile strength of six face-centered-cubic (fcc) crystals (Cu, Au, Ni, Pt, Al, and Ir) along an arbitrary tensile direction by considering the coupling effect of normal stress and shear stress on a given crystallographic plane. Meanwhile, the fracture modes of the six crystals can also be derived from the competition between shear and cleavage fracture along different crystallographic planes. The results show that both the intrinsic factors (the ideal shear strength and cleavage strength of low-index planes) and the orientation may affect the tensile strength and fracture modes of ideal fcc crystals, which may give the reliable strength limit of fcc metals and well interpret the observed high strength in nano-scale mechanical experiments.
Analytical surface-potential compact model for amorphous-IGZO thin-film transistors
Authors: Zong Zhiwei , Li Ling , Jang Jin , Lu Nianduan , Liu Ming
Published: June 2015

We present a compact model based on surface potential for amorphous-InGaZnO thin-film transistors, built using multiple trapping and detrapping theory. Using this model, the surface potential can be calculated analytically, so it can be used to rapidly determine the transistor characteristics during circuit simulation. We verified the proposed model using both numerical simulation and experiment, showing that the model is accurate over a wide range of operation regions. The model also provides a physics-based consistent description of DC and AC device characteristics and enables accurate design of amorphous InGaZnO thin-film transistor circuits.
Broadband absorption enhancement in organic solar cells with an antenna layer through surface-plasmon mediated energy transfer
Authors: Jin Yu , Feng Jing , Zhang Xu-Lin , Xu Ming , Chen Qi-Dai , Wu Zhi-Jun , Sun Hong-Bo
Published: June 2015

We demonstrated a strategy to realize broadband enhanced absorption in the top-incident inverted organic solar cells (OSCs) by employing an external antenna layer on top of the periodic corrugated metallic anode. Surface-plasmon polaritons (SPPs) are excited on the opposite interfaces of the periodic corrugated metallic anode, which mediate the energy transfer from the antenna layer to the active layer through the anode. The absorption of the OSCs is significantly broadened and enhanced by tuning the SPP resonance to coincide with both the emission of the antenna and the absorption of the active material. The power conversion efficiency exhibits an enhancement of 16% compared to that of the OSCs without the antenna layer.
Propagation of intense laser pulses in strongly magnetized plasmas
Authors: Yang X. H. , Yu W. , Xu H. , Yu M. Y. , Ge Z. Y. , Xu B. B. , Zhuo H. B. , Ma Y. Y. , Shao F. Q. , Borghesi M.
Published: June 2015

Propagation of intense circularly polarized laser pulses in strongly magnetized inhomogeneous plasmas is investigated. It is shown that a left-hand circularly polarized laser pulse propagating up the density gradient of the plasma along the magnetic field is reflected at the left-cutoff density. However, a right-hand circularly polarized laser can penetrate up the density gradient deep into the plasma without cutoff or resonance and turbulently heat the electrons trapped in its wake. Results from particle-in-cell simulations are in good agreement with that from the theory.
A reconfigurable gate architecture for Si/SiGe quantum dots
Authors: Zajac D. M. , Hazard T. M. , Mi X. , Wang K. , Petta J. R.
Published: June 2015

We demonstrate a reconfigurable quantum dot gate architecture that incorporates two interchangeable transport channels. One channel is used to form quantum dots, and the other is used for charge sensing. The quantum dot transport channel can support either a single or a double quantum dot. We demonstrate few-electron occupation in a single quantum dot and extract charging energies as large as 6.6 meV. Magnetospectroscopy is used to measure valley splittings in the range of 35–70 μeV. By energizing two additional gates, we form a few-electron double quantum dot and demonstrate tunable tunnel coupling at the (1,0) to (0,1) interdot charge transition.
A Simple, One-Pot Synthesis of Trans-Substituted Spiro [5,5] undecane-1,5,9-triones with Aromatic Aldehydes and Meldrum's Acid as the Starting Materials
Authors: Ou-Yang Jingping , Zhao Yu , Jiang Huailei , Meng Lingxin , Li Xingshu , Jia Xian
Published: June 2015

A simple, one-pot process for the construction of substituted spiro[5,5]undecane-1,5,9-triones using aromatic aldehydes and Meldrum’s acid, and aniline as a catalyst, is reported. Fifteen compounds were synthesized, and the trans/cis ratios were calculated based on 1H NMR analyses of the unpurified products. Quantum mechanical calculations and X-ray diffraction were undertaken to identify the configuration of compound 2a. The proposed mechanisms for these reactions are presented in this paper. In contrast to previous literature, this method endows excellent diastereoselectivity to a series of trans-substituted derivatives. The method is characterized by its simple operation, commercial availability of all materials, mild reaction conditions and moderate-to-good chemical yields.
The Armenia–Azerbaijan conflict through the prism of the British media and The New York Times, 1988–1994
Authors: Imranli-Lowe Kamala
Published: June 2015

This article applies discourse analysis to examine the coverage of the Armenia–Azerbaijan conflict by the leading British media outlets, such as BBC TV, The Guardian, The Times, The Financial Times and The Independent from February 1988, which is the widely accepted date of the start of the current stage of the conflict, to May 1994, when a ceasefire agreement was signed, and to compare it with the coverage of the conflict by The New York Times. It argues that the coverage of the conflict by the studied British and the US media outlets was influenced by such factors as the sources of information of correspondents, the Cold War, the Iranian Revolution, riots in the UK and the USA, perestroika and glasnost in the Soviet Union, the collapse of the Soviet Union and the new realities it brought. The article contributes to a better understanding of Western media coverage of different conflicts around the world, Western media practices and their impact on Western public opinion.
Archipelago groups
Authors: Conner Gregory , Hojka Wolfram , Meilstrup Mark
Published: June 2015

The classical archipelago is a non-contractible subset of

R

3

\mathbb {R}^3

which is homeomorphic to a disk except at one non-manifold point. Its fundamental group,

A

\mathscr {A}

, is the quotient of the topologist’s product of

Z

\mathbb Z

, the fundamental group of the shrinking wedge of countably many copies of the circle (the Hawaiian earring), modulo the corresponding free product. We show

A

\mathscr {A}

is locally free, not indicable, and has the rationals both as a subgroup and a quotient group. Replacing

Z

\mathbb Z

with arbitrary groups yields the notion of archipelago groups.

Surprisingly, every archipelago of countable groups is isomorphic to either

A

(

Z

)

\mathscr {A}(\mathbb Z)

or

A

(

Z

2

)

\mathscr {A}(\mathbb Z_2)

, the cases where the archipelago is built from circles or projective planes respectively. We conjecture that these two groups are isomorphic and prove that for large enough cardinalities of

G
i

G_i

,

A

(

G
i

)

\mathscr {A}(G_i)

is not isomorphic to either.
Southeast Alaska Sperm Whale Avoidance Project (SEASWAP): a successful collaboration among scientists and industry to study depredation in Alaskan waters
Authors: Straley Janice , O'Connell Victoria , Liddle Joe , Thode Aaron , Wild Lauren , Behnken Linda , Falvey Dan , Lunsford Chris
Published: June 2015

In Alaskan waters, depredation on sablefish longline gear by sperm whales increases harvesting cost, negatively biases stock assessments, and presents a risk of entanglement for whales. The Southeast Alaska Sperm Whale Avoidance Project (SEASWAP), a collaborative effort involving industry, scientists, and managers, since 2003 has undertaken research to evaluate depredation with a goal of recommending measures to reduce interactions. Prior to 2003, little was known about sperm whale distribution and behaviour in the Gulf of Alaska (GOA). Although fishers were reporting increasing interactions, the level of depredation varied with no apparent predictor of occurrence across vessels. Between 2003 and 2007, fishers were provided with fishery logbooks and recorded information on whale behaviour, whale presence and absence, during the set, soak, and haul for 319 sets in the GOA. Data were evaluated for a vessel, area, and seasonal (month) effect in the presence and absence of sperm whales. Using catch per unit effort (cpue) as a metric, in kg/100 hooks, results indicated that depredation depended on both the vessel and the area. More whales associated with vessels from April to August. Sperm whales were also likely to be present when cpue was high, revealing that whales and fishers both knew the most productive fishing areas, but confounding the use of cpue as a metric for depredation. Using a Bayesian mark-recapture analysis and the sightings histories of photo-identified whales, an estimated Nˆ=135 (95% CI 124, 153) sperm whales were associating with vessels in 2014. A spatial model was fitted to 319 longline sets and quantified a 3% loss in cpue, comparable to other global studies on sperm whale depredation. Through all phases of SEASWAP, our understanding of depredation has gained significantly. This successful collaboration should be considered as a model to create partnerships and build collaborations between researchers and fisherpeople encountering marine mammal interactions with fishing gear.
Serum Immunoglobulin A Cross-Strain Blockade of Human Noroviruses
Authors: Lindesmith Lisa C. , Beltramello Martina , Swanstrom Jesica , Jones Taylor A. , Corti Davide , Lanzavecchia Antonio , Baric Ralph S.
Published: June 2015

Background.  Human noroviruses are the leading cause of acute viral gastroenteritis, justifying vaccine development despite a limited understanding of strain immunity. After genogroup I (GI).1 norovirus infection and immunization, blockade antibody titers to multiple virus-like particles (VLPs) increase, suggesting that GI cross-protection may occur.

Methods.  Immunoglobulin (Ig)A was purified from sera collected from GI.1-infected participants, and potential neutralization activity was measured using a surrogate neutralization assay based on antibody blockade of ligand binding. Human and mouse monoclonal antibodies (mAbs) were produced to multiple GI VLPs to characterize GI epitopes.

Results.  Immunoglobulin A purified from day 14 post-GI.1 challenge sera blocked binding of GI.1, GI.3, and GI.4 to carbohydrate ligands. In some subjects, purified IgA preferentially blocked binding of other GI VLPs compared with GI.1, supporting observations that the immune response to GI.1 infection may be influenced by pre-exposure history. For other subjects, IgA equivalently blocked multiple GI VLPs. Only strain-specific mAbs recognized blockade epitopes, whereas strain cross-reactive mAbs recognized nonblockade epitopes.

Conclusions.  These studies are the first to describe a functional role for serum IgA in norovirus immunity and the first to characterize human monoclonal antibodies to GI strains, expanding our understanding of norovirus immunobiology.
Evaluation of Polymerase Chain Reaction (PCR)-Based Methods for Rapid, Accurate Detection and Monitoring of Verticillium dahliae in Woody Hosts by Real-Time PCR
Authors: Aljawasim Baker , Vincelli Paul
Published: June 2015

Verticillium wilt, caused by Verticillium dahliae, is one of the most economically important diseases of woody hosts such as ash (Fraxinus spp.), sugar maple (Acer saccharum), and redbud (Cercis canadensis). The causal agent has a broad host range, including not only woody hosts but also important vegetable and field crops, and it is distributed worldwide. Diagnosis of V. dahliae in infected woody hosts is often based on the occurrence of vascular discoloration and time-consuming isolation. However, not all woody hosts exhibit vascular discoloration, and not all vascular discoloration symptoms are due to infection by V. dahliae. In this study, real-time polymerase chain reaction (PCR)-based assays were evaluated and employed for rapid and accurate detection of V. dahliae in different woody hosts. High-quality DNA was extracted in large quantities from presumptively infected woody hosts by collecting drill-press shavings from sample tissue, bead beating, and extracting using a cetyltrimethylammonium bromide method. Six published primer sets were evaluated against genomic DNA of V. dahliae as well as selected negative controls, and two sets (VertBt-F/VertBt-R and VDS1/VDS2) showed promise for further evaluation using DNA extracts from field samples. The VertBt primers amplified a species-specific 115-bp fragment of the expected size, while the VDS primers amplified the expected specific 540-bp fragment. However, the VertBt primer set exhibited higher sensitivity in detection of V. dahliae even in asymptomatic trees. The PCR-based methods developed here could be used as rapid tools for pathogen detection and monitoring, thus informing plant pathogen management decisions.
Subfamily-Specific Fluorescent Probes for Cysteine Proteases Display Dynamic Protease Activities during Seed Germination
Authors: Lu Haibin , Chandrasekar Balakumaran , Oeljeklaus Julian , Misas-Villamil Johana C. , Wang Zheming , Shindo Takayuki , Bogyo Matthew , Kaiser Markus , van der Hoorn Renier A.L.
Published: June 2015

Cysteine proteases are an important class of enzymes implicated in both developmental and defense-related programmed cell death and other biological processes in plants. Because there are dozens of cysteine proteases that are posttranslationally regulated by processing, environmental conditions, and inhibitors, new methodologies are required to study these pivotal enzymes individually. Here, we introduce fluorescence activity-based probes that specifically target three distinct cysteine protease subfamilies: aleurain-like proteases, cathepsin B-like proteases, and vacuolar processing enzymes. We applied protease activity profiling with these new probes on Arabidopsis (Arabidopsis thaliana) protease knockout lines and agroinfiltrated leaves to identify the probe targets and on other plant species to demonstrate their broad applicability. These probes revealed that most commercially available protease inhibitors target unexpected proteases in plants. When applied on germinating seeds, these probes reveal dynamic activities of aleurain-like proteases, cathepsin B-like proteases, and vacuolar processing enzymes, coinciding with the remobilization of seed storage proteins.
Distinct effect of xenobiotics on the metal-binding properties of protein molecules
Authors: Novikova Natalia , Kovalchuk Mikhail , Stepina Nina , Gaynutdinov Radmir , Chukhrai Elena , Yurieva Eleonora
Published: June 2015

The X-ray standing-wave method was applied to study the elemental composition and molecular organization of ordered protein films of alkaline phosphatase exposed to different xenobiotics (drug compounds, lead). Binding of metal ions from triply distilled water to protein molecules has been experimentally observed. Definite differences in the arrangement of impurity metal ions in the films have been established. The considerable enhancement of protein–metal interactions is attributed to partial rearrangement of the protein native structure, induced by xenobiotics.
Temperature- and energy-dependent phase shifts of resonant multiple-beam X-ray diffraction in germanium crystals
Authors: Liao Po-Yu , Liu Wen-Chung , Cheng Chih-Hao , Chiu Yi-Hua , Kung Ying-Yu , Chang Shih-Lin
Published: June 2015

This paper reports temperature- and energy-dependent phase shifts of resonant multiple-beam X-ray diffraction in germanium crystals, involving forbidden (002) and weak (222) reflections. Phase determination based on multiple-beam diffraction is employed to estimate phase shifts from (002)-based \{(002)(375)(37\overline{3})\} four-beam cases and (222)-based \{ (222)(\overline{5}3\overline{3})\} three-beam cases in the vicinity of the GeKedge for temperatures from 20 K up to 300 K. The forbidden/weak reflections enhance the sensitivity of measuring phases at resonance. At room temperature, the resonance triplet phases reach a maximum of 8° for the four-beam cases and −19° for the three-beam cases. It is found that the peak intensities and triplet phases obtained from the (002) four-beam diffraction are related to thermal motion induced anisotropy and anomalous dispersion, while the (222) three-beam diffraction depends on the aspherical covalent electron distribution and anomalous dispersion. However, the electron–phonon interaction usually affects the forbidden reflections with increasing temperatures and seems to have less effect on the resonance triplet phase shifts measured from the (002) four-beam diffraction. The resonance triplet phase shifts of the (222) three-beam diffractionversustemperature are also small.
Crystal structure ofN,N-dimethyl-2-[(4-methylbenzyl)sulfonyl]ethanamine
Authors: Kennedy Alan R. , Khalaf Abedawn I. , Scott Fraser J. , Suckling Colin J.
Published: June 2015

In the crystal, the title compound, C12H19NO2S, has a disordered structure with two equally populated conformations of the amine fragment. A pair of weak C—H...O intermolecular interactions between the CH2and SO2groups gives a one-dimensional supramolecular structure that propagates through translation along thea-axis direction.
Crystal structure of benzyl 3-oxo-2-oxa-5-azabicyclo[2.2.1]heptane-5-carboxylate
Authors: Krishnamurthy Suvratha , Jalli Venkataprasad , Vagvala Tarun Chand , Moriguchi Tetsuji , Tsuge Akihiko
Published: June 2015

The title compound, C13H13NO4(also known asN-benzyloxycarbonyl-4-hydroxy-L-proline lactone), crystallizes with two molecules in the asymmetric unit. They have slightly different conformations: the fused ring systems almost overlap, but different C—O—C—C torsion angles for the central chains of −155.5 (2) and −178.6 (2)° lead to different twists for the terminal benzene ring. In the crystal, the molecules are linked by C—H...O interactions, generating a three-dimensional network. The absolute structure was established based on an unchanging chiral centre in the synthesis.
Cystal structure ofN-[2-(benzo[d][1,3]dioxol-5-yl)ethyl]-4-methylbenzenesulfonamide
Authors: Huang Ke-Bin , Zhang Gui-Jie
Published: June 2015

In the title compound, C16H17NO4S, the heterocyclic ring is almost planar (r.m.s. deviation = 0.007Å) and the dihedral angle between the benzene rings is 28.18 (10)°. The N—C—C—C torsion angle for the central chain is 62.4 (3)°: overall, the molecule has a Z-shape. In the crystal, inversion dimers linked by pairs of N—H...O hydrogen bonds generateR22(8) loops.
Integration of waqf-Islamic microfinance model for poverty reduction
Authors: Haneef Mohamed Aslam , Pramanik Ataul Huq , Mohammed Mustafa Omar , Bin Amin Md. Fouad , Muhammad Aliyu Dahiru
Published: June 2015

Purpose

– This paper aims to develop an integrated waqf-based Islamic microfinance (IsMF) for poverty reduction in Bangladesh. Microfinance institutions (MFIs) have been constrained by the high cost of funds, high interest rate charges and poor human resource quality of the recipients. Islamic MFIs have recently evolved with the hope of overcoming these financial, ethical and human capital deficiencies faced by the conventional financial institutions. Moreover, a good number of integrated models have been proposed to enhance the role played by Islamic MFIs. Most of these models, however, lack empirical justifications.

Design/methodology/approach

– The research uses survey techniques. A total of 381 respondents were included in the survey. The integrated waqf-based Islamic microfinance model (IWIMM) was earlier on developed using literature and intellectual discussions. There are six constructs presenting the IWIMM, namely, waqf resources, IsMF, takaful, project financing, human resource development and poverty alleviation. In the survey instrument, 45 items represent the six constructs, but only 26 items have been retained after factor analysis. Structural equation modelling has been adopted to examine the relationship among the constructs.

Findings

– The results show that there are significant relationships between IsMF and takaful, waqf resources and human resource development, takaful and human resource development, IsMF and human resource development and, waqf resources and project financing. The results also indicate that poverty alleviation is possible through the integration of these constructs.

Research limitations/implications

– Though the paper has studied conventional and Islamic MFIs in Bangladesh, one of the populated Organisation of Islamic Cooperation (OIC) member countries and also where poverty incidence is high, further studies need to be conducted in other OIC member countries to adopt the model in line with practical and regulatory environment of those countries. Similarly, the study is based on the perception of the respondents, which limits the generalization of the result.

Practical implications

– The paper proposed a model that has the potential of being applied for poverty alleviation programmes in most of the OIC member states.

Originality/value

– The present paper has developed an IWIMM for poverty reduction.
Women chairs in academic medicine: engendering strategic intuition
Authors: Isaac Carol , Griffin Lindsay
Published: June 2015

Purpose

– Because stereotypically masculine behaviors are required for effective leadership, examining female chairs’ leadership in academic medicine can provide insight into the complex ways in which gender impacts on their leadership practices. The paper aims to discuss this issue.

Design/methodology/approach

– The author interviewed three female clinical chairs and compared the findings to interviews with 28 of their faculty. Grounded theory analysis of the subsequent text gathered comprehensive, systematic, and in-depth information about this case of interest at a US top-tier academic medical center.

Findings

– Four of five themes from the faculty were consistent with the chair’s narrative with modifications: Prior Environment (Motivated by Excellence), Tough, Direct, Transparent (Developing Trust), Communal Actions (Creating Diversity of Opinion), and Building Power through Consensus (an “Artful Exercise”) with an additional theme, the Significance (and Insignificance) of a Female Chair. While faculty members were acutely aware of the chair’s gender, the chairs paradoxically vacillated between gender being a “non-issue” and noting that male chairs “don’t do laundry.” All three female chairs in this study independently and explicitly stated that gender was not a barrier, yet intuitively used successful strategies derived from the research literature.

Originality/value

– This study suggests that while their gender was highlighted by faculty, these women dismissed gender as a “non-issue.” The duality of gender for these three female leaders was both minimized and subtly affirmed.
Fiery Spirits in the context of institutional entrepreneurship in Swedish healthcare
Authors: Eriksson Nomie , Ujvari Sandor
Published: June 2015

Purpose

– Clinical governance and leadership concepts can lead to more or less successful implementations of new clinical practice. The purpose of this paper is to examine how Fiery Spirits, as institutional entrepreneurs can, working in a team, implement sustained change in hospital clinical practice.

Design/methodology/approach

– This paper describes two case studies, conducted at two Swedish hospitals over a period of two years, in which changes in clinical practice were implemented. In both cases, key-actors, termed Fiery Spirits, played critical roles in these changes. The authors use a qualitative approach and take an intra-organizational perspective with semi-structured in-depth interviews and document analysis.

Findings

– The new clinical practices were successfully implemented with a considerable influence of the Fiery Spirits who played a pivotal role in the change efforts. The Fiery Spirits persuasively, based on their structural and normative legitimacy and the adoption of learning processes, advocated, and supported change.

Practical implications

– Fiery Spirits, given flexibility and opportunity, can be powerful forces for change outside the trajectory of management-inspired and management-directed change. Team members, when inspired and encouraged by Fiery Spirits, are less resistant to change and more willing to test new clinical practices.

Originality/value

– The paper complements literature on how the Fiery Spirit concept aligns with concepts of clinical governance and leadership and how change can be achieved. Additionally, the findings show the effects of legitimacy and learning processes on change in clinical practice.
Accepting the challenges of social media research
Authors: Weller Katrin
Published: June 2015

Purpose

– The purpose of this paper is to introduce a new viewpoint series, Monitoring the Media: Spotlight on Social Media Research, by providing an overview of the key challenges in social media research and some current initiatives in addressing them.

Design/methodology/approach

– The paper considers publication output from disciplines dealing with social media studies and summarises the key challenges as discussed in the broader research community.

Findings

– The paper suggests that challenges originate both from the interdisciplinary nature of social media research and from the ever-changing research landscape. It concludes that, whilst the community is addressing some challenges, others require more attention.

Originality/value

– The paper summarises key challenges of social media and will be of interest to researchers in different disciplines, as well as a general audience, wanting to learn about how social media data are used for research.
Correlation analysis for comparison of the citation impact of journals, magazines, and conferences in computer science
Authors: Lin Wei-Chao , Tsai Chih-Fong , Ke Shih-Wen
Published: June 2015

Purpose

– In many research areas, there are a variety of different types of academic publications, including journals, magazines and conferences, which provide outlets for researchers to present their findings. Generally speaking, although there are differences in the reviewing criteria and publication processes of different publication types, in the same research area, there is certainly overlap in terms of the problems addressed and the audience for different publication types. Therefore, the research impacts of different publication types in the same research area should be moderately or highly correlated. The paper aims to discuss these issues.

Design/methodology/approach

– To prove this hypothesis, the authors examine the correlation coefficient of citation impacts for different types of publications, in seven research areas of computer science, from 2000 to 2013. In particular, four related citation statistics are examined for each publication type, which are average citations per paper, average citations per year, average annual increase in individual h-index, and h-index.

Findings

– The analysis results show only a partial correlation in terms of several specific citation measures for different publication types in the same research area. Moreover, the level of correlation of the citation impact between different publication types is different, depending on the research area.

Originality/value

– The contribution of this paper is to investigate whether the research impact of different types of publications in the same area is correlated. The findings can help guide researchers and academics choose the most appropriate publication outlets.