bluuebunny/crossref_metadata_2025 huggingface dataset:
Strangers in the Land, Gender, and Immigration Policy
Authors: Moloney Deirdre M.
Published: April 2012

I first read John Higham's book in an immigration history seminar in my first semester of graduate school at the University of Wisconsin. In fact, Higham visited campus that fall to present the Merle Curti lecture, named for his mentor. Higham's influence has remained significant: like many historians of immigration and ethnicity, I have often returned to his book during the course of my own teaching and research, whether on American Catholic history or U.S. immigration policy. My remarks focus on gender issues and immigration policy history inStrangers in the Land.
Polarimetric synthetic aperture radar utilized to track oil spills
Authors: Migliaccio Maurizio , Nunziata Ferdinando , Brown Carl E. , Holt Benjamin , Li Xiaofeng , Pichel William , Shimada Masanobu
Published: April 2012

The continued demand for crude oil and related petroleum products along with the resulting upward spiral of the market price of oil have forced oil exploration and production companies to seek out new reserves farther offshore and in deeper waters. The United States is among the top five nations globally in terms of estimated offshore oil reserves and petroleum production. Yet deepwater drilling to extract these reserves is a major engineering challenge for oil companies. Moreover, such drilling activity also comes with a significant environmental risk, and the extremely high pressures associated with deepwater oil wells mean that the mitigation of accidental releases from a deepwater spill is truly a challenging endeavor.
The R software environment in reproducible geoscientific research
Authors: Pebesma Edzer , Nüst Daniel , Bivand Roger
Published: April 2012

Reproducibility is an important aspect of scientific research, because the credibility of science is at stake when research is not reproducible. Like science, the development of good, reliable scientific software is a social process. A mature and growing community relies on the R software environment for carrying out geoscientific research. Here we describe why people use R and how it helps in communicating and reproducing research.
Monitoring seismic velocity change caused by the 2011 Tohoku‐oki earthquake using ambient noise records
Authors: Minato Shohei , Tsuji Takeshi , Ohmi Shiro , Matsuoka Toshifumi
Published: April 2012

We estimated the changes in seismic velocity in the southern Tohoku district of Japan during the six‐month period centered on the 11 March 2011 Tohoku‐oki earthquake, using scattered waves retrieved by autocorrelation of ambient seismic noise. The estimated velocity decrease after the earthquake, and after two large aftershocks in the study area, was as great as 1.5% in the area nearest to the mainshock. The velocity changes displayed gradual healing. The spatial distribution of the velocity change showed a correlation with both the changes in static strain, derived from GPS records, and the peak particle velocity experienced during the three earthquakes, derived from strong‐motion records. Therefore, our results show that velocity changes possibly contain information from deep in the crust bearing on coseismic stress release, in addition to shallower effects due to strong ground motion.
Forcing, feedbacks and climate sensitivity in CMIP5 coupled atmosphere‐ocean climate models
Authors: Andrews Timothy , Gregory Jonathan M. , Webb Mark J. , Taylor Karl E.
Published: April 2012

We quantify forcing and feedbacks across available CMIP5 coupled atmosphere‐ocean general circulation models (AOGCMs) by analysing simulations forced by an abrupt quadrupling of atmospheric carbon dioxide concentration. This is the first application of the linear forcing‐feedback regression analysis of Gregory et al. (2004) to an ensemble of AOGCMs. The range of equilibrium climate sensitivity is 2.1–4.7 K. Differences in cloud feedbacks continue to be important contributors to this range. Some models show small deviations from a linear dependence of top‐of‐atmosphere radiative fluxes on global surface temperature change. We show that this phenomenon largely arises from shortwave cloud radiative effects over the ocean and is consistent with independent estimates of forcing using fixed sea‐surface temperature methods. We suggest that future research should focus more on understanding transient climate change, including any time‐scale dependence of the forcing and/or feedback, rather than on the equilibrium response to large instantaneous forcing.
Generation of free ubiquitin chains is up-regulated in stress and facilitated by the HECT domain ubiquitin ligases UFD4 and HUL5
Authors: Braten Ori , Shabek Nitzan , Kravtsova-Ivantsiv Yelena , Ciechanover Aaron
Published: April 2012

Polyubiquitin chains serve a variety of physiological roles. Typically the chains are bound covalently to a protein substrate and in many cases target it for degradation by the 26S proteasome. However, several studies have demonstrated the existence of free polyubiquitin chains which are not linked to a specific substrate. Several physiological functions have been attributed to these chains, among them playing a role in signal transduction and serving as storage of ubiquitin for utilization under stress. In the present study, we have established a system for the detection of free ubiquitin chains and monitoring their level under changing conditions. Using this system, we show that UFD4 (ubiquitin fusion degradation 4), a HECT (homologous with E6-AP C-terminus) domain ubiquitin ligase, is involved in free chain generation. We also show that generation of these chains is stimulated in response to a variety of stresses, particularly those caused by DNA damage. However, it appears that the stress-induced synthesis of free chains is catalysed by a different ligase, HUL5 (HECT ubiquitin ligase 5), which is also a HECT domain E3.
Embryonic poly(A)-binding protein (ePAB) phosphorylation is required for Xenopus oocyte maturation
Authors: Friend Kyle , Brook Matthew , Bezirci F. Betül , Sheets Michael D. , Gray Nicola K. , Seli Emre
Published: April 2012

Oocyte maturation and early embryonic development require the cytoplasmic polyadenylation and concomitant translational activation of stored maternal mRNAs. ePAB [embryonic poly(A)-binding protein, also known as ePABP and PABPc1-like] is a multifunctional post-transcriptional regulator that binds to poly(A) tails. In the present study we find that ePAB is a dynamically modified phosphoprotein in Xenopus laevis oocytes and show by mutation that phosphorylation at a four residue cluster is required for oocyte maturation. We further demonstrate that these phosphorylations are critical for cytoplasmic polyadenylation, but not for ePAB's inherent ability to promote translation. Our results provide the first insight into the role of post-translational modifications in regulating PABP protein activity in vivo.
The physics of extreme sensitivity in whispering gallery mode optical biosensors
Authors: Lopez-Yglesias Xerxes , Gamba Jason M. , Flagan Richard C.
Published: April 2012

Whispering gallery mode (WGM) optical biosensors are capable of extraordinarily sensitive specific and nonspecific detection of species suspended in a gas or fluid. Recent experimental results suggest that these devices may attain single-molecule sensitivity to protein solutions in the form of stepwise shifts in their resonance wavelength, λR, but present sensor models predict much smaller steps than were reported. This study examines the physical interaction between a WGM sensor and a molecule adsorbed to its surface, exploring assumptions made in previous efforts to model WGM sensor behavior, and describing computational schemes that model the experiments for which single protein sensitivity was reported. The resulting model is used to simulate sensor performance, within constraints imposed by the limited material property data. On this basis, we conclude that nonlinear optical effects would be needed to attain the reported sensitivity, and that, in the experiments for which extreme sensitivity was reported, a bound protein experiences optical energy fluxes too high for such effects to be ignored.
Effects of high temperature annealing on single crystal ZnO and ZnO devices
Authors: Mtangi W. , Auret F. D. , Diale M. , Meyer W. E. , Chawanda A. , de Meyer H. , Janse van Rensburg P. J. , Nel J. M.
Published: April 2012

We have systematically investigated the effects of high-temperature annealing on ZnO and ZnO devices using current voltage, deep level transient spectroscopy (DLTS) and Laplace DLTS measurements. Current–voltage measurements reveal the decrease in the quality of devices fabricated on the annealed samples, with the high-temperature annealed samples yielding devices with low barrier heights and high reverse currents. DLTS results indicate the presence of three prominent defects in the as-received samples. Annealing the ZnO samples at 300 °C, 500 °C, and 600 °C in Ar results in an increase in reverse leakage current of the Schottky contacts and an introduction of a new broad peak. After 700 °C annealing, the broad peak is no longer present, but a new defect with an activation enthalpy of 0.18 eV is observed. Further annealing of the samples in oxygen after Ar annealing causes an increase in intensity of the broad peak. High-resolution Laplace DLTS has been successfully employed to resolve the closely spaced energy levels.
Dual-etalon frequency-comb cavity ringdown spectrometer
Authors: Chandler David W. , Strecker Kevin E.
Published: April 2012

We have demonstrated a spectroscopic technique for simultaneously obtaining broad spectral bandwidth and high frequency resolution absorption measurements, with 5 μs temporal resolution, continuously for tens of microseconds in an apparatus with no active stabilization. The technique utilizes two passive air-gap etalons to imprint two frequency comb patterns onto a single pulsed light source. The air-gap etalons also serve as cavity ringdown cells increasing the sensitivity of the absorption spectroscopy by increasing the interrogation path length. Here, we demonstrate the operation of the spectrometer utilizing a ∼0.15 cm−1 bandwidth pulsed dye laser and two nearly identical 300 MHz free-spectral range confocal air-gap etalons each with a finesse of ∼1 × 105, to investigate the (1,1,3) overtone of water and the R(7) transition of the O2 \documentclass[12pt]{minimal}\begin{document}$b^1 \Sigma _g ^+ \leftarrow X^3 \Sigma _g^-$\end{document}b1Σg+←X3Σg− (2,0) band with high spectral resolution.
Dust-acoustic waves and stability in the permeating dusty plasma. I. Maxwellian distribution
Authors: Gong Jingyu , Liu Zhipeng , Du Jiulin
Published: April 2012

The dust-acoustic waves and their stability in the permeating dusty plasma with the Maxwellian velocity distribution are investigated. We derive the dust-acoustic wave frequency and instability growth rate in two limiting physical cases that the thermal velocity of the flowing dusty plasma is (a) much larger than, and (b) much smaller than the phase velocity of the waves. We find that the stability of the waves depends strongly on the velocity of the flowing dusty plasma in the permeating dusty plasma. The numerical analyses are made based on the example that a cometary plasma tail is passing through the interplanetary space plasma. We show that, in case (a), the waves are generally unstable for any flowing velocity, but in case (b), the waves become unstable only when the wave number is small and the flowing velocity is large. When the physical conditions are between these two limiting cases, we gain a strong insight into the dependence of the stability criterions on the physical conditions in the permeating dusty plasma.
Spectroscopy and dynamics of barium-doped helium nanodroplets
Authors: Loginov Evgeniy , Drabbels Marcel
Published: April 2012

Excitation spectra up to the ionization threshold are reported for barium atoms located on the surface of helium nanodroplets. For states with low principal quantum number, the resonances are substantially broadened and shifted towards higher energy with respect to the gas phase. This has been attributed to the repulsive interaction of the excited atom with the helium at the Franck-Condon region. In contrast, for states with high principal quantum number the resonances are narrower and shifted towards lower energies. Photoelectron and ZEKE spectroscopy reveal that the redshift results from a lowering of the ionization threshold due to polarization of the helium by the barium ionic core. As a result of the repulsive interaction with the helium, excited barium atoms desorb from the surface of the droplets. Only when excited to the 6s6p 1P1 state, which reveals an attractive interaction with the helium, the atoms remain attached to the droplets.
Near-threshold shape resonance in the photoionization of 2-butyne
Authors: Xu Hong , Jacovella U. , Ruscic B. , Pratt S. T. , Lucchese R. R.
Published: April 2012

Photoelectron velocity map imaging is combined with one- and two-photon ionization to study the near threshold photoionization of the 2-butyne molecule. In this region, the photoabsorption and photoionization cross sections display a very intense broad feature that is assigned to an ℓ = 4, πg shape resonance. The effect of this shape resonance on the vibrational branching ratios and photoelectron angular distributions is explored. Theoretical calculations of the photoionization cross section and photoelectron angular distributions are in good agreement with the experiments. The results for 2-butyne are compared with those of acetylene, propyne, and 1-butyne, none of which show such significant enhancements near threshold, and the differences are rationalized in terms of the symmetries and orbital angular momenta of the highest occupied orbitals and the corresponding shape resonances. Expectations for larger alkynes and alkynyl radicals are also discussed. A preliminary measurement of the ionization energy of the 2-butyne dimer is also presented.
Multi-degree-of-freedom ultrasonic micromotor for guidewire and catheter navigation: The NeuroGlide actuator
Authors: Yun Cheol-Ho , Yeo Leslie Y. , Friend James R. , Yan Bernard
Published: April 2012

A 240-μm diameter ultrasonic micromotor is presented as a potential solution for an especially difficult task in minimally invasive neurosurgery, navigating a guidewire to an injury in the neurovasculature as the first step of surgery. The peak no-load angular velocity and maximum torque were 600 rad/s and 1.6 nN-m, respectively, and we obtained rotation about all three axes. By using a burst drive scheme, open-loop position and speed control were achieved. The construction method and control scheme proposed in this study remove most of the current limitations in minimally invasive, catheter-based actuation, enabling minimally invasive vascular surgery concepts to be pursued for a broad variety of applications.
Photoionization absorption and zero-field spin splitting of acceptor-bound magnetic polaron in p-type Hg1-xMnxTe single crystals
Authors: Zhu Liangqing , Shao Jun , Lin Tie , Lü Xiang , Zhu Junyu , Tang Xiaodong , Chu Junhao
Published: April 2012

Temperature-dependent magnetic (2–300 K), DC Hall (10–300 K), and infrared transmission (11.5–300 K) measurements are performed on a series of p-type Hg1-xMnxTe (0.12 ≤ x ≤ 0.26) single crystals in the spin-glass regime. Photoionization absorption (PIA) of acceptor-bound magnetic polarons (acceptor-BMPs) is observed to evolve with temperature, which is better accounted for by the classical oscillator model than by the quantum defect method. At low temperatures, p-type Hg1−xMnxTe manifests distinct phenomena of paramagnetic enhancement, negative magnetoresistance, and decrease of the effective binding energy and blueshift of the PIA of the acceptor-BMPs with nearly the same degree as temperature declines. A spin-splitting model is proposed, which can well reproduce the experimentally observed zero-field spin splitting of the acceptor-BMP level at low temperatures and the increase of the spin splitting as temperature drops. The results suggest that the acceptor-BMPs in Hg1−xMnxTe may have potential applications in light-driven polaronic memories, tunable far-infrared lasers, and detectors.
Electrical capacitance tomography using an accelerated proximal gradient algorithm
Authors: Xue Qian , Wang Huaxiang , Cui Ziqiang , Yang Chengyi
Published: April 2012

Image reconstruction in electrical capacitance tomography requires a solution of an ill-posed inverse problem. This paper applies an accelerated proximal gradient (APG) singular value thresholding algorithm, which is originally proposed for the matrix completion problem, to image two-phase flow. Aiming to improve the image quality, a nuclear norm-based regularization technique is adopted to treat the ill-posedness of the inverse problem, and a simple updating technique is used to update the sensitivity matrix. Both typical and complicated distributions (e.g., “sun-rise” and cross-shape), have been examined based on a 16-electrode configuration. The results showed that the APG algorithm with updated sensitivity matrix could produce higher quality images when compared to the algorithm based on the typical sensitivity matrix. Both simulation and experiment results indicate that the algorithm developed has been able to achieve good quality reconstructed images with relativity fast computation speed for the cases tested in this paper.
High resolution self-mixing laser rangefinder
Authors: Norgia M. , Magnani A. , Pesatori A.
Published: April 2012

This work describes the development of a novel laser instrument for non-contact absolute distance measurements, working in safety class I. The physical principle of operation is based on the self-mixing effect in a laser diode: the laser diode wavelength is modulated through a change of the supply current, inducing a self-mixing signal. The frequency of the produced fringes depends on the target distance, therefore a particular algorithm is applied, in real-time, to extract the frequency tone of the fringes, even in the case of very low signal-to-noise ratio. The final low-cost instrument is realized with an embedded digital signal processor and works in real-time over diffusive targets, with resolution better than 100 μm for distances up to 2 m.
Colored porous silicon as support for plasmonic nanoparticles
Authors: Lublow M. , Kubala S. , Veyan J.-F. , Chabal Y. J.
Published: April 2012

Colored nanoporous silicon thin films were employed as dielectric spacing layers for the enhancement of localized surface plasmon (LSP) polaritons. Upon formation of Au nanoparticles (Au-NPs) on these layers, a visible color change is observed due to multiple LSP resonance excitations. Far-field effects were assessed by angle-resolved reflectometry. Resonance enhancements, particularly for s-polarized light, account for the observed color change and are discussed in terms of effective medium and Mie scattering theory. Enhancements of the electric field strengths in the near-field and of the absorption in the substrate were deduced from finite difference time domain calculations and exceed considerably those of the non-porous Au-NP/Si interface. First results of improved photoelectrocatalytic hydrogen evolution at these interfaces are discussed. Samples were prepared by varied procedures of metal assisted etching and dry etching with XeF2. Structural and chemical properties were investigated by scanning electron and atomic force microscopy as well as energy dispersive x-ray analysis.
Essential self-adjointness of Wick squares in quasi-free Hadamard representations on curved spacetimes
Authors: Sanders Ko
Published: April 2012

We investigate whether a symmetric, second order Wick polynomial T of a free scalar field, including derivatives, is essentially self-adjoint on the natural (Wightman) domain in a quasi-free (i.e., Fock space) Hadamard representation. Our results apply to arbitrary spacetime dimensions d ≥ 2, but we do restrict our attention to the case where T is smeared with a test-function from a particular class \documentclass[12pt]{minimal}\begin{document}${\cal S}$\end{document}S, namely the class of sums of squares of test-functions. (This class of smearing functions is smaller than the class of all non-negative test-functions – a fact which follows Hilbert's theorem.) Combining techniques from microlocal and functional analysis we prove that T is essentially self-adjoint if it is a Wick square (without derivatives). In the presence of derivatives we prove the weaker result that T is essentially self-adjoint if its compression to the one-particle Hilbert space is essentially self-adjoint. For the latter result, we use Wüst's theorem and an application of Konrady's trick in Fock space. In the presence of derivatives, we also prove that one has some control over the spectral projections of T, by describing it as the strong graph limit of a sequence of essentially self-adjoint operators.
Light scattering at textured back contacts for n-i-p thin-film silicon solar cells
Authors: Bittkau K. , Böttler W. , Ermes M. , Smirnov V. , Finger F.
Published: April 2012

The angular resolved light scattering at textured back contacts for n-i-p thin-film silicon solar cells is investigated experimentally in air. These results are compared to simulations performed by a scalar model for reflection with excellent agreement. Furthermore, light scattering is modeled for the transmission and reflection inside the silicon solar cell. It is found that the reflection at the back contact dominates the light scattering in the absorber layer. From these simulations, a quantity is derived that successfully predicts the external quantum efficiencies of solar cells on different textures.
Hole shape effect induced optical response to permittivity change in palladium sub-wavelength hole arrays upon hydrogen exposure
Authors: Maeda Etsuo , Matsuki Takanori , Yamada Ichiro , Delaunay Jean-Jacques
Published: April 2012

Sensing with sub-wavelength hole arrays is being actively researched as a means to improve detection sensitivity and reduce the size of the developed sensor. One of the approaches to sensing with hole arrays is to use a shift of the main transmittance peak generated by analyte exposure. In this report, the effect of the shape of the holes on the peak shift is investigated with a view to improve further the main transmittance peak shift. Rectangular holes are studied by simulation and experiments with a palladium metallic matrix. Palladium permittivity is varied by exposure to hydrogen and generates main transmittance peak shifts toward longer wavelengths. The simulation results of the propagation constant and electric field distribution revealed that the peak shift is controlled by the short side length of the rectangular holes. The short side of the rectangular holes normalized by the peak wavelength should be below 1/10 for the rectangular holes to achieve their maximum effect.
Magnetoresistive effects in perpendicularly magnetized Tb-Co alloy based thin films and spin valves
Authors: Gottwald M. , Hehn M. , Montaigne F. , Lacour D. , Lengaigne G. , Suire S. , Mangin S.
Published: April 2012

Tb-Co ferrimagnetic alloy thin films and spin valves have been grown to study their magnetoresistance response in various geometries. The studied Tb-Co alloys show strong perpendicular anisotropy and tunable magnetization by several orders of magnitude. Magnetoresistance signals such as giant magnetoresistance (GMR), anisotropic magnetoresistance (AMR), extraordinary Hall effect (EHE), and magnon magnetoresistance (MMR) have been studied. The angular dependence of those magnetoresistive effects is also investigated. Finally we demonstrate that by adjusting the Tb-Co layer composition in a spin valve structure, the sign and the amplitude of the GMR and EHE signal can be tuned.
Vibrational mode frequencies of silica species in SiO2-H2O liquids and glasses from ab initio molecular dynamics
Authors: Spiekermann Georg , Steele-MacInnis Matthew , Schmidt Christian , Jahn Sandro
Published: April 2012

Vibrational spectroscopy techniques are commonly used to probe the atomic-scale structure of silica species in aqueous solution and hydrous silica glasses. However, unequivocal assignment of individual spectroscopic features to specific vibrational modes is challenging. In this contribution, we establish a connection between experimentally observed vibrational bands and ab initio molecular dynamics (MD) of silica species in solution and in hydrous silica glass. Using the mode-projection approach, we decompose the vibrations of silica species into subspectra resulting from several fundamental structural subunits: The SiO4 tetrahedron of symmetry Td, the bridging oxygen (BO) Si-O-Si of symmetry \documentclass[12pt]{minimal}\begin{document}${\rm C}_{2{\textit v}}$\end{document}C2v, the geminal oxygen O-Si-O of symmetry \documentclass[12pt]{minimal}\begin{document}${\rm C}_{2{\textit v}}$\end{document}C2v, the individual Si-OH stretching, and the specific ethane-like symmetric stretching contribution of the H6Si2O7 dimer. This allows us to study relevant vibrations of these subunits in any degree of polymerization, from the Q0 monomer up to the fully polymerized Q4 tetrahedra. Demonstrating the potential of this approach for supplementing the interpretation of experimental spectra, we compare the calculated frequencies to those extracted from experimental Raman spectra of hydrous silica glasses and silica species in aqueous solution. We discuss observed features such as the double-peaked contribution of the Q2 tetrahedral symmetric stretch, the individual Si-OH stretching vibrations, the origin of the experimentally observed band at 970 cm−1 and the ethane-like vibrational contribution of the H6Si2O7 dimer at 870 cm−1.
Origin of white light luminescence from Si+/C+ sequentially implanted and annealed silica
Authors: Zhou X. D. , Ren F. , Xiao X. H. , Xu J. X. , Dai Z. G. , Cai G. X. , Jiang C. Z.
Published: April 2012

The white light luminescence is observed from the silica slides implanted by sequential Si+ and C+ ions or only by C+ ions followed by thermal annealing. In the photoluminescence (PL) spectra, their white emissions cover the whole visible spectral range from 350 to 800 nm. The influence of thermal annealing on the PL of the implanted samples was studied. The microstructural and optical analysis allow us to figure out the origin of the white light emission, which is mainly attributed to the emission of graphite like C clusters although the contributions from the emissions of the Si and SiC nanocrystals are also included. Compared to the white light emission of C+ implanted sample, the white light emission of Si+/C+ implanted sample has higher thermal stability.
Ab initio study of vacancy and self-interstitial properties near single crystal silicon surfaces
Authors: Kamiyama Eiji , Sueoka Koji , Vanhellemont Jan
Published: April 2012

The microscopic model of the Si(001) crystal surface was investigated by first principles calculations to clarify the behavior of intrinsic point defects during crystal growth and thermal annealing. A c(4 × 2) structure model was used to describe the crystal surface in contact with vacuum. The calculations show that a vacancy in the first or second atomic layer has about a 2.0 eV lower formation energy than deeper inside the bulk and that there is a diffusion barrier to penetrate into the deeper crystal region. Furthermore, a vacancy in the first or second atomic layer is stabilized by the fact that Si atoms with dangling bonds attract each other due to ionic and/or covalent bonding. There is, however, no barrier for the diffusion of a vacancy from the first layer to the second one. The tetrahedral (T)-site and dumbbell (DB)-site, in which a Si atom is captured from the surface and forms a self-interstitial, are found as stable sites near the third atomic layer. The T-site has a barrier of 0.48 eV, whereas the DB-site has no barrier for the interstitial to penetrate into the crystal from the vacuum. Self-interstitials in both the T- and DB-sites in the third atomic layer have a 1.7 to 2.8 eV lower formation energy than deeper in the bulk and there is a diffusion barrier to penetrate into the deeper crystal region; 32 sites were found as stable sub-surface vacancy positions, whereas only 8 sites were found as stable self-interstitial positions. Using these results, a mechanism for the elimination of crystal-originated pits by thermal annealing is proposed. It is shown that the microscopic model is consistent with and allows to fine-tune existing macroscopic models that are used to calculate the intrinsic point defects behavior during crystal growth from a melt.
Real-space microscopic electrical imaging of n+-p junction beneath front-side Ag contact of multicrystalline Si solar cells
Authors: Jiang C.-S. , Li Z. G. , Moutinho H. R. , Liang L. , Ionkin A. , Al-Jassim M. M.
Published: April 2012

We investigated the quality of the n+-p diffused junction beneath the front-side Ag contact of multicrystalline Si solar cells by characterizing the uniformities of electrostatic potential and doping concentration across the junction using the atomic force microscopy-based electrical imaging techniques of scanning Kelvin probe force microscopy and scanning capacitance microscopy. We found that Ag screen-printing metallization fired at the over-fire temperature significantly degrades the junction uniformity beneath the Ag contact grid, whereas metallization at the optimal- and under-fire temperatures does not cause degradation. Ag crystallites with widely distributed sizes were found at the Ag-grid/emitter-Si interface of the over-fired cell, which is associated with the junction damage beneath the Ag grid. Large crystallites protrude into Si deeper than the junction depth. However, the junction was not broken down; instead, it was reformed on the entire front of the crystallite/Si interface. We propose a mechanism of junction-quality degradation, based on emitter Si melting at the temperature around the Ag-Si eutectic point during firing, and subsequent re-crystallization with incorporation of Ag and other impurities and with formation of crystallographic defects during quenching. The effect of this junction damage on solar cell performance is discussed.
Effect of quantum well cap layer thickness on the microstructure and performance of InGaN/GaN solar cells
Authors: Hu Yan-Ling , Farrell Robert M. , Neufeld Carl J. , Iza Michael , Cruz Samantha C. , Pfaff Nathan , Simeonov Dobri , Keller Stacia , Nakamura Shuji , DenBaars Steven P. , Mishra Umesh K. , Speck James S.
Published: April 2012

A two-step GaN barrier growth methodology was developed for InxGa1−xN/GaN multiple quantum well solar cells in which a lower temperature GaN cap layer was grown on top of the quantum wells (QWs) and then followed by a higher temperature GaN barrier layer. The performance of the solar cells improved markedly by increasing the low temperature GaN cap layer thickness from 1.5 to 3.0 nm. High-angle annular dark field scanning transmission electron microscopy and atom probe tomography measurements showed that increasing the GaN cap layer thickness improved the uniformity and increased the average indium content of the QWs.
Economies of Empathy: Obama, Neoliberalism, and Social Justice
Authors: Pedwell Carolyn
Published: April 2012

This paper asks how we might theorise the politics of empathy in a context in which visions of social justice premised on empathetic engagement need to be situated within prevailing neoliberal frameworks. Through reading the ambivalent grammar of President Obama's emotional rhetoric, I examine how it resonates in different ways both with feminist and antiracist debates about empathy and social justice and with the neoliberal discourse of the ‘empathy economy’ expressed within popular business literatures. I argue that, in framing empathy as a competency to be developed by individuals alongside imperatives to become more risk-taking and self-enterprising, Obama's rhetoric reveals its centrist neoliberal underpinnings and risks (re)producing social and geopolitical exclusions and hierarchies. Yet, I suggest that seeing the phenomenon of ‘Obama-mania’ as produced not only within discourses of neoliberal governmentality but also through more radical intersections of empathy, hope, and imagination illustrates how empathy might be conceptualised as an affective portal to different spaces and times of social justice.
Differences: Chaos in the History of the Sciences
Authors: Serres Michel
Published: April 2012

In this paper from the book Les origines de la géométrie (The origins of geometry), subtitled tiers livre des fondations (third book of foundations) (Serres, 1993, Flammarion, Paris), I argue that the history of the sciences and, in particular, the history of mathematics cannot be written using the tools and models of traditional historiography. Rather, I claim that there is a need for a science of history that takes seriously what I see as a radical contemporaneity or copresence of the archaic and the contemporary. The model of history that I propose attempts to seek a degree of congruence between a model of time that is not chronological but rather percolating and filtering the ways that the mathematical tradition is reinvented. There exists—or seems to exist—a structural similitude between mathematics itself and the form or model of historiography required to write its history.
Animal welfare - recent developments in the field.
Authors: Algers B.
Published: April 2012

Animal welfare science has engaged in the studies of how mainly farm animals, but to a lesser extent also sport and pet animals and laboratory animals, are affected by various environmental factors. With philosophers engaging in animal welfare it became obvious that animal welfare cannot be properly improved without addressing ethical values. A new trend in animal welfare research is to focus on animal-based measures of welfare, making use of positive emotions as measures of good animal welfare and a multidisciplinary approach to the subject of animal welfare. In order to help risk managers to set appropriate priorities, the European Food Safety Authority (EFSA) has taken on the task of developing a risk assessment methodology for animal welfare. In the last decade, the engagement in animal welfare has led to two international bodies working globally to bring on the subject of animal welfare as one of their areas of responsibility. It can be concluded that animal welfare research has developed from merely studies on changes in behaviour and physiological parameters to also include studies of affective states. Research has become more interdisciplinary and often social sciences are part of such research. Animal welfare has become a factor to consider for legislation and international trade.
Livestock and climate change, challenges and options.
Authors: Henderson B. , Gerber P. , Opio C.
Published: April 2012

This review outlines livestock's major emission pathways and production trends, and explores the challenges and options for livestock in addressing and coping with climate change. Ruminant production is, and will continue to be, the chief source of the livestock sector's greenhouse gas (GHG) emissions, mainly as a result of deforestation, land degradation and enteric fermentation. Livestock productivity improvement is fundamental to mitigation and where it is achieved through the transfer of improved production practices and technologies, it can also deliver important rural livelihood and food security co-benefits in developing countries. Mitigation is also possible by shifting production resources, particularly concentrate feeds, from ruminant to monogastric enterprises, given their higher feed conversion efficiencies and lower emission intensities. However, standard prescriptions for productivity improvements, which are often accompanied by higher concentrations of animals on land, need safeguards to ensure that they do not lead to localized pollution problems and increase disease risks. Further, measures that simultaneously improve productivity and capacity for adaptation to climate change, such as more efficient crop-livestock integration and water management, should be exploited wherever possible. Policy options for unlocking livestock's large mitigation potential are widely known, but their implementation is currently hampered by technical and institutional capacity constraints, and by a lack of political support and global agreement on mitigation. There is a particular need for practicable methods for measurement, reporting and verification of emissions, to improve access to carbon markets, and to facilitate the sector's transition to a low-emission future.
Young people's topography of musical functions: Personal, social and cultural experiences with music across genders and six societies
Authors: Boer Diana , Fischer Ronald , Tekman Hasan Gürkan , Abubakar Amina , Njenga Jane , Zenger Markus
Published: April 2012

How can we understand the uses of music in daily life? Music is a universal phenomenon but with significant interindividual and cultural variability. Listeners’ gender and cultural background may influence how and why music is used in daily life. This paper reports the first investigation of a holistic framework and a new measure of music functions (RESPECT‐music) across genders and six diverse cultural samples (students from Germany, Kenya, Mexico, New Zealand, Philippines, and Turkey). Two dimensions underlie the mental representation of music functions. First, music can be used for contemplation or affective functions. Second, music can serve intrapersonal, social, and sociocultural functions. Results reveal that gender differences occur for affective functions, indicating that female listeners use music more for affective functions, i.e., emotional expression, dancing, and cultural identity. Country differences are moderate for social functions (values, social bonding, dancing) and strongest for sociocultural function (cultural identity, family bonding, political attitudes). Cultural values, such as individualism–collectivism and secularism–traditionalism, can help explain cross‐cultural differences in the uses of music. Listeners from more collectivistic cultures use music more frequently for expressing values and cultural identity. Listeners from more secular and individualistic cultures like to dance more. Listeners from more traditional cultures use music more for expressing values and cultural identity, and they bond more frequently with their families over music. The two dimensions of musical functions seem systematically underpinned by listeners’ gender and cultural background. We discuss the uses of music as behavioral expressions of affective and contemplative as well as personal, social, and sociocultural aspects in terms of affect proneness and cultural values.
Speed of emotional information processing and emotional intelligence
Authors: Dodonova Yulia A. , Dodonov Yury S.
Published: April 2012

The present study aimed to investigate the relationship between the speed of emotional information processing and emotional intelligence (EI). To evaluate individual differences in the speed of emotional information processing, a recognition memory task consisted of two subtests similar in design but differing in the emotionality of the stimuli. The first subtest required judgment about whether an emotional facial expression in the test face was identical to one of the four emotional expressions of the same individual previously presented. The second subtest required deciding whether the test face with a neutral emotional expression was identical to one of the four neutral faces of different individuals previously presented. Mean response latencies were calculated for “Yes” and “No” responses. All latencies were correlated with other measures of processing speed such as discrimination time and time of figure recognition. However, the emotional expression recognition subtest was hypothesized to require the processing of emotional information in addition to that of facial identity. Latencies in this subtest were longer than those in the face recognition subtest. To obtain a measure of the additional processing that was called for by the emotionality of the stimuli, a subtraction method and regression analysis were employed. In both cases, measures calculated for “No” responses were related to ability EI, as assessed via a self‐report questionnaire. According to structural equation modeling, there was a moderately negative association between latent EI and the latency of “No” responses in the subtest with emotional stimuli. These relationships were not observed for “Yes” responses in the same subtest or for responses in the subtest with neutral face stimuli. Although the differences between “Yes” and “No” responses in their associations with EI require further investigation, the results suggest that, in general, individuals with higher EI are also more efficient in the processing of emotional information.
Risk and resilience: The moderating role of social coping for maternal mental health in a setting of political conflict
Authors: Taylor Laura K. , Merrilees Christine E. , Cairns Ed , Shirlow Peter , Goeke‐Morey Marcie , Cummings E. Mark
Published: April 2012

Violence can threaten individual wellbeing and tear at the social fabric of communities. At the same time, suffering can mobilize social coping and mutual support. Thus, the backdrop of political violence increases risk factors and stimulates resilience. The current study examined the moderating role of social coping as reflective of risk and resiliency in Northern Ireland, a setting of protracted conflict. Specifically, structural equation modeling was used to investigate whether social coping protects from or exacerbates the negative impact of sectarian crime and nonsectarian crime on maternal mental health (N = 631). Nonsectarian crime predicted greater psychological distress for mothers in Belfast. Mixed support was found for the buffering and depletion moderation hypotheses; social coping functioned differently for nonsectarian crime and sectarian crime. Greater social coping buffered mothers’ psychological distress from the negative effects of nonsectarian crime, but exacerbated maternal mental health problems when facing sectarian crime. Results suggest that social coping is a complex phenomenon, particularly in settings of protracted political violence. Implications for interventions aimed at alleviating psychological distress by enhancing mothers’ social coping in contexts of intergroup conflict are discussed.
Neutral Loci Reveal Population Structure by Geography, not Ecotype, in Kootenay Lake Kokanee
Authors: Lemay Matthew A. , Russello Michael A.
Published: April 2012

Genetic tools are often used to define stocks for fisheries management, however, traditional approaches using neutral markers may be inadequate for detecting fine-scale structure when populations have recently diverged. Kokanee Oncorhynchus nerka is a freshwater form of sockeye salmon that exhibits divergent reproductive ecotypes. We used a combination of expressed sequence tag (EST)-linked and non-EST-linked microsatellites to investigate kokanee stock structure and ecotype differentiation in Kootenay Lake, British Columbia. Despite being highly informative in other lakes in the province, the EST-linked loci used in this study did not exhibit outlier behavior relative to neutral loci for distinguishing shore-spawning and stream-spawning ecotypes. We found conflicting evidence for differentiation between ecotypes and strong evidence for geographical structure corresponding to the North Arm and West Arm of Kootenay Lake. These results are consistent with previous findings that neutral markers are not sufficient for resolving fine-scale ecotype differentiation in kokanee; additional studies are necessary to investigate the degree to which an outlier-based approach to kokanee fisheries management can be applied at a broader level.

Received September 29, 2011; accepted December 21, 2011
Differential effects of articulatory suppression on cue-switch and task-switch trials in random task cueing with 2:1 mapping
Authors: Saeki Erina , Saito Satoru
Published: April 2012

Recent studies have revealed that verbal representations play an important role in various task-switching situations. This study examined whether verbal representations contribute to the actual switching process using random task cueing with two cues per task. This procedure allowed us to produce a trial in which the cue switched, but the task repeated, thereby separating the cue-switching process from the actual task-switching process. Participants performed colour or shape judgements that were initiated by an arbitrary symbol cue (Experiments 1 and 2) or a kanji cue (Experiment 3) under control, articulatory-suppression, and foot-tapping conditions. In Experiments 1 and 2 with the arbitrary cues, articulatory suppression impaired performance in only the cue-switch condition. In Experiment 3, in which a kanji cue indicated the upcoming task name, articulatory suppression did not have any effects. These results suggest that the involvement of verbal representations in random task cueing is based on the cue-switching process rather than on the task-switching process.
Cell biology of spinocerebellar ataxia
Authors: Orr Harry T.
Published: April 2012

Ataxia is a neurological disorder characterized by loss of control of body movements. Spinocerebellar ataxia (SCA), previously known as autosomal dominant cerebellar ataxia, is a biologically robust group of close to 30 progressive neurodegenerative diseases. Six SCAs, including the more prevalent SCA1, SCA2, SCA3, and SCA6 along with SCA7 and SCA17 are caused by expansion of a CAG repeat that encodes a polyglutamine tract in the affected protein. How the mutated proteins in these polyglutamine SCAs cause disease is highly debated. Recent work suggests that the mutated protein contributes to pathogenesis within the context of its “normal” cellular function. Thus, understanding the cellular function of these proteins could aid in the development of therapeutics.
DNA damage–inducible SUMOylation of HERC2 promotes RNF8 binding via a novel SUMO-binding Zinc finger
Authors: Danielsen Jannie Rendtlew , Povlsen Lou Klitgaard , Villumsen Bine Hare , Streicher Werner , Nilsson Jakob , Wikström Mats , Bekker-Jensen Simon , Mailand Niels
Published: April 2012

Nonproteolytic ubiquitylation of chromatin surrounding deoxyribonucleic acid (DNA) double-strand breaks (DSBs) by the RNF8/RNF168/HERC2 ubiquitin ligases facilitates restoration of genome integrity by licensing chromatin to concentrate genome caretaker proteins near the lesions. In parallel, SUMOylation of so-far elusive upstream DSB regulators is also required for execution of this ubiquitin-dependent chromatin response. We show that HERC2 and RNF168 are novel DNA damage–dependent SUMOylation targets in human cells. In response to DSBs, both HERC2 and RNF168 were specifically modified with SUMO1 at DSB sites in a manner dependent on the SUMO E3 ligase PIAS4. SUMOylation of HERC2 was required for its DSB-induced association with RNF8 and for stabilizing the RNF8–Ubc13 complex. We also demonstrate that the ZZ Zinc finger in HERC2 defined a novel SUMO-specific binding module, which together with its concomitant SUMOylation and T4827 phosphorylation promoted binding to RNF8. Our findings provide novel insight into the regulatory complexity of how ubiquitylation and SUMOylation cooperate to orchestrate protein interactions with DSB repair foci.