bluuebunny/crossref_metadata_2025 huggingface dataset:
Temperature dependent magnetization in Co-base nanowire arrays: Role of crystalline anisotropy
Authors: Vivas L. G. , Vázquez M. , Vega V. , García J. , Rosa W. O. , del Real R. P. , Prida V. M.
Published: February 2012

Co, Co(1−x)Pdx, and Co(1−y)Niy nanowire arrays have been prepared by electrochemical template-assisted growth. Hcp, fcc or both phases are detected in Co nanowires depending on their length (300 nm to 40 μm) and on the content of Pd (0 ≤ x ≤ 0.4) and Ni (0 ≤ y ≤ 0.8). Their magnetic behavior has been studied under longitudinal and perpendicular applied fields. The effective magnetic anisotropy is mostly determined by the balance between the shape and the crystalline terms, the latter depending on the fractional volume of hcp phase with strong perpendicular anisotropy and fcc phase with weaker longitudinal anisotropy. The temperature dependence of remanence and coercivity and the eventual observation of compensation temperature is interpreted as due to the different temperature dependence of shape and hcp crystalline anisotropy. Optimum longitudinal magnetic anisotropy is achieved in low Pd-content CoPd nanowires and in short Co nanowires.
Dip coating with an interaction potential normal to the substrate
Authors: Vannozzi C.
Published: February 2012

Dip coating in the presence of a substrate-liquid interaction potential normal to the substrate, previously theoretically investigated by R. Krechetnikov and G. M. Homsy [Phys. Fluids 17, 038101 (2005)], was revisited. Their solution procedure leads to predictions of the entrained film thickness $h_\infty ^*$h∞* that deviate substantially from the classical Landau-Levich law because of the impossibility to identify meniscus solutions satisfying the proper boundary conditions of zero thickness and zero apparent contact angle on the solid substrate (L-L BC’s). In contrast, in the present analysis, by choosing a different method of integration and requiring the satisfaction of the boundary condition of flat bath for large, but finite, meniscus thickness, we obtain solutions subject to L-L BC's for the same parameter range studied in Krechetnikov and Homsy's paper. Thus, the matching follows a modified Landau-Levich law, where $h_\infty ^*$h∞* is inversely proportional to the meniscus curvature at the substrate. Since the interaction potential changes considerably this curvature, the entrained film significantly thickens for attractive interactions or thins for repulsive ones. Similar results are also found for a potential of the Debye-Hückel form.
Fluid dynamics and mass transport in organic vapor jet printing
Authors: McGraw Gregory J. , Forrest Stephen R.
Published: February 2012

Organic vapor jet printing (OVJP) is a high-resolution mask and solvent-free organic thin film deposition and patterning technique. In this work, we analyze factors that affect the material deposition rate and the dynamics of gas flow through an OVJP print head consisting of an array of micron-sized nozzles. Scaling laws governing carrier gas flow dynamics through a system of microchannels and nozzles are developed. From these laws, we predict the deposition rate and doping ratio of organic material as a function of carrier gas flow. The analysis is applied to an experimental print head, and is compared to results obtained via a more complex, direct simulation Monte Carlo model. The print head is used to grow efficient green phosphorescent organic light emitting diodes having an external quantum efficiency and luminance comparable to analogous devices grown by vacuum thermal evaporation.
Damage property of incompletely spalled aluminum under shock wave loading
Authors: Qi Meilan , Luo Chao , He Hongliang , Wang Yonggang , Fan Duan , Yan Shilin
Published: February 2012

The nucleation, growth, and coalescence of microscopic voids are induced inside ductile metal when it is subjected to dynamic tension, and this eventually results in a catastrophic fracture of the specimen. In the present work, this failure property is studied by using ultrapure aluminum (99.999%) as a representative candidate for the ductile metal and, further, the micro-void growth behavior (or the damage evolution) before the catastrophic fracture has been investigated. Measurements of the free surface velocity profile and statistical analysis of micro-voids were used to determine the spall characteristic and damage evolution behavior of dynamic tensile fracture in ultrapure aluminum. Through comparison of the differences between the incompletely and completely spalled signals, the spall characteristics of ultrapure aluminum from incomplete to complete spall were analyzed. Moreover, an obvious critical characteristic is found on the basis of the association between the maximum damage caused within samples and the product of peak stress and tensile duration. The damage variable slowly increased in a linear manner in the initial stages but changed to nonlinear growth and rapidly approached a fracture state as the damage variable extended beyond the critical value, which is approximately 0.09. A physical explanation for this transition is discussed and implicates micro-void linkage behavior during the dynamic failure.
Sample size effects on the large strain bursts in submicron aluminum pillars
Authors: Wang Zhang-Jie , Li Qing-Jie , Shan Zhi-Wei , Li Ju , Sun Jun , Ma Evan
Published: February 2012

In situ transmission electron microscope compression testing of submicron Al pillars shows two sample size regimes with contrasting behavior underlying the large strain bursts. For small pillars, the bursts originate from explosive and highly correlated dislocation generation, characterized by very high collapse stresses and nearly dislocation-free post-collapse microstructure. For larger pillars, the bursts result from the reconstruction of jammed dislocation configurations, featuring relative low stress levels and retention of dislocation network after bursts.
A femtosecond velocity map imaging study on B-band predissociation in CH3I. II. The $2_0^1$21 and $3_0^1$31 vibronic levels
Authors: Gitzinger G. , Corrales M. E. , Loriot V. , de Nalda R. , Bañares L.
Published: February 2012

Femtosecond time-resolved velocity map imaging experiments are reported on several vibronic levels of the second absorption band (B-band) of CH3I, including vibrational excitation in the ν2 and ν3 modes of the bound 3R1(E) Rydberg state. Specific predissociation lifetimes have been determined for the $2_0^1$201 and $3_0^1$301 vibronic levels from measurements of time-resolved I*(2P1/2) and CH3 fragment images, parent decay, and photoelectron images obtained through both resonant and non-resonant multiphoton ionization. The results are compared with our previously reported predissociation lifetime measurements for the band origin $0_0^0$000 [Gitzinger et al., J. Chem. Phys. 132, 234313 (2010)10.1063/1.3455207]. The result, previously reported in the literature, where vibrational excitation to the C-I stretching mode (ν3) of the CH3I 3R1(E) Rydberg state yields a predissociation lifetime about four times slower than that corresponding to the vibrationless state, whereas predissociation is twice faster if the vibrational excitation is to the umbrella mode (ν2), is confirmed in the present experiments. In addition to the specific vibrational state lifetimes, which were found to be 0.85 ± 0.04 ps and 4.34 ± 0.13 ps for the $2_0^1$201 and $3_0^1$301 vibronic levels, respectively, the time evolution of the fragment anisotropy and the vibrational activity of the CH3 fragment are presented. Additional striking results found in the present work are the evidence of ground state I(2P3/2) fragment production when excitation is produced specifically to the $3_0^1$301 vibronic level, which is attributed to predissociation via the A-band 1Q1 potential energy surface, and the indication of a fast adiabatic photodissociation process through the repulsive A-band 3A1(4E) state, after direct absorption to this state, competing with absorption to the $3_0^1$301 vibronic level of the 3R1(E) Rydberg state of the B-band.
Sizing optimization of a wind pumping plant: Case study in Sfax, Tunisia
Authors: Brahmi Nabiha , Chaabene Maher
Published: February 2012

The effectiveness of wind water pumping plant depends on the available wind potential in the region and on the plant components sizing. This paper presents an algorithm for wind potential assessment based on the widely used Weibull distribution. As many methods are adopted to determine Weibull parameters, an improvement version based on the selection of the most accurate method and the establishment of a huge database using an artificial neural network (ANN) is proposed. Since the site wind performance is evaluated, the wind generator blades surface is computed on the basis of the variation limits of the monthly wind potential and the well height of rise. The sizing principal considers the calculation of the gravity centre of the general function of surface. Results are illustrated using meteorological database provided by the National Institute of Meteorology (INM) corresponding to Sfax, Tunisia. Obtained results confirm that the modified maximum likelihood method (MMLM) is the most accurate one as it provides a monthly error between -11.6% and 2.3%. Hence, a typical pumping plant, with monthly water need of 15  m3month located in Sfax, Tunisia, requires 37  m2 as optimum blades surface.
Exploratory test of utility of magnetic insulation for electrostatic accelerators
Authors: Grisham L. R. , von Halle A. , Carpe A. F. , Rossi Guy , Gilton K. R. , McBride E. D. , Gilson E. P. , Stepanov A. , Stevenson T. N.
Published: February 2012

A recent paper [L. R. Grisham, Phys. Plasmas 16, 043111 (2009)] proposed that a magnetic field which enveloped each of the electrodes in an electrostatic accelerator, along with their support structures, might suppress field emission of electrons and thus allows a higher electric field gradient to be applied between accelerator stages without the onset of vacuum electrical breakdown. Such a magnetic field configuration might be produced by flowing a substantial electric current through each accelerator grid and its support from high current low voltage supplies floated at each accelerator grid potential. This experimental note reports a preliminary exploratory test of whether this magnetic insulation approach might be of benefit at a modest magnetic field strength which could be suitable for practical accelerator applications. This experiment did not find evidence for an increase of the electrostatic potential gradient which could be sustained across a vacuum gap when the cathodic (electron-emitting) electrode was enveloped in a magnetic field of about 240 G. This note discusses a number of possible explanations for this observation as well as the inherent limitations of the experiment.
Influence of the magnetization damping on dynamic hysteresis loops in single domain particles
Authors: Landi Gabriel T.
Published: February 2012

This article reports on the influence of the magnetization damping on dynamic hysteresis loops in single-domain particles with uniaxial anisotropy. The approach is based on the Néel–Brown theory and the hierarchy of differential recurrence relations, which follow from averaging over the realizations of the stochastic Landau–Lifshitz equation. A new method of solution is proposed, where the resulting system of differential equations is solved directly using optimized algorithms to explore its sparsity. All parameters involved in uniaxial systems are treated in detail, with particular attention given to the frequency dependence. It is shown that in the ferromagnetic resonance region, novel phenomena are observed for even moderately low values of the damping. The hysteresis loops assume remarkably unusual shapes, which are also followed by a pronounced reduction of their heights. Also demonstrated is that these features remain for randomly oriented ensembles and, moreover, are approximately independent of temperature and particle size.
Excluded volume effects in macromolecular forces and ion-interface interactions
Authors: Buyukdagli Sahin , Ala-Nissila T.
Published: February 2012

A charged Yukawa liquid confined in a slit nanopore is studied in order to understand excluded volume effects in the interaction force between the pore walls. A previously developed self-consistent scheme [S. Buyukdagli, C. V. Achim, and T. Ala-Nissila, J. Stat. Mech. 2011, P05033] and a new simpler variational procedure that self-consistently couple image forces, surface charge induced electric field, and pore modified core interactions are used to this aim. For neutral pores, it is shown that with increasing pore size, the theory predicts a transition of the interplate pressure from an attractive to a strongly repulsive regime associated with an ionic packing state, an effect observed in previous Monte Carlo simulations for hard core charges. We also establish the mean-field theory of the model and show that for dielectrically homogeneous pores, the mean-field regime of the interaction between the walls corresponds to large pores of size d > 4 Å. The role of the range of core interactions in the ionic rejection and interplate pressure is thoroughly analyzed. We show that the physics of the system can be split into two screening regimes. The ionic packing effect takes place in the regime of moderately screened core interactions characterized with the bare screening parameter of the Yukawa potential b ≲ 3/ℓB, where ℓB is the Bjerrum length. In the second regime of strongly screened core interactions b ≳ 3/ℓB, solvation forces associated with these interactions positively contribute to the ionic rejection driven by electrostatic forces and enhance the magnitude of the attractive pressure. For weakly charged pores without a dielectric discontinuity, core interactions make a net repulsive contribution to the interplate force and also result in oscillatory pressure curves, whereas for intermediate surface charges, these interactions exclusively strengthen the external pressure, thereby reducing the magnitude of the net repulsive interplate force. The pronounced dependence of the interplate pressure and ionic partition coefficients on the magnitude and the range of core interactions indicates excluded volume effects as an important ion specificity and a non-negligible ingredient for the stability of macromolecules in electrolyte solutions.
Microscopic probing of the size dependence in hydrophobic solvation
Authors: Huang Ningdong , Schlesinger Daniel , Nordlund Dennis , Huang Congcong , Tyliszczak Tolek , Weiss Thomas M. , Acremann Yves , Pettersson Lars G. M. , Nilsson Anders
Published: February 2012

We report small angle x-ray scattering data demonstrating the direct experimental microscopic observation of the small-to-large crossover behavior of hydrophobic effects in hydrophobic solvation. By increasing the side chain length of amphiphilic tetraalkyl-ammonium (CnH2n+1)4N+ (R4N+) cations in aqueous solution we observe diffraction peaks indicating association between cations at a solute size between 4.4 and 5 Å, which show temperature dependence dominated by hydrophobic attraction. Using O K-edge x-ray absorption we show that small solutes affect hydrogen bonding in water similar to a temperature decrease, while large solutes affect water similar to a temperature increase. Molecular dynamics simulations support, and provide further insight into, the origin of the experimental observations.
Kelvin probe microscopic visualization of charge storage at polystyrene interfaces with pentacene and gold
Authors: Dawidczyk T. J. , Johns G. L. , Ozgun R. , Alley O. , Andreou A. G. , Markovic N. , Katz H. E.
Published: February 2012

Charge carriers trapped in polystyrene (PS) were investigated with Kelvin probe microscopy (KPM) and thermally stimulated discharge current (TSDC). Lateral heterojunctions of pentacene/PS were scanned using KPM, effectively observing polarization along a side view of a lateral nonvolatile organic field-effect transistor dielectric interface. TSDC was used to observe charge migration out of PS films and to estimate the trap energy level inside the PS, using the initial rise method.
Rotational dynamics of benzene and water in an ionic liquid explored via molecular dynamics simulations and NMR T1 measurements
Authors: Yasaka Yoshiro , Klein Michael L. , Nakahara Masaru , Matubayasi Nobuyuki
Published: February 2012

The rotational dynamics of benzene and water in the ionic liquid (IL) 1-butyl-3-methylimidazolium chloride are studied using molecular dynamics (MD) simulation and NMR T1 measurements. MD trajectories based on an effective potential are used to calculate the 2H NMR relaxation time, T1 via Fourier transform of the relevant rotational time correlation function, C2R(t). To compensate for the lack of polarization in the standard fixed-charge modeling of the IL, an effective ionic charge, which is smaller than the elementary charge is employed. The simulation results are in closest agreement with NMR experiments with respect to the temperature and Larmor frequency dependencies of T1 when an effective charge of ±0.5e is used for the anion and the cation, respectively. The computed C2R(t) of both solutes shows a bi-modal nature, comprised of an initial non-diffusive ps relaxation plus a long-time ns tail extending to the diffusive regime. Due to the latter component, the solute dynamics is not under the motional narrowing condition with respect to the prevalent Larmor frequency. It is shown that the diffusive tail of the C2R(t) is most important to understand frequency and temperature dependencies of T1 in ILs. On the other hand, the effect of the initial ps relaxation is an increase of T1 by a constant factor. This is equivalent to an “effective” reduction of the quadrupolar coupling constant (QCC). Thus, in the NMR T1 analysis, the rotational time correlation function can be modeled analytically in the form of aexp (−t/τ) (Lipari-Szabo model), where the constant a, the Lipari-Szabo factor, contains the integrated contribution of the short-time relaxation and τ represents the relaxation time of the exponential (diffusive) tail. The Debye model is a special case of the Lipari-Szabo model with a = 1, and turns out to be inappropriate to represent benzene and water dynamics in ILs since a is as small as 0.1. The use of the Debye model would result in an underestimation of the QCC by a factor of 2–3 as a compensation for the neglect of the Lipari-Szabo factor.
Vibrational properties of alkyl monolayers on Si(111) surfaces: Predictions from ab-initio calculations
Authors: Li Yan , Galli Giulia
Published: February 2012

Vibrational properties of Si(111) surfaces terminated by different functional groups have been investigated using density functional theory (DFT). The variations in methyl-related frequencies in different chemical environments, e.g., in methane, methylsilane and ethylsilane, and the methyl- and ethyl-terminated Si(111) surfaces are well predicted by DFT within the local density approximation. In particular, DFT calculations provide useful information on trends and mode assignments in cases where the surface coverage and morphology are not well established experimentally, e.g., in the case of the ethyl-terminated Si(111) surface. Influences of DFT exchange-correlation functionals and anharmonic effects on computed vibrational frequencies are discussed.
Role of aluminum as an oxygen-scavenger in zirconium based bulk metallic glasses
Authors: Heinrich Jochen , Busch Ralf , Müller Frank , Grandthyll Samuel , Hüfner Stefan
Published: February 2012

In order to investigate a way to diminish the impact of oxygen onto the critical cooling rate of Zr-based alloys, the bonding chemistry of the elements in Zr-Cu-Ni-Al-Nb-Si bulk metallic glasses with different oxygen contents is studied by x-ray photoelectron spectroscopy. Complementary undercooling experiments lead to continuous-cooling-transformation diagrams for the studied alloys. The experimental results demonstrate that Al not only acts as a scavenger for both absorbed and intrinsic oxygen but the dissolution of its oxide on atomic length scales refrains from heterogeneous nucleation. The combined effect is an enhancement of oxygen tolerance in the investigated alloy.
Structural dependent ultrafast electron-phonon coupling in multiferroic BiFeO3 films
Authors: Jin Zuanming , Xu Yue , Zhang Zhengbing , Li Gaofang , Lin Xian , Ma Guohong , Cheng Zhenxiang , Wang Xiaolin
Published: February 2012

The electronic energy relaxation of polycrystalline BiFeO3 films is studied using ultrafast pump-probe spectroscopy. After photo-excitation with femtosecond laser pulses, the relaxation of hot electrons is identified to decay with two different characteristic times. The fast process is attributed to scattering of electrons with lattice-vibration modes, and the slow one is corresponding to the spin-lattice thermalization. The electron-phonon coupling is characterized by the second moment of the Eliashberg function, λ〈ω2〉. Due to the structural strain and symmetry breaking, the electron-phonon interaction strength of tetragonal BiFeO3 films is larger than that of rhombohedral counterparts.
Fabrication of high-performance fully depleted silicon-on-insulator based dual-gate ion-sensitive field-effect transistor beyond the Nernstian limit
Authors: Jang Hyun-June , Cho Won-Ju
Published: February 2012

High-performance dual-gate (DG) ion-sensitive field-effect transistors (ISFETs) beyond the Nernstian limit of 59 mV/pH were realized using the fully depleted (FD) silicon-on-insulator (SOI) substrate. The FD SOI-based DG ISFET exhibited a significantly enhanced pH sensitivity of 379.2 mV/pH for DG operation amplified by capacitive coupling, while it exhibited a relatively poor sensitivity of 47.9 mV/pH for single-gate (SG) operation. Meanwhile, the non-ideal effects for long-term use slightly increased by the DG operation compared to the SG operation. Therefore, the FD SOI-based DG ISFETs compatible with the complementary metal-oxide-semiconductor process are considered to be very promising bio-chemical sensors.
Profile of the liquid film wetting a channel
Authors: Emile J. , Casanova F. , Tabuteau H. , Emile O.
Published: February 2012

We have developed a simple optical technique to investigate the characteristics of liquid films wetting solid surfaces. To validate this technique, we have studied the wetting film that separates a train of lamellas moving through a channel. Total reflection of the laser beam on the wetting film/air interface is used to extract the profile and the thickness of the wetting film. For quasistatic movement of lamellas, we show that the thickness is well described by a capillary number power law.
Poly-(3-hexylthiophene)/[6,6]-phenyl-C61-butyric-acid-methyl-ester bilayer deposition by matrix-assisted pulsed laser evaporation for organic photovoltaic applications
Authors: Caricato A. P. , Cesaria M. , Gigli G. , Loiudice A. , Luches A. , Martino M. , Resta V. , Rizzo A. , Taurino A.
Published: February 2012

A poly-(3-hexylthiophene) (P3HT)/[6,6]-phenyl-C61-butyric-acid-methyl-ester (PCBM) bilayer structure has been realized by single step matrix-assisted pulsed laser evaporation (ss-MAPLE) technique using the same solvent for both the polymers under vacuum conditions. Our ss-MAPLE procedure allows the fabrication of polymeric multilayer device stacks, which are very difficult to realize with the conventional solvent assisted deposition methods. A proof of concept bilayer P3HT/PCBM solar cell based on ss-MAPLE deposition has been realized and characterized. This demonstration qualifies ss-MAPLE as a general and alternative technique for the implementation of polymeric materials in hetero-structure device technology.
Rotating turkeys and self-commutating artificial muscle motors
Authors: O’Brien Benjamin M. , McKay Thomas G. , Gisby Todd A. , Anderson Iain A.
Published: February 2012

Electrostatic motors—first used by Benjamin Franklin to rotisserie a turkey—are making a comeback in the form of high energy density dielectric elastomer artificial muscles. We present a self-commutated artificial muscle motor that uses dielectric elastomer switches in the place of bulky external electronics. The motor simply requires a DC input voltage to rotate a shaft (0.73 Nm/kg, 0.24 Hz) and is a step away from hard metallic electromagnetic motors towards a soft, light, and printable future.
Experimental realization of superconducting quantum interference devices with topological insulator junctions
Authors: Veldhorst M. , Molenaar C. G. , Wang X. L. , Hilgenkamp H. , Brinkman A.
Published: February 2012

We demonstrate topological insulator (Bi2Te3) dc SQUIDs, based on superconducting Nb leads coupled to nano-fabricated Nb-Bi2Te3-Nb Josephson junctions. The high reproducibility and controllability of the fabrication process allow the creation of dc SQUIDs with parameters that are in agreement with design values. Clear critical current modulation of both the junctions and the SQUID with applied magnetic fields have been observed. We show that the SQUIDs have a periodicity in the voltage-flux characteristic of Φ0 of relevance to the ongoing pursuit of realizing interferometers for the detection of Majorana fermions in superconductor—topological insulator structures.
Improved performance of multilayer InAs/GaAs quantum-dot solar cells using a high-growth-temperature GaAs spacer layer
Authors: Tutu F. K. , Sellers I. R. , Peinado M. G. , Pastore C. E. , Willis S. M. , Watt A. R. , Wang T. , Liu H. Y.
Published: February 2012

The use of high-growth-temperature GaAs spacer layers is demonstrated to significantly enhance the performance of multilayer InAs/GaAs quantum-dot solar cells. Threading dislocations are observed for a 30-layer quantum-dot structure with GaAs spacer layers grown at low temperature (510 °C). The formation of threading dislocations is suppressed by growing the GaAs spacer layer at high temperature (580 °C), leading to enhanced quantum-dot optical and structural characteristics. Incorporation of the high-growth-temperature GaAs spacer layers into a 30-layer InAs/GaAs quantum-dot solar cell results in a dramatic increase in the short-circuit current compared to the one without the high-growth-temperature spacer layers and an increase in the short-circuit current compared to the reference GaAs solar cell.
Tip-plasmon mediated molecular electroluminescence on the highly oriented pyrolytic graphite substrate
Authors: Zhang C. , Zhang R. , Jiang S. , Zhang L. , Gao H. Y. , Zhang X. L. , Chen L. G. , Liao Y. , Dong Z. C.
Published: February 2012

Well-defined molecular fluorescence is realized by tunneling electron excitations from porphyrins on highly oriented pyrolytic graphite that is non-plasmonic in the visible spectral range. The occurrence of molecular electroluminescence is found to rely critically on the plasmonic emitting state of scanning tunneling microscope tip that is pre-examined on silver. These observations, together with the selective enhancement of molecular emission bands by energy-matching tip plasmons, suggest that the plasmonic field is indispensable for the generation of molecular electroluminescence, and the tip plasmon alone is sufficient in achieving this. Excitation of molecules directly by electrons is inefficient to produce light.
The role of Mg interface layer in MgO magnetic tunnel junctions with CoFe and CoFeB electrodes
Authors: Yang Hyunsoo , Yang See-Hun , Parkin Stuart
Published: February 2012

The tunneling spin polarization (TSP) is directly measured from reactively sputter deposited crystalline MgO tunnel barriers with various CoFe(B) compositions using superconducting tunneling spectroscopy. We find that the Mg interface layer thickness dependence of TSP values for CoFeB/Mg/MgO junctions is substantially different from those for CoFe/Mg/MgO especially in the pre-annealed samples due to the formation of boron oxide at the CoFeB/MgO interface. Annealing depletes boron at the interface thus requiring a finite Mg interface layer to prevent CoFeOx formation at the CoFeB/MgO interface so that the TSP values can be optimized by controlling Mg thickness.
Association of common genetic variants in GPCPD1 with scaling of visual cortical surface area in humans
Authors: Bakken Trygve E. , Roddey J. Cooper , Djurovic Srdjan , Akshoomoff Natacha , Amaral David G. , Bloss Cinnamon S. , Casey B. J. , Chang Linda , Ernst Thomas M. , Gruen Jeffrey R. , Jernigan Terry L. , Kaufmann Walter E. , Kenet Tal , Kennedy David N. , Kuperman Joshua M. , Murray Sarah S. , Sowell Elizabeth R. , Rimol Lars M. , Mattingsdal Morten , Melle Ingrid , Agartz Ingrid , Andreassen Ole A. , Schork Nicholas J. , Dale Anders M. ,   for the Alzheimer's Disease Neuroimaging Initiative,   Pediatric Imaging, Neurocognition, and Genetics Study
Published: February 2012

Visual cortical surface area varies two- to threefold between human individuals, is highly heritable, and has been correlated with visual acuity and visual perception. However, it is still largely unknown what specific genetic and environmental factors contribute to normal variation in the area of visual cortex. To identify SNPs associated with the proportional surface area of visual cortex, we performed a genome-wide association study followed by replication in two independent cohorts. We identified one SNP (rs6116869) that replicated in both cohorts and had genome-wide significant association (
P
combined
= 3.2 × 10
−8
). Furthermore, a metaanalysis of imputed SNPs in this genomic region identified a more significantly associated SNP (rs238295;
P
= 6.5 × 10
−9
) that was in strong linkage disequilibrium with rs6116869. These SNPs are located within 4 kb of the 5′ UTR of
GPCPD1
, glycerophosphocholine phosphodiesterase GDE1 homolog (
Saccharomyces cerevisiae
), which in humans, is more highly expressed in occipital cortex compared with the remainder of cortex than 99.9% of genes genome-wide. Based on these findings, we conclude that this common genetic variation contributes to the proportional area of human visual cortex. We suggest that identifying genes that contribute to normal cortical architecture provides a first step to understanding genetic mechanisms that underlie visual perception.
Long-term perspective on wildfires in the western USA
Authors: Marlon Jennifer R. , Bartlein Patrick J. , Gavin Daniel G. , Long Colin J. , Anderson R. Scott , Briles Christy E. , Brown Kendrick J. , Colombaroli Daniele , Hallett Douglas J. , Power Mitchell J. , Scharf Elizabeth A. , Walsh Megan K.
Published: February 2012

Understanding the causes and consequences of wildfires in forests of the western United States requires integrated information about fire, climate changes, and human activity on multiple temporal scales. We use sedimentary charcoal accumulation rates to construct long-term variations in fire during the past 3,000 y in the American West and compare this record to independent fire-history data from historical records and fire scars. There has been a slight decline in burning over the past 3,000 y, with the lowest levels attained during the 20th century and during the Little Ice Age (LIA, ca. 1400–1700 CE [Common Era]). Prominent peaks in forest fires occurred during the Medieval Climate Anomaly (ca. 950–1250 CE) and during the 1800s. Analysis of climate reconstructions beginning from 500 CE and population data show that temperature and drought predict changes in biomass burning up to the late 1800s CE. Since the late 1800s , human activities and the ecological effects of recent high fire activity caused a large, abrupt decline in burning similar to the LIA fire decline. Consequently, there is now a forest “fire deficit” in the western United States attributable to the combined effects of human activities, ecological, and climate changes. Large fires in the late 20th and 21st century fires have begun to address the fire deficit, but it is continuing to grow.
Fusion protein Isl1–Lhx3 specifies motor neuron fate by inducing motor neuron genes and concomitantly suppressing the interneuron programs
Authors: Lee Seunghee , Cuvillier James M. , Lee Bora , Shen Rongkun , Lee Jae W. , Lee Soo-Kyung
Published: February 2012

Combinatorial transcription codes generate the myriad of cell types during development and thus likely provide crucial insights into directed differentiation of stem cells to a specific cell type. The LIM complex composed of Isl1 and Lhx3 directs the specification of spinal motor neurons (MNs) in embryos. Here, we report that Isl1–Lhx3, a LIM-complex mimicking fusion, induces a signature of MN transcriptome and concomitantly suppresses interneuron differentiation programs, thereby serving as a potent and specific inducer of MNs in stem cells. We show that an equimolar ratio of Isl1 and Lhx3 and the LIM domain of Lhx3 are crucial for generating MNs without up-regulating interneuron genes. These led us to design Isl1–Lhx3, which maintains the desirable 1:1 ratio of Isl1 and Lhx3 and the LIM domain of Lhx3. Isl1–Lhx3 drives MN differentiation with high specificity and efficiency in the spinal cord and embryonic stem cells, bypassing the need for sonic hedgehog (Shh). RNA-seq analysis revealed that Isl1–Lhx3 induces the expression of a battery of MN genes that control various functional aspects of MNs, while suppressing key interneuron genes. Our studies uncover a highly efficient method for directed MN generation and MN gene networks. Our results also demonstrate a general strategy of using embryonic transcription complexes for producing specific cell types from stem cells.
Basolateral sorting of the coxsackie and adenovirus receptor through interaction of a canonical YXXΦ motif with the clathrin adaptors AP-1A and AP-1B
Authors: Carvajal-Gonzalez Jose Maria , Gravotta Diego , Mattera Rafael , Diaz Fernando , Perez Bay Andres , Roman Angel C. , Schreiner Ryan P. , Thuenauer Roland , Bonifacino Juan S. , Rodriguez-Boulan Enrique
Published: February 2012

The coxsackie and adenovirus receptor (CAR) plays key roles in epithelial barrier function at the tight junction, a localization guided in part by a tyrosine-based basolateral sorting signal,
318
YNQV
321
. Sorting motifs of this type are known to route surface receptors into clathrin-mediated endocytosis through interaction with the medium subunit (μ2) of the clathrin adaptor AP-2, but how they guide new and recycling membrane proteins basolaterally is unknown. Here, we show that YNQV functions as a canonical YxxΦ motif, with both Y318 and V321 required for the correct basolateral localization and biosynthetic sorting of CAR, and for interaction with a highly conserved pocket in the medium subunits (μ1A and μ1B) of the clathrin adaptors AP-1A and AP-1B. Knock-down experiments demonstrate that AP-1A plays a role in the biosynthetic sorting of CAR, complementary to the role of AP-1B in basolateral recycling of this receptor. Our study illustrates how two clathrin adaptors direct basolateral trafficking of a plasma membrane protein through interaction with a canonical YxxΦ motif.
Singular agreement in there-existentials
Authors: Collins Peter
Published: February 2012

The phenomenon of “singular agreement” (“SA”) in there-existentials — the combination of a plural post-verbal notional subject and a singular verb — has been the subject of a number of studies which have confirmed its covariation with a range of social, stylistic and grammatical factors. Whereas the focus of most such studies has been on the relative influence of these factors, that of the present study is on the nature and frequency of SA across (a selection of eight) World Englishes. Beginning with the assumption, for which there is indirect evidence in the literature, that SA is on the rise in contemporary English, an attempt is made to relate the degree of advancement of the eight varieties to their evolutionary status and characteristic style orientations.
Formulating professional identity
Authors: McKenzie Kevin
Published: February 2012

Recent scholarly and practitioner research on the work of non-governmental organizations (NGOs) has been concerned with questions about the moral legitimacy of humanitarian aid in settings of armed conflict. At issue is the extent to which NGO activities are said to affect the conduct and outcome of warfare, thereby potentially implicating humanitarian aid in the partisan interests which it has traditionally eschewed as a condition of its legitimacy. This paper explores how such issues are taken up in the explanations offered by humanitarian aid operatives in descriptions of the work they carry out in settings of armed conflict. Drawing on a corpus of conversational material recorded in open-ended interviews with representatives of various NGOs that operate in Israel and the Occupied Palestinian Territories (OPT), I examine how speakers work to make themselves accountable to demands for sympathetic affiliation with the losing (or vanquished) parties in the Palestinian-Israeli conflict while maintaining a non-aligned stance relative to the partisan considerations that animate that conflict’s conduct. Both in first-hand narrative accounts of personal transformation and in descriptions of contrastive examples where professional colleagues are said to maintain a too-sympathetic affiliation with the partisan concerns of the Palestinian population whose needs they service, speakers work to provide for the legitimacy of their professional activities in the context of otherwise conflicting demands for moral accountability.
Improving the Learning Process for Both Instructor and Student Using Assessments
Authors: Lauer Thomas E
Published: February 2012

The objective of this article is to describe the theory and types of commonly used assessments and how they relate to course objectives and the learning process in higher education. Using a fisheries course example, I argue that quality assessment techniques occur continuously, are aimed at both instructor and student, are not always used to assign grades, and improve the quality of instruction in the classroom. Properly used, assessments can transform institutions of higher education from a place where instruction is given to one where learning takes place.
Psychopathy and Institutional Misbehavior Among Incarcerated Sex Offenders: A Comparison of the Psychopathy Checklist-Revised and the Personality Assessment Inventory
Authors: Edens JohnF. , Buffington-Vollum JacquelineK. , Colwell KevinW. , Johnson DarrylW. , Johnson JudyK.
Published: February 2012

The present study compared the utility of two measures of psychopathic traits, the Antisocial Features scale of the Personality Assessment Inventory (Morey, 1991) and the Psychopathy Checklist-Revised (Hare, 1991), to postdict serious institutional misbehavior among incarcerated sex offenders. Archival disciplinary infraction data for 92 offenders were coded as major acts of physical aggression, major acts of verbal aggression/ defiance, or non-aggressive major offenses. Receiver Operating Characteristic (ROC) analyses indicated that ANT performed comparably to the PCL-R in terms of predicting the occurrence of these infractions during the prior two years, although there was a trend for PCL-R scores to be associated somewhat more strongly with physically aggressive offenses. Regression analyses indicated that each measure accounted for unique variance in the criterion variables, suggesting that both may evidence incremental validity in terms of their relation to disciplinary infractions.
Asperger's Syndrome in Forensic Settings
Authors: Murrie DanielC. , Warren JanetI. , Kristiansson Marianne , Dietz ParkE.
Published: February 2012

Researchers and clinicians have devoted increasing attention to Asperger's syndrome during the past two decades. Although Asperger's syndrome is a developmental disorder, professionals in a variety of settings have begun to consider the diagnosis among adults who manifest social and communication abnormalities. Case studies (e.g., Baron-Cohen, 1988; Kohn et al., 1998) and prevalence research (Scragg & Shah, 1994) from forensic settings indicate that a small subset of Asperger's syndrome patients come into contact with the legal system due to their social impairments and idiosyncratic interests. We provide case histories of individuals with Asperger's syndrome encountered in forensic contexts and discuss the implications of this disorder for forensic clinicians. Our six cases were notable for certain commonalties, including deficient empathy. The cases also revealed ways in which Asperger's patients tend to differ from most individuals in forensic settings.
Aggressive and Antisocial Girls: Research Update and Challenges
Authors: Odgers CandiceL. , Moretti MarleneM.
Published: February 2012

There is a growing recognition that a significant number of young women engage in highly aggressive and antisocial behaviors. This acknowledgement has created demands on both policy and program development. The response to these demands, however, has been delayed due to the fact that we still know relatively little about aggressive and antisocial behavior in girls. In this article, we briefly review trends in the rates of aggressive and antisocial acts among female youth, address the issue of gender specific forms of aggression, and discuss research on the role of risk and protective factors. We emphasize the importance of understanding female aggression and antisocial behavior through a dynamic developmental framework that recognizes the cumulative and transactional impact of risk and protective factors over time. Our review focuses on adolescent girls in keeping with research that suggests that the risk for aggressive and antisocial behavior in girls is most acute during this developmental period.
Fitness to Stand Trial Evaluations: A Comparison of Referred and Non-Referred Defendants
Authors: Viljoen JodiL. , Zapf PatriciaA.
Published: February 2012

This study compared the characteristics of 80 defendants referred for fitness to stand trial evaluations with those of 80 defendants who were not referred. Results indicated that referred and non-referred defendants were comparable in terms of demographic characteristics. Referred defendants were significantly more likely to be charged with a violent offense, meet diagnostic criteria for current psychotic disorder, and demonstrate impaired legal abilities. They were less likely to have any previous criminal charges and meet criteria for antisocial personality disorder. Notably, approximately 25% of non-referred defendants demonstrated legal impairment. Also, approximately 20% of referred defendants appeared to have neither a current mental disorder nor legal impairment. Strategies to improve the detection and treatment of potential unfitness are discussed.
Some Questions for the Field of Violence Risk Assessment and Forensic Mental Health: Or, “Back To Basics” Revisited
Authors: Litwack ThomasR.
Published: February 2012

This paper addresses two related questions: (1) How can we best evaluate and compare clinical and actuarial assessments of dangerousness? (2) Should there not be more systematic qualitative (narrative and descriptive) studies in the field of forensic mental health (including violence risk assessment)? It is argued that adequate studies of both clinical and actuarial assessments of dangerousness have yet to be done, and that more qualitative studies of clinical assessments are necessary to better elucidate and evaluate clinical assessments and to better compare them to actuarial assessments. Furthermore, it is argued, many other areas of forensic mental health are also in need of systematic descriptive (i.e., qualitative and narrative) studies.
The Development of a Canadian Prison Based Program for Offenders with Mental Illnesses
Authors: Welsh Andrew , Ogloff JamesR.P.
Published: February 2012

A relatively large number of individuals entering the criminal justice system have a mental illness. Perhaps as many as 6% to 15% of inmates in North America have a serious mental illness, exceeding the rate found in the general population (Hodgins & Cote, 1990; Ogloff, Roesch, & Hart, 1994; Teplin, 1990). To increase the range of services available to MDOs, a number of initiatives have been undertaken in British Columbia, including the development of a prison-based mental health program. The Program has been designed for provincial offenders with a major mental illness to be conducted across a five-month (20-week) period, emphasizing the treatment and management of the offender's illness as well as the interruption of the offender's crime cycle. Currently still under development, the Program has adopted a graduated or multi-tiered approach to treatment with program content presented to participants across three distinct phases: (1) the comprehensive psychodiagnostic phase, (2) the intensive treatment phase, and (3) the community re-integration preparation phase. The purpose of this paper was to describe the Mental Health Program and to highlight important research upon which the program model was predicated.
Do Schizophrenic Patients With a History of Violence Express a Preference for Screen Violence?
Authors: Guy Karen , Mohan Damian , Taylor PamelaJ.
Published: February 2012

This study aimed to determine viewing preferences of men with schizophrenia and a history of violent crime and to compare them with two control groups. A retrospective study was carried out using a semi-structured interview to collect information. Results demonstrated that men with schizophrenia and a history of violence did not report watching more violence on screen compared to controls. However, they reported greater preference for watching violent screen images, more pleasure when watching screen violence, and greater identification with violent characters on screen. Avenues for further research and implications for treatment of violent forensic patients are discussed.
Psychological Risk Markers in Violent Female Behavior
Authors: Weizmann-Henelius Ghitta , Viemerö Vappu , Eronen Markku
Published: February 2012

The aim of this study was to identify psychological risk markers for violent female offenders. Victimization experiences, stressful life events, personality disorders and cognitive ability of 61 offenders and 30 nonoffenders were examined by a structured interview and an intelligence test. First-time offenders and repeat violent offenders were also compared on the Hare Psychopathy Checklist-Revised. Offenders had had more adverse experiences in childhood and adulthood than non-offenders, and reported partner related difficulties prior to the index offense. Cluster B personality disorders and more limited cognitive functioning characterized offenders who indulge in substance abuse and had received psychiatric treatment more often than nonoffenders. A comparison of repeat violent offenders and first-time offenders produced no differences in experiences of abuse, whereas domestic violence and parental divorce were more common in families of recidivists than in those of first-time offenders. Antisocial personality disorder, psychopathic traits, substance abuse and non-violent criminality also proved to be more frequent among the recidivists. A comparison of those whose victim was a partner and those whose victim was not a live-in companion did not reveal any significant difference in physical abuse in the partner relationship. The findings revealed that a great majority of women who pose a risk for violent behavior have personality disorder and substance abuse problems. Treatment implications are discussed.
Suicide Prevention in Penal Institutions: Validation and Optimization of a Screening Tool for Early Identification of High-Risk Inmates in Pretrial Detention
Authors: Dahle Klaus-Peter , Lohner JohannesC. , Konrad Norbert
Published: February 2012

Suicide is the leading cause of death in penal institutions, especially during the early stage of confinement. Effective suicide prevention thus requires early identification of at-risk inmates. The aim of this study was to assess a screening instrument developed in the Netherlands for early identification of potentially suicidal high-risk inmates. The screening instrument was retrospectively tested and further developed on the basis of 30 suicides that occurred between 1991–2000 at the pretrial detention center Berlin-Moabit and an equalsized control random sample. The screening instrument turned out to be sensitive. The initially high rate of false-positive classifications could be lowered by simplifying the instrument.