bluuebunny/crossref_metadata_2025 huggingface dataset:
Developing a tool for collecting and costing activity data on psychiatric inpatient wards
Authors: Sabes-Figuera R. , McCrone P. , Sharac J. , Csipke E. , Craig T. K. J. , Rose D. S. , Pearman D. , Wykes T.
Published: June 2012

Background.

Increasing therapeutic inpatient activities may improve the quality and outcomes of care. Evaluation of these interventions is necessary including assessment of cost-effectiveness. The aim of this paper is to describe the development and reliability of a tool to collect information on care contacts and therapeutic activities of patients on inpatient wards.

Method.

The development of the tool consisted of: 1) literature review, 2) interviews with staff, 3) expert consultation, 4) feasibility study, 5) focus groups with staff members, and 6) reliability tests. Service use data were collected with the tool and costs calculated.

Results.

Service users' reported more use of activities than that contained in case notes during a 7-day period. This resulted in a cost difference of £10 per person. Case notes had more one-to-one nursing contacts, with a cost difference of £4 per person. One-day data showed less nurse contact time reported by participants compared to observational data (p < 0.001) but similar use of activities. Costs were £46 for the tool and £67 for the observational data.

Conclusions.

This tool is a good source of information on the number of activities attended by service users and contacts with psychiatrists. There is some disagreement with other sources of information on interactions between service users and nurses, possibly reflecting different definitions of a ‘meaningful contact’. This does not have a major impact on cost given that for much of the care received there is reasonable agreement.
Emotion and Behavior: A General Factor of Personality From the EAS Temperament Survey and the Strengths and Difficulties Questionnaire
Authors: Veselka Livia , Schermer Julie Aitken , Just Caroline , Hur Yoon-Mi , Rushton J. Philippe , Jeong Hoe-Uk , Vernon Philip A.
Published: June 2012

The mothers of 603 pairs of 3- to 13-year-old twins in Korea completed the Emotionality, Activity, Sociability (EAS) Temperament Survey and the Strengths and Difficulties Questionnaire in reference to their twins. Principal factor analysis of the seven scales comprising these measures yielded a general factor on which all the scales had moderate to large loadings. Univariate behavioral genetic analyses showed that individual differences on this general factor could best be accounted for by additive genetic and non-shared environmental effects, with a heritability of 53%. The results strengthen the construct validity of the general factor of personality (GFP) by extracting this higher-order dimension from disparate measures, and have implications regarding social desirability criticisms applied to the GFP theory.
Anorogenic plateau formation: The importance of density changes in the lithosphere
Authors: Duesterhoeft Erik , Bousquet Romain , Wichura Henry , Oberhänsli Roland
Published: June 2012

Away from active plate boundaries the relationships between spatiotemporal variations in density and geothermal gradient are important for understanding the evolution of topography in continental interiors. In this context the classic concept of the continental lithosphere as comprising three static layers of different densities (upper crust, lower crust, and upper mantle) is not adequate to assess long‐term changes in topography and relief in regions associated with pronounced thermal anomalies in the mantle. We have therefore developed a one‐dimensional model, which is based on thermodynamic equilibrium assemblage computations and deliberately excludes the effects of melting processes like intrusion or extrusions. Our model calculates the “metamorphic density” of rocks as a function of pressure, temperature, and chemical composition. It not only provides a useful tool for quantifying the influence of petrologic characteristics on density, but also allows the modeled “metamorphic” density to be adjusted to variable geothermal gradients and applied to different geodynamic environments. We have used this model to simulate a scenario in which the lithosphere‐asthenosphere boundary is subjected to continuous heating over a long period of time (130 Ma), and demonstrate how an anorogenic plateau with an elevation of 1400 m can be formed solely as a result of heat transfer within the continental lithosphere. Our results show that, beside dynamic topography (of asthenospheric origin), density changes within the lithosphere have an important impact on the evolution of anorogenic plateaus.
The effect of surface heat fluxes on interannual variability in the spring onset of snow melt in the central Arctic Ocean
Authors: Maksimovich Elena , Vihma Timo
Published: June 2012

The timing of spring snow melt onset (SMO) on Arctic sea ice strongly affects the heat accumulation in snow and ice during the melt season. SMO itself is controlled by surface heat fluxes. Satellite passive microwave (SSM/I) observations show that the apparent melt onset (MO) varies a lot interannually and even over 50–100 km distances. The MO record appeared to be a complex blend of SMO on top of sea ice and opening of leads and polynyas due to divergent sea ice drift. We extracted SMO out of the original MO record using sea ice concentration data. Applying ERA Interim reanalysis, we evaluated the portion of SMO variance explained by radiative and turbulent surface heat fluxes in the period of 1989–2008. The anomaly of the surface net heat flux 1–7 days prior to SMO explained up to 65% of the interannual variance in SMO in the central Arctic. The main term of the net flux was the downward longwave radiation, which explained up to 90% of SMO variance within the western central Arctic. The role of the latent and sensible heat fluxes in earlier/later SMO was not to bring more/less heat to the surface but to reduce/enhance the surface heat loss. Solar radiation was not an important factor alone, but together with other fluxes improved the explained variance of SMO. Local 20‐year SMO trends averaged over the central Arctic Ocean are toward earlier melt by 9 days per decade.
Ice clouds microphysical retrieval using 94‐GHz Doppler radar observations: Basic relations within the retrieval framework
Authors: Szyrmer Wanda , Tatarevic Aleksandra , Kollias Pavlos
Published: June 2012

High quality measurements of ice cloud properties from ground‐ and space‐based sensors are key for improving our understanding of processes that affect ice cloud radiative effects and lifetime. Doppler cloud radars provide two independent measurements (reflectivity and Doppler velocity) to constrain the ice clouds microphysical retrievals. However, the retrievals are highly sensitive to the choice of the scattering forward model for non‐spherical particles at millimeter‐wavelengths and the selection of parameters in the mass‐ and velocity‐size relationships, as well as to the representation of the particle size distribution (PSD). In this paper (part 1), the development of the basic relations used in the retrieval is presented. A novel approach for reducing the number of free parameters required to describe the microphysical properties of ice particles is described. The new proposed form of the mass‐size relationship significantly reduces the sensitivity of the quantities of interest to the power law mass exponent, leaving only one parameter controlling mass dimensional relationship. A similar approach is adopted in the velocity calculation. In order to reduce the retrieval's dependence on the size distribution, the PSD defined for liquid‐equivalent diameter is described using the concept of double moment normalization. The two normalizing quantities, mean mass‐weighted diameter (Dm) and ice water content (IWC) are controlled mainly by the PSD size interval that is also an important contributor to the two Doppler observables. Both Dm and IWC are generally not very sensitive to the PSD segments of the smallest and largest particles that are considered as very uncertain.
Multiple dust sources in the Sahara Desert: The importance of sand dunes
Authors: Crouvi Onn , Schepanski Kerstin , Amit Rivka , Gillespie Alan R. , Enzel Yehouda
Published: June 2012

We determine the current sources of dust in the Sahara Desert using quantitative correlation between the number of days with dust storms (NDS), derived from remote‐sensing data of high temporal resolution, with the distribution of the soil types and geomorphic units. During 2006–8 the source of over 90% of the NDS was found to be sand dunes, leptosols, calcisols, arenosols, and rock debris. In contrast to previous studies, only few dust storms originated from playas and dry lake beds. Land erodibility was estimated by regressing the NDS to the number of days with high‐speed wind events, and was found to be high for sand dunes. Clay and fine‐silt grains and aggregates are scarce in sand dunes, which most likely produce dust particles through aeolian abrasion of sand grains. Thus, saltating sand grains impacting clay aggregates on playa surfaces cannot be the sole process for generating dust in the Sahara.
Tailward leap of multiple expansions of the plasma sheet during a moderately intense substorm: THEMIS observations
Authors: Ma Yonghui , Shen Chao , Angelopoulos V. , Lui A. T. Y. , Li Xinlin , Frey H. U. , Dunlop M. , Auster H. U. , McFadden J. P. , Larson D.
Published: June 2012

A moderately intense substorm on 1 March 2008, from 0830 to 1000 UT, observed by THEMIS probes and the Ground Based Observatory (GBO) is examined to investigate the global evolution of substorm phenomena. During this interval, all five THEMIS probes are closely aligned along the tail axis near midnight covering a radial range from ∼9 Re to ∼18 Re. After the substorm onset, plasma sheet expansions take place successively at multiple locations in the magnetotail as measured by different probes. The positions of the plasma sheet expansions have a tailward leap progression with an average velocity of ∼36 km/s. There are two types of dipolarization detected in this substorm. The first type is the dipolarization front which is associated with the bursty bulk flow (BBF). While the second type, which we call ‘global dipolarization’, is associated with plasma sheet expansions. In the substorm studied, there are four intensifications as shown in the THEMIS AE index. We can detect the effects of localized and short‐lived magnetic energy release processes occurring in the magnetotail corresponding to each of the four AE intensifications. Furthermore, the inner four probes can detect the global dipolarization signatures ∼4–15 min earlier than plasma sheet expansions, while the outermost probe (P1) cannot detect this before the plasma sheet expansion. These two phenomena are caused by the same process (magnetic energy release process) but the effects detected by probes locally appear delayed. The observations in this case are not sufficient to distinguish between the two competing substorm models.
Determination of the macroscopic optical properties of snow based on exact morphology and direct pore‐level heat transfer modeling
Authors: Haussener Sophia , Gergely Mathias , Schneebeli Martin , Steinfeld Aldo
Published: June 2012

A multiscale methodology for the determination of the macroscopic optical properties of snow is presented. It consists of solving the coupled volume‐averaged radiative transfer equations for two semi‐transparent phases – ice and air – by Monte Carlo ray tracing in an infinite slab via direct pore‐level simulations on the exact 3D microstructure obtained by computed tomography. The overall reflectance and transmittance are computed for slabs of five characteristic snow types subjected to collimated and diffuse incident radiative flux for wavelengths 0.3–3 μm. The effect of simplifying the snow microstructure and/or the radiative transfer model is elucidated by comparing our results to (i) a homogenized radiation model and considering a particulate medium made of optical equivalent grain size spheres (DISORT), or (ii) a multiphase radiation model considering a packed bed of identical overlapping semi‐transparent spheres. The calculations are experimentally validated by transmittance measurements. Significant differences in the macroscopic optical properties are observed when simplifying the snow morphology and the heat transfer model (i.e., homogenized versus multiphase). The proposed approach allows – in addition to determine macroscopic optical properties based on the exact morphology and obtained by advanced heat transfer model – for detailed understanding of radiative heat transfer in snow layers at the pore‐scale level.
Ecosystem carbon storage capacity as affected by disturbance regimes: A general theoretical model
Authors: Weng Ensheng , Luo Yiqi , Wang Weile , Wang Han , Hayes Daniel J. , McGuire A. David , Hastings Alan , Schimel David S.
Published: June 2012

Disturbances have been recognized as a key factor shaping terrestrial ecosystem states and dynamics. A general model that quantitatively describes the relationship between carbon storage and disturbance regime is critical for better understanding large scale terrestrial ecosystem carbon dynamics. We developed a model (REGIME) to quantify ecosystem carbon storage capacities (E[x]) under varying disturbance regimes with an analytical solution E[x] = U · τE · , where U is ecosystem carbon influx, τE is ecosystem carbon residence time, and τ1 is the residence time of the carbon pool affected by disturbances (biomass pool in this study). The disturbance regime is characterized by the mean disturbance interval (λ) and the mean disturbance severity (s). It is a Michaelis‐Menten‐type equation illustrating the saturation of carbon content with mean disturbance interval. This model analytically integrates the deterministic ecosystem carbon processes with stochastic disturbance events to reveal a general pattern of terrestrial carbon dynamics at large scales. The model allows us to get a sense of the sensitivity of ecosystems to future environmental changes just by a few calculations. According to the REGIME model, for example, approximately 1.8 Pg C will be lost in the high‐latitude regions of North America (>45°N) if fire disturbance intensity increases around 5.7 time the current intensity to the end of the twenty‐first century, which will require around 12% increases in net primary productivity (NPP) to maintain stable carbon stocks. If the residence time decreased 10% at the same time additional 12.5% increases in NPP are required to keep current C stocks. The REGIME model also lays the foundation for analytically modeling the interactions between deterministic biogeochemical processes and stochastic disturbance events.
The Murrumbidgee soil moisture monitoring network data set
Authors: Smith A. B. , Walker J. P. , Western A. W. , Young R. I. , Ellett K. M. , Pipunic R. C. , Grayson R. B. , Siriwardena L. , Chiew F. H. S. , Richter H.
Published: June 2012

This paper describes a soil moisture data set from the 82,000 km2 Murrumbidgee River Catchment in southern New South Wales, Australia. Data have been archived from the Murrumbidgee Soil Moisture Monitoring Network (MSMMN) since its inception in September 2001. The Murrumbidgee Catchment represents a range of conditions typical of much of temperate Australia, with climate ranging from semiarid to humid and land use including dry land and irrigated agriculture, remnant native vegetation, and urban areas. There are a total of 38 soil moisture‐monitoring sites across the Murrumbidgee Catchment, with a concentration of sites in three subareas. The data set is composed of 0–5 (or 0–8), 0–30, 30–60, and 60–90 cm average soil moisture, soil temperature, precipitation, and other land surface model forcing at all sites, together with other ancillary data. These data are available on the World Wide Web at http://www.oznet.org.au.
Heritability lost; intelligence found
Authors: Richardson Ken
Published: June 2012

The rise of intelligence was vital to evolution; the ability to process and predict rapidly changing environments allowed increasingly complex organisms to survive and thrive. Intelligence remains a fundamental property of the system rather than a discretely heritable trait.
Extreme value theory for singular measures
Authors: Lucarini Valerio , Faranda Davide , Turchetti Giorgio , Vaienti Sandro
Published: June 2012

In this paper, we perform an analytical and numerical study of the extreme values of specific observables of dynamical systems possessing an invariant singular measure. Such observables are expressed as functions of the distance of the orbit of initial conditions with respect to a given point of the attractor. Using the block maxima approach, we show that the extremes are distributed according to the generalised extreme value distribution, where the parameters can be written as functions of the information dimension of the attractor. The numerical analysis is performed on a few low dimensional maps. For the Cantor ternary set and the Sierpinskij triangle, which can be constructed as iterated function systems, the inferred parameters show a very good agreement with the theoretical values. For strange attractors like those corresponding to the Lozi and Hènon maps, a slower convergence to the generalised extreme value distribution is observed. Nevertheless, the results are in good statistical agreement with the theoretical estimates. It is apparent that the analysis of extremes allows for capturing fundamental information of the geometrical structure of the attractor of the underlying dynamical system, the basic reason being that the chosen observables act as magnifying glass in the neighborhood of the point from which the distance is computed.
Excitonic enhancement of nonradiative energy transfer from a quantum well in the optical near field of energy gradient quantum dots
Authors: Nizamoglu Sedat , Ludwig Hernández-Martínez Pedro , Mutlugun Evren , Ugur Karatay Durmus , Volkan Demir Hilmi
Published: June 2012

We report strong exciton migration with an efficiency of 83.3% from a violet-emitting epitaxial quantum well (QW) to an energy gradient colloidal construct of layered green- and red-emitting nanocrystal quantum dots (NQDs) at room temperature, enabled by the interplay between the exciton population and the depopulation of states in the optical near field. Based on the density matrix formalization of near-field interactions, we theoretically model and demonstrate that the energy gradient significantly boosts the QW-NQDs exciton transfer rate compared to using mono-dispersed NQDs, which is in agreement with the observed experimental results.
Laser induced lifetime degradation in p-type crystalline silicon
Authors: Ametowobla M. , Bilger G. , Köhler J. R. , Werner J. H.
Published: June 2012

Pulsed, green laser irradiation of uncoated p-type silicon leads to a significant reduction of the effective minority carrier lifetime. The reason for the lifetime drop lies in the introduction of recombination centres into the laser melted and recrystallized surface layer, leading to a low local minority carrier lifetime τ ≈ 10 ns inside this surface layer. The laser treatment introduces the impurities oxygen, carbon and nitrogen into the silicon and further leads to an n-type doping of the surface layer. There are strong indications that these impurities are responsible for the observed n-type doping, as well as the lifetime reduction after irradiation. Both effects are removed by thermal annealing. An estimate shows that the low local lifetime does nevertheless not affect the performance of industrial or contacted selective solar cell emitter structures.
The Ising model and critical behavior of transport in binary composite media
Authors: Murphy N. B. , Golden K. M.
Published: June 2012

We present a general theory for critical behavior of transport in binary composite media. The theory holds for lattice and continuum percolation models in both the static case with real parameters and the quasi–static case (frequency dependent) with complex parameters. Through a direct, analytic correspondence between the magnetization of the Ising model and the effective parameter problem of two phase random media, we show that the critical exponents of the transport coefficients satisfy the standard scaling relations for phase transitions in statistical mechanics. Our work also shows that delta components form in the underlying spectral measures at the spectral endpoints precisely at the percolation threshold pc and at 1 − pc. This is analogous to the Lee-Yang-Ruelle characterization of the Ising model phase transition, and identifies these transport transitions with the collapse of spectral gaps in these measures.
Bounding the distance of quantum surface codes
Authors: Fetaya Ethan
Published: June 2012

Homological quantum codes (also called topological codes) are low density parity check error correcting codes that come from surfaces and higher dimension manifolds. Homological codes from surfaces, i.e., surface codes, have also been suggested as a possible way to construct stable quantum memory and fault-tolerant computation. It has been conjectured that all homological codes have a square root bound on there distance and therefore cannot produce good codes. This claim has been disputed in dimension four using the geometric property of systolic freedom. We will show in this paper that the conjecture holds in dimension two due to the negation of systolic freedom, i.e., systolic rigidity.
Inhomogeneous mechanical losses in micro-oscillators with high reflectivity coating
Authors: Serra E. , Cataliotti F. S. , Marin F. , Marino F. , Pontin A. , Prodi G. A. , Bonaldi M.
Published: June 2012

We characterize the mechanical quality factor of micro-oscillators covered by a highly reflective coating. We test an approach to the reduction of mechanical losses that consists in limiting the size of the coated area to reduce the strain and the consequent energy loss in this highly dissipative component. Moreover, a mechanical isolation stage is incorporated in the device. The results are discussed on the basis of an analysis of homogeneous and non-homogeneous losses in the device and validated by a set of finite-element models. The contributions of thermoelastic dissipation and coating losses are separated and the measured quality factors are found in agreement with the calculated values, while the absence of unmodeled losses confirms that the isolation element integrated in the device efficiently uncouples the dynamics of the mirror from the support system. Also the resonant frequencies evaluated by finite-element models are in good agreement with the experimental data, and allow the estimation of the Young modulus of the coating. The models that we have developed and validated are important for the design of oscillating micro-mirrors with high quality factor and, consequently, low thermal noise. Such devices are useful in general for high sensitivity sensors, and in particular for experiments of quantum opto-mechanics.
Radiation and near field in resistance-inductor circuit transients
Authors: Latypov Damir , Bulmer John
Published: June 2012

A full wave solution to the classical problem of a transient response in an RL circuit is analyzed. We show that when radiation effects are rigorously taken into account, the response differs from a familiar exponential decay. The circuit behaves more like an RLC circuit and can exhibit an underdamped response. As a result of a two way energy transfer between the circuit and the near field in the underdamped regime, despite the radiation losses, current decay may be slower than predicted by the standard RL circuit model. During a transient, when retardation effects become important, inductance can no longer be defined as a coefficient of proportionality between the magnetic flux through the circuit and the current in the circuit. If rate of current decay is nearly constant, one can define a time-dependent generalized inductance which turns into conventional inductance after time D/c, where D is the diameter of the current loop. Connection of this generalized inductance with the radiation damping problem is discussed. The theory developed in this paper has been used to analyze ultra wide band radiation observed during a fast laser triggered superconducting to normal transition of a superconducting switch.
Shockley-Frank stacking faults in 6H-SiC
Authors: Sun J. W. , Robert T. , Andreadou A. , Mantzari A. , Jokubavicius V. , Yakimova R. , Camassel J. , Juillaguet S. , Polychroniadis E. K. , Syväjärvi M.
Published: June 2012

We report on Shockley-Frank stacking faults (SFs) identified in 6H-SiC by a combination of low temperature photoluminescence (LTPL) and high resolution transmission electron microscopy (TEM). In the faulted area, stacking faults manifested as large photoluminescence emissions bands located in between the 6H-SiC signal (at ∼2.99 eV) and the 3C-SiC bulk-like one (at ∼2.39 eV). Each of the stacking fault related emission band had a four-fold structure coming from the TA, LA, TO, and LO phonon modes of 3C-SiC. Up to four different faults, with four different thickness of the 3C-SiC lamella, could be observed simultaneously within the extent of the laser excitation spot. From the energy of the momentum-conservative phonons, they were associated with excitonic energy gaps at Egx1 = 2.837 eV, Egx2 = 2.689 eV, Egx3 = 2.600 eV and Egx4 = 2.525 eV. In the same part where low temperature photoluminescence was performed, high resolution transmission electron microscopy measurements revealed stacking faults which, in terms of the Zhdanov notation, could be recognized as SFs (3, 4), (3, 5), (3, 6), (3, 7), (3, 9), (3, 11), (3, 16) and (3, 22), respectively. Among them stacking fault (3, 4) was the most common one, but a faulted region with a (4, 4) 8H-SiC like sequence was also found. Using a type II 6H/3C/6H quantum-well model and comparing with experimental results, we find that the photoluminescence emissions with excitonic band gaps at 2.837 eV (Egx1), 2.689 eV (Egx2), 2.600 eV (Egx3) and 2.525 eV (Egx4) come from SFs (3, 4), (3, 5), (3, 6) and (3, 7), respectively. A possible formation mechanism of these SFs is suggested, which involves a combination of Frank faults with Shockley ones. This provides a basic understanding of stacking faults in 6H-SiC and gives a rapid and non-destructive approach to identify SFs by low temperature photoluminescence.
Domain wall configuration and magneto-transport properties in dual spin-valve with nanoconstriction
Authors: Sun Chun Byong , Wu Han-Chun , Jung Noh Su , Chang Chu In , Serrano-Guisan Santiago , Hwang Chanyong , Shvets Igor V. , Liao Zhi-Min , Abid Mohamed , Keun Kim Young
Published: June 2012

We investigated the effect of external field on magneto-transport properties of synthetic antiferromagnet dual spin-valve with nanoconstriction with focus on domain wall (DW) configuration and magnetization reversal process. As magnetic field rotated from in-plane to out-of-plane along hard axis configuration, the magnetization reversal mode changed from a vortex to a transverse type, and a multistep switching process appeared due to the development of a transverse magnetization reversal mode with DW pushing towards the higher anisotropy region. The difference in the shape of nanoconstriction made an asymmetric energy barrier to the DW propagation which resulted in an asymmetry depinning field.
Polymer stretch in two-phase microfluidics: Effect of wall wettability
Authors: Hu Ssu-Wei , Sheng Yu-Jane , Tsao Heng-Kwong
Published: June 2012

Polymer stretching in two-phase microfluidics is investigated by dissipative particle dynamics. The flow patterns can be controlled by wall wettability, flowrate ratio between two phases, and Reynolds number (Re). For neutral and partially wettable walls, segmented flows are formed and polymer stretching can be controlled by Re and segment length. At high Re, stratified flows are observed and the extension ratio can be tuned by the flowrate ratio. For nonwettable walls, slug flows are formed and polymer stretching can be controlled by Re and slug length. At high Re or flowrate ratio, annular flows are observed and high extension ratio can be easily attained.
A chaotic circuit based on Hewlett-Packard memristor
Authors: Buscarino Arturo , Fortuna Luigi , Frasca Mattia , Valentina Gambuzza Lucia
Published: June 2012

Memristors are gaining increasing attention as next generation electronic devices. They are also becoming commonly used as fundamental blocks for building chaotic circuits, although often arbitrary (typically piece-wise linear or cubic) flux-charge characteristics are assumed. In this paper, a chaotic circuit based on the mathematical realistic model of the HP memristor is introduced. The circuit makes use of two HP memristors in antiparallel. Numerical results showing some of the chaotic attractors generated by this circuit and the behavior with respect to changes in its component values are described.
Thick-wall effects in the theory of resistive wall modes
Authors: Pustovitov V. D.
Published: June 2012

Magnetic interaction of the plasma perturbations with the nearby resistive wall is considered as a resistive wall mode (RWM) problem, but with two essential differences from the traditional thin-wall approach. First, the wall is treated as magnetically thick, which means that the skin depth is not assumed larger than the wall thickness. Second, the plasma is allowed to enter the region where the RWM must be deeply unstable without rotation. The latter corresponds to the plasma operation above the no-wall stability limit demonstrated in the DIII-D tokamak [E. J. Strait et al., Phys. Plasmas 11, 2505 (2004)]. It is shown that the rotational stabilization observed in these experiments can be reproduced in this model if the mode is forced to rotate with a frequency above a critical level. The analytical estimates show that this effect (absent in the model based on the thin-wall approximation) is strong at realistic parameters. The model also predicts that the locking of the rotationally stabilized mode gives rise to instability with a growth rate much larger than its thin-wall estimate.
Note: Measuring effects of Ar-ion cleaning on the secondary electron yield of copper due to electron impact
Authors: Zhang Hai-Bo , Hu Xiao-Chuan , Wang Rui , Cao Meng , Zhang Na , Cui Wan-Zhao
Published: June 2012

In a measurement system of total secondary electron yield (SEY) with in situ ion cleaning, we investigate SEY characteristics of the Cu samples cleaned at different Ar-ion energies and cleaning time. Measured SEY data are compared with those before cleaning and simulated with the Monte Carlo method for an ideal surface of copper. We find that weakening the cleaning intensity, i.e., the ion energy or cleaning time, in some circumstances, can further reduce both the maximum SEY and the SEY at the high-energy end (>0.3 keV) of primary electrons, though the SEY is increased somewhat at the low-energy end. Accompanied by the analysis on the opposing contributions of contamination elimination and surface morphology to the SEY, this study thus provides a comprehensive insight into the effects of ion cleaning on the SEY in the investigation and suppression of secondary electron emission.
Enhanced keV peak power and yield using twisted pair “cables” in a z-pinch
Authors: Hoyt C. L. , Knapp P. F. , Pikuz S. A. , Shelkovenko T. A. , Cahill A. D. , Gourdain P.-A. , Greenly J. B. , Kusse B. R. , Hammer D. A.
Published: June 2012

Individual wires in a z-pinch were replaced with twisted pair “cables” of similar linear mass on the COBRA pulsed power generator, resulting in peak power and yield increases in radiation above 1 keV. A cable is defined here as two or more fine wires twisted together to form a continuous strand with a wavelength (λt) dependent on the twists per unit length. The magnitude of λt appears to play a strong role in these increases, with the largest gains found for a λt of ≈0.75 mm.
Electron caustic lithography
Authors: Kennedy S. M. , Zheng C. X. , Fu J. , Tang W. X. , Paganin D. M. , Jesson D. E.
Published: June 2012

A maskless method of electron beam lithography is described which uses the reflection of an electron beam from an electrostatic mirror to produce caustics in the demagnified image projected onto a resist–coated wafer. By varying the electron optics, e.g. via objective lens defocus, both the morphology and dimensions of the caustic features may be controlled, producing a range of bright and tightly focused projected features. The method is illustrated for line and fold caustics and is complementary to other methods of reflective electron beam lithography.
Analysis of neural subtypes reveals selective mitochondrial dysfunction in dopaminergic neurons from
parkin
mutants
Authors: Burman Jonathon L. , Yu Selina , Poole Angela C. , Decal Richard B. , Pallanck Leo
Published: June 2012

Studies of the familial Parkinson disease-related proteins PINK1 and Parkin have demonstrated that these factors promote the fragmentation and turnover of mitochondria following treatment of cultured cells with mitochondrial depolarizing agents. Whether PINK1 or Parkin influence mitochondrial quality control under normal physiological conditions in dopaminergic neurons, a principal cell type that degenerates in Parkinson disease, remains unclear. To address this matter, we developed a method to purify and characterize neural subtypes of interest from the adult
Drosophila
brain. Using this method, we find that dopaminergic neurons from
Drosophila parkin
mutants accumulate enlarged, depolarized mitochondria, and that genetic perturbations that promote mitochondrial fragmentation and turnover rescue the mitochondrial depolarization and neurodegenerative phenotypes of
parkin
mutants. In contrast, cholinergic neurons from
parkin
mutants accumulate enlarged depolarized mitochondria to a lesser extent than dopaminergic neurons, suggesting that a higher rate of mitochondrial damage, or a deficiency in alternative mechanisms to repair or eliminate damaged mitochondria explains the selective vulnerability of dopaminergic neurons in Parkinson disease. Our study validates key tenets of the model that PINK1 and Parkin promote the fragmentation and turnover of depolarized mitochondria in dopaminergic neurons. Moreover, our neural purification method provides a foundation to further explore the pathogenesis of Parkinson disease, and to address other neurobiological questions requiring the analysis of defined neural cell types.
Cobalt-dithiolene complexes for the photocatalytic and electrocatalytic reduction of protons in aqueous solutions
Authors: McNamara William R. , Han Zhiji , Yin Chih-Juo (Madeline) , Brennessel William W. , Holland Patrick L. , Eisenberg Richard
Published: June 2012

Artificial photosynthesis (AP) is a promising method of converting solar energy into fuel (H
2
). Harnessing solar energy to generate H
2
from H
+
is a crucial process in systems for artificial photosynthesis. Widespread application of a device for AP would rely on the use of platinum-free catalysts due to the scarcity of noble metals. Here we report a series of cobalt dithiolene complexes that are exceptionally active for the catalytic reduction of protons in aqueous solvent mixtures. All catalysts perform visible-light-driven reduction of protons from water when paired with

as the photosensitizer and ascorbic acid as the sacrificial donor. Photocatalysts with electron withdrawing groups exhibit the highest activity with turnovers up to 9,000 with respect to catalyst. The same complexes are also active electrocatalysts in 1∶1 acetonitrile/water. The electrocatalytic mechanism is proposed to be ECEC, where the Co dithiolene catalysts undergo rapid protonation once they are reduced to

. Subsequent reduction and reaction with H
+
lead to H
2
formation. Cobalt dithiolene complexes thus represent a new group of active catalysts for the reduction of protons.
High natural prevalence of a fungal prion
Authors: Debets Alfons J. M. , Dalstra Henk J. P. , Slakhorst Marijke , Koopmanschap Bertha , Hoekstra Rolf F. , Saupe Sven J.
Published: June 2012

Prions are infectious proteins that cause fatal diseases in mammals. Prions have also been found in fungi, but studies on their role in nature are scarce. The proposed biological function of fungal prions is debated and varies from detrimental to benign or even beneficial. [Het-s] is a prion of the fungus
Podospora anserina
. The
het-s
locus exists as two antagonistic alleles that constitute an allorecognition system: the
het-s
allele encoding the protein variant capable of prion formation and the
het-S
allele encoding a protein variant that cannot form a prion. We document here that
het-s
alleles, capable of prion formation, are nearly twice as frequent as
het-S
alleles in a natural population of 112 individuals. Then, we report a 92% prevalence of [Het-s] prion infection among the
het-s
isolates and find evidence of the role of the [Het-s]
/het-S
allorecognition system on the incidence of infection by a deleterious senescence plasmid. We explain the
het-s/het-S
allele ratios by the existence of two selective forces operating at different levels. We propose that during the somatic stage, the role of [Het-s]/HET-S in allorecognition leads to frequency-dependent selection for which an equilibrated frequency would be optimal. However, in the sexual cycle, the [Het-s] prion causes meiotic drive favoring the
het-s
allele. Our findings indicate that [Het-s] is a selected and, therefore, widespread prion whose activity as selfish genetic element is counteracted by balancing selection for allorecognition polymorphism.
Initial Investigations of Hops as a Salmonid Egg Fungicide
Authors: Barnes Joseph M , Dupont Taylor R , Barnes Michael E , Durben Dan J , Dixson John A
Published: June 2012

Hatchery incubation of salmonid eggs typically requires the use of chemical fungicides that possess potential negative effects on human health or the environment. Strobiles from the hops Humulus lupulus plant have exhibited antimicrobial properties in nonaquaculture situations. This study investigated the use of hops as an alternative zoosporic fungal treatment with three experiments. In the first experiment, dried strobiles from wild variety hops were ground and placed at two concentrations in petri dishes containing sesame seeds and hatchery water containing Saprolegnia diclina. There was a positive relationship between the concentrations of hops and the amount of time elapsed before the observance of zoosporic fungal infestation. In subsequent experiments, the antimycotic activity of two concentrations of commercially available Summit variety hop pellets were evaluated using dead Chinook salmon Oncorhynchus tshawytscha eggs in vertical-flow incubation trays. In the second experiment, which involved static treatments of either 24 or 48 g of hop pellets wrapped in cheesecloth, zoosporic fungi appeared on the eggs in all the treatments at the same time and developed at the same rate. In the third experiment, the cheesecloth was eliminated and hop pellets were placed directly in the incubation trays at amounts of either 224 g for the entire duration of the experiment, or 112 g initially with 88 g of hops added after 3 d. Zoosporic fungi did not appear on the dead eggs in any of the hops treatment trays until 72 h after water mold was observed on the controls. Hops also delayed complete egg infestation by 72 h. Results from these experiments indicate for the first time the potential use of both wild and commercially available hops to control zoosporic fungi on incubating salmonid eggs.
Impact of rotating resonant magnetic perturbation fields on plasma edge electron density and temperature
Authors: Stoschus H. , Schmitz O. , Frerichs H. , Reiser D. , Jakubowski M.W. , Unterberg B. , Lehnen M. , Reiter D. , Samm U.
Published: June 2012

Rotating resonant magnetic perturbation (RMP) fields impose a characteristic modulation to the edge electron density n
e(r, t) and temperature T
e(r, t) fields, which depends on the relative rotation f
rel between external RMP field and plasma fluid. The n
e(r, t) and T
e(r, t) fields measured in the edge (r/a = 0.9–1.05) of TEXTOR L-mode plasmas are in close correlation with the local magnetic vacuum topology for low relative rotation f
rel = −0.2 kHz. In comparison with the 3D neutral and plasma transport code EMC3-Eirene, this provides substantial experimental evidence that for low relative rotation level and high resonant field amplitudes (normalized radial field strength

), a stochastic edge with a remnant island chain dominated by diffusive transport exists. Radially outside a helical scrape-off layer, the so-called laminar zone embedded into a stochastic domain is found to exist. In contrast for high relative rotation of f
rel = 1.8 kHz, the measured modulation of n
e is shifted by π/2 toroidally with respect to the modelled vacuum topology. A pronounced flattening in T
e(r) and a reduction in n
e(r) is measured at the resonant flux surface and represents a clear signature for a magnetic island, which is phase shifted with respect to the vacuum island position. A correlated shift of the laminar zone radially outwards at the very plasma edge is observed suggesting that the actual near-field structure at the perturbation source is determined by the plasma response as well.
Measurement and calculation of Alfvén eigenmode damping and excitation over a full toroidal spectrum
Authors: Sears J. , Parker R.R. , Snipes J.A. , Golfinopoulos T. , Bader A. , Kramer G.J. , Tang V.
Published: June 2012

A broadband experimental study of Alfvén eigenmode (AE) damping and excitation examines both low-n and high-n AEs (0 < |n| < 9) with a single diagnostic. Direct measurements of the damping rate of stable AEs with the active MHD system, in conjunction with analytic and numerical calculation, indicate that AE stabilization in Alcator C-Mod is largely due to radiative damping. AEs are also regularly observed to become unstable during ICRF heating above 3 MW. The most unstable modes have moderate-n around n = −4, in agreement with the common scaling of k

θ

ρ
fast ≈ 1 at maximum excitation.
Corrigendum: Error field correction in DIII-D Ohmic plasmas with either handedness
Authors: Park Jong-Kyu , Schaffer Michael J. , La Haye Robert J. , Scoville Timothy J. , Menard Jonathan E.
Published: June 2012

Please see the PDF file for details.
Issues on diversity, training, and mentorship of young scientists: an interview
Authors: Aguilera Renato J.
Published: June 2012

Academic institutions across the country have long recognized the value of racial integration and have consistently opposed legal challenges to affirmative action policies. Despite these efforts, the percentage of underrepresented minorities in academic positions has not increased in proportion to their representation in society. Recruitment of underrepresented minorities into scientific and academic careers is important, because these individuals provide valuable contributions to research and teaching, and they serve as positive role models to others aspiring to such professions. In this interview, Renato Aguilera, Chair of the ASCB Minorities Affairs Committee, answers questions from MBoC Features Editor Doug Kellogg about diversity in the scientific workforce.
Sprat feeding behaviour, selective predation, and impact on plaice egg mortality
Authors: Plirú Antonio , van der Kooij Jeroen , Engelhard Georg H. , Fox Clive J. , Milligan Stephen P. , Hunter Ewan
Published: June 2012

Plirú, A., van der Kooij, J., Engelhard, G. H., Fox, C. J., Milligan, S. P., and Hunter, E. 2012. Sprat feeding behaviour, selective predation, and impact on plaice egg mortality. – ICES Journal of Marine Science, 69: 1019–1029. Although the causes of fish egg and larval mortality are poorly understood, predation is thought to be a major contributing factor. The feeding behaviour of sprat at a plaice spawning ground in the Irish Sea during February 2009 is described and their contribution to plaice egg mortality investigated. Acoustic observations and analysis of stomach contents revealed diel behaviour, with dense schools associated with feeding formed during daylight dispersing into thinly spread aggregations at dusk. Of 338 stomachs analysed, 95% contained identifiable prey items. Feeding activity peaked between 10:00 and 18:00, for all food groups. Numerically, gadoid eggs were the most frequently consumed prey (64%), followed by copepods (25%) and plaice eggs (7%). Plaice eggs were present in 91% of the stomachs analysed. Converting stomach content data to daily consumption suggested that sprat may consume 73% of all plaice eggs spawned in the area. Predation by sprat appears to account for a large proportion of plaice egg mortality, so the abundance and distribution of this pelagic predator may have important consequences for the recruitment dynamics of other fish species. Moreover, fish eggs may be an important energy source for sprat during late winter, when alternative prey is scarce.
Atlantic salmon post-smolt migration routes in the Gulf of St. Lawrence
Authors: Lefèvre Marylise A. , Stokesbury Michael J. W. , Whoriskey Frederick G. , Dadswell Michael J.
Published: June 2012

Lefèvre, M. A., Stokesbury, M. J. W., Whoriskey, F. G., and Dadswell, M. J. 2012. Atlantic salmon post-smolt migration routes in the Gulf of St. Lawrence – ICES Journal of Marine Science, 69: 981–990. The migration of Atlantic salmon (Salmo salar) post-smolts from the Rivière Saint-Jean on the north shore of the Gulf of St. Lawrence (Canada) was studied during 2009 and 2010. Salmon from rivers in this region spend ≥2 years at sea before returning to spawn, and are believed to migrate to ocean feeding areas off Greenland. To determine residency time in the nearshore environment, and to define the migration routes of post-smolts, tagged post-smolts were tracked passively in Jacques Cartier Strait and at the two exits of the Gulf of St. Lawrence to the Atlantic Ocean (Cabot Strait and the Strait of Belle Isle). Post-smolts moved rapidly south in the nearshore area; two of them were detected 45 km south of the estuary exit, suggesting that they were moving towards the centre of the Gulf of St. Lawrence. One tagged post-smolt was detected exiting the Gulf of St. Lawrence via the Strait of Belle Isle after 44 d and exhibited a minimum swimming speed of 14.4 km d−1. There was no apparent linkage between the detection patterns of post-smolts and surface water temperatures or surface water currents close to shore. Post-smolts, however, appeared to orient to higher salinity.