bluuebunny/crossref_metadata_2025 huggingface dataset:
Primary culture of neurospheres obtained from fetal mouse central nervous system and generation of inner ear hair cell immunophenotypes in vitro
Authors: Liu X-W , Sun J-W
Published: April 2011

Objective:

To investigate whether hair cell immunophenotypes can be derived from the central nervous system.

Design:

We established in vitro cell cultures from embryonic day 14.5 fetal rat brain tissue, and analysed changes in the immunohistochemical features of these cell cultures following differentiation.

Result:

The immature neural progenitors obtained from the fetal mouse central nervous system generated cell immunophenotypes which expressed epitopes of the hair cell marker proteins myosin VIIa and Brn-3c and the supporting cell marker pan-cytokeratin.

Conclusion:

Neural progenitors have the potential to differentiate into inner ear hair cell and supporting cell phenotypes, and thus may be a useful material for cell transplantation therapy aiming to replace damaged inner ear hair cells.
Precommitment Regimes for Intervention: Supplementing the Security Council
Authors: Buchanan Allen , Keohane Robert O.
Published: April 2011

As global governance institutions proliferate and become more powerful, their legitimacy is subject to ever sharper scrutiny. Yet what legitimacy means in this context and how it is to be ascertained are often unclear. In a previous paper in this journal, we offered a general account of the legitimacy of such institutions and a set of standards for determining when they are legitimate. In this paper we focus on the legitimacy of the UN Security Council as an institution for making decisions concerning the use of military force across state borders. The context for this topic has changed over the last decade as a result of the ongoing development of the responsibility to protect (RtoP) doctrine and extensive discussions about it in the United Nations. Yet the mostly widely accepted proposals for RtoP still require Security Council authorization for forceful intervention, and strictly limit the conditions under which such intervention may take place.
Public pension funding in practice
Authors: MUNNELL ALICIA H. , AUBRY JEAN-PIERRE , QUINBY LAURA
Published: April 2011

Public pension funding has recently become a front-burner policy issue in the wake of the financial crisis and given the pending retirement of large numbers of baby boomers. This paper examines the current funding of state and local pensions using a sample of 126 plans, estimating an aggregate funded ratio in 2009 of 78% using GASB accounting methods. Projections for 2010–2013 suggest that some continued deterioration is likely. Funded status can vary significantly among plans, and so the paper explores the influence of four types of factors: funding discipline, plan governance, plan characteristics, and the fiscal situation of the state. Judging the long-term health of plans requires more than just a snapshot of assets and liabilities, and so the paper examines how well plans are meeting their Annual Required Contributions and what factors influence whether they make them. The paper also addresses the controversy over what discount rate to use for valuing liabilities, concluding that using a riskless rate of return could help improve funding discipline but would need to be implemented in a manageable way. Finally, the paper assesses whether plans face a near-term liquidity crisis and finds that most have assets on hand to cover benefits over the next 15–20 years. The bottom line is that, like private investors, public plans have been hit hard by the financial crisis and their full recovery is dependent on the rebound of the economy and the stock market.
Thermo-mechanical analyses of beryllium compound refractive lens for NSLS-II beamline
Authors: Ravindranath V. , Sharma S. , Chubar O. , Cai Y. , Coburn S.
Published: April 2011

In this paper we discuss the finite-element analysis (FEA) of a one-dimensional beryllium compound refractive lens (Be-CRL) that was undertaken to study the feasibility of installing the CRL in the Inelastic X-ray Scattering (IXS) beamline of National Synchrotron Light Source-II (NSLS-II) (a new state-of-the-art medium-energy third-generation storage ring). The current insertion device for this beamline is an IVU22-6m in-vacuum planar undulator delivering a total power of ~9 kW with a peak power density of ~90 kW/mrad2. Through analysis, based on calculation of spectral angular distribution of undulator radiation from IVU22, we determined that it is essential to install a 30 µm graphite filter upstream of the CRL in order to restrict the temperature rise in the CRL to 65°C for acceptable thermal strain.
Arthrite, érythème noueux et ulcérations génitales
Authors: Arnold  , Revaz  , Dudler
Published: April 2011

La maladie de Behçet est une maladie d'étiologie inconnue à cheval entre les vasculites, les spondylarthropathies et les maladies auto-inflammatoires. Si son penchant pour les populations originaires du long de la route de la soie est bien connu, comme ses manifestations cutanées, oculaires et vasculaires, ce cas illustre bien la non-spécificité de ces manifestations, les difficultés diagnostiques et l'importance d'une évaluation systématique oculaire et digestive chez ce type de patient.
Quantifying mountain block recharge by means of catchment‐scale storage‐discharge relationships
Authors: Ajami Hoori , Troch Peter A. , Maddock Thomas , Meixner Thomas , Eastoe Chris
Published: April 2011

Despite the importance of mountainous catchments for providing freshwater resources, especially in semi‐arid regions, little is known about key hydrological processes such as mountain block recharge (MBR). Here we implement a data‐based method informed by isotopic data to quantify MBR rates using recession flow analysis. We applied our hybrid method in a semi‐arid sky island catchment in southern Arizona, United States. Sabino Creek is a 91 km2 catchment with its sources near the summit of the Santa Catalina Mountains northeast of Tucson. Southern Arizona's climate has two distinct wet seasons separated by prolonged dry periods. Winter frontal storms (November–March) provide about 50% of annual precipitation, and summers are dominated by monsoon convective storms from July to September. Isotope analyses of springs and surface water in the Sabino Creek catchment indicate that streamflow during dry periods is derived from groundwater storage in fractured bedrock. Storage‐discharge relationships are derived from recession flow analysis to estimate changes in storage during wet periods. To provide reliable estimates, several corrections and improvements to classic base flow recession analysis are considered. These corrections and improvements include adaptive time stepping, data binning, and the choice of storage‐discharge functions. Our analysis shows that (1) incorporating adaptive time steps to correct for streamflow measurement errors improves the coefficient of determination, (2) the quantile method is best for streamflow data binning, (3) the choice of the regression model is critical when the stage‐discharge function is used to predict changes in bedrock storage beyond the maximum observed flow in the catchment, and (4) the use of daily or night‐time hourly streamflow does not affect the form of the storage‐discharge relationship but will impact MBR estimates because of differences in the observed range of streamflow in each series.
OpenCOR
Authors: Garny Alan
Published: April 2011

A description of the OpenCOR project. What has been done so far, the choices that were made, etc., as well as the direction in which we are heading.
Key Information Technology and Management Issues 2010–11: An International Study
Authors: Luftman Jerry , Zadeh Hossein S
Published: April 2011

The importance of the impact of IT for organizations around the world, especially in light of the global financial crisis, has amplified the need to provide a better understanding of the specific geographic similarities and differences of IT managerial and technical trends. Going beyond identifying these influential factors is also the need to understand the considerations for addressing them, in light of recognizing the respective local characteristics, especially when operating in a globally linked environment. By comparing and contrasting different geographies, this paper presents important local and international factors (e.g., management concerns, influential technologies, budgets/spending, organizational considerations) necessary to prepare IT leaders for the challenges that await them. The research is based on data from four geographic regions (United States, Europe, Asia, and Latin America). The same questionnaire (although translated for the respective respondents), based on the lead authors of the well-respected and long-running Society for Information Management survey, was applied across geographies. This paper presents the major findings based on survey responses from 472 organizations (172 US, 142 European, 103 Asian, and 55 Latin) in mid-2010. The top five management concerns were: (1) business productivity and cost reduction; (2) IT and business alignment; (3) business agility and speed to market; (4) business process re-engineering; and (5) IT reliability and efficiency. The five most influential technologies were business intelligence, cloud computing, enterprise resource planning, Software as a Service/Platform as a Service, and collaborative tools.
Review of recent theories and experiments for improving high-power microwave window breakdown thresholds
Authors: Chang Chao , Liu Guozhi , Tang Chuanxiang , Chen Changhua , Fang Jinyong
Published: April 2011

Dielectric window breakdown is a serious challenge in high-power microwave (HPM) transmission and radiation. Breakdown at the vacuum/dielectric interface is triggered by multipactor and finally realized by plasma avalanche in the ambient desorbed or evaporated gas layer above the dielectric. Methods of improving breakdown thresholds are key challenges in HPM systems. First, the main theoretical and experimental progress is reviewed. Next, the mechanisms of multipactor suppression for periodic rectangular and triangular surface profiles by dynamic analysis and particle-in-cell simulations are surveyed. Improved HPM breakdown thresholds are demonstrated by proof-of-principle and multigigawatt experiments. The current theories and experiments of using dc magnetic field to resonantly accelerate electrons to suppress multipactor are also synthesized. These methods of periodic profiles and magnetic field may solve the key issues of HPM vacuum dielectric breakdown.
Electromagnetic properties of microwave sintered ferromagnetic-ferroelectric composites for application in low temperature co-fired ceramic devices
Authors: Qinghui Yang , Huaiwu Zhang , Qiye Wen , Yingli Liu
Published: April 2011

In this paper, microwave sintering (MS) technology has been applied in the preparation of ferromagnetic-ferroelectric composites. Several kinds of (Ni0.3Zn0.6Cu0.1)Fe2O4 (NiCuZn) ferrite with different contents of BaTiO3(BT) have been fabricated by MS technology. We found that the sintering time and temperature were significantly reduced from 22 h and 1100  °C for the conventional sintering (CS) process to 2 h and 840 °C for MS process, respectively. Experiments show that MS treated NiCuZn-BT composites possess both excellent ferromagnetic and ferroelectric properties. For the composites of NiCuZn added with 15% BaTiO3, the real part of permittivity is larger than 50 below 20 MHz and the real part of dielectric constant is larger than 18 below 1 GHz. Our results indicate that the microwave sintering method is a potential important technique in LTCC technology.
Optimization of melt spun RE-Fe-B powder composition for fully dense, high energy magnets
Authors: Brown D. N. , Lim Y. K. , Remoroza R. A. , Miller D. J.
Published: April 2011

Nanocrystalline melt-spun (Nd,Pr)-Fe-B powder can be consolidated into fully dense, anisotropic high-energy magnets by a series of thermo-mechanical processes. The powder composition and processing parameters dictate the magnetic properties of the resulting magnet. More specifically, the alloy must contain a high proportion of the (Nd,Pr)2Fe14B phase for magnetic performance together with a sufficient grain boundary phase to facilitate the grain alignment mechanism during die-upsetting. This paper demonstrates that the type of rare earth component (Nd,Pr) and minor alloy additions (Cu,Ga) have a dramatic effect on the grain boundary phase and ultimately the magnetic properties. A relatively low cost Pr-Fe-B-Cu alloy has been shown to have enhanced room temperature magnetic performance. However, these advantages are offset by the Pr-Fe-B composition having a larger thermal coefficient of Hci and as a result this type of magnet has inferior performance at 180 °C.
Tension and strain annealing for abnormal grain growth in magnetostrictive Galfenol rolled sheet
Authors: Chun Hyunsuk , Na Suok-Min , Yoo Jin-Hyeong , Wuttig Manfred , Flatau Alison B.
Published: April 2011

This paper investigates the effect of tension annealing and of strain annealing on abnormal grain growth (AGG) in polycrystalline rolled sheet of NbC-added Fe81Ga19. Electron backscattering diffraction patterns captured by orientation imaging microscopy were used for analyzing texture and grain configuration of tension annealed samples. Tension annealing, with simultaneous application of tension and high temperature annealing, with strain rate control, was conducted to study “dynamic recrystallization” for AGG. Strain annealing, application of tension to produce uniform strain and subsequent high temperature annealing, was carried out to study the effect of “strain induced boundary migration” on AGG. A small amount of texture variation resulted, but no significant AGG was observed during tension annealing. During strain annealing, no texture or grain size variation was observed in the gauge region of uniform strain in the sample; however, abnormally grown Goss-texture was observed in regions of high stress concentration outside of the gauge region of the sample.
Cells positioning using magnetic domain walls of ferromagnetic zigzag thin film
Authors: Huang Hao-Ting , Chen Chia-Yi , Lai Mei-Feng
Published: April 2011

Magnetic cell positioning is demonstrated by controlling the magnetic domain walls in ferromagnetic zigzag thin films. Magnetophoresis experiment is performed to determine the number of magnetic nanoparticles that enter the cells by endocytosis. It is observed that in the zigzag structure with larger wavelength the magnetic cells are better aligned at the vertices.
Electron self-injection into an evolving plasma bubble: Quasi-monoenergetic laser-plasma acceleration in the blowout regime
Authors: Kalmykov S. Y. , Beck A. , Yi S. A. , Khudik V. N. , Downer M. C. , Lefebvre E. , Shadwick B. A. , Umstadter D. P.
Published: April 2011

An electron density bubble driven in a rarefied uniform plasma by a slowly evolving laser pulse goes through periods of adiabatically slow expansions and contractions. Bubble expansion causes robust self-injection of initially quiescent plasma electrons, whereas stabilization and contraction terminate self-injection thus limiting injected charge; concomitant phase space rotation reduces the bunch energy spread. In regimes relevant to experiments with hundred terawatt- to petawatt-class lasers, bubble dynamics and, hence, the self-injection process are governed primarily by the driver evolution. Collective transverse fields of the trapped electron bunch reduce the accelerating gradient and slow down phase space rotation. Bubble expansion followed by stabilization and contraction suppresses the low-energy background and creates a collimated quasi-monoenergetic electron bunch long before dephasing. Nonlinear evolution of the laser pulse (spot size oscillations, self-compression, and front steepening) can also cause continuous self-injection, resulting in a large dark current, degrading the electron beam quality.
Perpendicular magnetic anisotropy in CoFe2O4(001) films epitaxially grown on MgO(001)
Authors: Yanagihara H. , Uwabo K. , Minagawa M. , Kita Eiji , Hirota Noriyuki
Published: April 2011

We report on the magnetic properties of epitaxial cobalt-ferrite films with orientations parallel to [001] and [111] grown by a reactive molecular beam epitaxy method using pure ozone gas as an oxidation agent. Both Mössbauer spectroscopy and magnetization measurement of the CoFe2O4(001) film grown on MgO(001) indicate that the film has perpendicular magnetic anisotropy (PMA) with high coercivity, whereas the film of CoFe2O4(111) grown on α-Al2O3(0001) appears to be paramagnetic. The maximum uniaxial anisotropy energy for CoFe2O4(001) estimated from the magnetization and coercivity at room temperature is ≈3×106 erg/cm3.
Phase decomposition diagram of magnetic alloy semiconductor
Authors: Nam Hai Pham , Yada Shinsuke , Tanaka Masaaki
Published: April 2011

We investigate the thermodynamics of phase decomposition in magnetic alloy semiconductors (MASs) using the statistical Flory–Huggins lattice model. Based on this model, we propose a method to determine experimentally the interaction parameter χ and apply it to draw the phase decomposition diagram of (GaMn)As. The interaction energy of (GaMn)As was estimated to be about 5.7 mRy, which is close to the first principle calculation of 4.2 mRy. Using this phase diagram, we fabricated MnAs nanoparticles with a rectangular lattice structure utilizing the spinodal decomposition. We discuss the formation of rectangular and triangular lattice structures at the late stage of spinodal decomposition in MASs using the Ginzburg–Landaulike free energy function.
Wave–particle interactions in rotating mirrors
Authors: Fetterman Abraham J. , Fisch Nathaniel J.
Published: April 2011

Wave–particle interactions in E×B rotating plasmas feature an unusual effect: particles are diffused by waves in both potential energy and kinetic energy. This wave–particle interaction generalizes the alpha channeling effect, in which radio frequency waves are used to remove alpha particles collisionlessly at low energy. In rotating plasmas, the alpha particles may be removed at low energy through the loss cone, and the energy lost may be transferred to the radial electric field. This eliminates the need for electrodes in the mirror throat, which have presented serious technical issues in past rotating plasma devices. A particularly simple way to achieve this effect is to use a high azimuthal mode number perturbation on the magnetic field. Rotation can also be sustained by waves in plasmas without a kinetic energy source. This type of wave has been considered for plasma centrifuges used for isotope separation. Energy may also be transferred from the electric field to particles or waves, which may be useful for ion heating and energy generation.
Formation of high-β plasma and stable confinement of toroidal electron plasma in Ring Trap 1
Authors: Saitoh H. , Yoshida Z. , Morikawa J. , Furukawa M. , Yano Y. , Kawai Y. , Kobayashi M. , Vogel G. , Mikami H.
Published: April 2011

Formation of high-β electron cyclotron resonance heating plasma and stable confinement of pure electron plasma have been realized in the Ring Trap 1 device, a magnetospheric configuration generated by a levitated dipole field magnet. The effects of coil levitation resulted in drastic improvements of the confinement properties, and the maximum local β value has exceeded 70%. Hot electrons are major component of electron populations, and its particle confinement time is 0.5 s. Plasma has a peaked density profile in strong field region [H. Saitoh et al., 23rd IAEA Fusion Energy Conference EXC/9-4Rb (2010)]. In pure electron plasma experiment, inward particle diffusion is realized, and electrons are stably trapped for more than 300 s. When the plasma is in turbulent state during beam injection, plasma flow has a shear, which activates the diocotron (Kelvin–Helmholtz) instability. The canonical angular momentum of the particle is not conserved in this phase, realizing the radial diffusion of charged particles across closed magnetic surfaces. [Z. Yoshida et al., Phys Rev. Lett. 104, 235004 (2010); H. Saitoh et al., Phys. Plasmas 17, 112111 (2010).].
Solution processed multilayer polymer light-emitting diodes based on different molecular weight host
Authors: Al-Attar Hameed A. , Monkman Andrew P.
Published: April 2011

Solution processed multilayer polymer light-emitting diodes (PLEDs) based on different molecular weight host have been investigated. A PLED based on high molecular weight poly (vinyl carbazole) PVKH and low molecular weight poly (vinyl carbazole) PVKL, doped with iridium, tris(2-phenylpyidine) Ir(ppy)3 as a host-guest emitting layer (EML), shows a dramatic increase in device efficiency. When the PVKH was used as a hole transport electron blocking layer (HT-EBL), effective electron blocking was achieved, which leads to an increase exciton population in the phosphorescent zone. The use of low molecular weight PVKL as a host material in the top layer prevents barrier formation for hole transport from the poly(3,4-ethylenedioxy-thiophene) (PEDOT)–EBL to the EML. External quantum efficiency of 11%, current efficiencies of 38 cd/A, power efficiency of 13 lm/W and brightness of 7000 cd/m2, were obtained. The effect of the PVKH layer on the electrical and optical device characteristics was investigated. Simulation of the optical outcoupling using SETFOS 3.1 software is in agreed with the observed results and allowed us to predict the emissive dipole location and distribution in the EML layer. The effect of the PVKH on the exciton quenching by the electrodes was also investigated using time resolved fluorescence photon counting, which indicates weak exciton quenching by the PEDOT layer and the device enhancement predominantly achieved by exciton confinement in the emissive layer.
Bifurcation mechanisms of regular and chaotic network signaling in brain astrocytes
Authors: Matrosov V. V. , Kazantsev V. B.
Published: April 2011

Bifurcation mechanisms underlying calcium oscillations in the network of astrocytes are investigated. Network model includes the dynamics of intracellular calcium concentration and intercellular diffusion of inositol 1,4,5-trisphosphate through gap junctions. Bifurcation analysis of underlying nonlinear dynamical system is presented. Parameter regions and principle bifurcation boundaries have been delineated and described. We show how variations of the diffusion rate can lead to generation of network calcium oscillations in originally nonoscillating cells. Different scenarios of regular activity and its transitions to chaotic dynamics have been obtained. Then, the bifurcations have been associated with statistical characteristics of calcium signals showing that different bifurcation scenarios yield qualitative changes in experimentally measurable quantities of the astrocyte activity, e.g., statistics of calcium spikes.
Kinetics of low pH-induced lamellar to bicontinuous cubic phase transition in dioleoylphosphatidylserine/monoolein
Authors: Alam Mahay Md. , Oka Toshihiko , Ohta Noboru , Yamazaki Masahito
Published: April 2011

Recently, it has been well recognized that the modulation of electrostatic interactions due to surface charges can induce transitions between lamellar liquid-crystalline (Lα) and inverse bicontinuous double-diamond cubic (QIID) phases in biological lipids. To reveal their kinetic pathway and mechanism, we investigated the low pH-induced Lα to QIID phase transitions in 20%-dioleoylphosphatidylserine (DOPS)/80%-monoolein (MO) using time-resolved small-angle x-ray scattering and a rapid mixing method. At a final pH of 2.6–2.9, the Lα phase was transformed completely into the hexagonal II (HII) phase within 2–10 s after mixing a low pH buffer with a suspension of multilamellar vesicles of 20%-DOPS/80%-MO (the initial step). Subsequently, the HII phase slowly converted into the QIID phase and completely disappeared within 15–30 min (the second step). The rate constants of the second step were obtained using the singular value decomposition analysis. On the basis of these data, we discuss the underlying mechanism of the kinetic pathway of the low pH-induced Lα to QIID phase transitions.
Large magnetoresistance in current-perpendicular-to-plane pseudospin valve using a Co2Fe(Ge0.5Ga0.5) Heusler alloy
Authors: Takahashi Y. K. , Srinivasan A. , Varaprasad B. , Rajanikanth A. , Hase N. , Nakatani T. M. , Kasai S. , Furubayashi T. , Hono K.
Published: April 2011

Using a newly developed highly spin-polarized Heusler alloy, Co2Fe(Ga0.5Ge0.5) (CFGG), as ferromagnetic layers, we have fabricated a current-perpendicular-to-plane pseudospin valve with large resistance change-area product (ΔRA) of 9.5 mΩ μm2 and magnetoresistance (MR) ratio (100×ΔR/R) of 41.7% at 300 K. These values were further enhanced to ΔRA=26.4 mΩ μm2 and MR=129.1% at 10 K. The large MR values are attributed to the high spin polarization of the CFGG alloy confirmed by point contact Andreev reflection measurements.
Global solutions of compressible barotropic Navier–Stokes equations with a density-dependent viscosity coefficient
Authors: Zhang Ting
Published: April 2011

In this paper, we consider the global existence and uniqueness of the classical (weak) solution for the 2D or 3D compressible Navier–Stokes equations with a density-dependent viscosity coefficient (λ = λ(ρ)). Initial data and solutions are only small in the energy-norm. We also give a description of the large time behavior of the solution. Then, we study the propagation of singularities in solutions. We obtain that if there is a vacuum domain initially, then the vacuum domain will exist for all time, and vanishes as time goes to infinity.
Optical interrogation system based on holographic soft matter filter
Authors: Donisi D. , De Sio L. , Beccherelli R. , Caponero M. A. , d’Alessandro A. , Umeton C.
Published: April 2011

We present an optical interrogation system based on a holographic soft-matter filter. It provides a wavelength-dependent transmittance, with a linear relation between Bragg wavelength shift and variation in the filter output intensity. This is the demonstration of a simple and inexpensive technology to implement a, low cost, monitoring system based on a fiber Bragg grating sensor.
Surface morphology and magnetic anisotropy in (Ga,Mn)As
Authors: Piano S. , Marti X. , Rushforth A. W. , Edmonds K. W. , Campion R. P. , Wang M. , Caha O. , Schülli T. U. , Holý V. , Gallagher B. L.
Published: April 2011

Atomic force microscopy and grazing incidence x-ray diffraction measurements have revealed the presence of ripples, aligned along the [11¯0] direction on the surface of (Ga,Mn)As layers grown on GaAs(001) substrates and buffer layers, with periodicity of about 50 nm in all samples that have been studied. These samples show the strong symmetry breaking uniaxial magnetic anisotropy normally observed in such materials. We observe a clear correlation between the amplitude of the surface ripples and the strength of the uniaxial magnetic anisotropy component suggesting that these ripples might be the source of such anisotropy.
Cation ratio of soil structural stability (CROSS)
Authors: Rengasamy Pichu , Marchuk Alla
Published: April 2011

Sodium salts tend to dominate salt-affected soils and groundwater in Australia; therefore, sodium adsorption ratio (SAR) is used to parameterise soil sodicity and the effects of sodium on soil structure. However, some natural soils in Australia, and others irrigated with recycled water, have elevated concentrations of potassium and/or magnesium. Therefore, there is a need to derive and define a new ratio including these cations in place of SAR, which will indicate the dispersive effects of Na and K on clay dispersion, and Ca and Mg on flocculation. Based on the differential dispersive effects Na and K and the differential flocculation powers of Ca and Mg, we propose the concept of ‘cation ratio of soil structural stability’ (CROSS), analogous to SAR. This paper also gives the results of a preliminary experiment conducted on three soils varying in soil texture on hydraulic conductivity using percolating waters containing different proportions of the cations Ca, Mg, K, and Na. The relative changes in hydraulic conductivity of these soils, compared with the control treatment using CaCl2 solution, was highly correlated with CROSS. Clay dispersion in 29 soils treated with irrigation waters of varying cationic composition was highly correlated with CROSS rather than SAR. It was also found that CROSS measured in 1 : 5 soil/water extracts was strongly related to the ratio of exchangeable cations. These results encourage further study to investigate the use of CROSS as an index of soil structural stability in soils with different electrolytes, organic matter, mineralogy, and pH.
Environmental risk indicators for soil phosphorus status
Authors: Moody P. W.
Published: April 2011

Biologically available phosphorus (P) is divided operationally into two sources, dissolved reactive P (DRP) and bioavailable particulate P (BPP). Dilute CaCl2-extractable soil P (CaCl2-P) is considered to be the benchmark method for estimating DRP in soils, whereas P desorbed to iron-oxide impregnated filter paper (FeO-P) is the benchmark method for BPP in soils and sediments. Neither of these methods is in routine use in Australia. Selected soil P analyses were carried out on 31 diverse surface soils to develop relationships between the environmental benchmark methods and the routine soil P tests of Colwell-P, Olsen-P, and the single-point P buffer index (PBI). The index (Colwell-P/PBI) was highly correlated with CaCl2-P (r = 0.925, P < 0.001), and both Olsen-P and Colwell-P were highly correlated with FeO-P (r = 0.955 and 0.828, respectively; P < 0.001). It is suggested that these measures can be used as environmental risk indicators for soil P status. The critical values of these measures for optimum productivity were compared to the values of these measures corresponding to threshold values of currently used environmental risk indicators.
Effect of Fe/Al oxides on desorption of Cd2+ from soils and minerals as related to diffuse layer overlapping
Authors: Wang Yan-ping , Xu Ren-kou , Li Jiu-yu
Published: April 2011

Cadmium is a toxic metal with high reactivity in acid variable charge soils. Adsorption and desorption of Cd2+ in soil and mineral particles can be affected by the interaction between the electrical double layers on oppositely charged particles, because the interaction can decrease the surface-charge density of the particles. We studied the effect of Fe/Al oxides on desorption of Cd2+ from soils and minerals and proposed the desorption mechanisms based on the overlapping of diffuse layers between negatively charged soils and mineral particles and positively charged Fe/Al oxide particles. Our results indicate that the overlapping of diffuse layers of electrical double layers between positively charged Fe/Al oxides [crystalline and amorphous Al(OH)3 and amorphous Fe(OH)3] and negatively charged Ultisol, Alfisol, kaolinite, and bentonite caused the effective negative surface-charge density on the soils and minerals to become less negative, and thus the adsorption affinity of these negatively charged surfaces for Cd2+ declined as a result of the incorporation of the Fe/Al oxides. Consequently, the release of exchangeable Cd2+ from the surfaces of the soils and minerals increased with the amount of Fe/Al oxides added. The more positive the charge on the surfaces of the Fe/Al oxides, the stronger the interaction of the electrical double layers between the oxides and soils and minerals, and thus the greater the release of Cd2+ from the soils and minerals. A decrease in pH led to an increase in the positive surface charge on the Fe/Al oxides and enhancement of the interaction of the electrical double layers between the oxides and soils and minerals. As a result, more Cd2+ was desorbed from the soils and minerals. This study suggests that the interaction between oppositely charged particles of variable charge soils can enhance the mobility of cadmium in the soils and thus increase its environmental risk.
Reproductive behaviour of the southern-hairy nosed wombat (Lasiorhinus latifrons)
Authors: Hogan Lindsay , Phillips Clive , Lisle Allan , Horsup Alan , Janssen Tina , Johnston Stephen
Published: April 2011

The southern hairy-nosed wombat (Lasiorhinus latifrons) is under threat as its current distribution range and population size is declining. The low reproductive rates observed for this species, both in the wild and within captivity, are a cause for concern; as such this study was designed to provide a comprehensive account of reproductive behaviour in L. latifrons. The behaviour of four groups of captive animals (each 1♂ : 2♀) was remotely monitored for 14 months using a digital video-surveillance system. Using this technology, 13 distinctive reproductive-based behaviours were identified and recorded; each behaviour was allocated to one of two categories: courtship/guarding or mating. The courtship-to-mating ritual was made up of six consecutive phases: investigation, attraction, chase, restraint, coitus and recovery. In total, 423 courtship and 49 mating bouts were observed from five (2♂ : 3♀) wombats. Courtship behaviour was observed on 116 days, with a mean bout number of 3.6 ± 0.2 per day and a mean total daily time of 29.8 ± 1.8 min. Mating was observed on 24 days, with a mean bout number of 2.1 ± 0.3 per day and a mean total daily time of 100.1 ± 9.8 min. Courtship occurred over the entire enclosure area and three distinctive courtship locomotor patterns were identified: spiral-circles, straight-lines and random. Matings occurred only in closed spaces and were always accompanied by courtship behaviour. In contrast, only 68% of all courtship days were associated with a mating event. Receptivity in the female wombats lasted for 13 h and the behavioural signs of oestrus were so subtle that only the reaction/interest of the male could be used for its detection. The covert reproductive behaviours identified for female L. latifrons closely match those previously reported for captive common wombats and may relate to this species’ need to conserve energy.
Genome-wide nested association mapping of quantitative resistance to northern leaf blight in maize
Authors: Poland Jesse A. , Bradbury Peter J. , Buckler Edward S. , Nelson Rebecca J.
Published: April 2011

Quantitative resistance to plant pathogens, controlled by multiple loci of small effect, is important for food production, food security, and food safety but is poorly understood. To gain insights into the genetic architecture of quantitative resistance in maize, we evaluated a 5,000-inbred-line nested association mapping population for resistance to northern leaf blight, a maize disease of global economic importance. Twenty-nine quantitative trait loci were identified, and most had multiple alleles. The large variation in resistance phenotypes could be attributed to the accumulation of numerous loci of small additive effects. Genome-wide nested association mapping, using 1.6 million SNPs, identified multiple candidate genes related to plant defense, including receptor-like kinase genes similar to those involved in basal defense. These results are consistent with the hypothesis that quantitative disease resistance in plants is conditioned by a range of mechanisms and could have considerable mechanistic overlap with basal resistance.
Quantifying structure and performance diversity for sets of small molecules comprising small-molecule screening collections
Authors: Clemons Paul A. , Wilson J. Anthony , Dančík Vlado , Muller Sandrine , Carrinski Hyman A. , Wagner Bridget K. , Koehler Angela N. , Schreiber Stuart L.
Published: April 2011

Using a diverse collection of small molecules we recently found that compound sets from different sources (commercial; academic; natural) have different protein-binding behaviors, and these behaviors correlate with trends in stereochemical complexity for these compound sets. These results lend insight into structural features that synthetic chemists might target when synthesizing screening collections for biological discovery. We report extensive characterization of structural properties and diversity of biological performance for these compounds and expand comparative analyses to include physicochemical properties and three-dimensional shapes of predicted conformers. The results highlight additional similarities and differences between the sets, but also the dependence of such comparisons on the choice of molecular descriptors. Using a protein-binding dataset, we introduce an information-theoretic measure to assess
diversity of performance
with a constraint on specificity. Rather than relying on finding individual active compounds, this measure allows rational judgment of compound subsets as groups. We also apply this measure to publicly available data from
ChemBank
for the same compound sets across a diverse group of functional assays. We find that performance diversity of compound sets is relatively stable across a range of property values as judged by this measure, both in protein-binding studies and functional assays. Because building screening collections with improved performance depends on efficient use of synthetic organic chemistry resources, these studies illustrate an important quantitative framework to help prioritize choices made in building such collections.
Loss of lysine-specific demethylase 1 nonautonomously causes stem cell tumors in the
Drosophila
ovary
Authors: Eliazer Susan , Shalaby Nevine A. , Buszczak Michael
Published: April 2011

Specialized microenvironments called niches keep stem cells in an undifferentiated and self-renewing state. Dedicated stromal cells form niches by producing a variety of factors that act directly on stem cells. The size and signaling output of niches must be finely tuned to ensure proper tissue homeostasis. Although advances have been made in identifying factors that promote niche cell fate, the mechanisms that restrict niche cell formation during development and limit niche signaling output in adults remain poorly understood. Here, we show that the histone lysine-specific demethylase 1 (Lsd1) regulates the size of the germline stem cell (GSC) niche in
Drosophila
ovaries. GSC maintenance depends on bone morphogenetic protein (BMP) signals produced by a small cluster of cap cells located at the anterior tip of the germarium.
Lsd1
null mutant ovaries carry small germline tumors containing an expanded number of GSC-like cells with round fusomes that display ectopic BMP signal responsiveness away from the normal niche. Clonal analysis and cell type-specific rescue experiments demonstrate that Lsd1 functions within the escort cells (ECs) that reside immediately adjacent to cap cells and prevents them from ectopically producing niche-specific signals. Temporally restricted gene knockdown experiments suggest that Lsd1 functions both during development, to specify EC fate, and in adulthood, to prevent ECs from forming ectopic niches independent of changes in cell fate. Further analysis shows that Lsd1 functions to repress
decapentaplegic
(
dpp
) expression in adult germaria. The role of Lsd1 in regulating niche-specific signals may have important implications for understanding how disruption of its mammalian homolog contributes to cancer and metastasis.
Motion of myosin head domains during activation and force development in skeletal muscle
Authors: Reconditi Massimo , Brunello Elisabetta , Linari Marco , Bianco Pasquale , Narayanan Theyencheri , Panine Pierre , Piazzesi Gabriella , Lombardi Vincenzo , Irving Malcolm
Published: April 2011

Muscle contraction is driven by a change in the structure of the head domain of myosin, the “working stroke” that pulls the actin filaments toward the midpoint of the myosin filaments. This movement of the myosin heads can be measured very precisely in intact muscle cells by X-ray interference, but until now this technique has not been applied to physiological activation and force generation following electrical stimulation of muscle cells. By using this approach, we show that the long axes of the myosin head domains are roughly parallel to the filaments in resting muscle, with their center of mass offset by approximately 7 nm from the C terminus of the head domain. The observed mass distribution matches that seen in electron micrographs of isolated myosin filaments in which the heads are folded back toward the filament midpoint. Following electrical stimulation, the heads move by approximately 10 nm away from the filament midpoint, in the opposite direction to the working stroke. The time course of this motion matches that of force generation, but is slower than the other structural changes in the myosin filaments on activation, including the loss of helical and axial order of the myosin heads and the change in periodicity of the filament backbone. The rate of force development is limited by that of attachment of myosin heads to actin in a conformation that is the same as that during steady-state isometric contraction; force generation in the actin-attached head is fast compared with the attachment step.
Fluctuations of fish populations and the magnifying effects of fishing
Authors: Shelton Andrew O. , Mangel Marc
Published: April 2011

A central and classic question in ecology is what causes populations to fluctuate in abundance. Understanding the interaction between natural drivers of fluctuating populations and human exploitation is an issue of paramount importance for conservation and natural resource management. Three main hypotheses have been proposed to explain fluctuations: (i) species interactions, such as predator–prey interactions, cause fluctuations, (ii) strongly nonlinear single-species dynamics cause fluctuations, and (iii) environmental variation cause fluctuations. We combine a general fisheries model with data from a global sample of fish species to assess how two of these hypothesis, nonlinear single-species dynamics and environmental variation, interact with human exploitation to affect the variability of fish populations. In contrast with recent analyses that suggest fishing drives increased fluctuations by changing intrinsic nonlinear dynamics, we show that single-species nonlinear dynamics alone, both in the presence and absence of fisheries, are unlikely to drive deterministic fluctuations in fish; nearly all fish populations fall into regions of stable dynamics. However, adding environmental variation dramatically alters the consequences of exploitation on the temporal variability of populations. In a variable environment, (i) the addition of mortality from fishing leads to increased temporal variability for all species examined, (ii) variability in recruitment rates of juveniles contributes substantially more to fluctuations than variation in adult mortality, and (iii) the correlation structure of juvenile and adult vital rates plays an important and underappreciated role in determining population fluctuations. Our results are robust to alternative model formulations and to a range of environmental autocorrelation.
Heat induces the splicing by IRE1 of a mRNA encoding a transcription factor involved in the unfolded protein response in Arabidopsis
Authors: Deng Yan , Humbert Sabrina , Liu Jian-Xiang , Srivastava Renu , Rothstein Steven J. , Howell Stephen H.
Published: April 2011

Adverse environmental conditions produce endoplasmic reticulum (ER) stress in plants. In response to heat or ER stress agents,Arabidopsisseedlings mitigate stress damage by activating ER-associated transcription factors and a RNA splicing factor, IRE1b. IRE1b splices the mRNA-encoding bZIP60, a basic leucine-zipper domain containing transcription factor associated with the unfolded protein response in plants. bZIP60 is required for the up-regulation ofBINDING PROTEIN3(BIP3) in response to ER stress, and loss-of-function mutations inIRE1bor point mutations in the splicing site ofbZIP60mRNA are defective inBIP3induction. These findings demonstrate thatbZIP60in plants is activated by RNA splicing and afford opportunities for monitoring and modulating stress responses in plants.
Fatty acid production in genetically modified cyanobacteria
Authors: Liu Xinyao , Sheng Jie , Curtiss III Roy
Published: April 2011

To avoid costly biomass recovery in photosynthetic microbial biofuel production, we genetically modified cyanobacteria to produce and secrete fatty acids. Starting with introducing an acyl–acyl carrier protein thioesterase gene, we made six successive generations of genetic modifications of cyanobacterium
Synechocystis
sp. PCC6803 wild type (SD100). The fatty acid secretion yield was increased to 197 ± 14 mg/L of culture in one improved strain at a cell density of 1.0 × 10
9
 cells/mL by adding codon-optimized thioesterase genes and weakening polar cell wall layers. Although these strains exhibited damaged cell membranes at low cell densities, they grew more rapidly at high cell densities in late exponential and stationary phase and exhibited less cell damage than cells in wild-type cultures. Our results suggest that fatty acid secreting cyanobacteria are a promising technology for renewable biofuel production.
Targeting p21-activated kinase 1 (PAK1) to induce apoptosis of tumor cells
Authors: Ong Christy C. , Jubb Adrian M. , Haverty Peter M. , Zhou Wei , Tran Victoria , Truong Tom , Turley Helen , O'Brien Tom , Vucic Domagoj , Harris Adrian L. , Belvin Marcia , Friedman Lori S. , Blackwood Elizabeth M. , Koeppen Hartmut , Hoeflich Klaus P.
Published: April 2011

p21-activated kinases (PAKs) are serine/threonine protein kinases that serve as important mediators of Rac and Cdc42 GTPase function as well as pathways required for Ras-driven tumorigenesis. PAK1 has been implicated in signaling by growth factor receptors and morphogenetic processes that control cell polarity, invasion, and actin cytoskeleton organization. To better understand the role of PAK1 in tumorigenesis, PAK1 genomic copy number and expression were determined for a large panel of breast, lung, and head and neck tumors. PAK1 genomic amplification at 11q13 was prevalent in luminal breast cancer, and PAK1 protein expression was associated with lymph node metastasis. Breast cancer cells with PAK1 genomic amplification rapidly underwent apoptosis after inhibition of this kinase. Strong nuclear and cytoplasmic PAK1 expression was also prevalent in squamous nonsmall cell lung carcinomas (NSCLCs), and selective PAK1 inhibition was associated with delayed cell-cycle progression in vitro and in vivo. NSCLC cells were profiled using a library of pathway-targeted small-molecule inhibitors, and several synergistic combination therapies, including combination with antagonists of inhibitor of apoptosis proteins, were revealed for PAK1. Dual inhibition of PAK1 and X chromosome-linked inhibitor of apoptosis efficiently increased effector caspase activation and apoptosis of NSCLC cells. Together, our results provide evidence for dysregulation of PAK1 in breast and squamous NSCLCs and a role for PAK1 in cellular survival and proliferation in these indications.
The role of response biases in the relationship between students’ perceptions of their courses and their approaches to studying in higher education
Authors: Richardson John T.E.
Published: April 2011

Questionnaire surveys have found a strong relationship between students’ perceptions of their courses and their approaches to studying, but this might result from the operation of response biases. Responses to the Course Experience Questionnaire and the Revised Approaches to Studying Inventory from 2137 students taking seven courses by distance learning were reanalysed. Both acquiescent responding and extreme responding were found to be consistent traits within individual students between the two instruments. When these were statistically controlled, the overlap in variance between the students’ scores on the two instruments was reduced from 45.3% to 31.9%, and the variation in the students’ course marks explained by their scores on the two instruments was reduced from 21.8% to 18.9%. Nevertheless, the relationship between the two sets of scores remained the same: students who rated their course positively were more likely to show desirable approaches to studying and less likely to show undesirable approaches.