bluuebunny/crossref_metadata_2025 huggingface dataset:
Gene Analysis of Single Cells
Authors: Cauli Bruno , Lambolez Bertrand
Published: October 2010

Shortly after the initial demonstration of the feasibility of gene analysis at the single cell level,1 the two major technical trends enabling gene expression analyses of single cells developed in the early 90s. These developments were aimed either at whole transcriptome analysis based on RNA amplification,2,3 or at limited gene expression profiling using RT-PCR for correlating molecular and functional properties.4 The brain complexity and cellular diversity has been a strong incentive for the development of these tools at a time when many of the major constituents of neurotransmission had been cloned. Both techniques initially relied on the use of the patch-clamp technique5 to harvest selectively the cell's mRNAs. In this chapter we will detail the key steps, which assessed the reliability and functional relevance of the “single cell RT-PCR after patch-clamp” technique (scPCR, Lambolez et al., 1922), and describe its evolutions. We will also share our observations on the design and interpretation of scPCR experiments and discuss the limits of this approach.
Proteomics
Authors: Hesse Anne-Marie , Vinh Joëlle
Published: October 2010

Understanding the functioning of a living cell supposes to decipher the complex molecular mechanisms which underlie the various cellular activities. All the genes of an organism, or its genome, constitute a static and specific databank of this living being. From a unique genome, every cellular type of an organism is going to express a set of proteins, or proteome, which is going to vary according to the environment of the cells. As proteins constitute the final actors of the biological processes, their study may offer the most relevant vision of the functioning of a living cell.

In this part the specificity of proteomic approaches are discussed. Analytical strategies involving biological mass spectrometry are presented in association with liquid chromatography. Multidimensional analyses are introduced for complex mixture analysis and quantification. In conclusion specific technological developments towards the miniaturization, the integration and the automation of the analysis of samples available in very low amounts are introduced as the next step towards single cell proteomics.
Cell Capture and Lysis on a Chip
Authors: Gac Séverine Le , van den Berg Albert
Published: October 2010

Single cell analysis in a microfluidic device proceeds through a certain number of steps. The two first steps of the protocol are the manipulation of individual cells in the microfluidic device and their positioning in precise locations and subsequently the process to rupture the cell membrane to retrieve the cellular content. In this chapter, we will focus on these two first steps of cell trapping and single cell lysis, and review different approaches and techniques found in the literature for these two steps to achieve these in a microfluidic format. We will also discuss the advantages and limitations of the different techniques of manipulation, trapping and lysis.
DNA Analysis in Microfluidic Devices and their Application to Single Cell Analysis
Authors: Marcy Yann , Bras Angélique Le
Published: October 2010

The main developments of microfluidic systems for genetic analyses are aimed at the miniaturization of all biological operations from sampling to detection, an operation named by Manz Micro Total Analysis System (μTAS) 20 years ago.1 Since then, intense efforts have been made to integrate on a single device all the steps of sample analysis. This integration proved highly complex and has hindered the development of hands-off systems with sample-in answer-out capabilities, apart from a handful of examples in the literature and only one commercially available device (Cepheid).2–4

Nevertheless, these efforts have not been wasted since we have witnessed successful uses of microfluidic systems for certain dedicated tasks, either as a preparative step or as a detection mean, with major improvements over conventional molecular biology. Some of these devices have now become part of the standard equipment of biology labs, replacing old technologies.

We will review here the state-of-the-art of microfluidic systems for genetic analyses and analyze their ability to reproduce biological operations and even go beyond, by achieving superior performances either in speed, consumption or efficiency, especially in the case of single cell analysis.
Gene Expression Analysis on Microchips
Authors: Chabert Max
Published: October 2010

Integration of the whole operations enabling gene expression analysis on microchips is a rather recent advance in the – rather young – world of microfluidics. Here, we summarize the gradual evolutions that led from the very first “millifluidic” integrated chip for RNA analysis to more sophisticated and sensitive devices. We show how the developments of an initially applied problematic (creating portable integrated devices for e.g. point of care analysis) are finally used for studies of fundamental importance in cell biology. Two main families of devices are found in the literature: those integrating multiple steps to carry out RNA reverse transcription and DNA amplification separately, and those that take advantage of the recent developments of biology chemicals to perform RNA analysis in a single step. The latter are generally highly sensitive, and single cell RNA analysis has been made possible in very low volume handling systems. Nevertheless, in contrast to some other microfluidics biological applications, there remains room for progress in miniaturized gene expression analysis. Further efforts are still needed to provide reliable tools for use in applied biology as well as in fundamental research.
A Concrete Case: A Microfluidic Device for Single Cell Whole Transcriptome Analysis
Authors: Bontoux Nathalie , Dauphinot Luce , Potier Marie-Claude
Published: October 2010

Single cell whole transcriptome analysis, i.e. the analysis of all the genes that are expressed by a cell at a given time and under given physiological or pathological conditions, constitutes a major challenge in understanding cellular diversity and the complexity of living organisms. Indeed, such analyses will be key in unravelling cellular regulatory networks and understanding cell growth, differentiation and migration mechanisms.1 They are also of significant interest for diagnosis and could prove a very efficient tool to identify new therapeutic targets.2

With the recent development of DNA microarrays, the transcriptome, i.e. the expression of all the genes, can now be studied in a single experiment. However, current labelling and detection methods require a starting amount of total RNA of about 100ng, which is around 104 times more than the content of a single cell. The sensitivity thus undoubtedly needs to be improved to achieve accurate single cell whole transcriptome analysis. In this context, microfluidic devices offer interesting perspectives since they enable studies to be performed at the pico or nanoliter scale.

In this chapter, we will detail our microfluidic approach for whole gene profiling of single cells. We will briefly review the choice of protocols for single cell transcriptome amplification as well as materials and techniques that can be used to fabricate microfluidic devices. We will describe the integration of the reverse-transcription (RT) and polymerase chain reaction (PCR) steps on chip and then discuss how all the steps of the biological protocol can be integrated in a single lab-on-a-chip.
Tiny Droplets for High-throughput Cell-based Assays
Authors: Baret J.-C. , Taly V.
Published: October 2010

In order to perform a high number of assays on biological objects or chemical compounds which are sometimes impossible to obtain in large quantities, miniaturizing experiments has been the main issue. Standard technologies, such as microtiter plates have nearly reached the smallest sizes of samples they can handle. In order to miniaturize the assays, a further decrease in the size of the reactors in which reactions are performed is required. The use of small droplets provides new ways to miniaturize assays; moreover droplets are ideal for compartmentalizing biological objects or compounds. Droplets of equal sizes are produced in series and manipulated on demand providing quantitative and miniaturized versions of the microtiter plate assays and enables the parallelization of the assay.

In this chapter we will review droplet-based microfluidics: droplet production, flow, fusion, sorting, and detection. We will discuss how to design reactions in droplets and particularly how to maintain living cells in droplets and run biological reactions.
New Detection Methods for Single Cells
Authors: Fort Emmanuel
Published: October 2010

The major factors that have limited the use of DNA microarrays in research and diagnostics are the amount of target needed, the detection specificity, as well as the cost and reliability of detection equipment and assays. While the current gold standard for detection is fluorescence technology, the emphasis on more efficient and sensitive instrumentation has spurred the development of a number of new labeling and detection methodologies. Recent reports have demonstrated that alternative techniques like semiconductor or metal nanoparticle labels or electrochemical detection techniques could eliminate the need for target amplification steps such as PCR. Besides, the improvements in labeling technology enabled multiplexing by increasing the number of detectable colour channels and direct tracking of gene expression inside living cells.

This chapter is devoted to the latest developments in terms of hybridization techniques and read-out technologies that are promising for enhanced detection and quantification of specific gene sequences. These techniques are widely used in two emerging trends: the bio-barcode strategy and live-cell imaging.
Strategies for the plant‐based expression of dengue subunit vaccines
Authors: Yap Yun‐Kiam , Smith Duncan R.
Published: October 2010

Despite significant efforts in many countries, there is still no commercially viable dengue vaccine. Currently, attention is focused on the development of either live attenuated vaccines or live attenuated chimaeric vaccines using a variety of backbones. Alternate vaccine approaches, such as whole inactivated virus and subunit vaccines are in the early stages of development, and are each associated with different problems. Subunit vaccines offer the advantage of providing a uniform antigen of well‐defined nature, without the added risk of introducing any genetic material into the person being inoculated. Preliminary trials of subunit vaccines (using dengue E protein) in rhesus monkeys have shown promising results. However, the primary disadvantages of dengue subunit vaccines are the low levels of expression of dengue proteins in mammalian or insect cells, as well as the added unknown risks of antigens produced from mammalian cells containing other potential sources of contamination. In the past two decades, plants have emerged as an alternative platform for expression of biopharmaceutical products, including antigens of bacterial, fungal or viral origin. In the present minireview, we highlight the current plant expression technologies used for expression of biopharmaceutical products, with an emphasis on plants as a production system for dengue subunit vaccines.
The Relevance of Bilingualism Questionnaires in the Personalized Treatment of Bilinguals With Aphasia
Authors: Centeno José G.
Published: October 2010

Bilingualism questionnaires are important intake instruments to develop clinically useful individual bilingualism histories on dual-language users. Insights from these questionnaires enhance diagnostic difference-versus-disorder determinations and therapeutic suitability. The relevance of bilingualism questionnaires, often stressed in the case of pediatric bilingual cases, has received minimal attention in aphasia rehabilitation with bilinguals. This article discusses the development and implementation of systematic bilingualism questionnaires to gather pre-morbid experiential insights on bilinguals with critical value in the design of personalized, social aphasia intervention that would maximize plausible linguistic, cultural, and cognitive interactions affecting language recovery.
Accurate and reliable image classification by using conformal predictors in the TJ-II Thomson scattering
Authors: Vega J. , Murari A. , Pereira A. , González S. , Pastor I.
Published: October 2010

The charge-coupled device camera of the TJ-II Thomson scattering (TS) can capture five different classes of images. Typically, different data processing is performed depending on the kind of image that is acquired. The procedure can be automated to recognize the type of image. To this end, machine learning methods (MLM) are applied. However, usually, MLM classify without confidence estimates. An image classifier based on conformal predictors has been developed for the TJ-II TS. It provides a couple of indicators (confidence and credibility) for each classification that measures the accuracy and reliability of the prediction. Results achieve success rates of about 97%. The implemented classifier is valid for any kind of images.
Photoacoustic cell for ultrasound contrast agent characterization
Authors: Alippi A. , Bettucci A. , Biagioni A. , D’Orazio A. , Germano M. , Passeri D.
Published: October 2010

Photoacoustics has emerged as a tool for the study of liquid gel suspension behavior and has been recently employed in a number of new biomedical applications. In this paper, a photoacoustic sensor is presented which was designed and realized for analyzing photothermal signals from solutions filled with microbubbles, commonly used as ultrasound contrast agents in echographic imaging techniques. It is a closed cell device, where photothermal volume variation of an aqueous solution produces the periodic deflection of a thin membrane closing the cell at the end of a short pipe. The cell then acts as a Helmholtz resonator, where the displacement of the membrane is measured through a laser probe interferometer, whereas photoacoustic signal is generated by a laser chopped light beam impinging onto the solution through a glass window. Particularly, the microbubble shell has been modeled through an effective surface tension parameter, which has been then evaluated from experimental data through the shift of the resonance frequencies of the photoacoustic sensor. This shift of the resonance frequencies of the photoacoustic sensor caused by microbubble solutions is high enough for making such a cell a reliable tool for testing ultrasound contrast agent, particularly for bubble shell characterization.
A large volume cell for in situ neutron diffraction studies of hydrothermal crystallizations
Authors: Xia Fang , Qian Gujie , Brugger Joël , Studer Andrew , Olsen Scott , Pring Allan
Published: October 2010

A hydrothermal cell with 320 ml internal volume has been designed and constructed for in situ neutron diffraction studies of hydrothermal crystallizations. The cell design adopts a dumbbell configuration assembled with standard commercial stainless steel components and a zero-scattering Ti–Zr alloy sample compartment. The fluid movement and heat transfer are simply driven by natural convection due to the natural temperature gradient along the fluid path, so that the temperature at the sample compartment can be stably sustained by heating the fluid in the bottom fluid reservoir. The cell can operate at temperatures up to 300 °C and pressures up to 90 bars and is suitable for studying reactions requiring a large volume of hydrothermal fluid to damp out the negative effect from the change of fluid composition during the course of the reactions. The capability of the cell was demonstrated by a hydrothermal phase transformation investigation from leucite (KAlSi2O6) to analcime (NaAlSi2O6⋅H2O) at 210 °C on the high intensity powder diffractometer Wombat in ANSTO. The kinetics of the transformation has been resolved by collecting diffraction patterns every 10 min followed by Rietveld quantitative phase analysis. The classical Avrami/Arrhenius analysis gives an activation energy of 82.3±1.1 kJ mol−1. Estimations of the reaction rate under natural environments by extrapolations agree well with petrological observations.
Development of a nuclear magnetic resonance system for in situ analysis of hydrogen storage materials under high pressures and temperatures
Authors: Hashimoto S. , Noda Y. , Maekawa H. , Takamura H. , Fujito T. , Moriya J. , Ikeda T.
Published: October 2010

A NMR system for in situ analysis of hydrogen storage materials under high pressure and temperature conditions was developed. The system consists of a gas pressure and flow rate controlling unit, a temperature controller, a high temperature NMR probe tunable for both H1 and other nuclei, and a sample tube holder. Sample temperature can be controlled up to 623 K by heated N2 gas flow. Sample tube atmosphere can be substituted by either H2 or Ar and can be pressurized up to 1 MPa under constant flow rate up to 100 ml/min. During the NMR measurement, the pressure can be adjusted easily by just handle a back pressure valve. On the blank NMR measurement, H1 background noise was confirmed to be very low. H1 and B11 NMR spectrum of LiBH4 were successfully observed at high temperature for the demonstration of the system. The intensity of the H1 NMR spectra of H2 gas was also confirmed to be proportional to the applied pressure.
Development and irradiation test of lost alpha detection system for ITER
Authors: Nishiura M. , Nagasaka T. , Fujioka K. , Fujimoto Y. , Tanaka T. , Ido T. , Yamamoto S. , Kashiwa S. , Sasao M.
Published: October 2010

We developed a lost alpha detection system to use in burning plasma experiments. The scintillators of Ag:ZnS and polycrystalline Ce:YAG were designed for a high-temperature environment, and the optical transmission line was designed to transmit from the scintillator to the port plug. The required optical components of lenses and mirrors were irradiated using the fission reactor with the initial result that there was no clear change after the irradiation with a neutron flux of 9.6×1017 nm−2 s−1 for 48 h. We propose a diagnostic of alpha particle loss, so-called alpha particle induced gamma ray spectroscopy. The initial laboratory test has been carried out by the use of the Ce doped Lu2SiO5 scintillator detector and an Am–Be source to detect the 4.44 MeV high energy gamma ray due to the B9e(α,nγ)C12 reaction.
Kinetic driven turbulence: Structure in space and time
Authors: Parashar T. N. , Servidio S. , Breech B. , Shay M. A. , Matthaeus W. H.
Published: October 2010

The structure in space and time of a driven turbulent magnetoplasma is analyzed using kinetic simulations. For a two dimensional case with a strong uniform out-of-plane magnetic field, large scale driving produces a turbulent state that spans fluid scales to kinetic proton scales. There are fluid electrons in this hybrid representation. In near steady conditions, spectral analysis shows an almost complete absence of discrete point spectral features that would be associated with a dispersion relation and wave activity. While there is indication of a low level of wave activity, the results show that the dynamics are dominated by nonlinear activity. Implications for understanding plasma cascade, dissipation, and heating are discussed.
Laser ablated zirconium plasma: A source of neutral zirconium
Authors: Yadav Dheerendra , Thareja Raj K.
Published: October 2010

The authors report spectroscopic investigations of laser produced zirconium (Zr) plasma at moderate laser fluence. At low laser fluence the neutral zirconium species are observed to dominate over the higher species of zirconium. Laser induced fluorescence technique is used to study the velocity distribution of ground state neutral zirconium species. Two-dimensional time-resolved density distributions of ground state zirconium is mapped using planner laser induced fluorescence imaging and total ablated mass of neutral zirconium atoms is estimated. Temporal and spatial evolutions of electron density and temperature are discussed by measuring Stark broadened profile and ratio of intensity of emission lines, respectively.
Regimes for experimental tests of kinetic effects in dust acoustic waves
Authors: Tolias P. , Ratynskaia S. , de Angelis U.
Published: October 2010

The low frequency responses of a kinetic model of dusty plasma, taking into account the absorption of the plasma particles on the dust particles and fluctuations of dust charge, are evaluated numerically in order to identify realistic experimental parameter regimes where charging effects are dominant. A range of parameters in terms of dust number density and size as well as plasma densities, where significant differences with the multicomponent approach can be found, is proposed. General expressions for the imaginary parts of the low frequency responses are derived and numerical results for the damping rate in the corresponding ranges are provided to ensure that observations of dust-acoustic waves in those conditions are plausible.
Superresolution confocal technology for displacement measurements based on total internal reflection
Authors: Kuang Cuifang , Ali M. Yakut , Hao Xiang , Wang Tingting , Liu Xu
Published: October 2010

In order to achieve a higher axial resolution for displacement measurement, a novel method is proposed based on total internal reflection filter and confocal microscope principle. A theoretical analysis of the basic measurement principles is presented. The analysis reveals that the proposed confocal detection scheme is effective in enhancing the resolution of nonlinearity of the reflectance curve greatly. In addition, a simple prototype system has been developed based on the theoretical analysis and a series of experiments have been performed under laboratory conditions to verify the system feasibility, accuracy, and stability. The experimental results demonstrate that the axial resolution in displacement measurements is better than 1 nm in a range of 200 nm which is threefold better than that can be achieved using the plane reflector.
Undamped collective surface plasmon oscillations along metallic nanosphere chains
Authors: Jacak W. , Krasnyj J. , Jacak J. , Chepok A. , Jacak L. , Donderowicz W. , Hu D. Z. , Schaadt D. M.
Published: October 2010

The random-phase-approximation semiclassical scheme for describing plasmon excitations in large metallic nanospheres (with radius ∼10–60 nm) is developed for the case when a dynamical electric field is present. The spectrum of plasmons in metallic nanospheres is determined including both surface and volume-type excitations and their mutual connections. It is demonstrated that only dipole-type surface plasmons can be excited by a homogeneous dynamical electric field. The Lorentz friction due to irradiation of electromagnetic energy by plasmon oscillations is analyzed with respect to sphere dimension. The resulting shift in resonance frequency due to plasmon damping is compared with experimental data for various sphere radii. Wave-type collective oscillations of surface plasmons in long chains of metallic nanospheres are described. The undamped region for collective plasmon propagation along the metallic chain is found in agreement with previous numerical simulations.
Temperature dependence of hole mobility in GaAs1−xBix alloys
Authors: Beaton D. A. , Lewis R. B. , Masnadi-Shirazi M. , Tiedje T.
Published: October 2010

The Hall mobility of holes has been measured in GaAs grown at low temperatures and in GaAs1−xBix alloys for Bi concentrations x ranging from 0.94% to 5.5%. The hole mobility is found to decrease with increasing Bi content. The temperature dependence of the mobility in the 25 to 300 K range is fit with a combination of phonon scattering, ionized impurity scattering, and Bi related scattering. The hole scattering cross-section for an isolated Bi impurity is estimated to be 0.2 nm2. The temperature independent mobility at the highest Bi concentration (x=5.5%), is interpreted as being limited by scattering from Bi clusters.
Influence of surface topography and chemical structure on wettability of electrodeposited ZnO thin films
Authors: Patra S. , Sarkar S. , Bera S. K. , Paul G. K. , Ghosh R.
Published: October 2010

The wettability of electrodeposited zinc oxide (ZnO) thin films has been rationally controlled by individually engineering surface topography and surface chemical structure. We have studied the wettability of hydrophobic ZnO thin films that were rendered ultrahydrophobic by coating with low surface-energy self-assembled monolayer of octadecyltrichlorosilane and also hydrophilized by annealing at elevated temperature in air ambient. The as deposited ZnO film was hydrophobic with contact angle of around 105°±3° against water, while the annealed films were distinctly hydrophilic. The silanized films were ultrahydrophobic with a contact angle of 143°±3°. The films could be successfully tailored to obtain hydrophilic, hydrophobic as well as ultrahydrophobic behavior. It is likely that similar tunable wetting behavior may be observed in other oxide materials also.

At the request of the authors, this article is being retracted effective 1 August 2011.
Phase-change activities on gallium-doped indium oxide
Authors: Wang S.-L. , Peng L.-H.
Published: October 2010

This study investigated the phase-change activities on a gallium-doped indium oxide (Ga:InO) device that can be supplied with a constant heat flow via symmetric contact to a pair of rodlike heating elements. A device set/reset current of 0.8/18 μA and resistance window of 2.6×105 to 107 Ω can be found on Ga:InO with a 6.2 μm2 device area and a thickness of 40 nm. Analysis of a log-log plot revealed slopes of 1.07±0.01 and −1.12±0.03 that were found to correlate with the switching current and resistance change between the high-/low-value states of the Ga:InO device area, respectively. These observations lead to the estimated energy densities of 1.77±0.11 pJ/μm3 and 7.26±0.44 pJ/μm3 required to initiate the set and reset process in Ga:InO, respectively. Through differential scanning calorimetry analysis and acceleration tests of the Ga:InO film and the device, an activation energy of ∼1.275±0.005 eV was found, which corresponded to the high-/low-resistance state change. A data retention time of ten years was further estimated when the Ga:InO device is operated at 75 °C. According to the transmission electron microscopy analysis, these observations are correlated with an amorphous to cubic phase transition in In2O3, which takes place at a crystallization temperature of 252 °C, and suggest that the phase-change activities originate from the Joule heating effect.
Evidence of quantum correction to conductivity in strained epitaxial LaNiO3 films
Authors: Kumar Yogesh , Choudhary R. J. , Singh Abhinav Pratap , Anjum G. , Kumar Ravi
Published: October 2010

We have deposited epitaxial thin films of LaNiO3 (LNO) on LaAlO3 (001) single crystals by rf-magnetron sputtering. Further, we studied the effect of systematically varied swift heavy ion irradiation induced strain on structural, electrical, and magnetotransport properties of the films. Deposited films were irradiated at varying fluence (1×1011, 1×1012, and 5×1012 ions/cm2) using 200 MeV Ag15+ beam. X-ray diffraction results reveal c-axis oriented epitaxial growth of the LNO film which is maintained even up to the highest fluence. All the films, except the one irradiated with highest fluence, show metallic behavior along with a resistivity upturn at lower temperatures. Film irradiated with the highest fluence value exhibits semiconducting behavior in the studied temperature range. Low temperature resistivity of the metallic films has been explained by quantum corrections to conductivity and it is observed that localization increases with the disorder. Presence of weak localization in metallic films is also supported by our magnetotransport data. At high temperatures, variable range hopping shown by the film irradiated with the highest fluence confirms the semiconducting behavior, which may be due to the disorder induced localization of charge carriers.
Origin of the size-dependence of the polarizability per atom in heterogeneous clusters: The case of AlP clusters
Authors: Krishtal Alisa , Senet Patrick , Van Alsenoy Christian
Published: October 2010

An analysis of the atomic polarizabilities α in stoichiometric aluminum phosphide clusters, computed at the MP2 and density functional theory (DFT) levels, the latter using the B3LYP functional, and partitioned using the classic and iterative versions of the Hirshfeld method, is presented. Two sets of clusters are examined: the ground-state AlnPn clusters (n=2–9) and the prolate clusters (Al2P2)N and (Al3P3)N (N≤6). In the ground-state clusters, the mean polarizability per atom, i.e., α/2n, decreases with the cluster size but shows peaks at n=5 and at n=7. We demonstrate that these peaks can be explained by a large polarizability of the Al atoms and by a low polarizability of the P atoms in Al5P5 and Al7P7 due to the presence of homopolar bonds in these clusters. We show indeed that the polarizability of an atom within an AlnPn cluster depends on the cluster size and the heteropolarity of the bonds it forms within the cluster, i.e., on the charges of the atoms. The polarizabilities of the fragments Al2P2 and Al3P3 in the prolate clusters were found to depend mainly on their location within the cluster. Finally, we show that the iterative Hirshfeld method is more suitable than the classic Hirshfeld method for describing the atomic polarizabilities and the atomic charges in clusters with heteropolar bonds, although both versions of the Hirshfeld method lead to similar conclusions.
High energy photocathodes for laser fusion diagnostics
Authors: Halvorson C. , Houck T. , Macphee A. , Opachich Y. P. , Lahowe D. , Copsey B.
Published: October 2010

Laser fusion experiments at the National Ignition Facility require time-resolved x-ray images of the ignition target self-emission. The photon energies are expected to be greater than 10 keV. Photoemission quantum yield measurement data and photoelectron energy spectrum data are presently unavailable in this photon energy range, but are essential in the design of x-ray imaging diagnostics. We developed an apparatus to measure the quantum efficiency of primary and secondary photoelectron emission and to estimate the energy spectrum of the secondary photoelectrons. The apparatus has been tested using photon energies less than 10 keV to allow comparisons with prior work. A method for preparing photocathodes with geometrically enhanced photoefficiency has been developed.
Electric field induced magnetization of multiferroic horizontal heterostructures
Authors: Zhong Chong Gui , Ji Xian Ming , Zhao Yong Lin , Zhou Peng Xia , Cao Hai Xia , Dong Zheng Chao
Published: October 2010

A model magnetoelectric system composed of a magnetostrictive film deposited on a ferroelectric single crystal is investigated by the phenomenological thermodynamic theory, in which the magnetocrystalline anisotropic energy, the magnetic-elastic energy, and applied electric energy, and so on are considered. The results show that upon applying the out-of-plane electric field, the in-plane magnetization of the heterostructures increases and out-of-plane magnetization decreases. The relative changes in electric field induced magnetization are discussed for both in-plane and out-of-plane cases. The analysis of the results indicated that through elastic coupling of the interface between the magnetostrictive films and ferroelectric substrates, the electric field induced change in magnetic anisotropy plays an important role in the magnetoelectric coupling in the heterostructures.
(
q
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μ
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and (p,q,ζ)-exponential functions: Rogers–Szegő polynomials and Fourier–Gauss transform
Authors: Hounkonnou Mahouton Norbert , Nkouankam Elvis Benzo Ngompe
Published: October 2010

From the realization of q-oscillator algebra in terms of generalized derivative, we compute the matrix elements from deformed exponential functions and deduce generating functions associated with Rogers–Szegő polynomials as well as their relevant properties. We also compute the matrix elements associated with the (p,q)-oscillator algebra (a generalization of the q-one) and perform the Fourier–Gauss transform of a generalization of the deformed exponential functions.
Metamaterials design using gradient-free numerical optimization
Authors: Diest Kenneth , Sweatlock Luke A. , Marthaler Daniel E.
Published: October 2010

We apply numerical optimization methods in combination with full-field electromagnetic simulations to tailor the broadband spectral response of gold and silver split-ring resonator metamaterials. A derivative-free, nonlinear mesh adaptive search technique was used to drive finite-difference time-domain simulations. This algorithm allows the designer to independently vary the spectral position of the two resonant peaks and their relative reflection amplitudes throughout a wide range of the near infrared. An application of this method is then shown to design split-ring resonator “notch filters,” with narrow pass bands at 1310, 1550, and 1800 nm which have an ∼45% change in reflectivity at the pass band and corresponding linewidths of ∼90 meV.
Electrical properties and x-ray photoelectron spectroscopy studies of Bi(Zn0.5Ti0.5)O3 doped Pb(Zr0.4Ti0.6)O3 thin films
Authors: Tang M. H. , Zhang J. , Xu X. L. , Funakubo H. , Sugiyama Y. , Ishiwara H. , Li J.
Published: October 2010

( 1 − x ) Pb ( Zr 0.4 , Ti 0.6 ) O 3 – ( x ) Bi ( Zn 0.5 , Ti 0.5 ) O 3 (PZT-BZT) (x=0, 0.03, 0.05, 0.08, and 0.1) films were deposited on Pt(111)/Ti/SiO2/Si(100) substrates by chemical solution deposition using spin-coating. All samples showed highly (111) oriented perovskite phase and no other phase was observed. The ferroelectric properties of PZT-BZT films were systematically investigated as a function of the content x of the BZT solution. It is found that BZT doping in PZT films could greatly enhance the remnant polarization (Pr), as well as improve the fatigue property. In a 3 wt % BZT-doped PZT film, the 2Pr and the coercive field (Ec) are 90 μC/cm2 and 95 kV/cm at 10 kHz, respectively, at an electric field of 500 kV/cm, and the leakage current density is less than 1×10−7 A/cm2. The impact of BZT doping on the structure of PZT has been investigated by x-ray photoelectron spectroscopy.
Organic and inorganic relaxor ferroelectrics with giant electrocaloric effect
Authors: Lu S. G. , Rožič B. , Zhang Q. M. , Kutnjak Z. , Li Xinyu , Furman E. , Gorny Lee J. , Lin Minren , Malič B. , Kosec M. , Blinc R. , Pirc R.
Published: October 2010

The electrocaloric effect (ECE) in inorganic thin film and organic relaxor ferroelectrics is investigated by directly measuring the ECE around room temperature. The results reveal that giant ECEs can be obtained in the high energy electron irradiated poly(vinylidene fluoride-trifluoroethylene) relaxor copolymer and in the La-doped Pb(ZrTi)O3 relaxor ceramic thin films, which are much larger than that from the normal ferroelectric counterparts. The large ECE observed, compared with normal ferroelectrics, is likely caused by the large number of disordered fluctuating polarization entities in relaxor ferroelectrics which can lead to extra entropy contributions and larger ECE.
Terahertz heterodyne spectrometer using a quantum cascade laser
Authors: Ren Y. , Hovenier J. N. , Higgins R. , Gao J. R. , Klapwijk T. M. , Shi S. C. , Bell A. , Klein B. , Williams B. S. , Kumar S. , Hu Q. , Reno J. L.
Published: October 2010

A terahertz (THz) heterodyne spectrometer is demonstrated based on a quantum cascade laser (QCL) as a local oscillator (LO) and an NbN hot electron bolometer as a mixer, and it is used to measure high-resolution molecular spectral lines of methanol (CH3OH) between 2.913–2.918 THz. The spectral lines are taken from a gas cell containing methanol gas and using a single-mode QCL at 2.9156 THz as an LO, which is operated in the free running mode. By increasing the pressure of the gas, line broadening and saturation are observed. The measured spectra showed good agreement with a theoretical model.
High room temperature ferromagnetic moment of Ho substituted nanocrystalline BiFeO3
Authors: Thakuria Pankaj , Joy P. A.
Published: October 2010

Magnetic properties of trivalent rare-earth ion substituted nanocrystalline BiFeO3 have been studied for the compositions Bi0.875R0.125FeO3 (R=La, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, and Yb). All compositions show ferromagnetic characteristics at room temperature, with enhanced magnetization after substitution. Very high magnetization (at 6 T), almost three times that of the unsubstituted composition, is observed for R=Ho, and highest remnant magnetization is obtained for R=Nd and Sm. The magnetic transition temperature is increased by ∼20 K for R=La. The results show that it is possible to tune the magnetic characteristics of the nanocrystalline multiferroic BiFeO3 by the choice of the rare-earth ion.
Trapping in high-k dielectrics
Authors: Rao Rosario , Simoncini Riccardo , Irrera Fernanda
Published: October 2010

In this paper, an analytical model of trapping in high-k dielectrics is proposed. It starts from the general rate equation and relies on the hypothesis that the density of states involved in the capture mechanism follows a Fermi-like distribution. Thus, the energy depth of the trap level respect to the Fermi level is explicited in the model. The model is validated comparing predictions of flat band shift (calculated integrating the density of involved states) with experimental curves measured on GdSiO metal-oxide-semiconductor capacitors in many different conditions. The energy level of the trap is extracted.
Hierarchical multilevel arrays of self-assembled gold nanoparticles: Control of resistivity-temperature dependence
Authors: Yajadda M. M. A. , Levchenko I. , Han Z. J. , Ostrikov K.
Published: October 2010

The possibility to control the electric resistivity-temperature dependence of the nanosized resistive components made using hierarchical multilevel arrays of self-assembled gold nanoparticles prepared by multiple deposition/annealing is demonstrated. It is experimentally shown that the hierarchical three-level patterns, where the nanoparticles of sizes ranging from several nanometers to several tens of nanometer play a competitive roles in the electric conductivity, demonstrate sharp changes in the activation energy. These patterns can be used for the precise tuning of the resistivity-temperature behavior of nanoelectronic components.
From Brown to Green? Assessing Social Vulnerability to Environmental Gentrification in New York City
Authors: Pearsall Hamil
Published: October 2010

Although urban sustainability programs frequently include measures that focus on the environmental and economic components of sustainability, the social dimension of sustainability remains underrepresented. An analytical vulnerability approach from global change vulnerability research provides one way to evaluate the distributional impacts and procedural aspects of sustainability initiatives. I apply the vulnerability approach to a study of one contemporary sustainability initiative in New York City, brownfield redevelopment, and identify populations who are vulnerable to the negative impacts of the redevelopment process: elderly residents, renters, and residents receiving government assistance. The results of the case study suggest that the vulnerability approach provides a way to develop indicators of social sustainability for inclusion in existing urban sustainability indicator projects.
The Biotechnology Industry in the Prague Metropolitan Region: A Cluster within a Fragmented Innovation System?
Authors: Blažek Jiří , Žížalová Pavla
Published: October 2010

Previous research on regional innovation systems (RISs) has shown that Prague is a prime example of a fragmented metropolitan RIS. Fragmented innovation systems are characterized by a strong endowment of knowledge and innovation infrastructure elements, but they suffer from a lack of local networking, cooperation, and knowledge transmission. The aim of this paper is to investigate the nature and geography of innovation, knowledge sourcing, and collaboration in the emerging and still embryonic biotechnology industry in the Prague metropolitan region. The key questions to be answered are whether this general feature of Prague's innovation system (ie its fragmented structure and the lack of local networking) can also be found in a knowledge-intensive sector, such a biotechnology, or whether sectoral drivers are more significant and the generalized ‘local buzz and global pipelines’ model can also be applied to Prague biotech firms. Our research, in contrast to previous studies, shows that relatively intensive linkages exist within the biotechnology sector. Therefore, our results imply that an RIS, even within a single city, might be more diversified and structured than existing studies and typologies of RISs have suggested.
Spatial Planning, Devolution, and New Planning Spaces
Authors: Allmendinger Phil , Haughton Graham
Published: October 2010

In this paper we put forward the case for viewing ‘spatial planning’ as a political resource, one which has been largely supportive of the rollout neoliberal approach of New Labour. Drawing on work on postpolitics, we argue that ironically the progressive credentials of spatial planning in terms of consensus building, policy integration, and the search for ‘win – win – win’ solutions may have helped script out oppositional voices. We then outline how the combination of changes to planning systems, devolution, and local government reform has not generated a ‘double dividend’ of greater planning powers devolving from new territorial administrations to local planning authorities. Instead a more complex process of creating new planning spaces has emerged after devolution. Five types of new planning spaces and spatial practices are identified, including new soft space forms of governance.
The Role of the Government in Adaptation to Climate Change
Authors: Osberghaus Daniel , Dannenberg Astrid , Mennel Tim , Sturm Bodo
Published: October 2010

Given the scarcity of resources, an economic approach is necessary in order to determine an optimal strategy of adaptation to climate change. In this paper we develop an economic framework for the study of adaptation which allows distinguishing between decentralised adaptation by private agents, on the one hand, and centralised adaptation measures by the government, on the other hand. The paper is in two parts: in the first we present the neoclassical view of adaptation policy, which is based on the paradigm of market failure. In the second part we deal with challenges and complements of the neoclassical view arising from the introduction of equity principles, security of supply concerns, and a polycentric approach to the provision of public goods. The analysis is illustrated with examples of adaptation measures in Germany.
Retrenchment or Resilience? New Evidence on Relative Social Expenditure Trends
Authors: Olaskoaga-Larrauri Jon , Aláez-Aller Ricardo , Díaz-de-Basurto Pablo
Published: October 2010

Two opposing viewpoints can be found in recent literature on trends in welfare states. The first (efficiency thesis) envisages the retrenchment of the welfare state, while the second viewpoint (the ‘resilience theory’) holds that reforms and cutbacks in some parameters of social protection will be minor and will not jeopardise the essential nature of Western states. The present study makes sense in this context of hypotheses to be tested and it proposes an alternative to the measures currently available. The measure drawn up and used in this paper could be called the ‘synthetic relative standards of protection measure’ and is based in the aggregate social spending levels. Much of the evidence gathered in this research study is consistent with the resilience thesis. The impact of reforms is by no means as drastic as posited by the champions of the efficiency thesis.
Thirty thousand-year-old evidence of plant food processing
Authors: Revedin Anna , Aranguren Biancamaria , Becattini Roberto , Longo Laura , Marconi Emanuele , Lippi Marta Mariotti , Skakun Natalia , Sinitsyn Andrey , Spiridonova Elena , Svoboda Jiří
Published: October 2010

European Paleolithic subsistence is assumed to have been largely based on animal protein and fat, whereas evidence for plant consumption is rare. We present evidence of starch grains from various wild plants on the surfaces of grinding tools at the sites of Bilancino II (Italy), Kostenki 16–Uglyanka (Russia), and Pavlov VI (Czech Republic). The samples originate from a variety of geographical and environmental contexts, ranging from northeastern Europe to the central Mediterranean, and dated to the Mid-Upper Paleolithic (Gravettian and Gorodtsovian). The three sites suggest that vegetal food processing, and possibly the production of flour, was a common practice, widespread across Europe from at least ~30,000 y ago. It is likely that high energy content plant foods were available and were used as components of the food economy of these mobile hunter–gatherers.
Endosomal sorting of readily releasable synaptic vesicles
Authors: Hoopmann Peer , Punge Annedore , Barysch Sina V. , Westphal Volker , Bückers Johanna , Opazo Felipe , Bethani Ioanna , Lauterbach Marcel A. , Hell Stefan W. , Rizzoli Silvio O.
Published: October 2010

Neurotransmitter release is achieved through the fusion of synaptic vesicles with the neuronal plasma membrane (exocytosis). Vesicles are then retrieved from the plasma membrane (endocytosis). It was hypothesized more than 3 decades ago that endosomes participate in vesicle recycling, constituting a slow endocytosis pathway required especially after prolonged stimulation. This recycling model predicts that newly endocytosed vesicles fuse with an endosome, which sorts (organizes) the molecules and buds exocytosis-competent vesicles. We analyzed here the endosome function using hippocampal neurons, isolated nerve terminals (synaptosomes), and PC12 cells by stimulated emission depletion microscopy, photooxidation EM, and several conventional microscopy assays. Surprisingly, we found that endosomal sorting is a rapid pathway, which appeared to be involved in the recycling of the initial vesicles to be released on stimulation, the readily releasable pool. In agreement with the endosomal model, the vesicle composition changed after endocytosis, with the newly formed vesicles being enriched in plasma membrane proteins. Vesicle proteins were organized in clusters both in the plasma membrane (on exocytosis) and in the endosome. In the latter compartment, they segregated from plasma membrane components in a process that is likely important for sorting/budding of newly developed vesicles from the endosome.
Keap1 perceives stress via three sensors for the endogenous signaling molecules nitric oxide, zinc, and alkenals
Authors: McMahon Michael , Lamont Douglas J. , Beattie Kenneth A. , Hayes John D.
Published: October 2010

Recognition and repair of cellular damage is crucial if organisms are to survive harmful environmental conditions. In mammals, the Keap1 protein orchestrates this response, but how it perceives adverse circumstances is not fully understood. Herein, we implicate NO, Zn
2+
, and alkenals, endogenously occurring chemicals whose concentrations increase during stress, in this process. By combining molecular modeling with phylogenetic, chemical, and functional analyses, we show that Keap1 directly recognizes NO, Zn
2+
, and alkenals through three distinct sensors. The C288 alkenal sensor is of ancient origin, having evolved in a common ancestor of bilaterans. The Zn
2+
sensor minimally comprises H225, C226, and C613. The most recent sensor, the NO sensor, emerged coincident with an expansion of the
NOS
gene family in vertebrates. It comprises a cluster of basic amino acids (H129, K131, R135, K150, and H154) that facilitate
S
-nitrosation of C151. Taken together, our data suggest that Keap1 is a specialized sensor that quantifies stress by monitoring the intracellular concentrations of NO, Zn
2+
, and alkenals, which collectively serve as second messengers that may signify danger and/or damage.