bluuebunny/crossref_metadata_2025 huggingface dataset:
Food and nutrition security and poverty alleviation in the Philippines
Authors: Angeles‐Agdeppa Imelda
Published: November 2010

Poverty, food and nutrition insecurity remain as critical problems in the Philippines. The average Filipino in 1997 needed an annual income of at least P7710 to meet food requirements or P11 319 to meet both food and non‐food requirements. Approximately 4 511 000 families (31.8%) are poor and most of these are in the rural areas. Economic growth in the country has been characterized as a ‘boom and bust’ cycle with growth derailed by a combination of natural calamities, adverse domestic political factors, energy shortages, and external shocks such as the Asian currency crisis. In 1988 the gross national product (GNP) reached a peak of 7.2% and then declined to less than 1% in 1991. The economy started to recover in 1992, and the GNP peaked at 7.2% in 1996. The Asian financial crisis, compounded by the drought in 1998, led to a fall in the output of the agricultural sector by 6.6%. A stronger world economy, however, in 1999 helped the Philippine economy to recover. The Food Balance Sheet 1997 indicates that there has been a steady increase in the aggregate net food supply in 1992−1997 with the cereals group contributing approximately 25% of the total food supply. Translating this into calorie supply, this has provided approximately 2400 kcal/person per day or approximately 25% more than 2000 kcal/day. The fact that mean per capita intake is low indicates a gap between supply, distribution and consumption. The 1998 Food and Nutrition Research Institute survey showed that nutritional deficiencies still persist. Among 0−5‐year‐old children, underweight was approximately 32.0%; stunting 34.0% and wasting 6.0%. Underweight among 6−10‐year‐olds was 30.2% while stunting was 40.8%. Vitamin A deficiency, iron deficiency anaemia and iodine deficiency disorder continue as public health concerns. Food security and poverty alleviation are among the top priority programmes. The Medium‐Term Philippine Development Plan (1999−2004) enunciates the country's vision of creating a modern and humane society through improved quality of life characterized by food‐secure and poverty‐free Filipinos, in an ecologically healthy state. The different government programmes are the following: the Agriculture and Fisheries Modernization Act of 1997 provides the blueprint for developing and modernizing the agriculture and fisheries sectors; the National Anti‐Poverty Alleviation Commission was created as the coordinating and advisory body for the implementation of poverty eradication programmes of the different sectors; the vision of the Medium‐Term Philippine Plan of Action for Nutrition is of a nutritionally improved country whose people are well nourished, healthy, intelligent, and socially and economically productive with a strong sense of human dignity.
Noninvasive Visualization of Atherosclerotic Plaque with Electron Beam and Multislice Spiral Computed Tomography
Authors: NIEMAN KOEN , VAN DER LUGT AAD , PATTYNAMA PETER MT , DE FEYTER PIM J
Published: November 2010

As an alternative to intracoronary modalities, electron beam computed tomography (EBCT) and multislice spiral computed tomography (MSCT) are able to noninvasively image the coronary arteries. In addition to stenosis detection by imaging the vessel lumen, MSCT has the ability to visualize the coronary artery wall. By using computed tomography (CT), the various components of atherosclerotic plaque may be distinguished and characterized, which holds the promise of, eventually, identifying vulnerable plaque. (J Interven Cardiol 2003;16:123–128)
Integrated microfluidic probe station
Authors: Perrault C. M. , Qasaimeh M. A. , Brastaviceanu T. , Anderson K. , Kabakibo Y. , Juncker D.
Published: November 2010

The microfluidic probe (MFP) consists of a flat, blunt tip with two apertures for the injection and reaspiration of a microjet into a solution—thus hydrodynamically confining the microjet—and is operated atop an inverted microscope that enables live imaging. By scanning across a surface, the microjet can be used for surface processing with the capability of both depositing and removing material; as it operates under immersed conditions, sensitive biological materials and living cells can be processed. During scanning, the MFP is kept immobile and centered over the objective of the inverted microscope, a few micrometers above a substrate that is displaced by moving the microscope stage and that is flushed continuously with the microjet. For consistent and reproducible surface processing, the gap between the MFP and the substrate, the MFP’s alignment, the scanning speed, the injection and aspiration flow rates, and the image capture need all to be controlled and synchronized. Here, we present an automated MFP station that integrates all of these functionalities and automates the key operational parameters. A custom software program is used to control an independent motorized Z stage for adjusting the gap, a motorized microscope stage for scanning the substrate, up to 16 syringe pumps for injecting and aspirating fluids, and an inverted fluorescence microscope equipped with a charge-coupled device camera. The parallelism between the MFP and the substrate is adjusted using manual goniometer at the beginning of the experiment. The alignment of the injection and aspiration apertures along the scanning axis is performed using a newly designed MFP screw holder. We illustrate the integrated MFP station by the programmed, automated patterning of fluorescently labeled biotin on a streptavidin-coated surface.
Linear viscoelastic properties of transient networks formed by associating polymers with multiple stickers
Authors: Indei Tsutomu , Takimoto Jun-ichi
Published: November 2010

We have developed a single-chain theory that describes dynamics of associating polymer chains carrying multiple associative groups (or stickers) in the transient network formed by themselves and studied linear viscoelastic properties of this network. It is shown that if the average number N¯ of stickers associated with the network junction per chain is large, the terminal relaxation time τA that is proportional to τXN¯2 appears. The time τX is the interval during which an associated sticker goes back to its equilibrium position by one or more dissociation steps. In this lower frequency regime ω<1/τX, the moduli are well described in terms of the Rouse model with the longest relaxation time τA. The large value of N¯ is realized for chains carrying many stickers whose rate of association with the network junction is much larger than the dissociation rate. This associative Rouse behavior stems from the association/dissociation processes of stickers and is different from the ordinary Rouse behavior in the higher frequency regime, which is originated from the thermal segmental motion between stickers. If N¯ is not large, the dynamic shear moduli are well described in terms of the Maxwell model characterized by a single relaxation time τX in the moderate and lower frequency regimes. Thus, the transition occurs in the viscoelastic relaxation behavior from the Maxwell-type to the Rouse-type in ω<1/τX as N¯ increases. All these results are obtained under the affine deformation assumption for junction points. We also studied the effect of the junction fluctuations from the affine motion on the plateau modulus by introducing the virtual spring for bound stickers. It is shown that the plateau modulus is not affected by the junction fluctuations.
Heteroepitaxy of Nd0.67Sr0.33MnO3 on silicon for bolometric x-ray detector application
Authors: Yong G. J. , Kolagani Rajeswari M. , Adhikari S. , Drury O. B. , Gardner C. , Bionta R. M. , Friedrich S.
Published: November 2010

We have recently reported the design concept and sensor fabrication for a novel bolometric x-ray detector based on a rare earth manganite material for application as a total energy monitor for the Linac Coherent Light Source (LCLS) free electron laser at the Stanford Linear Accelerator Center (SLAC). The detector employs epitaxial thin films of Nd0.67Sr0.33MnO3 grown on Si by pulsed laser deposition. In this paper we report details of the fabrication of the actual detector, its response characteristics under photon illumination from LCLS, and improvements in the growth scheme of the sensor material on Si using a buffer/template layer scheme that employs yttria-stabilized zirconia, cerium oxide (CeO2), and bismuth titanate (Bi4Ti3O12). The thermal sensor response changes linearly with the energy of an optical calibration laser as expected, and the signals from optical and x-ray pulses at LCLS are very similar, thereby validating the design concept. To the best of our knowledge, the LCLS detector application reported here is the first practical use of colossal magnetoresistive manganite bolometers.
Magnetic anisotropy and magnetization reversal of La0.67Sr0.33MnO3 thin films on SrTiO3(110)
Authors: Boschker Hans , Kautz Jaap , Houwman Evert P. , Koster Gertjan , Blank Dave H. A. , Rijnders Guus
Published: November 2010

The magnetic behavior of La0.67Sr0.33MnO3 (LSMO) films grown on SrTiO3 (110) substrates was studied. In-plane uniaxial magnetic anisotropy with the easy axis aligned with the [001] lattice direction was observed, together with an out-of-plane component. This is explained by the crystal structure of the films, which shows a tilt of the (001) planes. This tilt creates a long body diagonal which forces the easy axis out-of-plane and results in magnetic domain formation. The domain size is estimated at 500 nm. The switching behavior of the magnetization is well described by a two-phase model which takes both coherent rotation and domain wall motion into account. These results are of importance for the application of LSMO in tunnel magnetoresistance devices, where the (110) orientation is preferred because of the reduction in the dead layer in this direction.
Extreme ultraviolet emission spectra of Gd and Tb ions
Authors: Kilbane D. , O’Sullivan G.
Published: November 2010

Theoretical extreme ultraviolet emission spectra of gadolinium and terbium ions calculated with the Cowan suite of codes and the flexible atomic code (FAC) relativistic code are presented. 4d–4f and 4p–4d transitions give rise to unresolved transition arrays in a range of ions. The effects of configuration interaction are investigated for transitions between singly excited configurations. Optimization of emission at 6.775 nm and 6.515 nm is achieved for Gd and Tb ions, respectively, by consideration of plasma effects. The resulting synthetic spectra are compared with experimental spectra recorded using the laser produced plasma technique.
Case-hardening inspection of steel using photothermal phase maxima
Authors: Fivez J. , Glorieux C.
Published: November 2010

Starting from the exact solution for the photothermal signal in semi-infinite materials with an exponential and with a piecewise linear thermal conductivity profile, a set of equations valid for a broad class of profiles is derived for the direct computation of the conductivity profile depth and surface conductivity from the properties of the photothermal phase maximum alone. By virtue of the usual anticorrelation between conductivity gradient and hardening gradient, this can be used for the assessment of case depth and surface hardening of case-hardened steels. The results compare very well with the results of Vickers hardness tests. The methodology only applies to concave conductivity profiles, excluding e.g., sigmoidal shapes.
Pump-probe imaging of nanosecond laser-induced bubbles in distilled water solutions: Observations of laser-produced-plasma
Authors: Evans R. , Camacho-López S.
Published: November 2010

This article presents the analysis of the laser-produced-plasma (LPP) formed by the focusing of a 9 ns laser pulse, λ=532 nm, with a NA=0.6 aspherical lens using energies between 100–1500 μJ, into distilled water with varying solutions of table salt. Observations of the filamentation plasma were made, which are explained by self-focusing of the laser pulse by the LPP through ponderomotive cavitation of the electron plasma in the center of the beam. The filamentation of the beam through a low density plasma wave guide explains why the transmission of the pump laser through the interaction region was notably higher on previous experiments that we performed [R. Evans et al., Opt. Express 16, 7481 (2008)], than a very similar set of experiments performed by Noack and Vogel [IEEE J. Quantum Electron. 35, 1156 (1999)].
Anode modification of inverted polymer solar cells using graphene oxide
Authors: Gao Yan , Yip Hin-Lap , Hau Steven K. , O’Malley Kevin M. , Cho Nam Chul , Chen Hongzheng , Jen Alex K.-Y.
Published: November 2010

A simple method has been developed to modify the anode interface of inverted bulk-heterojunction (BHJ) polymer solar cells by spin-coating a thin layer of graphene oxide (GO) on top of the organic active layer. The device with GO exhibited a remarkable improvement in power conversion efficiency compared to devices without any interfacial layer, indicating that GO can effectively modify the BHJ/metal anode interface to facilitate efficient hole collection. The dependence of the device performance on the GO layer thickness was also investigated showing an optimum performance from a GO thickness of ∼2–3 nm.
Plasma formation in a double-gap vircator
Authors: Queller T. , Shlapakovski A. , Krasik Ya. E.
Published: November 2010

Time-resolved light emission imaging was used to observe the plasma formation within the cavity of the double-gap vircator powered by a sub-microsecond generator (∼500 kV, ∼10 kA, ∼500 ns). The vircator generated well reproducible S-band microwave pulses of ∼200 MW peak power and up to 200 ns full duration. The plasma light emission was observed ∼30 ns prior to the ending of the generated microwave pulses at the surface of the aluminum foil separating the vircator cavity gaps, in the gap where the virtual cathode is formed. Estimations showed that the energy deposition into the foil by the high-current electron beam is sufficient for the surface plasma formation. The plasma ions accelerated toward the virtual cathode neutralize its electron space charge. The latter was confirmed by the increase in the electron current transmitted through the vircator cavity. In addition, the time of the plasma appearance was determined by comparing the measured transmitted current with that following from the one-dimensional model of a stationary un-neutralized two-stream electron flow. This time agrees with the maximum of the microwave power observed in the experiments, thus showing that the plasma ions cause the termination of the microwave generation.
Biaxial and uniaxial strain effects on the ultraviolet emission efficiencies of AlxGa1−xN films with different Al concentrations
Authors: Fu D. Y. , Zhang R. , Wang B. G. , Liu B. , Xie Z. L. , Xiu X. Q. , Lu H. , Zheng Y. D. , Edwards G.
Published: November 2010

The influences of biaxial and uniaxial strain on the ultraviolet emission efficiencies of both c- and m-plane AlxGa1−xN films with different Al concentrations are investigated under the framework of k⋅p perturbation theory. The optimal high efficiency windows, for ultraviolet light emissions are quantitatively estimated. c-plane AlxGa1−xN modified by uniaxial strain, shows more advantages over biaxial-strained AlxGa1−xN. This is due to the relatively more flexible tuning range and the advantage of obtaining pure linear polarization, which can be utilized to design polarized emission devices. For m-plane AlxGa1−xN, there are always in-plane polarized emissions under both biaxial and uniaxial strain conditions, thus, it is more likely to obtain high surface emission efficiency.
Kinetic electrocaloric effect and giant net cooling of lead-free ferroelectric refrigerants
Authors: Bai Yang , Zheng Guang-Ping , Shi San-Qiang
Published: November 2010

The electrocaloric effect of BaTiO3 multilayer thick film structure was investigated by direct measurement using differential scanning calorimeter. The samples show a giant electrocaloric effect of 0.89 J/g under E=176 kV/cm, which also depends on the varying rate of applied field, following a general power-law relation. Based on the large net-cooling (0.37 J/g) resulting from the difference in the varying rates of rising and falling fields, the kinetic electrocaloric effect provides a solution for the design of refrigeration cycle in ferroelectric microrefrigerator.
On the velocity variation in atmospheric pressure plasma plumes driven by positive and negative pulses
Authors: Xiong Z. , Lu X. , Xian Y. , Jiang Z. , Pan Y
Published: November 2010

To better understand the variation in the “plasma bullet” velocity, the dynamics of an atmospheric pressure plasma plume driven by positive and negative pulses are investigated in detail. It is found that, before the plasma exits the nozzle, the plasma propagates at a speed of about 30 km/s for both positive and negative pulses. As soon as the plasma exits the nozzle, the plasma propagation speed increases dramatically for both cases. The peak velocity for the case of the positive pulse is much higher than that of the negative pulse, it is approximately 150 km/s and 70 km/s, respectively. According to the optical emission spectra, the acceleration behavior of the plasma bullet when it exits the nozzle is due to the increase in the N2+ concentration.
Regularity analysis of an individual-based ecosystem simulation
Authors: Golestani Abbas , Gras Robin
Published: November 2010

We analyze the results of a large simulation of an evolving ecosystem to evaluate its complexity. In particular, we are interested to know how close to a stochastic or a deterministic behavior our simulation is. Four methods have been used for this analysis: Higuchi fractal dimension, correlation dimension, largest Lyapunov exponent, and P&H method. Besides, we use a surrogate data test to reach a final decision about analysis. As we expect, our results show that there is a deterministic and chaotic behavior in ecosystem simulation.
Controlled large strain of Ni silicide/Si/Ni silicide nanowire heterostructures and their electron transport properties
Authors: Wu W. W. , Lu K. C. , Chen K. N. , Yeh P. H. , Wang C. W. , Lin Y. C. , Huang Yu
Published: November 2010

Unusually large and compressively strained Si in nanoheterostructures of Ni silicide/Si/Ni silicide, in which the strain of the Si region can be achieved up to 10%, has been produced with point contact reactions between Si and Ni nanowires in an ultrahigh vacuum transmission electron microscope. The growth rate and relationships between the strain and the spacing of the Si region have been measured. Based on the rate and relationships, we can control the Si dimension and, in turn, the strain of remaining Si can be tuned with appropriate spacing. Since one-dimensional nanoheterostructures may have potential applications in nanoelectronic devices, the existent strain will further affect carrier mobility and piezoresistance coefficients in the Si region. Electrical measurements on the nanodevices from such nanoheterostructures show that the current output closely correlates with the Si channel length and compressive strain.
Control of excitons by laterally modulated electrode density
Authors: Kuznetsova Y. Y. , High A. A. , Butov L. V.
Published: November 2010

We propose a method for the realization of in-plane potential landscapes for excitons by the lateral modulation of the electrode density and present traps created using this method.
Temperature dependent transport behavior of n-InN nanodot/p-Si heterojunction structures
Authors: Bhat Thirumaleshwara N. , Roul Basanta , Rajpalke Mohana K. , Kumar Mahesh , Krupanidhi S. B. , Sinha Neeraj
Published: November 2010

The present work explores the temperature dependent transport behavior of n-InN nanodot/p-Si(100) heterojunction diodes. InN nanodot (ND) structures were grown on a 20 nm InN buffer layer on p-Si(100) substrates. These dots were found to be single crystalline and grown along [001] direction. The junction between these two materials exhibits a strong rectifying behavior at low temperatures. The average barrier height (BH) was determined to be 0.7 eV from current-voltage-temperature, capacitance-voltage, and flat band considerations. The band offsets derived from built-in potential were found to be ΔEC=1.8 eV and ΔEV=1.3 eV and are in close agreement with Anderson’s model.
Determination of optimum Si excess concentration in Er-doped Si-rich SiO2 for optical amplification at 1.54 μm
Authors: Savchyn Oleksandr , Coffey Kevin R. , Kik Pieter G.
Published: November 2010

The presence of indirect Er3+ excitation in Si-rich SiO2 is demonstrated for Si-excess concentrations in the range of 2.5–37 at. %. The Si excess concentration providing the highest density of sensitized Er3+ ions is demonstrated to be relatively insensitive to the presence of Si nanocrystals and is found to be ∼14.5 at. % for samples without Si nanocrystals (annealed at 600 °C) and ∼11.5 at. % for samples with Si nanocrystals (annealed at 1100 °C). The observed optimum is attributed to an increase in the density of Si-related sensitizers as the Si concentration is increased, with subsequent deactivation and removal of these sensitizers at high Si concentrations. The optimized Si excess concentration is predicted to generate maximum Er-related gain at 1.54 μm in devices based on Er-doped Si-rich SiO2.
Extremely high T-values (∼450 K) of long-wavelength (∼15 μm), low-threshold-current-density quantum-cascade lasers based on the indirect pump scheme
Authors: Fujita Kazuue , Yamanishi Masamichi , Edamura Tadataka , Sugiyama Atsushi , Furuta Shinichi
Published: November 2010

The high device performance of a long-wavelength (∼15 μm), InGaAs/InAlAs, Fabry–Pérot quantum-cascade laser based on the indirect pump scheme is reported. As a result of felicitous designing of the active region and waveguide structure, a low threshold-current-density of ∼3.5 kA/cm2, a high maximum output power of ∼216 mW, and a high slope efficiency of ∼346 mW/A, all at room temperature are obtained. The observed extremely high characteristic temperature of threshold current, T0∼450 K over wide temperature range, 320–380 K is ascribed to a strong suppression of electron populations in injectors, which are specifically visualized in the indirect pump scheme.
Do aggregation, treading, and dung deposition affect phosphorus and suspended sediment losses in surface runoff?
Authors: Cournane Fiona Curran , McDowell Richard W. , Condron Leo M.
Published: November 2010

Cattle grazing can enhance the loss of phosphorus (P) and suspended sediment (SS) in surface runoff, which can impair receiving water bodies. We tested the hypothesis that much of the particulate-bound P in surface runoff is carried in light, low-density aggregates that may enhance the transfer of P and SS to surface water. Four contrasting soil types were treated with combinations with or without treading by an artificial hoof to simulate a 24-h grazing event, and with or without dung return. A rainfall simulator was used to generate surface runoff. Dung application enriched P and SS losses much more than treading, while losses were greater from Recent Gley and Pallic soils (New Zealand Soil Classification), which were defined as vulnerable to physical damage and slaking, as opposed to well-structured Melanic and Brown soils. Allowing runoff samples to settle showed that, according to Stoke’s law, particles that remained floating after 19.1 min (termed ‘lighter’ particles; <10 µm) accounted for a larger proportion of the P load than particles that sank after 19.1 min (termed ‘heavy’ particles; >10 µm), despite only contributing <30% of runoff volume. Furthermore, dispersion of the different sized particles showed that aggregation was significant for the lighter (<10 µm) sample, especially if treading occurred or dung was applied to the Pallic or Recent Gley soils. Caution should be practiced when grazing Recent Gley and Pallic soils because of the greater potential for P and SS loss particularly when these soils are wet and surface runoff is likely.
Herbivore-induced and floral homoterpene volatiles are biosynthesized by a single P450 enzyme (CYP82G1) in
Arabidopsis
Authors: Lee Sungbeom , Badieyan Somayesadat , Bevan David R. , Herde Marco , Gatz Christiane , Tholl Dorothea
Published: November 2010

Terpene volatiles play important roles in plant-organism interactions as attractants of pollinators or as defense compounds against herbivores. Among the most common plant volatiles are homoterpenes, which are often emitted from night-scented flowers and from aerial tissues upon herbivore attack. Homoterpene volatiles released from herbivore-damaged tissue are thought to contribute to indirect plant defense by attracting natural enemies of pests. Moreover, homoterpenes have been demonstrated to induce defensive responses in plant–plant interaction. Although early steps in the biosynthesis of homoterpenes have been elucidated, the identity of the enzyme responsible for the direct formation of these volatiles has remained unknown. Here, we demonstrate that CYP82G1 (At3g25180), a cytochrome P450 monooxygenase of the
Arabidopsis
CYP82 family, is responsible for the breakdown of the C
20
-precursor (
E
,
E
)-geranyllinalool to the insect-induced C
16
-homoterpene (
E
,
E
)-4,8,12-trimethyltrideca-1,3,7,11-tetraene (TMTT). Recombinant CYP82G1 shows narrow substrate specificity for (
E
,
E
)-geranyllinalool and its C
15
-analog (
E
)-nerolidol, which is converted to the respective C
11
-homoterpene (
E
)-4,8-dimethyl-1,3,7-nonatriene (DMNT). Homology-based modeling and substrate docking support an oxidative bond cleavage of the alcohol substrate via
syn
-elimination of the polar head, together with an allylic C-5 hydrogen atom.
CYP82G1
is constitutively expressed in
Arabidopsis
stems and inflorescences and shows highly coordinated herbivore-induced expression with geranyllinalool synthase in leaves depending on the F-box protein COI-1. CYP82G1 represents a unique characterized enzyme in the plant CYP82 family with a function as a DMNT/TMTT homoterpene synthase.
Probing magnetization dynamics of strongly interacting magnetic nanoparticles through magnetoresistive current noise measurements
Authors: Taub Nurit , Markovich Gil
Published: November 2010

The dependence of tunnelling current fluctuations on temperature and magnetic field was studied in an organically capped magnetite (Fe3O4) nanocrystal (NC) array deposited between 30 nm spaced gold electrodes. Low-frequency Lorentzian (random telegraph) noise was observed around the magnetization freezing temperature due to magnetic moment switching of the NCs under zero magnetic fields, diminishing with a saturating magnetic field. The temperature dependence of current fluctuations followed the temperature dependence of magnetic susceptibility. This work offers a new tool for locally studying collective magnetization dynamics in strongly interacting magnetic NC arrays.
Hydrodynamic Instabilities Driven by Acid-base Neutralization Reaction in Immiscible System
Authors: Asad Ahmed , Yang Ya-hui , Chai Chuan , Wu Jiang-tao
Published: November 2010

The hydrodynamic instabilities driven by an acid-base neutralization reaction, in contact along a plane interface, placed in a Hele-Shaw cell under the gravitational field are reported. The system consists of the heavier aqueous tetramethyle-ammonium hydroxide below the lighter layer of organic phase with propionic acid as reacting specie. The effect of chemical composition on hydrodynamic instabilities during interfacial mass transfer accompanied by a neutralization reaction is investigated. Depending on the initial concentration of the reacting species, Marangoni convection in the form of roll cells or trains of waves is observed. Mach-Zehnder interferometer is used to measure the change in base concentration at the time of instability formation. The results show that the instabilities resulted from the convection flow are more efficient to the mechanism of mass transfer and can drastically alter pattern formation in the system.
First-principles Studies on Electronic Structures of Ga-doped ZnO and ZnS
Authors: Li Ping , Deng Sheng-hua , Zhang Li , Li Yi-bao , Yu Jiang-ying , Liu Dong
Published: November 2010

First-principles calculations have been performed to clarify the differences of the electronic structures of Ga-doped ZnO and ZnS. Results show the local density approximation and local density approximation+U calculations are in good qualitative agreement with each other. After doping, impurity states appear near the Fermi level in both ZnO and ZnS cases. When ZnO is doped, the impurity states are delocalized in the whole conduction band. On the contrary, when ZnS is doped, though the p state of Ga is also delocalized, the s state is localized near the Fermi level. Partial charge density distributions of the frontier orbital show the same information. After an exchange of the crystal structures of ZnO and ZnS, results remain unchanged. The localized Ga s state accounts for the bad electrical properties of Ga-doped ZnS.
DFT Study of Alkali Metal Atom Adsorption on Defect-Free MgO(001) Surface
Authors: Xu Run , Gong Wei-ming , Zhang Xu , Wang Lin-jun , Hong Feng
Published: November 2010

The adsorption of isolated alkali metal atoms (Li, Na, K, Rb, and Cs) on defect-free surface of MgO(001) has been systemically investigated with density functional theory using a pseudopotential plane-wave approach. The adsorption energy calculated is about −0.72 eV for the lithium on top of the surface O site and about one third of this value for the other alkali metals. The relatively strong interaction of Li with the surface O can be explained by a more covalent bonding involved, evidenced by results of both the projected density of states and the charge density difference. The bonding mechanism is discussed in detail for all alkali metals.
Structural, Magnetic, and Electrical Properties of Al3+ Substituted CuZn-ferrites
Authors: M. Ramay S. , A. Siddiqi Saadat , Atiq S. , S. Awan M. , Riaz S.
Published: November 2010

Nanocrystalline Cu0.5Zn0.5AlxFe2−xO2 (x=0.0, 0.1, 0.2, 0.3, 0.4, and 0.5) ferrite materials were synthesized using standard solid state reaction technique. The effects of Al3+ contents on the structural, electrical, and magnetic properties were investigated. Single phase cubic spinel structure was revealed by X-ray diffraction analysis. The crystallite size was evaluated considering the most intense diffraction peak (311) using Scherrer formula. Lattice constant decreased, whereas porosity increased with the increase in Al3+ concentration. The value of saturation magnetization decreased with increasing aluminum contents. Temperature dependent value of direct current electrical resistivity has been determined. It is observed that the substitution of Al3+ has significant impact on the dielectric constant, tangent of dielectric loss angle and dielectric loss factor. The variation in dielectric properties was attributed to space charge polarization.
Contributions of chaperone/usher systems to cell binding, biofilm formation and Yersinia pestis virulence
Authors: Felek Suleyman , Jeong Jenny J. , Runco Lisa M. , Murray Susan , Thanassi David G. , Krukonis Eric S.
Published: November 2010

Yersinia pestis genome sequencing projects have revealed six intact uncharacterized chaperone/usher systems with the potential to play roles in plague pathogenesis. We cloned each locus and expressed them in the Δfim Escherichia coli strain AAEC185 to test the assembled Y. pestis surface structures for various activities. Expression of each chaperone/usher locus gave rise to specific novel fibrillar structures on the surface of E. coli. One locus, y0561-0563, was able to mediate attachment to human epithelial cells (HEp-2) and human macrophages (THP-1) but not mouse macrophages (RAW264.7), while several loci were able to facilitate E. coli biofilm formation. When each chaperone/usher locus was deleted in Y. pestis, only deletion of the previously described pH 6 antigen (Psa) chaperone/usher system resulted in decreased adhesion and biofilm formation. Quantitative RT-PCR (qRT-PCR) revealed low expression levels for each novel chaperone/usher system in vitro as well as in mouse tissues following intravenous infection. However, a Y. pestis mutant in the chaperone/usher locus y1858-1862 was attenuated for virulence in mice via the intravenous route of infection, suggesting that expression of this locus is, at some stage, sufficient to affect the outcome of a plague infection. qRT-PCR experiments also indicated that expression of the chaperone/usher-dependent capsule locus, caf1, was influenced by oxygen availability and that the well-described chaperone/usher-dependent pilus, Psa, was strongly induced in minimal medium even at 28 °C rather than 37 °C, a temperature previously believed to be required for Psa expression. These data indicate several potential roles for the novel chaperone/usher systems of Y. pestis in pathogenesis and infection-related functions such as cell adhesion and biofilm formation.
Anabaena sp. strain PCC 7120 conR contains a LytR-CpsA-Psr domain, is developmentally regulated, and is essential for diazotrophic growth and heterocyst morphogenesis
Authors: Mella-Herrera Rodrigo A. , Neunuebel M. Ramona , Golden James W.
Published: November 2010

TheconR(all0187) gene of the filamentous cyanobacteriumAnabaena(Nostoc) sp. strain PCC 7120 is predicted to be part of a family of proteins that contain the LytR-CpsA-Psr domain associated with septum formation and cell wall maintenance. TheconRgene was originally misannotated as a transcription regulator. Northern RNA blot analysis showed thatconRexpression was upregulated 8 h after nitrogen step-down. Fluorescence microscopy of a PconR–gfpreporter strain revealed increased GFP fluorescence in proheterocysts and heterocysts beginning 9 h after nitrogen step-down. Insertional inactivation ofconRcaused a septum-formation defect of vegetative cells grown in nitrate-containing medium. In nitrate-free medium, mutant filaments formed abnormally long heterocysts and were defective for diazotrophic growth. Septum formation between heterocysts and adjacent vegetative cells was abnormal, often with one or both poles of the heterocysts appearing partially open. In aconRmutant, expression ofnifHwas delayed after nitrogen step-down and nitrogenase activity was approximately 70 % of wild-type activity, indicating that heterocysts of theconRmutant strain are partially functional. We hypothesize that the diazotrophic growth defect is caused by an inability of the heterocysts to transport fixed nitrogen to the neighbouring vegetative cells.
Tissue-specific disallowance of housekeeping genes: The other face of cell differentiation
Authors: Thorrez Lieven , Laudadio Ilaria , Van Deun Katrijn , Quintens Roel , Hendrickx Nico , Granvik Mikaela , Lemaire Katleen , Schraenen Anica , Van Lommel Leentje , Lehnert Stefan , Aguayo-Mazzucato Cristina , Cheng-Xue Rui , Gilon Patrick , Van Mechelen Iven , Bonner-Weir Susan , Lemaigre Frédéric , Schuit Frans
Published: November 2010

We report on a hitherto poorly characterized class of genes that are expressed in all tissues, except in one. Often, these genes have been classified as housekeeping genes, based on their nearly ubiquitous expression. However, the specific repression in one tissue defines a special class of “disallowed genes.” In this paper, we used the intersection-union test to screen for such genes in a multi-tissue panel of genome-wide mRNA expression data. We propose that disallowed genes need to be repressed in the specific target tissue to ensure correct tissue function. We provide mechanistic data of repression with two metabolic examples, exercise-induced inappropriate insulin release and interference with ketogenesis in liver. Developmentally, this repression is established during tissue maturation in the early postnatal period involving epigenetic changes in histone methylation. In addition, tissue-specific expression of microRNAs can further diminish these repressed mRNAs. Together, we provide a systematic analysis of tissue-specific repression of housekeeping genes, a phenomenon that has not been studied so far on a genome-wide basis and, when perturbed, can lead to human disease.
New cancer treatment strategy using combination of green tea catechins and anticancer drugs
Authors: Suganuma Masami , Saha Achinto , Fujiki Hirota
Published: November 2010

Green tea is now recognized as the most effective cancer preventive beverage. In one study, 10 Japanese‐size cups of green tea daily supplemented with tablets of green tea extract limited the recurrence of colorectal polyps in humans to 50%. Thus, cancer patients who consume green tea and take anticancer drugs will have double prevention. We studied the effects of combining (−)‐epigallocatechin gallate (EGCG) and anticancer drugs, focusing on inhibition of cell growth and induction of apoptosis. Numerous anticancer drugs, such as tamoxifen, COX‐2 inhibitors, and retinoids were used for the experiments, and the combination of EGCG and COX‐2 inhibitors consistently induced the enhancement of apoptosis. To study the mechanism of the enhancement, we paid special attention to the enhanced expressions of DDIT3 (growth arrest and DNA damage‐inducible 153, GADD153), GADD45A, and CDKN1A (p21/WAF1/CIP1) genes, based on our previous evidence that a combination of EGCG and sulindac specifically induced upregulated expression of GADD153 and p21 genes in PC‐9 lung cancer cells. The synergistic enhancements of apoptosis and GADD153 gene expression in human non‐small cell lung cancer cells by the combination of EGCG and celecoxib were mediated through the activation of the MAPK signaling pathway. This article reviews the synergistic enhancement of apoptosis, gene expression, and anticancer effects using various combinations of EGCG and anticancer drugs, including the combination of (−)‐epicatechin (EC) and curcumin. Based on the evidence, we present a new concept: green tea catechins as synergists with anticancer drugs. (Cancer Sci 2011; 102: 317–323)
Prolonged recurrence-free survival following OK432-stimulated dendritic cell transfer into hepatocellular carcinoma during transarterial embolization
Authors: Nakamoto Y , Mizukoshi E , Kitahara M , Arihara F , Sakai Y , Kakinoki K , Fujita Y , Marukawa Y , Arai K , Yamashita T , Mukaida N , Matsushima K , Matsui O , Kaneko S
Published: November 2010

Despite curative locoregional treatments for hepatocellular carcinoma (HCC), tumour recurrence rates remain high. The current study was designed to assess the safety and bioactivity of infusion of dendritic cells (DCs) stimulated with OK432, a streptococcus-derived anti-cancer immunotherapeutic agent, into tumour tissues following transcatheter hepatic arterial embolization (TAE) treatment in patients with HCC. DCs were derived from peripheral blood monocytes of patients with hepatitis C virus-related cirrhosis and HCC in the presence of interleukin (IL)-4 and granulocyte-macrophage colony-stimulating factor and stimulated with 0·1 KE/ml OK432 for 2 days. Thirteen patients were administered with 5 × 106 of DCs through arterial catheter during the procedures of TAE treatment on day 7. The immunomodulatory effects and clinical responses were evaluated in comparison with a group of 22 historical controls treated with TAE but without DC transfer. OK432 stimulation of immature DCs promoted their maturation towards cells with activated phenotypes, high expression of a homing receptor, fairly well-preserved phagocytic capacity, greatly enhanced cytokine production and effective tumoricidal activity. Administration of OK432-stimulated DCs to patients was found to be feasible and safe. Kaplan–Meier analysis revealed prolonged recurrence-free survival of patients treated in this manner compared with the historical controls (P = 0·046, log-rank test). The bioactivity of the transferred DCs was reflected in higher serum concentrations of the cytokines IL-9, IL-15 and tumour necrosis factor-α and the chemokines CCL4 and CCL11. Collectively, this study suggests that a DC-based, active immunotherapeutic strategy in combination with locoregional treatments exerts beneficial anti-tumour effects against liver cancer.
The resource availability hypothesis revisited: a meta‐analysis
Authors: Endara María‐José , Coley Phyllis D.
Published: November 2010

1. Several theories have provided a framework for understanding variation in plant defence against herbivores. Among them, the plant apparency theory and the resource availability hypothesis (RAH) have aimed to explain the patterns of defence investment and the selective pressures that have led to the variety of defensive strategies across species. Here we provide a historical review of both theories, present evidence that shaped their development and contrast their predictions.

2. We present the results of a meta‐analysis of the utility of the RAH 25 years after it was proposed and compare it to apparency theory. We performed a meta‐analysis of 50 studies that have examined plant growth, defences and herbivory in relation to resource availability across latitude and ontogeny. Specifically, we tested four predictions that follow the RAH: (i) species adapted to resource‐rich environments have intrinsically faster growth rates than species adapted to resource‐poor environments; (ii) fast‐growing species have shorter leaf lifetimes than slow‐growing species; (iii) fast‐growing species have lower amounts of constitutive defences than slow‐growing species; and (iv) fast‐growing species support higher herbivory rates than slow‐growing species.

3. Our results confirm the predictions that species adapted to resource‐poor environments grow inherently more slowly, invest more in constitutive defences and support lower herbivory than species from more productive habitats. Our data also showed that variation in growth rate among species better explains the differences in herbivory than variation in apparency, suggesting that the evolution of different defensive strategies across species is resource, rather than herbivore driven. We also found that the application of this theory appears robust across latitude and ontogeny, as the magnitude of the effect sizes for most of the predictions did not vary significantly between ecosystems or across ontogenic stages.

4. We conclude that the RAH has served as a valid framework for investigating the patterns of plant defences and that its applicability is quite general.
Predicting root defence against herbivores during succession
Authors: Rasmann Sergio , Bauerle Taryn L. , Poveda Katja , Vannette Rachel
Published: November 2010

1. Root herbivores and pathogens interfere with basic below‐ground plant function, and can thereby affect plant fitness and spatial and temporal patterns in natural plant communities. However, there has been little development of concepts and theories on below‐ground plant defence, a deficit that is in contrast to the abundance of theorizing for above‐ground plant parts.

2. A review of the past 10 years of research on below‐ground plant–herbivore interactions has revealed that, similar to above‐ground tissues, root defences can be expressed constitutively or induced upon herbivore attack, and can be classified into direct and indirect traits, tolerance, and escape. Indeed, it has been shown that roots tolerate herbivory by outgrowing or re‐growing lost tissues, or resist it by producing secondary metabolites that are toxic to herbivores or attract natural enemies of herbivores.

3. We propose that, similar to above‐ground plant–herbivore theories, the partition of abiotic and biotic factors over ecological succession can serve as the basis for predicting investment in defence strategies below‐ground.

4. Investigation of herbivore pressure and root responses along primary and secondary successional gradients suggests that: (i) roots are often fast growing, thinner and softer in early compared to later succession. (ii) Insect and nematode herbivore pressure increases until mid‐succession and later decreases. (iii) Mycorrhizal abundance increases with succession, and the composition of fungal species changes through succession, often shifting from arbuscular mycorrhizae to ecto‐mycorrhizae.

5. Based on these findings, and on classical (above‐ground) plant defence theory, we suggest the following set of testable hypotheses for below‐ground plant defence: (i) During succession, early plants invest most of their resources in growth and less in defences (associated with a general lack of herbivores and pathogens, and with limited availability of resources in the system), therefore relying more on re‐growth (tolerance) strategies. (ii) During mid‐succession, a buildup of herbivore pressure facilitates replacement by plant species that exhibit greater direct and indirect defence strategies. (iii) Constitutive and inducible levels of defences may trade‐off, and early successional plants should rely more on induction of defences after herbivore attack, whereas late successional plants will increasingly rely on constitutively produced levels of physical and chemical defence. (iv) Successional changes in microbial associations have consequences for root defence by improving plant nutrition and defence expression as well as directly competing for root space; however, toxic or impenetrable root defences may also limit association with root symbionts, and so may constrain the expression of root defence.
Peer interaction: the experience of distance students at university level
Authors: Ferguson R.
Published: November 2010

This study investigates how university students on distance learning courses experience interaction with their peers. Students on two distance learning courses at The Open University (UK) were interviewed, to investigate learners' experience of interaction on these courses. The analysis, using a grounded‐theory approach, reveals disparities between course designers' and students' reasons for integrating computer‐mediated interaction within the courses. It draws attention to the significant affective challenges that online students face when working together, and demonstrates a need to pay attention to their problems with self‐presentation. The study also reinforces the socio‐cultural view that it is important to consider the various contexts in which online learning takes place. Distance students have opportunities to structure their own learning contexts, and this allows them to source face‐to‐face learning interaction and other forms of support as they engage with individuals in their everyday environment.