bluuebunny/crossref_metadata_2025 huggingface dataset:
Stabilization effects of spatial aggregation of vectors in plant disease systems
Authors: Yamamura Kohji
Published: December 2007

Stabilization effects of spatial aggregation of vectors were examined in insect‐borne plant disease systems by constructing a model that describes the yearly dynamics of rice stripe virus disease transmitted by the small brown planthopper Laodelphax striatellus (Fallén). Two transmission paths between vectors were considered: vertical transmission from parents through eggs, and horizontal transmission from infected plants by acquisition feeding. In this model, a paddy field was divided into quadrats and horizontal transmission was assumed to occur within each quadrat. A negative binomial distribution was used to describe the frequency distribution of vectors per quadrat. The parameters of the model were estimated using field data collected in Ibaraki Prefecture, Japan. The model showed that (1) the disease cannot invade into an epidemiological system if the mean crowding of vectors is less than a critical value, (2) the proportion of infected vectors is maintained at about 30% irrespective of the vector density if vectors are highly aggregated, and (3) the proportion of infected plants is maintained at a low level irrespective of the vector density if vectors are highly aggregated. It was also shown that these stabilization effects of aggregation in this epidemiological system come from a mechanism that is common to other systems such as single‐species systems and competition systems.
Polymorphic fundatrices in thimbleberry aphid — ecology and maintenance
Authors: Gilbert Neil , Raworth David A.
Published: December 2007

The thimbleberry aphid, Masonaphis maxima (Mason) lives on patches of plants that support 3,4 or 5 generations depending on site and weather. The life cycle requires sexual females and males to produce overwintering eggs. The eggs hatch in the spring to produce the first ‘fundatrix’ generation; subsequent generations are produced parthenogenically. Males and other morphs are produced by wingless virginoparae, but sexual females are produced by ‘gynoparae’, a winged morph that is specialized to produce only sexual females. The fundatrices have no indication of the number of generations that the plants will support in the current year. There are two fundatrix types that coexist in different ratios depending on the number of generations supported by the patch the previous year. One type produces sexual females in generations 3 and 5, and males in generations 4 and 5; the other type produces sexual females in generations 4 and 5, and males in generations 3, 4 and 5. The dimorphism adapts the aphid to its heterogeneous and somewhat unpredictable environment. The role of sex in the maintenance of the dimorphism is discussed. This is the first report of fundatrix polymorphism and consequent differential sex expression in aphids.
Anthropogenic, ecological and genetic factors in extinction and conservation
Authors: Lande Russell
Published: December 2007

Anthropogenic factors constitute the primary deterministic causes of species declines, endangerment and extinction: land development, overexploitation, species translocations and introductions, and pollution. The primary anthropogenic factors produce ecological and genetic effects contributing to extinction risk. Ecological factors include environmental stochasticity, random catastrophes, and metapopulation dynamics (local extinction and colonization) that are intensified by habitat destruction and fragmentation. Genetic factors include hybridization with nonadapted gene pools, and selective breeding and harvesting. In small populations stochastic factors are especially important, including the ecological factors of Allee effect, edge effects, and demographic stochasticity, and the genetic factors of inbreeding depression, loss of genetic variability, and fixation of new deleterious mutations. All factors affecting extinction risk are expressed, and can be evaluated, through their operation on population dynamics.
Extinction risk assessment of declining wild populations: The case of the southern Bluefin Tuna
Authors: Matsuda Hiroyuki , Takenaka Yasuto , Yahara Tetsukazu , Uozumi Yuji
Published: December 2007

We estimate the extinction probability of a large and decreasing population, the southern bluefin tuna. This tuna was listed as critically endangered by the World Conservation Union (IUCN) in 1996. However, the absolute population size is still large and the extinction probability within the next half century is negligible if the recent population decline rate does not increase in the future. IUCN's criterion with respect to the population decline rate should be linked to the absolute population size, if this is estimated. Several methods estimating the probability of extinction conclude that the southern bluefin tuna population will be below 500 mature individuals within the next 100 years and may be listed as vulnerable. These analyses suggest that extinction risk assessment is useful for management action for taxa that still have large population and are rapidly decreasing.
Theoretical aspects of extinction by inbreeding depression
Authors: Tanaka Yoshinari
Published: December 2007

Populational extinction due to inbreeding depression is analyzed with simple population genetic and population ecological models. Two alternative genetic mechanisms of inbreeding depression, i.e. recessive deleterious genes and overdominant genes, are assumed in separate analyses in order to examine their relative importance. With both mechanisms the population size and the coefficient of inbreeding are maintained at stable equilibria if there is no non‐genetic demographic disturbance or stress. With a certain amount of demographic disturbance the population declines rapidly due to interaction between the decrease of population size and the increase of inbreeding coefficient. Such rapid extinction occurs with both genetic mechanisms. However, in the case of overdominant genes extinction happens only if the equilibrium population size is small and the selection coefficient is large such that segregation load is large. In nature, extinction due to overdominant genes is considered to be much less likely than extinction due to recessive deleterious genes.
Evolutionary character changes and population responses in an insect host‐parasitoid experimental system
Authors: Tuda Midori
Published: December 2007

In an insect host (the cowpea weevil Callosobruchus maculatus)‐ parasitoid Heterospilus prosopidis) experimental system, the population densities of the component species oscillated for the first 20 generations and then abruptly stabilized as the parasitoid density decreased. Examination of the host and parasitoid after the 40th generation in the long‐term experiment showed that (1) host larvae exhibited contest‐type competition (killing other larvae inhabiting the same bean), in contrast to the founder population being scramble‐type competitors and (2) the parasitoid attack rate on the host did not change. There was also an evolutionary trade‐off between body size and the rates of larval survival and development, suggesting a cost of contest competition on larval survivorship and development. I tested model predictions (Tuda and Iwasa 1998) that (1) host equilibrium population size should gradually decrease as the proportion of the contest type increases and that (2) random attacks of the parasitoid on the host should reduce the rate of increase in proportion of the contest type, and the effect should become manifest especially during the first 20 generations. Two of three host‐only replicates showed significant decrease in population sizes. Although the density of emerging adults per bean did not differ between replicates of the host‐only and host‐parasitoid systems, comparison of the host body size between them on day 270 (at the 13th generation) showed that the host was more contest‐type in the host‐only system than in the host‐parasitoid system, as the model predicted, and later on day 650 the effect of the parasitoid had disappeared.
Genetic changes of life history and behavioral traits during mass‐rearing in the melon Fly, Bactrocera cucurbitae (Diptera: Tephritidae)
Authors: Miyatake Takahisa
Published: December 2007

Quantitative genetic studies for life history and behavioral traits are important in quality control for insect mass‐rearing programs. Firstly, a brief history of quality control in mass‐reared insects is described. Next, the differentiation of many traits of wild and mass‐reared melon flies, Bactrocera cucurbitae, in Okinawa is reviewed, and the factors which have caused variation in these traits are considered. As artificial selection pressures are thought to be more important than inbreeding depression and genetic drift in the mass‐reared strain of the Okinawan melon fly, two artificial selection experiments were conducted to evaluate genetic variations and genetic correlations among life history and behavioral traits. These are divergent selections for age at reproduction and for developmental period. The genetic relationship among 5 traits, i.e. longevity, age at reproduction, developmental period, circadian period, and time of mating was clarified and discussed in relation to genetic changes of traits during the mass‐rearing. The results suggest that the genetic trade‐off relationships between traits should be taken into account in mass‐rearing programs.
Brief report: Expressive and collaborative relationship processes in observations of adolescents’ interactions with parents and romantic partners
Authors: Madsen Stephanie D. , Andrew Collins W.
Published: December 2007

This study examines observations of participants (N=64) interacting with family members at age 13 and romantic partners at age 20–21. Scales capturing expressive processes and collaborative processes were used to test and find support for the differential prediction that family collaborative processes at age 13 would predict both expressive processes and collaborative processes with romantic partners at age 20–21, whereas expressive processes at age 13 would predict only concurrent collaborative processes. Results suggest that continuity in relationship functioning is more differentiated than is commonly expected.
Drotaverine hydrochloride versus hyoscine‐N‐butylbromide in augmentation of labor
Authors: Gupta Bindiya , Nellore Vimala , Mittal Suneeta
Published: December 2007

Objectives: To study and compare the efficacy and side effects of drotaverine hydrochloride and hyoscine‐N‐butylbromide in the augmentation of labor. Methods: A prospective randomized trial of 150 women in active labor included 50 women given drotaverine (group 1), 50 women given hyoscine‐N‐butylbromide (group 2), and 50 women given no medication (group 3). Duration of labor, rate of cervical dilation, mode of delivery, side effects, and neonatal outcome were compared among the groups. Results: The mean duration of the active phase of labor was 4.48 ± 2.26 h, 3.9 ± 2.42 h, and 3.6 ± 2.07 h in groups 1, 2, and 3, respectively. The mean rate of cervical dilation was 2.6 cm/h, 2.4 cm/h, and 2.5 cm/h, respectively. The differences were not statistically significant. There was no difference in the duration of the second and third stages of labor. No adverse maternal or fetal outcomes were noted. Conclusion: Drotaverine hydrochloride and hyoscine‐N‐butylbromide do not have a role in augmentation of labor.
Ovarian suppression treatment prior to in‐vitro fertilization and embryo transfer in Chinese women with stage III or IV endometriosis
Authors: Ma Caihong , Qiao Jie , Liu Ping , Chen Guian
Published: December 2007

Objective

To evaluate the efficacy of a 2‐month treatment with a gonadotropin‐releasing hormone (GnRH) agonist prior to in‐vitro fertilization in Chinese women with moderate or severe endometriosis.

Methods

A study of 162 women surgically diagnosed as having moderate or severe endometriosis. Pituitary down‐regulation was achieved with injections of a GnRH agonist prior to the IVF procedures either for 7 to 10 days in the mid‐luteal phase (group 1 [standard protocol], 97 cycles in total), or for 2 months (group 2, 55 cycles), or 3 months (group 3, 75 cycles).

Results

Women pretreated with a GnRH agonist for 2 or 3 months required significantly higher doses of gonadotropin for ovarian stimulation (P < 0.001), and for a longer time, than those treated with the standard long protocol (P < 0.05). The number of oocytes and good embryos was lower in group 3 than in groups 1 or 2 (P < 0.05). The implantation rate was significantly higher in group 2 than in group 1 (P < 0.02).

Conclusion

A 2‐month treatment with a GnRH agonist prior to IVF produced a trend toward an increase in the implantation rate in a group of Chinese women with stages III and IV endometriosis.
Numerical simulation of the paleohydrology of glacial Lake Oshkosh, eastern Wisconsin, USA
Authors: Clark James A. , Befus Kevin M. , Hooyer Thomas S. , Stewart Peter W. , Shipman Taylor D. , Gregory Chris T. , Zylstra Deborah J.
Published: December 2007

Proglacial lakes, formed during retreat of the Laurentide ice sheet, evolved quickly as outlets became ice-free and the earth deformed through glacial isostatic adjustment. With high-resolution digital elevation models (DEMs) and GIS methods, it is possible to reconstruct the evolution of surface hydrology. When a DEM deforms through time as predicted by our model of viscoelastic earth relaxation, the entire surface hydrologic system with its lakes, outlets, shorelines and rivers also evolves without requiring assumptions of outlet position. The method is applied to proglacial Lake Oshkosh in Wisconsin (13,600 to 12,900 cal yr BP). Comparison of predicted to observed shoreline tilt indicates the ice sheet was about 400 m thick over the Great Lakes region. During ice sheet recession, each of the five outlets are predicted to uplift more than 100 m and then subside approximately 30 m. At its maximum extent, Lake Oshkosh covered 6600 km2with a volume of 111 km3. Using the Hydrologic Engineering Center-River Analysis System model, flow velocities during glacial outburst floods up to 9 m/s and peak discharge of 140,000 m3/s are predicted, which could drain 33.5 km3of lake water in 10 days and transport boulders up to 3 m in diameter.
Translation and reorientation of CD4 molecules in nanoscale cages of zeolites as studied by deuteron spin-lattice relaxation
Authors: Birczyński A. , Punkkinen M. , Szymocha A. M. , Lalowicz Z. T.
Published: December 2007

Deuteron spin-lattice relaxation was applied to study translational and rotational mobility of CD4 molecules trapped in the cages of zeolites. Tetrahedral methane molecules are treated as quantum rotators. Relaxation rates related to the intraquadrupole interaction are derived for the T and A+E symmetry species in the presence of large tunneling splittings, consistently with the assumption that A and E species molecules relax at the same rate. An exchange model is presented, which describes the effect on relaxation of CD4 jumping between two positions characterized by different potentials. While staying at either position bonded to an atom or ion at the cage wall, the molecule has some freedom to move in the vicinity. This causes a time-dependent external electric field gradient, which contributes to the deuteron relaxation rate via the electric quadrupole interaction. Spin conversion transitions couple the relaxation of magnetizations MT and MAE, which is taken into account by reapplying the presented model under somewhat different conditions. Such a two-step procedure leads to successful fits with the experimental results obtained in the range of temperatures roughly 20–200K for zeolites HY, NaA, and NaMordenite. At higher temperatures CD4 molecules fly freely across zeolite cages and relaxation changes accordingly, while incoherent tunneling dominates for immobile molecules below 20K.
Equilibrium shapes and stability of a liquid film subjected to a nonuniform electric field
Authors: Yeoh Hak Koon , Xu Qi , Basaran Osman A.
Published: December 2007

Stresses induced by a spatially nonuniform electric field acting on an initially flat fluid-fluid interface can (i) be exploited beneficially to pattern polymer microstructures without the use of resists, exposure, development, and etching, but (ii) cause undesirable nonuniformity in film thickness in precision coating processes. The equilibrium shape of an interface separating a liquid film from an ambient fluid subjected to a uniform electric field is flat so long as the field strength is below a critical value. A nonuniform electric field, however, results in the deformation of the interface no matter how small its strength, an important difference which previous theoretical studies have not addressed satisfactorily. Hence, whereas under a uniform field loss of stability occurs via a bifurcation from the flat film solution, under a nonuniform field destabilization may occur at a turning point at which the film profile already exhibits a finite-amplitude deformation. This deficiency in understanding is remedied here by analyzing a model problem in which a gas overlying a perfect dielectric liquid film is sandwiched between two electrodes wherein the top electrode is grounded and the electric potential of the bottom electrode varies sinusoidally with distance measured along it. The equilibrium shapes and stability of the liquid-gas interface are determined directly in the present work by simultaneously solving the augmented Young-Laplace equation governing the shape of the free surface and the Laplace equation governing electric potentials theoretically by domain perturbation analysis and numerically by finite element analysis. For small nonuniformities in the electric field, analytical solutions are reported for the profile of the free surface. The computational predictions are shown to be in excellent accord with these small-deformation results. Moreover, computations are used to extend the investigations into the nonlinear regime where nonuniformities in the electric field and deformations of the free surface are large, and loss of stability may occur. The variation of the equilibrium shapes and the limits of stability with the governing dimensionless groups are investigated thoroughly. It is shown that the rich response exhibited by the system can be rationalized by interrogating the computed solutions and scrutinizing the balance of stresses due to the normal component of the electric field, which are destabilizing, and those due to its tangential component, which are stabilizing.
Block correlated coupled cluster theory with a complete active-space self-consistent-field reference function: The formulation and test applications for single bond breaking
Authors: Fang Tao , Li Shuhua
Published: December 2007

Block correlated coupled cluster (BCCC) theory with a complete active-space self-consistent-field (CASSCF) reference function is presented. This theory provides an alternative multireference coupled cluster framework to describe the multireference characters of the ground-state wave functions. In this approach, a multireference block is defined to incorporate the nondynamic correlation, and all other blocks involve just a single spin orbital. The cluster operators are truncated up to the four-block correlation level, leading to the BCCC4 scheme. For a single bond breaking problem, the present CAS-BCCC4 approach with a CASSCF(2,2) reference function computationally scales as the traditional single-reference coupled cluster singles and doubles. We have applied the present approach to investigate the electronic structures of several model systems including H4, P4, and BeH2, and the single bond breaking processes in small systems such as F2, HF, BH, and CH4. A comparison of our results with those from full configuration interaction calculations shows that the present approach can provide quantitative descriptions for all the studied systems. The size-consistency error is found to be quite small in the dissociation limit of diatomic molecules F2, HF, and BH.
Evidence for cluster shape effects on the kinetic energy spectrum in thermionic emission
Authors: Calvo F. , Lépine F. , Baguenard B. , Pagliarulo F. , Concina B. , Bordas C. , Parneix P.
Published: December 2007

Experimental kinetic energy release distributions obtained for the thermionic emission from Cn− clusters, 10⩽n⩽20, exhibit significant non-Boltzmann variations. Using phase space theory, these different features are analyzed and interpreted as the consequence of contrasting shapes in the daughter clusters; linear and nonlinear isomers have clearly distinct signatures. These results provide a novel indirect structural probe for atomic clusters associated with their thermionic emission spectra.
Poly(3,3‴-didodecylquarterthiophene) field effect transistors with single-walled carbon nanotube based source and drain electrodes
Authors: Zhang Yuan Yuan , Shi Yumeng , Chen Fuming , Mhaisalkar S. G. , Li Lain-Jong , Ong Beng S. , Wu Yiliang
Published: December 2007

A solution processable method for employing single-walled carbon nanotubes (SWCNTs) as bottom contact source/drain electrodes for a significant reduction of contact resistance in poly(3,3‴-didodecylquarterthiophene) based organic field effect transistors (OFETs) is proposed. A two order of magnitude reduction in contact resistance and up to a threefold improvement in field effect mobilities were observed in SWCNT contacted OFETs as opposed to similar devices with gold source/drain electrodes. Based on Kelvin probe measurements, this improvement was attributed to a reduction in the Schottky barrier for hole injection into organic semiconductor.
Collisional damping of plasma waves on a pure electron plasma column
Authors: Anderson M. W. , O’Neil T. M.
Published: December 2007

The collisional damping of electron plasma waves (or Trivelpiece–Gould waves) on a pure electron plasma column is discussed. The damping in a pure electron plasma differs from that in a neutral plasma, since there are no ions to provide collisional drag. A dispersion relation for the complex wave frequency is derived from Poisson’s equation and the drift-kinetic equation with the Dougherty collision operator—a Fokker–Planck operator that conserves particle number, momentum, and energy. For large phase velocity, where Landau damping is negligible, the dispersion relation yields the complex frequency ω=(kzωp∕k)[1+(3∕2)(kλD)2(1+10iα∕9)(1+2iα)−1], where ωp is the plasma frequency, kz is the axial wavenumber, k is the total wavenumber, λD is the Debye length, ν is the collision frequency, and α≡νk∕ωpkz. This expression spans from the weakly collisional regime (α⪡1) to the moderately collisional regime (α∼1) and in the weakly collisional limit yields a damping rate which is smaller than that for a neutral plasma by the factor k2λD2⪡1. In the strongly collisional limit (α⪢1), the damping is enhanced by long-range interactions that are not present in the kinetic theory (which assumes pointlike interactions); the effect of these long-range collisions on the damping is discussed.
Thermal quenching sample chamber for grazing incidence small angle x-ray scattering studies of polymer films
Authors: Singh M. A. , Groves M. N. , Müller M. S. , Stahlbrand I. J. , Smilgies D.-M.
Published: December 2007

The second generation of a sample chamber designed for in situ measurement of temperature- and time-dependent polymer film nanostructure using the method of grazing incidence small angle x-ray scattering is presented. An increased operating temperature limit (from 260to400°C) with precise control (±0.1°C) at fixed temperatures as well as a fourfold increase in maximum instantaneous cooling rate (up to 73°C∕s) relative to the first generation chamber [M. N. Groves et al, J. Appl. Crystallogr. 39, 120 (2006)] are reported. Thermal quenches from 220to90°C are shown to be reproducible to within ±1°C of the final temperature. Experimental tests on spin-coated films of symmetric diblock styrene-butadiene copolymer demonstrate the ability to resolve the kinetics of orientation of lamellar domains parallel to the silicon substrate, distinct from the initial formation of randomly oriented lamellar domains immediately following the thermal quench.
Effects of magnetosonic perturbations on electron temperature gradient driven modes and the stability of skin depth sized electron ballooning modes
Authors: Joiner N. , Hirose A.
Published: December 2007

The effect of the magnetosonic perturbation δB∥ on the growth of electron temperature gradient driven (ETG) modes and electron temperature gradient driven ballooning modes [Hirose, Plasma Phys. Control. Fusion 49, 145 (2007)] is investigated using local gyrokinetic analysis and numerical solution, with supporting simulations from the initial value code GS2 [Kotschenreuther, et al., Comp. Phys. Commun. 88, 128 (1996)]. The effect of δB∥ on the ETG mode is found to depend on the competition between two physical processes related to magnetosonic compression. Local analysis of the ballooning mode appears to significantly overestimate growth rates of this instability. The electron temperature gradient driven ballooning mode has been observed in GS2 simulations. However, this work supports the conclusion that this instability will be subdominant to the ETG mode in normal tokamak regimes.
Manufacturing a thin wire electrostatic trap for ultracold polar molecules
Authors: Kleinert J. , Haimberger C. , Zabawa P. J. , Bigelow N. P.
Published: December 2007

We present a detailed description on how to build a thin wire electrostatic trap (TWIST) for ultracold polar molecules. It is the first design of an electrostatic trap that can be superimposed directly onto a magneto-optical trap (MOT). We can thus continuously produce ultracold polar molecules via photoassociation from a two species MOT and instantaneously trap them in the TWIST without the need for complex transfer schemes. Despite the spatial overlap of the TWIST and the MOT, the two traps can be operated and optimized completely independently due to the complementary nature of the utilized trapping mechanisms.
A structural basis for the Hodgkin and Huxley relation
Authors: Kang Yeona , Fortmann C. M.
Published: December 2007

Neural channel transport was analyzed using a previously reported relation for charged particle transport in two energy-type gradients: the electric field and here a water/strucural deformation energy. Neural channels are lined with α-helix structures filled with water vapor and sequestered hydrophobic amino acids arranged to present minimum water vapor and water-hydrophobic interface. Cation point charges generate enormous electric fields on sub-nanometer distances. Electrostatic energy reduction is characterized by dielectric water being pulled toward the transporting ion deforming the neural channel. An ion-water-structure coupling energy is induced by changes in channel diameter width. The resultant two energy gradient relation for cation transport: reduces to the Hodgkin-Huxley relation [A. L. Hodgkin and A. F. Huxley, J. Physiol. (London) 116, 449 (1952)], explains channel selectivity and environmental sensitivity, predicts fast non-dispersive transport under a narrow range of conditions, and produces current-voltage characteristics consistent with observation.
Surfaces in RN2−1 based on harmonic maps S2→CPN−1
Authors: Zakrzewski W. J.
Published: December 2007

We show that many surfaces in RN2−1 can be generated by harmonic maps of S2→CPN−1. These surfaces are based on the projectors in CPN−1 which describe maps of S2→CPN−1. In the case when these maps form the Veronese sequence, all the surfaces have a constant curvature.
Kinetic roughening of magnetic flux penetration in MgB2 thin films
Authors: Lucarelli Andrea , Hümmert Stephanie , Chaney Andrea , Lüpke Gunter , Moeckly Brian , Zhao Yue , Dou Shi Xue
Published: December 2007

Time-resolved magneto-optical studies are performed on MgB2 thin film samples grown by in situ pulsed laser deposition and in situ reactive deposition technique. The latter reveal dendritic avalanche-free flux penetration. The kinetic roughening of magnetic flux penetration is studied for applied ac current. Dynamic scaling laws determined for both static field and ac current are consistent with the directed percolation depinning model, placing the vortex dynamics in MgB2 in the same universality class as YBCO and Nb.
Atomic layer deposited TaCy metal gates: Impact on microstructure, electrical properties, and work function on HfO2 high-k dielectrics
Authors: Triyoso D. H. , Gregory R. , Schaeffer J. K. , Werho D. , Li D. , Marcus S. , Wilk G. D.
Published: December 2007

TaC y has been reported to have the appropriate work function for negative metal-oxide semiconductor metal in high-k metal-oxide field-effect transistors. As device size continues to shrink, a conformal deposition for metal gate electrodes is needed. In this work, we report on the development and characterization of a novel TaCy process by atomic layer deposition (ALD). Detailed physical properties of TaCy films are studied using ellipsometry, a four-point probe, Rutherford backscattering spectrometry (RBS), x-ray photoelectron spectroscopy (XPS), and x-ray diffraction (XRD). RBS and XPS analysis indicate that TaCy films are near-stoichiometric, nitrogen free, and have low oxygen impurities. Powder XRD spectra showed that ALD films have a cubic microstructure. XPS carbon bonding studies revealed that little or no glassy carbon is present in the bulk of the film. Excellent electrical properties are obtained using ALD TaCy as a metal gate electrode. Well-behaved capacitance-voltage characteristics with ALD HfO2 gate dielectrics are demonstrated for TaCy thicknesses of 50, 100, and 250 Å. A low fixed charge (∼2–4×10−11 cm−2) is observed for all ALD HfO2/ALD TaCy devices. Increasing the thickness of ALD TaCy results in a decrease in work function (4.77 to 4.54 eV) and lower threshold voltages.
Electron spin dynamics in Fe-doped InP
Authors: Li Bo , Tamargo Maria C. , Meriles Carlos A.
Published: December 2007

We have used time-resolved Kerr rotation to investigate carrier spin relaxation in bulk InP:Fe from 80K to room temperature. We observe several coexisting mechanisms contributing to spin relaxation with different time scales, as well as a rich but intricate dependence on the illumination frequency and intensity. In particular, we find indications of strong many-body interactions that result in a slower relaxation rate with increasing excitation intensity and that, possibly, generate spin level splitting in the absence of magnetic fields.
Hydrogen blistering of silicon: Effect of implantation temperature, isotope dependence, and key role of dynamic annealing
Authors: Giguère Alexandre , Terreault Bernard
Published: December 2007

Blistering of (001) Cz–Si crystals (>1Ωcm), by either protium (H) or deuterium (D) ions of 5keV energy, was studied as a function of the sample temperature during implantation in the range of 150–450K. It was found that the blistering dose thresholds decreased with temperature, and very dramatically so in the case of D ions, revealing new aspects of the giant isotope effect. An optimal implantation temperature for ion cutting was found around 100°C, where the required dose is reduced and the isotope effect is minimized. The results are interpreted in terms of models of the interaction of implanted hydrogen with radiation defects, and they show that dynamic annealing is incomparably more efficient in promoting blistering than purely thermal annealing.
Growth of Ca3Co4O9 films: Simple chemical solution deposition and stress induced spontaneous dewetting
Authors: Zhu Xuebin , Sun Yuping , Lei Hechang , Li Xianghu , Ang Ran , Zhao Bangchuan , Song Wenhai , Shi Dongqi , Dou Shixue
Published: December 2007

Chemical solution deposition as a simple method for preparation of oxide films is used to fabricate misfit structured Ca3Co4O9 thermoelectric films using cheap precursors, Ca and Co acetates, which opens up a simple route to fabricate large-area Co-based oxide thermoelectric films. The results show that when the annealing temperature is higher than 800°C crystallized Ca3Co4O9 films can be obtained on single-crystal LaAlO3 substrates, whereas the Ca3Co4O9 films are amorphous for lower annealing temperatures. Experimental evidence shows that the amorphous Ca3Co4O9 films behave like semiconductors with enhanced resistivity and Seebeck coefficient within the measured temperature range. The magnetoresistance is positive indicating the absence of long-range order of the Co-ion spins. For the crystallized Ca3Co4O9 films, it can be seen that the thinner films show the characteristics of spontaneous dewetting induced by the stress, which suggests that it is possible to prepare nanostructured Ca3Co4O9 films through tailoring the film thickness and the lattice mismatch; whereas, for the thicker films the temperature dependence of the resistivity and the Seebeck coefficient shows that it is possible to prepare excellent Ca3Co4O9 thermoelectric films using chemical solution deposition route, which will broaden the range of preparation methods for misfit structured Co-based thermoelectric films.
All-optical demultiplexing of 160–10Gbit∕s signals with Mach-Zehnder interferometric switch utilizing intersubband transition in InGaAs∕AlAs∕AlAsSb quantum well
Authors: Akimoto R. , Simoyama T. , Tsuchida H. , Namiki S. , Lim C. G. , Nagase M. , Mozume T. , Hasama T. , Ishikawa H.
Published: December 2007

We have developed a Mach-Zehnder interferometric all-optical switch employing intersubband transition in an InGaAs∕AlAs∕AlAsSb-coupled double quantum well waveguide. The recently discovered cross-phase modulation phenomenon was utilized as the switching mechanism; the nonlinear index of refraction for transverse electric polarized light is induced by intersubband optical excitation using transverse magnetic pump light. We demonstrate the demultiplexing operation of 160Gbit∕s data signals to 10Gbit∕s using this switch. At the input control pulse energy of 8pJ, the demultiplexed signals showed an extinction ratio better than 10dB, and an error-free demultiplexing was achieved.
Grain size dependence of relaxor behavior in CaCu3Ti4O12 ceramics
Authors: Yu Hongtao , Liu Hanxing , Hao Hua , Guo Liling , Jin Chengjun , Yu Zhiyong , Cao Minghe
Published: December 2007

The dielectric properties show a typical ferroelectric relaxor behavior in CaCu3Ti4O12 ceramics with different grain sizes in the temperature range of 400–600K. The relaxation strength and the frequency dispersion increase with grain size decreasing, which can be due to the different stresses in grains with different sizes. These variations have been confirmed by the modified Curie-Weiss law. The results fitted well by the Volgel-Fulcher relationship and the variations in the slim current-voltage loops are correlated with the microstructures closely. It can be proposed that the grain size is one of the main factors of affecting the relaxor behavior.
Evaluating Social Marketing Elements in Sponsorship
Authors: O'Reilly Norman J. , Madill Judith J.
Published: December 2007

Organizations of all types increasingly recognize the importance of sponsorship as a source of revenue and as a means to achieve their objectives. This trend is driving the broader adoption of sponsorship, which has resulted in its use to pursue objectives other than those related to promotion, including those related to behavior change and, thus, social marketing. Concurrently, sponsors and sponsees are demanding the development of legitimate, reliable, and meaningful methods for the evaluation of sponsorship as investment in the area increases. For organizations whose objectives include behavior change and, thus seek to market behaviors (i.e., social marketers) this results in a need to be able to evaluate the social marketing elements of their sponsorships, distinct from other objectives that may be sought. The current research conceptualizes social marketing in sponsorship and then develops hypothetical examples for each resulting scenario to demonstrate how social marketing elements in sponsorship should be evaluated.
The National Diabetes Education Program's “Control Your Diabetes. For Life.” Campaign: Design, Implementation, and Lessons Learned
Authors: Gallivan Joanne , Lising Mimi , Ammary Neyal J. , Greenberg Rachel
Published: December 2007

The National Diabetes Education Program (NDEP) is a federally sponsored national partnership including government, nonprofit, professional, and private sector organizations. The NDEP uses social marketing principles and processes to develop and implement awareness campaigns and educational activities to improve the treatment and health status of people with diabetes. Co-sponsored by the National Institutes of Health (NIH) and the Centers for Disease Control and Prevention (CDC), NDEP launched its “Control Your Diabetes. For Life.” awareness campaign in 1998. The campaign was designed to educate the millions of Americans with diabetes and their social supporters about the seriousness of diabetes, ways to control the disease, and the benefits of good glucose control. The NDEP conducted extensive audience research and applied behavior change theories and the social marketing framework to design, implement, and evaluate the campaign. From 1998 to 2003, the campaign achieved at least 700 million media impressions with its culturally appropriate television and radio public service announcements, print ads, and newspaper and magazine stories. In addition, over half of people with diabetes indicated awareness of the campaign and NDEP has tracked positive trends in practice of blood glucose testing and awareness of the A1C (also known as the hemoglobin A1C), the best measure of blood glucose control, since the campaign's launch.
Putative promoter regions of miRNA genes involved in evolutionarily conserved regulatory systems among vertebrates
Authors: Fujita Shuji , Iba Hideo
Published: December 2007

Motivation: Just as transcription factors, miRNA genes modulate global patterns of gene expression during differentiation, metabolic activation, stimulus response and also carcinogenesis. However, little is currently known how the miRNA gene expression itself is regulated owing to lack of basic information of their gene structure. Global prediction of promoter regions of miRNA genes would allow us to explore the mechanisms underlying gene-regulatory mechanisms involving these miRNAs.

Results: We speculate that if specific miRNA molecules are involved in evolutionarily conserved regulatory systems in vertebrates, this would entail a high level of conservation of the promoter of miRNA gene as well as the miRNA molecule. By our current screening of putative promoter regions of miRNA genes (miPPRs) on this base, we identified 59 miPPRs that would direct production of 79 miRNAs. We present both biochemical and bioinformatical verifications of these putative promoters.

Contact:  iba@ims.u-tokyo.ac.jp

Supplementary information: Supplementary data are available at Bioinformatics online.
Motif module map reveals enforcement of aging by continual NF-κB activity
Authors: Adler Adam S. , Sinha Saurabh , Kawahara Tiara L.A. , Zhang Jennifer Y. , Segal Eran , Chang Howard Y.
Published: December 2007

Aging is characterized by specific alterations in gene expression, but their underlying mechanisms and functional consequences are not well understood. Here we develop a systematic approach to identify combinatorial cis-regulatory motifs that drive age-dependent gene expression across different tissues and organisms. Integrated analysis of 365 microarrays spanning nine tissue types predicted fourteen motifs as major regulators of age-dependent gene expression in human and mouse. The motif most strongly associated with aging was that of the transcription factor NF-κB. Inducible genetic blockade of NF-κB for 2 wk in the epidermis of chronologically aged mice reverted the tissue characteristics and global gene expression programs to those of young mice. Age-specific NF-κB blockade and orthogonal cell cycle interventions revealed that NF-κB controls cell cycle exit and gene expression signature of aging in parallel but not sequential pathways. These results identify a conserved network of regulatory pathways underlying mammalian aging and show that NF-κB is continually required to enforce many features of aging in a tissue-specific manner.
UV-B Signaling Pathways with Different Fluence-Rate Response Profiles Are Distinguished in Mature Arabidopsis Leaf Tissue by Requirement for UVR8, HY5, and HYH
Authors: Brown Bobby A. , Jenkins Gareth I.
Published: December 2007

UV-B signaling is an important but poorly understood aspect of light responsiveness in plants. Arabidopsis (Arabidopsis thaliana) UV RESISTANCE LOCUS8 (UVR8) is a recently identified UV-B-specific signaling component that regulates UV-protective responses. Using the uvr8 mutant, we defined genetically distinct UVR8-dependent and UVR8-independent pathways that stimulate different sets of genes in mature Arabidopsis leaf tissue. Both pathways operate at 1 μmol m−2 s−1 UV-B and above, but the UVR8-dependent pathway is able to stimulate UV-protective genes even in response to 0.1 μmol m−2 s−1 UV-B. Both pathways function in mutants lacking phytochromes, cryptochromes, or phototropins. Genes encoding the ELONGATED HYPOCOTYL5 (HY5) and HY5 HOMOLOG (HYH) transcription factors are induced at low UV-B fluence rates (0.1 μmol m−2 s−1). Experiments with hy5 and hyh mutants reveal that both these factors mediate responses of the UVR8-dependent pathway, acting with partial or complete redundancy to stimulate expression of particular genes. Furthermore, evidence is presented that all UVR8 pathway genes are likely to be regulated by HY5/HYH and that these transcription factors do not mediate UV-B responses independent of UVR8. Finally, we highlight the functions of HY5 and HYH in UV protection and show that HY5 plays the more critical role. This research provides evidence that, in UV-B signaling, UVR8, HY5, and HYH act together in a photoregulatory pathway and demonstrates a new role for HYH in UV-B responses.
Core Genome Responses Involved in Acclimation to High Temperature
Authors: Larkindale Jane , Vierling Elizabeth
Published: December 2007

Plants can acclimate rapidly to environmental conditions, including high temperatures. To identify molecular events important for acquired thermotolerance, we compared viability and transcript profiles of Arabidopsis thaliana treated to severe heat stress (45°C) without acclimation or following two different acclimation treatments. Notably, a gradual increase to 45°C (22°C to 45°C over 6 h) led to higher survival and to more and higher-fold transcript changes than a step-wise acclimation (90 min at 38°C plus 120 min at 22°C before 45°C). There were significant differences in the total spectrum of transcript changes in the two treatments, but core components of heat acclimation were apparent in the overlap between treatments, emphasizing the importance of performing transcriptome analysis in the context of physiological response. In addition to documenting increases in transcripts of specific genes involved in processes predicted to be required for thermotolerance (i.e. protection of proteins and of translation, limiting oxidative stress), we also found decreases in transcripts (i.e. for programmed cell death, basic metabolism, and biotic stress responses), which are likely equally important for acclimation. Similar protective effects may also be achieved differently, such as prevention of proline accumulation, which is toxic at elevated temperatures and which was reduced by both acclimation treatments but was associated with transcript changes predicted to either reduce proline synthesis or increase degradation in the two acclimation treatments. Finally, phenotypic analysis of T-DNA insertion mutants of genes identified in this analysis defined eight new genes involved in heat acclimation, including cytosolic ascorbate peroxidase and the transcription factors HsfA7a (heat shock transcription factor A7a) and NF-X1.
PRR3 Is a Vascular Regulator of TOC1 Stability in theArabidopsisCircadian Clock
Authors: Para Alessia , Farré Eva M. , Imaizumi Takato , Pruneda-Paz José L. , Harmon Franklin G. , Kay Steve A.
Published: December 2007

The pseudoresponse regulators (PRRs) participate in the progression of the circadian clock in Arabidopsis thaliana. The founding member of the family, TIMING OF CAB EXPRESSION1 (TOC1), is an essential component of the transcriptional network that constitutes the core mechanism of the circadian oscillator. Recent data suggest a role in circadian regulation for all five members of the PRR family; however, the molecular function of TOC1 or any other PRRs remains unknown. In this work, we present evidence for the involvement of PRR3 in the regulation of TOC1 protein stability. PRR3 was temporally coexpressed with TOC1 under different photoperiods, yet its tissue expression was only partially overlapping with that of TOC1, as PRR3 appeared restricted to the vasculature. Decreased expression of PRR3 resulted in reduced levels of TOC1 protein, while overexpression of PRR3 caused an increase in the levels of TOC1, all without affecting the amount of TOC1 transcript. PRR3 was able to bind to TOC1 in yeast and in plants and to perturb TOC1 interaction with ZEITLUPE (ZTL), which targets TOC1 for proteasome-dependent degradation. Together, our results indicate that PRR3 might function to modulate TOC1 stability by hindering ZTL-dependent TOC1 degradation, suggesting the existence of local regulators of clock activity and adding to the growing importance of posttranslational regulation in the design of circadian timing mechanisms in plants.
A Feedback Regulatory Module Formed by LITTLE ZIPPER and HD-ZIPIII Genes
Authors: Wenkel Stephan , Emery John , Hou Bi-Huei , Evans Matthew M.S. , Barton M.K.
Published: December 2007

The Arabidopsis thaliana REVOLUTA (REV) protein is a member of the class III homeodomain-leucine zipper (HD-ZIPIII) proteins. REV is a potent regulator of leaf polarity and vascular development. Here, we report the identification of a gene family that encodes small leucine zipper–containing proteins (LITTLE ZIPPER [ZPR] proteins) where the leucine zipper is similar to that found in REV, PHABULOSA, and PHAVOLUTA proteins. The transcript levels of the ZPR genes increase in response to activation of a steroid-inducible REV protein. We show that the ZPR proteins interact with REV in vitro and that ZPR3 prevents DNA binding by REV in vitro. Overexpression of ZPR proteins in Arabidopsis results in phenotypes similar to those seen when HD-ZIPIII function is reduced. We propose a negative feedback model in which REV promotes transcription of the ZPR genes. The ZPR proteins in turn form heterodimers with the REV protein, preventing it from binding DNA. The HD-ZIPIII/ZPR regulatory module would serve not only to dampen the effect of fluctuations in HD-ZIPIII protein levels but more importantly would provide a potential point of regulation (control over the ratio of inactive heterodimers to active homodimers) that could be influenced by other components of the pathway governing leaf polarity.