bluuebunny/crossref_metadata_2025 huggingface dataset:
Stress protein content of matureBrassicaseeds and their germination performance
Authors: Bettey Mary , Finch-Savage W. E.
Published: September 2008

Plants respond to sub-optimal conditions by the synthesis of specific ‘stress’ proteins, and these are thought to play a role in stress tolerance. Some of these proteins accumulate during late seed development, arguably to protect against damage during post-maturation drying and subsequent imbibition, prior to germination. Seed vigour is also determined during this late stage of seed development. High vigour seeds are those that can withstand the desiccation required for storage and successfully germinate under sub-optimal conditions to establish healthy seedlings. If stress proteins are involved in tolerating stress conditions, then they are likely to be important determinants of seed vigour. In this work the relationship between seed vigour (measured by seed germination performance following rapid aging, or under water stress) inBrassica oleraceavar.capitataand the content of two classes of stress protein (dehydrins and a low molecular weight heat shock protein HSP17.6) at maturity was examined. Dehydrins did not show a positive relationship with seed performance. However, the protein HSP17.6 showed a positive correlation with seed performance, and a treatment that reduced the amount of this protein in the seed also caused a reduction in subsequent seed performance.
The impact of groundwater level on soil seed bank survival
Authors: Bekker R. M. , Oomes M. J. M. , Bakker J. P.
Published: September 2008

Seed longevity of plant species is an important topic in restoration management, and little is known about the effects of environmental conditions on seed survival and longevity under natural conditions. Therefore, the effect of groundwater level on the survival of seeds in the soil seed bank of a natural grassland community was investigated. Large soil cores, mesocosms, were sampled from a grassland site and transferred to two basins under a glass roof. The mesocosms were subjected to different groundwater-level treatments (high and low, respectively 5 and 30 cm below the soil surface) for nearly three years. After that period the soil seed bank of the mesocosms was sampled. In total 15 789 seeds of 38 taxa emerged from the experiment. Significant differences between the number of viable seeds that emerged in the two treatments were found for several species. More seeds ofGlyceria fluitans, Cardamine pratensisandMyosotis palustrisgerminated in the high water-level treatment, whereas fewer seeds ofJuncusspp.,Cerastium fontanumandStellaria mediawere found in this treatment than in the low water-level treatment. The experiment showed that the anoxic conditions prevailing in the high water-level treatment were beneficial to the survival of seeds of species of wet grassland communities. Species of dry grasslands, although represented by only two species, survived better under aerobic conditions.
Effects of the metal pollutants cadmium and nickel on soybean seed development
Authors: Malan H. L. , Farrant J. M.
Published: September 2008

The chloride salts of Cd or Ni were added to the nutrient solution in which soybean (Glycine max) plants were grown and the response of the plants to these pollutants examined. Both metals markedly reduced plant biomass and seed production. Accumulation was mostly in the roots. Nickel was more mobile than Cd, reaching higher levels in all plant parts, especially seeds. Within the tissues of mature seeds, the highest concentrations of Ni were found in the axis and testa. The highest concentrations of Cd were in the testa and cotyledon, and the lowest in the axis. When expressed on a per seed basis, metal contents of these organs increased with developmental age. Nickel amounts were lower in the pods than the seeds for all growth stages, however there was no significant difference for Cd. Cadmium reduced mature seed mass. This effect was mostly due to decreased yields of lipids, protein and carbohydrates. Although the number of seeds per pod declined as a response to Ni, seed mass was unaffected and there was no apparent effect on storage reserves.
Endosperm cap weakening and endo-β-mannanase activity during priming of tomato (Lycopersicon esculentumcv. Moneymaker) seeds are initiated upon crossing a threshold water potential
Authors: Toorop Peter E. , van Aelst Adriaan C. , Hilhorst Henk W. M.
Published: September 2008

The relationship between endosperm cap weakening and endo-β-mannanase activity during priming and the time to germination after priming was studied in tomato (Lycopersicon esculentum) seeds. During priming of seeds in −0.4 MPa PEG, the mechanical restraint of the endosperm cap decreased while the endo-β-mannanase activity in the endosperm cap increased. There was no decrease in required puncture force and no increase in endo-β-mannanase activity in seeds during priming in −1.0 MPa PEG. Two classes of seeds could be distinguished during priming in −0.7 MPa PEG: one with decreased required puncture force and one without. A strong correlation was found between the lowering of the mechanical restraint and endo-β-mannanase activity. It was concluded that individual seeds have to cross a threshold water potential in order to develop enzyme activity and lower their mechanical restraint. A decrease in required puncture force and increase in endo-β-mannanase activity correlated with ice crystal-induced porosity in the endosperm cap cell walls in scanning micrographs. It was presumed that ice crystal-induced porosity reflects cell-wall hydrolysis. Germination time after priming correlated positively with required puncture force during priming, depending on the osmotic potential. Seeds in −1.0 MPa PEG improved their time to germination, without a decrease in the required puncture force. Therefore it was concluded that lowering of the endosperm restraint during priming positively affects the time to germination of primed seeds but is not a prerequisite for rapid germination.
A comparative study of seed dormancy and germination in an annual and a perennial species of Senna (Fabaceae)
Authors: Baskin Jerry M. , Nan Xiaoying , Baskin Carol C.
Published: September 2008

Seed dormancy and germination ofSenna marilandicaandS. obtusifoliawere compared in greenhouse and laboratory studies. About 90% of theS. obtusifoliaseeds were green and had hard seed coat dormancy, whereas the other 10% were brown and nondormant. Seed-colour morphs did not occur inS. marilandica, and nearly 100% of the seeds had hard seed coat dormancy. Seeds ofS. obtusifoliawere significantly heavier than those ofS. marilandica. Mechanical scarification was very effective in overcoming dormancy in seeds of both species. However, concentrated sulfuric acid, absolute ethanol and boiling water were less effective in breaking dormancy in seeds ofS. marilandicathan in those ofS. obtusifolia. Further, incubating seeds at 30/15 to 40/25°C and dry-heat treatments at 80–100°C were ineffective in breaking dormancy inS. marilandica, but significantly increased germination percentages inS. obtusifolia. In neither species were simulated daily/seasonal temperature shifts effective in breaking dormancy. Scarified seeds of both species germinated over a wide range of temperatures in both light and darkness. Under near-natural temperature conditions, seeds ofS. marilandicagerminated in spring only, whereas those ofS. obtusifoliaemerged in late spring and throughout summer. Both species can form a long-lived seed bank. Dormancy break by high field temperatures in seeds ofS. obtusifoliaallows this species to germinate throughout the warm growing season and thus contributes to its success as a weed in arable crops.
Environment and integrated agricultural systems
Authors: Hendrickson J.R. , Liebig M.A. , Sassenrath G.F.
Published: September 2008

Modern agriculture has done an excellent job producing food, feed and fiber for the world's growing population, but there are concerns regarding its continued ability to do so, especially with the world's limited resources. To adapt to these challenges, future agricultural systems will need to be diverse, complex and integrated. Integrated agricultural systems have many of these properties, but how they are shaped by the environment and how they shape the environment is still unclear. In this paper, we used commonly available county-level data and literature review to answer two basic questions. First, are there environmental limitations to the adoption of integrated agricultural systems? Second, do integrated agricultural systems have a lower environmental impact than more specialized systems? We focused on the Great Plains to answer these questions. Because of a lack of farm-level data, we used county-level surrogate indicators. The indicators selected were percent land base in pasture and crop diversity along a precipitation gradient in North Dakota, South Dakota, Nebraska and Kansas. Evaluated over the four-state region, neither indicator had a strong relationship with precipitation. In the Dakotas, both percent pasture land and crop diversity suggested greater potential for agricultural integration at the mid-point of the precipitation gradient, but there was no clear trend for Kansas and Nebraska. Integrated agricultural systems have potential to reduce the impact of agriculture on the environment despite concerns with nutrient management. Despite advantages, current adoption of integrated agricultural systems appears to be limited. Future integrated agricultural systems need to work with environmental limitations rather than overcoming them and be capable of enhancing environmental quality.
A 4‐year zonal climatology of lower tropospheric CO2 derived from ocean‐only Atmospheric Infrared Sounder observations
Authors: Strow L. Larrabee , Hannon Scott E.
Published: September 2008

A 4‐year zonally averaged climatology of atmospheric CO2, ocean only, between ±60° latitude has been derived from the Atmospheric Infrared Sounder (AIRS) radiances. Using only very clear fields of view, the CO2 profile in the computed radiances is scaled until agreement is found with observations. ECMWF forecast and analysis fields are used for the temperature profile in the computed radiances. The AIRS channels used to derive CO2 amounts are nominally sensitive to CO2 variability in the ∼300–800 mbar region (2–9 km), significantly lower in the atmosphere than that in previous studies using AIRS. Validation using aircraft measurements of CO2 at 650 mbar indicates that the AIRS CO2 results presented here are accurate to the 0.5–1.0 ppm level. The AIRS‐derived climatology clearly exhibits the CO2 rectifier effect, with mean CO2 values several parts per million lower than in those in the boundary layer. The AIRS CO2 seasonal cycle has a relatively constant amplitude of ∼3 ppm from +10° to +60° latitude, which matches the boundary layer seasonal cycle amplitude near +10° latitude but is about three times smaller than that in the boundary layer amplitude at +60° latitude. Phase comparisons between the AIRS and boundary layer CO2 seasonal cycles show the boundary layer phase leading AIRS in the Northern Hemisphere until ∼+10° latitude, where the phases cross and the AIRS higher‐altitude CO2 begins to lead the boundary layer phase down to ∼−10° latitude. These results may offer new insight into CO2 interhemispherical transport. Growth rates derived from the AIRS CO2 climatology are 2.21 ± 0.24 ppm/year, in good agreement with in situ measurements.
Wood dynamics in headwater streams of the Colorado Rocky Mountains
Authors: Wohl Ellen , Goode Jaime R.
Published: September 2008

An 11‐year monitoring study begun in 1996 evaluates wood mobility in five Colorado Rocky Mountain streams. Each channel reach is 40–70 m in length. Initial surveys included channel dimensions and arrangement of each piece of wood. Annual resurveys focused on wood arrangement and persistence. Average diameter of 15 cm and length of 3.2 m varied little among sites. Average yearly mobility ranged from 16% to 23%. Average residence time was 3.4 years. Wood load correlates positively with valley width and channel gradient, and negatively with relative substrate submergence and mean annual peak discharge. Survival analysis revealed that individual piece residence time was controlled by a nondimensional piece length and peak unit stream power during the year of removal. Residence time increases as piece length relative to channel width decreases, which could be explained by a greater integration of the flow field for longer pieces. Mobility of individual pieces of wood is controlled primarily by piece characteristics (length, diameter, type). Likelihood of mobility is smallest for buried pieces. The brevity of residence time relative to studies from other regions likely results from relatively low wood loads in these channels after timber harvesting cleared both instream and riparian wood supply more than a century ago. Although individual pieces of wood are exchanged, wood load and the location of individual logjams remain relatively constant.
Flow‐weighted values of runoff tracers (δ18O, DOC, Ba, alkalinity) from the six largest Arctic rivers
Authors: Cooper L. W. , McClelland J. W. , Holmes R. M. , Raymond P. A. , Gibson J. J. , Guay C. K. , Peterson B. J.
Published: September 2008

We present new flow‐weighted data for δ18OH2O, dissolved organic carbon (DOC), dissolved barium and total alkalinity from the six largest Arctic rivers: the Ob', Yenisey, Lena, Kolyma, Yukon and Mackenzie. These data, which can be used to trace runoff, are based upon coordinated collections between 2003 and 2006 that were temporally distributed to capture linked seasonal dynamics of river flow and tracer values. Individual samples indicate significant variation in the contributions each river makes to the Arctic Ocean. Use of these new flow‐weighted estimates should reduce uncertainties in the analysis of freshwater transport and fate in the upper Arctic Ocean, including the links to North Atlantic thermohaline circulation, as well as regional water mass analysis. Additional improvements should also be possible for assessing the mineralization rate of the globally significant flux of terrigenous DOC contributed to the Arctic Ocean by these major rivers.
Analysis of variability and trends of extreme rainfall events over India using 104 years of gridded daily rainfall data
Authors: Rajeevan M. , Bhate Jyoti , Jaswal A. K.
Published: September 2008

In this study, using 104 years (1901–2004) of high resolution daily gridded rainfall data, variability and long‐term trends of extreme rainfall events over central India have been examined. Frequency of extreme rainfall events shows significant inter‐annual and inter‐decadal variations in addition to a statistically significant long term trend of 6% per decade. Detailed analysis shows that inter‐annual, inter‐decadal and long‐term trends of extreme rainfall events are modulated by the SST variations over the tropical Indian Ocean. The present study supports the hypothesis that the increasing trend of extreme rainfall events in the last five decades could be associated with the increasing trend of sea surface temperatures and surface latent heat flux over the tropical Indian Ocean. In the global warming scenario, the coherent relationship between Indian Ocean SST and extreme rainfall events suggests an increase in the risk of major floods over central India.
Processive kinesins require loose mechanical coupling for efficient collective motility
Authors: Bieling Peter , Telley Ivo A , Piehler Jacob , Surrey Thomas
Published: September 2008

Processive motor proteins are stochastic steppers that perform actual mechanical steps for only a minor fraction of the time they are bound to the filament track. Motors usually work in teams and therefore the question arises whether the stochasticity of stepping can cause mutual interference when motors are mechanically coupled. We used biocompatible surfaces to immobilize processive kinesin‐1 motors at controlled surface densities in a mechanically well‐defined way. This helped us to study quantitatively how mechanical coupling between motors affects the efficiency of collective microtubule transport. We found that kinesin‐1 constructs that lack most of the non‐motor sequence slow each other down when collectively transporting a microtubule, depending on the number of interacting motors. This negative interference observed for a motor ensemble can be explained quantitatively by a mathematical model using the known physical properties of individual molecules of kinesin‐1. The non‐motor extension of kinesin‐1 reduces this mutual interference, indicating that loose mechanical coupling between motors is required for efficient transport by ensembles of processive motors.
Plasticity of Drosophila Stat DNA binding shows an evolutionary basis for Stat transcription factor preferences
Authors: Rivas María Luisa , Cobreros Laura , Zeidler Martin P , Hombría James Castelli‐Gair
Published: September 2008

In vertebrates, seven signal transducer and activator of transcription (STAT) proteins bind to palindromic sites separated by spacers of two or three nucleotides (STAT1), four nucleotides (STAT6) or three nucleotides (STAT2 to STAT5a/b). This diversity of binding sites provides specificity to counter semiredundancy and was thought to be a recent evolutionary acquisition. Here, we examine the natural DNA‐binding sites of the single Drosophila Stat and show that this is not the case. Rather, Drosophila Stat92E is able to bind to and activate target gene expression through both 3n and 4n spaced sites. Our experiments indicate that Stat92E has a higher binding affinity for 3n sites than for 4n sites and suggest that the levels of target gene expression can be modulated by insertion and/or deletion of single bases. Our results indicate that the ancestral STAT protein had the capacity to bind to 3n and 4n sites and that specific STAT binding preferences evolved with the radiation of the vertebrate STAT family.
High resolution energy analyzer for broad ion beam characterization
Authors: Kanarov V. , Siegfried D. , Sferlazzo P. , Hayes A. , Yevtukhov R.
Published: September 2008

Characterization of the ion energy distribution function (IEDF) of low energy high current density ion beams by conventional retarding field and deflection type energy analyzers is limited due to finite ion beam emittance and beam space charge spreading inside the analyzer. These deficiencies are, to a large extent, overcome with the recent development of the variable-focusing retarding field energy analyzer (RFEA), which has a cylindrical focusing electrode preceding the planar retarding grid. The principal concept of this analyzer is conversion of a divergent charged particle beam into a quasiparallel beam before analyzing it by the planar retarding field. This allows analysis of the beam particle total kinetic energy distribution with greatly improved energy resolution. Whereas this concept was first applied to analyze 5–10keV pulsed electron beams, the present authors have adapted it to analyze the energy distribution of a low energy (⩽1KeV) broad ion beam. In this paper we describe the RFEA design, which was modified from the original, mainly as required by the specifics of broad ion beam energy analysis, and the device experimental characterization and modeling results. Among the modifications, an orifice electrode placed in front of the RFEA provides better spatial resolution of the broad ion beam ion optics emission region and reduces the beam plasma density in the vicinity of analyzer entry. An electron repeller grid placed in front of the RFEA collector was found critical for suppressing secondary electrons, both those incoming to the collector and those released from its surface, and improved energy spectrum measurement repeatability and accuracy. The use of finer mesh single- and double-grid retarding structures reduces the retarding grid lens effect and improves the analyzer energy resolution and accuracy of the measured spectrum mean energy. However, additional analyzer component and configuration improvements did not further change the analyzed IEDF shape or mean energy value. This led us to conclude that the optimized analyzer construction provides an energy resolution considerably narrower than the investigated ion beam energy spectrum full width at half maximum, and the derived energy spectrum is an objective and accurate representation of the analyzed broad ion beam energy distribution characteristics. A quantitative study of the focusing voltage and retarding grid field effects based on the experimental data and modeling results have supported this conclusion.
Rare events via multiple reaction channels sampled by path replica exchange
Authors: Bolhuis Peter G.
Published: September 2008

Transition path sampling (TPS) was developed for studying activated processes in complex systems with unknown reaction coordinate. Transition interface sampling (TIS) allows efficient evaluation of the rate constants. However, when the transition can occur via more than one reaction channel separated by a high barrier, TPS and TIS are ineffective in sampling both channels. The combination of replica exchange with TIS can overcome this problem. This work shows how, by including both the backward and forward reactions, the corresponding rate constants, as well as the free energy barrier can be computed in a single simulation. The method is illustrated on a two dimensional potential using the Langevin dynamics. In addition, a simpler algorithm based on only forward shooting from the interfaces is shown to give equally accurate results, and forms a bridge between the transition interface and the forward flux sampling methods. The diffusive behavior of the replicas can be used to assess the quality of the choice of the order parameter used for the interfaces.
Effects of high-fluence ion implantation on colorless diamond self-standing films
Authors: Amekura H. , Kishimoto N.
Published: September 2008

Self-standing polycrystalline diamond films fabricated by chemical vapor deposition, which were transparent up to the intrinsic band edge of ∼5.5 eV, were implanted with boron negative dimer ions (B2−) of 60 keV at various fluences ranging from 1×1014 to 3×1017 B/cm2. Even at the lowest fluence of 1×1014 B/cm2, a weak color darkening was observed by the naked eye, indicating the optical absorption due to damage, not to implants. The subbandgap absorption tail increases with the fluence to the powers of ∼0.5 and ∼0.2 in the fluence regions lower and higher, respectively, than the transition fluence of ∼1×1016 B/cm2. The implanted regions also show large surface swelling of up to ∼60 nm in height. The swelling shows the same two-step power-law dependence with the same transition fluence. The same two-step power-law fluence dependence with the same transition fluence is also observed in the intensity of the defect Raman band around 1520 cm−1. From the good agreement between the estimated volume change due to graphitization and the measured swelling, the transition fluence is ascribed to the fluence where all the diamond structures in the implanted layer are transformed to graphitelike structures.
Bias dependent dielectric relaxation dynamics of electrically tuned large-scale aligned zinc oxide nanorods in nematic liquid crystal host
Authors: Nayek P. , Ghosh S. , Karan S. , Majumder T. Pal , Roy S. K.
Published: September 2008

It was observed that mixed ZnO nanorods and twisted nematic liquid crystals (LCs) show highly ordered molecular system. The observed molecular relaxation arose due to a reorientation of long molecular axis of the order of 400 kHz for pure ZLI-1636, while such relaxation was shifted to a lower frequency for mixture. By using the proposed equations, f=fDB−α exp[−EV/(B−BC)] and σ=σDB−sα exp[−sEV/(B−BC)], the obtained equivalent activation energy was increased remarkably by the introduction of ZnO nanorods in pure LC. A strong long-range interaction is established in 0.01% ZnO nanorods mixed LC system.
Microscopic calculation of the sticking force for nanodrops on an inclined surface
Authors: Berim Gersh O. , Ruckenstein Eli
Published: September 2008

A two-dimensional nanodrop on a vertical rough solid surface is examined using a nonlocal density functional theory in the presence of gravity. The roughness is modeled either as a chemical inhomogeneity of the solid or as a result of the decoration with pillars of a smooth homogeneous surface. From the obtained fluid density distribution, the sticking force, which opposes the drop motion along an inclined surface, and the contact angles on the lower and upper leading edges of the drop are calculated. On the basis of these results, it is shown that the macroscopically derived equation for a drop in equilibrium on an inclined surface is also applicable to nanodrops. The liquid-vapor surface tension involved in this equation was calculated for various specific cases, and the values obtained are of the same order of magnitude as those obtained in macroscopic experiments.
Yellow AlGaInP/InGaP laser diodes achieved by pressure and temperature tuning
Authors: Bohdan R. , Bercha A. , Trzeciakowski W. , Dybała F. , Piechal B. , Sanayeh M. Bou , Reufer M. , Brick P.
Published: September 2008

The emission wavelength of broad-area AlGaInP/InGaP quantum-well lasers is tuned by the application of high hydrostatic pressure and low temperature from 645 down to 575 nm, i.e., from the red through the orange to yellow spectral range. Emission powers up to 300 mW are obtained in the full tuning range. The pressure and temperature dependence of threshold currents indicates that leakage occurs into the L and X minima in the barriers.
Improved operation of the nonambipolar electron source
Authors: Longmier Ben , Hershkowitz Noah
Published: September 2008

Significant improvements have been made to the nonambipolar electron source (NES), a radio frequency (rf) plasma-based electron source that does not rely on electron emission at a cathode surface [B. Longmier, S. Baalrud, and N. Hershkowitz, Rev. Sci. Instrum. 77, 113504 (2006)]. A prototype NES has produced 30 A of continuous electron current, using 2 SCCM (SCCM denotes cubic centimeter per minute at STP) Xe, 1300 W rf power at 13.56 MHz, yielding a 180 times gas utilization factor. A helicon mode transition has also been identified during NES operation with an argon propellant, using 15 SCCM Ar, 1000 W rf, and 100 G magnetic field. This NES technology has the ability to replace hollow cathode electron sources and to enable high power electric propulsion missions, eliminating one of the lifetime restrictions that many ion thrusters have previously been faced with.
Twin formation during SiC nanowire synthesis
Authors: Shim Hyun Woo , Zhang Yongfeng , Huang Hanchen
Published: September 2008

Silicon carbide (SiC) is a covalent material with many polytypes. The cubic phase, which has essentially zero formation energy, dominates in SiC nanowires. These nanowires contain twin boundaries that are far separated, in contradiction to the zero formation energy. This paper presents a model to account for the well-separated and equal-spaced twins in SiC nanowires. The model is based on the energy minimization of interfaces and edges near twin boundaries. Our theoretical result shows that the distance between neighboring twin boundaries is equal to 18%–31% of the diameter for SiC nanowires. This result is in agreement with our experimental data of SiC nanowires and also those of microwhiskers in the literature.
Influence of sub-Tg annealing on the crystallization kinetics of Cu47Ti33Zr11Ni8Si1 metallic glass
Authors: Venkataraman S. , Hermann H. , Sordelet D. J. , Eckert J.
Published: September 2008

The influence of sub-Tg preannealing on the crystallization of Cu47Ti33Zr11Ni8Si1 metallic glass powders is investigated by differential scanning calorimetry. Sub-Tg treatment induces changes in the isochronal calorimetry traces. Isothermal investigations show that transformation occurs by nucleation and growth, and there is no influence of the preannealing on the transformation kinetics in terms of the Avrami constant. Crystallization occurs by an increasing nucleation rate. A gradual but significant difference is observed in the calculated values of the activation energy. The decrease in activation energy of nanocrystallization can be explained on the basis of increased short-range ordering caused by preannealing.
Cationic and charge segregation in La2/3Ca1/3MnO3 thin films grown on (001) and (110) SrTiO3
Authors: Estradé S. , Arbiol J. , Peiró F. , Infante I. C. , Sánchez F. , Fontcuberta J. , de la Peña F. , Walls M. , Colliex C.
Published: September 2008

Electron energy-loss spectroscopy is used to map composition and electronic states in epitaxial La2/3Ca1/3MnO3 films grown on SrTiO3 (001) and (110) substrates. It is found that in partially relaxed (110) films cationic composition and valence state of Mn3+/4+ ions are preserved across the film thickness. In contrast, in fully strained (001) films, the Ca/La ratio gradually changes across the film, being La rich at film/substrate interface and La depleted at free surface; Mn valence state changes accordingly. These observations suggest that a strongly orientation-dependent adaptative composition mechanism dominates stress accommodation in manganite films and provides microscopic understanding of their dissimilar magnetic properties.
Design of a high temperature sensing system using luminescence lifetime measurement
Authors: Kamma Indumathi , Kommidi Praveena , Reddy B. Rami
Published: September 2008

Temperature sensing system has been designed and fluorescence lifetime measurements have been performed to estimate the temperature. S43/2 lifetime of LaF3:Er3+ and S52 lifetime of LaF3:Ho3+ have been measured as a function of temperature. Lifetime versus temperature calibration plots have been made up to 1000 °C.
Exploring Richtmyer–Meshkov instability phenomena and ejecta cloud physics
Authors: Zellner M. B. , Buttler W. T.
Published: September 2008

This effort investigates ejecta cloud expansion from a shocked Sn target propagating into vacuum. To assess the expansion, dynamic ejecta cloud density distributions were measured via piezoelectric pin diagnostics offset at three heights from the target free surface. The dynamic distributions were first converted into static distributions, similar to a radiograph, and then self compared. The cloud evolved self-similarly at the distances and times measured, inferring that the amount of mass imparted to the instability, detected as ejecta, either ceased or approached an asymptotic limit.
In situ stress evolution during magnetron sputtering of transition metal nitride thin films
Authors: Abadias G. , Guerin Ph.
Published: September 2008

Stress evolution during reactive magnetron sputtering of TiN, ZrN, and TiZrN layers was studied using real-time wafer curvature measurements. The presence of stress gradients is revealed, as the result of two kinetically competing stress generation mechanisms: atomic peening effect, inducing compressive stress, and void formation, leading to a tensile stress regime predominant at higher film thickness. No stress relaxation is detected during growth interrupt in both regimes. A change from compressive to tensile stress is evidenced with increasing film thickness, Ti content, sputtering pressure, and decreasing bias voltage.
Self-detecting gate-tunable nanotube paddle resonators
Authors: Witkamp B. , Poot M. , Pathangi H. , Hüttel A. K. , van der Zant H. S. J.
Published: September 2008

We have fabricated suspended metal paddle resonators with carbon nanotubes functioning as self-detecting torsional springs. We observe gate-tunable resonances that either tune to higher or to lower frequencies when increasing the dc voltage on the back gate. We attribute the former modes to flexural vibrations of the paddle resonator, while the latter ones are identified as torsional vibrations. Compared to top-down silicon fabricated paddle resonators, nanotube springs have smaller torsional spring constants and provide a larger frequency tunability.
Enhancement of two-photon excited fluorescence in two-dimensional nonlinear optical polymer photonic crystal waveguides
Authors: Inoue Shin-ichiro , Yokoyama Shiyoshi
Published: September 2008

We examined two-photon excited fluorescence (TPEF) in two-dimensional highly nonlinear optical polymer photonic crystal waveguides with metallic cladding. A large TPEF enhancement of approximately two orders of magnitude was observed, originating from resonance between the external pump laser field and a photonic band mode. The results for TPEF enhancement are in good agreement with experimental photonic band resonances obtained by angle-resolved reflectivity measurements and the theoretical photonic band structure generated by three-dimensional finite-difference time-domain calculations, indicating that it is possible to use band dispersion control to design artificial nonlinear two-photon excitation processes.
Excited-state spectroscopy on a quantum dot side coupled to a quantum wire
Authors: Otsuka T. , Abe E. , Iye Y. , Katsumoto S.
Published: September 2008

We report excited-state spectroscopy on a quantum dot side coupled to a quantum wire with accurate energy estimation. Our method utilizes periodic voltage pulses on the dot, and the energy calibration is performed with reference to the bias voltage across the wire. We demonstrate the observation on the orbital excited state and the Zeeman splitting in a single dot.
Loss mechanisms of surface plasmon polaritons on gold probed by cathodoluminescence imaging spectroscopy.
Authors: Kuttge M. , Vesseur E. J. R. , Verhoeven J. , Lezec H. J. , Atwater H. A. , Polman A.
Published: September 2008

We use cathodoluminescence imaging spectroscopy to excite surface plasmon polaritons and measure their decay length on single crystal and polycrystalline gold surfaces. The surface plasmon polaritons are excited on the gold surface by a nanoscale focused electron beam and are coupled into free space radiation by gratings fabricated into the surface. By scanning the electron beam on a line perpendicular to the gratings, the propagation length is determined. Data for single-crystal gold are in agreement with calculations based on dielectric constants. For polycrystalline films, grain boundary scattering is identified as additional loss mechanism, with a scattering coefficient SG=0.2%.
Three-dimensional optical antennas: Nanocones in an apertureless scanning near-field microscope
Authors: Fleischer M. , Stanciu C. , Stade F. , Stadler J. , Braun K. , Heeren A. , Häffner M. , Kern D. P. , Meixner A. J.
Published: September 2008

A sharp-tipped gold nanocone and the vertically aligned metallic tip of a near-field optical microscope together form a three-dimensional optical antenna with a highly controllable gap. Confocal measurements with different laser modes show the efficient axial excitation of the cones with a longitudinally polarized field. In the antenna configuration, extremely strong field enhancement up to a factor of 100 is obtained by tuning the gap between the two sharp tips down to few nanometers.
The multiple roles of cultural transmission experiments in understanding human cultural evolution
Authors: Mesoudi Alex , Whiten Andrew
Published: September 2008

In this paper, we explore how experimental studies of cultural transmission in adult humans can address general questions regarding the ‘who, what, when and how’ of human cultural transmission, and consequently inform a theory of human cultural evolution. Three methods are discussed. The transmission chain method, in which information is passed along linear chains of participants, has been used to identify content biases in cultural transmission. These concern the kind of information that is transmitted. Several such candidate content biases have now emerged from the experimental literature. The replacement method, in which participants in groups are gradually replaced or moved across groups, has been used to study phenomena such as cumulative cultural evolution, cultural group selection and cultural innovation. The closed-group method, in which participants learn in groups with no replacement, has been used to explore issues such as who people choose to learn from and when they learn culturally as opposed to individually. A number of the studies reviewed here have received relatively little attention within their own disciplines, but we suggest that these, and future experimental studies of cultural transmission that build on them, can play an important role in a broader science of cultural evolution.
Anhydrous versus hydrated N
4-substituted 1H-pyrazolo[3,4-d]pyrimidine-4,6-diamines: hydrogen bonding in two and three dimensions
Authors: Trilleras Jorge , Quiroga Jairo , Cobo Justo , Marchal Antonio , Nogueras Manuel , Low John N. , Glidewell Christopher
Published: September 2008

Ten new N
4-substituted 1H-pyrazolo[3,4-d]pyrimidine-4,6-diamines have been synthesized and the structures of nine of them are reported here, falling into two clear groups, those which are stoichiometric hydrates and those which crystallize in solvent-free forms. In each of N
4-methyl-N
4-phenyl-1H-pyrazolo[3,4-d]pyrimidine-4,6-diamine, C12H12N6 (I), N
4-cyclohexyl-N
4-methyl-1H-pyrazolo[3,4-d]pyrimidine-4,6-diamine, C12H18N6 (II), and N
4-(3-chlorophenyl)-1H-pyrazolo[3,4-d]pyrimidine-4,6-diamine, C11H9ClN6 (III), the molecules are linked into hydrogen-bonded sheets. The molecules of 2-{4-(6-amino-1H-pyrazolo[3,4-d]pyrimidin-4-yl)piperazin-1-yl}ethanol, C11H17N7O (IV), are linked into a three-dimensional framework, while the structure of N
4-methyl-N
4-(4-methylphenyl)-1H-pyrazolo[3,4-d]pyrimidine-4,6-diamine monohydrate, C13H14N6·H2O (V), is only two-dimensional despite the presence of five independent hydrogen bonds. The stoichiometric hemihydrates N
4-ethyl-N
4-phenyl-1H-pyrazolo[3,4-d]pyrimidine-4,6-diamine hemihydrate, C13H14N6·0.5H2O (VI) and N
4-(4-methoxyphenyl)-N
4-methyl-1H-pyrazolo[3,4-d]pyrimidine-4,6-diamine hemihydrate, C13H14N6O·0.5H2O (VII), exhibit remarkably similar sheet structures, despite different space groups and Z′ values, Z′ = 0.5 in C2/c for (VI) and Z′ = 1 in P\bar 1 for (VII). N
4-4-Benzyl-N
4-phenyl-1H-pyrazolo[3,4-d]pyrimidine-4,6-diamine monohydrate, C18H16N6·H2O (VIII), crystallizes with Z′ = 2 in P21/n, and the four independent molecular components are linked into sheets by a total of 11 intermolecular hydrogen bonds. The sheet structure in {4-(pyrrolidin-1-yl)-1H-pyrazolo[3,4-d]pyrimidine-6-amine} ethanol hemisolvate hemihydrate, C9H12N6·0.5C2H6O·0.5H2O (IX), is built from the pyrimidine and water components only; it contains eight independent hydrogen bonds, and it very closely mimics the sheets in (VI) and (VII); the ethanol molecules are pendent from these sheets. The N
4-alkyl-N
4-aryl-4-aminopyrazolopyrimidine molecules in (I), (V)–(VIII) all adopt very similar conformations, dominated in each case by an intramolecular C—H...π(arene) hydrogen bond: this interaction is absent from (III) where the molecular conformation is entirely different and probably dominated by the intermolecular hydrogen bonds.
Regulation of TGF‐β family signaling by E3 ubiquitin ligases
Authors: Inoue Yasumichi , Imamura Takeshi
Published: September 2008

Members of the transforming growth factor‐β (TGF‐β) family, including TGF‐β, activin and bone morphogenetic proteins (BMPs), are multifunctional proteins that regulate a wide variety of cellular responses, such as proliferation, differentiation, migration and apoptosis. Alterations in their downstream signaling pathways are associated with a range of human diseases like cancer. TGF‐β family members transduce signals through membrane serine/threonine kinase receptors and intracellular Smad proteins. The ubiquitin–proteasome pathway, an evolutionarily conserved cascade, tightly regulates TGF‐β family signaling. In this pathway, E3 ubiquitin ligases play a crucial role in the recognition and degradation of target proteins by the 26S proteasomes. Smad degradation regulates TGF‐β family signaling; HECT (homologous to the E6‐accessory protein C‐terminus)‐type E3 ubiquitin ligases, Smad ubiquitin regulatory factor 1 (Smurf1), Smurf2, and a RING‐type E3 ubiquitin ligase, ROC1‐SCFFbw1a have been implicated in Smad degradation. Smurf1 and Smurf2 bind to TGF‐β family receptors via the inhibitory Smads, Smad6 and Smad7, to induce their ubiquitin‐dependent degradation. Arkadia, a RING‐type E3 ubiquitin ligase, induces the ubiquitination and degradation of Smad7 and corepressors, c‐Ski and SnoN, to enhance TGF‐β family signaling. Abnormalities in E3 ubiquitin ligases that control components of TGF‐β family signaling may lead to the development and progression of various cancers. (Cancer Sci 2008; 99: 2107–2112)
Helicobacter pylori eradication in long‐term proton pump inhibitor users is highly cost‐effective: economic analysis of the HELPUP trial
Authors: MASON J. M. , RAGHUNATH A. S. , HUNGIN A. P. S. , JACKSON W.
Published: September 2008

Background  Proton pump inhibitor (PPI) use is costly and about two‐thirds of prescribing is long‐term. Although 20–50% of patients may be infected with Helicobacter pylori, eradication is not normal clinical practice.

Aim  To establish if H. pylori eradication in long‐term PPI users is cost‐effective.

Methods  Long‐term PPI‐using patients (n = 183) testing positive for H. pylori were randomly assigned to true or placebo eradication therapy. Patients provided 2‐year resource data, and 1‐year symptom severity scores. A within‐trial cost effectiveness analysis was conducted from a British health service perspective.

Results  Significant reductions in resource use occurred comparing eradication with placebo. After 2 years, PPI prescriptions (full‐dose equivalents) fell by 3.9 (P < 0.0001); clinician (GP) consultations by 2.4 (P = 0.0001); upper gastrointestinal (GI) endoscopies by 14.8% (P = 0.008); clinician GI‐related home visits by 19.9% (P = 0.005) and abdominal ultrasound scans fell by 20.3% (P = 0.005). Average net savings/patient were £93 (95% CI: 33–153) after costs of detection and eradication had been deducted. At 1 year, Leeds Dyspepsia Questionnaire symptoms fell by 3.1 (P = 0.005) and quality‐of‐life measures improved (EuroQol‐5D: 0.089, P = 0.08; visual analogue scale: 5.6, P = 0.002) favouring eradication.

Conclusion  Helicobacter pylori eradication in infected, long‐term PPI users is an economically dominant strategy, significantly reducing overall healthcare costs and symptom severity.
The effect of naloxone‐3‐glucuronide on colonic transit time in healthy men after acute morphine administration: a placebo‐controlled double‐blinded crossover preclinical volunteer study
Authors: NETZER P. , SENDENSKY A. , WISSMEYER M. P. , BAUMELER S. , BATISTA C. , SCHEURER U. , KRAUSE T. , REBER P. , BRENNEISEN R.
Published: September 2008

Background  Constipation is a significant side effect of opioid therapy. We have previously demonstrated that naloxone‐3‐glucuronide (NX3G) antagonizes the motility‐lowering‐effect of morphine in the rat colon.

Aim  To find out whether oral NX3G is able to reduce the morphine‐induced delay in colonic transit time (CTT) without being absorbed and influencing the analgesic effect.

Methods  Fifteen male volunteers were included. Pharmacokinetics: after oral administration of 0.16 mg/kg NX3G, blood samples were collected over a 6‐h period. Pharmacodynamics: NX3G or placebo was then given at the start time and every 4 h thereafter. Morphine (0.05 mg/kg) or placebo was injected s.c. 2 h after starting and thereafter every 6 h for 24 h. CTT was measured over a 48‐h period by scintigraphy. Pressure pain threshold tests were performed.

Results  Neither NX3G nor naloxone was detected in the venous blood. The slowest transit time was observed during the morphine phase, which was significantly different from morphine with NX3G and placebo. The pain perception was not significantly influenced by NX3G.

Conclusions  Orally administered NX3G is able to reverse the morphine‐induced delay of CTT in humans without being detected in peripheral blood samples. Therefore, NX3G may improve symptoms of constipation in‐patients using opioid medication without affecting opioid‐analgesic effects.
Patient safety incidents associated with equipment in critical care: a review of reports to the UK National Patient Safety Agency
Authors: Thomas A. N. , Galvin I.
Published: September 2008

We reviewed all patient safety incidents reported to the UK National Patient Safety Agency between August 2006 and February 2007 from intensive care or high dependency units. Incidents involving equipment were then categorised. A total of 12 084 incidents were submitted from 151 organisations (median (range) 40 (1–634) per organisation). Of these, 1021 incidents were associated with use of equipment, most commonly involving syringe pumps/infusion devices (185 incidents), ventilators (164 incidents), haemofilters (107 incidents) and monitoring equipment (70 incidents). Twenty‐nine incidents were associated with more than temporary harm to patients. Failure or faulty equipment was described in 537 incidents (26% with some harm) and incorrect setting or use was described in 358 incidents; these were more likely to be associated with harm (39%; p = 0.001). We suggest changes to improve the reporting of incidents and to improve equipment safety.
Effects of light history on primary productivity in a phytoplankton community dominated by the toxic cyanobacterium Cylindrospermopsis raciborskii
Authors: O’BRIEN K. R. , BURFORD M. A. , BROOKES J. D.
Published: September 2008

1. The effects of instantaneous irradiance and short‐term light history on primary production were determined for samples from a subtropical water reservoir dominated by the toxic cyanobacterium Cylindrospermopsis raciborskii. 14C‐bicarbonate uptake incubations were conducted on water samples from the reservoir, for irradiance (photosynthetically active radiation) ranging from 0 to 1654 μmol quanta m−2 s−1. Prior to the 14C incubations, cells were pre‐treated at irradiance levels ranging from 0 to 1006 μmol quanta m−2 s−1.

2. The average irradiance experienced by cells during the 2–2.5 h pre‐treatment incubations affected the productivity–irradiance (P–I) parameters: exposure to high light in pre‐treatment conditions caused a substantial decrease in maximum rate of primary production Pmax and the photoinhibition parameter β when compared to cells pre‐treated in the dark.

3. While the data collected in this study were not sufficient to develop a full dynamic model of C. raciborskii productivity, Pmax and β were modelled as a function of pre‐treatment irradiance, and these models were applied to predict the rate of primary production as a function of both instantaneous and historical irradiance. The results indicated that while cells with a history of exposure to high irradiance will be the most productive in high irradiance, production rates will be highest overall for dark‐acclimated cells in moderate irradiance.

4. Our results may explain why optically‐deep mixing favours C. raciborskii. If the mixing depth zm exceeds the euphotic depth zeu, cells will be dark‐acclimated, which will increase their rate of production when they are circulated through the euphotic zone. These results also predict that production rates will be higher during morning hours than for the same irradiance in the afternoon, which is consistent with other phytoplankton studies.

5. Since the rate of production of C. raciborskii‐dominated systems cannot be described by a single P–I curve, accurate estimates of production rates will require measurements over the daily light cycle.