bluuebunny/crossref_metadata_2025 huggingface dataset:
An experimental study of flow through rigid vegetation
Authors: Liu D. , Diplas P. , Fairbanks J. D. , Hodges C. C.
Published: December 2008

Better understanding of the role of vegetation in the transport of fluid and pollutants requires improved knowledge of the detailed flow structure within the vegetation. Instead of spatial averaging, this study uses discrete measurements at multiple locations within the canopy to develop velocity and turbulence intensity profiles and observe the changes in the flow characteristics as water travels through a vegetation array simulated by rigid dowels. Velocity data was collected with a one dimensional laser Doppler velocimeter under emergent and submerged flow conditions. The effects of dowel arrangement, density, and roughness were also examined. The results show that the velocity within the vegetation array is constant with depth and the velocity profile is logarithmic above it, however the boundaries are marked by inflection points. The strongest vortices and turbulence intensities can be found there, especially in the region immediately downstream of a dowel. These results support the idea that the flow in the region near the bed and at the top of the dowel array is very unstable leading to the formation of coherent structures and are areas of significant mass and momentum exchange.
Stable isotope probing reveals Trichosporon yeast to be active in situ in soil phenol metabolism
Authors: DeRito Christopher M , Madsen Eugene L
Published: December 2008

The aim of this study was to extend the results of our previous stable isotope probing (SIP) investigation: we identified a soil fungus involved in phenol biodegradation at an agricultural field site. DNA extracts from our previous study were examined using fungi-specific PCR amplification of the 18S–28S internal transcribed spacer (ITS) region. We prepared an 80-member clone library using PCR-amplified, 13C-labeled DNA derived from field soil that received 12 daily doses of 13C-phenol. Restriction-fragment-length-polymorphism screening and DNA sequencing revealed a dominant clone (41% of the clone library), the ITS sequence of which corresponded to that of the fungal genus Trichosporon. We successfully grew and isolated a white, filamentous fungus from site soil samples after plating soil dilutions on mineral salts agar containing 250 p.p.m. phenol. Restreaking on both yeast extract–peptone–galactose and Sabouraud dextrose agar plates led to further purification of the fungus, the morphological characteristics of which matched those of the genus Trichosporon. The ITS sequence of our isolated fungus was identical to that of a clone from our SIP-based library, confirming it to be Trichosporon multisporum. High-performance liquid chromatography and turbidometeric analyses showed that the culture was able to metabolize and grow on 200 p.p.m. phenol in an aqueous mineral salts medium within 24 h at room temperature. Gas chromatography–mass spectrometry analysis of 13CO2 respiration from laboratory soil incubations demonstrated accelerated phenol mineralization in treatments inoculated with T. multisporum. These findings show that T. multisporum actively degraded phenol in our field-based, soil experiments.
Timing feedback-inhibition of the male reproductive hormone axis
Authors: Malik Ritu , Tondwal Shailesh , Venkatesh K Subramanian , Gupta Gopal , Misra Amit
Published: December 2008

Hormonal methods of male contraception have addressed feedback-inhbition of the cascade of hormones that has evolved to regulate sperm production but high concentrations of testosterone (T) in the blood have not worked satisfactorily. We hypothesized that an episodic event, such as degranulation of gonadotropin-releasing hormone (GnRH) neurons in the hypothalamus, could be as well inhibited by episodic interference as by continuously-applied suppression. We used a computational model of hypothalamus-pituitary-gonad axis described by Veldhuis et al. to test the hypothesis that episodic administration of T would inhibit GnRH and/or luteinizing hormone (LH) secretion. A set of stochastic differential equations model feedback as well as feed-forward actions of GnRH, LH and T. The model predicted feedback-inhibition of GnRH pulses in a dose and frequency dependent manner when transdermal patches or injections delivering pulsatile T were applied. Since the published model did not address the effect of chronic GnRH deprivation on the viability of pituitary gonadotrophes, we introduced a function to address this issue. Incorporation of this function in the model allowed the prediction of a “holiday period” in the contraceptive regimen, during which exogenous T would not be needed to protect from conception. Pulsatile T delivered by real-life transdermal delivery system applied as per a parsimonious regimen reduced secretion of LH and T and fertility. The vitality function, proposed to account for survival and proliferation of pituitary gonadotrophes correlated with in vivo observations as extensive apoptosis in the anterior pituitary was observed after application of transdermal T.
Increased expression of TGFβ type I receptor in brain tissues of patients with temporal lobe epilepsy
Authors: Lu Yang , Xue Tao , Yuan Jie , Li Yuqin , Wu Yuan , Xi Zhiqin , Xiao Zheng , Chen Yangmei , Wang Xuefeng
Published: December 2008

TβRs (transforming growth factor β receptors) have recently been identified in animal experiments as being involved in the pathogenesis of epilepsy. The aim of the present study was to understand further the potential effects of TβRs in human epilepsy. Tissue samples of temporal neocortices from 30 patients with temporal lobe epilepsy were prepared for detecting TβR-I (type 1 TβR) protein expression using immunohistochemistry, immunofluorescence and Western blotting. We compared these tissues with histologically normal temporal lobes from controls. TβR-I immunoreactivity was increased in the patient group compared with controls using immunohistochemistry, and this finding was consistently observed with Western blot analysis. Immunofluorescence showed that TβR-I fluorescence stain mainly accumulated in the cytoplasm of astrocytes. In conclusion, our findings demonstrate that an up-regulation of TβR-I is present in patients with temporal lobe epilepsy.
Crystal structure prediction of LiBeH3 using ab initio total-energy calculations and evolutionary simulations
Authors: Hu Chao-Hao , Oganov A. R. , Wang Y. M. , Zhou H. Y. , Lyakhov A. , Hafner J.
Published: December 2008

The stable crystal structure of LiBeH3 is predicted on the basis of ab initio total-energy calculations using density-functional theory and an extended database of candidate structures and using global optimizations based on an evolutionary algorithm. At the level of density-functional theory, a CaSiO3_1-type structure with space group P21/c, containing BeH4 tetrahedra linked in chains, is the ground-state structure of LiBeH3 (α-LiBeH3). It is found to be lower in energy than the structures proposed in previous studies. The analysis of the electronic structure shows that α-LiBeH3 is an insulator with a band gap of about 4.84 eV and exhibits strong covalent bonding in the BeH4 tetrahedral complexes. Calculations at finite temperatures and high pressures suggest that at T=408 K and ambient pressure a structural transition from α-LiBeH3 (CaSiO3-type) to a YBO3-type structure with space group Cmcm occurs and that at a pressure of 7.1 GPa α-LiBeH3 undergoes a pressure-induced structural transition from the α-phase to a MgSiO3-type structure with space group C2/c. The calculated enthalpies of formation (−45.36 and −30.12 kJ/mol H2 without and with zero-point energy corrections) are in good agreement with the experimental result, indicating that LiBeH3 is a potential hydrogen storage material with low activation barriers for hydrogen desorption.
Fluorine diffusion assisted by diffusing silicon on the Si(111)-(7×7) surface
Authors: Fujikawa Y. , Kuwano S. , Nakayama K. S. , Nagao T. , Sadowski J. T. , Bahktizin R. Z. , Sakurai T. , Asari Y. , Nara J. , Ohno T.
Published: December 2008

The diffusion process of fluorine (F) atoms on the Si(111)-(7×7) surface is investigated using high-temperature scanning tunneling microscopy. The kinetic parameters of F hopping agree well with those of the diffusing silicon (Si) atoms, which implies that of all reaction processes, the Si diffusion serves as the rate-determining one. Deposition of Si on the surface is found to enhance F hopping, which supports the above-mentioned observation. Theory reveals that the replacement of F adsorption sites by diffusing Si atoms is the key process in the diffusion mechanism.
Two-dimensional quantum effects in “ultimate” nanoscale metal-oxide-semiconductor field-effect transistors
Authors: Walls Thomas J. , Likharev Konstantin K.
Published: December 2008

We have carried out a thorough analysis of quantum effects in sub-10-nm silicon double-gate field-effect transistors with ultrathin undoped channels connecting highly doped bulk electrodes, using a self-consistent solution of the two-dimensional (2D) Schrödinger and Poisson equations in a mixed momentum-space representation. The results are compared with the earlier solution of the same problem using the one-dimensional (1D) Schrödinger equation. The 2D theory confirms the basic qualitative conclusions of the 1D theory, but shows that at large values of source-drain voltage, the 1D approximation underestimates the electron backscattering into the source. As a result, the drain current saturates better than the 1D approximation predicts. Our results indicate also that the on/off current performance expectations in an influential industrial forecast are way too optimistic, regardless of the possible gate insulation material improvement.
Beyond harmonic sounds in a simple model for birdsong production
Authors: Amador Ana , Mindlin Gabriel B.
Published: December 2008

In this work we present an analysis of the dynamics displayed by a simple bidimensional model of labial oscillations during birdsong production. We show that the same model capable of generating tonal sounds can present, for a wide range of parameters, solutions which are spectrally rich. The role of physiologically sensible parameters is discussed in each oscillatory regime, allowing us to interpret previously reported data.
Experiments on the mechanism of inducing transition between regular and Mach reflection
Authors: Mouton Christopher A. , Hornung Hans G.
Published: December 2008

A study of the mechanism by which disturbances can cause tripping between steady-flow regular and Mach reflection in the dual-solution domain is presented. Computational results indicate that the disturbance shock created as a result of the impact of dense particles on one of the shock-generating wedges can cause transition from regular to Mach reflection. The disturbance shock may also be generated by direct energy deposition on the wedge. Estimates of the lower bound of the required energy for transition to occur are presented and compared to values obtained computationally. Experiments were performed at Mach 4.0 in a Ludwieg tube that has a test duration of 100 ms. Proper starting of the flow necessitated operation with an upstream diaphragm and modifications in the dump tank. The reflection state was changed by rapid rotation of one of the shock-generating wedges. The flow in the facility is sufficiently quiet to permit entering the dual-solution domain to approximately its midpoint before spontaneous transition to the Mach reflection occurs. The short test time prompted a study of the effect of wedge rotation speed on the transition from regular to Mach reflection. Transition due to deposition of energy on one of the wedges was also examined by using a pulsed laser focused on one of the two wedges. Measurements of the minimum energy to bring about transition and of the rapid growth of the Mach stem to its steady-state are compared to numerical and theoretical predictions.
Dielectric scaling of a top gate silicon nanowire on insulator transistor
Authors: Bhowmick Sishir , Alam Khairul
Published: December 2008

The effects of gate dielectric constant and thickness on the performance of a top gate silicon nanowire on insulator transistor are studied using three-dimensional quantum simulation. The replacement of SiO2 by a high-K dielectric improves the off-state current, the on/off-current ratio, the inverse subthreshold slope, and the channel transconductance and degrades the switching performance. The high-K gate dielectric provides better control of the channel potential, especially in the off-state, and improves the off-state tunneling current by almost two orders of magnitude. With high-K dielectric, the switching performance degrades primarily due to increase in gate capacitance. The gate has better control of channel potential with thinner oxide. The on/off-current ratio, inverse subthreshold slope, channel transconductance, and the switching performance improve with thinner gate oxide. Our device of 10 nm gate length, 1 nm oxide with dielectric constant of 10, has an on/off-current ratio of 1.16×108, an inverse subthreshold slope of 70.5 mV/decade, and the intrinsic unity current gain frequency of 2.7414 THz.
The role of parallel heat transport in the relation between upstream scrape-off layer widths and target heat flux width in H-mode plasmas of the National Spherical Torus Experiment
Authors: Ahn J-W. , Boedo J. A. , Maingi R. , Soukhanovskii V. ,   the NSTX Research Team
Published: December 2008

The physics of parallel heat transport was tested in the scrape-off layer (SOL) plasma of the National Spherical Torus Experiment [M. Ono et al., Nucl. Fusion 40, 557 (2000); S. M. Kaye et al., Nucl. Fusion 45, S168 (2005)] tokamak by comparing the upstream electron temperature (Te) and density (ne) profiles measured by the midplane reciprocating probe to the heat flux (q⊥) profile at the divertor plate measured by an infrared camera. It is found that electron conduction explains the near SOL width data reasonably well while the far SOL, which is in the sheath limited regime, requires an ion heat flux profile broader than the electron one to be consistent with the experimental data. The measured plasma parameters indicate that the SOL energy transport should be in the conduction-limited regime for R−Rsep (radial distance from the separatrix location) <2–3cm. The SOL energy transport should transition to the sheath-limited regime for R−Rsep>2–3cm. The Te, ne, and q⊥ profiles are better described by an offset exponential function instead of a simple exponential. The conventional relation between midplane electron temperature decay length (λTe) and target heat flux decay length (λq) is λTe=7∕2λq, whereas the newly derived relation, assuming offset exponential functional forms, implies λTe=(2–2.5)λq. The measured values of λTe∕λq differ from the new prediction by 25%–30%. The measured λq values in the far SOL (R−Rsep>2–3cm) are 9–10cm, while the expected values are 2.7<λq<4.9cm (for the sheath-limited regime). We propose that the ion heat flux profile is substantially broader than the electron heat flux profile as an explanation for this discrepancy in the far SOL.
A broadband absorption spectrometer using light emitting diodes for ultrasensitive, in situ trace gas detection
Authors: Langridge Justin M. , Ball Stephen M. , Shillings Alexander J. L. , Jones Roderic L.
Published: December 2008

A broadband absorption spectrometer has been developed for highly sensitive and target-selective in situ trace gas measurements. The instrument employs two distinct modes of operation: (i) broadband cavity enhanced absorption spectroscopy (BBCEAS) is used to quantify the concentration of gases in sample mixtures from their characteristic absorption features, and (ii) periodic measurements of the cavity mirrors’ reflectivity are made using step-scan phase shift cavity ringdown spectroscopy (PSCRDS). The latter PSCRDS method provides a stand-alone alternative to the more usual method of determining mirror reflectivities by measuring BBCEAS absorption spectra for calibration samples of known composition. Moreover, the instrument’s two modes of operation use light from the same light emitting diode transmitted through the cavity in the same optical alignment, hence minimizing the potential for systematic errors between mirror reflectivity determinations and concentration measurements. The ability of the instrument to quantify absorber concentrations is tested in instrument intercomparison exercises for NO2 (versus a laser broadband cavity ringdown spectrometer) and for H2O (versus a commercial hygrometer). A method is also proposed for calculating effective absorption cross sections for fitting the differential structure in BBCEAS spectra due to strong, narrow absorption lines that are under-resolved and hence exhibit non-Beer–Lambert law behavior at the resolution of the BBCEAS measurements. This approach is tested on BBCEAS spectra of water vapor’s 4v+δ absorption bands around 650 nm. The most immediate analytical application of the present instrument is in quantifying the concentration of reactive trace gases in the ambient atmosphere. The instrument’s detection limits for NO3 as a function of integration time are considered in detail using an Allan variance analysis. Experiments under laboratory conditions produce a 1σ detection limit of 0.25 pptv for a 10 s acquisition time, which improves with further signal averaging to 0.09 pptv in 400 s. Finally, an example of the instrument’s performance under field work conditions is presented, in this case of measurements of the sum of NO3+N2O5 concentrations in the marine boundary layer acquired during the Reactive Halogens in the Marine Boundary Layer field campaign.
Magnetic and electric transport properties of Nd0.75Sr1.25Co1−xMnxO4
Authors: Huang S. L. , Guan L. X. , Yi J. B. , Zhao B. C. , Wu Y. , Fan Z. C. , Sum T. C. , Ding J. , Wang L.
Published: December 2008

We present the results of a systematic investigation of crystal structure, dc magnetization, ac susceptibility, resistivity, and magnetoresistance (MR) of Nd0.75Sr1.25Co1−xMnxO4 (0≤x≤0.3) polycrystals. All synthesized specimens are indexed in the same tetragonal space group I4/mmm with random occupation of Co and Mn ions at the identical site. The refinement result confirms the tetragonal distortion of the CoO6 octahedron with elongation along the c axis. The substitution of the Mn ions at Co site brings about the suppression of ferromagnetism as well as the enhancement of antiferromagnetism. The coexistence of ferromagnetic double exchange interactions and antiferromagnetic superexchange interactions and the suppression of ferromagnetism with increasing Mn doping are substantiated by the isothermal magnetization hysteresis loops. The result suggests that the substitution creates more antiferromagnetic bonds with superexchange interactions at the expense of the existing Co–O–Co bonds with ferromagnetic double exchange interactions. At low temperature, a crossover from ferromagnetic cluster-glass phase to spin-glass phase is shown in the dc and ac magnetic measurements. For all the specimens, the resistivity ρ(T) follows semiconducting behavior (dρ/dT<0) in the whole measured temperature region. The substitution induces an obvious increase in resistivity, which originates from the diminishing of ferromagnetic double exchange interactions and the localization of charge carriers caused by the disorder for the substitution. The system presents negative MR due to tunneling effect at low temperatures and positive MR at high-temperature range.
Anomalous size dependence of the luminescence in reconstructed silicon nanoparticles
Authors: Wang X. , Zhang R. Q. , Lee S. T. , Frauenheim Th. , Niehaus T. A.
Published: December 2008

Using a time-dependent density-functional method, we investigated the effect of surface reconstruction in a series of hydrogen-capped silicon nanoparticles of sizes up to 2 nm with different coverage ratios of Si–Si dimers. For the models ranging from perfect bulklike to fully reconstructed configurations, changes in structural stability and optical absorption and luminescence properties were systematically studied. Excited state relaxation is sizable in these systems and gives rise to huge Stokes shifts of several eV. Contrary to the trend observed for II-VI quantum dots, luminescence energies of reconstructed Si dots increase with increasing system size, showing an “inverse quantum confinement effect.”
Aluminum-oxide tunnel barriers with high field endurance
Authors: Tan Zhongkui , Patel Vijay , Liu Xueqing , Lukens James E. , Likharev Konstantin K. , Zhu Yimei
Published: December 2008

We have measured transport properties of all-metallic tunnel junctions, fabricated using rf-plasma-grown aluminum oxide layers and rapid thermal postannealing, in particular, their endurance in electric fields in excess of 10 MV/cm. The results indicate that such junctions may combine high-field endurance (corresponding to at least 1010 write/erase cycles in floating-gate memories) and high current density (corresponding to 30 ns scale write/erase time) at high voltages, with very low conductance (corresponding to ∼0.1 s scale retention time) at low voltages. We discuss the improvements necessary for the use of such junctions in advanced floating-gate memories.
Zero-group-velocity modes in longitudinally uniform waveguides
Authors: Jiang Chun , Ibanescu Mihai , Joannopoulos J. D. , Soljacic Marin
Published: December 2008

We present a longitudinally uniform slow light waveguide, which consists of transverse periodic dielectric strips with a few defect layers. The parameters of the proposed waveguide can be tuned to have two anomalous dispersion curves with extreme points which have zero-group-velocity frequencies at nonzero wave vector in uniform-index direction. The group velocity and group velocity dispersion of the two photonic bands are analyzed, and the propagation of the slow mode with a given bandwidth is demonstrated theoretically.
High-performance InGaZnO thin-film transistors with high-k amorphous Ba0.5Sr0.5TiO3 gate insulator
Authors: Kim J. B. , Fuentes-Hernandez C. , Kippelen B.
Published: December 2008

We report on high-performance n-channel thin-film transistors (TFTs) fabricated using amorphous indium gallium zinc oxide (a-IGZO) and amorphous Ba0.5Sr0.5TiO3 (a-BST) as the channel and gate dielectric layers, respectively. a-BST∕a-IGZO TFTs achieve low-voltage operation with a high saturation mobility value of 10±1cm2∕Vs, excellent subthreshold slopes of 0.06±0.01V/decade, a low threshold voltage of 0.5±0.1V, and a high on-off current ratio up to 8×107 (W∕L=1000μm∕5μm) at 3V. The high capacitance density of a-BST (145±2nF∕cm2) and the small contact resistance, smaller than the channel resistance, are responsible for the high performance of these TFTs.
The ISC Framework: Modelling Drivers for the Degree of Local Agenda 21 Implantation in Western Europe
Authors: Echebarria Carmen , Barrutia Jose M , Aguado Itziar
Published: December 2008

We analyse the Local Agenda 21 (LA21) implantation process in Western Europe from 1992 to the present day. Basing our work on a literature review and on our own direct observations, we construct a model that explains the development of LA21 processes. We term it the ‘isolated, supported, and connected’ (ISC) framework. Our model attempts to make a contribution to (1) LA21 literature and (2) policy network literature. On the one hand, previous LA21 literature discussed factors that hold back and drive LA21 processes, but a comprehensive conceptual framework has not been constructed. Our model integrates the different variables within a single conceptual ISC framework. On the other hand, conceptual policy network literature holds that fully connected models ought to be superior to less connected, or isolated, models, but empirical evidence is scanty and inconclusive. Our research supports the conclusion that policy networks are superior in terms of disseminating LA21 processes.
Detection of components in nanoparticles by resonant ionisation and laser breakdown time-of-flight mass spectrometry
Authors: Deguchi Yoshihiro , Tanaka Nobuyuki , Tsuzaki Masaharu , Fushimi Akihiro , Kobayashi Shinji , Tanabe Kiyoshi
Published: December 2008

Environmental context. The monitoring of aerosol nanoparticles in the atmosphere is a ‘hot’ topic in environmental management. Such particles in the atmosphere are produced by the combustion of fossil fuels such as in engines. Although they make up only a small percentage of particle total mass, nanosized particles account for more than 90% of the particle number in diesel engine exhaust, and their harmful influences on human health are a serious issue. The system developed in this study has great potential to clarify the origin and behaviour of these aerosol particles more precisely using its online characteristics.
Abstract. Resonance ionisation and laser breakdown time-of-flight mass spectrometry (TOFMS) with particle size selectivity using a differential mobility analyser (DMA) was developed and applied to detect components in nanoparticles. The resonance ionisation and laser breakdown TOFMS method was demonstrated to have a sensitivity of ng m–3, and was shown to be applicable to nanoparticles using a newly developed standard nanoparticle generator. The developed system was successfully applied to 4-stroke diesel engine exhaust gas to show the mass spectrum patterns measured in 30 and 80-nm particles. The measured spectrum intensities were evaluated to calculate the concentration of organic compounds in nanoparticles, and these values were compared with low-pressure impactor measurement results. The two measurements showed concentrations with the same order of magnitude and the validity of the newly developed TOFMS method was examined using the nanoparticles in the actual diesel gas exhaust.
Size distribution and new particle formation in subtropical eastern Australia
Authors: Guo Hai , Ding Aijun , Morawska Lidia , He Congrong , Ayoko Godwin , Li Yok-sheung , Hung Wing-tat
Published: December 2008

Environmental context. Atmospheric submicrometre particles have a significant impact on human health, visibility impairment, acid deposition and global climate. This study aims to understand the size distribution of submicrometre particles and new particle formation in eastern Australia and the results indicate that photochemical reactions of airborne pollutants are the main mechanism of new particle formation. The findings will contribute to a better understanding of the effects of aerosols on climate and the reduction of submicrometre particles in the atmosphere.
Abstract. An intensive measurement campaign of particle concentrations, nitrogen oxides and meteorological parameters was conducted at a rural site in subtropical eastern Australia during September 2006. The aim of this work was to develop an understanding of the formation and growth processes of atmospheric aerosols, and the size distributions under various meteorological conditions. In order to achieve this, the origins of air arriving at the site were explored using back trajectories cluster analysis and the diurnal patterns of particle number concentration and size distribution for the classified air masses were investigated. The study showed that the photochemical formation of nucleation mode particles and their consequent growth was often observed. Furthermore, the nucleation mode usually dominated the size distribution and concentration of the photochemical event in the first 3–4 h with a geometric mean diameter of 26.9 nm and a geometric standard deviation of 1.28. The average particle growth rate was estimated to be 1.6 nm h–1, which is lower than that observed at urban sites, but comparable to the values reported in clean environments. The potential precursors of the photochemical events are also discussed.
Understanding mesotrione photochemistry when applied on leaves
Authors: Lavieille Delphine , ter Halle Alexandra , Richard Claire
Published: December 2008

Environmental context. Pesticide has greatly contributed to the increased yields and regular production in agriculture; however, its use is nowadays more and more being questioned. Current authorisation procedures are more and more comprehensive (evaluating their environmental fate and impact on ecosystems and on human health) but are not yet fully satisfactory. Here we demonstrate the utility of evaluating the stability of pesticide towards sunlight when applied on crops.
Abstract. We developed a methodology to perform laboratory studies that approach field conditions. To demonstrate our methods, we used the herbicide mesotrione. Simulated solar light irradiation experiments were conducted on several cuticular wax films. Adjuvants greatly favoured the rate of mesotrione photolysis. Specifically, the photolytic transformation of formulated mesotrione was 15 times faster than that of pure mesotrione. The morphology and composition of the wax films had a greater effect on the photolysis of formulated mesotrione than of pure mesotrione, which formed aggregates on the waxes. This shows the importance of considering the formulation when studying pesticide photolysis on crops. To corroborate our model, we conducted experiments on detached leaves. The rates of photolysis on leaves and on wax films were of the same order of magnitude. Finally, the mesotrione rate of photolysis on leaves is much higher compared with data from the literature in water and on soils. Photolysis is likely to be a fast dissipation process on crops. The photodegradation of pesticide on crops should be systematically evaluated.
Severe growth retardation and early lethality in mice lacking the nuclear localization sequence and C-terminus of PTH-related protein
Authors: Miao Dengshun , Su Hanyi , He Bin , Gao Jianjun , Xia Qingwen , Zhu Min , Gu Zhen , Goltzman David , Karaplis Andrew C.
Published: December 2008

Parathyroid hormone (PTH) plays a central role in the regulation of serum calcium and phosphorus homeostasis, while parathyroid hormone-related protein (PTHrP) has important developmental roles. Both peptides signal through the same G protein-coupled receptor, the PTH/PTHrP or PTH type 1 receptor (PTH1R). PTHrP, normally a secreted protein, also contains a nuclear localization signal (NLS) that in vitro imparts functionality to the protein at the level of the nucleus. We investigated this functionality in vivo by introducing a premature termination codon in
Pthrp
in ES cells and generating mice that express PTHrP (1–84), a truncated form of the protein that is missing the NLS and the C-terminal region of the protein but can still signal through its cell surface receptor. Mice homozygous for the knock-in mutation (
Pthrp
KI) displayed retarded growth, early senescence, and malnutrition leading postnatally to their rapid demise. Decreased cellular proliferative capacity and increased apoptosis in multiple tissues including bone and bone marrow cells were associated with altered expression and subcellular distribution of the senescence-associated tumor suppressor proteins p16
INK4a
and p21 and the oncogenes Cyclin D, pRb, and Bmi-1. These findings provide in vivo experimental proof that substantiates the biologic relevance of the NLS and C-terminal portion of PTHrP, a polypeptide ligand that signals mainly via a cell surface G protein-coupled receptor.
Visualizing stimulus convergence in amygdala neurons during associative learning
Authors: Barot Sabiha K. , Kyono Yasuhiro , Clark Emily W. , Bernstein Ilene L.
Published: December 2008

A central feature of models of associative memory formation is the reliance on information convergence from pathways responsive to the conditioned stimulus (CS) and unconditioned stimulus (US). In particular, cells receiving coincident input are held to be critical for subsequent plasticity. Yet identification of neurons in the mammalian brain that respond to such coincident inputs during a learning event remains elusive. Here we use
Arc c
ellular compartmental
a
nalysis of
t
emporal gene transcription by
f
luorescence
i
n
s
itu
h
ybridization (catFISH) to locate populations of neurons in the mammalian brain that respond to both the CS and US during training in a one-trial learning task, conditioned taste aversion (CTA). Individual neurons in the basolateral nucleus of the amygdala (BLA) responded to both the CS taste and US drug during conditioning. Coincident activation was not evident, however, when stimulus exposure was altered so as to be ineffective in promoting learning (backward conditioning, latent inhibition). Together, these data provide clear visualization of neurons in the mammalian brain receiving convergent information about the CS and US during acquisition of a learned association.
The
spt
-function of Andrews
Authors: Folsom Amanda , Ono Ken
Published: December 2008

Recently, Andrews introduced the function
s
(
n
) =
spt
(
n
) which counts the number of smallest parts among the integer partitions of
n
. We show that its generating function satisfies an identity analogous to Ramanujan's mock theta identities. As a consequence, we are able to completely determine the parity of
s
(
n
). Using another type of identity, one based on Hecke operators, we obtain a complete multiplicative theory for
s
(
n
) modulo 3. These congruences confirm unpublished conjectures of Garvan and Sellers. Our methods generalize to all integral moduli.
Transfer of response codes from choice-response to go/no-go tasks
Authors: Ansorge Ulrich , Wühr Peter
Published: December 2008

The present study investigated the conditions for observing the Simon effect in go/no-go tasks. The Simon effect denotes faster and more accurate responses when irrelevant stimulus location and response location correspond than when they do not correspond. In four experiments, participants performed both in a choice-response task (CRT) and in a go/no-go task, and we varied the order and the similarity of the tasks. In the CRT, participants pressed a left key to one stimulus colour and a right key to another stimulus colour; in the go/no-go task, participants pressed one (e.g., left) key to one stimulus colour and refrained from responding to the other stimulus colour. As expected, Simon effects were consistently observed in the CRT. In contrast, Simon effects in the go/no-go task were only observed when it followed the CRT and when the mapping of stimulus colours to response locations was preserved between tasks (i.e., in Experiment 4). Results suggest that transfer of a particular S–R rule including response location from the CRT to the go/no-go task was responsible for the Simon effect in the latter task. In general, results are consistent with a response-discrimination account of the Simon effect.
The different representational frameworks underpinning abstract and concrete knowledge: Evidence from odd-one-out judgements
Authors: Crutch Sebastian J. , Connell Sarah , Warrington Elizabeth K.
Published: December 2008

Recent evidence from neuropsychological investigations of individuals with global aphasia and deep or deep-phonological dyslexia suggests that abstract and concrete concepts are underpinned by qualitatively different representational frameworks. Abstract words are represented primarily by their association to other words, whilst concrete words are represented primarily by their taxonomic similarity to one another. In the current study, we present the first evidence for this association/similarity distinction to be gathered from healthy research participants. Using a semantic odd-one-out task, it is shown that normal participants identify associative connections more quickly than similarity-based connections when processing abstract words, but that the pattern is reversed for concrete words. It is also demonstrated that the typical concrete-word advantage observed in many cognitive tasks is abolished and even reversed when participants have to comprehend the semantic associations between words. The data provide converging evidence for the different representational frameworks hypothesis and suggest that claims based on information from previous neuropsychological investigations can be generalized to normal cognition.
In Vivo Interference with AtTCP20 Function Induces Severe Plant Growth Alterations and Deregulates the Expression of Many Genes Important for Development
Authors: Hervé Christine , Dabos Patrick , Bardet Claude , Jauneau Alain , Auriac Marie Christine , Ramboer Agnès , Lacout Fabrice , Tremousaygue Dominique
Published: December 2008

AtTCP20 is a transcription factor belonging to the Arabidopsis (Arabidopsis thaliana) TCP-P subfamily, characterized by its capacity to bind to site II motifs (TGGGCY). Our aim was to understand the role of AtTCP20 in plant development. The expression pattern of a translational fusion of PromTCP20:CDS20∷GUS∷GFP suggested a function for AtTCP20 in several plant organs and stages of development. The role of AtTCP20 was challenged in planta by inducing expression of AtTCP20 proteins fused with either a transcriptional activator domain (VP16) or a repressor domain (EAR). Expression of both modified proteins led to severe developmental phenotypes. In-depth analysis suggested that AtTCP20 may participate in the regulation of cell expansion, cell division, and cell differentiation. Gene expression profiling in roots and hypocotyls revealed that 252 genes were down-regulated in both organs after induction of the AtTCP20∷EAR repressor gene. Site II motifs (TGGGCY) were underrepresented in their promoters. Conversely, GG(A/T)CCC sequences related to binding sites identified for TCP proteins in rice (Oryza sativa) were overrepresented, and a TCP20 fusion protein was shown to bind to these sequences in vitro. Gene ontology indicated that many targeted genes were involved in cell wall biogenesis and modification during expansion and also encoded numerous transcription factors controlling plant development. Our results are consistent with the previous proposal that AtTCP20 is involved in cell division and growth coordination. Moreover, they further suggest that AtTCP20 also contributes to cell expansion control and indicate a different involvement of this protein in plant morphogenesis depending on the organ and the developmental stage.
Single-crystal diamond: a potential gem in neutron instrumentation
Authors: Freund A. K.
Published: December 2008

Calculations have been performed showing that single-crystal diamond has the highest performance of all materials proposed in the past and presently used as neutron monochromators. If large mosaic crystals were available, the presently available flux on most neutron scattering instruments could be increased by factors of between 1.5 and 4. Thanks to recent progress in chemical vapour deposition technology the growth of diamond single-crystal layers with a suitable mosaic spread has become feasible. Provided an adequate research and development effort is made, it is expected that the high potential of this extraordinary material can be exploited in the not too distant future.
Simulation of powder diffraction patterns of mixed-layer compounds in the restacked binary nanosheet system Ti0.91O2–MnO2
Authors: Onoda Mitsuko , Liu Zhaoping , Takada Kazunori , Sasaki Takayoshi
Published: December 2008

Two-component colloidal nanosheets in a Ti0.91O2–MnO2system with different compositions were restacked by flocculation with K ions. X-ray powder diffraction patterns of the products showed remarkably broad reflections. The structures suggested the presence of mixed layers of Ti0.91O2and MnO2connected by K ions. Powder pattern simulation was conducted using the matrix method, in an approach similar to that used for analyzing layered composite crystals with one-directional disorder. The following were considered: (1) stacking disorder in layered K–Ti-oxide, (2) stacking disorder in layered K–Mn-oxide, and (3) sequence probabilities of K–Ti-oxide and K–Mn-oxide sheets. Taking into consideration chemical composition, three types of probability tables were unified into one large probability table. For 00ζ calculation,zcoordinates of all atoms were used. Forh1k1ζ calculation except 00ζ, atom coordinates of the K–Ti-oxide sheet were used on an orthorhombic cell (a1= 2.96,b1= 3.77,c1= 9.32 Å), and forh2k2ζ calculation except 00ζ, those of the K–Mn-oxide sheet were used on a trigonal cell (a2=b2= 2.84,c2= 7.10 Å). The agreement in pattern fitting between the experimental and calculated intensities was satisfactory in all composition ranges. From the results, the phase relationship of the misfit mixed-layer material in the binary restacked nanosheet system of Ti0.91O2–MnO2flocculated with K ions was clarified.
UK Alcohol Treatment Trial: client–treatment matching effects
Authors:   UKATT Research Team
Published: December 2008

Aim  To test a priori hypotheses concerning client–treatment matching in the treatment of alcohol problems and to evaluate the more general hypothesis that client–treatment matching adds to the overall effectiveness of treatment.

Design  Pragmatic, multi‐centre, randomized controlled trial (the UK Alcohol Treatment Trial: UKATT) with open follow‐up at 3 months after entry and blind follow‐up at 12 months.

Setting  Five treatment centres, comprising seven treatment sites, including National Health Service (NHS), social services and joint NHS/non‐statutory facilities.

Treatments  Motivational enhancement therapy and social behaviour and network therapy.

Measurements  Matching hypotheses were tested by examining interactions between client attributes and treatment types at both 3 and 12 months follow‐up using the outcome variables of percentage days abstinent, drinks per drinking day and scores on the Alcohol Problems Questionnaire and Leeds Dependence Questionnaire.

Findings  None of five matching hypotheses was confirmed at either follow‐up point on any outcome variable.

Conclusion  The findings strongly support the conclusion reached in Project MATCH in the United States that client–treatment matching, at least of the kind examined, is unlikely to result in substantial improvements to the effectiveness of treatment for alcohol problems. Possible reasons for this failure to support the general matching hypothesis are discussed, as are the implications of UKATT findings for the provision of treatment for alcohol problems in the United Kingdom.
The effect of retail cigarette pack displays on impulse purchase
Authors: Wakefield Melanie , Germain Daniella , Henriksen Lisa
Published: December 2008

Aims  To assess the extent to which point‐of purchase (POP) cigarette displays stimulate impulse purchases.

Design  Telephone‐administered population survey.

Setting  Victoria, Australia.

Participants  A total of 2996 adults, among whom 526 smoked factory‐made cigarettes and 67 were recent quitters (quit in the past 12 months).

Measurements  Reported cigarette purchase behaviour; perceived effect on smoking of removing cigarettes from view in retail outlets; reported urges to buy cigarettes as a result of seeing the cigarette display.

Findings  When shopping for items other than cigarettes, 25.2% of smokers purchased cigarettes at least sometimes on impulse as a result of seeing the cigarette display. Thirty‐eight per cent of smokers who had tried to quit in the past 12 months and 33.9% of recent quitters experienced an urge to buy cigarettes as a result of seeing the retail cigarette display. One in five smokers trying to quit and one in eight recent quitters avoided stores where they usually bought cigarettes in case they might be tempted to purchase them. Many smokers (31.4%) thought the removal of cigarette displays from stores would make it easier for them to quit.

Conclusions  POP cigarette displays act as cues to smoke, even among those not explicitly intending to buy cigarettes, and those trying to avoid smoking. Effective POP marketing restrictions should encompass cigarette displays.
Acute risk of drug‐related death among newly released prisoners in England and Wales
Authors: Farrell Michael , Marsden John
Published: December 2008

Aims  To investigate drug‐related deaths among newly released prisoners in England and Wales.

Design  Database linkage study.

Participants  National sample of 48 771 male and female sentenced prisoners released during 1998–2000 with all recorded deaths included to November 2003.

Findings  There were 442 recorded deaths, of which 261 (59%) were drug‐related. In the year following index release, the drug‐related mortality rate was 5.2 per 1000 among men and 5.9 per 1000 among women. All‐cause mortality in the first and second weeks following release for men was 37 and 26 deaths per 1000 per annum, respectively (95% of which were drug‐related). There were 47 and 38 deaths per 1000 per annum, respectively, among women, all of which were drug‐related. In the first year after prison release, there were 342 male deaths (45.8 were expected in the general population) and there were 100 female deaths (8.3 expected in the general population). Drug‐related deaths were attributed mainly to substance use disorders and drug overdose. Coronial records cited the involvement of opioids in 95% of deaths, benzodiazepines in 20%, cocaine in 14% and tricyclic antidepressants in 10%. Drug‐related deaths among men were more likely to involve heroin and deaths among women were more likely to involve benzodiazepines, cocaine and tricyclic antidepressants.

Conclusions  Newly released male and female prisoners are at acute risk of drug‐related death. Appropriate prevention measures include overdose awareness education, opioid maintenance pharmacotherapy, planned referral to community‐based treatment services and a community overdose‐response using opioid antagonists.
Root canal morphology of mandibular first premolars in an Indian population: a laboratory study
Authors: Velmurugan N. , Sandhya R.
Published: December 2008

Aim  To determine the root canal morphology of mandibular first premolar teeth in an Indian population using a decalcification and clearing technique.

Methodology  One hundred extracted adult mandibular first premolar teeth were studied following decalcification and clearing. The shape of the canal orifice, root canal pattern and length of the teeth were determined.

Results  The mandibular first premolars were identified to have a round orifice (38%), oval orifice (44%), flattened orifice (17%) and C‐shaped orifice (1%). The canal patterns were classified as Type I (72%), Type II (6%), Type III (3%), Type IV (10%) and Type V (8%) according to Vertucci’s classification. C‐shaped canals were identified in one tooth (1%). The average length of the teeth was 21.6 mm. Fourteen per cent of the teeth had mesial invaginations of the root.

Conclusions  Type I canal patterns were the most frequently occurring in mandibular first premolars amongst the Indian population. 85.7% of the teeth with mesial invagination of the root had either two canals or division of canals.