bluuebunny/crossref_metadata_2025 huggingface dataset:
Propranolol modulates the collateral vascular responsiveness to vasopressin via a Gα-mediated pathway in portal hypertensive rats
Authors: Lee Jing-Yi , Huo Teh-Ia , Huang Hui-Chun , Lee Fa-Yauh , Lin Han-Chieh , Chuang Chiao-Lin , Chang Ching-Chih , Wang Sun-Sang , Lee Shou-Dong
Published: July 2011

Gastro-oesophageal variceal haemorrhage is one of the most dreadful complications of portal hypertension and can be controlled with vasoconstrictors. Nevertheless, sympathetic tone abnormality and vascular hyporesponsiveness in portal hypertension may impede the haemostatic effects of vasoconstrictors. Propranolol, a β-blocker binding the G-protein-coupled adrenoceptor, is a portal hypotensive agent. However, whether propranolol influences the collateral vasoresponse is unknown. Portal hypertension was induced by PVL (portal vein ligation) in Sprague–Dawley rats. In an acute study with an in situ perfusion model, the collateral responsiveness to AVP (arginine vasopressin) was evaluated with vehicle, propranolol (10 μmol/l), propranolol plus suramin (100 μmol/l, a Gα inhibitor) or suramin pre-incubation. Gα mRNA expression in the splenorenal shunt, the most prominent intra-abdominal collateral vessel, was measured. In the chronic study, rats received DW (distilled water) or propranolol (10 mg·kg−1 of body weight·day−1) for 9 days. Then the concentration–response relationship of AVP and Gα mRNA expression were assessed. Propranolol pre-incubation elevated the perfusion pressure changes of collaterals in response to AVP, which was inhibited by suramin. The splenorenal shunt Gαq and Gα11 mRNA expression were enhanced by propranolol. The group treated with propranolol plus suramin had a down-regulation of Gα11 as compared with the propranolol group. Chronic propranolol treatment reduced mean arterial pressure, PP (portal pressure) and the perfusion pressure changes of collaterals to AVP. Gαs expression was up-regulated. In conclusion, propranolol pre-incubation enhanced the portal-systemic collateral AVP responsiveness in portal hypertensive rats, which was related to Gαq and Gα11 up-regulation. In contrast, the attenuated AVP responsiveness by chronic propranolol treatment was related to Gαs up-regulation. The Gα signalling pathway may be a therapeutic target to control variceal bleeding and PP in portal hypertension.
Toll-like receptors in health and disease in the brain: mechanisms and therapeutic potential
Authors: Hanke Mark L. , Kielian Tammy
Published: July 2011

The discovery of mammalian TLRs (Toll-like receptors), first identified in 1997 based on their homology with Drosophila Toll, greatly altered our understanding of how the innate immune system recognizes and responds to diverse microbial pathogens. TLRs are evolutionarily conserved type I transmembrane proteins expressed in both immune and non-immune cells, and are typified by N-terminal leucine-rich repeats and a highly conserved C-terminal domain termed the TIR [Toll/interleukin (IL)-1 receptor] domain. Upon stimulation with their cognate ligands, TLR signalling elicits the production of cytokines, enzymes and other inflammatory mediators that can have an impact on several aspects of CNS (central nervous system) homoeostasis and pathology. For example, TLR signalling plays a crucial role in initiating host defence responses during CNS microbial infection. Furthermore, TLRs are targets for many adjuvants which help shape pathogen-specific adaptive immune responses in addition to triggering innate immunity. Our knowledge of TLR expression and function in the CNS has greatly expanded over the last decade, with new data revealing that TLRs also have an impact on non-infectious CNS diseases/injury. In particular, TLRs recognize a number of endogenous molecules liberated from damaged tissues and, as such, influence inflammatory responses during tissue injury and autoimmunity. In addition, recent studies have implicated TLR involvement during neurogenesis, and learning and memory in the absence of any underlying infectious aetiology. Owing to their presence and immune-regulatory role within the brain, TLRs represent an attractive therapeutic target for numerous CNS disorders and infectious diseases. However, it is clear that TLRs can exert either beneficial or detrimental effects in the CNS, which probably depend on the context of tissue homoeostasis or pathology. Therefore any potential therapeutic manipulation of TLRs will require an understanding of the signals governing specific CNS disorders to achieve tailored therapy.
What Speech-Language Pathologists Need to Know About Auditory Processing Disorder
Authors: Kamhi Alan G.
Published: July 2011

Purpose

To consider whether auditory processing disorder (APD) is truly a distinct clinical entity or whether auditory problems are more appropriately viewed as a processing deficit that may occur with various developmental disorders.

Method

Theoretical and clinical factors associated with APD are critically evaluated.

Results

There are compelling theoretical and clinical reasons to question whether APD is in fact a distinct clinical entity. Not only is there little evidence that auditory perceptual impairments are a significant risk factor for language and academic performance (e.g., Hazan, Messaoud-Galusi, Rosan, Nouwens, & Shakespeare, 2009; Watson & Kidd, 2009), there is also no evidence that auditory interventions provide any unique benefit to auditory, language, or academic outcomes (Fey et al., 2011).

Conclusion

Because there is no evidence that auditory interventions provide any unique therapeutic benefit (Fey et al., 2011), clinicians should treat children who have been diagnosed with APD the same way they treat children who have been diagnosed with language and learning disabilities. The theoretical and clinical problems associated with APD should encourage clinicians to consider viewing auditory deficits as a processing deficit that may occur with common developmental language and reading disabilities rather than as a distinct clinical entity.
Temperature dependences of rate coefficients for electron catalyzed mutual neutralization
Authors: Shuman Nicholas S. , Miller Thomas M. , Friedman Jeffrey F. , Viggiano Albert A. , Maeda Satoshi , Morokuma Keiji
Published: July 2011

The flowing afterglow technique of variable electron and neutral density attachment mass spectrometry (VENDAMS) has recently yielded evidence for a novel plasma charge loss process, electron catalyzed mutual neutralization (ECMN), i.e., A+ + B− + e− → A + B + e−. Here, rate constants for ECMN of two polyatomic species (POCl3− and POCl2−) and one diatomic species (Br2−) each with two monatomic cations (Ar+and Kr+) are measured using VENDAMS over the temperature range 300 K–500 K. All rate constants show a steep negative temperature dependence, consistent with that expected for a three body process involving two ions and an electron. No variation in rate constants as a function of the cation type is observed outside of uncertainty; however, rate constants of the polyatomic anions (∼1 × 10−18 cm6 s−1 at 300 K) are measurably higher than that for Br2− [(5.5 ± 2) × 10−19 cm6 s−1 at 300 K].
Band gaps of two-dimensional antiferromagnetic photonic crystal
Authors: Song Yu-Ling , Ta Jin-Xing , Wang Xuan-Zhang
Published: July 2011

In an external magnetic field, the band structure of a two-dimensional photonic crystal (PC) composed of parallel antiferromagnetic cylinders in a background dielectric is investigated with a Green’s function method. The cylinders with two resonant frequencies form a square lattice and are characterized by a magnetic permeability tensor. In our numerical calculation, we find that this method allows fast convergence and is available in both the resonant and non-resonant frequency ranges. In the non-resonant range, the PC is similar in band structure to an ordinary dielectric PC. Two electromagnetic band gaps, however, appear in the resonant frequency region, and their frequency positions and widths are governed by the external field. The dependence of the electromagnetic gaps on the cylinder radius also is discussed.
Detection of charge density wave ground state in granular thin films of blue bronze K0.3MoO3 by femtosecond spectroscopy
Authors: Dominko D. , Starešinić D. , Salamon K. , Biljaković K. , Tomeljak A. , Schäfer H. , Huber Tim , Demsar J. , Socol G. , Ristoscu C. , Mihailescu I. N. , Siketić Z. , Bogdanović Radović I. , Pletikapić G. , Svetličić V. , Ðekić M. , Šamić H. , Marcus J.
Published: July 2011

During the last years, femtosecond time-resolved spectroscopy (fsTRS) has become an important new tool to investigate low energy excitations in strongly correlated systems. By studying energy relaxation pathways linking various degrees of freedom (e.g., electrons, spin, or lattice), the interaction strengths between different subsystems can be deduced. Here we report on yet another application of fsTRS, where the technique is used to unambiguously determine the nature of the ground state in granular thin films of a prototype charge density wave system blue bronze, K0.3MoO3. These, potassium blue bronze, films, obtained for the first time ever, have been prepared by pulsed laser deposition and investigated by various standard characterization methods. While the results of all used methods indicate that the thin films consist of nanometer grains of K0.3MoO3, it is only the non-destructive fsTRS that demonstrates the charge density wave nature of the ground state. Furthermore, the comparison of the fsTRS data obtained in thin films and in single crystals shows the reduction of the charge density wave transition temperature and of the photoinduced signal strength in granular thin films in respect to single crystals, which is attributed to the granularity and crystal growth morphology.
Photoexcited conversion of gauche-1,3-butadiene to bicyclobutane via a conical intersection: Energies and reduced density matrices from the anti-Hermitian contracted Schrödinger equation
Authors: Snyder James W. , Mazziotti David A.
Published: July 2011

The photoexcited reaction pathway from gauche-1,3-butadiene to bicyclobutane via a conical intersection is analyzed through the direct calculation of two-electron reduced density matrices (2-RDMs) from solutions to the anti-Hermitian contracted Schrödinger equation (ACSE). The study utilizes the recent generalization of the ACSE method for the treatment of excited states [G. Gidofalvi and D. A. Mazziotti, Phys. Rev. A 80, 022507 (2009)10.1103/PhysRevA.80.022507]. We computed absolute energies of the critical points as well as various intermediate points along the ground-and excited-state potential energy surface of gauche-1,3-butadiene and bicyclobutane. To treat multi-reference correlation, we seeded the ACSE with an initial 2-RDM from a multi-configuration self-consistent field (MCSCF) calculation. The ACSE, MCSCF, and second-order multi-reference many-body perturbation theory (MRPT2) all demonstrate that there exists a family of pathways from gauche-1,3-butadiene to bicyclobutane via a conical intersection that are monotonically decreasing in energy, confirming a conjecture by Sicilia et al. [J. Phys. Chem. A 111, 2182 (2007)10.1021/jp067614w]. The ACSE recovers more single-reference correlation energy than MRPT2 and more multi-reference correlation energy than comparable single-reference wave function methods. The 2-RDMs from the ACSE nearly satisfy all necessary N-representability conditions.
The critical behavior of the dielectric constant in the polar + polar binary liquid mixture nitromethane + 3-pentanol: An unusual sign of its critical amplitude in the one-phase region
Authors: Leys Jan , Losada-Pérez Patricia , Troncoso Jacobo , Glorieux Christ , Thoen Jan
Published: July 2011

Dielectric constant measurements have been carried out in the one- and two-phase regions near the critical point of the polar + polar binary liquid mixture nitromethane + 3-pentanol. In the two-phase region, evidence for the |t|2β singularity in the coexistence-curve diameter has been detected, thus confirming the novel predictions of complete scaling theory for liquid-liquid criticality. In the one-phase region, an “unusual” negative sign for the amplitude of the |t|1 − α singularity has been encountered for the first time in an upper critical solution temperature type of binary liquid mixture at atmospheric pressure. Mass density measurements have also been carried out to provide additional information related to such experimental finding, which entails an increase of the critical temperature Tc under an electric field.
Ab initio full-potential study of mechanical properties and magnetic phase stability of rare earth diboride compounds
Authors: Zazoua F. , Kacimi S. , Djermouni M. , Zaoui A.
Published: July 2011

We study the structures and magnetic phase stability of rare earth diboride compounds, RB2, using density functional simulations within the local density approximation. At zero pressure the hexagonal (P6/mmm) structure is energetically stable and at high pressure these materials prefer to keep the same structure. The five different elastic constants, bulk modulus, shear modulus, and hardness of all the hexagonal compounds have been calculated. The pressure dependence of the volumes is determined. The calculated large bulk modulus and high hardness reveal that they are incompressible and hard materials. The structural parameters and magnetic phase stability for RB2 (R = Tb, Dy, Ho, Er, Tm, and Yb) compare quite well with experimental results. For the others rare earth materials, our results are predictions.
Forward bias voltage controlled infrared photodetection and electroluminescence from a p-i-n quantum dot structure
Authors: Cui Kai , Ma Wenquan , Zhang Yanhua , Huang Jianliang , Wei Yang , Cao Yulian , Jin Zhao , Bian Lifeng
Published: July 2011

We report a specially designed p-i-n quantum dot (QD) device in which both the intersubband and the interband transitions of the QD are controlled by the applied forward bias voltage. The design is achieved by using asymmetric AlGaAs barriers on both sides of only one QD layer and by placing two-dimensional electron gas structure on one side of the QD layer. Experimentally, at 77 K, the device can detect normal incidence infrared light of about 5.6 µm when the forward bias voltage is in between about 3 and 7 V, while it emits electroluminescence of about 1 μm when the applied forward bias voltage is larger than 11 V.
Molecular simulation of bundle-like crystal nucleation from n-eicosane melts
Authors: Yi Peng , Rutledge Gregory C.
Published: July 2011

Homogeneous nucleation of n-eicosane crystals from the supercooled melt was studied by molecular simulation using a realistic, united-atom model for n-alkanes. Using molecular dynamics simulation, we observed nucleation events directly at constant pressure and temperature, corresponding to about 19% supercooling. Under these conditions, the induction time is found to be 80.6 ± 8.8 ns for a system of volume (1.882 ± 0.006) × 10−19 cm3, corresponding to a nucleation rate of (6.59 ± 0.72) × 1025 cm−3 s−1. The nucleation free energy was calculated separately for three temperatures, ranging from 10% to 19% supercooling, by a Monte Carlo method with umbrella sampling. Values for the nucleation free energy range from 7.3 to 13.2 (in units of kBT). Detailed examination of the simulations reveals the critical nucleus to be a bundle of stretched segments about eight methylene groups long, organized into a cylindrical shape. The remaining methylene groups of the chains that participate in the nucleus form a disordered interfacial layer. By fitting the free energy curve to the cylindrical nucleus model, the solid-liquid interfacial free energies are calculated to be about 10 mJ/m2 for the side surface and 4 mJ/m2 for the end surface, both of which are relatively insensitive to temperature.
Early stage domain coarsening of the isotropic-nematic phase transition
Authors: Bradač Z. , Kralj Samo , Žumer S.
Published: July 2011

We study numerically the early stage domain coarsening dynamics of the temperature driven isotropic-nematic (I-N) liquid crystal phase transition. System of rod like objects which interact via the modified Lebwohl-Lasher pairwise interaction is considered in 3D. The coarsening dynamics is followed using Brownian molecular dynamics. The box-restricted lattice point fluctuations are allowed in order to get rid of lattice geometry enforced phenomena. We analyze order parameter growth and domain coarsening in the early regime of the I-N phase transition as a function of the quench rate. We show that soon after the transition bimodal distribution of domains appears, where the shorter branch gradually vanishes. The behavior of the system is in accordance with predictions of the Kibble-Zurek mechanism which was originally introduced to model conditions in the early universe.
Response to “Comment on ‘Accurate frozen-density embedding potentials as a first step towards a subsystem description of covalent bonds’” [J. Chem. Phys. 135, 027101 (2011)]
Authors: Fux Samuel , Jacob Christoph R. , Neugebauer Johannes , Visscher Lucas , Reiher Markus
Published: July 2011

The five points of criticism in Wesolowski's comment can be separated into three categories. Two issues are related to the question whether the nonadditive kinetic-energy functional or its functional derivative should be investigated, which is a matter of personal choice of research subject. Another issue is an unfounded accusation addressing the numerical soundness of our data. Finally, the remaining two points do not concern our paper, but deal with connections between previous work by two of us [J. Chem. Phys. 126, 234116 (2007)] and by Wesolowski and co-workers [J. Chem. Phys.129, 074107 (2008)], which we clarify in this response. Issues from all three categories have in common that they do not question the usefulness of our paper, or criticize any of our results or conclusions.
On the interfacial thermodynamics of nanoscale droplets and bubbles
Authors: Corti David S. , Kerr Karl J. , Torabi Korosh
Published: July 2011

We present a new self-consistent thermodynamic formalism for the interfacial properties of nanoscale embryos whose interiors do not exhibit bulklike behavior and are in complete equilibrium with the surrounding mother phase. In contrast to the standard Gibbsian analysis, whereby a bulk reference pressure based on the same temperature and chemical potentials of the mother phase is introduced, our approach naturally incorporates the normal pressure at the center of the embryo as an appropriate reference pressure. While the interfacial properties of small embryos that follow from the use of these two reference pressures are different, both methods yield by construction the same reversible work of embryo formation as well as consistency between their respective thermodynamic and mechanical routes to the surface tension. Hence, there is no a priori reason to select one method over another. Nevertheless, we argue, and demonstrate via a density-functional theory (with the local density approximation) analysis of embryo formation in the pure component Lennard-Jones fluid, that our new method generates more physically appealing trends. For example, within the new approach the surface tension at all locations of the dividing surface vanishes at the spinodal where the density profile spanning the embryo and mother phase becomes completely uniform (only the surface tension at the Gibbs surface of tension vanishes in the Gibbsian method at this same limit). Also, for bubbles, the location of the surface of tension now diverges at the spinodal, similar to the divergent behavior exhibited by the equimolar dividing surface (in the Gibbsian method, the location of the surface of tension vanishes instead). For droplets, the new method allows for the appearance of negative surface tensions (the Gibbsian method always yields positive tensions) when the normal pressures within the interior of the embryo become less than the bulk pressure of the surrounding vapor phase. Such a prediction, which is allowed by thermodynamics, is consistent with the interpretation that the mother phase's attempted compression of the droplet is counterbalanced by the negative surface tension, or free energy cost to decrease the interfacial area. Furthermore, for these same droplets, the surface of tension can no longer be meaningfully defined (the surface of tension always remains well defined in the Gibbsian method). Within the new method, the dividing surface at which the surface tension equals zero emerges as a new lengthscale, which has various thermodynamic analogs to and similar behavior as the surface of tension.
Enhancement of second harmonic generation in a doubly resonant metamaterial
Authors: Kanazawa Tetsuo , Tamayama Yasuhiro , Nakanishi Toshihiro , Kitano Masao
Published: July 2011

We investigate second harmonic (SH) generation in a doubly resonant metamaterial. We show that SH generation can be enhanced when the resonant condition is satisfied for the SH frequency as well as for the fundamental frequency. A unit cell of the doubly resonant metamaterial consists of two coupled resonators, one of which resonates at the fundamental frequency, whereas the other resonates around the SH frequency. We observe that the SH generation in the doubly resonant metamaterial is 4.6 times as large as that in a singly resonant metamaterial.
Spin-glass magnetism of surface rich Au cluster film
Authors: Costelle L. , Pirojenko A. , Tuboltsev V. , Savin A. , Mizohata K. , Räisänen J.
Published: July 2011

The magnetic response of two-dimensional uncapped Au islands tens of nanometers in size was measured using a superconducting quantum interference device magnetometer. The magnetization vs. field was found to exhibit a clear ferromagnetic-like hysteresis loop and a large positive remanent magnetization was acquired after momentary application of a strong magnetic field. The Au magnetic response is assumed to be due to the surface effects in the nanosized islands and the large fraction of canted surface magnetic moments which interaction and mutual orientation differ from the bulk diamagnetic order.
Communication: First observation of ground state I(2P3/2) atoms from the CH3I photodissociation in the B-band
Authors: González M. G. , Rodríguez J. D. , Rubio-Lago L. , Bañares L.
Published: July 2011

The photodissociation of CH3I in the second absorption band (the \documentclass[12pt]{minimal}\begin{document}$\textit {B}$\end{document}B-band) has been studied at the wavelength 199.11 nm, coincident with the \documentclass[12pt]{minimal}\begin{document}$3^1_0$\end{document}301 \documentclass[12pt]{minimal}\begin{document}$^3R_1(E) \leftarrow \tilde{X}(^1A_1)$\end{document}R13(E)←X̃(1A1) CH3I vibronic transition, using a combination of slice imaging and resonance enhanced multiphoton ionization detection of the CH3 fragment. The kinetic energy and angular distributions of the recoiling CH3 fragment confirm a major predissociation dynamics channel as a result of the interaction between the bound 3R1 Rydberg state and the repulsive 3A1(E) state − ascribed to the \documentclass[12pt]{minimal}\begin{document}$\textit {A}$\end{document}A-band − yielding CH3 fragments in correlation with spin-orbit excited I*(2P1/2) atoms. In addition, first evidence of a non-negligible population of ground state I(2P3/2) atoms in the CH3 fragment slice images, suggests a secondary predissociation mechanism via interaction between the 3R1 Rydberg state and the repulsive \documentclass[12pt]{minimal}\begin{document}$\textit {A}$\end{document}A-band 1Q1 state.
Ecological implications of organic carbon dynamics in the traps of aquatic carnivorous Utricularia plants
Authors: Sirová Dagmara , Borovec Jakub , Picek Tomáš , Adamec Lubomír , Nedbalová Linda , Vrba Jaroslav
Published: July 2011

Rootless aquatic carnivorous Utricularia exude up to 25% of their photosynthates into the trap lumen, which also harbours a complex microbial community thought to play a role in enhancing Utricularia nutrient acquisition. We investigated the composition of organic carbon in the trap fluid, its availability for microbial uptake, the influence of plant nutrient status and trap age on its biodegradability, and the composition of prokaryotic assemblages within the traps of three aquatic Utricularia species. Using ion chromatography and basal respiration rate measurements we confirmed that up to 30% of total dissolved organic carbon in Utricularia trap fluid in oligotrophic conditions was easily biodegradable compounds commonly found in plant root exudates (mainly glucose, fructose and lactate). The proportion of these compounds and their microbial utilisation decreased with increasing mineral nutrient supply and trap age. Fluorescence in situ hybridisation analyses showed that microbial trap assemblages are dominated by alpha and beta Proteobacteria, and that the assemblage composition is affected by changes in the ambient mineral nutrient supply. We suggest that organic carbon dynamics within the traps, involving both the plant and associated microbial assemblages, underlies the acquisition of key nutrients by Utricularia and may help explain the evolutionary success of the genus.
Two distinct strategies of cotton and soybean differing in leaf movement to perform photosynthesis under drought in the field
Authors: Zhang Ya-Li , Hu Yuan-Yuan , Luo Hong-Hai , Chow Wah Soon , Zhang Wang-Feng
Published: July 2011

This paper reports an experimental test of the hypothesis that cotton and soybean differing in leaf movement have distinct strategies to perform photosynthesis under drought. Cotton and soybean were exposed to two water regimes: drought stressed and well watered. Drought-stressed cotton and soybean had lower maximum CO2 assimilation rates than well-watered (control) plants. Drought reduced the light saturation point and photorespiration of both species – especially in soybean. Area-based leaf nitrogen decreased in drought-stressed soybean but increased in drought-stressed cotton. Drought decreased PSII quantum yield (ΦPSII) in soybean leaves, but increased ΦPSII in cotton leaves. Drought induced an increase in light absorbed by the PSII antennae that is dissipated thermally via ΔpH- and xanthophylls-regulated processes in soybean leaves, but a decrease in cotton leaves. Soybean leaves appeared to have greater cyclic electron flow (CEF) around PSI than cotton leaves and drought further increased CEF in soybean leaves. In contrast, CEF slightly decreased in cotton under drought. These results suggest that the difference in leaf movement between cotton and soybean leaves gives rise to different strategies to perform photosynthesis and to contrasting photoprotective mechanisms for utilisation or dissipation of excess light energy. We suggest that soybean preferentially uses light-regulated non-photochemical energy dissipation, which may have been enhanced by the higher CEF in drought-stressed leaves. In contrast, cotton appears to rely on enhanced electron transport flux for light energy utilisation under drought, for example, in enhanced nitrogen assimilation.
Characterisation of xylem conduits and their possible role in limiting the vase life of cut Acacia holosericea (Mimosaceae) foliage stems
Authors: Damunupola Jilushi W. , Ratnayake Kamani , Joyce Daryl C. , Irving Donald E.
Published: July 2011

Early desiccation limits the vase life of Acacia cut flowers and foliage and may be attributable to poor hydraulic conductivity (Kh) of the cut stems. Acacia holosericea A.Cunn. ex G.Don has been adopted as the test species to investigate the postharvest water relations of the genus Acacia. To understand potential constraints on Kh, xylem conduits in cut A. holosericea stems were anatomically characterised by light and scanning and transmission electron microscopy. Vessels with simple perforation plates and tracheids were the principal water conducting cells. Bordered vestured intervessel pits were present in xylem vessel elements. The majority of conduits (89%) were short at 1–5 cm long. Only 2% were 15–16 cm in length. Mean xylem conduit diameter was 77 ± 0.9 µm and the diameter profile showed a normal distribution, with 29% of diameters in the range of 70–80 µm. Simple perforation plates can offer relatively low resistance to water flow. On the other hand, bordered vestured pits and short xylem conduits can confer comparatively high resistance to water flow. Overall, the presence of bordered vestured pits, together with a high proportion of short xylem conduits and high stomatal densities (232 ± 2 mm–2) on unifacial phyllodes, could contribute to early dehydration of A. holosericea cut foliage stems standing in vase water. Further research will relate these anatomical features with changes in Kh and transpiration of cut foliage stems.
Stay-green quantitative trait loci's effects on water extraction, transpiration efficiency and seed yield depend on recipient parent background
Authors: Vadez Vincent , Deshpande Santosh P. , Kholova Jana , Hammer Graeme L. , Borrell Andrew K. , Talwar Harvinder S. , Hash C. Thomas
Published: July 2011

A stay-green phenotype enhances the adaptation of sorghum (Sorghum bicolor (L.) Moench) to terminal drought, although the mechanisms leading to its expression remain unclear. Differences in tillering and leaf area at anthesis, transpiration efficiency (TE), water extraction, harvest index (HI) and yield under terminal drought and fully irrigated conditions were assessed in 29 introgression lines (IL) targeting stay-green quantitative trait loci (QTLs) Stg1, Stg2, Stg3, Stg4, StgA and StgB in an S35 background, and 16 IL targeting Stg1, Stg3, Stg4 and StgB in an R16 background. TE was increased by StgB in the R16 background, whereas there was no effect in the S35 background. Water extraction was increased by Stg1 in the S35 background but not in R16. StgB modified the proportion of water extracted before and after anthesis in the S35 background. While tillering and leaf area at anthesis were decreased by Stg1 and Stg3 in S35, there was no effect in R16. Yield data under fully irrigated conditions showed higher tiller grain yield in Stg1, Stg2 and Stg3 ILs. Although yield differences were mostly explained by HI variation, the yield variation unexplained by HI was closely related to TE in S35 (R2 = 0.29) and R16 (R2 = 0.72), and was closely related to total water extracted in S35 (R2 = 0.41) but not in R16. These data indicate the potential for several stay-green QTLs to affect traits related to plant water use. However, these effects depend on the interaction between the genetic background and individual QTLs.
Contribution of natural and drained wetland systems to carbon stocks, CO2, N2O, and CH4 fluxes: an Australian perspective
Authors: Page K. L. , Dalal R. C.
Published: July 2011

Greenhouse gas (GHG) flux from wetland systems, both in their natural state and following drainage, has not been well accounted for in the carbon accounting process. We review GHG production from both natural and drained wetlands, and estimate the likely GHG emissions from these systems in Australia. Only a small number of studies have quantified GHG emissions from undisturbed Australian wetland environments. Consequently, in order to estimate GHG flux for Australia, it was necessary to collate data collected overseas from similar climatic zones. Using this approach, it appears that undisturbed, vegetated wetlands in Australia are likely to be net GHG sinks, with the greatest rates of sequestration occurring in mangrove ecosystems (–2669 g CO2-e/m2.year) where biomass production is high but CH4 emissions are limited by salinity. The uncertainty surrounding these values is high, however, due to (a) the low number of measurements from Australia, (b) the low number of measurements for CO2 flux, and (c) the low number of studies where all GHGs have been measured concurrently. It was estimated that the drainage of melaleuca and mangrove forest wetlands in Australia would turn them from carbon sinks into carbon sources, and that in the first 50 years since drainage, this has increased global warming potential by 1149 Tg CO2-e or 23 Tg CO2-e/year. This is significant given that GHG emissions due to land-use change in 2007 totalled 77.1 Tg CO2-e. However, data surrounding the area of wetlands drained, carbon stocks in drained wetlands, and the effect of drainage on CH4 and N2O flux are limited, making the uncertainty surrounding these estimates high. Further study is clearly required if Australia wishes to accurately incorporate wetland systems into national carbon and greenhouse gas accounting budgets.
Loss of nitrogen by ammonia volatilisation and denitrification after application of urea to maize in Shanxi Province, China
Authors: Yang Z. P. , Turner D. A. , Zhang J. J. , Wang Y. L. , Chen M. C. , Zhang Q. , Denmead O. T. , Chen D. , Freney J. R.
Published: July 2011

Much of the fertiliser nitrogen (N) used in agriculture is lost to the atmosphere as nitric oxide and nitrogen dioxide (collectively referred to as NOx), ammonia (NH3), and nitrous oxide (N2O). The lost N is not only an economic problem for the farmer; it also contaminates the environment and affects human health. Because the values obtained for NOx and NH3 loss to the atmosphere from agriculture in Monsoon Asia have been questioned, we quantitatively determined, using new techniques, the emission of these gases from a maize crop fertilised with urea in northern China. The fertiliser was deep-placed by traditional farmers’ practice and emissions of NOx and NH3were determined with a chemiluminescence analyser and a backward Lagrangian stochastic dispersion technique. The emission measurements indicate that 1.2% of the applied N was lost as NOx. This loss is far greater than measured or derived by other researchers, and we suggest that this is because our measurements were made continuously rather than as spot measurements with static chambers. The results for NH3 show that, although the fertiliser was placed below the soil surface, a small amount (7% of the applied N) was still lost to the atmosphere. Soil analyses indicate that the rate of nitrification in this soil was low, and the maximum nitrate (NO3–) concentration found in the soil (31.4 µg N/g) was only 3.9% of the fertiliser N added. Thus, there is little potential for NO3– to be leached down the profile. A study using soil cores and acetylene inhibition to measure denitrifying activity suggested that the rate of denitrification in this soil was also very low. The results suggest that in this soil with slow nitrification and denitrification rates and little potential for leaching, deep placement of the urea to limit NH3 volatilisation is an effective method for increasing fertiliser use efficiency.
Recent ecological responses to climate change support predictions of high extinction risk
Authors: Maclean Ilya M. D. , Wilson Robert J.
Published: July 2011

Predicted effects of climate change include high extinction risk for many species, but confidence in these predictions is undermined by a perceived lack of empirical support. Many studies have now documented ecological responses to recent climate change, providing the opportunity to test whether the magnitude and nature of recent responses match predictions. Here, we perform a global and multitaxon metaanalysis to show that empirical evidence for the realized effects of climate change supports predictions of future extinction risk. We use International Union for Conservation of Nature (IUCN) Red List criteria as a common scale to estimate extinction risks from a wide range of climate impacts, ecological responses, and methods of analysis, and we compare predictions with observations. Mean extinction probability across studies making predictions of the future effects of climate change was 7% by 2100 compared with 15% based on observed responses. After taking account of possible bias in the type of climate change impact analyzed and the parts of the world and taxa studied, there was less discrepancy between the two approaches: predictions suggested a mean extinction probability of 10% across taxa and regions, whereas empirical evidence gave a mean probability of 14%. As well as mean overall extinction probability, observations also supported predictions in terms of variability in extinction risk and the relative risk associated with broad taxonomic groups and geographic regions. These results suggest that predictions are robust to methodological assumptions and provide strong empirical support for the assertion that anthropogenic climate change is now a major threat to global biodiversity.
Unprecedented anisotropic metallic state in undoped iron arsenide BaFe
2
As
2
revealed by optical spectroscopy
Authors: Nakajima M. , Liang T. , Ishida S. , Tomioka Y. , Kihou K. , Lee C. H. , Iyo A. , Eisaki H. , Kakeshita T. , Ito T. , Uchida S.
Published: July 2011

An ordered phase showing remarkable electronic anisotropy in proximity to the superconducting phase is now a hot issue in the field of high-transition-temperature superconductivity. As in the case of copper oxides, superconductivity in iron arsenides competes or coexists with such an ordered phase. Undoped and underdoped iron arsenides have a magnetostructural ordered phase exhibiting stripe-like antiferromagnetic spin order accompanied by an orthorhombic lattice distortion; both the spin order and lattice distortion break the tetragonal symmetry of crystals of these compounds. In this ordered state, anisotropy of in-plane electrical resistivity is anomalous and difficult to attribute simply to the spin order and/or the lattice distortion. Here, we present the anisotropic optical spectra measured on detwinned BaFe
2
As
2
crystals with light polarization parallel to the Fe planes. Pronounced anisotropy is observed in the spectra, persisting up to an unexpectedly high photon energy of about 2 eV. Such anisotropy arises from an anisotropic energy gap opening below and slightly above the onset of the order. Detailed analysis of the optical spectra reveals an unprecedented electronic state in the ordered phase.
The human visual system's assumption that light comes from above is weak
Authors: Morgenstern Yaniv , Murray Richard F. , Harris Laurence R.
Published: July 2011

Every biological or artificial visual system faces the problem that images are highly ambiguous, in the sense that every image depicts an infinite number of possible 3D arrangements of shapes, surface colors, and light sources. When estimating 3D shape from shading, the human visual system partly resolves this ambiguity by relying on the light-from-above prior, an assumption that light comes from overhead. However, light comes from overhead only on average, and most images contain visual information that contradicts the light-from-above prior, such as shadows indicating oblique lighting. How does the human visual system perceive 3D shape when there are contradictions between what it assumes and what it sees? Here we show that the visual system combines the light-from-above prior with visual lighting cues using an efficient statistical strategy that assigns a weight to the prior and to the cues and finds a maximum-likelihood lighting direction estimate that is a compromise between the two. The prior receives surprisingly little weight and can be overridden by lighting cues that are barely perceptible. Thus, the light-from-above prior plays a much more limited role in shape perception than previously thought, and instead human vision relies heavily on lighting cues to recover 3D shape. These findings also support the notion that the visual system efficiently integrates priors with cues to solve the difficult problem of recovering 3D shape from 2D images.
Soils on exposed Sunda Shelf shaped biogeographic patterns in the equatorial forests of Southeast Asia
Authors: Slik J. W. Ferry , Aiba Shin-Ichiro , Bastian Meredith , Brearley Francis Q. , Cannon Charles H. , Eichhorn Karl A. O. , Fredriksson Gabriella , Kartawinata Kuswata , Laumonier Yves , Mansor Asyraf , Marjokorpi Antti , Meijaard Erik , Morley Robert J. , Nagamasu Hidetoshi , Nilus Reuben , Nurtjahya Eddy , Payne John , Permana Andrea , Poulsen Axel D. , Raes Niels , Riswan Soedarsono , van Schaik Carel P. , Sheil Douglas , Sidiyasa Kade , Suzuki Eizi , van Valkenburg Johan L. C. H. , Webb Campbell O. , Wich Serge , Yoneda Tsuyoshi , Zakaria Rahmad , Zweifel Nicole
Published: July 2011

The marked biogeographic difference between western (Malay Peninsula and Sumatra) and eastern (Borneo) Sundaland is surprising given the long time that these areas have formed a single landmass. A dispersal barrier in the form of a dry savanna corridor during glacial maxima has been proposed to explain this disparity. However, the short duration of these dry savanna conditions make it an unlikely sole cause for the biogeographic pattern. An additional explanation might be related to the coarse sandy soils of central Sundaland. To test these two nonexclusive hypotheses, we performed a floristic cluster analysis based on 111 tree inventories from Peninsular Malaysia, Sumatra, and Borneo. We then identified the indicator genera for clusters that crossed the central Sundaland biogeographic boundary and those that did not cross and tested whether drought and coarse-soil tolerance of the indicator genera differed between them. We found 11 terminal floristic clusters, 10 occurring in Borneo, 5 in Sumatra, and 3 in Peninsular Malaysia. Indicator taxa of clusters that occurred across Sundaland had significantly higher coarse-soil tolerance than did those from clusters that occurred east or west of central Sundaland. For drought tolerance, no such pattern was detected. These results strongly suggest that exposed sandy sea-bed soils acted as a dispersal barrier in central Sundaland. However, we could not confirm the presence of a savanna corridor. This finding makes it clear that proposed biogeographic explanations for plant and animal distributions within Sundaland, including possible migration routes for early humans, need to be reevaluated.
Insect olfaction from model systems to disease control
Authors: Carey Allison F. , Carlson John R.
Published: July 2011

Great progress has been made in the field of insect olfaction in recent years. Receptors, neurons, and circuits have been defined in considerable detail, and the mechanisms by which they detect, encode, and process sensory stimuli are being unraveled. We provide a guide to recent progress in the field, with special attention to advances made in the genetic model organismDrosophila. We highlight key questions that merit additional investigation. We then present our view of how recent advances may be applied to the control of disease-carrying insects such as mosquitoes, which transmit disease to hundreds of millions of people each year. We suggest how progress in defining the basic mechanisms of insect olfaction may lead to means of disrupting host-seeking and other olfactory behaviors, thereby reducing the transmission of deadly diseases.
Tumor-specific silencing of
COPZ2
gene encoding coatomer protein complex subunit ζ2 renders tumor cells dependent on its paralogous gene
COPZ1
Authors: Shtutman Michael , Baig Mirza , Levina Elina , Hurteau Gregory , Lim Chang-uk , Broude Eugenia , Nikiforov Mikhail , Harkins Timothy T. , Carmack C. Steven , Ding Ye , Wieland Felix , Buttyan Ralph , Roninson Igor B.
Published: July 2011

Anticancer drugs are effective against tumors that depend on the molecular target of the drug. Known targets of cytotoxic anticancer drugs are involved in cell proliferation; drugs acting on such targets are ineffective against nonproliferating tumor cells, survival of which leads to eventual therapy failure. Function-based genomic screening identified the
coatomer protein complex ζ1
(
COPZ1
) gene as essential for different tumor cell types but not for normal cells. COPZ1 encodes a subunit of coatomer protein complex 1 (COPI) involved in intracellular traffic and autophagy. The knockdown of COPZ1, but not of COPZ2 encoding isoform coatomer protein complex ζ2, caused Golgi apparatus collapse, blocked autophagy, and induced apoptosis in both proliferating and nondividing tumor cells. In contrast, inhibition of normal cell growth required simultaneous knockdown of both COPZ1 and COPZ2. COPZ2 (but not COPZ1) was down-regulated in the majority of tumor cell lines and in clinical samples of different cancer types. Reexpression of COPZ2 protected tumor cells from killing by COPZ1 knockdown, indicating that tumor cell dependence on COPZ1 is the result of COPZ2 silencing. COPZ2 displays no tumor-suppressive activities, but it harbors microRNA 152, which is silenced in tumor cells concurrently with COPZ2 and acts as a tumor suppressor in vitro and in vivo. Silencing of microRNA 152 in different cancers and the ensuing down-regulation of its host gene COPZ2 offer a therapeutic opportunity for proliferation-independent selective killing of tumor cells by COPZ1-targeting agents.
Induction of PP2A Bβ, a regulator of IL-2 deprivation-induced T-cell apoptosis, is deficient in systemic lupus erythematosus
Authors: Crispín José C. , Apostolidis Sokratis A. , Finnell Melissa I. , Tsokos George C.
Published: July 2011

The activity and substrate specificity of the ubiquitously expressed phosphatase PP2A is determined by the type of regulatory (B) subunit that couples to the catalytic/scaffold core of the enzyme. We determined that the Bβ subunit (
PPP2R2B
) is expressed in resting T cells, its transcription is down-regulated during T-cell activation, and up-regulated in conditions of low IL-2. Specifically, high levels of PP2A Bβ were produced during IL-2 deprivation-induced apoptosis, whereas Fas ligation had no effect. Forced expression of the Bβ subunit in primary human T cells was sufficient to induce apoptosis, whereas silencing using siRNA protected activated T cells from IL-2 withdrawal-induced cell death. Because T-cell apoptosis is known to be altered in T cells from patients with systemic lupus erythematosus, we analyzed the regulation of PP2A Bβ in this autoimmune disease. We found that levels of PP2A Bβ did not increase upon IL-2 deprivation in 50% of the patients. Remarkably, this defect was accompanied by resistance to apoptosis. Importantly, kinetics of cell death were normal in cells of patients that up-regulated PP2A Bβ in a normal manner. We have identified a unique role for the phosphatase PP2A, particularly the holoenzyme formed by PP2A Bβ. Bβ appears to trigger apoptosis of T cells in the absence of IL-2 and probably contributes to the termination of a no-longer-needed immune response. We propose that defective production of PP2A Bβ upon IL-2 deprivation results in apoptosis resistance and longer survival of autoreactive T cells, in a subset of SLE patients.
Targeted Sos1 deletion reveals its critical role in early T-cell development
Authors: Kortum Robert L. , Sommers Connie L. , Alexander Clayton P. , Pinski John M. , Li Wenmei , Grinberg Alex , Lee Jan , Love Paul E. , Samelson Lawrence E.
Published: July 2011

Activation of the small G protein Ras is required for thymocyte differentiation. In thymocytes, Ras is activated by the Ras guanine exchange factors (RasGEFs) Sos1, Sos2, and RasGRP1. We report the development of a floxed allele ofsos1to assess the role of Sos1 during thymocyte development. Sos1 was required for pre–T-cell receptor (pre-TCR)– but not TCR-stimulated developmental signals. Sos1 deletion led to a partial block at the DN-to-DP transition. Sos1-deficient thymocytes showed reduced pre-TCR–stimulated proliferation, differentiation, and ERK phosphorylation. In contrast, TCR-stimulated positive selection, and negative selection under strong stimulatory conditions, remained intact in Sos1-deficient mice. Comparison of RasGEF expression at different developmental stages showed that relative to Sos2 and RasGRP1, Sos1 is most abundant in DN thymocytes, but least abundant in DP thymocytes. These data reveal that Sos1 is uniquely positioned to affect signal transduction early in thymocyte development.