bluuebunny/crossref_metadata_2025 huggingface dataset:
PKA phosphorylation of the small heat-shock protein Hsp20 enhances its cardioprotective effects
Authors: Edwards Helen V. , Scott John D. , Baillie George S.
Published: January 2012

The small heat-shock protein Hsp20 (heat-shock protein 20), also known as HspB6, has been shown to protect against a number of pathophysiological cardiac processes, including hypertrophy and apoptosis. Following β-adrenergic stimulation and local increases in cAMP, Hsp20 is phosphorylated on Ser16 by PKA (protein kinase A). This covalent modification is required for many of its cardioprotective effects. Both Hsp20 expression levels and its phosphorylation on Ser16 are increased in ischaemic myocardium. Transgenic mouse models with cardiac-specific overexpression of Hsp20 that are subject to ischaemia/reperfusion show smaller myocardial infarcts, and improved recovery of contractile performance during the reperfusion phase, compared with wild-type mice. This has been attributed to Hsp20's ability to protect against cardiomyocyte necrosis and apoptosis. Phosphomimics of Hsp20 (S16D mutants) confer improved protection from β-agonist-induced apoptosis in the heart, whereas phospho-null mutants (S16A) provide no protection. Naturally occurring mutants of Hsp20 at position 20 (P20L substitution) are associated with markedly reduced Hsp20 phosphorylation at Ser16, and this lack of phosphorylation correlates with abrogation of Hsp20's cardioprotective effects. Therefore phosphorylation of Hsp20 at Ser16 by PKA is vital for the cardioprotective actions of this small heat-shock protein. Selective targeting of signalling elements that can enhance this modification represents an exciting new therapeutic avenue for the prevention and treatment of myocardial remodelling and ischaemic injury.
Inhibition of protein kinase B activity induces cell cycle arrest and apoptosis during early G1 phase in CHO cells
Authors: van Opstal Angélique , Bijvelt José , van Donselaar Elly , Humbel Bruno M. , Boonstra Johannes
Published: January 2012

Inhibition of PKB (protein kinase B) activity using a highly selective PKB inhibitor resulted in inhibition of cell cycle progression only if cells were in early G1 phase at the time of addition of the inhibitor, as demonstrated by time‐lapse cinematography. Addition of the inhibitor during mitosis up to 2 h after mitosis resulted in arrest of the cells in early G1 phase, as deduced from the expression of cyclins D and A and incorporation of thymidine. After 24 h of cell cycle arrest, cells expressed the cleaved caspase‐3, a central mediator of apoptosis. These results demonstrate that PKB activity in early G1 phase is required to prevent the induction of apoptosis. Using antibodies, it was demonstrated that active PKB translocates to the nucleus during early G1 phase, while an even distribution of PKB was observed through cytoplasm and nucleus during the end of G1 phase.
Dimensional scaling treatment with relativistic corrections for stable multiply charged atomic ions in high-frequency super-intense laser fields
Authors: Hoehn Ross D. , Wang Jiaxiang , Kais Sabre
Published: January 2012

We present a theoretical framework which describes multiply charged atomic ions, their stability within super-intense laser fields, and also lay corrections to the systems due to relativistic effects. Dimensional scaling calculations with relativistic corrections for systems: H, H−, H2 −, He, He−, He2 −, He3 − within super-intense laser fields were completed. Also completed were three-dimensional self consistent field calculations to verify the dimensionally scaled quantities. With the aforementioned methods the system's ability to stably bind “additional” electrons through the development of multiple isolated regions of high potential energy leading to nodes of high electron density is shown. These nodes are spaced far enough from each other to minimize the electronic repulsion of the electrons, while still providing adequate enough attraction so as to bind the excess electrons into orbitals. We have found that even with relativistic considerations these species are stably bound within the field. It was also found that performing the dimensional scaling calculations for systems within the confines of laser fields to be a much simpler and more cost-effective method than the supporting D = 3 SCF method. The dimensional scaling method is general and can be extended to include relativistic corrections to describe the stability of simple molecular systems in super-intense laser fields.
Tetragonal magnetostriction and magnetoelastic coupling in Fe-Al, Fe-Ga, Fe-Ge, Fe-Si, Fe-Ga-Al, and Fe-Ga-Ge alloys
Authors: Restorff J. B. , Wun-Fogle M. , Hathaway K. B. , Clark A. E. , Lograsso T. A. , Petculescu G.
Published: January 2012

This paper presents a comparative study on the tetragonal magnetostriction constant, λγ,2, [ = (3/2)λ100] and magnetoelastic coupling, b1, of binary Fe100-xZx (0 < x < 35, Z = Al, Ga, Ge, and Si) and ternary Fe-Ga-Al and Fe-Ga-Ge alloys. The quantities are corrected for magnetostrains due to sample geometry (the magnetostrictive form effect). Recently published elastic constant data along with magnetization measurements at both room temperature and 77 K make these corrections possible. The form effect correction lowers the magnetostriction by ∼10 ppm for high-modulus alloys and by as much as 30 ppm for low-modulus alloys. The elastic constants are also used to determine the values of the magnetoelastic coupling constant, b1. With the new magnetostriction data on the Fe-Al-Ga alloy, it is possible to show how the double peak magnetostriction feature of the binary Fe-Ga alloy flows into the single peak binary Fe-Al alloy. The corrected magnetostriction and magnetoelastic coupling data for the various alloys are also compared using the electron-per-atom ratio, e/a, as the common variable. The Hume-Rothery rules link the e/a ratio to the regions of phase stability, which appear to be intimately related to the magnetostriction versus the solute concentration curve in these alloys. Using e/a as the abscissa tends to align the peaks in the magnetostriction and magnetoelastic coupling for the Fe-Ga, Fe-Ge, Fe-Al, Fe-Ga-Al, and Fe-Ga-Ge alloys, but not for the Fe-Si alloys for which the larger atomic size difference may play a greater role in phase stabilization. Corrections for the form effect are also presented for the rhombohedral magnetostriction, λɛ,2, and the magnetoelastic coupling, b2, of Fe100-xGax (0 < x < 35) alloys.
Statistical thermodynamics of 1-butanol, 2-methyl-1-propanol, and butanal
Authors: Seal Prasenjit , Papajak Ewa , Yu Tao , Truhlar Donald G.
Published: January 2012

The purpose of the present investigation is to calculate partition functions and thermodynamic quantities, viz., entropy, enthalpy, heat capacity, and Gibbs free energies, for 1-butanol, 2-methyl-1-propanol, and butanal in the vapor phase. We employed the multi-structural (MS) anharmonicity method and electronic structure calculations including both explicitly correlated coupled cluster theory and density functional theory. The calculations are performed using all structures for each molecule and employing both the local harmonic approximation (MS-LH) and the inclusion of torsional anharmonicity (MS-T). The results obtained from the MS-T calculations are in excellent agreement with experimental data taken from the Thermodynamics Research Center data series and the CRC Handbook of Chemistry and Physics, where available. They are also compared with Benson's empirical group additivity values, where available; in most cases, the present results are more accurate than the group additivity values. In other cases, where experimental data (but not group additivity values) are available, we also obtain good agreement with experiment. This validates the accuracy of the electronic structure calculations when combined with the MS-T method for estimating the thermodynamic properties of systems with multiple torsions, and it increases our confidence in the predictions made with this method for molecules and temperatures where experimental or empirical data are not available.
Comparison of entropy production rates in two different types of self-organized flows: Bénard convection and zonal flow
Authors: Kawazura Y. , Yoshida Z.
Published: January 2012

Two different types of self-organizing and sustaining ordered motion in fluids or plasmas—one is a Bénard convection (or streamer) and the other is a zonal flow—have been compared by introducing a thermodynamic phenomenological model and evaluating the corresponding entropy production rates (EP). These two systems have different topologies in their equivalent circuits: the Bénard convection is modeled by parallel connection of linear and nonlinear conductances, while the zonal flow is modeled by series connection. The “power supply” that drives the systems is also a determinant of operating modes. When the energy flux is a control parameter (as in usual plasma experiments), the driver is modeled by a constant-current power supply, and when the temperature difference between two separate boundaries is controlled (as in usual computational studies), the driver is modeled by a constant-voltage power supply. The parallel (series)-connection system tends to minimize (maximize) the total EP when a constant-current power supply drives the system. This minimum/maximum relation flips when a constant-voltage power supply is connected.
An improved model for non-resonant terahertz detection in field-effect transistors
Authors: Preu S. , Kim S. , Verma R. , Burke P. G. , Sherwin M. S. , Gossard A. C.
Published: January 2012

Transistors operating well above the frequencies at which they have gain can still rectify terahertz currents and voltages, and have attracted interest as room-temperature terahertz detectors. We show that such rectifying field-effect transistors may still be treated as a lumped element device in the limit where plasma resonances of the electron gas do not occur. We derive analytic formulas for important transistor parameters, such as effective rectification length and device impedance using a transmission-line model. We draw conclusions for plasma-resonant detection where possible. We derive the THz response of a field-effect transistor with a two-dimensional electron-gas channel by a Taylor expansion of the drain–source bias. We connect circuit theory to the existing theories that describe the bias in the gated region by differential equations. Parasitic effects, such as the access resistance, are included. With the approach presented in this paper, we derive the responsivity for a novel field detector that mixes a (THz) signal applied between gate and source with another signal applied between drain and source in homodyne or heterodyne operation mode. We further derive expressions for the expected noise-equivalent power (NEP) in direct detection and mixing mode, including parasitic effects, and find that sub-pW/Hz should be achievable for realistic device and material parameters for direct detection and less than 900 K noise temperature for mixing at 10 μW local oscillator power.
Multiscale modeling of particle in suspension with smoothed dissipative particle dynamics
Authors: Bian Xin , Litvinov Sergey , Qian Rui , Ellero Marco , Adams Nikolaus A.
Published: January 2012

We apply smoothed dissipative particle dynamics (SDPD) [Español and Revenga, Phys. Rev. E 67, 026705 (2003)] to model solid particles in suspension. SDPD is a thermodynamically consistent version of smoothed particle hydrodynamics (SPH) and can be interpreted as a multiscale particle framework linking the macroscopic SPH to the mesoscopic dissipative particle dynamics (DPD) method. Rigid structures of arbitrary shape embedded in the fluid are modeled by frozen particles on which artificial velocities are assigned in order to satisfy exactly the no-slip boundary condition on the solid-liquid interface. The dynamics of the rigid structures is decoupled from the solvent by solving extra equations for the rigid body translational/angular velocities derived from the total drag/torque exerted by the surrounding liquid. The correct scaling of the SDPD thermal fluctuations with the fluid-particle size allows us to describe the behavior of the particle suspension on spatial scales ranging continuously from the diffusion-dominated regime typical of sub-micron-sized objects towards the non-Brownian regime characterizing macro-continuum flow conditions. Extensive tests of the method are performed for the case of two/three dimensional bulk particle-system both in Brownian/non-Brownian environment showing numerical convergence and excellent agreement with analytical theories. Finally, to illustrate the ability of the model to couple with external boundary geometries, the effect of confinement on the diffusional properties of a single sphere within a micro-channel is considered, and the dependence of the diffusion coefficient on the wall-separation distance is evaluated and compared with available analytical results.
Chemical sensors based on randomly stacked graphene flakes
Authors: Salehi-Khojin Amin , Estrada David , Lin Kevin Y. , Ran Ke , Haasch Richard T. , Zuo Jian-Min , Pop Eric , Masel Richard I.
Published: January 2012

We demonstrate a simple fabrication method to produce randomly stacked graphene chemiresistors using surfactant-assisted exfoliation of graphite. We analyze the sensitivity of such chemiresistors as a function of vacuum filtration volume and temperature. At low vacuum filtration volumes (<∼5 mL) the sensors exhibit superior sensitivity towards target molecules compared to previously developed polycrystalline graphene, polycrystalline graphene microribbon, and carbon nanotube chemical sensors. Temperature dependent measurements, transmission electron microscopy and scanning electron microscopy suggest the improved sensitivity in the randomly stacked graphene chemiresistors is due to 2-dimensional charge carrier hopping through edge defects.
Size and shape effects on receptor-mediated endocytosis of nanoparticles
Authors: Li Xinlei
Published: January 2012

We present a thermodynamic approach to elucidate the effects of the size and shape of nanoparticles (NPs) on endocytosis. It is found that endocytosis needs to surmount a thermodynamic energy barrier and has a minimum radius of NPs for endocytosis. Through referring to the concept of “diffusion length of receptors,” we obtain a simple and analytical expression for the optimal size of NPs. Furthermore, a phase diagram has been constructed, which can clarify the interrelated effects of the radius and the aspect ratio of NPs. We can identify from the phase the relation between the geometry of NP and its endocytosis rate. The theoretical results are in good agreement with the experimental observations and reveal physical mechanisms involved in the effects of the size and shape of NPs on endocytosis, which implies that these studies may provide useful guidance to the conscious design of NPs for diagnostic agents and drug delivery applications.
Spatiotemporal chaos arising from standing waves in a reaction-diffusion system with cross-diffusion
Authors: Berenstein Igal , Beta Carsten
Published: January 2012

We show that quasi-standing wave patterns appear in the two-variable Oregonator model of the Belousov-Zhabotinsky reaction when a cross-diffusion term is added, no wave instability is required in this case. These standing waves have a frequency that is half the frequency of bulk oscillations displayed in the absence of diffusive coupling. The standing wave patterns show a dependence on the systems size. Regular standing waves can be observed for small systems, when the system size is an integer multiple of half the wavelength. For intermediate sizes, irregular patterns are observed. For large sizes, the system shows an irregular state of spatiotemporal chaos, where standing waves drift, merge, and split, and also phase slips may occur.
Boson peak of alkali and alkaline earth silicate glasses: Influence of the nature and size of the network-modifying cation
Authors: Richet Nicolas F.
Published: January 2012

The influence of the size of the alkaline earth cation on the boson peak of binary metasilicate glasses, MSiO3 (M = Mg, Ca, Sr, Ba), has been investigated from vibrational densities of states determined by inversion of low-temperature heat capacities. As given both by Cp/T 3 and g(ω)/ω2, the intensity of the boson peak undergoes a 7-fold increase from Mg to Ba, whereas its temperature and frequency correlatively decrease from 18 to 10 K and from 100 to 20 cm−1, respectively. The boson peak results from a combination of librations of SiO4 tetrahedra and localized vibrations of network-modifying cations with non-bridging oxygens whose contribution increases markedly with the ionic radius of the alkaline earth. As a function of ionic radii, the intensity for Sr and Ba varies in the same way as previously found for alkali metasilicate glasses. The localized vibrations involving alkali and heavy alkaline earth cations appear to be insensitive to the overall glass structure. Although the new data are coherent with an almost linear relationship between the temperature of the boson peak and transverse sound velocity, pure SiO2 and SiO2-rich glasses make marked exceptions to this trend because of the weak transverse character of SiO4 librations. Finally, the universality of the calorimetric boson peak is again borne out because all data for silicate glasses collapse on the same master curve when plotted in a reduced form (CP/T 3)/(CP/T 3)b vs. T/Tb.
Improving the precision of Hall effect measurements using a single-crystal copper probe
Authors: Cha Su-Young , Moon Shin Jong , Kim Su Jae , Park Sang Eon , Cho Chae Ryong , Cho Yong Chan , Jeong Se-Young
Published: January 2012

The circuitry and components of a Hall measurement kit were replaced with single-crystal copper (SCC) wires and parts prepared by a novel wire fabrication process. This process preserved the grain-free structure of SCC grown by the Czochralski method. The new kit was used to determine, with greatly improved precision, the electrical coefficients such as carrier density and mobility, establish the reproducibility of the measured values, and define the semiconductor type. The observed reduction in electrical signal losses and distortion has been attributed to grain boundary elimination.
A multidentate lubricant for use in hard disk drives at sub-nanometer thickness
Authors: Guo X.-C. , Marchon B. , Wang R.-H. , Mate C. M. , Dai Q. , Waltman R. J. , Deng H. , Pocker D. , Xiao Q.-F. , Saito Y. , Ohtani T.
Published: January 2012

We describe a second generation of multidentate lubricant structures for use on a magnetic media in a hard disk drive. Building on earlier work where a perfluoropolyether (PFPE) chain with hydroxyl bonding moieties were placed in the middle of the chain as well as on chain ends, creating a structure with two PFPE sub-units for enhanced tribological performance under very low head-disk spacing, this paper focuses on a PFPE chain composed of three, even shorter PFPE sub-units. Experimental data focusing on surface characterization of sub-nanometer thickness films, as well as tribological performance, are presented that confirm the high confinement level achieved with the lubricant structure. Molecular dynamics calculations are also discussed, that are consistent with a molecular film of high stiffness, leading to a denser, more compact structure. This approach could pave the way to achieving the sub-nanometer head-disk clearance level, presumed necessary for storage densities exceeding the terabit per square inch density landmark.
Graphene-protein bioelectronic devices with wavelength-dependent photoresponse
Authors: Lu Ye , Lerner Mitchell B. , John Qi Zhengqing , Mitala Joseph J. , Hsien Lim Jong , Discher Bohdana M. , Charlie Johnson A. T.
Published: January 2012

We implemented a nanoelectronic interface between graphene field effect transistors (FETs) and soluble proteins. This enables production of bioelectronic devices that combine functionalities of the biomolecular and inorganic components. The method serves to link polyhistidine-tagged proteins to graphene FETs using the tag itself. Atomic force microscopy and Raman spectroscopy provide structural understanding of the bio/nano hybrid; current-gate voltage measurements are used to elucidate the electronic properties. As an example application, we functionalize graphene FETs with fluorescent proteins to yield hybrids that respond to light at wavelengths defined by the optical absorption spectrum of the protein.
Low-voltage driven visible and infrared electroluminescence from light-emitting device based on Er-doped TiO2/p+-Si heterostructure
Authors: Yang Yang , Jin Lu , Ma Xiangyang , Yang Deren
Published: January 2012

We report on visible and infrared electroluminescence (EL) from the light-emitting device based on Er-doped TiO2/p+-Si heterostructure. Under a forward bias voltage as low as 5.5 V, the device emits ∼1540 nm infrared light and visible light peaking at 522, 553, 564, and 663 nm, respectively, which are originated from Er3+ intra-4f transitions. It is found that the existence of sufficient oxygen vacancies in TiO2 is critical for triggering the Er-related EL. Furthermore, the energy transfer from the oxygen-vacancy-related excitons in TiO2 matrix to Er3+ ions is supposed to be responsible for the above-mentioned EL.
Fabrication of nanometer-size structures in metal thin films using femtosecond laser Bessel beams
Authors: Yalizay B. , Ersoy T. , Soylu B. , Akturk S.
Published: January 2012

We report nanometer-scale fabrication on metal thin films using ablation by femtosecond laser pulses, with Bessel beam profiles. Choosing the laser fluence around ablation threshold allows control of the structure size below the diffraction limit. We show that using Bessel beams has several advantages. Bessel beams have focal spot sizes insensitive to longitudinal position, which significantly relaxes alignment constraints. Tighter foci are easier to generate, less costly, and less prone to aberrations. Scaling the method to shorter wavelengths, and hence increasing the resolution is also straightforward. By using the proposed method, we generate structures with resolution below 200 nm.
A study of the dielectric and magnetic properties of multiferroic materials using the Monte Carlo method
Authors: Sosa A. , Almodovar N. S. , Portelles J. , Heiras J. , Siqueiros J. M.
Published: January 2012

A study of the dielectric and magnetic properties of multiferroic materials using the Monte Carlo (MC) method is presented. Two different systems are considered: the first, ferroelectric-antiferromagnetic (FE-AFM) recently studied by X. S. Gaoand J. M. Liu and the second antiferroelectric-ferromagnetic (AFE-FM). Based on the DIFFOUR-Ising hybrid microscopic model developed by Janssen, a Hamiltonian that takes into account the magnetoelectric coupling in both ferroic phases is proposed. The obtained results show that the existence of such coupling modifies the ferroelectric and magnetic ordering in both phases. Additionally, it is shown that the presence of a magnetic or an electric field influences the electric polarization and the magnetization, respectively, making evident the magnetoelectric effect.
Nanoparticle production in arc generated fireballs of granular silicon powder
Authors: Ito Tsuyohito , Cappelli Mark A.
Published: January 2012

Recently we observed buoyant fireballs by arc igniting silicon that drift in air for several seconds and postulated that the low aggregate density was attributed to the formation of a network of nanoparticles that must completely surround the burning silicon core, trapping the heated vapor generated as a result of particle combustion [Ito et al. Phys Rev E 80, 067401 (2009)]. In this paper, we describe the capturing of several of these fireballs in flight, and have characterized their nanostructure by high resolution microscopy. The nanoparticle network is found to have an unusually high porosity (> 99%), suggesting that this arc-ignition of silicon can be a novel method of producing ultra-porous silica. While we confirm the presence of a nanoparticle network within the fireballs, the extension of this mechanism to the production of ball lightning during atmospheric lightning strikes in nature is still the subject of ongoing debate.
COPICAT: a software system for predicting interactions between proteins and chemical compounds
Authors: Sakakibara Yasubumi , Hachiya Tsuyoshi , Uchida Miho , Nagamine Nobuyoshi , Sugawara Yohei , Yokota Masahiro , Nakamura Masaomi , Popendorf Kris , Komori Takashi , Sato Kengo
Published: January 2012

Summary: Since tens of millions of chemical compounds have been accumulated in public chemical databases, fast comprehensive computational methods to predict interactions between chemical compounds and proteins are needed for virtual screening of lead compounds. Previously, we proposed a novel method for predicting protein–chemical interactions using two-layer Support Vector Machine classifiers that require only readily available biochemical data, i.e. amino acid sequences of proteins and structure formulas of chemical compounds.

In this article, the method has been implemented as the COPICAT web service, with an easy-to-use front-end interface. Users can simply submit a protein–chemical interaction prediction job using a pre-trained classifier, or can even train their own classification model by uploading training data. COPICAT's fast and accurate computational prediction has enhanced lead compound discovery against a database of tens of millions of chemical compounds, implying that the search space for drug discovery is extended by >1000 times compared with currently well-used high-throughput screening methodologies.

Availability: The COPICAT server is available at http://copicat.dna.bio.keio.ac.jp. All functions, including the prediction function are freely available via anonymous login without registration. Registered users, however, can use the system more intensively.

Contact:  yasu@bio.keio.ac.jp
The sva package for removing batch effects and other unwanted variation in high-throughput experiments
Authors: Leek Jeffrey T. , Johnson W. Evan , Parker Hilary S. , Jaffe Andrew E. , Storey John D.
Published: January 2012

Summary: Heterogeneity and latent variables are now widely recognized as major sources of bias and variability in high-throughput experiments. The most well-known source of latent variation in genomic experiments are batch effects—when samples are processed on different days, in different groups or by different people. However, there are also a large number of other variables that may have a major impact on high-throughput measurements. Here we describe the sva package for identifying, estimating and removing unwanted sources of variation in high-throughput experiments. The sva package supports surrogate variable estimation with the sva function, direct adjustment for known batch effects with the ComBat function and adjustment for batch and latent variables in prediction problems with the fsva function.

Availability: The R package sva is freely available from http://www.bioconductor.org.

Contact:  jleek@jhsph.edu

Supplementary information:  Supplementary data are available at Bioinformatics online.
Comparative Effectiveness of the C-MAC Video Laryngoscope versus Direct Laryngoscopy in the Setting of the Predicted Difficult Airway
Authors: Aziz Michael F. , Dillman Dawn , Fu Rongwei , Brambrink Ansgar M.
Published: January 2012

Background

Video laryngoscopy may be useful in the setting of the difficult airway, but it remains unclear if intubation success is improved in routine difficult airway management. This study compared success rates for tracheal intubation with the C-MAC® video laryngoscope (Karl Storz, Tuttlingen, Germany) with conventional direct laryngoscopy in patients with predicted difficult airway.

Methods

We conducted a two arm, single-blinded randomized controlled trial that involved 300 patients. Inclusion required at least one of four predictors of difficult intubation. The primary outcome was successful tracheal intubation on first attempt.

Results

The use of video laryngoscopy resulted in more successful intubations on first attempt (138/149; 93%) as compared with direct laryngoscopy (124/147; 84%), P = 0.026. Cormack-Lehane laryngeal view was graded I or II in 139/149 of C-MAC attempts versus 119/147 in direct laryngoscopy attempts (P < 0.01). Laryngoscopy time averaged 46 s (95% CI, 40-51) for the C-MAC group and was shorter in the direct laryngoscopy group, 33 s (95% CI, 29-36), P < 0.001. The use of a gum-elastic bougie and/or external laryngeal manipulation were required less often in the C-MAC intubations (24%, 33/138) compared with direct laryngoscopy (37%, 46/124, P = 0.020). The incidence of complications was not significantly different between the C-MAC (20%, 27/138) versus direct laryngoscopy (13%, 16/124, P = 0.146).

Conclusion

A diverse group of anesthesia providers achieved a higher intubation success rate on first attempt with the C-MAC in a broad range of patients with predictors of difficult intubation. C-MAC laryngoscopy seems to be a useful technique for the initial approach to a potentially difficult airway.
Predicting oscillatory dynamics in the movement of territorial animals
Authors: Giuggioli L. , Potts J. R. , Harris S.
Published: January 2012

Understanding ecological processes relies upon the knowledge of the dynamics of each individual component. In the context of animal population ecology, the way animals move and interact is of fundamental importance in explaining a variety of observed patterns. Here, we present a theoretical investigation on the movement dynamics of interacting scent-marking animals. We study how the movement statistics of territorial animals is responsible for the appearance of damped oscillations in the mean square displacement (MSD) of the animals. This non-monotonicity is shown to depend on one dimensionless parameter, given by the ratio of the correlation distance between successive steps to the size of the territory. As that parameter increases, the time dependence of the animal's MSD displays a transition from monotonic, characteristic of Brownian walks, to non-monotonic, characteristic of highly correlated walks. The results presented here represent a novel way of determining the degree of persistence in animal movement processes within confined regions.
Classical swine fever virus NS5B protein suppresses the inhibitory effect of NS5A on viral translation by binding to NS5A
Authors: Sheng Chun , Wang Jing , Xiao Jing , Xiao Jun , Chen Yan , Jia Lin , Zhi Yimiao , Li Guangyuan , Xiao Ming
Published: January 2012

In order to investigate molecular mechanisms of internal ribosome entry site (IRES)-mediated translation in classical swine fever virus (CSFV), an important pathogen of pigs, the expression level of NS3 was evaluated in the context of genomic RNAs and reporter RNA fragments. All data showed that the NS5A protein has an inhibitory effect on IRES-mediated translation and that NS5B proteins suppress the inhibitory effect of NS5A on viral translation, but CSFV NS5B GDD mutants do not. Furthermore, glutathione S-transferase pull-down assay and immunoprecipitation analysis, associated with deletion and alanine-scanning mutations, were performed. Results showed that NS5B interacts with NS5A and that the region aa 390–414, located in the C-terminal half of NS5A, is important for binding of NS5B to NS5A. Furthermore, amino acids K399, T401, E406 and L413 in the region were found to be essential for NS5A–NS5B interaction, virus rescue and infection. The above-mentioned region and four amino acids were observed to overlap with the site responsible for inhibition of IRES-mediated translation by the NS5A protein. We also found that aa 63–72, aa 637–653 and the GDD motif of NS5B were necessary for the interaction between NS5A and NS5B. These findings suggest that the repression activity of the NS5B protein toward the role of NS5A in translation might be achieved by NS5A–NS5B interaction, for which aa 390–414 of NS5A and aa 63–72, aa 637–653 and the GDD motif of NS5B are indispensable. This is important for understanding the role of NS5A–NS5B interaction in the virus life cycle.
Funding source and conflict of interest disclosures by authors and editors in gastroenterology specialty journals revisited
Authors: Qureshi J. , Sud A. , Vakil N.
Published: January 2012

Background

A survey of journals published in the field of Gastroenterology conducted 5 years ago showed marked variability in reporting of conflicts of interest or funding sources in these journals.

Aim

To re‐examine reporting of conflicts of interest and funding sources for original articles and editorials in Gastroenterology and Hepatology journals.

Methods

We evaluated all original articles and editorials in 15 leading journals (determined by impact factor‐Thomson Reuter Science Citation Index) devoted to Gastroenterology and Hepatology for disclosures of conflicts and for editor's self disclosures. We examined each journal's editorial policy by contacting the journal directly if the information was not revealed on the Web site or print versions of the journal.

Results

Of the 1574 articles evaluated, a total of 1207 (77%) reported the presence or absence of a potential conflict of interest and 1047 (67%) reported the presence or absence of funding sources. A total of 3 of the 15 (20%) journals (American Journal of Gastroenterology, Gastroenterology, and Alimentary Pharmacology and Therapeutics reported the presence or absence of funding sources in all their published original articles. Only 5 of 15 (33%) journals (Gut, Gastrointestinal Endoscopy, American Journal of Gastroenterology, Neurogastroenterology & Motility and Alimentary Pharmacology and Therapeutics) publicly disclosed the conflicts of interest of the editors.

Conclusions

(i) Funding sources and conflicts of interest are still reported variably in the GI literature. (ii) Editorials and review articles are influential, but have poor reporting of conflicts of interest. (iii) Editors of many journals still do not report their conflicts of interest.
Harvester ants modify seed rain using nest vegetation and granivory
Authors: NICOLAI NANCY , BOEKEN BERTRAND R.
Published: January 2012

1. In annual plant communities, the seed bank determines each generation's potential emergence and any factor that influences it could alter community structure. Harvester ants are common seed predators that may cause seed sources and seed rain composition to vary.

2. In semi‐arid shrubland of the Negev desert of Israel, we hypothesised that the positive effects of dense vegetation on nests of the harvester ant Messor ebeninus Sant. would outweigh reduction by granivory.

3. To test whether nests were seed sources, we removed vegetation on 10 of 20 sampled nests prior to seeding. We tested the interaction between seed sources and granivory by locating seed traps at three locations: nests, foraging trails, and unvisited areas. Trapped seeds were recorded during spring and summer dispersal. Plant recruitment from the altered seed bank was recorded the following spring.

4. During April, seeds were more abundant near nests than the other locations and at uncut compared with cut nests. Foraging trails had fewer species and higher equitability compared with nests or unvisited areas. May and June to August had highest species richness at nests, but richness of cut and uncut nests were similar. Ordination of plant recruitment showed slightly lower vegetation community variation by diminished species in the cut seed bank.

5. While intact nest vegetation initially had high abundance of locally deposited seeds, it apparently blocked wind‐dispersed seeds later in the summer. Conversely, granivory reduced seed species richness only on trails and decreased dominance structure by preferential removal of some species.
Entomopathogenic fungi stimulate transgenerational wing induction in pea aphids, Acyrthosiphon pisum (Hemiptera: Aphididae)
Authors: HATANO EDUARDO , BAVERSTOCK JASON , KUNERT GRIT , PELL JUDITH K. , WEISSER WOLFGANG W.
Published: January 2012

1. Aphid natural enemies include not only predators and parasitoids but also pathogens, of which fungi are the most studied for biological control. While wing formation in aphids is induced by abiotic conditions, it is also affected by biotic interactions with their arthropod natural enemies. Wing induction via interactions with arthropod natural enemies is mediated by the increase in their physical contact when alarmed (pseudo‐crowding). Pathogenic fungi do not trigger this alarm behaviour in aphids and, therefore, no pseudo‐crowding occurs.

2. We hypothesise that, while pathogenic fungi will stimulate maternally induced wing formation, the mechanism is different and is influenced by pathogen specificity. We tested this hypothesis using two entomopathogenic fungi, Pandora neoaphidis and Beauveria bassiana, an aphid specialist and a generalist respectively, on the pea aphid, Acyrthosiphon pisum Harris.

3. We first demonstrate that pea aphids infected with either pathogen and maintained in groups on broad bean plants produced a higher proportion of winged morphs than uninfected control aphids. We then show that, when maintained in isolation, aphids infected with either pathogen also produced higher proportions of winged offspring than control aphids. There was no difference between P. neoaphidis and B. bassiana in their effects on wing induction in either experiment.

4. Unlike the effect of predators and parasitoids on pea aphid wing induction, the effect of pathogens is independent of physical contact with other aphids, suggesting that physiological cues induce wing formation in infected aphids. It is possible that aphids benefit from wing induction by escaping infected patches whilst pathogens may benefit through dispersion. Possible mechanisms of wing induction are discussed.
Variation in performance of two co‐occurring mosquito species across diverse resource environments: insights from nutrient and stable isotope analyses
Authors: WINTERS ANNE E. , YEE DONALD A.
Published: January 2012

1. Inputs of animal and plant detritus are the main energy sources for food webs in a number of isolated container systems, including discarded automobile tyres and tree holes. Containers are dominated by mosquitoes in the generaCulexandAedes, which among other differences often engage in different foraging behaviours. We hypothesised that becauseAedesfeed more by browsing surfaces, whereasCulexoften filter the water column, these mosquitoes would show variation in performance and differentially affect detritus. Effects of different ratios of animal and plant detritus on survival, mass, and development time for two common container mosquito species,Culex restuansL. andAedes albopictusSkuse, were examined. We also quantified detrital contribution to biomass via isotopic and nutrient analysis and the effect of larvae on detrital decay.

2. Adult male and female mass of both species was highest with some animal detritus and lowest in only leaf detritus.Aedes albopictussurvival was higher thanC. restuansacross most detritus ratios.

3.Aedes albopictushad higher values of15N and in some cases13C across all detritus ratios compared withC. restuans;A. albopictushad lower nitrogen in tissue.Aedes albopictusappeared to be more efficient at obtaining potentially limiting nutrients and had a greater overall effect on detrital decay – a possible consequence of greater foraging effort.

4. Findings further support the view that mosquito performance can be influenced by detritus type, and provide a more precise hypothesis (i.e. lower need for nitrogen) that may explain the superior competitive ability ofA. albopictusover other container mosquitoes.
Seasonal patterns of predation for gray wolves in the multi‐prey system of Yellowstone National Park
Authors: Metz Matthew C. , Smith Douglas W. , Vucetich John A. , Stahler Daniel R. , Peterson Rolf O.
Published: January 2012

1. For large predators living in seasonal environments, patterns of predation are likely to vary among seasons because of related changes in prey vulnerability. Variation in prey vulnerability underlies the influence of predators on prey populations and the response of predators to seasonal variation in rates of biomass acquisition. Despite its importance, seasonal variation in predation is poorly understood.

2. We assessed seasonal variation in prey composition and kill rate for wolves Canis lupus living on the Northern Range (NR) of Yellowstone National Park. Our assessment was based on data collected over 14 winters (1995–2009) and five spring–summers between 2004 and 2009.

3. The species composition of wolf‐killed prey and the age and sex composition of wolf‐killed elk Cervus elaphus (the primary prey for NR wolves) varied among seasons.

4. One’s understanding of predation depends critically on the metric used to quantify kill rate. For example, kill rate was greatest in summer when quantified as the number of ungulates acquired per wolf per day, and least during summer when kill rate was quantified as the biomass acquired per wolf per day. This finding contradicts previous research that suggests that rates of biomass acquisition for large terrestrial carnivores tend not to vary among seasons.

5. Kill rates were not well correlated among seasons. For example, knowing that early‐winter kill rate is higher than average (compared with other early winters) provides little basis for anticipating whether kill rates a few months later during late winter will be higher or lower than average (compared with other late winters). This observation indicates how observing, for example, higher‐than‐average kill rates throughout any particular season is an unreliable basis for inferring that the year‐round average kill rate would be higher than average.

6. Our work shows how a large carnivore living in a seasonal environment displays marked seasonal variation in predation because of changes in prey vulnerability. Patterns of wolf predation were influenced by the nutritional condition of adult elk and the availability of smaller prey (i.e. elk calves, deer). We discuss how these patterns affect our overall understanding of predator and prey population dynamics.
Interspecific interactions drive cultural co‐evolution and acoustic convergence in syntopic species
Authors: Laiolo Paola
Published: January 2012

1. Antagonistic interactions have been favourite subjects of studies on species co‐evolution, because coexistence among competing species often results in quantifiable character displacement. A common output for competitive interactions is trait divergence, although the opposite phenomenon, convergence, has been proposed to evolve in some instances, for example in the communication behaviour of species that maintain mutually exclusive territories.

2. I use here experimental and observational evidence to study how species interactions drive heterospecific signal convergence and analyse how convergence feeds back to the interaction itself, in the form of aggressive behaviour. I recorded the learned territorial signals of two non‐hybridizing larks, Galerida cristata and G. theklae, and used allopatric populations as controls for evaluating acoustic convergence in syntopy. Acoustic variation was analysed with respect to social conditions controlling for other potential agents of natural selection, habitat and climate.

3. Interspecific convergence of Galerida calls peaked in syntopy. Although call acoustic structure was affected by climate and habitat, it matched gradients of density and proximity to congeners even at small local scales. The process of cultural transmission, in which individuals may acquire components of behaviour by copying neighbours, enhances the correlation between call acoustics and the local social milieu.

4. Territories were defended against both species, but playback stimuli of convergent congener calls elicited a stronger aggressive reaction than congener calls from allopatric locations.

5. This study shows that learned behaviours may co‐evolve as a consequence of antagonistic interactions, determining reciprocal cultural evolution or cultural co‐evolution. As for (biological) co‐evolution, the distribution of competing species influences whether a particular area becomes a syntopic environment in which convergence is occurring, or an allopatric environment lacking interactions and reciprocal change. Because of their plastic nature, cultural coadaptations may rapidly shift in response to fluctuating social selection, thus propelling dynamic interactions and fine adjustments to the local environment.
The immune evasion protein Sbi of Staphylococcus aureus occurs both extracellularly and anchored to the cell envelope by binding lipoteichoic acid
Authors: Smith Emma Jane , Corrigan Rebecca M. , van der Sluis Tetje , Gründling Angelika , Speziale Pietro , Geoghegan Joan A. , Foster Timothy J.
Published: January 2012

The Sbi protein of Staphylococcus aureus comprises two IgG‐binding domains similar to those of protein A and a region that triggers the activation of complement C3. Sbi is expressed on the cell surface but its C‐terminal domain lacks motifs associated with wall or membrane anchoring of proteins in Gram‐positive bacteria. Cell‐associated Sbi fractionates with the cytoplasmic membrane and is not solubilized during protoplast formation. S. aureus expressing Sbi truncates of the C‐terminal Y domain allowed identification of residues that are required for association of Sbi with the membrane. Recombinant Sbi bound to purified cytoplasmic membrane material in vitro and to purified lipoteichoic acid. This explains how Sbi partitions with the membrane in fractionation experiments yet is partially exposed on the cell surface. An LTA‐defective mutant of S. aureus had reduced levels of Sbi in the cytoplasmic membrane.
Heart rate variability in the irritable bowel syndrome: a review of the literature
Authors: Mazurak N. , Seredyuk N. , Sauer H. , Teufel M. , Enck P.
Published: January 2012

Background  Patients with irritable bowel syndrome (IBS) often present with disturbances of bowel habits (diarrhea, constipation) and abdominal pain/discomfort that are modulated by the autonomic nerve system (ANS). In this narrative review, we analyzed studies that measured ANS functioning in IBS by means of heart rate variability (HRV).

Methods  The PUBMED was searched with the keywords ‘irritable bowel syndrome’ AND (‘heart rate variability’ OR ‘autonomic function’). We included only papers that used ‘traditional’ HRV indices and diagnosed IBS based on Manning or Rome criteria. Studies were sub‐grouped according to methodological features of HRV analysis (24‐h monitoring, short‐term laboratory records, records during sleep).

Key Results  Most studies reported no difference in HRV when the IBS population was compared to healthy controls. Dividing the IBS sample into subgroups – according to their predominant bowel symptoms, the severity of clinical course, the presence of depressive symptoms, or a history of abuse in the past – revealed changes in autonomic functioning.

Conclusions & Inferences  Patients with IBS appear to experience symptoms that may be the result of changes in ANS functioning. HRV measures in clinical routine may allow assessing these changes, but further studies performed in a standardized fashion should improve the validity of HRV measures for clinical research first.