bluuebunny/crossref_metadata_2025 huggingface dataset:
Spirodiclofen and spirotetramat bioassays for monitoring resistance in citrus red mite, Panonychus citri (Acari: Tetranychidae)
Authors: Ouyang Yuling , Montez Gregory H , Liu Lucy , Grafton‐Cardwell Elizabeth E
Published: November 2011

BACKGROUND: Citrus red mite, Panonychus citri (McGregor), is a key pest of San Joaquin Valley California citrus. Spirodiclofen was registered for mite control in 2007, and spirotetramat for scale control in 2008. Because of the potential for resistance to spirodiclofen to develop in spider mites, and cross‐resistance to spirotetramat used for other citrus pests, bioassay methods for resistance monitoring were developed.

RESULTS: The responses of four populations of adult female, egg and larval stages of P. citri to spirodiclofen were compared to determine the most robust bioassay method for this pesticide. Adult females responded with a higher LC99 and larval stages exhibited higher control mortality and a lower slope of response compared with the egg stage. Thus, the egg stage was found to be the most suitable stage for testing. Egg production and egg shape were significantly affected by spirodiclofen treatment of adult female mites. Bioassays with the related compound spirotetramat revealed that P. citri egg hatch was less affected by this compound, requiring the assessment of mortality to be extended to 11 days after treatment when the hatched larvae succumbed to the pesticide. Discriminating concentrations of 10 ppm for spirodiclofen and 31.6 ppm for spirotetramat in an 11 day bioassay were tested against eight field populations of P. citri, and 99–100% mortality resulted.

CONCLUSION: These results provide a baseline for the response of P. citri to spirodiclofen and spirotetramat that will aid resistance management in California citrus. Copyright © 2011 Society of Chemical Industry
2,2′‐Dithiobis(5‐nitropyridine) (DTNP) as an effective and gentle deprotectant for common cysteine protecting groups
Authors: Schroll Alayne L. , Hondal Robert J. , Flemer Stevenson
Published: November 2011

Of all the commercially available amino acid derivatives for solid phase peptide synthesis, none has a greater abundance of side‐chain protection diversity than cysteine. The high reactivity of the cysteine thiol necessitates its attenuation during peptide construction. Moreover, the propensity of cysteine residues within a peptide or protein sequence to form disulfide connectivity allows the opportunity for the peptide chemist to install these disulfides iteratively as a post‐synthetic manipulation through the judicious placement of orthogonal pairs of cysteine S‐protection within the peptide's architecture. It is important to continuously discover new vectors of deprotection for these different blocking protocols in order to achieve the highest degree of orthogonality between the removal of one species in the presence of another. We report here a complete investigation of the scope and limitations of the deprotective potential of 2,2′‐dithiobis(5‐nitropyridine) (DTNP) on a selection of commercially available Cys S‐protecting groups. The gentle conditions of DTNP in a TFA solvent system show a remarkable ability to deprotect some cysteine blocking functionality traditionally removable only by more harsh or forcing conditions. Beyond illustrating the deprotective ability of this reagent cocktail within a cysteine‐containing peptide sequence, the utility of this method was further demonstrated through iterative disulfide formation in oxytocin and apamin test peptides. It is shown that this methodology has high potential as a stand‐alone cysteine deprotection technique or in further manipulation of disulfide architecture within a more complex cysteine‐containing peptide template. Copyright © 2011 European Peptide Society and John Wiley & Sons, Ltd.
Towards Comparative Measures of Circulation: Insights from Indigenous Australia
Authors: Taylor John , Bell Martin
Published: November 2011

Circulation and other forms of temporary movement are of rising importance in the context of overall population mobility. Despite this, analysis is constrained by a lack of appropriate data and techniques for developing summary measures. Ethnographic methods have afforded useful insights into the complex space–time circuits and lifetime sequences involved, but without quantitative indicators these forms of mobility are effectively invisible to researchers and policy makers. Building on prior work in developing countries we advance methodologies for summarising the temporal dimension of circular mobility. Using illustrative data drawn from a variety of field studies among indigenous peoples in Australia we show how lifelines tracing individual mobility profiles can be used to generate systematic measures of frequency and duration. When plotted graphically these reveal distinctive periodicities that correspond to particular forms of mobility behaviour. Because these metrics are scalable and readily amenable to collection in general surveys they offer a unique bridge between the richness of detail that flows from biographic approaches and the aggregate metrics needed for statistical comparison. Copyright © 2011 John Wiley & Sons, Ltd.
Networked LQG control over unreliable channels
Authors: Moayedi M. , Foo Y.K. , Soh Y.C.
Published: November 2011

In this article, the linear quadratic Gaussian (LQG) optimal control problem for networked control systems when data is transmitted through a transmission control protocol (TCP)‐like network and both measurement and control packets are subject to random packet dropouts, is addressed for two cases. In the ﬁrst case, it is assumed that the control acknowledgment packets in TCP‐like protocols are always available, that is, they always reach the ﬁlter‐controller unit on time and without fail, and we propose how to design a linear optimal ‘hold‐input’ control law for this case. In the second problem, we assume the acknowledgement packets may go missing with a known probability. This case is known to be diﬃcult and the optimal control law would be nonlinear. Hence, we derive a suboptimal linear estimation‐control law instead. Simulation results are presented to demonstrate the effectiveness of the proposed approaches. Copyright © 2011 John Wiley & Sons, Ltd.
Consistency in explaining model behavior based on its feedback structure
Authors: Mojtahedzadeh Mohammad
Published: November 2011

Real‐world concepts can be operationalized into a variety of feedback structures which may be mathematically identical but diverse in the number of feedback loops. Factors including model purpose, the modeler's perspective and the intended audience all influence the final layout of a feedback‐rich model. One challenge in the analysis of model behavior is to account for the variations in the appearance of its structure and the feedback loops. This technical paper focuses on consistency in explaining model behavior and illustrates some of the issues related to the cancellation problem and figure‐8 loops. Both conditions can potentially lead to poor and even contradictory explanations of model behavior based on its idiosyncratic feedback structure. The paper presents three case studies and demonstrates that for these case studies the pathway participation approach remains consistent in detecting the dominant structure regardless of variations in the number of feedback loops in mathematically equivalent models. The paper calls for comparative studies using alternative approaches to model analysis to better understand the general principles and subtleties in connecting the structure to the behavior and explaining observed dynamics. Copyright © 2011 System Dynamics Society.
The impact of current and founding institutions on strength of competitive aspirations in transition economies
Authors: Shinkle George A. , Kriauciunas Aldas P.
Published: November 2011

Northian institutional theory argues that firms adapt to their current institutional environments. Organizational imprinting theory argues that firms will be constrained by their founding institutional environments. We explore the combined influence of these two institutional environments on the strength of competitive aspirations using a unique dataset of firms in the shifted institutional environment of Central European transition economies. Our results indicate founding institutional environments temper adaptation to current institutional environments for certain competitive aspirations and this effect increases as the size of the shift between current and founding institutional environments increases. Copyright © 2011 John Wiley & Sons, Ltd.
Nitric Oxide Sustains Long-Term Skeletal Muscle Regeneration by Regulating Fate of Satellite Cells Via Signaling Pathways Requiring Vangl2 and Cyclic GMP
Authors: Buono Roberta , Vantaggiato Chiara , Pisa Viviana , Azzoni Emanuele , Bassi Maria Teresa , Brunelli Silvia , Sciorati Clara , Clementi Emilio
Published: November 2011

Satellite cells are myogenic precursors that proliferate, activate, and differentiate on muscle injury to sustain the regenerative capacity of adult skeletal muscle; in this process, they self-renew through the return to quiescence of the cycling progeny. This mechanism, while efficient in physiological conditions does not prevent exhaustion of satellite cells in pathologies such as muscular dystrophy where numerous rounds of damage occur. Here, we describe a key role of nitric oxide, an important signaling molecule in adult skeletal muscle, on satellite cells maintenance, studied ex vivo on isolated myofibers and in vivo using the α-sarcoglycan null mouse model of dystrophy and a cardiotoxin-induced model of repetitive damage. Nitric oxide stimulated satellite cells proliferation in a pathway dependent on cGMP generation. Furthermore, it increased the number of Pax7+/Myf5− cells in a cGMP-independent pathway requiring enhanced expression of Vangl2, a member of the planar cell polarity pathway involved in the Wnt noncanonical pathway. The enhanced self-renewal ability of satellite cells induced by nitric oxide is sufficient to delay the reduction of the satellite cell pool during repetitive acute and chronic damages, favoring muscle regeneration; in the α-sarcoglycan null dystrophic mouse, it also slowed disease progression persistently. These results identify nitric oxide as a key messenger in satellite cells maintenance, expand the significance of the Vangl2-dependent Wnt noncanonical pathway in myogenesis, and indicate novel strategies to optimize nitric oxide-based therapies for muscular dystrophy.

Disclosure of potential conflicts of interest is found at the end of this article.
The Crosstalk Between Transforming Growth Factor-β1 and Delta Like-1 Mediates Early Chondrogenesis During Embryonic Endochondral Ossification
Authors: Taipaleenmäki Hanna , Harkness Linda , Chen Li , Larsen Kenneth H. , Säämänen Anna-Marja , Kassem Moustapha , Abdallah Basem M.
Published: November 2011

Delta like-1 (Dlk1)/preadipocyte factor-1 (Pref-1)/fetal antigen-1 (FA1) is a novel surface marker for embryonic chondroprogenitor cells undergoing lineage progression from proliferation to prehypertrophic stages. However, mechanisms mediating control of its expression during chondrogenesis are not known. Thus, we examined the effect of a number of signaling molecules and their inhibitors on Dlk1 expression during in vitro chondrogenic differentiation in mouse embryonic limb bud mesenchymal micromass cultures and mouse embryonic fibroblast (MEF) pellet cultures. Dlk1/Pref-1 was initially expressed during mesenchymal condensation and chondrocyte proliferation, in parallel with expression of Sox9 and Col2a1, and was downregulated upon the expression of Col10a1 by hypertrophic chondrocytes. Among a number of molecules that affected chondrogenesis, transforming growth factor-β1 (TGF-β1)-induced proliferation of chondroprogenitors was associated with decreased Dlk1 expression. This effect was abolished by TGF-β signaling inhibitor SB431542, suggesting regulation of Dlk1/FA1 by TGF-β1 signaling in chondrogenesis. TGF-β1-induced Smad phosphorylation and chondrogenesis were significantly increased in Dlk1−/− MEF, while they were blocked in Dlk1 overexpressing MEF, in comparison with wild-type MEF. Furthermore, overexpression of Dlk1 or addition of its secreted form FA1 dramatically inhibited TGF-β1-induced Smad reporter activity. In conclusion, our data identified Dlk1/FA1 as a downstream target of TGF-β1 signaling molecule that mediates its function in embryonic chondrogenesis. The crosstalk between TGF-β1 and Dlk1/FA1 was shown to promote early chondrogenesis during the embryonic endochondral ossification process.

Disclosure of potential conflicts of interest is found at the end of this article.
Pathfinding in angiosperm reproduction: pollen tube guidance by pistils ensures successful double fertilization
Authors: Palanivelu Ravishankar , Tsukamoto Tatsuya
Published: November 2011

Sexual reproduction in flowering plants is unique in multiple ways. Distinct multicellular gametophytes contain either a pair of immotile, haploid male gametes (sperm cells) or a pair of female gametes (haploid egg cell and homodiploid central cell). After pollination, the pollen tube, a cellular extension of the male gametophyte, transports both male gametes at its growing tip and delivers them to the female gametes to affect double fertilization. The pollen tube travels a long path and sustains its growth over a considerable amount of time in the female reproductive organ (pistil) before it reaches the ovule, which houses the female gametophyte. The pistil facilitates the pollen tube's journey by providing multiple, stage‐specific, nutritional, and guidance cues along its path. The pollen tube interacts with seven different pistil cell types prior to completing its journey. Consequently, the pollen tube has a dynamic gene expression program allowing it to continuously reset and be receptive to multiple pistil signals as it migrates through the pistil. Here, we review the studies, including several significant recent advances, that led to a better understanding of the multitude of cues generated by the pistil tissues to assist the pollen tube in delivering the sperm cells to the female gametophyte. We also highlight the outstanding questions, draw attention to opportunities created by recent advances and point to approaches that could be undertaken to unravel the molecular mechanisms underlying pollen tube–pistil interactions. WIREs Dev Biol 2012, 1:96–113. doi: 10.1002/wdev.6

This article is categorized under:

Plant Development > Gametophyte Development

Plant Development > Fertilization, Embryogenesis, and Seed Development

Plant Development > Inflorescence, Flower, and Fruit Development

Additional Supporting Information may be found in the online version of this article.

Movie1‐Palanivelu‐Tsukamoto.mov

Movie1‐Palanivelu‐Tsukamoto.mov
Birds of an ethnic feather? Ethnic identity homophily among college‐age friends
Authors: Syed Moin , Juan Mary Joyce D.
Published: November 2011

This study assessed the degree to which pairs of friends report similar levels of ethnic identity. College‐age friends (n= 107 pairs;N= 214 overall) completed measures of ethnic identity exploration and commitment, identity synthesis, relationship closeness, and frequency of talking to friends and family about ethnicity‐related issues. Participants were ethnically‐diverse and constituted three types of dyads: both ethnic minorities (n= 51), both White (n= 24), or mixed ethnic minority and White (n= 32). Overall, friends reported similar levels of ethnic identity exploration and commitment. The ethnic composition of the pair moderated similarity, with ethnic minority pairs showing greater similarity than the White and mixed pairs. Frequency of ethnicity‐related discussions with friends and family, but not relationship closeness, mediated the observed similarity for ethnic minority pairs. These findings suggest a level of ethnic identity homophily between ethnic minority friends that can be explained by interactional mechanisms.
Bursting bubble aerosols
Authors: Lhuissier H. , Villermaux E.
Published: November 2011

We depict and analyse the complete evolution of an air bubble formed in a water bulk, from the time it emerges at the liquid surface, up to its fragmentation into dispersed drops. To this end, experiments describing the drainage of the bubble cap film, its puncture and the resulting bursting dynamics determining the aerosol formation are conducted on tapwater bubbles. We discover that the mechanism of marginal pinching at the bubble foot and associated convection motions in the bubble cap, known as marginal regeneration, both drive the bubble cap drainage rate, and are responsible for its puncture. The resulting original film thickness $h$ evolution law in time, supplemented with considerations about the nucleation of holes piercing the film together culminate in a determination of the cap film thickness at bursting ${h}_{b} \propto {R}^{2} / \mathscr{L}$, where $R$ is the bubble cap radius of curvature, and $\mathscr{L}$ a length which we determine. Subsequent to a hole nucleation event, the cap bursting dynamics conditions the resulting spray. The latter depends both on the bubble shape prescribed by $R/ a$, where $a$ is the capillary length based on gravity, and on ${h}_{b} $. The mean drop size $\langle d\rangle \ensuremath{\sim} {R}^{3/ 8} \hspace{0.167em} { h}_{b}^{5/ 8} $, the number of drops generated per bubble $N\ensuremath{\sim} \mathop{ (R/ a)}\nolimits ^{2} \mathop{ (R/ {h}_{b} )}\nolimits ^{7/ 8} $ and the drop size distribution $P(d)$ are derived, comparing well with measurements. Combined with known bubble production rates over the ocean, our findings offer an adjustable parameter-free prediction for the aerosol flux and spray structure caused by bubble bursting in this precise context.
Effect of intensive counselling on the quality of dietary fats in pregnant women at high risk of gestational diabetes mellitus
Authors: Korpi-Hyövälti Eeva , Schwab Ursula , Laaksonen David E. , Linjama Hilpi , Heinonen Seppo , Niskanen Leo
Published: November 2011

As part of a feasibility study to prevent gestational diabetes mellitus (GDM), we evaluated the effect of an intensive dietary therapy on quality of diet, weight gain and birth weight in women at high risk of GDM. Women with risk factors for GDM (n 54) were randomly assigned from April 2005 to May 2006 to a lifestyle intervention group (n 27) including dietary advice six times during pregnancy or to a close follow-up group (n 27) in a community-based setting in Finland. Dietary intake was recorded three times during pregnancy using 4 d food records. The main outcome was the incidence of GDM. The secondary outcomes were the changes in nutrient intake, weight gain and birth weight. Overall, seventeen (65 %) women in the intervention group and eighteen (69 %) women in the close follow-up group returned all three food records. PUFA intake increased (P = 0·008) during pregnancy in the intervention as compared to the close follow-up group. There were no clear differences in the changes of saturated fat or fibre intake between the groups. Intensive dietary education resulted in a somewhat lower weight gain during pregnancy (P = 0·062) and higher birth weights of the infants (P = 0·047) without an effect on macrosomia as compared to the close follow-up group. Individualised counselling by a clinical nutritionist as part of a lifestyle intervention improved the quality of dietary fat intake in pregnant women at high risk of GDM.
Dissolved O2/Ar and other methods reveal rapid changes in productivity during a Lagrangian experiment in the Southern Ocean
Authors: Hamme Roberta C. , Cassar Nicolas , Lance Veronica P. , Vaillancourt Robert D. , Bender Michael L. , Strutton Peter G. , Moore Tommy S. , DeGrandpre Michael D. , Sabine Christopher L. , Ho David T. , Hargreaves Bruce R.
Published: November 2011

We use continuous and discrete measurements of the dissolved O2/Ar ratio in the mixed layer to investigate the dynamics of biological productivity during the Southern Ocean Gas Exchange Experiment in March and April 2008. Injections of SF6 defined two water masses (patches) that were followed for up to 2 weeks. In the first patch, dissolved O2/Ar was supersaturated, indicating net biological production of organic carbon. In the second patch, rapidly decreasing O2/Ar could only be reasonably explained if the mixed layer was experiencing a period of net heterotrophy. The observations rule out dominant contributions from vertical mixing, lateral dilution, or respiration in the ship's underway seawater supply lines. We also compare nine different estimates of net community, new, primary, or gross production made during the experiment. Net community and new production estimates agreed well in the first patch but disagreed in the second patch, both during an initial net heterotrophic period but also during the apparently autotrophic period at the end of the observations. Rapidly changing productivity during the second patch complicated the comparison of methods that integrate over daily and several week timescales. Primary productivity values from on‐deck 24 h 14C incubations and gross carbon production values from photosynthesis‐irradiance experiments were nearly identical even during highly dynamic periods of net heterotrophy, while gross oxygen production measurements were 3.5–4.2 times higher but with uncertainties in that ratio near ±2. These comparisons show that the photosynthesis‐irradiance experiments based on 1–2 h 14C incubations underestimated gross carbon production.
Wire number dependence of the implosion dynamics, stagnation, and radiation output of tungsten wire arrays at Z driver
Authors: Mazarakis Michael G. , Deeney Christopher E. , Stygar William A. , Douglas Melissa R. , Chittenden Jerry , Sinars Daniel B. , Cuneo Michael E. , Nash Thomas J. , Chandler Gordon A. , Keith Matzen M. , Porter John L. , Struve Kenneth W. , McDaniel Dillon H.
Published: November 2011

We report results of the experimental campaign, which studied the initiation, implosion dynamics, and radiation yield of tungsten wire arrays as a function of the wire number. The wire array dimensions and mass were those of interest for the Z-pinch driven Inertial Confinement Fusion (ICF) program. An optimization study of the x-ray emitted peak power, rise time, and full width at half maximum was effectuated by varying the wire number while keeping the total array mass constant and equal to ∼5.8 mg. The driver utilized was the ∼20-MA Z accelerator before refurbishment in its usual short pulse mode of 100 ns. We studied single arrays of 20-mm diameter and 1-cm height. The smaller wire number studied was 30 and the largest 600. It appears that 600 is the highest achievable wire number with present day’s technology. Radial and axial diagnostics were utilized including crystal monochromatic x-ray backlighter. An optimum wire number of ∼375 was observed which was very close to the routinely utilized 300 for the ICF program in Sandia.
Unusual temperature dependence of the magnetic anisotropy constant in barium ferrite BaFe12O19
Authors: Wang Jun , Zhao Fan , Wu Wei , Zhao Guo-Meng
Published: November 2011

We report magnetic hysteresis loops in a wide temperature range (4-700 K) for silica-coated barium ferrite BaFe12O19 nanoparticles. The saturation magnetization Ms and the first magnetic anisotropy constant K are determined simultaneously from the magnetic hysteresis loop using the law of approach to saturation. It is remarkable that K is linearly proportional to Ms and varies precisely with temperature as K(T) = K(0)[1 − (T/TC)1.58] in the whole temperature range below the Curie temperature TC (740 K). The unusual temperature dependence of the anisotropy constant and its linear relation with the saturation magnetization in BaFe12O19 are not predicted from the existing theoretical models.
Mapping the Arnold web with a graphic processing unit
Authors: Seibert A. , Denisov S. , Ponomarev A. V. , Hänggi P.
Published: November 2011

The Arnold diffusion constitutes a dynamical phenomenon which may occur in the phase space of a non-integrable Hamiltonian system whenever the number of the system degrees of freedom is M ≥ 3. The diffusion is mediated by a web-like structure of resonance channels, which penetrates the phase space and allows the system to explore the whole energy shell. The Arnold diffusion is a slow process; consequently, the mapping of the web presents a very time-consuming task. We demonstrate that the exploration of the Arnold web by use of a graphic processing unit-supercomputer can result in distinct speedups of two orders of magnitude as compared with standard CPU-based simulations.
The electronic spectrum of the previously unknown HAsO transient molecule
Authors: Grimminger Robert , Clouthier Dennis J.
Published: November 2011

The $\tilde A\,{}^1A^{\prime \prime} {\rm - }\tilde X\,{}^1A^\prime $ÃA′′1−X̃A′1 electronic spectrum of the jet-cooled transient molecule HAsO and its deuterated isotopologue has been observed for the first time by pulsed discharge jet laser spectroscopy. The techniques of laser-induced fluorescence and single vibronic level emission were employed to probe the electronic properties of the species. The bending and AsO stretching frequencies have been determined in both states. A rotational analysis of the $0_0^0$000 bands of both HAsO and DAsO has been completed and the following effective (r0) structures were derived: r″(HAs) = 1.576(3) Å, r″(AsO) = 1.8342(5) Å, and θ″ = 101.5(4)°; and r′(HAs) = 1.569(4) Å, r′(AsO) = 1.7509(9) Å, and θ′ = 93.1(10)°. In the rotational analysis, lines induced by axis-tilting were observed, and calculated spectra with an axis tilting angle of 3.0(5)° reproduced the intensity of these lines. The change in geometry on electronic excitation is similar to that observed for the molecule HPO, with an increase in the X–O bond length and a decrease in the HXO angle, but contrary to the predictions of the Walsh diagram for generic HAB triatomic molecules. Our ab initio calculations show that the correlation between orbital energy and bond angle changes upon electronic excitation, resulting in the atypical angle change.
Prospects for release-node quantum Monte Carlo
Authors: Tubman Norm M. , DuBois Jonathan L , Hood Randolph Q. , Alder Berni J.
Published: November 2011

We perform release-node quantum Monte Carlo simulations on the first row diatomic molecules in order to assess how accurately their ground-state energies can be obtained. An analysis of the fermion-boson energy difference is shown to be strongly dependent on the nuclear charge, Z, which in turn determines the growth of variance of the release-node energy. It is possible to use maximum entropy analysis to extrapolate to ground-state energies only for the low Z elements. For the higher Z dimers beyond boron, the error growth is too large to allow accurate data for long enough imaginary times. Within the limit of our statistics we were able to estimate, in atomic units, the ground-state energy of Li2 (−14.9947(1)), Be2 (−29.3367(7)), and B2(−49.410(2)).
Modeling the low-voltage regime of organic diodes: Origin of the ideality factor
Authors: Hyun Kim Chang , Yaghmazadeh Omid , Bonnassieux Yvan , Horowitz Gilles
Published: November 2011

This paper investigates the physics of single-layer organic diodes in the low-voltage regime. A simple analytical model is developed to describe the current-voltage characteristics of the device. At variance with what is often reported in the literature, the operating mechanism of the organic diode is closer to that of the p-n junction than that of the conventional Schottky diode. The influence of an exponential distribution of traps is also analyzed. Alongside a drastic reduction of the current at above-diffusion-potential regime, traps introduce a substantial ideality factor in the low-voltage current. Two-dimensional physically based simulations are carried out in order to ascertain the validity of our model. By including trap effects, device simulation could fairly fit the experimental data of the organic diodes made of vacuum-evaporated pentacene.
Comparison of P⋯D (D = P,N) with other noncovalent bonds in molecular aggregates
Authors: Adhikari Upendra , Scheiner Steve
Published: November 2011

All the minima on the potential energy surfaces of homotrimers and tetramers of PH3 are identified and analyzed as to the source of their stability. The same is done with mixed trimers in which one PH3 molecule is replaced by either NH3 or PFH2. The primary noncovalent attraction in all global minima is the BP⋯D (D = N,P) bond which is characterized by the transfer of charge from a lone pair of the donor D to a σ* B–P antibond of the partner molecule which is turned away from D, the same force earlier identified in the pertinent dimers. Examination of secondary minima reveals the presence of other weaker forces, some of which do not occur within the dimers. Examples of the latter include PH⋯P, NH⋯P, and PH⋯F H-bonds, and “reverse” H-bonds in which the source of the electron density is the smaller tail lobe of the donor lone pair. The global minima are cyclic structures in all cases, and exhibit some cooperativity, albeit to a small degree. The energy spacing of the oligomers is much smaller than that in the corresponding strongly H-bonded complexes such as the water trimer.
Chirality- and curvature-dependent bending stiffness of single layer graphene
Authors: Ma Tinghua , Li Bin , Chang Tienchong
Published: November 2011

An analytical molecular mechanics model is developed to relate the bending properties of a single layer graphene to its atomic structure. Explicit expression for the bending stiffness of graphene with arbitrary chirality is derived. The results show that the bending stiffness of graphene depends significantly on the chiral angle, especially when the bending curvature is large. Curvature can induce significant anisotropic bending properties of graphene. The present analytical results are helpful for understanding of chirality- and curvature-dependent bending properties of graphene and thus useful for potential applications of graphene as a bending component of nano devices.
Manipulating particle trajectories with phase-control in surface acoustic wave microfluidics
Authors: Orloff Nathan D. , Dennis Jaclyn R. , Cecchini Marco , Schonbrun Ethan , Rocas Eduard , Wang Yu , Novotny David , Simmonds Raymond W. , Moreland John , Takeuchi Ichiro , Booth James C.
Published: November 2011

We present a 91 MHz surface acoustic wave resonator with integrated microfluidics that includes a flow focus, an expansion region, and a binning region in order to manipulate particle trajectories. We demonstrate the ability to change the position of the acoustic nodes by varying the electronic phase of one of the transducers relative to the other in a pseudo-static manner. The measurements were performed at room temperature with 3 μm diameter latex beads dispersed in a water-based solution. We demonstrate the dependence of nodal position on pseudo-static phase and show simultaneous control of 9 bead streams with spatial control of −0.058 μm/deg ± 0.001 μm/deg. As a consequence of changing the position of bead streams perpendicular to their flow direction, we also show that the integrated acoustic-microfluidic device can be used to change the trajectory of a bead stream towards a selected bin with an angular control of 0.008 deg/deg ± 0.000(2) deg/deg.
Communication: Limitations of the stochastic quasi-steady-state approximation in open biochemical reaction networks
Authors: Thomas Philipp , Straube Arthur V. , Grima Ramon
Published: November 2011

It is commonly believed that, whenever timescale separation holds, the predictions of reduced chemical master equations obtained using the stochastic quasi-steady-state approximation are in very good agreement with the predictions of the full master equations. We use the linear noise approximation to obtain a simple formula for the relative error between the predictions of the two master equations for the Michaelis-Menten reaction with substrate input. The reduced approach is predicted to overestimate the variance of the substrate concentration fluctuations by as much as 30%. The theoretical results are validated by stochastic simulations using experimental parameter values for enzymes involved in proteolysis, gluconeogenesis, and fermentation.
Microsphere based microscope with optical super-resolution capability
Authors: Hao Xiang , Kuang Cuifang , Liu Xu , Zhang Haijun , Li Yanghui
Published: November 2011

We experimentally demonstrated that the microsphere can discern the details of the object whose sizes are below the conventional diffractive limit and such super-resolution capability can be reinforced if semi-immersing the corresponding microspheres in liquid droplet, producing a sharper contrast and a comparatively smaller magnification factor. The microsphere is considered as a channel that connects the near-field evanescent wave and the transmission one in far field. A conjecture based on this is proposed to explain the mechanism of super-resolution and the corresponding phenomenon.
Temperature-dependence and microscopic origin of low frequency 1/f noise in GaN/AlGaN high electron mobility transistors
Authors: Roy T. , Zhang E. X. , Puzyrev Y. S. , Shen X. , Fleetwood D. M. , Schrimpf R. D. , Koblmueller G. , Chu R. , Poblenz C. , Fichtenbaum N. , Suh C. S. , Mishra U. K. , Speck J. S. , Pantelides S. T.
Published: November 2011

We have performed low frequency 1/f noise measurements from 85 K to 450 K to investigate the energy distribution of defects in GaN/AlGaN high electron mobility transistors fabricated in three different processes. The noise is well described by the model of P. Dutta and P. M. Horn, Rev. Mod. Phys. 53, 497 (1981). A peak in the defect energy distribution is observed at ∼0.2 eV for all device types investigated, which we attribute to the reconfiguration of an oxygen DX-like center in AlGaN. An additional peak at an energy >1 eV is observed for devices grown under nitrogen-rich conditions, which we attribute to the reconfiguration energy of negatively charged nitrogen antisites.
Note: Scale-free center-of-mass displacement correlations in polymer films without topological constraints and momentum conservation
Authors: Wittmer J. P. , Schulmann N. , Polińska P. , Baschnagel J.
Published: November 2011

We present here computational work on the center-of-mass displacements in thin polymer films of finite width without topological constraints and without momentum conservation obtained using a well-known lattice Monte Carlo algorithm with chain lengths ranging up to N = 8192. Computing directly the center-of-mass displacement correlation function CN(t) allows to make manifest the existence of scale-free colored forces acting on a reference chain. As suggested by the scaling arguments put forward in a recent work on three-dimensional melts, we obtain a negative algebraic decay CN(t) ∼ −1/(N t) for times t ≪ TN with TN being the chain relaxation time. This implies a logarithmic correction to the related center-of-mass mean square-displacement hN(t) as has been checked directly.
Phylogeny of Polycentropodidae Ulmer, 1903 (Trichoptera:Annulipalpia:Psychomyioidea) inferred from larval, pupal and adult characters
Authors: Chamorro Maria Lourdes , Holzenthal Ralph W.
Published: November 2011

Phylogeny of Polycentropodidae Ulmer is inferred based on data from immature and adult stages. Larval information is unknown for 61% of the taxa included in this study. To understand the effects of including characters with large sets of missing data, three alternative datasets were analysed using parsimony and Bayesian methods. Five outgroup taxa, including the four families in Psychomyioidea and the single family in Hydropsychoidea, were used in all datasets. Monophyly of Polycentropodidae, as currently defined, was rejected and the monophyly of the three largest cosmopolitan genera, Polycentropus, Polyplectropus and Nyctiophylax, was not confirmed. Monophyly of Pseudoneureclipsinae, including the genera Antillopsyche and Pseudoneureclipsis, was supported in all analyses. The placement of Pseudoneureclipsis within Dipseudopsidae was rejected. Monophyly of Kambaitipsychinae was supported, but its placement within Polycentropodidae was not confirmed. Analyses were sensitive to either inclusion or exclusion of characters from immature stages. Based on the results of these analyses, the following taxonomic changes are established: Kambaitipsychidae, stat. nov. and Pseudoneureclipsidae, stat. nov. are elevated to family status. North American Polycentropus species originally described in either Plectrocnemia or Holocentropus are returned to their original combinations and North American species described in Polycentropus post-1944 are transferred to either Holocentropus or Plectrocnemia. The following new or reinstated combinations are proposed: Plectrocnemia albipuncta Banks, comb. rev.; Plectrocnemia aureola Banks, comb. rev.; Plectrocnemia cinerea (Hagen), comb. rev.; Plectrocnemia clinei Milne, comb. rev.; Plectrocnemia crassicornis (Walker), comb. rev.; Plectrocnemia jenula (Denning) comb. nov.; Plectrocnemia icula (Ross), comb. nov.; Plectrocnemia nascotia (Ross), comb. nov.; Plectrocnemia remota (Banks), comb. rev.; Plectrocnemia sabulosa (Leonard & Leonard), comb. nov.; Plectrocnemia smithae (Denning), comb. nov.; Plectrocnemia vigilatrix Navás, comb. rev.; Plectrocnemia weedi (Blickle & Morse), comb. nov.; Holocentropus chellus (Denning), comb. nov.; Holocentropus flavus Banks, comb. nov.; Holocentropus glacialis Ross, comb. rev.; Holocentropus grellus Milne, comb. rev.; Holocentropus interruptus Banks, comb. rev.; Holocentropus melanae Ross, comb. rev.; Holocentropus milaca (Etnier), comb. nov.; and Holocentropus picicornis (Stephens), comb. rev.
Developing a framework for understanding doctors' health access: a qualitative study of Australian GPs
Authors: Kay Margaret , Mitchell Geoffrey , Clavarino Alexandra , Frank Erica
Published: November 2011

Health access behaviours of doctors need to be understood if the profession is to adequately respond to concerns raised about doctors’ health. There has been limited investigation of these issues and most qualitative studies have focussed on doctors who have been seriously unwell. This research project was designed to explore doctors’ attitudes to health access and the barriers they experience using six independently facilitated focus groups (37 general practitioners) in Brisbane, Australia. Themes that emerged using inductive thematic analysis were grouped into three key categories. The findings challenge current representations of doctors’ health within the medical literature. Doctors in this study reported positive attitudes towards their own health care. Health access, however, was difficult because of the barriers they encountered. These barriers are described in detail revealing the rationale used by doctors seeking care. A framework of patient, provider and profession barrier domains is developed to enable a comparison between the health access barriers of the doctor and those experienced by the general community. The complexity is highlighted as the socio-cultural factors woven through these barrier domains are recognised. The potential for this framework to provide a structure for future interventions to enhance doctors’ health access is discussed.
Primary health care and equity: the case of lesbian, gay, bisexual, trans and intersex Australians
Authors: Rosenstreich Gabi , Comfort Jude , Martin Paul
Published: November 2011

The current period of health reform in Australia offers an opportunity for positive actions to be taken to address the significant challenges that lesbian, gay, bisexual, trans, intersex and other sexuality, sex and gender diverse (LGBTI) people face in the health system. This paper provides analysis of why this group should be considered a priority health group using a social determinants of health framework, which has, to date, largely been ignored within primary health care policy reform in Australia. Several key areas of the primary health care reform package are considered in relation to LGBTI health and well-being. Practical suggestions are provided as to how the primary health care sector could contribute to reducing the health inequities affecting LGBTI people. It is argued that care needs to be taken to ensure the reform process does not further marginalise this group.
Exploring discourses of equity, social justice and social determinants in Australian health care policy and planning documents
Authors: Young Janette , McGrath Richard
Published: November 2011

The Australian National Health Reform agenda includes aims to reduce health disadvantages and provide equitable access. However, this reform will be implemented through state and territory governments, and as such will be built on existing conceptualisations of health as a social justice concept (core to understandings of social determinants). A selection of state and territory health policy documents were analysed within a critical discourse framework focussing on their use of terms relating to social determinants. Analysis revealed that the understandings of social justice concepts vary across Australia and are generally apolitical, belying core concerns inherent in a social determinants understanding. Such differentiation bears recognition by reformers seeking to implement national consistency. This paper also considers how health professionals might become aware of their own cultural enmeshment in neo-liberal frameworks of understanding, recognising a social determinants framework as counter-cultural and hence requiring radical thinking.
Population health planning for health equity
Authors: Keleher Helen
Published: November 2011

Australia’s health reform documents make reference to the need to address health equity and strengthen population health planning. They make a stronger case about the need to address equity than policy documents that have preceded them. However, they do not make clear that health care is one of many determinants of health and equity, and that planning for health care, social care and social health outcomes are necessary for effectiveness. In other words, population health planning is much more than health care planning. Population health plans vary in their intent and design, depending on the population catchment for the plan, the remit of the organisations involved and the paradigms from which the plan is written. A stronger vision is necessary if population health plans are to affect health inequities. Comprehensive population planning is necessarily intersectoral with engagement across a wide cross-section of government department policies, portfolios and data sources, with a focus on the determinants of health and inequity, and a sound foundation of social values. This paper unpacks the elements of population health planning, the data sources that may be used and their interrogation in terms of the determinants of health, and presents core principles that distinguish population health planning from other types of planning to ensure that planning is comprehensive and able to be actioned.
Mechanical stochastic tug-of-war models cannot explain bidirectional lipid-droplet transport
Authors: Kunwar Ambarish , Tripathy Suvranta K. , Xu Jing , Mattson Michelle K. , Anand Preetha , Sigua Roby , Vershinin Michael , McKenney Richard J. , Yu Clare C. , Mogilner Alexander , Gross Steven P.
Published: November 2011

Intracellular transport via the microtubule motors kinesin and dynein plays an important role in maintaining cell structure and function. Often, multiple kinesin or dynein motors move the same cargo. Their collective function depends critically on the single motors’ detachment kinetics under load, which we experimentally measure here. This experimental constraint—combined with other experimentally determined parameters—is then incorporated into theoretical stochastic and mean-field models. Comparison of modeling results and in vitro data shows good agreement for the stochastic, but not mean-field, model. Many cargos in vivo move bidirectionally, frequently reversing course. Because both kinesin and dynein are present on the cargos, one popular hypothesis explaining the frequent reversals is that the opposite-polarity motors engage in unregulated stochastic tugs-of-war. Then, the cargos’ motion can be explained entirely by the outcome of these opposite-motor competitions. Here, we use fully calibrated stochastic and mean-field models to test the tug-of-war hypothesis. Neither model agrees well with our in vivo data, suggesting that, in addition to inevitable tugs-of-war between opposite motors, there is an additional level of regulation not included in the models.
Basic residues in the T-cell receptor ζ cytoplasmic domain mediate membrane association and modulate signaling
Authors: Zhang Hao , Cordoba Shaun-Paul , Dushek Omer , Anton van der Merwe P.
Published: November 2011

The T-cell receptor (TCR) consists of a TCRαβ heterodimer, a TCRζ homodimer, and CD3γε and CD3δε heterodimers. The precise mechanism of T-cell triggering following TCR ligand engagement remains elusive. Previous studies reported that the cytoplasmic tail of CD3ε binds to the plasma membrane through a basic residue-rich stretch (BRS) and proposed that dissociation from the membrane is required for phosphorylation thereof. In this report we show that BRS motifs within the cytoplasmic tail of TCRζ mediate association with the plasma membrane and that TCR engagement results in TCRζ dissociation from the membrane. This dissociation requires phosphorylation of the TCRζ immunoreceptor tyrosine-based activation motifs by lymphocyte cell-specific
protein
tyrosine kinase (Lck) but not ζ-chain–associated protein kinase 70 binding. Mutations of the TCRζ BRS motifs that disrupt this membrane association attenuate proximal and distal responses induced by TCR engagement. These mutations appear to alter the localization of TCRζ with respect to Lck as well as the mobility of the TCR complex. This study reveals that tyrosine phosphorylation of the TCRζ cytoplasmic domain regulates its association with the plasma membrane and highlights the functional importance of TCRζ BRS motifs.
Dynamic social networks promote cooperation in experiments with humans
Authors: Rand David G. , Arbesman Samuel , Christakis Nicholas A.
Published: November 2011

Human populations are both highly cooperative and highly organized. Human interactions are not random but rather are structured in social networks. Importantly, ties in these networks often are dynamic, changing in response to the behavior of one's social partners. This dynamic structure permits an important form of conditional action that has been explored theoretically but has received little empirical attention: People can respond to the cooperation and defection of those around them by making or breaking network links. Here, we present experimental evidence of the power of using strategic link formation and dissolution, and the network modification it entails, to stabilize cooperation in sizable groups. Our experiments explore large-scale cooperation, where subjects’ cooperative actions are equally beneficial to all those with whom they interact. Consistent with previous research, we find that cooperation decays over time when social networks are shuffled randomly every round or are fixed across all rounds. We also find that, when networks are dynamic but are updated only infrequently, cooperation again fails. However, when subjects can update their network connections frequently, we see a qualitatively different outcome: Cooperation is maintained at a high level through network rewiring. Subjects preferentially break links with defectors and form new links with cooperators, creating an incentive to cooperate and leading to substantial changes in network structure. Our experiments confirm the predictions of a set of evolutionary game theoretic models and demonstrate the important role that dynamic social networks can play in supporting large-scale human cooperation.