bluuebunny/crossref_metadata_2025 huggingface dataset:
On the proof of Kuranishi’s embedding theorem
Authors: Webster Sidney
Published: February 2017

We prove a local holomorphic embedding theorem for a formally integrable, strictly pseudoconvex CR manifold M with

\dim M = 2n − 1 ≧ 7

. This embedding is obtained as the limit of a sequence of approximate embeddings into complex

n

-space, which is constructed and shown to converge by the methods of Nash and Moser. The linearized problem is solved using the explicit integral operators constructed by Henkin. With estimates wich we have previously obtained for these operators, we show that if

M

is of class

C^m

, then it admits a

C^k

embedding provided

21 ≦ k

,

6k + 5n − 2 ≦ m

. Our argument is much shorter and simpler than previous arguments, which were based on the Neumann operator and carried out in the

C^∞

category.

Nous démontrons un théorème de plongement holomorphe local pour une variété CR M, intégrable et strictement pseudoconvexe, si

\dim M = 2n − 1 ≧ 7

. Ce plongement est obtenu comme limite d’une suite de plongements approximatifs dans l’espace

ℂ^n

. Nous construisons cette suite et démontrons sa convergence par les méthodes de Nash et Moser. Pour le problème linéarisé nous utilisons les opérateurs construits par Henkin et les bornes que nous avons obtenu auparavant. Si M est de classe

C^m

, le plongement est de classe

C^k

pourvu que

k ≧ 21

et

m ≧ 6k + 5n − 2

.
Direct numerical simulations of a high Karlovitz number laboratory premixed jet flame – an analysis of flame stretch and flame thickening
Authors: Wang Haiou , Hawkes Evatt R. , Chen Jacqueline H. , Zhou Bo , Li Zhongshan , Aldén Marcus
Published: February 2017

This article reports an analysis of the first detailed chemistry direct numerical simulation (DNS) of a high Karlovitz number laboratory premixed flame. The DNS results are first compared with those from laser-based diagnostics with good agreement. The subsequent analysis focuses on a detailed investigation of the flame area, its local thickness and their rates of change in isosurface following reference frames, quantities that are intimately connected. The net flame stretch is demonstrated to be a small residual of large competing terms: the positive tangential strain term and the negative curvature stretch term. The latter is found to be driven by flame speed–curvature correlations and dominated in net by low probability highly curved regions. Flame thickening is demonstrated to be substantial on average, while local regions of flame thinning are also observed. The rate of change of the flame thickness (as measured by the scalar gradient magnitude) is demonstrated, analogously to flame stretch, to be a competition between straining tending to increase gradients and flame speed variations in the normal direction tending to decrease them. The flame stretch and flame thickness analyses are connected by the observation that high positive tangential strain rate regions generally correspond with low curvature regions; these regions tend to be positively stretched in net and are relatively thinner compared with other regions. High curvature magnitude regions (both positive and negative) generally correspond with lower tangential strain; these regions are in net negatively stretched and thickened substantially.
Entry and exit flows in curved pipes
Authors: Ault Jesse T. , Rallabandi Bhargav , Shardt Orest , Chen Kevin K. , Stone Howard A.
Published: February 2017

Solutions are presented for both laminar developing flow in a curved pipe with a parabolic inlet velocity and laminar transitional flow downstream of a curved pipe into a straight outlet. Scalings and linearized analyses about appropriate base states are used to show that both cases obey the same governing equations and boundary conditions. In particular, the governing equations in the two cases are linearized about fully developed Poiseuille flow in cylindrical coordinates and about Dean’s velocity profile for curved pipe flow in toroidal coordinates respectively. Subsequently, we identify appropriate scalings of the axial coordinate and disturbance velocities that eliminate dependence on the Reynolds number $Re$ and dimensionless pipe curvature $\unicode[STIX]{x1D6FC}$ from the governing equations and boundary conditions in the limit of small $\unicode[STIX]{x1D6FC}$ and large $Re$. Direct numerical simulations confirm the scaling arguments and theoretical solutions for a range of $Re$ and $\unicode[STIX]{x1D6FC}$. Maximum values of the axial velocity, secondary velocity and pressure perturbations are determined along the curved pipe section. Results collapse when the scalings are applied, and the theoretical solutions are shown to be valid up to Dean numbers of $D=Re^{2}\unicode[STIX]{x1D6FC}=O(100)$. The developing flows are shown numerically and analytically to contain spatial oscillations. The numerically determined decay of the velocity perturbations is also used to determine entrance/development lengths for both flows, which are shown to scale linearly with the Reynolds number, but with a prefactor ${\sim}60\,\%$ larger than the textbook case of developing flow in a straight pipe.
Natural convection in a corrugated slot
Authors: Abtahi Arman , Floryan J. M.
Published: February 2017

Analysis of natural convection in a horizontal slot formed by two corrugated isothermal plates has been carried out. The analysis is limited to subcritical Rayleigh numbers$Ra$where no secondary motion takes place in the absence of corrugations. The corrugations have a sinusoidal form characterized by the wavenumber, the upper and lower amplitudes and the phase difference. The most intense convection occurs for corrugation wavelengths comparable to the slot height; it increases proportionally to$Ra$and proportionally to the corrugation height. Placement of corrugations on both plates may either significantly increase or decrease the convection depending on the phase difference between the upper and lower corrugations, with the strongest convection found for corrugations being in phase, i.e. a ‘wavy’ slot, and the weakest for corrugations being out of phase, i.e. a ‘converging–diverging’ slot. It is shown that the shear forces would always contribute to the corrugation build-up if erosion was allowed, while the role of pressure forces depends on the location of the corrugations as well as on the corrugation height and wavenumber, and the Rayleigh number. Placing corrugations on both plates results in the formation of a moment which attempts to change the relative position of the plates. There are two limiting positions, i.e. the ‘wavy’ slot and the ‘converging–diverging’ slot, with the latter being unstable. The system would end up in the ‘wavy’ slot configuration if relative movement of the two plates was allowed. The presence of corrugations affects the conductive heat flow and creates a convective heat flow. The conductive heat flow increases with the corrugation height as well as with the corrugation wavenumber; it is largest for short-wavelength corrugations. The convective heat flow is relevant only for wavenumbers of$O(1)$, it increases proportionally to$Ra^{3}$and proportionally to the second power of the corrugation height. Convection is qualitatively similar for all Prandtl numbers$Pr$, with its intensity increasing for smaller$Pr$and with the heat transfer augmentation increasing for larger$Pr$.
Impact of inclusive leadership on innovative work behavior: The role of psychological safety
Authors: Javed Basharat , Naqvi Sayyed Muhammad Mehdi Raza , Khan Abdul Karim , Arjoon Surendra , Tayyeb Hafiz Habib
Published: February 2017

The purpose of this study is to examine inclusive leadership as a predictor of innovative work behavior with the mediating role of psychological safety. Data were collected from supervisors–subordinates dyads working in textile industry in Pakistan. Our findings suggest that inclusive leadership is a positively related with innovative work behavior, and psychological safety mediates the effect of inclusive leadership on innovative work behavior. The leader–member exchange theory was used to build our theoretical model. We have also discussed theoretical and practical implications of our findings.
ON ∞-COMPLEX SYMMETRIC OPERATORS
Authors: CHŌ MUNEO , KO EUNGIL , LEE JI EUN
Published: February 2017

In this paper, we study spectral properties and local spectral properties of ∞-complex symmetric operatorsT. In particular, we prove that ifTis an ∞-complex symmetric operator, thenThas the decomposition property (δ) if and only ifTis decomposable. Moreover, we show that ifTandSare ∞-complex symmetric operators, then so isT⊗S.
Cost-effectiveness of computerized cognitive–behavioural therapy for the treatment of depression in primary care: findings from the Randomised Evaluation of the Effectiveness and Acceptability of Computerised Therapy (REEACT) trial
Authors: Duarte A. , Walker S. , Littlewood E. , Brabyn S. , Hewitt C. , Gilbody S. , Palmer S.
Published: February 2017

Background

Computerized cognitive–behavioural therapy (cCBT) forms a core component of stepped psychological care for depression. Existing evidence for cCBT has been informed by developer-led trials. This is the first study based on a large independent pragmatic trial to assess the cost-effectiveness of cCBT as an adjunct to usual general practitioner (GP) care compared with usual GP care alone and to establish the differential cost-effectiveness of a free-to-use cCBT programme (MoodGYM) in comparison with a commercial programme (Beating the Blues) in primary care.

Method

Costs were estimated from a healthcare perspective and outcomes measured using quality-adjusted life years (QALYs) over 2 years. The incremental cost-effectiveness of each cCBT programme was compared with usual GP care. Uncertainty was estimated using probabilistic sensitivity analysis and scenario analyses were performed to assess the robustness of results.

Results

Neither cCBT programme was found to be cost-effective compared with usual GP care alone. At a £20 000 per QALY threshold, usual GP care alone had the highest probability of being cost-effective (0.55) followed by MoodGYM (0.42) and Beating the Blues (0.04). Usual GP care alone was also the cost-effective intervention in the majority of scenario analyses. However, the magnitude of the differences in costs and QALYs between all groups appeared minor (and non-significant).

Conclusions

Technically supported cCBT programmes do not appear any more cost-effective than usual GP care alone. No cost-effective advantage of the commercially developed cCBT programme was evident compared with the free-to-use cCBT programme. Current UK practice recommendations for cCBT may need to be reconsidered in the light of the results.
Laser generated Richtmyer–Meshkov and Rayleigh–Taylor instabilities and nonlinear wave-vortex paradigm in turbulent mixing. II. Near-central region of Gaussian spot
Authors: Lugomer Stjepan
Published: February 2017

Laser-induced three-dimensional (3D) Richtmyer–Meshkov and Rayleigh–Taylor instabilities (RMI and RTI) on metal target in the semi-confined configuration (SCC) show the new paradigm of wave-vortex mixing. The SCC enables extended lifetime of a hot vapor/plasma plume above the target surface and the formation of fast multiple reshocks. This causes – in the central region (CR) of Gaussian-like spot – the evolution of RMI with the spike breakup (Lugomer, 2016b), while in the near CR causes the RMI followed by the RTI. The density interface is transformed into the large-scale broken irregular, quasi-periodic web, which comprises the RTI mushroom-shape spikes and the coherent wave-vortex structures such as the line solitons and vortex filaments. The intensity and direction of reshocks change (due to irregularity of the interface) and cause the formation of domains with the weak and the strong reshocks effects. The weak reshocks affect mushroom-shape spikes only slightly, while the strong ones cause their deformation and symmetry break, bubble collapse, and separation of the horizontal flow into vortex ribbons. Interaction of ribbons with spikes and bubbles causes the ribbon pinning, looping, winding, and formation of knotted and tangled structures. The line solitons, vortex filaments, and ribbons tend to organize into complex large-scale structures with the low wave-vortex turbulent mixing. They represent the new paradigm of 3D RMI and RTI in which the transition to the small-scale turbulent mixing does not appear.
Robust Positioning, Preliminary Orbit Determination, and Trajectory Prediction of Space Debris using In-Space Iterative-Bearing-Only Observations
Authors: Atashgah MA Amiri , Torkamani MR , Lavaei Abolfazl
Published: February 2017

This paper is concerned with the preliminary localisation, orbit determination and model-based path forecasting of space debris based on a robust procedure. In this work, an in-orbit observer utilises only relative bearing observations iteratively. To this end, the problem is first formulated in order to calculate the distance vector between the space debris and any orbiting observer. Afterwards, the obtained position vector is corrected through an Extended Kalman Filter (EKF) for shrinking the sensor and process errors and increasing robustness of the computations in the presence of uncertainties. After preliminary positioning, the related classical orbital elements are acquired via the predicted position and velocity vectors using a hybrid technique. Extensive simulations demonstrate the efficacy and robustness of the aforementioned method, and in particular it is verified that the proposed scheme is capable of producing a suitable solution for preliminary localisation and orbit determination of space debris based on the presented space-based observation, which is practical in phasing and chasing manoeuvres of any grabber space robot.
Unbiased Nonlinear Least Squares Estimations of Short-distance Equations
Authors: Xue Shuqiang , Yang Yuanxi
Published: February 2017

Nonlinear least squares estimations have been widely applied in positioning. However, nonlinear least squares estimations are generally biased. As the Gauss-Newton method has been widely applied to obtain a nonlinear least squares solution, we propose an iterative procedure for obtaining unbiased estimations with this method. The characteristics of the linearization error are discussed and a systematic error source of the linearization error needs to be removed to guarantee the unbiasedness. Both the geometrical condition and the statistical condition for unbiased nonlinear least squares estimations are revealed. It is shown that for long-distance observations of high precision, or for a positioning configuration with the lowest Geometric Dilution Of Precision (GDOP), the nonlinear least squares estimations tend to be unbiased; but for short-distance cases, the bias in the nonlinear least squares solution should be estimated to obtain unbiased values by removing the bias from the nonlinear least squares solution. The proposed results are verified by the Monte Carlo method and this shows that the bias in nonlinear least squares solution of short-distance distances cannot be ignored.
Soldiers as Victims at the ECCC: Exploring the Concept of ‘Civilian’ in Crimes against Humanity
Authors: KILLEAN RACHEL , DOWDS EITHNE , KRAMER AMANDA
Published: February 2017

The inspiration for this article came from a call foramicus curiaebriefs issued in April 2016 by the Office of the Co-Investigating Judges in the Extraordinary Chambers in the Courts of Cambodia (ECCC). The call sought guidance on: whether, under customary international law applicable between 1975 and 1979, an attack by a state or organization against members of its own armed forces may amount to an attack directed against a civilian population for the purpose of constituting a crime against humanity under Article 5 of the ECCC Law. We argue that customary international law justifies a finding that an attack on members of the armed forces can constitute crimes against humanity. In particular, the article focuses on the importance placed on the persecution element of crimes against humanity in the post-Second World War jurisprudence, and the broad interpretation of the term ‘civilian’. The article also examines the jurisprudence of contemporary international courts, finding that in some cases the courts have interpreted the term ‘civilian’ as incorporatinghors de combat. However, the International Criminal Tribunal for the former Yugoslavia (ICTY) and International Criminal Court (ICC) have moved towards a more restrictive interpretation of the term ‘civilian’, potentially excluding members of the armed forces. We argue that this move is regressive, and against the spirit in which the offence of crimes against humanity was created. The ECCC has an opportunity to counter this restrictive approach, thereby narrowing the protection gap which crimes against humanity were initially created to close.
A variational inequality arising from optimal exercise perpetual executive stock options
Authors: LAI XIN , CHEN XINFU , QIN CONG , YU WANGHUI
Published: February 2017

We investigate a degenerate parabolic variational inequality arising from optimal continuous exercise perpetual executive stock options. It is also shown in Qinet al.(Continuous-Exercise Model for American Call Options with Hedging Constraints, working paper, available at SSRN:http://dx.doi.org/10.2139/ssrn.2757541) that to make this problem non-trivial the stock's growth rate must be no smaller than the discount rate. Well-posedness of the problem is established in Laiet al.(2015, Mathematical analysis of a variational inequality modeling perpetual executive stock options, Euro. J. Appl. Math., 26 (2015), 193–213), Qinet al.(2015, Regularity free boundary arising from optimal continuous exercise perpetual executive stock options, Interfaces and Free Boundaries, 17 (2015), 69–92), Song & Yu (2011, A parabolic variational inequality related to the perpetual American executive stock options, Nonlinear Analysis, 74 (2011), 6583-6600) for the case when the underlying stock's expected return rate is smaller than the discount rate. In this paper, we consider the remaining case: the discount rate is bigger than the growth rate but no bigger than the return rate. The existence of a unique classical solution as well as a continuous and strictly decreasing free boundary is proved.
Eyetracking methodology in SCMC: A tool for empowering learning and teaching
Authors: Stickler Ursula , Shi Lijing
Published: February 2017

Computer-assisted language learning, or CALL, is an interdisciplinary area of research, positioned between science and social science, computing and education, linguistics and applied linguistics. This paper argues that by appropriating methods originating in some areas of CALL-related research, for example human-computer interaction (HCI) or psycholinguistics, the agenda of “attention-focus” research can be shifted from a cognitive perspective to a learner-centred approach; understanding online language learning and teaching spaces as mediated by technology; second/foreign language learning; and online teaching culture.

Taking a method that has traditionally been used within a positivist paradigm, the authors exemplify the potential of eyetracking to advance online language learning research – extending it in ways compatible with a sociocultural paradigm. This is evidenced by two pioneering studies in which an innovative combination of methods allows participants, whose gaze focus was recorded during synchronous computer-mediated communication (SCMC), to reflect back on their involvement. Eyetracking is combined with stimulated recall interviews that trigger deep reflection on learner and teacher strategies by directing participants’ recollections on their attention focus.

The rich, multifaceted results shown by this original and innovative use of eyetracking methods in a sociocultural framework suggest a way forward in researching online learning by integrating insider and outside views coherently and systematically.
Significance of the globally threatened Straw-headed Bulbul Pycnonotus zeylanicus populations in Singapore: a last straw for the species?
Authors: YONG DING LI , LIM KIM SENG , LIM KIM CHUAH , TAN TRIXIE , TEO SIYANG , HO HUA CHEW
Published: February 2017

The globally threatened Straw-headed Bulbul Pycnonotus zeylanicus is one of South-East Asia’s most imperilled songbirds due to the surging demand for the species in the regional bird trade. Recently uplisted from Vulnerable to Endangered, populations of the Straw-headed Bulbul have been extirpated from Java, Thailand and possibly Sumatra while those in Borneo and Peninsular Malaysia are in decline. Intriguingly, a significant yet rarely documented population of this species persists in Singapore. A major stronghold in Singapore is Ubin Island where a population is known since the 1920s. Using a long-term citizen science dataset rarely available for South-East Asian bird species, we determined the status and population trends of the Straw-headed Bulbul in Singapore over a 10–15 year period using Poisson regression models and standardised population indices. We found that the Straw-headed Bulbul population has increased at a rate of 3.69 ± 1.21% per annum on Ubin Island, while the population on Singapore Island remained stable (0.56% per annum) from 2000 to 2016. The population trends in Singapore contrast starkly with the declines reported elsewhere in South-East Asia. We estimated the population in Singapore to be a minimum of 202 individuals, distributed over multiple forest patches. The largest subpopulation of about 110 adult individuals persists on Ubin and which alone forms between 6.5–18.3% of the estimated global population in 2016. Given this unique situation, we recommend a number of conservation measures for the Straw-headed Bulbul to better protect the species, including: (1) an expansion of the protected area network in Singapore to include Ubin as a reserve, (2) the development of an endangered species management plan and, (3) the establishment of ex-situ conservation programmes in zoological institutions and wildlife centres in the region.
Knowledge of behavioural management principles amongst specialist paediatric dental practitioners in the United Kingdom
Authors: Coxon James , Hosey Marie Therese , Newton J. Tim
Published: February 2017

Background: Paediatric specialist dental practitioners are often faced with the challenge of disruptive behaviour or refusal to comply with treatment. Behaviour management skills are an essential component of their role. However, little is known of the confidence or competence of practitioners in these approaches. Aim: To identify paediatric dentists’ knowledge of behavioural management principles as applied to paediatric dentistry. Method: Postal questionnaire survey of all specialists in Paediatric Dentistry on the General Dental Council UK register (n = 234), using the Knowledge of Behavioural Principles as Applied to Children Questionnaire (KBPACQ; O'Dell, 1979) adapted for the dental setting. Information was also gathered on experience in using behavioural management techniques and demographics. Results: Responses were received from 105 practitioners (45%). Participants gave the correct answer, on average, to 38% of the items (range 0 to 75%). Conclusion: Knowledge of behavioural principles amongst paediatric dentists in the United Kingdom is poor, despite their widespread reported use of such techniques.
Determining Optimal Fluorescent Agent Concentrations in Dental Adhesive Resins for Imaging the Tooth/Restoration Interface
Authors: Bim Júnior Odair , Cebim Marco A. , Atta Maria T. , Machado Camila M. , Francisconi-dos-Rios Luciana F. , Wang Linda
Published: February 2017

Fluorescent dyes like Rhodamine B (RB) have been used to identify the spatial distribution of adhesive restorative materials in the tooth/restoration interface. Potential effects of the addition of RB to dental adhesives were addressed in the past, but no further information is available on how to determine suitable concentrations of RB in these bonding agents for imaging in the confocal laser scanning microscope. This study provides systematical strategies for adding RB to viscous dental adhesive resins, focusing on the determination of the lowest range of dye concentrations necessary to achieve an acceptable image of the dentin/adhesive interface. It was demonstrated that optimized images of the resin distribution in dentin can be produced with 0.1–0.02 mg/mL of RB in the (tested) adhesives. Our approaches took into account aspects related to the dye concentration, photophysical parameters in different host media, specimen composition and morphology to develop a rational use of the fluorescent agent with the resin-based materials. Information gained from this work can help optimize labeling methods using dispersions of low-molecular-weight dyes in different monomer blend systems.
Experimental Parameters Leading to Optimal Bilayers for Total Internal Reflection Fluorescence Microscopy Visualization
Authors: Mantil Elisabeth , Crippin Trinda , Ianoul Anatoli , Avis Tyler J.
Published: February 2017

Supported lipid bilayer systems were evaluated following various experimental procedures in an effort to determine their appropriateness for visualization using total internal reflection fluorescence (TIRF) microscopy. The incorporation and distribution of Texas Red® 1,2-dihexadecanoyl-sn-glycero-3-phosphoethanolamine (TR-DHPE) was studied when incorporated into bilayers of variable lipid composition using different forms of mechanical shearing. Results showed that 0.8 mol% TR-DHPE provides the most optimum TIRF images. At this concentration, a sufficient level of photostability can be achieved without an undesirable increase in TR-DHPE aggregates caused by excess probe molecules. Solutions composed of a 3:1 molar ratio of DOPC:DPPC with 0.8 mol% TR-DHPE produce bilayers that consistently display clear, distinct, rounded domains, whereas other lipid compositions did not. This optimum phase separation appears to be influenced by an increase in mechanical shearing during the vesicle formation process, when the lipid solutions were exposed to sonication and extrusion processes. The combination of a sonication and extrusion process also helped with eliminating the presence of TR-DHPE aggregates within the model membranes. It was also shown that bilayers formed on conditioned glass, placed on a slide, produced more highly detailed bilayers in which distinct lipid phase separation could be optimally visualized using TIRF microscopy.
Subjective value of the guarantees embedded in public cash-balance pension plans
Authors: TANG CHUN-HUA
Published: February 2017

Some public sectors provide cash-balance pension plans with guaranteed interest credits. We use the certainty-equivalence framework to derive the subjective value of the guarantee perceived by the participant. Numerical results show that in many scenarios the subjective value is lower than the cost of the guarantee derived by option pricing approaches, implying that public sectors potentially spend too much in providing the guarantee. However, the subjective value could be higher than the cost of the guarantee under some scenarios, depending on the participant's level of risk aversion, the feasibility of diversification, and so forth.
A Novel Approach for Pathway Analysis of GWAS Data Highlights Role of BMP Signaling and Muscle Cell Differentiation in Colorectal Cancer Susceptibility – Erratum
Authors: Mishra Aniket , MacGregor Stuart
Published: February 2017

The publishers regret to announce that the affiliation for the above paper was incorrectly inserted. The correct affiliation is below:

Aniket Mishra1, Genetics and Epidemiology of Colorectal Cancer Consortium (GECCO) and the Colorectal Cancer Family Registry (CCFR), and Stuart MacGregor1

1 Statistical Genetics, QIMR Berghofer Medical Research Institute, Brisbane, Queensland, Australia
What Proportion of River Nutrients Reaches the Open Sea?
Authors: Cook Terri
Published: February 2017

Results of the first geographically based estimates of river nutrient supply indicate that 75% of dissolved nitrogen and 80% of phosphorus reach the open ocean.
Seven Earth-Sized Planets Seen Whizzing Around One Cool Star
Authors: Wendel JoAnna
Published: February 2017

Although all the exoplanets orbit closer than Mercury does to our Sun, liquid water may persist on some of them because their star radiates so little heat.
Broad-scale lake expansion and flooding inundates essential wood bison habitat
Authors: Korosi Jennifer B. , Thienpont Joshua R. , Pisaric Michael F. J. , deMontigny Peter , Perreault Joelle T. , McDonald Jamylynn , Simpson Myrna J. , Armstrong Terry , Kokelj Steven V. , Smol John P. , Blais Jules M.
Published: February 2017

Understanding the interaction between the response of a complex ecosystem to climate change and the protection of vulnerable wildlife species is essential for conservation efforts. In the Northwest Territories (Canada), the recent movement of the Mackenzie wood bison herd (Bison bison athabascae) out of their designated territory has been postulated as a response to the loss of essential habitat following regional lake expansion. We show that the proportion of this landscape occupied by water doubled since 1986 and the timing of lake expansion corresponds to bison movements out of the Mackenzie Bison Sanctuary. Historical reconstructions using proxy data in dated sediment cores show that the scale of recent lake expansion is unmatched over at least the last several hundred years. We conclude that recent lake expansion represents a fundamental alteration of the structure and function of this ecosystem and its use by Mackenzie wood bison, in response to climate change.
Oxidation of F-actin controls the terminal steps of cytokinesis
Authors: Frémont Stéphane , Hammich Hussein , Bai Jian , Wioland Hugo , Klinkert Kerstin , Rocancourt Murielle , Kikuti Carlos , Stroebel David , Romet-Lemonne Guillaume , Pylypenko Olena , Houdusse Anne , Echard Arnaud
Published: February 2017

Cytokinetic abscission, the terminal step of cell division, crucially depends on the local constriction of ESCRT-III helices after cytoskeleton disassembly. While the microtubules of the intercellular bridge are cut by the ESCRT-associated enzyme Spastin, the mechanism that clears F-actin at the abscission site is unknown. Here we show that oxidation-mediated depolymerization of actin by the redox enzyme MICAL1 is key for ESCRT-III recruitment and successful abscission. MICAL1 is recruited to the abscission site by the Rab35 GTPase through a direct interaction with a flat three-helix domain found in MICAL1 C terminus. Mechanistically,in vitroassays on single actin filaments demonstrate that MICAL1 is activated by Rab35. Moreover, in our experimental conditions, MICAL1 does not act as a severing enzyme, as initially thought, but instead induces F-actin depolymerization from both ends. Our work reveals an unexpected role for oxidoreduction in triggering local actin depolymerization to control a fundamental step of cell division.
Product selectivity in plasmonic photocatalysis for carbon dioxide hydrogenation
Authors: Zhang Xiao , Li Xueqian , Zhang Du , Su Neil Qiang , Yang Weitao , Everitt Henry O. , Liu Jie
Published: February 2017

Photocatalysis has not found widespread industrial adoption, in spite of decades of active research, because the challenges associated with catalyst illumination and turnover outweigh the touted advantages of replacing heat with light. A demonstration that light can control product selectivity in complex chemical reactions could prove to be transformative. Here, we show how the recently demonstrated plasmonic behaviour of rhodium nanoparticles profoundly improves their already excellent catalytic properties by simultaneously reducing the activation energy and selectively producing a desired but kinetically unfavourable product for the important carbon dioxide hydrogenation reaction. Methane is almost exclusively produced when rhodium nanoparticles are mildly illuminated as hot electrons are injected into the anti-bonding orbital of a critical intermediate, while carbon monoxide and methane are equally produced without illumination. The reduced activation energy and super-linear dependence on light intensity cause the unheated photocatalytic methane production rate to exceed the thermocatalytic rate at 350 °C.
Direct observation of oxygen vacancy-driven structural and resistive phase transitions in La2/3Sr1/3MnO3
Authors: Yao Lide , Inkinen Sampo , van Dijken Sebastiaan
Published: February 2017

Resistive switching in transition metal oxides involves intricate physical and chemical behaviours with potential for non-volatile memory and memristive devices. Although oxygen vacancy migration is known to play a crucial role in resistive switching of oxides, an in-depth understanding of oxygen vacancy-driven effects requires direct imaging of atomic-scale dynamic processes and their real-time impact on resistance changes. Here we use in situ transmission electron microscopy to demonstrate reversible switching between three resistance states in epitaxial La2/3Sr1/3MnO3 films. Simultaneous high-resolution imaging and resistance probing indicate that the switching events are caused by the formation of uniform structural phases. Reversible horizontal migration of oxygen vacancies within the manganite film, driven by combined effects of Joule heating and bias voltage, predominantly triggers the structural and resistive transitions. Our findings open prospects for ionotronic devices based on dynamic control of physical properties in complex oxide nanostructures.
Demonstrating the potential of yttrium-doped barium zirconate electrolyte for high-performance fuel cells
Authors: Bae Kiho , Jang Dong Young , Choi Hyung Jong , Kim Donghwan , Hong Jongsup , Kim Byung-Kook , Lee Jong-Ho , Son Ji-Won , Shim Joon Hyung
Published: February 2017

In reducing the high operating temperatures (≥800 °C) of solid-oxide fuel cells, use of protonic ceramics as an alternative electrolyte material is attractive due to their high conductivity and low activation energy in a low-temperature regime (≤600 °C). Among many protonic ceramics, yttrium-doped barium zirconate has attracted attention due to its excellent chemical stability, which is the main issue in protonic-ceramic fuel cells. However, poor sinterability of yttrium-doped barium zirconate discourages its fabrication as a thin-film electrolyte and integration on porous anode supports, both of which are essential to achieve high performance. Here we fabricate a protonic-ceramic fuel cell using a thin-film-deposited yttrium-doped barium zirconate electrolyte with no impeding grain boundaries owing to the columnar structure tightly integrated with nanogranular cathode and nanoporous anode supports, which to the best of our knowledge exhibits a record high-power output of up to an order of magnitude higher than those of other reported barium zirconate-based fuel cells.
The critical role of point defects in improving the specific capacitance of δ-MnO2 nanosheets
Authors: Gao Peng , Metz Peter , Hey Trevyn , Gong Yuxuan , Liu Dawei , Edwards Doreen D. , Howe Jane Y. , Huang Rong , Misture Scott T.
Published: February 2017

3D porous nanostructures built from 2D δ-MnO2 nanosheets are an environmentally friendly and industrially scalable class of supercapacitor electrode material. While both the electrochemistry and defects of this material have been studied, the role of defects in improving the energy storage density of these materials has not been addressed. In this work, δ-MnO2 nanosheet assemblies with 150 m2 g−1 specific surface area are prepared by exfoliation of crystalline KxMnO2 and subsequent reassembly. Equilibration at different pH introduces intentional Mn vacancies into the nanosheets, increasing pseudocapacitance to over 300 F g−1, reducing charge transfer resistance as low as 3 Ω, and providing a 50% improvement in cycling stability. X-ray absorption spectroscopy and high-energy X-ray scattering demonstrate a correlation between the defect content and the improved electrochemical performance. The results show that Mn vacancies provide ion intercalation sites which concurrently improve specific capacitance, charge transfer resistance and cycling stability.
Dynamical Majorana edge modes in a broad class of topological mechanical systems
Authors: Prodan Emil , Dobiszewski Kyle , Kanwal Alokik , Palmieri John , Prodan Camelia
Published: February 2017

Mechanical systems can display topological characteristics similar to that of topological insulators. Here we report a large class of topological mechanical systems related to the BDI symmetry class. These are self-assembled chains of rigid bodies with an inversion centre and no reflection planes. The particle-hole symmetry characteristic to the BDI symmetry class stems from the distinct behaviour of the translational and rotational degrees of freedom under inversion. This and other generic properties led us to the remarkable conclusion that, by adjusting the gyration radius of the bodies, one can always simultaneously open a gap in the phonon spectrum, lock-in all the characteristic symmetries and generate a non-trivial topological invariant. The particle-hole symmetry occurs around a finite frequency, and hence we can witness a dynamical topological Majorana edge mode. Contrasting a floppy mode occurring at zero frequency, a dynamical edge mode can absorb and store mechanical energy, potentially opening new applications of topological mechanics.
Flower-like superstructures of AIE-active tetraphenylethylene through solvophobic controlled self-assembly
Authors: Salimimarand Mina , La Duong Duc , Kobaisi Mohammad Al , Bhosale Sheshanath V.
Published: February 2017

The development of well-organized structures with high luminescent properties in the solid and aggregated states is of both scientific and technological interest due to their applications in nanotechnology. In this paper we described the synthesis of amphiphilic and dumbbell shaped AIE-active tetraphenylethylene (TPE) derivatives and studied their self-assembly with solvophobic control. Interestingly, both TPE derivatives form a 3D flower-shape supramolecular structure from THF/water solutions at varying water fractions. SEM microscopy was used to visualise step-wise growth of flower-shape assembly. TPE derivatives also show good mechanochromic properties which can be observed in the process of grinding, fuming and heating. These TPE derivative self-assemblies are formed due to two main important properties: (i) the TPE-core along with alkyl chains, optimizing the dispersive interactions within a construct, and (ii) amide-linkage through molecular recognition. We believe such arrangements prevent crystallization and favour the directional growth of flower-shape nanostructures in a 3D fashion.
Advanced-Retarded Differential Equations in Quantum Photonic Systems
Authors: Alvarez-Rodriguez Unai , Perez-Leija Armando , Egusquiza Iñigo L. , Gräfe Markus , Sanz Mikel , Lamata Lucas , Szameit Alexander , Solano Enrique
Published: February 2017

We propose the realization of photonic circuits whose dynamics is governed by advanced-retarded differential equations. Beyond their mathematical interest, these photonic configurations enable the implementation of quantum feedback and feedforward without requiring any intermediate measurement. We show how this protocol can be applied to implement interesting delay effects in the quantum regime, as well as in the classical limit. Our results elucidate the potential of the protocol as a promising route towards integrated quantum control systems on a chip.
Cartilage-like electrostatic stiffening of responsive cryogel scaffolds
Authors: Offeddu G. S. , Mela I. , Jeggle P. , Henderson R. M. , Smoukov S. K. , Oyen M. L.
Published: February 2017

Cartilage is a structural tissue with unique mechanical properties deriving from its electrically-charged porous structure. Traditional three-dimensional environments for the culture of cells fail to display the complex physical response displayed by the natural tissue. In this work, the reproduction of the charged environment found in cartilage is achieved using polyelectrolyte hydrogels based on polyvinyl alcohol and polyacrylic acid. The mechanical response and morphology of microporous physically-crosslinked cryogels are compared to those of heat-treated chemical gels made from the same polymers, as a result of pH-dependent swelling. In contrast to the heat-treated chemically-crosslinked gels, the elastic modulus of the physical cryogels was found to increase with charge activation and swelling, explained by the occurrence of electrostatic stiffening of the polymer chains at large charge densities. At the same time, the permeability of both materials to fluid flow was impaired by the presence of electric charges. This cartilage-like mechanical behavior displayed by responsive cryogels can be reproduced in other polyelectrolyte hydrogel systems to fabricate biomimetic cellular scaffolds for the repair of the tissue.
α-synuclein transfer through tunneling nanotubes occurs in SH-SY5Y cells and primary brain pericytes from Parkinson’s disease patients
Authors: Dieriks Birger Victor , Park Thomas I-H. , Fourie Chantelle , Faull Richard L. M. , Dragunow Mike , Curtis Maurice A.
Published: February 2017

Parkinson’s disease (PD) is characterized by the presence of inclusions known as Lewy bodies, which mainly consist of α-synuclein (α-syn) aggregates. There is growing evidence that α-syn self-propagates in non-neuronal cells, thereby contributing to the progression and spread of PD pathology in the brain. Tunneling nanotubes (TNTs) are long, thin, F-actin-based membranous channels that connect cells and have been proposed to act as conduits for α-syn transfer between cells. SH-SY5Y cells and primary human brain pericytes, derived from postmortem PD brains, frequently form TNTs that allow α-syn transfer and long-distance electrical coupling between cells. Pericytes in situ contain α-syn precipitates like those seen in neurons. Exchange through TNTs was rapid, but dependent on the size of the protein. Proteins were able to spread throughout a network of cells connected by TNTs. Transfer through TNTs was not restricted to α-syn; fluorescent control proteins and labeled membrane were also exchanged through TNTs. Most importantly the formation of TNTs and transfer continued during mitosis. Together, our results provide a detailed description of TNTs in SH-SY5Y cells and human brain PD pericytes, demonstrating their role in α-syn transfer and further emphasize the importance that non-neuronal cells, such as pericytes play in disease progression.
Glycan-independent binding and internalization of human IgM to FCMR, its cognate cellular receptor
Authors: Lloyd Katy A. , Wang Jiabin , Urban Britta C. , Czajkowsky Daniel M. , Pleass Richard J.
Published: February 2017

IgM is the first antibody to be produced in immune responses and plays an important role in the neutralization of bacteria and viruses. Human IgM is heavily glycosylated, featuring five N-linked glycan sites on the μ chain and one on the J-chain. Glycosylation of IgG is known to modulate the effector functions of Fcγ receptors. In contrast, little is known about the effect of glycosylation on IgM binding to the human Fcμ receptor (hFCMR). In this study, we identify the Cμ4 domain of IgM as the target of hFCMR, and show that binding and internalization of IgM by hFCMR is glycan-independent. We generated a homology-based structure for hFCMR and used molecular dynamic simulations to show how this interaction with IgM may occur. Finally, we reveal an inhibitory function for IgM in the proliferation of T cells.
Establishment of planar cell polarity is coupled to regional cell cycle exit and cell differentiation in the mouse utricle
Authors: Yang Xiaoyu , Qian Xiaoqing , Ma Rui , Wang Xinwei , Yang Juanmei , Luo Wenwei , Chen Ping , Chi Fanglu , Ren Dongdong
Published: February 2017

Sensory hair cells are coordinately oriented within each inner ear sensory organ to exhibit a particular form of planar cell polarity (PCP) necessary for mechanotransduction. However, the developmental events associated with establishing PCP in the vestibule are unclear, hindering data interpretation and employment of the vestibule for PCP studies. Herein, we investigated PCP of the mouse vestibular organs. We further characterised cell cycle exit, cell differentiation, and PCP establishment in the utricle. We found that hair cells formed first in the striolar and medial extrastriolar (MES) regions of the utricle at embryonic day 11.5 (E11.5), while cells in the lateral extrastriolar region (LES) mostly formed at E13.5. Cell differentiation was initiated in the striolar region, which expanded first toward the MES, then to the LES by E15.5. The polarity of hair cells was established at birth along a putative line of polarity reversal (LPR), lateral to the striolar region. Core PCP protein Vangl2 emerged in the cell boundaries since E11.5, while cell intrinsic polarity protein Gαi3 appeared at E12.5, then polarized to the bare zone of individual hair cell at E13.5. These findings provide a blueprint of the developmental events associated with establishing PCP in the utricle.
High-resolution imaging of living mammalian cells bound by nanobeads-connected antibodies in a medium using scanning electron-assisted dielectric microscopy
Authors: Okada Tomoko , Ogura Toshihiko
Published: February 2017

Nanometre-scale-resolution imaging technologies for liquid-phase specimens are indispensable tools in various scientific fields. In biology, observing untreated living cells in a medium is essential for analysing cellular functions. However, nanoparticles that bind living cells in a medium are hard to detect directly using traditional optical or electron microscopy. Therefore, we previously developed a novel scanning electron-assisted dielectric microscope (SE-ADM) capable of nanoscale observations. This method enables observation of intact cells in aqueous conditions. Here, we use this SE-ADM system to clearly observe antibody-binding nanobeads in liquid-phase. We also report the successful direct detection of streptavidin-conjugated nanobeads binding to untreated cells in a medium via a biotin-conjugated anti-CD44 antibody. Our system is capable of obtaining clear images of cellular organelles and beads on the cells at the same time. The direct observation of living cells with nanoparticles in a medium allowed by our system may contribute the development of carriers for drug delivery systems (DDS).
Suppression of Fusarium wilt of cucumber by ammonia gas fumigation via reduction of Fusarium population in the field
Authors: Zhao Jun , Mei Zhong , Zhang Xu , Xue Chao , Zhang Chenzhi , Ma Tengfei , Zhang Shusheng
Published: February 2017

Cucumber plants subjected to consecutive monoculture for 9 years were found to suffer from severe Fusarium wilt disease, caused by the soil-borne fungus Fusarium oxysporum f. sp. Cucumerinum J. H. Owen. In the present study, greenhouse experiments were performed to evaluate the influence of ammonia gas fumigation on Fusarium wilt suppression, fungal abundance and fungal community composition. Results showed that ammonia gas fumigation remarkably reduced disease incidence from 80% to 27%, resulting in a four-fold increase in yield, compared to the control. Total fungal abundance declined dramatically after fumigation and reached the lowest level at day 32, at 243 times lower than the control. Moreover, fumigation significantly increased soil fungal diversity, though it also decreased considerably coinciding with cucumber growth. Fumigation also significantly altered soil fungal community composition, relative to the control. Fusarium was strongly inhibited by fumigation in both relative abundance (3.8 times lower) and targeted quantification (a decrease of 167 fold). Collectively, the application of ammonia gas fumigation to control Fusarium wilt of cucumber resulted in a re-assembly of the fungal community to resemble that of a non-disease conducive consortium. Additional strategies, such as bioorganic fertilizer application, may still be required to develop sustainable disease suppression following fumigation.