bluuebunny/crossref_metadata_2025 huggingface dataset:
Optical loss compensation in a bulk left-handed metamaterial by the gain in quantum dots
Authors: Dong Zheng-Gao , Liu Hui , Li Tao , Zhu Zhi-Hong , Wang Shu-Ming , Cao Jing-Xiao , Zhu Shi-Ning , Zhang X.
Published: February 2010

A bulk left-handed metamaterial with fishnet structure is investigated to show the optical loss compensation via surface plasmon amplification with the assistance of the gain medium of PbS quantum dots. Simultaneously negative permittivity and permeability are confirmed at the telecommunication wavelength (1.5 μm) by the retrieval of the effective electromagnetic property. The dependence of enhanced transmission on the gain coefficient, as well as on the propagation layers, demonstrates that ultralow loss is feasible in bulk left-handed metamaterials.
STAT3 is a substrate of SYK tyrosine kinase in B-lineage leukemia/lymphoma cells exposed to oxidative stress
Authors: Uckun Fatih M. , Qazi Sanjive , Ma Hong , Tuel-Ahlgren Lisa , Ozer Zahide
Published: January 2010

We provide unprecedented genetic and biochemical evidence that the antiapoptotic transcription factor STAT3 serves as a substrate for SYK tyrosine kinase both in vitro and in vivo. Induction of SYK in an ecdysone-inducible mammalian expression system results in STAT3 activation, as documented by tyrosine phosphorylation and nuclear translocation of STAT3, as well as amplified expression of several STAT3 target genes. STAT3 activation after oxidative stress (OS) is strongly diminished in DT40 chicken B-lineage lymphoma cells rendered SYK-deficient by targeted disruption of thesykgene. Introduction of a wild-type, C-terminal or N-terminal SH2 domain-mutated, but not a kinase domain-mutated,sykgene into SYK-deficient DT40 cells restores OS-induced enhancement of STAT-3 activity. Thus, SYK plays an important and indispensable role in OS-induced STAT3 activation and its catalytic SH1 domain is critical for this previously unknown regulatory function. These results provide evidence for the existence of a novel mode of cytokine-independent cross-talk that operates between SYK and STAT3 pathways and regulates apoptosis during OS. We further provide experimental evidence that SYK is capable of associating with and phosphorylating STAT3 in human B-lineage leukemia/lymphoma cells challenged with OS. In agreement with a prerequisite role of SYK in OS-induced STAT3 activation, OS does not induce tyrosine phosphorylation of STAT3 in SYK-deficient human proB leukemia cells. Notably, inhibition of SYK with a small molecule drug candidate prevents OS-induced activation of STAT3 and overcomes the resistance of human B-lineage leukemia/lymphoma cells to OS-induced apoptosis.
Switchable hardening of a ferromagnet at fixed temperature
Authors: Silevitch D. M. , Aeppli G. , Rosenbaum T. F.
Published: January 2010

The intended use of a magnetic material, from information storage to power conversion, depends crucially on its domain structure, traditionally crafted during materials synthesis. By contrast, we show that an external magnetic field, applied transverse to the preferred magnetization of a model disordered uniaxial ferromagnet, is an isothermal regulator of domain pinning. At elevated temperatures, near the transition into the paramagnet, modest transverse fields increase the pinning, stabilize the domain structure, and harden the magnet, until a point where the field induces quantum tunneling of the domain walls and softens the magnet. At low temperatures, tunneling completely dominates the domain dynamics and provides an interpretation of the quantum phase transition in highly disordered magnets as a localization/delocalization transition for domain walls. While the energy scales of the rare earth ferromagnet studied here restrict the effects to cryogenic temperatures, the principles discovered are general and should be applicable to existing classes of highly anisotropic ferromagnets with ordering at room temperature or above.
Competition between native topology and nonnative interactions in simple and complex folding kinetics of natural and designed proteins
Authors: Zhang Zhuqing , Chan Hue Sun
Published: January 2010

We compared folding properties of designed protein Top7 and natural protein S6 by using coarse-grained chain models with a mainly native-centric construct that accounted also for nonnative hydrophobic interactions and desolvation barriers. Top7 and S6 have similar secondary structure elements and are approximately equal in length and hydrophobic composition. Yet their experimental folding kinetics were drastically different. Consistent with experiment, our simulated folding chevron arm for Top7 exhibited a severe rollover, whereas that for S6 was essentially linear, and Top7 model kinetic relaxation was multiphasic under strongly folding conditions. The peculiar behavior of Top7 was associated with several classes of kinetic traps in our model. Significantly, the amino acid residues participating in nonnative interactions in trapped conformations in our Top7 model overlapped with those deduced experimentally. These affirmations suggest that the simple ingredients of native topology plus sequence-dependent nonnative interactions are sufficient to account for some key features of protein folding kinetics. Notably, when nonnative interactions were absent in the model, Top7 chevron rollover was not correctly predicted. In contrast, nonnative interactions had little effect on the quasi linearity of the model folding chevron arm for S6. This intriguing distinction indicates that folding cooperativity is governed by a subtle interplay between the sequence-dependent driving forces for native topology and the locations of favorable nonnative interactions entailed by the same sequence. Constructed with a capability to mimic this interplay, our simple modeling approach should be useful in general for assessing a designed sequence’s potential to fold cooperatively.
Perceived normative pressure and majority adolescents’ implicit and explicit attitudes towards immigrants
Authors: Mähönen Tuuli Anna , Jasinskaja‐Lahti Inga , Liebkind Karmela , Finell Eerika
Published: January 2010

The aim of the present study was to examine if perceived normative pressure (i.e., perception of the normative expectations of family and friends regarding one's intergroup attitudes) had a direct impact on majority youth's (N = 93) explicit attitudes and moderated the relationship between their implicit (measured with the ST‐IAT) and explicit attitudes towards Russian immigrants in Finland. The results indicated that normative pressure is positively associated with the explicit attitudes of adolescents, and that the implicit attitudes of the adolescents towards immigrants surface on the explicit level only when they do not perceive a normative pressure to hold positive intergroup attitudes. More specifically, when there is no normative pressure, the explicit attitudes of youth are, at best, neutral, and reflect their implicit attitudes. In contrast, when normative pressure is perceived to be high, the level of explicit attitudes is generally more positive, and the expression of explicit attitudes is not determined by implicit attitudes. The effects of age, sex, quality of past intergroup contact experiences, and intergroup anxiety were controlled for in the analysis. The findings highlight the importance of taking normative pressure into consideration when studying socially sensitive ethnic attitudes among adolescents.
Regulatory focus and attitudes to migrants
Authors: Whelan Jennifer , Laham Simon M. , Peters Kim , Boldero Jennifer , Kashima Yoshihisa
Published: January 2010

In two studies we examined the role of two regulatory foci (i.e., prevention and promotion) in predicting Australian's attitudes to different types of migrants. According to regulatory focus theory, promotion‐focused self‐regulation is concerned with nurturance and accomplishment needs and involves the pursuit of wishes and aspirations. As such, it results in sensitivity to positive outcomes and to relative pleasure from gains. On the other hand, prevention‐focused self‐regulation is concerned with security needs and is directed at meeting duties and obligations. As such, it results in sensitivity to negative outcome and relative pain from losses. In Study 1, as predicted, the extent of promotion focus (i.e., a concern with accomplishment and the pursuit of ideals) predicted more positive attitudes to culturally similar and economically beneficial migrants, whereas the extent of prevention focus (i.e., concern with security and meeting obligations) predicted more negative attitudes to migrants who are culturally dissimilar. In Study 2 we replicated and extended these findings, showing that the extent of promotion focus and a lack of concern with threats predicted positive attitudes to both culturally similar and economically beneficial migrants, which, in the case of the latter group, was mediated by a focus on the benefits these migrants provide. In the case of culturally dissimilar migrants, the extent of promotion focus and a concern with gains predicted more positive attitudes. However, for economically less beneficial migrants, neither the extent of promotion nor prevention focus was a predictor. Only lower concerns with threat predicted more positive attitudes to this migrant group. The results are discussed with respect to other determinants of attitudes to migrants and the implications for migration and asylum‐seeker policy.
Group‐based problem‐solving therapy in self‐poisoning females: A pilot study
Authors: Bannan Noreen
Published: January 2010

Aims:The treatment of suicidal behaviour remains limited in efficacy. This pilot study assessed the effectiveness of a time‐limited, group‐based problem‐solving therapy intervention compared with a treatment as usual control group, in females who self‐poison.Method: A total of 18 clients were equally randomised to treatment or control groups. All clients were assessed using standardised questionnaires for depression, hopelessness, suicidal ideation and social problem‐solving skills, at pre‐treatment, post‐treatment and two months follow‐up.Results:The treatment group experienced significant reductions in levels of depression, hopelessness, suicidal ideation and improvements in self‐assessed social problem‐solving skills. Improvements in mental health and aspects of self‐assessed problem‐solving skills for the treatment group continued to be evident at two months follow‐up. The control group did not change significantly over time on mental health measures or social problem solving abilities.Conclusion:Although limited by small sample size, the results suggest that group‐based problem‐solving therapy is effective in the management of deliberate self‐poisoning. This paper is a unique contribution in that it examines the implementation of problem solving therapy with a homogenous population and in a group format. Methodological concerns and directions for future research are discussed.
Therapists' experiences of personal therapy: A descriptive phenomenological study
Authors: Oteiza Vicky
Published: January 2010

Aim: To consider therapists' descriptive accounts of their experiences of personal therapy. Method: The methodology employed was qualitative, using data obtained from individual semi‐structured interviews. Ten Spanish psychotherapists were interviewed about their experiences of personal therapy. Findings: In a systematic thematic analysis of the interview transcripts, six emergent themes were identified: different approaches to personal therapy; time in therapy; approach to choosing personal therapist; experiences of personal therapy; contribution of personal therapy to therapists' professional development, and contribution of personal therapy to therapists' affective development. These findings are consistent with previous research. Conclusion: The findings indicated that participants' experiences of personal therapy were positive. Alternative approaches for personal development are considered.
Where do counsellors in private practice receive their support? A pilot study
Authors: Savic-Jabrow Pamela Catherine
Published: January 2010

Background: Previous research suggests that independent practitioners should ensure that they attend to self‐care, and the requirement for self‐care is written into ethical practice requirements. Aims: To explore whether or how counsellors in private practice received support, and if so from where. Method: A survey questionnaire containing 29 questions was sent to 525 recipients. Results: 31 questionnaires were completed. The results from these questionnaires indicated that support was primarily received through supervision. Discussion: The support needs of private practitioners are discussed in the context of a very low response rate. The researcher considers factors that might have led to this response rate, as well as reflecting on the study design.
Counsellors' perspectives on self‐harm and the role of the therapeutic relationship for working with clients who self‐harm
Authors: Long Maggie , Jenkins Mary
Published: January 2010

Aims: To gain insight into counsellors' experiences of and ideas about self‐harm, and to develop understanding of relational depth when working with clients who self‐harm. Method: A qualitative exploration of counsellors' perspectives on working with people who self‐harm. The research proposal gained approval from the University Ethics Committee. Data were collected from a sample of counsellors who have experience of working with people who self‐harm (n = 8) using tape‐recorded interviews. Grounded Theory was used for analysis. Findings: Two major categories emerged from the findings: (i) the activity of self‐harm; (ii) the therapeutic relationship with people who self‐harm. These categories and sub‐categories were integrated to form the core category. Implications: Counsellors have a valuable role to play in the lives of people who self‐harm, by embodying confidentiality and so facilitating a sense of trust, by opening minds through acceptance, and by expanding knowledge through participation in research. Conclusions: In order to effectively accompany clients from a life of self‐harm to a life of self‐healing, counsellors must be aware of and responsive to the many concepts underpinning the emergent categories of the research.
Enclosure shape influences cue competition effects and goal location learning
Authors: Wilson Paul N. , Alexander Tim
Published: January 2010

In virtual-environment spatial-learning procedures, Experiment 1 investigated blocking of learning about distal landmarks beyond the walls of an enclosure following preliminary training to find a goal using local landmarks within the enclosure. Separate sets of blocking and control groups searched within enclosures that, in plan view, formed either a square or a circle. Blocking was apparent when training and testing occurred in the circular but not the square enclosure. In Experiment 2, preliminary training to find a goal using local landmarks blocked spatial learning based on a circular enclosure divided into four differently coloured sections. The results are discussed in relation to theories of incidental versus error-correcting learning linked to different types of spatial cue.
Are Transposition Effects Specific to Letters?
Authors: García-Orza Javier , Perea Manuel , Muñoz Samara
Published: January 2010

Recent research has consistently shown that pseudowords created by transposing two letters are perceptually similar to their corresponding base words (e.g., jugde–judge). In the framework of the overlap model (Gomez, Ratcliff, & Perea, 2008), this effect is due to a noisy process in the localization of the “objects” (e.g., letters, kana syllables). In the present study, we examine whether this effect is specific to letter strings or whether it also occurs with other “objects” (namely, digits, symbols, and pseudoletters). To that end, we conducted a series of five masked priming experiments using the same–different task. Results showed robust effects of transposition for all objects, except for pseudoletters. This is consistent with the view that locations of familiar objects (i.e., letters, numbers, and symbols) can be best understood as distributions along a dimension rather than as precise points.
Force calibration in lateral force microscopy: a review of the experimental methods
Authors: Munz Martin
Published: January 2010

Lateral force microscopy (LFM) is a variation of atomic/scanning force microscopy (AFM/SFM). It relies on the torsional deformation of the AFM cantilever that results from the lateral forces acting between tip and sample surface. LFM allows imaging of heterogeneities in materials, thin films or monolayers at high spatial resolution. Furthermore, LFM is increasingly used to study the frictional properties of nanostructures and nanoparticulates. An impediment for the quantification of lateral forces in AFM, however, is the lack of reliable and established calibration methods. A widespread acceptance of LFM requires quantification coupled with a solid understanding of the sources of uncertainty. This paper reviews the available experimental calibration methods and identifies particularly promising approaches.
Super-low-k SiOCH film (k = 1.9) with extremely high water resistance and thermal stability formed by neutral-beam-enhanced CVD
Authors: Yasuhara Shigeo , Sasaki Toru , Shimayama Tsutomu , Tajima Kunitoshi , Yano Hisashi , Kadomura Shingo , Yoshimaru Masaki , Matsunaga Noriaki , Samukawa Seiji
Published: January 2010

We developed a neutral-beam-enhanced method of chemical vapour deposition (NBECVD) to obtain a lower dielectric constant for the SiOCH interlayer dielectric film while maintaining a reasonable modulus. We achieved a higher deposition rate than that with the precursor of dimethyl-dimethoxy-silane (DMDMOS) we previously reported on by using Ar NBECVD with a precursor of dimethoxy-tetramethyl-disiloxine (DMOTMDS). This is because of the high absorption coefficient of DMOTMDS. Ar NBECVD with DMOTMDS also achieved a much lower dielectric constant than the conventional PECVD film, because this method avoids the precursor dissociation that causes low dielectric film with many linear Si–O structures. We obtained a k value of 1.9 for the super-low-k SiOCH film with an extremely water resistant, and very thermally stable and integration-possible modulus (>4 GPa) by controlling the bias power.
Dimensional analysis of detrimental ozone generation by positive wire-to-plate corona discharge in air
Authors: Bo Z , Chen J H
Published: January 2010

The dimensional analysis technique is used to formulate a correlation between ozone generation rate and various parameters that are important in the design and operation of positive wire-to-plate corona discharges in indoor air. The dimensionless relation is determined by linear regression analysis based on the results from 36 laboratory-scale experiments. The derived equation is validated by experimental data and a numerical model published in the literature. Applications of such derived equation are illustrated through an example selection of the appropriate set of operating conditions in the design/operation of a photocopier to follow the federal regulations of ozone emission. Finally, a new current–voltage characteristic equation is proposed for positive wire-to-plate corona discharges based on the derived dimensionless equation.
Differences between dielectric barrier discharge plasma actuators with cylindrical and rectangular exposed electrodes
Authors: Hoskinson A R , Hershkowitz N
Published: January 2010

Surface dielectric barrier discharges (DBDs) used as plasma actuators can induce significant time-averaged forces in nearby neutral gases. For single-barrier actuators (one electrode insulated) these forces are dependent on the geometry of the exposed electrode. We demonstrate that using thin cylindrical exposed electrodes can increase the induced force by several hundred percent compared with an actuator with a rectangular exposed electrode of the same thickness. This difference is due almost exclusively to the extent of the exposed electrode in the same direction as the gap between the two electrodes, which tends to be much longer for actuators constructed with rectangular exposed electrodes. The exact shape of the electrode cross-section plays no role. In addition, using an intensified digital camera we observed a new filament-free plasma that occurred only in discharges with exposed electrodes smaller than approximately 0.15 mm in diameter. These discharges spent an increasing fraction of the applied voltage period in this mode as we reduced the exposed electrode diameter. The mode shared several characteristics with a positive corona, and was partially responsible for a decrease in the electrical power used by these discharges.
Energetic deposition of metal ions: observation of self-sputtering and limited sticking for off-normal angles of incidence
Authors: Wu Hongchen , Anders André
Published: January 2010

The deposition of films under normal and off-normal angles of incidence has been investigated in order to explore the relevance of non-sticking and self-sputtering of energetic ions. Non-sticking and self-sputtering lead to the formation of neutral atoms which return to the plasma and affect its properties. The flow of energetic ions was obtained using a filtered cathodic arc system in high vacuum. The range of materials included Cu, Ag, Au, Pt, Ti and Ni. Consistent with molecular dynamics simulations published in the literature, the experiments showed that the combined effects of non-sticking and self-sputtering appear to be significant, although the relatively large error range of the experimental method would not allow us to derive quantitative data. It was shown that modest heating of the substrate and intentional introduction of oxygen background gas considerably affected the results.
A Monte Carlo study of photoelectron extraction efficiency from CsI photocathodes into Xe–CH4 and Ne–CH4 mixtures
Authors: Escada J , Dias T H V T , Rachinhas P J B M , Santos F P , Lopes J A M , Coelho L C C , Conde C A N , Stauffer A D
Published: January 2010

The extraction efficiency f for the photoelectrons emitted from a CsI photocathode into gaseous Xe–CH4 and Ne–CH4 mixtures is investigated by Monte Carlo simulation. The results are compared with earlier calculations in Ar–CH4 mixtures and in the pure gases Xe, Ar, Ne and CH4. The calculations examine the dependence of f on the density-reduced electric field E/N in the 0.1–40 Td range, on the incident photon energy E
ph in the 6.8–9.8 eV (183–127 nm) VUV range and on the mixture composition. Results calculated for irradiation of the photocathode with a Hg(Ar) lamp are compared with experimental measurements for this lamp. To test the electron scattering cross-sections used in the simulations, electron drift parameters in Xe, Ne and their mixtures with CH4 are also presented and compared with available experimental data.
Electron Bernstein wave assisted plasma current start-up in MAST
Authors: Shevchenko V.F. , O'Brien M.R. , Taylor D. , Saveliev A.N.
Published: January 2010

Electron Bernstein wave (EBW) assisted plasma current start-up has been demonstrated for the first time in a tokamak. It was shown that plasma currents up to 17 kA can be generated non-inductively by 100 kW of RF power injected. With optimized vertical field ramps, plasma currents up to 33 kA have been achieved without the use of solenoid flux. It is shown that the plasma formation and current generation are governed predominantly by EBW current drive. Experimental results are consistent with ray-tracing and quasilinear Fokker–Planck modelling.
Cyclic scenarios for steady-state operation of tokamak reactors
Authors: Garcia J. , Giruzzi G. , Maget P. , Artaud J.F. , Basiuk V. , Decker J. , Huysmans G. , Imbeaux F. , Peysson Y. , Schneider M.
Published: January 2010

A new concept of steady-state scenario for tokamak reactors is proposed. It is based on cyclic operations, alternating phases of positive and negative loop voltage with no magnetic flux consumption on average. Localized non-inductive current drive by electron cyclotron waves is used to trigger and sustain an internal transport barrier (ITB), whereas neutral beam current drive is used to periodically recharge the tokamak transformer. The fact of operating in cycles relaxes the hard constraint of simultaneous fusion performance maximization and full non-inductive operation, within the MHD stability limits. Integrated modelling simulations are performed to apply this concept for the ITER steady-state regime. A linear MHD analysis of the instabilities that could appear in this type of scenario is performed, showing that MHD stability would be strongly improved with respect to a steady regime with a strong ITB.
Performance of the ITER ICRH system as expected from TOPICA and ANTITER II modelling
Authors: Messiaen A. , Koch R. , Weynants R.R. , Dumortier P. , Louche F. , Maggiora R. , Milanesio D.
Published: January 2010

The performance on plasma of the antennas of the proposed ITER ICRF system is evaluated by means of the antenna 24 × 24 impedance matrix provided by the TOPICA code and confirmed and interpreted by the semi-analytical code ANTITER II (summarized in an appendix). From this analysis the following system characteristics can be derived: (1) a roughly constant power capability in the entire 40–55 MHz frequency band with the same maximum voltage in the eight feeding lines is obtained for all the considered heating and current drive phasings on account of the broadbanding effect of service stubs. (2) The power capability of the array significantly depends on the distance of the antenna to the separatrix, the density profile in the scrape-off layer (SOL) and on the strap current toroidal and poloidal phasings. The dependence on phasing is stronger for wider SOL. (3) To exceed a radiated power capability of 20 MW per antenna array in the upper part of the frequency band, with a separatrix–wall distance of 17 cm and a conservative short decay plasma edge density profile, the system voltage stand-off must be 45 kV and well chosen combinations of toroidal and poloidal phasing are needed. (4) On account of the plasma gyrotropy and of poloidal magnetic field, special care must be taken in choosing the optimal toroidal current drive and poloidal phasings.

The ANTITER II analysis shows furthermore that important coaxial and surface mode excitation can only be expected in the monopole toroidal phasing, that strong wave reflection from a steep density profile significantly reduces the coupling even if the separatrix is closer to the antenna and that the part of the edge density profile having a density lower than the cut-off density pertaining to the considered phasing does not significantly contribute to the coupling.
Real-time and post-plasma studies of influence of low levels of tungsten on carbon erosion and surface evolution behaviour in D2 plasma
Authors: Weilnboeck F. , Fox-Lyon N. , Oehrlein G.S. , Doerner R.P.
Published: January 2010

A profound influence of monolayer tungsten coverage of hard carbon films on the evolution of carbon surface erosion behaviour, surface chemistry and morphology in D2 plasma has been established by real-time ellipsometry, x-ray photoelectron spectroscopy and atomic force microscopy measurements. The erosion of tungsten-covered carbon showed two distinct stages of plasma material interactions: rapid tungsten removal during the initial erosion period and steady-state amorphous carbon removal accompanied by large-scale surface roughness development. The initial removal of tungsten takes place at a rate that significantly exceeds typical sputter yields at the ion energies used here and is attributed to elimination of weakly bonded tungsten from the surface. The tungsten remaining on the a-C : H film surface causes surface roughness development of the eroding carbon surface by a masking effect, and simultaneously leads to a seven fold reduction of the steady-state carbon erosion rate for long plasma surface interaction times (∼100 s). Results presented are of direct relevance for material transport and re-deposition, and the interaction of those films with plasma in the divertor region and on mirror surfaces of fusion devices.
Study of turbulent fluctuations driven by the electron temperature gradient in the National Spherical Torus Experiment
Authors: Mazzucato E.
Published: January 2010

We wish to correct the omission of the following co-authors in this article: C. Domier and N. Luhmann, UC Davis, Davis, California, USA
and H. Park, POSTECH, Pohang, Korea. The UC Davis work was supported by US DOE Contract No DE-FG02-99ER54518.
Platonic polyhedra tune the three-sphere: III. Harmonic analysis on octahedral spherical three-manifolds
Authors: Kramer Peter
Published: January 2010

From the homotopy groups of three distinct octahedral spherical three-manifolds we construct the isomorphic groups H of deck transformations acting on the three-sphere. The H-invariant polynomials on the three-sphere constructed by representation theory span the bases for the harmonic analysis on three spherical manifolds. Analysis of the Cosmic Microwave Background in terms of these new bases can reveal a non-simple topology of the space part of space–time.
Aitken extrapolation and epsilon algorithm for an accelerated solution of weakly singular nonlinear Volterra integral equations
Authors: Mesgarani H , Aghazadeh N , Parmour P
Published: January 2010

In this paper, we apply Aitken extrapolation and epsilon algorithm as acceleration technique for the solution of a weakly singular nonlinear Volterra integral equation of the second kind. In this paper, based on Tao and Yong (2006 J. Math. Anal. Appl.
324 225–37.) the integral equation is solved by Navot's quadrature formula. Also, Tao and Yong (2006) for the first time applied Richardson extrapolation to accelerating convergence for the weakly singular nonlinear Volterra integral equations of the second kind. To our knowledge, this paper may be the first attempt to apply Aitken extrapolation and epsilon algorithm for the weakly singular nonlinear Volterra integral equations of the second kind.
Generation of teletraffic of generalized Cauchy type
Authors: Li Ming
Published: January 2010

Generation of long-range-dependent (LRD) traffic is crucial for networking, e.g. simulating the Internet. In this respect, it is necessary to generate an LRD traffic series according to a given correlation structure that may well reflect the statistics of real traffic. Recent research on traffic modeling exhibits that the LRD traffic is well modeled by the generalized Cauchy (GC) process indexed by two parameters that separately characterize the self-similarity (SS), which is a local property described by the fractal dimension D, and long-range dependence (LRD), which is a global property measured by the Hurst parameter H. This paper gives a computational method to generate the LRD traffic based on the correlation form of the GC process in both the unifractal and multifractal cases. It may nevertheless be used as a way to flexibly simulate the realizations that reflect the fractal phenomena of traffic for both short-term lags and long-term ones.
Extending the class of solvable potentials: III. The hyperbolic single wave
Authors: Bahlouli H , Alhaidari A D
Published: January 2010

A new solvable hyperbolic single wave potential is found by expanding the regular solution of the 1D Schrödinger equation in terms of square integrable basis. The main characteristic of the basis is that it supports an infinite tridiagonal matrix representation of the wave operator. However, the eigenenergies associated with this potential cannot be obtained using traditional procedures. Hence, a new approach (the ‘potential parameter’ approach) has been adopted for this eigenvalue problem. For a fixed energy, the problem is solvable for a set of values of the potential parameters (the ‘parameter spectrum’). Subsequently, the map that associates the parameter spectrum with the energy is inverted to give the energy spectrum. The bound state wavefunction is written as a convergent series involving products of the ultraspherical Gegenbauer polynomial in space and a new polynomial in energy, which is a special case of the ‘dipole polynomial’ of the second kind.
Effects of correlated noise in a tumor cell growth model in the presence of immune response
Authors: Zeng Chunhua
Published: January 2010

The effects of correlated noises in a tumor cell growth model in the presence of immune response under the simultaneous action of correlated multiplicative and additive white noise and a weak periodic signal are investigated. The analytical expression of the signal-to-noise ratio (SNR) for the model is obtained by using the theory of SNR in the adiabatic limit. Based on the numerical computations, it is found that (i) a maximum appears in the curve of SNR as a function of cross-correlation intensity λ in the region of λ> 0, i.e. this is a resonant peak, and (ii) for the case of λ>0, the curve of SNR as a function of additive noise intensity α exhibits a minimum first and then a maximum, that is to say, it exhibits suppression first and resonance later. But for the case of λ⩽0, the resonant peak of the SNR-α curve disappears.
Particle–rotor model interpretation of nuclear states in 127I
Authors: Zeghib Sadek
Published: January 2010

Previously observed positive and negative parity states of 127I have been interpreted using a particle–rotor model. Experimental energies and transition properties have been compared to those predicted by the calculation. The results show that this simple model with very few parameters can successfully explain most of the structure of 127I at low and medium energies. 127I being only three protons beyond the closed Z=50 shell with N=74 relatively far from the middle of the 50–82 neutron region (N=66), there is evidence that it is slightly deformed. The rotational structure of the ΔJ=1 band built on an unusually low-lying g9/2 proton–hole state (9/2+[404]) has been naturally very well predicted as well as other rotational features for the g7/2, d5/2 and h11/2 orbitals. Complete particle–core multiplets have been successfully identified for the first time.
An exact solution for electromagnetic solitons in relativistic plasmas
Authors: Biswas Anjan , Milovic Daniela , Zerrad Essaid
Published: January 2010

In this paper, the dynamics of electromagnetic solitons in relativistic plasmas is studied. An exact solution is obtained for the governing nonlinear Schrödinger equation along with perturbation terms. The solitary wave ansatz is used to carry out this integration. The domain restriction of the parameters is also identified.
Cosmic dust-laden plasma expansion: the role of charged impurities
Authors: Djebli M
Published: January 2010

The ionization source model is considered to study the expansion of a cosmic dust-laden plasma. Source and sink terms are included in fluid equations to investigate the one-dimensional self-similar expansion in the presence of dust charge fluctuation. As a consequence of the presence of neutralizing heavy particles and momentum transfer, the validity domain of the self-similar solution is found to increase with dust initial charge. The ion density profile is also found to depend on the dust charge value.
The Decoupling of Farm Programs: Revisiting the Wealth Effect
Authors: Femenia Fabienne , Gohin Alexandre , Carpentier Alain
Published: January 2010

Recent reforms of agricultural policies in developed countries have introduced direct payments as replacements for traditional production‐enhancing instruments. Whereas these new instruments can, in principle, influence production through several channels, current empirical studies show no significant impact on production; direct payments mainly increase land values. In this article, we revisit the evaluation of the coupling effects passing through the wealth of agricultural households. The initial wealth of these agents, while mainly being in the form of land asset holding, is always assumed to be fixed. To the contrary, we show theoretically and through an empirical simulation exercise that once the impact of farm programs on initial wealth is properly accounted for, the measure of the coupling effects is not as negligible as found in previous studies.
International Financial Volatility and Commodity Exports: Evidence from the Thai Agricultural Sector
Authors: May Justin B.
Published: January 2010

Using 1981–2006 data from the Bank of Thailand, I estimate the effect of four measures of real exchange rate volatility on Thai exports of five key agricultural commodities, controlling for both the level of the real exchange rate and foreign incomes. Estimates of the effect of volatility on export volume are generally negative and often significant, lending support to a range of theoretical models that predict such an effect. No such relationship exists between lagged values of exchange rate volatility and agricultural production. The range of results obtained using various measures of volatility suggests caution in comparing studies using different measures.
Profit Margin Hedging
Authors: Kim Hyun Seok , Brorsen B. Wade , Anderson Kim B.
Published: January 2010

Some extension economists and others recommend profit margin hedging as a way to choose the timing of crop sales. However, the theory behind this strategy recommendation is not well developed. This article determines the producer's utility function and price processes where profit margin hedging is optimal. Profit margin hedging is shown to be an optimal strategy under a highly restricted target utility function even in an efficient market. Profit margin hedging is profitable if prices are mean reverting.
A fast and automated solution for accurately resolving protein domain architectures
Authors: Yeats Corin , Redfern Oliver C. , Orengo Christine
Published: January 2010

Motivation: Accurate prediction of the domain content and arrangement in multi-domain proteins (which make up >65% of the large-scale protein databases) provides a valuable tool for function prediction, comparative genomics and studies of molecular evolution. However, scanning a multi-domain protein against a database of domain sequence profiles can often produce conflicting and overlapping matches. We have developed a novel method that employs heaviest weighted clique-finding (HCF), which we show significantly outperforms standard published approaches based on successively assigning the best non-overlapping match (Best Match Cascade, BMC).

Results: We created benchmark data set of structural domain assignments in the CATH database and a corresponding set of Hidden Markov Model-based domain predictions. Using these, we demonstrate that by considering all possible combinations of matches using the HCF approach, we achieve much higher prediction accuracy than the standard BMC method. We also show that it is essential to allow overlapping domain matches to a query in order to identify correct domain assignments. Furthermore, we introduce a straightforward and effective protocol for resolving any overlapping assignments, and producing a single set of non-overlapping predicted domains.

Availability and implementation: The new approach will be used to determine MDAs for UniProt and Ensembl, and made available via the Gene3D website: http://gene3d.biochem.ucl.ac.uk/Gene3D/. The software has been implemented in C++ and compiled for Linux: source code and binaries can be found at: ftp://ftp.biochem.ucl.ac.uk/pub/gene3d_data/DomainFinder3/

Contact:  yeats@biochem.ucl.ac.uk

Supplementary information:  Supplementary data are available at Bioinformatics online.
Gene selection in microarray survival studies under possibly non-proportional hazards
Authors: Dunkler Daniela , Schemper Michael , Heinze Georg
Published: January 2010

Motivation: Univariate Cox regression (COX) is often used to select genes possibly linked to survival. With non-proportional hazards (NPH), COX could lead to under- or over-estimation of effects.

The effect size measure c=P(T1<T0), i.e. the probability that a person randomly chosen from group G1 dies earlier than a person from G0, is independent of the proportional hazards (PH) assumption. Here we consider its generalization to continuous data c′ and investigate the suitability of c′ for gene selection.

Results: Under PH, c′ is most efficiently estimated by COX. Under NPH, c′ can be obtained by weighted Cox regression (WHE) or a novel method, concordance regression (CON). The least biased and most stable estimates were obtained by CON. We propose to use c′ as summary measure of effect size to rank genes irrespective of different types of NPH and censoring patterns.

Availability: WHE and CON are available as R packages.

Contact:  georg.heinze@meduniwien.ac.at

Supplementary Information:  Supplementary Data are available at Bioinformatics online.
Anti‐Oxidative Abilities of Essential Oils from Atractylodes ovata Rhizome
Authors: Wang Kun-Teng , Chen Lih-Geeng , Chou Duen-Suey , Liang Wen-Li , Wang Ching-Chiung
Published: January 2010

The rhizome of Atractylodes ovata De Candolle is rich in essential oils, which are usually removed by processing. In this study, anti‐oxidative abilities of essential oils and aqueous extracts of A. ovata rhizome were explored, and the influence of processing on the anti‐oxidative abilities was examined. Essential oils and aqueous extracts of A. ovata were extracted by boiling water and steam distillation, respectively. Quality of these two A. ovata samples was controlled by HPLC and GC‐MS system, and anti‐oxidative abilities were then evaluated. Results showed that surface color of A. ovata turned to brown and chemical components were changed by processing. Contents of both atractylon and atractylenolide II decreased in the essential oils, but only the contents of atractylon decreased by processing. Atractylenolide III increased in both A. ovata samples. However, A. ovata essential oils displayed stronger anti‐oxidative abilities than aqueous extracts in DPPH‐scavenging, TBH‐induced lipid peroxidation and catalase activity assays. Moreover, the bioactivity of essential oils from raw A. ovata was stronger than oils from processed A. ovata. On the other hand, cytotoxicity of A. ovata essential oils was stronger than that of aqueous extracts, and was more sensitive on H9C2 cell than NIH‐3T3 and WI‐38 cells. In contrast, stir‐frying processing method increased cytotoxicity of essential oils, but the cytotoxicity was ameliorated when processed with assistant substances. The results suggested that phytochemical components and bioactivity of A. ovata were changed after processing and the essential oils from raw A. ovata showed better anti‐oxidative and fewer cytotoxicity effects.
Salmonella SdiA Recognizes N-acyl Homoserine Lactone Signals from Pectobacterium carotovorum in Vitro, but Not in a Bacterial Soft Rot
Authors: Noel J. T. , Joy J. , Smith J. N. , Fatica M. , Schneider K. R. , Ahmer B. M. M. , Teplitski M.
Published: February 2010

Genomes of Salmonella enterica isolates, including those linked to outbreaks of produce-associated gastroenteritis, contain sdiA, which encodes a receptor of N-acyl homoserine lactones (AHL). AHL are the quorum-sensing signals used by bacteria to coordinately regulate gene expression within -their populations. Because S. enterica does not produce its own AHL, SdiA is hypothesized to function in the interspecies cross-talk with AHL-producing bacteria. Under laboratory conditions, S. enterica responded to AHL from phytobacteria by upregulating expression of srgE. AHL-dependent expression of srgE required a functional sdiA. Essentially, no sdiA-dependent resolution of the srgE recombinase-based (RIVET) reporter was observed inside a soft rot formed on a tomato by an AHL-producing strain of Pectobacterium carotovorum. The results of the control experiments suggest that sdiA is not expressed inside tomato, pepper, green onion, or carrot affected by the soft rot, and the lack of sdiA expression in planta prevents Salmonella spp. from responding to AHL. Despite its inability to detect and respond to AHL during colonization of soft rots, S. enterica reached higher final cell numbers inside a tomato soft rot compared with its growth in intact tomato fruit. The synergistic effect was the strongest under the conditions that are typical for the Florida fall/winter production season.
The enigma of optical momentum in a medium
Authors: Barnett Stephen M. , Loudon Rodney
Published: February 2010

It is 100 years since Minkowski and Abraham first gave rival expressions for the momentum of light in a material medium. At the single-photon level, these correspond, respectively, either to multiplying or dividing the free-space value (

) by the refractive index (
n
). The debate that this work started has continued till the present day, punctuated by the occasional publication of ‘decisive’ experimental demonstrations supporting one or other of these values. We review the compelling arguments made in support of the Minkowski and Abraham forms and are led to the conclusion that
both
momenta are correct. We explain why two distinct momenta are needed to describe light in a medium and why each appears as the natural, and experimentally observed, momentum in appropriate situations.
Geometry and physics
Authors: Atiyah Michael , Dijkgraaf Robbert , Hitchin Nigel
Published: February 2010

We review the remarkably fruitful interactions between mathematics and quantum physics in the past decades, pointing out some general trends and highlighting several examples, such as the counting of curves in algebraic geometry, invariants of knots and four-dimensional topology.
Flat-panel electronic displays: a triumph of physics, chemistry and engineering
Authors: Hilsum Cyril
Published: February 2010

This paper describes the history and science behind the development of modern flat-panel displays, and assesses future trends. Electronic displays are an important feature of modern life. For many years the cathode ray tube, an engineering marvel, was universal, but its shape was cumbersome and its operating voltage too high. The need for a flat-panel display, working at a low voltage, became imperative, and much research has been applied to this need. Any versatile flat-panel display will exploit an electro-optical effect, a transparent conductor and an addressing system to deliver data locally. The first need is to convert an electrical signal into a visible change. Two methods are available, the first giving emission of light, the second modulating ambient illumination. The most useful light-emitting media are semiconductors, historically exploiting III–V or II–VI compounds, but more recently organic or polymer semiconductors. Another possible effect uses gas plasma discharges. The modulating, or subtractive, effects that have been studied include liquid crystals, electrophoresis, electrowetting and electrochromism.

A transparent conductor makes it possible to apply a voltage to an extended area while observing the results. The design is a compromise, since the free electrons that carry current also absorb light. The first materials used were metals, but some semiconductors, when heavily doped, give a better balance, with high transmission for a low resistance. Delivering data unambiguously to a million or so picture elements across the display area is no easy task. The preferred solution is an amorphous silicon thin-film transistor deposited at each cross-point in an
X
–
Y
matrix.

Success in these endeavours has led to many applications for flat-panel displays, including television, flexible displays, electronic paper, electronic books and advertising signs.