bluuebunny/crossref_metadata_2025 huggingface dataset:
Capacitive behavior of pentacene-based diodes: Quasistatic dielectric constant and dielectric strength
Authors: Kim Chang Hyun , Yaghmazadeh Omid , Tondelier Denis , Jeong Yong Bin , Bonnassieux Yvan , Horowitz Gilles
Published: April 2011

The capacitive behavior of pentacene films was investigated in the metal-semiconductor-metal (MSM) diode structure. Impedance analysis of diodes with a thick pentacene layer up to 1012 nm showed a full depletion of the organic layer. This observation allowed us to regard the MSM diode as a parallel-plate capacitor in the reverse-bias regime without current flow. Under forward-bias, the diode was evaluated through frequency-dependent impedance measurements by using an equivalent circuit composed of a single parallel resistance-capacitance circuit. The analysis of the data in both the reverse and forward bias regime led us to electrical methods for quantifying dielectric properties of pentacene.
Complementary chiral metamaterials with giant optical activity and negative refractive index
Authors: Li Zhaofeng , Alici Kamil Boratay , Colak Evrim , Ozbay Ekmel
Published: April 2011

A complementary bilayer cross-wire chiral metamaterial is proposed and studied experimentally and numerically. It exhibits giant optical activity and a small circular dichroism. The retrieval results reveal that a negative refractive index is realized for right circularly polarized waves due to the strong chirality. Our numerical results show that the mechanism of the chiral behavior at the resonance of lower frequency can be interpreted as the coupling effects between two sets of mutually twisted virtual magnetic dipoles, while the resonance of higher frequency shows complicated nonlocal features.
Magnetic properties and phonon behavior of Pr2NiMnO6 thin films
Authors: Singh M. P. , Truong K. D. , Jandl S. , Fournier P.
Published: April 2011

We report on the magnetic properties and the phonon behavior of epitaxial Pr2NiMnO6 (PNMO) films. The temperature dependence of their magnetic properties shows a ferromagnetic behavior up to 214 K owing to a dominant Ni2+/Mn4+ ordering. The observation of a secondary low-temperature magnetic transition around 126 K indicates that a small proportion of Ni/Mn disordered lattice remains in our films. Unlike La2NiMnO6, the temperature dependence of the 651 cm−1 Raman active phonon of our films reflects the presence of a weak spin–phonon coupling in PNMO.
Propagation characters of Gaussian laser beams in collisionless plasma: Effect of plasma temperature
Authors: Wang Ying , Zhou Zhongxiang
Published: April 2011

This paper presents an investigation of the propagation characters of Gaussian laser beam in cold collisionless plasma by considering the plasma temperature variation. The ponderomotive nonlinearity is involved and induces the nonlinear self-focusing against spatial diffraction. The second-order differential equation of dimensionless beam width parameter f(ξ) in terms of plasma temperature is established from Maxwell’s equations with paraxial approximation. The initial (P0,ρ0) plane, behaviors of f(ξ) parameter, and perturbed density n/nn0n0 of different plasma temperatures are plotted and analyzed. The plasma temperature is divided into four regions, which leads to different propagation characters including oscillatory divergence, self-trapping, self-focusing, and steady divergence. The plasma density distribution modified by the electric field intensity and plasma temperature is discussed.
An effusive molecular beam technique for studies of polyatomic gas–surface reactivity and energy transfer
Authors: Cushing G. W. , Navin J. K. , Valadez L. , Johánek V. , Harrison I.
Published: April 2011

An effusive molecular beam technique is described to measure alkane dissociative sticking coefficients, S(Tg, Ts; ϑ), on metal surfaces for which the impinging gas temperature, Tg, and surface temperature, Ts, can be independently varied, along with the angle of incidence, ϑ, of the impinging gas. Effusive beam experiments with Tg = Ts = T allow for determination of angle-resolved dissociative sticking coefficients, S(T; ϑ), which when averaged over the cos (ϑ)/π angular distribution appropriate to the impinging flux from a thermal ambient gas yield the thermal dissociative sticking coefficient, S(T). Nonequilibrium S(Tg, Ts; ϑ) measurements for which Tg ≠ Ts provide additional opportunities to characterize the transition state and gas–surface energy transfer at reactive energies. A resistively heated effusive molecular beam doser controls the Tg of the impinging gas striking the surface. The flux of molecules striking the surface from the effusive beam is determined from knowledge of the dosing geometry, chamber pressure, and pumping speed. Separate experiments with a calibrated leak serve to fix the chamber pumping speed. Postdosing Auger electron spectroscopy is used to measure the carbon of the alkyl radical reaction product that is deposited on the surface as a result of alkane dissociative sticking. As implemented in a typical ultrahigh vacuum chamber for surface analysis, the technique has provided access to a dynamic range of roughly 6 orders of magnitude in the initial dissociative sticking coefficient for small alkanes on Pt(111).
Bifurcation, amplitude death and oscillation patterns in a system of three coupled van der Pol oscillators with diffusively delayed velocity coupling
Authors: Song Yongli , Xu Jian , Zhang Tonghua
Published: April 2011

In this paper, we study a system of three coupled van der Pol oscillators that are coupled through the damping terms. Hopf bifurcations and amplitude death induced by the coupling time delay are first investigated by analyzing the related characteristic equation. Then the oscillation patterns of these bifurcating periodic oscillations are determined and we find that there are two kinds of critical values of the coupling time delay: one is related to the synchronous periodic oscillations, the other is related to eight branches of asynchronous periodic solutions bifurcating simultaneously from the zero solution. The stability of these bifurcating periodic solutions are also explicitly determined by calculating the normal forms on center manifolds, and the stable synchronous and stable phase-locked periodic solutions are found. Finally, some numerical simulations are employed to illustrate and extend our obtained theoretical results and numerical studies also describe the switches of stable synchronous and phase-locked periodic oscillations.
Exact solution for a noncentral electric dipole ring-shaped potential in the tridiagonal representation
Authors: Huang-Fu Guo-Qing , Zhang Min-Cang
Published: April 2011

The Schrödinger equation with noncentral electric dipole ring-shaped potential is investigated by working in a complete square integrable basis that supports an infinite tridiagonal matrix representation of the wave operator. The three-term recursion relations for the expansion coefficients of both the angular and radial wavefunctions are presented. The discrete spectrum for the bound states is obtained by the diagonalization of the radial recursion relation. Some potential applications of this system in different fields are discussed.
An estimate for the resolvent of a non-self-adjoint differential operator on the half-line
Authors: Gil M. I.
Published: April 2011

We consider the operator defined by \documentclass[12pt]{minimal}\begin{document}$(T_0y)(x)=-y^{\prime \prime }+ q(x)y\;\;(x>0)$\end{document}(T0y)(x)=−y′′+q(x)y(x>0) on the domain Dom (T0) = {f ∈ L2(0, ∈fty): f′′ ∈ L2(0, ∈fty), f(0) = 0}. Here q(x) = p(x) + ib(x), where p(x) and b(x) are real functions satisfying the following conditions: b(x) is bounded on [0, ∞), there exists the limit b0 ≔ limx → ∞b(x) and b(x) − b0 ∈ L2(0, ∈fty). In addition, \documentclass[12pt]{minimal}\begin{document}$\inf _x p(x)> \sup _x |b_1(x)|$\end{document}infxp(x)>supx|b1(x)|. We derive an estimate for the norm of the resolvent of T0, as well as prove that (T0 − ib0I)−1 is a sum of a normal operator and a quasinilpotent one, and these operators have the same invariant subspaces.
The stochastic quasi-steady-state assumption: Reducing the model but not the noise
Authors: Srivastava Rishi , Haseltine Eric L. , Mastny Ethan , Rawlings James B.
Published: April 2011

Highly reactive species at small copy numbers play an important role in many biological reaction networks. We have described previously how these species can be removed from reaction networks using stochastic quasi-steady-state singular perturbation analysis (sQSPA). In this paper we apply sQSPA to three published biological models: the pap operon regulation, a biochemical oscillator, and an intracellular viral infection. These examples demonstrate three different potential benefits of sQSPA. First, rare state probabilities can be accurately estimated from simulation. Second, the method typically results in fewer and better scaled parameters that can be more readily estimated from experiments. Finally, the simulation time can be significantly reduced without sacrificing the accuracy of the solution.
Breather solutions of the discrete nonlinear Schrödinger equations with sign changing nonlinearity
Authors: Zhang Guoping
Published: April 2011

In this paper, we investigate the breather solutions of the discrete nonlinear Schrödinger equation with the unbounded potential and nonlinearity containing both self-focusing and defocusing sites (which means the coefficients of nonlinearity change sign). By using the generalized Nehari manifold method, we obtain the existence of nontrivial exponential decay breather solutions.
Feasibility of noninvasive cavitation-guided blood-brain barrier opening using focused ultrasound and microbubbles in nonhuman primates
Authors: Tung Yao-Sheng , Marquet Fabrice , Teichert Tobias , Ferrera Vincent , Konofagou Elisa E.
Published: April 2011

In vivo transcranial and noninvasive cavitation detection with blood-brain barrier (BBB) opening in nonhuman primates is hereby reported. The BBB in monkeys was opened transcranically using focused ultrasound (FUS) in conjunction with microbubbles. A passive cavitation detector, confocal with the FUS transducer, was used to identify and monitor the bubble behavior. During sonication, the cavitation spectrum, which was found to be region-, pressure-, and bubble-dependent, provided real-time feedback regarding the opening occurrence and its properties. These findings demonstrate feasibility of transcranial, cavitation-guided BBB opening using FUS and microbubbles in noninvasive human applications.
Lifetime recovery in p-type Czochralski silicon due to the reconfiguration of boron–oxygen complexes via a hole-emitting process
Authors: Lim Bianca , Voronkov Vladimir V. , Falster Robert , Bothe Karsten , Schmidt Jan
Published: April 2011

The recovery of the light-degraded lifetime during annealing in darkness at 120 to 160 °C is examined in boron-doped p-type Czochralski silicon (Cz-Si) as well as in compensated Cz-Si codoped with boron and phosphorus. The rate constant for the recovery is found to be inversely proportional to the hole concentration for both boron-doped and compensated material. Our experiments confirm a model, in which the process of recovery is assigned to a reconfiguration of a boron–oxygen defect complex, whereby a hole is emitted. The activation energy for the recovery process is determined to be (1.36±0.06) eV.
Ultrasmall and ultrafast all-optical modulation based on a plasmonic lens
Authors: Yue Song , Li Zhi , Chen Jianjun , Gong Qihuang
Published: April 2011

By exciting a plasmonic lens with femtosecond laser and utilizing the optical nonlinearity of the gold, an ultrasmall and ultrafast all-optical modulation spot was achieved inside a thin gold film. Near-field pump-probe measurements indicated a modulation spot size of about 600 nm, and a response time of about 1.5 ps. Even smaller spot size of about 300 nm was inferred from numerical simulations, beyond the diffraction limit given an incident wavelength of 1000 nm. Moreover, the optical nonlinearity and the modulation depth were increased by one order of magnitude at the focus compared to that at positions without structures.
Multiple negative differential resistance and the modulation in a nanotubelike fullerene D5h(1)-C90
Authors: Guo Y. D. , Yan X. H. , Xiao Y.
Published: April 2011

We have preformed a first-principle calculation on the electronic transport properties of a recently synthesized nanotubelike fullerene D5h(1)-C90. One finds three negative differential resistance regions in the I-V curve, which could be modulated by gate voltage and contact configuration. Further analysis showed that, the charge transfer and molecule-electrode coupling, induced by both bias and gate voltages, are responsible for the observed phenomena.
Structural controlled magnetic anisotropy in Heusler L1−MnGa epitaxial thin films
Authors: Wang Kangkang , Lu Erdong , Knepper Jacob W. , Yang Fengyuan , Smith Arthur R.
Published: April 2011

Ferromagnetic L10−MnGa thin films have been epitaxially grown on GaN, sapphire, and MgO substrates using molecular beam epitaxy. Using diffraction techniques, the epitaxial relationships are determined. It is found that the crystalline orientation of the films differ due to the influence of the substrate. By comparing the magnetic anisotropy to the structural properties, a clear correlation could be established indicating that the in-plane and out-of-plane anisotropy is directly determined by the crystal orientation of the film and could be controlled via selection of the substrates. This result could be helpful in tailoring magnetic anisotropy in thin films for spintronic applications.
Atypical protein kinase C controls sea urchin ciliogenesis
Authors: Prulière Gérard , Cosson Jacky , Chevalier Sandra , Sardet Christian , Chenevert Janet
Published: April 2011

The atypical protein kinase C (aPKC) is part of the conserved aPKC/PAR6/PAR3 protein complex, which regulates many cell polarity events, including the formation of a primary cilium at the apical surface of epithelial cells. Cilia are highly organized, conserved, microtubule-based structures involved in motility, sensory processes, signaling, and cell polarity. We examined the distribution and function of aPKC in the sea urchin embryo, which forms a swimming blastula covered with motile cilia. We found that in the early embryo aPKC is uniformly cortical and becomes excluded from the vegetal pole during unequal cleavages at the 8- to 64-cell stages. During the blastula and gastrula stages the kinase localizes at the base of cilia, forming a ring at the transition zone between the basal body and the elongating axoneme. A dose-dependent and reversible inhibition of aPKC results in mislocalization of the kinase, defective ciliogenesis, and lack of swimming. Thus, as in the primary cilium of differentiated mammalian cells, aPKC controls the growth of motile cilia in invertebrate embryos. We suggest that aPKC might function to phosphorylate kinesin and so activate the transport of intraflagellar vesicles.
GRB2 couples RhoU to epidermal growth factor receptor signaling and cell migration
Authors: Zhang Jin-San , Koenig Alexander , Young Charles , Billadeau Daniel D.
Published: April 2011

RhoU is an atypical Rho family member with high homology to CDC42 but containing unique N- and C-terminal extensions. The mechanisms regulating RhoU activation, as well as its downstream effectors, are not fully characterized. We show that after epidermal growth factor (EGF) stimulation RhoU colocalizes with EGF receptor (EGFR) on endosomes, which requires both its N- and C-terminal extension sequences. Moreover, RhoU physically associates with activated EGFR in a GRB2-dependent manner through specific proline-rich motifs within its N-terminus. Mutation of these proline-rich sequences or suppression of GRB2 by RNA interference abrogates the interaction of RhoU with activated EGFR, as well as EGF-stimulated RhoU GTP binding. In addition, RhoU is involved in EGFR-mediated signaling, leading to AP1 transcriptional activity and cell migration in pancreatic cancer cells, events that require its interaction with the Grb2–EGFR complex. Taken together, the data suggest a unique regulatory mechanism by which RhoU interaction with SH3 adaptor proteins might serve to integrate growth factor receptor signaling with RhoU activation.
Distinct roles of cadherin-6 and E-cadherin in tubulogenesis and lumen formation
Authors: Jia Liwei , Liu Fengming , Hansen Steen H. , ter Beest Martin B.A. , Zegers Mirjam M.P.
Published: April 2011

Classic cadherins are important regulators of tissue morphogenesis. The predominant cadherin in epithelial cells, E-cadherin, has been extensively studied because of its critical role in normal epithelial development and carcinogenesis. Epithelial cells may also coexpress other cadherins, but their roles are less clear. The Madin Darby canine kidney (MDCK) cell line has been a popular mammalian model to investigate the role of E-cadherin in epithelial polarization and tubulogenesis. However, MDCK cells also express relatively high levels of cadherin-6, and it is unclear whether the functions of this cadherin are redundant to those of E-cadherin. We investigate the specific roles of both cadherins using a knockdown approach. Although we find that both cadherins are able to form adherens junctions at the basolateral surface, we show that they have specific and mutually exclusive roles in epithelial morphogenesis. Specifically, we find that cadherin-6 functions as an inhibitor of tubulogenesis, whereas E-cadherin is required for lumen formation. Ablation of cadherin-6 leads to the spontaneous formation of tubules, which depends on increased phosphoinositide 3-kinase (PI3K) activity. In contrast, loss of E-cadherin inhibits lumen formation by a mechanism independent of PI3K.
Alanine substitutions within a linker region of the influenza A virus non-structural protein 1 alter its subcellular localization and attenuate virus replication
Authors: Li Wei , Noah James W. , Noah Diana L.
Published: April 2011

The influenza A virus non-structural protein 1 (NS1) is a multifunctional protein and an important virulence factor. It is composed of two well-characterized domains linked by a short, but not well crystallographically defined, region of unknown function. To study the possible function of this region, we introduced alanine substitutions to replace the two highly conserved leucine residues at amino acid positions 69 and 77. The mutant L69,77A NS1 protein retained wild-type (WT)-comparable binding capabilities to dsRNA, cleavage and polyadenylation specificity factor 30 and the p85β subunit of PI3K. A mutant influenza A virus expressing the L69,77A NS1 protein was generated using reverse genetics. L69,77A NS1 virus infection induced significantly higher levels of beta interferon (IFN-β) expression in Madin–Darby canine kidney (MDCK) cells compared with WT NS1 virus. In addition, the replication rate of the L69,77A NS1 virus was substantially lower in MDCK cells but not in Vero cells compared with the WT virus, suggesting that the L69,77A NS1 protein does not fully antagonize IFN during viral replication. L69,77A NS1 virus infection was not able to activate the PI3K/Akt anti-apoptotic pathway, suggesting that the mutant NS1 protein may not be localized such that it has access to p85β in vivo during infection, which was supported by the altered subcellular localization pattern of the mutant NS1 compared with WT NS1 after transfection or virus infection. Our data demonstrate that this linker region between the two domains is critical for the functions of the NS1 protein during influenza A virus infection, possibly by determining the protein’s correct subcellular localization.
Quantitative texture analysis from powder-like electron diffraction data
Authors: Gemmi Mauro , Voltolini Marco , Ferretti Anna Maria , Ponti Alessandro
Published: April 2011

The textures of an Al thin film and of α-MnS nanocrystals deposited on a carbon film grid have been analysed using powder electron diffraction. For each sample a series of powder electron diffraction patterns tilted with respect to two orthogonal axes were collected, to adapt to this type of data the texture analysis procedures commonly used in synchrotron X-ray transmission geometry. Both pattern sets have been analysed with the Rietveld procedure embedded in the softwareMAUD. The fit is satisfactory with agreement factors of 7.03% for the Al film and 3.42% for α-MnS and reveals in both cases a (111) preferred orientation with a pronounced cylindrical symmetry. The (111) and (100) pole figures, plotted in terms of multiples of random distribution (m.r.d.), show a fairly strong lattice preferred orientation in the Al thin film and a stronger one in the deposited α-MnS nanocrystals, with maxima, for the (111) pole figures, of 8.8 and 19.7 m.r.d., respectively.
Back-reflection energy-dispersive X-ray diffraction: a novel diffraction technique with almost complete insensitivity to sample morphology
Authors: Hansford Graeme Mark
Published: April 2011

A novel X-ray diffraction (XRD) technique, which exhibits almost complete insensitivity to the morphology of and distance to the sample, is presented for the first time. This technique applies energy-dispersive XRD (EDXRD) in a back-reflection geometry, with 2θ ≃ 180°. Although this geometry leads to low resolution of diffraction peaks and the greatest overlap with fluorescence peaks, it nevertheless yields a combination of properties that are unique in the field of X-ray diffractometry. It is likely that diffraction patterns can be obtained with no or very minimal sample preparation. Furthermore, the intrinsic geometry of the method and the simplicity inherent to EDXRD enables a compact lightweight instrument design, suitable for field-portable or hand-held XRD and X-ray fluorescence analysis. Application to geological and planetary science is emphasized in this paper. The characteristics of the technique are elucidatedviatheoretical considerations and ray-trace modelling, and the simplest possible implementation is described.
Contribution of subsurface peat to CO2 and CH4 fluxes in a neotropical peatland
Authors: WRIGHT EMMA L. , BLACK COLIN R. , CHEESMAN ALEXANDER W. , DRAGE TREVOR , LARGE DAVID , TURNER BENJAMIN L. , SJÖGERSTEN SOFIE
Published: April 2011

Tropical peatlands play an important role in the global carbon cycling but little is known about factors regulating carbon dioxide (CO2) and methane (CH4) fluxes from these ecosystems. Here, we test the hypotheses that (i) CO2 and CH4 are produced mainly from surface peat and (ii) that the contribution of subsurface peat to net C emissions is governed by substrate availability. To achieve this, in situ and ex situ CO2 and CH4 fluxes were determined throughout the peat profiles under three vegetation types along a nutrient gradient in a tropical ombrotrophic peatland in Panama. The peat was also characterized with respect to its organic composition using 13C solid state cross‐polarization magic‐angle spinning nuclear magnetic resonance spectroscopy. Deep peat contributed substantially to CO2 effluxes both with respect to actual in situ and potential ex situ fluxes. CH4 was produced throughout the peat profile with distinct subsurface peaks, but net emission was limited by oxidation in the surface layers. CO2 and CH4 production were strongly substrate‐limited and a large proportion of the variance in their production (30% and 63%, respectively) was related to the quantity of carbohydrates in the peat. Furthermore, CO2 and CH4 production differed between vegetation types, suggesting that the quality of plant‐derived carbon inputs is an important driver of trace gas production throughout the peat profile. We conclude that the production of both CO2 and CH4 from subsurface peat is a substantial component of the net efflux of these gases, but that gas production through the peat profile is regulated in part by the degree of decomposition of the peat.
A review of the burden of vertigo
Authors: Holmes Susan , Padgham Nigel D
Published: April 2011

Aim and objectives.  To provide an overview of vertigo and its management and identify its impact on individuals to offer strategies for managing the condition.

Background.  Dizziness and vertigo are symptoms common to many pathologies/dysfunctions ranging from the benign to the potentially serious; many are poorly understood. Although rarely life‐threatening, vertigo is debilitating and significantly affects quality of life; it may be as disabling as paralysis or loss of a limb. Although 40–80% of cases remain unexplained, referral for specific investigation is rare.

Design.  A narrative literature review including descriptive, theoretical and empirical material reliant on the keywords ‘dizziness’ and ‘vertigo’ and the phrase ‘vestibular disorders’. This provided diverse information that was used to address the research questions.

Results.  Vertigo is a widespread and potentially distressing symptom that may arise at any age and be acute or chronic. For most, it resolves spontaneously; for others, dizziness persists, causing significant distress. Its management is challenging, especially when the underlying cause is unclear. Pharmacological interventions, physiotherapy, psychotherapy or, rarely, surgery can be used in its management. Few nursing studies are available, suggesting that nursing knowledge may be limited.

Relevance to clinical practice.  Although nurses may frequently encounter patients with vertigo, there are few relevant nursing studies in this area; few consider appropriate nursing interventions or approaches to patient care. The information provided reveals that understanding the full impact of the condition and identification of patients’ needs are essential to effective care. Some strategies to help affected patients are outlined.

Conclusions.  Vertigo, a widespread, often intractable condition, affects significant numbers of people; diagnosis and management can be challenging. Treatment, care and support must be selected on an individual basis taking individuals into account. The primary goals are to maintain physical status, psychosocial interaction and quality of life.
Leprosy in the Philippines: a review
Authors: Handog Evangeline B. , Gabriel Ma. Teresita G. , Co Cheryl C.
Published: April 2011

Leprosy is a skin disease that accounts for serious deformities and disabilities, leading to stigmatization and psychosocial suffering. It is included in “The Neglected Tropical Diseases”. Not surprisingly, its management is increasingly reported as a function of Dermatology Departments, with a strong community‐orientated bias. Prompt and accurate diagnosis of leprosy is crucial in the control of leprosy. Its management requires a multidisciplinary team of skilled physicians, laboratory staff, and nurses. All members of the health sectors should remain vigilant to combat this battle against leprosy.
SLA‐DRB1 and ‐DQB1 genotyping by the PCR–SSOP–Luminex method
Authors: Ando A. , Shigenari A. , Ota M. , Sada M. , Kawata H. , Azuma F. , Kojima‐Shibata C. , Nakajoh M. , Suzuki K. , Uenishi H. , Kulski J. K. , Inoko H.
Published: April 2011

A simple and novel genotyping method was developed to detect alleles at the swine leukocyte antigen (SLA)‐DRB1 and ‐DQB1 class II loci by using polymerase chain reaction (PCR)–fluorescently labeled sequence‐specific oligonucleotide probes (SSOPs) and Luminex 100 xMAP detection. The PCR–SSOP–Luminex method exhibited accuracy of 95% for both SLA‐DRB1 and ‐DQB1 in 6 homozygous and 16 heterozygous pig samples as confirmed by sequencing the PCR products of the same samples. In addition, 12 low‐resolution SLA class II haplotypes consisting of 7 and 9 DRB1 and DQB1 alleles were identified, respectively, in one population of 283 Landrace pigs. This genotyping method facilitates the rapid and accurate identification of two‐ or four‐digit alleles at the SLA‐DRB1 and ‐DQB1 loci.
Antiplatelet and antithrombotic activities of timosaponin B‐II, an extract of Anemarrhena asphodeloides
Authors: Lu Wen‐Quan , Qiu Yan , Li Tie‐Jun , Tao Xia , Sun Lian‐Na , Chen Wan‐Sheng
Published: April 2011

1. Antithrombotic agents are effective in the treatment of ischaemic stroke. Timosaponin B‐II (TB‐II) is a major active component of Anemarrhena asphodeloides Bunge (Liliaceae; rhizome) that has protective effects against cerebral ischaemic damage. The present study examined the antiplatelet and antithrombotic actions of TB‐II.

2. In in vitro experiments, TB‐II (20, 40 and 80 mg/mL) potently and dose‐dependently inhibited ADP‐induced platelet aggregation. Furthermore, 1, 3 and 6 mg/kg TB‐II prolonged activated partial thromboplastin time by 9.29, 16.86 and 25.50%, respectively, but had no effect on the prothrombin time. Furthermore, 1, 3 and 6 mg/kg TB‐II significantly reduced the wet weight, dry weight and length of the thrombi (%inhibition (based on wet weight): 13.6, 19.8 and 24.7%, respectively).

3. In a rabbit arteriovenous shunt model, 1, 3 and 6 mg/kg, i.v., TB‐II had no effect on thrombus formation. Plasma euglobulin lysis time and fibrin degradation product were not affected by 1, 3 and 6 mg/kg TB‐II, but plasminogen levels were decreased significantly by 14.4, 18.3 and 29.0%, respectively.

4. The results of the present study demonstrate significant antiplatelet and anticoagulation effects of TB‐II and suggest that these actions could contribute to its neuroprotective effect against damage following cerebral ischaemia damage.
Neural correlates of Pavlovian‐to‐instrumental transfer in the nucleus accumbens shell are selectively potentiated following cocaine self‐administration
Authors: Saddoris Michael P. , Stamatakis Alice , Carelli Regina M.
Published: April 2011

During Pavlovian‐to‐instrumental transfer (PIT), learned Pavlovian cues significantly modulate ongoing instrumental actions. This phenomenon is suggested as a mechanism under which conditioned stimuli may lead to relapse in addicted populations. Following discriminative Pavlovian learning and instrumental conditioning with sucrose, one group of rats (naive) underwent electrophysiological recordings in the nucleus accumbens core and shell during a single PIT session. Other groups, following Pavlovian and instrumental conditioning, were subsequently trained to self‐administer cocaine with nosepoke responses, or received yoked saline infusions and nosepoked for water rewards, and then performed PIT while electrophysiological recordings were taken in the nucleus accumbens. Behaviorally, although both naive and saline‐treated groups showed increases in lever pressing during the conditioned stimulus cue, this effect was significantly enhanced in the cocaine‐treated group. Neurons in the core and shell tracked these behavioral changes. In control animals, core neurons were significantly more likely to encode general information about cues, rewards and responses than those in the shell, and positively correlated with behavioral PIT performance, whereas PIT‐specific encoding in the shell, but not core, tracked PIT performance. In contrast, following cocaine exposure, there was a significant increase in neural encoding of all task‐relevant events that was selective to the shell. Given that cocaine exposure enhanced both behavior and shell‐specific task encoding, these findings suggest that, whereas the core is important for acquiring the information about cues and response contingencies, the shell is important for using this information to guide and modulate behavior and is specifically affected following a history of cocaine self‐administration.
Neurodevelopmental outcome following exposure to sedative and analgesic drugs for complex cardiac surgery in infancy*
Authors: Garcia Guerra Gonzalo , Robertson Charlene M. T. , Alton Gwen Y. , Joffe Ari R. , Cave Dominic A. , Dinu Irina A. , Creighton Dianne E. , Ross David B. , Rebeyka Ivan M. ,   the Western Canadian Complex Pediatric Therapies Follow‐up Group
Published: April 2011

Objectives/Aim:  To determine whether sedation/analgesia drugs used before, during, and after infant cardiac surgery are associated with neurodevelopmental outcome.

Background:  Animal models suggest detrimental effects of anesthetic drugs on the developing brain. Whether these results can be extrapolated to human neonates is unclear.

Methods/Materials:  This is a prospective follow‐up project conducted in Western Canada. In all infants ≤6 weeks of age having surgery for congenital heart disease between April 2003 and December 2006, demographic and perioperative variables were collected prospectively. Sedation/analgesia variables were collected retrospectively. For each drug class (inhalationals, opioids, benzodiazepines, ketamine, and chloral hydrate), we calculated the cumulative dose received during hospitalization, average dose received per day, and cumulative number of days the patient received the drug. The outcomes at 18–24 months were as follows: General Adaptive Composite and motor scaled scores of the Adaptive Behavior Assessment System, significant mental, motor, and vocabulary delay. Multivariable logistic and linear regression was used to analyze the data.

Results:  One hundred and thirty‐five neonates underwent open heart surgery; 19 died, 16 had chromosomal abnormality, and five were lost to follow up, leaving 95 survivors for analysis. Multiple linear regression analysis found no evidence of an association between sedation/analgesia variables and ABAS‐GAC score or motor scale score. Multiple logistic regression analysis found no evidence of an association between sedation/analgesia variables and significant mental, motor, or vocabulary delay.

Conclusion:  We found no evidence of an association between dose and duration of sedation/analgesia drugs during the operative and perioperative period and adverse neurodevelopmental outcomes.
Prostate cancer and diet: food for thought?
Authors: Hori Satoshi , Butler Elizabeth , McLoughlin John
Published: April 2011

What’s known on the subject? and What does the study add?

There has been increasing recognition that diet plays an important role in the pathogenesis of prostate cancer. Despite this, the largely heterogenous nature of prostate cancer and nutritional research often means that no definitive conclusions can be drawn for those seeking answers in this important topic.

In this review article, we summarize the key evidence available in this topic to date. Although we found mounting evidence on certain nutritional components being important in prostate cancer prevention and progression, further high quality studies are needed to fully understand the complex nature of diet and prostate cancer.

• There is now increasing evidence that diet plays a major role in prostate cancer biology and tumorigenesis.

• In a health conscious society, it is becoming increasingly common for Urologists to be asked about the impact of diet on prostate cancer.

• In the present review, we explore the current evidence for the role of different dietary components and its’ effect on prostate cancer prevention and progression.

• A literature search was conducted using PubMed® to identify key studies.

• There was some evidence to suggest that green tea, isoflavones, lycopenes, cruciferous vegetables and omega 3 polyunsaturated fatty acid intake to be beneficial in the prevention and/or progression of prostate cancer.

• There was also evidence to suggest that a high total fat, meat (especially well cooked) and multivitamin intake may be associated with an increased risk of developing prostate cancer.

• To date publications have been highly heterogeneous and variable in quality and design. More robust, high quality research trials are needed to help us understand the complex relationship between diet and prostate cancer.
Effect of testosterone administration to men with prostate cancer is unpredictable: a word of caution and suggestions for a registry
Authors: Morales Alvaro
Published: April 2011

What’s known on the subject? and What does the study add?

Very little is known on the effect of T in men with untreated PCa. There are only two small series (including the present one) available that comprise less than 25 men with PCs receiving TTh.

It raises a warning that testosterone administration to men with PCa is not always safe, that current precautions should be maintained, and that only an international registry would provide prompt answers to these issues.

To assess the evidence for the concept that the androgen receptor of prostate cancer (PCa) cells becomes saturated when testosterone values exceed castrate levels, so that testosterone administration in hypogonadal men with untreated PCa does not stimulate tumour growth. To propose basic criteria for administration of testosterone to untreated patients with PCa and, as this is a rare clinical situation, to encourage the establishment of an international registry for these patients. Men with a diagnosis of PCa and symptomatic testosterone deficiency received testosterone therapy (TTh). Patients were assessed quarterly. Prostate‐specific antigen (PSA) velocity was used as the criterion to discontinue therapy and a return to nadir PSA levels allowed re‐initiation of testosterone supplementation. The responses to testosterone supplementation were varied according to each individual and were unpredictable. While some men showed little change after years of treatment, others exhibited a rapid and significant increase in PSA levels. In others, the use of intermittent therapy resulted in synchronous changes in PSA levels. Interruption of TTh invariably translated into a decrease in PSA to pre‐therapy levels. Available evidence regarding the effect of testosterone administration to hypogonadal men with untreated PCa is too limited to be considered reliable. In addition, the response to this treatment appears to be varied and unpredictable. Hypogonadism associated with untreated PCa is not common, therefore, we propose the establishment of an international registry as the quickest way to establish the basic parameters for consideration of TTh in this situation and recommendations for follow‐up. Until credible evidence becomes available, the current restrictions regarding the administration of testosterone to men with PCa should remain in place.
Improved Model‐ and View‐Dependent Pruning of Large Botanical Scenes
Authors: Neubert B. , Pirk S. , Deussen O. , Dachsbacher C.
Published: April 2011

We present an optimized pruning algorithm that allows for considerable geometry reduction in large botanical scenes while maintaining high and coherent rendering quality. We improve upon previous techniques by applying model‐specific geometry reduction functions and optimized scaling functions. For this we introduce the use of Precision and Recall (PR) as a measure of quality to rendering and show how PR‐scores can be used to predict better scaling values. We conducted a user‐study letting subjects adjust the scaling value, which shows that the predicted scaling matches the preferred ones. Finally, we extend the originally purely stochastic geometry prioritization for pruning to account for view‐optimized geometry selection, which allows to take global scene information, such as occlusion, into consideration. We demonstrate our method for the rendering of scenes with thousands of complex tree models in real‐time.
Flexible and Accurate Transparent‐Object Matting and Compositing Using Refractive Vector Field
Authors: Duan Qi , Zheng Jianmin , Cai Jianfei
Published: April 2011

In digital image editing, environment matting and compositing are fundamental and interesting operations that can capture and simulate the refraction and reflection effects of light from an environment. The state‐of‐the‐art real‐time environment matting and compositing method is short of flexibility, in the sense that it has to repeat the entire complex matte acquisition process if the distance between the object and the background is different from that in the acquisition stage, and also lacks accuracy, in the sense that it can only remove noises but not errors. In this paper, we introduce the concept of refractive vector and propose to use a refractive vector field as a new representation for environment matte. Such refractive vector field provides great flexibility for transparent‐object environment matting and compositing. Particularly, with only one process of the matte acquisition and the refractive vector field extraction, we are able to composite the transparent object into an arbitrary background at any distance. Furthermore, we introduce a piecewise vector field fitting algorithm to simultaneously remove both noises and errors contained in the extracted matte data. Experimental results show that our method is less sensitive to artefacts and can generate perceptually good composition results for more general scenarios.
HETEROGENEITY IN WILLINGNESS‐TO‐PAY FOR THEATRE PRODUCTIONS: INDIVIDUAL SPECIFIC WILLINGNESS‐TO‐PAY ESTIMATES FOR THEATRES, SHOWS AND THEIR ATTRIBUTES
Authors: Grisolia Jose M. , Willis Ken
Published: April 2011

This paper investigates people's preferences for live theatre, and heterogeneity in willingness‐to‐pay (WTP). A stated preference discrete choice model estimates utility and WTP for different attributes of theatre productions. Previous studies assumed fixed coefficients across all theatre‐goers. This study allows coefficients of attributes to vary across individuals in the population, providing information on the heterogeneity of tastes. Theatre‐goers' choices are used to estimate individual‐based parameters for a person's tastes in theatre productions. The analysis reveals the heterogeneity of tastes for different types of plays and ticket price; and the significance of ‘reviews’ by critics and ‘word of mouth’ opinions as important variables determining choice.
A tipping point in dialect obsolescence? Change across the generations in Lerwick, Shetland1
Authors: Smith Jennifer , Durham Mercedes
Published: April 2011

The dialect spoken in the Shetland Islands is one of the most distinctive in the British Isles. However, there are claims that this variety is rapidly disappearing, with local forms replaced by more standard variants in the younger generations. In this paper we test these claims through a quantitative analysis of variable forms across three generations of speakers from the main town of Lerwick. We target six variables: two lexical, two morphosyntactic and two phonetic/phonological. Our results show that there is decline in use of the local forms across all six variables. Closer analysis of individual use reveals that the older age cohort form a linguistically homogeneous group. In contrast, the younger speakers form a heterogeneous group: half of the younger speakers have high rates of the local forms, while the other half uses the standard variants near‐categorically. We suggest that these results may pinpoint the locus of rapid obsolescence in this traditionally relic dialect area.
Limit theorems for the discount sums of moving averages
Authors: Chu Ba
Published: April 2011

The present article derives the limiting distributions of the discount sums (a.k.a. the Abel summands) of moving averages. These distributions are extensions of the result obtained for the i.i.d. case by Omey (1984). An example about the ordinary least squares regression model is provided to illustrate the applicability of the proposed theorems.
Bernard Williams: Political Realism and the Limits of Legitimacy
Authors: Bavister‐Gould Alex
Published: April 2011

Abstract: A central component of Bernard Williams' political realism is the articulation of a standard of legitimacy from within politics itself: LEG. This standard is presented as basic, inherent in all political orders and the best way to underwrite fundamental liberal principles particular to the modern state, including basic human rights. It does not require, according to Williams, a wider set of liberal values. In the following, I show that where Williams restricts LEG to generating only minimal political protections, seeking to isolate his account of political legitimacy from a range of liberal principles, this is neither internal to, nor necessarily demanded by, the specifically political account of LEG. Instead, the limitation depends upon his wider ethical thought.
Distributing Leadership in Health and Social Care: Concertive, Conjoint or Collective?
Authors: Currie Graeme , Lockett Andy
Published: April 2011

This paper examines leadership in practice, specifically the interaction of leaders and followers, taking account of context (Spillane, J.P. (2006). Distributed Leadership. San Francisco, CA: Jossey Bass). Employing Gronn's dimensions of concertive action and conjoint agency (Gronn, P. (2002). Distributed leadership as a unit of analysis. Leadership Quarterly, 13, pp. 423–451), different conceptualizations of distributed leadership (DL) are examined, and the influence of a health and social care context on attempts to enact DL is analysed. In so doing, boundary conditions or the limits to distributing leadership in health and social care are identified. The analysis suggests that the collective leadership DL model presented by Denis et al. (Denis, J.‐L., Lamothe, L. and Langley, A. (2001). The dynamics of collective leadership and strategic change in pluralistic organizations. Academy of Management Journal, 44, pp. 809–837) is most likely to be enacted in the face of policy and professional pressures towards more concentrated leadership. However, where DL does not encompass conjoint agency, it will tend towards more towards ‘nobody in charge’ (Buchanan, D.A., Addicott, R., Fitzgerald, L., Ferlie, E. and Baeza, J.I. (2007). Nobody in charge: distributed change agency in healthcare. Human Relations, 60, pp. 1065–1090) or collaborative leadership (Huxham, C. and Vangen, S. (2000). Leadership in the shaping and implementation of collaboration agendas: how things happen in a (not quite) joined‐up world. Academy of Management Journal, 43, pp. 1159–1175). Following the analysis, the authors argue that researchers need to move beyond a reified concept of DL, and ask a more straightforward question of how power is distributed. As Gosling et al. suggest (Gosling, J., Bolden, R. and Petrov, G. (2009). Distributed leadership in higher education: what does it accomplish? Leadership, 5, pp. 299–310), DL evokes an aspiration for the way leadership is configured, and draws attention to iterative relations between leadership, followership and context, but it is a conception of leadership that requires unpacking. This conceptual analysis, applied to health and social care, is offered in pursuit of this aim.