bluuebunny/crossref_metadata_2025 huggingface dataset:
Erythrina variegata extract exerts osteoprotective effects by suppression of the process of bone resorption
Authors: Zhang Yan , Li Qi , Li Xiaoli , Wan Hoi-Ying , Wong Man-Sau
Published: May 2010

Our previous study showed that Erythrina variegata L. (EV) inhibited bone loss and improved bone properties in ovariectomised rats. The purpose of the present study is to investigate the potential mechanism involved in mediating the osteoprotective actions of EV. Female Sprague–Dawley rats were fed a phyto-oestrogen-free diet and subjected to either ovariectomy or a sham operation. Ovariectomised rats were treated with genistein (40 mg/kg) as well as low (200 mg/kg), medium (500 mg/kg) or high (1000 mg/kg) doses of EV extract. Bone properties and mRNA expressions were evaluated by micro-computed tomography and quantitative RT-PCR, respectively. Osteoclast differentiation in RAW 264·7 cells was studied by tartrate-resistant acid phosphatase (TRAP) staining. High doses of EV could decrease urinary Ca and P excretion, maintain serum Ca and P level, and exert beneficial effects on the micro-structure and morphology of trabecular bone and cortical bone in ovariectomised rats. EV suppressed the up-regulation of cathepsin K mRNA and the down-regulation of osteoprotegrin mRNA in the tibia of ovariectomised rats. TRAP-positive cell numbers were significantly decreased in receptor activator of nuclear factor-κB ligand (RANKL)-induced RAW 264·7 cells when co-cultured with EV extracts. The present study indicated that the protective effects of EV on bone properties in ovariectomised rats are likely to be mediated by its inhibitory actions on the process of bone resorption via the suppression of osteoclast differentiation and maturation.
Dietary zinc intake is inversely related to subclinical atherosclerosis measured by carotid intima-media thickness
Authors: Yang Yoon Jung , Choi Bo Youl , Chun Byung-Yeol , Kweon Sun-Seog , Lee Young-Hoon , Park Phil Sook , Kim Mi Kyung
Published: May 2010

The relationship between dietary Zn intake and the risk of atherosclerosis remains unclear, and no epidemiological studies have been reported on the effects of dietary Zn intake on morphological changes in the vascular wall. We examined the relationship between dietary Zn intake and common carotid intima-media thickness (IMT) as a marker of subclinical atherosclerosis among the middle-aged and elderly populations. A cross-sectional analysis of a prospective cohort baseline study was performed with 4564 adults aged 40–89 years and free of clinical CVD. Dietary data were collected by trained interviewers using an FFQ. Common carotid IMT was measured using a B-mode ultrasound imaging technique. Subclinical atherosclerosis was determined using carotid IMT, and defined as >80th percentile of carotid IMT or ≥ 1 mm of carotid IMT. After adjustment for potential confounders, the mean carotid IMT in the low Zn intake group was higher than that in the high Zn intake group. When subclinical atherosclerosis was defined as >80th percentile value of IMT or ≥ 1 mm of carotid IMT, after adjustment for potential confounders, Zn intake was inversely related to subclinical atherosclerosis (5thv.1st quintile, OR 0·64, 95 % CI 0·45, 0·90,Pfor trend = 0·069; 5thv.1st quintile, OR 0·34, 95 % CI 0·16, 0·70,Pfor trend = 0·005, respectively). In persons free of clinical CVD, dietary Zn intake was inversely correlated with subclinical atherosclerosis. The present findings suggest a putative protective role of dietary Zn intake against the development of atherosclerosis.
Dietary DHA: time course of tissue uptake and effects on cytokine secretion in mice
Authors: Lefils Jennifer , Géloën Alain , Vidal Hubert , Lagarde Michel , Bernoud-Hubac Nathalie
Published: May 2010

Consumption of DHA has numerous beneficial effects, but little is known about these effects during the first few days of the DHA dietary intake. The main objectives of the present study were to determine the time course of DHA incorporation into phospholipids in different mouse tissues and the effects of DHA supplementation on adiponectin and leptin secretion. Mice were fed either a control diet or a DHA-rich diet, and some were killed on days 0, 4, 8, 16 and 32. Some mice were fed the DHA-rich diet for 16 d, and were then maintained on the control diet for sixteen more days (washout period). DHA supplementation increased plasma adiponectin secretion by 2·4-fold as early as 4 d after the initiation of the DHA-rich diet feeding. The adiponectin concentration remained 1·6-fold higher after the 16 d washout period. Plasma leptin levels were significantly lower after 4 d of feeding with DHA. These effects were associated with a significant increase in DHA incorporation in phosphatidylethanolamine and phosphatidylcholine of all analysed tissues (liver, heart and white adipose tissues). DHA mainly got incorporated at the expense ofn-6 arachidonic acid. The present data show that DHA rapidly improved the profile of secreted adipokines, and that these protective effects were long lasting.
Hexane–ethanol extract ofGlycyrrhiza uralensiscontaining licoricidin inhibits the metastatic capacity of DU145 human prostate cancer cells
Authors: Park So Young , Lim Soon Sung , Kim Jin Kyu , Kang Il-Jun , Kim Jong-Sang , Lee Choonghwan , Kim Jongdai , Park Jung Han Yoon
Published: May 2010

Licorice extracts are known to exhibit anti-carcinogenic activities. However, chronic licorice consumption can lead to serious side effects due to the presence of considerable quantities of glycyrrhizin, which causes severe hypokalaemia and hypertension. In the present study, we evaluated the effects of a hexane–ethanol extract ofGlycyrrhiza uralensis(HEGU), which lacks glycyrrhizin, on the metastatic characteristics of DU145 prostate cancer cells. HEGU inhibited basal and epidermal growth factor-induced cell migration, invasion and adhesion in a dose-dependent fashion. HEGU significantly suppressed the secretion and activation of the matrix metalloproteinase (MMP)-2 and MMP-9. The secretion of tissue inhibitor of metalloproteinase (TIMP)-1 was reduced, but that of TIMP-2 was increased in HEGU-treated cells. HEGU reduced the protein levels of integrin-α2, the intercellular adhesion molecule, and the vascular cell adhesion molecule. An active fraction of HEGU was separated via column chromatography, and the structure of the active component, licoricidin, was identified via1H NMR and13C NMR. The treatment of DU145 cells with licoricidin induced a reduction in cell migration and the secretion of MMP-9, TIMP-1, urokinase-type plasminogen activator and vascular endothelial growth factor, as well as in the expression of adhesion molecules. These results indicate that HEGU, which contains licoricidin, is a potent anti-metastatic agent, which can markedly inhibit the metastatic and invasive capacity of malignant prostate cancer cells. The observed reductions in the activation of proteases and the levels of adhesion molecules may constitute a component of the mechanisms by which HEGU inhibits the migration and adhesion of prostate cancer cells.
‘RESOURCEFUL AND PROGRESSIVE BLACKMEN’: MODERNITY AND RACE IN BIAFRA, 1967–70
Authors: ANTHONY DOUGLAS
Published: May 2010

Propaganda from Biafra and pro-Biafran rhetoric generated by its supporters drew heavily on ideas of modernity. This continued a pattern of associations rooted in colonial-era policies and ethnic stereotypes, and also represented a deliberate rhetorical strategy aimed at both internal and external audiences. During the second half of the Nigeria–Biafra War, the concept of race assumed an increasingly prominent role in both Biafran and pro-Biafran discourse, in part because of the diminished persuasiveness of Biafran claims about Nigeria's genocidal intentions. Arguments about race dovetailed with established claims about modernity in ways that persist today.
DISTANCE ASSOCIATED WITH MARRIAGE MIGRATION IN A NORTHERN AND A SOUTHERN REGION OF BANGLADESH: AN EMPIRICAL STUDY
Authors: RAHMAN MD. MIZANUR , AKTER SHAMIMA , RAHMAN ATAUR
Published: May 2010

This paper investigates the distribution of distance associated with marriage migration in the northern region of Rajshahi and the southern region of Khulna in Bangladesh. The study was conducted in 2007 on 2250 respondents who had migrated due to marriage. Of the wide variety of curves that fitted the distance–marriage/contact data, three are discussed: Pareto, exponential, and Pareto-exponential. Logistic regression models were used to identify the covariates of marriage distance migration. In general, the three functions work better for marriages, whereas Pareto-exponential functions are a superior fit for migrations and marriage distance. The models disclose that the distribution of distance is significantly associated with marriage migration (p<0.001). The Pareto-exponential model was 100% stable and its shrinkage was 0.000000125. The main covariates associated with short-distance marriage migration were respondent's education, father's education and religion, whereas age at the time of marriage did not play a significant role in marriage migration. The risk of short-distance migration was greater in higher- than lower-educated Muslim families.
An experimental investigation of cloud cavitation about a sphere
Authors: BRANDNER P. A. , WALKER G. J. , NIEKAMP P. N. , ANDERSON B.
Published: May 2010

Cloud cavitation occurrence about a sphere is investigated in a variable-pressure water tunnel using low- and high-speed photography. The model sphere, 0.15 m in diameter, was sting-mounted within a 0.6 m square test section and tested at a constant Reynolds number of 1.5 × 106with cavitation numbers varying between 0.36 and 1.0. High-speed photographic recordings were made at 6 kHz for several cavitation numbers providing insight into cavity shedding and nucleation physics. Shedding phenomena and frequency content were investigated by means of pixel intensity time series data using wavelet analysis. Instantaneous cavity leading edge location was investigated using image processing and edge detection.

The boundary layer at cavity separation is shown to be laminar for all cavitation numbers, with Kelvin–Helmholtz instability and transition to turbulence in the separated shear layer the main mechanism for cavity breakup and cloud formation at high cavitation numbers. At intermediate cavitation numbers, cavity lengths allow the development of re-entrant jet phenomena, providing a mechanism for shedding of large-scale Kármán-type vortices similar to those for low-mode shedding in single-phase subcritical flow. This shedding mode, which exists at supercritical Reynolds numbers for single-phase flow, is eliminated at low cavitation numbers with the onset of supercavitation.

Complex interactions between the separating laminar boundary layer and the cavity were observed. In all cases the cavity leading edge was structured in laminar cells separated by well-known ‘divots’. The initial laminar length and divot density were modulated by the unsteady cavity shedding process. At cavitation numbers where shedding was most energetic, with large portions of leading edge extinction, re-nucleation was seen to be circumferentially periodic and to consist of stretched streak-like bubbles that subsequently became fleck-like. This process appeared to be associated with laminar–turbulent transition of the attached boundary layer. Nucleation occurred periodically in time at these preferred sites and formed the characteristic cavity leading edge structure after sufficient accumulation of vapour had occurred. These observations suggest that three-dimensional instability of the decelerating boundary layer flow may have significantly influenced the developing structure of the cavity leading edge.
A model for the pinch-off process of the leading vortex ring in a starting jet
Authors: GAO L. , YU S. C. M.
Published: May 2010

Modifications have been made to an analytical model proposed by Shusser & Gharib (J. Fluid Mech., vol. 416, 2000b, pp. 173–185) for the vortex ring formation and pinch-off process in a starting jet. Compared with previous models, the present investigation distinguishes the leading vortex ring from its trailing jet so as to consider the details of the pinch-off process in terms of the properties of the leading vortex ring, which are determined by considering the flux of kinetic energy, impulse and circulation from the trailing jet into the leading vortex ring by convective transportation. A two-stage process has been identified before the complete separation of the leading vortex ring from its trailing jet. The first stage involves the growth of the leading vortex ring by absorbing all the ejected fluid from the nozzle until certain optimum size is achieved. The second stage is characterized by the appreciable translational velocity of the leading vortex ring followed by a trailing jet. The leading vortex ring is approximated as a Norbury vortex ring with growing characteristic core radius ϵ such that dimensionless energy α, as well as its translational velocity and penetration depth, can be estimated. By applying the Kelvin–Benjamin variational principle, the pinch-off process is signified by two time scales, i.e. the formation number, which indicates the onset of the pinch-off process, and the separation time, which corresponds to the time when the leading vortex ring becomes physically separated from the trailing jet and is therefore referred to as the end of the pinch-off process. The effect of nozzle geometry, i.e. a straight nozzle or a converging nozzle, has also been taken into account by using different descriptions of the growth of the trailing jet. The prediction of the formation number and the characteristics of the vortex ring are found to be in good agreement with previous experimental results on starting jets with straight nozzles and converging nozzles, respectively.
The limits of tolerance: Islam as counter-hegemony?
Authors: EVANS TONY
Published: May 2010

Following recent acts of terrorism in many parts of the world, Islam has become an object of fear. While the threat of violence is undoubtedly an element that inspires this fear, Islam's counter-hegemonic threat is not limited to violence alone. Given its 1.2 billion following, Islam also offers a challenge to the central values that describe the dominant neo-liberal world order, particularly those values that legitimate the global political economy. Although tolerance is an important value in liberal thought, tolerance cannot be exercised where counter-hegemonic threats include challenges to the central tenets of liberalism. This article argues that the current fear of Islam is motivated by just such a challenge. By looking at four central concepts where liberal and Islamic thought diverge – reason and revelation, private property, rights and duties, and government and state – this article seeks to gain a more nuanced insight into current attitudes towards Islam and the fear of counter-hegemony.
The hegemon's choice between power and security: explaining US policy toward Asia after the Cold War
Authors: HE KAI
Published: May 2010

After the Cold War, US strategists have suggested four strategies for the hegemon: hegemonic dominion, selective engagement, offshore balancing, and multilateralism. Rather than debating which strategy is the best for the US at all times, this article focuses on examining which policy is more likely to be chosen by the hegemon – the US – under different strategic conditions. Through a neoclassical realist argument – the power-perception hegemonic model, I argue that US foreign policy depends on how US policymakers perceive US hegemonic status in the international system. Under rising and stable hegemony, selective engagement and hegemonic dominion are two possible power-maximisation strategies given the weak security constraints from the system. Under declining hegemony, offshore balancing and multilateralism are more likely to be chosen by US policymakers to pursue security because of a resumed security imperative from anarchy. US policy toward Asia after the Cold War is a case study to test the validity of the power-perception hegemonic model. I conclude that US policymakers should prepare for life after Pax-Americana, and early implementation of offshore balancing and multilateralism may facilitate the soft-landing of declining US hegemony.
Beck and beyond: selling security in the world risk society
Authors: KRAHMANN ELKE
Published: May 2010

Expanding on the works of Beck and others on the growing business of risk, this article examines the role of the private security industry in the creation, management and perpetuation of the world risk society. It observes that the replacement of the concept of security with risk over the past decades has permitted private firms to identify a growing range of unknown and unknown-unknown dangers which cannot be eliminated, but require permanent risk management. Using the discourse of risk and its strategies of commercialised, individualised and reactive risk management, the private risk industry thus has contributed to the rise of a world risk society in which the demand for security can never be satisfied and guarantees continuous profits.
Self and other in critical international theory: assimilation, incommensurability and the paradox of critique
Authors: PAIPAIS VASSILIOS
Published: May 2010

This article is principally concerned with the way some sophisticated critical approaches in International Relations (IR) tend to compromise their critical edge in their engagement with the self/other problematique. Critical approaches that understand critique as total non-violence towards, or unreflective affirmation of, alterity risk falling back into precritical paths. That is, either a particularistic, assimilative universalism with pretensions of true universality or a radical incommensurability and the impossibility of communication with the other. This is what this article understands as the paradox of the politics of critique. Instead, what is more important than seeking a final overcoming or dismissal of the self/other opposition is to gain the insight that it is the perpetual striving to preserve the tension and ambivalence between self and other that rescues both critique's authority and function.
Southern Africa's response(s) to international HIV/AIDS norms: the politics of assimilation
Authors: VIEIRA MARCO ANTONIO
Published: May 2010

This article is interested in the impact of a singular international phenomenon, namely the global securitisation of the HIV/AIDS epidemic, on the domestic structure of three Southern African states: Botswana, Mozambique and South Africa. These countries are geographically located in the epicenter of the global HIV/AIDS epidemic, Southern Africa. However, notwithstanding their common HIV/AIDS burden, Botswana, Mozambique and South Africa present quite different political cultures and institutions which reflected upon the distinctive way they responded to the influence of international HIV/AIDS actors and norms. So, by investigating the latter's impact in these rather diverse settings, the present analysis aims to empirically demonstrate and compare variations in the effects of norm adaptation across states. To carry out this evaluation, the study provides a framework for understanding the securitisation of HIV/AIDS as an international norm defined and promoted mainly by the Joint UN Programme on HIV/AIDS (UNAIDS), the US government and transnational HIV/AIDS advocacy networks. The HIV/AIDS securitisation norm (HASN) is an intellectual attempt of the present work to synthesise in a single analytical concept myriad of ideas and international prescriptions about HIV/AIDS interventions.
Crossover in coarsening rates for the monopole approximation of the Mullins–Sekerka model with kinetic drag
Authors: Dai Shibin , Niethammer Barbara , Pego Robert L.
Published: May 2010

The Mullins–Sekerka sharp-interface model for phase transitions interpolates between attachment-limited and diffusion-limited kinetics if kinetic drag is included in the Gibbs–Thomson interface condition. Heuristics suggest that the typical length-scale of patterns may exhibit a crossover in coarsening rate from l(t) ˜ t1/2 at short times to l(t) ˜ t1/3 at long times. We establish rigorous, universal one-sided bounds on energy decay that partially justify this understanding in the monopole approximation and in the associated Lifshitz–Slyozov–Wagner mean-field model. Numerical simulations for the Lifshitz–Slyozov–Wagner model illustrate the crossover behaviour. The proofs are based on a method for estimating coarsening rates introduced by Kohn and Otto, and make use of a gradient-flow structure that the monopole approximation inherits from the Mullins–Sekerka model by restricting particle geometry to spheres.
Periodic solutions for functional differential equations with sign-changing nonlinearities
Authors: Graef John R. , Kong Lingju
Published: May 2010

We establish some eigenvalue criteria for the existence of non-trivial T-periodic solutions of a class of first-order functional differential equations with a nonlinearity f(x). The nonlinear term f(x) can take negative values and may be unbounded from below. Conditions are determined by the relationship between the behaviour of the quotient f(x)/x for x near 0 and ±∞ and the smallest positive characteristic value of an associated linear integral operator. This linear operator plays a key role in the proofs of the results and its construction is non-trivial. Applications to related eigenvalue problems are also discussed. The analysis mainly relies on the topological degree theory.
Multiple positive solutions for singular elliptic equations with weighted Hardy terms and critical Sobolev–Hardy exponents
Authors: Hsu Tsing-San , Lin Huei-Li
Published: May 2010

Variational methods are used to prove the multiplicity of positive solutions for the following singular elliptic equation:

where 0 ∈ Ω ⊂ ℝN, N ≥ 3, is a bounded domain with smooth boundary ∂ Ω, λ > 0 , $1\le q<2$, $0\le\mu<\bar{\mu}=(N-2)^2/4$, 0 ≤ s < 2, 2*(s)=2(N−s)/(N−2) and f and g are continuous functions on $\bar{\varOmega}$, that change sign on Ω.
A NOTE ON PUBLIC INVESTMENT, PUBLIC DEBT, AND MACROECONOMIC PERFORMANCE
Authors: Ismihan Mustafa , Ozkan F. Gulcin
Published: May 2010

This paper provides an assessment of public capital spending within a macroeconomic policy model with explicit monetary and fiscal interactions, in contrast to most of the existing analyses of public investment that utilize “real” general equilibrium models. As such, we are able to consider the interactions of public investment with inflation, taxation, and public debt. Our results indicate that a clear trade-off exists between the costs and benefits of public investment, as is the case in the existing literature. However, the use of a monetary-fiscal policy model rather than a “real” general equilibrium one enables us to trace the macroeconomic channels including monetary ones through which these costs and benefits are transmitted to the rest of the economy. To the extent that these costs and benefits vary between countries, our results provide a potential explanation for the mixed empirical findings on the real effects of public capital spending.
Same-sex marriage: the irrelevance of the economic approach to law
Authors: White Mark D.
Published: May 2010

Several noted legal scholars, most prominently Richard Posner, have applied the economic analysis of law to the debate over same-sex marriage. In this note, I argue that the economic approach to law is ill-equipped to deal with the issues of principle, dignity and rights that are at the core of the debate, regardless of the position taken on the issue. Other scholars, such as Darren Bush, acknowledge the shortcomings of the economic approach, such as the importance of the assumptions on which cost-benefit analysis is made, but they do not appreciate that this is symptomatic of the economic approach as a whole, not merely the application of it by some scholars in some cases. My contention is that the economic approach to law is appropriate regarding issues of policy, where trade-offs are essential and necessary, but not regarding issues of principle, with which trade-offs are not so easily made.
Closing the gate: family lawyers as gatekeepers to a holistic service
Authors: Melville Angela , Laing Karen
Published: May 2010

In 2001, the Legal Services Commission (LSC) introduced a new pilot, the Family Advice and Information Network (FAInS), which recognised that family law clients typically face a cluster of legal and non-legal issues. Family lawyers involved in FAInS were encouraged to address a client’s legal problems, and then refer the client to other services for assistance with non-legal issues. In this way, family law clients were to be offered a holistic service, with the lawyer acting as a ‘case manager’ who helped match services to their client’s individual needs. This article presents data drawn from an evaluation of FAInS, and shows that lawyers did not regularly refer their clients to other services, with referrals largely being limited to mediation. We conclude that family lawyers are not necessarily the most appropriate gatekeepers, and propose a number of alternatives for providing a multi-agency approach to resolving family law issues.
A 350 year drought reconstruction from Alpine tree ring stable isotopes
Authors: Kress Anne , Saurer Matthias , Siegwolf Rolf T. W. , Frank David C. , Esper Jan , Bugmann Harald
Published: May 2010

Climate reconstructions based on stable isotopes in tree rings rely on the assumption that fractionation‐controlling processes are strongly linked to meteorological variables. In this context, we investigated the climate sensitivity of 350 years of carbon and oxygen isotope ratios of tree ring cellulose from European larch obtained at a high‐elevation site in the Swiss Alps (∼2100 m above sea level). Unlike tree ring width and maximum latewood density, which contain only summer temperature information at this site, we found that our stable isotope series reveal additionally to temperature a striking sensitivity to precipitation (mainly for carbon) and sunshine duration (mainly for oxygen) during July and August. A drought index reflecting the combined temperature and precipitation influence provided the most stable correlations over time for the carbon isotope series. All of these climate‐isotope relationships are preserved in the isotope series obtained from younger trees at the same site, while strong intertree correlations further emphasize the high climate sensitivity. We thus present the first carbon‐isotope‐based summer drought reconstruction for the Swiss Alps, which provides new evidence for interannual to long‐term changes in summer regional moisture variability from 1650 to 2004 in Europe, revealing extreme drought summers in the second half of the 18th century and throughout the 20th century.
Relationships between southeastern Australian rainfall and sea surface temperatures examined using a climate model
Authors: Watterson I. G.
Published: May 2010

Rainfall in southeastern Australia has declined in recent years, particularly during austral autumn over the state of Victoria. A recent study suggests that sea surface temperature (SST) variations in both the Indonesian Throughflow (ITF) region and in a meridional dipole in the central Indian Ocean have influenced Victorian late autumn rainfall since 1950. However, it remains unclear to what extent SSTs in these and other regions force such a teleconnection. Analysis of a 1080 year simulation by the climate model CSIRO Mk3.5 shows that the model Victorian rainfall is correlated rather realistically with SSTs but that part of the above relationships is due to the model ENSO. Furthermore, the remote patterns of pressure, rainfall, and land temperature greatly diminish when the data are lagged by 1 month, suggesting that the true forcing by the persisting SSTs is weak. In a series of simulations of the atmospheric Mk3.5 with idealized SST anomalies, raised SSTs to the east of Indonesia lower the simulated Australian rainfall, while those to the west raise it. A positive ITF anomaly lowers pressure over Australia, but with little effect on Victorian rainfall. The meridional dipole and SSTs to the west and southeast of Australia have little direct effect on southeastern Australia in the model. The results suggest that tropical SSTs predominate as an influence on Victorian rainfall. However, the SST indices appear to explain only a fraction of the observed trend, which in the case of decadal means remains within the range of unforced variability simulated by Mk3.5.
Martian dust devil electron avalanche process and associated electrochemistry
Authors: Jackson Telana L. , Farrell William M. , Delory Gregory T. , Nithianandam Jeyasingh
Published: May 2010

Mars' dynamic atmosphere displays localized dust devils and larger, global dust storms. Based on terrestrial analog studies, electrostatic modeling, and laboratory work, these features will contain large electrostatic fields formed via triboelectric processes. In the low‐pressure Martian atmosphere, these fields may create an electron avalanche and collisional plasma due to an increase in electron density driven by the internal electrical forces. To test the hypothesis that an electron avalanche is sustained under these conditions, a self‐consistent atmospheric process model is created including electron impact ionization sources and electron losses via dust absorption, electron dissociation attachment, and electron/ion recombination. This new model is called the Dust Devil Electron Avalanche Model (DDEAM). This model solves simultaneously nine continuity equations describing the evolution of the primary gaseous chemical species involved in the electrochemistry. DDEAM monitors the evolution of the electrons and primary gas constituents, including electron/water interactions. We especially focus on electron dynamics and follow the electrons as they evolve in the E field driven collisional gas. When sources and losses are self‐consistently included in the electron continuity equation, the electron density grows exponentially with increasing electric field, reaching an equilibrium that forms a sustained time‐stable collisional plasma. However, the character of this plasma differs depending upon the assumed growth rate saturation process (chemical saturation versus space charge). DDEAM also shows the possibility of the loss of atmospheric methane as a function of electric field due to electron dissociative attachment of the hydrocarbon. The methane destruction rates are presented and can be included in other larger atmospheric models.
Molecular basis of the head‐to‐tail assembly of giant muscle proteins obscurin‐like 1 and titin
Authors: Sauer Florian , Vahokoski Juha , Song Young‐Hwa , Wilmanns Matthias
Published: May 2010

Large filament proteins in muscle sarcomeres comprise many immunoglobulin‐like domains that provide a molecular platform for self‐assembly and interactions with heterologous protein partners. We have unravelled the molecular basis for the head‐to‐tail interaction of the carboxyl terminus of titin and the amino‐terminus of obscurin‐like‐1 by X‐ray crystallography. The binary complex is formed by a parallel intermolecular β‐sheet that presents a novel immunoglobulin‐like domain‐mediated assembly mechanism in muscle filament proteins. Complementary binding data show that the assembly is entropy‐driven rather than dominated data by specific polar interactions. The assembly observed leads to a V‐shaped zipper‐like arrangement of the two filament proteins.
Thickness dependence study of inorganic CdTe/CdSe solar cells fabricated from colloidal nanoparticle solutions
Authors: Ju Tong , Yang Lily , Carter Sue
Published: May 2010

The thickness dependence of cadmium telluride/cadmium selenide (CdTe/CdSe) heterojunctions is studied in order to maximize the performance of solar cells. The best overall performance of 3.02% efficiency at air mass 1.5 was achieved from a device with 300 nanometers (nm) of sintered CdTe and 100 nm CdSe, using indium tin oxide and evaporated aluminum as the electrodes. In contrast to thin film CdTe solar cells, the power efficiency was strongly dependent on the thickness of the nanoparticle layer, indicating that the device efficiency is limited by charge transport.
The same etchant produces both near-atomically flat and microfaceted Si(100) surfaces: The effects of gas evolution on etch morphology
Authors: Aldinger Brandon S. , Gupta Ankush , Clark Ian T. , Hines Melissa A.
Published: May 2010

The effects of H2 gas evolution during the etching of silicon surfaces by aqueous ammonium fluoride (NH4F) solutions were investigated by scanning tunneling microscopy, atomic force microscopy, optical microscopy, and noncontact profilometry. If H2 bubbles, a reaction product, were removed from the etching surface or if their coalescence was suppressed, near-atomically flat surfaces were produced. Otherwise, the etched surface developed significant roughening on many length scales with several characteristic morphological features, including nested, nearly-concentric circular etch pillars, circular etch pits, and faceted micropits. Mechanisms for the production of all three types of features are proposed. Chemical and physical means of suppressing bubble-induced surface roughening are presented. These results explain the conventional wisdom that aqueous fluoride etchants roughen Si(100) surfaces, in part by promoting the formation of Si{111} microfacets. Although some conditions promote the formation of a high density of {111}-faceted micropits (areal densities of 30%–50% were observed), microfacet formation is not inherent to the atomic-scale reactions. Instead, the microfacets are a direct result of gas evolution during the etching reaction.
The impulsive motion of a small cylinder at an interface
Authors: Vella Dominic , Li Jie
Published: May 2010

We study the unsteady motion caused by an impulse acting at time t=0 on a small cylinder floating horizontally at a liquid–gas interface. This is a model for the impact of a cylinder onto a liquid surface after the initial splash. Following the impulse, the motion of the cylinder is determined by its weight per unit length (pulling it into the bulk liquid) and resistance from the liquid, which acts to keep the cylinder at the interface. The range of cylinder radii r and impact speeds U considered is such that the resistance from the liquid comes from both the interfacial tension and hydrodynamic pressures. We use two theoretical approaches to investigate this problem. In the first, we apply the arbitrary Lagrangian Eulerian (ALE) method developed by Li et al. [“An arbitrary Lagrangian Eulerian method for moving-boundary problems and its application to jumping over water,” J. Comput. Phys. 208, 289 (2005)] to compute the fluid flow caused by the impulse and the (coupled) motion of the cylinder. We show that at early times the interfacial deformation is given by a family of shapes parametrized by r/t2/3. We also find that for a given density and radius there is a critical impulse speed below which the cylinder is captured by the interface and floats but above which it pierces the interface and sinks. Our second theoretical approach is a simplified one in which we assume that the interface is in equilibrium and derive an ordinary differential equation for the motion of the cylinder. Solving this we again find the existence of a critical impulse speed for sinking giving us some quantitative understanding of the results from the ALE simulations. Finally, we compare our theoretical predictions with the results of experiments for cylinder impacts by Vella and Metcalfe [“Surface tension dominated impact,” Phys. Fluids 19, 072108 (2007)]. This comparison suggests that the influence of contact line effects, neglected here, may be important in the transition from floating to sinking.
Reduced bleaching in organic nanofibers by bilayer polymer/oxide coating
Authors: Tavares L. , Kjelstrup-Hansen J. , Rubahn H.-G. , Sturm H.
Published: May 2010

Para-hexaphenylene (p-6P) molecules exhibit a characteristic photoinduced reaction (bleaching) resulting in a decrease in luminescence intensity upon UV light exposure, which could render the technological use of the nanofibers problematic. In order to investigate the photoinduced reaction in nanofibers, optical bleaching experiments have been performed by irradiating both pristine and coated nanofibers with UV light. Oxide coating materials (SiOx and Al2O3) were applied onto p-6P nanofibers. These treatments caused a reduction in the bleaching reaction but in addition, the nanofiber luminescence spectrum was significantly altered. It was observed that some polymer coatings [a statistical copolymer of tetrafluoroethylene and 2,2-bis-trifluoromethyl-4,5-difluoro-1,3-dioxole, P(TFE-PDD), and poly(methyl methacrylate), PMMA] do not interfere with the luminescence spectrum from the p-6P but are not effective in stopping the bleaching. Bilayer coatings with first a polymer material, which should work as a protection layer to avoid modifications of the p-6P luminescence spectrum, and second an oxide layer used as oxygen blocker were tested and it was found that a particular bilayer polymer/oxide combination results in a significant reduction in bleaching without affecting significantly the emission spectrum from the nanofibers.
A simple external resistance heating diamond anvil cell and its application for synchrotron radiation x-ray diffraction
Authors: Fan Dawei , Zhou Wenge , Wei Shuyi , Liu Yonggang , Ma Maining , Xie Hongsen
Published: May 2010

A simple external heating assemblage allowing diamond anvil cell experiments at pressures up to 34 GPa and temperatures up to 653 K was constructed. This cell can be connected to the synchrotron radiation conveniently. The design and construction of this cell are fully described, as well as its applications for x-ray diffraction. Heating is carried out by using an external-heating system, which is made of NiCr resistance wire, and the temperature was measured by a NiCr–NiSi or PtRh–Pt thermocouple. We showed the performance of the new system by introducing the phase transition study of cinnabar (α-HgS) and thermal equation of state study of almandine at high pressure and temperature with this cell.
An in situ examination of atomic layer deposited alumina/InAs(100) interfaces
Authors: Kirk A. P. , Milojevic M. , Kim J. , Wallace R. M.
Published: May 2010

Undoped InAs(100) wafers were either passivated with sulfur from a (NH4)2Sx solution or etched with NH4OH and then characterized with monochromatic x-ray photoelectron spectroscopy (XPS) before and after in situ deposition of Al2O3 by atomic layer deposition. Sulfur passivation minimized oxidation. Trimethyl aluminum (TMA) exposure reduced trivalent indium and arsenic oxidation states. The In1+ chemical state persisted while elemental arsenic remained at the Al2O3/InAs interface prior to TMA exposure and possibly a mixture of As–As and As–Al bonds were present afterwards. The In 3d5/2 peak line shape from bulk InAs differed from previous XPS experiments on epitaxial InxGa1−xAs.
Fast reset and suppressing spontaneous emission of a superconducting qubit
Authors: Reed M. D. , Johnson B. R. , Houck A. A. , DiCarlo L. , Chow J. M. , Schuster D. I. , Frunzio L. , Schoelkopf R. J.
Published: May 2010

Spontaneous emission through a coupled cavity can be a significant decay channel for qubits in circuit quantum electrodynamics. We present a circuit design that effectively eliminates spontaneous emission due to the Purcell effect while maintaining strong coupling to a low-Q cavity. Excellent agreement over a wide range in frequency is found between measured qubit relaxation times and the predictions of a circuit model. Using fast (nanosecond time-scale) flux biasing of the qubit, we demonstrate in situ control of qubit lifetime over a factor of 50. We realize qubit reset with 99.9% fidelity in 120 ns.
Thermal conductivity of graphene ribbons from equilibrium molecular dynamics: Effect of ribbon width, edge roughness, and hydrogen termination
Authors: Evans William J. , Hu Lin , Keblinski Pawel
Published: May 2010

We use equilibrium molecular dynamic simulations to compute thermal conductivity of graphene nanoribbons with smooth and rough edges. We also study effects of hydrogen termination. We find that conductivity is the highest for smooth edges and is essentially the same for zigzag and armchair edges. In the case of rough edges, the thermal conductivity is a strong function of the ribbon width indicating the important effect of phonon scattering from the edge. Hydrogen termination also reduces conductivity by a significant amount.
N,N-Dialkyl-N'-Chlorosulfonyl Chloroformamidines in Heterocyclic Synthesis. Part IX. Novel Triazolo-Fused Thiatriazoles and Pyrazolo-Fused Oxathiazines
Authors: Forsyth Craig M. , Francis Craig L. , Jahangiri Saba , Liepa Andris J. , Perkins Michael V. , Young Anna P.
Published: May 2010

N,N-dialkyl-N′-chlorosulfonyl chloroformamidines 1 reacted with 4-substituted urazoles 2 to give [1,2,4]triazolo[1,2-b][1,2,3,5]thiatriazoles 3 in a selective 1,2-NN dinucleophilic mode of reaction. The reaction of 1 with N
1-substituted pyrazol-5-ones 4 afforded pyrazolo[4,3-e][1,4,3]oxathiazines 5 via selective 1,3-CCO dinucleophilic substitution. Compounds 3 and 5 were the sole products isolated from the respective reactions and both represent new ring systems.
Efficient Alkylation Methods for the Synthesis of Hybrid Fluorocarbon - Hydrocarbon Tetrazoles as Potential Fluorinated Surfactants
Authors: Huang Yangen , Read Roger W. , Wang Xiaobei
Published: May 2010

The first 1,5- and 2,5-disubstituted fluorous tetrazoles are sought as potential surfactants. Direct alkylation of monosubstituted tetrazoles using alkyl iodides and triflates is compared with the Mitsunobu reaction. Mitsunobu conditions provide advantage for perfluoroalkylethylation, in terms of selectivity towards the 2,5-isomers and overall yield, but are not applicable to perfluoroalkylmethylation.
Speciation of Chlorometallate Ionic Liquids Based on Gallium(III) and Indium(III)
Authors: Hardacre Christopher , Murphy Richard W. , Seddon Kenneth R. , Srinivasan Geetha , Swadźba-Kwaśny Małgorzata
Published: May 2010

A range of ionic liquids was prepared by mixing 1-alkyl-3-methylimidazolium chloride with gallium(iii) chloride or indium(iii) chloride in various ratios, producing both acidic and basic compositions. Their speciation was investigated using 71Ga NMR or 115In NMR spectroscopy, as well as extended X-ray absorption fine structure. Polynuclear Lewis acidic anions, [MxCl3x+1]–, were found in chlorogallate(iii) ionic liquids, but not in chloroindate(iii) systems.
Synthesis and Biological Evaluation of a New Family of Constrained Azabicyclic Homocholine Analogues
Authors: Halliday Jill I. , Chebib Mary , McLeod Malcolm D.
Published: May 2010

A family of constrained acylated homocholine analogues have been synthesized, based on the azabicyclic ring scaffold derived from a double-Mannich annulation of cyclic ketones. The short synthetic route allows generation of structural diversity including, variation in the carbocyclic ring size, bridgehead substitution, nitrogen substitution and the ester sidechain. Biological assays on selected analogues demonstrate these compounds are nicotinic acetylcholine receptor (nAChR) antagonists. Several analogues also bind to other neuronal transporter and receptor targets.
Total Synthesis of the Galbulimima Alkaloid (±)-GB 13
Authors: McLachlan Matthew M. W. , O'Connor Patrick D. , Fairweather Kelly A. , Willis Anthony C. , Mander Lewis N.
Published: May 2010

The synthesis of alkaloid GB 13 (4), isolated from the North Australian rain forest tree Galbulimima belgraveana is described. Birch reductive alkylation of 2,5-dimethoxybenzoic acid by 3-methoxybenzyl bromide, followed by an acid-catalyzed cyclization was used to synthesize the [3.3.1]bicyclononane 12. Ring contraction performed on the diazoketone 19 followed by a Diels–Alder reaction generated a pentacyclic intermediate 34 with a carbon skeleton closely resembling the target alkaloid. The surplus nitrile substituent, required for activation and regioselectivity in the Diels–Alder reaction, was removed by treatment with lithium and liquid ammonia. Birch reduction of the aromatic ring could be performed at the same time to give diene 38 and thence enone 41, which was cleaved by means of an Eschenmoser fragmentation. The piperidine ring found in the natural product was formed by reductive cyclization of bis-oxime 49 derived from the alkynyl ketone 48 and the resulting material further elaborated to GB 13.
Visualizing enveloping layer glycans during zebrafish early embryogenesis
Authors: Baskin Jeremy M. , Dehnert Karen W. , Laughlin Scott T. , Amacher Sharon L. , Bertozzi Carolyn R.
Published: May 2010

Developmental events can be monitored at the cellular and molecular levels by using noninvasive imaging techniques. Among the biomolecules that might be targeted for imaging analysis, glycans occupy a privileged position by virtue of their primary location on the cell surface. We previously described a chemical method to image glycans during zebrafish larval development; however, we were unable to detect glycans during the first 24 hours of embryogenesis, a very dynamic period in development. Here we report an approach to the imaging of glycans that enables their visualization in the enveloping layer during the early stages of zebrafish embryogenesis. We microinjected embryos with azidosugars at the one-cell stage, allowed the zebrafish to develop, and detected the metabolically labeled glycans with copper-free click chemistry. Mucin-type O-glycans could be imaged as early as 7 hours postfertilization, during the gastrula stage of development. Additionally, we used a nonmetabolic approach to label sialylated glycans with an independent chemistry, enabling the simultaneous imaging of these two distinct classes of glycans. Imaging analysis of glycan trafficking revealed dramatic reorganization of glycans on the second time scale, including rapid migration to the cleavage furrow of mitotic cells. These studies yield insight into the biosynthesis and dynamics of glycans in the enveloping layer during embryogenesis and provide a platform for imaging other biomolecular targets by microinjection of appropriately functionalized biosynthetic precursors.
The Discovery of Argon: A Case for Learning from Data?
Authors: Spanos Aris
Published: May 2010

Rayleigh and Ramsay discovered the inert gas argon in the atmospheric air in 1895 using a carefully designed sequence of experiments guided by an informal statistical analysis of the resulting data. The primary objective of this article is to revisit this remarkable historical episode in order to make a case that the error-statistical perspective can be used to bring out and systematize (not to reconstruct) these scientists't resourceful ways and strategies for detecting and eliminating error, as well as dealing with Duhemian ambiguities and underdetermination problems as they arose in the context of their local research settings.
James Bond and the Barking Dog: Evolution and Extended Cognition
Authors: Shapiro Lawrence
Published: May 2010

Prominent defenders of the extended cognition thesis have looked to evolutionary theory for support. Roughly, the idea is that natural selection leads one to expect that cognitive strategies should exploit the environment, and exploitation of the right sort results in a cognitive system that extends beyond the head of the organism. I argue that proper appreciation of evolutionary theory should create no such expectation. This leaves open whether cognitive systems might in fact bear a relationship to the environment that leads to their extension.
Walsh on Causes and Evolution
Authors: Northcott Robert
Published: May 2010

Denis Walsh has written a striking new defense in this journal of the statisticalist (i.e., noncausalist) position regarding the forces of evolution. I defend the causalist view against his new objections. I argue that the heart of the issue lies in the nature of nonadditive causation. Detailed consideration of that turns out to defuse Walsh's ‘description-dependence’ critique of causalism. Nevertheless, the critique does suggest a basis for reconciliation between the two competing views.