bluuebunny/crossref_metadata_2025 huggingface dataset:
Flaxseed cotyledon fraction reduces tumour growth and sensitises tamoxifen treatment of human breast cancer xenograft (MCF-7) in athymic mice
Authors: Chen Jianmin , Saggar Jasdeep K. , Corey Paul , Thompson Lilian U.
Published: December 2010

Dietary flaxseed (FS) inhibited the growth of human breast tumours and enhanced the effectiveness of tamoxifen (TAM) in athymic mice with low oestradiol (E2) levels. The present study determined whether then-3 fatty acid-rich cotyledon fraction of FS (FC), alone or in combination with TAM, has a similar effect and thus can substitute for FS. In a 2 × 2 factorial design, ovariectomised mice with established oestrogen receptor (ER)-positive breast tumours (MCF-7) were treated as follows: groups 1 and 2 were fed the basal diet (BD, control) and FC diet (82 g FC/kg), respectively. Groups 3 and 4 with TAM implants (5 mg) were fed the BD and FC diet, respectively. At 8 weeks post-treatment, mice were euthanised, and tumours were analysed by immunohistochemistry and real-time PCR. BD, FC and FC/TAM groups significantly decreased tumour area, but the TAM group did not. Tumour regression in the FC/TAM group was greater compared to the TAM group. FC lowered cell proliferation but had no effect on apoptosis; the opposite was observed with TAM. FC suppressed mRNA expressions of pS2 and insulin-like growth factor 1 receptor (IGF-1R) and protein expressions of ERα, phosphospecific ERα, human epidermal growth factor receptor 2 (HER2), phosphospecific HER2 (pHER2) and amplified in breast 1 (AIB1), while TAM up-regulated mRNA expressions of Bcl2, progesterone receptor and IGF-1R and protein expression of pHER2, and down-regulated ERβ mRNA. FC modulated the effect of TAM on tumour growth biomarkers. In conclusion, FC reduced the growth of ER+human breast tumours at low circulating E2, alone and combined with TAM, in part through modulation of ER −  and growth factor-mediated signalling pathways; it may substitute for FS in increasing the effectiveness of TAM.
Effects of cannabinoids on neuropeptide Y and β-endorphin expression in the rat hypothalamic arcuate nucleus
Authors: Bakkali-Kassemi Lamiae , El Ouezzani Seloua , Magoul Rabia , Merroun Ikram , Lopez-Jurado Maria , Errami Mohammed
Published: December 2010

The control of appetite and satiety is extremely complex and involves a balance between neurotransmitters and neuropeptides to stimulate and/or inhibit feeding behaviour. The effect of cannabinoids on food intake is well established, but little is known about the mechanism of action underlying their activity. In the present report, the effect of pharmacological manipulation of the cannabinoid receptor on the expression of hypothalamic neuropeptides is investigated. We used an immunohistochemical approach to examine the effect of intracerebroventricular administration of the cannabinoid receptor agonist WIN55,212-2 and the inverse agonist AM251 on neuropeptide Y (NPY) and the β-endorphin (β-end) neuronal hypothalamic systems. Double immunohistochemistry (c-fos/β-end) was used to assess the number of β-end neurons activated by the cannabinoid agonist. The present results showed that 1 μg WIN 55,212-2 increases β-end immunoreactivity within the arcuate nucleus while no significant changes were noted in the NPY-immunoreactive nerve fibres network in comparison to the control group. Injection of 1 μg AM251 decreases both NPY and β-end immunoreactivity within the arcuate nucleus. The number of β-end neurons exhibiting c-fos increased significantly in WIN 55,212-2 compared with the control group. These results suggest that cannabinoids affect the expression of hypothalamic neuropeptides, notably the NPY and β-end systems, which may have implications in the orexigenic action of cannabinoids.
Weimar Germany and its Histories
Authors: Weitz Eric D.
Published: December 2010

Years later, after the catastrophes of the Third Reich and World War II, Arnold Zweig remembered how he had returned home from another disaster, World War I. “With what hopes had we come back from the war!” he wrote. Zweig recalled not just the catastrophe of total war, but also the élan of revolution. Like a demon, he threw himself into politics, then into his writing. “I have big works, wild works, great well-formed, monumental works in my head!,” he wrote to his friend Helene Weyl in April 1919. “I want to write! Everything that I have done up until now is just a preamble.” And it was not to be “normal” writing. The times were of galloping stallions and wide-open furrows, and talent was everywhere. War and revolution had drawn people out of the confining security of bourgeois life. “The times have once again placed adventure in the center of daily life, making possible once more the great novel and the great story.”
Heroes and Martyrs of the Republic: ReichsbannerGeschichtspolitikin Weimar Germany
Authors: Bryden Eric
Published: December 2010

It is common knowledge among historians of Germany that the nationalist right frequently and loudly argued that the Weimar Republic, throughout its fourteen-year existence, was fundamentally “un-German,” foreign in inspiration, and resting on a foundation of internationalist political thought. Indeed, in the opinion of many on the more traditionally minded right, such as theDeutsche Volkspartei(DVP) and theDeutschnationale Volkspartei(DNVP), monarchy corresponded most closely to Germany's historical development and German national character as a form of state. In large part due to Weimar's ultimate demise at the hands of the conservative and radical right, these sentiments have received the lion's share of scholarly attention. Curiously, however, the republican response to these charges remains less well explored.
Regular/irregular is not the whole story: the role of frequency and generalization in the acquisition of German past participle inflection
Authors: SZAGUN GISELA
Published: December 2010

The acquisition of German participle inflection was investigated using spontaneous speech samples from six children between 1 ; 4 and 3 ; 8 and ten children between 1 ; 4 and 2 ; 10 recorded longitudinally at regular intervals. Child-directed speech was also analyzed. In adult and child speech weak participles were significantly more frequent than strong participles. Children's errors involved all elements of participle marking. All error types, including over-regularization, occurred from the beginning alongside correct forms. Errors decreased significantly over age. Over-regularization in the sense of -taffixation on strong verbs was significantly more frequent than erroneous -ensuffixation on weak verbs but not than prefix and suffix omission. On participles with stem vowel change erroneous stem vowel was significantly more frequent than correct stem vowel with suffix error alone. Error patterns are explained in terms of frequencies, and participle inflection being learned as part of general verb inflection.
Transportation Use in Community-Dwelling Older Adults: Association with Participation and Leisure Activities
Authors: Dahan-Oliel Noémi , Mazer Barbara , Gélinas Isabelle , Dobbs Bonnie , Lefebvre Hélène
Published: December 2010

Les objectifs de cette étude étaient de comparer la participation selon les moyens de transport utilisés, et d’estimer l’association entre le transport, les facteurs personnels et environnementaux avec la participation chez les personnes âgées habitant dans la communauté. Les participants incluaient 90 adultes âgés de 65 ans et plus (moyenne d’âge = 76.3 ans ; ET = 7.7). Ils étaient classifiés selon le moyen de transport utilisé le plus souvent: conducteur, passager, transport en commun, marche, ou transport adapté/taxi. La participation a été mesuré avec le « Craig Handicap Assessment and Reporting Technique (CHART) » et le « Nottingham Leisure Questionnaire (NLQ) ». Somme toute, les résultats ont indiqué que les conducteurs, utilisateurs de transport en commun et ceux qui utilisaient la marche avaient des niveaux de participation plus élevés comparativement aux passagers et utilisateurs de transport adapté/taxi. Cette étude suggère que les cliniciens devraient considérer l’utilisation du transport chez les personnes âgées afin d’encourager et de maximiser leur participation.
La souffrance en lien avec les écueils de la communication chez les femmes âgées atteintes de cancer incurable
Authors: Bourgeois-Guérin Valérie
Published: December 2010

Among the older population in Canada, the majority of whom are women, incurable cancer is rampant. Having incurable cancer often implies suffering. Studies reveal that communication with one’s circle is therefore often arduous, leading us to believe that it can cause suffering. To our knowledge, there has been no research that specifically explores the suffering related to communication among older women with incurable cancer: this will be the objective of our article.

This exploratory qualitative research is in humanistic psychology. It is based on a phenomenological analysis of the conceptual categories that emerged from 19 semi-structured interviews among 10 women aged 65 years and over with incurable cancer.

The results reveal both the dynamic of silence, desired in order to prevent increased suffering, and sometimes imposed and a source of further suffering. They also reveal that the absence of listening, the imposition of silence, and the minimization of what these women say, also cause suffering. The consequences of disclosing one’s illness and its suffering are also explored.
Beliefs about Aging and Alzheimer’s Disease in Three Domains
Authors: Rust Tiana B. , Kwong See Sheree T.
Published: December 2010

Cette étude des mesures répétées a examiné les croyances des étudiants de premier cycle concernant le vieillissement et la maladie d’Alzheimer (MA) dans les domaines cognitifs, physiques et socials. Les étudiants ont evalué les personnes typiques de 25 ans (cible jeune), les personnes typiques de 75 ans (cible vieux), et les personnes institutionnalisées typiques avec MA (MA cible) sur 46 déclarations sur les capacités cognitives, physiques et sociaux. Croyances sur le vieillissement se sont avérés pour être généralement négative dans les domaines cognitifs et physiques mais positive dans le domaine social, ce qui est compatible avec la littérature des stéréo-types de l’âge. La maladie d’Alzheimer est perçu comme une maladie essentiellement de l’esprit, mais on croit, qu’en comparaison avec les différences prévues au vieillissement, que la prouesse physique est renforcée. Documenter les croyances, un premier pas vers la modification des comportements stéréotypes, pourrait avoir des effets significatifs sur la santé et le bien-être des personnes agées et des personnes atteintes de MA.
The Role of Languaging in Creating Zones of Proximal Development (ZPDs): A Long-Term Care Resident Interacts with a Researcher
Authors: Lapkin Sharon , Swain Merrill , Psyllakis Paula
Published: December 2010

“Cet article traite de la question: Quel est le rôle du  (la mise en mots) – l’élaboration et l’organisation des processus mentaux supérieures par la langue – dans les zones émergents de développement proximales (ZDPs) co-crée par deux adultes ? » Les deux adultes sont Mike, un résident dans un établissement de soins de longue durée, et un chercheur. Un zone proximale de développement (ZPD) est un processus continu cognitive/affective dans lequel l’apprentissage et le développement se produisent quand les participants interagissent. Ce processus est medié par le langage. Grâce à une analyse microgénétique d’extraits representatifs selectionnés à partir de 11 seances, nous illustrons comment les interactions entre Mike et le chercheur ont crée un contexte affectif et positif qui offre des possibilités multiples de ZDPs à émerger. Comme les ZDPs émergent, nous observons comment le  rassemble les composantes cognitives et affectives essentielles afin que le développement du participant peut continuer. Au fil du temps, Mike récupère l’expertise perdu et entreprend de nouveaux défis cognitivement complexes. Les résultats pour Mike comprennent à la fois le développement cognitif et un meilleur amour-propre.
Antimicrobial resistance ofEscherichia coliandEnterococcus faecalisin housed laying-hen flocks in Europe
Authors: VAN HOOREBEKE S. , VAN IMMERSEEL F. , BERGE A. C. , PERSOONS D. , SCHULZ J. , HARTUNG J. , HARISBERGER M. , REGULA G. , BARCO L. , RICCI A. , DE VYLDER J. , DUCATELLE R. , HAESEBROUCK F. , DEWULF J.
Published: December 2010

The aim of this study was to determine the potential association between housing type and multiple drug resistance (MDR) inEscherichia coliandEnterococcus faecalisisolates recovered from 283 laying-hen flocks. In each flock, a cloacal swab from four hens was collected and produced 1102E. coliand 792E. faecalisisolates. Broth microdilution was used to test susceptibility to antimicrobials. Country and housing type interacted differently with the MDR levels of both species. In theE. colimodel, housing in a raised-floor system was associated with an increased risk of MDR compared to the conventional battery system [odds ratio (OR) 2·12, 95% confidence interval (CI) 1·13–3·97)]. In theE. faecalismodel the MDR levels were lower in free-range systems than in conventional battery cages (OR 0·51, 95% CI 0·27–0·94). In Belgium, ceftiofur-resistantE. coliisolates were more numerous than in the other countries.
The impact of maternal cortisol concentrations on child arterial elasticity
Authors: Rondó P. H. C. , Pereira J. A. , Lemos J. O. , Ferreira R. F.
Published: December 2010

Epidemiological studies suggest that glucocorticoid excess in the fetus may contribute to the pathophysiology of cardiovascular diseases in adulthood. However, the impact of maternal glucocorticoid on the cardiovascular system of the offspring has not been much explored in studies involving humans, especially in childhood. The objective of this study was to assess the influence of maternal cortisol concentrations on child arterial elasticity. One hundred and thirty pregnant women followed from 1997 to 2000, and respective children 5–7 years of age followed from 2004 to 2006 were included in the study. Maternal cortisol was determined in saliva by an enzyme immunoassay utilizing the mean concentration of nine samples of saliva. Arterial elasticity was assessed by the large artery elasticity index (LAEI; the capacitive elasticity of large arteries) by recording radial artery pulse wave, utilizing the equipment HDI/PulseWave CR-2000 Cardiovascular Profiling System®. The nutritional status of the children was determined by the body mass index (BMI). Insulin concentration was assessed by chemiluminescence, and insulin resistance by the homeostasis model assessment. Blood glucose, total cholesterol and fractions (LDL-c and HDL-c) and triglyceride concentrations were determined by automated enzymatic methods. The association between maternal cortisol and child arterial elasticity was assessed by multivariate linear regression analysis. There was a statistically significant association between maternal cortisol and LAEI (P= 0.02), controlling for birth weight, age, BMI and HDL-c of the children. This study suggests that exposure to higher glucocorticoid concentrations in the prenatal period is associated to lower arterial elasticity in childhood, an earlier cardiovascular risk marker.
Carbon dioxide effects of Antarctic stratification, North Atlantic Intermediate Water formation, and subantarctic nutrient drawdown during the last ice age: Diagnosis and synthesis in a geochemical box model
Authors: Hain Mathis P. , Sigman Daniel M. , Haug Gerald H.
Published: December 2010

In a box model synthesis of Southern Ocean and North Atlantic mechanisms for lowering CO2 during ice ages, the CO2 changes are parsed into their component geochemical causes, including the soft‐tissue pump, the carbonate pump, and whole ocean alkalinity. When the mechanisms are applied together, their interactions greatly modify the net CO2 change. Combining the Antarctic mechanisms (stratification, nutrient drawdown, and sea ice cover) within bounds set by observations decreases CO2 by no more than 36 ppm, a drawdown that could be caused by any one of these mechanisms in isolation. However, these Antarctic changes reverse the CO2 effect of the observed ice age shoaling of North Atlantic overturning: in isolation, the shoaling raises CO2 by 16 ppm, but alongside the Antarctic changes, it lowers CO2 by an additional 13 ppm, a 29 ppm synergy. The total CO2 decrease does not reach 80 ppm, partly because Antarctic stratification, Antarctic sea ice cover, and the shoaling of North Atlantic overturning all strengthen the sequestration of alkalinity in the deepest ocean, which increases CO2 both by itself and by decreasing whole ocean alkalinity. Increased nutrient consumption in the sub‐Antarctic causes as much as an additional 35 ppm CO2 decrease, interacting minimally with the other changes. With its inclusion, the lowest ice age CO2 levels are within reach. These findings may bear on the two‐stepped CO2 decrease of the last ice age.
Precise determination of the open ocean 234U/238U composition
Authors: Andersen M. B. , Stirling C. H. , Zimmermann B. , Halliday A. N.
Published: December 2010

Uranium has a long residence time in the open oceans, and therefore, its salinity‐normalized U concentration and 234U/238U activity ratio (expressed herein as δ234U, the ‰ deviation from secular equilibrium) are assumed to be uniform. The marine 234U/238U activity ratio is currently in radioactive disequilibrium and shows a ∼15% excess of 234U with respect to the secular equilibrium value due to continuous input from riverine sources. Knowledge of the marine δ234U, and how it has evolved through the Quaternary, is important for validating age accuracy in the U series dating of marine carbonates, which is increasingly relied upon for providing a chronological basis in paleoclimate research. However, accurate and precise measurements of δ234U are technically difficult. Thus, existing compilations of the open ocean δ234U value vary by up to ∼10‰, and the assumed uniformity in the oceanic δ234U remains to be confirmed. Using MC‐ICPMS techniques and a suite of multiple Faraday cups instead of the typical configurations based on a combined Faraday cup–multiplier array, a long‐term reproducibility of better than ±0.3‰ (2σ) is achieved for δ234U measurements. Applying these very high precision techniques to open ocean seawater samples, an average δ234U of 146.8 ± 0.1‰ (2σm, n = 19) is obtained. These high‐precision seawater measurements yield an external reproducibility of better than ±0.4‰ (2σ) and show that the open oceans have a uniform δ234U on the sub‐‰ level. These new data constrain the vertical mixing time of the open oceans to less than 1000 years.
Relocation and characterization of the August 2009 microearthquake swarm above the Socorro magma body in the central Rio Grande Rift
Authors: Ruhl Christine , Bilek Susan L. , Stankova‐Pursley Jana
Published: December 2010

Earthquake swarms, often attributed to magma or fluid movement in the uppermost crust, have differing statistics depending on tectonic setting, with volcanic swarms producing b‐values of up to 2.5 and continental rift swarms having b‐values ∼0.8‐1. Along the Rio Grande continental rift (RGR) in the western US, earthquake swarms have occurred in the area of the Socorro Magma Body (SMB), including the 2009 swarm of 431 events (magnitudes −1.0 to 2.5) over 26 days. We characterize the 2009 swarm to define spatial and temporal patterns to help understand the role of the SMB on the swarm. Our relocations suggest a small seismogenic volume of 34.5 km3 and focal mechanisms of the largest events are consistent with regional stress patterns. The b‐value of 0.9 is more characteristic of continental rift zones than volcanic swarms, suggesting more emphasis on the preexisting highly fractured crust rather than direct influence of magmatic movement.
Present‐Day Volcanism on Venus: Evidence from Microwave Radiometry
Authors: Bondarenko N. V. , Head J. W. , Ivanov M. A.
Published: December 2010

We present new evidence for volcanic eruptions and lava flow emplacement on Venus within the last several decades. An integrated study of a radar‐dark lava flow unit in Bereghinia Planitia on Venus (∼28°E, ∼39°N) based on Magellan data obtained in 1993 reveals a significant apparent microwave thermal emission excess, consistent with increased subsurface temperature due to very recent lava flow emplacement. The flow unit occupies the stratigraphically youngest position in the area and in part is more than 15 years old because it was also observed in the radar map obtained by Pioneer‐Venus in 1978. Analysis of lava flow cooling rates and geological characteristics point to flow material of mafic composition. Future missions can employ this microwave radiometry technique to search for and monitor active volcanism on Venus.
Dual scaling for self‐organized critical models of the magnetosphere
Authors: Vallières‐Nollet M.‐A. , Charbonneau P. , Uritsky V. , Donovan E. , Liu W.
Published: December 2010

The central plasma sheet is a complex magnetized plasma structure located in the equatorial plane of the magnetotail from where substorms are believed to originate. Dynamically, it may behave like a self‐organized critical (SOC) system, driven by the slow energy input of the solar wind. The power law distributions for the sizes, energies, and durations of substorms that are reflected in observations can be reproduced using such SOC models. However, the expected scale invariance does not seem to hold for all scale ranges and observables. Recent observations of all‐sky auroras have suggested a dual regime, where small and large events scale as different power laws, the smaller events having a steeper slope. On the other hand, scale‐dependent substorm behavior can materialize as a consequence of an energy loading‐unloading cycle. Accordingly, we designed a 2‐D SOC model subject to global deterministic driving and a nonconservative redistribution law. This model can reproduce the coexistence of two scaling regimes, with the second regime appearing as a consequence of the enhanced spatial development of avalanches caused by a higher spatial intermittency in the energy gradients. Thresholded interevent waiting time statistics showed a well‐defined peak with an exponential tail, consistent with observations and the expected dynamics of a loading‐unloading cycle. Finally, we show that the coherency index extracted from the simulations decreases prior to large avalanches, as is in fact observed in auroral arcs. This suggests that the coherency index may be a useful substorm predictor.
Medical Doctors Turn to Unions
Authors: Liebowitz Barry
Published: December 2010

The growing power of managed care companies to dictate services and working conditions of physicians is contributing to unprecedented interest in joining unions.
Active control of thermoacoustic amplification in an annular engine
Authors: Desjouy C. , Penelet G. , Lotton P.
Published: December 2010

In this paper, a new method is proposed to control the thermoacoustic amplification in thermoacoustic engines. This method, based on the active control of the spatial distribution of the acoustic field by means of auxiliary acoustic sources, is applied here to an annular thermoacoustic engine. Two auxiliary acoustic sources are used to tune the spatial distribution of the sound field in the engine in such a way that the thermal-to-acoustic energy conversion occurring into the thermoacoustic core is maximized. An experimental study of this device is proposed, which should be considered as a proof-of-concept study, aiming at demonstrating that the addition of auxiliary acoustic sources can be used advantageously to improve the efficiency of thermoacoustic engines. The overall device is characterized below and above the onset of thermoacoustic instability. It is demonstrated that below the onset of thermoacoustic instability, there exists an optimum phase shift between the auxiliary sources which maximizes the acoustic power available in the annular waveguide. When the device is operated above the onset of thermoacoustic instability, it is demonstrated that the appropriate tuning of the two auxiliary sources enables to improve significantly the acoustic work produced into the engine (compared to the case without active control), that the additional output acoustic power is significantly larger than the input electric power supplied to the acoustic sources, and that the overall efficiency of the engine is thus significantly increased. A discussion about the applicability of this new method for the improvement of actual, high power thermoacoustic engines is also provided.
Eliminating thickness dependence of critical current density in YBa2Cu3O7−x films with aligned BaZrO3 nanorods
Authors: Wang Xiang , Baca F. Javier , Emergo Rose L. S. , Wu Judy Z. , Haugan Timothy J. , Barnes Paul N.
Published: December 2010

The thickness dependence of critical current density (Jc) has been investigated in YBa2Cu3O7−x films with BaZrO3 (BZO) nanorods (YBCO/BZO) aligned along the film normal. With the presence of linear defects in the YBCO/BZO films, the thickness dependence of Jc becomes negligible at self field and weak applied magnetic field (H), suggesting these linear defects playing a key role to the elimination of the thickness dependence of Jc. The effect of temperature (T) and H on Jc thickness dependence have been investigated and comparisons have been made between YBCO and YBCO/BZO samples. Since BZO nanorods alignment is greatly influenced by growth temperature, the quantitative difference in terms of nanorod’s density and average length is reflected on Jc angular dependence of H and Jc thickness dependence as thermally assisted flux motion (TAFM) becomes important above a threshold H determined by the BZO nanorod density. With further increasing H, a monotonically increasing Jc vs. thickness trend was observed in YBCO/BZO films, in contrast to an opposite trend when collective pinning is dominant. This result suggests the thickness dependence of Jc is dictated by the microstructure and hence pinning mechanism in YBCO films.
Poroelasticity of a covalently crosslinked alginate hydrogel under compression
Authors: Cai Sengqiang , Hu Yuhang , Zhao Xuanhe , Suo Zhigang
Published: December 2010

This paper studies the poroelastic behavior of an alginate hydrogel by a combination of theory and experiment. The gel—covalently crosslinked, submerged in water, and fully swollen—is suddenly compressed between two parallel plates. The gap between the plates is held constant subsequently, and the force on the plate relaxes while water in the gel migrates. This experiment is analyzed by using the theory of linear poroelasticity. A comparison of the relaxation curve recorded in the experiment and that derived from the theory determines the elastic constants and the permeability of the gel. The material constants so determined agree well with those determined by using a recently developed indentation method. Furthermore, during relaxation, the concentration of water in the gel is inhomogeneous, resulting in tensile hoop stresses near the edge of the gel, and possibly causing the gel to fracture.
Readout-power heating and hysteretic switching between thermal quasiparticle states in kinetic inductance detectors
Authors: de Visser P. J. , Withington S. , Goldie D. J.
Published: December 2010

A model is presented for readout-power heating in kinetic inductance detectors. It is shown that the power dissipated by the readout signal can cause the temperature of the quasiparticle system in the superconducting resonator to switch between well-defined states. At low readout powers, only a single solution to the heat balance equation exists, and the resonance curve merely distorts as the readout power is increased. At high readout powers, three states exist, two of which are stable, and the resonance curve shows hysteretic switching. The power threshold for switching depends on the geometry and material used but is typically around −70 dBm for Aluminum resonators. A comprehensive set of simulations is reported, and a detailed account of the switching process is given. Experimental results are also shown, which are in strong qualitative agreement with the simulations. The general features of the model are independent of the precise cooling function, and are even applicable for resonators on suspended, thermally isolated, dielectric membranes, where an increase in quasiparticle lifetime is expected. We discuss various extensions to the technique, including the possibility of recovering the cooling function from large-signal measurements of the resonance curve.
Stable bipolar surface potential behavior of copper-doped zinc oxide films studied by Kelvin probe force microscopy
Authors: Wong Meng Fei , Herng Tun Seng , Zhang Zhongkun , Zeng Kaiyang , Ding Jun
Published: December 2010

The surface potential of undoped and copper-doped zinc oxide (ZnO:Cu) films has been studied using the Kelvin probe force microscopy at ambient condition. In contrast to the undoped ZnO with unipolar behavior, the ZnO:Cu film exhibits a bipolar surface potential behavior under a dc bias. The localized hole trapping phenomenon is attributed to the presence of Cu ions in ZnO films. With an appropriate amount of the Cu ions (∼8 at. %), the charge trapping is reasonably stable over a period of 20 h, which can be associated with the presence of oxygen vacancies. This coexistence of Cu ions and oxygen vacancies in ZnO gives rise to stable bipolar behavior, paving way to potential charge storage application.
Nongeminate carrier recombination rates in organic solar cells
Authors: Lombardo Christopher , Dodabalapur Ananth
Published: December 2010

Ambipolar organic thin-film transistors and lateral resistor structures have been used to study the transport of charge carriers in bulk heterojunction (BHJ) organic photovoltaic devices. Active layers of a phase-separated blend of poly(3-hexylthiophene) and [6,6]-phenyl C61-butyric acid methyl ester were chosen due to their wide use in BHJ solar cell devices. A new method for determining nongeminate recombination rates is reported. Field dependent measurements of the recombination rate show that recombination decreases with increasing electric field.
Electronic properties of metal-semiconductor and metal-oxide-semiconductor structures composed of carbon nanotube film on silicon
Authors: Behnam Ashkan , Radhakrishna Nischal Arkali , Wu Zhuangchun , Ural Ant
Published: December 2010

We fabricate and experimentally characterize the electrical properties of metal-semiconductor (MS) and metal-oxide-semiconductor (MOS) structures where the metal is single-walled carbon nanotube (CNT) film and the semiconductor is a Si substrate. Our results suggest that for the MS devices thermionic emission is the main high-temperature current transport mechanism, while tunneling becomes the dominant mechanism for MOS devices with thermally grown thin oxide layers between the CNT film and Si. In addition, the CNT film workfunction, a key parameter for the performance of CNT film-based devices, is obtained from the capacitance-voltage measurements on the MOS structures.
High permittivity Bi24Fe2O39 thin films prepared by a low temperature process
Authors: Zhu X. H. , Defaÿ E. , Lee Y. , André B. , Aïd M. , Zhu J. L. , Xiao D. Q. , Zhu J. G.
Published: December 2010

High permittivity Bi24Fe2O39 (BFO) thin films have been deposited on platinized silicon substrates by a low temperature process combining rf magnetron sputtering at room temperature and postdeposition annealing at 450 °C. A nearly pure tetragonal crystal structure with highly (201)-preferred orientation, determined by x-ray diffraction, was formed in the BFO thin film. The BFO film not only exhibits high dielectric permittivity (εr=113) and relatively low loss tangent (tan δ=0.012), but also shows a fairly small quadratic voltage coefficient of capacitance (α∼800 ppm/V2) and a small temperature coefficient of capacitance (αT∼790 ppm/°C). Moreover, the leakage current density, obeying the Fowler–Nordheim tunneling mechanism, remains at a reasonably low level with the increase in applied electric field (J∼10−6–10−4 A/cm2 under E=400 kV/cm). These attractive dielectric and electrical properties make the low temperature processed Bi24Fe2O39 thin film a promising candidate for high-k dielectric applications in silicon-based integrated circuits.
Numerical study of a droplet migration induced by combined thermocapillary-buoyancy convection
Authors: Nguyen Huy-Bich , Chen Jyh-Chen
Published: December 2010

Numerical computations have been performed to study the effects of thermocapillary convection and buoyancy convection, and free surface deformation induced by gravity on the migration behavior of a liquid droplet on a horizontal solid surface subjected to a uniform temperature gradient. Investigations are carried out by solving the Navier–Stokes equations coupled with the energy equation through the finite element method. The combined thermocapillary and buoyancy force driven convection produces complex dynamic behavior of fluid motion inside the droplet. The net momentum generated by a pair of asymmetric thermocapillary convection vortices inside the droplet drives the droplet to move in both small and middle droplet sized regimes. In the small sized regime, the quasisteady migration speed of the droplet is mostly linearly proportional to its size because of the stronger net thermocapillary momentum. When the droplet is in the middle sized regime, its quasisteady migration speed reaches a maximum, but this is gradually reduced as the droplet size increases due to the suppression of the net thermocapillary momentum by the buoyancy force. In the large droplet sized regime, two pairs of convection vortices exist inside the droplet as a result of the appearance of the buoyancy-driven convection accompanying the thermocapillary convection. The quasisteady migration speed quickly diminishes mainly due to the reduction of the net thermocapillary momentum from the stronger buoyancy convection.
Small amplitude dust ion-acoustic solitary waves and double layers in a dusty plasma with flat-topped electron distribution
Authors: Alinejad H. , Mamun A. A.
Published: December 2010

The properties of small but finite amplitude dust ion-acoustic (DIA) solitary waves (SWs) as well double layers (DLs) in a dusty plasma containing warm adiabatic ions, electrons following flat-topped velocity distribution, and arbitrarily (positively or negatively) charged immobile dust are studied. The effects of ion-temperature, resonant electrons, and dust number density are found to significantly modify the criteria for the existence of the DIA SWs and DLs, as well as significantly modify their basic features. It is also shown that the ion-temperature reduces the possibility for the formation of these localized structures, and that their amplitude decreases (increases) with the increase in the negative (positive) dust number density.
A framework to diagnose barriers to climate change adaptation
Authors: Moser Susanne C. , Ekstrom Julia A.
Published: December 2010

This article presents a systematic framework to identify barriers that may impede the process of adaptation to climate change. The framework targets the process of
planned
adaptation and focuses on potentially challenging but malleable barriers. Three key sets of components create the architecture for the framework. First, a staged depiction of an idealized, rational approach to adaptation decision-making makes up the process component. Second, a set of interconnected structural elements includes the actors, the larger context in which they function (e.g., governance), and the object on which they act (the system of concern that is exposed to climate change). At each of these stages, we ask (
i
) what could impede the adaptation process and (
ii
) how do the actors, context, and system of concern contribute to the barrier. To facilitate the identification of barriers, we provide a series of diagnostic questions. Third, the framework is completed by a simple matrix to help locate points of intervention to overcome a given barrier. It provides a systematic starting point for answering critical questions about how to support climate change adaptation at all levels of decision-making.
Mycobacterium tuberculosisevades host immunity by recruiting mesenchymal stem cells
Authors: Raghuvanshi Shilpa , Sharma Pawan , Singh Sarman , Van Kaer Luc , Das Gobardhan
Published: December 2010

Tuberculosis (TB) is the cause of 2 million deaths each year, which is the second highest cause of mortality from a single infectious disease worldwide. Resistance of these organisms to drugs has emerged as an important health concern. Alternative approaches to the prevention and treatment of tuberculosis are therefore urgently needed. Despite the generation of robust host immune responses,Mycobacterium tuberculosis(M. tb) successfully evades host immunity and establishes a persistent infection. The mechanism(s) by whichM. tuberculosismanages to persist in the face of potent host immune responses remain(s) incompletely understood. Here, we demonstrate thatM. tbsuppresses T-lymphocyte responses by recruiting mesenchymal stem cells (MSCs) to the site of infection. We found that MSCs infiltrated tissues in mice containingM. tborganisms and T lymphocytes. We further demonstrate that MSCs suppressed T-cell responses by producing nitric oxide. Our findings reveal a key role of MSCs in the capacity ofM. tbto evade host immune responses and identify these cells as unique targets for therapeutic intervention in tuberculosis.
Structural insights into the activation mechanism of melibiose permease by sodium binding
Authors: Granell Meritxell , León Xavier , Leblanc Gérard , Padrós Esteve , Lórenz-Fonfría Víctor A.
Published: December 2010

The melibiose carrier from
Escherichia coli
(MelB) couples the accumulation of the disaccharide melibiose to the downhill entry of H
+
, Na
+
, or Li
+
. In this work, substrate-induced FTIR difference spectroscopy was used in combination with fluorescence spectroscopy to quantitatively compare the conformational properties of MelB mutants, implicated previously in sodium binding, with those of a fully functional Cys-less MelB permease. The results first suggest that Asp55 and Asp59 are essential ligands for Na
+
binding. Secondly, though Asp124 is not essential for Na
+
binding, this acidic residue may play a critical role, possibly by its interaction with the bound cation, in the full Na
+
-induced conformational changes required for efficient coupling between the ion- and sugar-binding sites; this residue may also be a sugar ligand. Thirdly, Asp19 does not participate in Na
+
binding but it is a melibiose ligand. The location of these residues in two independent threading models of MelB is consistent with their proposed role.
Pericytes in capillaries are contractile in vivo, but arterioles mediate functional hyperemia in the mouse brain
Authors: Fernández-Klett Francisco , Offenhauser Nikolas , Dirnagl Ulrich , Priller Josef , Lindauer Ute
Published: December 2010

Modern functional imaging techniques of the brain measure local hemodynamic responses evoked by neuronal activity. Capillary pericytes recently were suggested to mediate neurovascular coupling in brain slices, but their role in vivo remains unexplored. We used two-photon microscopy to study in real time pericytes and the dynamic changes of capillary diameter and blood flow in the cortex of anesthetized mice, as well as in brain slices. The thromboxane A
2
analog, 9,11-dideoxy-9α,11α-methanoepoxy Prostaglandin F2α (U46619), induced constrictions in the vicinity of pericytes in a fraction of capillaries, whereas others dilated. The changes in vessel diameter resulted in changes in capillary red blood cell (RBC) flow. In contrast, during brief epochs of seizure activity elicited by local administration of the GABA
A
receptor antagonist, bicuculline, capillary RBC flow increased without pericyte-induced capillary diameter changes. Precapillary arterioles were the smallest vessels to dilate, together with penetrating and pial arterioles. Our results provide in vivo evidence that pericytes can modulate capillary blood flow in the brain, which may be important under pathological conditions. However, our data suggest that precapillary and penetrating arterioles, rather than pericytes in capillaries, are responsible for the blood flow increase induced by neural activity.
Mechanism for the inhibition of the carboxyltransferase domain of acetyl-coenzyme A carboxylase by pinoxaden
Authors: Yu Linda P. C. , Kim Yi Seul , Tong Liang
Published: December 2010

Acetyl-CoA carboxylases (ACCs) are crucial metabolic enzymes and have been targeted for drug development against obesity, diabetes, and other diseases. The carboxyltransferase (CT) domain of this enzyme is the site of action for three different classes of herbicides, as represented by haloxyfop, tepraloxydim, and pinoxaden. Our earlier studies have demonstrated that haloxyfop and tepraloxydim bind in the CT active site at the interface of its dimer. However, the two compounds probe distinct regions of the dimer interface, sharing primarily only two common anchoring points of interaction with the enzyme. We report here the crystal structure of the CT domain of yeast ACC in complex with pinoxaden at 2.8-Å resolution. Despite their chemical diversity, pinoxaden has a similar binding mode as tepraloxydim and requires a small conformational change in the dimer interface for binding. Crystal structures of the CT domain in complex with all three classes of herbicides confirm the importance of the two anchoring points for herbicide binding. The structures also provide a foundation for understanding the molecular basis of the herbicide resistance mutations and cross resistance among the herbicides, as well as for the design and development of new inhibitors against plant and human ACCs.
Diffusion-limited retention of porous particles at density interfaces
Authors: Kindler Kolja , Khalili Arzhang , Stocker Roman
Published: December 2010

Downward carbon flux in the ocean is largely governed by particle settling. Most marine particles settle at low Reynolds numbers and are highly porous, yet the fluid dynamics of this regime have remained unexplored. We present results of an experimental investigation of porous particles settling through a density interface at Reynolds numbers between 0.1 and 1. We tracked 100 to 500 μm hydrogel spheres with 95.5% porosity and negligible permeability. We found that a small negative initial excess density

relative to the lower (denser) fluid layer, a common scenario in the ocean, results in long retention times of particles at the interface. We hypothesized that the retention time was determined by the diffusive exchange of the stratifying agent between interstitial and ambient fluid, which increases excess density of particles that have stalled at the interface, enabling their settling to resume. This hypothesis was confirmed by observations, which revealed a quadratic dependence of retention time on particle size, consistent with diffusive exchange. These results demonstrate that porosity can control retention times and therefore accumulation of particles at density interfaces, a mechanism that could underpin the formation of particle layers frequently observed at pycnoclines in the ocean. We estimate retention times of 3 min to 3.3 d for the characteristic size range of marine particles. This enhancement in retention time can affect carbon transformation through increased microbial colonization and utilization of particles and release of dissolved organics. The observed size dependence of the retention time could further contribute to improve quantifications of vertical carbon flux.
Genetic control of immune cell types in fungal disease
Authors: Mayfield Jacob A. , Fontana Mary F. , Rine Jasper
Published: December 2010

Millions of people harbor latent infections of the fungusHistoplasma capsulatum. Such persistent infections represent a stalemate between mechanisms of virulence and the immune response. The differing responses of inbred mouse strains to the same pathogen reflect variation in the genes that control the outcome of infection. Here we show that a 250-fold difference inH. capsulatumsusceptibility between inbred mouse strains is attributable to the genotype at the MHCH2locus. Gene expression analysis of strains varying only at theH2locus identified genotype-specific and genotype-independent expression signatures, including infection-induced genes such as the fungal pattern recognition receptorClec7a. Surprisingly, B-cell–specific gene expression was negatively correlated with fungal burden, whereas neutrophil-specific genes were correlated with superior disease outcome. Indeed, disease outcome improved when B cells were eliminated and neutrophils were more active, a previously unknown aspect of the host response. These data refine the understanding of genetic influences on histoplasmosis, reveal how shifts in the composition of immune cell populations compel different disease outcomes, and uncover how innate immunity modulation alters histoplasmosis.
Exquisite sensitivity to subsecond, picomolar nitric oxide transients conferred on cells by guanylyl cyclase-coupled receptors
Authors: Batchelor Andrew M. , Bartus Katalin , Reynell Clare , Constantinou Sophie , Halvey Edward J. , Held Kara F. , Dostmann Wolfgang R. , Vernon Jeffrey , Garthwaite John
Published: December 2010

Nitric oxide (NO) functions as a diffusible transmitter in most tissues of the body and exerts its effects by binding to receptors harboring a guanylyl cyclase transduction domain, resulting in cGMP accumulation in target cells. Despite its widespread importance, very little is known about how this signaling pathway operates at physiological NO concentrations and in real time. To address these deficiencies, we have exploited the properties of a novel cGMP biosensor, named δ-FlincG, expressed in cells containing varying mixtures of NO-activated guanylyl cyclase and cGMP-hydrolyzing phosphodiesterase activity. Responsiveness to NO, signifying a physiologically relevant rise in cGMP to 30 nM or more, was seen at concentrations as low as 1 pM, making cells by far the most sensitive NO detectors yet encountered. Even cells coexpressing phosphodiesterase-5, a cGMP-activated isoform found in many NO target cells, responded to NO in concentrations as low as 10 pM. The dynamics of NO capture and signal transduction was revealed by administering timed puffs of NO from a local pipette. A puff lasting only 100 ms, giving a calculated peak intracellular NO concentration of 23 pM, was detectable. The results could be encapsulated in a quantitative model of cellular NO-cGMP signaling, which recapitulates the NO responsiveness reported previously from crude cGMP measurements on native cells, and which explains how NO is able to exert physiological effects at extremely low concentrations, when only a tiny proportion of its receptors would be occupied.