bluuebunny/crossref_metadata_2025 huggingface dataset:
SH2B1β regulates N‐cadherin levels, cell–cell adhesion and nerve growth factor‐induced neurite initiation
Authors: Wang Tien‐Cheng , Li Yi‐Hsuan , Chen Kuan‐Wei , Chen Ching‐Jen , Wu Chia‐Ling , Teng Nan‐Yuan , Chen Linyi
Published: December 2010

Little is known regarding the role of inter‐cellular interaction during neuronal differentiation. Homophilic N‐cadherin engagement between cells contributes to neuronal migration. However, its function in neurite initiation is not clear. In this study, we provide the first evidence that the adaptor protein SH2B1β regulated N‐cadherin levels and neurite initiation. Overexpression of SH2B1β reduces N‐cadherin levels and increased phosphotyrosine 654 β‐catenin, leading to increased nerve growth factor‐induced neurite initiation in PC12 cells, an established model for neuronal differentiation. In contrast, overexpression of the dominant‐negative mutant SH2B1β(R555E) increases N‐cadherin expression, cell–cell aggregation, and reduces neurite initiation. Moreover, SH2B1β binds directly or indirectly to N‐cadherin indicative of its involvement in regulating the levels of N‐cadherin. Taken together, these findings provide significant new insights into how N‐cadherin‐mediated inter‐cellular interactions may influence neurite initiation and how SH2B1β may regulate these processes. J. Cell. Physiol. 226: 2063–2074, 2011. © 2010 Wiley‐Liss, Inc.
Signal transduction pathways involved in PPARβ/δ‐induced neuronal differentiation
Authors: D'Angelo B. , Benedetti E. , Di Loreto S. , Cristiano L. , Laurenti G. , Cerù M.P. , Cimini A.
Published: December 2010

Neuroblastomas are pediatric tumors originating from neuroblasts in the developing peripheral nervous system. The neurotrophin brain‐derived neurotrophic factor (BDNF) is a key regulator of survival and differentiation of specific neuronal populations in the central and peripheral nervous system. Patients whose neuroblastoma tumors express high levels of BDNF and TrkB have an unfavorable prognosis. We have previously reported on the neuronal differentiating activity of peroxisome proliferator‐activated receptors (PPAR)β/δ natural and synthetic ligands by modulating BDNF/TrkB pathway, suggesting their potential use as new therapeutic strategies for neuroblastoma. The validation of new therapeutic agents implies the understanding of their mechanisms of action. Herein, we report the effects of activated‐PPARβ/δ on signal transduction pathways known to be involved in neuronal differentiation, such as ERK1,2 and BDNF pathways. The results obtained, using also PPARβ/δ silencing, indicating a neuronal differentiating effect PPARβ/δ‐dependent through BDNF‐P75‐ERK1,2 pathways, further support a role for PPARβ/δ in neuronal differentiation and pointing towards PPARβ/δ as a modulator of pathways crucial for neuronal differentiation. These findings open new perspectives in the formulation of potential therapeutic approaches to be used as adjuvant treatment with the standard therapies. J. Cell. Physiol. 226: 2170–2180, 2011. © 2010 Wiley‐Liss, Inc.
Instrumental and expressive violence in Belgian homicide perpetrators
Authors: Thijssen Jill , de Ruiter Corine
Published: December 2010

The present study aimed to examine offender types in a sample of Belgian single‐perpetrator/single‐victim homicide cases. First, it was investigated if the distinction between instrumental and expressive aggression could be documented in crime scene and offender background characteristics. Second, the instrumental and expressive themes from the first analysis were examined in relation to the motives the perpetrators themselves provided for their offence. A sample of 97 solved homicide cases was analysed using the non‐metric multidimensional scaling procedure Proxscal. The results revealed that 62% of the homicide crime scenes and 67% of the offender backgrounds could be classified as either expressive or instrumental. The self‐reported motives did not correspond with the themes according to the Proxscal analysis. Copyright © 2010 John Wiley & Sons, Ltd.
Proteins, Lipids, and Water in the Gas Phase
Authors: van der Spoel David , Marklund Erik G. , Larsson Daniel S. D. , Caleman Carl
Published: December 2010

Evidence from mass‐spectrometry experiments and molecular dynamics simulations suggests that it is possible to transfer proteins, or in general biomolecular aggregates, from solution to the gas‐phase without grave impact on the structure. If correct, this allows interpretation of such experiments as a probe of physiological behavior. Here, we survey recent experimental results from mass spectrometry and ion‐mobility spectroscopy and combine this with observations based on molecular dynamics simulation, in order to give a comprehensive overview of the state of the art in gas‐phase studies. We introduce a new concept in protein structure analysis by determining the fraction of the theoretical possible numbers of hydrogen bonds that are formed in solution and in the gas‐phase. In solution on average 43% of the hydrogen bonds is realized, while in vacuo this fraction increases to 56%. The hydrogen bonds stabilizing the secondary structure (α‐helices, β‐sheets) are maintained to a large degree, with additional hydrogen bonds occurring when side chains make new hydrogen bonds to rest of the protein rather than to solvent. This indicates that proteins that are transported to the gas phase in a native‐like manner in many cases will be kinetically trapped in near‐physiological structures. Simulation results for lipid‐ and detergent‐aggregates and lipid‐coated (membrane) proteins in the gas phase are discussed, which in general point to the conclusion that encapsulating proteins in “something” aids in the conservation of native‐like structure. Isolated solvated micelles of cetyl‐tetraammonium bromide quickly turn into reverse micelles whereas dodecyl phosphocholine micelles undergo much slower conversions, and do not quite reach a reverse micelle conformation within 100 ns.

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Biochemikalien aus Biomasse
Authors: Dambroth M.
Published: December 2010

Der folgende Beitrag von Prof. M. Dumbroth, dem Leiter des Instituts für Pflanzenbau und Pflanzenzüchtung der Bundesforschungsanstalt fü Landwirtschaft in Braunschweig‐Völkenrode, ergänzt den Leitartikel zum gleichen Thema von Prof. K. H. Büchel [vgl. diese Nachr. 28, 715 (1979)] und stellt das Problem vor allem fü unsere gemäßigte Klimazone dar.
Weniger ÖI, alternative Polymere
Authors: Karger Gerhard
Published: December 2010

Eine Antwort auf hohe Rohstoffpreise in der Kunststoffproduktion ist die Copolymerisation der wohlfeilen technischen Monomere Kohlenmonoxid und Propylenoxid zu Polyhydroxybutyraten. Die Methode entstammt einem Hochschule‐Industrie‐Projekt, das gerade mit dem Philip‐Morris‐Forschungspreis ausgezeichnet wurde. Mit einem der Kooperationspartner, Bernhard Rieger von der Universität Ulm, sprachen die Nachrichten aus der Chemie.
Aptamersensoren
Authors: Schmidt Cordula
Published: December 2010

Der ideale Sensor wäre ein idiotensicheres Gerät im Bleistiftformat, das sich ohne Zusatz von Reagentien jederzeit und überall einsetzen ließe, mit „schmutzigen”︁ Proben fertig würde und leicht abzulesen wäre. Durch Kombination von DNA und Elektrochemie sind einige Forscher diesem Ideal bereits sehr nahe gekommen.
Elevated GnRH receptor expression plus GnRH agonist treatment inhibits the growth of a subset of papillomavirus 18‐immortalized human prostate cells
Authors: Morgan Kevin , Stavrou Emmanouil , Leighton Samuel P. , Miller Nicola , Sellar Robin , Millar Robert P.
Published: December 2010

BACKGROUND AND AIMS

Human metastatic prostate cancer cell growth can be inhibited by GnRH analogs but effects on virus‐immortalized prostate cells have not been investigated.

METHODS

Virus‐immortalized prostate cells were stably transfected with rat GnRH receptor cDNA and levels of GnRH binding were correlated with GnRH effects on signaling, cell cycle, growth, exosome production, and apoptosis.

RESULTS

High levels of cell surface GnRH receptor occurred in transfected papillomavirus‐immortalized WPE‐1‐NB26 epithelial cells but not in non‐tumourigenic RWPE‐1, myoepithelial WPMY‐1 cells, or SV40‐immortalized PNT1A. Endogenous cell surface GnRH receptor was undetectable in non‐transfected cells or cancer cell lines LNCaP, PC3, and DU145. GnRH receptor levels correlated with induction of inositol phosphates, elevation of intracellular Ca2+, cytoskeletal actin reorganization, modulation of ERK activation and cell growth‐inhibition with GnRH agonists. Hoechst 33342 DNA staining‐cell sorting indicated accumulation of cells in G2 following agonist treatment. Release of exosomes from transfected WPE‐1‐NB26 was unaffected by agonists, unlike induction observed in HEK293[SCL60] cells. Increased PARP cleavage and apoptotic body production were undetectable during growth‐inhibition in WPE‐1‐NB26 cells, contrasting with HEK293[SCL60]. EGF receptor activation inhibited GnRH‐induced ERK activation in WPE‐1‐NB26 but growth‐inhibition was not rescued by EGF or PKC inhibitor Ro320432. Growth of cells expressing low levels of GnRH receptor was not affected by agonists.

CONCLUSIONS

Engineered high‐level GnRH receptor activation inhibits growth of a subset of papillomavirus‐immortalized prostate cells. Elucidating mechanisms leading to clone‐specific differences in cell surface GnRH receptor levels is a valuable next step in developing strategies to exploit prostate cell anti‐proliferation using GnRH agonists. Prostate 71: 915–928, 2011. © 2010 Wiley‐Liss, Inc.
Intracellular uptake of (‐)epicatechin by human erythrocytes as a function of human age
Authors: Maurya Pawan Kumar , Prakash Siya
Published: December 2010

The present studies were carried out to determine the intracellular uptake of (‐)epicatechin by erythrocytes during aging in humans. (‐)Epicatechin uptake was estimated by performing ethyl acetate extraction while the total antioxidant potential of the (‐)epicatechin was estimated in terms of FRAP (ferric reducing ability of plasma) values. A significant (p < 0.001) decrease in (‐)epicatechin uptake by human erythrocytes was observed as a function of age. It is hypothesized that the uptake of (‐)epicatechin in human erythrocytes has an important role in the regulation of PMRS (plasma membrane redox system) activity during normal human aging. Copyright © 2010 John Wiley & Sons, Ltd.
‘Workaholism’ and potential outcomes in well‐being and health in a cross‐occupational sample
Authors: Andreassen Cecilie Schou , Hetland Jørn , Molde Helge , Pallesen Ståle
Published: December 2010

This study examined ‘workaholism’ components (work involvement, drive, enjoyment of work) and potential outcomes in terms of psychological well‐being and health. A sample of 661 Norwegian cross‐occupational employees from six different organizations completed an online questionnaire measuring ‘workaholism’, job satisfaction, life satisfaction, insomnia and subjective health complaints. A short version of the Norwegian‐translated Workaholism Battery showed significant relationships with reports of psychological well‐being and subjective health. Enjoyment of work was positively associated with job and life satisfaction and negatively associated with symptoms of poor health. Work involvement and drive were the strongest predictors of job dissatisfaction. Both were positively related to symptoms of poor health. Drive was, in addition, negatively associated with life satisfaction. The results showed that it is important to discriminate between different ‘workaholic’ features when investigating associations between ‘workaholism’ and potential outcomes, which were related in predictable ways to outcomes in terms of psychological well‐being and health. Copyright © 2010 John Wiley & Sons, Ltd.
Advances in Aqueous Extraction Processing of Soybeans
Authors: Campbell K. A. , Glatz C. E. , Johnson L. A. , Jung S. , de Moura J. M. N. , Kapchie V. , Murphy P.
Published: December 2010

Aqueous extraction processing technologies, having advanced in recent years, may be a viable alternative to hexane extraction to separate oil and protein from soybeans. Different extraction strategies incorporating various modes of comminution, extraction buffers, and enzymes allow production of a range of oil and protein products, but also create different processing challenges. Processes capable of achieving high free oil yields often result in a soluble protein fraction difficult to isolate and dilute oil emulsions difficult to break. Other processes can achieve high yields and purities of native soy protein, but with reduced free oil yield or require a high osmotic and ionic strength extraction buffer. This review article discusses these various advanced processes and their relative advantages and disadvantages. In addition, the current understanding of the underlying fundamental concepts of aqueous extraction is discussed in order to help direct future investigations to improve these technologies.
Cross‐Linking of Lipases Adsorbed on Hydrophobic Supports: Highly Selective Hydrolysis of Fish Oil Catalyzed by RML
Authors: Fernandez‐Lorente Gloria , Filice Marco , Lopez‐Vela Dolores , Pizarro Carolina , Wilson Lorena , Betancor Lorena , Avila Yanoska , Guisan Jose M.
Published: December 2010

Organic cosolvents may improve the properties of lipases (e.g., selectivity); however, organic cosolvents also promote the desorption of the enzyme from its hydrophobic supports. In this study, adsorbed lipase molecules were cross‐linked with polyfunctional polymers, such as aldehyde‐dextrans, to prevent this desorption. The desorption of adsorbed lipases was greatly reduced by optimizing the polymer size, polymer/lipase ratio, and cross‐linking time. More than 95% of cross‐linked, immobilized Rhizomucor miehei lipase (RML) remained adsorbed on the support after washing with cosolvents or detergents. This new, immobilized RML preparation mediated the hydrolysis of sardine oil in the presence of organic cosolvents. The presence of cosolvents promoted small losses of hydrolytic activity. Interestingly, however, 50% 2‐propanol also promoted increased selectivity in the release of eicosapentaenoic acid (EPA) in relation to docosahexaenoic acid (DHA). An EPA/DHA ratio of 4:1 in the absence of 2‐propanol was increased to a ratio of 22:1 in the presence of 2‐propanol. The new RML derivatives were relatively stable under the selected reaction conditions. Their overall half‐life was 100 h, but, in a second inactivation phase (below 60% of remaining activity), it took 600 h to reach 30% of their remaining activity.
Contribution of Compositional Parameters to the Oxidative Stability of Olive and Walnut Oil Blends
Authors: Torres Mariela , Martínez Marcela , Pierantozzi Pierluigi , Albanese María , Nasjleti Agustín , Maestri Damián
Published: December 2010

Oil blending was conducted to study the effects of changes in fatty acid composition (FAC), tocopherols and total phenol content (TPC) on oxidative stability of virgin olive oil (VOO):walnut oil (WO) blends. The measurement of the antioxidant activity of bioactive components present in the parent oils and blends was achieved by their ability to scavenge the free stable 2,2‐diphenyl‐1‐picrylhydrazyl radical (DPPH·). The highest percentage of DPPH· inhibition was found for pure VOO, and the lowest one for pure WO. EC50 values obtained from the DPPH assay correlated significantly and inversely with TPC. The generation of volatile flavor components in VOO indicated the predominance of C6 compounds produced through biochemical (enzymatic) pathways, whereas WO showed increased concentrations of medium chain (C7–C11) aldehydes produced through chemical (oxidative) pathways. The results obtained confirm the importance of VOO phenolics in providing protection against oxidation in VOO and VOO/WO blends. However, considering the impact of FAC and the content of endogenous antioxidant substances mentioned previously on the oxidative stability of the oils analyzed, the effect of an elevated unsaturation level (WO) prevails over a high amount of such bioactive components (VOO).
Resilience and suicidality among homeless youth
Authors: Cleverley Kristin , Kidd Sean A.
Published: December 2010

Homeless and street‐involved youth are considered an extremely high risk group, with many studies highlighting trajectories characterized by abusive, neglectful, and unstable family histories, victimization and criminal involvement while on the streets, high rates of physical and mental illness, and extremely high rates of mortality. While there exists a substantial body of knowledge regarding risk, in recent years attention has been increasingly shifting to the examination of resilience, intervention, and service delivery models for these young people. The present study describes the findings from a quantitative examination of personal and street‐related demographics, psychological distress, self‐esteem, resilience, and suicidality among 47 homeless and street‐involved youth. Key findings indicate that the apparent erosion of mental health variables, including resilience, occurs as a function of how long the youths have been without stable housing. Finally, those youths’ perceived resilience was associated with less suicidal ideation whereas higher psychological distress was associated with higher suicidal ideation, even when accounting for resiliency.
Online Personal Branding: Processes, Challenges, and Implications
Authors: Labrecque Lauren I. , Markos Ereni , Milne George R.
Published: December 2010

This research examines how people manage online personal brands in a Web 2.0 context. Using a novel mixed-method approach and consenting participants, the authors generated digital brand audits of 12 people and asked undergraduate students and a human resources professional to judge their profiles (made anonymous), both qualitatively and quantitatively. After comparing these evaluations with participants’ own judgments of their online profiles, the authors conducted long interviews to understand how people manage online profiles and feel about others’ judgment of the content they post. According to these results, people engage in personal branding, though their efforts are often misdirected or insufficient. They consider personal online branding challenging, especially, during life changes or when managing multiple audiences.
Congestive heart failure and atrial fibrillation in a cat with myocardial fibro-fatty infiltration
Authors: Harjuhahto Tytti A.I. , Leinonen Merja R. , Simola Outi T.M. , Järvinen Anna-Kaisa , Rajamäki Minna M.
Published: December 2010

Congestive heart failure and atrial fibrillation were diagnosed in a 4-year-old castrated Birman cat with progressive signs of dyspnea, tachypnea, and lethargy. Echocardiography revealed massive right-sided heart dilatation with ascites and hydrothorax. Electrocardiogram recording showed atrial fibrillation. Medical therapy with diuretics, benazepril, and antithrombotic agents was unsuccessful. The owner requested euthanasia. In post-mortem examination, changes associated with myocardial fibro-fatty infiltration were confirmed. Changes were most marked in the right ventricular wall but with left ventricular involvement was detected.
Dividends, maturity, and acquisitions: Evidence from a sample of bank IPOs
Authors: Cornett Marcia Millon , Fayman Alex , Marcus Alan J. , Tehranian Hassan
Published: December 2010

Post‐IPO banks are far more likely to initiate dividends than nonfinancial IPO firms. Moreover, dividend initiation has a significant impact on the ultimate disposition of a newly public bank, increasing its likelihood of subsequent acquisition by around 40% and reducing the expected time until acquisition by 83%. Conditional on being acquired, dividend initiation increases the average takeover premium by about 55% of the market value of the bank in the month prior to the takeover announcement. Dividend initiating banks are also more mature, as indicated by asset growth rates, profitability, risk measures, and corporate governance measures. The initiation of the dividends and the ultimate sale of the firm may be consequences of the same underlying driver—maturity—but the dividend initiation appears to expedite the process by confirming the status of the firm and by drawing attention to the bank's readiness and willingness to be acquired. Dividend initiation thus seems to speed up and amplify the rewards to owners that may be reaped through an ultimate sale of the institution.
Maternal consumption of high-prebiotic fibre or -protein diets during pregnancy and lactation differentially influences satiety hormones and expression of genes involved in glucose and lipid metabolism in offspring in rats
Authors: Maurer Alannah D. , Reimer Raylene A.
Published: December 2010

Risk of developing the metabolic syndrome may be influenced by nutritional environment early in life. We examined the effects of high-fibre (HF) and high-protein (HP) diets consumed during pregnancy and lactation on satiety hormones and expression of genes involved in glucose and lipid metabolism in offspring. Wistar dams were fed a control (C), HF or HP diets during pregnancy and lactation. At parturition, litters were culled to ten pups. At 21 d, all pups were weaned onto C diet. At 7, 14, 21, 28 and 35 d after birth, blood was analysed for satiety hormones and tissues for mRNA expression in offspring. No differences were observed in litter size or birth weight. At 21 d, offspring of HF dams had greater adjusted intestinal mass and lower liver weight than those of C but not of HP dams. Plasma glucose at 28 d and amylin at 7, 14 and 28 d were lower in HF v. C and HP offspring. Glucagon-like peptide-1 was higher in HP offspring than in HF offspring at 7 d but was higher in HF v. C offspring at 21 d. Offspring of HF dams had higher glucose transporter (GLUT2 and Na+-dependent glucose/galactose transporter) mRNA expression at 21 d v. C and HP offspring. In brown adipose tissue, HF and HP up-regulated uncoupling protein-1 and PPAR-γ coactivator. HP was associated with increased resistin and IL-6 mRNA expression. The present study demonstrates that maternal diet composition differentially regulates circulating satiety hormones and genes involved in glucose transport and energy metabolism in offspring. These early changes could have long-term consequences for obesity risk.
Pragmatic Scruples and the Correspondence Theory of Truth
Authors: Atkins Richard Kenneth
Published: December 2010

ABSTRACT: Cheryl Misak has offered a pragmatic argument
against a position she calls “scientific
transcendentalism.” Scientific transcendentalists hold that truth
is something different from what would be believed at the end of inquiry;
more specifically, they adhere to a correspondence theory of truth. Misak
thinks scientific transcendentalists thereby undermine the connection
between truth and inquiry, for (a) pragmatically speaking, it adds nothing
to truth and inquiry to ask whether what would be the results of
sufficiently rigorous inquiry are really true and (b) they can only accept
it as an article of faith that inquiry leads us to truth. I defend
“scientific transcendentalism” against
Misak’s objections.
Raising teachers' awareness of corpora
Authors: Frankenberg-Garcia Ana
Published: December 2010

The last couple of decades have seen a dramatic increase in corpus availability and a steady growth in the number of supporters of the use of corpora in language teaching. Yet there still seems to be a long way to go before corpora can be understood and used by language teachers in general. Novice corpus users often fail to grasp that corpora do not work in the same way as the more familiar language learning resources – such as dictionaries, grammar books and textbooks – that they are accustomed to using. I therefore propose a series of task-based, consciousness-raising exercises to help teachers (who are not corpus linguists) understand the basics of corpora. The tasks proposed are not about learning how to use a specific corpus or software, but about learning how to use corpora in general.
LITTLE BUILDERS: CORAL INSECTS, MISSIONARY CULTURE, AND THE VICTORIAN CHILD
Authors: Elleray Michelle
Published: December 2010

In his Preface to R. M. Ballantyne's most famous novel, J. M. Barrie writes that “[t]o be born is to be wrecked on an island,” and so the British boy “wonder[s] how other flotsam and jetsam have made the best of it in the same circumstances. He wants a guide: in short, The Coral Island” (v). While for Barrie the island is a convenient shorthand for masculine self-actualization, the question pursued here is the relevance of a coral island, or more specifically the coral that forms the island, to the child reader. Published in 1857 and widely recommended for boys in the latter half of the nineteenth century, The Coral Island presents three boys, shipwrecked in the South Pacific, who in the first half of the novel demonstrate their resourcefulness in forming an idyllic community. Their pre-lapsarian paradise is then disrupted, first by Pacific Island cannibals and then by European pirates, the juxtaposition implicitly presenting civility as a quality that must be actively maintained by the European reader, rather than assumed as inherent in ethnicity. The second half of the novel sees the boy narrator, and eventually all the boys, implicated in key Western activities in the South Pacific: piracy, trade, and missionary activity. The latter is important to Ballantyne, a staunch Christian himself, and is focused through the historical phenomenon of Pacific Island “teachers,” that is, converted Pacific Islanders who preceded or accompanied European missionaries in the effort to spread Christianity across the South Pacific. The missionary work highlighted in the novel, as this essay will show, is also integrally connected to the coral featured prominently in its title.
Polymer space-charge-limited transistor as a solid-state vacuum tube triode
Authors: Chao Yu-Chiang , Ku Ming-Che , Tsai Wu-Wei , Zan Hsiao-Wen , Meng Hsin-Fei , Tsai Hung-Kuo , Horng Sheng-Fu
Published: December 2010

We report the construction of a polymer space-charge-limited transistor (SCLT), a solid-state version of vacuum tube triode. The SCLT achieves a high on/off ratio of 3×105 at a low operation voltage of 1.5 V by using high quality insulators both above and below the grid base electrode. Applying a greater bias to the base increases the barrier potential, and turns off the channel current, without introducing a large parasitic leakage current. Simulation result verifies the influence of base bias on channel potential distribution. The output current density is 1.7 mA/cm2 with current gain greater than 1000.
Correlations for predicting the surface wettability for organic light-emitting-diode patterns by x-ray photoelectron spectroscopy analysis
Authors: Yang L. , Svarnas P. , Shard A. G. , Bradley J. W. , Seah M. P.
Published: December 2010

X-ray photoelectron spectroscopy (XPS) and contact angle measurements have been made to characterize patterned organic light-emitting-diode (OLED) substrates comprising indium-tin-oxide and a photoresist, both of which are modified by treatment with oxygen and tetrafluoromethane in a radiofrequency (13.56 MHz) low-power (∼1 W) capacitively coupled plasma as a function of time. Correlations between the surface chemical compositions from XPS and the contact angle, θ, are evaluated in order that the wettability of very small areas may be predicted. Very clear correlations for both the indium-tin-oxide and the photoresist surfaces are obtained enabling the prediction of the contact angles for these plasma-treated OLED materials from XPS data to a standard uncertainty of 9% in cos θ. These correlations need to be extended to a wider range of compositions in order to establish the physicochemical properties of particular surface functional groups that control water contact angles by this method.
Growth and characterization of iron-doped semi-insulating InP buffer layers for Al-free GaInP/GaInAs high electron mobility transistors
Authors: Ostinelli O. , Alt A. R. , Lövblom R. , Bolognesi C. R.
Published: December 2010

We characterize the resistivity of InP buffer layers deposited by metal-organic vapor-phase epitaxy for the fabrication of Al-free GaInP/GaInAs high electron mobility transistors (HEMTs). Achieving highly-resistive InP buffer layers on semi-insulating (SI) InP:Fe substrates has long been recognized to be challenging. This is particularly true in HEMT applications because such devices are especially sensitive to the deleterious effects of buffer leakage currents. Our experiments show that impurities arising from the SI InP substrate as well as from reactor parts produce an overall n-type doping concentration of n=1–10×1016 cm−3 near the buffer/substrate interface, which decays exponentially to a level of 4×1014 cm−3 after approximately 1 μm of InP growth. This nonintentional impurity incorporation leads to a parasitic channel in the buffer and a current leakage path for the HEMT structures, regardless of the growth conditions used. Highly-insulating buffer layers could however be obtained with InP doped by Fe at a concentration of 6×1016 cm−3 in a thin region near the InP:Fe substrate. The sheet resistance consequently increased from RS=3 000 Ω/◻ for the not intentionally doped InP layers to RS=9.4×107 Ω/◻ when Fe-doping is used in the buffer layers, a value suitable for the realization of high-speed HEMTs. As a demonstration vehicle, Al-free pseudomorphic T-gate GaInP/GaInAs HEMTs with a 100 nm footprint were fabricated and achieved a cutoff frequency of fT=fMAX∼250 GHz based on a still nonoptimized channel structure featuring a mobility and sheet carrier concentration of 10 000 cm2/V s and 1012 cm−2, respectively. The present work differentiates itself from previous Fe doping studies of InP by clarifying and quantifying the physical processes leading to parasitic conduction in not intentionally doped InP buffer layers grown on InP:Fe substrates.
A low profile vibro-impacting energy harvester with symmetrical stops
Authors: Moss Scott , Barry Alex , Powlesland Ian , Galea Steve , Carman Gregory P.
Published: December 2010

This paper reports on an investigation into the use of a vibro-impact approach to construct a relatively broadband kinetic energy harvester. Potentially, the vibro-impacting process may be exploited as an autotuning mechanism for energy harvesting in an environment where the source vibration spectrum varies in time, such as an aircraft in flight. The energy harvester examined in this paper is based on a vibro-impacting oscillator with double-sided, symmetrical, piezoelectric bimorph-stops. The energy harvester operates in the frequency range of 100–113 Hz and has a (non-optimized) maximum energy of 5.3 mW from an rms host vibration of 450 mG.
Vibration energy harvesting using piezoelectric unimorph cantilevers with unequal piezoelectric and nonpiezoelectric lengths
Authors: Gao Xiaotong , Shih Wei-Heng , Shih Wan Y.
Published: December 2010

We have examined a piezoelectric unimorph cantilever (PUC) with unequal piezoelectric and nonpiezoelectric lengths for vibration energy harvesting theoretically by extending the analysis of a PUC with equal piezoelectric and nonpiezoelectric lengths. The theoretical approach was validated by experiments. A case study showed that for a fixed vibration frequency, the maximum open-circuit induced voltage which was important for charge storage for later use occurred with a PUC that had a nonpiezoelectric-to-piezoelectric length ratio greater than unity, whereas the maximum power when the PUC was connected to a resistor for immediate power consumption occurred at a unity nonpiezoelectric-to-piezoelectric length ratio.
A superconducting 180° hybrid ring coupler for circuit quantum electrodynamics
Authors: Hoffmann E. , Deppe F. , Niemczyk T. , Wirth T. , Menzel E. P. , Wild G. , Huebl H. , Mariantoni M. , Weißl T. , Lukashenko A. , Zhuravel A. P. , Ustinov A. V. , Marx A. , Gross R.
Published: December 2010

Superconducting circuit quantum electrodynamics experiments with propagating microwaves require devices acting as beam splitters. Using niobium thin films on silicon and sapphire substrates, we fabricated superconducting 180° microstrip hybrid ring couplers, acting as beam splitters with center frequencies of about 6 GHz. For the magnitude of the coupling and isolation, we find −3.5±0.5 dB and at least −15 dB, respectively, in a bandwidth of 2 GHz. We also investigate the effect of reflections at the superconductor-normal conductor contact by means of low temperature laser scanning microscopy. Our measurements show that our hybrid rings are well suited for on-chip applications in circuit quantum electrodynamics experiments.
Enhanced photocatalytic activity of TiO2 nanobarbed fibers treated with atmospheric pressure plasma using O2 gas
Authors: Lee Hyun-Uk , Ahn Kyun , Jeong Se-Young , Cho Chae-Ryong , Kim Jong-Pil , Bae Jong-Seong , Kim Hyun-Gyu , Kwon Se-Hun , Lee Hyung Woo
Published: December 2010

TiO 2 nanobarbed fibers (NBFs) were prepared by growing rutile TiO2 nanorods on anatase TiO2 nanofibers via electrospinning and hydrothermal reaction processes. There was a large increase in the photocatalytic activity of O2-plasma-treated (OP)-TiO2 NBFs relative to that of the TiO2 NBFs; this is due to the hydroxylation of the surface of the TiO2 NBFs by OP treatment. The repeatability of the photocatalytic activity of the OP-TiO2 NBFs was found to be high and the decolorization rate after ten cycles was 88.3% of the initial value. These results indicate that OP-TiO2 NBFs have great potential for use as a photocatalyst.
Sharp rise of excitation temperature in the periphery of lamp arcs measured from the 254 nm resonance line of mercury
Authors: Drakakis E. , Karabourniotis D.
Published: December 2010

Unexpected sharp rise of the excitation temperature of the resonance state of mercury measured in the arc boundary of a high intensity discharge lamp verifies the existence of an enhanced radiation source in the outer arc layer from which radiation excess observed in the valley of self-reversed lines is originated. This temperature was deduced from line-of-sight measurements of the radiance at the red peak of the 254 nm resonance line of mercury. The nonradiative transfer of excitation energy by resonant collisions between mercury atoms in the dense plasma medium is a very plausible explanation of the radiation source enhancement.
Single-mode waveguiding in bundles of self-assembled semiconductor nanowires
Authors: Zhang J. , Lutich A. A. , Susha A. S. , Rogach A. L. , Jäckel F. , Feldmann J.
Published: December 2010

We report on waveguiding in bundles of parallel oriented semiconductor nanowires, self-assembled from colloidal CdTe nanocrystals in solution at room temperature. Individual bundles, as narrow as 170 nm, act as single-mode, subwavelength waveguides for red visible light. Losses are dominated by reabsorption and allow waveguiding over distances of micrometers. This renders self-assembled NW bundles candidates for low-cost, short-distance optical interconnects in hybrid electronic-photonic circuits.
High switching endurance in TaOx memristive devices
Authors: Yang J. Joshua , Zhang M.-X. , Strachan John Paul , Miao Feng , Pickett Matthew D. , Kelley Ronald D. , Medeiros-Ribeiro G. , Williams R. Stanley
Published: December 2010

We demonstrate over 1×1010 open-loop switching cycles from a simple memristive device stack of Pt/TaOx/Ta. We compare this system to a similar device stack based on titanium oxides to obtain insight into the solid-state thermodynamic and kinetic factors that influence endurance in metal-oxide memristors.
The peculiar magnetic property evolution along RCu3Mn4O12 (R=Y, La, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu): A first-principles study
Authors: Liu Xiaojuan , Lv Shuhui , Li hongping , Meng Jian
Published: December 2010

Within RCu3Mn4O12 (R=Rare earth), besides the expected ferrimagnetic order of Mn and Cu ions below TC1, R magnetic moments also play an important role at lower temperatures TC2, leading to their peculiar magnetic behavior. By first-principles calculation, we found that along the series from La to Lu, TC1 monotonically increased due to the ionic radius (IR) induced chemical pressure, as experimentally observed, while TC2 is closely related to the atomic radius of R. Additionally, the magnetic anisotropy energy (ΔEani) along the series is found to be correlated with the total magnetic moment of R ion.
Spatial and temporal evolution of filamentation instability in a current-carrying plasma
Authors: Mohammadhosseini B. , Niknam A. R. , Shokri B.
Published: December 2010

The spatial and temporal evolution of the electric and magnetic fields in a current-carrying plasma is investigated in the nonlinear regime. Using the magnetohydrodynamic equations, a nonlinear diffusion equation for the magnetic field in the plasma is obtained. This nonlinear equation is numerically solved and the spatiotemporal evolution of the electric and magnetic fields and the electron density distribution are plotted. It is shown that as the time passes, the profile of the electric and magnetic fields changes from a sinusoidal shape to a saw-tooth one and the electron density distribution becomes very steepened. Also, the mechanism of the filament formation is then discussed. Furthermore, the effects of the thermal motion, collisions, and ion mass on growth rate of filaments as well as the saturation time are argued. Finally, it is found that the energy dissipation is associated with the aforementioned effects and strong plasma density gradient.
Notable Substituent Effects on the Rate Constant of Thermal Denitrogenation of Cyclic Azoalkanes: Strong Evidence for a Stepwise Denitrogenation Mechanism
Authors: Ishihara Chizuko , Abe Manabu
Published: December 2010

The thermal denitrogenation rates (k) of a series of 7,7-dimethoxy-1,4-diaryl-2,3-diazabicyclo[2.2.1]hept-2-ene derivatives 2 with a variety of aryl groups (p-CNC6H4, C6H5, p-MeC6H4, p-MeOC6H4) were determined to investigate the denitrogenation mechanism. A linear correlation (r = 0.988) between the relative rate-constant (log krel) of the denitrogenation reaction and Arnold’s σα• parameter for benzylic-type radical-stabilization was observed. However, the relative rate-constant was not correlated with the substituent effect on the lifetime of the resulting singlet diradicals DR2. These results indicate that the rate-determining step of denitrogenation of 7,7-dimethoxy-2,3-diazabicyclo[2.2.1]hept-2-ene derivatives involves stepwise C–N bond cleavage.
Mixed [2.2]Cyclophanes of Pyrene and Benzene
Authors: Vermeij Rudolf J. , Miller David O. , Dawe Louise N. , Aprahamian Ivan , Sheradsky Tuvia , Rabinovitz Mordecai , Bodwell Graham J.
Published: December 2010

An examination of the literature on [2.2]cyclophanes reveals a loose relationship between the relative sizes of the two ‘half-cyclophanes’ (as measured by the parameter Δd) and the limitations of the dominant general synthetic approaches. Direct coupling methods tend to be successful only for systems with Δd values below 1.0 Å, whereas ring-contraction-based approaches are usually viable for systems with Δd values up to 2.0 Å. For the very few known systems with Δd values greater than 2.0 Å, aromatization-based approaches are the only ones that have been successful. The syntheses of two [2.2]cyclophanes with very large Δd values, [2]paracyclo[2](2,7)pyrenophane (17) (Δd = 4.25 Å) and [2]metacyclo[2](2,7)pyrenophane (18) (Δd = 5.04 Å) are presented here. The syntheses hinge on a valence isomerization/dehydrogenation reaction. The crystallographically determined bend angle, θ, for 18 is 96.1°. Cyclophane 18 undergoes a degenerate conformational flip, the energy barrier for which was determined to be 18.9 kcal mol–1 by DNMR.
Biophysical information representation in temporally correlated spike trains
Authors: Nesse William H. , Maler Leonard , Longtin André
Published: December 2010

Spike trains commonly exhibit interspike interval (ISI) correlations caused by spike-activated adaptation currents. Here we investigate how the dynamics of adaptation currents can represent spike pattern information generated from stimulus inputs. By analyzing dynamical models of stimulus-driven single neurons, we show that the activation states of the correlation-inducing adaptation current are themselves statistically independent from spike to spike. This paradoxical finding suggests a biophysically plausible means of information representation. We show that adaptation independence is elicited by input levels that produce regular, non-Poisson spiking. This adaptation-independent regime is advantageous for sensory processing because it does not require sensory inferences on the basis of multivariate conditional probabilities, reducing the computational cost of decoding. Furthermore, if the kinetics of postsynaptic activation are similar to the adaptation, the activation state information can be communicated postsynaptically with no information loss, leading to an experimental prediction that simple synaptic kinetics can decorrelate the correlated ISI sequence. The adaptation-independence regime may underly efficient weak signal detection by sensory afferents that are known to exhibit intrinsic correlated spiking, thus efficiently encoding stimulus information at the limit of physical resolution.
Dendritic spikes mediate negative synaptic gain control in cerebellar Purkinje cells
Authors: Rancz Ede A. , Häusser Michael
Published: December 2010

Dendritic spikes appear to be a ubiquitous feature of dendritic excitability. In cortical pyramidal neurons, dendritic spikes increase the efficacy of distal synapses, providing additional inward current to enhance axonal action potential (AP) output, thus increasing synaptic gain. In cerebellar Purkinje cells, dendritic spikes can trigger synaptic plasticity, but their influence on axonal output is not well understood. We have used simultaneous somatic and dendritic patch-clamp recordings to directly assess the impact of dendritic calcium spikes on axonal AP output of Purkinje cells. Dendritic spikes evoked by parallel fiber input triggered brief bursts of somatic APs, followed by pauses in spiking, which cancelled out the extra spikes in the burst. As a result, average output firing rates during trains of input remained independent of the input strength, thus flattening synaptic gain. We demonstrate that this “clamping” of AP output by the pause following dendritic spikes is due to activation of high conductance calcium-dependent potassium channels by dendritic spikes. Dendritic spikes in Purkinje cells, in contrast to pyramidal cells, thus have differential effects on temporally coded and rate coded information: increasing the impact of transient parallel fiber input, while depressing synaptic gain for sustained parallel fiber inputs.
Polyethyleneimine nanoparticles incorporated into resin composite cause cell death and trigger biofilm stress in vivo
Authors: Beyth Nurit , Yudovin-Farber Ira , Perez-Davidi Michael , Domb Abraham J. , Weiss Ervin I.
Published: December 2010

Incorporation of cross-linked quaternary ammonium polyethylenimine (QPEI) nanoparticles in dental resin composite has a long-lasting and wide antimicrobial effect with no measured impact on biocompatibility in vitro. We hypothesized that QPEI nanoparticles incorporated into a resin composite have a potent antibacterial effect in vivo and that this stress condition triggers a suicide module in the bacterial biofilm. Ten volunteers wore a removable acrylic appliance, in which two control resin composite specimens and two resin composite specimens incorporating 1% wt/wt QPEI nanoparticles were inserted to allow the buildup of intraoral biofilms. After 4 h, the specimens were removed and tested for bacterial vitality and biofilm thickness, using confocal laser scanning microscopy. The vitality rate in specimens incorporating QPEI was reduced by > 50% (
p
 < 0.00001), whereas biofilm thickness was increased (
p
 < 0.05). The ability of the biofilm supernatant to restore bacterial death was tested in vitro. The in vitro tests showed a 70% decrease in viable bacteria (
p
 < 0.05). Biofilm morphological differences were also observed in the scanning electron microscope micrographs of the resin composite versus the resin composite incorporating QPEI. These results strongly suggest that QPEI nanoparticles incorporated at a low concentration in resin composite exert a significant in vivo antibiofilm activity and exhibit a potent broad spectrum antibacterial activity against salivary bacteria.
DNA transposon
Hermes
inserts into DNA in nucleosome-free regions in vivo
Authors: Gangadharan Sunil , Mularoni Loris , Fain-Thornton Jennifer , Wheelan Sarah J. , Craig Nancy L.
Published: December 2010

Transposons are mobile genetic elements that are an important source of genetic variation and are useful tools for genome engineering, mutagenesis screens, and vectors for transgenesis including gene therapy. We have used second-generation sequencing to analyze ≈2 × 10
5
unique de novo transposon insertion sites of the transposon
Hermes
in the
Saccharomyces cerevisiae
genome from both in vitro transposition reactions by using purified yeast genomic DNA, to better characterize intrinsic sequence specificity, and sites recovered from in vivo transposition events, to characterize the effect of intracellular factors such as chromatin on target site selection. We find that
Hermes
transposon targeting in vivo is profoundly affected by chromatin structure: The subset of genome-wide target sites used in vivo is strongly associated (
P
< 2
e
-16 by Fisher's exact test) with nucleosome-free chromatin. Our characterization of the insertion site preferences of
Hermes
not only assists in the future use of this transposon as a molecular biology tool but also establishes methods to more fully determine targeting mechanisms of other transposons. We have also discovered a long-range sequence motif that defines
S. cerevisiae
nucleosome-free regions.
The Experimental Mindset within Development Economics: Proper Use and Handling Are Everything
Authors: Ehmke Mariah , Shogren Jason F.
Published: December 2010

Recent work with Randomized Controlled Trials (RCTs) in development economics has contributed to economists' use of the experimental mindset to inform policy choices. Development scholars, however, question the authority of RCT evidence, and worry that the RCT trend will turn their profession away from theory and econometrics. We examine this challenge, as well as RCTs' role within the broader experimental area, with a thorough review of relevant literature. We find that generic RCT fears are overstated. Experimental methods should be evaluated as a tool to test theory, search for patterns, and to pre‐test new institutions. From this mindset, we see unexplored pathways that may benefit from the experimental mindset, further economic theory, and reduce poverty.