bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of solvent on the free radical polymerization of N,N‐dimethylacrylamide
Authors: Valdebenito Andrea , Encinas María Victoria
Published: May 2010

The free radical photopolymerization of N,N‐dimethylacrylamide was investigated at 25 °C and at low conversion in several solvents ranging from weak polar solvents to water. The polymerization is strongly accelerated in the aqueous medium, with the polymerization rate increasing one order of magnitude when the solvent is changed from an organic one to aqueous medium. These results were analysed in terms of macroradical conformation, effect of medium viscosity, aggregate formation, hydrogen bond formation and effect of temperature. The results suggest that the main factor that controls the polymerization rate is a kinetic effect due to the hydrogen bonding between the amide carbonyl group and water molecules. Also, we found that polymer properties, such as the thermodynamic quality of the solvent for the polymer backbone and molecular weight control using transfer agents, are influenced by the intermolecular hydrogen bonding. Copyright © 2010 Society of Chemical Industry
Magnetization‐prepared NMR imaging of water penetration into poly(vinyl alcohol)–poly(N‐vinyl‐2‐pyrrolidone) hydrogels
Authors: Zainuddin  , Strounina Ekaterina V , Hill David JT , Whittaker Andrew K
Published: May 2010

Poly(vinyl alcohol)–poly(N‐vinyl‐2‐pyrrolidone) (PVA–PVP) polymer network hydrogels were prepared by subjecting an aqueous solution of PVA–PVP to gamma irradiation. The hydrogels had initial water contents of approximately 87%, and upon further immersion in water the hydrogels absorbed significantly more, reaching a final water content of about 95%. The use of magnetization‐prepared NMR imaging enabled acquisition of T2‐weighted NMR images from which T2 maps were constructed and subsequently instantaneous concentration profiles of water molecules were determined. The concentration profiles could be described using Fick's second law of diffusion and the resultant diffusion coefficients were in excellent agreement with those determined from mass‐uptake measurements reported previously. In addition an apparent change in water content over longer times was observed from the NMR images. This phenomenon could be attributed to changes in the distribution of T2 relaxation times due to rearrangement of the water molecules, or alternatively diffusion of non‐crosslinked polymer chains out of the hydrogel network. Copyright © 2010 Society of Chemical Industry
Design and simulations of novel enhancement‐mode high‐voltage GaN vertical hybrid MOS‐HEMTs
Authors: Li Z. , Tang K. , Chow T. P. , Sugimoto M. , Uesugi T. , Kachi T.
Published: May 2010

The design, simulations and optimization of a novel high‐voltage vertical GaN MOS‐controlled High Electron Mobility Transistor (HEMT) with epitaxially grown thin p type body and terrace gate structure is presented, with projected maximum breakdown voltage of 1289 V, Ron,sp of 1.9 mΩ‐cm2, and switching power loss of 34.9 μJ/cm2 and 2.60 μJ/cm2 for drain and gate respectively. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Effects of low charge carrier wave function overlap on internal quantum efficiency in GaInN quantum wells
Authors: Netzel Carsten , Hoffmann Veit , Wernicke Tim , Knauer Arne , Weyers Markus , Kneissl Michael
Published: May 2010

To determine relevant processes affecting the internal quantum efficiency in GaInN quantum well structures, we have studied the temperature and excitation power dependent photoluminescence intensity for quantum wells with different well widths on (0001) c‐plane GaN and for quantum wells on nonpolar (11‐20) a‐plane GaN. In thick polar quantum wells, the quantum confined Stark effect (QCSE) causes a stronger intensity decrease with increasing temperature as long as the radiative recombination dominates. At higher temperatures, when the nonradiative recombination becomes more important, thick polar quantum wells feature a lower relative intensity decrease than thinner polar or nonpolar quantum wells. Excitation power dependent photoluminescence points to a transition from a recombination of excitons to a bimolecular recombination of uncorrelated charge carriers for thick polar quantum wells in the same temperature range. This transition might contribute to the limitation of nonradiative recombination by a reduced diffusivity of charge carriers. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Networks controlling mRNA decay in the immune system
Authors: Schott Johanna , Stoecklin Georg
Published: May 2010

The active control of mRNA degradation has emerged as a key regulatory mechanism required for proper gene expression in the immune system. An adenosine/uridine (AU)‐rich element (ARE) is at the heart of a first regulatory system that promotes the rapid degradation of a multitude of cytokine and chemokine mRNAs. AREs serve as binding sites for a number of regulatory proteins that either destabilize or stabilize the mRNA. Several kinase pathways regulate the activity of ARE‐binding proteins and thereby coordinate the expression of their target mRNAs. Small regulatory micro (mi)‐RNAs represent a second system that enhances the degradation of several mRNAs encoding important components of signal transduction cascades that are activated during adaptive and innate immune responses. Specific miRNAs are important for the differentiation of T helper cells, class switch recombination in B cells, and the maturation of dendritic cells. Excitement in this area of research is fueled by the discovery of novel RNA elements and regulatory proteins that exert control over specific mRNAs, as exemplified by an endonuclease that was found to directly cleave interleukin‐6 mRNA. Together, these systems make up an extensive regulatory network that controls decay rates of individual mRNAs in a precise manner and thereby orchestrates the dynamic expression of many factors essential for adaptive and innate immune responses. In this review, we provide an overview of relevant factors regulated at the level of mRNA stability, summarize RNA‐binding proteins and miRNAs that control their degradation rates, and discuss signaling pathways operating within this regulatory network Copyright © 2010 John Wiley & Sons, Ltd.

This article is categorized under:

RNA Interactions with Proteins and Other Molecules > Protein–RNA Interactions: Functional Implications

RNA Turnover and Surveillance > Regulation of RNA Stability

Regulatory RNAs/RNAi/Riboswitches > Regulatory RNAs
West Nile virus impacts in American crow populations are associated with human land use and climate
Authors: LaDeau Shannon L. , Calder Catherine A. , Doran Patrick J. , Marra Peter P.
Published: May 2010

West Nile virus (WNV) was first detected in the western hemisphere during the summer of 1999, reawakening US public awareness of the potential severity of vector‐borne pathogens. Since its New World introduction, WNV has caused disease in human, avian, and mammalian communities across the continent. American crows (Corvus brachyrhynchos) are a highly susceptible WNV host and when modeled appropriately, changes in crow abundances can serve as a proxy for the spatio‐temporal presence of WNV. We use the dramatic declines in abundance of this avian host to examine spatio‐temporal heterogeneity in WNV intensity across the northeastern US, where WNV was first detected. Using data from the Breeding Bird Survey, we identify significant declines in crow abundance after WNV emergence that are associated with lower forest cover, more urban land use, and warmer winter temperatures. Importantly, we document continued declines as WNV was present in an area over consecutive years. Our findings support the urban‐pathogen link that human WNV incidence studies have shown. For each 1% increase in urban land cover we expect an additional 5% decline in the log crow abundance beyond the decline attributed to WNV in undeveloped areas. We also demonstrate a significant relationship between above‐average winter temperatures and WNV‐related declines in crow abundance. The mechanisms behind these patterns remain uncertain and hypotheses requiring further research are suggested. In particular, a strong positive relationship between urban land cover and winter temperatures may confound mechanistic understanding, especially when a temperature‐sensitive vector is involved.
Serous Cystadenomas of the Pancreas: Long-term Follow-up Measurement of Growth Rate
Authors: Menard Alexandre , Tomlinson George , Cleary Sean , Wei Alice , Gallinger Steven , Haider Masoom A.
Published: May 2010

Purpose

To measure the growth rate of microcystic subtype serous adenomas of the pancreas diagnosed by imaging.

Methods

For this retrospective study, 241 imaging studies were reviewed from 1998 to 2005. Thirty-one patients met our strict diagnostic imaging inclusion criteria and had at least 18 months of imaging follow-up. Patient demographics and lesion imaging characteristics were tested as predictors of growth.

Results

Growth was measured over a mean period of 42 months. There was a significant ( P = .0004) linear growth of tumour for the population. There was significant clustering ( P = .001) of the population into 2 growth rates: 0.50 mm/y ( n = 23) and 5.5 mm/y ( n = 8). The diameter of the lesion at presentation was significantly correlated with growth (r = 0.45; P = .01).

Conclusion

The microcystic subtype of serous cystadenomas of the pancreas diagnosed with imaging criteria demonstrates 2 distinct and slow growth rates. The size of the lesion at presentation is correlated with growth rate.
Evolution of the mammary capillary network and carbonic anhydrase activity throughout lactation and during somatotropin treatment in goats
Authors: Nielsen Mette O , Cvek Katarina , Dahlborn Kristina
Published: May 2010

During the normal course of lactation, mammary metabolic activity and blood flow are closely correlated. Six lactating goats were used in this experiment to test the hypothesis that the capillary network and the capillary enzyme, carbonic anhydrase (CA; EC 4.2.1.1) are important regulatory factors involved in the coordination of mammary blood flow (MBF) and metabolic activity. Milk vein blood velocity was determined as a measure of MBF, and fine needle mammary biopsies were obtained at different time points during lactation and by the end of a 14-d bovine somatotropin (BST) treatment initiated 3 months post partum. In mammary sections, CA activity was determined histochemically and alveolar and capillary structures by image analyses upon azure blue staining. In early lactation, alveoli were large and surrounded by many small capillaries with high CA activity. As lactation progressed, capillaries almost tripled in size, whereas number of capillaries surrounding each alveolus decreased by 1/3, and CA activity more than halved. BST treatment did not affect capillary traits but increased number of alveoli in mammary sections, and BST thus appeared to be targeted mostly towards the mammary epithelial cell. Milk vein blood velocity decreased over the course of lactation, when capillary area markedly increased, suggesting that control of mammary blood perfusion is not at the level of the capillary itself, but at pre- or post-capillary sites. We suggest that the observed changes in capillary diameter and CA activity with progressing lactation contributes to reduce efficiency of nutrient and waste product exchange across the capillary-mammary epithelial cell barrier, and this could be an important factor in regulation of mammary (epithelial cell) metabolic activity and lactation performance.
Land Conflicts, Property Rights, and the Rise of the Export Economy in Colombia, 1850–1925
Authors: Sánchez Fabio , López-Uribe María del Pilar , Fazio Antonella
Published: May 2010

The poor performance of the Colombian economy in the world markets during the late nineteenth and early twentieth centuries are attributable, in part, to the weakness of settlers’ property rights in frontier lands. To examine this issue, we collected data on production of agricultural exports at county (municipal) level in 1892, coffee production in 1925, and of public land allocation and land conflicts during the nineteenth and twentieth centuries. The quantitative analysis suggests that in the absence of land conflicts, the per capita production of agricultural exports would have been in 1925 at least twice as much as that observed.
Selective fine needle aspiration of parotid masses. FNA should be performed in all patients older than 60 years
Authors: Kieran S M , McKusker M , Keogh I , Timon C
Published: May 2010

Objectives:

The exact role of fine needle aspiration in the pre-operative assessment of patients presenting with parotid masses is controversial. Some surgeons propose that fine needle aspiration be performed only selectively in those patients with likely malignant disease, whilst others recommend it for all patients presenting with such a mass. Intuitively, one would expect older patients to be more likely to suffer from primary malignant parotid tumours and secondary deposits of malignant skin tumours. Therefore, we hypothesised that older patients with a parotid mass should undergo fine needle aspiration regardless of their medical history.

Design:

We retrospectively reviewed 197 consecutive parotidectomies to test this hypothesis.

Results:

One hundred and twenty-one patients (61.4 per cent) were diagnosed with benign disease, whilst 76 (38.6 per cent) were diagnosed with malignant disease. Eighty-three per cent of patients aged 60 years or younger had benign disease, as opposed to 35.6 per cent of patients aged more than 60 years. Malignant disease occurred more commonly in patients older than 60 years (odds ratio 8.962, 95 per cent confidence interval 4.607–17.434).

Conclusion:

In patients with a parotid mass, fine needle aspiration should be performed on all those aged 60 years or older.
Testing the Saturday Night Live Hypothesis: Fairness and Bias in Newspaper Coverage of Hillary Clinton's Presidential Campaign
Authors: Miller Melissa K. , Peake Jeffrey S. , Boulton Brittany Anne
Published: May 2010

Studies of press coverage afforded women running for public office indicate that historically, women tend to garner less coverage overall and that the coverage they do receive tends to focus disproportionately on their appearance, personality, and family status at the expense of their qualifications and issue positions. This study examines newspaper coverage of U.S. Senator Hillary Rodham Clinton's campaign for the 2008 Democratic presidential nomination. Notably, Clinton did not allege that she was receiving too little coverage or coverage that focused disproportionately on her clothing or appearance. Rather, she charged that she was being treated negatively relative to her chief rival, U.S. Senator Barack Obama. More than 6,000 articles from 25 leading newspapers from across the country were content-coded from Labor Day through Super Tuesday in order to assess Clinton's coverage on two dimensions: traditional and tonal. On a range of traditional indicators of bias, such as coverage amount and mentions of candidate appearance, Clinton's coverage clearly broke established patterns typically afforded women presidential candidates. However, the tone of Clinton's coverage was decidedly negative relative to her male competitors. Normative implications of this mixed bag of fairness and bias are discussed.
Constituting and Substantively Representing Women: Applying New Approaches to a UK Case Study
Authors: Childs Sarah , Webb Paul , Marthaler Sally
Published: May 2010

With critical mass theory increasingly rejected as an explanatory theory of women's substantive representation, new conceptual approaches and methods are being suggested that look toward the role of multiple actors and multiple sites of representation, and which point to the importance of critical actors. Within them, there is particular concern with what constitutes the substantive representation of women (SRW). At the same time, the constitutive representation of gender (CRG) has been advanced as a complementary facet of representation. This article offers the first case study of both the SRW and the CRG in the parliamentary setting. It does so through an over-time analysis of the British Conservative Party. By examining general election manifestos (1992–2005), it considers how the Conservative Party constitutes women's concerns, the relations between the sexes, and the pledges the party makes “for women”. The research, furthermore, suggests that in studying the SRW and the CRG, scholars should both look at changes in the representative claims and pledges that are made by individual political actors, such as political parties, and explore the relationship between the two facets of representation.
Gender, Development and Global Householding
Authors: Bergeron Suzanne
Published: May 2010

That issues related to migration and global householding are finally being taken seriously by mainstream development institutions is clear from the focus of the United Nation's 2009 Human Development Report. Subtitled Overcoming Barriers: Human Mobility and Development, it is the first major intergovernmental organization publication to view transnational mobility as integral to human development. The report makes a strong case for recognizing that the impact of migration in relation to development aims is significant for both sending and receiving countries. As the report states repeatedly, the old nation-centered growth and antipoverty frameworks and policies no longer fit when migrants work in one country yet send remittances that reduce poverty and promote human development in another country. Similarly, global householding—the reconfiguration of household and family arrangements as people move across national boundaries—necessitates new frameworks for understanding human livelihood strategies at the micro level. In addition to making the case for taking transnational mobility seriously in development policy, the report offers a set of recommendations that are centered on migration management, regularization, and liberalization policies, such as bilateral temporary workers' agreements that allow nations to enhance growth and competitiveness while simultaneously securing their borders.
Displacing Palestine: Palestinian Householding in an Era of Asymmetrical War
Authors: Johnson Penny
Published: May 2010

In emails from the besieged town of Khan Yunis in the southern Gaza Strip during Israel's December 2008/January 2009 war on Gaza, Majeda Al Saqqa (2009a), a long-time community and women's activist, describes to friends the shrinkage of her life into the domestic space. She explains the endless strategizing to protect children physically and psychologically and her fears not only for family but for friends all over Gaza, sometimes reachable by mobile phone, sometimes, most terribly, not. In her war diary, there is no mention of Palestinian leaders or governments, neither the Hamas-led de facto government in Gaza nor the Palestinian Authority in the West Bank. She offers only bitter asides about the international community. Apart from family, neighbors, and friends, the only agents that offer a modicum of sanity and security are local: the Palestinian health workers risking their lives for the wounded and local radio broadcasters who stay on the air with news, warnings, and encouragement.
A global view of horizontally oriented crystals in ice clouds from Cloud‐Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO)
Authors: Noel Vincent , Chepfer Helene
Published: May 2010

We analyze optical signatures in 18 months of CALIOP layer‐integrated backscatter and depolarization ratio to investigate the geographical and seasonal distribution of oriented crystals in ice clouds on a global scale. Oriented crystals are found to be rare: they appear in ∼6% of all ice cloud layers, and inside these layers the proportion of oriented crystals is estimated below 5%, even though they have a significant effect on the cloud optical properties. The geographical pattern of crystal orientation is very stable over the year, without any noticeable cycle. We investigate the atmospheric conditions which might lead to crystal orientation, including synoptic‐scale dynamics and thermodynamic profiles. In the tropics, detections of crystal orientation are more numerous in areas dominated by convection on a monthly basis, and at midlatitudes less numerous in areas dominated by strong horizontal winds. Synoptic effects, however, appear secondary; orientation is primarily driven by temperature. Oriented crystals are mostly nonexistent in ice clouds colder than −30°C, and very frequent in warmer ice clouds, appearing in 30% of such clouds in the tropics and up to 50% at higher latitudes. The temperatures where oriented crystals are found (−30°C to −10°C) are conducive to the formation of planar crystals. Results suggest oriented crystals are more frequent just above cloud base in slightly thicker cloud layers, which might provide clues to how and why orientation takes place.
Seasonal variation of the Hough modes of the diurnal component of ozone heating evaluated from Aura Microwave Limb Sounder observations
Authors: Xu Jiyao , Smith A. K. , Jiang Guoying , Yuan Wei
Published: May 2010

The global distribution of atmospheric ozone from August 2004 to December 2008 observed by Aura Microwave Limb Sounder is used to calculate the daily ozone heating rate. Comparison with a photochemical model shows that the Strobel/Zhu parameterized model of the solar heating rate gives an accurate diurnal cycle of the heating in the 10–70 km altitude range. The heating calculated using the Strobel/Zhu model is decomposed into Hough modes and the annual (AO), semiannual (SAO), and quasi‐biennial (QBO) periodicities of each Hough mode are presented. The results show that the majority of the O3 heating goes into the symmetric (1,−2), (1,1), and (1,−4) modes. The largest propagating mode (1,1) and the largest trapped mode (1,−2) have obvious SAO signatures near 47 km, where the heating magnitude is largest. The forcing of the propagating (1,1) mode by ozone heating is larger during solstices than during equinoxes. There are also AO in the (1,−2) and (1,1) modes. The QBO signatures are relatively weak in the two modes in the region of large heating rate. The heating rate of the strongest propagating mode (1,1) reaches maximum near December/January solstice; that for the strongest trapped mode (1,−2) reaches maximum near equinoxes. The strongest annual variation takes place in the (1,−1) mode; it reaches 3.6 K/d near 45 km at the December/January solstice. A new parameterization of the diurnal component of the heating rate, which covers the vertical range from 10 km to 70 km, is developed based on the seasonal variations in each Hough mode.
A simple method to estimate threshold friction velocity of wind erosion in the field
Authors: Li Junran , Okin Gregory S. , Herrick Jeffrey E. , Belnap Jayne , Munson Seth M. , Miller Mark E.
Published: May 2010

This study provides a fast and easy‐to‐apply method to estimate threshold friction velocity (TFV) of wind erosion in the field. Wind tunnel experiments and a variety of ground measurements including air gun, pocket penetrometer, torvane, and roughness chain were conducted in Moab, Utah and cross‐validated in the Mojave Desert, California. Patterns between TFV and ground measurements were examined to identify the optimum method for estimating TFV. The results show that TFVs were best predicted using the air gun and penetrometer measurements in the Moab sites. This empirical method, however, systematically underestimated TFVs in the Mojave Desert sites. Further analysis showed that TFVs in the Mojave sites can be satisfactorily estimated with a correction for rock cover, which is presumably the main cause of the underestimation of TFVs. The proposed method may be also applied to estimate TFVs in environments where other non‐erodible elements such as postharvest residuals are found.
A critical role of conventional protein kinase C in morphological changes of rodent mast cells
Authors: Yanase Yuhki , Hide Izumi , Mihara Shoji , Shirai Yasuhito , Saito Naoaki , Nakata Yoshihiro , Hide Michihiro , Sakai Norio
Published: May 2010

In mast cells, crosslinking the high‐affinity IgE receptor (FcεRI) results in a dynamic reorganization of the actin cytoskeleton that is associated with membrane ruffling. Although the signaling involved in degranulation has been well described, it is less understood in morphological changes. In this study, we investigated the specific role of conventional protein kinase C (cPKC), a crucial signal for degranulation, in antigen‐induced membrane ruffling of mast cells. In RBL‐2H3 mast cells, antigen induced a long‐lasting membrane ruffling, which was blocked with late‐added Gö6976, a specific cPKC inhibitor, indicating that sustained activation of cPKC is required for maintaining the reaction. Immunofluorescence staining of endogenous PKCα/β and real‐time imaging of transfected green fluorescent protein‐tagged PKCα/β demonstrated that in response to antigen both PKCα and PKCβI quickly translocated to the plasma membrane and were colocalized with actin filaments at the ruffling sites. These reactions were blocked by expression of kinase‐negative PKCβI, but not kinase‐negative PKCα, and by treatment with a specific PKCβ inhibitor, LY333531. The adhesion, spreading and membrane ruffling of mouse bone marrow‐derived mast cells (BMMCs), which are mostly nonadhesive, were promoted by both antigen and thymeleatoxin. Treatment with Gö6976 abolished all these reactions. Antigen‐mediated migration of BMMC was also sensitive to Gö6076 and LY333531. In addition, BMMC adhesion by and migration toward stem cell factor were shown to be dependent on cPKC. Thus, cPKC, at least PKCβ subtype, may be critical for the dynamic morphological changes that lead to the migration of mast cells.
DNA repair systems and the pathogenesis of Mycobacterium tuberculosis: varying activities at different stages of infection
Authors: Gorna Alina E. , Bowater Richard P. , Dziadek Jaroslaw
Published: May 2010

Mycobacteria, including most of all MTB (Mycobacterium tuberculosis), cause pathogenic infections in humans and, during the infectious process, are exposed to a range of environmental insults, including the host's immune response. From the moment MTB is exhaled by infected individuals, through an active and latent phase in the body of the new host, until the time they reach the reactivation stage, MTB is exposed to many types of DNA-damaging agents. Like all cellular organisms, MTB has efficient DNA repair systems, and these are believed to play essential roles in mycobacterial pathogenesis. As different stages of infection have great variation in the conditions in which mycobacteria reside, it is possible that different repair systems are essential for progression to specific phases of infection. MTB possesses homologues of DNA repair systems that are found widely in other species of bacteria, such as nucleotide excision repair, base excision repair and repair by homologous recombination. MTB also possesses a system for non-homologous end-joining of DNA breaks, which appears to be widespread in prokaryotes, although its presence is sporadic within different species within a genus. However, MTB does not possess homologues of the typical mismatch repair system that is found in most bacteria. Recent studies have demonstrated that DNA repair genes are expressed differentially at each stage of infection. In the present review, we focus on different DNA repair systems from mycobacteria and identify questions that remain in our understanding of how these systems have an impact upon the infection processes of these important pathogens.
Optical-conductivity sum rule in cuprates and unconventional charge density waves: a short review
Authors: Benfatto L. , Sharapov S. G.
Published: May 2010

We begin with an overview of the experimental results for the temperature and doping dependences of the optical-conductivity spectral weight in cuprate superconductors across the whole phase diagram. Then we discuss recent attempts to explain the observed behavior of the spectral weight using reduced and full models with unconventional dx2−y2 charge-density waves.
Microwave properties of HTS films: measurements in the millimeter wave range
Authors: Cherpak N. T. , Barannik A. A. , Prokopenko Yu. V. , Filipov Yu. F. , Vitusevich S. A.
Published: May 2010

A theoretical and experimental justification of an approach proposed and developed by us for surface impedance standard measurements of HTS films is presented. An analysis of the electromagnetic properties of quasi-optical dielectric resonators with conducting endplates, which provides a theoretical background for studies of HTS films in the millimeter wave range, is performed. With this technique, the highest-quality modes, namely whispering gallery modes, are excited in a dielectric cylindrical disc sandwiched between HTS films. Considerable enhancement of the sensitivity of surface resistance measurements in the millimeter wave range is demonstrated, which is important for the fundamental investigation of superconductor physics. It is also shown that the measured frequency shift in the resonator with the HTS endplates as a function of the temperature reveals a possibility for accurate evaluation of the field penetration depth in HTS films.
Effect of deposition temperature of TiO2 on the piezoelectric property of PbTiO3 film grown by PbO gas phase reaction sputtering
Authors: Kim Jiyoon , Hong Seungbum , Bühlmann Simon , Kim Yunseok , Park Moonkyu , Kim Yong Kwan , No Kwangsoo
Published: May 2010

A 17 nm thick PbTiO3 (PTO) films were fabricated via PbO gas phase reaction with TiO2 starting layer in a sputtering chamber. The influence of deposition temperature of TiO2 on the piezoelectric properties of PTO thin films was investigated. The remnant piezoresponse of PTO films nonlinearly increased as a function of TiO2 deposition temperature, which is correlated with the increase in average grain diameter of PTO film. As grain size increases, the restriction on remnant piezoresponse imposed by the grain boundary via coupling between local strain and polarization becomes less pronounced, which results in the increase in remnant piezoresponse. Furthermore, we found that the vertical shift in piezoresponse hysteresis loops is closely related to the residual stress state. A strong correlation between the negative vertical shift and the residual tensile stress reveals that residual stress on the resulting PTO film contributed to the asymmetric piezoelectric property.
Operating quantum waveguide circuits with superconducting single-photon detectors
Authors: Natarajan C. M. , Peruzzo A. , Miki S. , Sasaki M. , Wang Z. , Baek B. , Nam S. , Hadfield R. H. , O’Brien J. L.
Published: May 2010

Advanced quantum information science and technology (QIST) applications place exacting demands on optical components. Quantum waveguide circuits offer a route to scalable QIST on a chip. Superconducting single-photon detectors (SSPDs) provide infrared single-photon sensitivity combined with low dark counts and picosecond timing resolution. In this study, we bring these two technologies together. Using SSPDs we observe a two-photon interference visibility of 92.3±1.0% in a silica-on-silicon waveguide directional coupler at λ=804 nm—higher than that measured with silicon detectors (89.9±0.3%). We further operated controlled-NOT gate and quantum metrology circuits with SSPDs. These demonstrations present a clear path to telecom-wavelength quantum waveguide circuits.
Theoretical study of the light scattering from two alternating concentric double silica-gold nanoshell
Authors: Khosravi H. , Daneshfar N. , Bahari A.
Published: May 2010

The cross section of two alternating concentric double silica-gold nanoshell (DSGNS) is obtained as a function of wavelength. Numerical calculations show that two alternating concentric DSGNSs display two separated scattering peaks that the intensity and position of the scattering peaks depend on two gold shells thicknesses and silica layer thickness between them. By varying thicknesses of the layers of the gold shells, two alternating concentric DSGNS can be designed with the scattering peak from the visible to infrared regions of the spectrum.
The geometry effect on steady electrokinetic flows in curved rectangular microchannels
Authors: Yun Jang Ho , Chun Myung-Suk , Jung Hyun Wook
Published: May 2010

Microfluidic designs require the effort to understand the flow pattern depending on the channel geometry. An in-depth analysis based on the theoretical model is presented for the pressure-driven electrokinetic microflows in curved rectangular channels by applying the finite volume scheme with a SIMPLE (semi-implicit method for pressure-linked equations) algorithm. The external body force originated from between the nonlinear Poisson–Boltzmann field around the channel wall and the flow-induced electric field is employed in the Navier–Stokes equation, and the Nernst–Planck equation is taken into further consideration. Unknown pressure terms of the momentum equation are solved by using the continuity equation as the pressure-velocity coupling achieves convergence. Attention is focused on the geometry effect on the fluid velocity profile at the turn of charged rectangular channels with ranging complementary channel aspect ratios (i.e., H/W=0.2–5.0). Simulation results exhibit that the streamwise axial velocity at the turn skews the profile to the inner region of the microchannel. This is due to the stronger effect of spanwise pressure gradient arising from a sufficiently low Dean number. The skewed pattern in the velocity profile becomes greater with decreasing channel aspect ratio as well as degree of the channel curvature. Quantitative predictions for the decreasing velocity due to the electrokinetic interaction were also provided in both cases of shallow and deep microchannels.
Optical fiber imaging for high speed plasma motion diagnostics: Applied to low voltage circuit breakers
Authors: McBride J. W. , Balestrero A. , Ghezzi L. , Tribulato G. , Cross K. J.
Published: May 2010

An integrated portable measurement system is described for the study of high speed and high temperature unsteady plasma flows such as those found in the vicinity of high current switching arcs. An array of optical fibers allows the formation of low spatial resolution images, with a maximum capture rate of 1×106 images per second (1 MHz), with 8 bit intensity resolution. Novel software techniques are reported to allow imaging of the arc; and to measure arc trajectories. Results are presented on high current (2 kA) discharge events in a model test fixture and on the application to a commercial low voltage circuit breaker.
Electromagnetic control of coupled droplets
Authors: Malouin Bernard A. , Vogel Michael J. , Hirsa Amir H.
Published: May 2010

Electromagnetism offers several advantages for moving capillary surfaces, including energy efficiency, fast response, and device integrability. Here, we demonstrate electromagnetic control of a pinned-contact, coupled droplet system using aqueous ferrofluids. A time-varying magnetic field provides the necessary perturbation to toggle millimeter scale capillary switches. Furthermore, periodic magnetic fields can drive coupled droplets at resonant frequencies approaching 100 Hz using only 1 V by balancing capillary forces with liquid inertia. These addressable devices may find applications in adaptive optics, fluidic actuators, and read-write arrays.
A quantum logical and geometrical approach to the study of improper mixtures
Authors: Domenech Graciela , Holik Federico , Massri César
Published: May 2010

We study improper mixtures from a quantum logical and geometrical point of view. Taking into account the fact that improper mixtures do not admit an ignorance interpretation and must be considered as states in their own right, we do not follow the standard approach which considers improper mixtures as measures over the algebra of projections. Instead of it, we use the convex set of states in order to construct a new lattice whose atoms are all physical states: pure states and improper mixtures. This is done in order to overcome one of the problems which appear in the standard quantum logical formalism, namely, that for a subsystem of a larger system in an entangled state, the conjunction of all actual properties of the subsystem does not yield its actual state. In fact, its state is an improper mixture and cannot be represented in the von Neumann lattice as a minimal property which determines all other properties as is the case for pure states or classical systems. The new lattice also contains all propositions of the von Neumann lattice. We argue that this extension expresses in an algebraic form the fact that—alike the classical case—quantum interactions produce nontrivial correlations between the systems. Finally, we study the maps which can be defined between the extended lattice of a compound system and the lattices of its subsystems.
An all optically driven integrated deformable mirror device
Authors: Mathur V. , Vangala S. R. , Qian X. , Goodhue W. D. , Haji-Saeed B. , Khoury J.
Published: May 2010

We demonstrate a technique for actuating micromirrors vertically cascaded on wafer fused GaAs-GaP photodiodes. Unlike traditional actuation schemes, the electrostatic drive of the individual capacitive actuators is addressed optically in this device. Vertical mirror displacements of up to 500 nm were observed using interferometry while addressing the photodetectors with a 5 mW optical signal. Microlenses were used to address a 900 pixel device with patterned conductive pillars and thin film load resistors for each actuator-detector element. This approach can enable realization of faster and denser adaptive optics wave front corrector arrays.
Callan–Symanzik equation and asymptotic freedom in the Marr–Shimamoto model
Authors: Scarfone Leonard M.
Published: May 2010

The exactly soluble nonrelativistic Marr–Shimamoto model was introduced in 1964 as an example of the Lee model with a propagator and a nontrivial vertex function. An exactly soluble relativistic version of this model, known as the Zachariasen model, has been found to be asymptotically free in terms of coupling constant renormalization at an arbitrary spacelike momentum and on the basis of exact solutions of the Gell–Mann–Low equations. This is accomplished with conventional cut-off regularization by setting up the Yukawa and Fermi coupling constants at Euclidean momenta in terms of on mass-shell couplings and then taking the asymptotic limit. In view of this background, it may be expected that an investigation of the nonrelativistic Marr–Shimamoto theory may also exhibit asymptotic freedom in view of its manifest mathematical similarity to that of the Zachariasen model. To prove this point, the present paper prefers to examine asymptotic freedom in the nonrelativistic Marr–Shimamoto theory using the powerful concepts of the renormalization group and the Callan–Symanzik equation, in conjunction with the specificity of dimensional regularization and on-shell renormalization. This approach is based on calculations of the Callan–Symanzik coefficients and determinations of the effective coupling constants. It is shown that the Marr–Shimamoto theory is asymptotically free for dimensions D<3 and for values of D>3 occurring in periodic intervals over the range of 0<D<27 of particular interest. This differs from the original Lee model which has been shown by several authors, using these same concepts, to be asymptotically free only for D<4.
Sub-100 attoseconds stability optics-to-microwave synchronization
Authors: Zhang W. , Xu Z. , Lours M. , Boudot R. , Kersalé Y. , Santarelli G. , Le Coq Y.
Published: May 2010

We use two fiber-based femtosecond frequency combs and a low-noise carrier suppression phase detection system to characterize the optical to microwave synchronization achievable with such frequency divider systems. By applying specific noise reduction strategies, a residual phase noise as low as −120 dBc/Hz at 1 Hz offset frequency from a 11.55 GHz carrier is measured. The fractional frequency instability from a single optical-to-microwave frequency divider is 1.1×10−16 at 1 s averaging down to below 2×10−19 after only 1000 s. The corresponding rms time deviation is lower than 100 attoseconds up to 1000 s averaging duration.
Broadband quantum cascade laser gain medium based on a “continuum-to-bound” active region design
Authors: Yao Yu , Charles William O. , Tsai Tracy , Chen Jianxin , Wysocki Gerard , Gmachl Claire F.
Published: May 2010

We present quantum cascade laser designs at 7–9 μm with two lower injector states strongly coupled with the upper laser state at the operating electric fields. Optical transitions from these three coupled states contribute to a large gain spectrum width (∼250 cm−1 full width at half maximum), which enables external cavity tuning of the lasers over 200 cm−1. Lasers show comparable performance to the conventional narrow band design at a similar wavelength with a peak modal gain coefficient of ∼10 kA/cm, a slope efficiency ∼1 W/A, and good temperature performance (T0=170 K) in pulsed mode operation at 295 K.
Bulk and interfacial scatterings in current-perpendicular-to-plane giant magnetoresistance with Co2Fe(Al0.5Si0.5) Heusler alloy layers and Ag spacer
Authors: Nakatani T. M. , Furubayashi T. , Kasai S. , Sukegawa H. , Takahashi Y. K. , Mitani S. , Hono K.
Published: May 2010

We report the transport properties of a current-perpendicular-to-plane giant magnetoresistance (CPP-GMR) device with Co2Fe(Al0.5Si0.5) (CFAS) Heusler alloy ferromagnetic layers and a Ag spacer layer. The CPP-GMR devices showed relatively high ΔRA values and MR ratios up to 17 m Ω μm2 and 80% at 14 K, and 8 m Ω μm2 and 34% at 290 K. The spin diffusion length ∼3 nm and the bulk spin asymmetry ∼0.77 for the CFAS alloy at 14 K were estimated by the Valet–Fert model, indicating a large contribution of the interfacial scattering.
Turnover and intent to leave among speech pathologists
Authors: McLaughlin Emma G. H. , Adamson Barbara J. , Lincoln Michelle A. , Pallant Julie F. , Cooper Cary L.
Published: May 2010

Sound, large scale and systematic research into why health professionals want to leave their jobs is needed. This study used psychometrically-sound tools and logistic regression analyses to determine why Australian speech pathologists were intending to leave their jobs or the profession. Based on data from 620 questionnaires, several variables were found to be significantly related to intent to leave. The speech pathologists intending to look for a new job were more likely to be under 34 years of age, and perceive low levels of job security and benefits of the profession. Those intending to leave the profession were more likely to spend greater than half their time at work on administrative duties, have a higher negative affect score, not have children under 18 years of age, and perceive that speech pathology did not offer benefits that met their professional needs. The findings of this study provide the first evidence regarding the reasons for turnover and attrition in the Australian speech pathology workforce, and can inform the development of strategies to retain a skilled and experienced allied health workforce.
What is known about the topic?There is a recognised shortage of speech pathologists in Australia, and a growing need for their services. Despite this, there has been no large scale systematic investigation to clarify the reasons why Australian speech pathologists may be leaving their jobs or the profession.
What does this paper add?This is the first large scale nationwide investigation into why Australian speech-language pathologists leave their jobs or the profession. Approximately 31% of Australian speech pathologists intended to change jobs and 13% intended to change professions in search of opportunities for promotion, better pay and more rewarding and interesting work. The traditional assumption that speech pathologists have been leaving the profession due to family responsibilities was not supported, as it appeared that speech pathologists without young children were more likely to explore roles outside the profession.
What are the implications for practitioners?One way to address the issues raised in this study is for practising speech pathologists to increase their participation in industrial, organisational, educational and professional activities such as negotiating working conditions and lobbying. Student supervision, mentoring and professional supervision are important avenues for developing resilience and such skills that have not traditionally been given priority in the education of health professionals.
A snapshot of rehabilitation referrals in rural New South Wales
Authors: Pryor Julie
Published: May 2010

The aim of this paper is to describe patterns of referral to inpatient rehabilitation in rural NSW. Archival records of referrals to one rural speciality medical rehabilitation service during 2004 and 2005 were analysed using descriptive statistics displayed using tables and graphs. Seventy-six referrers referred 922 patients for inpatient rehabilitation. Almost two-thirds (63.6%) came from the local acute hospital. Most referrals (80.4%) were considered appropriate for inpatient rehabilitation. Almost three-quarters (72.5%) of the patients referred were admitted.
The demand for inpatient rehabilitation is high in rural NSW, suggesting that many healthcare providers view rehabilitation as a valuable service. Furthermore, this study suggests the important contribution that inpatient rehabilitation makes to the utilisation of acute care beds, but does not confirm it.
What is known about the topic?Internationally and nationally there is a growing appreciation of the contribution that clinical rehabilitation services make to quality of life for people with a range of conditions, but little is known about referrals patterns to inpatient rehabilitation in rural NSW.
What does the paper add?This paper provides the first focussed study of referrals to inpatient rehabilitation in rural NSW. It reports the number of patients referred, the number of referrers, the appropriateness of those referrals and their outcomes.
What are the implications for practitioners?Rehabilitation services are important, widely and largely appropriately used; and that further work is needed to assess whether additional services are required to meet this demand.