bluuebunny/crossref_metadata_2025 huggingface dataset:
Reciprocal influences between maternal language and children's language and cognitive development in low-income families
Authors: SONG LULU , SPIER ELIZABETH T. , TAMIS-LEMONDA CATHERINE S.
Published: January 2013

We examined reciprocal associations between early maternal language use and children's language and cognitive development in seventy ethnically diverse, low-income families. Mother–child dyads were videotaped when children were aged 2;0 and 3;0. Video transcripts were analyzed for quantity and lexical diversity of maternal and child language. Child cognitive development was assessed at both ages and child receptive vocabulary was assessed at age 3;0. Maternal language related to children's lexical diversity at each age, and maternal language at age 2;0, was associated with children's receptive vocabulary and cognitive development at age 3;0. Furthermore, children's cognitive development at age 2;0 was associated with maternal language at age 3;0 controlling for maternal language at age 2;0, suggesting bi-directionality in mother–child associations. The quantity and diversity of the language children hear at home has developmental implications for children from low-income households. In addition, children's early cognitive skills further feed into their subsequent language experiences.
An indefinite and critical concave—convex-type equation
Authors: Quoirin Humberto Ramos , Ubilla Pedro
Published: January 2013

We analyse the multiplicity of non-negative solutions for the critical concave—convex-type equation

where Ω is a bounded domain of ℝN, 1 < r < p and λ > 0, and μ is a real parameter. Combining minimization on the underlying Nehari manifold with energy estimates, we show that, under suitable conditions on a and b, three non-negative solutions may exist when λ is positive and sufficiently small and μ is in a right neighbourhood of μ1, the first weighted eigenvalue of the p-Laplacian. To the best of our knowledge, our multiplicity result is new, even in the semi-linear case p = 2.
A concave—convex elliptic problem involving the fractional Laplacian
Authors: Brändle C. , Colorado E. , de Pablo A. , Sánchez U.
Published: January 2013

We study a nonlinear elliptic problem defined in a bounded domain involving fractional powers of the Laplacian operator together with a concave—convex term. We completely characterize the range of parameters for which solutions of the problem exist and prove a multiplicity result. We also prove an associated trace inequality and some Liouville-type results.
Spectral theory of elliptic differential operators with indefinite weights
Authors: Behrndt Jussi
Published: January 2013

The spectral properties of a class of non-self-adjoint second-order elliptic operators with indefinite weight functions on unbounded domains Ω are investigated. It is shown, under an abstract regularity assumption, that the non-real spectrum of the associated elliptic operators in L2(Ω) is bounded. In the special case where Ω = ℝn decomposes into subdomains Ω+ and Ω− with smooth compact boundaries and the weight function is positive on Ω+ and negative on Ω−, it turns out that the non-real spectrum consists only of normal eigenvalues that can be characterized with a Dirichlet-to-Neumann map.
The case for diglossia: Describing the emergence of two grammars in the early acquisition of metropolitan French
Authors: PALASIS KATERINA
Published: January 2013

This article supports the diglossic approach to variation in metropolitan French by delving into the subject from the point of view of acquisition. Drawing on naturalistic data from 37 native French children between the ages of 2;3 and 4;0, the investigation exemplifies the existence of two cognate, but distinct grammars in the mind/brain of these children. The distinction between Spontaneous French (G1, all children) and Normed French (G2, 4 children by age 4) hinges upon two crucial characteristics, i.e. the morpho-syntactic status of nominative clitics and the emergence of the negative particlene. Accusative clitics with imperatives and past-participle agreement are also examined in order to gain a comprehensive picture of the two grammars. Finally, the emergence ofneis interpreted as a trigger forcing a speaker to move from G1to G2due to the total unavailability ofnein G1.
Do French speakers really have two grammars?
Authors: ROWLETT PAUL
Published: January 2013

I consider variation within French and its status in speakers’ mental grammars. I start with Massot's (2008) claim that, within relevant grammatical units, speakers in contemporary metropolitan France do not combine socio-stylistically marked L and H features, and his explanation of this in terms of diglossia (Ferguson, 1959), that is, the idea that speakers possess two (in this case massively overlapping but not identical) ‘French’ grammars which co-exist in their minds: one (français démotique, FD: acquired early, well, and in a naturalistic environment) comprises one set of grammatical features which generate unmarked forms and the marked L forms; the other (français classique tardif, FCT: learnt later, often unreliably, in a more formal context and under the influence of literacy) comprises a (partially) different set of grammatical features which generate the same unmarked forms as well as the marked H forms. Speakers switch between FD and FCT but do not use them both simultaneously, at least not within the context of an individual clause. While Massot's claim is controversial (see Coveney, 2011), I provisionally accept that it is correct, and move on to consider his explanation. I review instances of variation for which I suggest Massot's model needs to be revised in order to account for the phenomenon of surface forms which can be generated by both putative grammars, and which are therefore superficially part of the overlap, but which have a different linguistic status in each and underlyingly are not therefore part of any overlap. I then reconsider Massot's two-grammar hypothesis, raising issues surrounding the extent of the overlap between them, the nature of the differences between them, and their respective statuses in the minds of speakers. I suggest that in view of their massive overlap, their non-random differences, and their contrasting cognitive statuses, it does not make sense to view both FD and FCT as autonomous grammars. Rather, I suggest that only FD is an autonomous grammar. Since the differences between FD and FCT are instantiations of naturally occurring developments usually conceptualised in terms of cyclic grammaticalisation and renewal (the L features of FD are innovations with respect to the H features of FCT), I suggest that FCT should be seen as a dependent grammatical ‘bolt on’ which encodes its conservatism in an abstract and economical way.
Decreased serum levels of brain-derived neurotrophic factor in adults with attention-deficit hyperactivity disorder
Authors: Corominas-Roso Margarida , Ramos-Quiroga Josep A. , Ribases Marta , Sanchez-Mora Cristina , Palomar Gloria , Valero Sergi , Bosch Rosa , Casas Miguel
Published: January 2013

It has been hypothesized that brain-derived neurotrophic factor (BDNF) is involved in the pathogenesis of attention-deficit hyperactivity disorder (ADHD), although experimental data regarding the contribution of BDNF gene polymorphisms to this psychiatric disorder are controversial. Recently, changes in BDNF serum levels have been reported in children with ADHD, but there are no studies about the possible role of this neurotrophin in adults. A total of 54 Caucasoid ADHD adults, including the predominantly inattentive and combined types (aged 33.43 ± 8.99 yr) and 59 Caucasoid unrelated healthy controls (aged 35.52 ± 9.37 yr) were included in a study to evaluate BDNF levels in serum. Medical, neurological and psychiatric co-morbidities were excluded. Clinical data concerning ADHD diagnosis and blood samples for patients and controls were collected. BDNF serum levels were significantly lower in adults with ADHD compared to healthy controls (p < 0.0001). Although the combined type of ADHD subgroup displayed lower BDNF serum levels than the inattentive type, the differences did not reach statistical significance. No significant correlations were found between serum BDNF levels and scores on the Conners' Adult ADHD Rating Subscales. These results suggest a role for BDNF in ADHD, at least in those patients whose disorder persists throughout life. Low BDNF levels may contribute to the neurodevelopmental deficits of ADHD and to the persistence of the disorder into adulthood. BDNF differences between ADHD subtypes should be further studied.
A worldwide comparison of the best sites for submillimetre astronomy
Authors: Tremblin P. , Schneider N. , Minier V. , Durand G. Al. , Urban J.
Published: January 2013

Over the past few years a major effort has been put into the exploration of potential sites for the deployment of submillimetre (submm) astronomical facilities. Amongst the most important sites are Dome C and Dome A on the Antarctic Plateau, and the Chajnantor area in Chile. In this context, we report on measurements of the sky opacity at 200 μm over a period of three years at the French-Italian station, Concordia, at Dome C, Antarctica. Based on satellite data, we present a comparison of the atmospheric transmission at 200, 350 μm between the best potential/known sites for submillimetre astronomy all around the world.

The precipitable water vapour (PWV) was extracted from satellite measurements of the Infrared Atmospheric Sounding Interferometer (IASI) on the METOP-A satellite, between 2008 and 2010. We computed the atmospheric transmission at 200 μm and 350 μm using the forward atmospheric model MOLIERE (Microwave Observation LIne Estimation and REtrieval). This method allows us to compare known sites all around the world without the calibration biases of multiple in-situ instruments, and to explore the potential of new sites.
Winter sky brightness and cloud cover at Dome A, Antarctica
Authors: Moore Anna M. , Yang Yi , Fu Jianning , Ashley Michael C. B. , Cui Xiangqun , Feng Long Long , Gong Xuefei , Hu Zhongwen , Lawrence Jon S. , Luong-Van Daniel M. , Riddle Reed , Shang Zhaohui , Sims Geoff , Storey John W. V. , Tothill Nicholas F. H. , Travouillon Tony , Wang Lifan , Yang Huigen , Yang Ji , Zhou Xu , Zhu Zhenxi
Published: January 2013

At the summit of the Antarctic plateau, Dome A offers an intriguing location for future large scale optical astronomical observatories. The Gattini Dome A project was created to measure the optical sky brightness and large area cloud cover of the winter-time sky above this high altitude Antarctic site. The wide field camera and multi-filter system was installed on the PLATO instrument module as part of the Chinese-led traverse to Dome A in January 2008. This automated wide field camera consists of an Apogee U4000 interline CCD coupled to a Nikon fisheye lens enclosed in a heated container with glass window. The system contains a filter mechanism providing a suite of standard astronomical photometric filters (Bessell B, V, R) and a long-pass red filter for the detection and monitoring of airglow emission. The system operated continuously throughout the 2009, and 2011 winter seasons and part-way through the 2010 season, recording long exposure images sequentially for each filter. We have in hand one complete winter-time dataset (2009) returned via a manned traverse. We present here the first measurements of sky brightness in the photometric V band, cloud cover statistics measured so far and an estimate of the extinction.
Neutrino Astronomy: An Update
Authors: Halzen Francis
Published: January 2013

Detecting neutrinos associated with the still enigmatic sources of cosmic rays has reached a new watershed with the completion of IceCube, the first detector with sensitivity to the anticipated fluxes. In this review, we will briefly revisit the rationale for constructing kilometer-scale neutrino detectors and summarize the status of the field.
Cometary dust in Antarctic micrometeorites
Authors: Imae Naoya
Published: January 2013

Cometary nuclei consist of aggregates of interstellar dust particles less than ~1 μm in diameter and can produce rocky dust particles as a result of the sublimation of ice as comets enter the inner solar system. Samples of fine-grained particles known as chondritic porous interplanetary dust particles (CP-IDPs), possibly from comets, have been collected from the Earth's stratosphere. Owing to their fine-grained texture, these particles were previously thought to be condensates formed directly from interstellar gas. However, coarse-grained chondrule-like objects have recently been observed in samples from comet 81P/Wild 2. The chondrule-like objects are chemically distinct from chondrules in meteoritic chondrites, possessing higher MnO contents (0.5 wt%) in olivine and low-Ca pyroxene. In this study, we analyzed AMM samples by secondary electron microscopy and backscattered electron images for textural observations and compositional analysis. We identified thirteen AMMs with characteristics similar to those of the 81P/Wild 2 samples, and believe that recognition of these similarities necessitates reassessment of the existing models of chondrule formation.
Antarctic meteorites and the origin of planetesimals and protoplanets
Authors: Yamaguchi Akira
Published: January 2013

Almost all meteorites (about 99% by number) are samples from a few hundreds of asteroids that are leftover from planetesimals and protoplanets formed within several million years after the birth of the Solar System. These meteorites record detailed evolutionary history of dust to planets, including condensation, accretion, aqueous alteration, thermal metamorphism, partial and total melting.
225 GHz Atmospheric Opacity Measurements from Two Arctic Sites
Authors: Matsushita S. , Chen Ming-Tang , Martin-Cocher P. , Asada K. , Chen C.-P. , Inoue M. , Paine S. , Turner D. , Steinbring E.
Published: January 2013

We report the latest results of 225 GHz atmospheric opacity measurements from two Arctic sites; one on high coastal terrain near the Eureka weather station, on Ellesmere Island, Canada, and the other at the Summit Station near the peak of the Greenland icecap. This is a campaign to search for a site to deploy a new telescope for submillimeter Very Long Baseline Interferometry and THz astronomy in the northern hemisphere. Since 2011, we have obtained 3 months of winter data near Eureka, and about one year of data at Summit Station. The results indicate that these sites offer a highly transparent atmosphere for observations in submillimeter wavelengths. Summit Station is particularly excellent, and its zenith opacity at 225 GHz is statistically similar to the Atacama Large Milllimeter/submillimeter Array site in Chile. In winter, the opacity at Summit Station is even comparable to that observed at the South Pole.
Time domain astronomy from Dome C: results from ASTEP
Authors: Rivet J.-P. , Abe L. , Agabi K. , Barbieri M. , Crouzet N. , Goncalves I. , Guillot T. , Mekarnia D. , Szulagyi J. , Daban J.-B. , Gouvret C. , Fantei-Caujolle Y. , Schmider F.-X. , Furth T. , Erikson A. , Rauer H. , Fressin F. , Alapini A. , Pont F. , Aigrain S.
Published: January 2013

ASTEP (Antarctic Search for Transiting Exo Planets) is a research program funded mainly by French ANR grants and by the French Polar Institute (IPEV), dedicated to the photometric study of exoplanetary transits from Antarctica.

The preliminary “pathfinder” instrument ASTEP–South is described in another communication (Crouzet et al., these proceedings), and we focus in this presentation on the main instrument of the ASTEP program: “ASTEP–400”, a 40 cm robotized and thermally-controlled photometric telescope operated from the French-Italian Concordia station (Dome C, Antarctica).

ASTEP–400 has been installed at Concordia during the 2009-2010 summer campaign. Since, the telescope has been operated in nominal conditions during 2010 and 2011 winters, and the 2012 winterover is presently in progress. Data from the first two winter campaigns are available and processed. We give a description of the ASTEP–400 telescope from the mechanical, optical and thermal point of view. Control and software issues are also addressed. We end with a discussion of some astronomical results obtained with ASTEP–400.
Preliminary daytime seeing monitoring at Dome A, Antarctica
Authors: Pei Chong , Li Zhengyangg , Chen Hualin , Yuan Xiangyan
Published: January 2013

Sites on Antarctic plateau have unique atmospheric properties that make them better than any mid-latitude sites as observatory locations. From site testing measurements over 4 years on Dome A carried out by the Chinese Center for Antarctic Astronomy, we can reasonably predict that Dome A is as good as or even better than Dome C, which has been proved to be the best astronomical site by now, and suitable for high angular resolution observations. Seeing monitoring is necessary for planning large scale ground-based optical astronomical telescopes. In 2012, the 28th Chinese Antarctic Scientific Expedition carried out preliminary daytime seeing monitoring using a Differential Image Motion Monitor (DIMM) placed at a height of 3.5m. The median seeing was found to be 0.8″. This will be the foundation of future research that obtains comprehensive and long-period monitoring of the site's optical parameters.
Testing the bimodal distribution of long gamma-ray bursts in the cosmological rest-frame
Authors: Vásconez Christian , Vásquez Nicolás , López Ericson
Published: January 2013

Among the several methods of classifying gamma-ray bursts (GRBs), the duration parameter has lead to the canonical classification of GRBs of long and shorts. However, the canonical classification of bursts has recently seen the emergence of a third type of GRB, which is present in a recent large burst sample from the Swift observatory. The high redshifts and the cosmological distances are directly confirmed for long bursts only, while for the short ones there is only indirect evidence for their cosmological origin. Cosmological objects should not only be redshifted in energy but also extended in time because of the expansion of the Universe. Meanwhile, an anticorrelation between the hardness and the duration is found for this subclass in contrast to the short and the long groups (Horvath et al. (2010)). Despite the differences among these three groups, it is not yet clear whether the third group represents a physically different phenomenon. In this scenario, we want to study the bimodal distribution of long bursts, focusing their temporal properties in the source location (burst frame). We have determined a temporal estimator in the cosmological rest-frame from a sample of 60 Swift's GRBs. If GRBs are at cosmological distances, then the burst profiles should be stretched in time due to cosmological time dilation by an amount proportional to the redshift, 1 + z (Chang (2001)). Complementary, we use the hardness ratio between the soft emission (15–50keV) and hard X-ray emission (50–150keV) in order to analyze the bimodal distribution of long bursts in the time-energy plane.
Where is Ridge A?
Authors: Sims Geoff , Kulesa Craig , Ashley Michael C. B. , Lawrence Jon S. , Saunders Will , Storey John W. V.
Published: January 2013

First identified in 2009 as the site with the lowest precipitable water vapour (PWV) and best terahertz transmission on Earth, “Ridge A” is located approximately 150 km south of Dome A, Antarctica. We use three years of data from the Microwave Humidity Sensor (MHS) on the NOAA-18 satellite and recent ground-based measurements from Ridge A to probe the PWV variations and stability over the high Antarctic plateau.
Solar Eclipses Observed from Antarctica
Authors: Pasachoff Jay M.
Published: January 2013

Aspects of the solar corona are still best observed during totality of solar eclipses, and other high-resolution observations of coronal active regions can be observed with radio telescopes by differentiation of occultation observations, as we did with the Jansky Very Large Array for the annular solar eclipse of 2012 May 20 in the US. Totality crossing Antarctica included the eclipse of 2003 November 23, and will next occur on 2021 December 4; annularity crossing Antarctica included the eclipse of 2008 February 7, and will next occur on 2014 April 29. Partial phases as high as 87% coverage were visible and were imaged in Antarctica on 2011 November 25, and in addition to partial phases of the total and annular eclipses listed above, partial phases were visible in Antarctica on 2001 July 2011, 2002 December 4, 2004 April 19, 2006 September 22, 2007 September 11, and 2009 January 26, and will be visible on 2015 September 13, 2016 September 1, 2017 February 26, 2018 February 15, and 2020 December 14. On behalf of the Working Group on Solar Eclipses of the IAU, the poster showed the solar eclipses visible from Antarctica and this article shows a subset (see www.eclipses.info for the full set). A variety of investigations of the Sun and of the response of the terrestrial atmosphere and ionosphere to the abrupt solar cutoff can be carried out at the future eclipses, making the Antarctic observations scientifically useful.
Photometry of Variables from Dome A, Antarctica
Authors: Wang Lingzhi , Macri L. M. , Wang L. , Ashley M. C. B. , Cui X. , Feng L. L. , Gong X. , Lawrence J. S. , Liu Q. , Luong-Van D. , Pennypacker C. R. , Shang Z. , Storey J. W. V. , Yang H. , Yang J. , Yuan X. , York D. G. , Zhou X. , Zhu Z. , Zhu Z.
Published: January 2013

Dome A on the Antarctic plateau is likely one of the best observing sites on Earth (Saunders et al. 2009). We used the CSTAR telescope (Yuan et al. 2008) to obtain time-series photometry of 104 stars with i>14.5 mag during 128 days of the 2008 Antarctic winter season (Wang et al. 2011). During the 2010 season we observed 2 × 104 stars with i>15 mag for 183 days (Wang et al. 2012). We detected a total of 262 variables, a 6 × increase relative to previous surveys of the same area and depth carried out from temperate sites (Pojmanski 2004). Our observations show that high-precision, long-term photometry is possible from Antarctica and that astronomically useful data can be obtained during 80% of the winter season.
Heat transport regimes in an inclined channel
Authors: Riedinger X. , Tisserand J.-C. , Seychelles F. , Castaing B. , Chillà F.
Published: January 2013

In this paper we report measurements of the heat flux in a slightly tilted channel (angle less than 45°), filled with water, that connects two chambers: the hot in the lower part and the cold on the top. We show that different regimes develop depending on the angle and the applied power. We put in evidence a hard turbulent regime, a soft turbulent regime, a laminar regime, and an intermittent one. In the last regime, the flow oscillates between laminar and turbulent, which locks the temperature gradient to a constant value. We characterize those regimes thanks to the measurement of the axial gradient of temperature and to the measurement of the power. We model them giving descriptions in term of Nusselt and Rayleigh numbers. The soft turbulence to hard turbulence transition is interpreted as the birth of the inertial range of developed turbulence. This transition, which appears in several systems, is particularly clear here, thanks to its consequences on heat transport properties.
First-principles study of the structural, electronic, and optical properties of Y-doped SrSi2
Authors: Chen Zhongjun , Yu Meisun , Chen Taihong
Published: January 2013

The structural, electronic, and optical properties of Y-doped SrSi2 crystals were studied by first-principles calculations in the framework of density-functional theory. Indeed doping with Y induced the structural compression evidently, at the same time, a structural transition was observed from cubic to tetragonal configuration for Sr0.5Y0.5Si2. Band structure calculations revealed that the replacement of Sr by Y made SrSi2 undergo semiconductor-metal transition, meanwhile, the metallic characteristics of Y-doped SrSi2 was enhanced with increasing the Y content. This encouraging finding suggests that further improvements of the thermoelectric performance on the SrSi2-based alloys may be made by increasing Y content; in a word, this changes would make this system attractive for possible candidates for thermoelectric applications. Finally, the dielectric function, absorption spectrum, and energy-loss spectrum were calculated and analyzed for Y-doped SrSi2 crystals, which show that it is a promising dielectric material.
Highly efficient photoinduced desorption of N2O and CO from porous silicon
Authors: Toker Gil , Sagi Roey , Bar-Nachum Shay , Asscher Micha
Published: January 2013

Photoinduced desorption (PID) of N2O and CO from porous silicon (PSi) samples is reported. Both adsorbates exhibit unusually large cross sections for PID at 193 nm, up to 10−15 cm2, 2–3 orders of magnitude larger than the literature values for similar processes on flat Si. Under this UV irradiation, N2O molecules undergo photodissociation (a competing process leading to surface oxidation) with a cross section that is 2 orders of magnitude smaller than photodesorption. In the case of CO desorption is the exclusive photodepletion mechanism. PID efficiency decreases with increasing CO coverage suggesting PID hindrance by interactions among the desorbing CO molecules leading to re-adsorption at higher coverage. The wavelength and fluence dependence measurements exclude the possibility of laser induced thermal desorption for both adsorbates. The proposed mechanism for this phenomenon is desorption induced by hot electron transfer from the substrate to the adsorbate. Enhanced lifetime of transient negative adsorbate due to stabilization by localized holes on PSi nanotips can explain the observed abnormally large PID efficiency on top of porous silicon.
Transparent graphitic tiles synthesized from carbon nanowalls by shock compression and rapid quenching
Authors: Nakamura Kazutaka , Atou Toshiyuki , Niwase Keisuke , Nakamura Kazutaka G. , Yoshimura Akihiko , Tanimura Makoto , Kobayashi Ken-ichi , Tachibana Masaru
Published: January 2013

Here, we report the synthesis of transparent graphitic tiles from carbon nanowalls (CNWs) by shock compression and rapid quenching. The transparent tiles are included in samples recovered from shock pressures above 57 GPa. They exhibit strong photoluminescence but no diamond Raman peak, similar to the case of amorphous diamond synthesized from C60 fullerene and neutron-irradiated graphite. However, the electron energy-loss spectroscopy exhibits relatively intense π* peak associated with graphite, that is inconsistent with the transparency. From these results, it is suggested that the transparent tile is a mixture of amorphous diamond and superhard graphitic material with the transparency. Such carbon phase may come from the unique structural feature of CNWs as the starting material for the shock compression.
Experimental validation of numerical study on thermoelectric-based heating in an integrated centrifugal microfluidic platform for polymerase chain reaction amplification
Authors: Amasia Mary , Kang Seok-Won , Banerjee Debjyoti , Madou Marc
Published: January 2013

A comprehensive study involving numerical analysis and experimental validation of temperature transients within a microchamber was performed for thermocycling operation in an integrated centrifugal microfluidic platform for polymerase chain reaction (PCR) amplification. Controlled heating and cooling of biological samples are essential processes in many sample preparation and detection steps for micro-total analysis systems. Specifically, the PCR process relies on highly controllable and uniform heating of nucleic acid samples for successful and efficient amplification. In these miniaturized systems, the heating process is often performed more rapidly, making the temperature control more difficult, and adding complexity to the integrated hardware system. To gain further insight into the complex temperature profiles within the PCR microchamber, numerical simulations using computational fluid dynamics and computational heat transfer were performed. The designed integrated centrifugal microfluidics platform utilizes thermoelectrics for ice-valving and thermocycling for PCR amplification. Embedded micro-thermocouples were used to record the static and dynamic thermal responses in the experiments. The data collected was subsequently used for computational validation of the numerical predictions for the system response during thermocycling, and these simulations were found to be in agreement with the experimental data to within ∼97%. When thermal contact resistance values were incorporated in the simulations, the numerical predictions were found to be in agreement with the experimental data to within ∼99.9%. This in-depth numerical modeling and experimental validation of a complex single-sided heating platform provide insights into hardware and system design for multi-layered polymer microfluidic systems. In addition, the biological capability along with the practical feasibility of the integrated system is demonstrated by successfully performing PCR amplification of a Group B Streptococcus gene.
On the mechanism of recombination at oxide precipitates in silicon
Authors: Murphy J. D. , Bothe K. , Voronkov V. V. , Falster R. J.
Published: January 2013

Oxide precipitates are well known to degrade minority carrier lifetime in silicon, but the mechanism by which they act as recombination centres is not fully understood. We report minority carrier lifetime measurements on oxide precipitate-containing silicon which has been intentionally contaminated with iron. Analysis of the injection-dependence of lifetime demonstrates the same recombination centres exist in iron-contaminated and not intentionally contaminated samples, with the state density scaling with iron loss from the bulk. This shows that recombination activity arises from impurity atoms segregated to oxide precipitates and/or surrounding crystallographic defects.
Efficient organic solar cells with solution-processed carbon nanosheets as transparent electrodes
Authors: Na Seok-In , Noh Yong-Jin , Son Su-Young , Kim Tae-Wook , Kim Seok-Soon , Lee Sungho , Joh Han-Ik
Published: January 2013

We demonstrate that solution-processed carbon nanosheet (CNS) films can efficiently serve as transparent electrodes for organic solar cells (OSCs). The CNS was obtained by spin-coating of polyacrylonitrile (PAN) dissolved in dimethylformamide on quartz substrates, followed by stabilization and carbonization processes to convert polymer into CNS. The thickness of the newly developed CNS films was easily controlled by varying the PAN solution concentration. The polymer-converted CNS films were intensively examined for the feasibility of the use as transparent anodes in solar cells. This approach could be highly desirable for all-solution-processed or printed OSCs.
Tunable nanowire Wheatstone bridge for improved sensitivity in molecular recognition
Authors: Maedler Carsten , Erramilli Shyamsunder , House L. J. , Hong M. K. , Mohanty Pritiraj
Published: January 2013

Poor signal-to-noise ratio (SNR) is a strong limiting factor on the performance of nanowire field-effect transistor based sensing of molecules. Using an advanced measurement configuration such as a Wheatstone bridge, electrical noise, drift due to fluid dynamics, thermal fluctuations, and chemical changes of the gate oxide can be drastically reduced. Here, a miniature Wheatstone bridge has been lithographically fabricated. All four arms consist of silicon nanowires, while two of the arms are tunable by top gate electrodes to enable balancing of the bridge. We have studied the performance of the bridge for pH detection. The signal-to-noise ratio is significantly enhanced in the balanced configuration, which also helps to reduce overall drift.
Damage and strain in single-layer graphene induced by very-low-energy electron-beam irradiation
Authors: Murakami Katsuhisa , Kadowaki Takuya , Fujita Jun-ichi
Published: January 2013

From the analysis of the ratio of D peak intensity to G peak intensity in Raman spectroscopy, electron beam irradiation with energies of 100 eV was found to induce damage in single-layer graphene. The damage becomes larger with decreasing electron beam energy. Internal strain in graphene induced by damage under irradiation is further evaluated based on G peak shifts. The dose-dependent internal strain was approximately 2.22% cm2/mC at 100 eV and 2.65 × 10−2% cm2/mC at 500 eV. The strain induced by the irradiation showed strong dependence on electron energy.
Hidden order emerges in stream networks
Authors: Smart Ashley G.
Published: January 2013

A model for groundwater flows reveals that merging tributaries have an affinity for the angle 2π/5.
An electrical insulator turns metallic within a femtosecond
Authors: Wilson R. Mark
Published: January 2013

When silica is driven by an ultraintense and ultrashort light pulse, its electrical conductivity can rise and fall by 18 orders of magnitude during a single optical cycle.
The physics of eukaryotic chemotaxis
Authors: Levine Herbert , Rappel Wouter-Jan
Published: January 2013

Cells sense chemical gradients, communicate gradient information throughout the cell, and change their shape in response. Statistics, materials science, and more underlie thoseessential biological processes.
Ecologies of Experience: Materiality, Sociality, and the Embodied Experience of (Street) Performing
Authors: Simpson Paul
Published: January 2013

Recently a range of relational approaches have established themselves in many arenas of geographical thought. Insights have been drawn in from poststructural philosophy and social theory to decentre the human subject and consider agency in a more distributed way. Within such work, amongst references to networks, rhizomes, assemblages, and the like, the term ‘ecology’ has at times been employed to refer to such relationalty. However, the implications of its use and the specific value of the term in thinking about relationality have not yet been fully considered. Therefore, this paper articulates an ‘ecological approach’ to the study of the embodied practices. The significance of such an approach is expressed in terms of its ability to pay attention to the co-constitutive relatedness of practices and the social—cultural—material environments in which they take place. This is articulated in the paper in three main ways: (1) by drawing attention to the sheer complexity and singularity of relatedness; (2) by reflecting on connections with, and the status of, human and nonhuman entities in the playing out of practices; and (3) by considering the structuring of affective relations and the context in which practices take place. This is illustrated in the paper in relation to the practice of street performance and the intertwining both of the more concrete ‘material’ aspects of the street space (architecture, benches, people), and of its less concrete, but still materially significant, aspects (meteorological-atmospheres, felt-ambiences, not physically present regulative formations), with the performer in the playing out of this practice.
Aqueous Microemulsions as Efficient and Versatile Media for Transition-Metal-Catalyzed Reactions
Authors: Taylor Jason G. , Ferrari Jailton
Published: January 2013

The search for efficient and versatile reaction medium to perform transition-metal-catalyzed reactions is a continuous challenge to the synthetic community. Organic solvents have been traditionally employed for this task, nevertheless, new environmentally friendly, safe, and economically viable alternatives are still highly sought after. In this context, herein, we present an overview of some interesting applications of aqueous microemulsions (oil-in-water, O/W) for transition metal catalyzed reactions as an alternative and promising aqueous-organic reaction medium that has been found to be a highly effective tool in overcoming some environmental or practical issues presented by traditional organic solvents.
Nonspecific uptake and homeostasis drive the oceanic cadmium cycle
Authors: Horner Tristan J. , Lee Renee B. Y. , Henderson Gideon M. , Rickaby Rosalind E. M.
Published: January 2013

The global marine distributions of Cd and phosphate are closely correlated, which has led to Cd being considered as a marine micronutrient, despite its toxicity to life. The explanation for this nutrient-like behavior is unknown because there is only one identified biochemical function for Cd, an unusual Cd/Zn carbonic anhydrase. Recent developments in Cd isotope mass spectrometry have revealed that Cd uptake by phytoplankton causes isotopic fractionation in the open ocean and in culture. Here we investigate the physiochemical pathways that fractionate Cd isotopes by performing subcellular Cd isotope analysis on genetically modified microorganisms. We find that expression of the Cd/Zn carbonic anhydrase makes no difference to the Cd isotope composition of whole cells. Instead, a large proportion of the Cd is partitioned into cell membranes with a similar direction and magnitude of Cd isotopic fractionation to that seen in surface seawater. This observation is well explained if Cd is mistakenly imported with other divalent metals and subsequently managed by binding within the cell to avoid toxicity. This process may apply to other divalent metals, whereby nonspecific uptake and subsequent homeostasis may contribute to elemental and isotopic distributions in seawater, even for elements commonly considered as micronutrients.
Experimental Evaluation of Size-Dependent Predation by Adult Post-Spawned Rainbow Smelt on Larval Lake Whitefish
Authors: Gorsky Dimitry , Zydlewski Joseph
Published: January 2013

Introduced landlocked Rainbow Smelt Osmerus mordax are hypothesized to be a major factor in the decline of Lake Whitefish Coregonus clupeaformis populations in many lakes. We sought to identify the size of Lake Whitefish preyed upon by adult Rainbow Smelt and how the efficiency of Rainbow Smelt predation changes Lake Whitefish ontogeny. In a laboratory setting, we exposed larval Lake Whitefish of increasing sizes to groups of seven Rainbow Smelt (>100 mm) for a 1-h period and observed predation behaviors and efficiencies. In each trial, the group of Rainbow Smelt consumed at least one larval Lake Whitefish, which were up to 45 mm in length (up to 89% of Rainbow Smelt gape width). Predation efficiency, the total number of Lake Whitefish consumed by Rainbow Smelt during trials, was 100% after Lake Whitefish hatching and followed a decreasing sigmoidal response to increasing lengths of Lake Whitefish. The apparent predatory window of Rainbow Smelt on Lake Whitefish is from Lake Whitefish size at hatch (∼12 mm) to approximately 34 mm. Rainbow Smelt generally required multiple attacks to capture a single Lake Whitefish. The capture efficiencies of Rainbow Smelt decreased from 30% as Lake Whitefish length increased and were highly variable within each Lake Whitefish size-group. The overall impact that Rainbow Smelt predation will have on Lake Whitefish populations is dependent on the growth rate of Lake Whitefish, environmental conditions that cause the Lake Whitefish hatching period to coincide with Rainbow Smelt spawning events, and the degree of overlap in habitat use between spawning Rainbow Smelt, nonspawning subadult Rainbow Smelt, and hatching Lake Whitefish.

Received August 29, 2011; accepted November 7, 2012
The majority of endogenous microRNA targets within Alu elements avoid the microRNA machinery
Authors: Hoffman Yonit , Dahary Dvir , Bublik Debora Rosa , Oren Moshe , Pilpel Yitzhak
Published: January 2013

Motivation: The massive spread of repetitive elements in the human genome presents a substantial challenge to the organism, as such elements may accidentally contain seemingly functional motifs. A striking example is offered by the roughly one million copies of Alu repeats in the genome, of which ∼0.5% reside within genes’ untranslated regions (UTRs), presenting ∼30 000 novel potential targets for highly conserved microRNAs (miRNAs). Here, we examine the functionality of miRNA targets within Alu elements in 3′UTRs in the human genome.

Results: Using a comprehensive dataset of miRNA overexpression assays, we show that mRNAs with miRNA targets within Alus are significantly less responsive to the miRNA effects compared with mRNAs that have the same targets outside Alus. Using Ago2-binding mRNA profiling, we confirm that the miRNA machinery avoids miRNA targets within Alus, as opposed to the highly efficient binding of targets outside Alus. We propose three features that prevent potential miRNA sites within Alus from being recognized by the miRNA machinery: (i) Alu repeats that contain miRNA targets and genuine functional miRNA targets appear to reside in distinct mutually exclusive territories within 3′UTRs; (ii) Alus have tight secondary structure that may limit access to the miRNA machinery; and (iii) A-to-I editing of Alu-derived mRNA sequences may divert miRNA targets. The combination of these features is proposed to allow toleration of Alu insertions into mRNAs. Nonetheless, a subset of miRNA targets within Alus appears not to possess any of the aforementioned features, and thus may represent cases where Alu insertion in the genome has introduced novel functional miRNA targets.

Contact: moshe.oren@weizmann.ac.il or Pilpel@weizmann.ac.il

Supplementary information:  Supplementary data are available at Bioinformatics online.
Impact of bosentan on exercise capacity in adults after the Fontan procedure: a randomized controlled trial
Authors: Schuuring Mark J. , Vis Jeroen C. , van Dijk Arie P.J. , van Melle Joost P. , Vliegen Hubert W. , Pieper Petronella G. , Sieswerda Gertjan T. , de Bruin‐Bon Rianne H.A.C.M. , Mulder Barbara J.M. , Bouma Berto J.
Published: January 2013

Aims

An endothelin‐1 receptor blocker, shown to be effective in patients with pulmonary arterial hypertension, might decrease pulmonary vascular resistance to increase cardiac filling and consequently improve exercise capacity in Fontan patients.

Methods and results

This was a prospective, multicentre randomized open label trial in Fontan patients. One group received bosentan for 6 months. The other group did not receive study medication for the first 3 months, followed by bosentan for 6 months. The primary endpoint was exercise capacity, and secondary endpoints were NT‐proBNP level, cardiac output, SF‐36 (Short Form‐36) quality of life (QoL), and NYHA class. Forty‐two adults (median age 29 (range 18–56) years, 52% male, 88% NYHA class I–II) from five tertiary referral centres participated in the study. Ten patients were on diuretics. Ten patients were not motivated to finish the study. Analysis of all 32 patients who finished the study at 6 months of treatment showed that mean peak V'O2 (24 vs. 25 mL/kg/min), median SQUASH score (6614 vs. 6390), median NT‐proBNP (314 vs. 274 ng/L), and mental QoL (50 vs. 51) remained unchanged as compared with baseline (P = NS, for all). After treatment, NYHA class had improved in 6 (19%), was unchanged in 24 (75%), and declined in 2 (6%) patients. Subgroup analysis on age, ventricular morphology, type of Fontan circulation, or baseline NT‐proBNP level did not reveal efficacy of bosentan. Six transient adverse effects were reported.

Conclusion

An increased NT‐proBNP level was present in the majority of Fontan patients. Six months of bosentan treatment was not beneficial.

Trial registration

NTR1557
Xenon and Isoflurane Reduce Left Ventricular Remodeling after Myocardial Infarction in the Rat
Authors: Roehl Anna B. , Funcke Sandra , Becker Michael M. , Goetzenich Andreas , Bleilevens Christian , Rossaint Rolf , Steendijk Paul , Hein Marc
Published: January 2013

Background:

Xenon and isoflurane are known to have cardioprotective properties. We tested the hypothesis that these anesthetics positively influence myocardial remodeling 28 days after experimental perioperative myocardial infarction and compared their effects.

Methods:

A total of 60 male Sprague–Dawley rats were subjected to 60min of coronary artery occlusion and 120min of reperfusion. Prior to ischemia, the animals were randomized for the different narcotic regimes (0.6 vol% isoflurane, 70 vol% xenon, or intraperitoneal injection of s-ketamine). Acute injury was quantified by echocardiography and troponin I. After 4 weeks, left ventricular function was assessed by conductance catheter to quantify hemodynamic compromise. Cardiac remodeling was characterized by quantification of dilatation, hypertrophy, fibrosis, capillary density, apoptosis, and expression of fetal genes (α/β myosin heavy chains, α-skeletal actin, periostin, and sarco/endoplasmic reticulum Ca

2+

-ATPase).

Results:

Whereas xenon and isoflurane impeded the acute effects of ischemia-reperfusion on hemodynamics and myocardial injury at a comparable level, differences were found after 4 weeks. Xenon in contrast to isoflurane or ketamine anesthetized animals demonstrated a lower remodeling index (0.7±0.1 vs. 0.9±0.3 and 1.0±0.3g/ml), better ejection fraction (62±9 vs. 49±7 and 35±6%), and reduced expression of β-myosin heavy chain and periostin. The effects on hypertrophy, fibrosis, capillary density, and apoptosis were comparable.

Conclusions:

Compared to isoflurane and s-ketamine, xenon limited progressive adverse cardiac remodeling and contractile dysfunction 28 days after perioperative myocardial infarction.
Ecological consequences of body size decline in harvested fish species: positive feedback loops in trophic interactions amplify human impact
Authors: Audzijonyte Asta , Kuparinen Anna , Gorton Rebecca , Fulton Elizabeth A.
Published: January 2013

Humans are changing marine ecosystems worldwide, both directly through fishing and indirectly through climate change. One of the little explored outcomes of human-induced change involves the decreasing body sizes of fishes. We use a marine ecosystem model to explore how a slow (less than 0.1% per year) decrease in the length of five harvested species could affect species interactions, biomasses and yields. We find that even small decreases in fish sizes are amplified by positive feedback loops in the ecosystem and can lead to major changes in natural mortality. For some species, a total of 4 per cent decrease in length-at-age over 50 years resulted in 50 per cent increase in predation mortality. However, the magnitude and direction in predation mortality changes differed among species and one shrinking species even experienced reduced predation pressure. Nevertheless, 50 years of gradual decrease in body size resulted in 1–35% decrease in biomasses and catches of all shrinking species. Therefore, fisheries management practices that ignore contemporary life-history changes are likely to overestimate long-term yields and can lead to overfishing.