bluuebunny/crossref_metadata_2025 huggingface dataset:
Species diversity of dermal microfilariae of the genus Cercopithifilaria infesting dogs in the Mediterranean region
Authors: OTRANTO DOMENICO , BRIANTI EMANUELE , DANTAS-TORRES FILIPE , MIRÓ GUADALUPE , LATROFA MARIA STEFANIA , MUTAFCHIEV YASEN , BAIN ODILE
Published: August 2012

Following the recent description of microfilariae of a Cercopithifilaria sp. in a dog from Sicily, Italy, (herein after referred to as Cercopithifilaria sp. I), numerous skin samples were collected from dogs in the Mediterranean region. In addition to Cercopithifilaria sp. I (185·7 ± 7·2 μm long), microfilariae of 2 other species were identified, namely Cercopithifilaria grassii (651·7 ± 23·6 μm long) and a yet undescribed microfilaria, Cercopithifilaria sp. II (264·4 ± 20·2 μm long, with evident lateral alae). The morphological differentiation among the 3 species of dermal microfilariae was confirmed by differences in cytochrome c oxidase subunit 1 and ribosomal 12S sequences examined (mean level of interspecific pairwise distance of 11·4%, and 17·7%, respectively). Phylogenetic analyses were concordant in clustering these with other sequences of Cercopithifilaria spp. to the exclusion of Dirofilaria spp., Onchocerca spp. and Acanthocheilonema spp. Dermal microfilariae collected (n = 132) were morphologically identified as Cercopithifilaria sp. I (n = 108, 81·8%), Cercopithifilaria sp. II (n = 17, 12·9%), whereas only 7 (5·3%) were identified as C. grassii. Mixed infestations were detected in all sites examined. The great diversity of these neglected filarioids in dogs is of biological interest, considering the complex interactions occurring among hosts, ticks and Cercopithifilaria spp. in different environments.
The social consequences of language ideologies in courtroom cross-examination
Authors: Eades Diana
Published: August 2012

Investigations of inequality within the courtroom have mostly examined ways in which discourse structure and rules of use constrain witnesses. This article goes beyond interactional practices to deal with four central language ideologies, which both facilitate these practices and impact on the interpretation and understanding of what people say in evidence. The article further shows that language ideologies can have much wider consequences beyond the courtroom. Focusing on language ideologies involved in storytelling and retelling in cross-examination, and using an Australian example, the article traces the recontextualization of part of a witness's story from an initial investigative interview to cross-examination, then to its evaluation in closing arguments and the judicial decision, as well as its (mis)representation in the print media. The analysis reveals the role of these language ideologies in the perpetuation of neocolonial control over Australian Aboriginal people. (Language ideologies, courtroom talk, cross-examination, decontextualization, recontextualization, neocolonial control, Australia)*
Bilingual intercultural education and Andean hip hop: Transnational sites for indigenous language and identity
Authors: Hornberger Nancy H. , Swinehart Karl F.
Published: August 2012

Exploring contemporary Aymara and Quechua speakers' engagements with multilingualism, this article examines two transnational sites of Indigenous language use in Bolivia—a master's program in bilingual intercultural education in Cochabamba and a hip hop collective in El Alto. Responding to the call for a sociolinguistics of globalization that describes and interprets mobile linguistic resources, speakers, and markets, we draw on long-term ethnographic fieldwork to explore the transnational nature of these mobile and globalized sites, ideologies of Indigenous language and identity present there, and flexible language practices therein. From our analysis of selected narratives and interactions observed and recorded between 2004 and 2009, we argue that these sites, ideologies, and language practices constitute productive spaces for Indigenous language speakers to intervene in a historically and enduringly unequal, globalizing world. (Indigeneity, mobility, translanguaging, flexible language practices, multilingual repertoire, global hip hop)*
ASPIRIN ADMINISTRATION FOR PREVENTION OF ADVERSE PREGNANCY OUTCOMES
Authors: BUJOLD EMMANUEL , ROBERGE STÉPHANIE , DEMERS SUZANNE , NICOLAIDES KYPROS H
Published: August 2012

The prophylactic use of low-dose aspirin for prevention of preeclampsia has been an important research question in obstetrics for the last three decades. In 1979, Crandon and Isherwood observed that nulliparous women who had taken aspirin regularly during pregnancy were less likely to have preeclampsia than women who did not. In 1985, Beaufils et al published the first randomized trial suggesting that 150 mg aspirin and 300 mg dipyridamole daily from 3 months’ gestation onwards decreased the risk of preeclampsia, fetal growth restriction and stillbirth in high-risk women. Subsequently, more than 50 trials have been carried out throughout the world and a meta-analysis of these studies reported that the administration of low-dose aspirin in high-risk pregnancies is associated with a decrease in the rate of preeclampsia by approximately 10%. Consequently, several national professional bodies recommend that high-risk pregnancies should be treated with aspirin (50–150 mg daily).
The formation of a European constitution: an approach from historical-political sociology
Authors: Thornhill Chris
Published: August 2012

This article sets out a sociological reconstruction of the constitution of the European Union (EU). Utilising a methodology derived from historical-functionalist sociology, it explains the distinctive court-led, judicial form of this constitution within a wide comparative-sociological framework, and it cites earlier examples of judicialised constitutions to elucidate the adaptive functions performed by judicial actors in the EU constitution. The article proposes a new method for analysing constitutions in general and that of the EU in particular, and it offers an encompassing sociological perspective for addressing the increasing preponderance of judicial institutions in contemporary democratic polity building.
Visual justice
Authors: Moran Leslie J.
Published: August 2012

As the many pages of law journals, monographs and textbooks demonstrate, the complex interface between law and visual culture continues to be a marginal aspect of legal study, research and scholarship. To paraphrase sociologist Pierre Bourdieu (1965/1990, p. 1) there exists a hierarchy of legitimate objects of study. The orthodoxy continues to be preoccupied with the ways in which the written texts of law make the world. The multifarious gatekeepers of legal studies have responded in a variety of ways to scholarly and pedagogic projects that turn away from law's written text and its operationalisation. In my experience from giving papers and talking to lawyers and judges, these range from bewilderment, disbelief and passive aggressive indifference to more open attacks and withering denunciations that dismiss work that touches on the visual aspects of law as esoteric, trivial, ‘not law’. The publication of these three books exploring various dimensions of the interface between law and visual culture does not herald the death of the written text of law, but they do point to the long history and contemporary significance of visual culture for law. Their publication provides an opportunity to examine a body of work that takes this interface seriously. Each of these studies demonstrates the need to qualify the legal obsession with the word and for legal scholars to pay due regard to a wider range of visual cultural forms and practices that shape and represent law and legal practice. They also provide an opportunity to reflect on apparent resistance to taking the visual dimensions of law more seriously. In combination, these three monographs illustrate the substantive, jurisdictional, disciplinary and methodological diversity of current research on the visual dimensions of law and its historical range.
High‐frame rate thermal imagery of Strombolian explosions: Implications for explosive and infrasonic source dynamics
Authors: Delle Donne Dario , Ripepe Maurizio
Published: August 2012

Explosive activity at Stromboli volcano is analyzed using a high‐frame rate (50 Hz) thermal camera and differential pressure transducers. We develop a thermal image‐based decomposition method to derive vertical and horizontal exit velocities of the explosive cloud. Peak vertical velocity ranges between 23 and 203 m/s, slightly higher than previous estimates and rapidly decreasing to a constant value of 30–50 m/s within the first ∼0.1 s. Plume velocities are consistent with an elongated cloud expanding much faster vertically than horizontally and indicating the interaction with the conduit wall. Considering a vent radius of ∼2 m we estimate a volumetric flux of 200–600 m3/s, which converts to total volumes of gas‐particles of 103–104 m3 for a single eruption. These volumes are proportional to the thermal energy recorded by the camera, providing a means to convert thermal radiance to volumes. Comparing the thermal onset of the explosions with the arrival time of the acoustic pressure, we demonstrate that infrasound is propagating 0.14−1.7 s ahead of the explosive front. The time difference between thermal and acoustic onsets constrains the infrasonic source within the conduit at 15–35 m below the crater rim. Peak amplitudes of acoustic pressure show a power law relationship (p ∼ U2) with the exit vertical velocities consistent with the energy balance of a two‐phase flow rapidly accelerated in the conduit by gas decompression. Our results support monopole isotropic acoustic radiation of a source embedded within the conduit walls and indicate that explosive dynamics undergo strong accelerations of 103–104 m/s2.
Geology of the King crater region: New insights into impact melt dynamics on the Moon
Authors: Ashley J. W. , Robinson M. S. , Hawke B. R. , van der Bogert C. H. , Hiesinger H. , Sato H. , Speyerer E. J. , Enns A. C. , Wagner R. V. , Young K. E. , Burns K. N.
Published: August 2012

New geologic sketch maps and digital elevation models for King crater and the surrounding lunar farside highlands were created from Lunar Reconnaissance Orbiter Camera (LROC) Wide‐angle Camera (WAC) and Narrow Angle Camera (NAC) images. NAC images reveal that high volume impact melt accumulations exhibit evidence of dynamic processes during and following emplacement that resulted in downwarped zones, and other morphologic anomalies visible at the 50 cm pixel scale. Among the most significant of these forms are negative relief features, some of which may represent evidence for near‐surface caverns, offering points of access to subsurface environments and possible shelter from surface hazards. Other negative relief features may represent regions of extension and separation in response to possible subsurface drainage, together with isostatic readjustments, contraction, and/or compaction, in the cooling impact melt. Crater counts on the continuous ejecta blanket suggest a Late Eratosthenian to Copernican age for King crater, which is older than the estimate of Young (1977), but consistent with those of others.
Decay and expansion of the early aftershock activity following the 2011, Mw9.0 Tohoku earthquake
Authors: Lengliné O. , Enescu B. , Peng Z. , Shiomi K.
Published: August 2012

The 2011, Mw9.0 Tohoku earthquake was followed by an abundant amount of seismicity providing a unique opportunity to analyze the triggering mechanism of great earthquakes. Although the Tohoku earthquake occurred close to a dense seismic network, many aftershocks that occurred in the first few hours after the mainshock are not recorded in the earthquake catalogs. Here we use a template waveform approach to recover as many as possible missing events in the first 12 hours following the Tohoku mainshock. Our analysis is able to detect about 1.4 times more events than those listed in the High Sensitivity Seismograph (Hi‐net) earthquake catalog. Combining our new dataset with earthquakes that occurred at latter times, we are able to observe a continuous decay of the aftershock rate and along strike expansion of aftershock area. We relate the latter observation to the occurrence of post‐seismic slip over the deep interface.
Observed interannual variability of the Atlantic meridional overturning circulation at 26.5°N
Authors: McCarthy G. , Frajka‐Williams E. , Johns W. E. , Baringer M. O. , Meinen C. S. , Bryden H. L. , Rayner D. , Duchez A. , Roberts C. , Cunningham S. A.
Published: August 2012

The Atlantic meridional overturning circulation (MOC) plays a critical role in the climate system and is responsible for much of the heat transported by the ocean. A mooring array, nominally at 26°N between the Bahamas and the Canary Islands, deployed in Apr 2004 provides continuous measurements of the strength and variability of this circulation. With seven full years of measurements, we now examine the interannual variability of the MOC. While earlier results highlighted substantial seasonal and shorter timescale variability, there had not been significant interannual variability. The mean MOC from 1 Apr 2004 to the 31 March 2009 was 18.5 Sv with the annual means having a standard deviation of only 1.0 Sv. From 1 April 2009 to 31 March 2010, the annually averaged MOC strength was just 12.8 Sv, representing a 30% decline. This downturn persisted from early 2009 to mid‐2010. We show that the cause of the decline was not only an anomalous wind‐driven event from Dec 2009–Mar 2010 but also a strengthening of the geostrophic flow. In particular, the southward flow in the top 1100 m intensified, while the deep southward return transport—particularly in the deepest layer from 3000–5000 m—weakened. This rebalancing of the transport from the deep overturning to the upper gyre has implications for the heat transported by the Atlantic.
Argon supersaturation indicates low decadal‐scale vertical mixing in the ocean thermocline
Authors: Emerson Steven , Ito Taka , Hamme Roberta C.
Published: August 2012

The rate of vertical mixing in the ocean's stratified waters limits the uptake of anthropogenic CO2, influences the strength of the overturning circulation, and regulates the transport of nutrients to the lighted surface waters, controlling global biological production. Despite this fundamental importance, there is a long‐standing conundrum in oceanography that experimentally‐measured rates of turbulent mixing across density surfaces (diapycnal mixing) in the main thermocline cannot support sufficient nutrient fluxes from below to explain rates of biological production measured in the subtropical euphotic zone. Possible solutions to this problem are transport mechanisms that occur intermittently on short time and space scales that would be difficult to observe in tracer‐ release experiments and are not resolved in large‐scale ocean models. We tested this hypothesis by measuring highly‐accurate argon profiles from the subtropical thermocline in the North Pacific Ocean. It has been shown theoretically that the change in argon supersaturation along density surfaces is a measure of diapycnal mixing averaged over the decadal time‐scale of thermocline ventilation. Two different model interpretations of our data indicate that the mean rate of diapycnal mixing on density surfaces betweenσθ = 26.4 – 26.7 (depths 150–600 m) is no more than 0.2 × 10−4 m2 s−1. This supports low diapycnal mixing rates even on decadal time‐scales and rules out enhancement of diapycnal mixing on this density interval by intermittent mixing or mixing at boundaries that propagates into the ocean interior.
A simple model to relate ionogram signatures to large‐scale wave structure
Authors: Tsunoda Roland T.
Published: August 2012

The development of plasma structure in the nighttime equatorial F region, known as equatorial spread F(ESF), appears to be controlled by the preceding presence of large‐scale wave structure (LSWS). To understand this process, knowledge of the properties of LSWS is crucial. Information about LSWS appears to reside in two ionogram signatures, multi‐reflected echoes (MREs) and the so‐called “satellite” traces (STs). However, how LSWS is related to MREs and STs is not yet clear. To gain insight, a tilted, linear reflector, modulated by LSWS, is described and shown to be capable of explaining even the most puzzling forms of MREs and STs. With this kind of model, ionogram signatures can be used to infer the nature of LSWS.
Characteristics of low‐latitude ionospheric depletions and enhancements during solar minimum
Authors: Haaser R. A. , Earle G. D. , Heelis R. A. , Klenzing J. , Stoneback R. , Coley W. R. , Burrell A. G.
Published: August 2012

Under the waning solar minimum conditions during 2009 and 2010, the Ion Velocity Meter, part of the Coupled Ion Neutral Dynamics Investigation aboard the Communication/Navigation Outage Forecasting System satellite, is used to measure in situ nighttime ion densities and drifts at altitudes between 400 and 550 km during the hours 21:00–03:00 solar local time. A new approach to detecting and classifying well‐formed ionospheric plasma depletions and enhancements (bubbles and blobs) with scale sizes between 50 and 500 km is used to develop geophysical statistics for the summer, winter, and equinox seasons during the quiet solar conditions. Some diurnal and seasonal geomagnetic distribution characteristics confirm previous work on equatorial irregularities and scintillations, while other elements reveal new behaviors that will require further investigation before they may be fully understood. Events identified in the study reveal very different and often opposite behaviors of bubbles and blobs during solar minimum. In particular, more bubbles demonstrating deeper density fluctuations and faster perturbation plasma drifts typically occur earlier near the magnetic equator, while blobs of similar magnitude occur more often far away from the geomagnetic equator closer to midnight.
The cause of the seasonal variation in the oxygen isotopic composition of precipitation along the western U.S. coast
Authors: Buenning Nikolaus H. , Stott Lowell , Yoshimura Kei , Berkelhammer Max
Published: August 2012

This study seeks to find the primary influence on the seasonal cycle of the oxygen isotopic composition of precipitation (δ18Op) along the western U.S. coast. Observed long‐term mean seasonal variations ofδ18Op from 16 different stations along the west coast are presented. The most robust features in the observations are high values in the summer and a drop in δ18Opduring the winter. The Isotope‐incorporated Global Spectral Model (IsoGSM) also simulates this wintertime drop inδ18Op along the west coast of the U.S. Sensitivity experiments are performed with IsoGSM where individual oxygen isotope fractionation processes are turned off. These simulations reveal that the primary control on the seasonal variations is equilibrium oxygen isotopic fractionation during vapor condensation. There is almost no influence of the temperature dependence of equilibrium fractionation on the seasonal δ18Op cycle for both evaporation and condensation. Additional experiments (including tagging simulations) are performed to better understand why Rayleigh distillation causes the seasonal variation in δ18Op. The tagging simulations and budget calculations reveal that vertical oxygen isotope gradients and variations in condensation height cause the seasonal cycle in δ18Op. This results from seasonal changes in the polar jet, and subsequent changes to divergence and vertical velocities, which affects the uplift of moisture. These findings suggest that δ18Op in the western U.S. is a tracer of condensation height on seasonal timescales. The large influence of condensation height on δ18Op seasonality complicates interpretations of interannual climate proxy records based on isotopes in precipitation as the seasonality is likely not static.
Technical note: Large‐eddy simulation of cloudy boundary layer with the Advanced Research WRF model
Authors: Yamaguchi Takanobu , Feingold Graham
Published: August 2012

A thorough evaluation of the large‐eddy simulation (LES) mode of the Advanced Research WRF model is performed with use of three cloudy boundary layer cases developed as LES intercomparison cases by the GEWEX Cloud System Study. Our evaluation reveals two problems that must be recognized and carefully addressed before proceeding with production runs. These are (i) sensitivity of results to the prescribed number of acoustic time steps per physical time step; and (ii) the assumption of saturation adjustment in the initial cloudy state. A temporary, but effective method of how to cope with these issues is suggested. With the proper treatment, the simulation results are comparable to the ensemble mean of the other LES models, and sometimes closer to the observational estimate than the ensemble mean. In order to ease the burden for configuration and post‐processing, two new packages are developed and implemented. A detailed description of each package is presented. These packages are freely available to the public.
Inorganic carbon fixation by chemosynthetic ectosymbionts and nutritional transfers to the hydrothermal vent host-shrimp Rimicaris exoculata
Authors: Ponsard Julie , Cambon-Bonavita Marie-Anne , Zbinden Magali , Lepoint Gilles , Joassin André , Corbari Laure , Shillito Bruce , Durand Lucile , Cueff-Gauchard Valérie , Compère Philippe
Published: August 2012

The shrimp Rimicaris exoculata dominates several hydrothermal vent ecosystems of the Mid-Atlantic Ridge and is thought to be a primary consumer harbouring a chemoautotrophic bacterial community in its gill chamber. The aim of the present study was to test current hypotheses concerning the epibiont’s chemoautotrophy, and the mutualistic character of this association. In-vivo experiments were carried out in a pressurised aquarium with isotope-labelled inorganic carbon (NaH13CO3 and NaH14CO3) in the presence of two different electron donors (Na2S2O3 and Fe2+) and with radiolabelled organic compounds (14C-acetate and 3H-lysine) chosen as potential bacterial substrates and/or metabolic by-products in experiments mimicking transfer of small biomolecules from epibionts to host. The bacterial epibionts were found to assimilate inorganic carbon by chemoautotrophy, but many of them (thick filaments of epsilonproteobacteria) appeared versatile and able to switch between electron donors, including organic compounds (heterotrophic acetate and lysine uptake). At least some of them (thin filamentous gammaproteobacteria) also seem capable of internal energy storage that could supply chemosynthetic metabolism for hours under conditions of electron donor deprivation. As direct nutritional transfer from bacteria to host was detected, the association appears as true mutualism. Import of soluble bacterial products occurs by permeation across the gill chamber integument, rather than via the digestive tract. This first demonstration of such capabilities in a decapod crustacean supports the previously discarded hypothesis of transtegumental absorption of dissolved organic matter or carbon as a common nutritional pathway.
Postal code for a plant MAPK
Authors: Ellis Brian E.
Published: August 2012

Plants contain hundreds of protein kinases that are believed to provide cellular signal transduction services, but the identities of the proteins they are targeting are largely unknown. Using an Arabidopsis MAPK (mitogen-activated protein kinase) (MPK6) as a model, Sörensson et al. describe in this issue of the Biochemical Journal how arrayed combinatorial peptide scanning offers an efficient route to discovery of new potential kinase substrates.
Solution structure of the strawberry allergen Fra a 1
Authors: Seutter von Loetzen Christian , Schweimer Kristian , Schwab Wilfried , Rösch Paul , Hartl-Spiegelhauer Olivia
Published: August 2012

The PR10 family protein Fra a 1E from strawberry (Fragaria x ananassa) is down-regulated in white strawberry mutants, and transient RNAi (RNA interference)-mediated silencing experiments confirmed that Fra a 1 is involved in fruit pigment synthesis. In the present study, we determined the solution structure of Fra a 1E. The protein fold is identical with that of other members of the PR10 protein family and consists of a seven-stranded antiparallel β-sheet, two short V-shaped α-helices and a long C-terminal α-helix that encompass a hydrophobic pocket. Whereas Fra a 1E contains the glycine-rich loop that is highly conserved throughout the protein family, the volume of the hydrophobic pocket and the size of its entrance are much larger than expected. The three-dimensional structure may shed some light on its physiological function and may help to further understand the role of PR10 proteins in plants.
Angiotensin-(1–7) in kidney disease: a review of the controversies
Authors: Zimmerman Danielle , Burns Kevin D.
Published: August 2012

Ang-(1–7) [angiotensin-(1–7)] is a biologically active heptapeptide component of the RAS (renin–angiotensin system), and is generated in the kidney at relatively high levels, via enzymatic pathways that include ACE2 (angiotensin-converting enzyme 2). The biological effects of Ang-(1–7) in the kidney are primarily mediated by interaction with the G-protein-coupled receptor Mas. However, other complex effects have been described that may involve receptor–receptor interactions with AT1 (angiotensin II type 1) or AT2 (angiotensin II type 2) receptors, as well as nuclear receptor binding. In the renal vasculature, Ang-(1–7) has vasodilatory properties and it opposes growth-stimulatory signalling in tubular epithelial cells. In several kidney diseases, including hypertensive and diabetic nephropathy, glomerulonephritis, tubulointerstitial fibrosis, pre-eclampsia and acute kidney injury, a growing body of evidence supports a role for endogenous or exogenous Ang-(1–7) as an antagonist of signalling mediated by AT1 receptors and thereby as a protector against nephron injury. In certain experimental conditions, Ang-(1–7) appears to paradoxically exacerbate renal injury, suggesting that dose or route of administration, state of activation of the local RAS, cell-specific signalling or non-Mas receptor-mediated pathways may contribute to the deleterious responses. Although Ang-(1–7) has promise as a potential therapeutic agent in humans with kidney disease, further studies are required to delineate its signalling mechanisms in the kidney under physiological and pathophysiological conditions.
Impaired cerebral haemodynamic function associated with chronic traumatic brain injury in professional boxers
Authors: Bailey Damian M. , Jones Daniel W. , Sinnott Andrew , Brugniaux Julien V. , New Karl J. , Hodson Danielle , Marley Christopher J. , Smirl Jonathan D. , Ogoh Shigehiko , Ainslie Philip N.
Published: August 2012

The present study examined to what extent professional boxing compromises cerebral haemodynamic function and its association with CTBI (chronic traumatic brain injury). A total of 12 male professional boxers were compared with 12 age-, gender- and physical fitness-matched non-boxing controls. We assessed dCA (dynamic cerebral autoregulation; thigh-cuff technique and transfer function analysis), CVRCO2 (cerebrovascular reactivity to changes in CO2: 5% CO2 and controlled hyperventilation), orthostatic tolerance (supine to standing) and neurocognitive function (psychometric tests). Blood flow velocity in the middle cerebral artery (transcranial Doppler ultrasound), mean arterial blood pressure (finger photoplethysmography), end-tidal CO2 (capnography) and cortical oxyhaemoglobin concentration (near-IR spectroscopy) were continuously measured. Boxers were characterized by fronto-temporal neurocognitive dysfunction and impaired dCA as indicated by a lower rate of regulation and autoregulatory index (P<0.05 compared with controls). Likewise, CVRCO2 was also reduced resulting in a lower CVRCO2 range (P<0.05 compared with controls). The latter was most marked in boxers with the highest CTBI scores and correlated against the volume and intensity of sparring during training (r=−0.84, P<0.05). These impairments coincided with more marked orthostatic hypotension, cerebral hypoperfusion and corresponding cortical de-oxygenation during orthostatic stress (P<0.05 compared with controls). In conclusion, these findings provide the first comprehensive evidence for chronically impaired cerebral haemodynamic function in active boxers due to the mechanical trauma incurred by repetitive, sub-concussive head impact incurred during sparring training. This may help explain why CTBI is a progressive disease that manifests beyond the active boxing career.
Overtone vibrational spectroscopy in H2-H2O complexes: A combined high level theoretical ab initio, dynamical and experimental study
Authors: Ziemkiewicz Michael P. , Pluetzer Christian , Nesbitt David J. , Scribano Yohann , Faure Alexandre , van der Avoird Ad
Published: August 2012

First results are reported on overtone (vOH = 2 ← 0) spectroscopy of weakly bound H2-H2O complexes in a slit supersonic jet, based on a novel combination of (i) vibrationally mediated predissociation of H2-H2O, followed by (ii) UV photodissociation of the resulting H2O, and (iii) UV laser induced fluorescence on the nascent OH radical. In addition, intermolecular dynamical calculations are performed in full 5D on the recent ab initio intermolecular potential of Valiron et al. [J. Chem. Phys. 129, 134306 (2008)10.1063/1.2988314] in order to further elucidate the identity of the infrared transitions detected. Excellent agreement is achieved between experimental and theoretical spectral predictions for the most strongly bound van der Waals complex consisting of ortho (I = 1) H2 and ortho (I = 1) H2O (oH2-oH2O). Specifically, two distinct bands are seen in the oH2-oH2O spectrum, corresponding to internal rotor states in the upper vibrational manifold of Σ and Π rotational character. However, none of the three other possible nuclear spin modifications (pH2-oH2O, pH2-pH2O, or oH2-pH2O) are observed above current signal to noise level, which for the pH2 complexes is argued to arise from displacement by oH2 in the expansion mixture to preferentially form the more strongly bound species. Direct measurement of oH2-oH2O vibrational predissociation in the time domain reveals lifetimes of 15(2) ns and <5(2) ns for the Σ and Π states, respectively. Theoretical calculations permit the results to be interpreted in terms of near resonant energy levels and intermolecular alignment of the H2 and H2O wavefunctions, providing insight into predissociation dynamical pathways from these metastable levels.
Path integral approach to the photoionization of one active electron atom by a pulsed Fock state: Fluctuations contribution
Authors: Thrapsaniotis E. G.
Published: August 2012

We model in a fully quantum mechanical way the dynamics of an atom of one optically active electron interacting with a pulsed Fock state which is linearly polarized. We use path integral methods. We derive the system's sign solved propagator which gives full information on its dynamics. We apply our method to the ionization of atomic hydrogen by a one-photon pulsed Fock state and study the contribution of the electromagnetic fluctuations.
Assessment and mitigation of diagnostic-generated electromagnetic interference at the National Ignition Facility
Authors: Brown C. G. , Ayers J. , Felker B. , Ferguson W. , Holder J. P. , Nagel S. R. , Piston K. W. , Simanovskaia N. , Throop A. L. , Chung M. , Hilsabeck T.
Published: August 2012

Electromagnetic interference (EMI) is an ever-present challenge at laser facilities such as the National Ignition Facility (NIF). The major source of EMI at such facilities is laser-target interaction that can generate intense electromagnetic fields within, and outside of, the laser target chamber. In addition, the diagnostics themselves can be a source of EMI, even interfering with themselves. In this paper we describe EMI generated by ARIANE and DIXI, present measurements, and discuss effects of the diagnostic-generated EMI on ARIANE's CCD and on a PMT nearby DIXI. Finally we present some of the efforts we have made to mitigate the effects of diagnostic-generated EMI on NIF diagnostics.
Wide-band current preamplifier for conductance measurements with large input capacitance
Authors: Kretinin Andrey V. , Chung Yunchul
Published: August 2012

A wide-band current preamplifier based on a composite operational amplifier is proposed. It has been shown that the bandwidth of the preamplifier can be significantly increased by enhancing the effective open-loop gain. The described 107 V/A current gain preamplifier had the bandwidth of about 100 kHz with the 1 nF input shunt capacitance. The measured preamplifier current noise was 46 fA/\documentclass[12pt]{minimal}\begin{document}$\sqrt{\rm Hz}$\end{document} Hz at 1 kHz, close to the design noise minimum. The voltage noise was found to be about 2.9 nV/\documentclass[12pt]{minimal}\begin{document}$\sqrt{\rm Hz}$\end{document} Hz at 1 kHz, which is in a good agreement with the value expected for the particular operational amplifier used in the input stage. By analysing the total produced noise we found that the optimal frequency range suitable for the fast lock-in measurements is from 1 kHz to 2 kHz. To obtain the same signal-to-noise ratio, the reported preamplifier requires ∼10% of the integration time needed in measurements made with a conventional preamplifier.
Classical field isomorphisms in two-fluid plasmas
Authors: Thompson Richard J. , Moeller Trevor M.
Published: August 2012

Previous work recognized a new framework for the equations of a multifluid plasma, wherein each species can be described by a set of equations remarkably similar to the Maxwell equations of classical electrodynamics. This paper extends the previous effort to form an exact isomorphism between the multifluid theory and classical electrodynamics. The major benefits of the new formulation are that the explicit coupling between different species is minimized, and theorems and techniques of classical electrodynamics can be immediately applied to the new multifluid formulation. We introduce the exact isomorphism and investigate some of the immediate consequences from classical electrodynamics. To provide a visualization of the isomorphism, previous 1D and 2D numerical simulations are postprocessed and presented to illustrate the generalized fields and source terms.
Electron acoustic waves in a magnetized plasma with kappa distributed ions
Authors: Devanandhan S. , Singh S. V. , Lakhina G. S. , Bharuthram R.
Published: August 2012

Electron acoustic solitary waves in a two component magnetized plasma consisting of fluid cold electrons and hot superthermal ions are considered. The linear dispersion relation for electron acoustic waves is derived. In the nonlinear regime, the energy integral is obtained by a Sagdeev pseudopotential analysis, which predicts negative solitary potential structures. The effects of superthermality, obliquity, temperature, and Mach number on solitary structures are studied in detail. The results show that the superthermal index κ and electron to ion temperature ratio σ alters the regime where solitary waves can exist. It is found that an increase in magnetic field value results in an enhancement of soliton electric field amplitude and a reduction in soliton width and pulse duration.
Space-charge polarization of a dilute electrolytic cell in the presence of diffuse double layers
Authors: Sawada Atsushi
Published: August 2012

The frequency dependence of the complex dielectric constant due to space-charge polarization is analyzed for a dilute electrolytic cell with blocking electrodes in the presence of diffuse double layers. If the diffuse double layer is not generated by an external voltage application but induced by a contact potential difference between the electrode and electrolytic solution, the dielectric constant in Poisson’s equation does not include the contribution of the space-charge polarization. The space-charge polarization is measured by applying an external field. The external voltage source supplies positive and negative charges to the electrodes to keep the potential difference between the electrodes constant in the measurement. Accordingly, the dielectric constant in Poisson’s equation has to include the contribution of the space-charge polarization to take account of the external charges in the data analysis. An electrode polarization model developed with this concept can well explain the frequency-dependent behavior of the complex dielectric constant observed for the dilute electrolytic cell with the specific adsorption of ions to the electrodes.
Self-organization of amphiphilic macromolecules with local helix structure in concentrated solutions
Authors: Glagolev M. K. , Vasilevskaya V. V. , Khokhlov A. R.
Published: August 2012

Concentrated solutions of amphiphilic macromolecules with local helical structure were studied by means of molecular dynamic simulations. It is shown that in poor solvent the macromolecules are assembled into wire-like aggregates having complex core-shell structure. The core consists of a hydrophobic backbone of the chains which intertwine around each other. It is protected by the shell of hydrophilic side groups. In racemic mixture of right-hand and left-hand helix macromolecules the wire-like complex is a chain of braid bundles of macromolecules with the same chirality stacking at their ends. The average number of macromolecules in the wire cross-section is close to that of separate bundles observed in dilute solutions of such macromolecules. The effects described here could serve as a simple model of self-organization in solutions of macromolecules with local helical structure.
A generalised 17-state vibronic-coupling Hamiltonian model for ethylene
Authors: Jornet-Somoza Joaquim , Lasorne Benjamin , Robb Michael A. , Meyer Hans-Dieter , Lauvergnat David , Gatti Fabien
Published: August 2012

In a previous work [B. Lasorne, M. A. Robb, H.-D. Meyer, and F. Gatti, “The electronic excited states of ethylene with large-amplitude deformations: A dynamical symmetry group investigation,” Chem. Phys. 377, 30–45 (2010)10.1016/j.chemphys.2010.08.011; B. Lasorne, M. A. Robb, H.-D. Meyer, and F. Gatti, Chem. Phys. 382, 132 (2011) (Erratum)]10.1016/j.chemphys.2011.01.004, we investigated the electronic structure of ethylene (ethene, C2H4) in terms of 17 dominant configurations selected at the multiconfiguration self-consistent field level of theory. These were shown to be sufficient to recover most of the static electron correlation among the first valence and Rydberg states at all geometries. We also devised a strategy to build a 17-quasidiabatic-state matrix representation of the electronic Hamiltonian for curvilinear coordinates using dynamical symmetry. Here, we present fitted surfaces in the form of a generalised vibronic-coupling Hamiltonian model for two nuclear coordinates, CC bond stretching and torsion. Dynamic electron correlation is included into the electronic structure to improve the energetics of the Rydberg states at the multireference configuration interaction level of theory. The chemical interpretation of the adiabatic states of interest does not change qualitatively, which validates our choice of underlying quasidiabatic states in the model. The absorption spectrum is calculated with quantum dynamics and partially assigned. This first two-dimensional model shows a surprisingly good agreement with the experimental spectrum.
Geometrical constraints on plasma couplers for Raman compression
Authors: Toroker Z. , Malkin V. M. , Balakin A. A. , Fraiman G. M. , Fisch N. J.
Published: August 2012

Backward Raman compression in plasma is based on a 3-wave resonant interaction, which includes two counter-propagating laser pulses (pump and seed pulses) and an electron plasma wave (Langmuir wave). The resonant interaction can be ensured in nearly homogeneous plasmas. However, for high-power, large-aperture experiments, the homogeneous region becomes pancake-shaped and would likely be surrounded by thicker regions of inhomogeneous plasma. When these inhomogeneous plasma regions are extensive, significant inverse bremsstrahlung and seed dispersion may impede the compression effect. These deleterious effects may, however, be mitigated by chirping the seed and pump pulses.
Experimental observation of a strong mean flow induced by internal gravity waves
Authors: Bordes Guilhem , Venaille Antoine , Joubaud Sylvain , Odier Philippe , Dauxois Thierry
Published: August 2012

We report the experimental observation of a robust horizontal mean flow induced by internal gravity waves. A wave beam is forced at the lateral boundary of a tank filled with a linearly stratified fluid initially at rest. After a transient regime, a strong jet appears in the wave beam, with horizontal recirculations outside the wave beam. Using multiple scale analysis, we present a simple physical mechanism predicting the growth rate of the mean flow and its initial spatial structure. We find good agreement with experimental results. These results show that a mean flow with non-zero vertical vorticity can be generated by Reynolds stresses if the wave fulfils two conditions: (1) the wave amplitude must vary along its propagation direction, which is the case in the presence of viscosity; (2) the wave amplitude must vary in the lateral direction, which is the case when the wave generator is localized in space.
The influence of charged ions on the electro-optical properties of polymer-dispersed liquid crystal films prepared by ultraviolet-initiated cationic polymerization
Authors: Song Ping , Yu Lilong , Jiao Aijun , Wang Feifei , Liu Fang , Zhang Cuihong , Yang Chaoyong , Cao Hui , Yang Huai
Published: August 2012

Polymer-dispersed liquid crystal (PDLC) films based on epoxy resins were prepared by UV-initiated cationic polymerization using UVI-6974 as UV-initiator. The charged ions arose from photolysis of the UV-initiator remained in the liquid crystal (LC) droplet of the polymer matrix. Optical devices based on PDLC films derive their functional properties from the electric field induced reorientation of LC droplets. These PDLC films doped with ions showed different reorientation of LC molecules and electro-optical properties than those prepared without ionic dopants. When an electric field was applied across these PDLC films, the charged ions in the LC droplet migrated along the direction of the electric field in inducement of the electric field and assembled at the LC droplet/polymer interface. According to the situation mentioned above, the model of charged double layers at the LC droplet/polymer interface was set up in our study. The behavior was attributed to the charged double layers that cancel the field strength within the “bulk” of the liquid crystal in time. By using this model, the electric field and initiator concentration dependent results and the difference of the PDLC with and without ions were investigated and explained.
Dielectric spectroscopy and ultrasonic study of propylene carbonate under ultra-high pressures
Authors: Kondrin M. V. , Gromnitskaya E. L. , Pronin A. A. , Lyapin A. G. , Brazhkin V. V. , Volkov A. A.
Published: August 2012

We present the high pressure dielectric spectroscopy (up to 4.2 GPa) and ultrasonic study (up to 1.7 GPa) of liquid and glassy propylene carbonate (PC). Both of the methods provide complementary pictures of the glass transition in PC under pressure. No other relaxation processes except α-relaxation have been found in the studied pressure interval. The propylene carbonate liquid is a glassformer where simple relaxation and the absence of β-relaxation are registered in the record-breaking ranges of pressures and densities. The equation of state of liquid PC was extended up to 1 GPa from ultrasonic measurements of bulk modulus and is in good accordance with the previous equations developed from volumetric data. We measured the bulk and shear moduli and Poisson's ratio of glassy PC up to 1.7 GPa. Many relaxation and elastic properties of PC can be qualitatively described by the soft-sphere or Lennard-Jones model. However, for the quantitative description of entire set of the experimental data, these models are insufficient. Moreover, the Poisson coefficient value for glassy PC indicates a significant contribution of non-central forces to the intermolecular potential. The well-known correlation between Poisson's ratio and fragility index (obtained from dielectric relaxation) is confirmed for PC at ambient pressure, but it is violated with pressure increase. This indicates that different features of the potential energy landscape are responsible for the evolution of dielectric response and elasticity with pressure increase.
Resonant control of an atomic force microscope micro-cantilever for active Q control
Authors: Fairbairn M. , Moheimani S. O. R.
Published: August 2012

Active Q control may be used to modify the effective quality (Q) factor of an atomic force microscope (AFM) micro-cantilever when operating in tapping mode. The control system uses velocity feedback to obtain an effective cantilever Q factor to achieve optimal scan speed and image resolution for the imaging environment and sample type. Time delay of the cantilever displacement signal is the most common method of cantilever velocity estimation. Spill-over effects from unmodeled dynamics may degrade the closed loop system performance, possibly resulting in system instability, when time delay velocity estimation is used. A resonant controller is proposed in this work as an alternate method of velocity estimation. This new controller has guaranteed closed loop stability, is easy to tune, and may be fitted into existing commercial AFMs with minimal modification. Images of a calibration grating are obtained using this controller to demonstrate its effectiveness.
High pressure sample cell for total internal reflection fluorescence spectroscopy at pressures up to 2500 bar
Authors: Koo Juny , Czeslik Claus
Published: August 2012

Total internal reflection fluorescence (TIRF) spectroscopy is a surface sensitive technique that is widely used to characterize the structure and dynamics of molecules at planar liquid-solid interfaces. In particular, biomolecular systems, such as protein adsorbates and lipid membranes can easily be studied by TIRF spectroscopy. Applying pressure to molecular systems offers access to all kinds of volume changes occurring during assembly of molecules, phase transitions, and chemical reactions. So far, most of these volume changes have been characterized in bulk solution, only. Here, we describe the design and performance of a high pressure sample cell that allows for TIRF spectroscopy under high pressures up to 2500 bar (2.5 × 108 Pa), in order to expand the understanding of volume effects from the bulk phase to liquid-solid interfaces. The new sample cell is based on a cylindrical body made of Nimonic 90 alloy and incorporates a pressure transmitting sample cuvette. This cuvette is composed of a fused silica prism and a flexible rubber gasket. It contains the sample solution and ensures a complete separation of the sample from the liquid pressure medium. The sample solution is in contact with the inner wall of the prism forming the interface under study, where fluorescent molecules are immobilized. In this way, the new high pressure TIRF sample cell is very useful for studying any biomolecular layer that can be deposited at a planar water-silica interface. As examples, high pressure TIRF data of adsorbed lysozyme and two phospholipid membranes are presented.