bluuebunny/crossref_metadata_2025 huggingface dataset:
Observations of nonlinear runup patterns on plane and rhythmic beach morphology
Authors: Bryan K. R. , Coco Giovanni
Published: September 2010

Application of nonlinear forecasting and bispectral analysis to video observations of runup over cuspate topography shows that these alongshore patterns in the morphology are accompanied by changes to the fundamental behavior of the runup time series. Nonlinear forecasting indicates that at beach cusp horns, the behavior of swash flow is more predictable and global (meaning that characteristics of individual swash events are well represented by the behavior of the time series as a whole). Conversely, at beach cusp bays, the behavior of swash flow is less predictable and more local (meaning that the characteristics of individual swash events are best represented by the behavior of a small fraction of the time series). Bispectral analysis indicates that there is a nonlinear transfer of energy from the incident wave frequency f to the infragravity frequency ∼f/2 which only occurs in the bay, suggesting that the local behavior is caused by interactions between successive swash cycles which are magnified by channeling caused by the beach cusp geometry. The local behavior and the bispectral signatures are not present in offshore measurements, and they are not present in runup time series collected when the beach was planar. These results provide evidence that interactions between successive runups are a fundamental characteristic of beach cusp bays. Ultimately, these interactions could lead to the growth of an infragravity wave with an alongshore wavelength forced by the presence of beach cusps.
Numerical study of K1 internal tides in the Kuril straits
Authors: Tanaka Yuki , Hibiya Toshiyuki , Niwa Yoshihiro , Iwamae Nobuyuki
Published: September 2010

Tide‐induced strong diapycnal mixing in the Kuril straits is thought to be one of the essential processes controlling water mass formation in the North Pacific. In order to make a definite quantification of diapycnal diffusivity in the Kuril straits, we drive a three‐dimensional numerical model and examine the generation, propagation, and dissipation features of internal waves which play an essential role in transferring energy from the predominant K1 barotropic tide to diapycnal mixing processes. It is shown that most of the internal wave energy subtracted from the K1 barotropic tide is dissipated within the Kuril straits such that the local dissipation efficiency becomes 0.8–1.0, about three times the value previously employed. This is because the K1 tidal frequency is subinertial in this area so that significant amount of K1 tidal energy is fed into coastal trapped waves (CTWs) which stay around each island without propagating away from the straits; CTWs induce strong velocity shear near the ocean bottom causing bottom‐confined intense mixing with a vertical decay scale ∼200 m, less than half the value previously employed, although there remains some uncertainties resulting from the employed parameterizations of viscosity and diffusivity. The average diapycnal diffusivity in the Kuril straits becomes ∼25 × 10−4 m2 s−1, about three times the value previously estimated, although it is still an order of magnitude less than assumed for the Kuril straits in the existing ocean general circulation models.
Descent of deep stratospheric intrusions during the IONS August 2006 campaign
Authors: Bourqui M. S. , Trépanier P.‐Y.
Published: September 2010

Deep stratosphere‐to‐troposphere transport (STT) conveying ozone‐rich stratospheric air to the lower troposphere in the extratropics can episodically increase ozone concentrations in the lower troposphere. However, dynamical aspects of the descent, including dispersion and mixing with the surrounding tropospheric air and necessary conditions for reaching the lower troposphere, are not clearly understood yet. This study focuses on August 2006, as daily balloon sonde measurements were made from many sites covering North America within the Intercontinental Chemical Transport Experiment Ozonesonde Network Study campaign. During this period, four profiles were found with clear signs of deep STT. A mesoscale model was used together with trajectory calculation to represent these events. Over 10 days, 20 distinct clusters of trajectories were identified as significant deep STT events, including three observed. The four largest clusters carried 41, 35, 25, and 16 × 1012 kg of mass of air, respectively. A dynamical analysis was performed on the three observed events that were captured numerically. The descents showed three distinct phases: (1) crossing of the tropopause, (2) free descent, and (3) quasi‐horizontal dispersion in the lower troposphere. Clusters are rapidly sliding down sloping isentropes while being slowly diabatically cooled (approximately −1 K d−1). The tilt in the isentropes along the descent is due to an approximately equal combination of a negative potential temperature anomaly at the tropopause during phase 1 and a nearby baroclinic zone at the ground. The combination of these two conditions appears to be necessary for reaching the lower troposphere. In the three cases, the clusters stayed compact until they reach the lower troposphere, and it is estimated that approximately 80% of the ozone of stratospheric origin is released directly in the lower troposphere.
WRF/Chem‐MADRID: Incorporation of an aerosol module into WRF/Chem and its initial application to the TexAQS2000 episode
Authors: Zhang Yang , Pan Ying , Wang Kai , Fast Jerome D. , Grell Georg A.
Published: September 2010

The Model of Aerosol Dynamics, Reaction, Ionization and Dissolution (MADRID) with three improved gas/particle mass transfer approaches (i.e., bulk equilibrium (EQUI), hybrid (HYBR), and kinetic (KINE)) has been incorporated into the Weather Research and Forecast/Chemistry Model (WRF/Chem) (referred to as WRF/Chem‐MADRID) and evaluated with a 5‐day episode from the 2000 Texas Air Quality Study (TexAQS2000). WRF/Chem‐MADRID demonstrates an overall good skill in simulating surface/aloft meteorological parameters and chemical concentrations of O3 and PM2.5, tropospheric O3 residuals, and aerosol optical depths. The discrepancies can be attributed to inaccuracies in meteorological predictions (e.g., overprediction in mid‐day boundary layer height), sensitivity to meteorological schemes used (e.g., boundary layer and land‐surface schemes), inaccurate total emissions or their hourly variations (e.g., HCHO, olefins, other inorganic aerosols) or uncounted wildfire emissions, uncertainties in initial and boundary conditions for some species (e.g., other inorganic aerosols, CO, and O3) at surface and aloft, and some missing/inactivated model treatments for this application (e.g., chlorine chemistry and secondary organic aerosol formation). Major differences in the results among the three gas/particle mass transfer approaches occur over coastal areas, where EQUI predicts higher PM2.5 than HYBR and KINE due to improperly redistributing condensed nitrate from chloride depletion process to fine PM mode. The net direct, semi‐direct, and indirect effects of PM2.5 decrease domainwide shortwave radiation by 11.2–14.4 W m−2 (or 4.1–5.6%) and near‐surface temperature by 0.06–0.14°C (or 0.2–0.4%), lead to 125 to 796 cm−3 cloud condensation nuclei at a supersaturation of 0.1%, produce cloud droplet numbers as high as 2064 cm−3, and reduce domainwide mean precipitation by 0.22–0.59 mm day−1.
Semi‐diurnal tidal ellipse variability in a region of freshwater influence
Authors: Verspecht F. , Simpson J. H. , Rippeth T. P.
Published: September 2010

New insight into a key process, instrumental in the onset of stratification in tidally driven systems, is presented for the first time using long‐term field observations from the Liverpool Bay region of freshwater influence (ROFI). Tidal ellipses respond to changes in stratification, becoming more circular with greater vertical structure, and reveal variability in response to tidal straining. An inflection point that occurs before the maximum vertical density difference, at the time of maximum positive bed‐surface cross‐shore shear, is identified as the crucial point where the water column abruptly decouples. The surface and bed layers then rotate in clockwise and anti‐clockwise directions, respectively. The maximum vertical stratification is observed when the maximum negative bed‐surface along‐shore shear is reached. Decoupling to a two‐layer system is therefore not the smooth progression predicted using turbulence closure models, but rather a very sudden switch, highlighting the importance of the role of Reynolds stresses.
Temporal and spatial precursors in the ionospheric global positioning system (GPS) total electron content observed before the 26 December 2004 M9.3 Sumatra–Andaman Earthquake
Authors: Liu J. Y. , Chen Y. I. , Chen C. H. , Hattori K.
Published: September 2010

We report seismo‐ionospheric precursors of anomalous decreases in the total electron content (TEC) appearing day 5 prior to an M9.3 earthquake, the largest one in the last five decades, which occurred in Sumatra‐Andaman, Indonesia on 26 December 2004. Sequences of global ionosphere maps of the TEC derived from worldwide ground‐based receivers of the global positioning system (GPS) are used to statistically study the temporal and spatial precursors of the earthquake. It was found that the temporal precursor of the GPS TEC around the epicenter was significantly reduced during the afternoon period on d 5 before the earthquake. The spatial precursors prominently, persistently, and simultaneously appear around the epicenter and its conjugate areas of the Sumatra‐Andaman earthquake.
Sensitive and specific immunological detection methods for porcine endogenous retroviruses applicable to experimental and clinical xenotransplantation
Authors: Tacke Stefan J. , Bodusch Kirsten , Berg Angelika , Denner Joachim
Published: September 2010

Abstract: The use of organs from transgenic pigs for xenotransplantation may be associated with the risk of transmission of microorganisms, especially when the transgenic pigs express human proteins influencing complement activation. The porcine endogenous retroviruses (PERVs) are of particular concern as they can infect human cells in vitro. However, it is unknown whether PERVs can infect transplant recipients in vivo and, if so, whether they are pathogenic. It is therefore essential for experimental and clinical xenotransplantation procedures that specific and sensitive screening methods for PERVs are established. We developed Western blot and enzyme‐linked immunosorbant assays (ELISA) based on purified PERVs produced by pig and human cells or recombinant viral protein and synthetic peptides corresponding to PERVs' transmembrane envelope protein, respectively. PERV‐specific anti‐sera generated against purified virus particles, purified viral proteins and synthetic peptides served as positive controls. Both assays were used for screening the sera of healthy blood donors, pregnant women, patients treated with pig tissues, and butchers with extensive contact to living porcine material to detect antibodies against PERV. None of the individuals showed an antibody pattern characteristic for retroviral infections. Some individuals had antibodies reactive against the major capsid protein p27, against smaller viral proteins of the group specific antigen (Gag) in Western blot assays, or against peptides in the ELISA, probably due to cross‐reactivity. Here, we present specific and highly sensitive screening methods applicable for future xenotransplantation procedures, but using these methods we found no evidence of PERV‐infection among humans potentially at risk.
Quantitative analysis of a deeply sequenced marine microbial metatranscriptome
Authors: Gifford Scott M , Sharma Shalabh , Rinta-Kanto Johanna M , Moran Mary Ann
Published: September 2010

The potential of metatranscriptomic sequencing to provide insights into the environmental factors that regulate microbial activities depends on how fully the sequence libraries capture community expression (that is, sample-sequencing depth and coverage depth), and the sensitivity with which expression differences between communities can be detected (that is, statistical power for hypothesis testing). In this study, we use an internal standard approach to make absolute (per liter) estimates of transcript numbers, a significant advantage over proportional estimates that can be biased by expression changes in unrelated genes. Coastal waters of the southeastern United States contain 1 × 1012 bacterioplankton mRNA molecules per liter of seawater (∼200 mRNA molecules per bacterial cell). Even for the large bacterioplankton libraries obtained in this study (∼500 000 possible protein-encoding sequences in each of two libraries after discarding rRNAs and small RNAs from >1 million 454 FLX pyrosequencing reads), sample-sequencing depth was only 0.00001%. Expression levels of 82 genes diagnostic for transformations in the marine nitrogen, phosphorus and sulfur cycles ranged from below detection (<1 × 106 transcripts per liter) for 36 genes (for example, phosphonate metabolism gene phnH, dissimilatory nitrate reductase subunit napA) to >2.7 × 109 transcripts per liter (ammonia transporter amt and ammonia monooxygenase subunit amoC). Half of the categories for which expression was detected, however, had too few copy numbers for robust statistical resolution, as would be required for comparative (experimental or time-series) expression studies. By representing whole community gene abundance and expression in absolute units (per volume or mass of environment), ‘omics’ data can be better leveraged to improve understanding of microbially mediated processes in the ocean.
The Effects of Consuming Frequent, Higher Protein Meals on Appetite and Satiety During Weight Loss in Overweight/Obese Men
Authors: Leidy Heather J. , Tang Minghua , Armstrong Cheryl L.H. , Martin Carmen B. , Campbell Wayne W.
Published: September 2010

The purpose of this study was to determine the effects of dietary protein and eating frequency on perceived appetite and satiety during weight loss. A total of 27 overweight/obese men (age 47 ± 3 years; BMI 31.5 ± 0.7 kg/m2) were randomized to groups that consumed an energy‐restriction diet (i.e., 750 kcal/day below daily energy need) as either higher protein (HP, 25% of energy as protein, n = 14) or normal protein (NP, 14% of energy as protein, n = 13) for 12 weeks. Beginning on week 7, the participants consumed their respective diets as either 3 eating occasions/day (3‐EO; every 5 h) or 6 eating occasions/day (6‐EO; every 2 h), in randomized order, for 3 consecutive days. Indexes of appetite and satiety were assessed every waking hour on the third day of each pattern. Daily hunger, desire to eat, and preoccupation with thoughts of food were not different between groups. The HP group experienced greater fullness throughout the day vs. NP (511 ± 56 vs. 243 ± 54 mm · 15 h; P < 0.005). When compared to NP, the HP group experienced lower late‐night desire to eat (13 ± 4 vs. 27 ± 4 mm, P < 0.01) and preoccupation with thoughts of food (8 ± 4 vs. 21 ± 4 mm; P < 0.01). Within groups, the 3 vs. 6‐EO patterns did not influence daily hunger, fullness, desire to eat, or preoccupation with thoughts of food. The 3‐EO pattern led to greater evening and late‐night fullness vs. 6‐EO but only within the HP group (P < 0.005). Collectively, these data support the consumption of HP intake, but not greater eating frequency, for improved appetite control and satiety in overweight/obese men during energy restriction‐induced weight loss.
Feeding Frequency and Appetite in Lean and Obese Prepubertal Children
Authors: Mehra Rinku , Tsalikian Eva , Chenard Catherine A. , Zimmerman M. Bridget , Sivitz William I.
Published: September 2010

To determine the effect of feeding frequency on appetite in normal weight (NW) and obese (OB) prepubertal children, we carried out a prospective, randomized interventional study of 18 NW and 17 OB children ages 6–10. Children received three or five feedings in random order on separate days. Total calories, carbohydrate, protein, and fat composition on each day were equal. Two hours following the last feeding, children were offered ice cream ad lib. The major outcome variable was kilocalories ice cream consumed. A visual analog scale to assess fullness was also administered before consumption of ice cream. We observed that OB children consumed 73.0 ± 37.4 kcal more after five feedings than after three feedings whereas the NW children consumed 47.1 ± 27.8 kcal less. There was significant interaction between meal pattern and weight group indicating that this change in ice cream consumption differed significantly between groups (P = 0.014 by two‐factor analysis). Ice cream intake/kg was less in OB compared to NW subjects (P = 0.012). Fullness ratings before ice cream did not differ by meal pattern or weight group. However, pre‐ice cream fullness predicted ice cream intake in NW but not OB children. In summary, OB and NW children differed in appetite response to meal frequency. Our data suggest that: (i) satiety in OB children is related more to proximity of calories (larger supper) than to antecedent distribution of calories and; (ii) NW children may be more prone to restrict intake based on subjective fullness.
The Effect of Electronic Self‐Monitoring on Weight Loss and Dietary Intake: A Randomized Behavioral Weight Loss Trial
Authors: Burke Lora E. , Conroy Molly B. , Sereika Susan M. , Elci Okan U. , Styn Mindi A. , Acharya Sushama D. , Sevick Mary A. , Ewing Linda J. , Glanz Karen
Published: September 2010

Technology may improve self‐monitoring adherence and dietary changes in weight loss treatment. Our study aimed to investigate whether using a personal digital assistant (PDA) with dietary and exercise software, with and without a feedback message, compared to using a paper diary/record (PR), results in greater weight loss and improved self‐monitoring adherence. Healthy adults (N = 210) with a mean BMI of 34.01 kg/m2 were randomized to one of three self‐monitoring approaches: PR (n = 72), PDA with self‐monitoring software (n = 68), or PDA with self‐monitoring software and daily feedback messages (PDA+FB, n = 70). All participants received standard behavioral treatment. Self‐monitoring adherence and change in body weight, waist circumference, and diet were assessed at 6 months; retention was 91%. All participants had a significant weight loss (P < 0.01) but weight loss did not differ among groups. A higher proportion of PDA+FB participants (63%) achieved ≥5% weight loss in comparison to the PR group (46%) (P < 0.05) and PDA group (49%) (P = 0.09). Median percent self‐monitoring adherence over the 6 months was higher in the PDA groups (PDA 80%; PDA+FB 90%) than in the PR group (55%) (P < 0.01). Waist circumference decreased more in the PDA groups than the PR group (P = 0.02). Similarly, the PDA groups reduced energy and saturated fat intake more than the PR group (P < 0.05). Self‐monitoring adherence was greater in the PDA groups with the greatest weight change observed in the PDA+FB group.
Biomass Gasification
Authors: Neathery James K.
Published: September 2010

Gasifier reactors are relatively simple in construction, although the chemistry and physics involved in their operation is still not well understood. Consequently, the practice of gasification involves as much art as science. There are many papers available in the literature regarding modeling of gasifier reactors that provide an abundance of information that is helpful for reactor design. However, there are limited resources available to those individuals with the goal of successfully operating a gasifier system with biomass fuels. Therefore, the intent of this chapter is to give an overview of the gasification processes used to convert biomass fuels into a producer gas. Gasifier designs are generally categorized into three types: downdraft, updraft, and fluidized beds. Selection of a specific gasifier type will depend on the end use and the quantity of the producer gas required. The focus here will be on the practical aspects of gasification for small to medium-scale systems. Practical issues addressed in this chapter are: gasifier fuels; performance evaluation; fuel feeding; process control; and producer gas quality.
Conversion of Biomass to Liquid Fuels and Chemicals via the Fischer–Tropsch Synthesis Route
Authors: Jacobs Gary , Davis Burtron H.
Published: September 2010

The chapter opens by examining how the Fischer-Tropsch synthesis (FT) reaction will likely take on an increasing role in the near-term for supplying high quality, high energy density transportation fuels, such as diesel and jet fuel, as well as chemicals; in the more distant future, FT products may serve as chemical carriers of hydrogen for mobile fuel cell applications. The flexibility of fuels produced from FT and upgrading lies in the fact that the syngas feed can be derived not only from natural gas and coal, but also from biomass and coal/biomass blends which aim to reduce carbon dioxide emissions. Considerations to be taken into account in converting biomass-derived syngas are then investigated, including the potential contaminants generated from the gasification of biomass that may poison downstream water-gas shift and FT catalysts, as well as the importance of capturing and sequestering or fixing carbon dioxide and sulfur. The general aspects of FT catalyst selection and reactor configuration are then discussed before moving to the specific issues of product tailoring, reaction kinetics, catalytic mechanisms, and the structure-function relationships of iron and cobalt FT catalysts.
Hydrothermal Processing of Biomass
Authors: Savage P. E. , Levine R. B. , Huelsman C. M.
Published: September 2010

Biomass can be reformed into higher-value fuels using hydrothermal processes that employ high-temperature and high-pressure water as a reaction medium. Hydrothermal processing obviates feedstock drying and can achieve high energy efficiencies through heat integration. Hydrothermal liquefaction occurs under mild conditions (250–350 °C) in which biomass hydrolyzes rapidly and reacts to form a viscous bio-crude oil. At higher temperatures (350–500 °C), catalysts may be employed to promote the formation of CH4-rich gas in the process of catalytic hydrothermal gasification. Supercritical conditions (500–800 °C) may be used to achieve a H2-rich gas through supercritical water gasification (SCWG). The reaction chemistry underlying these hydrothermal processes is complex and not fully understood, but the influence of temperature, pressure, feedstock concentration, and the presence of catalysts on this chemistry has been extensively studied. In this chapter, we review hydrothermal processing of biomass, with a focus on the chemistry that describes biomass conversion under various hydrothermal conditions. Special attention is given to the relatively recent interest in processing aquatic feedstocks, such as algae, in a hydrothermal environment.
Catalysts in Biomass Pyrolysis
Authors: Lappas Angelos A. , Iliopoulou Eleni F. , Kalogiannis K.
Published: September 2010

One of the most promising suggested methods either to improve the quality of bio-oil (the liquid or oil fraction produced via biomass pyrolysis) by minimizing its undesirable properties (high viscosity, corrosivity, instability, etc.) or to increase the production of valuable chemical products is the application of heterogeneous catalysis. The most appropriate process for biomass catalytic pyrolysis should be based on the circulating fluid bed (CFB) technology, overviewed in this study. Upgrading of bio-oil can be achieved either during or after its production process. The first case refers to the application of heterogeneous catalysis in biomass pyrolysis (in-situ catalytic upgrading), which decreases organic yield but significantly improves bio-oil composition. A plethora of micro- (zeolitic) or meso-porous (Al-MCM-41) acid materials have been tested, either promoted or not with several transition metals. Lately basic materials are also suggested as promising candidate catalysts for biomass catalytic pyrolysis, however tailoring of their acidity/basicity and porosity characteristics is still needed to develop an optimized catalyst. Conversion of biomass compounds (e.g., aqueous glucose feedstocks) to aromatics is also studied using metal-promoted catalysts. Downstream upgrading of the pyrolytic oils, mainly focusing on their deoxygenation, is attempted either by a typical catalytic hydrotreatment with hydrogen and carbon monoxide under high pressure and/or in the presence of hydrogen donor solvents or utilizing zeolitic cracking catalysts. Lately, integration of bio-oil upgrading in a conventional petrochemical refinery is approached via co-processing bio-oil with conventional oil refinery feedstocks; this approach has received great interest both from research groups and big oil companies.
Heterogeneous Catalysts for Biodiesel Production
Authors: Dacquin Jean-Philippe , Lee Adam F. , Wilson Karen
Published: September 2010

The combination of dwindling oil reserves and growing concerns over carbon dioxide emissions and associated climate change is driving the urgent development of clean, sustainable energy supplies. Biodiesel is non-toxic and biodegradable, with the potential for closed CO2 cycles and thus vastly reduced carbon footprints compared with petroleum fuels. However, current manufacturing routes employing soluble catalysts are very energy inefficient and produce copious amounts of contaminated water waste. This review highlights the significant progress made in recent years towards developing solid acid and base catalysts for biodiesel synthesis. Issues to be addressed in the future are also discussed including the introduction of non-edible oil feedstocks, as well as technical advances in catalyst and reactor design to ensure that biodiesel remains a key player in the renewable energy sector for the 21st century.
Catalytic Conversion of Glycerol to Valuable Commodity Chemicals
Authors: Beltramini Jorge N , Zhou Chun-Hui (Clayton)
Published: September 2010

The recent progress of research and development on the catalytic selective conversion of glycerol to valuable commodity chemicals is reviewed in this chapter. Glycerol is currently produced in large quantities during the biodiesel process and as such is an important and useful by-product. The reaction networks of the different processes such as selective oxidation, hydrogenation, dehydrogenation, hydrogenolysis, gasification, etc., are discussed as a function of the type of catalyst (supported noble or non-noble metal catalysts, porous oxides, micro- and mesoporous) and reaction conditions on the selectivity to desired products. In conclusion, the effective utilization of glycerol will be a key factor that can promote biodiesel commercialization and further development. As a biomass-derived chemical feedstock, its utilization is also part of the global challenge aiming at the production of marketable chemicals via the catalytic transformation of biosustainable resources employed as substitutes for fossil fuels and fine chemicals.
A general and concise asymmetric synthesis of sphingosine, safingol and phytosphingosinesviatethered aminohydroxylation
Authors: Kumar Pradeep , Dubey Abhishek , Puranik Vedavati G.
Published: September 2010

A novel, practical and efficient enantioselective synthesis of sphingoid bases,l-threo-[2S,3S]-sphinganine (safingol),l-threo-[2S,3S]-sphingosine,l-arabino-[2R,3S,4R] andl-xylo-[2R,3S,4S]-C18-phytosphingosine is described. The synthetic strategy features the Sharpless kinetic resolution and tethered aminohydroxylation as the key steps.
Modified Spectral Tilt Affects Older, but Not Younger, Infants' Native-Language Fricative Discrimination
Authors: Beach Elizabeth Francis , Kitamura Christine
Published: September 2010

Purpose

It is important to ensure that hearing aid fitting strategies for infants take into account the infant’s developing speech perception system. As a way of exploring this issue, this study examined how 6- and 9-month-olds with normal hearing perceive native-language speech in which the natural spectral shape was altered to emphasize either high-frequency (positive spectral tilt) or low-frequency (negative spectral tilt) information.

Method

Discrimination was tested using a visual habituation procedure. Forty-eight 6-month-olds and forty-eight 9-month-olds were presented with a fricative contrast, /f/–/s/, in 1 of 3 conditions: (a) as unmodified speech; (b) with a −6 dB/octave tilt; or (c) with a +6 dB/octave tilt.

Results

Six-month-olds showed evidence of discriminating /f/–/s/ in all 3 conditions, but 9-month-olds showed such evidence only in the unmodified condition.

Conclusions

The findings suggest that the perceptual reorganization that emerges for consonants at the end of the first year affects 9-month-olds' discrimination of native speech sounds. Perceptual reorganization is usually indexed by a decline in the ability to discriminate nonnative speech sounds. In this study, 6-month-olds demonstrated an acoustic-based sensitivity to both modified and unmodified native speech sounds, but 9-month-olds were most sensitive to the unmodified speech sounds that adhered to the native spectral profile.
Are False-Positive Rates Leading to an Overestimation of Noise-Induced Hearing Loss?
Authors: Schlauch Robert S. , Carney Edward
Published: September 2010

Purpose

To estimate false-positive rates for rules proposed to identify early noise-induced hearing loss (NIHL) using the presence of notches in audiograms.

Method

Audiograms collected from school-age children in a national survey of health and nutrition (the Third National Health and Nutrition Examination Survey [NHANES III]; National Center for Health Statistics, 1994) were examined using published rules for identifying noise notches at various pass–fail criteria. These results were compared with computer-simulated “flat” audiograms. The proportion of these identified as having a noise notch is an estimate of the false-positive rate for a particular rule.

Results

Audiograms from the NHANES III for children 6–11 years of age yielded notched audiograms at rates consistent with simulations, suggesting that this group does not have significant NIHL. Further, pass–fail criteria for rules suggested by expert clinicians, applied to NHANES III audiometric data, yielded unacceptably high false-positive rates.

Conclusions

Computer simulations provide an effective method for estimating false-positive rates for protocols used to identify notched audiograms. Audiometric precision could possibly be improved by (a) eliminating systematic calibration errors, including a possible problem with reference levels for TDH-style earphones; (b) repeating and averaging threshold measurements; and (c) using earphones that yield lower variability for 6.0 and 8.0 kHz—2 frequencies critical for identifying noise notches.
Effect of Parkinson’s Disease on the Production of Structured and Unstructured Speaking Tasks: Respiratory Physiologic and Linguistic Considerations
Authors: Huber Jessica E. , Darling Meghan
Published: September 2010

Purpose

To examine the effects of cognitive–linguistic deficits and respiratory physiologic changes on respiratory support for speech in individuals with Parkinson’s disease (PD) using two speech tasks: reading and extemporaneous speech.

Method

Five women with PD, 9 men with PD, and 14 age- and sex-matched control participants read a passage and spoke extemporaneously on a topic of their choice at comfortable loudness. Sound pressure level, syllables per breath group, speech rate, and lung volume parameters were measured. Number of formulation errors, disfluencies, and filled pauses were counted.

Results

Individuals with PD produced shorter utterances compared with control participants. The relationships between utterance length and lung volume initiation and inspiratory duration were weaker for individuals with PD than for control participants, particularly for the extemporaneous speech task. These results suggest less consistent planning for utterance length by individuals with PD in extemporaneous speech. Individuals with PD produced more formulation errors in both tasks and significantly fewer filled pauses in extemporaneous speech.

Conclusion

Both respiratory physiologic and cognitive–linguistic issues affected speech production by individuals with PD. Overall, individuals with PD had difficulty planning or coordinating language formulation and respiratory support, particularly during extemporaneous speech.
Perception of Suprasegmental Speech Features via Bimodal Stimulation: Cochlear Implant on One Ear and Hearing Aid on the Other
Authors: Most Tova , Harel Tamar , Shpak Talma , Luntz Michal
Published: September 2010

Purpose

The purpose of the study was to evaluate the contribution of acoustic hearing to the perception of suprasegmental features by adults who use a cochlear implant (CI) and a hearing aid (HA) in opposite ears.

Method

23 adults participated in this study. Perception of suprasegmental features—intonation, syllable stress, and word emphasis—was assessed. All tests were administered in 2 conditions: CI alone and CI + HA (bimodal).

Results

Scores were significantly higher in the bimodal condition in comparison to scores in CI alone for all 3 tests. In both conditions, there was great variability among the individual participants. Significant negative correlations emerged between perception of suprasegmental features and the unaided pure-tone average of the contralateral ear to the CI.

Conclusions

This study found a significant bimodal advantage for perception of all suprasegmental features, most probably due to the better low-frequency acoustic hearing that is provided by the HA. Outcomes suggest that in cases of residual hearing in the contralateral ear to the implanted ear, HA use should be encouraged.
Reducing the Effects of Background Noise During Auditory Functional Magnetic Resonance Imaging of Speech Processing: Qualitative and Quantitative Comparisons Between Two Image Acquisition Schemes and Noise Cancellation
Authors: Blackman Graham A. , Hall Deborah A.
Published: September 2010

Purpose

The intense sound generated during functional magnetic resonance imaging (fMRI) complicates studies of speech and hearing. This experiment evaluated the benefits of using active noise cancellation (ANC), which attenuates the level of the scanner sound at the participant’s ear by up to 35 dB around the peak at 600 Hz.

Method

Speech and narrowband noise were presented at a low sound level to 8 listeners during fMRI using 2 common scanning protocols: short (“continuous”) and long (“sparse”) temporal schemes. Three outcome measures were acquired simultaneously during fMRI: ratings of listening quality, discrimination performance, and brain activity.

Results

Subjective ratings and discrimination performance were significantly improved by ANC and sparse acquisition. Sparse acquisition was the more robust method for detecting auditory cortical activity. ANC reduced some of the “extra-auditory” activity that might be associated with the effort required for perceptual discrimination in a noisy environment and also offered small improvements for detecting activity within Heschl’s gyrus and planum polare.

Conclusions

For the scanning protocols evaluated here, the sparse temporal scheme was the more preferable for detecting sound-evoked activity. In addition, ANC ensures that listening difficulty is determined more by the chosen stimulus parameters and less by the adverse testing environment.
Colonization of an island volcano, Long Island, Papua New Guinea, and an emergent island, Motmot, in its caldera lake. II. The vascular flora
Authors: Harrison Rhett D. , Banka Roy , Thornton Ian W. B. , Shanahan Mike , Yamuna Ruby
Published: September 2010

AimLong Island erupted catastrophically inc. 1645 with the probable destruction of its entire biota. While several expeditions have visited the island since, no survey of its flora has been published. In 1968 a small island, Motmot, emerged from its caldera lake. Motmot has been surveyed several times but not since 1988. The aim of this study was to investigate the colonization by vascular plants of this interesting nested pair of islands.

LocationLong Island is 55 km off the northeast coast of Papua New Guinea (PNG) and Motmot lies in its fresh water caldera lake, Lake Wisdom,c. 4 km from the rim of the surrounding volcano.

MethodsWe conducted a complete survey of the vascular plants on Motmot and madead hoccollections on Long Island, including surveying three small plots, over 15 days in 1999. In addition, we incorporated data from several collections lodged at the regional herbarium in Lae. Data on seed dispersal syndromes and plant habit were obtained from the literature.

ResultsWe recorded 305 species of vascular plants from Long Island, but most trees were small and the species diversity was low. Motmot was still very sparsely vegetated and only forty‐five species of vascular plants were found. Communities on Motmot were unspecialized and common species widespread. The flora of Motmot was not significantly different from that on Long Island in terms of the number of species amongst higher taxa, seed dispersal syndromes or plant habits.

Main conclusionsLow rainfall combined with very porous soils may be responsible for the small stature and low diversity of the forest on Long Island's caldera rim. The absence of specialist littoral species on Motmot, as a result of its landlocked situation, is probably responsible for the very slow species recruitment on the island. This community appears to be functionally important for colonization by comparison with other small volcanic islands in a marine situation.
Colonization of an island volcano, Long Island, Papua New Guinea, and an emergent island, Motmot, in its caldera lake. IV. Colonization by non‐avian vertebrates
Authors: Cook S. , Singidan R. , Thornton I. W. B.
Published: September 2010

Aim In a 1999 expedition we surveyed the non‐avian vertebrates recolonizing a volcanic island off the north coast of Papua New Guinea, and the more recently emerged islet in its caldera lake. It is our intention with this research to document the reassembly of an ecosystem after a cataclysmic event at two temporal stages.

Location Long Island, 55 km north of Papua New Guinea, erupted explosively in the seventeenth century. Its biota was destroyed and the island has been recolonized by animals and plants. From about 1953 to 1968, an island, Motmot, emerged from Long's freshwater caldera lake about 4 km from the nearest shore.

Methods For 15 days in 1999 we surveyed the mammals, reptiles and amphibians of Motmot and the western parts of Long.

Results We assess the present fauna as thirteen mammals, fourteen reptiles and two amphibians.

Main conclusions Long appears to have a high proportion of tramp‐type species in its bat fauna, indicative of a developing biota. Several groups, especially snakes and amphibians, appear to be depauperate compared to the fauna of other islands in the area. On Motmot we recorded only one species of insectivorous bat; its vertebrate fauna is still in the very first stages of development.
Colonization of an island volcano, Long Island, Papua New Guinea, and an emergent island, Motmot, in its caldera lake. VI. The pioneer arthropod community of Motmot
Authors: Edwards John S. , Thornton Ian W. B.
Published: September 2010

Aim To evaluate the arthropod community of Motmot in relation to primary colonization of young volcanic surfaces.

Location Motmot, an island in Lake Wisdom which occupies the caldera of Long Island, Papua New Guinea.

Methods Arthropod sampling by means of pitfall, water and tube traps, fallout collectors, and hand collecting.

Results At least thirty‐five species of arthropod were collected in 6 days between 23 June and 3 July 1999. Lycosid spiders and ants dominated in all areas. The predator‐scavenger arthropod population is largely or entirely dependent on allochthonous input of aquatic insects from the surrounding lake.

Main conclusions Major changes in the arthropod fauna since the pioneer surveys of Ball and his colleagues in the 1970s are the loss of a strand flotsam community as the island has eroded to form a predominantly cliffed coastline. Ant and spider diversity has increased. The current colonists include a number of widespread ‘tramp' species sensu Diamond.
Novel Visualisation and Analysis of Natural and Complex Systems Using Systemic Computation
Authors: Martelot Erwan Le , Bentley Peter J.
Published: September 2010

The study, analysis and understanding of natural processes are difficult tasks considering the complex nature of such processes. In this respect, the visual analysis of such systems can be of great help in the understanding of their behaviour. The increasing power of modern computers enables novel possible uses of computer graphics for such tasks. Previous work introduced systemic computation, a new model of computation and corresponding computer architecture aiming at enabling a clear formalism of natural and complex systems and providing tools for their analysis. Here, we present an online visualisation of dynamic systems based on this novel paradigm. The observation is done at a high level of abstraction, focussing on information flow, interactions and emergent behaviour, and enabling the identification of similarities and differences between models of complex systems. This visualisation framework is then applied to two biological networks: a bistable gene network and a MAPK signalling cascade.
Determination of the interface δ-hole density in a blue-emitting organic semiconductor diode by electromodulated absorption spectroscopy
Authors: Zhou Mi , Png Rui-Qi , Sivaramakrishnan Sankaran , Chia Perq-Jon , Yong Chaw-Keong , Chua Lay-Lay , Ho Peter K. H.
Published: September 2010

The hole density at the interface of a poly(fluorene-alt-triarylamine) (TFB) with p-doped poly(3,4-ethylenedioxythiophene) (PEDT) anodes has been determined from electromodulation of the TFB subgap polaron band. At 295 K, this δ-hole density σOSC is approximately 1×1012 cm−2, for which the current–voltage characteristics indicate an Ohmic contact. However at 30 K, σOSC falls to 2×1011 cm−2, and the contact characteristics approach the injecting-blocking boundary. The PEDT/TFB vacuum offset inside the device is inferred to be 0.1 eV, and so the Fermi level is not as deeply pinned in the TFB gap as suggested by ultraviolet photoemission measurements.
A Lanczos-chain driven approach for calculating damped vibrational configuration interaction response functions
Authors: Hansen Mikkel Bo , Seidler Peter , Győrffy Werner , Christiansen Ove
Published: September 2010

We present an approach based on the Lanczos method for calculating the vibrational configuration interaction response functions necessary for evaluating the pure vibrational contributions to the polarizabilities and first hyperpolarizabilities of molecules. The method iteratively builds a tridiagonal representation of the central response matrix, which is subsequently used for solving the response equations. From the same chain, the response functions can be evaluated approximately for any frequency as well as using any complex damping factor. Applications to formaldehyde, cyclopropene, and uracil illustrate the concepts presented.
Discussion of some “trap signatures” observed by admittance spectroscopy in CdTe thin-film solar cells
Authors: Li Jian V. , Johnston Steve W. , Li Xiaonan , Albin David S. , Gessert Timothy A. , Levi Dean H.
Published: September 2010

Considerable ambiguity and controversy exist concerning the defect signatures (H1, H2, and H3) frequently observed in admittance spectroscopy of thin-film CdTe solar cells. We prove that the commonly labeled H1 defects, observed in all devices in this study, are actually due to the freeze-out of the majority carriers in the neutral CdTe absorber. This freeze-out is evident in the temperature dependencies of capacitance, carrier concentration, and depletion region width. Contrary to intuitive expectation, the activation energy of freeze-out is less than, not identical to, that of the conductivity. In some other cases, H2 or H3 are observed and attributed to the back-contact potential barrier, rather than to the carrier emission from the traps. We extract the back-contact barrier height from the activation energy of the saturation current determined from the temperature-dependent current-voltage curves using the back-to-back diode model. The back-contact barrier height agrees well with the H2 or H3 energy determined by admittance spectroscopy. We present a more comprehensive and realistic equivalent circuit that includes the admittances from both the back-contact and the neutral absorber.
Time-dependent density functional theory for quantum transport
Authors: Zheng Xiao , Chen GuanHua , Mo Yan , Koo SiuKong , Tian Heng , Yam ChiYung , Yan YiJing
Published: September 2010

Based on our earlier works [X. Zheng et al., Phys. Rev. B 75, 195127 (2007); J. S. Jin et al., J. Chem. Phys. 128, 234703 (2008)], we propose a rigorous and numerically convenient approach to simulate time-dependent quantum transport from first-principles. The proposed approach combines time-dependent density functional theory with quantum dissipation theory, and results in a useful tool for studying transient dynamics of electronic systems. Within the proposed exact theoretical framework, we construct a number of practical schemes for simulating realistic systems such as nanoscopic electronic devices. Computational cost of each scheme is analyzed, with the expected level of accuracy discussed. As a demonstration, a simulation based on the adiabatic wide-band limit approximation scheme is carried out to characterize the transient current response of a carbon nanotube based electronic device under time-dependent external voltages.
Stretched exponential dynamics in lipid bilayer simulations
Authors: Brandt Erik G. , Edholm Olle
Published: September 2010

The decay of fluctuations in fluid biomembranes is strongly stretched and nonexponential on nanometer lengthscales. We report on calculations of structural correlation functions for lipid bilayer membranes from atomistic and coarse-grained molecular dynamics simulations. The time scales extend up to microseconds, whereas the linear size of the largest systems is around 50 nm. Thus, we can cover the equilibrium dynamics of wave vectors over two orders of magnitude (0.2–20 nm−1). The time correlations observed in the simulations are best described by stretched exponential functions, with exponents of 0.45 for the atomistic and 0.60 for the coarse-grained model. Area number density fluctuations, thickness fluctuations, and undulations behave dynamically in a similar way and have almost exactly the same dynamics for wavelengths below 3 nm, indicating that in this regime undulations and thickness fluctuations are governed by in-plane density fluctuations. The out-of-plane height fluctuations are apparent only at the longest wavelengths accessible in the simulations (above 6 nm). The effective correlation times of the stretched exponentials vary strongly with the wave vector. The variation fits inverse power-laws that change with wavelength. The exponent is 3 for wavelengths smaller than about 1.25 nm and switches to 1 above this. There are indications for a switch to still another exponent, 2, for wavelengths above 20 nm. Compared to neutron spin-echo (NSE) experiments, the simulation data indicate a faster relaxation in the hydrodynamic limit, although an extrapolation of NSE data, as well as inelastic neutron scattering data, is in agreement with our data at larger wave vectors.