bluuebunny/crossref_metadata_2025 huggingface dataset:
Modeling ULF waves in a compressed dipole magnetic field
Authors: Degeling A. W. , Rankin R. , Kabin K. , Rae I. J. , Fenrich F. R.
Published: October 2010

This paper presents the results of a linear model for global scale magneto‐hydrodynamic (MHD) waves in a compressed dipole model magnetosphere. We examine scenarios where a localized monochromatic source along the magnetopause boundary launches MHD fast mode ultralow frequency (ULF) waves into the magnetosphere, where they couple to shear Alfvén waves. Sharply peaked field line resonance (FLR) structures are found to form at discrete locations within the magnetosphere in response to the fast mode driver. The extent in local time and relative amplitudes of FLR structures are found to depend strongly on the source location along the magnetopause boundary, indicating how the addition of day/night asymmetry affects the penetration of MHD fast waves within the magnetosphere. This also suggests that observed FLR structures within the magnetosphere may be used to deconvolve the spatial characteristics of the ULF wave source at the magnetopause, giving insight to the excitation mechanism responsible for observed ULF waves. As an example, we consider narrow band ULF activity observed on 25 November 2001 during a high solar wind speed interval following a geomagnetic storm and qualitatively reproduce the spatial and temporal characteristics of observations made by the Prince George SuperDARN radar by constraining the ULF wave source characteristics.
Influence of an inertia‐gravity wave on mesospheric dynamics: A case study with the Poker Flat Incoherent Scatter Radar
Authors: Nicolls M. J. , Varney R. H. , Vadas S. L. , Stamus P. A. , Heinselman C. J. , Cosgrove R. B. , Kelley M. C.
Published: October 2010

A case study of mesospheric winds and waves observed by the Poker Flat Incoherent Scatter Radar (PFISR) on 23 April 2008 is presented. Active auroral precipitation created sufficient ionization for nearly 12 h of continuous incoherent scatter measurements of the D region ionosphere from ∼60 to 90 km altitude. PFISR utilized a multilook‐direction mode which permitted measurements of vector winds, in addition to high precision vertical velocities, at high temporal resolution. A large‐amplitude coherent wave packet (appearing superficially to be a single wave) with a downward phase velocity and a long period (τ ∼ 10.5 h) was observed. Vertical wavelengths were measured directly to be λz ≃ 4–10 km, increasing with altitude. The proximity of τ to the local inertial period in addition to its large horizontal wavelength are suggestive of a coherent inertia‐gravity wave (IGW) packet. Using polarization analyses, we find that the IGWs are propagating mainly southward. The waves were observed to saturate at z ∼ 70–85 km, and have their largest amplitudes in the first 8 h of the measurements (before 2000 UT). A stability analysis confirms that the waves were likely dynamically unstable at these altitudes and times. In conjunction with this observation, the background wind is found to be southward of HWM winds by 10–20 m/s until ∼2000 UT, consistent with the horizontal background wind acceleration created by the saturation of these IGWs. After 2000 UT, the background wind relaxes to the north by 10–20 m/s, consistent with a significant decrease of the IGW amplitudes. The IGWs may have originated from a jet stream adjustment at z ∼ 10 km in northern Russia about 5 days prior to the observation in Alaska.
Physical atmospheric structure and tropospheric mixing information in vertical profiles of atmospheric CO2 mixing ratios
Authors: Font A. , Morguí J.‐A. , Rodó X.
Published: October 2010

Vertical distribution of atmospheric CO2 mixing ratios, as well as CO2 vertical variance and gradient are related to the vertical stability at the time of measurement, to the transport of coherent upstream plumes studied through changes in the upstream surface influence or to the historic mixing processes and dispersive behavior. Three vertical profiles of CO2 mixing ratios measured from 900 to 4200 m above sea level (masl) in 2006 at La Muela, Spain (LMU, 41.60°N 1.10°W, 570 masl) are examined. Changes in CO2 mixing ratio are associated with changes of the atmospheric physical parameters on the day of the survey; and with the transport of coherent air masses. Its consistency is examined through changes of the historical horizontal dispersion and chaotic mixing dynamics of air masses during the four days prior to measurements. A climatology of Lagrangian backward simulations run once a week at four altitudes (600, 1200, 2500 and 4000 masl) at LMU for 2006 shows that dispersion in these altitudes is superdiffusive (exponent coefficient γ > 1/2) and mixing follows a chaotic dynamics (power law exponent λ > 0) at all altitudes and in all seasons. Furthermore, a Horizontal Mixing Discontinuity (HMD) at ∼2500 masl separates two layers with different constraints on vertical mixing. Above the HMD, more coherent air masses and laminar transport characterizes the dynamics of atmospheric horizontal mixing whereas below it, filamentation and chaotic mixing dominate horizontal mixing. In the lower part of the vertical profile, within the ABL, mixing takes place by convection. Chaotic mixing below the HMD induces the boundary layer entrainment. Results highlight that there are two main discontinuities in the air column which separates different atmospheric dynamics. The ABL is driven by local meteorological conditions of the site at the sampling time; the HMD is driven by the synoptic‐scale historical mixing conditions of air masses. The effect of horizontal transport in the free troposphere should be considered equally as important as the local vertical mixing processes in the atmospheric boundary layer when interpreting CO2 vertical gradients. The dispersive exponents can be used to identify the transport of coherent plumes from anthropogenic emissions with different carbon composition that the one‐single backtrajectories models do not detect.
Comparative metagenomics of microbial communities inhabiting deep-sea hydrothermal vent chimneys with contrasting chemistries
Authors: Xie Wei , Wang Fengping , Guo Lei , Chen Zeling , Sievert Stefan M , Meng Jun , Huang Guangrui , Li Yuxin , Yan Qingyu , Wu Shan , Wang Xin , Chen Shangwu , He Guangyuan , Xiao Xiang , Xu Anlong
Published: October 2010

Deep-sea hydrothermal vent chimneys harbor a high diversity of largely unknown microorganisms. Although the phylogenetic diversity of these microorganisms has been described previously, the adaptation and metabolic potential of the microbial communities is only beginning to be revealed. A pyrosequencing approach was used to directly obtain sequences from a fosmid library constructed from a black smoker chimney 4143-1 in the Mothra hydrothermal vent field at the Juan de Fuca Ridge. A total of 308 034 reads with an average sequence length of 227 bp were generated. Comparative genomic analyses of metagenomes from a variety of environments by two-way clustering of samples and functional gene categories demonstrated that the 4143-1 metagenome clustered most closely with that from a carbonate chimney from Lost City. Both are highly enriched in genes for mismatch repair and homologous recombination, suggesting that the microbial communities have evolved extensive DNA repair systems to cope with the extreme conditions that have potential deleterious effects on the genomes. As previously reported for the Lost City microbiome, the metagenome of chimney 4143-1 exhibited a high proportion of transposases, implying that horizontal gene transfer may be a common occurrence in the deep-sea vent chimney biosphere. In addition, genes for chemotaxis and flagellar assembly were highly enriched in the chimney metagenomes, reflecting the adaptation of the organisms to the highly dynamic conditions present within the chimney walls. Reconstruction of the metabolic pathways revealed that the microbial community in the wall of chimney 4143-1 was mainly fueled by sulfur oxidation, putatively coupled to nitrate reduction to perform inorganic carbon fixation through the Calvin–Benson–Bassham cycle. On the basis of the genomic organization of the key genes of the carbon fixation and sulfur oxidation pathways contained in the large genomic fragments, both obligate and facultative autotrophs appear to be present and contribute to biomass production.
Lifestyle and Socioeconomic‐Status Modify the Effects of ADRB2 and NOS3 on Adiposity in European‐American and African‐American Adolescents
Authors: Lagou Vasiliki , Liu Gaifen , Zhu Haidong , Stallmann‐Jorgensen Inger S. , Gutin Bernard , Dong Yanbin , Snieder Harold
Published: October 2010

The aim of the study is to investigate the influence of and interaction between lifestyle behaviors (diet and physical activity (PA)) and single‐nucleotide polymorphisms (SNPs) in obesity‐candidate genes (ADRB2, APOB and NOS3) on general and central adiposity. Six‐hundred‐and‐twenty‐one European‐American (EA) and African‐American (AA) youths aged 13–19 years were classified by ethnicity (49% AA), gender (45% male), and socioeconomic status (SES). PA and dietary intake with up to seven 24‐h recalls were reported for all subjects. Percent body fat (%BF) was measured by dual‐energy X‐ray absorptiometry, visceral adipose tissue (VAT), and subcutaneous abdominal adipose tissue (SAAT) by magnetic resonance imaging. Reported energy intake (EI) and vigorous PA (VPA) were negative predictors of %BF and SAAT. Carriers of the NOS3 Asp298 allele had higher %BF only in the presence of an adverse environment (low SES). Compared to the most common NOS3 haplotype, homozygotes for haplotype A‐non4r‐Asp had 6.1% higher %BF. Significant interactions were revealed between the ADRB2 Arg16Gly SNP and VPA on VAT, SAAT and waist circumference (WC) such that Gly16 homozygotes may benefit less from increased VPA to reduce their weight. Genetic susceptibility to increased general and central adiposity is dependent on several factors, such as SES and vigorous exercise. Improved understanding of the joint effect of genes and lifestyle on adiposity will offer new insights into obesity and may provide new avenues for personalized prevention and treatment.
The immunoproteasome, the 20S proteasome and the PA28αβ proteasome regulator are oxidative-stress-adaptive proteolytic complexes
Authors: Pickering Andrew M. , Koop Alison L. , Teoh Cheryl Y. , Ermak Gennady , Grune Tilman , Davies Kelvin J. A.
Published: October 2010

Oxidized cytoplasmic and nuclear proteins are normally degraded by the proteasome, but accumulate with age and disease. We demonstrate the importance of various forms of the proteasome during transient (reversible) adaptation (hormesis), to oxidative stress in murine embryonic fibroblasts. Adaptation was achieved by ‘pre-treatment’ with very low concentrations of H2O2, and tested by measuring inducible resistance to a subsequent much higher ‘challenge’ dose of H2O2. Following an initial direct physical activation of pre-existing proteasomes, the 20S proteasome, immunoproteasome and PA28αβ regulator all exhibited substantially increased de novo synthesis during adaptation over 24 h. Cellular capacity to degrade oxidatively damaged proteins increased with 20S proteasome, immunoproteasome and PA28αβ synthesis, and was mostly blocked by the 20S proteasome, immunoproteasome and PA28 siRNA (short interfering RNA) knockdown treatments. Additionally, PA28αβ-knockout mutants achieved only half of the H2O2-induced adaptive increase in proteolytic capacity of wild-type controls. Direct comparison of purified 20S proteasome and immunoproteasome demonstrated that the immunoproteasome can selectively degrade oxidized proteins. Cell proliferation and DNA replication both decreased, and oxidized proteins accumulated, during high H2O2 challenge, but prior H2O2 adaptation was protective. Importantly, siRNA knockdown of the 20S proteasome, immunoproteasome or PA28αβ regulator blocked 50–100% of these adaptive increases in cell division and DNA replication, and immunoproteasome knockdown largely abolished protection against protein oxidation.
Print-Focused Read-Alouds in Preschool Classrooms: Intervention Effectiveness and Moderators of Child Outcomes
Authors: Justice Laura M. , McGinty Anita S. , Piasta Shayne B. , Kaderavek Joan N. , Fan Xitao
Published: October 2010

Purpose

This study was conducted to determine the effectiveness of teachers' use of a print-referencing style during whole-class read-alouds with respect to accelerating 4- and 5-year-old children’s print-knowledge development. It also examined 8 specific child- and setting-level moderators to determine whether these influenced the relation between teachers' use of a print-referencing style and children’s print-knowledge development.

Method

In this randomized controlled trial, 59 teachers were randomly assigned to 2 conditions. Teachers in the experimental group (
n
= 31) integrated explicit references to specified print targets within each of 120 read-aloud sessions conducted in their classrooms over a 30-week period; comparison teachers (
n
= 28) read the same set of book titles along the same schedule but read using their business-as-usual reading style. Children’s gains over the 30-week period on a composite measure of print knowledge were compared for a subset of children who were randomly selected from the experimental (
n
= 201) and comparison (
n
= 178) classrooms.

Results

When controlling for fall print knowledge, child age, and classroom quality, children who experienced a print-referencing style of reading had significantly higher print knowledge scores in the spring than did children in the comparison classroom. None of the child-level (age, initial literacy skills, language ability) or setting-level characteristics (program type, instructional quality, average level of classroom socioeconomic status, teachers' education level, teachers' experience) significantly moderated intervention effects.

Clinical Implications

Considered in tandem with prior study findings concerning this approach to emergent literacy intervention, print-focused read-alouds appear to constitute an evidence-based practice with net positive impacts on children’s literacy development.
DAILY FLUCTUATIONS OF EXOPOLYMERS IN CULTURES OF THE BENTHIC DIATOMS CYLINDROTHECA CLOSTERIUM AND NITZSCHIA SP. (BACILLARIOPHYCEAE)1
Authors: De Brouwer Jody F.C. , Stal Lucas J.
Published: October 2010

Dynamics in the production of extracellular polymeric substances (EPS) were investigated for the benthic diatoms Cylindrotheca closterium (Ehrenberg) and Nitzschia sp. The effect of growth phase and light:dark conditions were examined using axenic cultures. Two EPS fractions were distinguished. Soluble EPS was recovered from the culture supernatant and represented polysaccharides that were only loosely associated with the cells. Bound EPS was extracted from the cells using warm (30° C) water and was more closely associated with the diatom aggregates. Concentrations of EPS exceeded internal concentrations of sugar throughout growth, indicating that EPS production is important in these organisms. Soluble and bound EPS revealed distinct differences in daily dynamics during the course of growth. Soluble EPS was produced continuously once cultures entered the stationary phase. During the stationary phase, chl a‐normalized EPS production rates equaled 6.4 and 3.4 d−1 for C. closterium and Nitzschia sp., respectively. In contrast, production of bound EPS occurred only in the light and was highest during the exponential phase. Up to 90% of the attached EPS that was produced in the light was degraded during the subsequent dark period. The monosaccharide distribution of EPS was constant during the course of the experiment. The soluble EPS consisted of high amounts of galactose and glucuronic acid, relative to rhamnose, glucose, xylose/mannose, and galacturonic acid. In contrast, glucose was the dominant monosaccharide present in the bound EPS. These differences suggest that the production of the two distinct EPS fractions is under different metabolic controls and probably serves different cellular functions.
QUANTIFICATION OF THE RELATIVE ABUNDANCE OF THE TOXIC DINOFLAGELLATE,KARENIA BREVIS(DINOPHYTA), USING UNIQUE PHOTOPIGMENTS1
Authors: Örnólfsdóttir Erla Björk , Pinckney James L. , Tester Patricia A.
Published: October 2010

Diagnostic photopigment analysis is a useful tool for determining the presence and relative abundance of algal groups in natural phytoplankton assemblages. This approach is especially useful when a genus has a unique photopigment composition. The toxic dinoflagellateKarenia brevis(Davis) G. Hansen & Moestrup comb. nov. shares the diagnostic pigment gyroxanthin‐diester with only a few other dinoflagellates and lacks peridinin, one of the major diagnostic pigments of most dinoflagellate species. In this study, measurements of gyroxanthin‐diester and other diagnostic pigments ofK. breviswere incorporated into the initial pigment ratio matrix of the chemical taxonomy program (CHEMTAX) to resolve the relative contribution ofK. brevisbiomass in mixed estuarine phytoplankton assemblages from Florida and Galveston Bay, Texas. The phytoplankton community composition of the bloom in Galveston Bay was calculated based on cell enumerations and biovolumetric measurements in addition to chla‐specific photopigment estimates of biomass (HPLC and CHEMTAX). The CHEMTAX and biovolume estimates of the phytoplankton community structure were not significantly different and suggest that the HPLC–CHEMTAX approach provides reasonable estimates ofK. brevisbiomass in natural assemblages. The gyroxanthin‐diester content per cell ofK. brevisfrom Galveston Bay was significantly higher than inK. breviscollected from the west coast of Florida. This pigment‐based approach provides a useful tool for resolving spatiotemporal distributions of phytoplankton in the presence ofK. brevisblooms, when an appropriate initial ratio matrix is applied.
REVERSAL OF HELIX ORIENTATION IN THE CYANOBACTERIUM ARTHROSPIRA1
Authors: Mühling Martin , Harris Nicholas , Belay Amha , Whitton Brian A.
Published: October 2010

A survey of the morphological characters of 36 clonal axenic strains of Arthrospira showed that 34 had helical and 2 had straight trichomes. Of those with helical trichomes, five were right‐handed and 29 left‐handed. After repeated subculture for 1 year, the orientation of one helical strain (D893) had changed from right‐ to left‐handed, suggesting a probable genetic shift. The influence of environmental factors on helix orientation was tested on a subset of 10 strains. A temperature upshift from 30 to 32–34° C for 7 days led to a change in orientation in three strains (D918/H, D923, D925). Incubation at 32° C (D918/H, D923) or 34° C (D925) for periods less than needed for the morphological change to show still permitted the change to take place subsequently, when the temperature was reduced to 30° C; however, further subculture at 30° C led to the orientation reverting to its original state. In strain D925, but not the other nine strains, continuous shaking at 30° C also led to a change in helix orientation. In this case, some trichomes showed both orientations in a single trichome, with a snag at the point of reversion. A repeat survey of the stock cultures of all 34 strains after 2 years showed that another strain (D918/H) had now changed orientation from right‐handed to left‐handed. These observations are compared with the behavior of other helical structures in the literature, including filamentous Bacillus subtilis mutants and helix reversal in tendrils of climbing plants.
REEVALUATION OF THE NITROGEN FIXATION BEHAVIOR IN THE MARINE NON‐HETEROCYSTOUS CYANOBACTERIUM LYNGBYA MAJUSCULA1
Authors: Lundgren Pernilla , Bauer Karolina , Lugomela Charles , Söderbäck Erik , Bergman Birgitta
Published: October 2010

Lyngbya majuscula Harvey ex Gomont is a common marine cyanobacterium in tropical and subtropical near‐shore waters. A few reports have indicated that L. majuscula fixes nitrogen only in the light. Because this feature is uncommon among non‐heterocystous cyanobacteria, we attempted a reevaluation. Nitrogenase activity, regulation, and localization were examined over diel cycles on natural populations of L. majuscula growing in subtidal zones off Zanzibar in the western Indian Ocean. The data show that L. majuscula fixed nitrogen and synthesized nitrogenase in all cells during the dark phase of a diel cycle. During the light phase, nitrogenase was degraded to undetectable levels.
MULTIPLE CRYPTIC SPECIES: MOLECULAR DIVERSITY AND REPRODUCTIVE ISOLATION IN THE BOSTRYCHIA RADICANS/B. MORITZIANA COMPLEX (RHODOMELACEAE, RHODOPHYTA) WITH FOCUS ON NORTH AMERICAN ISOLATES
Authors: Zuccarello Giuseppe C. , West John A.
Published: October 2010

Red algae of the Bostrychia radicans/B. moritziana complex are common in warm temperate areas of North America. Phylogenetic analysis of both plastid and mitochondrial DNA sequence data revealed seven distinct evolutionary lineages among worldwide samples. Although only two haplotypes (plastid and mitochondrial) were found in Pacific Mexico, four plastid and 11 mitochondrial haplotypes were found in a similar latitudinal spread along the Atlantic coast of the United States. On the U.S. Atlantic coast only one plastid haplotype was found in northern samples (Connecticut to North Carolina), whereas further south several plastid haplotypes were found. Phylogenetic analyses suggested that this single plastid haplotype found among northern samples could be the result of a northward range expansion possibly since the last glacial maximum. Crossing data of samples within the same evolutionary lineage showed that samples with the same plastid haplotypes were generally sexually compatible; samples with different plastid haplotypes were reproductively isolated. Samples from Pacific Mexico were partially reproductively compatible with some samples from the Atlantic USA (plastid haplotype C) and were more closely related to these samples than these U.S. samples were to other U.S. Atlantic samples. Compatible solute types mirrored the plastid haplotype, with plastid haplotype B having only sorbitol, whereas all other haplotypes also contained dulcitol. Samples from Atlantic USA, with different plastid haplotypes (e.g. B vs. C), but within the same evolutionary lineage, were reproductively isolated from each other. Data indicate that reproductive isolation occurs between and within supported evolutionary lineages and that the number of cryptic species is high.
Mycosporines: Detection Methodologies and Assessment
Authors: Zimba P. V. , Wulff A.
Published: October 2010

Mycosporine‐like amino acids (MAAs) are found in a variety of prokaryotic and eucaryotic algae, as well as higher plants, fungi, and animals. These compounds function as a photoprotective sunscreen to prevent ultra‐violet light damage. MAAs may thus be one of the competitive advantages that facilitated development of ozone (by oxytrophs), and thereby may be a competitive advantage for the proliferation of cyanobacteria and other harmful algal species. Numerous difficulties exist with assessment of MAAs, including identification of the compounds, conversion of isomers during HPLC preparation as a result of pH shifts, as well as the ecological implications of the presence, concentration, and forms of these compounds (see J Phycology 1999; 35, for relevant papers). This symposium will provide opportunities for intercalibration of laboratories involved in MAA analyses, suggestions regarding standardization of extraction protocols, as well as results from field‐ and laboratory‐based studies.
The Ecological Significance of Mycosporine‐Like Amino Acids in Algae
Authors: Franklin L. A.
Published: October 2010

The links among mycosporine‐like amino acids (MAAs), algal physiological ecology, and the environment may be viewed from two sides. The UV‐absorption spectra of MAAs make them prime candidates for UV‐screening compounds, and indeed, numerous studies have shown that a high concentration of MAAs is correlated with various degrees of protection of cellular processes from UV damage. Thus, it might be said that the structure of terrestrial, eulittoral and sublittoral algal communities depends in part on their ability to synthesize effective quantities of MAAs. Corollaries to this hypothesis might include the proposition that those species incapable of synthesizing MAAs will be excluded from UV‐containing environments, and that UV is necessary to trigger MAA synthesis. However, a number of studies have demonstrated that triggers of MAA synthesis need not include exposure to UV, but may include the relative availability of nitrogen, osmotic stress, or high levels of photosynthetically active radiation. Furthermore, the response to these factors may vary as a function of other environmental conditions. These issues will be discussed with respect to elucidating the master switch for MAA synthesis.
18S‐Based Taxonomy and Intraspecific Its Sequence Variation in the Marine Fungal Endosymbiont Haloguignardia Irritans Infecting Cystoseira Osmundacea Along the Californian Coast
Authors: Harvey J. B. J.
Published: October 2010

Abstract withdrawn
Branching Morphology of Gametophytes and Tetrasporophytes of Ceramium Codicola is Related to Phase and Reproductive Structures
Authors: Lewis R. J. , Lanker M. D.
Published: October 2010

Most red algae with a Polysiphonia‐type life history are regarded as having isomorphic phases. However, some show minor deviations in morphology, including differences in branching reported in female gametophytes and tetrasporophytes of Ceramium. By sampling populations of Ceramium codicola, an epiphyte of Codium fragile, it was possible to characterize the morphology of female and male gametophytes and tetrasporophytes. Branching pattern was characterized by the Strahler method, in which terminal branches are counted as primary branches, and higher order branches are counted where lower order branches meet. Since Ceramium shows dichotomous branching, this method can be used to characterize the degree in which branching is dichotomous. The angle of branching was also measured. Female gametophytes had a higher ratio of primary to secondary branches (3.6–5.1) than male gametophytes (2.5) and tetrasporophytes (2.5–2.6), which have a similar ratio to each other. This indicates that males and tetrasporophytes have a more dichotomous pattern of branching while female gametophytes have more proliferative primary branches. The differences in branching pattern appear to be related to the location of reproductive cells, which occur along the surface of branches in male gametophytes and tetrasporophytes, but occur near the apices in female gametophytes. The branching angle of female and male gametophytes is similar to each other, and greater than that of tetrasporophytes. Therefore, gametophytes and sporophytes differ in branching angle.
Phragmoplastins, the Trentepohliales, and the Evolution of the Cytokinesis in Green Plants
Authors: Lopez‐Bautista J. M. , Chapman R. L.
Published: October 2010

Green plants have been shown to have a common ancestor and to contain two lineages: the Chlorophytes and the Streptophytes, both encompassing representatives of the original ‘green algae’. The phragmoplast‐mediated cell division characterizes the land plants in the Streptophyte lineage and some basal green algal orders (Coleochaetales, Charales and Zygnematales). However, a well‐developed phragmoplast‐type cell division has been documented in two subaerial green algae (Cephaleuros parasiticus and Trentepohlia odorata) belonging to the order Trentepohliales, an order that molecular sequence data place unequivocally within the Chlorophytes (rather than Streptophytes). Is the phragmoplast‐mediated cell division of the Trentepohliales a case for homology or nonhomology? In order to reveal the answer to this question, we are exploring the potential phylogenetic information inferred from gene sequences of phragmoplastin, a dynamin‐like protein which has been demonstrated to be associated with cell plate formation during the phragmoplast‐mediated cytokinesis in land plants. Primers were designed based on an available phragmoplastin sequence from soybean, and yielded PCR amplifications from the green algae (Trentepohlia and Cephaleuros), a bryophyte (Bazzania) and land plants (Glycine and Arabidopsis). The evolutionary history of the development of the phragmoplast may remain in the analysis of the gene sequences for this group of proteins.
Towards a stakeholder society: Stakeholder theory vs theory of civil society
Authors: Bonnafous‐Boucher Maria , Porcher Simon
Published: October 2010

Associating the concept of civil society with stakeholder theory has become a common practice. The point of view put forward here attribute paternity of the stakeholder theory essentially to Freeman as a strategic framework for business studies and practices (1981, 1983, 1984, 1985, 1987, 2001, 2004), as a strong framework for political and moral philosophy (1988, 1994, 1998), as an inescapable framework for business ethics (2000). In order to take into account the advancement bringing by Freeman, the intention of this article is to demonstrate the degree to which stakeholder theory can be considered as a theory of civil society, which in turn is a theory of business. The argument will be based on the following points:

Stakeholder theory occupies an intermediate position between strategic management and political philosophy in that it presents a new form of sovereignty, the sovereignty of big business;

Stakeholder theory is a strategic theory; whether it legitimises, relativises or neutralises the sovereignty of the firm, it conceptualises and situates it in relation to other models;

Stakeholder theory can be understood as a theory of civil society for the 21st century but it cannot be a substitute for a civil society theory devised in the 19th century;

Stakeholder theory can thus be considered as affording a strategic perspective that, although somewhat unfamiliar, serves as the foundation of business ethics.
Modeling of neutron induced backgrounds in x-ray framing cameras
Authors: Hagmann C. , Izumi N. , Bell P. , Bradley D. , Conder A. , Eckart M. , Khater H. , Koch J. , Moody J. , Stone G.
Published: October 2010

Fast neutrons from inertial confinement fusion implosions pose a severe background to conventional multichannel plate (MCP)-based x-ray framing cameras for deuterium-tritium yields >1013. Nuclear reactions of neutrons in photosensitive elements (charge coupled device or film) cause some of the image noise. In addition, inelastic neutron collisions in the detector and nearby components create a large gamma pulse. The background from the resulting secondary charged particles is twofold: (1) production of light through the Cherenkov effect in optical components and by excitation of the MCP phosphor and (2) direct excitation of the photosensitive elements. We give theoretical estimates of the various contributions to the overall noise and present mitigation strategies for operating in high yield environments.
New plasma measurements with a multichannel millimeter-wave fluctuation diagnostic system in the DIII-D tokamak (invited)
Authors: Hillesheim J. C. , Peebles W. A. , Rhodes T. L. , Schmitz L. , White A. E. , Carter T. A.
Published: October 2010

A novel multichannel, tunable Doppler backscattering (DBS)/reflectometry system has recently been developed and applied to a variety of DIII-D plasmas. Either DBS or reflectometry can be easily configured for use in a wide range of plasma conditions using a flexible quasi-optical antenna system. The multiple closely spaced channels, when combined with other fluctuation diagnostic systems, have opened up new measurements of plasma properties. For example, the toroidal and fine-scale radial structure of coherent plasma oscillations, such as geodesic acoustic modes, have been probed simultaneously in the core of high temperature plasmas by applying correlation analysis between two toroidally separated DBS systems, as well as within the multichannel array. When configured as a reflectometer, cross-correlation with electron cyclotron emission radiometry has uncovered detailed information regarding the crossphase relationship between density and temperature fluctuations. The density-temperature crossphase measurement yields insight into the physics of tokamak turbulence at a fundamental level that can be directly compared with predictions from nonlinear gyrokinetic simulations.
A resonance Raman spectroscopic and CASSCF investigation of the Franck–Condon region structural dynamics and conical intersections of thiophene
Authors: Wu Xian-Fang , Zheng Xuming , Wang Hui-Gang , Zhao Yan-Yin , Guan Xiangguo , Phillips David Lee , Chen Xuebo , Fang Weihai
Published: October 2010

Resonance Raman spectra were acquired for thiophene in cyclohexane solution with 239.5 and 266 nm excitation wavelengths that were in resonance with ∼240 nm first intense absorption band. The spectra indicate that the Franck–Condon region photodissociation dynamics have multidimensional character with motion mostly along the reaction coordinates of six totally symmetry modes and three nontotally symmetry modes. The appearance of the nontotally symmetry modes, the CS antisymmetry stretch +CCC bend mode ν21(B2) at 754 cm−1 and the H7C3C4H8 twist ν9(A2) at 906 cm−1, suggests the existence of two different types of vibronic-couplings or curve-crossings among the excited states in the Franck–Condon region. The electronic transition energies, the excited state structures, and the conical intersection points B11/A11 and B12/A11 between 2 A11 and 1 B12 or 1 B11 potential energy surfaces of thiophene were determined by using complete active space self-consistent field theory computations. These computational results were correlated with the Franck–Condon region structural dynamics of thiophene. The ring opening photodissociation reaction pathway through cleavage of one of the CS bonds and via the conical intersection point B11/A11 was revealed to be the predominant ultrafast reaction channel for thiophene in the lowest singlet excited state potential energy hypersurface, while the internal conversion pathway via the conical intersection point B12/A11 was found to be the minor decay channel in the lowest singlet excited state potential energy hypersurface.
A continuum framework for grain boundary diffusion in thin film/substrate systems
Authors: Ayas Can , van der Giessen Erik
Published: October 2010

A two-dimensional continuum model is developed for stress relaxation in thin films through grain boundary (GB) diffusion. When a thin film with columnar grains is subjected to thermal stress, stress gradients along the GBs are relaxed by diffusion of material from the film surface into the GBs. The transported material constitutes a wedge and becomes the source of stress inside the adjacent elastic grains that are perfectly bonded to the substrate. In the model, the coupling between diffusion and elasticity is obtained by numerically solving the governing equations in a staggered manner. A finite difference scheme is used to solve the diffusion equations, modified in order to implement realistic boundary conditions, while the elasticity problem is solved with the finite element method. The solutions reveal the existence of a universal power law scaling between the unrelaxed fraction of stress and the grain aspect ratio. For slender grains, the GB wedge attains a more uniform shape and relaxation is more effective. The kinetics of the process depends not only on the grain aspect ratio but also strongly on the thickness of the film. In case there is no adhesion between film and substrate, complete stress relaxation is attained albeit at a slightly slower rate.
Three dimensional measurements of engine plumes with four-channel single spectral tomography
Authors: Wan Xiong , Zhang Zhimin , Leng Biyan , Deng Xiaoming
Published: October 2010

The design and improvement of an aeroengine rely on the analysis of the combustion process in the combustion chamber to a certain extent. It is difficult to investigate the combustion inside the chamber directly due to its obturation and invisibility, however, the physical distribution of exhaust plumes outside the chamber can be measured by various means and provide the information to deduce the combustion condition inside the chamber. Most traditional measurementations such as thermography can only measure the plane temperature distribution of the plumes, hence its applications are restrained. In this paper, a three dimensional (3D) measurement approach is proposed, which is based on a multichannel single spectral tomography (SST) and the radiation theory of blackbody. Furthermore, an SST real-time testing system was built to measure the 3D temperature distribution of the plumes of a pulse detonation engine. To improve the precision of the testing system, an emission projection matrix was proposed and the relationship between the radiant intensity of blackbody and the gray scale of the photoelectronic sensor was also deduced. Theoretical analysis and experimental results prove the feasibility of the proposed SST approach that can be promoted to apply to the 3D measurement of plumes of other aeroengines.
Strong ferroelectric domain-wall pinning in BiFeO3 ceramics
Authors: Rojac Tadej , Kosec Marija , Budic Bojan , Setter Nava , Damjanovic Dragan
Published: October 2010

We have studied the polarization-electric-field hysteresis, the dielectric permittivity dispersion, the piezoelectric properties, the electric-field-induced strain, and the interrelations between these properties for bismuth ferrite (BiFeO3) ceramics. The results indicate that the domain-wall movement in BiFeO3 is strongly inhibited by charged defects, most probably acceptor-oxygen-vacancy defect pairs. The domain-wall mobility can be considerably increased by preventing the defects from migrating into their stable configuration; this can be achieved by thermal quenching from above the Curie temperature, which freezes the disordered defect state. Similarly, Bi2O3 loss during annealing at high temperatures contributes to depinning of the domain walls and an increase in the remanent polarization. The possible defects causing the pinning effect are analyzed and discussed. A weakening of the contacts between the grains in the ceramics and crack propagation were observed during poling with constant field at 100 kV/cm. This is probably caused by an electrically induced strain associated with ferroelastic domain reversal. A relatively large piezoelectric d33 constant of 44 pC/N was obtained by “cyclic poling,” in which the electric field was released after each applied cycle with the purpose to relax the mechanical stresses and minimize the problem of cracking.
The role of the geometry in multiwall carbon nanotube interconnects
Authors: Bellucci S. , Onorato P.
Published: October 2010

We develop an approach to calculate the electron spectrum of metallic multiwall carbon nanotubes (MWNT) with an arbitrary number of coaxial layers. The approach is based on the model with singular attractive potential of equidistant conductive cylinders and includes the presence of a geometrical potential. The knowledge of the one-electron spectrum allows us to calculate the number of electrically active channels, Nch, in MWNT in the ideal case where all the shells are contacted to the electrodes. Starting from the dependence of Nch on the temperature and on the radii of both the innermost and outermost tube we will be able to discuss the potential performances of MWNT interconnects. With the aim of designing carbon based nanointerconnects, we demonstrate that, for small innermost radius MWNT, the presence of the geometrical potential can be quite relevant, when all the shells are contacted to the electrodes, while the intershell tunneling can be quite relevant in determining Nch, when the radius of the outermost shell becomes of the order of hundreds of nanometers.
Reversible room temperature ferromagnetism in undoped zinc oxide: Correlation between defects and physical properties
Authors: Mal Siddhartha , Nori Sudhakar , Jin Chunming , Narayan J. , Nellutla S. , Smirnov A. I. , Prater J. T.
Published: October 2010

We report a systematic study of the structural, chemical, electrical, optical, and magnetic properties of undoped ZnO thin films grown under different conditions as well as the films that were annealed in various environments. Oxygen-annealed films displayed a sequential transition from ferromagnetism to diamagnetism as a function of the annealing temperature. An increase in the green band intensity has been observed in oxygen-annealed ZnO films. Reversible switching of room-temperature ferromagnetism and n-type conductivity have been demonstrated by oxygen and vacuum annealing. Electron paramagnetic resonance data were found to be in agreement with the results of magnetization and conductivity measurements. Possibility of external ferromagnetic impurity as the origin of the unconventional room temperature ferromagnetism in these films has been ruled out by secondary ion mass spectrometer and electron energy loss spectroscopy studies. Correlation between structural, electrical, optical, and magnetic properties has been established in terms of defects and defect complexes. Taken together, our data indicate that the ferromagnetic order in ZnO matrix might be defect-mediated.
Photoluminescence from nanocrystalline graphite monofluoride
Authors: Wang Bei , Sparks Justin R. , Gutierrez Humberto R. , Okino Fujio , Hao Qingzhen , Tang Youjian , Crespi Vincent H. , Sofo Jorge O. , Zhu Jun
Published: October 2010

We synthesize and study the structural and optical properties of nanocrystalline graphene monofluoride and graphite monofluoride, which are carbon-based wide band gap materials. Using laser excitations 2.41–5.08 eV, we identify six emission modes of graphite monofluoride, spanning the visible spectrum from red to violet. The energy and linewidth of the modes point to defect-induced midgap states as the source of the photoemission. We discuss possible candidates. Our findings open the window to electro-optical applications of graphene fluoride.
Reduction of surface leakage current in InAs/GaSb strained layer long wavelength superlattice detectors using SU-8 passivation
Authors: Kim H. S. , Plis E. , Gautam N. , Myers S. , Sharma Y. , Dawson L. R. , Krishna S.
Published: October 2010

We report on SU-8 passivation for reducing surface leakage current in type-II InAs/GaSb strained layer superlattice detectors (λ100% cut-off∼12 μm). The electrical behavior of SU-8 passivated and unpassivated devices was compared for devices with variable mesa sizes. Dark current was reduced by more than one order of magnitude for the small area (50 μm×50 μm) passivated diode at 77 K. The surface resistivity, the responsivity and specific detectivity were measured for SU-8 passivated devices and are equal to 204 Ω cm, 0.58 A/W and 3.49×109 Jones, respectively (77 K).
Charge transport in columnar mesophases of carbazole macrocycles
Authors: Vehoff Thorsten , Baumeier Björn , Andrienko Denis
Published: October 2010

Charge transport properties of a columnar mesophase of carbazole macrocycles are analyzed. Realistic morphologies are sampled using all-atom molecular dynamics simulations while charge transport is simulated using the kinetic Monte Carlo method with transfer rates obtained from the high temperature nonadiabatic limit of Marcus theory. It is shown that the molecular design with side chains pointing inside the macrocycle allows close approach between molecules of neighboring columns, thus enabling three-dimensional transport and helping to circumvent charge trapping on structural defects.
Introduction: perspectives on Garibaldi and Italian unity
Authors: Seymour Mark
Published: October 2010

One hundred and fifty years ago, in October 1860, the legendary dawn meeting at Teano between Giuseppe Garibaldi and Victor Emmanuel of Piedmont marked a momentary confluence of competing visions of Italian unification. Although the moment represented an ideological about-face for Garibaldi, his status as the most luminous hero of Italian unification continued to rise like a serene spirit, seemingly untainted by the contested realities of the nation he had helped to create. Of course, that generalisation ignores a thousand exceptions, and already from the 1950s and 1960s, authors such as Denis Mack Smith and Christopher Hibbert had underlined that Garibaldi's life and historic role were not without conflict or enmity (Mack Smith 1957; Hibbert 1965). But it remains true that, all told, Garibaldi's legacy and personal reputation have been characterised, until very recently, by an almost uncanny pact of agreement not to disagree – at least in public.
Opportunists and Opportunities: The 2010 SHEA Lecture
Authors: Henderson David K.
Published: October 2010

My experience as a hospital epidemiologist at the National Institutes of Health Clinical Center has underscored the importance of aggressively managing infection with opportunistic pathogens and of taking advantage of opportunities as they arise (most often as crises). I review selected aspects of my career and use these as examples of the opportunists and opportunities now facing healthcare epidemiology.
The Antibiotic Development Pipeline for Multidrug-Resistant Gram-Negative Bacilli: Current and Future Landscapes
Authors: Talbot George H.
Published: October 2010

Development of antibiotics to treat infections caused by multidrug-resistant gram-negative bacilli has lagged significantly behind development of antibiotics to treat infections with gram-positive pathogens. Although a few promising drugs have entered early clinical development, more must be done to preserve the utility of currently available antibiotics and to ensure a pipeline of efficacious, safe antibacterials.
The Past, Present, and Future of Healthcare-Associated Infection Prevention in Pediatrics: Catheter-Associated Bloodstream Infections
Authors: Bryant Kristina A. , Zerr Danielle M. , Huskins W. Charles , Milstone Aaron M.
Published: October 2010

Central line–associated bloodstream infections cause morbidity and mortality in children. We explore the evidence for prevention of central line–associated bloodstream infections in children, assess current practices, and propose research topics to improve prevention strategies.
Detection of Clostridium difficile Infection
Authors: Bartlett John G.
Published: October 2010

There has been a recent surge of interest in Clostridium difficile infection, which reflects an impressive increase in the number and severity of these infections. This review addresses some of the newer methods for detection of C. difficile infection at the bedside and in the laboratory. Particularly important are the new rapid diagnostic tests that detect toxigenic C. difficile using polymerase chain reaction and the combination tests that, either simultaneously or sequentially, screen for C. difficile and test for toxins A and B. It is expected that these new testing methods will largely supplant the enzyme immunoassays for toxins, which are used by most laboratories, departments, and divisions. The present goal is to combine clinical, laboratory, and animal research related to C. difficile that reflects issues that are considered to be major contemporary challenges. Among this work is the pursuit of studies of immune mechanisms to better control this disease.