bluuebunny/crossref_metadata_2025 huggingface dataset:
31P‐NMR STUDIES ON INORGANIC POLYPHOSPHATES IN MICROALGAE1
Authors: Ok‐hama Tamiko , Siebelt Friederike , Furihata Kazuo , Seto Haruo , Miyachi Shigetoh , Ohmori Masayuki
Published: March 2008

Using “P nuclear magnetic resonance analysis, total inorganic polyphosphate in algae could be quantitatively estimated, For this purpose the algal suspension, which had been kept in cold trichloroacetic acid, was further treated with 6 mM EDTA, or the cells were kept in 2 N KOH containing 100 mM EDTA for 18 h at 37°C. These simple methods avoid hydrolysis of cellular inorganic polyphosphate and, therefore, are useful for the study of phosphorus metabolism in algae. The effects of these treatments on visualization of the signal for inorganic polyphosphate in nuclear magnetic resonance spectra were discussed in comparison with in vivo, ‘P nuclear magnetic resonance spectra of algae.
REJUVENATION OF MELOSIRA GRANULATA (BACILLARIOPHYCEAE) RESTING CELLS FROM THE ANOXIC SEDIMENTS OF DOUGLAS LAKE, MICHIGAN. I. LIGHT MIGROSCOPY AND 14C UPTAKE 1
Authors: Sicko‐Goad L. , Stoermer E. F. , Fahnenstiel G.
Published: March 2008

Resting cells of Melosira granulate (Ehr.) Ralfs were collected from the anoxic sediments of Douglas Lake, Michigan. Sediment containing M. granulata was inoculated into distilled water and incubated in a growth chamber for one week during which observations were made on the cytological differentiation process. Cells classified as “condensed,” i.e. containing a dark brown cytoplasmic mass were identified as resting cells. The differentiation process consisted of a series of gradual cytological changes that included elongation of the cytoplasmic mass and recognition of definable organelles to the point where the cells were non‐distinguishable from water column vegetative cells. Differentiating cells accumulated large polyphosphate and lipid granules. However, these granules disappeared just prior to cell division. The complete differentiation or rejuvenation sequence occurred in some cells in less than 24 h. However, not all dormant cells rejuvenated at the same time and it was observed that the lag period for rejuvenation increased with resting cell age (depth of burial in sediments). In the 14C uptake studies, label was initially observed in condensed state cells. The label gradually progressed to the more differentiated forms. Total carbon uptake during the rejuvenation process was initially lower in the rejuvenating cells, but roughly equal to water column populations after 8 h, indicating a period of high metabolic activity in the rejuvenating cells between 1 and 8 h.
GROWTH RATES AND ULTRASTRUCTURE OF SILICEOUS SETAE OF CHAETOCEROS GRACILIS (BACILLARIOPHYCEAE) 12
Authors: Rogerson A. , DeFreitas A. S. W. , McInnes A. G.
Published: March 2008

The growth of setae in post‐division Chaeloceros gracilis Schütt was triphasic. Following cell separation there was an initial lag phase of about 30 min after which setae grew linearly at rates ranging from 0.20 to 0.38 μm‐min−1. The growth rate was independent of whether diatoms cultured in medium containing 200 μM Si were transferred for experimentation to media containing 10 or 200 μM Si. When developing setae had attained a length of approximately 2 μm, their growth rate slowed as they entered a clearly defined plateau phase. The amount of silicon per unit length of setae was found to be 0.02 pg Si μm−1, and the deposition rate was estimated as 0.005 Pg Si min−1. Transmission electron microscopy revealed an axial structure resembling a microlubule extending the length of each seta and membrane bound polyphosphate bodies postulated to be the energy source for growth and associated biomineralization processes.
A DESCRIPTIVE AND ULTRASTRUCTURAL STUDY OF THE GREEN ALGA, CHLAMYDOMONAS DESMIDII SP. NOV. (VOLVOCALES. CHLAMYDOMONADACEAE) FROM ROCKY MOUNTAIN NATIONAL PARK LAKES 1
Authors: Kugrens Paul , Delivopoulos Stylianos G.
Published: March 2008

The green algal flagellate Chlamydomonas desmidii sp. nov., is described from several lakes in Rocky Mountain National Park, Colorado. The biflagellate cells generally have an hour‐glass shape. They possess a single chloroplast with two pyrenoids and a superficial stigma near the center of the cell. Numerous contractile vacuoles occur in the Peripheral cytoplasm and they are arranged in several rings around the nucleus in the constricted region of the cell. Ultrastructural studies verify these features and elaborate upon the structure of the cell.
TWO NEW PLOCENE SPECIES OF CYCLOSTEPHANOS (BACILLARIOPHYCEAE) WITH COMMENTS ON THE CLASSIFICATION OF THE FRESHWATER THALASSIOSIRACEAE1
Authors: Theriot Edward , Kociolek John P.
Published: March 2008

Two new species of the diatom genus Cyclostephanos Round are described from Pliocene fossil deposits in western North America. Cyclostephanos undatus is distinguished from other Cyclostephanos species by its tangentially undulate valve face; Cyclostephanos fenestratus is distinguished by its extremely shallow alveoli. This paper records previously unreported morphological detail of Cyclostephanos and speculates that structure of the punctum, labiate process and strutted process may enhance diagnosis of the freshwater genera of the Thalassiosiraceae Lebour emend. Hasle. Cyclostephanos undatus is similar to several Cyclotella species, but its external costae are raised and its alveolar morphology is similar to that of Cyclostephanos dubius (Fricke) Round. Cyclostephanos fenestratus is similar in external view to Stephanodiscus Ehrenb. However, the two species described here have flat cribra covering the mantle puncta and the labiate processes appear to lack external tubes, whereas Stephanodiscus species have domed mantle cribra and external tubes.
SEASONAL ANALYSIS OF VOLATILE ORGANIC BIOGENIC SUBSTANCES (VOBS) IN FRESHWATER PHYTOPLANKTON POPULATIONS DOMINATED BY DINOBRYON, MICROCYSTIS AND APHANIZOMENON1
Authors: Jüttner Friedrich , Höflacher Brigitte , Wurster Karl
Published: March 2008

Over the course of one year the volatile organic biogenic substances (VOBS) found in the water of a eutrophied shallow lake were determined by gas chromatographic and mass spectrometric methods. The substances detected belonged to nor‐carotenoids, terpenoids, unsaturated hydrocarbons, ketones, and aldehydes. The occurrence of particular VOBS correlated with the frequency with which certain phytoplankton species were recorded. The latter showed a well developed succession in that year. The following correspondences were found: β‐cyclocitral and Microcystis; heptadec‐cis 5‐ene and Oscillatoria redekei; geosmin and argosmin and Aphanizomenon gracile; hepta‐trans, cis 2,4‐dienal, deca‐trans, cis 2,4‐dienal and Dinobryon; octa‐trans, cis 1,3,5‐triene and Asterionella formosa. Dictyopterenes and ectocarpene were only detected in high amounts in one sample obtained in August. The VOBS exhibited marked dynamics in the lake and usually were rapidly eliminated from the water body.
PROTOPLAST ISOLATION AND CELL DIVISION IN THE AGAR‐PRODUCING SEAWEED GRACILARIA (RHODOPHYTA)1
Authors: Cheney Donald P. , Mar Emily , Saga Naotsune , van der Meer John
Published: March 2008

Methods were developed for the isolation of large numbers of healthy protoplasts from two species of the agarophyte Gracilaria; G. tikvahiae McLachlan and G. lemaneiformis (Bory) Weber‐van Bosse. This is the first report of protoplast isolation and cell division in a commercially important, phycocolloid‐producing red seaweed, as well as for a member of the Florideophycidae. The optimal enzyme composition for cell wall digestion and protoplast viability consisted of 3% Onozuka R‐10, 3% Macerozyme R‐10, 1% agarase and 0.5% Pectolyase Y‐ 23 dissolved in a 60% seawater osmoticum containing 1.0 M mannitol. The complete removal of the cell wall was confirmed by several different methods, including electron microscopic examination, and the absence of Calcofluor White (for cellulose) and TBO (for sulfated polysaccharide) staining. Spontaneous protoplast fusion was observed on several occasions. Protoplast viability was dependent upon the strain and age of the parent material, as well as the mannitol concentration of the enzyme osmoticum. Cell wall regeneration generally occurred in 2‐6 days; cell division in 5‐10 days. Protoplast‐produced cell masses up to the 16‐32 cell stage have been grown in culture. However, efforts to regenerate whole plants have been unsuccessful to date.
FRUSTULAR MORPHOLOGY AND TAXONOMIC AFFINITIES OF NAVICULA COMPLANATOIDES (BACILLARIOPHYCEAE)1
Authors: Brogan Michael W. , Rosowski James R.
Published: March 2008

Live and prepared cells of the marine pennate diatom Navicula complanatoides Hust. were examined with light and electron microscopy. It has narrowly lanceolate valves (26–55 μm long, 4–5 μm wide) and girdles 10–24 μm in depth. Striae are parallel at the center of the valve (24–28 in 10 μm), becoming slightly convergent toward the apices.

Electron microscopy revealed that the external valve surface presents a longitudinally ribbed appearance (20–28 parallel ribs at its maximum width), whereas internally, rectangular areolae are occluded by ricae. The raphe slit lies in a narrow axial area, and one side of the raphe sternum is deeper and folds over the other, obscuring the internal opening. Internally, the central virga on one side of the raphe and two virgae on the other are somewhat broader. A conspicuous pore (stigma) is present between the two broadened virgae.

The girdle consists of valvocopulae, copulae, and pleurae. There are 16–20 bands per cingulum. The valvocopulae and copulae are hollow tube‐like structures, with inner and outer portions contrsting in morphology. They decrease in diameter in an abvalvar direction. There are four pleurae. These are flat bands which facilitate overlap of the epicingulum and hypocingulum.

Fundamental features of the valve and girdle reveal the distinctness of this species within Navicula. The areolae, external longitudinal ribs, and raphe structure suggest affinities with Pleurosigma, Gyrosigma, and Haslea. It is hypothesized that they share a derived state which indicates a recent common ancestor for these taxa. N. complanatoides and related species of the Naviculae microstigmatacae are distinctive enough to merit their own genus within the Naviculaceae.
PROPERTIES OF MICROCYSTIS AERUGINOSA AND M. FLOS‐AQUAE (CYANOPHYTA) IN CULTURE: TAXONOMIC IMPLICATIONS1
Authors: Doers Mary P. , Parker Dorothy L.
Published: March 2008

Cultures were cloned from a sample containing Microcystis aeruginosa, M. flos‐aquae and a few morphological intermediates. The M. aeruginosa cultures remained distinct from the M. flos‐aquae cultures in (a) cell size, (b) cell aggregation pattern, (c) width of the mucilage surrounding the multicellular colonies, (d) sharpness of the mucilage boundary, (e) efect of 0.1–1.0 μM calcium chloride on the disaggregation of multicellular colonies, (f) frequency of mucilage mutants and (g) colony morphology on agar media. No M. flos‐aquae culture produced morphs resembling M. aeruginosa, inconsistent with proposals that M. flos‐aquae is a developmental stage or environmentally‐induced variant of M. aeruginosa. After longterm cultivation, but not soon after origanal isolation, several M. aeruginosa cultures contained mutants with diminished mucilage production and an altered colony shape.
LIPIDS AND CHEMOTAXONOMY OF PROCHLOROTHRIX HOLLANDICA, A PLANKTONIC PROKARYOTE CONTAINING CHLOROPHYLLS a AND b1
Authors: Volkman John K. , Burger‐Wiersma Tineke , Nichols Peter D. , Summons Roger E.
Published: March 2008

ABSTRACTS

The lipid composition of a planktonic prokaryote, Prochlorothrix hollandica Burger‐Wiersma, isolated from Lake Loosdrecht (The Netherlands) has been determined. This species is only the second prokaryote that has been found to contain chlorophylls a and b. Its lipid composition is similar to that of another prochlorophyte, Prochloron didemni Lewin, as well as to some cyanobacteria and bacteria, but there are also some unique features. Major fatty acids were 14:0, 14: 1ω5, 16:0, 16: 1ω7 and two novel fatty acids 16: 1ω12 (hexadec‐4‐enoic acid) and a new 16:2 isomer. Double bond positions in monounsaturated fatty acids and alkenes were determined by derivatization with dimethyl disulfide followed by analysis of the products by gas chromatography‐mass spectrometry. Hydrocarbons consisted mainly of the pentacyclic triterpene hop‐22(29)‐ene and straight‐chain n‐heptadecane and n‐heptadec‐5‐ene. The presence of hopanoids, low abundance of triacylglycerols and absence of sterols clearly show that the lipid biochemistry of this organism is more closely related to that of prokaryotes than to eukaryotes even though it contains chlorophyll b which is more typical of green algae. Implications of these data to chemotaxonomic studies of this unusual group of prokaryotes are discussed.
GLYOXYLATE CYCLE ENZYME ACTIVITIES IN THE CYANOBACTERIUM ANACYSTIS NIDULANS1
Authors: Eley James H.
Published: March 2008

The enzymes of the glyoxylate cycle, isocitrate lyase (EC.4.1.3.1) and malate synthase (EC.4.1.3.2), were measured in cell‐free extracts from the cyanobacterium Anacystis nidulans Drouet during photoautotrophic growth in medium aerated with ordinary air (0.03% CO2). Isocitrate lyase had an average specific activity of 112 nmoles·min−1·mg protein−1 whereas malate synthase had an average specific activity of 12.5 nmoles·min−1·mg protein−1. Unpurified isocitrate lyase showed classical Michaelis kinetics with a Km of 8 mM. Isocitrate lyase activity was strongly inhibited by numerous cellular metabolites at 10 mM concentration. The previously reported low specific activity for isocitrate lyase may be due to metabolite inhibition caused by growth in high CO2 concentrations. The activities reported for isocitrate lyase and malate synthase suggest the operation of the glyoxylate cycle in Anacystis nidulans under CO2‐limiting growth conditions.
COMPETITION FOR PHOSPHORUS BETWEEN DESMIDS1
Authors: Healey F. Patrick , Hendzel Leonard L.
Published: March 2008

During competition for phosphate in continuous cultures, Cosmarium subcostatum Nord. routinely displaced Staurastrum paradoxum Meyer. The rate of displacement was independent of cell density between 100 and 6000 cells mL−1. This suggests that competition for nutrients is important over a wide range of naturally occurring cell densities. C. subcostatum had higher saturated rates of phosphate uptake but also higher half saturation values for uptake. As a result, the two desmids were similarly able to take up phosphate at low concentrations. The competitive advantage of C. subcostatum lay in its greater yield per unit of phosphorus. Growth of the two algae in shared medium in a dual‐chamber chemostat had no effect on uptake or yield characteristics.
REPEAT AND SINGLE COPY SEQUENCES ARE DIFFERENTIALLY CONSERVED IN THE EVOLUTION OF KELP CHLOROPLAST DNA1
Authors: Fain Steven R. , Druehl Louis D. , Baillie David L.
Published: March 2008

A method for the isolation of total blade, chloroplast and nuclear DNAs from kelp is described. Total blade DNA was isolated from various kelp species at yields of about 1.0 μg.g−1 wet weight of tissue extracted. Purified chloroplast and nuclear DNAs were isolated from Macrocystis integrifolia at respective yields of about 0.05 μg.g−1 and 1.0 μg.g−1 wet weight of tissue extracted.

Hybridization experiments with a cloned portion of the 23S rRNA gene of M. integrifolia as probe (pMiR23S) showed that the M. integrifolia chloroplast genome contains two copies of the 23S rRNA gene.

Three regions of the kelp chloroplast genome were studied by restriction analysis of the cpDNA of five genera. Respective differences were assessed by comparing the restriction fragment patterns produced with five restriction endonucleases for each of three cloned M. integrifolia cpDNA hybridization probes. The kelp cpDNA sequences that hybridized to the repeated sequence probe pMiR23S were less divergent (100 × p = 2.53) than were the sequences that hybridized to the single copy probes pMiR432 and pMiH7 (100 × p = 7.48–7.74). Sequence variation (100 × p) between kelp species ranged from 3.38–6.82. Sequence variation between kelp species and Fucus gardneri ranged from 9.08–12.04.

Chloroplast DNA restriction fragment length data were used to derive two most parsimonious phylogenetic trees. Both trees had consistency indexes of 0.78 and indicated that the three lessoniacean genera in the comparison do not comprise a single distinct lineage.
THE USE OF PLASTID DNA RESTRICTION ENDONUCLEASE PATTERNS IN DELINEATING RED ALGAL SPECIES AND POPULATIONS1
Authors: Goff Lynda J. , Coleman Annette W.
Published: March 2008

Plastid DNA band patterns generated by electrophoresis of endonuclease digests demonstrate remarkable conservation of DNA sequences at the species and subspecies level in flowering plants. Generally, patterns are identical or near‐identical from different populations belonging to the same species. This methodology has now been applied to red algae to ascertain its value in systematic studies.

Plastid DNA from nine bangiophycean and florideophycean red algae was isolated and cut with restriction endonucleases that recognize different 6‐base pair sequences. The patterns generated upon the electrophoretic separation of digestion fragments show that within a species patterns are identical, but not within higher taxa. The proper identification of one Gracilaria population of uncertain taxonomic affinity was clearly established by this method of plastid DNA analysis.

Differences between species in plastid DNA sequences were confirmed by probing blots of restriction fragments with known gene sequences. A number of heterologous plastid DNA probes were found to be sufficiently homologous to be useful in studying red algal DNA.

Unexpectedly, supercoiled circular plasmids ranging in size from ca. 1.5–8 kb were found in some red algal species but not in others. The position of these plasmids in agarose gels following electrophoresis is uniform within a species but differs between different species of the same genus, contributing further patterns for taxonomic analysis.
Is Pregnancy the Time to Change Alcohol Consumption Habits in France?
Authors: De Chazeron Ingrid , Llorca Pierre‐Michel , Ughetto Sylvie , Vendittelli Françoise , Boussiron Didier , Sapin Vincent , Coudore François , Lemery Didier
Published: March 2008

Background:  Although it is well known that France has a cultural history of alcohol use, no recent French data on alcohol consumption during pregnancy in a large sample are available.

Methods:  To determine the alcohol consumption patterns among pregnant women in France, we analyzed data from a 1‐year multicenter self‐survey. Sociodemographic profile, obstetrical history, neonatal data, and a self‐report for assessing drinking patterns during pregnancy including AUDIT were recorded from women who delivered recently. Cases of fetal alcohol syndrome (FAS) were also reported.

Results:  A total of 837 pregnant women have described all parameters. The mean age at delivery of our sample was 29.7 years (SD = 4.8 years). A total of 52.2% of women indicated that they had consumed alcohol at least once during their pregnancy, and among abstainers 54.5% had a positive AUDIT score. Of the pregnant women who consumed alcohol, 13.7% reported at least one binge drinking episode (5 or more drinks on 1 occasion) during pregnancy. Binge drinking is significantly more frequent than regular alcohol consumption (at least 1 drink more than 1 time per week) during pregnancy. A prevalence rate of FAS of 1.8 per 1,000 live births was observed.

Conclusions:  There is a large population of women who still drink alcohol during pregnancy, particularly in binge drinking episodes. This underlines the need to clearly inform women of childbearing age about the dangers of alcohol during pregnancy as related to all types of consumption. Moreover, acting to prevent alcohol consumption prior to pregnancy may also greatly influence prenatal drinking.
Impulsive Errors on a Go‐NoGo Reaction Time Task: Disinhibitory Traits in Relation to a Family History of Alcoholism
Authors: Saunders Buddy , Farag Noha , Vincent Andrea S. , Collins Frank L. , Sorocco Kristen H. , Lovallo William R.
Published: March 2008

Background:  Behavioral undercontrol may contribute to risk for alcoholism in vulnerable persons. We predicted that healthy young adults with a family history of alcoholism (FH+) who also displayed externalizing behavior characteristics (low scores on the California Psychological Inventory Sociability Scale; CPI‐So) would exhibit more impulsive responding (false alarms) on a Go‐NoGo reaction time task.

Methods:  Subjects were 230 healthy volunteers, 18 to 30 years of age with no history of alcohol or drug dependence. The task included 100 trials: 60 of “Go,” calling for a button press, and 40 of “NoGo,” or “XX,” calling for inhibiting a response. Data analysis involved a signal detection analysis of performance with subsequent group comparisons for rates of impulsive responding indicated by False Alarms (responses to NoGo signals).

Results:  CPI‐So scores were lower in FH+ than in FH– (p < .000001) indicating a greater clustering of disinhibitory tendencies in these persons. FH, CPI‐So scores, and Gender together predicted false alarm rates, accounting for 4.9% of the variance, F = 3.89, p = 0.009. False alarms were associated with low CPI‐So scores, F = 5.15, p = 0.024, and being male, F = 6.27, p = 0.013, but not with FH once these variables were accounted for.

Conclusions:  A disinhibited temperament may underlie a behavioral impulsivity that contributes to elevated risk for future alcoholism, especially among FH+ males.
The use of granulocyte–colony‐stimulating factor in volunteer unrelated hemopoietic stem cell donors
Authors: Pamphilon Derwood , Nacheva Elisabeth , Navarrete Cristina , Madrigal Alejandro , Goldman John
Published: March 2008

Granulocyte–colony‐stimulating factor (G‐CSF) is used for the mobilization of hemopoietic stem cells in healthy donors. It has a number of common side effects such as bone pain, which resolve rapidly after administration is discontinued. Recent publications have raised concern that it might act as a trigger for the development of hematologic malignancy in susceptible individuals, possibly by causing genomic instability, but to date there is no evidence that healthy volunteer donors who receive G‐CSF are at any increased risk. Ongoing studies aim to confirm whether or not G‐CSF can cause chromosomal abnormalities in healthy donors. In the UK, the British Bone Marrow Registry and Anthony Nolan Trust give G‐CSF to donors who have agreed to donate peripheral blood stem cells. It is recommended by the UK Registries at present that all stem cell donors are given updated information explaining the current uncertainties with regard to the use of G‐CSF before they give informed consent to its administration. This information is based on a statement agreed by the World Marrow Donor Association for use by individual donor registries. Further, it is our current practice that all donors who have received G‐CSF, as well as marrow donors who do not, should be under regular review for at least 10 years to allow the occurrence of any long‐term adverse events to be documented.
How Do People Cope with Natural Disasters? Evidence from the Great Hanshin‐Awaji (Kobe) Earthquake in 1995
Authors: SAWADA YASUYUKI , SHIMIZUTANI SATOSHI
Published: March 2008

This paper investigates the coping strategies employed by victims of the Great Hanshin‐Awaji (Kobe) earthquake in 1995. Using a unique household data set, we show that households that held a large amount of collateralizable assets before the catastrophe and were free from a binding borrowing constraint were able to maintain their consumption levels by borrowing. In contrast, households subject to a binding borrowing constraint before the disaster were unable to borrow to cope with the losses inflicted by the earthquake. On the other hand, both types of households relied on private transfers, depending on the extent of the damage.
Differences in Interest Rate Policy at the ECB and the Fed: An Investigation with a Medium‐Scale DSGE Model
Authors: SAHUC JEAN‐GUILLAUME , SMETS FRANK
Published: March 2008

Using two estimated models for the euro area and the United States, this paper investigates whether the observed difference in the amplitude of the interest rate cycle since 1999 in both areas is due to differences in the estimated monetary policy reaction function, differences in the structure of the economy or differences in the size and nature of the shocks hitting both economies. The paper concludes that differences in the type, size and persistence of shocks in both areas can largely explain the different interest rate setting.
Why Do Bank Runs Look Like Panic? A New Explanation
Authors: CHEN YEHNING , HASAN IFTEKHAR
Published: March 2008

This paper demonstrates that, even if depositors are fully rational and always choose the Pareto‐dominant equilibrium when there are multiple equilibria, a bank run may still occur when depositors' expectations on the bank's fundamentals do not change. More specifically, a bank run may occur when depositors learn that noisy bank‐specific information will be revealed, or when they learn that precise bank‐specific information will not be revealed. The results in this paper are consistent with the empirical evidence about bank runs. It also implies that suspension of convertibility can improve the efficiency of bank runs.
American Sign Language as a Foreign Language in U.S. High Schools: State of the Art
Authors: ROSEN RUSSELL S.
Published: March 2008

The last 2 decades witnessed a growth in American Sign Language (ASL) as a foreign language in U.S. secondary schools. This overview of the current state of ASL as a foreign language in the schools consists of a history and a survey. The information on history was drawn from a study conducted byRosen (2006). This history is followed by a national survey compiled byRosen (2005)on U.S. secondary schools offering ASL for foreign language credit. The survey provided information on the number and distribution of schools, teachers, classes, students, departments, and the process for program implementation. The information is used to ascertain the current breadth and scope of, and to discern trends in, ASL as a foreign language in public high schools nationwide.
What's the Problem? L2 Learners' Use of the L1 During Consciousness‐Raising, Form‐Focused Tasks
Authors: SCOTT VIRGINIA M. , FUENTE MARÍA JOSÉ DE LA
Published: March 2008

This qualitative study provides preliminary insight into the role of the first language (L1) when pairs of intermediate‐level college learners of French and Spanish are engaged in consciousness‐raising, form‐focused grammar tasks. Using conversation analysis of audiotaped interactions and stimulated recall sessions, we explored the ways students used the L1 and their second language (L2) to solve a grammar problem. Students who were allowed to use the L1 (Group 1) worked collaboratively in a balanced and coherent manner; students who were required to use the L2 (Group 2) exhibited fragmented interaction and little evidence of collaboration. Findings from the stimulated recall sessions suggested that reading, thinking, and talking appeared to be simultaneous and integrated processes for the students in Group 1, whereas these processes appeared to be sequential and competing for the students in Group 2. In addition to suggesting that using the L1 for these kinds of tasks reduces cognitive overload, these findings invite teachers to tackle the “problem” of the L1 in the foreign language classroom.
Managing Interdependence: The Effects of Outsourcing Structure on the Performance of Complex Projects*
Authors: Hui Pamsy P. , Davis‐Blake Alison , Broschak Joseph P.
Published: March 2008

The outsourcing of complex activities has become a common organizational practice. Yet very little research has focused on the implications of how these activities are divided up among outsourcing partners. Drawing on structural contingency theory, we argue that: (1) because activities within stages of complex projects are highly interdependent, outsourcing structures where owner firms do not maintain high levels of dominance over the activities that are performed will pose control and coordination challenges, leading to poor project performance; (2) the adverse effects of poorly structured outsourcing arrangements will spill over to subsequent project stages when activities are interdependent across project stages; and (3) dividing activities among large numbers of contractors or distributing work evenly among contractors exacerbates coordination and control problems further contributing to poor project performance. Our empirical analysis of 323 capital facility construction projects supports our predictions. Overall, these results provide strong evidence that some outsourcing structures are more costly than others and that because of the nature of complex projects the detrimental effects of poorly structured outsourcing are often not completely observable at the time activities are completed. We discuss the implications of our findings for capital construction and for outsourcing more generally.
Pooling Data Across Transparently Different Groups of Key Informants: Measurement Equivalence and Survey Research*
Authors: Rungtusanatham M. , Ng C. H. , Zhao X. , Lee T. S.
Published: March 2008

Survey research is often deployed in the study of situational issues facing organizations and functions within organizations. One particular survey research approach can be described as follows: (1) survey questionnaires involving perceptual questions about a situational issue are administered to key informants, one key informant per unit of analysis; (2) key informants vary in a transparent manner across units of analysis such that groups of these key informants are discernible; and (3) perceptual responses, after data collection, are then pooled to create a single larger data set for subsequent statistical manipulations. In this methodological note, we draw attention to this particular survey research approach and ask the question: When is it appropriate to pool data provided by key informants with transparently different demographics across units of analysis so as to create a single larger data set for statistical manipulations? We use a simple example and data from a published study to motivate the relevance and gravity of this methodological question. Offering the concept and empirical assessment of measurement equivalence as the answer to this methodological question of data pooling, we prescribe and demonstrate, with the total quality management→customer satisfaction relationship, the procedural steps for evaluating the seven subdimensions of measurement equivalence. In conclusion, we highlight methods that should be adopted, before data collection, to minimize the risk of violating measurement equivalence. After data collection and for the instances when the empirical assessment for measurement equivalence advises against pooling of such data, we also offer suggestions for analyzing such data and presenting associated statistical results.
Expected Time Value Decay of Options: Implications for Put‐Rolling Strategies
Authors: Tannous George F. , Lee‐Sing Clifton
Published: March 2008

Assuming the underlying asset price remains constant, previous studies show that the time value of an option decays gradually at a rate that accelerates over time and peaks at the expiration date. Thus, a significant portion of time value is lost in the four weeks leading up to expiration. This paper shows the time value of currently at‐ or near‐the‐money options should be expected to decay at a rate that decreases over time. The time values of options that are currently deep‐in‐ or deep‐out‐of‐the‐money are expected to initially rise and then resume the normal decay pattern.
Brugada Syndrome in Pure Black Africans
Authors: BONNY AIMÉ , TONET JOELCI , FONTAINE GUY , LACOTTE JÉRÔME , COIGNARD ELISABETH , DUTHOIT GUILLAUME , HIDDEN‐LUCET FRANÇOISE , CHARRON PHILIPPE , BRUGADA PEDRO , FRANK ROBERT
Published: March 2008

Aims: Although all races are concerned with the Brugada syndrome, no case has ever been reported among black Africans. We describe five different cases in this specific group of populations.

Methods and Results: In all patients, Brugada syndrome was identified after detailed noninvasive and invasive evaluations. Sex ratio was four males for one female. Convulsive syncope was noticed in 1 patient with a family history of sudden death. Diagnostic coved‐type pattern was observed spontaneously in the normal position of right precordial leads in 3 patients and in a higher position of leads in 3 patients. Sixty percent had first‐degree atrioventricular block. An ajmaline test was performed in 4 patients and was positive either in normal position of leads or in superior position in all of them. Sustained ventricular tachycardia (VT) or ventricular fibrillation (VF) was inducible during programmed ventricular stimulation in 3 patients. Right ventricular cineangiography found localized apical hypokinesia with preserved systolic function in 1 patient. Automatic cardioverter defibrillator was implanted in 2 patients. SCN5A was not found in any of the patients.

Conclusion: These observations demonstrate that Brugada syndrome is also present in black African populations, and increasingly reported cases of apparent sudden death in the sub‐Saharan part of the world need to rule out cardiac electrical disturbance such as Brugada syndrome.
Time and Temperature Profile of Catheter Cryoablation of Right Septal and Free Wall Accessory Pathways in Children
Authors: KALTMAN JONATHAN R. , TANEL RONN E. , WEGRZYNOWICZ BRADLEY , KOZODOY ERIC , WIEAND TAMMY , ENNIS JEAN , VETTER VICTORIA L. , SHAH MAULLY J.
Published: March 2008

Introduction: The overall acute success with cryoablation for accessory pathways (APs) has been reported to be lower than with radiofrequency ablation. Generally, prior cryomapping (limited to −30°C) has been used to test for loss of AP conduction and absence of atrioventricular (AV) node impairment. However, the temperature at which loss of AP conduction occurs may be variable. The purpose of this study was to evaluate the time and temperature profile at which loss of AP conduction occurs.

Methods and Results: A retrospective study evaluated 25 patients (mean age 13.3 ± 3.6 years) who underwent cryoablation for right‐sided APs (22 manifest/3 concealed). Direct cryoablation (–80°C) without cryomapping was performed using a “time to success” strategy. If AP conduction was successfully interrupted within 25 seconds of the onset of cryoablation, the lesion was continued for 240 seconds; otherwise it was terminated and further mapping was performed. Cryoablation was successful in 24/25 (96%) patients. Temperature at loss of AP conduction was −66.2 ±−16.7°C (range +32 to −84°C) with conduction block at temperatures lower than −30°C for all but 3 APs. Critical time to success (interval from cryoadherence to loss of AP conduction) was significantly shorter for permanently successful cryolesions, compared with transiently successful lesions (6.3 ± 4.1 vs. 11.2 ± 2.2 sec; P < 0.001). There were no major complications.

Conclusions: Cryothermal energy required for successful ablation may be variable and restricting test applications to −30°may limit its efficacy. A “time to success” strategy may improve outcome of cryoablation for right‐sided APs in children without compromising safety.
Differences in 12‐Lead Electrocardiogram Between Symptomatic and Asymptomatic Brugada Syndrome Patients
Authors: JUNTTILA M. JUHANI , BRUGADA PEDRO , HONG KUI , LIZOTTE ERIC , DE ZUTTER MARC , SARKOZY ANDREA , BRUGADA JOSEP , BENITO BEGONA , PERKIOMAKI JUHA S. , MÄKIKALLIO TIMO H. , HUIKURI HEIKKI V. , BRUGADA RAMON
Published: March 2008

Introduction:
Brugada syndrome (BrS) is an inherited disorder that predisposes some subjects to sudden cardiac death (SCD). It is not well established which BrS patients are at risk of severe arrhythmias. Our aim was to study whether standard 12‐lead electrocardiogram (ECG) would give useful information for this purpose.

Methods:
This study included 200 BrS probands (142 male, 62%; mean age 42 ± 16 years). Symptoms related to BrS were defined as syncope, documented ventricular tachyarrhythmia, or SCD. We determined PR, QRS, QTc, Tpeak, and Tend interval from leads II and V2 and QRS from lead V5, R′/S ratio from lead aVR (aVR sign), QRS axis, and J‐point elevation amplitude from right precordial leads from the baseline ECGs.

Results:
Sixty‐six subjects (33%) had experienced symptoms related to BrS. The only significant difference between the symptomatic and asymptomatic BrS subjects was the QRS duration measured from lead II or lead V2, for example, the mean QRS in V2 was 115 ± 26 ms in symptomatic versus 104 ± 19 ms in asymptomatic patients (P < 0.001). The optimized cut‐off point of V2 QRS ≥120 ms gave an odds ratio (OR) of 2.5 (95% CI: 1.4–4.6, P = 0.003) for being symptomatic. In a multivariate analysis adjusted with gender, age, and SCN5A mutation, the OR was 2.6 (95% CI: 1.4–4.8, P = 0.004).

Conclusion:
Prolonged QRS duration, measured from standard 12‐lead ECG, is associated with symptoms and could serve as a simple noninvasive risk marker of vulnerability to life‐threatening ventricular arrhythmias in BrS.
Automatic 3D Mapping of Complex Fractionated Atrial Electrograms (CFAE) in Patients with Paroxysmal and Persistent Atrial Fibrillation
Authors: WU JINJIN , ESTNER HEIDI , LUIK ARMIN , ÜCER EKREM , REENTS TILKO , PFLAUMER ANDREAS , ZRENNER BERNHARD , HESSLING GABRIELE , DEISENHOFER ISABEL
Published: March 2008

Background:
Complex fractionated atrial electrograms (CFAE) are a possible target for atrial fibrillation (AF) ablation and can be visualized in three‐dimensional (3D) mapping systems with specialized software.

Objective:
To use the new CFAE software of CartoXP® (Biosense Webster, Diamond Bar, CA, USA) for analysis of spatial distribution of CFAE in paroxysmal and persistent AF.

Methods:
We included 16 consecutive patients (6 females; mean 59.3 years) with AF (6 paroxysmal and 10 persistent) undergoing AF ablation. Carto maps of left atrium (LA) were reconstructed. Using the new CFAE software, the degree of local electrogram fractionation was displayed color‐coded on the map surface. LA was divided into four regions: anterior wall, inferior wall, septum, and pulmonary veins (PV). The relationship among regions with CFAE visualized and CFAE ablation regions (persistent AF only) was analyzed retrospectively.

Results:
In paroxysmal and persistent AF, CFAE were observed in all four LA regions. In paroxysmal AF, the density of CFAE around the PV was significantly higher than in other regions (P < 0.05) and higher than in persistent AF (P < 0.05). In persistent AF, CFAE were evenly distributed all over the LA. Of 40 effective ablation sites with significant AF cycle length prolongation, 33 (82.5%) were judged retrospectively by CFAE map as CFAE sites.

Conclusion:
CFAE software can visualize the spatial distribution of CFAE in AF. CFAE in persistent AF were observed in more regions of LA compared to paroxysmal AF in which CFAE concentrated on the PV. Automatically detected CFAE match well with ablation sites targeted by operators.
Anatomy and Physiology of the Right Interganglionic Nerve: Implications for the Pathophysiology of Inappropriate Sinus Tachycardia
Authors: ZHOU JING , SCHERLAG BENJAMIN J. , NIU GUODONG , HOU YINGLONG , LU ZHIBING , ZHANG YUAN , DING YANSHENG , LAZZARA RALPH , JACKMAN WARREN M. , PO SUNNY S.
Published: March 2008

Objective:
To simulate inappropriate sinus tachycardia (IST) in experimental animals.

Background:
We recently found that epinephrine injected into the anterior right ganglionated plexi (ARGP) adjacent to the sinoatrial (SA) node induced an arrhythmia simulating IST.

Methods:
In 19 anesthetized dogs, via a right thoracotomy, the course of the interganglionic nerve (IGN) from the right stellate ganglion along the superior vena cava to the heart was delineated. High‐frequency stimulation (HFS; 0.1 msec duration, 20 Hz, 4.5–9.3 V) was applied to IGN at the junction of innominate vein and SVC.

Results:
HFS of the IGN significantly increased the sinus rate (SR) (baseline: 156 ± 19 beats/minutes [bpm], 4.5 V: 191 ± 28 bpm*, 8.0 V: 207 ± 23 bpm*, 9.3 V: 216 ± 18 bpm*; *P < 0.01 compared to baseline) without significant changes in A‐H interval or blood pressure. P‐wave morphology, ice mapping, and noncontact mapping indicated that this tachycardia was sinus tachycardia. In 8 of 19 dogs, injecting hexamethonium (5 mg), a ganglionic blocker, into the ARGP attenuated the response elicited by IGN stimulation (baseline: 160 ± 21 bpm, 4.5 V: 172 ± 32 bpm, 8.0 V: 197 ± 32 bpm*, 9.3 V: 206 ± 26 bpm*; *P < 0.05 compared to baseline). In 19 of 19 animals, after formaldehyde injection into the ARGP, SR acceleration induced by IGN stimulation was markedly attenuated (baseline: 149 ± 17 bpm, 4.5 V: 151 ± 21 bpm, 8.0 V: 155 ± 23 bpm, 9.3 V: 167 ± 24 bpm*; *P < 0.05 compared to baseline).

Conclusions:
HFS of the IGN caused a selective and significant acceleration of the SR. A significant portion of IGN traverses the ARGP or synapses with the autonomic ganglia in the ARGP before en route to the SA node. Dysautonomia involving the IGN and/or ARGP may play an important role in IST.
Estimation and Inference for the Causal Effect of Receiving Treatment on a Multinomial Outcome
Authors: Cheng Jing
Published: March 2008

Summary This article considers the analysis of two‐arm randomized trials with noncompliance, which have a multinomial outcome. We first define the causal effect in these trials as some function of outcome distributions of compliers with and without treatment (e.g., the complier average causal effect, the measure of stochastic superiority of treatment over control for compliers), then estimate the causal effect with the likelihood method. Next, based on the likelihood‐ratio (LR) statistic, we test those functions of or the equality of the outcome distributions of compliers with and without treatment. Although the corresponding LR statistic follows a chi‐squared (χ2) distribution asymptotically when the true values of parameters are in the interior of the parameter space under the null, its asymptotic distribution is not χ2 when the true values of parameters are on the boundary of the parameter space under the null. Therefore, we propose a bootstrap/double bootstrap version of a LR test for the causal effect in these trials. The methods are illustrated by an analysis of data from a randomized trial of an encouragement intervention to improve adherence to prescribed depression treatments among depressed elderly patients in primary care practices.
A Semi‐Parametric Shared Parameter Model to Handle Nonmonotone Nonignorable Missingness
Authors: Tsonaka Roula , Verbeke Geert , Lesaffre Emmanuel
Published: March 2008

Summary Longitudinal studies often generate incomplete response patterns according to a missing not at random mechanism. Shared parameter models provide an appealing framework for the joint modelling of the measurement and missingness processes, especially in the nonmonotone missingness case, and assume a set of random effects to induce the interdependence. Parametric assumptions are typically made for the random effects distribution, violation of which leads to model misspecification with a potential effect on the parameter estimates and standard errors. In this article we avoid any parametric assumption for the random effects distribution and leave it completely unspecified. The estimation of the model is then made using a semi‐parametric maximum likelihood method. Our proposal is illustrated on a randomized longitudinal study on patients with rheumatoid arthritis exhibiting nonmonotone missingness.
Synthesis and Characterization of Coralline Magnesium Oxide Nanoparticles
Authors: Boddu Veera M. , Viswanath Dabir S. , Maloney Stephen W.
Published: March 2008

Magnesium oxide (MgO) nanoparticles were prepared using sol–gel process. The nanoparticles were then dried using a supercritical drying process. The particles were characterized for surface morphology, crystal structure, and surface functionality. The nanoparticles show a coralline structure with an average particle size of 200–300 nm with a surface area of 257 m2/g. The X‐ray diffraction spectra of these materials are also obtained. The MgO particles, when contacted with a model explosive component 2, 4 dinitrotoluene in water at 50°C, showed a concentration reduction of 96%.
Flexural Creep Deformation of ZrB2/SiC Ceramics in Oxidizing Atmosphere
Authors: Talmy I. G. , Zaykoski J. A. , Martin C.A.
Published: March 2008

Flexural creep of ZrB2/0–50 vol% SiC ceramics was characterized in oxidizing atmosphere as a function of temperature (1200°–1500°C), stress (30–180 MPa), and SiC particle size (2 and 10 μm). Creep behavior showed strong dependence on SiC content and particle size, temperature and stress. The rate of creep increased with increasing SiC content, temperature, and stress and with decreasing SiC particle size, especially, at temperatures above 1300°C. The activation energy of creep showed linear dependence on the SiC content increasing from about 130 to 511 kJ/mol for ceramics containing 0 and 50 vol% 2‐μm SiC, respectively. The stress exponent was about 2 for ZrB2 containing 50 vol% SiC regardless of SiC particle size, which is an indication that the leading mechanism of creep for this composition is sliding of grain boundaries. Compared with that, the stress exponent is about 1 for ZrB2 containing 0–25vol% SiC, which is an indication that diffusional creep has a significant contribution to the mechanism of creep for these compositions. Cracking and grain shifting were observed on the tensile side of the samples containing 25 and 50 vol% SiC. Cracks propagate through the SiC phase confirming the assumption that grain‐boundary sliding of the SiC grains is the controlling creep mechanism in the ceramics containing 50 vol% SiC. The presence of stress, both compressive and tensile, in the samples enhanced oxidation.
Estimating Observation Unit Profitability with Options Modeling
Authors: Baugh Christopher W. , Stephen Bohan J.
Published: March 2008

Background:  Over the past two decades, the use of observation units to treat such common conditions as chest pain, asthma, and others has greatly increased. These units allow patients to be directed out of emergency department (ED) acute care beds while potentially avoiding inpatient admission. Many studies have demonstrated the clinical effectiveness of care delivered in such a setting compared to the ED or inpatient ward. However, there are limited data published about observation unit finance.

Methods:  Using the economic principles of stock options, opportunity costs, and net present value (NPV), a model that captures the value generated by admitting a patient to an observation unit was derived. In addition, an appendix is included showing how this model can be used to calculate the dollar value of an observation unit admission.

Results:  A model is presented that captures more complexity of observation finance than the simple difference between payments and costs. The calculated estimate in the Appendix suggests that the average value of a single observation unit admission was about $2,908, which is about 40% higher than expected.

Conclusion:  Subtraction of costs from payments may significantly underestimate the financial value of an observation unit admission. However, the positive value generated by an observation unit bed must be considered in the context of other projects available to hospital administrators.