bluuebunny/crossref_metadata_2025_split huggingface dataset:
SEASONAL PATTERNS OF MORPHOLOGICAL VARIABILITY IN SARGASSUM POLYCERATIUM (PHAEOPHYTA)1
Authors: Kilar John A. , Hanisak M. Dennis 
Published: March 2008

ABSTRACTTemporal variability in certain morphological and taxonomically important features was quantified for Sargassum polyceratium Mont. from a population in the Content Keys, Florida (U.S.A.). Patterns of blade development, senescence, and loss caused pronounced seasonal changes in blade length‐width ratios. Blade length and width were maximal early in the growing season (August‐November) and decreased as the annual stems matured. Early in the growing season, plants had broader blades with randomly distributed cryptostomata. Late in the growing season (February‐April), plants had more linear blades with cryptostomata approximately arranged in two rows, one on each side of the midrib. The length‐width ratio of blades increased acropetally along the stems and were directly correlated to the size of the cryptostomatal opening and inversely correlated with the number of cryptostomata. The branching pattern of the annual stems ranged from short spur branches to well‐developed, lateral axillary branches. The frequency of bifurcated blades increased significantly late in the growing season. Vesicle shape and size and pedicel length were temporally stable. Alated pedicels and mucronate vesicles occurred in low frequencies. The variability of the morphological features used to delineate species within the genus Sargassum on the tropical eastern coasts of the Americas is poorly understood.
STRUCTURE AND FUNCTION OF THE BRISTLES OF PEDIASTRUM BORYANUM (CHLOROPHYTA)1
Authors: Gawlik Stanley R. , Millington William F. 
Published: March 2008

ABSTRACTTufts of long delicate bristles were detected on mature colonies of Pediastrum boryanum (Turp.) Meneghini. The bristles are not uniform in length and can exceed 100 μm. Bristle number per tuft can exceed eighty. Ultrastructure studies revealed that tufts are an aggregate of hexagonal tubules arranged in staggered rows. Each hexagonal tubule has an inner diameter of 6 nm and is made up of six interconnected subunits 4 nm in diameter that are shared by adjoining tubules. The bristles can be easily removed from mature colonies with a vortex stirrer. Removal of bristles from mature colonies in culture results in the loss of buoyancy and subsequent settling to the bottom of the flask.
THE FLAGELLAR APPARATUS AND RESERVOIR/CANAL CYTOSKELETON OF CRYPTOGLENA PIGRA (EUGLENOPHYCEAE)1
Authors: Owens Kristin J. , Farmer Mark A. , Triemer Richard E. 
Published: March 2008

ABSTRACTThe flagellar apparatus and reservoir cytoskeleton of Cryptoglena pigra Ehrenberg are described. Three flagellar roots are associated with the two basal bodies. The four‐membered dorsal root arises from the dorsal basal body and extends anteriorly following the reservoir membrane. At the base of the reservoir the dorsal root nucleates a large microtubular group termed the dorsal band. The dorsal band continues anteriorlhy between the reservoir and eyespot and is continuous with the microtubules of the canal and ultimately the pellicle. The ventral basal body is associated with two roots. The four‐membered intermediate root proceeds anteriorly and extends the length of the reservoir. The seven‐to eight‐membered ventral root projects anteriorly along the reservoir membrane and bends away from the reservoir. At this point, the microtubules of the ventral root line a cytoplasmic pocket and are termed the MTR (reinforcing microtubules). The canal region is composed of longitudinal microtubules surrounded by two semicircles of microtubles. Ultimately, the fifteen ridges of the canal give rise to the pellicular ridges.
ENDOPHYTIC ALGAE OF CHONDRUS CRISPUS (RHODOHYTA). II. ACROCHAETE HETEROCLADA SP. NOV., A. OPERCULATA SP. NOV., AND PHAEOPHILA DENDROIDES (CHLOROPHYTA)1
Authors: Correa Jun A. , Nielsen Ruth , Grund Darryl W. 
Published: March 2008

ABSTRACTThe occurrence of three endophytic green algae within Chondrus crispus Stackh. is reported. Two of them are new to science and are described as Acrochaete heteroclada Correa and Nielsen sp. nov. and A. operculata Correa and Nielsen sp. nov. The algae were studied in unialgal culture and in association with the host following infection of C. crispus under laboratory conditions. The experimental infection showed A. heteroclada to be initially epiphytic, with endophytic filaments growing into the cortex of the host during late infection. A. operculata is entirely endophytic when associated with the host. Phaeophila dendroides (Crouan frat.) Batters behaves as an epiphyte at 15 and 24°C but penetrates the host tissues at 20°C. For all three species, a close physical association with the host is established only when zoospores settle and germinate on the surface of C. crispus.
PHYCOGENETIC COMPARISON OF THE SMALL‐SUBUNIT RIBOSOMAL DNA SEQUENCE OF COSTARIA COSTATA (PHAEOPHYTA) WITH THOSE OF OTHER ALGAE, VASCULAR PLANTS AND OOMYCETES1
Authors: Bhattacharya Debashish , Druehl Louis D. 
Published: March 2008

ABSTRACTThe small‐subunit ribosomal DNA (rDNA) coding sequence was determined for the help Costaris Costata (Phaeophyta) and compared to those of chlorophyll a + b‐ and chlorophyll a + c‐containing vascular and nonvascular plants. Phylogenetic comparison of all sequences indicated a common ancestor for phaeophytes, chrysophytes and oomycetes. Phylogenies based on rDNA sequence data and those based on plastid characteristics were compared. Relative evolutionary distances between some taxa, derived from rDNA sequence data, conflicted with findings of plastid‐based phylogenies.
THE MICROTUBULAR CYTOSKELETON OF AMPHIDINIUM RHYNCHOCEPHALUM (DINOPHYCEAE)1
Authors: Roberts Keith R. , Farmer Mark A. , Schneider Robin M. , Lemoine Julie E. 
Published: March 2008

ABSTRACTSThe sub‐thecal microtubular cytoskeleton of Amphidinium rhynchocephalum Anissimowa was investigated using indirect immunofluorescence microscopy and transmission electron microscopy. The majority of sub‐thecal microtubules are longitudinally oriented and radiate from one of two sub‐thecal transverse microtubular bands that lie adjacent to the anterior and posterior edge of the cingulum.Both transverse bands consist of 3–5 microtubules and are loop shaped with one end adjacent to the cell's right edge of the sulcus and the other end adjacent to the fibrous ventral ridge. The posterior transverse microtubular band (PTB) defines the posterior edge of the cingulum and gives rise to numerous posteriorly directed longitudinal microtubular bundles that consist of 1–3 microtubules per bundle. These bundles end at the posterior end of the cell. The PTB also gives rise to the cingular longitudinal microtubules that underlie the cingular groove and terminate at the anterior transverse microtubular band (ATB). The ATB defines the anterior edge of the cingulum and loops around the base of the epicone. This band gives rise to anteriorly directed longitudinal microtubular bundles that terminate in the small epicone of the cell. The longitudinal microtubular root of the flagellar apparatus is directed posteriorly and lies immediately beneath the theca but is distinct from the subthecal microtubule system. A narrow fibrous ridge is ventrally located to the cell's left between the exit apertures of the transverse and longitudinal flagella. In this position, the ventral ridge lies between and also connects with the anterior and posterior transverse microtubular bands. The ventral ridge is also associated with three microtubules that are distinct from other cytoskeletal microtubules. Our results demonstrate that the majority of sub‐thecal microtubules originate from one of two microtubular bands associated with the cingulum. The possible role of the fibrous ventral ridge and its associated microtubules is also discussed.
PHYSIOLOGICAL ECOLOGY OF NITROGEN FIXING BLUE‐GREEN ALGAL CRUSTS IN THE UPPER‐SUBALPINE LIFE ZONE1
Authors: Fritz‐Sheridan Richard P. 
Published: March 2008

ABSTRACTBlue‐green algal (cyanobacterial) crusts composed of nitrogen fixing Nostoc commune Voucher ex Born. et Flah. and Tolypothrix conglutinata var. colorata Ghose were studied in the upper‐subalpine life zone, Mission Mountain Wilderness, Montana. Rates of ethylene production were highest in the submerged shoreline crusts, lower for exposed crusts pioneering rocky shorelines and lowest in the Carex meadow. Nitrogenase activity (acetylene reduction technique) was constant between 200–285% crust moisture content (wet/dry weight) and then rapidly declined to 0 between 200–140%. Optimal temperatures for ethylene production by illuminated cells was between 20–30° C for T. conglutinata, 20° C for N. commune and about 25° C in darkness for both species. Nitrogenase activity by T. conglutinata in culture was unaffected by repeated freeze‐thaw treatments whereas N. commune was severely inhibited. In contrast, N2‐ase activity of these two species in an intact crust was unaffected by repeated freeze‐thaw treatments. Application of nitrogen‐free growth medium to intact crusts increased nitrogenase activity by 3.7 times implying that these were mineral deficient under field conditions. Photosynthesis was light saturated at 125 μmol‐m−2.s−1 whereas nitrogenase activity was light independent for cells with carbohydrate reserves. When carbohydrate reserves were reduced by 8 h incubation in darkness, between 1–3 h of illumination were required to restore nitrogenase activity to 80% of the maximum rate. Biochemical pathway inhibitor studies employing DCMU, MFA, and CCCP showed that oxidative metabolism was the source of reductant for acetylene reduction. Tetrazolium precipitation in heterocysts paralleled acetylene reduction activity in the inhibitor treated cells.
DIEL PERIODICITY OF PHOTOSYNTHESIS AND CELL DIVISION COMPARED IN THALASSIOSIRA WEISSFLOGII (BACILLARIOPHYCEAE)1
Authors: Putt Mary , Prézelin Barbara B. 
Published: March 2008

ABSTRACTDiel patterns of photosynthesis and cell division were examined in Thalassiosira weissflogii Grun. (clone Actin) grown in nitrogen‐limited cyclostat culture. Ammonia (NH4+) was either supplied continuously or as a daily pulse to cultures grown in constant light or in a light: dark cycle. When either nitrogen or light was supplied periodically, both cell division and photosynthetic capacity were periodic. When both nitrogen and light were supplied periodically, cell division was coupled to the N‐pulse whereas periodicities of photosynthetic capacity were modified but remained coupled to the light‐dark cycle. Diel oscillations in photosynthesis were i) largely independent of cellular pigmentation and ii) similar for light‐limiting and saturating irradiances. Periodicity in photosynthetic capacity also persisted following transfer of non‐dividing batch cultures to constant light. Results suggest that photosynthesis but not cell division was coupled to a circadian clock in T. weissflogii. A circadian rhythm of photosynthesis may optimize carbon assimilation in phytoplankton exposed to intermittent nutrient supply by ensuring that maximum photosynthetic capacity occurs during the day.
ASCOPHYLLUM NODOSUM (PHAEOPHYTA) IN AXENIC CULTURE AND ITS RESPONSE TO THE ENDOPHYTIC FUNGUS MYCOSPHAERELLA ASCOPHYLLI AND EPIPHYTIC BACTERIA1
Authors: Fries Lisbeth 
Published: March 2008

ABSTRACTAscophyllum nodosum (L.) Le Jol. was freed from bacteria and the endophytic fungus Mycosphaerella ascophylli Cotton by repeated treatment with chlorine solutions and grown in artificial seawater. Two types of axenic culture of different origin were obtained. Type 1 was developed from apices of A. nodosum collected in the sea. Type 2 was from plants which developed from adventitious embryos on rhizoids formed by type 1. This is the first time A. nodosum has been cultivated axenically. Growth of the axenic alga was increased by IAA, 21P and zeatin. Without external growth regulators some strains of the axenic alga deteriorated within a year; others developed a filamentous habit. Sulfur in a reduced state also stimulated growth. Addition of either glucose, mannose or mannitol to the medium caused the formation of calluslike layers of loosely packed colorless cells under the epidermis of the thalli and the epidermis was sloughed off. No increase in thallus length was noticed.Mycosphaerella ascophylli in axenic culture did not excude any substances stimulating growth of the alga, but that does not exclude an influence of the fungus on the alga in vivo. The fungus, when growing within the alga, seemed to have little influence on algal morphology. A bacterized but fungus‐free A. nodosum was cultivated in an artificial seawater for 8 years. In the bacteria‐free alga, the fungus protruded from the epidermis and evidently utilized the alga as a carbon source. The bacteria thus seem much more important than the fungus for normal growth of the Ascophyllum plant.
INTERACTIONS BETWEEN PULSED NUTRIENT SUPPLIES AND A PHOTOCYCLE AFFECT PHYTOPLANKTON COMPETITION FOR LIMITING NUTRIENTS IN LONG‐TERM CULTURE1
Authors: Brzezinski Mark A. , Nelson David M. 
Published: March 2008

ABSTRACT The influence of periodic nutrient supplies and a photocycle on phytoplankton competition for limiting nutrients was examined using the diatoms Thalassiosira rotula Meunier (clone 411) and Chaetoceros sp. cf. vixvisibilis Schiller (clone 847). Chaetoceros sp. cf. vixvisibilis displaced T. rotula from ammonium‐limited cultures under constant light irrespective of whether ammonium was supplied continuously, in 6 pulses.day−1 or in a single daily pulse. In contrast, the species coexisted under the 14:10 h LD photocycle under either continuous or pulsed ammonium supplies with the relative abundance of C. sp. cf. vixvisibilis increasing as the interval between ammonium additions lengthened. Coexistence was not observed with either silicic acid or nitrate limitation. Chaetoceros sp. cf. vixvisibilis displaced T. rotula from both nitrate‐ and silicic acid‐limited chemostat cultures and from semi‐continuous cultures grown under the same photoperiod that produced coexistence with a daily pulse of ammonium.The presence of a photocycle was both necessary and sufficient to permit coexistence with ammonium limitation. Under continuous ammonium supply the photocycle may have induced a temporal separation of ammonium uptake between species, permitting sharing of the limiting nutrient and coexistence. In contrast, the species were shown to be in direct competition for the daily ammonium pulse. A competition model suggested that coexistence in this case arose from a balance between the species’ammonium uptake rates and their nitrogen demands for steady‐state growth induced by the photocycle. The results indicate that variations in nutrient supply rates may contribute to the coexistence of phytoplankton species in the sea, but that the identity of the limiting nutrient and the influence of variations in other non‐limiting resources play important roles in affecting the outcome of nutrient competition among planktonic algae.
ULTRASTRUCTURE AND ECOLOGY OF AUREOCOCCUS ANOPHAGEFERENS GEN. ET SP. NOV. (CHRYSOPHYCEAE): THE DOMINANT PICOPLANKTER DURING A BLOOM IN NARRAGANSETT BAY, RHODE ISLAND, SUMMER 19851
Authors: Sieburth John McN. , Johnson Paul W. , Hargraves Paul E. 
Published: March 2008

ABSTRACTObservations of a marked cessation of feeding in filter feeding animals maintained in flowing Narragansett Bay seawater in June 1985 drew our attention to a bloom of a golden alga 2 μm in diameter at unprecedented populations of 109 cells. L−1. This picoplankter lacked morphological features useful in discriminating it from other similar sized forms with either phase contrast or epifluorescence light microscopy. Natural populations of picoplankton, obtained from the height of the bloom until its decline, were examined in thin section with transmission electron microscopy. A cell with a single chloroplast, nucleus, and mitochondrion and an unusual exocellular polysaccharide‐like layer was apparently the bloom alga. The ultrastructure of this alga is consistent with that of the Chrysophyceae, and a new genus and species, Aureococcus anophagefferens is described.Attempts to grow this previously unrecognized picoplanktonic alga as an obligate phototroph failed and only yielded cultures of other previously described picoalgae. Facultative and obligate phagotrophic protists with ingested cells of Aureococcus were only observed as the bloom waned and minute diatoms became common. Cells of A. anophagefferens with virus particles typical for picoalgae occurred throughout the bloom. Populations of the usually dominant photosynthetic picoplankter, the cyanobacterium Synechococcus Nägeli, were depressed during the bloom. This could be due in part to selective grazing on Synechococcus rather than Aureococcus by elevated populations of Calycomonas ovalis Wulff which accompanied the algal bloom.
Improving the Capture of Fall Events in Hospitals: Combining a Service for Evaluating Inpatient Falls with an Incident Report System
Authors: Shorr Ronald I. , Mion Lorraine C. , Chandler A. Michelle , Rosenblatt Linda C. , Lynch Debra , Kessler Lori A. 
Published: March 2008

OBJECTIVES: To determine the utility of a fall evaluation service to improve the ascertainment of falls in acute care.DESIGN: Six‐month observational study.SETTING: Sixteen adult nursing units (349 beds) in an urban, academically affiliated, community hospital.PARTICIPANTS: Patients admitted to the study units during the study period.INTERVENTION: Nursing staff identifying falls were instructed to notify, using a pager, a trained nurse “fall evaluator.” Fall evaluators provided 24‐hour‐per‐day 7‐day‐per‐week coverage throughout the study. Data on patient falls gathered by fall evaluators were compared with falls data obtained through the hospital's incident reporting system.RESULTS: During 51,180 patient‐days of observation, 191 falls were identified according to incident reports (3.73 falls/1,000 patient‐days), whereas the evaluation service identified 228 falls (4.45 falls/1,000 patient‐days). Combining falls reported from both data sources yielded 266 falls (5.20 falls/1,000 patient‐days), a 39% relative rate increase compared with incident reports alone (P<.001). For falls with injury, combining data from both sources yielded 79 falls (1.54 injurious falls/1,000 patient‐days), compared with 57 falls (1.11 injurious falls/1,000 patient‐days) filed in incident reports—a 28% increase (P=.06). In the 16 nursing units, the relative percentage increase of captured fall events using the combined data sources versus the incident reporting system alone ranged from 13% to 125%.CONCLUSION: Incident reports significantly underestimate both injurious and noninjurious falls in acute care settings and should not be used as the sole source of data for research or quality improvement initiatives.
Patient‐Controlled Analgesia in Chronic Pain Patients: Experience with a New Device Designed to be Used with Implanted Programable Pumps
Authors: Ilias Wilfried , Le Polain Bernard , Buchser Eric , Demartini Laura ,   the oPTiMa study group
Published: March 2008

▪ Abstract Background:  Intrathecal drug delivery using implantable pumps is an effective method to control stable chronic pain. However, the appropriate alleviation of unpredictable pain fluctuations remains challenging. A possible solution is the use of patient‐controlled analgesia (PCA) by means of a specific device—the personal therapy manager (PTM)—designed to be used with implanted programable pumps.Methods:  A multicenter (n = 17), open‐label registry recording 168 patients suffering from chronic pain with unsatisfactory control of pain episodes was initiated. While 79 patients (47%) (group A) already carried an implanted pump at enrollment, all other patients were implanted after being registered in the study (group B). Parameters assessed included pain relief (visual analog score, VAS), quality of life (EQ‐5D), patient and physician satisfaction, medication use, PTM programming parameters and adverse events. Final follow‐up was at 12 months.Results:  At 12 months, there was a significant reduction (29%) of the overall average VAS compared with baseline (P < 0.01) in patients with newly implanted devices (group B). All patients tended to decrease the concomitant pain medication and the quality of life tended to improve (10% on the EQ‐5D scale). In total, 85% of patients were satisfied with the PTM. No serious adverse events related to the use of the PTM device were observed.Conclusions:  Patient‐controlled analgesia using a PTM with a programable, implantable pump system is an effective therapy for the treatment of chronic pain and allows patients to feel that they have more control over unpredictable pain fluctuations. ▪
Price Momentum and Idiosyncratic Volatility
Authors: Arena Matteo P. , Haggard K. Stephen , Yan Xuemin (Sterling) 
Published: March 2008

AbstractWe find that returns to momentum investing are higher among high idiosyncratic volatility (IVol) stocks, especially high IVol losers. Higher IVol stocks also experience quicker and larger reversals. The findings are consistent with momentum profits being attributable to underreaction to firm‐specific information and with IVol limiting arbitrage of the momentum effect. We also find a positive time‐series relation between momentum returns and aggregate IVol. Given the long‐term rise in IVol, this result helps explain the persistence of momentum profits since Jegadeesh and Titman's (1993) study.
Price Discovery and Liquidity in Basket Securities
Authors: Henker Thomas , Martens Martin 
Published: March 2008

AbstractBasket securities enable investors to purchase a broad portfolio of securities in a single transaction. We examine the link between HOLDRS, a basket security comprising stocks from an industry or sector, and the underlying stocks. We find that the price of the portfolio of underlying securities leads and is more informative than the basket price. Our results are contrary to the findings of empirical studies that use futures, which are basket securities with features less like those of the underlying equities. Our findings suggest uninformed investors can minimize adverse selection costs by trading basket securities rather than the underlying stocks.
Information Asymmetry and Corporate Investment Decisions: A Dynamic Approach
Authors: Tsai Shih‐Chuan 
Published: March 2008

AbstractThis paper develops a dynamic model of the financing and operating decisions of firms in the presence of information asymmetry. When the value of growth opportunities is not fully recognized, securities are undervalued, thus influencing the financing and investment decisions. The agency‐based underinvestment problem is re‐examined under information asymmetry. For firms with greater growth opportunities, the investment distortion resulting from information asymmetry is especially significant. Information asymmetry also increases the expected bankruptcy cost. The cost of information asymmetry in terms of both the firm value and the information spread under the optimal capital structure could be substantial.