bluuebunny/crossref_metadata_2025_split huggingface dataset:
Multivariate statistics applied to phytoplankton data from two Gulf Stream warm core rings1
Authors: Gould, Jr. R. W. , Balmori E. R. , Fryxell G. A. 
Published: April 2010

Multivariate statistical techniques were used on data from two cruises to Gulf Stream warm core rings to reveal patterns and relationships between phytoplankton species abundance and environmental parameters. Principal component analysis (PCA) was performed on each cruise separately and on the combined data to help delineate groups of stations, depths, and species. A ring center station with high numbers of diatoms and a Slope Water station formed separate groups. Deep samples from all the stations grouped together. We consistently observed strong similarities in phytoplankton abundance and species composition between fall samples from the two rings. Inverse analysis was performed using presence or absence data, and the values of the first three principal components were then used in a cluster analysis to determine species co‐occurrences. This analysis resulted in separate groupings of a large number of diatom species found at the center of the rings, of deep species, and of the most abundant and the most frequently observed taxa.Simple correlations, multiple regressions, and canonical correlations were performed with the phytoplankton log abundance data and the environmental data. The canonical coefficients and correlations suggest that high numbers of dinoflagellates and other algae are associated with lower salinity in the Slope Water and at the ring edge, and that higher temperatures and low values of silica (dissolved) are reflected in higher numbers of diatoms and coccolithophorids at ring center.
Wind‐induced internal seiches in Lake Zurich observed and modeled1
Authors: Horn W. , Mortimer C.H. , Schwab D.J. 
Published: April 2010

During August and September 1978, 31 current meters and 120 temperature sensors were deployed to record every 10 or 20 min at various depths at 12 moorings (with wind speed and direction at three moorings) in Lake Zurich. We explore here the baroclinic (internal seiche) response to wind impulses, observed as fluctuations in isotherm depth and current speeds. Those fluctuations and their energy spectra are compared with the predictions of two models fitted to basin topography and to the observed average thermal structure: a two‐layered variable‐depth (TVD) model developed by D. J. Schwab, fitted to basin topography and incorporating a two‐dimensional horizontal grid, and C. H. Mortimer’s two‐layered modification of a simpler procedure originally developed for surface seiche calculations by A. Defant.The dominant responses to wind impulses were internal seiches of the first longitudinal mode (average period 44 h). Weaker signals from the second (24 h) and third (17 h) modes were also seen in spectra of temperature and current fluctuations. The models displayed patterns of thermocline displacement and current which, in periodicity and structure, were closely similar to those observed. Predictions of the Defant model were less precise, particularly for current.Founded on linear theory and neglecting the effects of rotation, the models were unable to reproduce two features occasionally seen in the lake motions: clockwise or anticlockwise rotation of current direction; and internal surges arising when storms induced large‐amplitude downstrokes of the thermocline at one basin end or the other. The lake’s internal response was principally dependent on the timing, strength, and duration of the wind impulse, relative to and interacting with internal seiche motions already in progress.
Currents in Lake Geneva1
Authors: Bohle‐Carbonell M. 
Published: April 2010

The first synoptic measurements of currents and temperatures in Lake Geneva and the wind field on its shoreline have been analyzed to derive mean characteristics of the internal motions. The observations cover the periods from October to March of 1981/1982, 1982/1983, and 1983/ 1984.The lake responds to a very inhomogeneous diurnal and gradient wind field with high‐energy, statistically nonstationary fluctuating currents superimposed on a weak mean state. Current fluctuations of periods between 24 and 12 h appear to propagate cyclonically. Clockwise‐turning current vectors, mainly at near‐inertial frequencies, and a tendency to high energy at low frequencies at nearshore locations are found. Only a portion of the observed details can be explained by features of gravity waves modified by rotation.
Phosphorus transfer from sediments by Myriophyllum spicatum1
Authors: Smith Craig S. , Adams Michael S. 
Published: April 2010

The uptake of phosphorus, the biomass, and the standing P stock were measured over the course of a year in roots and shoots of the Eurasian watermilfoil, Myriophyllum spicatum, from Lake Wingra, Wisconsin. The resulting data were used to estimate the relative contributions of root and shoot uptake to the phosphorus economy of the plant and to examine the role of the plant in moving phosphorus between sediment and water.The total yearly uptake of P by a square meter of Myriophyllum was 3.0 g P m−2. Root uptake accounted for 2.2 g, shoot uptake only 0.8 g. The rate of P release from healthy shoots was insignificant, but about 2.8 g P m−2 yr−1 was lost due to shoot turnover.Since most of the P uptake is by the roots and much of the plant P is transferred to and lost by the shoots, Myriophyllum is a potentially important vector in the movement of P from the sediments to the water. The net transfer of P from the sediments to shoots of Myriophyllum in Lake Wingra is about 2.0 g P m−2 yr−1. Release of this P during decay makes Myriophyllum an important source of P for pelagic phytoplankton and can explain much of the previously reported P export from the littoral zone of Lake Wingra.
The theory of secondary production calculations for continuously reproducing populations
Authors: Kimmerer W. J. 
Published: April 2010

Definitions and mathematical expressions currently used to calculate secondary production are based on the observation of development in cohorts. Most populations of marine zooplankton and many benthic populations do not meet the strict conditions necessary for measurement of growth and mortality in cohorts, and application of the mathematics used in cohort methods to such populations can lead to errors. A better approach is to assume approximate steady state and to determine integrated production (IP) over a time period from observations of the instantaneous production rate, PR.The determination of IP consists of two steps: measurement of PR, usually by a direct method, and integration. The value of IP determined from PR over a given time interval depends on assumptions about the trajectory of PR between samples. I use several simple models to demonstrate that mortality need not be measured and that IP can be determined from sample data on PR. The best estimate of IP is a simple sum of PR values multiplied by appropriate time intervals.
Measurement of free cupric ion concentration in seawater by a ligand competition technique involving copper sorption onto C18 SEP‐PAK cartridges1
Authors: Sunda William G. , Hanson Alfred K. 
Published: April 2010

Knowledge of ion speciation and free ion concentrations is important in predicting the biological availability and geochemical behavior of trace metals. Here we describe a new technique for measuring free cupric ion concentration in seawater based on sorption of copper onto SEP‐PAK C18 cartridges and internal free cupric ion calibration. Calibration was achieved by adding cupric ion buffers, consisting of copper and excess concentrations of synthetic chelator, ethylenediaminetetraacetic acid (EDTA). EDTA competes with natural organic ligands for copper complexation, but its copper chelate is not retained by the C18 cartridges. This latter property allows EDTA to be used for free cupric ion calibration.Titrations in seawater utilizing the new technique revealed that copper was highly complexed. Free cupric ion concentrations in three samples of seawater from lower Narragansett Bay, Rhode Island, and one from off the coast of Peru were measured to be 10−12.3, 10−12.0, 10 12.1, and 10−11.5 M at total dissolved copper concentrations of 26.7, 16.5, 19.4, and 3.7 nM. From these values and from computed and experimental values for inorganic complexation, we compute that only 0.03–2% of the dissolved copper can be accounted for as inorganic species (Cu2+, CuCO3, CuOH +, etc.). The remainder, 99.97–98%, appears to be organically complexed. These results are in general agreement with several other recent studies, using several techniques, of copper complexation in seawater.
Tritium hydrologic studies in four closed‐basin lakes in the Great Basin, U.S.A.1
Authors: Herczeg Andrew L. , Imboden Dieter M. 
Published: April 2010

Four closed‐basin lakes in the Great Basin (Lake Abert, Oregon; Mono Lake, California; Pyramid Lake and Walker Lake, Nevada) were analyzed for tritium (3H) in water samples collected in 1969, 1976, 1980, and 1981. In each case the tritium concentration increased to a maximum in the mid‐to late 1960s in response to fallout produced by nuclear weapons testing and then slowly decreased soon after the 1966 moratorium. The highest level attained was a function of the water residence time of the lake (i.e. shorter residence time corresponding to higher maximum tritium concentration), and the rate of decrease was slowest for lakes with longer water residence times. The residence time of tritium is less than the water residence time and depends strongly on the evaporative exchange of tritium with the atmosphere.A tritium hydrologic model was constructed in an attempt to constrain hydrologic properties such as evaporation rate, relative humidity, and the degree of homogeneity of the water column with respect to tritium. If evaporation rates determined from hydrologic balance are within 20% of the true rates, then the tritium input must be between 50 and 90% enriched over that calculated from data on tritium fallout in Portland rain. This enrichment is considerably reduced if the surface waters are on the average depleted by about 10% in tritium relative to the whole lake. Calculated mean relative humidities lie between 0.45 (Mono Lake) and 0.25 (Walker Lake). Calculated exchange velocities in the gas phase are between 17 and 27 m h−1, which corresponds to a mean wind speed of about 4 m s−1.
Field measurements of air‐sea CO2 exchange1
Authors: Frankignoulle M. 
Published: April 2010

The direction and magnitude of air‐sea exchanges depend on the difference of gas partial pressure (ΔP) between phases and on a gas exchange coefficient (K). In this work, field air‐sea CO2 exchange and ΔPco2 have been measured simultaneously to study the in situ relations between parameters. Experiments have been carried out at three sites: the Bay of Calvi (Corsica), the Ligurian Sea, and the North Sea. Flux measurements were made with a direct chamber method to detect invasion or evasion of gas.Due to its bed of seagrass (P(Posidonia), the Bay of Calvi is the site of regular, daily, and yearly variations of surface CO2 content. Daily variations are often too small to overcome the variation of K and to find a correlation between hourly measured fluxes and daily changes of ΔP. The yearly variation of Pco2 in surface water (from 300 ppm in winter to 900 ppm in summer) has however permitted derivation of a linear relationship between mean fluxes and ΔP that fits well with fluxes measured at the two other sites under similar meteorological conditions and thus with nearly the same K. Calculated coefficients range between 10−5 and 4 × 10−5 m s−1 and so agree well with those determined with radiotracers or in wind tunnels.Measurements in the North Sea under different meteorological conditions show the influence of wind speed and sea state on exchanges measured by the in situ methodology used and allow the results to be compared with those obtained by others in wind tunnels.
Growth and phosphorus status of limnetic phytoplankton and bacteria
Authors: Vadstein Olav , Jensen Arne , Olsen Yngvar , Reinertsen Helge 
Published: April 2010

The phosphorus status [total phosphorus (P), surplus P, and alkaline phosphatase activity (APA)] of phytoplankton and bacteria were followed in a eutrophic Norwegian lake. On average 36% (range 20–60) of the particulate P and 57% (range 10–100) of the surplus P were bound by bacteria. The P : C ratio of phytoplankton and bacteria varied between 2.5 and 55 (median 5.1) and 34 and 360 (median 89) µg P (mg C)−1, indicating that bacteria have a substantially higher P requirement than do phytoplankton.The inverse relation found between surplus P : C and APA : C ratios during a Microcystis aeruginosa bloom and the positive relation between P : C ratio and growth rate of the cryptophyte‐dominated community in summer indicate that the phytoplankton were P limited during most of the ice‐free period. This is supported by the fact that the data from the cryptophyte‐dominated community could be described by the Droop model for nutrient‐limited growth. For the bacteria a positive relation was found between growth rate and cellular P (i.e. the P : C and the surplus P : C ratios), as predicted by the Droop model. Although the bacteria obviously were P subsaturated, it cannot be concluded that they were P limited since C may have been supplied at an even lower rate. Because of their high P requirements the bacteria acted as consumers of inorganic P and their net consumption of P was four times higher than that of the phytoplankton.
The effect of pH on iron and manganese uptake by a green alga
Authors: Schenck R. C. , Tessier A. , Campbell P. G. C. 
Published: April 2010

Experiments were conducted with 54Mn and 59Fe in buffered synthetic solutions to determine the short‐term uptake of manganese and iron by the green alga Chlamydomonas variabilis as a function of pH and metal concentration. Over the pH range 7 to 5, the adsorption of Fe(II) and Mn(II) onto the cell surface was independent of pH, but the fluxes of metals into the cells decreased 2–2.5 times for each unit decrease in pH. Thus increasing acidity decreased metal uptake and, by inference, the effects of the metal on the cell.We also compared the uptake of Fe(II) and Fe(III) at the same external concentration (0.1 µM), under conditions where all the metal was dissolved (pH 5). The uptake rates were nearly identical, even though the ratio [Fe2+]:[Fe3+] was ∼106. The measured fluxes of Fe(III) into an algal cell were l04 times greater than the calculated diffusive flux of Fe3+ to the cell surface. The results indicate that the uptake of Fe(III) involves transport to the cell surface of hydroxy‐Fe(III) species that are in rapid protolytic equilibrium with each other and with the free hydrated ferric iron.
Reproductive costs and hydrodynamic benefits of chemically induced defenses in Keratella testudo
Authors: Stemberger Richard S. 
Published: April 2010

Food concentration differentially affected reproductive rates and hydrodynamic characteristics of spined and unspined phenotypes of the polymorphic rotifer Keratella testudo. The intrinsic rate of population growth (0.15 d−1) of the predator‐induced phenotype was less than half that of the unspined morph (0.39 d 1) at high food concentrations. The spined phenotype had considerably lower survivorship and fecundity than the unspined one after the first 3–4 d of life. At low food concentrations population growth rates were not statistically different; their age‐specific survivorship and fecundity schedules were nearly identical.Sinking rates and swimming speeds of both morphs were significantly and negatively correlated (r = −0.96). Attached eggs increased sinking rates regardless of food level. Changes in sinking rate occurred within 6 h of transferring animals acclimated to high food to conditions of starvation. Food concentration greatly influenced the center of gravity of the morphs and, consequently, affected orientation during sinking. They sank posterior‐end downward in high food conditions and in a more horizontal plane in low food treatments. The latter position should give maximal resistance to sinking, consistent with the slower sinking rates in low food conditions.The specific gravity of both phenotypes increased in high food concentrations—the spined morph being consistently higher than the unspined one at both food levels. Lorica densities of both phenotypes were >1.3 g cm−3 suggesting that this structure may contribute significantly to body mass and may be energetically costly to produce or maintain. The coefficient of form resistance (the ratio of the sinking rate of the rotifer to the sinking rate of a sphere having an equivalent volume and specific gravity) was ∼27% higher in the spined phenotype than in the unspined one in low food treatments. Greater form resistance may provide an energetic benefit which offsets the costs associated with the spined phenotype.
Organic matter sources to the water column and surficial sediments of a marine bay
Authors: Hedges John I. , Clark Wayne A. , Come Gregory L. 
Published: April 2010

Sediment trap and net plankton samples were collected monthly for a year at three depths in a marine bay (Dabob Bay, Washington). These materials and subsamples from a sediment box core were analyzed for lignin oxidation products as well as elemental and stable carbon isotope compositions. The sediment core was compositionally uniform over its entire 50‐cm length. The elemental and lignin compositions of the sediment trap and core samples indicate nitrogen‐rich (atomic C : N ≅ 7.5) plankton‐derived organic matter mixed with vascular plant debris.At most, vascular plant debris accounts for 10% (nonwinter months) to 35% (winter months) of the total organic carbon in the upper water column (30 m) sediment trap samples and consists predominantly of gymnosperm wood along with some nonwoody gymnosperm tissues and angiosperm woods. Bulk land‐derived organic matter in Dabob Bay contains a maximum of 50% vascular plant debris and comprises an average of one‐third of the total organic carbon in the sediment trap samples and two‐thirds of the total organic carbon in the underlying sediments. Lignin in the sediment trap and core samples shows evidence (from elevated vanillic acid:vanillin ratios) of white‐rot fungal degradation before (but not after) introduction to the water column at the study site. Vascular plant debris introduced to the bay has already lost almost half of its initial bulk polysaccharide. Glucose yields are particularly low whereas rhamnose and fucose are obtained in excess of expected yields and must have additional sources.Lignin and neutral sugars together account for <20% of the total organic carbon in the sediment trap and core samples. Overall, the sediments of Dabob Bay compositionally resemble the gymnosperm wood‐rich particulate material introduced to the overlying water column during winter and poorly record the input of plankton and other types of vascular plant debris during nonwinter months.
Precancerous Lesions of Oral Cavity
Authors: Pawar Uday , Souza Chris de 
Published: April 2010

AbstractThe term premalignant (precancerous) lesion has been replaced by the term potentially malignant lesion. Such lesions have as their cause, tobacco use, exposure to the human papilloma virus and the chewing of the betel nut. These substances contain carcinogens. The mucosa of the oral cavity is normally quite robust. Exposure to these substances can cause it to undergo change. These changes are usually initiated as a leukoplakic patch. While some leucoplakic patches recover and resolve, some progress into invasive squamous cell carcinoma. Oral submucus fibrosis is another such potentially malignant condition caused by the abuse of betel nut.
Evaluation of Applicability of Standard Growth Curves to Indian Women by Fetal Biometry
Authors: Acharya Ashini , Acharya Prashant 
Published: April 2010

ABSTRACT

Objective
To verify the applicability of standard fetal growth curves proposed for western populations to an Indian population.

Method
Thirty patients were included and ultrasound scans were performed on Indian pregnant women to measure fetal growth parameters of biparietal diameter, head circumference, abdominal circumference and femur length for every weekly interval from 14 to 40 weeks. Twenty-five hundred women had ultrasonic measurements of fetal BPD, HC, AC and FL between 12 to 42 weeks of pregnancy were also included in study for confirming the growth parameters and plotting of Growth curves. The data were compared with the commonly recommended standards of Hadlock, Campbell, Jeanty and Chitty.

Results
First and second trimester biometry findings are comparable to western charts but none of the standard charts agreed with the data in the present study particularly in third trimester.

Conclusion
Since most parameters of the standard growth curves developed in the west are not applicable for assessing the intrauterine growth of Indian babies we have developed growth curves for the Indian population to prevent over-diagnosis of intrauterine growth retardation and correct prediction of fetal age in Indian population.
Is Pneumoperitoneum Really Required before Primary Trocar Insertion in Laparoscopy?
Authors: Kapur Krishan 
Published: April 2010

ABSTRACTObjectivesTraditionally a Veress needle is used to create a pneumoperitoneum before entering the primary trocar/cannula for laparoscopy. Insufflation of gas into the peritoneal cavity with the Veress needle is not without its problems. To do away with these problems the technique of direct trocar access was started.Materials and methodsBetween 01 Jan 2003 and 31 Dec 2008— 2958 laparoscopic procedures were carried out in a Government hospital. 345 patients out of these had undergone previous laparotomies. In all cases direct trocar insertion without pneumoperitoneum was done.ResultIn this series there were no complications except in one case there was mesenteric injury with bleeding which required a laparotomy. There were no failed laparoscopies.ConclusionWe have found that direct trocar insertion before creating pneumoperitoneum is a safe and effective method for laparoscopic access and offers advantages over the conventional access modality of using a Veress needle for pneumoperitoneum.
Challenges for Utilization of Antenatal and Delivery Care Services in Urban Setting of Bangladesh
Authors: Tasnim Saria , Rahman Aminur , Chowdhury Sameena , Shahabuddin AKM 
Published: April 2010

ABSTRACT
In most developing countries like Bangladesh the health care facilities are not optimally available and usually are underutilized. The study explored the perception of urban poor women regarding pregnancy, childbirth and obstetric care services of the health centers and factors for utilization and/or nonutilization of such services.
Focus group discussions were conducted among mothers with a child aged one year or below, their husband and elder female members of the family between May and June 2001 in selected geographical clusters of Dhaka city.
It was revealed that women regard pregnancy and child birth as a natural process that needs no medical care unless some dire emergency arises. Taking tetanus toxoid during pregnancy was equated with availing antenatal care. Traditional birth attendant (Dai) was more preferable as birth attendant as they are available at home, like a kin to them, and affordable. Reason for not availing the services were high cost, nonavailability of drugs, hassles to get free bed, ignorance about the complications, negative cultural norm, rude behavior of health care providers, fear of cesarian section and an unfamiliar environment in the hospitals. Utilization of maternity care services can be improved through a combined effort of increasing awareness to avail skilled care and made the services more accessible and with better quality.