bluuebunny/crossref_metadata_2025 huggingface dataset:
Submersible‐operated porewater sampler for permeable sediments
Authors: Sansone Francis J. , Spalding Heather L. , Smith Celia M.
Published: April 2011

A sampler was developed to collect porewater from permeable (sandy) sediments during manned‐submersible operations. The sampler uses vacuum (or atmospheric‐pressure) reservoirs to draw porewater into a sediment probe and then into inline sample loops. The sampler is relatively inexpensive, easy to construct, and self‐contained, operating without an external power supply. The sample‐loop/reservoir system (without the probe) can also be used to sample wells or other apparatus installed in or on the seafloor, and would be comparatively easy to automate. In addition, the sampler should be adaptable to SCUBA diving operations (including rebreather or mixed‐gas diving). The sampler was used with Pisces submersibles to determine dissolved chemical profiles in sandy sediments inside and outside the extensive deepwater meadows of macroalgae offshore of the main Hawaiian Islands. The sampler collected porewater (to 25 cm sediment depth) from sites at 40‐200 m water depth. Porewater inorganic nutrient concentrations were comparable with those in nearshore permeable sediments, but showed distinct differences between a vegetated and an unvegetated site.
In situ ichthyoplankton imaging system (ISIIS): system design and preliminary results
Authors: Cowen Robert K. , Guigand Cedric M.
Published: April 2011

Over the last two decades, there has been an accelerating advancement of acoustic and optical plankton samplers, opening many opportunities for fine‐scale studies of plankton distribution. To date, however, the imaging systems have been limited in the volume of water being sampled, thereby restricting their utility to quantifying highly abundant, small zooplankton like copepods, but not relatively rarer, larger ichthyo‐ and other meso‐zooplankton (e.g., larval decapods, salps, pteropods, ctenophores, etc.). Here we describe an imaging system, In situ ichthyoplankton imaging system (ISIIS), that is capable of In situ (i.e., noninvasive) sampling of sufficiently large volumes of water at very high resolution, allowing quantitative measurement of these rare plankton, while at the same time also recording the smaller more abundant taxa. Capitalizing on state‐of‐the‐art digital line scan cameras and high‐throughput computer data transfer and storage, combined with shadow photographic lighting techniques, we have designed and built a towed system capable of imaging at 68‐micron pixel resolution, yet with up to a 20‐cm depth of field (with a 14‐cm field of view). This system is coupled with various environmental sensors (e.g., CTD, fluorometer), enabling the evaluation of fine‐scale, taxon‐specific distributions in relation to environmental conditions. Field testing demonstrated high‐resolution imagery of plankters, while quantitatively imaging >70 L s−1 continuously for a 78‐min trial.
Gas exchange system for extended in situ benthic chamber flux measurements under controlled oxygen conditions: First application—Sea bed methane emission measurements at Captain Arutyunov mud volcano
Authors: Sommer Stefan , Türk Matthias , Kriwanek Sonja , Pfannkuche Olaf
Published: April 2011

Mass transfer rates of many gases, nutrients, and trace metals across the sediment water interface are dependent on environmental oxygen conditions. In this article, a novel gas exchange system for extended in situ flux and respiration measurements in benthic chambers under defined oxygen conditions is described. Integrated within a GEOMAR modular lander, the gas exchange system was used to perform in situ measurements of the total oxygen uptake and sea bed methane emission rates under constant oxygen conditions at Captain Arutyunov mud volcano (Gulf of Cadiz) in a water depth of 1320 m. During two separate lander deployments, the oxygen concentration within the benthic chambers was kept constant for 37 and 47 h, respectively. Under these conditions total oxygen uptake rate remained constant at 4.4 and 13.2 mmol m−2 d−1. Seabed methane emission was low, in the range 0 to 0.2 mmol m−2 d−1. The system is suited for prolonged (days) in situ flux determinations under natural background oxygen conditions and offers a wide range of experimental applications.
A simple and efficient method for the solid‐phase extraction of dissolved organic matter (SPE‐DOM) from seawater
Authors: Dittmar Thorsten , Koch Boris , Hertkorn Norbert , Kattner Gerhard
Published: April 2011

A simple protocol is presented for the solid‐phase extraction of dissolved organic matter (SPE‐DOM) from seawater using commercially prepacked cartridges. The method does not require major instrumentation and can be performed in the field. Modified styrene divinyl benzene polymer type sorbents (Varian PPL and ENV) and sorbents of a silica structure bonded with different hydrocarbon chains (Varian C8, C18, C18OH, and C18EWP) were considered. Except for C18OH, which heavily contaminated the samples, none of the sorbents leached significant amounts of dissolved organic carbon (DOC) or nitrogen (DON). Samples from the North Brazil shelf with strong mixing gradients of terrigenous and marine DOM were used to compare the various sorbents. PPL was the most efficient—on average, 62% of DOC was recovered as salt‐free extracts. C18 was found to be most efficient among the silica‐based sorbents, but it showed only two‐thirds of the extraction efficiency of PPL. As indicated by [1H]NMR, C/N, and δ13C analyses, PPL extracted a more representative proportion of DOM than C18. Therefore, PPL was used for comparative studies in the Gulf of Mexico and Antarctica. From brackish marsh and river waters, 65% and 62% of total DOC, respectively, could be extracted. For purely marine DOM in Antarctica and the deep sea, the extraction efficiency was lower (43% on average). The efficiency of the new method to isolate marine DOM is better than or similar to highly laborious methods. A further advantage is the complete desalination of the sample. The isolation of a major DOM fraction, which is salt‐free, offers many possibilities to further characterize DOM by advanced analytical techniques.
The Land/Ocean Biogeochemical Observatory: A robust networked mooring system for continuously monitoring complex biogeochemical cycles in estuaries
Authors: Jannasch Hans W. , Coletti Luke J. , Johnson Kenneth S. , Fitzwater Stephen E. , Needoba Joseph A. , Plant Joshua N.
Published: April 2011

An ocean observatory that consists of an array of moored sensor platforms, telemetry, and data collection and dissemination software was designed for monitoring the biogeochemistry and physical dynamics of coastal and estuarine ecosystems. The Land‐Ocean Biogeochemical Observatory (LOBO) consists of robust moorings that can withstand tidal currents and weather. The moorings are highly configurable, can be deployed in waters as shallow as 0.5 m, are relatively easy to maintain, and accommodate a complete array of standard and novel sensors. The sensors communicate with an on‐board controller which relays data to shore in near‐real time. Up to five LOBO moorings have been simultaneously deployed and maintained in Elkhorn Slough, California, since November 2003. Continuous hourly data of biological, chemical, and physical properties are relayed to shore, processed, and disseminated to users through a web interface in near‐real time. This article describes the design, implementation, and functionality of the LOBO monitoring system.
Inhibiting diatom motility: a new tool for the study of the photophysiology of intertidal microphytobenthic biofilms
Authors: Cartaxana Paulo , Serôdio João
Published: April 2011

The study of the photophysiology of intertidal microphytobenthos biofilms has been hampered by the confounding effects of vertical migration by motile microalgae. The present work introduces a methodology to obtain undisturbed nonmigratory biofilms, based on the diatom motility inhibitor latrunculin A (Lat A). Application of Lat A to intact sediments prevented light‐induced vertical migration while not affecting the biofilm photosynthetic activity or disrupting the photic zone microenvironment. The inhibition of microalgal migration maintained the surface microalgae biomass despite exposure to stimuli that induced large migratory responses in noninhibited samples, including supersaturating irradiances or darkness. The characterization of the photophysiological responses of undisturbed biofilms without the interference of changes in surface biomass was illustrated by addressing two questions that are not possible to study on migratory biofilms with the existing methods: (i) the construction of light‐response curves of steady‐state photosynthetic activity, commonly used to characterize the photoacclimation status of photoautotrophs, and (ii) the characterization of the induction and relaxation kinetics of nonphotochemical quenching of in vivo fluorescence, required for the study of photoprotective processes or photoinhibition.
A novel gel‐based technique for the high resolution, two‐dimensional determination of iron (II) and sulfide in sediment
Authors: Robertson David , Teasdale Peter R. , Welsh David T.
Published: April 2011

Many coastal marine sediments display highly heterogeneous biogeochemistry due to complex biological and chemical interactions. Existing measurement techniques are limited in their ability to characterize the distributions of reduced species at high resolution in two dimensions. To obtain more detailed information than existing methods, a novel technique for the simultaneous high‐resolution (1 mm), two‐dimensional determination of porewater iron (II), and sulfide using a gel‐based diffusive sampler was developed. A diffusive equilibration in a thin‐film (DET) hydrogel was colorized by Ferrozine reagent, imaged electronically, and analyzed using computer imaging densitometry. With the selected gel parameters, the method detection limit for iron (II) was 0.6 µmol L−1, with an upper calibration limit of 500 µmol L−1 and relative standard deviations below 10% across the calibration range. This method was integrated into the existing diffusive gradient in a thin film (DGT) method for sulfide determination. Field deployments of a prototype probe, which measured an area of 170 × 80 mm, in estuarine sediment revealed complex, fine‐scale, interlocking zones of iron (II) and sulfide. This confirms the need to assess more than a single dimension, at appropriately high resolution, to obtain an accurate representation of sediment geochemistry. Advantages of the technique include its high spatial resolution, minimal sample handling, flexible probe size, simultaneous measurement of two analytes at exactly the same location in the sediment, and the rapid production of data without requiring expensive analytical instrumentation.
Extending the cell digestion assay to quantify dead phytoplankton cells in cold and polar waters
Authors: Llabrés Moira , Agustí Susana
Published: April 2011

The cell digestion assay (CDA) is an effective method to quantify living/dead cells in complex natural phytoplankton communities. The CDA involves the incubation of fresh samples at 35°C for 45 min for the enzymatic digestion of dead cells. The relatively high incubation temperature has raised concerns as to the applicability of the CDA to phytoplankton samples from polar and cold environments. Here, we examined the applicability of the CDA to phytoplankton growing at low temperatures and developed modifications and recommendations to reliably use the CDA in polar and cold‐water communities. We carried out different tests with polar and temperate phytoplankton species, and with natural communities from the Arctic Ocean. Increased cell death when applying the standard CDA method was evident in some of the species tested, when compared with results obtained using alternative staining membrane permeability tests. We confirmed that the use of an incubation temperature of 25°C with Arctic communities and cultured species growing at 5°C results in the complete digestion of dead cells and no significant effect on the percentage of living cells. We recommend the use of 25°C as the incubation temperature when applying the CDA to phytoplankton communities inhabiting cold environments.
An inexpensive remotely operated vehicle for underwater studies
Authors: Teece Mark A.
Published: April 2011

Remotely operated vehicles (ROVs) are an increasingly important tool in understanding underwater environments; however, their widespread use has been dampened by high operating costs and accessibility. To address the lack of affordable ROV technology, I have designed, constructed, and tested a ROV that can record real‐time video images for less than $400. With some additional modifications and cost, the ROV can deliver a multiparameter probe to user‐defined locations and collect water samples. The ROV provides high‐quality video images of underwater environments and can be used for video transects of benthic environments. I show that, using an attached multiparameter probe, continuous water quality and chemical parameters can also be recorded. The ROV is made from readily available materials and can easily be built by anyone, and its maintenance costs are low. The ROV is easily maneuvered in depths up to 30 m and is easily deployable by one person. The ROV is small, lightweight, and, as it requires 12V DC power, can easily be transported to remote locations. The low cost and broad capabilities of the ROV will provide aquatic scientists, teachers, and students with a window to visually observe a wide range of underwater environments. The construction and potential applications of this ROV are discussed.
Comparison of a sediment trap and plankton pump for time‐series sampling of larvae near deep‐sea hydrothermal vents
Authors: Beaulieu Stace E. , Mullineaux Lauren S. , Adams Diane K. , Mills Susan W.
Published: April 2011

Studies of larval dispersal and supply are critical to understanding benthic population and community dynamics. A major limitation to these studies in the deep sea has been the restriction of larval sampling to infrequent research cruises. In this study, we investigated the utility of a sediment trap for autonomous, time‐series sampling of larvae near deep‐sea hydrothermal vents. We conducted simultaneous deployments of a time‐series sediment trap and a large‐volume plankton pump in close proximity on the East Pacific Rise (2510‐m depth). Grouped and species‐specific downward fluxes of larvae into the sediment trap were not correlated to larval abundances in pump samples, mean horizontal flow speeds, or mean horizontal larval fluxes. The sediment trap collected a higher ratio of gastropod to polychaete larvae, a lower diversity of gastropod species, and over‐ or undercollected some gastropod species relative to frequencies in pump sampling. These differences between the two sampling methods indicate that larval concentrations in the plankton are not well predicted by fluxes of larvae into the sediment trap. Future studies of deep‐sea larvae should choose a sampling device based on specific research goals. Limited by battery power, a plankton pump in combination with a current meter is useful for estimating horizontal advective fluxes in short‐term (days to weeks) studies of larval dispersal. A sediment trap, selecting for larvae with downward trajectories, is more appropriate for studies of larval supply to the benthos. For some species, a time‐series sediment trap can collect sequential larval samples for long‐term studies (months to years) for correlation to larval settlement and recruitment patterns.
Analytical intercomparison between type I and type II long‐pathlength liquid core waveguides for the measurement of chromophoric dissolved organic matter
Authors: Floge Sheri A. , Hardy Kathleen R. , Boss Emmanuel , Wells Mark L.
Published: April 2011

In the past decade, technological advances in optical sensors have facilitated an increased understanding of the relationship between optical characteristics and biogeochemistry of our oceans. In particular, long‐pathlength liquid core waveguide cells (LCWs) are being used to “map” chromophoric dissolved organic matter (CDOM), as a biogeochemical tracer, in various coastal and open ocean regions. At present, two LCW cell types are used in the study of marine CDOM, and concerns about discrepancies in data collected with the different cell types and problems with baseline offsets have arisen. We conducted a direct comparison of absorption coefficient spectra of a dissolved spectrophotometric standard, molecular weight standard (MWS), and dilution series of natural seawater obtained in type I and type II LCWs to assess data agreement and potential colloid‐mediated biases. Although no statistical difference was observed for the dissolved standard, we found the type I to have a slight bias toward higher absorption coefficient values for MWS 14–150 kDa (within 95% confidence interval) and natural seawater. Seawater CDOM spectral slopes differed significantly between type I and type II LCWs, with a maximum difference in slope of 0.0006 nm−1. Fastidious elimination of microbubbles from the capillary cells greatly reduced baseline offsets and markedly improved CDOM spectral slope precision.
Trapping migrating zooplankton
Authors: Pierson James J , Frost Bruce W. , Thoreson David , Leising Andrew W. , Postel James R. , Nuwer Mikelle
Published: April 2011

We have developed a method to determine if individual zooplankton make short‐duration migrations, on the order of meters to tens of meters in vertical extent, between food‐rich surface water and deeper, food‐poor water. To do this, we developed a zooplankton trapping system, consisting of paired traps to catch zooplankton migrating downward and an inverted ring net to catch zooplankton migrating upward. These two trap systems were deployed simultaneously with the openings at the same depth, to catch zooplankton crossing a particular depth horizon, and samples were immediately sorted to make morphological and physiological measurements of individuals. Initial tests showed that there were differences in the ability to capture upward‐ and downward‐migrating marine zooplankton. In addition, physiological (gut contents) and morphological (prosome length) characteristics of individual copepods differed between those moving in opposite directions. These data support the hypothesis that copepods make repeated nighttime forays between deeper, food‐poor water and the near‐surface, food‐rich waters. This is part of an ongoing study on the variability of this behavior in different conditions and over seasonal cycles, but the method may be applicable to other pelagic environments, to explore various ecological questions.
Evaluating the triplet state photoreactivity of dissolved organic matter isolated by chromatography and ultrafiltration using an alkylphenol probe molecule
Authors: Cawley Kaelin M. , Hakala J. Alexandra , Chin Yu‐Ping
Published: April 2011

The triplet state photochemistry of dissolved organic matter (DOM) isolated by XAD and C‐18 chromatography and tangential flow ultrafiltration (TFUF) was investigated using 2,4,6 trimethylphenol (TMP) as a molecular probe. Water samples were taken from an Arctic seep adjacent the Oksrukuyik River (OKS) on the north slope of Alaska, USA, where DOM is derived primarily from allochthonous material and from a eutrophic midlatitude wetland, Old Woman Creek (OWC), in northern Ohio, USA, where the DOM is formed from both allochthonous and autochthonous precursors. DOM‐mediated TMP photolysis occurred for all samples, but was significantly faster in the OWC isolates. The method used to isolate DOM also influenced TMP photoreactivity, whereby the C‐18 and XAD isolated material were typically more reactive than ultrafiltered DOM. Analysis of the isolates by spectroscopy revealed that the materials isolated by chromatography were relatively enriched in aromatic constituents, while the TFUF fraction had the lowest aromaticity based on molar absorptivity at 280 nm. The fluorescence index values revealed differences between OKS and OWC, but no discernable trends were observed among isolates. This study shows that both the manner in which DOM is isolated and the composition of its precursors will influence its triplet state photoreactivity.
Evaluation of a well‐established sequential phosphorus fractionation technique for use in calcite‐rich lake sediments: identification and prevention of artifacts due to apatite formation
Authors: Hupfer Michael , Zak Dominik , Roβberg Reingard , Herzog Christiane , Pöthig Rosemarie
Published: April 2011

Speciation of particulate phosphorus in soils and aquatic sediments by sequential extraction techniques is commonly used to address both fundamental and applied problems. It has been suggested, however, that sequential extraction techniques can produce misleading results due to the generation of new solid phases during the extraction process. In this study, a well‐established fractionation technique introduced by Psenner et al. (1984) for crystalline sediments was reevaluated in four calcite‐rich lake sediments using a set of additional extraction tests and structural analyses. Extended tests using a sediment artificially enriched with Al and Ca, regarded as model sediment, showed a distinct overestimation of Ca‐bound P (HCl‐TP) and concomitant under‐estimation of metal oxide‐bound P (NaOH‐SRP). The formation of new solid phases during extraction was evident by P addition to the alkaline extract, change of volume‐to‐solid ratio, and variation of extraction time. Examination of the model sediment with infrared and X‐ray spectroscopy demonstrated that Ca‐bound P was not present before the NaOH step. Apatitic structures were detected by IR spectroscopy in the model sediment after NaOH extraction. In contrast, in the three natural calcite‐rich sediments with high HCl‐TP portions, underestimations of NaOH‐SRP were not detected with the standard protocol. Therefore, a modification of the Psenner method does not appear necessary for most conditions. In hardwater lakes, however, especially those restored with Al and Fe salts, a shift from NaOH‐SRP to HCl‐P cannot be excluded. Our study provides helpful tools to identify such artifacts and thus to prevent misinterpretation of fractionation results.
Characterization of phosphorus, calcium, iron, and other elements in organisms at sub‐micron resolution using X‐ray fluorescence spectromicroscopy
Authors: Diaz Julia , Ingall Ellery , Vogt Stefan , de Jonge Martin D. , Paterson David , Rau Christoph , Brandes Jay A.
Published: April 2011

X‐ray spectromicroscopy (combined X‐ray spectroscopy and microscopy) is uniquely capable of determining sub‐micron scale elemental content and chemical speciation in minimally‐prepared particulate samples. The high spatial resolutions achievable with this technique have enabled the close examination of important microscale processes relevant to the cycling of biogeochemically important elements. Here, we demonstrate the value of X‐ray microscopy to environmental and biological research by examining the phosphorus and metal chemistry of complete individual cells from the algal genera Chlamydomonas sp. and Chlorella sp. X‐ray analysis revealed that both genera store substantial intracellular phosphorus as distinct, heterogeneously distributed granules whose X‐ray fluorescence spectra are consistent with that of polyphosphate. Polyphosphate inclusions ranged in size from 0.3‐1.4 µm in diameter and exhibited a nonspecies‐specific average phosphorus concentration of 6.87 ± 1.86 µg cm−2, which was significantly higher than the average concentration of phosphorus measured in the total cell, at 3.14 ± 0.98 µg cm−2 (95% confidence). Polyphosphate was consistently associated with calcium and iron, exhibiting average P:cation molar ratios of 8.31 ± 2.00 and 108 ± 34, respectively (95% confidence). In some cells, polyphosphate was also associated with potassium, zinc, manganese, and titanium. Based on our results, X‐ray spectromicroscopy can provide high‐resolution elemental data on minimally prepared, unsectioned cells that are unattainable through alternative microscopic methods and conventional bulk chemical techniques currently available in many fields of marine chemistry.
Pinnipeds as ocean‐temperature samplers: calibrations, validations, and data quality
Authors: Simmons Samantha E. , Tremblay Yann , Costa Daniel P.
Published: April 2011

Recently marine organisms have emerged as ocean‐sensing platforms, generating data useful to biologists and oceanographers. However, sensor calibrations, performance over time, and effects of behavior and sampling frequency on data quality have not been adequately examined. We performed temperature calibration trials on 36 Wildlife Computers Mk9 time‐depth recorders (stated accuracy 0.1°C ± 0.05°C) versus Rosemount Model 162CE standard platinum resistance thermometer (0.001°C, ± 0.0001°C). Sixty‐four percent of trials were within ± 0.1°C. Subtracting 0.05°C from all calibrations brought this to 83%. Six instruments calibrated before and after deployment on free‐ranging pinnipeds, showed no significant drift in temperature measurements. Mk9 performance was tested against a Seabird© CTD (SBE‐19). Root mean square (rms) difference between CTD and Mk9 temperature was 0.15°C (max. 0.45°C, min. 0.10°C). Applying a 1‐s time‐lag improved the data fit. To assess animal effects on thermal data, Mk9s were deployed on juvenile elephant seals released between CTD casts. Overall rms were within ± 0.1°C. Subsampling of Mk9 data revealed a sampling frequency of 10 s was sufficient to accurately resolve thermal features, e.g., thermocline depth, for these CTD experiments. We present four equations to assess temperature data quality from diving marine animals around the globe carrying different thermistors.
Multiple Enzyme Analyzer (MEA): Steps toward the in situ detection of microbial community ectoenzyme activities
Authors: Jaeger Stephanie A. , Gaas Brian M. , Klinkhammer Gary P. , Ammerman James W.
Published: April 2011

The capability of microbes to use certain compounds can be examined by measuring ectoenzyme activities. These enzymes are found on or near the surface of a cell and hydrolyze large molecules to a smaller size, serving as a key first step in organic matter use. A new instrument is under development for high‐resolution measurements of in situ ectoenzyme activity intended for use at coastal ocean observatories. This system, the Multiple Enzyme Analyzer (MEA), measures up to four different enzyme activities in flow‐through channels by quantifying the fluorescence increase associated with substrate hydrolysis over time. A description of the MEA design, a comparison of MEA performance with laboratory fluorometers, an exploration of instrument and reagent stability, and results from a preliminary experiment in a seawater tank are addressed. These results demonstrate that the MEA is capable of detecting variable ectoenzyme activity in seawater. As microbes are major players in organic matter transformations in the aquatic environment, such a tool may assist in characterizing the rapid metabolic activities of microbial communities on both short‐term (e.g., diurnal, tidal) and more extended time scales.
Determination of aquatic food‐web structure based on compound‐specific nitrogen isotopic composition of amino acids
Authors: Chikaraishi Yoshito , Ogawa Nanako O. , Kashiyama Yuichiro , Takano Yoshinori , Suga Hisami , Tomitani Akiko , Miyashita Hideaki , Kitazato Hiroshi , Ohkouchi Naohiko
Published: April 2011

The nitrogen isotopic composition (δ15N) of amino acids is potentially useful as an alternative method for estimating the trophic levels of organisms in food webs. However, because this “amino acid method” has been constructed from the observations of only a few case studies of food‐consumer combinations in previous studies, the universality of the approach remains unclear. In this study, we investigated the δ15N signatures of amino acids in 17 photoautotrophs and the trophic relationships during four controlled feeding experiments using green algae, zooplankton, and fish. The results are consistent with those reported in previous studies, implying that the amino acid method can be applied to a variety of organisms. From these and previously published data, we estimate the two factors (β, isotope differences among amino acids in primary producers; Δ, the 15N‐enrichment factor for each trophic level) required to calculate the trophic level. Based on the lowest error (1σ = 0.12) in the estimated trophic level, we conclude that a comparison of the δ15N values for glutamic acid and phenylalanine is most useful in calculating precise estimates of the trophic level, using the following equation: trophic level (TLGlu/Phe) = (δ15NGlu − δ15NPhe − 3.4)/7.6 + 1.
Dynamic sediment profile imaging (DySPI): a new field method for the study of dynamic processes at the sediment‐water interface
Authors: Blanpain Olivier , du Bois Pascal Bailly , Cugier Philippe , Lafite Robert , Lunven Michel , Dupont Jacky , Le Gall Erwan , Legrand Julien , Pichavant Pascal
Published: April 2011

Sediment transport processes at the sediment‐water interface are usually studied using flume tests. Due to technical limitations, extreme hydro‐sedimentary conditions are then rarely considered. Sediment profile imaging (SPI) is a widely used technique for mapping benthic habitat quality in soft sediments but several limitations exist that make the system ineffective for coarse or indurate sediment investigations and for transport processes studies. To address this problem, a modified system was designed to investigate these processes in situ, on a grain‐size scale, with high temporal resolution. A dynamic sediment profile imaging (DySPI) system was constructed with a new mode of penetration, an appropriate design and an imaging system based on high‐definition video recording. The supporting frame was instrumented with autonomous sensors to monitor boundary layer characteristics along with video observations. This system was deployed during spring tide on sediment characterized by a mixture of particle sizes dominated by coarse grains. Appropriate image processing allowed determination of the area of sediment entrained, movement threshold, size of moving particles, instantaneous transport rate and interface profile changes, in addition to usual SPI parameters. However, DySPI is a prototype and further development of the instrument and the image processing are possible to enlarge the scope presented in this study.
Electrospray and photoionization mass spectrometry for the characterization of organic matter in natural waters: a qualitative assessment
Authors: Hockaday William C. , Purcell Jeremiah M. , Marshall Alan G. , Baldock Jeffery A. , Hatcher Patrick G.
Published: April 2011

Fourier‐transform ion cyclotron resonance mass spectrometry (MS) has demonstrated potential to revolutionize the fields of limnology and chemical oceanography by identifying the individual molecular components of organic matter in natural waters. The use of MS for this purpose is made possible by the electrospray technique which successfully ionizes polar, nonvolatile organic molecules. Another recently developed ion source, atmospheric pressure photoionization (APPI), extends MS capabilities to less polar molecules. This article presents early results on the application of APPI MS to natural organic matter. We compare APPI MS and electrospray MS data for dissolved organic matter from Lake Drummond (Virginia, USA). Collectively, electrospray and APPI MS identify more than 6000 molecular species to which we assign unique molecular formulas. Fewer than 1000 molecular species are common to both electrospray and APPI mass spectra, indicating that the techniques are highly complementary in the types of molecules they ionize. Access to a broad range of molecules provided by combining APPI and electrospray has prompted a qualitative analysis. The goal is to assess the extent to which molecular MS data correspond with elemental (CHNOS) and structural characteristics determined by combustion elemental analyses and 13C nuclear magnetic resonance (NMR). Because the data obtained by these different methods are not directly comparable, we propose a novel data analysis procedure that facilitates their comparison. The bulk elemental composition calculated from electrospray MS data are in close agreement (± 15%) with values determined by combustion elemental analysis. APPI and electrospray MS detect protein contributions in agreement with 13C NMR (6 wt %) but underestimate carbohydrates relative to 13C NMR. Nevertheless, MS results agree with NMR on the relative proportions of noncarbohydrate compounds in the organic matter: lignins > lipids > peptides. Finally, we use a molecular mixing model to simulate a 13C NMR spectrum from the MS datasets. The correspondence of the simulated and measured 13C NMR signals (74%) suggests that, collectively, the molecular species identified by APPI and electrospray MS comprise a large portion of the organic matter in Lake Drummond. These results add credibility to electrospray and APPI MS in limnology and oceanography applications, but further characterization of ion source behavior is fundamental to the accurate interpretation of MS data.
Transport‐based method for estimating in‐stream nitrogen uptake at ambient concentration from nutrient addition experiments
Authors: Claessens Luc , Tague Christina L.
Published: April 2011

Nutrient addition experiments are commonly used for reach‐scale quantification of in‐stream nitrogen uptake. Traditional, short‐term nutrient addition experiments are subject to nutrient saturation effects, which influence the measured uptake rates, and are not transport based, which limits their ability to distinguish between channel and hyporheic processes. We developed a transport‐based nutrient addition approach adapted to account for the effect of nutrient saturation. We incorporated the Michaelis‐Menten saturation‐limited uptake function into the One‐dimensional Transport with Inflow and Storage (OTIS) solute transport model and specifically designed the field experiments for this modified version of the model (called OTIS‐MM). Cross‐method evaluations were performed for estimates of NH4+ and NO3− uptake lengths (Sw). For NH4+, OTIS‐MM and sequential, multiple‐level traditional experiments produced almost identical Sw values (124 versus 122 m), and the slopes of the regression lines relating Sw to added concentration were similar (4% difference). For NO3−, the methods produced similar Sw values (872 versus 909 m), but the slopes of the regression lines relating Sw to added concentration were different (23% difference). We complemented the cross‐method evaluations with sensitivity analyses for both NH4+ and NO3−, which confirmed that the estimates of the OTIS‐MM uptake parameters were robust. Our field‐modeling approach can easily be designed to cover multiple, sequential reaches in one single addition; hence, it allows for increased spatial coverage.
Automated system for sampling, counting, and biological analysis of rotifer populations
Authors: Stelzer Claus‐Peter
Published: April 2011

Zooplankton organisms with short generation times, such as rotifers, are ideal models to study general ecological and evolutionary questions on the population level, because meaningful experiments can often be completed within a couple of weeks. Yet biological analysis of such populations is often extremely time consuming, owing to abundance estimation by counting, measuring body size, or determining the investment into sexual versus asexual reproduction. An automated system for sampling and analyzing experimental rotifer populations is described. It relies on image analysis of digital photographs taken from subsamples of the culture. The system works completely autonomously for up to several weeks and can sample up to 12 cultures at time intervals down to a few hours. It allows quantitative analysis of female population density at a precision equivalent to that of conventional methods (i.e., manual counts of samples fixed in Lugol solution), and it can also recognize males, which allows detecting temporal variation of sexual reproduction in such cultures. Another parameter that can be automatically measured with the image analysis system is female body size. This feature may be useful for studies of population productivity and/or in competition experiments with clones of different body size. In this article, I describe the basic setup of the system and tests on the efficiency of data collection, and show some example data sets on the population dynamics of different strains of the rotifer Brachionus calyciflorus.
Inappropriate Asystole Detection in Early Postoperative Phase after Loop Recorder Implantation
Authors: Bortnik Miriam , Occhetta Eraldo , Magnani Andrea , Degiovanni Anna , Marino Paolo
Published: April 2011

The implantable loop recorder is a useful diagnostic tool for patients with unexplained syncope. The capability to automatically detect and store arrhythmic events, implemented in the last generations of these devices, can further improve the diagnostic yield, but this feature can be compromised by inappropriate detection of false arrhythmias. We herein report the case of a patient in which several inappropriate activations of long-lasting asystole occurred in the two days following the implant, probably because of an intermittently loose contact between the device and subcutaneous tissue for a small pocket haematoma.
Influence of Smoking on the Location of Acute Myocardial Infarctions
Authors: Alemu Rahel , Fuller Eileen E. , Harper John F. , Feldman Mark
Published: April 2011

Objective. To determine whether there is an association between smoking and the location of acute myocardial infarctions. Methods. Using a cohort from our hospital and published cohorts from Ireland, Uruguay, and Israel, we calculated odds of having an inferior wall as opposed to an anterior wall acute myocardial infarction among smokers and nonsmokers. Results. In our cohort, there was a higher proportion of smokers than nonsmokers in patients with inferior acute myocardial infarctions than in patients with anterior infarctions. This difference was also present in each of the other cohorts. Odds ratios for an inferior versus an anterior acute myocardial infarction among smokers ranged from 1.15 to 2.00 (median odds ratio, 1.32). When the cohorts were combined (), the pooled odds ratio for an inferior as opposed to an anterior acute myocardial infarction among smokers was 1.38 ( confidence interval, 1.20 to 1.58) (). Conclusions. Cigarette smoking increases the risk of inferior wall acute myocardial infarction more than the risk of anterior wall infarction. Smoking thus appears to adversely affect the right coronary arterial circulation to a greater extent than the left coronary arterial circulation by a mechanism not yet understood.
Inflammatory Animal Model for Parkinson's Disease: The Intranigral Injection of LPS Induced the Inflammatory Process along with the Selective Degeneration of Nigrostriatal Dopaminergic Neurons
Authors: Machado A. , Herrera A. J. , Venero J. L. , Santiago M. , de Pablos R. M. , Villarán R. F. , Espinosa-Oliva A. M. , Argüelles S. , Sarmiento M. , Delgado-Cortés M. J. , Mauriño R. , Cano J.
Published: April 2011

We have developed an animal model of degeneration of the nigrostriatal dopaminergic neurons, the neuronal system involved in Parkinson's disease (PD). The implication of neuroinflammation on this disease was originally established in 1988, when the presence of activated microglia in the substantia nigra (SN) of parkinsonians was reported by McGeer et al. Neuroinflammation could be involved in the progression of the disease or even has more direct implications. We injected 2 μg of the potent proinflammatory compound lipopolysaccharide (LPS) in different areas of the CNS, finding that SN displayed the highest inflammatory response and that dopaminergic (body) neurons showed a special and specific sensitivity to this process with the induction of selective dopaminergic degeneration. Neurodegeneration is induced by inflammation since it is prevented by anti-inflammatory compounds. The special sensitivity of dopaminergic neurons seems to be related to the endogenous dopaminergic content, since it is overcome by dopamine depletion. Compounds that activate microglia or induce inflammation have similar effects to LPS. This model suggest that inflammation is an important component of the degeneration of the nigrostriatal dopaminergic system, probably also in PD. Anti-inflammatory treatments could be useful to prevent or slow down the rate of dopaminergic degeneration in this disease.
Spectral Analysis and Crystal Structures of 4-(4-Methylphenyl)-6-Phenyl-2,3,3a, 4-Tetrahydro-1H-Pyrido[3,2,1-jk]Carbazole and 4-(4-Methoxyphenyl)-6-Phenyl-2,3,3a, 4-Tetrahydro-1H-Pyrido[3,2,1-jk]Carbazole
Authors: Kalyana Sundar J. , Natarajan S. , Chitra S. , Paul Nidhin , Manisankar P. , Muthusubramanian S. , Suresh J.
Published: April 2011

The crystal structures of 4-(4-methylphenyl)-6-phenyl-2,3,3a,4-tetrahydro-1H-pyrido[3,2,1-jk]carbazole (IIa) and 4-(4-methoxyphenyl)-6-phenyl-2,3,3a,4-tetrahydro-1H-pyrido[3,2,1-jk]carbazole (IIb) were elucidated by single crystal X-ray diffraction. Compound (IIa), C28H25N, crystallizes in the triclinic system, space group P-1, witha=8.936(2) Å,b=10.490(1) Å,c=11.801(1) Å,α=102.69(5)°, β=103.27(3)°,γ=93.80(1)°, andZ=2. The compound (IIb), C28H25NO, crystallizes in the monoclinic system, space group P21/a, witha=11.376(5) Å,b=14.139(3) Å,c=13.237(4) Å,β=97.41(3)°, andZ=4. In both the structures, the pyrido ring adopts a twist boat conformation and the carbazole molecule has the twisted envelope structure with C3 and C13 at the flap. No classical hydrogen bonds are observed in the crystal structures. Details of the preparation, structures, and spectroscopic properties of the new compounds are discussed.
Spontaneous Hepatic Rupture with Intraperitoneal Hemorrhage without Underlying Etiology: A Report of Two Cases
Authors: Klein Kristin , Shapiro A. M. James
Published: April 2011

Spontaneous hepatic rupture is a rare event most often occurring in association with underlying liver disease or pregnancy. We report two unusual cases of hepatic rupture without any identifiable pathology, trauma, or comorbid conditions.
Randomized Split-Mouth Study on Postoperative Effects of Palmitoylethanolamide for Impacted Lower Third Molar Surgery
Authors: Bacci Christian , Cassetta Giulia , Emanuele Bruno , Berengo Mario
Published: April 2011

The aim of this study was to assess the efficacy of Normast 300 mg in reducing swelling and pain after the surgical extraction of impacted lower third molars.
Materials and Methods. A randomized, split-mouth, single-blind study was conducted on 30 patients between 18 and 30 years of age requiring lower third molar extraction. Patients underwent bilateral extractions in a randomized sequence, one extraction being performed under Normast treatment. The Normast treatment involved 2 tablets a day for 15 days.
The parameters assessed at each procedure were trismus, swelling, pain, NSAID consumption, postoperative complications, drug tolerability, and safety. The results obtained were processed using repeated measures analysis of variance.
Results. Perceived postoperative pain was reportedly significantly milder on Normast treatment than control. The trend of the means differed over time (P<.0001) and between the two extraction groups (P<.0221). On the other hand, for edema and trismus, the trend differed over time for both groups but did not differ between the two groups.
Discussion. Our analyses indicate that patients experienced significantly less postoperative pain when they were treated with Normast.
Conclusions. Administering Normast improves the postoperative course—in terms of pain—after lower third molar extraction.
Effects of Variable Food Supply on the Body Condition of Breeding Tawny OwlsStrix alucoin Southern Finland
Authors: Solonen Tapio
Published: April 2011

Body condition of boreal species of vole-eaters seems to vary in accordance with fluctuating vole populations. Tawny owlsStrix alucoof temperate origin were studied to reveal if they show a similar pattern during nestling period near the northern limit of the species' range. The body condition of tawny owls was not considerably affected by the annual fluctuations of small voles indicated by regional vole indices and local prey samples. There were some significant relationships with some alternative prey but the variation in the body condition of owls was largely explained by the bird's age, time of the season, and stage of the nestling period. Old birds that bred earlier in the season were in better condition than young ones that bred later. Due to alternative prey, the body condition seemed to be relatively resistant to the effects of variable foraging conditions as expected for a generalist species of southern origin.
A post-merger hospital library collection survey and data analysis indicated better resource allocation and user satisfaction
Authors: Davis Alexandra , Shorr Risa , Campbell Kaitryn , McGowan Jessie
Published: April 2011

This article follows a previous article in "Bibliotheca Medica Canadiana" describing the original merger of this library. Library Services at The Ottawa Hospital (TOH) was created as the result of a series of hospital mergers. It supports a large teaching hospital serving the city of Ottawa, Ontario, and the surrounding area. TOH was formed in 1999 with the amalgamation of three hospitals: the Ottawa Civic, Ottawa General, and Riverside Hospitals. Before the first merger, there were three separate libraries. Library Services serves primarily staff from TOH and its affiliated research institute, the Ottawa Health Research Institute.