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The Role Of Mesoscale Hydrography On Microbial Dynamics In The Northeast Atlantic: Results Of A Spring Bloom Experiment, B. Karrasch, H. G. Hoppe, S. Ullrich, S. Podewski Jan 1996

The Role Of Mesoscale Hydrography On Microbial Dynamics In The Northeast Atlantic: Results Of A Spring Bloom Experiment, B. Karrasch, H. G. Hoppe, S. Ullrich, S. Podewski

Journal of Marine Research

During RV Meteor cruise No. 10 from May to June 1989 (JGOFS pilot study) bacterial and picocyanobacterial abundance, biomass, and bacterial production were estimated at two drift stations close to 47N, 20W and 58N, 20W in the northeast Atlantic. At 47N two different mesoscale hydrographic structures were sampled which divided the drift experiment into a cyclonic and an anticyclonic circulation phase. Transition from one phase to the next was clearly reflected by changes of the biological structure in the upper water column. Phytoplankton stocks maintained during the cyclonic phase were about 1.8 times higher than those of the anticyclonic phase …

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Biological Removal Of Fine-Grained Lithogenic Particles From A Large River Plume, M. J. Dagg, E. P. Green, B. A. Mckee, P. B. Ortner Jan 1996

Biological Removal Of Fine-Grained Lithogenic Particles From A Large River Plume, M. J. Dagg, E. P. Green, B. A. Mckee, P. B. Ortner

Journal of Marine Research

The pelagic tunicate, Oikopleura dioica, feeds by non-selectively filtering particles in the size range of 0.2–20 μm. In the northern Gulf of Mexico, particulate matter in this size range contains large amounts of fine-grained lithogenic material because of the influence of the Mississippi River. During May 1992, O. dioica populations filtered between 2 and 44% (mean = 20%) of the upper 5 m each day. The filtered lithogenic particles either remain in the oikopleurid house or are defecated in fecal pellets which have high sinking velocities. Either way, the larvacean populations significantly alter the fates of fine-grained lithogenic particles …

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Molecular Diversity Of The Copepod, Nannocalunus Minor: Genetic Evidence Of Species And Population Structure In The North Atlantic Ocean, Anna Bucklin, Todd C. Lajeunesse, Eva Curry, John Wallinga, Karen Garrison Jan 1996

Molecular Diversity Of The Copepod, Nannocalunus Minor: Genetic Evidence Of Species And Population Structure In The North Atlantic Ocean, Anna Bucklin, Todd C. Lajeunesse, Eva Curry, John Wallinga, Karen Garrison

Journal of Marine Research

The abundant calanoid copepod, Nannocalanus minor, is widespread from the Florida Straits (FS), throughout the Gulf Stream and the Sargasso Sea, to the eastern North Atlantic Ocean. Does the species represent a single, randomly-mating population across this extensive region, or does it comprise a number of genetically distinct populations or taxonomically distinct forms? What are patterns and pathways of dispersal of the copepod across the North Atlantic? These questions were addressed using population genetic analysis of DNA sequence variation of a 440 base-pair region of the mitochondrial 16S rRNA gene. This analysis separated N. minor into two genetically distinct …

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A High Resolution Camera System (Parca) For Imaging Particles In The Ocean: System Design And Results From Profiles And A Three-Month Deployment, Volker Ratmeyer, Gerold Wefer Jan 1996

A High Resolution Camera System (Parca) For Imaging Particles In The Ocean: System Design And Results From Profiles And A Three-Month Deployment, Volker Ratmeyer, Gerold Wefer

Journal of Marine Research

For direct optical measurement of abundance, concentration and size distribution of marine particles, a high-resolution camera system (ParCa) was designed to improve on similar systems used by Honjo et al. (1984), Asper (1987) and others. Imaging a probe volume of up to 37 1, smallest particles with diameters of 50 μm can be counted. The images provide information on particle size, shape and abundance either during profiling through the water column or while moored in a certain depth over time. Depth profiles were acquired between fall 1992 and late spring 1993 on R. V. Meteor cruises M22-1 and M23-3 …

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Seasonal Transport Variations Of The Wind-Driven Ocean Circulation In A Two-Layer Planetary Geostrophic Model With A Continental Slope, Toshihiro Sakamoto, Toshio Yamagata Jan 1996

Seasonal Transport Variations Of The Wind-Driven Ocean Circulation In A Two-Layer Planetary Geostrophic Model With A Continental Slope, Toshihiro Sakamoto, Toshio Yamagata

Journal of Marine Research

Using a simple two-layer planetary geostrophic model with a continental slope, the observed seasonal variation of the total transport of the Kuroshio is explained qualitatively for the first time in a quite concise way. During the period of weak winds in summer, the total transport is much larger than the nontopographic Sverdrup transport. This is because the joint effect of baroclinicity and bottom relief (so-called JEBAR) drives the barotropic flow with releasing the available potential energy accumulated in winter. In winter, on the other hand, the transport is much smaller than the nontopographic Sverdrup transport. This is mainly due to …

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Carbon Cycling In Mesohaline Chesapeake Bay Sediments 2: Kinetics Of Particulate And Dissolved Organic Carbon Turnover, Eric E. Roden, Jon H. Tuttle Jan 1996

Carbon Cycling In Mesohaline Chesapeake Bay Sediments 2: Kinetics Of Particulate And Dissolved Organic Carbon Turnover, Eric E. Roden, Jon H. Tuttle

Journal of Marine Research

Temporal and depth variations in benthic carbon metabolism rates were examined in relation to particulate organic carbon (POC) deposition rates and particulate and dissolved organic carbon degradation kinetics in two sediments from the mesohaline region of Chesapeake Bay. The depth distribution of a single pool of metabolizable POC (MPOC) in mid-Bay sediments was estimated by curve-fitting of dry weight POC profiles (“1-G” approach). Estimated MPOC pools accounted for 3–4% of total POC content in the upper 10 cm of sediment. First-order MPOC decay constants of ≈10 yr−1 during the warm season were estimated from the ratio of …

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The Role Of Turbulence In The Sedimentation Loss Of Pelagic Aggregates From The Mixed Layer, Javier Ruiz Jan 1996

The Role Of Turbulence In The Sedimentation Loss Of Pelagic Aggregates From The Mixed Layer, Javier Ruiz

Journal of Marine Research

A simple approach is presented to model the effect that turbulence has on the sedimentation loss of pelagic particles from the mixed layer. The approach consists in determining how turbulence affects their vertical distribution by splitting the solution of the advection-diffusion equation into two functions, one for the concentration of particles in the mixed layer and the other one reflecting the shape of the profile of particle concentration. The results of the paper indicate that the sedimentation flux is seriously underestimated if a uniform distribution of particles is assumed in the mixed layer when turbulence levels are low. A correction …

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Grid-Scale Instability Of Convective-Adjustment Schemes, Paola Cessi Jan 1996

Grid-Scale Instability Of Convective-Adjustment Schemes, Paola Cessi

Journal of Marine Research

Through a simple illustrative example, it is shown that instantaneous convective adjustment schemes, of the type used in general circulation models to parametrize nonhydrostatic convective processes, lead to the spontaneous emergence of the smallest resolved horizontal scale: the grid mode is unstable regardless of the strength of the horizontal diffusivity. Convective adjustment vertically mixes properties at each grid-point, irrespective of the horizontal distribution of such properties. Thus, horizontal spatial gradients are amplified by convective adjustment, as long as adjustment is faster than the horizontal diffusion (or advection) time between neighboring grid-points. In the example presented here, the grid-scale instability is …

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Spin-Down And The Dynamics Of Dense Pool Gyres In Shallow Seas, A. E. Hill Jan 1996

Spin-Down And The Dynamics Of Dense Pool Gyres In Shallow Seas, A. E. Hill

Journal of Marine Research

Isolated lenses or domes of dense (often cold) bottom water are found in many shelf seas and can be expected to induce significant baroclinic circulations. However, provided they have the correct thermal wind shear, many flow states can support a bottom dome structure, including: (a) an anticyclonically circulating dense dome overlain by a static surface layer or (b) cyclonic surface flow around a static dome. A one-dimensional, two-layer, quasi-geostrophic model is applied to a Gaussian vortex to argue that, on account of bottom friction in shelf seas, the bottom layer will spin down to rest over a time-scale of just …

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Water-Property Distributions Along An Eastern Pacific Hydrographic Section At 135w, Mizuki Tsuchiya, Lynne D. Talley Jan 1996

Water-Property Distributions Along An Eastern Pacific Hydrographic Section At 135w, Mizuki Tsuchiya, Lynne D. Talley

Journal of Marine Research

As part of the World Ocean Circulation Experiment, full-depth CTD/hydrographic measurements with high horizontal and vertical resolutions were made in June-August 1991 along a line extending from 34N to 33S at a nominal longitude of 135W with an additional short leg that connects it to the California coast roughly along 34N. The line spans the major part of the subtropical and intertropical circulation regime of the eastern North and South Pacific. The primary purpose of this paper is to present vertical sections of various properties from CTD and discrete water-sample measurements along this line and to give an overview of …

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Fluid Flow And Suspended Particulates As Determinants Of Polychaete Feeding Behavior, Michael J. Bock, Douglas C. Miller Jan 1996

Fluid Flow And Suspended Particulates As Determinants Of Polychaete Feeding Behavior, Michael J. Bock, Douglas C. Miller

Journal of Marine Research

We examined the interactive effects of fluid flow, bed characteristics and suspended load on the feeding behavior of four species of marine polychaetes. Two species of obligate deposit feeders (Marenzelleria viridis and Ampharete parvidentata) and two species of palp-coiling facultative suspension feeders (Spiochaetopterus oculatus and Spio setosa) were exposed to flow and sediment-bed treatments that served to decouple fluid flow and particle flux. We employed low (no particle transport), medium (transport of flocs only) and high (transport of sand) flow speeds in factorial treatments of natural sediment, winnowed bed (flocs removed), armored bed (no sand transport …

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The Solubility Pump Of Carbon In The Subtropical Gyre Of The North Atlantic, Michael J. Follows, Richard G. Williams, John C. Marshall Jan 1996

The Solubility Pump Of Carbon In The Subtropical Gyre Of The North Atlantic, Michael J. Follows, Richard G. Williams, John C. Marshall

Journal of Marine Research

The subduction of carbon is examined using abiotic models of the solubility pump in the subtropical gyre of the North Atlantic. The importance of the seasonal cycle of the mixed layer, and advection of carbon, is examined using sensitivity experiments with a Lagrangian model of the carbon system. The rate of subduction of carbon is found to be strongly influenced by the gradients in mixed-layer thickness over the gyre and, to a lesser extent, modified by the end of winter bias in the properties of subducted fluid. A seasonally-cycling geochemical model of the carbon system is then developed for the …

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Inertial Gyre Solutions From A Primitive Equation Ocean Model, Annalisa Griffa, Eric P. Chassignet, Victoria Coles, Donald B. Olson Jan 1996

Inertial Gyre Solutions From A Primitive Equation Ocean Model, Annalisa Griffa, Eric P. Chassignet, Victoria Coles, Donald B. Olson

Journal of Marine Research

A numerical exploration of inertial equilibrium states obtained with a primitive equation ocean model suggests that they can be described using statistical mechanics theory developed in the framework of quasi-geostrophy. The performance of the numerical model is first assessed with respect to the quasi-geostrophic model considering a series of experiments in the quasi-geostrophic range, in a closed basin with flat bottom and varying Rossby numbers. The results show that our model is consistent with the quasi-geostrophic model even in terms of dependence from boundary conditions and eddy viscosity values, and that the free surface contribution is negligible. As in the …

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Deducing Dynamic Properties From Simulated Hydrographic Data: Part I. Results From A Non-Eddy-Resolving Model, Huai-Min Zhang, Nelson G. Hogg Jan 1996

Deducing Dynamic Properties From Simulated Hydrographic Data: Part I. Results From A Non-Eddy-Resolving Model, Huai-Min Zhang, Nelson G. Hogg

Journal of Marine Research

Inverse models are widely used in oceanography. However, their reliability remains an open question, as comparison of inverse model results with real values of ocean parameters is difficult due to insufficient knowledge of the latter. The feasibility of extracting the ocean general circulation, mixing rates, as well as air-sea heat and freshwater fluxes from hydrographic data is studied by applying an inverse model to the CME (Community Modeling Effort) results where both the physics and parameter values are known. The inverse model assumes approximate thermal wind balance and steady state conservation laws for mass, heat, and salt, assumptions satisfied by …

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Plankton Production In Tidal Fronts: A Model Of Georges Bank In Summer, Peter J. S. Franks, Changsheng Chen Jan 1996

Plankton Production In Tidal Fronts: A Model Of Georges Bank In Summer, Peter J. S. Franks, Changsheng Chen

Journal of Marine Research

A two-dimensional (x,z) coupled physical-biological model of the plankton on Georges Bank during the summer was developed. The physical portion included a primitive-equation turbulence-closure model with topography-following σ coordinate. The biological model was a simple N-P-Z model. Tidal forcing at the model boundary generated a well-mixed region on the top of the bank, and strong tidal fronts at the bank edges. Biological fields were homogenized on the bank, while pronounced phytoplankton patches and horizontal gradients in properties developed in the fronts. The biomasses and fluxes of biological variables in the model agreed well with field estimates from Georges …

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The Classification And Structure Of Megafaunal Assemblages In The Venezuela Basin, Caribbean Sea, Kevin B. Briggs, Michael D. Richardson, David K. Young Jan 1996

The Classification And Structure Of Megafaunal Assemblages In The Venezuela Basin, Caribbean Sea, Kevin B. Briggs, Michael D. Richardson, David K. Young

Journal of Marine Research

Data from 23 benthic trawls collected from the Venezuela Basin (3411–5062 m water depth) indicate that megafauna are less abundant than in basins of similar depths in the Atlantic and are segregated by sedimentary province. Taxonomic assemblages, in terms of abundance and biomass, from three sites coincide with distinctions of sedimentary characteristics among the pelagic, hemipelagic and turbidite sedimentary provinces. Mollusks, decapods and fishes are most abundant in trawls collected from the pelagic and hemipelagic provinces and anemones and holothurians are most abundant in trawls collected from the turbidite province. Sponges dominate the biomass of fauna in trawls collected in …

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Unsteady Similarity Solutions And Oscillating Ocean Gyres, Neil R. Edwards Jan 1996

Unsteady Similarity Solutions And Oscillating Ocean Gyres, Neil R. Edwards

Journal of Marine Research

The effect of time-dependent forcing on steady solutions representing basin-scale flows is investigated. Analytical and numerical solutions are considered separately and compared. We first use symmetry methods to show how any steady solution of the ideal thermocline equations can be used to generate a family of unsteady solutions, via an arbitrary function of time α(t). The resulting time-dependent solutions correspond to distortion of the isopycnal surfaces by a velocity field which varies linearly in the three coordinate directions. Although the displacements are linear, the fluctuations can lead to a form of nonlinear streaming wherever the function α appears …

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Analysis Of The North Atlantic Climatologies Using A Combined Ogcm/Adjoint Approach, Lisan Yu, Paola Malanotte-Rizzoli Jan 1996

Analysis Of The North Atlantic Climatologies Using A Combined Ogcm/Adjoint Approach, Lisan Yu, Paola Malanotte-Rizzoli

Journal of Marine Research

An exact adjoint for the full-scale Bryan-Cox primitive equation model is applied to assimilate the North Atlantic climatologies. The inverse calculation aims at searching a steady state oceanic general circulation consistent with observations, by controlling the model input parameters (such as the initial states and the upper thermal and haline boundary conditions). Two climatological hydrographies (Levitus (1982) and Fukumori and Wunsch (1991)) are used for the assimilation. This enables the examination of the sensitivity of the assimilated results to data quality. In addition, the consistency between the climatological hydrography and fluxes is discussed by examining the fits between the optimally …

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An Experimental And Modeling Study Of Ph And Related Solutes In An Irrigated Anoxic Coastal Sediment, Roberta L. Marinelli, Bernard P. Boudreau Jan 1996

An Experimental And Modeling Study Of Ph And Related Solutes In An Irrigated Anoxic Coastal Sediment, Roberta L. Marinelli, Bernard P. Boudreau

Journal of Marine Research

Macrofaunal irrigation is an important process in nearshore sediments, facilitating greater exchange between sediments and seawater and imparting significant lateral heterogeneity to the porewater profiles of many constituents. Like many macrofaunal activities, irrigation is a transient behavior, i.e. tubes and burrows are flushed periodically, at frequencies that generally are species-specific. As a result, transient concentrations within the dwelling arise, potentially impacting gradients, fluxes and reaction rates in the vicinity of the dwelling. We investigated the impact of periodic burrow irrigation on the distribution of several diagenetically important porewater constituents. Laboratory experiments evaluated irrigation periodicity using artificially irrigated tubes embedded in …

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Characterization Of The Particulate Protein In Pacific Surface Waters, Eiichiro Tanoue Jan 1996

Characterization Of The Particulate Protein In Pacific Surface Waters, Eiichiro Tanoue

Journal of Marine Research

The molecular characteristics of particulate protein in the surface waters along transects from 45N to 25S in the central Pacific are reported. The majority of particulate-combined amino acids (PCAA) was in the form of protein molecules in the samples from the northern North Pacific and Equatorial regions, namely, productive areas, while PCAA was mainly present as nonproteinaceous amino acid in the subtropical regions, namely, oligotrophic areas. Thus, it appears that the chemical form of PCAA, one of the major constituents of particulate organic matter (POM), varies meridionally. Two characteristic groups of particulate protein were identified from meridional differences in their …

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Diatom And Silicoflagellate Fluxes At The Walvis Ridge: An Environment Influenced By Coastal Upwelling In The Benguela System, Ute F. Treppke, Carina B. Lange, Barbara Donner, Gerhard Fischer, Götz Ruhland, Gerold Wefer Jan 1996

Diatom And Silicoflagellate Fluxes At The Walvis Ridge: An Environment Influenced By Coastal Upwelling In The Benguela System, Ute F. Treppke, Carina B. Lange, Barbara Donner, Gerhard Fischer, Götz Ruhland, Gerold Wefer

Journal of Marine Research

Seasonal fluctuations in the total particle, biogenic opal, diatom and silicoflagellate fluxes were observed in sediment traps deployed at 599 m and 1648 m in the Walvis Ridge area, within the Benguela upwelling system, from March 1989 to March 1990 (station WR 2: 20°02.8′S, 09°09.3′E). Fluxes were directly related to wind stress variations (wind maxima preceding flux maxima by several weeks), and inversely related to SST changes (derived from measured concentrations of C37 alkenones; range: 14.6°–23.6°C). The biogenic particle composition at different depths reflected the complicated hydrology of the area with a combination of tropical, temperate and subantarctic water …

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Variability And Sources Of The Southeastern Atlantic Circulation, Silvia L. Garzoli, Arnold L. Gordon, Vladimir Kamenkovich, Dale Pillsbury, Christopher Duncombe-Rae Jan 1996

Variability And Sources Of The Southeastern Atlantic Circulation, Silvia L. Garzoli, Arnold L. Gordon, Vladimir Kamenkovich, Dale Pillsbury, Christopher Duncombe-Rae

Journal of Marine Research

The 1992–1993 Benguela Sources and Transport (BEST) time series provide a quantitative view of the Benguela Current transport and the eddy field crossing 30S, as well as an estimate of the relation between its barotropic and baroclinic components. This is done by a simultaneous analysis of the BEST data derived from inverted echo sounders, pressure sensors, current meter moorings, CTD, and ADCP stations. The analysis of the time series indicates that the annual mean baroclinic transport of the Benguela Current is 13 Sv with a total transport of 16 Sv. Through the combination of instruments the total baroclinic plus barotropic …

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Carbon Export And Regeneration In The Coastal Upwelling System Of Monterey Bay, Central California, Cynthia H. Pilskaln, Jennifer B. Paduan, Francisco P. Chavez, Roger Y. Anderson, William M. Berelson Jan 1996

Carbon Export And Regeneration In The Coastal Upwelling System Of Monterey Bay, Central California, Cynthia H. Pilskaln, Jennifer B. Paduan, Francisco P. Chavez, Roger Y. Anderson, William M. Berelson

Journal of Marine Research

In order to quantify the role of coastal upwelling regions as source or sink areas for carbon, the relationships between particulate organic carbon (POC) production, export, remineralization, and accumulation were examined in Monterey Bay from 1989 through 1992. During a normal upwelling year (1989–90), a high positive correlation (r = 0.91) is observed between biweekly primary production and POC export at 450 m. Primary production values range from 500 mgC m−2 d−1 during the winter, to 2600 mgC m−2 d−1 in the spring and summer upwelling months. Corresponding deep-water (450 m) POC fluxes vary from …

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Photochemotherapy Of Vascular Cells With 8-Methoxypsoralen And Visible Light: A Novel Approach To The Prevention Of Post-Angioplasty Restenosis, David Marshall Lee Jan 1996

Photochemotherapy Of Vascular Cells With 8-Methoxypsoralen And Visible Light: A Novel Approach To The Prevention Of Post-Angioplasty Restenosis, David Marshall Lee

Yale Medicine Thesis Digital Library

No abstract provided.

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Prenatal Ultrasound Biometry Combined With Umbilical And Middle Cerebral Artery Doppler Velocimetry For The Detection Of Intrauterine Growth Restriction, Andrea Toulson Jeffress Jan 1996

Prenatal Ultrasound Biometry Combined With Umbilical And Middle Cerebral Artery Doppler Velocimetry For The Detection Of Intrauterine Growth Restriction, Andrea Toulson Jeffress

Yale Medicine Thesis Digital Library

No abstract provided.

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Magnetic Resonance Imaging Of The Ovary : Can It Predict Low Response To Empiric Superovulation?, Rebecca Jane Crichton Jan 1996

Magnetic Resonance Imaging Of The Ovary : Can It Predict Low Response To Empiric Superovulation?, Rebecca Jane Crichton

Yale Medicine Thesis Digital Library

No abstract provided.

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The Value Of Lateral Chest Radiographs In The Assessment Of Bone Density And Detection Of Osteopenia, Monica Anna Medynski Jan 1996

The Value Of Lateral Chest Radiographs In The Assessment Of Bone Density And Detection Of Osteopenia, Monica Anna Medynski

Yale Medicine Thesis Digital Library

No abstract provided.

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Analysis Of In Vivo Tissue Expander Fluid Composition, Richard A. Nahouraii Jan 1996

Analysis Of In Vivo Tissue Expander Fluid Composition, Richard A. Nahouraii

Yale Medicine Thesis Digital Library

No abstract provided.

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Ethics Or Etiquette: The History And Epidemiology Of Professional Courtesy In Medicine, Jeffrey Ian Algazy Jan 1996

Ethics Or Etiquette: The History And Epidemiology Of Professional Courtesy In Medicine, Jeffrey Ian Algazy

Yale Medicine Thesis Digital Library

No abstract provided.

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The Expression Of Angiogenic Growth Factors And Extracellular Matrix Proteins In Central Nervous System Vascular Malformations, Jiyon Lee Jan 1996

The Expression Of Angiogenic Growth Factors And Extracellular Matrix Proteins In Central Nervous System Vascular Malformations, Jiyon Lee

Yale Medicine Thesis Digital Library

No abstract provided.

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