Chris W. Brown

Coccolithophorid blooms in the global ocean

The global distribution pattern of coccolithophorid blooms was mapped in order to ascertain the prevalence of these blooms in the worlds oceans and to estimate their worldwide production of CaCO3 and dimethyl sulfide (DMS). Mapping was accomplished by classifying pixels of 5-day global composites of coastal zone color scanner imagery into bloom and nonbloom classes using a supervised, multispectral classification scheme. Surface waters with the spectral signature of coccolithophorid blooms annually covered an average of 1.4×106 km2 in the world oceans from 1979 to 1985, with the subpolar latitudes accounting for 71% of this surface area. Classified blooms were most extensive in the Subarctic North Atlantic. Large expanses of the bloom signal were also detected in the North Pacific, on the Argentine shelf and slope, and in numerous lower latitude marginal seas and shelf regions. The greatest spatial extent of classified blooms in subpolar oceanic regions occurred in the months from summer to early autumn, while those in lower latitude marginal seas occurred in midwinter to early spring. Though the classification scheme was efficient in separating bloom and nonbloom classes during test simulations, and biogeographical literature generally confirms the resulting distribution pattern of blooms in the subpolar regions, the cause of the bloom signal is equivocal in some geographic areas, particularly on shelf regions at lower latitudes. Standing stock estimates suggest that the presumed Emiliania huxleyi blooms act as a significant source of calcite carbon and DMS sulfur on a regional scale. On a global scale, however, the satellite-detected coccolithophorid blooms are estimated to play only a minor role in the annual production of these two compounds and their flux from the surface mixed layer.

Sol-gel glass as a matrix for chemical and biochemical sensing

Abstract Sol-gel glass is a porous glass-like material produced at low temperatures by the sol-gel technique. Sol-gel glass has been increasingly used as a solid matrix for entrapment of chemical and biochemical agents in sensor development and other applications. This article will provide a brief introduction of sol-gel technique and a thorough up-to-date review of the applications of sol-gel derived glass in chemical and biochemical sensing. The sol-gel sensors reviewed include those for pH, ionic species, gases, and glucose. Sol-gel glasses for entrapment of organic dyes, proteins, enzymes and microbial cells, as well as sol-gel derived selective electrodes, are also reviewed.

Representing key phytoplankton functional groups in ocean carbon cycle models: Coccolithophorids

Carbonates are the largest reservoirs of carbon on Earth. From mid-Mesozoic time, the biologically catalyzed precipitation of calcium carbonates by pelagic phytoplankton has been primarily due to the production of calcite by coccolithophorids. In this paper we address the physical and chemical processes that select for coccolithophorid blooms detected in Sea-viewing Wide Field-of-view Sensor (SeaWiFS) ocean color imagery. Our primary goal is to develop both diagnostic and prognostic models that represent the spatial and temporal dynamics of coccolithophorid blooms in order to improve our knowledge of the role of these organisms in mediating fluxes of carbon between the ocean, the atmosphere, and the lithosphere. On the basis of monthly composite images of classified coccolithophorid blooms and global climatological maps of physical variables and nutrient fields, we developed a probability density function that accounts for the physical chemical variables that predict the spatiotemporal distribution of coccolithophorids in the world oceans. Our analysis revealed that areas with sea surface temperatures (SST) between 3° and 15°C, a critical irradiance between 25 and 150 µmol quanta m-2 s-1, and decreasing nitrate concentrations (N/t < 0) are selective for upper ocean large-scale coccolithophorid blooms. While these conditions favor both Northern and Southern Hemisphere blooms of the most abundant coccolithophorid in the modern oceans, Emiliania huxleyi, the Northern and Southern Hemisphere populations of this organism are genetically distinct. Applying amplified fragment length polymorphism as a marker of genetic diversity, we identified two major taxonomic clades of E. huxleyi; one is associated with the Northern Hemisphere blooms, while the other is found in the Southern Hemisphere. We suggest a rule of “universal distribution and local selection”: that is, coccolithophorids can be considered cosmopolitan taxa, but their genetic plasticity provides physiological accommodation to local environmental selection pressure. Sea surface temperature, critical irradiance, and N/t were predicted for the years 2060–2070 using the NCAR Community Climate System Model to generate future monthly probability distributions of coccolithophorids based upon the relationships observed between the environmental variables and coccolithophorid blooms in modern oceans. Our projected probability distribution analysis suggests that in the North Atlantic, the largest habitat for coccolithophorids on Earth, the areal extent of blooms will decrease by up to 50% by the middle of this century. We discuss how the magnitude of carbon fluxes may be affected by the evolutionary success of coccolithophorids in future climate scenarios.

Environmental signatures associated with cholera epidemics

The causative agent of cholera, Vibrio cholerae, has been shown to be autochthonous to riverine, estuarine, and coastal waters along with its host, the copepod, a significant member of the zooplankton community. Temperature, salinity, rainfall and plankton have proven to be important factors in the ecology of V. cholerae, influencing the transmission of the disease in those regions of the world where the human population relies on untreated water as a source of drinking water. In this study, the pattern of cholera outbreaks during 1998–2006 in Kolkata, India, and Matlab, Bangladesh, and the earth observation data were analyzed with the objective of developing a prediction model for cholera. Satellite sensors were used to measure chlorophyll a concentration (CHL) and sea surface temperature (SST). In addition, rainfall data were obtained from both satellite and in situ gauge measurements. From the analyses, a statistically significant relationship between the time series for cholera in Kolkata, India, and CHL and rainfall anomalies was determined. A statistically significant one month lag was observed between CHL anomaly and number of cholera cases in Matlab, Bangladesh. From the results of the study, it is concluded that ocean and climate patterns are useful predictors of cholera epidemics, with the dynamics of endemic cholera being related to climate and/or changes in the aquatic ecosystem. When the ecology of V. cholerae is considered in predictive models, a robust early warning system for cholera in endemic regions of the world can be developed for public health planning and decision making.

Raman Spectra of Possible Corrosion Products of Iron

Raman spectra of FeO, Fe3O4, α-Fe2O3, α-FeOOH, and γ-FeOOH, the common products of iron oxidation, have been measured. The spectra of FeO and Fe3O4 appear to be identical. Armco iron oxidized in air at 250°C was examined by Raman spectroscopy after varying periods of exposure and the surface film was found to contain Fe3O4 and α-Fe2O3.

Detecting Trichodesmium blooms in SeaWiFS imagery

A multispectral classification scheme was developed to detect the cyanobacteria Trichodesmium spp. in satellite data of the sea-viewing wide field-of-view sensor (SeaWiFS). The criteria for this scheme were established from spectral characteristics derived from (1) SeaWiFS imagery of a Trichodesmium bloom located in the South Atlantic Bight and (2) modeled remote sensing reflectances of Trichodesmium and other phytoplankton. The classification scheme, which is valid for moderate chlorophyll concentrations of Trichodesmium in coastal waters, is based on the magnitude of the 490-channel reflectance and the spectral shape of remote sensing reflectance at 443, 490 and 555 nm. Analysis suggests that the spatial structure of Trichodesmium populations at sub-pixel scales must be considered when employing spectral characteristics to detect their presence in satellite imagery. This study demonstrates the potential of mapping Trichodesmium from space using spectral observations, even in waters as optically complex as the South Atlantic Bight. Future efforts, which will incorporate ancillary data such as wind speeds and water temperature, will improve the likelihood of correct identification.

Prevalence of neoplasia in 10 New England populations of the soft-shell clam (Mya arenaria).

Neoplasia was a prevalent disease of the soft-shell clam and was found in widely geographically distinct sites in New England. Two types of neoplasms were recognized. Most were of hematopoietic origin, except in clams from Maine, which also had gonadal neoplasms. Both types were apparently malignant neoplasms, based on their characteristic anaplastic appearance, invasiveness, metastasis, mitotic activity, associated tissue necrosis, and mortality. Diagnosis of neoplasia in the living mollusk was achieved rapidly and accurately by cytologic examination of circulating blood. The etiology of the neoplasms was not identified. In general, nonneoplastic lesions, such as epithelial hyperplasia and accumulations of a orange-brown bodies, were more common in clams from polluted areas.

Characterization of the passive film formed on weathering steels

Abstract Raman spectroscopy, infrared spectroscopy and electrochemical reduction techniques were used to characterize the passive film formed on weathering steels. Test pieces of weathering steel were exposed to an industrial environment for 4.5 and 8 yrs. In both cases the passive film was composed predominantly of 8-FeOOH with 10–20% γ-FeOOH and possibly some α-FeOOH. Raman spectra from different depths of the surface were identical which implied that the film composition was homogeneous.

Outcomes following HSCT Using Fludarabine, Busulfan, and Thymoglobulin: A Matched Comparison to Allogeneic Transplants Conditioned with Busulfan and Cyclophosphamide

We have reported a lower incidence of acute graft-versus-host disease (aGVHD) with a novel conditioning regimen using low-dose rabbit antithymocyte globulin (ATG; Thymoglobulin [TG]) with fludarabine and intravenous busulfan (FluBuTG). To assess further this single-center experience, we performed a retrospective matched-pair analysis comparing outcomes of adult patients transplanted using the FluBuTG conditioning regimen with matched controls from patients reported to the CIBMTR receiving a first allogeneic hematopoietic stem cell transplant (HCT) after standard oral busulfan and cyclophosphamide (BuCy). One hundred twenty cases and 215 matched controls were available for comparison. Patients receiving FluBuTG had significantly less treatment related mortality (TRM; 12% versus 34%, P < .001) and grades II-IV aGVHD (15% versus 34%, P < .001) compared to BuCy patients. The risk of relapse was higher in the FluBuTG patients (42% versus 20%, P < .001). The risks of chronic GVHD (cGVHD) and disease free survival (DFS) were similar in the cases and controls. These results suggest that the novel regimen FluBuTG decreases the risk of aGVHD and TRM after HLA-identical sibling HSCT, but is associated with an increased risk of relapse, resulting in similar DFS. Whether these conditioning regimens may be more suitable for specific patient populations based on relapse risk requires testing in prospective randomized trials.

Superior autologous blood stem cell mobilization from dose-intensive cyclophosphamide, etoposide, cisplatin plus G-CSF than from less intensive chemotherapy regimens

The study purpose was to determine if G-CSF plus dose-intensive cyclophosphamide 5.25 g/m2, etoposide 1.05 g/m2 and cisplatin 105 mg/m2 (DICEP) results in superior autologous blood stem cell mobilization (BSCM) than less intensive chemotherapy. From January 1993 until May 1997, 152 consecutive patients with non-Hodgkin’s lymphoma (n = 55), breast cancer (n = 47), Hodgkin’s disease (n = 14), multiple myeloma (n = 9), AML (n = 9), or other cancers (n = 18) initially underwent BSCM by one of three methods: Group 1: G-CSF alone × 4 days (n = 30). Group 2: disease-oriented chemotherapy, dosed to avoid blood transfusions, followed by G-CSF starting day 7 or 8, and apheresis day 13 or 14 (n = 82). Group 3: DICEP days 1–3, G-CSF starting day 14, and apheresis planned day 19, 20 or 21 (n = 40). A multivariate analysis was performed to determine which factors independently predicted BSCM. The median peripheral blood CD34+ (PB CD34+) cell count the morning of apheresis linearly correlated with the number of CD34+ cells removed per litre of apheresis that day. The median PB CD34+ cell count and median CD34+ cells × 106 removed per litre of apheresis were highest for Group 3, intermediate for Group 2, and lowest for Group 1. By multivariate analysis, mobilization group (3 > 2 > 1), disease other than AML, no prior melphalan or mitomycin-C, and less than two prior chemotherapy regimens predicted better BSCM. Out of 15 Group 3 patients who had infiltrated marrows, 11 had no detectable cancer in marrow and apheresis products after DICEP. These data suggest that DICEP results in superior BSCM than less intensive chemotherapy regimens.