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"Anderson, D. M."
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An atlas of Middle Eastern affairs
\"The Middle East is a major focus of world interest. This revised and updated atlas provides accessible, concisely written entries on the most important current issues in the Middle East, combining maps with their geopolitical background. Providing a clear context for analysis of key concerns, it includes background topics, the position of the Middle East in the world and profiles of the constituent countries. \" -- from publisher.
Book
Composition of soil Frankia assemblages across ecological drivers parallels that of nodule assemblages in Alnus incana ssp. tenuifolia in interior Alaska
In root nodule symbioses (RNS) between nitrogen (N)‐fixing bacteria and plants, bacterial symbionts cycle between nodule‐inhabiting and soil‐inhabiting niches that exert differential selection pressures on bacterial traits. Little is known about how the resulting evolutionary tension between host plants and symbiotic bacteria structures naturally occurring bacterial assemblages in soils. We used DNA cloning to examine soil‐dwelling assemblages of the actinorhizal symbiont Frankia in sites with long‐term stable assemblages in Alnus incana ssp. tenuifolia nodules. We compared: (1) phylogenetic diversity of Frankia in soil versus nodules, (2) change in Frankia assemblages in soil versus nodules in response to environmental variation: both across succession, and in response to long‐term fertilization with N and phosphorus, and (3) soil assemblages in the presence and absence of host plants. Phylogenetic diversity was much greater in soil‐dwelling than nodule‐dwelling assemblages and fell into two large clades not previously observed. The presence of host plants was associated with enhanced representation of genotypes specific to A. tenuifolia, and decreased representation of genotypes specific to a second Alnus species. The relative proportion of symbiotic sequence groups across a primary chronosequence was similar in both soil and nodule assemblages. Contrary to expectations, both N and P enhanced symbiotic genotypes relative to non‐symbiotic ones. Our results provide a rare set of field observations against which predictions from theoretical and experimental work in the evolutionary ecology of RNS can be compared. N‐fixing host plants can theoretically affect the structure of soil‐dwelling assemblages of symbiotic microbes via selective amplification of specific genotypes. However, little is known about how soil‐dwelling and nodule‐dwelling assemblages compare in natural populations. This study examined this comparison in the Alnus‐Frankia system across a primary successional gradient in interior Alaska.
Journal Article
Suppression of the 2010 Alexandrium fundyense bloom by changes in physical, biological, and chemical properties of the Gulf of Maine
For the period 2005–2009, the abundance of resting cysts in bottom sediments from the preceding autumn was a first-order predictor of the overall severity of spring–summer blooms of Alexandrium fundyense in the western Gulf of Maine and southern New England. Cyst abundance off mid-coast Maine was significantly higher in autumn 2009 than it was preceding a major regional bloom in 2005. A seasonal ensemble forecast was computed using a range of forcing conditions for the period 2004–2009, suggesting that a large bloom was likely in the western Gulf of Maine in 2010. This did not materialize, perhaps because environmental conditions in spring–summer 2010 were not favorable for growth of A. fundyense. Water mass anomalies indicate a regional-scale change in circulation with direct influence on A. fundyense’s niche. Specifically, near-surface waters were warmer, fresher, more stratified, and had lower nutrients than during the period of observations used to construct the ensemble forecast. Moreover, a weaker-than-normal coastal current lessened A. fundyense transport into the western Gulf of Maine and Massachusetts Bay. Satellite ocean color observations indicate the 2010 spring phytoplankton bloom was more intense than usual. Early season nutrient depletion may have caused a temporal mismatch with A. fundyense’s endogenous clock that regulates the timing of cyst germination. These findings highlight the difficulties of ecological forecasting in a changing oceanographic environment, and underscore the need for a sustained observational network to drive such forecasts.
Journal Article
Geographical distribution of red and green Noctiluca scintillans
The dinoflagellate Noctiluca scintillans is one of the most important and abundant red tide organisms and it is distributed world-wide. It occurs in two forms. Red Noctiluca is heterotrophic and fills the role of one of the microzooplankton grazers in the foodweb. In contrast, green Noctiluca contains a photosynthetic symbiont Pedinomonas noctilucae (a prasinophyte), but it also feeds on other plankton when the food supply is abundant. In this review, we document the global distribution of these two forms and include the first maps of their global distribution. Red Noctiluca occurs widely in the temperate to sub-tropical coastal regions of the world. It occurs over a wide temperature range of about 10°C to 25°C and at higher salinities (generally not in estuaries). It is particularly abundant in high productivity areas such as upwelling or eutrophic areas where diatoms dominate since they are its preferred food source. Green Noctiluca is much more restricted to a temperature range of 25°C–30°C and mainly occurs in tropical waters of Southeast Asia, Bay of Bengal (east coast of India), in the eastern, western and northern Arabian Sea, the Red Sea, and recently it has become very abundant in the Gulf of Oman. Red and green Noctiluca do overlap in their distribution in the eastern, northern and western Arabian Sea with a seasonal shift from green Noctiluca in the cooler winter convective mixing, higher productivity season, to red Noctiluca in the more oligotrophic warmer summer season.
Journal Article
Proxy benchmarks for intercomparison of 8.2 ka simulations
The Paleoclimate Modelling Intercomparison Project (PMIP3) now includes the 8.2 ka event as a test of model sensitivity to North Atlantic freshwater forcing. To provide benchmarks for intercomparison, we compiled and analyzed high-resolution records spanning this event. Two previously-described anomaly patterns that emerge are cooling around the North Atlantic and drier conditions in the Northern Hemisphere tropics. Newer to this compilation are more robustly-defined wetter conditions in the Southern Hemisphere tropics and regionally-limited warming in the Southern Hemisphere. Most anomalies around the globe lasted on the order of 100 to 150 yr. More quantitative reconstructions are now available and indicate cooling of ~ 1 °C and a ~ 20% decrease in precipitation in parts of Europe as well as spatial gradients in δ18O from the high to low latitudes. Unresolved questions remain about the seasonality of the climate response to freshwater forcing and the extent to which the bipolar seesaw operated in the early Holocene.
Journal Article
DIFFUSE-INTERFACE METHODS IN FLUID MECHANICS
We review the development of diffuse-interface models of hydrodynamics and
their application to a wide variety of interfacial phenomena. These models have
been applied successfully to situations in which the physical phenomena of
interest have a length scale commensurate with the thickness of the interfacial
region (e.g. near-critical interfacial phenomena or small-scale flows such as
those occurring near contact lines) and fluid flows involving large interface
deformations and/or topological changes (e.g. breakup and coalescence events
associated with fluid jets, droplets, and large-deformation waves). We discuss
the issues involved in formulating diffuse-interface models for
single-component and binary fluids. Recent applications and computations using
these models are discussed in each case. Further, we address issues including
sharp-interface analyses that relate these models to the classical
free-boundary problem, computational approaches to describe interfacial
phenomena, and models of fully miscible fluids.
Journal Article
The Economic Effects of Harmful Algal Blooms in the United States: Estimates, Assessment Issues, and Information Needs
During the last several decades, harmful algal bloom (HAB) events have been observed in more locations than ever before throughout the United States. Scientists have identified a larger number of algal species involved in HABs, more toxins have been uncovered, and more fisheries resources have been affected. Whether this apparent increase in HAB events is a real phenomenon or is the result of increased sampling and monitoring is a topic of intense discussions within the scientific community. We also have an inchoate understanding of the reasons for the apparent increase, particularly concerning the role of anthropogenic nutrient loadings as a causal factor. Whatever the reasons, virtually all coastal regions of the U. S. are now regarded as potentially subject to a wide variety and increased frequency of HABs. It is important to begin to understand the scale of the economic costs to society of such natural hazards. It is a common, but not yet widespread, practice for resource managers and scientists in many localities to develop rough estimates of the economic effects of HAB events in terms of lost sales in the relevant product or factor markets, expenditures for medical treatments, environmental monitoring and management budgets, or other types of costs. These estimates may be invoked in policy debates, often without concern about how they were developed. Although such estimates are not necessarily good measures of the true costs of HABs to society, they may help to measure the scale of losses and be suggestive of their distribution across political jurisdictions or industry sectors. With adequate interpretation, our thinking about appropriate policy responses may be guided by these estimates. Here we compile disparate estimates of the economic effects of HABs for events in the U. S. where such effects were measured during 1987-1992. We consider effects of four basic types: public health, commercial fisheries, recreation and tourism, and monitoring and management. We discuss many of the issues surrounding the nature of these estimates, their relevance as measures of the social costs of natural hazards, and their potential for comparability and aggregation into a national estimate.
Journal Article
Community Assembly and Seasonal Succession of Marine Dinoflagellates in a Temperate Estuary: The Importance of Life Cycle Events
Dinoflagellate successional strategies and community structure were investigated in Perch Pond, a temperate estuary on the North American east coast by field surveys as well as laboratory investigations on growth rates, cyst maturation period, and cyst germination temperature thresholds. The dominant species were those predicted by the Smayda and Reynolds Rules of Assembly life form model. Three successional strategies were characterized: (1) holoplanktonic, (2) meroplanktonic (i.e., germinated from cysts), and (3) introduced by advection. The seasonal succession of the meroplanktonic dinoflagellates that were studied reflects the differential lengths of their mandatory dormancy periods as well as differences in their temperature thresholds or \"windows\" for germination. The holoplanktonic species present at low densities year-round in Perch Pond had a wide temperature tolerance for growth and thus did not need a cyst stage to survive seasonal extremes. Another non-cyst-forming species relied solely on advection to inoculate the salt pond; thus, blooms in successive years would be expected to be more stochastic in nature than for the other two strategies. The timing of cyst formation and population decline for meroplanktonic species corresponded on several occasions to an increase in grazers, suggesting that grazing might have contributed to bloom decline from cyst formation. This timing also suggests the possibility of encystment as a predator avoidance strategy. We suggest that seasonal succession of cyst-forming dinoflagellates is not stochastic. Instead, the appearance of these species in the plankton is predictable on the basis of measurable physiological responses to both endogenous and exogenous factors that they experience during dormancy and quiescence.
Journal Article
The brain microenvironment and cancer metastasis
The process of metastasis consists of a series of sequential, selective steps that few cells can complete. The outcome of cancer metastasis depends on multiple interactions between metastatic cells and homeostatic mechanisms that are unique to one or another organ microenvironment. The specific organ microenvironment determines the extent of cancer cell proliferation, angiogenesis, invasion and survival. Many lung cancer, breast cancer, and melanoma patients develop fatal brain metastases that do not respond to therapy. The blood-brain barrier is intact in and around brain metastases that are smaller than 0.25 mm in diameter. Although the blood-brain barrier is leaky in larger metastases, the lesions are resistant to many chemotherapeutic drugs. Activated astrocytes surround and infiltrate brain metastases. The physiological role of astrocytes is to protect against neurotoxicity. Our current data demonstrate that activated astrocytes also protect tumor cells against chemotherapeutic drugs.
Journal Article
A homologue of the TNF receptor and its ligand enhance T-cell growth and dendritic-cell function
Dendritic cells are rare haematopoietic cells that reside in a number of organs and tissues. By capturing, processing and presenting antigens to T cells, dendritic cells are essential for immune surveillance and the regulation of specific immunity
1
,
2
,
3
,
4
. Several members of the tumour necrosis factor receptor (TNFR) superfamily are integral to the regulation of the immune response. These structurally related proteins modulate cellular functions ranging from proliferation and differentiation to inflammation and cell survival or death
5
,
6
. The functional activity of dendritic cells is greatly increased by signalling through the TNFR family member CD40 (
refs 7
,
8
). Here we report the characterization of RANK (for receptor activator of NF-κB), a new member of the TNFR family derived from dendritic cells, and the isolation of a RANK ligand (RANKL) by direct expression screening. RANKL augments the ability of dendritic cells to stimulate naive T-cell proliferation in a mixed lymphocyte reaction, and increases the survival of RANK
+
T cells generated with interleukin-4 and transforming growth factor (TGF)-β. Thus RANK and RANKL seem to be important regulators of interactions between T cells and dendritic cells.
Journal Article