263 research outputs found
Training Student Organizers Curriculum (Revised Edition)
This second edition of the Training Student Organizers Curriculum has been written to reflect the project organizing experiences of students, teachers and staff participating in the Council on the Environment of New York City\u27s Training Student Organizers Program (TSO) since the first edition of the curriculum was published in 1983. We have expanded the lessons/narratives in Part I to include more information on environmental issues and have also added lessons and/or narratives for specific environmental action projects. The how to\u27s of project organizing are described, step by step, in specific improvement projects in Part I, and reviewed as a total process in Part II. While this has led to some repetition, teachers, youth leaders, and student organizers can turn to any specific project and read the lessons and/or statements in that section without having to read Part II unless clearly designated in the specific lessons. We have also added three issue units to Part I: Noise --an addenda section in the original version; Transportation; and Nuclear Issues
Troublesome toxins: time to re-think plant-herbivore interactions in vertebrate ecology
Earlier models of plant-herbivore interactions relied on forms of functional response that related rates of ingestion by herbivores to mechanical or physical attributes such as bite size and rate. These models fail to predict a growing number of findings that implicate chemical toxins as important determinants of plant-herbivore dynamics. Specifically, considerable evidence suggests that toxins set upper limits on food intake for many species of herbivorous vertebrates. Herbivores feeding on toxin-containing plants must avoid saturating their detoxification systems, which often occurs before ingestion rates are limited by mechanical handling of food items. In light of the importance of plant toxins, a new approach is needed to link herbivores to their food base. We discuss necessary features of such an approach, note recent advances in herbivore functional response models that incorporate effects of plant toxins, and mention predictions that are consistent with observations in natural systems. Future ecological studies will need to address explicitly the importance of plant toxins in shaping plant and herbivore communities
Enzymatic Synthesis of Glycosaminoglycan Heparin
Heparin and its low molecular weight heparin derivatives, widely used as clinical anticoagulants, are acidic polysaccharide members of a family of biomacromolecules called glycosaminoglycans (GAGs). Heparin and the related heparan sulfate are biosynthesized in the Golgi apparatus of eukaryotic cells. Heparin is a polycomponent drug that currently is prepared for clinical use by extraction from animal tissues. A heparin pentasaccharide, fondaparinux, has also been prepared through chemical synthesis for use as a homogenous anticoagulant drug. Recent enabling technologies suggest that it may now be possible to synthesize heparin and its derivatives enzymatically. Moreover, new technologies including advances in synthetic carbohydrate synthesis, enzyme-based GAG synthesis, micro- and nano-display of GAGs, rapid on-line structural analysis, and microarray/microfluidic technologies might be applied to the enzymatic synthesis of heparins with defined structures and exhibiting selected activities. The advent of these new technologies also makes it possible to consider the construction of an artificial Golgi to increase our understanding of the cellular control of GAG biosyntheses in this organelle
Historical Neighborhood Redlining
The source data used to construct this contextual file for the National Longitudinal Study of Adolescent to Adult Health (Add Health) come from Mapping Inequality: Redlining in New Deal America, compiled by Robert K. Nelson and the Digital Scholarship Lab at the University of Richmond. This file augments the current Add Health contextual data collection by providing information about whether a respondent’s place of residence falls inside or within varying proximities to historically redlined neighborhood boundaries at the time of their Wave I, III, IV, and V survey interviews. This contextual database allows researchers to identify potential long-term consequences of redlining for contemporary inequities in neighborhood environments, and individual health and socioeconomic attainment over the life course. Before analyzing these data, however, we urge users to review the following background section and cited references
A survey of educational articles appearing in sixteen popular magazines for an eleven year period from January, 1943 through December, 1953.
Thesis (Ed.M.)--Boston Universit
Heparan Sulfate Domains Required for Fibroblast Growth Factor 1 and 2 Signaling through Fibroblast Growth Factor Receptor 1c
A small library of well defined heparan sulfate (HS) polysaccharides was chemoenzymatically synthesized and used for a detailed structure-activity study of fibroblast growth factor (FGF) 1 and FGF2 signaling through FGF receptor (FGFR) 1c. The HS polysaccharide tested contained both undersulfated (NA) domains and highly sulfated (NS) domains as well as very well defined non-reducing termini. This study examines differences in the HS selectivity of the positive canyons of the FGF12-FGFR1c2 and FGF22-FGFR1c2 HS binding sites of the symmetric FGF2-FGFR2-HS2 signal transduction complex. The results suggest that FGF12-FGFR1c2 binding site prefers a longer NS domain at the non-reducing terminus than FGF22-FGFR1c2. In addition, FGF22-FGFR1c2 can tolerate an HS chain having an N-acetylglucosamine residue at its non-reducing end. These results clearly demonstrate the different specificity of FGF12-FGFR1c2 and FGF22-FGFR1c2 for well defined HS structures and suggest that it is now possible to chemoenzymatically synthesize precise HS polysaccharides that can selectively mediate growth factor signaling. These HS polysaccharides might be useful in both understanding and controlling the growth, proliferation, and differentiation of cells in stem cell therapies, wound healing, and the treatment of cancer
Synthesis of Uridine 5′-diphosphoiduronic Acid: A Potential Substrate for the Chemoenzymatic Synthesis of Heparin
An improved understanding of the biological activities of heparin requires structurally defined heparin oligosaccharides. The chemoenzymatic synthesis of heparin oligosaccharides relies on glycosyltransferases that use UDP-sugar nucleotides as donors. Uridine 5′-diphosphoiduronic acid (UDP-IdoA) and uridine 5′-diphosphohexenuronic acid (UDP-HexUA) have been synthesized as potential analogues of uridine 5′-diphosphoglucuronic acid (UDP-GlcA) for enzymatic incorporation into heparin oligosaccharides. Non-natural UDP-IdoA and UDP-HexUA were tested as substrates for various glucuronosyltransferases to better understand enzyme specificity
Chemoenzymatic Synthesis of Uridine Diphosphate-GlcNAc and Uridine Diphosphate-GalNAc Analogs for the Preparation of Unnatural Glycosaminoglycans
Eight N-acetylglucosamine-1-phosphate and N-acetylgalactosamine-1-phosphate analogs have been synthesized chemically and were tested for their recognition by the GlmU uridyltransferase enzyme. Among these, only substrates that have an amide linkage to the C-2 nitrogen were transferred by GlmU to afford their corresponding uridine diphosphate(UDP)-sugar nucleotides. Resin-immobilized GlmU showed comparable activity to non-immobilized GlmU and provides a more facile final step in the synthesis of an unnatural UDP-donor. The synthesized unnatural UDP-donors were tested for their activity as substrates for glycosyltransferases in the preparation of unnatural glycosaminoglycans in vitro. A subset of these analogs was useful as donors, increasing the synthetic repertoire for these medically important polysaccharides
Restoring shellfish reefs: Global guidelines for practitioners and scientists
Widespread global declines in shellfish reefs (ecosystem-forming bivalves such as oysters and mussels) have led to growing interest in their restoration and protection. With restoration projects now occurring on four continents and in at least seven countries, global restoration guidelines for these ecosystems have been developed based on experience over the past two decades. The following key elements of the guidelines are outlined: (a) the case for shellfish reef resto- ration and securing financial resources; (b) planning, feasibility, and goal set- ting; (c) biosecurity and permitting; (d) restoration in practice; (e) scaling up from pilot to larger scale restoration, (f) monitoring, (g) restoration beyond oyster reefs (specifically mussels), and (h) successful communication for shell- fish reef restoration projects
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Geochemical observations on Hydrate Ridge, Cascadia Margin during R/V BROWN-ROPOS cruise : August 1998
A massive release of methane on the Cascadia Hydrate Ridge was documented
during a ROPOS program in August 1998, consistent with previously reported
observations in 1996. An extensive survey of the seafloor revealed that the
seeps lie within a narrow band trending 109 degrees. This feature parallels larger
mounds imaged by Seabeam as well as larger structures of the accretionary
prism such as the Daisy bank. The area of intense bubbling is characterized by
extensive bacterial mats. Large clam fields were observed ten's of meters away
from the gas seeps. A third province with carbonate blocks but no clams or
bacterial mats was mapped approximately 200 meters away from the seeps. To
constrain fluid flow through the sediments, we deployed 8 osomotic flow meters.
The areas of gas discharge are discrete and highly focussed within conduits with
an approximate cross-sectional area of 5 cm2. We estimate the gas flow rate to
be on the order of 5 liters/minute. While the subsurface plumbing is unknown,
the high flow rate of the sampled gas seep suggests a very short transit time
from the gas source (presumably the base of the BSR at 70 mbsf) to the sea floor. The Rn/CH4 ratio in gas samples collected from the gas vents is very
high, approximately 50 dpm/liter (stp) CH4. Using these values, we estimate
that the time required for the fluids to transit 70 m is approximately 1 hour. To
further constrain the nature of the discharging fluids, we will analyze samples
for their elemental and isotopic composition. Methane hydrate should be stable
at the temperature and pressure conditions at the seafloor on Hydrate Ridge.
Indeed, solid hydrate was observed to form within the gas samplers as well as
on the camera itself, supporting the conclusion that methane is rapidly
transported to the seafloor from beneath the BSR within discrete conduits, most
likely separated from significant amounts of pore water. When discharged at the
seafloor, some of the methane precipitate as hydrate and some continues to rise
within the water column. Bubbles were observed with the ROV up to 50 meters
above the seafloor. This methane generates a plume in the water column, which
was first documented during the 1996 GEOMAR survey. The most pronounced
methane plumes observed during 1998 occur nearest to the active discharge
sites, where methane concentrations up to 800 nmol/l were recorded
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