Sites In New England Research Articles

A Monte Carlo approach to seismic hazard analysis

AbstractWe have developed a Monte Carlo methodology for the estimation of seismic hazard at a site or across an area. This method uses a multitudinous resampling of an earthquake catalog, perhaps supplemented by parametric models, to construct synthetic earthquake catalogs and then to find earthquake ground motions from which the hazard values are found. Large earthquakes extrapolated from a Gutenberg-Richter recurrence relation and characteristic earthquakes can be included in the analysis. For the ground motion attenuation with distance, the method can use either a set of observed ground motion observations from which estimates are randomly selected, a table of ground motion values as a function of epicentral distance and magnitude, or a parametric ground motion attenuation relation. The method has been tested for sites in New England using an earthquake catalog for the northeastern United States and southeastern Canada, and it yields reasonable ground motions at standard seismic hazard values. This is true both when published ground motion attenuation relations and when a dataset of observed peak acceleration observations are used to compute the ground motion attenuation with distance. The hazard values depend to some extent on the duration of the synthetic catalog and the specific ground motion attenuation used, and the uncertainty in the ground motions increases with decreasing hazard probability. The program gives peak accelerations that are comparable to those of the 1996 U.S. national seismic hazard maps. The method can be adapted to compute seismic hazard for cases where there are temporal or spatial variations in earthquake occurrence rates or source parameters.

A Summary of Airborne Concentrations of Sulfur- and Nitrogen-Containing Pollutants in the Northeastern United States

ABSTRACT Airborne concentrations of SO2, SO4 2-, HNO3, NO3 -, NH4+, and O3 were monitored over the six-year period from September 1, 1989, through August 31, 1995, at 10 largely rural Clean Air Status and Trends Network (CASTNet) sites in the northeastern United States. Each of the sulfur- and nitrogen-containing air pollutants monitored by CASTNet displays regular, seasonal cyclical behavior and also exhibits a relatively strong high-to-low spatial concentration gradient from southwest to northeast. On average, more than 70% of the measured airborne sulfur is present as SO2, except during the summer, when the figure drops to about 50%. During the summer, the SO2 concentration is the lowest, SO4 2- is the highest, and the fraction of airborne sulfur present as SO4 2- varies considerably with location, ranging from an average of 42% at five sites in Pennsylvania to 70% at two sites in New England. Studywide, more than 70% of the measured, oxidized, airborne nitrogen (N) is present as HNO3, except during the winter, when the figure drops to about 60%. The concentrations of gaseous SO2 and HNO3 are usually comparable but not always larger than the corresponding concentrations of measured sulfur and nitrogen aerosols. Nevertheless, the relatively faster deposition velocities for gases are sufficient to ensure that SO2 and HNO3 are usually the dominant contributors to dry sulfur and nitrogen deposition. Observed changes of 1990–1995 annual average airborne sulfur and N concentrations at 10 CASTNet sites in the Northeast are generally consistent with changes in emissions estimated to have occurred in the Northeast over the same period.

INCIDENCE OF AUTOTOMY IN NEW ENGLAND POPULATIONS OF GREEN CRABS, CARCINUS MAENAS, AND AN EXAMINATION OF THE EFFECT OF CLAW AUTOTOMY ON DIET

ABSTRACT Like other decapod crustaceans, the green crab Carcinus maenas can actively amputate limbs by the process of autotomy. The loss of limbs may have consequences for the future fitness of an individual, since it is likely to impose energetic costs, including a reduced foraging efficiency. This study examined the occurrence of limb loss and the effects of claw autotomy on the diet of green crabs. Green crabs were collected from May-October 1995 from sites in New England. All crabs (N = 1,504) were examined in the field, and 402 adult crabs (>30 mm wide) were included in the analysis of gut contents. Overall, females experienced more injuries (38.4% missing at least I limb, N = 277; 17.89% missing 1 or both claws, N = 129) than males (32.18% missing at least 1 limb, N = 252; 14.8% missing 1 or both claws, N = 116). The overall incidence of autotomy generally increased with increasing crab size. but the incidence of claw autotomy did not. The most common identifiable materials in the guts were the hard parts of molluscs, arthropods, and annelids. The contents of the guts differed between sites, but was not significantly different for crabs missing claws than for intact crabs. Thus, the loss of a single claw does not seem to alter crab diet.

Inadequate management of blood pressure in a hypertensive population.

Many patients with hypertension have inadequate control of their blood pressure. Improving the treatment of hypertension requires an understanding of the ways in which physicians manage this condition and a means of assessing the efficacy of this care. We examined the care of 800 hypertensive men at five Department of Veterans Affairs sites in New England over a two-year period. Their mean (+/-SD) age was 65.5+/-9.1 years, and the average duration of hypertension was 12.6+/-5.3 years. We used recursive partitioning to assess the probability that antihypertensive therapy would be increased at a given clinic visit using several variables. We then used these predictions to define the intensity of treatment for each patient during the study period, and we examined the associations between the intensity of treatment and the degree of control of blood pressure. Approximately 40 percent of the patients had a blood pressure of > or =160/90 mm Hg despite an average of more than six hypertension-related visits per year. Increases in therapy occurred during 6.7 percent of visits. Characteristics associated with an increase in antihypertensive therapy included increased levels of both systolic and diastolic blood pressure at that visit (but not previous visits), a previous change in therapy, the presence of coronary artery disease, and a scheduled visit. Patients who had more intensive therapy had significantly (P<0.01) better control of blood pressure. During the two-year period, systolic blood pressure declined by 6.3 mm Hg among patients with the most intensive treatment, but increased by 4.8 mm Hg among the patients with the least intensive treatment. In a selected population of older men, blood pressure was poorly controlled in many. Those who received more intensive medical therapy had better control. Many physicians are not aggressive enough in their approach to hypertension.

Use of formerly plowed land in New England to monitor the vertical distribution of lead, zinc and copper in mineral soil

In this study, we used once-plowed lands that have returned to forest for over 50 years to study the vertical distribution of meteorologically-deposited lead. These mineral soils were an essentially homogeneous 20 cm-thick layer when last plowed. As such, they were effectively a “clean slate” upon which pollutants deposited since the last plowing can be measured without the confounding aspects of well-developed natural soil horizons and the spatial heterogeneity of native forest soils. The concentration and amount of lead as well as copper and zinc, biologically active metals, were measured at five sites in New England. In the mineral soil, copper content ranged from 25 mg cm depth−1 m−2 at 0–2 cm depth to 37 mg cm depth−1 m−2 at 6–8 cm depth, but showed no consistent pattern with depth at all sites. Zinc concentrations and amounts increased with depth in the mineral soil to 14 μg g−1 and 167 mg cm depth−1 m−2, respectively. In contrast, lead showed a decrease with depth from 350 mg cm depth−1 m−2 at 0–2 cm depth to 102–108 mg cm depth−1 m−2 between 10 and 20 cm depth. At all five sites, decreases in lead concentration with depth were correlated with decreases in the amount of organic mater. Amounts of total lead deposited since the abandonment from plowing have been estimated at 1.4 g m-2 in rural sites. Thirty-five percent of this presumably anthropogenically-derived lead was in the forest floor; the remaining 65 % was in the upper mineral soil.

Electric-hydraulic conductivity correlation in fractured crystalline bedrock: Central Landfill, Rhode Island, USA

Remote sensing and geoelectrical methods were used to find water-bearing fractures in the Scituate granite under the Central Landfill of Rhode Island. These studies were necessary to evaluate the integrity of the sanitary landfill and for planning safe landfill extensions. The most useful results were obtained with fracture trace analysis using Landsat and SLAR imagery in combination with ground-based resistivity measurements using Schlumberger vertical electrical soundings based on the assumption of horizontally layered strata. Test borings and packer tests confirmed, in the presence of a lineament and low bedrock resistivity, the probable existence of high bedrock fracture density and high average hydraulic conductivity. However, not every lineament was found to be associated with high fracture density and high hydraulic conductivity. Lineaments alone are not a reliable basis for characterising a landfill site as being affected by fractured bedrock. Horizontal fractures were found in borings located away from lineaments. High values of hydraulic conductivity were correlated with low bedrock resistivities. Bedrock resistivities between 60 and 700 Ω m were associated with average hydraulic conductivities between 4 and 60 cm/day. In some cases very low resistivities were confined to the upper part of the bedrock where the hydraulic conductivity was very large. These types of fractures apparently become narrower in aperture with depth. Bedrock zones having resistivities greater than 1000 Ω m showed, without exception, no flow to the test wells. Plots of bedrock resistivity versus the average hydraulic conductivity indicate that the resistivity decreases with increasing hydraulic conductivity. This relationship is inverse to that found in most unconsolidated sediments and is useful for estimating the hydraulic conductivity in groundwater surveys in fractured bedrock. In appropriate settings such as the Central Landfill site in New England, this electric-hydraulic correlation relationship, supplemented by lineament trace analysis, can be used effectively to estimate the hydraulic conductivity in bedrock from only a limited number of resistivity depth soundings and test wells.

96/04419 Mitigation of methane emissions at landfill sites in New England, USA

96/04419 Mitigation of methane emissions at landfill sites in New England, USA

Mitigation of methane emissions at landfill sites in New England, USA

Field measurements of methane emissions from landfills are essential if one is to accurately constrain uncertainties in current estimates of global methane emissions from landfills and document emissions reductions realized by currently available control technology. Two experimental techniques for the measurement of methane flux from landfills, flux chamber measurements and tracer flux techniques, have been evaluated at a 24 hectare landfill site in New England. Agreement between the two techniques was quite good, with the flux chamber technique giving a landfill wide methane flux of 16.4 m 3 CH 4 min −1 while a series of seven tracer flux tests resulted in a mean flux of 17.8 m 3 CH 4 min −1. Model estimates suggest that the installation of gas recovery measures at the five largest landfill sites in the state of New Hampshire and the ten largest sites in Massachusetts would reduce landfill emissions in each state by approximately 75%, resulting in a total emissions reduction of 65 × 10 9 g CH 4/yr.

Comorbidity of anxiety disorders in a multicenter anxiety study

From 11 sites in New England and Missouri, 711 patients with ≥ one of five index anxiety disorders were recruited onto a longitudinal study in which they were interviewed every 6 months regarding symptoms, course, and treatments received. Of the five disorders studied, panic disorder without agoraphobia was the disorder most often found as a sole diagnosis and generalized anxiety disorder (GAD) was least often found alone, both as lifetime diagnoses or when restricted to cases active at intake. Panic disorder with agoraphobia and agoraphobia without history of panic disorder (AWOPD) had three specific diagnoses with which they were frequently comorbid: social phobia, simple phobia, and GAD. AWOPD, social phobia, and GAD were frequently found in the presence of each other. It is possible that the experience of anxiety due to any syndromal cause may decrease the threshold for an individual to experience other anxiety symptoms or disorders. Clinicians should be aware of these patterns of comorbidity in order to formulate accurate differential diagnoses and prescribe treatments in a rational manner.

The Ordered-Heterogeneity Family of Tests

SUMMARY A new testing procedure is described concerning ordered alternative hypotheses when three or more populations are categorized by class. The test is specifically designed for use in complex testing applications frequently found in biological research where the isotonic regression and JonckheereTerpstra test cannot readily be applied. The test has both parametric and nonparametric applications. Significance tables for the test are provided for both large and small sample sizes, and a power analysis relative to isotonic regression is described for the case of the one-way layout. The problem of testing ordered alternative hypotheses in the context of comparing several populations is common in biological research. The techniques of isotonic regression [reviewed in Barlow et al. (1972); Robertson, Wright, and Dykstra (1988)] and the Jonckheere-Terpstra test [reviewed in Hollander and Wolfe (1973)] have been developed for the context of the one-way layout, but these techniques frequently cannot be pragmatically applied in more complex biological applications. The reasons for this are twofold. First, it is common in biological research to test ordered alternatives in the context of complex designs where concomitant variates require the use of multi-way contingency, ANOVA, ANCOVA, or mixed-effects ANOVA models. An example of this situation from our own research concerns filter feeders in marine ecosystems and the identification of the factors that cause variation in demographic parameters both among and within populations. Many marine invertebrates capture microscopic food with appendages that act like nets. Their feeding rate is therefore a flux that may depend on the concentration of particles in the water and its velocity. These two components of particle flux can vary dramatically among sites and microhabitats. This should lead to predictable variation in growth rates and other demographic parameters. We have measured growth rates of transplanted barnacles from a common source population at numerous sites in New England and within particular microhabitats at each site (tidal height, which varies the amount of time barnacles are submerged and can feed, and exposure to waves, which alters velocities). The experimental design is a three-way repeated-measures ANCOVA, with initial body size serving as a covariate. All three factors have a priori expectations on HA. Sites are ordered by their predicted ranks in particle concentrations. Tidal heights are ordered by their ranked period of submergence (low zone > mid zone > high zone). Orientations are ordered by their expected ranked velocities (exposed > intermediate > protected). Although the isotonic regression and Jonckheere-Terpstra test can be extended to two-factor designs, they are not easily applied to more complex models such as this. Second, biologists have been, and will continue to be, confronted with a broad spectrum of new k-sample heterogeneity tests. Many of these represent specialized extensions of ANOVA- and ANCOVA-like statistical models and do not evaluate ordered alternative hypotheses, despite the fact that a priori ordering is commonly implicit in the hypotheses biologists seek to test [see for review Gaines and Rice (1990)]. The null distributions of the test statistics for these tests are frequently idiosyncratic and complex. For example, Excoffier, Smouse, and Quattro (1992) describe

A pressure-packer system for conducting rising head tests in water table wells

The pressure system developed for fully-saturated well screens has been modified for conducting rising head tests in water table wells installed in highly permeable aquifers. The pressure system consists of a compressed air source and 1 inch diameter PVC piping with a packer attached at the end. The pressure system was evaluated in a series of rising head tests conducted in a well at a Superfund site in New England. The well was tested with slugs and with the pressure system. Within each technique, estimates of hydraulic conductivity showed no difference. Comparison of hydraulic conductivity estimates between techniques (slug test vs. pressure test) showed differences due to stratigraphy. The interval tested using slug tests crossed two stratigraphic units; the pressure system tested only one of these units. We conclude that the pressure system may be used to characterize the vertical hydraulic conductivity distribution in a series of successive tests by changing the packer position and the screened interval tested.

Did New England Go Downhill?

Did New England Go Downhill?

The Population Biology of the Genus Viola: I. The Demography of Viola Sororia

(1) A census of all plants of Viola sororia 1-yr-old or older was carried out at regular intervals over an 8-yr period in a forest site in New England. Over a 2-yr period seedlings were similarly recorded, and each leaf and reproductive structure on twenty selected plants was marked and its fate recorded at weekly intervals. (2) Calculations were made of population flux, age distribution, survivorship and life expectancy of 1-yr-old or older plants, and of seedlings. (3) Fluctuation in population size was small compared to the number of individual plants gained and lost in the population. There was a remarkably constant annual death risk, superimposed upon a seasonal cycle, May-September being a period of greater mortality than the winter months when the plants were inactive. (4) The life expectancy of a 1-yr-old plant was over 10 yr. While seedlings and adult plants exhibited a Deevey type-III mortality curve, leaves had a Deevey type-I curve. (5) It was also established that seedling survival and production-probability are a function of plant size; the relationship is exponential in the case of seed production. It is suggested that individual plant size is regulated by competition for environmental resources.

Late Pleistocene magnetic stratigraphy recorded in some New England tills

Magnetic remanence data from six till sites in New England indicate that the predominant late Pleistocene till types found in southern and central New England can be differentiated on the basis of statistically distinct virtual geomagnetic poles (VGPs). The lower till records an excursion (VGP = lat. 27.7° N, long. 165.2° E) tentatively correlated with the Lake Mungo excursion dated at approximately 32,000 years BP. The use of characteristic remanence is suggested for dating of tills in New England where other conventional methods cannot be applied.

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.

Power plant siting: A paretian environmental approach

Several different interest groups are involved in the siting decision process for nuclear power plants. Their inputs and how the final decision affects them are usually not explicitly included in mathematical analyses. Paretian analysis is a technique which attempts to identify the preferences of each of the interest groups involved in the decision-making process, and to illuminate the trade-offs among these groups. The specific problem studied is the deployment by a regional power plant siting agency of nuclear base-load power plants to coastal sites in New England. Four interest groups participate in power plant siting decisions; utility functions can represent their preferences. Techniques to find Pareto-admissible decisions are described.