The Economic Argument for Cleaning Up the Chesapeake Bay and its Rivers

Failure to "Save the Bay" threatens the Bay's value as an economic driver. Conversely, investing in clean-water technology creates jobs, generates economic activity, and saves money in the long run. Hence, the protection and restoration of the Chesapeake is essential for a healthy and vibrant regional economy. This CBF report takes a close look at the relationship between clean water and the Bay region's local economies

Bad Water 2009: The Impact on Human Health in the Chesapeake Bay Region

The report links pollution to human health risks and calls on the federal Environmental Protection Agency (EPA) to act now to reduce that pollution and the potential threats to human health

On the Brink: Chesapeake's Native Oysters

This CBF report finds that Chesapeake Bay oysters are developing natural resistance to the diseases that have so devastated the Bay's oyster population in recent decades and calls for additional sanctuaries to repopulate the species

An Efficient Source of Single Photons: A Single Quantum Dot in a Micropost Microcavity

We have demonstrated efficient production of triggered single photons by coupling a single semiconductor quantum dot to a three-dimensionally confined optical mode in a micropost microcavity. The efficiency of emitting single photons into a single-mode travelling wave is approximately 38%, which is nearly two orders of magnitude higher than for a quantum dot in bulk semiconductor material. At the same time, the probability of having more than one photon in a given pulse is reduced by a factor of seven as compared to light with Poissonian photon statistics

Optimization of three-dimensional micropost microcavities for cavity quantum electrodynamics

This article presents a detailed analysis, based on the first-principles finite-difference time-domain method, of the resonant frequency, quality factor (Q), mode volume (V), and radiation pattern of the fundamental (HE11) mode in a three-dimensional distributed-Bragg-reflector (DBR) micropost microcavity. By treating this structure as a one-dimensional cylindrical photonic crystal containing a single defect, we are able to push the limits of Q/V beyond those achievable by standard micropost designs, based on the simple rules established for planar DBR microcavities. We show that some of the rules that work well for designing large-diameter microposts (e.g., high-refractive index contrast) fail to provide high-quality cavities with small diameters. By tuning the thicknesses of mirror layers and the spacer, the number of mirror pairs, the refractive indices of high and low refractive index regions, and the cavity diameter, we are able to achieve Q as high as 10^4, together with a mode volume of 1.6 cubic wavelengths of light in the high-refractive-index material. The combination of high Q and small V makes these structures promising candidates for the observation of such cavity quantum electrodynamics phenomena as strong coupling between a quantum dot and the cavity field, and single-quantum-dot lasing.Comment: 11 pages, 8 figure

Rider Preferences and Values of Equestrian Trail Characteristics in Kentucky

A conjoint analysis of equestrian trail characteristics (trail length, scenic views, open land, bathroom/shower facilities, restricted use, distance, and entrance fee) is conducted for the state of Kentucky. The conditional logit results show location is an important determiner of willingness to pay. In particular, scenic views and restricted use are highly valued (WTP above $20). However, increased distance from home to the trail results in a negative willingness to pay.Equestrian trail characteristics, Conditional logit, Conjoint analysis, Environmental Economics and Policy,

A Study of Seed Dormancy in Eighteen Species of High Altitude Colorado Plants

The investigation reported below involves experimental work dealing with the occurrence and type of seed dormancy exhibited by a number of plants collected at high altitudes in Colorado. The objectives of the work include contributing to an understanding of the autecology of the species studied, as well as aiding in an evaluation of the ecological significance of seed dormancy itself. Collections were made during July and August of 1953 at two localities in Colorado: The Rocky Mountain Biological Laboratory north of Gunnison in the Elk Mountains of south-central Colorado (Gunnison County); and near the former University of Colorado Science Lodge, now the Arctic-Alpine Institute, west of Boulder in the Front Range of Colorado (Boulder County). These localities will be referred to below as R.M.B.L. and Alpine Institute, respectively. The altitudes at which collections were made ranged within what is usually considered to be climatically subalpine in Colorado, the lowest collection being at 9200 feet and the highest at 10,000 feet elevation

A Survey of the Ecology of Tecoma stans

Tecoma stans (L.) Juss. ex H.B.K., a shrub or small tree in the Bignoniaceae, is a widely distributed polymorphic complex of the Western Hemisphere tropics and subtropics, and is commonly planted as an ornamental throughout the tropical world. Winter temperature limits its poleward distribution. The species is characteristic of rocky slopes, often limestone outcrops, but also alluvial and other substrata as long as drainage is excellent. In arid regions it occurs in climax xerophytic shrub or thorn forest communities, while in humid areas it is common mainly in deforested and other disturbed sites since it behaves as a heliophyte. The large yellow funnel-form flowers are pollinated by hummingbirds and perhaps also by some insects. The sensitive lobed stigma may favor cross-pollination, and neither dichogamy nor autogamy are usually shown. Extra-floral calyx nectaries which attract ants seem ineffective against corolla-base piercers. A low percentage of fruit is commonly set, drought and pollination failure probably being contributing factors. The pendant capsules contain many paper-thin wind-dispersed winged seeds, which have moderately high viability undiminished even after four years, and no dormancy. The strongly tap-rooted seedlings are often abundant in disturbed sites. The leaflet size class is microphyllous, and the species varies from evergreen to winter deciduous. It responds to drought partly by leaf abscission, but also by survival of prolonged permanent wilting, unusual for a thin-leaved mesomorph. Stump-sprouting is vigorous following cutting or fire, and browsing occurs in heavily-used pastures. No insect parasites or diseases are generally limiting

Triggered single photons from a quantum dot

We demonstrate a new method for generating triggered single photons. After a laser pulse generates excitons inside of a single quantum dot, electrostatic interactions between them and the resulting spectral shifts allow a single emitted photon to be isolated. Autocorrelation measurements show a reduction of the two-photon probability to 0.12 times the value for Poisson light. Strong anti-bunching persists when the emission is saturated. The emitted photons are also polarized.Comment: 4 pages, 4 figures, RevTex, to be published in PR