Preliminary comparison of landscape pattern-normalized difference vegetation index (NDVI) relationships to Central Plains stream conditions

We explored relationships of water quality parameters with landscape pattern metrics (LPMs), land use-land cover (LULC) proportions, and the advanced very high resolution radiometer (AVHRR) normalized difference vegetation index (NDVI) or NDVI-derived metrics. Stream sites (271) in Nebraska, Kansas, and Missouri were sampled for water quality parameters, the index of biotic integrity, and a habitat index in either 1994 or 1995. Although a combination of LPMs (interspersion and juxtaposition index, patch density, and percent forest) within Ozark Highlands watersheds explained >60% of the variation in levels of nitrite-nitrate nitrogen and conductivity, in most cases the LPMs were not significantly correlated with the stream data. Several problems using landscape pattern metrics were noted: small watersheds having only one or two patches, collinearity with LULC data, and counterintuitive or inconsistent results that resulted from basic differences in land use-land cover patterns among ecoregions or from other factors determining water quality. The amount of variation explained in water quality parameters using multiple regression models that combined LULC and LPMs was generally lower than that from NDVI or vegetation phenology metrics derived from time-series NDVI data. A comparison of LPMs and NDVI indicated that NDVI had greater promise for monitoring landscapes for stream conditions within the study area.     

Getting of the seeds-and-tools treadmill with CRS seed vouchers and fairs

The free distribution of seeds and tools is the standard approach to agricultural recovery. The predominance of this approach is partly attributable to the: (1) perception that farmer seed quality is poor, (2) insistence on seed certification, (3) promotion of researcher varieties, (4) misdiagnosis of unavailability, (5) difficulty accessing farmer seed, and (6) support for the commercial seed sector. This paper presents a Seed Security Assessment Framework to distinguish among the causes of seed insecurity and focuses on three principal concepts: seed availability; access to seed; and factors associated with seed utilisation. Using this diagnostic framework, Catholic Relief Services (CRS) has developed a better approach to promoting seed system-based agricultural recovery. It involves a combination of seed voucher distribution and the organization of seed fairs, which bring together a range of sellers from whom the holders of vouchers may purchase seed. This approach is advantageous because it: strengthens farmer seed procurement systems; is cost efficient; in economic terms, has a multiplier effect in the community; is straightforward to plan and implement; allows commercial sector participation; provides an opportunity to promote improved varieties for farmer evaluation; brings together different communities.     

Caste and division of labor in leaf-cutter ants (Hymenoptera: Formicidae: Atta)

Summary Leaf cutting was selected for an evaluation of ergonomic efficiency in the fungus-growing ant Atta sexdens because it is performed largely by medias (head width 1.8–2.8 mm), which attend to relatively few other functions and hence are less likely to be evolutionarily compromised by the demands of competing tasks (Fig. 1).Three alternative a priori criteria of evolutionary optimization were envisioned that are consistent with natura selection theory: the reduction of predation by means of defense and evasion during foraging, the minimization of foraging time through skill and running velocity during foraging, and energetic efficiency, which must be evaluated with reference to both the energetic construction costs of new workers and the energetic cost of maintenance of the existing worker force.In order to measure the performance of various size groups within the A. sexdens worker caste in isolation, I devised the pseudomutant technique: in each experiment, groups of foraging workers were thinned out until only individuals of one size class were left outside the nest. Measurements were then made of the rate of attraction, initiative in cutting, and performance of each size group at head-width intervals of 0.4 mm (Figs. 2, 3, and 7). Other needed measurements were made in body weight, oxygen consumption, and running velocity (Figs. 5, 6, and 8).The size-frequency distribution ff leaf cutters in the A. sexdens conforms closely to the optimum predicted by the energetic efficiency criterion for harder forms of vegetation, such as rhododendron leaves. The distribution is optimum with reference to both construction and maintenance costs. The difference between the predicted and actual modal size groups specializing on leaf cutting is 10% or less of the total size range of the sexdens worker caste.A model was next constructed in which attraction and initiative were allowed to evolve genetically to uniform maximum levels. The theoretical maximum efficiency levels obtained by this means were found to reside in the head-width 2.6–2.8 mm size class, or 8% from the actual maximally efficiency class (head width 2.2–2.4 mm). In the activity of leaf cutting, A. sexdens can therefore be said to be not only at an adaptive optimum but also, within at most a relatively narrow margin of error, to have been optimized in the course of evolution.     

Determination of 99Tc, 63Ni and 121m+126Sn in the marine environment

Four artificially produced radionuclides (${}^{99}\text{Tc, t}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}\text{= 2·15 × 10}{}^5\text{y;}{}^{63}\text{Ni, t}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}\text{= 93 y}$ and ${}^{\mathrm{121m+126}}\text{Sn, t}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}\text{= 55·5 y}$) have been analyzed in sediments and organisms from the marine environment. The samples were obtained from the vicinities of nuclear energy facilities, at sites of nuclear weapon tests and at sites remote from both of these locales. The activities of these nuclides per unit dry weight are remarkably similar at the first two of the above areas but are usually detectable only with difficulty, if at all, in the third area. Techniques for sample treatment and measurement are given.     

Atmospheric BTEX-concentrations in an area with intensive street traffic

The major threat to clean air in developed and industrializing countries is now posed by traffic emissions. The effects of traffic road modifications on the air quality are, however, rarely reported in the literature. The aim of this study was to determine the influence of the modernization and renovation of a traffic artery in the region of Mortsel (Antwerp, Belgium) on the concentration of volatile organic compounds such as: benzene, toluene, ethylbenzene and m-, p-, o-xylenes (BTEX). The original goal of the reconstruction works was to reduce the traffic lanes of one of the busiest streets in Antwerp, in order to discourage the road traffic and in consequence also to improve the air quality in this region. The average concentrations of BTEX before these works in 2003 were: 1.6, 7.0, 0.9, 2.3, and 0.9 μg/m³, for benzene, toluene, ethylbenzene, m + p xylenes, and o-xylene, respectively. However, after the completion of the works, in 2005, they were slightly higher: 2.5, 9.5, 1.6, 3.4, and 1.3 μg/m³, respectively. The scatter plots of benzene against toluene, ethylbenzene and xylenes in 2003 and 2005 showed very good correlations. This fact indicated that all of the measured compounds originated from the same source, namely the road traffic. Moreover, the data obtained from an air-monitoring station at less than 6 km distance from the sampling site (operated by the Flemish Environment Agency, and located in Borgerhout, Antwerp), confirmed the lack of influence of background concentrations of BTEX. The obtained results led to the conclusion that the reduction of the number of traffic lanes had apparently increased the traffic jams and also increased the emission from cars. Therefore, these modernization works had even a negative impact on the local concentration of traffic-related pollutants as BTEX.     

Selection for male choice based primarily on mate compatibility in the oldfield mouse, Peromyscus polionotus rhoadsi

Despite the consensus that mate choice acts as a mechanism for selection of secondary sexual traits, the evolutionary forces affecting mate preferences themselves remain controversial. In this study, we first demonstrated selection acting directly on the mate preferences of monogamous male oldfield mice, Peromyscus polionotus rhoadsi. One group of male oldfield mice were allowed to express a social preference between two potential mates, and were subsequently paired with either their preferred or rejected female. Among these pairs, those containing preferred females produced more offspring than did those containing rejected females. We next demonstrated that this fitness advantage depended primarily on compatibility between the members of a mated pair. A second group of male oldfield mice were not allowed the opportunity to express a social preference between potential mates. Rather, these males were paired with females that had been either preferred or rejected by males in the first group. Among these pairs, those containing preferred females did not produce more offspring than those containing rejected females. In other words, individual mate preferences had fitness consequences only for those males that expressed them, demonstrating that these preferences were based primarily on compatibility between mates.     

Quantification of source-level turbulence during LNG spills onto a water pond

The use of computational fluid dynamics (CFD) models to simulate LNG vapor dispersion scenarios has been growing steadily over the last few years, with applications to LNG spills on land as well as on water. Before a CFD model may be used to predict the vapor dispersion hazard distances for a hypothetical LNG spill scenario, it is necessary for the model to be validated with respect to relevant experimental data. As part of a joint-industry project aimed at validating the CFD methodology, the LNG vapor source term, including the turbulence level associated with the evaporation process vapors was quantified for one of the Falcon tests.This paper presents the method that was used to quantify the turbulent intensity of evaporating LNG, by analyzing the video images of one of the Falcon tests, which involved LNG spills onto a water pond. The measured rate of LNG pool growth and spreading and the quantified turbulence intensity that were obtained from the image analysis were used as the LNG vapor source term in the CFD model to simulate the Falcon-1 LNG spill test. Several CFD simulations were performed, using a vaporization flux of 0.127 kg/m² s, radial and outward spreading velocities of 1.53 and 0.55 m/s respectively, and a range of turbulence kinetic energy values between 2.9 and 28.8 m²/s². The resulting growth and spread of the vapor cloud within the impounded area and outside of it were found to match the observed behavior and the experimental measured data.The results of the analysis presented in this paper demonstrate that a detailed and accurate definition of the LNG vapor source term is critical in order for any vapor cloud dispersion simulation to provide useful and reliable results.     

Fabric filters versus electrostatic precipitators

Control of particulate emissions from pulverized coal fired steam generators is becoming a significant factor in the siting and public acceptability of large coal burning power plants. The particulate emission limit established by the EPA for new coal fired boilers is 0.03 lb/10⁶ Btu (13 ng/J) Possibly more restrictive than this is the state of New Mexico's particulate regulation which calls for no more than 0.05 lb/10⁶ Btu (22 ng/J) total, and no more than 0.02 lb/10⁶ Btu (9 ng/J) less than 2 microns in diameter. This paper will evaluate the effect of these stringent limitations on the technical feasibility and economics of dry particulate removal. Electrostatic precipitators have been the dominant particulate collection device in the electric utility industry for many years because of their low capital and operating cost. However, increasingly stringent emission standards have led to substantially higher costs for precipitators. These costs have increased sufficiently for fabric filtration to become a competitive alternative in achieving cost effective control. This paper will compare the economics and performance of fabric filtration with respect to conventional electrostatic precipitators. The paper will also address the preliminary evaluation procedures that should be followed in order to select the appropriate device for new or existing coal-fired boilers.