45,328 research outputs found
Field Tests of Kairomones to Increase Parasitism of Spruce Budworm (Lepidoptera: Tortricidae) Eggs by \u3ci\u3eTrichogramma\u3c/i\u3e Spp. (Hymenoptera: Trichogrammatidae)
Hexane extracts of spruce budworm, Choristoneura fumiferana, moth scales, applied at 0.04 moth-gram equivalents/branch and at 0.06 moth-gram equivalents/tree, failed to increase parasitism rates of Trichogramma spp. in two cutover spruce-fir stands in Maine. Releasing Maine-strain T. minutum apparently increased parasitism rates about 20-fold. However, application of kairomone extracts to whole branches and to upper crowns of small trees may have interfered with host-searching behaviors of Trichogramma parasitoids
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The impact of resolution on the adjustment and decadal variability of the Atlantic Meridional Overturning Circulation in a coupled climate model
Variations in the Atlantic Meridional Overturning Circulation (MOC) exert an important influence on climate, particularly on decadal time scales. Simulation of the MOC in coupled climate models is compromised, to a degree that is unknown, by their lack of fidelity in resolving some of the key processes involved. There is an overarching need to increase the resolution and fidelity of climate models, but also to assess how increases in resolution influence the simulation of key phenomena such as the MOC.
In this study we investigate the impact of significantly increasing the (ocean and atmosphere) resolution of a coupled climate model on the simulation of MOC variability by comparing high and low resolution versions of the same model. In both versions, decadal variability of the MOC is closely linked to density anomalies that propagate from the Labrador Sea southward along the deep western boundary. We demonstrate that the MOC adjustment proceeds more rapidly in the higher resolution model due the increased speed of western boundary waves. However, the response of the Atlantic Sea Surface Temperatures (SSTs) to MOC variations is relatively robust - in pattern if not in magnitude - across the two resolutions. The MOC also excites a coupled ocean-atmosphere response in the tropical Atlantic in both model versions. In the higher resolution model, but not the lower resolution model, there is evidence of a significant response in the extratropical atmosphere over the North Atlantic 6 years after a maximum in the MOC. In both models there is evidence of a weak negative feedback on deep density anomalies in the Labrador Sea, and hence on the MOC (with a time scale of approximately ten years). Our results highlight the need for further work to understand the decadal variability of the MOC and its simulation in climate models
Electrical power system design for the US space station
The multipurpose, manned, permanent space station will be our next step toward utilization of space. A multikilowatt electrical power system will be critical to its success. The power systems for the space station manned core and platforms that have been selected in definition studies are described. The system selected for the platforms uses silicon arrays and Ni-H2 batteries. The power system for the manned core is a hybrid employing arrays and batteries identical to those on the platform along with solar dynamic modules using either Brayton or organic Rankine engines. The power system requirements, candidate technologies, and configurations that were considered, and the basis for selection, are discussed
Perceived Family Life Quality in Junior Secondary School Students in Hong Kong
The file attached to this record is the author's final peer reviewed version. The Publisher's final version can be found by following the DOI link.The present longitudinal study examined perceived family functioning and related socio-demographic correlates from the perspective of adolescents in Hong Kong. Results showed that adolescent perceptions of family functioning based on different indicators gradually deteriorated over time. Regarding the socio-demographic correlates, (a) boys had more favourable perceived family functioning than did girls; (b) adolescents from non-intact families had poorer perceived family functioning than those from intact families; and (c) economically disadvantaged adolescents had poorer perceived family functioning than non-economically disadvantaged adolescents. Results also revealed that adolescents’ perceived family functioning was positively related to positive youth devel- opment. Analyses further indicated that perceived family functioning and positive youth development were concurrently and longitudinally related
BEYOND GATEWAY CITIES: ECONOMIC RESTRUCTURING AND POVERTY AMONG MEXICAN IMMIGRANT FAMILIES AND CHILDREN
Our main objective is to better understand how new residential patterns have reshaped patterns of poverty among America's growing Mexican-origin population. We use data from the Integrated Public Use Microdata Samples (IPUMS) to document recent changes in poverty rates among native-born and foreign-born Mexicans living in the Southwest and in new regions where many Mexican families have resettled. Our analysis focuses on how changing patterns of employment (e.g., in construction and food processing industries) have altered the risk of poverty among Mexican families and children. We demonstrate that the Mexican population dispersed widely throughout the United States during the 1990s. Perhaps surprisingly, Mexican workers, especially new immigrants, had much lower rates of poverty in the new destination regions and rural areas than their counterparts that remained in traditional areas of population concentration - the Southwest. As we show in this study, the dispersion of America's Mexican native-born and immigrant populations raises questions and hopes about their economic and political incorporation into American society.Food Security and Poverty,
Predation by Amphibians and Small Mammals on the Spruce Budworm (Lepidoptera: Tortricidae)
Stomach-content analyses of pitfall-trapped amphibians and small mammals showed that the eastern American toad, Bujo americanus americanus, and the wood frog, Rana sylvatica, preyed on late instars and moths of the spruce budworm, Choristoneura fumiferana. The spotted salamander, Ambystoma maculatum, and the masked shrew, Sorex cinereus, also preyed on late instars of the spruce budworm
Competition between Electromagnetically Induced Transparency and Raman Processes
We present a theoretical formulation of competition among electromagnetically
induced transparency (EIT) and Raman processes. The latter become important
when the medium can no longer be considered to be dilute. Unlike the standard
formulation of EIT, we consider all fields applied and generated as interacting
with both the transitions of the scheme. We solve Maxwell equations
for the net generated field using a fast-Fourier-transform technique and obtain
predictions for the probe, control and Raman fields. We show how the intensity
of the probe field is depleted at higher atomic number densities due to the
build up of multiple Raman fields.Comment: 3.5 pages, 7 figure
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