Spatial and temporal patterns of carabid activity-density in cereals do not explain levels of predation on weed seeds

Seed predation is an important component of seed mortality of weeds in agro-ecosystems, but the agronomic use and management of this natural weed suppression is hampered by a lack of insight in the underlying ecological processes. In this paper, we investigate whether and how spatial and temporal variation in activity-density of granivorous ground beetles (Coleoptera: Carabidae) results in a corresponding pattern of seed predation. Activity-density of carabids was measured by using pitfall traps in two organic winter wheat fields from March to July 2004. Predation of seeds (Capsella bursa-pastoris, Lamium amplexicaule, Poa annua and Stellaria media) was assessed using seed cards at the same sites and times. As measured by pitfall traps, carabids were the dominant group of insects that had access to the seed cards. In the field, predation of the four different species of seed was in the order: C. bursa-pastoris>P. annua>S. media>L. amplexicaule; and this order of preference was confirmed in the laboratory using the dominant species of carabid. On average, seed predation was higher in the field interior compared to the edge, whereas catches of carabids were highest near the edge. Weeks with elevated seed predation did not concur with high activity-density of carabids. Thus, patterns of spatial and temporal variation in seed predation were not matched by similar patterns in the abundance of granivorous carabid beetles. The lack of correspondence is ascribed to effects of confounding factors, such as weather, the background density of seeds, the composition of the carabid community, and the phenology and physiological state of the beetles. Our results show that differences in seed loss among weed species may be predicted from laboratory trials on preference. However, predator activity-density, as measured in pitfall traps, is an insufficient predictor of seed predation over time and space within a fiel

Fluidic Technology and Some Recent Applications to Space and Oceanography

This paper is presented to show the degree of advancements that fluidic technology is making in various technical disciplines. Examples are used and discussed based on the many programs sponsored by the government. The references used here represent only a small percent of the total. Individuals with specific interests or applications can expand the reference list on the choosen subject to take advantage of the considerable amount of advanced research and development already completed

Edge smoothing for real-time simulation of a polygon face object system as viewed by a moving observer

The visual system within an aircraft flight simulation system receives flight data and terrain data which is formated into a buffer memory. The image data is forwarded to an image processor which translates the image data into face vertex vectors Vf, defining the position relationship between the vertices of each terrain object and the aircraft. The image processor then rotates, clips, and projects the image data into two-dimensional display vectors (Vd). A display generator receives the Vd faces, and other image data to provide analog inputs to CRT devices which provide the window displays for the simulated aircraft. The video signal to the CRT devices passes through an edge smoothing device which prolongs the rise time (and fall time) of the video data inversely as the slope of the edge being smoothed. An operational amplifier within the edge smoothing device has a plurality of independently selectable feedback capacitors each having a different value. The values of the capacitors form a series which doubles as a power of two. Each feedback capacitor has a fast switch responsive to the corresponding bit of a digital binary control word for selecting (1) or not selecting (0) that capacitor. The control word is determined by the slope of each edge. The resulting actual feedback capacitance for each edge is the sum of all the selected capacitors and is directly proportional to the value of the binary control word. The output rise time (or fall time) is a function of the feedback capacitance, and is controlled by the slope through the binary control word

'Hear Israel:' The involvement of Jews in education of the deaf

During the last two centuries there has been a methodological struggle over teaching the deaf. Do deaf people learn to communicate by means of gestures and signs (the "manual method") or is it important for them to learn speech and lip-reading (the "oral method")? In the second half of the nineteenth century, many schools for the deaf made the transition from the manual to the oral method, which the Milan conference of teachers of the deaf decided to promote in 1880. In this conversion, Jews played an important role. Yet there appears to be a clear link between their efforts and Jewish tradition, including its perception of the deaf. © 2008 The Author(s)

Sensitivity of Vertebrate Embryos to Heavy Metals as a Criterion of Water Quality, Phase II: Bioassay Procedures Using Developmental Stages as Test Organisms

Chick, amphibian, and fish embryos were evaluated as bioassay and bioindicator organisms. Test procedures were developed by which embryonic stages may be used 1) in bioassay systems to evaluate the toxicity of particular metallic or metal-containing trace contaminants, and 20 as bioindicators to monitor the quality of natural water resources. A bioassay technique was devised in which metallic toxicants were administered to chick embryos by needle tract injection into the yolk sac. This provided more uniform distribution of test metals throughout the yolk mass than can be obtained by conventional yolk sac injection methods, and gave more sensitivity and uniformity of test results. Metals such as arsenic, cadmium, mercury, lead and zinc are easily detectable at a level of 1 ppb. An in vitroculture technique was developed by which embryos of aquatic vertebrates may be maintained for bioassay and bioindicator purposes. Five test species were identified, suitable synthetic culture water was formulated, and culture monitoring procedures were determined. Most toxic metals (e.g., mercury) may be detected at 1ppb or less with the use of more sensitive embryonic species (e.g., trout). Early cleavage stages of the leopard frog (Rana pipiens) proved more sensitive to cadmium than older embryos, similar to results obtained in Phase I with mercury treatment of frog embryos. Early developmental stages, therefore, have proven especially important for use in bioassay and bioindicator systems

Boskoop en Bollenstreek. Hoe innig is de samenwerking

In het kader van de streekplanherziening Zuid-Holland Oost is in opdracht van de provincie Zuid-Holland onderzoek gedaan naar de autonome ontwikkeling van het boomteeltcomplex Boskoop en de interacties met het bloembollencomplex 'De Bollenstreek'. Om het belang van het boomteeltcomplex binnen het sierteeltcomplex Zuid-Holland te duiden zijn ook de interacties met de bloemisterij in kaart gebracht. De interacties tussen Boskoop en de Bollenstreek blijven beperkt tot een gecombineerde afzet van bloembollen en een beperkt assortiment boomteeltproducten, met name vaste planten. Mede door het groeiende belang van de bloemenveilingen in de afzet van boomteeltproducten en de toenemende vraag naar visueel aantrekkelijke boomteeltproducten is de interactie tussen Boskoop en het bloemisterijcomplex Zuid-Holland veel sterker. Vanwege de aanwezigheid van een groot assortiment aan boomteeltproducten, de beschikbaarheid van veel kennis en vakmanschap, korte transportlijnen naar de veilingen en de centrale ligging heeft Boskoop een belangrijke meerwaarde binnen het sierteeltcomplex Zuid-Holland