Control of the Colorado Potato Beetle (Coleoptera: Chrysomelidae) on Tomatoes with \u3ci\u3eBacillus Thuringiensis\u3c/i\u3e Var. \u3ci\u3eThuringiensis\u3c/i\u3e

(excerpt) The Colorado potato beetle, Leptinotarsa decemlineata (Say), is a serious pest of tomatoes grown in this country. This beetle is also developing resistance to several classes of chemical insecticides including most of the carbamates, chlorinated hydrocarbons, and organophosphates (Forgash 1981). and most recently to the pyrethroids. According to figures in a report released by Schwartz and Klassen (1981). the value of the tomato crop in the CSA in 1978 was placed at $914,121,000 and crop loss due to Colorado potato beetle (CPB) damage alone would be 93% of its value if no control were undertaken. These figures along with the fact that the CPB is developing resistance dictate the need for. and development of, alternative control measures

Effect of \u3ci\u3eBeauveria Bassiana\u3c/i\u3e on Underground Stages Of the Colorado Potato Beetle, \u3ci\u3eLeptinotarsa Decemlineata\u3c/i\u3e (Coleoptera: Chrysomelidae)

Tests were conducted to determine the effect of the fungus Beauveria bassiana (B.b.) on underground of the Colorado potato beetle (CPB), Leptinotarsa decemlineata. Two levels of B.h., g/m2 and 75 g/m2 , were suspended in water and sprinkled over the surface of the ground in cages to which CPB were added, either as overwintering adults or as 4th instar larvae of the 15t generation. Efficacy of treatments was determined by counting emerged adults. Neither level of B .b. increased mortality in overwintering adults. The highest level of B.h. caused a significant decline in emergence of adults from the 1st generation 4th instars. The 7.5 g/m2 treatment level did not significantly differ from control treatments

Efficient method for estimating the number of communities in a network

While there exist a wide range of effective methods for community detection in networks, most of them require one to know in advance how many communities one is looking for. Here we present a method for estimating the number of communities in a network using a combination of Bayesian inference with a novel prior and an efficient Monte Carlo sampling scheme. We test the method extensively on both real and computer-generated networks, showing that it performs accurately and consistently, even in cases where groups are widely varying in size or structure.Comment: 13 pages, 4 figure

Characterisation of re-entrant circuit (or rotational activity) in vitro using the HL1-6 myocyte cell line

Fibrillation is the most common arrhythmia observed in clinical practice. Understanding of the mechanisms underlying its initiation and maintenance remains incomplete. Functional re-entries are potential drivers of the arrhythmia. Two main concepts are still debated, the “leading circle” and the “spiral wave or rotor” theories. The homogeneous subclone of the HL1 atrial-derived cardiomyocyte cell line, HL1-6, spontaneously exhibits re-entry on a microscopic scale due to its slow conduction velocity and the presence of triggers, making it possible to examine re-entry at the cellular level. We therefore investigated the re-entry cores in cell monolayers through the use of fluorescence optical mapping at high spatiotemporal resolution in order to obtain insights into the mechanisms of re-entry. Re-entries in HL1-6 myocytes required at least two triggers and a minimum colony area to initiate (3.5 to 6.4 mm2). After electrical activity was completely stopped and re-started by varying the extracellular K+ concentration, re-entries never returned to the same location while 35% of triggers re-appeared at the same position. A conduction delay algorithm also allows visualisation of the core of the re-entries. This work has revealed that the core of re-entries is conduction blocks constituted by lines and/or groups of cells rather than the round area assumed by the other concepts of functional re-entry. This highlights the importance of experimentation at the microscopic level in the study of re-entry mechanisms

Nanometer-scale sharpness in corner-overgrown heterostructures

A corner-overgrown GaAs/AlGaAs heterostructure is investigated with transmission and scanning transmission electron microscopy, demonstrating self-limiting growth of an extremely sharp corner profile of 3.5 nm width. In the AlGaAs layers we observe self-ordered diagonal stripes, precipitating exactly at the corner, which are regions of increased Al content measured by an XEDS analysis. A quantitative model for self-limited growth is adapted to the present case of faceted MBE growth, and the corner sharpness is discussed in relation to quantum confined structures. We note that MBE corner overgrowth maintains nm-sharpness even after microns of growth, allowing the realization of corner-shaped nanostructures.Comment: 4 pages, 3 figure