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1.
D. M. Suckling R. W. Peck L. M. Manning L. D. Stringer J. Cappadonna A. M. El-Sayed 《Journal of chemical ecology》2008,34(12):1602-1609
Disruption of Argentine ant trail following and reduced ability to forage (measured by bait location success) was achieved
after presentation of an oversupply of trail pheromone, (Z)-9-hexadecenal. Experiments tested single pheromone point sources and dispersion of a formulation in small field plots. Ant
walking behavior was recorded and digitized by using video tracking, before and after presentation of trail pheromone. Ants
showed changes in three parameters within seconds of treatment: (1) Ants on trails normally showed a unimodal frequency distribution
of walking track angles, but this pattern disappeared after presentation of the trail pheromone; (2) ants showed initial high
trail integrity on a range of untreated substrates from painted walls to wooden or concrete floors, but this was significantly
reduced following presentation of a point source of pheromone; (3) the number of ants in the pheromone-treated area increased
over time, as recruitment apparently exceeded departures. To test trail disruption in small outdoor plots, the trail pheromone
was formulated with carnuba wax-coated quartz laboratory sand (1 g quartz sand/0.2 g wax/1 mg pheromone). The pheromone formulation,
with a half-life of 30 h, was applied by rotary spreader at four rates (0, 2.5, 7.5, and 25 mg pheromone/m2) to 1- and 4-m2 plots in Volcanoes National Park, Hawaii. Ant counts at bait cards in treated plots were significantly reduced compared to
controls on the day of treatment, and there was a significant reduction in ant foraging for 2 days. These results show that
trail pheromone disruption of Argentine ants is possible, but a much more durable formulation is needed before nest-level
impacts can be expected.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
2.
JL Stringer 《Canadian Metallurgical Quarterly》1995,68(2):407-413
In a particular brain region specific changes in inhibition or excitation may be the basis of seizure initiation. Alternatively, changes in the balance of excitation and inhibition in the circuit, which may be detectable as polysynaptic responses may be more important indicators of epileptogenesis. That the appearance of polysynaptic responses precedes the initiation and, therefore, may be necessary for the onset of epileptiform activity in the hippocampal-parahippocampal circuit was tested using the chemical convulsant pentylenetetrazol. Excitation and paired-pulse inhibition were measured in CA1 and the dentate gyrus of the urethane-anaesthetized rat before and after administration of pentylenetetrazol. In addition, three polysynaptic responses were monitored. In both CA1 and the dentate gyrus, pentylenetetrazol, 100 mg/kg, caused a trend towards increased excitability and caused a relatively mild loss of inhibition. Two polysynaptic responses appeared in the dentate gyrus after the administration of pentylenetratrazol, both apparently mediated through the entorhinal cortex. A polysynaptic response of the CA1 pyramidal neurons to contralateral angular bundle stimulation was not observed. These experiments demonstrate that pentylenetetrazol will facilitate only the appearance of polysynaptic responses mediated through the entorhinal cortex. These results support the hypothesis that pentylenetetrazol has a specific action within the entorhinal cortex that may facilitate the synchronization and spread of epileptiform activity. These results are also consistent with the hypothesis that the appearance of polysynaptic responses may be necessary for the onset of epileptogenesis in the hippocampal-parahippocampal circuit. 相似文献
3.
A 14-year-old girl presenting with acute massive gastric dilatation secondary to duodenal obstruction by the superior mesenteric artery is described. The diagnosis was facilitated by contrast-enhanced abdominal computerized tomography. She was successfully treated by gastrostomy and subsequent duodenal derotation. This unique presentation of the superior mesenteric artery syndrome is discussed. 相似文献
4.
The extracellular environment controls many cellular activities thereby linking external material cues to internal cell function. By better understanding these processes, synthetic extracellular material niches can be tailored to present cells with highly regulated physical and/or chemical cues that promote or suppress selected cell functions. Here, poly(ethylene glycol) (PEG) hydrogels were functionalized with fluvastatin-releasing grafts and growth factor binding heparin domains to enable the dynamic exchange of information between the material and cells from the outside-in and inside-out (i.e., bidirectional signaling). By incorporating a fluvastatin-releasing graft and carefully controlling the dose and temporal release, materials were designed to promote bone morphogenic protein (BMP2) and alkaline phosphatase (ALP) production by human mesenchymal stem cells (hMSCs). When the release of fluvastatin was controlled to occur over 2 weeks, BMP2 and ALP production was increased 2.2-fold and 1.7-fold, respectively, at day 28 compared to hMSCs cultured in the absence of fluvastatin. By introducing a heparin functionality into the gel to sequester and localize the hMSC-produced BMP2, the osteogenic differentiation of hMSCs was further augmented over fluvastatin delivery alone. Osteopontin and core binding factor α1 gene expression was 6-fold and 4-fold greater for hMSCs exposed to fluvastatin in the presence of the heparin functionalities, respectively. These results demonstrate how multifunctional gels that interact with cells in a bidirectional manner can efficiently promote selected cell functions, such as the osteogenic differentiation of hMSCs. 相似文献
5.
Kaslow Nadine J.; Rubin Nancy J.; Forrest Linda; Elman Nancy S.; Van Horne Barbara A.; Jacobs Sue C.; Huprich Steven K.; Benton Sherry A.; Pantesco Victor F.; Dollinger Stephen J.; Grus Catherine L.; Behnke Stephen H.; Miller David S. Shen; Shealy Craig N.; Mintz Laurie B.; Schwartz-Mette Rebecca; Van Sickle Kristi; Thorn Beverly E. 《Canadian Metallurgical Quarterly》2007,38(5):479
Working collaboratively, psychologist educators and trainers at the doctoral, internship, and postdoctoral levels; credentialers; practitioners; and students offer 8 proposals for psychologists to consider in recognizing, assessing, and intervening with problems of professional competence in students and practicing professionals. In the proposals, the authors address the following topics: definitions and categories; preparing the system; self-assessment; remediation; diversity; communication across various levels of the system; confidentiality; and ethical, regulatory, and legal underpinnings. They also propose future directions for the assessment of problems in professional competence in both students and practicing psychologists. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
6.
7.
The results are presented of exposure to a controlled high-temperature erosive gas stream of a series of alloys, which were selected to represent the range of microstructures and mechanical properties available in commercial high-temperature alloys. Analysis of the kinetic and morphological data suggested that the high-temperature oxidation behavior of a given alloy plays a very important role in determining its erosion-corrosion behavior under the conditions studied. In terms of relative behavior, alloys which are weak but ductile at temperature, and which form tenacious oxide scales, exhibited the highest resistance to high-temperature erosion-corrosion. Simple models were developed to describe the expected interaction between high-temperature oxidation and erosion. 相似文献
8.
The chemical composition, defect structure, and diffusion in nickel sulfide -Ni3S2 have been investigated in H2S-H2 mixtures containing between 1 and 65% H2S between 560 and 700°C. Gravimetric, density, and X-ray studies were carried out. In the thermodynamically stable compound the ratio of Ni/S varied between 1.3 and 1.75. The X-ray examination showed a step change in the lattice parameter at the Ni/S ratio 1.4. A linear dependence of the density values (between 5.5 and 6.2 g/cm3) on the composition was observed. On the basis of the chemical composition and density measurements the number of nickel and sulfur atoms in 1 cm3 were determined. It has been shown that the Ni3S2 phase is defected in both anion and cation sublattices and that its chemical formula may be described as follows: Ni3±yS2x, where y 2x. It has been found that in the mixture containing 10% H2S the process of defect formation is determined by their diffusion in the sulfide. The temperature dependence of the diffusion coefficient is described by the equation D = 13.15 exp(-30,000/RT) cm2/sec. No dependence of D on the sulfur partial pressure was observed, but this may be due to the relatively large uncertainties in the measurement of the diffusion coefficients. 相似文献
9.
The oxidation of Ni-23.1Nb-4.4Al and Ni-19.7Nb-6 Cr-2.5Al alloys in air at temperatures in the range 870–1100°C has been studied for times up to 168 hr, in the as-cast, slowly cooled, and directionally solidified forms. The oxidation rate decreases with increasing temperature for the ternary alloy, and this appears to be due to the increasing tendency to establish a continuous Al2O3 layer at the metal surface, although at no temperature in this range is a complete layer established. At the lowest temperature the -Ni3Nb lamellae are preferentially oxidized, with fingers of oxide extending into the metal, but at 900°C and above a continuous single-phase 8-free layer is established at the metal surface very early in the oxidation. The oxidation rate of the quaternary alloy increases with increasing temperature. At the lower temperatures a continuous Al2O3 layer is established at the metal surface, but at the highest temperature the aluminum oxidizes internally and a continuous layer is not established, internal oxidation penetrating down the lamellae. It appears that niobium, like chromium, is able to promote the formation of external Al2O3 layers; if this fact is accepted, the beneficial role of chromium in these alloys is difficult to explain. 相似文献
10.
The effect of sodium sulphate coatings on the oxidation of cobalt-base alloys at 900°C in oxygen at 1 atm pressure has been studied. The oxidation of pure cobalt is rather slower with a sodium sulphate coating than without; and this is also true of cobalt-chromium alloys. However, the oxidation of cobalt-tungsten alloys is accelerated by the presence of a sodium sulphate layer: a porous CoO scale develops, with an accumulation of a tungsten-rich oxide at the metal surface. Cobalt-molybdenum alloys suffer an even greater acceleration, and unlike the tungsten-containing alloys the rate does not fall as the oxide at the surface becomes protective, possibly due to the higher volatility of MoOs. It is possible to produce a similar rapid corrosion of pure cobalt with sodium sulphate-sodium tungstate coating.It is concluded that basic fluxing of CoO does not take place, either because there is no salt-soluble anionic species analogous to the nickelate ion, or because it is stable at salt basicities higher than those reached in these experiments. The accelerated attack in the presence of tungsten or molybdenum is thought to be due to acid fluxing of the cobalt.Chromium has little effect on the acid fluxing of cobalt-tungsten alloys until the chromium-content is high enough for the establishment of a continuous Cr2O3 layer; this does not then suffer accelerated attack in the presence of sodium sulphate.A sodium carbonate layer has a similar accelerating effect on the tungsten and molybdenum containing alloys except that there is an incubation period before rapid attack commences. This may be associated with the decomposition of the salt with the evolution of CO2. 相似文献