987 resultados para ion trap, rf-trap, Mathieu equation, stability diagram, anharmonic oscillation


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Erbium-activated silica-based planar waveguides were prepared by three different technological routes: RF-sputtering, sol-gel and ion exchange. Various parameters of preparation were varied in order to optimize the waveguides for operation in the NIR region. Particular attention was devoted to the minimization of the losses and the increase of the luminescence efficiency of the metastable I-4(13/2) state of the Er3+ ion. Waveguide properties were determined by m-line spectroscopy and loss measurements. Waveguide Raman and luminescence spectroscopy were used to obtain information about the structure of the prepared films and about the dynamical processes related to the luminescence of the Er3+ ions.

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Although it is generally accepted that osteoclasts breakdown and resorb bone matrix, the possibility that they may also be able to engulf apoptotic osteoblasts/ lining cells and/or osteocytes remains controversial. Apoptosis of osteoblasts/ lining cells and/or osteocytes and interactions between these cells and osteoclasts are extremely rapid events that are difficult to observe in viva. A suitable in viva model for studying these events is the alveolar bone of young rats because it is continuously. Thus, sections of aldehyde fixed alveolar undergoing intense resorption/remodeling bone of young rats were stained by the combined terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) method and the tartrate-resistant acid phosphatase (TRAP) method for the simultaneous visualization of apoptotic cells and osteoclasts in the same section. The combined TUNEL and TRAP reactions, in the same section, greatly facilitated visualization of relationship between osteoclasts and apoptotic bone cells during alveolar bone remodeling. Our results showed that several TRAP-positive osteoclasts exhibited large vacuoles containing TUNEL positive apoptotic structures, probably derived from osteoblasts/lining cells and/or osteocytes. These results support the idea that alveolar bone osteoclasts are able to internalize dying apoptotic bone cells.

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The stability of the parameters of the Johnson-Mehl-Avrami equation was studied using two parametrizations of the sigmoidal function and its fit to some kinetic data. The results indicate that one of the forms of the function has more stable parameters and only for this form it is reasonable to use, as an approximation, the linear regression theory to analyse the parameters. © 1995 Chapman & Hall.

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The Gross-Pitaevskii equation for Bose-Einstein condensation (BEC) in two space dimensions under the action of a harmonic oscillator trap potential for bosonic atoms with attractive and repulsive interparticle interactions was numerically studied by using time-dependent and time-independent approaches. In both cases, numerical difficulty appeared for large nonlinearity. Nonetheless, the solution of the time-dependent approach exhibited intrinsic oscillation with time iteration which is independent of space and time steps used in discretization.

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The asymptotic stability of the null solution of the equation ẋ(t) = -a(t)x(t)+b(t)x([t]) with argument [t], where [t] designates the greatest integer function, is studied by means of dichotomic maps. © 2010 Academic Publications.

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Includes bibliography

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Includes bibliography.

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One of the most commonly used sampling techniques to capture leaf litter amphibians, lizards and small mammals is a set of pitfall traps with drift fences. However, there are still many speculations concerning the effectiveness of different designs of pitfall traps and the most adequate size of each trap. To address this problem, we conducted the first standardized comparison of patterns of species richness, rank-abundance, and community structure of leaf litter amphibians, lizards and small mammals for two trap designs (I and Y format) and three bucket sizes (35, 62, and 100 L) in a Neotropical forest. Results are very similar for the herpetofauna, regardless of the pitfall trap design or size used, while for small mammals values of species richness were higher for 100 L pitfall traps, as compared to the smaller traps. Therefore, the use of 100 L pitfall traps is recommended to sample the terrestrial vertebrate fauna, in multidisciplinary studies. For surveys aiming only the herpetofauna the use of smaller (35 L) traps is acceptable, taking into consideration the cost-benefits obtained by the smaller traps, in comparison to the larger ones.

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Although the human-landing catch (HLC) method is the most effective for collecting anthropophilic anophelines, it has been increasingly abandoned, primarily for ethical considerations. The objective of the present study was to develop a new trap for the collection of Anopheles darlingi . The initial trials were conducted using the BG-Sentinel trap as a standard for further trap development based on colour, airflow direction and illumination. The performance of the trap was then compared with those of the CDC, Fay-Prince, counterflow geometry trap (CFG) and HLC. All trials were conducted outdoors between 06:00 pm-08:00 pm. Female specimens of An. darlingi were dissected to determine their parity. A total of 8,334 anophelines were captured, of which 4,945 were identified as An. darlingi . The best trap configuration was an all-white version, with an upward airflow and no required light source. This configuration was subsequently named BG-Malaria (BGM). The BGM captured significantly more anophelines than any of the other traps tested and was similar to HLC with respect to the number and parity of anophelines. The BGM trap can be used as an alternative to HLC for collecting anophelines.

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Current detection tools for Sirex noctilio F. (Hymenoptera: Siricidae) in North America are poor. To determine the importance of intercept trap type for capturing females of S. noctilio and its native congener, Sirex nigricornis F., in eastern North America, we report on seven trap comparison studies from different years and geographic locations. Among studies, total numbers of S. noctilio captured were low (mean of <= 1waspper trap). Total numbers of S. nigricornis caught were generally greater, andranged from ameanof 1-13 wasps per trap. Nearly all studies found no significant differencesamongintercept trap types in the number of woodwasps caught. For future studies, we recommend that either panel or 12-unit Lindgren funnel traps be used to catch S. noctilio or S. nigricornis in eastern North America.

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The Rose-ringed parakeet (Psittacula krameri [Scopdi]) has been reported (Roberts, 1974; Bashir, 1978; Beg, 1978; and DeGrazio, 1978) as a serious bird pest of maize, sunflower, rape seeds, and fruit crops, particularly citrus, mangoes, and guavas, in Pakistan. Estimated annual losses to maize grown for seed alone amount to about 97,000 tons, worth about Pak. Rs. 150 million or US $15 million (Roberts, 1978). Paradoxically, this handsome bright green parakeet is highly esteemed in the pet trade; and limited numbers are also marketed locally and sometimes exported to neighboring countries, particularly the Arab Gulf Emirates, as caged pets. Traditional control methods aimed at scaring or chasing birds from the crops, usually with noise-making devices, are costly; furthermore, they have largely been unsuccessful and time consuming because they require human patrolling before and after normal working hours. They provide at best only temporary relief. The aim of this study was to develop a new decoy trap based on the Modified Australian Crow Trap (MAC), which we propose to call the PAROTRAP, and to evaluate its effectiveness and potential in capturing live parakeets in the field as a possible solution to the parakeet problem, as well as promoting the economic exploitation of trapped parakeets for the pet trade. The study was undertaken during March and June 1979 as a part of the UNDP/FAO Project No. PAK/71/554, assisting Pakistan Vertebrate Pest Control Centre in developing and improving control techniques to prevent or reduce bird damage to important crops. Our earlier trials showed that parakeets could be induced to enter a conventionally designed MAC trap, and that after some time they learned how to escape from it. Therefore, a series of minor modifications were introduced and field tested.

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Workplace accidents involving machines are relevant for their magnitude and their impacts on worker health. Despite consolidated critical statements, explanation centered on errors of operators remains predominant with industry professionals, hampering preventive measures and the improvement of production-system reliability. Several initiatives were adopted by enforcement agencies in partnership with universities to stimulate production and diffusion of analysis methodologies with a systemic approach. Starting from one accident case that occurred with a worker who operated a brake-clutch type mechanical press, the article explores cognitive aspects and the existence of traps in the operation of this machine. It deals with a large-sized press that, despite being endowed with a light curtain in areas of access to the pressing zone, did not meet legal requirements. The safety devices gave rise to an illusion of safety, permitting activation of the machine when a worker was still found within the operational zone. Preventive interventions must stimulate the tailoring of systems to the characteristics of workers, minimizing the creation of traps and encouraging safety policies and practices that replace judgments of behaviors that participate in accidents by analyses of reasons that lead workers to act in that manner.