252 research outputs found

    Evaluation of attract-and-kill strategy for management of cocoa pod borer, Conopomorpha cramerella, in Malaysia cocoa plantation

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    In South-East Asia, cocoa production is dramatically affected by cocoa pod borer (CPB) infestations. As an alternative tool to chemical control, the efficacy of attract-and-kill strategy (CPB sex-pheromone as attractant and Delta trap without sticky liner sprayed with cypermethrin solution as killing station) was evaluated and compared with current standard CPB management approach as control treatment during two main cocoa harvest seasons in Malaysia (with 100 mu g and 33.3 mu g CPB-pheromone loading per station, respectively). In both seasons, attract-and-kill strategy was highly effective at reducing male flight activity (p < 0.05) in attract-and-kill plots comparing with standard CPB management plots. For the percentage of CPB-infested pods, the attract-and-kill strategy (100 mu g) was as good as the conventional pesticide spray applications of cypermethrin (p = 0.083) in first season. However, it was significantly (p = 0.021) reduced in the second season with lower pheromone loading (33.3 mu g), indicating that this semiochemical based strategy is far superior to and more feasible than the currently applied conventional synthetic pesticide treatment and is therefore a good alternative in CPB integrated pest management

    Optical flow tracking method for vibration identification of out-of-plane vision

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    Vibration measurement based on computer vision has been extensively studied and considered as a wide-range, non-contact measurement method. In this paper, the principle of vibration measurement using out-of-plane vision has been investigated under conventional imaging condition. A measurement model for out-of-plane vision has also been demonstrated. Combined the out-of-plane vision measurement model with the optical flow motion estimation principle, a novel model of optical flow tracking method for vibration detection based on out-of-plane vision has been proposed. It enables the identification of vibration parameters without image feature extraction. Visual vibration detection experiment has been conducted with a cantilever beam and a motor cover. Experimental results have been rigorously compared with finite element simulation to verify the efficacy of the proposed method. It shows that this method can effectively identify vibration parameters of the structure without image feature extraction

    Observational study of tidal mixing asymmetry and eddy viscosity-shear covariance – induced residual flow in the Jiulong River estuary

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    Abstract(#br)An observation study was conducted at three stations in the inner regime of the Jiulong River estuary to examine the tidal mixing asymmetry and its associated residual flow induced by eddy viscosity-shear covariance (ESCO). The water columns at the observation stations were approximately well-mixed during the later flood and were stratified during the early ebb, a typical tidal mixing asymmetry. Corresponding to the tidal variation of stratification, the Reynolds stress and vertical eddy viscosity, which were obtained using the ADCP variance method, exhibited distinct differences in the magnitude and vertical structure between flood and ebb tides. The ESCO flow was calculated using the decomposition method for estuarine circulation, revealing a two-layer vertical structure similar to density-driven flow but with a much greater magnitude, confirming the findings of previous generic model studies that the ESCO flow dominates the density-driven flow in periodically stratified estuaries. The drivers of tidal mixing asymmetry were explored using the potential energy anomaly method. Longitudinal straining reduced stratification during flood tides and reinforced stratification during ebb tides, whereas longitudinal advection acted in the opposite manner. Although the contribution of lateral circulation to stratification was neglected due to the lack of lateral observation data, scaling analysis revealed that lateral advection was important in the longitudinal dynamics and tidal evolution of stratification and warrants further study

    Case report: Giant cystic ileal gastrointestinal stromal tumor with an atypical intratumoral abscess

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    BackgroundGastrointestinal stromal tumors (GISTs) are typically solid, sometimes with small cystic areas, but rarely manifest as predominantly cystic neoplasms. In addition, cystic intestinal GISTs with intratumoral abscess formation are rare.Case presentationWe present the case of a 49-year-old male patient with a history of frequent and urgent urination for 2 weeks. Radiologic studies revealed a large cystic mass in the lower abdomen. The patient underwent abdominal laparotomy, which revealed a large cystic mass arising from the distal ileum invading the sigmoid mesocolon and apex vesicae. Partial resection of the ileum along with the tumor and the adjacent bladder was performed. Macroscopic examination revealed that the cystic mass contained a large amount of foul-smelling pus and a tumor-bowel fistula. The final pathology revealed an abdominal stromal tumor. Postoperative recovery was uneventful, and adjuvant imatinib mesylate 400 mg was administered daily. No tumor recurrence or metastasis was observed during the 9-month follow-up period.ConclusionFingings of a cystic tumor in the abdomen should raise concern for cystic GISTs. This case report reviews a rare presentation of an ileal giant cystic GIST with atypical intratumoral abscess formation. Complete surgical resection and adjuvant imatinib is still the mainstay treatment for GISTs

    On the use of an explicit chemical mechanism to dissect peroxy acetyl nitrate formation.

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    Peroxy acetyl nitrate (PAN) is a key component of photochemical smog and plays an important role in atmospheric chemistry. Though it has been known that PAN is produced via reactions of nitrogen oxides (NOx) with some volatile organic compounds (VOCs), it is difficult to quantify the contributions of individual precursor species. Here we use an explicit photochemical model--Master Chemical Mechanism (MCM) model--to dissect PAN formation and identify principal precursors, by analyzing measurements made in Beijing in summer 2008. PAN production was sensitive to both NOx and VOCs. Isoprene was the predominant VOC precursor at suburb with biogenic impact, whilst anthropogenic hydrocarbons dominated at downtown. PAN production was attributable to a relatively small class of compounds including NOx, xylenes, trimethylbenzenes, trans/cis-2-butenes, toluene, and propene. MCM can advance understanding of PAN photochemistry to a species level, and provide more relevant recommendations for mitigating photochemical pollution in large cities
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