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排序方式: 共有1374条查询结果,搜索用时 11 毫秒
91.
D Tena M Pérez Simón C Gimeno MT Pérez Pomata S Illescas I Amondarain A González J Domínguez J Bisquert 《Canadian Metallurgical Quarterly》1998,36(8):2375-2376
We report a case of Hymenolepis diminuta infection in a human. The patient was a 5-year-old girl referred to us through the onset of a cyanotic attack. Treatment with a single dose (10 mg/kg of body weight) of praziquantel was ineffective, but the parasite was eradicated after three treatment cycles with the same drug at dosages of 25 mg/kg/day for 5 days. 相似文献
92.
The administration, to rats, of a combination of pregnant mares serum gonadotrophin (PMSG) and human chorionic gonadotrophin (hCG) in high doses induces the ovarian hyperstimulation syndrome (OHSS) which is characterized by increased vascular permeability (VP) and simultaneous overexpression of vascular endothelial growth factor (VEGF) in ovarian cells. hCG has a longer half-life than LH and a greater biological activity, expressed in a higher incidence of complications such as OHSS. Similarly, FSH may also be related to the ovulatory changes within the follicle as there is a simultaneous surge in spontaneous cycles. The aim of this study was to compare the capacity of hCG, FSH and LH to induce ovulation and simultaneously prevent OHSS in the animal model. Immature female rats were treated with 10 IU PMSG for 4 days, and ovulation was triggered with saline, 10 IU hCG, 10 IU FSH, 10 IU LH or 60 IU LH. The number of oocytes ovulated into the tubes, VP and mRNA VEGF expression were evaluated and compared. All the hormones employed were as effective at triggering ovulation, with similar significant P values when compared with the control for which saline was used. The use of 10 IU LH resulted in significantly lower VP and VEGF expression than that seen in the groups treated with 10 IU hCG, 10 IU FSH or 60 IU LH. In conclusion, FSH and hCG, as well as a sixfold increase in LH, displayed similar biological activities, including increased VP due to excessive VEGF expression. The use of lower doses of LH produced similar rates of ovulation, while preventing the undesired changes in permeability. These experiments should therefore encourage clinicians to determine the optimal dose of LH to be employed in women in order to trigger ovulation and, at the same time, avoid the risk of OHSS. 相似文献
93.
Atmospheric dry deposition of persistent organic pollutants to the Atlantic and inferences for the global oceans 总被引:3,自引:0,他引:3
Jurado E Jaward FM Lohmann R Jones KC Simó R Dachs J 《Environmental science & technology》2004,38(21):5505-5513
Atmospheric deposition to the oceans is a key process affecting the global dynamics and sinks of persistent organic pollutants (POPs). A new methodology that combines aerosol remote sensing measurements with measured POP aerosol-phase concentrations is presented to derive dry particulate depositional fluxes of POPs to the oceans. These fluxes are compared with those due to diffusive air-water exchange. For all polychlorinated biphenyl (PCB) congeners and lower chlorinated dibenzo-p-dioxins and furans (PCDD/Fs), air-water exchange dominates the dry deposition mechanism. However, this tendency reverses in some areas, such as in marine aerosol influenced areas and dust outflow regions, consistent with the important variability encountered for the depositional fluxes. Seasonal variability is mainly found in mid-high latitudes, due to the important influence of wind speed enhancing dry deposition fluxes and temperature as a driver of the gas-particle partitioning of POPs. The average dry aerosol deposition flux of sigmaPCBs and sigmaPCDD/Fs to the Atlantic Ocean is calculated to be in the order of 66 ng m(-2) yr(-1) and 9 ng m(-2)yr(-1) respectively. The total dry aerosol deposition of sigmaPCBs and sigmaPCDD/Fs to the Atlantic Ocean is estimated to be 2200 kg yr(-1) and 500 kg yr(-1), respectively, while the net air-water exchange is higher, 22000 kg sigmaPCBs yr(-1) for PCBs and 1300 kg sigmaPCDD/Fs yr(-1). Furthermore, it is suggested that marine aerosol plays an important role in scavenging atmospheric contaminants. 相似文献
94.
Hormones excreted in animal waste have been measured in surface and groundwater associated with manure that is applied to the land surface. Limited studies have been done on the fate and transport of androgenic hormones in soils. In this study, batch and column experiments were used to identify the fate and transport of radiolabeled [14C] testosterone in agricultural soils. The batch results indicated that aqueous-phase concentrations decreased for the first 5 h and then appeared to increase through time. The first-order sorption kinetics ranged from 0.08 to 0.640 h(-1) for the first 5 h. Beyond 5 h the increase in aqueous 14C could have been caused by desorption of testosterone back into the aqueous phase. However, metabolites were also produced beyond 5 h and would have likely resulted in the increase in aqueous 14C by sorption site competition and/or by lower sorption affinity. There were weak correlations of sorption with soil particle size, organic matter, and specific surface area. Testosterone was the dominant compound present in the soil column effluents, and a fully kinetic-sorption, chemical nonequilibrium model was used to describe the data. Column experiment sorption estimates were lower than the batch, which resulted from rate-limiting sorption due to the advective transport. The column degradation coefficients (0.404-0.600 h(-1)) were generally higher than values reported in the literature for 17beta-estradiol. Although it was found that testosterone degraded more readily than 17beta-estradiol, it appeared to have a greater potential to migrate in the soil because it was not as strongly sorbed. This study underlined the importance of the simultaneous transformation and sorption processes in the transport of hormones through soils. 相似文献
95.
Robert Sim Pantelis Elinas James J. Little 《International Journal of Computer Vision》2007,74(3):303-318
With recent advances in real-time implementations of filters for solving the simultaneous localization and mapping (SLAM)
problem in the range-sensing domain, attention has shifted to implementing SLAM solutions using vision-based sensing. This
paper presents and analyses different models of the Rao-Blackwellised particle filter (RBPF) for vision-based SLAM within
a comprehensive application architecture. The main contributions of our work are the introduction of a new robot motion model
utilizing structure from motion (SFM) methods and a novel mixture proposal distribution that combines local and global pose
estimation. In addition, we compare these under a wide variety of operating modalities, including monocular sensing and the
standard odometry-based methods. We also present a detailed study of the RBPF for SLAM, addressing issues in achieving real-time,
robust and numerically reliable filter behavior. Finally, we present experimental results illustrating the improved accuracy
of our proposed models and the efficiency and scalability of our implementation. 相似文献
96.
Yong-Duck Chung Kwang-Seong Choi Jae-Sik Sim Hyun-Kyu Yu Jeha Kim 《Lightwave Technology, Journal of》2007,25(11):3407-3412
We developed an analog optical system-on-package (SoP) transmitter for a 60-GHz-band radio-over-fiber (RoF) link. The SoP transmitter consisted of an electroabsorption modulator, radio frequency amplifiers, and a bandpass filter. The 60-GHz RoF wireless link was prepared to measure the performance of the SoP transmitter. The transmission characteristics of 64-quadrature amplitude modulation (64-QAM) data of the 60-GHz RoF wireless link, including the SoP transmitter, were investigated by measuring the error vector magnitude (EVM) and signal-to-noise ratio (SNR) with a baseband frequency. The EVM of the 60-GHz RoF wireless link was between 2.25% and 2.80%, and the SNR was between 27.36 and 29.31 dB from 140 and 770 MHz, at input baseband power of -9 dBm. The noise figure had the minimum of 8.44 dB at 500 MHz. We successfully transmitted digital community antenna television (CATV) system signals through the 60-GHz RoF wireless link, including the SoP transmitter. Digital CATV signals of 86 channels could be transmitted through the 60-GHz RoF wireless link, and the total throughput was found to be 2.61 Gb/s. 相似文献
97.
Service composition in multi-Cloud environments must coordinate self-interested participants, automate service selection, (re)configure distributed services, and deal with incomplete information about Cloud providers and their services. This work proposes an agent-based approach to compose services in multi-Cloud environments for different types of Cloud services: one-time virtualized services, e.g., processing a rendering job, persistent virtualized services, e.g., infrastructure-as-a-service scenarios, vertical services, e.g., integrating homogenous services, and horizontal services, e.g., integrating heterogeneous services. Agents are endowed with a semi-recursive contract net protocol and service capability tables (information catalogs about Cloud participants) to compose services based on consumer requirements. Empirical results obtained from an agent-based testbed show that agents in this work can: successfully compose services to satisfy service requirements, autonomously select services based on dynamic fees, effectively cope with constantly changing consumers’ service needs that trigger updates, and compose services in multiple Clouds even with incomplete information about Cloud participants. 相似文献
98.
An augmented EDA with dynamic diversity control and local neighborhood search for coevolution of optimal negotiation strategies 总被引:2,自引:2,他引:0
In this paper, we present an estimation of distribution algorithm (EDA) augmented with enhanced dynamic diversity controlling and local improvement methods to solve competitive coevolution problems for agent-based automated negotiations. Since optimal negotiation strategies ensure that interacting agents negotiate optimally, finding such strategies—particularly, for the agents having incomplete information about their opponents—is an important and challenging issue to support agent-based automated negotiation systems. To address this issue, we consider the problem of finding optimal negotiation strategies for a bilateral negotiation between self-interested agents with incomplete information through an EDA-based coevolution mechanism. Due to the competitive nature of the agents, EDAs should be able to deal with competitive coevolution based on two asymmetric populations each consisting of self-interested agents. However, finding optimal negotiation solutions via coevolutionary learning using conventional EDAs is difficult because the EDAs suffer from premature convergence and their search capability deteriorates during coevolution. To solve these problems, even though we have previously devised the dynamic diversity controlling EDA (D2C-EDA), which is mainly characterized by a diversification and refinement (DR) procedure, D2C-EDA suffers from the population reinitialization problem that leads to a computational overhead. To reduce the computational overhead and to achieve further improvements in terms of solution accuracy, we have devised an improved D2C-EDA (ID2C-EDA) by adopting an enhanced DR procedure and a local neighborhood search (LNS) method. Favorable empirical results support the effectiveness of the proposed ID2C-EDA compared to conventional and the other proposed EDAs. Furthermore, ID2C-EDA finds solutions very close to the optimum. 相似文献
99.
100.
Yeom Hong-Gi Park Seung-Min Park Junheong Sim Kwee-Bo 《International Journal of Control, Automation and Systems》2011,9(3):595-600
To improve the performance of classification algorithms, we proposed a new varianceconsidered machine (VCM) classification
algorithm in a previous study. The study showed theoretically that VCMs have lower error probabilities than SVMs. The purpose
of this paper is to experimentally demonstrate the superiority of VCMs. Therefore, we verified our proposal with several case
experiments using data following a Gaussian distribution with different variances and prior probabilities. To estimate performance,
the experiment for each case was executed 1000 times and the error rates were averaged for accuracy. The data of each experiment
have different distances between means of data, and different ratios between training data and testing data. Thus, we proved
that the error rate of VCMs is lower than the error rate of SVMs, although their performances were not similar in each case.
Consequently, we expect that VCMs will be applied to a variety fields. 相似文献