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Node Level (node + level)

Distribution by Scientific Domains

Medical Sciences	60%

Selected Abstracts

Fragment Propagation and Colonization Ability Enhanced and Varied at Node Level after Escaping from Apical Dominance in Submerged Macrophytes

JOURNAL OF INTEGRATIVE PLANT BIOLOGY, Issue 3 2009
Jinhui Jiang
Abstract Aquatic plants develop strong fragment propagation and colonization ability to endure the natural disturbances. However, detailed research of ability to endure the natural disturbances has been lacking to date. Therefore, reproduction (shoot) and colonization (root) of shoot fragments of Potamogeton crispus L. with or without apices were investigated for the effect of apical dominance, and the growth of decapitated shoot fragments at three lengths (2, 4, 6 cm) was compared. Meanwhile, fragment propagation at levels of bud position was studied for bud position effect after escaping from apical dominance. The results showed significant increases occurred in the outgrowth of lateral branches on fragments decapitated compared with the fragments with apices, implying that apical dominance exists. Different lengths of fragments showed little difference in biomass allocations, but significant differences were noted in their propagation. Meanwhile, the effect of bud position was verified, due to the significant difference of average reproduction per node among the three length groups. Thus, the present study has made progress in the current understanding of aquatic plant dispersion among natural systems and contributes to improve methods of in vitro propagation for re-implantation purposes. [source]

A dynamic key management solution to access hierarchy

INTERNATIONAL JOURNAL OF NETWORK MANAGEMENT, Issue 6 2007
Xukai Zou
Hierarchical access control (HAC) has been a fundamental problem in computer and network systems. Since Akl and Taylor proposed the first HAC scheme based on number theory in 1983, cryptographic key management techniques for HAC have appeared as a new and promising class of solutions to the HAC problem. Many cryptographic HAC schemes have been proposed in the past two decades. One common feature associated with these schemes is that they basically limited dynamic operations at the node level. In this paper, by introducing the innovative concept of ,access polynomial' and representing a key value as the sum of two polynomials in a finite field, we propose a new key management scheme for dynamic access hierarchy. The newly proposed scheme supports full dynamics at both the node level and user level in a uniform yet efficient manner. Furthermore, the new scheme allows access hierarchy to be a random structure and can be flexibly adapted to many other access models such as ,transfer down' and ,depth-limited transfer'. Copyright © 2007 John Wiley & Sons, Ltd. [source]

Integrated 18F-FDG PET/CT for the initial evaluation of cervical node level of patients with papillary thyroid carcinoma: comparison with ultrasound and contrast-enhanced CT

CLINICAL ENDOCRINOLOGY, Issue 3 2006
Han-Sin Jeong
Summary Objective, To compare the diagnostic accuracy of integrated 18F-fluorodeoxyglucose PET/CT with ultrasonography (US) and contrast enhanced CT (CECT) alone in the initial evaluation of cervical lymph node levels of patients with papillary thyroid carcinoma. Patients and measurements, From July 2004 to March 2005, 26 consecutive patients with papillary thyroid carcinoma, confirmed by aspiration cytology analysis, underwent US, CECT and PET/CT. The sensitivity, specificity and diagnostic accuracy of the US, CECT and PET/CT studies for the final status of 312 cervical node levels (levels I,V: 260, level VI: 52) were compared by employing a generalized estimating equation test. The final status of cervical node levels was determined by the surgical pathology and follow-up data. Results, At all lymph node levels (levels I,VI), PET/CT showed a sensitivity of 30·4%, a specificity of 96·2% and a diagnostic accuracy of 86·9%. The corresponding values for US and CECT were 41·3%, 97·4%, 89·1% (US) and 34·8%, 96·2%, 87·2% (CECT). Considering only the lateral cervical node group (levels I,V), PET/CT showed a sensitivity of 50·0%, a specificity of 97·0% and a diagnostic accuracy of 92·3%. The corresponding values for US and CECT were 53·9%, 97·9%, 93·5% (US) and 42·3%, 96·6%, 91·2% (CECT). The diagnostic results for US, CECT and PET/CT upon initial evaluation of the cervical lymph nodes did not differ significantly on a level-by-level basis. Conclusion, Our preliminary results suggest that integrated PET/CT does not provide any additional benefit when compared to US and CECT for the initial evaluation of cervical node levels in patients with papillary thyroid carcinoma. [source]

Lymph node metastases in the lower neck

CLINICAL OTOLARYNGOLOGY, Issue 3 2003
W. Giridharan
Lymph node metastases in the lower neck Current knowledge suggests that lymph node metastases in the lower neck (supraclavicular fossa and posterior triangle) are associated with a poor survival. Very little systematic work has been published on this subject. This was a retrospective study carried out on a database where all patients were entered in a prospective manner over a 35-year period using a standard pro-forma. Data on 168 patients presenting with a lower neck node metastasis were retrieved. The main outcome measures were: association between variables and tumour-specific survival. Data were displayed in contingency tables and analysed by chi-square and categorical modelling. Recurrence and survival were plotted in a cause-specific manner using the Kaplan Meir method. Differences in curves were analysed using the log rank test. Multivariate analysis was carried out using Cox's proportional hazard model. The only association was between site and node level and histology. Head and neck tumours were associated with squamous histology (P = 0.0004) and supraclavicular nodes (P = 0.0047). Survival time was not significantly different when lower-neck lymph node metastasis from the head and neck was compared to non-head and neck metastasis: 5-year survival 30% and 10% respectively (P = 0.1363). Survival with posterior triangle metastases was significantly better than supraclavicular metastases (P = 0. 0059), confirmed on multivariate analysis. Laterality of metastasis had no effect on survival (P < 0.0001). There was no significant difference in survival between squamous and non-squamous metastases on Cox regression (P = not significant). There were 85 head and neck primaries including lymphomas, 53 infraclavicular primaries and 30 unknown primaries. There were 73 squamous cell carcinomas, 27 adenocarcinomas, 34 lymphomas, 28 undifferentiated tumours and six other tumours. Nearly half the primary tumours were below the clavicle. Survival was unaffected by laterality, primary site or histology, but was better for posterior triangle nodes. [source]

Integrated 18F-FDG PET/CT for the initial evaluation of cervical node level of patients with papillary thyroid carcinoma: comparison with ultrasound and contrast-enhanced CT