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21.
针对现有固定宽带有线、无线接入技术存在的不足,本文结合Ad hoc技术和移动IP技术,提出了一种支持IP漫游的多跳接入方式,包括组网设计及协议扩展。其组网方式为:边缘接入采用多跳Ad hoc技术,主干接入采用分层移动IPv6技术。多跳Ad hoc网络大大增加了网络的覆盖范围,减轻了网络铺设成本,且支持宽带接入;分层移动IPv6降低了域内切换的信令开销和时延。同时,对现有的分层移动IPv6协议进行扩展,实现了主干网络与边缘多跳网络的有机结合。移动用户不但能以较低的信令开销实现全局的IP漫游,还能保证进入同一MANET网络中的移动节点直接通信,减轻了主干网络的传输负担,也保证了突发情况下节点能通过边缘MANET网络保持链路畅通。  相似文献   
22.
Results of analysis of investigations of welded joints produced in welding low-alloy high-strength 07G2NDMFBT steel at linear energies up to 6 kJ/mm show that the proposed combinations of welding materials and the technology of multi-arc submerged-arc welding result in high hot-cracking resistance and high properties of the weld metal. However, regardless of the high cold-cracking resistance of the steel, in welding at high heat inputs there is a considerable degradation of the structure and the toughness of the metal in the coarse-grained region of the heat-affected zone decreases under the effect of the welding thermal cycle. Consequently, it is concluded that the weldability of this steel is limited and it is therefore necessary to apply restrictions in the practical application of the processes with high heat input.  相似文献   
23.
In the process of creating a multimodal map of space, auditory-visual neurons in the optic tectum establish associations between particular values of auditory spatial cues and locations in the visual field. In the barn owl, tectal neurons reveal these associations in the match between their tuning for interaural time differences (ITDs) and the locations of their visual receptive fields (VRFs). In young owls ITD-VRF associations can be adjusted by experience over a wide range, but the range of adjustment normally becomes quite restricted in adults. This normal range of adjustment in adults was greatly expanded in owls that had previously learned abnormal ITD-VRF associations as juveniles. Thus, the act of learning abnormal associations early in life leaves an enduring trace in this pathway that enables unusual functional connections to be reestablished, as needed, in adulthood, even when the associations represented by these connections have not been used for an extended period of time.  相似文献   
24.
Supplementation of children diet with food enriched by vitamins, antioxidants and dietary fiber food (beverage 'Zolotoy shar', bread with addition of bran, 'doctorskije' rolls inhibited or normalized the lipid peroxidation of cell membranes, methemoglobin production and increased some indices of humoral immunity. The results allow to recommend the studied special food for prophylactic use for children dietary intake in regions of ecological pollution.  相似文献   
25.
The psychopathology and associated disabilities experienced by persons with schizophrenia have only partially responded to conventional pharmacological and psychosocial treatment approaches. Biobehavioral treatment and rehabilitation employs behavioral assessment, social learning principles, skills training, and a focus on the recovery process to amplify the effects of pharmacotherapy. Utilizing the Medline database, we review a selection of English-language studies published from 1970 to 1994 that support the effectiveness of each of the components of biobehavioral therapy, such as case management, psychopharmacology with behavioral assessment, psychoeducation, family involvement, and social skills training. An integrated biobehavioral therapy directed toward early detection and treatment of schizophrenic symptoms, collaboration between consumers and caregivers in managing treatment, family and social skills training, and teaching coping skills and self-help techniques has been documented to improve the course and outcome of schizophrenia, as measured by symptom recurrence, social functioning, and quality of life. A case vignette is presented to illustrate the successful integration of biobehavioral therapies into a treatment system that focuses on consumers' attempts to become increasingly responsible for recovering from illness.  相似文献   
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PURPOSE: To determine the impact of treatment toxicity on long-term survival in pediatric Hodgkin's disease. PATIENTS AND METHODS: We studied late events in 387 patients treated for pediatric Hodgkin's disease on four consecutive clinical trials at St Jude Children's Research Hospital from 1968 to 1990. Relative risks, actuarial risks, and absolute excess risks for cause-specific deaths were calculated. RESULTS: As of April 1997, 316 (82%) of patients were alive, with a median follow-up of 15.1 (range, 2.9 to 28.6) years. In this cohort, which represented 5,623 person-years of follow-up, 71 fatal events resulted from Hodgkin's disease (n=36), second malignancies (n=14), infections (n=7), accidents (n=7), cardiac disease (n=6), and asphyxiation (n=1). The 5-year estimated event-free survival (EFS) for the entire cohort was 79.6%+/-2.1 %, which declined to 63.1%+/-4.4% by 20 years. Cumulative incidences of cause-specific deaths at 25 years were 9.8%+/-1.6% for Hodgkin's disease, 8.1%+/-2.6% for second malignancy, 4.0%+/-1.8% for cardiac disease, 3.9%+/-1.5% for infection, and 2.1%+/-0.8% for accidents. Standardized incidence ratios showed excess risk for all second malignancies (12; 95% confidence interval [CI], 8 to 17), acute myeloid leukemia (81; 95% CI, 16 to 237), solid tumors (11; 95% CI, 7 to 16), and breast cancer (33; 95% CI, 12 to 72). Standardized mortality ratios also showed excess mortality from cardiac disease (22; 95% CI, 8 to 48) and infection (18; 95% CI, 7 to 38). CONCLUSION: Compared with age- and sex-matched control populations, survivors of pediatric Hodgkin's disease who were treated before 1990 face an increased risk of early mortality related to second cancers, cardiac disease, and infection.  相似文献   
29.
Hemifacial spasm (HFS), generally a disease of the elderly, is caused by vascular compression of the seventh nerve. Vascular compression is thought to result from atherosclerotic changes within the vessels of the posterior fossa, and therefore rarely presents in childhood. Here we describe our experience with 12 patients with onset of HFS during childhood (age 18 or less) and who had surgical exploration of the cerebellopontine angle. These patients represent less than 1.2% of the patient population with HFS operated upon at this institution during the study period. Nine patients had follow-up data extending over 83 months. All 12 patients were found to have microvascular compression of the seventh nerve at the time of surgery. The most common operative finding was compression of the seventh nerve by a vein, alone or in combination with a branch of the anterior inferior cerebellar artery. At the time of discharge and after a mean follow-up period of 125 months, microvascular decompression resulted in complete relief of spasm in 67% of the patients.  相似文献   
30.
The distribution of dopamine (DA)-containing cell bodies, fibers, and terminals in the brain and spinal cord of Lampetra fluviatilis was investigated by immunohistochemical means. In order to distinguish dopaminergic neurons from those using other catecholamines as the primary neurotransmitter, the distribution of dopamine-immunoreactive structures was compared to that of cell bodies, fibers, and terminals labelled with antibodies directed against the enzymes tyrosine hydroxylase (TH), aromatic L-amino acid decarboxylase (AADC), dopamine beta-hydroxylase (DBH), and phenylethanolamine-N-methyl transferase (PNMT). We define dopaminergic neurons as those that are simultaneously DA, TH, and AADC immunoreactive and at the same time DBH and PNMT nonreactive. The overall concentrations of dopamine, noradrenaline, and adrenaline and some of their metabolites were also measured via high-performance liquid chromatography of whole-brain extracts. Our results revealed the presence of 10 populations of dopaminergic neurons in the brain of the lamprey in the olfactory bulb, preoptic area, hypothalamus, rhombencephalon, and spinal cord. In addition, uniquely DA-immunoreactive neurons, in contact with the cerebrospinal fluid, were observed in the hypothalamus and spinal cord. Chromatography indicated that dopamine exists in considerably higher concentrations than noradrenaline in the lamprey brain, whereas adrenaline is absent, the latter finding being supported by our failure to observe any PNMT-immunoreactive cell bodies, fibers, or terminals. The dopaminergic system of the lamprey appears to share many features not only with that of other anamniotes but also with that of amniotes; however, as in teleosts, dopaminergic neurons in the midbrain corresponding to the substantia nigra, the retrorubral area, and the ventral tegmental area of other species do not exist in the lamprey.  相似文献   
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